Material Agreement (Form 8-K)

Item 1.01. Entry into a Material Definitive Agreement.

On August 21, 2026, OS Therapies Incorporated (the "Company") entered into an Open Market Sale Agreement℠ (the "Sales Agreement") with Jefferies LLC (the "Sales Agent"), pursuant to which the Company may offer and sell shares of its common stock from time to time through or to the Sales Agent in connection with the Company's "at the market offering" program (the "ATM Offering").

On August 21, 2026, the Company filed with the Securities and Exchange Commission (the "SEC") a prospectus supplement (the "Prospectus Supplement") relating to the ATM Offering under the Company's shelf registration statement on Form S-3 (File No. 333-289443) filed by the Company with the SEC on August 8, 2025 and declared effective by the SEC on August 25, 2025 (the "Registration Statement"). Pursuant to the Prospectus Supplement, the Company may offer and sell shares of its common stock having an aggregate offering price of up to $75 million pursuant to the Sales Agreement (the "Shares").

From time to time during the term of the Sales Agreement, the Company may deliver a placement notice to the Sales Agent specifying the length of the selling period, the amount of Shares to be sold, any limitation on the number of Shares that may be sold in any one trading day and the minimum price below which sales may not be made. Upon its acceptance of the placement notice from the Company, the Sales Agent will use its commercially reasonable efforts consistent with its normal trading and sales practices to solicit offers to purchase Shares, under the terms and subject to the conditions set forth in the Sales Agreement, in transactions that are deemed to be an "at the market offering" as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended (the "Securities Act"), in block transactions, sales made directly on the Principal Market (as defined in the Sales Agreement) or sales made into any other existing trading markets of the Shares. The Company may instruct the Sales Agent not to sell Shares if the sales cannot be effected at or above the price designated by the Company in any placement notice. The Company or the Sales Agent may suspend the offering of the Shares at any time upon proper notice and subject to other conditions.

The Company will pay the Sales Agent a commission equal to 3.0% of the aggregate gross proceeds the Company receives from each sale of Shares pursuant to the Sales Agreement. In addition, we have agreed to reimburse the Sales Agent for the fees and disbursements of its counsel, payable upon execution of the Sales Agreement, in an amount not to exceed $100,000, in addition to certain ongoing disbursements of its legal counsel.

Under the terms of the Sales Agreement, the Company also may sell Shares to the Sales Agent, as principal for its own account, at a price to be agreed upon at the time of sale.

The ATM Offering of the Shares pursuant to the Sales Agreement will terminate upon the earlier of (i) the sale of all Shares subject to the Sales Agreement and (ii) the termination of the Sales Agreement as permitted therein. The Company and the Sales Agent may each terminate the Sales Agreement at any time upon 10 days' prior notice.

The Company made certain customary representations, warranties and covenants concerning the Company and the Shares in the Sales Agreement and agreed to indemnify the Sales Agent against certain liabilities, including liabilities under the Securities Act.

A copy of the Sales Agreement is filed as Exhibit 1.1 hereto and is incorporated herein by reference. The foregoing description of the material terms of the Sales Agreement does not purport to be complete and is qualified in its entirety by reference to such exhibit.