Supplemental Prospectus (Form 424B5)

Filed Pursuant to Rule 424(b)(5)

Registration No. 333-285327

PROSPECTUS SUPPLEMENT

(To Prospectus Dated May 13, 2025)

9,293,078 Shares of Common Stock

Common Warrants to Purchase 9,293,078 Shares of Common Stock

(and the 9,293,078 shares of Common Stock underlying the Common Warrants)

Placement Agent Warrants to Purchase 464,654 Shares of Common Stock

(and the 464,654 shares of Common Stock underlying the Placement Agent Warrants)

We are offering 8,571,429 shares of our common stock, $0.0001 par value per share, together with accompanying warrants (the "Common Warrants") to purchase up to 8,571,429 shares of common stock (the "Common Warrant Shares"), pursuant to this prospectus supplement and the accompanying prospectus to several institutional investors. The purchase price of each share of common stock and accompanying Common Warrant to the purchasers identified in the securities purchase agreement dated July 14, 2026, by and among us and the purchasers listed on the signature pages thereto (the "SPA") is $1.05 per share and accompanying Common Warrant.

We are also offering 721,649 shares of our common stock, (the "Insider Shares"), together with 721,649 Common Warrants, pursuant to this prospectus supplement and the accompanying prospectus to certain of the Company's officers and directors. The purchase price of each share of common stock and accompanying Common Warrant to the purchasers identified in the securities purchase agreement dated July 14, 2026, by and among us and the insider purchasers listed on the signature pages thereto (the "Insiders") is $1.455 per share and accompanying Common Warrant.

The Common Warrants will have an exercise price of $1.31 per share ($1.33 for the Insiders), will be exercisable beginning on the later of (i) six months after issuance or (ii) the Authorized Share Increase Date (as defined below) (the "Initial Exercise Date") and will have a term of exercise equal to five and one-half years after the Initial Exercise Date. "Authorized Share Increase Date" means the date on which an amendment to our certificate of incorporation increasing the number of authorized shares of our common stock to an amount sufficient for the exercise in full of the Common Warrants is filed with and accepted by the State of Delaware, subject to approval of such amendment by our stockholders. We have agreed to file a proxy statement on or prior to the date that is forty-five (45) days following the closing of this offering for the purpose of obtaining such stockholder approval, and if we do not obtain such approval at the first meeting, to call a meeting every sixty (60) days thereafter until such approval is obtained or the Common Warrants are no longer outstanding.

Our common stock is traded on The Nasdaq Capital Market under the symbol "CRDF." On July 14, 2026, the last sale price of our common stock as reported on The Nasdaq Capital Market was $1.31 per share. There is no established public trading market for the Common Warrants and we do not expect a market to develop. In addition, we do not intend to apply for a listing of the Common Warrants on any national securities exchange or other nationally recognized trading system.

We have retained H.C. Wainwright & Co., LLC to act as our exclusive placement agent (the "Placement Agent") in connection with this offering. The Placement Agent is not purchasing or selling any of the securities offered pursuant to this prospectus supplement and the accompanying prospectus and the Placement Agent is not required to arrange the purchase or sale of any specific number of securities or dollar amount and has agreed to use its reasonable best efforts to sell the securities offered by this prospectus supplement and the accompanying prospectus. We have agreed to pay the Placement Agent certain cash fees set forth in the table below, which assumes that we sell all of the shares of common stock and warrants we are offering pursuant to this prospectus supplement and the accompanying prospectus. See "Plan of Distribution" beginning on page S-14 of this prospectus supplement for additional information with respect to the compensation we will pay the Placement Agent.

Investing in our common stock involves a high degree of risk. See "Risk Factors" beginning on page S-5 of this prospectus supplement, on page 11 of the accompanying prospectus and in the documents incorporated by reference into this prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

Delivery of the shares of common stock and warrants offered hereby is expected to be made on or about July 16, 2026, subject to satisfaction of certain customary closing conditions.

H.C. Wainwright & Co.

The date of this prospectus supplement is July 14, 2026

TABLE OF CONTENTS

PROSPECTUS SUPPLEMENT

PROSPECTUS

ABOUT THIS PROSPECTUS SUPPLEMENT

This prospectus supplement and the accompanying prospectus are part of a registration statement that we filed with the U.S. Securities and Exchange Commission utilizing a "shelf" registration process. This document is in two parts. The first part is this prospectus supplement, which describes the specific terms of this offering and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference herein. The second part, the accompanying prospectus, provides more general information. Generally, when we refer to this prospectus, we are referring to both parts of this document combined. To the extent there is a conflict between the information contained in this prospectus supplement and the information contained in the accompanying prospectus or any document incorporated by reference therein filed prior to the date of this prospectus supplement, you should rely on the information in this prospectus supplement; provided that if any statement in one of these documents is inconsistent with a statement in another document having a later date-for example, a document incorporated by reference in the accompanying prospectus-the statement in the document having the later date modifies or supersedes the earlier statement.

We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference herein were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

You should rely only on the information contained in this prospectus supplement or the accompanying prospectus, or incorporated by reference herein. We have not authorized, and the Placement Agent has not authorized, anyone to provide you with information that is different. The information contained in this prospectus supplement or the accompanying prospectus, or incorporated by reference herein or therein is accurate only as of the respective dates thereof, regardless of the time of delivery of this prospectus supplement and the accompanying prospectus or of any sale of our securities. It is important for you to read and consider all information contained in this prospectus supplement and the accompanying prospectus, including the documents incorporated by reference herein and therein, in making your investment decision. You should also read and consider the information in the documents to which we have referred you in the sections entitled "Where You Can Find More Information" and "Incorporation of Documents By Reference" in this prospectus supplement and in the accompanying prospectus, respectively.

We are offering to sell, and seeking offers to buy, the securities offered by this prospectus supplement only in jurisdictions where offers and sales are permitted. The distribution of this prospectus supplement and the accompanying prospectus and the offering of the securities offered by this prospectus supplement in certain jurisdictions may be restricted by law. Persons outside the United States who come into possession of this prospectus supplement and the accompanying prospectus must inform themselves about, and observe any restrictions relating to, the offering of the securities and the distribution of this prospectus supplement and the accompanying prospectus outside the United States. This prospectus supplement and the accompanying prospectus do not constitute, and may not be used in connection with, an offer to sell, or a solicitation of an offer to buy, any securities offered by this prospectus supplement and the accompanying prospectus by any person in any jurisdiction in which it is unlawful for such person to make such an offer or solicitation.

All references in this prospectus supplement and the accompanying prospectus to "Cardiff," the "Company," "we," "us," "our," or similar terms refer to Cardiff Oncology, Inc. and its subsidiary taken as a whole, except where the context otherwise requires or as otherwise indicated.

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PROSPECTUS SUPPLEMENT SUMMARY

This summary highlights selected information about us, this offering and information appearing elsewhere in this prospectus supplement, in the accompanying prospectus and in the documents incorporated by reference herein and therein. This summary is not complete and does not contain all the information you should consider before investing in our securities pursuant to this prospectus supplement and the accompanying prospectus. Before making an investment decision, to fully understand this offering and its consequences to you, you should carefully read this entire prospectus supplement and the accompanying prospectus, including "Risk Factors," the financial statements, and related notes, and the other information incorporated by reference herein and therein.

Overview

We are a clinical-stage biotechnology company advancing innovative cancer treatments focused on PLK1 inhibition, a validated oncology drug target with practice-changing potential. Our lead asset, onvansertib, is a highly specific, oral PLK1 inhibitor currently being evaluated in a Phase 2 trial for first-line treatment of RAS-mutated metastatic colorectal cancer ("mCRC"), addressing a large, underserved patient population with high unmet need. Onvansertib is also under investigation in other PLK1-driven cancers through investigator-initiated trials such as metastatic pancreatic ductal adenocarcinoma ("mPDAC"), small cell lung cancer ("SCLC"), and metastatic triple negative breast cancer ("mTNBC"). Additionally, onvansertib has also shown robust single agent activity in an investigator-initiated trial in chronic myelomonocytic leukemia ("CMML"). These programs and our broader development strategy are designed to target tumor vulnerabilities in order to overcome treatment resistance and deliver improved clinical outcomes in patients. Our clinical development programs incorporate tumor genomics and biomarker assays to refine patient selection and assessment of patient response to treatment.

Our Lead Drug Candidate, Onvansertib

We believe the attributes of onvansertib and its early clinical evidence of favorable safety and efficacy, with expected on-target, manageable and tolerable side effects, may prove beneficial in addressing clinical therapeutic needs across a variety of cancers. Key attributes of onvansertib include:

In vitro studies have shown synergistic effects when onvansertib was administered in combination with different cytotoxic agents including microtubule-targeting agents, topoisomerase 1 inhibitors, antimetabolites, alkylating agents, proteasome inhibitors, kinase inhibitors, PARP inhibitors, BCL-2 inhibitors, and androgen biosynthesis inhibitors.

In addition, in vivo combination studies have confirmed the positive results obtained in vitro and additive or synergistic effects on efficacy have been observed in xenograft models of onvansertib in combination with irinotecan, 5-fluorouracil ("5-FU"), abiraterone, PARP inhibitors, venetoclax, paclitaxel, or bevacizumab. Combining onvansertib with standard of care ("SoC") cancer agents may provide opportunities for synergy with many cancer therapies.

There are several ongoing clinical trials of onvansertib in multiple indications: one trial (CRDF-004) in first-line treatment in patients with RAS-mutated mCRC, and investigator-initiated trials in first-line mPDAC, first-line CMML as monotherapy, second-line relapsed SCLC as monotherapy, and second-line unresectable locally advanced or metastatic TNBC.

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RISK FACTORS

An investment in our securities involves a high degree of risk. Before deciding whether to invest in our securities, you should consider carefully the risks described below, together with other information in this prospectus supplement, the accompanying prospectus and the information and documents incorporated by reference. You should also consider the risks, uncertainties and assumptions discussed under the heading "Risk Factors" included in our most recent Annual Report on Form 10-K and the subsequent reports that we file with the SEC which are on file with the SEC and are incorporated herein by reference, and which may be amended, supplemented or superseded from time to time by other reports we file with the SEC in the future. If any of these risks actually occur, our business, financial condition, results of operations or cash flow could be adversely effected. This could cause the trading price of our common stock to decline, resulting in a loss of all or part of your investment. The risks and uncertainties described below are not the only ones facing us. Additional risks and uncertainties not presently known to us, or that we currently see as immaterial, may also harm our business. Please also read carefully the section below entitled "Special Note Regarding Forward-Looking Statements."

Risks Related to This Offering and Our Common Stock

Our management team may invest or spend the proceeds raised in this offering in ways with which you may not agree or which may not yield a significant return.

Our management will have broad discretion over the use of proceeds from this offering and could spend the proceeds in ways that do not improve our results of operations or enhance the value of our common stock. The failure by management to apply these funds effectively could result in financial losses that could have a material adverse effect on our business, cause the price of our common stock to decline, and delay the development of our product candidates.

You will experience substantial dilution.

Based on an effective offering price of $1.08 per share, and a net tangible book value of $34.7 million, or approximately $0.51 per share of common stock, as of March 31, 2026, if you purchase securities in this offering, you will experience dilution of approximately $0.52 per share in the net tangible book value of the common stock you purchase representing the difference between our as adjusted net tangible book value per share after giving effect to this offering and the offering price per share of common stock. The exercise of outstanding stock options and warrants, including those sold in this offering, will result in further dilution of your investment.

If you purchase securities in this offering, you may also experience future dilution as a result of future equity offerings.

We expect that significant additional capital will be needed in the future to continue our planned operations, including research and development, increased marketing, hiring new personnel, commercializing our products, and continuing activities as an operating public company. To the extent we raise additional capital by issuing equity securities, our shareholders may experience substantial dilution. We may sell common stock, convertible securities or other equity securities in one or more transactions at prices and in a manner we determine from time to time. If we sell common stock, convertible securities or other equity securities in more than one transaction, investors may be materially diluted by subsequent sales. Such sales may also result in material dilution to our existing shareholders, and new investors could gain rights superior to our existing shareholders.

We do not intend to pay cash dividends on our shares of common stock so any returns will be limited to the value of our shares.

We have never paid or declared any cash dividends on our common stock, and we do not anticipate paying any cash dividends on our common stock in the foreseeable future. We currently anticipate that we will retain future earnings for the development, operation and expansion of our business. Any future determination to pay dividends will be at the discretion of our board of directors and will depend upon a number of factors, including our results of operations, financial condition, future prospects, contractual restrictions, restrictions imposed by applicable law and other factors that our board of directors deems relevant. Therefore, any return to shareholders will be limited to the increase, if any, of our share price

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Holders of Common Warrants purchased in this offering will have no rights as holders of shares of our Common Stock until such holders exercise their Common Warrants to acquire shares of our Common Stock.

Until holders of the Common Warrants acquire shares of our Common Stock upon exercise of such Common Warrants, the holders will have no rights with respect to the Common Stock underlying such Common Warrants, such as voting rights or the rights to receive dividends. Upon exercise of the Common Warrants, the holders will be entitled to exercise the rights of a stockholder only as to matters for which the record date occurs after the exercise.

Significant holders or beneficial holders of our Common Stock may not be permitted to exercise Common Warrants that they hold.

Holders of the Common Warrants will not be entitled to exercise any portion of any Common Warrant which, upon giving effect to such exercise, would cause the aggregate number of shares of Common Stock beneficially owned by the holder (together with its affiliates) to exceed 4.99% (or 9.99%) of the number of shares of Common Stock outstanding immediately after giving effect to the exercise, as such percentage ownership is determined in accordance with the terms of the Common Warrant. As a result, you may not be able to exercise your Common Warrant for shares of our Common Stock at a time when it would be financially beneficial for you to do so. In such circumstances, you could seek to sell your Common Warrants to realize value, but you may be unable to do so in the absence of an established trading market for the Common Warrants.

We are currently listed on The Nasdaq Capital Market. If we are unable to maintain listing of our securities on Nasdaq or any stock exchange, our stock price could be adversely affected and the liquidity of our stock and our ability to obtain financing could be impaired and it may be more difficult for our shareholders to sell their securities.

Although our common stock is currently listed on The Nasdaq Capital Market, we may not be able to continue to meet the exchange's minimum listing requirements or those of any other national exchange. The Listing Rules of Nasdaq require listing issuers to comply with certain standards in order to remain listed on its exchange. If, for any reason, we should fail to maintain compliance with these listing standards and Nasdaq should delist our securities from trading on its exchange and we are unable to obtain listing on another national securities exchange, a reduction in some or all of the following may occur, each of which could have a material adverse effect on our shareholders:

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement and the documents incorporated by reference herein contain forward-looking statements that are based on current management expectations. Statements other than statements of historical fact included in this prospectus supplement, including statements about us and the future growth and anticipated operating results and cash expenditures, are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 ("Securities Act"), as amended, and Section 21E of the Securities Exchange Act of 1934, as amended ("Exchange Act"). When used in this prospectus supplement the words "anticipate," "objective," "may," "might," "should," "could," "can," "intend," "expect," "believe," "estimate," "predict," "potential," "plan" or the negative of these and similar expressions identify forward-looking statements. These statements reflect our current views with respect to uncertain future events and are based on imprecise estimates and assumptions and subject to risk and uncertainties. Given these uncertainties, you should not place undue reliance on these forward-looking statements. While we believe our plans, intentions and expectations reflected in those forward-looking statements are reasonable, these plans, intentions or expectations may not be achieved. Our actual results, performance or achievements could differ materially from those contemplated, expressed or implied by the forward-looking statements contained in, or incorporated by reference into, this prospectus supplement for a variety of reasons.

We urge investors to review carefully risks contained in the section of this prospectus entitled "Risk Factors" above as well as other risks and factors identified from time to time in our SEC filings in evaluating the forward-looking statements contained in this prospectus supplement. We caution investors not to place significant reliance on forward-looking statements contained in this document; such statements need to be evaluated in light of all the information contained herein.

All forward-looking statements attributable to us or persons acting on our behalf are expressly qualified in their entirety by the risk factors and other cautionary statements set forth, or incorporated by reference, in this prospectus supplement. Except as required by law, we are under no obligation, and we do not intend, to update any forward-looking statement, whether as result of new information, future events or otherwise.

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DIVIDEND POLICY

We have never paid or declared any cash dividends on our common stock, and we do not anticipate paying any cash dividends on our common stock in the foreseeable future. We intend to retain all available funds and any future earnings to fund the development and expansion of our business. Any future determination to pay dividends will be at the discretion of our board of directors and will depend upon a number of factors, including our results of operations, financial condition, future prospects, contractual restrictions, restrictions imposed by applicable law and other factors that our board of directors deems relevant.

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DILUTION

If you purchase securities in the offering, you will experience immediate dilution to the extent of the difference between the effective offering price per share of $1.08 per share of common stock and accompanying Common Warrant and our as adjusted net tangible book value per share immediately after the offering. Net tangible book value per share is equal to the amount of our total tangible assets, less total liabilities, divided by the number of outstanding shares of our common stock. As of March 31, 2026, our net tangible book value was approximately $34.7 million, or approximately $0.51 per share.

Based on the sale by us in this offering of 9,293,078 shares of common stock and accompanying Common Warrants at an offering price of $1.08 per share and accompanying Common Warrants, after deducting estimated offering expenses and placement agent fees and expenses payable by us, our as adjusted net tangible book value as of March 31, 2026 was approximately $43.8 million, or $0.56 per share of our common stock. This represents an immediate increase in as adjusted net tangible book value to existing stockholders of $0.05 per share of our common stock and an immediate dilution to purchasers in this offering of $0.52 per share of our common stock.

The following table illustrates this per-share of our common stock dilution:

* Blended price of 8,571,429 shares of common stock at $1.05 for non-insiders and 721,649 shares of common stock at $1.455 for insiders.

To the extent that outstanding exercisable options or warrants are exercised, you may experience further dilution. In addition, we may need to raise additional capital and to the extent that we raise additional capital by issuing equity or convertible debt securities your ownership will be further diluted.

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USE OF PROCEEDS

We expect to receive net proceeds from this offering of approximately $9.1 million, after deducting the Placement Agent fees and estimated offering expenses payable by us.

We currently intend to use the net proceeds from the sale of the securities offered hereby for general corporate and working capital purposes. This expected use of net proceeds from this offering and our existing cash represents our intentions based upon our current plans and business conditions, which could change in the future as our plans and business conditions evolve. The amounts and timing of our actual expenditures may vary significantly depending on numerous factors. As a result, our management will retain broad discretion over the allocation of the net proceeds from this offering.

As of the date of this prospectus supplement, we cannot predict with certainty all the uses for the net proceeds to be received upon the completion of this offering or the amounts we will spend on the uses set forth above.

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DESCRIPTION OF SECURITIES WE ARE OFFERING

We are offering shares of common stock. The following description of our shares of common stock summarizes the material terms of the shares of common stock we are offering under this prospectus supplement and the accompanying prospectus.

Common Stock

For a description of the rights associated with the common stock, see "Description of Capital Stock" in the accompanying prospectus. Our common stock is listed on The Nasdaq Capital Market under the symbol "CRDF." Our transfer agent is Pacific Stock Transfer Company, Inc.

Common Warrants

The following summary of certain terms and provisions of the Common Warrants is not complete and is subject to, and qualified in its entirety by, the provisions of the form of Common Warrant, which is filed as an exhibit to the Current Report on Form 8-K that we will file with the SEC in connection with this offering. Prospective investors should carefully review the terms and provisions of the form of Common Warrant for a complete description of the terms and conditions of the Common Warrants.

The Common Warrants will be issued in certificated form pursuant to the securities purchase agreement dated July 14, 2026. The exercise price per share of Common Stock under each Common Warrant will be $1.31 per share ($1.33 for Insiders), subject to adjustment as described below.

Exercisability

The Common Warrants will be exercisable on and after the later of (i) the date that is six months from the date of issuance and (ii) the Authorized Share Increase Date (the "Initial Exercise Date") and on or prior to 5:00 p.m. (New York City time) on the date that is the five and one-half anniversary of the Initial Exercise Date, provided that, if such date is not a Trading Day, then the date that is the immediately following Trading Day (the "Termination Date").

Cashless Exercise

If at the time of exercise of a Common Warrant there is no effective registration statement registering, or the prospectus contained therein is not available for, the issuance of the Warrant Shares to the Holder, then the Common Warrant may also be exercised, in whole or in part, at such time by means of a "cashless exercise" in which the Holder shall be entitled to receive a number of Warrant Shares equal to the quotient obtained by dividing [(A-B)(X)] by (A), where (A) equals, as applicable, (i) the VWAP on the Trading Day immediately preceding the date of the applicable Notice of Exercise if such Notice of Exercise is delivered on a day that is not a Trading Day or prior to the opening of "regular trading hours" on such Trading Day, (ii) the highest Bid Price of the Common Stock on the principal Trading Market as reported by Bloomberg within two (2) hours of the time of the Holder's delivery of the Notice of Exercise if such Notice of Exercise is delivered during "regular trading hours," or within two (2) hours after the close of "regular trading hours" on a Trading Day, or (iii) the VWAP on the date of the applicable Notice of Exercise if the date of such Notice of Exercise is a Trading Day and such Notice of Exercise is delivered after two (2) hours following the close of "regular trading hours" on such Trading Day; (B) equals the Exercise Price, as adjusted; and (X) equals the number of Warrant Shares that would be issuable upon exercise of the Common Warrant if such exercise were by means of a cash exercise rather than a cashless exercise. If Warrant Shares are issued in such a cashless exercise, the Warrant Shares shall take on the registered characteristics of the Warrants being exercised in accordance with Section 3(a)(9) of the Securities Act.

Delivery of Common Warrant Shares

The Company shall cause the Warrant Shares purchased upon exercise of a Common Warrant to be transmitted by the Transfer Agent to the Holder by crediting the account of the Holder's or its designee's balance account with The Depository Trust Company through its Deposit or Withdrawal at Custodian system ("DWAC") if the Company is then a participant in such system and either (A) there is an effective registration statement permitting the issuance of the Warrant Shares to or resale of the Warrant Shares by the Holder, or (B) the Common Warrant is being exercised via cashless exercise, and otherwise by physical delivery of a

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certificate, registered in the Company's share register in the name of the Holder or its designee, for the number of Warrant Shares to which the Holder is entitled, by the date that is the earlier of (i) one (1) Trading Day after the delivery of the Notice of Exercise and (ii) the number of Trading Days comprising the Standard Settlement Period after the delivery of the Notice of Exercise (the "Warrant Share Delivery Date").

Transferability

The Common Warrants and all rights thereunder are transferable, in whole or in part, upon surrender of the Common Warrant at the principal office of the Company or its designated agent, together with a written assignment in the form attached to the Common Warrant duly executed by the Holder or its agent or attorney and funds sufficient to pay any transfer taxes payable upon the making of such transfer. Upon such surrender and, if required, such payment, the Company shall execute and deliver a new Warrant or Warrants in the name of the assignee or assignees, as applicable, and in the denomination or denominations specified in such instrument of assignment, and shall issue to the assignor a new Warrant evidencing the portion of the Common Warrant not so assigned.

Fractional Shares

No fractional shares or script representing fractional shares shall be issued upon the exercise of the Common Warrants. As to any fraction of a share which the Holder would otherwise be entitled to purchase upon such exercise, the Company shall, at its election, either pay a cash adjustment in respect of such final fraction in an amount equal to such fraction multiplied by the Exercise Price or round up to the next whole share.

Trading Market

The Common Warrants are not and will not be listed for trading on any national securities exchange or other nationally recognized trading system. There is no established public trading market for the Common Warrants and we do not expect a market to develop.

Fundamental Transaction

If, at any time while a Common Warrant is outstanding, (i) the Company, directly or indirectly, in one or more related transactions, effects any merger or consolidation of the Company with or into another person, (ii) the Company (or any subsidiary), directly or indirectly, effects any sale, lease, license, assignment, transfer, conveyance or other disposition of all or substantially all of its assets in one or a series of related transactions, (iii) any direct or indirect purchase offer, tender offer or exchange offer is completed pursuant to which holders of Common Stock are permitted to sell, tender or exchange their shares for other securities, cash or property and has been accepted by the holders of greater than 50% of the outstanding Common Stock or greater than 50% of the voting power of the common equity of the Company, (iv) the Company, directly or indirectly, in one or more related transactions, effects any reclassification, reorganization or recapitalization of the Common Stock or any compulsory share exchange pursuant to which the Common Stock is effectively converted into or exchanged for other securities, cash or property, or (v) the Company, directly or indirectly, in one or more related transactions, consummates a stock or share purchase agreement or other business combination with another person or group of persons whereby such other person or group acquires greater than 50% of the outstanding shares of Common Stock or greater than 50% of the voting power of the common equity of the Company (each, a "Fundamental Transaction"), then, upon any subsequent exercise of the Common Warrant, the Holder shall have the right to receive, for each Warrant Share that would have been issuable upon such exercise immediately prior to the occurrence of such Fundamental Transaction, at the option of the Holder (without regard to the Beneficial Ownership Limitation), the number of shares of Common Stock of the successor or acquiring corporation, or of the Company if it is the surviving corporation, and any additional consideration (the "Alternate Consideration") receivable as a result of such Fundamental Transaction by a holder of the number of shares of Common Stock for which the Common Warrant is exercisable immediately prior to such Fundamental Transaction. If holders of Common Stock are given any choice as to the securities, cash or property to be received in a Fundamental Transaction, then the Holder shall be given the same choice as to the Alternate Consideration it receives upon any exercise of the Common Warrant following such Fundamental Transaction. Additionally, as more fully described in the Common Warrants, in the event of certain fundamental transactions, the holders of the Common Warrants will be entitled to receive consideration in an amount equal to the Black Scholes value of Common Warrants on the date of consummation of such transaction.

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Rights as a Stockholder

The Common Warrants do not entitle the Holder to any voting rights, dividends or other rights as a stockholder of the Company prior to the exercise thereof, except as expressly set forth in the adjustment provisions described above. In no event shall the Company be required to net cash settle an exercise of a Common Warrant.

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PLAN OF DISTRIBUTION

Pursuant to an engagement letter agreement, dated as of July 1, 2026, we have engaged H.C. Wainwright & Co., LLC (the "Placement Agent") to act as our exclusive placement agent in connection with this offering. Under the terms of the engagement letter agreement, the Placement Agent has agreed to act as our exclusive placement agent, on a reasonable best efforts basis, in connection with the issuance and sale of the securities offered pursuant to this prospectus supplement and the accompanying prospectus. Therefore, we may not sell the entire amount of securities being offered. The terms of this offering were subject to market conditions and negotiations between us, the Placement Agent and prospective investors. The engagement letter agreement does not give rise to any commitment by the Placement Agent to purchase or sell any of our securities, and the Placement Agent will have no authority to bind us by virtue of the engagement letter agreement. The Placement Agent may retain other brokers, dealers or agents on its behalf in connection with this offering.

The Placement Agent proposes to arrange for the sale of shares of our common stock and accompanying Common Warrants to purchase shares of our common stock, which are being offered on a registered basis pursuant to this prospectus supplement and the accompanying prospectus.

Pursuant to the terms of the securities purchase agreement and subject to certain exceptions, we are prohibited from entering into any agreement to issue or announcing the issuance or proposed issuance of any shares of common stock or securities convertible or exercisable into common stock for a period commencing on the date of this prospectus supplement and expiring 60 days from the closing date of this offering. Additionally, our directors and executive officers have entered into lock-up agreements. Under these agreements, these individuals have agreed, subject to specified exceptions, not to sell or transfer any shares of common stock or securities convertible into, or exchangeable or exercisable for, our common stock during a period ending 60 days after the closing date of this offering. Specifically, these individuals have agreed, in part, not to:

Furthermore, from the date of the securities purchase agreement until ninety (90) days after the closing date of this offering, we are prohibited from effecting or entering into an agreement to effect any issuance of shares of our common stock or common stock equivalents involving a Variable Rate Transaction, as defined in the securities purchase agreement, which includes, among other things, any equity line of credit or "at-the-market offering."

We have agreed to pay the Placement Agent a cash fee equal to 7.0% of the aggregate gross proceeds of this offering. We will also pay the Placement Agent $35,000 for non-accountable expenses, up to $50,000 for fees and expenses of its legal counsel and other out-of-pocket expenses, and closing costs not to exceed $15,950, which includes reimbursement of the out-of-pocket cost of the clearing agent. We estimate the total offering expenses of this offering that will be payable by us, excluding the cash fee payable to the Placement Agent but including all other Placement Agent fees and expenses, will be approximately $127,000.

In addition, we have agreed to issue to the Placement Agent, or its designees, warrants (the "Placement Agent Warrants") to purchase up to a number of shares of our common stock equal to 5.0% of the aggregate number of shares of our common stock (or common stock equivalents) purchased in this offering. The Placement Agent Warrants shall have the same terms as the Common Warrants issued to investors in this offering, except that the Placement Agent Warrants shall have an exercise price per share equal to $1.3125 per share, representing 125% of the offering price per share in this offering and the Placement Agent Warrants will have a term of five (5) years from the commencement of sales pursuant to this offering. The Placement Agent Warrants and the shares of common stock issuable upon exercise of the Placement Agent Warrants are registered pursuant to this prospectus supplement and the accompanying prospectus.

We have granted the Placement Agent a right of first refusal, for a period of six (6) months from the consummation of this offering (subject to FINRA Rule 5110(g)(6)(A)), to act as our sole book-running manager, sole underwriter or sole placement agent for

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any future debt financing or refinancing or capital raising transaction of equity, equity-linked or debt securities that we or any of our subsidiaries decide to pursue, subject to certain exceptions.

We have also agreed to pay the Placement Agent a tail cash fee equal to 7.0% of the gross proceeds and to issue Placement Agent Warrants covering 5.0% of the aggregate number of shares of securities sold in any offering consummated within the 12-month period following the termination or expiration of the engagement letter agreement, to the extent that any capital in such financing is provided by investors whom the Placement Agent had "wall crossed" during the term of the engagement letter, with all such investors being identified in writing by the Placement Agent and sent to us as soon as reasonably practicable after the closing of this offering or the expiration or termination of the engagement letter, as applicable.

We have agreed to indemnify the Placement Agent and specified other persons against certain liabilities relating to or arising out of the Placement Agent's activities under the engagement letter agreement, including liabilities under the Securities Act, and to contribute to payments that the Placement Agent may be required to make in respect of such liabilities.

The Placement Agent may be deemed to be an underwriter within the meaning of Section 2(a)(11) of the Securities Act, and any commissions received by it and any profit realized on the resale of the securities sold by it while acting as principal might be deemed to be underwriting discounts or commissions under the Securities Act. As an underwriter, the Placement Agent would be required to comply with the requirements of the Securities Act and the Exchange Act, including, without limitation, Rule 415(a)(4) under the Securities Act and Rule 10b-5 and Regulation M under the Exchange Act. These rules and regulations may limit the timing of purchases and sales of securities by Wainwright acting as principal. Under these rules and regulations, the Placement Agent:

The Placement Agent has provided and may in the future provide various advisory, investment and commercial banking and other services to us in the ordinary course of business, for which it has received and may continue to receive customary fees and commissions.

However, except as disclosed in this prospectus supplement, we have no present arrangements with the Placement Agent for any further services.

Our common stock is listed on The Nasdaq Capital Market under the symbol "CRDF."

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LEGAL MATTERS

The validity of the shares of our common stock offered hereby will be passed upon for us by Sheppard, Mullin, Richter & Hampton LLP, New York, New York. Ellenoff Grossman & Schole LLP, New York, New York is counsel to the placement agent in connection with this offering.

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EXPERTS

Our consolidated financial statements as of and for the years ended December 31, 2025 and 2024, incorporated by reference in this prospectus supplement, have been audited by BDO USA, P.C., independent registered public accounting firm, as set forth in their report thereon incorporated by reference herein, and are included in reliance on such report given on the authority of such firm as experts in accounting and auditing. The report on the consolidated financial statements contains an explanatory paragraph regarding the Company's ability to continue as a going concern.

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WHERE YOU CAN FIND MORE INFORMATION

We have filed with the SEC a registration statement on Form S-3 under the Securities Act, of which this prospectus supplement forms a part. The rules and regulations of the SEC allow us to omit from this prospectus supplement and the accompanying prospectus certain information included in the registration statement. For further information about us and the securities we are offering under this prospectus supplement, you should refer to the registration statement and the exhibits and schedules filed with the registration statement. With respect to the statements contained in this prospectus supplement and the accompanying prospectus regarding the contents of any agreement or any other document, in each instance, the statement is qualified in all respects by the complete text of the agreement or document, a copy of which has been filed as an exhibit to the registration statement.

We file reports, proxy statements and other information with the SEC. The SEC maintains a website that contains reports, proxy and information statements and other information regarding issuers that file electronically with the SEC. The address of the SEC's website is www.sec.gov.

We make available free of charge on or through our website at www.cardiffoncology.com, our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Exchange Act, as soon as reasonably practicable after we electronically file such material with or otherwise furnish it to the SEC. The information on, or accessible through, our website is not part of, and is not incorporated into, this prospectus supplement or the accompanying prospectus and should not be considered part of this prospectus supplement or the accompanying prospectus.

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INCORPORATION OF DOCUMENTS BY REFERENCE

The SEC allows us to incorporate by reference into this prospectus supplement much of the information we file with the SEC, which means that we can disclose important information to you by referring you to those publicly available documents. The information that we incorporate by reference is considered to be part of this prospectus supplement and the accompanying prospectus. Because we are incorporating by reference future filings with the SEC, this prospectus supplement and the accompanying prospectus are continually updated and those future filings may modify or supersede some of the information included or incorporated in this prospectus supplement and the accompanying prospectus. This means that you must look at all of the SEC filings that we incorporate by reference to determine if any of the statements in this prospectus supplement or the accompanying prospectus or in any document previously incorporated by reference have been modified or superseded. This prospectus supplement and the accompanying prospectus incorporate by reference the documents listed below and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act (in each case, other than those documents or the portions of those documents not deemed to be filed) until the offering of the securities under the registration statement is terminated or completed:

You may request, and we will provide you with, a copy of these filings, at no cost, by calling us at (858) 952-7570 or by writing to us at the following address:

Cardiff Oncology, Inc.

11055 Flintkote Avenue

San Diego, CA 92121

Attn.: Secretary

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PROSPECTUS

Common Stock

Preferred Stock

Debt Securities

Warrants

Units

We may offer and sell, from time to time in one or more offerings, any combination of common stock, preferred stock, debt securities, warrants to purchase common stock, preferred stock or debt securities, or any combination of the foregoing, either individually or as units comprised of one or more of the other securities, having an aggregate initial offering price not exceeding $400 million.

This prospectus provides a general description of the securities we may offer. Each time we sell a particular class or series of securities, we will provide specific terms of the securities offered in a supplement to this prospectus. The prospectus supplement and any related free writing prospectus may also add, update or change information contained in this prospectus. We may also authorize one or more free writing prospectuses to be provided to you in connection with these offerings. You should read carefully this prospectus, the applicable prospectus supplement and any related free writing prospectus, as well as any documents incorporated by reference herein or therein before you invest in any of our securities.

The specific terms of any securities to be offered, and the specific manner in which they may be offered, will be described in one or more supplements to this prospectus. This prospectus may not be used to consummate sales of any of these securities unless it is accompanied by a prospectus supplement. Before investing, you should carefully read this prospectus and any related prospectus supplement.

Our common stock is presently listed on The Nasdaq Capital Market under the symbol "CRDF." On May 5, 2025 the last reported sale price of our common stock was $2.68 per share. The applicable prospectus supplement will contain information, where applicable, as to any other listing on The Nasdaq Capital Market or any securities market or other exchange of the securities, if any, covered by the prospectus supplement. Prospective purchasers of our securities are urged to obtain current information as to the market prices of our securities, where applicable.

These securities may be sold directly by us, through dealers or agents designated from time to time, to or through underwriters, dealers, or through a combination of these methods on a continuous or delayed basis. See "Plan of Distribution" in this prospectus. We may also describe the plan of distribution for any particular offering of our securities in a prospectus supplement. If any agents, underwriters or dealers are involved in the sale of any securities in respect of which this prospectus is being delivered, we will disclose their names and the nature of our arrangements with them in a prospectus supplement. The price to the public of such securities and the net proceeds we expect to receive from any such sale will also be included in a prospectus supplement.

Investing in our securities involves various risks. See "Risk Factors" contained herein for more information on these risks. Additional risks will be described in the related prospectus supplements under the heading "Risk Factors." You should review that section of the related prospectus supplements for a discussion of matters that investors in our securities should consider.

Neither the U.S. Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities, or passed upon the adequacy or accuracy of this prospectus or any accompanying prospectus supplement. Any representation to the contrary is a criminal offense.

The date of this prospectus is May 13, 2025.

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TABLE OF CONTENTS

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ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the U.S. Securities and Exchange Commission, or SEC, using a "shelf" registration process. Under this shelf registration statement, we may sell from time to time in one or more offerings of common stock and preferred stock, various series of debt securities and/or warrants to purchase any of such securities, either individually or as units comprised of a combination of one or more of the other securities in one or more offerings up to a total dollar amount of $400 million. This prospectus provides you with a general description of the securities we may offer. Each time we sell any type or series of securities under this prospectus, we will provide a prospectus supplement that will contain more specific information about the terms of that offering.

This prospectus does not contain all of the information included in the registration statement. For a more complete understanding of the offering of the securities, you should refer to the registration statement, including its exhibits. We may add, update or change, in a prospectus supplement or free writing prospectus, any of the information contained in this prospectus or in the documents we have incorporated by reference into this prospectus. We may also authorize one or more free writing prospectuses to be provided to you that may contain material information relating to these offerings. This prospectus, together with the applicable prospectus supplement, any related free writing prospectus and the documents incorporated by reference into this prospectus and the applicable prospectus supplement, will include all material information relating to the applicable offering. You should carefully read both this prospectus and the applicable prospectus supplement and any related free writing prospectus, together with the additional information described under "Where You Can Find More Information," before buying any of the securities being offered.

We have not authorized any dealer, agent or other person to give any information or to make any representation other than those contained or incorporated by reference in this prospectus, any accompanying prospectus supplement or any related free writing prospectus that we may authorize to be provided to you. You must not rely upon any information or representation not contained or incorporated by reference in this prospectus or an accompanying prospectus supplement, or any related free writing prospectus that we may authorize to be provided to you. This prospectus, the accompanying prospectus supplement and any related free writing prospectus, if any, do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the registered securities to which they relate, nor do this prospectus, the accompanying prospectus supplement or any related free writing prospectus, if any, constitute an offer to sell or the solicitation of an offer to buy securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction. You should not assume that the information contained in this prospectus, any applicable prospectus supplement or any related free writing prospectus is accurate on any date subsequent to the date set forth on the front of the document or that any information we have incorporated by reference is correct on any date subsequent to the date of the document incorporated by reference (as our business, financial condition, results of operations and prospects may have changed since that date), even though this prospectus, any applicable prospectus supplement or any related free writing prospectus is delivered or securities are sold on a later date.

We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference in this prospectus were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

This prospectus may not be used to consummate sales of our securities, unless it is accompanied by a prospectus supplement. To the extent there are inconsistencies between any prospectus supplement, this prospectus and any documents incorporated by reference, the document with the most recent date will control.

As permitted by the rules and regulations of the SEC, the registration statement, of which this prospectus forms a part, includes additional information not contained in this prospectus. You may read the registration statement and the other reports we file with the SEC at the SEC's web site or at the SEC's offices described below under the heading "Where You Can Find More Information."

Company References

In this prospectus "the Company," "we," "us," and "our" refer to Cardiff Oncology, Inc., a Delaware corporation, and its subsidiaries, unless the context otherwise requires.

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SUMMARY

Overview

We are a clinical-stage biotechnology company leveraging PLK1 inhibition, a well-validated oncology drug target, to develop novel therapies across a range of cancers with the greatest unmet medical need. Our goal is to target tumor vulnerabilities with treatment combinations of onvansertib, our oral and highly selective PLK1 inhibitor, and standard-of-care ("SoC") therapeutics. We are focusing our clinical program in indications such as RAS-mutated metastatic colorectal cancer ("mCRC"), as well as in investigator-initiated ongoing or planned trials in metastatic pancreatic ductal adenocarcinoma ("mPDAC"), small cell lung cancer ("SCLC"), and triple negative breast cancer ("TNBC"). Our clinical development programs incorporate tumor genomics and biomarker assays to refine assessment of patient response to treatment.

Our Lead Drug Candidate, Onvansertib

Onvansertib is an oral, small molecule drug candidate that is highly specific for PLK1 inhibition with a 24-hour half-life.

We believe the attributes of onvansertib described below, as well as early clinical evidence of favorable safety and efficacy, with expected on-target, manageable and tolerable side effects, may prove beneficial in addressing clinical therapeutic needs across a variety of cancers:

In vitro studies have shown synergistic effects when onvansertib was administered in combination with different cytotoxic agents including microtubule-targeting agents, topoisomerase 1 inhibitors, antimetabolites, alkylating agents, proteasome inhibitors, kinase inhibitors, PARP inhibitors, BCL-2 inhibitors, and androgen biosynthesis inhibitors.

In addition, in vivo combination studies have confirmed the positive results obtained in vitro and additive or synergistic effects on efficacy have been observed in xenograft models of onvansertib in combination with irinotecan, 5-fluorouracil ("5-FU"), abiraterone, PARP inhibitors, venetoclax, paclitaxel, or bevacizumab. Combining onvansertib with SoC cancer agents may provide opportunities for synergy with many cancer therapies.

There are several ongoing and planned clinical trials of onvansertib in multiple indications: one trial (CRDF-004) in first-line treatment in patients with RAS-mutated mCRC, and investigator-initiated trials in first-line mPDAC, relapsed SCLC and unresectable locally advanced or metastatic TNBC.

RAS-mutated mCRC Program:

CRDF-004 Randomized Clinical Trial in First-Line RAS-mutated mCRC

CRDF-004 is a Phase 2 open-label, randomized multi-center clinical trial of onvansertib in combination with SoC FOLFIRI and bevacizumab or SoC FOLFOX and bevacizumab for the first-line treatment of patients with RAS-mutated mCRC. The primary objectives of the CRDF-004 trial are to evaluate onvansertib's safety and efficacy in combination with the SoC, as well as to evaluate two doses of onvansertib, 20mg and 30mg, given in combination with SoC, against SoC alone. The primary endpoint of the trial is objective response rate ("ORR"). Progression-free survival and duration of response will be secondary endpoints. This trial is conducted in partnership with Pfizer Ignite, an end-to-end service for biotech companies, and it is expected to enroll approximately 90 evaluable patients. For more information, please visit NCT06106308 at www.clinicialtrials.gov.

Contingent upon the results of CRDF-004, we plan to initiate CRDF-005, a Phase 3, randomized trial with registrational intent. The FDA has agreed that a seamless trial with an interim endpoint of ORR, with duration of response, is acceptable to pursue accelerated approval, with progression-free survival and trend in overall survival being the endpoints for full approval.

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Data presented on December 10, 2024 provided initial results from the ongoing CRDF-004 Phase 2 randomized clinical trial in first-line RAS-mutated metastatic colorectal cancer. ORR, as of the data cut-off date of November 26, 2024, are shown below.

Spider Plots, displaying the change in tumor size from baseline for each patient over time, demonstrate deeper responses observed in patients receiving the 30mg dose of onvansertib in combination with the SoC compared to both the control arms and 20mg dose of onvansertib arms.

Note: Radiographic response determined per RECIST 1.1 by blinded independent central review. Spider plot reflects interim data as of November 26, 2024 from an ongoing trial and unlocked database.

Onvansertib in combination with chemo/bevacizumab was well-tolerated and there have been no major or unexpected toxicities observed.

Phase 1b/2 Clinical Trial in Second-Line KRAS-mutated mCRC

TROV-054, a Phase 1b/2 open-label multi-center clinical trial of onvansertib in combination with SoC FOLFIRI and bevacizumab for the second-line treatment of patients with KRAS-mutated mCRC, completed enrollment in October 2022.

The primary objectives of this trial were to evaluate the Dose-Limiting Toxicities ("DLTs"), maximum tolerated dose ("MTD") and recommended Phase 2 dose ("RP2D") of onvansertib in combination with FOLFIRI and bevacizumab (Phase 1b) and to continue to assess the safety and preliminary efficacy of onvansertib in combination with FOLFIRI and bevacizumab patients with KRAS-mutated mCRC (Phase 2). For more information, please visit NCT03829410 at www.clinicialtrials.gov.

Data presented on August 7, 2023, provided an update of the ongoing TROV-054 Phase 1b/2 single arm clinical trial in KRAS-mutated metastatic colorectal cancer:

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Based on the interim results of the TROV-054 trial, we designed the ONSEMBLE trial (CRDF-003) as the next phase of our mCRC program. Upon further review of the clinical data from the bevacizumab naïve subgroup (those patients who did not receive bevacizumab in their first-line therapy), the preclinical data on the mechanism of action and the feedback from the FDA on our clinical development strategy, we made the decision to discontinue enrollment in the ONSEMBLE trial and to initiate the CRDF-004 clinical trial.

Phase 2 Clinical Trial in Second-Line RAS-mutated mCRC

The ONSEMBLE trial (CRDF-003) was a Phase 2 randomized, open-label multi-center clinical trial of onvansertib in combination with SoC FOLFIRI and bevacizumab for the second-line treatment of patients with RAS-mutated mCRC. The ONSEMBLE trial completed enrollment in August 2023 as part of our shift to a first-line mCRC program. The primary objectives of the ONSEMBLE trial were to evaluate onvansertib's safety and efficacy in combination with FOLFIRI and bevacizumab, as well as to evaluate two doses of onvansertib, 20mg and 30mg, given in combination with FOLFIRI and bevacizumab, against FOLFIRI and bevacizumab alone. The primary endpoint of the trial was ORR. For more information, please visit NCT05593328 at www.clinicialtrials.gov.

The ORR data from the randomized ONSEMBLE trial validates the findings observed in our earlier single-arm Phase 1b/2 KRAS-mutated mCRC trial (TROV-054). In the ONSEMBLE trial, objective responses were observed only in bevacizumab naïve patients, not bevacizumab exposed patients. In addition, these objective responses were present only in bevacizumab naïve patients randomized to the experimental arms of onvansertib in combination with FOLFIRI and bevacizumab versus bevacizumab naïve patients randomized to the FOLFIRI and bevacizumab alone control arm.

mPDAC Program:

Phase 1b/2 Investigator-Initiated Clinical Trial in First-Line mPDAC

In February 2024, the FDA approved NALIRIFOX as a first-line treatment option for mPDAC. As a result, we are currently supporting a new investigator-initiated mPDAC Phase 1b/2 trial of onvansertib in combination with first-line SoC NALIRIFOX, which is now open for enrollment at the University of Kansas Medical Center. The trial replaced a previously planned two-cohort, non-randomized Phase 2 trial of onvansertib in combination with first-line SoC Gemzar® and Abraxane® . For more information, please visit NCT06736717 at www.clinicaltrials.gov.

The primary objective in this study is to determine anti-tumor activity by measuring Overall Response Rate (ORR). The secondary objectives are to determine treatment safety based on toxicities in participants who have received at least one dose of onvansertib, to determine anti-tumor activity by Progression Free Survival (PFS), to determine anti-tumor activity by Disease Control Rate (DCR), to determine Overall Survival (OS).

Phase 2 Clinical Trial in mPDAC

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CRDF-001, a Phase 2 open-label multi-center clinical trial of onvansertib in combination with nanoliposomal irinotecan (Onivyde®), leucovorin, and fluorouracil for 2nd line treatment of patients with mPDAC, completed enrollment in October 2023.

The objective of this trial was to assess the safety and preliminary efficacy of onvansertib in combination with nanoliposomal irinotecan (Onyvide®), 5-FU and leucovorin as a 2nd line treatment in patients with mPDAC who have failed first-line gemcitabine-based therapy. For more information, please visit NCT04752696 at www.clinicialtrials.gov.

Preliminary data presented on September 26, 2023, and updated on February 29, 2024, showed promising data that caused us to shift the program to a first-line investigator initiated trial.

mPDAC biomarker discovery trial

The investigator-initiated biomarker discovery trial is exploring the impact of onvansertib 10-day monotherapy on tumors in mPDAC patients, and enrolled at the Oregon Health & Science University (OHSU) Knight Cancer Institute. Enrollment for this trial is closed.

Preliminary data were presented on September 26, 2023. One patient demonstrated an 86% decrease in Ki67, a well-established biomarker of tumor proliferation, and a 28% decrease in CA 19-9, a clinically-used biomarker to monitor treatment response.

Other Clinical Programs:

Phase 2 Investigator-Initiated Clinical Trial in SCLC

A single-arm, two-stage, Phase 2 trial of onvansertib monotherapy in patients with relapsed SCLC is open for enrollment at the University of Maryland, Baltimore. The trial is designed to enroll 15 patients in Stage 1, with the study proceeding to Stage 2 if 2 or more Stage 1 patients achieve an objective response. Stage 2 is designed to enroll an additional 20 patients. The primary endpoint of the trial is ORR, while key secondary endpoints include PFS and overall survival. For more information, please visit NCT05450965 at www.clinicialtrials.gov.

An examination of the safety data from the first six patients by the institutional review board confirmed the trial can continue to enroll as planned. Preliminary efficacy data for seven patients presented on September 26, 2023, showed one confirmed partial response ("PR"), three stable disease ("SD") and three progressive disease ("PD"). The disease control rate ("DCR"), including PR and SD, is 57% (4 of 7 patients).

Phase 1b Investigator-Initiated Clinical Trial in TNBC

A single-arm, Phase 1b trial of onvansertib in combination with paclitaxel in patients with unresectable locally advanced or metastatic TNBC is open for enrollment at Dana Farber Cancer Institute ("DFCI"). In Phase 1b, approximately 14-16 patients will be treated with different doses of onvansertib in combination with a fixed dose of paclitaxel to determine the maximum tolerated dose and the safety and efficacy of onvansertib in combination with paclitaxel. For more information, please visit NCT05383196 at www.clinicialtrials.gov.

Risks Associated with Our Business

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Company Information

We were originally incorporated under the laws of the State of Florida in April 2002. In January 2010, we re-incorporated under the laws of the State of Delaware and changed our name to Trovagene, Inc. In May 2012, our common stock was listed on The Nasdaq Capital Market ("Nasdaq") under the ticker symbol TROV. In May 2020 we changed our name to Cardiff Oncology, Inc. and our Nasdaq ticker symbol changed to CRDF. Our corporate website address is www.cardiffoncology.com.

The Securities We May Offer

We may offer shares of our common stock and preferred stock, various series of debt securities and warrants to purchase any of such securities, either individually or in units, from time to time under this prospectus, together with any applicable prospectus supplement and related free writing prospectus, at prices and on terms to be determined by market conditions at the time of offering. If we issue any debt securities at a discount from their original stated principal amount, then, for purposes of calculating the total dollar amount of all securities issued under this prospectus, we will treat the initial offering price of the debt securities as the total original principal amount of the debt securities. Each time we offer securities under this prospectus, we will provide offerees with a prospectus supplement that will describe the specific amounts, prices and other important terms of the securities being offered, including, to the extent applicable:

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A prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update, or change information contained in this prospectus or in documents we have incorporated by reference. However, no prospectus supplement or free writing prospectus will offer a security that is not registered and described in this prospectus at the time of the effectiveness of the registration statement of which this prospectus is a part.

We may sell the securities to or through underwriters, dealers or agents or directly to purchasers. We, as well as any agents acting on our behalf, reserve the sole right to accept and to reject in whole or in part any proposed purchase of securities. Each prospectus supplement will set forth the names of any underwriters, dealers or agents involved in the sale of securities described in that prospectus supplement and any applicable fee, commission or discount arrangements with them, details regarding any over-allotment option granted to them, and net proceeds to us. The following is a summary of the securities we may offer with this prospectus.

Common Stock

We currently have authorized 150,000,000 shares of common stock, par value $0.0001 per share. As of May 5, 2025, 66,525,854 shares of common stock were issued and outstanding. We may offer shares of our common stock either alone or underlying other registered securities convertible into or exercisable for our common stock. Holders of our common stock are entitled to such dividends as our board of directors (the "Board of Directors" or "Board") may declare from time to time out of legally available funds, subject to the preferential rights of the holders of any shares of our preferred stock that are outstanding or that we may issue in the future. Currently, we do not pay any dividends on our common stock. Each holder of our common stock is entitled to one vote per share. In this prospectus, we provide a general description of, among other things, the rights and restrictions that apply to holders of our common stock.

Preferred Stock

We currently have authorized 20,000,000 shares of preferred stock, par value $0.001, of which 277,100 shares are designated as Series A Convertible Preferred Stock, of which 60,600 shares are issued and outstanding as of May 5, 2025;

Any authorized and undesignated shares of preferred stock may be issued from time to time in one or more additional series pursuant to a resolution or resolutions providing for such issue duly adopted by our Board of Directors (authority to do so being hereby expressly vested in the Board of Directors). The Board of Directors is further authorized, subject to limitations prescribed by law, to fix by resolution or resolutions the designations, powers, preferences and rights, and the qualifications, limitations or restrictions thereof, of any wholly unissued series of preferred stock, including without limitation authority to fix by resolution or resolutions the dividend rights, dividend rate, conversion rights, voting rights, rights and terms of redemption (including sinking fund provisions), redemption price or prices, and liquidation preferences of any such series, and the number of shares constituting any such series and the designation thereof, or any of the foregoing.

The rights, preferences, privileges, and restrictions granted to or imposed upon any series of preferred stock that we offer and sell under this prospectus and applicable prospectus supplements will be set forth in a certificate of designation relating to the series. We will incorporate by reference into the registration statement of which this prospectus is a part the form of any certificate of designation that describes the terms of the series of preferred stock we are offering before the issuance of shares of that series of preferred stock. You should read any prospectus supplement and any free writing prospectus that we may authorize to be provided to you related to the series of preferred stock being offered, as well as the complete certificate of designation that contains the terms of the applicable series of preferred stock.

Debt Securities

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We may offer general debt obligations, which may be secured or unsecured, senior or subordinated, and convertible into shares of our common stock or preferred stock. In this prospectus, we refer to the senior debt securities and the subordinated debt securities together as the "debt securities." We may issue debt securities under a note purchase agreement or under an indenture to be entered between us and a trustee. The indentures do not limit the amount of securities that may be issued under it and provide that debt securities may be issued in one or more series. The senior debt securities will have the same rank as all of our other indebtedness that is not subordinated. The subordinated debt securities will be subordinated to our senior debt on terms set forth in the applicable prospectus supplement. In addition, the subordinated debt securities will be effectively subordinated to creditors and preferred stockholders of our subsidiaries. Our Board of Directors will determine the terms of each series of debt securities being offered. This prospectus contains only general terms and provisions of the debt securities. The applicable prospectus supplement will describe the particular terms of the debt securities offered thereby. You should read any prospectus supplement and any free writing prospectus that we may authorize to be provided to you related to the series of debt securities being offered, as well as the complete note agreements and/or indentures that contain the terms of the debt securities. The forms of senior and subordinated indentures have been filed as exhibits to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of debt securities being offered will be incorporated by reference into the registration statement of which this prospectus is a part from reports we file with the SEC.

Warrants

We may offer warrants for the purchase of shares of our common stock or preferred stock or of debt securities. We may issue the warrants by themselves or together with common stock, preferred stock or debt securities, and the warrants may be attached to or separate from any offered securities. Any warrants issued under this prospectus may be evidenced by warrant certificates. Warrants may be issued under a separate warrant agreement to be entered into between us and the investors or a warrant agent. Our Board of Directors will determine the terms of the warrants. This prospectus contains only general terms and provisions of the warrants. The applicable prospectus supplement will describe the particular terms of the warrants being offered thereby. You should read any prospectus supplement and any free writing prospectus that we may authorize to be provided to you related to the series of warrants being offered, as well as the complete warrant agreements that contain the terms of the warrants. Specific warrant agreements will contain additional important terms and provisions and will be incorporated by reference into the registration statement of which this prospectus is a part from reports we file with the SEC.

Units

We may offer units consisting of our common stock or preferred stock, debt securities and/or warrants to purchase any of these securities in one or more series. We may evidence each series of units by unit certificates that we will issue under a separate agreement. We may enter into unit agreements with a unit agent. Each unit agent will be a bank or trust company that we select. We will indicate the name and address of the unit agent in the applicable prospectus supplement relating to a particular series of units. This prospectus contains only a summary of certain general features of the units. The applicable prospectus supplement will describe the particular features of the units being offered thereby. You should read any prospectus supplement and any free writing prospectus that we may authorize to be provided to you related to the series of units being offered, as well as the complete unit agreements that contain the terms of the units. Specific unit agreements will contain additional important terms and provisions and will be incorporated by reference into the registration statement of which this prospectus is a part from reports we file with the SEC.

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RISK FACTORS

An investment in our securities involves a high degree of risk. This prospectus contains, and the prospectus supplement applicable to each offering of our securities will contain, a discussion of the risks applicable to an investment in our securities. Prior to making a decision about investing in our securities, you should carefully consider the specific factors discussed under the heading "Risk Factors" in this prospectus and the applicable prospectus supplement, together with all of the other information contained or incorporated by reference in the prospectus supplement or appearing or incorporated by reference in this prospectus. You should also consider the risks, uncertainties and assumptions discussed under Item 1A, "Risk Factors," in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, filed with the SEC on February 27, 2025, and any updates described in our Quarterly Reports on Form 10-Q, all of which are incorporated herein by reference, and may be amended, supplemented or superseded from time to time by other reports we file with the SEC in the future and any prospectus supplement related to a particular offering. The risks and uncertainties we have described are not the only ones we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also affect our operations. The occurrence of any of these known or unknown risks might cause you to lose all or part of your investment in the offered securities.

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FORWARD-LOOKING STATEMENTS

This prospectus, any accompanying prospectus supplement, any related free writing prospectus and the documents incorporated by reference herein or therein contain, in addition to historical information, certain forward-looking statements within the meaning of Section 27A of the Securities Act or 1933, as amended (the "Securities Act"), and Section 21E of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), that include information relating to future events, future financial performance, strategies, expectations, competitive environment, regulation and availability of resources. Such forward-looking statements include those that express plans, anticipation, intent, contingency, goals, targets or future development and/or otherwise are not statements of historical fact. These forward-looking statements are based on our current expectations and projections about future events and they are subject to risks and uncertainties known and unknown that could cause actual results and developments to differ materially from those expressed or implied in such statements.

In some cases, you can identify forward-looking statements by terminology, such as "expects," "anticipates," "intends," "estimates," "plans," "believes," "seeks," "may," "should", "could" or the negative of such terms or other similar expressions. Accordingly, these statements involve estimates, assumptions and uncertainties that could cause actual results to differ materially from those expressed in them. Any forward-looking statements are qualified in their entirety by reference to the factors discussed throughout this prospectus supplement or incorporated herein by reference.

Risks, uncertainties and other factors that may cause our actual results, performance or achievements to be different from those expressed or implied in our written or oral forward-looking statements may be found in this prospectus supplement under the heading "Risk Factors" and in our Annual Report on Form 10-K for the year ended December 31, 2024 under the headings "Risk Factors" and "Business," as updated in our Quarterly Report(s) on Form 10-Q.

Forward-looking statements speak only as of the date they are made. You should not put undue reliance on any forward-looking statements. We assume no obligation to update forward-looking statements to reflect actual results, changes in assumptions or changes in other factors affecting forward-looking information, except to the extent required by applicable securities laws. If we do update one or more forward-looking statements, no inference should be drawn that we will make additional updates with respect to those or other forward-looking statements.

New factors emerge from time to time, and it is not possible for us to predict which factors will arise. In addition, we cannot assess the impact of each factor on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements. We qualify all of the information presented in this prospectus supplement and incorporated herein by reference, and particularly our forward-looking statements, by these cautionary statements.

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USE OF PROCEEDS

Except as described in any prospectus supplement and any free writing prospectus in connection with a specific offering, we currently intend to use the net proceeds from the sale of the securities offered under this prospectus for general corporate purposes, including the development and commercialization of our products, research and development, general and administrative expenses, license or technology acquisitions, and working capital and capital expenditures. We may also use the net proceeds to repay any debts and/or invest in or acquire complementary businesses, products, or technologies, although we have no current commitments or agreements with respect to any such investments or acquisitions as of the date of this prospectus. We have not determined the amount of net proceeds to be used specifically for the foregoing purposes. As a result, our management will have broad discretion in the allocation of the net proceeds and investors will be relying on the judgment of our management regarding the application of the proceeds of any sale of the securities. Pending use of the net proceeds, we intend to invest the proceeds in short-term, investment-grade, interest-bearing instruments.

Each time we offer securities under this prospectus, we will describe the intended use of the net proceeds from that offering in the applicable prospectus supplement. The actual amount of net proceeds we spend on a particular use will depend on many factors, including, our future capital expenditures, the amount of cash required by our operations, and our future revenue growth, if any. Therefore, we will retain broad discretion in the use of the net proceeds.

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DESCRIPTION OF CAPITAL STOCK

General

The following description of our capital stock, together with any additional information we include in any applicable prospectus supplement or any related free writing prospectus, summarizes the material terms and provisions of our common stock and the preferred stock that we may offer under this prospectus. While the terms we have summarized below will apply generally to any future common stock or preferred stock that we may offer, we will describe the particular terms of any class or series of these securities in more detail in the applicable prospectus supplement. For the complete terms of our common stock and preferred stock, please refer to our amended and restated certificate of incorporation, as amended ("Certificate of Incorporation"), and our bylaws that are incorporated by reference into the registration statement of which this prospectus is a part or may be incorporated by reference in this prospectus or any applicable prospectus supplement. The terms of these securities may also be affected by Delaware General Corporation Law (the "DGCL"). The summary below and that contained in any applicable prospectus supplement or any related free writing prospectus are qualified in their entirety by reference to our Certificate of Incorporation and our bylaws.

As of the date of this prospectus, our authorized capital stock consisted of 150,000,000 shares of common stock, $0.0001 par value per share, and 20,000,000 shares of preferred stock, $0.001 par value per share. Our Board may establish the rights and preferences of the preferred stock from time to time. As of May 5, 2025, there were 66,525,854 shares of our common stock issued and outstanding, 60,600 shares of our Series A Convertible Preferred Stock issued and outstanding.

Common Stock

We are authorized to issue up to a total of 150,000,000 shares of common stock, par value $0.0001 per share. Holders of our common stock are entitled to one vote for each share held on all matters submitted to a vote of our stockholders. Holders of our common stock have no cumulative voting rights. All shares of common stock offered hereby will, when issued, be fully paid and nonassessable, including shares of common stock issued upon the exercise of common stock warrants or subscription rights, if any.

Further, holders of our common stock have no preemptive or conversion rights or other subscription rights. Upon our liquidation, dissolution or winding- up, holders of our common stock are entitled to share in all assets remaining after payment of all liabilities and the liquidation preferences of any of our outstanding shares of preferred stock. Subject to preferences that may be applicable to any outstanding shares of preferred stock, holders of our common stock are entitled to receive dividends, if any, as may be declared from time to time by our Board of Directors out of our assets which are legally available. Such dividends, if any, are payable in cash, in property or in shares of capital stock.

The holders of a majority of the shares of our capital stock, represented in person or by proxy, are necessary to constitute a quorum for the transaction of business at any meeting. If a quorum is present, an action by stockholders entitled to vote on a matter is approved if the number of votes cast in favor of the action exceeds the number of votes cast in opposition to the action, with the exception of the election of directors, which requires a plurality of the votes cast.

Preferred Stock

Our Board of Directors has the authority, without further action by the stockholders, to issue up to 20,000,000 shares of preferred stock in one or more series and to fix the designations, powers, preferences, privileges, and relative participating, optional, or special rights as well as the qualifications, limitations, or restrictions of the preferred stock, including dividend rights, conversion rights, voting rights, terms of redemption, and liquidation preferences, any or all of which may be greater than the rights of the common stock. Our Board of Directors, without stockholder approval, can issue preferred stock with voting, conversion, or other rights that could adversely affect the voting power and other rights of the holders of common stock. Preferred stock could be issued quickly with terms calculated to delay or prevent a change of control or make removal of management more difficult. Additionally, the issuance of preferred stock may have the effect of decreasing the market price of our common stock, and may adversely affect the voting and other rights of the holders of common stock. At present, we have no plans to issue any shares of preferred stock following this offering.

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Anti-Takeover Effects of Certain Provisions of our Certificate of Incorporation, Bylaws and the DGCL

We are governed by the provisions of Section 203 of the DGCL. In general, Section 203 prohibits a publicly traded Delaware corporation from engaging in a business combination with an interested stockholder for a period of three years after the date of the transaction in which the person became an interested stockholder, unless the business combination is approved in a prescribed manner. A business combination includes mergers, asset sales or other transactions resulting in a financial benefit to the stockholder. An interested stockholder is a person who, together with affiliates and associates, owns (or within three years, did own) 15% or more of the corporation's voting stock, subject to certain exceptions. The statute could have the effect of delaying, deferring or preventing a change in control of our Company.

Our Certificate of Incorporation and bylaws contain provisions that could have the effect of discouraging potential acquisition proposals or making a tender offer or delaying or preventing a change in control, including changes a stockholder might consider favorable. In particular, our Certificate of Incorporation and bylaws, as applicable, among other things:

Such provisions may have the effect of discouraging a third-party from acquiring us, even if doing so would be beneficial to our stockholders. These provisions are intended to enhance the likelihood of continuity and stability in the composition of our Board of Directors and in the policies formulated by them, and to discourage some types of transactions that may involve an actual or threatened change in control of our Company. These provisions are designed to reduce our vulnerability to an unsolicited acquisition proposal and to discourage some tactics that may be used in proxy fights. We believe that the benefits of increased protection of our potential ability to negotiate with the proponent of an unfriendly or unsolicited proposal to acquire or restructure our Company outweigh the disadvantages of discouraging such proposals because, among other things, negotiation of such proposals could result in an improvement of their terms.

However, these provisions could have the effect of discouraging others from making tender offers for our shares that could result from actual or rumored takeover attempts. These provisions also may have the effect of preventing changes in our management.

Listing

Our common stock is listed on The Nasdaq Capital Market under the trading symbol "CRDF."

Transfer Agent and Registrar

The Transfer Agent and Registrar for our common stock is Pacific Stock Transfer Company, Inc.

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DESCRIPTION OF DEBT SECURITIES

The following description, together with the additional information we include in any applicable prospectus supplements or free writing prospectuses, summarizes the material terms and provisions of the debt securities that we may offer under this prospectus. We may issue debt securities, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. While the terms we have summarized below will apply generally to any future debt securities we may offer under this prospectus, we will describe the particular terms of any debt securities that we may offer in more detail in the applicable prospectus supplement or free writing prospectus. The terms of any debt securities we offer under a prospectus supplement may differ from the terms we describe below. However, no prospectus supplement shall fundamentally change the terms that are set forth in this prospectus or offer a security that is not registered and described in this prospectus at the time of its effectiveness. As of the date of this prospectus, we have no outstanding registered debt securities. Unless the context requires otherwise, whenever we refer to the "indentures," we also are referring to any supplemental indentures that specify the terms of a particular series of debt securities.

We will issue any senior debt securities under the senior indenture that we will enter into with the trustee named in the senior indenture. We will issue any subordinated debt securities under the subordinated indenture and any supplemental indentures that we will enter into with the trustee named in the subordinated indenture. We have filed forms of these documents as exhibits to the registration statement, of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of the debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.

The indentures will be qualified under the Trust Indenture Act of 1939, as amended (the "Trust Indenture Act"). We use the term "trustee" to refer to either the trustee under the senior indenture or the trustee under the subordinated indenture, as applicable.

The following summaries of material provisions of the senior debt securities, the subordinated debt securities and the indentures are subject to, and qualified in their entirety by reference to, all of the provisions of the indenture and any supplemental indentures applicable to a particular series of debt securities. We urge you to read the applicable prospectus supplements and any related free writing prospectuses related to the debt securities that we may offer under this prospectus, as well as the complete indentures that contains the terms of the debt securities. Except as we may otherwise indicate, the terms of the senior indenture and the subordinated indenture are identical.

General

The terms of each series of debt securities will be established by or pursuant to a resolution of our Board of Directors and set forth or determined in the manner provided in an officers' certificate or by a supplemental indenture. Debt securities may be issued in separate series without limitation as to aggregate principal amount. We may specify a maximum aggregate principal amount for the debt securities of any series. We will describe in the applicable prospectus supplement the terms of the series of debt securities being offered, including:

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Conversion or Exchange Rights

We will set forth in the applicable prospectus supplement the terms under which a series of debt securities may be convertible into or exchangeable for our common stock, our preferred stock or other securities (including securities of a third party). We will include provisions as to whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of shares of our common stock, our preferred stock or other securities (including securities of a third party) that the holders of the series of debt securities receive would be subject to adjustment.

Consolidation, Merger or Sale

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Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the indentures will not contain any covenant that restricts our ability to merge or consolidate, or sell, convey, transfer or otherwise

dispose of all or substantially all of our assets. However, any successor to or acquirer of such assets must assume all of our obligations under the indentures or the debt securities, as appropriate. If the debt securities are convertible into or exchangeable for our other securities or securities of other entities, the person with whom we consolidate or merge or to whom we sell all of our property must make provisions for the conversion of the debt securities into securities that the holders of the debt securities would have received if they had converted the debt securities before the consolidation, merger or sale.

Events of Default under the Indenture

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the following are events of default under the indentures with respect to any series of debt securities that we may issue:

We will describe in each applicable prospectus supplement any additional events of default relating to the relevant series of debt securities.

If an event of default with respect to debt securities of any series occurs and is continuing, other than an event of default specified in the last bullet point above, the trustee or the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series, by notice to us in writing, and to the trustee if notice is given by such holders, may declare the unpaid principal, premium, if any, and accrued interest, if any, due and payable immediately. If an event of default arises due to the occurrence of certain specified bankruptcy, insolvency or reorganization events, the unpaid principal, premium, if any, and accrued interest, if any, of each issue of debt securities then outstanding shall be due and payable without any notice or other action on the part of the trustee or any holder.

The holders of a majority in principal amount of the outstanding debt securities of an affected series may waive any default or event of default with respect to the series and its consequences, except defaults or events of default regarding payment of principal, premium, if any, or interest, unless we have cured the default or event of default in accordance with the indenture. Any waiver shall cure the default or event of default.

Subject to the terms of the indentures, if an event of default under an indenture shall occur and be continuing, the trustee will be under no obligation to exercise any of its rights or powers under such indenture at the request or direction of any of the holders of the applicable series of debt securities, unless such holders have offered the trustee reasonable indemnity or security satisfactory to it against any loss, liability or expense. The holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee, or exercising any trust or power conferred on the trustee, with respect to the debt securities of that series, provided that:

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The indentures will provide that if an event of default has occurred and is continuing, the trustee will be required in the exercise of its powers to use the degree of care that a prudent person would use in the conduct of its own affairs. The trustee, however, may refuse to follow any direction that conflicts with law or the indenture, or that the trustee determines is unduly prejudicial to the rights of any other holder of the relevant series of debt securities, or that would involve the trustee in personal

liability. Prior to taking any action under the indentures, the trustee will be entitled to indemnification against all costs, expenses and liabilities that would be incurred by taking or not taking such action.

A holder of the debt securities of any series will have the right to institute a proceeding under the indentures or to appoint a receiver or trustee, or to seek other remedies only if:

These limitations do not apply to a suit instituted by a holder of debt securities if we default in the payment of the principal, premium, if any, or interest on, the debt securities, or other defaults that may be specified in the applicable prospectus supplement.

We will periodically file statements with the trustee regarding our compliance with specified covenants in the indentures.

The indentures will provide that if a default occurs and is continuing and is actually known to a responsible officer of the trustee, the trustee must mail to each holder notice of the default within the earlier of 90 days after it occurs and 30 days after it is known by a responsible officer of the trustee or written notice of it is received by the trustee, unless such default has been cured or waived. Except in the case of a default in the payment of principal or premium of, or interest on, any debt security or certain other defaults specified in an indenture, the trustee shall be protected in withholding such notice if and so long as the Board of Directors, the executive committee or a trust committee of directors, or responsible officers of the trustee, in good faith determine that withholding notice is in the best interests of holders of the relevant series of debt securities.

Modification of Indenture; Waiver

Subject to the terms of the indenture for any series of debt securities that we may issue, we and the trustee may change an indenture without the consent of any holders with respect to the following specific matters:

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In addition, under the indentures, the rights of holders of a series of debt securities may be changed by us and the trustee with the written consent of the holders of at least a majority in aggregate principal amount of the outstanding debt securities of each series that is affected. However, subject to the terms of the indenture for any series of debt securities that we may issue or otherwise provided in the prospectus supplement applicable to a particular series of debt securities, we and the trustee may only make the following changes with the consent of each holder of any outstanding debt securities affected:

Discharge

Each indenture provides that, subject to the terms of the indenture and any limitation otherwise provided in the prospectus supplement applicable to a particular series of debt securities, we may elect to be discharged from our obligations with respect to one or more series of debt securities, except for specified obligations, including obligations to:

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In order to exercise our rights to be discharged, we will deposit with the trustee money or government obligations sufficient to pay all the principal of, and any premium and interest on, the debt securities of the series on the dates payments are due.

Form, Exchange and Transfer

We will issue the debt securities of each series only in fully registered form without coupons and, unless we otherwise specify in the applicable prospectus supplement, in denominations of $1,000 and any integral multiple thereof. The indentures will provide that we may issue debt securities of a series in temporary or permanent global form and as book-entry securities that will be deposited with, or on behalf of, The Depository Trust Company or another depositary named by us and identified in a prospectus supplement with respect to that series. See "Legal Ownership of Securities" below for a further description of the terms relating to any book-entry securities.

At the option of the holder, subject to the terms of the indentures and the limitations applicable to global securities described in the applicable prospectus supplement, the holder of the debt securities of any series can exchange the debt securities for other debt securities of the same series, in any authorized denomination and of like tenor and aggregate principal amount.

Subject to the terms of the indentures and the limitations applicable to global securities set forth in the applicable prospectus supplement, holders of the debt securities may present the debt securities for exchange or for registration of transfer, duly endorsed or with the form of transfer endorsed thereon duly executed if so required by us or the security registrar, at the office of the security registrar or at the office of any transfer agent designated by us for this purpose. Unless otherwise provided in the debt securities that the holder presents for transfer or exchange, we will make no service charge for any registration of transfer or exchange, but we may require payment of any taxes or other governmental charges.

We will name in the applicable prospectus supplement the security registrar, and any transfer agent in addition to the security registrar, that we initially designate for any debt securities. We may at any time designate additional transfer agents or rescind the designation of any transfer agent or approve a change in the office through which any transfer agent acts, except that we will be required to maintain a transfer agent in each place of payment for the debt securities of each series.

If we elect to redeem the debt securities of any series, we will not be required to:

Information Concerning the Trustee

The trustee, other than during the occurrence and continuance of an event of default under an indenture, undertakes to perform only those duties as are specifically set forth in the applicable indenture and is under no obligation to exercise any of the powers given it by the indentures at the request of any holder of debt securities unless it is offered reasonable security and indemnity against the costs, expenses and liabilities that it might incur. However, upon an event of default under an indenture, the trustee must use the same degree of care as a prudent person would exercise or use in the conduct of his or her own affairs.

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Payment and Paying Agents

Unless we otherwise indicate in the applicable prospectus supplement, we will make payment of the interest on any debt securities on any interest payment date to the person in whose name the debt securities, or one or more predecessor securities, are registered at the close of business on the regular record date for the interest payment.

We will pay principal of and any premium and interest on the debt securities of a particular series at the office of the paying agents designated by us, except that unless we otherwise indicate in the applicable prospectus supplement, we will make interest payments by check that we will mail to the holder or by wire transfer to certain holders. Unless we otherwise indicate in the applicable prospectus supplement, we will designate the corporate trust office of the trustee as our sole paying agent for payments with respect to debt securities of each series. We will name in the applicable prospectus supplement any other paying agents that we initially designate for the debt securities of a particular series. We will maintain a paying agent in each place of payment for the debt securities of a particular series.

All money we pay to a paying agent or the trustee for the payment of the principal of or any premium or interest on any debt securities that remains unclaimed at the end of two years after such principal, premium or interest has become due and payable will be repaid to us, and the holder of the debt security thereafter may look only to us for payment thereof.

Governing Law

The indentures and the debt securities will be governed by and construed in accordance with the laws of the State of New York, except to the extent that the Trust Indenture Act is applicable.

Ranking Debt Securities

The subordinated debt securities will be unsecured and will be subordinate and junior in priority of payment to certain other indebtedness to the extent described in a prospectus supplement. The subordinated indenture does not limit the amount of subordinated debt securities that we may issue. It also does not limit us from issuing any other secured or unsecured debt.

The senior debt securities will be unsecured and will rank equally in right of payment to all our other senior unsecured debt. The senior indenture does not limit the amount of senior debt securities that we may issue. It also does not limit us from issuing any other secured or unsecured debt.

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DESCRIPTION OF WARRANTS

The following description, together with the additional information we may include in any applicable prospectus supplements and free writing prospectuses, summarizes the material terms and provisions of the warrants that we may offer under this prospectus, which may consist of warrants to purchase common stock, preferred stock or debt securities and may be issued in one or more series. Warrants may be offered independently or together with common stock, preferred stock or debt securities offered by any prospectus supplement, and may be attached to or separate from those securities. While the terms we have summarized below will apply generally to any warrants that we may offer under this prospectus, we will describe the particular terms of any series of warrants that we may offer in more detail in the applicable prospectus supplement and any applicable free writing prospectus. The terms of any warrants offered under a prospectus supplement may differ from the terms described below. However, no prospectus supplement will fundamentally change the terms that are set forth in this prospectus or offer a security that is not registered and described in this prospectus at the time of its effectiveness.

We may issue the warrants under a warrant agreement that we will enter into with a warrant agent to be selected by us. If selected, the warrant agent will act solely as an agent of ours in connection with the warrants and will not act as an agent for the holders or beneficial owners of the warrants. If applicable, we will file as exhibits to the registration statement of which this prospectus is a part, or will incorporate by reference from a Current Report on Form 8-K that we file with the SEC, the form of warrant agreement, including a form of warrant certificate, that describes the terms of the particular series of warrants we are offering before the issuance of the related series of warrants. The following summaries of material provisions of the warrants and the warrant agreements are subject to, and qualified in their entirety by reference to, all the provisions of the warrant agreement and warrant certificate applicable to a particular series of warrants. We urge you to read the applicable prospectus supplement and any applicable free writing prospectus related to the particular series of warrants that we sell under this prospectus, as well as the complete warrant agreements and warrant certificates that contain the terms of the warrants.

General

We will describe in the applicable prospectus supplement the terms relating to a series of warrants, including:

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Before exercising their warrants, holders of warrants will not have any of the rights of holders of the securities purchasable upon such exercise, including:

Exercise of Warrants

Each warrant will entitle the holder to purchase the securities that we specify in the applicable prospectus supplement at the exercise price that we describe in the applicable prospectus supplement. Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants at any time up to the specified time on the expiration date that we set forth in the applicable prospectus supplement. After the close of business on the expiration date, unexercised warrants will become void.

Holders of the warrants may exercise the warrants by delivering the warrant certificate representing the warrants to be exercised together with specified information, and paying the required amount to the warrant agent in immediately available funds, as provided in the applicable prospectus supplement. We will set forth on the reverse side of the warrant certificate and in the applicable prospectus supplement the information that the holder of the warrant will be required to deliver to us or the warrant agent as applicable.

Upon receipt of the required payment and the warrant certificate properly completed and duly executed at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement, we will issue and deliver the securities purchasable upon such exercise. If fewer than all of the warrants represented by the warrant certificate are exercised, then we will issue a new warrant certificate for the remaining amount of warrants. If we so indicate in the applicable prospectus supplement, holders of the warrants may surrender securities as all or part of the exercise price for warrants.

Enforceability of Rights by Holders of Warrants

If selected, each warrant agent will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of agency or trust with any holder of any warrant. A single bank or trust company may act as warrant agent for more than one issue of warrants. A warrant agent will have no duty or responsibility in case of any default by us under the applicable warrant agreement or warrant, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a warrant may, without the consent of the related warrant agent or the holder of any other warrant, enforce by appropriate legal action its right to exercise, and receive the securities purchasable upon exercise of, its warrants.

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DESCRIPTION OF UNITS

The following description, together with the additional information we may include in any applicable prospectus supplements and free writing prospectuses, summarizes the material terms and provisions of the units that we may offer under this prospectus.

While the terms we have summarized below will apply generally to any units that we may offer under this prospectus, we will describe the particular terms of any series of units in more detail in the applicable prospectus supplement. The terms of any units offered under a prospectus supplement may differ from the terms described below. However, no prospectus supplement will fundamentally change the terms that are set forth in this prospectus or offer a security that is not registered and described in this prospectus at the time of its effectiveness.

We will file as exhibits to the registration statement of which this prospectus is a part, or will incorporate by reference from a Current Report on Form 8-K that we file with the SEC, the form of unit agreement that describes the terms of the series of units we are offering, and any supplemental agreements, before the issuance of the related series of units. The following summaries of material terms and provisions of the units are subject to, and qualified in their entirety by reference to, all the provisions of the unit agreement and any supplemental agreements applicable to a particular series of units. We urge you to read the applicable prospectus supplements related to the particular series of units that we sell under this prospectus, as well as the complete unit agreement and any supplemental agreements that contain the terms of the units.

General

We may issue units comprised of one or more debt securities, shares of common stock, shares of preferred stock and warrants in any combination. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each included security. The unit agreement under which a unit is issued may provide that the securities included in the unit may not be held or transferred separately, at any time or at any time before a specified date.

We will describe in the applicable prospectus supplement the terms of the series of units, including:

The provisions described in this section, as well as those described under "Description of Capital Stock," "Description of Debt Securities" and "Description of Warrants" will apply to each unit and to any common stock, preferred stock, debt security or warrant included in each unit, respectively.

Unit Agent

The name and address of the unit agent, if any, for any units we offer will be set forth in the applicable prospectus supplement.

Issuance in Series

We may issue units in such amounts and in numerous distinct series as we determine.

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Enforceability of Rights by Holders of Units

Each unit agent will act solely as our agent under the applicable unit agreement and will not assume any obligation or relationship of agency or trust with any holder of any unit. A single bank or trust company may act as unit agent for more than one series of units. A unit agent will have no duty or responsibility in case of any default by us under the applicable unit agreement or unit, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a unit may, without the consent of the related unit agent or the holder of any other unit, enforce by appropriate legal action its rights as holder under any security included in the unit.

We, the unit agents and any of their agents may treat the registered holder of any unit certificate as an absolute owner of the units evidenced by that certificate for any purpose and as the person entitled to exercise the rights attaching to the units so requested, despite any notice to the contrary. See "Legal Ownership of Securities."

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LEGAL OWNERSHIP OF SECURITIES

We can issue securities in registered form or in the form of one or more global securities. We describe global securities in greater detail below. We refer to those persons who have securities registered in their own names on the books that we or any applicable trustee or depositary or warrant agent maintain for this purpose as the "holders" of those securities. These persons are the legal holders of the securities. We refer to those persons who, indirectly through others, own beneficial interests in securities that are not registered in their own names, as "indirect holders" of those securities. As we discuss below, indirect holders are not legal holders, and investors in securities issued in book-entry form or in street name will be indirect holders.

Book-Entry Holders

We may issue securities in book-entry form only, as we will specify in the applicable prospectus supplement. This means securities may be represented by one or more global securities registered in the name of a financial institution that holds them as depositary on behalf of other financial institutions that participate in the depositary's book-entry system. These participating institutions, which are referred to as participants, in turn, hold beneficial interests in the securities on behalf of themselves or their customers.

Only the person in whose name a security is registered is recognized as the holder of that security. Global securities will be registered in the name of the depositary or its participants. Consequently, for global securities, we will recognize only the depositary as the holder of the securities, and we will make all payments on the securities to the depositary. The depositary passes along the payments it receives to its participants, which in turn pass the payments along to their customers who are the beneficial owners. The depositary and its participants do so under agreements they have made with one another or with their customers; they are not obligated to do so under the terms of the securities.

As a result, investors in a global security will not own securities directly. Instead, they will own beneficial interests in a global security, through a bank, broker or other financial institution that participates in the depositary's book-entry system or holds an interest through a participant. As long as the securities are issued in global form, investors will be indirect holders, and not legal holders, of the securities.

Street Name Holders

We may terminate a global security or issue securities that are not issued in global form. In these cases, investors may choose to hold their securities in their own names or in "street name." Securities held by an investor in street name would be registered in the name of a bank, broker or other financial institution that the investor chooses, and the investor would hold only a beneficial interest in those securities through an account he or she maintains at that institution.

For securities held in street name, we or any applicable trustee or depositary will recognize only the intermediary banks, brokers and other financial institutions in whose names the securities are registered as the holders of those securities, and we or any such trustee or depositary will make all payments on those securities to them. These institutions pass along the payments they receive to their customers who are the beneficial owners, but only because they agree to do so in their customer agreements or because they are legally required to do so. Investors who hold securities in street name will be indirect holders, not legal holders, of those securities.

Legal Holders

Our obligations, as well as the obligations of any applicable trustee or third party employed by us or a trustee, run only to the legal holders of the securities. We do not have obligations to investors who hold beneficial interests in global securities, in street name or by any other indirect means. This will be the case whether an investor chooses to be an indirect holder of a security or has no choice because we are issuing the securities only in global form.

For example, once we make a payment or give a notice to the holder, we have no further responsibility for the payment or notice even if that holder is required, under agreements with its participants or customers or by law, to pass it along to the indirect holders but does not do so. Similarly, we may want to obtain the approval of the holders to amend an indenture, to relieve us of the consequences of a default or of our obligation to comply with a particular provision of an indenture, or for other purposes. In

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such an event, we would seek approval only from the legal holders, and not the indirect holders, of the securities. Whether and how the legal holders contact the indirect holders is up to the legal holders.

Special Considerations for Indirect Holders

If you hold securities through a bank, broker or other financial institution, either in book-entry form because the securities are represented by one or more global securities or in street name, you should check with your own institution to find out:

Global Securities

A global security is a security that represents one or any other number of individual securities held by a depositary. Generally, all securities represented by the same global securities will have the same terms.

Each security issued in book-entry form will be represented by a global security that we issue to, deposit with and register in the name of a financial institution or its nominee that we select. The financial institution that we select for this purpose is called the depositary. Unless we specify otherwise in the applicable prospectus supplement, The Depository Trust Company, New York, NY, known as DTC, will be the depositary for all securities issued in book-entry form.

A global security may not be transferred to or registered in the name of anyone other than the depositary, its nominee or a successor depositary, unless special termination situations arise. We describe those situations below under "- Special Situations When A Global Security Will Be Terminated." As a result of these arrangements, the depositary, or its nominee, will be the sole registered owner and legal holder of all securities represented by a global security, and investors will be permitted to own only beneficial interests in a global security. Beneficial interests must be held by means of an account with a broker, bank or other financial institution that in turn has an account with the depositary or with another institution that does. Thus, an investor whose security is represented by a global security will not be a legal holder of the security, but only an indirect holder of a beneficial interest in the global security.

If the prospectus supplement for a particular security indicates that the security will be issued as a global security, then the security will be represented by a global security at all times unless and until the global security is terminated. If termination occurs, we may issue the securities through another book-entry clearing system or decide that the securities may no longer be held through any book-entry clearing system.

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Special Considerations For Global Securities

As an indirect holder, an investor's rights relating to a global security will be governed by the account rules of the investor's financial institution and of the depositary, as well as general laws relating to securities transfers. We do not recognize an indirect holder as a holder of securities and instead deal only with the depositary that holds the global security.

If securities are issued only as global securities, an investor should be aware of the following:

Special Situations When A Global Security Will Be Terminated

In a few special situations described below, a global security will terminate and interests in it will be exchanged for physical certificates representing those interests. After that exchange, the choice of whether to hold securities directly or in street name will be up to the investor. Investors must consult their own banks or brokers to find out how to have their interests in securities transferred to their own names, so that they will be direct holders. We have described the rights of holders and street name investors above.

A global security will terminate when the following special situations occur:

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The applicable prospectus supplement may also list additional situations for terminating a global security that would apply only to the particular series of securities covered by the prospectus supplement. When a global security terminates, the depositary, and neither we, nor any applicable trustee, is responsible for deciding the names of the institutions that will be the initial direct holders.

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PLAN OF DISTRIBUTION

We may sell the securities being offered hereby in one or more of the following ways from time to time:

As set forth in more detail below, the securities may be distributed from time to time in one or more transactions:

We will set forth in a prospectus supplement the terms of that particular offering of securities, including:

Only underwriters named in an applicable prospectus supplement are underwriters of the securities offered by that prospectus supplement.

If underwriters are used in an offering, we will execute an underwriting agreement with such underwriters and will specify the name of each underwriter and the terms of the transaction (including any underwriting discounts and other terms constituting compensation of the underwriters and any dealers) in a prospectus supplement. The securities may be offered to the public either through underwriting syndicates represented by managing underwriters or directly by one or more investment banking firms or others, as designated. If an underwriting syndicate is used, the managing underwriter(s) will be specified on the

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cover of the prospectus supplement. If underwriters are used in the sale, the offered securities will be acquired by the underwriters for their own accounts and may be resold from time to time in one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at the time of sale. Any public offering price and any discounts or concessions allowed or re-allowed or paid to dealers may be changed from time to time. Unless otherwise

set forth in the prospectus supplement, the obligations of the underwriters to purchase the offered securities will be subject to conditions precedent and the underwriters will be obligated to purchase all of the offered securities if any are purchased.

We may grant to the underwriters options to purchase additional securities to cover over-allotments, if any, at the public offering price, with additional underwriting commissions or discounts, as may be set forth in a related prospectus supplement. The terms of any over-allotment option will be set forth in the prospectus supplement for those securities.

If we use a dealer in the sale of the securities being offered pursuant to this prospectus or any prospectus supplement, we will sell the securities to the dealer, as principal. The dealer may then resell the securities to the public at varying prices to be determined by the dealer at the time of resale. The names of the dealers and the terms of the transaction will be specified in a prospectus supplement.

We may sell the securities directly or through agents we designate from time to time. We will name any agent involved in the offering and sale of securities and we will describe any commissions we will pay the agent in the prospectus supplement. Unless the prospectus supplement states otherwise, any agent will act on a best-efforts basis for the period of its appointment.

We may authorize agents or underwriters to solicit offers by institutional investors to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. We will describe the conditions to these contracts and the commissions we must pay for solicitation of these contracts in the prospectus supplement.

In connection with the sale of the securities, underwriters, dealers or agents may receive compensation from us or from purchasers of the common stock for whom they act as agents in the form of discounts, concessions or commissions. Underwriters may sell the securities to or through dealers, and those dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters or commissions from the purchasers for whom they may act as agents. Underwriters, dealers and agents that participate in the distribution of the securities, and any institutional investors or others that purchase common stock directly and then resell the securities, may be deemed to be underwriters, and any discounts or commissions received by them from us and any profit on the resale of the common stock by them may be deemed to be underwriting discounts and commissions under the Securities Act.

We may provide agents and underwriters with indemnification against particular civil liabilities, including liabilities under the Securities Act, or contribution with respect to payments that the agents or underwriters may make with respect to such liabilities. Agents and underwriters may engage in transactions with, or perform services for, us in the ordinary course of business.

We may engage in at the market offerings into an existing trading market in accordance with Rule 415(a)(4) under the Securities Act. In addition, we may enter into derivative transactions with third parties (including the writing of options), or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement indicates, in connection with such a transaction, the third parties may, pursuant to this prospectus and the applicable prospectus supplement, sell securities covered by this prospectus and the applicable prospectus supplement. If so, the third party may use securities borrowed from us or others to settle such sales and may use securities received from us to close out any related short positions. We may also loan or pledge securities covered by this prospectus and the applicable prospectus supplement to third parties, who may sell the loaned securities or, in an event of default in the case of a pledge, sell the pledged securities pursuant to this prospectus and the applicable prospectus supplement. The third party in such sale transactions will be an underwriter and will be identified in the applicable prospectus supplement or in a post-effective amendment.

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To facilitate an offering of a series of securities, persons participating in the offering may engage in transactions that stabilize, maintain, or otherwise affect the market price of the securities. This may include over-allotments or short sales of the securities, which involves the sale by persons participating in the offering of more securities than have been sold to them by us. In those circumstances, such persons would cover such over-allotments or short positions by purchasing in the open market or by exercising the over-allotment option granted to those persons. In addition, those persons may stabilize or maintain the price of the securities by bidding for or purchasing securities in the open market or by imposing penalty bids, whereby selling concessions allowed to underwriters or dealers participating in any such offering may be reclaimed if securities sold by them are repurchased in connection with stabilization transactions. The effect of these transactions may be to stabilize or maintain the market price of the securities at a level above that which might otherwise prevail in the open market. Such transactions, if commenced, may be discontinued at any time. We make no representation or prediction as to the direction or magnitude of any effect that the transactions described above, if implemented, may have on the price of our securities.

Unless otherwise specified in the applicable prospectus supplement, each class or series of securities will be a new issue with no established trading market, other than our common stock, which is listed on The Nasdaq Capital Market. We may elect to list any other class or series of securities on any exchange or market, but we are not obligated to do so. It is possible that one or more underwriters may make a market in a class or series of securities, but the underwriters will not be obligated to do so and may discontinue any market making at any time without notice. We cannot give any assurance as to the liquidity of the trading market for any of the securities.

In order to comply with the securities laws of some U.S. states or territories, if applicable, the securities offered pursuant to this prospectus will be sold in those states only through registered or licensed brokers or dealers. In addition, in some states securities may not be sold unless they have been registered or qualified for sale in the applicable state or an exemption from the registration or qualification requirement is available and complied with.

Any underwriter may engage in overallotment, stabilizing transactions, short covering transactions and penalty bids in accordance with Regulation M under the Exchange Act. Overallotment involves sales in excess of the offering size, which create a short position. Stabilizing transactions permit bids to purchase the underlying security so long as the stabilizing bids do not exceed a specified maximum. Short covering transactions involve purchases of the securities in the open market after the distribution is completed to cover short positions. Penalty bids permit the underwriters to reclaim a selling concession from a dealer when the securities originally sold by the dealer are purchased in a covering transaction to cover short positions. Those activities may cause the price of the securities to be higher than it would otherwise be. If commenced, the underwriters may discontinue any of these activities at any time.

Any underwriters who are qualified market makers on The Nasdaq Capital Market may engage in passive market making transactions in the securities on The Nasdaq Capital Market in accordance with Rule 103 of Regulation M, during the business day prior to the pricing of the offering, before the commencement of offers or sales of the securities. Passive market makers must comply with applicable volume and price limitations and must be identified as passive market makers. In general, a passive market maker must display its bid at a price not in excess of the highest independent bid for such security. If all independent bids are lowered below the passive market maker's bid, however, the passive market maker's bid must then be lowered when certain purchase limits are exceeded.

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LEGAL MATTERS

The validity of the issuance of the securities offered hereby will be passed upon for us by Sheppard, Mullin, Richter & Hampton LLP, New York, NY. Additional legal matters may be passed upon for us or any underwriters, dealers or agents, by counsel that we will name in the applicable prospectus supplement.

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EXPERTS

The financial statements of Cardiff Oncology, Inc. as of December 31, 2024 and 2023 and for the years then ended incorporated by reference in this prospectus and in the registration statement have been so incorporated in reliance on the report of BDO USA, P.C., an independent registered public accounting firm given on the authority of said firm as experts in auditing and accounting.

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WHERE YOU CAN FIND MORE INFORMATION

This prospectus constitutes a part of the registration statement on Form S-3 that we have filed with the SEC under the Securities Act. As permitted by the SEC's rules, this prospectus supplement and any accompanying prospectus, which forms a part of the registration statement, do not contain all of the information that is included in the registration statement. You will find additional information about us in the registration statement. Any statement made in this prospectus supplement or any accompanying prospectus concerning legal documents are not necessarily complete and you should read the documents that are filed as exhibits to the registration statement or otherwise filed with the SEC for a more complete understanding of the document or matter.

We are subject to the reporting requirements of the Exchange Act and file annual, quarterly and current reports, proxy statements and other information with the SEC. You can read our SEC filings, including the registration statement, over the Internet at the SEC's website at http://www.sec.gov. We also maintain a website at www.cardiffoncology.com, at which you may access these materials free of charge as soon as reasonably practicable after they are electronically filed with, or furnished to, the SEC. The information contained in, or that can be accessed through, our website is not part of this prospectus.

You may also read and copy any document we file with the SEC at its public reference facilities at 100 F Street, N.E., Room 1580, Washington, DC 20549. You may also obtain copies of these documents at prescribed rates by writing to the Public Reference Section of the SEC at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the operation of the public reference facilities. You may also request a copy of these filings, at no cost, by writing or telephoning us at: 11055 Flintkote Avenue, San Diego, California, 92121, (858) 952-7570.

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INCORPORATION OF DOCUMENTS BY REFERENCE

This prospectus supplement is part of the registration statement, but the registration statement includes and incorporates by reference additional information and exhibits. The SEC permits us to "incorporate by reference" the information contained in documents we file with the SEC, which means that we can disclose important information to you by referring you to those documents rather than by including them in this prospectus supplement. Information that is incorporated by reference is considered to be part of this prospectus supplement and you should read it with the same care that you read this prospectus supplement and the accompanying prospectus. Information that we file later with the SEC will automatically update and supersede the information that is either contained, or incorporated by reference, in this prospectus supplement, and will be considered to be a part of this prospectus supplement from the date those documents are filed.

We incorporate by reference the documents listed below, all filings filed by us pursuant to the Exchange Act after the date of the registration statement of which this prospectus supplement and the accompanying prospectus forms a part, and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act prior to the time that all securities covered by this prospectus supplement have been sold; provided, however, that we are not incorporating any information furnished under either Item 2.02 or Item 7.01 of any current report on Form 8-K:

Any statements made in a document incorporated by reference in this prospectus supplement are deemed to be modified or superseded for purposes of this prospectus supplement to the extent that a statement in this prospectus supplement or in any other subsequently filed document, which is also incorporated by reference, modifies or supersedes the statement. Any statement made in this prospectus supplement is deemed to be modified or superseded to the extent a statement in any subsequently filed document, which is incorporated by reference in this prospectus supplement, modifies or supersedes such statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus supplement.

The information relating to us contained in this prospectus supplement should be read together with the information in the documents incorporated by reference. In addition, certain information, including financial information, contained in this prospectus or incorporated by reference in this prospectus should be read in conjunction with documents we have filed with the SEC.

We will provide to each person, including any beneficial holder, to whom a prospectus is delivered, at no cost, upon written or oral request, a copy of any or all of the information that has been incorporated by reference in the prospectus but not delivered with the prospectus. Requests for documents should be by writing to or telephoning us at the following address: Cardiff Oncology, Inc., 11055 Flintkote Avenue, San Diego, CA 92121; (858) 952-7570. Exhibits to these filings will not be sent unless those exhibits have been specifically incorporated by reference in such filings.

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Cardiff Oncology, Inc.

9,293,078 Shares of Common Stock

Common Warrants to Purchase 9,293,078 Shares of Common Stock

(and the 9,293,078 shares of Common Stock underlying the Common Warrants)

Placement Agent Warrants to Purchase 464,654 Shares of Common Stock

(and the 464,654 shares of Common Stock underlying the Placement Agent Warrants)

PROSPECTUS SUPPLEMENT

H.C. Wainwright & Co.

July 14, 2026