Quarterly Report for Quarter Ending September 30, 2026 (Form 10-Q)

Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations.

The following discussion and analysis of our financial condition and results of operations should be read together with our unaudited condensed consolidated financial statements and related notes appearing elsewhere in this Quarterly Report on Form 10-Q and with our audited consolidated financial statements and related notes for the year ended December 31, 2025 included in our Annual Report on Form 10-K. Some of the information contained in this discussion and analysis or set forth elsewhere in this Quarterly Report on Form 10-Q, including information with respect to our plans and strategy for our business, includes forward-looking statements that involve risks and uncertainties. As a result of many factors, including those factors set forth in the "Risk Factors" section of this Quarterly Report on Form 10-Q and our Annual Report on Form 10-K for the fiscal year ended December 31, 2025, our actual results could differ materially from the results described in, or implied by, the forward-looking statements contained in the following discussion and analysis.

Overview

Tango was founded with a clear mission: to discover the next wave of targeted therapies in oncology by addressing the specific genetic alterations that drive cancer. We are committed to delivering breakthrough targeted therapies that extend and improve the lives of patients with cancer. Using an approach that focuses on genetic vulnerabilities in cancer, we are pursuing PRMT5-targeted therapies designed to address pancreatic and other forms of cancer while sparing healthy normal tissues. We believe our approach will provide the ability to deliver deep, durable target inhibition with favorable tolerability and safety profiles, thus potentially maximizing clinical benefit.

We are currently focused on clinical development of two MTAP-deleted selective PRMT5 inhibitors: vopimetostat (TNG462) for non-CNS cancers, both as a monotherapy and in combination with RAS inhibitors, and TNG456, our next-generation, brain-penetrant PRMT5 inhibitor, for CNS cancers, including GBM. We are evaluating vopimetostat alone and in combination with RAS inhibitors based on overlapping patient populations, preclinical data supporting potential strong combination effect in clinical trials, and favorable clinical efficacy, durability, and safety profiles observed to date with each applicable drug individually.

Vopimetostat

In June 2025, we treated the first patient in our combination clinical trial evaluating vopimetostat with the RAS(ON) multi-selective inhibitor, daraxonrasib, and RAS(ON) G12D-selective inhibitor, zoldonrasib (Revolution Medicines) and in June 2026, we reported initial safety and efficacy data from our ongoing Phase 1/2 clinical trial evaluating vopimetostat in combination with Revolution Medicines' RAS(ON) inhibitors in patients with MTAP-deleted and RAS-mutant metastatic PDAC.

In October 2026, we announced promising results from our ongoing Phase 1/2 clinical trial of vopimetostat in combination with Revolution Medicines' RAS(ON) inhibitors in patients with MTAP-deleted and RAS-mutant metastatic PDAC and NSCLC, which was presented at the European Society for Medical Oncology (ESMO) 2026 Congress.

As of the data cutoff date of August 20, 2026, updated data from the ongoing Phase 1/2 clinical trial demonstrated an 82% ORR and a 9-month PFS rate of 88% in 22 patients with second-line or third-line MTAP-deleted/RAS-mutant PDAC who were efficacy-evaluable as of the data cutoff date. Median PFS had not yet been reached. The combination was generally well-tolerated in the 30 PDAC and NSCLC patients who received dose level 1.

As of the data cutoff date of August 20, 2026, 34 patients with previously treated MTAP-deleted and RAS-mutant PDAC (n=29) or NSCLC (n=5) were treated with vopimetostat plus daraxonrasib. The majority of PDAC patients (13 of 22 patients) who were efficacy-evaluable received the combination as third-line treatment. Efficacy-evaluable patients are those patients who received their first dose of treatment at least 14 weeks prior to the data cutoff date.

In the vopimetostat plus daraxonrasib dose escalation arm, efficacy-evaluable patients received either vopimetostat 200 mg (n=19; dose level 1) or 250 mg (n=3; dose level 2) QD plus daraxonrasib 100 mg QD. As of the data cutoff date of August 20, 2026, 22 patients were efficacy-evaluable, with a median follow up of 7.1 months (range: 3.3-12.5 months).

In efficacy-evaluable PDAC patients with MTAP-deleted, RAS-mutant PDAC, we observed an ORR of 82% (18 of 22 patients, with 11 of 18 cPRs and 7 unconfirmed partial responses), an 88% 9-month PDF rate and a 100% DCR. All unconfirmed responses were confirmed after the data cutoff date. Median PFS had not yet been reached.

Dose level 1 (n=25 safety-evaluable patients) of the vopimetostat plus daraxonrasib combination in PDAC patients was generally well-tolerated as of the data cutoff date. There were no DLTs and no withdrawals due to TRAEs. There were no Grade 4

or 5 TRAEs and the rate of Grade 3 TRAEs was 40% (10 of 25 patients). The most common TRAEs were Grade 1 or 2 stomatitis (48%), rash (44%), and diarrhea (28%). Dose level 2 (n=4 safety-evaluable patients) of the vopimetostat plus daraxonrasib combination in PDAC patients was not well-tolerated and there were 3 DLTs in 2 patients at this dose level. Safety evaluable patients are those who received at least one dose of the applicable combination prior to the data cutoff date.

In NSCLC patients, as of the data cutoff date, we observed an ORR of 80% (4 of 5 patients, all of whom had cPRs) at dose level 1 and a 100% DCR.

The vopimetostat plus daraxonrasib combination in NSCLC patients (n=5 safety-evaluable patients) had no Grade 4 or 5 TRAEs and the rate of Grade 3 TRAEs was 20% (1 of 5 patients). The most common TRAEs in NSCLC safety-evaluable patients were Grade 1 or 2 rash (100%), diarrhea (80%), stomatitis (40%), nausea (40%), and fatigue (40%).

In the vopimetostat plus zoldonrasib dose escalation arm, PDAC patients with MTAP deletion and KRAS G12D mutation received vopimetostat 200 mg or 250 mg QD plus zoldonrasib 600 mg or 1200 mg QD across four dose levels (dose level 1: 200 mg/600 mg QD; dose level 2: 250 mg/600 mg QD; dose level 3: 250 mg/1200 mg QD; and dose level 4: 200 mg/1200 mg QD). As of the data cutoff date of August 20, 2026, 35 patients were efficacy-evaluable, meaning that they received their first dose of treatment at least 14 weeks prior to the data cutoff date. 39 patients were safety-evaluable, meaning they received at least one dose of this combination prior to the data cutoff date.

We observed an ORR of 54% (19 of 35 patients, with 18 cPRs and one confirmed complete response as of the data cutoff date) across all dose levels in the vopimetostat plus zoldonrasib arm. We also observed a 61% 9-month PFS rate and a 97% DCR in these patients.

The vopimetostat plus zoldonrasib combination was generally well-tolerated across dose levels. There were no DLTs and no withdrawals due to TRAEs. The rate of dose reduction was 15% (6 of 39 patients). There were no Grade 5 TRAEs and there was one Grade 4 TRAE (3%). The rate of Grade 3 TRAEs was 28% (11 of 39 patients). The most common TRAEs were Grade 1 or 2 nausea (39%), vomiting (39%), dysgeusia (28%), and fatigue (26%).

Following recent interactions with the FDA, we plan to initiate a global, randomized registrational trial evaluating the combination of vopimetostat with daraxonrasib in front-line patients with MTAP-deleted PDAC. The planned study will randomize patients 1:1 to receive either vopimetostat (200 mg QD) plus daraxonrasib (100 mg QD) or standard-of-care chemotherapy. The dual primary endpoints of the planned study are ORR and PFS, with overall survival as a key secondary endpoint. We anticipate initiating this study in the first half of 2027. We are pursuing multiple pathways to obtain clinical supply of daraxonrasib for the planned study. In addition, we intend to discuss the possibility of seeking approval of this combination in patients with second-line PDAC with regulatory authorities.

Given the differentiated profile of vopimetostat enabling the potential for efficacious and tolerable RAS inhibitor combinations, in March 2026, we entered into a CTCSA with Erasca to evaluate vopimetostat in combination with Erasca's pan-RAS molecular glue, ERAS-0015. Under the terms of the CTCSA with Erasca, we are the sponsor of the trial and Erasca is supplying ERAS-0015 at no cost. We initiated this Phase 1/2 clinical trial in November 2026.

In October 2026, we also disclosed that we plan to initiate a Phase 1/2 vopimetostat + RAS combination study in second-line MTAP-wild type PDAC in the first half of 2027.

The Phase 1/2 clinical trial of vopimetostat monotherapy in patients with MTAP-deleted selective cancers is ongoing. Emerging data from the lung cancer cohort are consistent with expectations, and we anticipate providing a safety and efficacy update in January 2027.

TNG456

TNG456 is a brain-penetrant PRMT5 inhibitor. In May 2025, the first patient was treated with TNG456 in the dose escalation portion of the Phase 1/2 clinical trial to evaluate the safety, pharmacokinetics, pharmacodynamics and antitumor activity of TNG456 as a monotherapy. The trial is currently enrolling patients with MTAP-deleted solid tumors, with a focus on GBM and NSCLC. We anticipate providing initial clinical data from this trial in January 2027.

Reprioritization

Due to an increased focus on our PRMT5 pipeline, we are deprioritizing future development and resources allocated to TNG260 and are in the process of shutting down the clinical trial. Additionally, TNG961 is currently IND-ready and we do not

have current plans to further advance development of this molecule. In October 2026, our Board of Directors also approved a strategic reprioritization of our research and development activities to focus our efforts on the advancement of PRMT5-targeted therapies and our clinical product candidates, vopimetostat and TNG456, and to deprioritize novel target discovery. In connection with this reprioritization, we intend to stop certain preclinical and research activities to focus on translational work and our PRMT5 programs. As part of this reprioritization, we have reduced our overall workforce by approximately 14%, with the majority of the headcount reductions from our research group.

Financial Overview

Since our inception, we have focused primarily on organizing and staffing our company, business planning, raising capital, discovering product candidates, securing related intellectual property, and conducting research and development activities for our programs. To date, we have funded our operations primarily through equity financings and from the proceeds received from our collaboration agreement with Gilead. Through September 30, 2026, we have raised an aggregate of $1.8 billion from such transactions, including $1.6 billion in aggregate gross proceeds from the sale of preferred shares, the closing of our Business Combination, follow-on public and private offerings, and through our "at-the-market" offering programs, and $237.1 million pursuant to our collaboration with Gilead, the research portion of which concluded in August 2025.

We expect that our existing cash, cash equivalents and marketable securities on hand as of September 30, 2026 of $977.5 million will enable us to meet our current operating plan and fund our operating expenses and capital expenditure requirements for at least twelve months from the issuance of the financial statements in this Quarterly Report. Since inception, we have incurred significant operating losses. For the nine months ended September 30, 2026 and 2025, our net losses were $169.2 million and $62.8 million, respectively. We had an accumulated deficit of $772.4 million as of September 30, 2026. We expect to continue to incur significant and increasing expenses and operating losses for the foreseeable future as we advance our product candidates through preclinical and clinical development and seek regulatory approvals, manufacture drug product and drug supply, and maintain and expand our intellectual property portfolio. We also expect to hire additional personnel, pay for accounting, audit, legal, regulatory and consulting services, and pay costs associated with maintaining compliance with The Nasdaq Stock Market LLC listing rules and the requirements of the SEC, director and officer liability insurance, investor and public relations activities and other expenses associated with operating as a public company. Our net losses may fluctuate significantly from quarter-to-quarter and year-to-year, depending on the timing of our preclinical studies, our clinical trials, and our expenditures on other research and development activities.

We do not have any product candidates approved for sale and have not generated any revenue from product sales. We will not generate revenue from product sales unless and until we successfully complete clinical development and obtain regulatory approval for our product candidates, if ever. In addition, if we obtain regulatory approval for any of our product candidates and do not enter into a third-party commercialization partnership, we expect to incur significant expenses related to developing our commercialization capability to support product sales, marketing, manufacturing and distribution activities. As a result, we will need substantial additional funding to support our continuing operations and pursue our growth strategy. Until we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of public or private equity offerings and debt financings or other sources, such as potential collaboration agreements, strategic alliances and licensing arrangements. We may be unable to raise additional funds or enter into such other agreements or arrangements when needed on acceptable terms, or at all. Our failure to raise capital or enter into such agreements, as and when needed, could have a material adverse effect on our business, results of operations and financial condition.

Because of the numerous risks and uncertainties associated with pharmaceutical development, we are unable to predict the timing or amount of increased expenses or when or if we will be able to achieve or maintain profitability. Even if we are able to generate revenues from the sale of our therapies, if approved, we may not become profitable. If we fail to become profitable or are unable to sustain profitability on a continuing basis, then we may be unable to continue our operations at planned levels and be forced to reduce our operations.

Revenue

To date, we have not recognized any revenue from product sales, and we do not expect to generate any revenue from the sale of products in the next several years. If our development efforts for our product candidates are successful and result in regulatory approval, or license agreements with third parties, we may generate revenue in the future from product sales. However, there can be no assurance as to when we will generate such revenue, if at all.

Collaboration Agreements with Gilead

In October 2018, we entered into the 2018 Gilead Agreement with Gilead, under which we received an initial upfront payment of $50.0 million. In August 2020, the 2018 Gilead Agreement was expanded into the Gilead Agreement, a broader collaboration via an amended and restated research collaboration and license agreement, under which we received an upfront payment of $125.0 million. Upfront payments totaling $175.0 million and subsequent research extension fees totaling $24.0 million were recorded as deferred revenue on our balance sheet and recognized as revenue as or when the performance obligation under the contract was satisfied. In June 2024, Gilead licensed a program for a $12.0 million fee, which was recognized as license revenue in the second quarter of 2024.

In August 2025, we and Gilead mutually agreed to truncate the research term of the Gilead Agreement from seven to five years, concluding the research portion of the collaboration. There was no financial penalty to us as a result, no licensed programs were returned to us, all ongoing work at Gilead on licensed programs will continue and agreements for all future milestones and royalties remain in effect. We have no future research obligations and the remaining unrecognized deferred revenue balance at the time of truncating the collaboration agreement of $53.8 million was recognized as revenue in the third quarter of 2025.

During the three months ended September 30, 2026 and 2025, we recognized $0 and $53.8 million, respectively, and during the nine months ended September 30, 2026 and 2025, we recognized $0 and $62.4 million, respectively, of collaboration revenue associated with the 2018 Gilead Agreement and the Gilead Agreement based on performance completed during each period.

Refer to Note 2 and Note 3 to our unaudited condensed consolidated financial statements and related notes appearing elsewhere in this Quarterly Report on Form 10-Q and our audited consolidated financial statements and related notes for the year ended December 31, 2025 included in our Annual Report on Form 10-K for additional information regarding our revenue recognition accounting policy and our collaboration agreement with Gilead.

Operating Expenses

Research and Development Expenses

Research and development expenses consist primarily of costs incurred for our drug discovery efforts and the development of our product candidates. We expense research and development costs as incurred, which include:

Costs for certain activities are recognized based on an evaluation of the progress to completion of specific tasks using data such as information provided to us by our vendors and analyzing the progress of our preclinical studies or other services performed. Significant judgment and estimates are made in determining the accrued expense balances at the end of any reporting period.

Our direct external research and development expenses consist primarily of fees paid to contract research organizations, as well as outside vendors and consultants in connection with our preclinical and clinical development and manufacturing activities. We track these external research and development costs on a program-by-program basis once we have identified a product candidate.

We do not allocate employee costs or costs associated with our target discovery efforts, laboratory supplies, and facilities, including depreciation or other indirect costs, to specific programs because these costs are deployed across multiple programs and,

as such, are not separately classified. We characterize research and development costs incurred prior to the identification of a product candidate as discovery costs. We use internal resources primarily to conduct our research and discovery activities, as well as for managing our preclinical, development and manufacturing activities.

The following table summarizes our research and development expenses:

*In May 2026, we announced we would deprioritize future development and resources allocated to the Phase 1/2 TNG260 clinical trial given the limited clinical benefit demonstrated in patients.

**In May 2026, we announced we did not plan to further advance development of TNG961.

***In November 2024, we announced we stopped enrollment in the TNG908 Phase 1/2 trial due to insufficient brain exposure for GBM clinical activity and portfolio prioritization. Expenses beyond November 2024 related to previously enrolled patients and close-out clinical trial costs.

****In October 2026, we announced a strategic reprioritization of our research and development activities to focus our efforts on the advancement of PRMT5-targeted therapies and our clinical product candidates, vopimetostat and TNG456, and to deprioritize novel target discovery.

The successful development of our product candidates is highly uncertain. We plan to substantially increase our research and development expenses for the foreseeable future as we continue the development of our product candidates and manufacturing processes and conduct research activities for our preclinical programs. We cannot determine with certainty the timing of initiation, the duration or the completion costs of current or future preclinical studies and clinical trials of our product candidates or the timing of regulatory filings in connection with clinical trials or regulatory approval, due to the inherently unpredictable nature of preclinical and clinical development. Clinical and preclinical development timelines, the probability of success and development costs can differ materially from expectations. We anticipate that we will make determinations as to which product candidates to pursue and how much funding to direct to each product candidate on an ongoing basis in response to the results of ongoing and future preclinical studies and clinical trials, regulatory developments and our ongoing assessments as to each product candidate's commercial potential. Our clinical development costs have, and are expected to continue to increase significantly with the commencement and continuation of our current and planned clinical trials. We anticipate that our expenses will increase substantially, particularly due to the numerous risks and uncertainties associated with developing product candidates, including the uncertainty of:

Any changes in the outcome of any of these variables with respect to the development of our product candidates in preclinical and clinical development could mean a significant change in the costs and timing associated with the development of these product candidates. We may never succeed in achieving regulatory approval for any of our product candidates. We may obtain unexpected results from our clinical trials. We may elect to discontinue, delay or modify clinical trials of some product candidates or focus on other product candidates.

General and Administrative Expenses

General and administrative expenses consist primarily of employee-related costs, including salaries, bonuses, benefits, stock-based compensation and other related costs. General and administrative expenses also include professional services, including legal, accounting and audit services and other consulting fees, as well as facility costs not otherwise included in research and development expenses, insurance and other general administrative expenses.

We anticipate that our general and administrative expenses will increase in the future as we increase our headcount to support our continued research activities and development of our product candidates. We also anticipate that we will incur increased accounting, audit, legal, regulatory, compliance and director and officer insurance costs, as well as investor and public relations expenses associated with operating as a public company.

Other Income, Net

Interest Income

Interest income consists of income earned and losses incurred in connection with our investments in money market funds, U.S. Treasury bills, U.S. government agency bonds, and corporate debt securities.

Other Income, Net

Other income, net consists of miscellaneous income and expense unrelated to our core operations.

Provision for Income Taxes

Our provision for income tax consists of an estimate for U.S. federal and state income taxes based on enacted rates, as adjusted for allowable credits, deductions, uncertain tax positions, changes in deferred tax assets and liabilities and changes in tax law. We recorded an insignificant provision for income taxes for each of the three and nine months ended September 30, 2026 and 2025.

Results of Operations

Comparison of the three months ended September 30, 2026 and 2025

The following table summarizes our results of operations for the three months ended September 30, 2026 and 2025:

Collaboration Revenue

Collaboration revenue of $0 and $53.8 million for the three months ended September 30, 2026 and 2025, respectively, was derived from the Gilead Agreement. All remaining deferred revenue from the upfront and research option-extension payments under the Gilead Agreement was recognized as collaboration revenue during the year ended December 31, 2025 as a result of the truncation of the Gilead Agreement which concluded all research activities in August 2025.

Research and Development Expenses

Research and development expense was $48.9 million for the three months ended September 30, 2026 compared to $30.8 million for the three months ended September 30, 2025. The increase of $18.1 million was primarily driven by a $14.0 million increase in spend related to the advancement of the vopimetostat and TNG456 clinical programs, a $4.7 million increase in personnel-related costs, including share-based compensation expense, and a $1.3 million increase in discovery program expenses. These increases were partially offset by a $1.0 million decrease due to the discontinuation of the TNG908 and TNG260 clinical programs and a $1.0 million decrease in development costs for TNG961.

General and Administrative Expenses

General and administrative expense was $29.2 million for the three months ended September 30, 2026 compared to $8.9 million for the three months ended September 30, 2025. The increase of $20.3 million was primarily due to an increase in personnel-related costs, including share-based compensation expense which included increases derived from the modification of previously issued equity awards for our former Executive Chair during the three months ended September 30, 2026. The change also included increased spend on professional fees, including consulting and legal services, and information technology related spend.

Interest Income

Interest income was $7.2 million for the three months ended September 30, 2026 compared to $1.1 million for the three months ended September 30, 2025, with the increase primarily attributable to a higher marketable securities balance during the third quarter of 2026 as compared to the same period in the prior year.

Other Income, Net

Other income, net was $2.6 million for the three months ended September 30, 2026 compared to $0.7 million for the three months ended September 30, 2025. In both periods, other income, net, was primarily derived from accretion from investments purchased at a discount.

Provision for Income Taxes

Provision for income taxes was less than $0.1 million for each of the three months ended September 30, 2026 and 2025. The tax provisions were insignificant in each of the three months ended September 30, 2026 and 2025.

Comparison of the nine months ended September 30, 2026 and 2025

The following table summarizes our results of operations for the nine months ended September 30, 2026 and 2025:

Collaboration Revenue

Collaboration revenue of $0 and $62.4 million for the nine months ended September 30, 2026 and 2025, respectively, was derived from the Gilead Agreement. All remaining deferred revenue from the upfront and research option-extension payments under the Gilead Agreement was recognized as collaboration revenue during the year ended December 31, 2025 as a result of the truncation of the Gilead Agreement which concluded all research activities in August 2025.

Research and Development Expenses

Research and development expense was $119.7 million for the nine months ended September 30, 2026 compared to $100.1 million for the nine months ended September 30, 2025. The increase of $19.6 million was primarily driven by a $26.2 million increase in spend related to the advancement of the vopimetostat and TNG456 clinical programs and a $4.9 million increase from personnel-related costs, including share-based compensation expense. The increase was partially offset by a $4.4 million decrease in development costs for TNG961, a $3.5 million decrease due to the discontinuation of the TNG908 and TNG260 clinical programs, and lower discovery program expenses. The increase was further reduced by decreased spend on lab supplies and services and other facilities related costs.

General and Administrative Expenses

General and administrative expense was $67.0 million for the nine months ended September 30, 2026 compared to $31.7 million for the nine months ended September 30, 2025. The increase of $35.3 million was primarily due to an increase in personnel-related costs, including share-based compensation expense which included increases derived from the modification of previously issued equity awards for our former Executive Chair and former Chief Financial Officer during the nine months ended September 30, 2026. The change also included increased spend on professional fees, including consulting and legal services, and information technology related spend.

Interest Income

Interest income was $13.1 million for the nine months ended September 30, 2026 compared to $4.0 million for the nine months ended September 30, 2025, with the increase primarily attributable to a higher marketable securities balance during the third quarter of 2026 as compared to the same period in the prior year.

Other Income, Net

Other income, net was $4.4 million for the nine months ended September 30, 2026 compared to $2.7 million for the nine months ended September 30, 2025. In both periods, other income, net, was primarily derived from accretion from investments purchased at a discount.

Provision for Income Taxes

Provision for income taxes was less than $0.1 million for each of the nine months ended September 30, 2026 and 2025. The tax provisions were insignificant in each of the nine months ended September 30, 2026 and 2025.

Liquidity and Capital Resources

Sources of Liquidity

Since our inception, we have generated recurring net losses. We have not yet commercialized any products and we do not expect to generate revenue from sales of any products for several years, if at all. To date, we have funded our operations primarily through equity financings and from the proceeds received from the Gilead Agreement. Through September 30, 2026, we have raised an aggregate of $1.8 billion from such transactions, including $1.6 billion in aggregate gross proceeds from the sale of pre-public entity preferred shares, the closing of our Business Combination, follow-on public and private offerings, and through our "at-the-market" offering programs, and $237.1 million pursuant to our collaboration with Gilead, the research portion of which concluded in August 2025. As of September 30, 2026, we had cash and cash equivalents and marketable securities of $977.5 million.

In June 2026, we completed an underwritten public offering for the issuance of a total of 21,166,676 shares of common stock, including 3,000,009 shares pursuant to the exercise of the underwriters' option to purchase additional shares, at a price to the public of $30.00 per share and pre-funded warrants to purchase up to 1,833,395 shares of common stock at a public offering price of $29.999 per pre-funded warrant, which represents the per share public offering price of each share of common stock less the $0.001 per share exercise price for each pre-funded warrant, resulting in gross proceeds of $690.0 million. The pre-funded warrants are immediately exercisable and will remain exercisable until exercised in full. After deducting underwriting discounts and commissions and expenses related to the offering of $38.6 million, net proceeds were $651.4 million.

In November 2025, we entered into the Leerink Sales Agreement, which permits us to sell from time to time, at our option, shares of our common stock through Leerink Partners, as sales agent. Sales of the common stock are made by methods deemed to be "at-the-market" offerings. Leerink Partners is entitled to receive compensation equal to up to 3.0% of the gross sales price of the shares of our common stock sold pursuant to the Leerink Sales Agreement. The Leerink Sales Agreement will terminate upon the earliest of: (a) the sale of all placement shares thereunder or (b) the termination of the Leerink Sales Agreement by us or Leerink Partners. In November 2025, we filed a shelf registration statement on Form S-3ASR with the SEC for which we registered for sale an indeterminate amount of any combination of our common stock, preferred stock, debt securities, warrants, and/or units from time to time during the three-year period that commenced upon the filing of the S-3ASR and at prices and on terms that we may determine. The S-3ASR included a sales agreement prospectus relating to the offer and sale of up to an aggregate of $100.0 million shares of our common stock, pursuant to the Leerink Sales Agreement. In August 2026, we filed a prospectus supplement under the S-3ASR, relating to the offer and sale of up to an aggregate of $400.0 million of shares of our common stock, pursuant to the Leerink Sales Agreement, which includes approximately $35.6 million of unsold shares under the November 2025 sales agreement prospectus. Accordingly, the offering pursuant to the November 2025 sales agreement prospectus has been terminated, and we will not make any further offer or sale of shares pursuant to that prospectus . During the three months ended September 30, 2026, we did not sell any shares of our common stock under the Leerink Sales Agreement and during the nine months ended September 30, 2026, we sold 5,148,151 shares of common stock pursuant to this "at-the-market" offering program for gross proceeds of $64.4 million.

Funding Requirements

We expect that our existing cash, cash equivalents and marketable securities on hand as of September 30, 2026 of $977.5 million will enable us to meet our current operating plan and fund our operating expenses and capital expenditure requirements for at least twelve months from the issuance of the financial statements in this Quarterly Report. We have based this estimate on assumptions that may prove to be wrong, and we could expend our capital resources sooner than we expect.

Cash Flows

Comparison of the nine months ended September 30, 2026 and 2025

The following table summarizes our cash flows for each of the nine month periods presented:

Operating Activities

Net cash used in operating activities was $120.4 million for the nine months ended September 30, 2026 compared to net cash used in operating activities of $109.2 million for the nine months ended September 30, 2025. The increase in net cash used in operating activities for the nine months ended September 30, 2026 was primarily due to an increase in the net loss as a result of higher operating expenses related to the advancement of our clinical programs and personnel-related costs. The increase was partially offset by higher non-cash expenses and a decrease in operating assets and liabilities.

Investing Activities

Net cash used in investing activities was $660.3 million for the nine months ended September 30, 2026 compared to net cash provided by investing activities of $94.9 million for the nine months ended September 30, 2025. The change was primarily due to an increase in purchases of marketable securities, which was partially offset by an increase in sales and maturities of marketable securities as compared to the nine months ended September 30, 2025.

Financing Activities

Net cash provided by financing activities was $754.8 million for the nine months ended September 30, 2026 compared to net cash provided by financing activities of $3.1 million for the nine months ended September 30, 2025. The cash provided by financing activities for the nine months ended September 30, 2026 primarily consisted of $651.4 million in net proceeds received from our June 2026 financing, $62.8 million in net proceeds received from our "at-the-market" offering program, as well as the cash provided from the exercises of stock options and ESPP purchases of $41.3 million during the period. The cash provided by financing activities for the nine months ended September 30, 2025 consisted of the cash provided from the exercises of stock options and ESPP purchases.

Contractual Obligations and Commitments

The following table summarizes our contractual obligations at September 30, 2026 and the effects that such obligations are expected to have on our liquidity and cash flows in future periods:

The commitment amounts in the table above primarily reflect the minimum payments due under our amended operating lease for office and laboratory space at our 201 Brookline Avenue, Boston, Massachusetts location. These commitments are also recognized as operating lease liabilities in our balance sheet at September 30, 2026. Refer to Note 7 to our audited consolidated financial statements and related notes included in our Annual Report on Form 10-K for the year ended December 31, 2025 for additional discussion of the lease.

Purchase Obligations

In the normal course of business, we enter into contracts with third parties for preclinical studies, clinical operations, manufacturing and research and development supplies. These contracts generally do not contain minimum purchase commitments and generally provide for termination with limited notice, and therefore are cancellable contracts. These payments are not included in the table above as the amount and timing of such payments are not known as of September 30, 2026.

License Agreement Obligations

We have also entered into a license agreement under which we may be obligated to make milestone and royalty payments. We have not included future milestone or royalty payments under the agreement in the table above since the payment obligations are contingent upon future events, such as achieving certain development, regulatory, and commercial milestones or generating product sales. As of September 30, 2026 and December 31, 2025, we were unable to estimate the timing or likelihood of achieving these milestones or generating future product sales. Refer to Note 8 of our audited consolidated financial statements and related notes included in our Annual Report on Form 10-K for the year ended December 31, 2025 for a description of our license agreement.

Critical Accounting Policies and Significant Judgments and Estimates

Our consolidated financial statements have been prepared in accordance with U.S. GAAP. The preparation of these consolidated financial statements requires us to make judgments and estimates that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities in our financial statements. We base our estimates on historical experience, known trends and events and various other factors that we believe are reasonable under the circumstances and at the time these estimates are made, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. We evaluate our estimates and assumptions on an ongoing basis. Some of the judgments and estimates we make can be subjective and complex. Our actual results may differ from these estimates under different assumptions or conditions. On an ongoing basis, we evaluate our judgments and estimates in light of changes in circumstances, facts, and experience. The effects of material revisions in estimates, if any, will be reflected in the consolidated financial statements prospectively from the date of change in estimates.

While our significant accounting policies are described in more detail in Note 2 to our audited consolidated financial statements and related notes included in our Annual Report on Form 10-K for the year ended December 31, 2025, we believe that the following accounting policies are those most critical to the judgments and estimates used in the preparation of our financial statements.

Revenue Recognition

The terms of our collaboration agreements may include consideration such as non-refundable up-front payments, license fees, research extension fees, and clinical, regulatory and sales-based milestones and royalties on product sales.

We recognize revenue under ASC 606, Revenue from Contracts with Customers, which applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, collaboration arrangements and financial instruments. ASC 606 provides a five-step framework whereby revenue is recognized when control of promised goods or services is transferred to a customer at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To determine revenue recognition for arrangements that we determine are within the scope of the revenue standard, we perform the following five steps: (i) identify the promised goods or services in the contract; (ii) determine whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measure the transaction price, including the constraint on variable consideration; (iv) allocate the transaction price to the performance obligations; and (v) recognize revenue when (or as) we satisfy each performance obligation. We only apply the five-step model to contracts when collectability of the consideration to which we are entitled in exchange for the goods or services we transfer to the customer is determined to be likely. At contract inception, once the contract is determined to be within the scope of ASC 606, we assess whether the goods or services promised within each contract are distinct and, therefore, represent a separate performance obligation. Goods and services that are determined not to be distinct are combined with

other promised goods and services until a distinct bundle is identified. We then allocate the transaction price (the amount of consideration we expect to be entitled to from a customer in exchange for the promised goods or services) to each performance obligation and recognize the associated revenue when (or as) each performance obligation is satisfied. Our estimate of the transaction price for each contract includes all variable consideration to which we expect to be entitled.

We recognize the transaction price allocated to license payments as revenue upon delivery of the license to the customer and resulting ability of the customer to use and benefit from the license, if the license is determined to be distinct from the other performance obligations identified in the contract. If the license is considered to not be distinct from other performance obligations, we utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied (i) at a point in time, but only for licenses determined to be distinct from other performance obligations in the contract, or (ii) over time; and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from license payments. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition.

We evaluate whether it is probable that the consideration associated with each milestone payment will not be subject to a significant reversal in the cumulative amount of revenue recognized. Amounts that meet this threshold are included in the transaction price using the most likely amount method, whereas amounts that do not meet this threshold are considered constrained and excluded from the transaction price until they meet this threshold. Milestones tied to regulatory approval, and therefore not within our control, are considered constrained until such approval is received. Upfront and ongoing development milestones under our collaboration agreements are not subject to refund if the development activities are not successful. At the end of each subsequent reporting period, we re-evaluate the probability of a significant reversal of the cumulative revenue recognized for the milestones, and, if necessary, adjust the estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues from collaborators in the period of adjustment. We exclude sales-based milestone payments and royalties from the transaction price until the sale occurs (or, if later, until the underlying performance obligation to which some or all of the royalty has been allocated has been satisfied or partially satisfied), because the license to our intellectual property is deemed to be the predominant item to which the royalties relate as it is the primary driver of value.

ASC 606 requires us to allocate the arrangement consideration on a relative standalone selling price basis for each performance obligation after determining the transaction price of the contract and identifying the performance obligations to which that amount should be allocated. The relative standalone selling price is defined in ASC 606 as the price at which an entity would sell a promised good or service separately to a customer. If other observable transactions in which we have sold the same performance obligation separately are not available, we are required to estimate the standalone selling price of each performance obligation. Key assumptions to determine the standalone selling price may include forecasted revenues, development timelines, reimbursement rates for personnel costs, discount rates and probabilities of technical and regulatory success.

Whenever we determine that multiple promises to a customer are not distinct and comprise a combined performance obligation that includes services, we recognize revenue over time using the cost-to-cost input method, based on the total estimated cost to fulfill the obligation. Significant management judgment is required in determining the level of effort required under an arrangement and the period over which we are expected to complete our performance obligations under an arrangement.

Consideration that does not meet the requirements to satisfy the above revenue recognition criteria is a contract liability and is recorded as deferred revenue in the consolidated balance sheets. We have recorded short-term and long-term deferred revenue on our consolidated balance sheets based on our best estimate of when such revenue will be recognized. Short-term deferred revenue consists of amounts that are expected to be recognized as revenue in the next 12 months. Amounts that we expect will not be recognized within the next 12 months are classified as long-term deferred revenue.

In certain instances, the timing of and total costs of satisfying these obligations under our collaboration agreement can be difficult to estimate. Accordingly, our estimates may change in the future. If these estimates and judgments change over the course of these agreements, it may affect the timing and amount of revenue that we will recognize and record in future periods.

Under ASC 606, we will recognize revenue when we fulfill our performance obligations under the agreements with customers. As the required performance obligation is satisfied, we will recognize revenue for the portion satisfied and record a receivable for any fees that have not been received. Amounts are recorded as short-term collaboration receivables when our right to consideration is unconditional. A contract liability is recognized when a customer prepays consideration or owes payment to an entity in advance of our performance according to a contract. We do not assess whether a contract has a significant financing component if the expectation at contract inception is that the period between payment by the customer and the transfer of the promised goods or services to the customer will be one year or less. We expense incremental costs of obtaining a contract as and when incurred if the expected amortization period of the asset that we would have recognized is one year or less or the amount is immaterial.

Accrued Research and Development Expenses

As part of the process of preparing our consolidated financial statements, we are required to estimate our accrued research and development expenses. This process involves estimating the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of actual costs. The majority of our service providers invoice us in arrears for services performed, on a pre-determined schedule or when contractual milestones are met; however, some require advance payments, which would be recorded as a prepaid expense in other assets, or if there is the right of offset, offset against our liability balance with the counterparty. We make estimates of our accrued expenses as of each balance sheet date in the consolidated financial statements based on facts and circumstances known to us at that time. At each period end, we corroborate the accuracy of these estimates with the service providers and make adjustments, if necessary.

We record the expense and accrual related to research and development activities performed by our vendors based on our estimates of the services received and efforts expended considering a number of factors, including our knowledge of the progress towards completion of the research and development activities; invoicing to date under the contracts; communication from the vendors of any actual costs incurred during the period that have not yet been invoiced; and the costs included in the contracts and purchase orders. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. There may be instances in which payments made to our vendors will exceed the level of services provided and result in a prepayment of the expense. In accruing service fees, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, we adjust the accrual or prepaid expense accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, our understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in reporting amounts that are too high or too low in any particular period. To date, there have not been any material adjustments to our prior estimates of accrued research and development expenses.

Recently Adopted Accounting Pronouncements

A description of recently issued and adopted accounting pronouncements that may potentially impact our financial position, results of operations or cash flows is disclosed within Note 2 of our unaudited condensed consolidated financial statements and related notes appearing elsewhere in this Quarterly Report on Form 10-Q and also in Note 2 to our audited consolidated financial statements and related notes in our Annual Report on Form 10-K for the year ended December 31, 2025.