OS Therapies Inc
For the period ended Jun 30, 2026. Filed Aug 14, 2026.
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A company's report for each of its first three quarters. The financial statements are not audited. It shows how the business has moved since the last annual report, and what management says changed.
Jun 30, 2026 · Filed Aug 14, 2026
OSTX$1.00+2.0%Stored close · as of Nov 6, 2026
What changed in Management’s Discussion and Analysis?
Read the current filingPrevious report: 10-Q
Period ended 2026-03-31; filed 2026-05-18.
0001213900-26-058070
Item 2. Management’s Discussion and Analysis of Financial Condition and Results of OperationsCurrent report: 10-Q
Period ended 2026-06-30; filed 2026-08-14.
0001213900-26-090238
Item 2. Management’s Discussion and Analysis of Financial Condition and Results of OperationsThe baseline is this issuer’s latest earlier reporting period of the same form that was filed before the current report. A previous 10-Q is a different quarter, not a year-over-year comparison. Amendments are excluded.
Compared 94 previous paragraphs and 113 current paragraphs.
49 unchanged; 24 reworded; 37 added; 20 removed; 1 previous and 3 current paragraphs rearranged.
Tables are not compared: 15 previous and 16 current tables excluded. Dates, whitespace, punctuation and numbering changes are ignored; changes to financial figures remain significant.
A changed paragraph is not evidence that risk increased or decreased. An unchanged paragraph does not establish that risk stayed the same.
Added paragraphs (37)
Current report
Termination of Prior Sales Agreement
Current report
On August 8, 2025, we entered into an at market issuance sales agreement with B. Riley Securities, Inc. and JonesTrading Institutional Services LLC (the “Prior Sales Agreement”), pursuant to which we could offer and sell shares of our common stock having an aggregate offering price of up to $18,000,000. Effective as of July 28, 2026, we terminated the Prior Sales Agreement. At the time of termination, we had sold an aggregate of 282,679 shares of our common stock for aggregate gross proceeds of approximately $530,162 under the Prior Sales Agreement and the related prospectus supplement dated August 25, 2025 (the “Prior Prospectus Supplement”), and approximately $17,469,838 remained unsold thereunder. No further shares of our common stock may or will be offered or sold under the Prior Sales Agreement or the Prior Prospectus Supplement.
Current report
Leonite Secured Financing
Current report
On June 30, 2026, we, together with our wholly owned subsidiaries, entered into a securities purchase agreement (the “Leonite SPA”) with Leonite Fund I, LP (“Leonite”) and related transaction documents, pursuant to which we issued and sold to Leonite, in a private placement (the “Leonite Private Placement”), a senior secured convertible promissory note in an aggregate principal amount of up to $10,000,000 (the “Leonite Note”). As additional consideration for Leonite’s purchase of the Leonite Note, we issued to Leonite (i) 275,000 shares of our common stock (the “Leonite Commitment Shares”) and (ii) a five-year warrant to purchase up to 1,750,000 shares of our common stock (the “Leonite Warrant”) an initial exercise price of $2.85 per share, subject to adjustment as provided therein.
Current report
Pursuant to the Leonite SPA, Leonite agreed to purchase the Leonite Note in one or more tranches, in an aggregate principal amount of up to $10,000,000. Each funded tranche was subject to an original issue discount of 7.5%, which was included in the principal amount of the Leonite Note and was earned only upon the funding of such tranche. On July 2, 2026, Leonite funded the initial tranche in the principal amount of $1,600,000 (less $35,000 retained by Leonite for legal fees and expenses).
Current report
The Leonite Note was secured by a continuing first-priority security interest in substantially all of our and our subsidiaries’ existing and after-acquired assets, subject to certain exclusions, including intellectual property assets. Notwithstanding such exclusions, the collateral included accounts, payment intangibles and other rights to payment arising from the sale, license or other disposition of intellectual property.
Current report
Leonite Settlement
Current report
On July 31, 2026, we, together with our wholly owned subsidiaries, entered into the Leonite Settlement Agreement, pursuant to which we paid Leonite $1,900,000 in cash (the “Settlement Payment”) and issued to Leonite 500,000 shares of our common stock (the “Settlement Shares”) on August 3, 2026 and August 6, 2026, respectively, in full and complete satisfaction of all amounts outstanding under the Leonite Note and the other transaction documents related to the Leonite Private Placement (the “Leonite Settlement”).
Current report
On August 2, 2026, in connection with the Leonite Settlement, we issued to an accredited investor a bridge convertible promissory note in the principal amount of $2,200,000 (the “August Bridge Note”) for a purchase price of $2,190,000 (the “August Bridge Financing”). The August Bridge Note did not bear interest and was scheduled to mature on September 1, 2026, unless earlier converted by the holder. Upon the initial closing of a private offering by us of original issue discount promissory notes in an aggregate principal amount of up to $10,000,000, the outstanding principal amount of the August Bridge Note would automatically convert into the securities issued in such offering on the same terms as the other purchasers in the offering.
Current report
In accordance with the terms of the August Bridge Note, we used the proceeds from the August Bridge Financing to fund the Settlement Payment.
Current report
The closing of the Leonite Settlement occurred on August 6, 2026, effective as of which closing: (i) the Leonite Note and all amounts outstanding thereunder were deemed fully paid, satisfied, discharged and cancelled, and all conversion rights thereunder terminated; (ii) the Leonite Warrant terminated and was cancelled in its entirety, unexercised; (iii) the Leonite Commitment Shares were surrendered by Leonite to us for cancellation; (iv) the Leonite SPA, the related security agreement and all other transaction documents entered into in connection with the Leonite Private Placement terminated and ceased to be of any further force or effect, including all rights of Leonite under the participation rights, rights of first refusal, future financing rights, disclosure rights relating to future financings, rollover rights and registration rights provisions of the Leonite SPA; and (v) all security interests, liens, pledges and other collateral granted to or for the benefit of Leonite were automatically, unconditionally and irrevocably released, terminated and discharged, and all assets assigned to Leonite by OS Therapies UK Ltd., our wholly owned subsidiary (“OSUK”), including value-added tax repayments and research and development tax relief claims, reverted to OSUK free and clear of any claim or lien of Leonite.
Current report
2026 OID Secured Note Financing
Current report
On August 10, 2026, we, together with our wholly owned subsidiaries, entered into a securities purchase agreement (the “2026 OID Secured Note SPA”) with the purchasers signatory thereto, pursuant to which we agreed to issue and sell to such purchasers, in a private placement (the “August Private Placement”), senior secured convertible promissory notes in an aggregate subscription amount of up to $10,000,000 (each, a “Secured Note” and, collectively, the “Secured Notes”), consisting of (i) an initial tranche with an aggregate subscription amount of up to $5,000,000 (the “First Tranche”) and (ii) a second tranche with an aggregate subscription amount of up to $5,000,000 (the “Second Tranche” and, together with the First Tranche, the “Tranches,” and each, a “Tranche”). Each Secured Note purchased pursuant to the 2026 OID Secured Note SPA will be issued with an original issue discount equal to 7.5% of the principal amount of such Secured Note (the “OID”).
Current report
Pursuant to the 2026 OID Secured Note SPA, each purchaser may subscribe for one or more units (each, a “Unit”) at a purchase price of $100,000 per Unit, consisting of (i) a Secured Note in the principal amount of $108,108.11, reflecting the applicable OID, (ii) 30,000 shares of our common stock or, in lieu thereof, pre-funded warrants to purchase up to 30,000 shares of our common stock, and (iii) five-year warrants to purchase up to 30,000 shares of our common stock.
Current report
On August 10, 2026, we consummated the closing of the First Tranche (the “Initial Closing”), pursuant to which the purchasers purchased an aggregate of $5,000,000 of Units (inclusive of the August Bridge Note conversion described below), and we issued to such purchasers (i) Secured Notes in an aggregate principal amount of $5,405,405.42, (ii) an aggregate of 600,000 shares of our common stock, (iii) pre-funded warrants to purchase up to an aggregate of 900,000 shares of our common stock and (iv) warrants to purchase up to an aggregate of 1,500,000 shares of our common stock.
Current report
At the Initial Closing, the August Bridge Note automatically converted, in accordance with the terms of the 2026 OID Secured Note SPA, into (i) a Secured Note in the principal amount of $2,378,378.38, (ii) a pre-funded warrant to purchase up to 660,000 shares of our common stock and (iii) a warrant to purchase 660,000 shares of our common stock. Upon such conversion, the August Bridge Note was automatically terminated, cancelled and satisfied in full.
Current report
The Secured Notes bear interest at a rate of 9.0% per annum, payable monthly in arrears. Interest accrues on each Secured Note from the date the applicable Tranche is funded by the applicable purchaser (the “advance date”). Notwithstanding any conversion, prepayment, repayment or acceleration of the Secured Notes prior to the expiration of 12 months following the applicable advance date, the holder is entitled to receive a minimum amount of interest equal to one full year of interest calculated at the applicable interest rate on the original principal amount of such Tranche. Each Tranche of the Secured Notes matures on the date that is nine months following the applicable advance date. Each Secured Note is convertible, at the holder’s option, in whole or in part, into shares of our common stock at a conversion price of $2.05 per share, subject to adjustment as provided therein. Subject to the terms of the applicable Secured Note, a conversion of such Secured Note may be effected at any time from and after the date that is 90 days following the applicable advance date for the applicable Tranche.
Current report
The Secured Notes are secured by a continuing first-priority security interest in substantially all of the existing and after-acquired assets of our company and our subsidiaries, subject to certain exclusions, including intellectual property assets. Notwithstanding such exclusions, the collateral includes accounts, payment intangibles and other rights to payment arising from the sale, license or other disposition of intellectual property.
Current report
The warrants issued in connection with the First Tranche have an exercise price of $2.85 per share, subject to adjustment as provided therein, and are exercisable in whole or in part at any time from the issuance date through August 10, 2031. Any warrants issued in connection with the Second Tranche will have an exercise price per share equal to 190% of the closing price of our common stock on the applicable closing date of the Second Tranche and will be exercisable in whole or in part for a period of five years following such date.
Current report
On August 6, 2026, we engaged Ceros to act as our exclusive placement agent in connection with the August Private Placement. We agreed to pay Ceros a cash fee equal to 5.0% of the aggregate subscription amount paid by the purchasers for Units purchased in each Tranche. We also agreed to pay Ceros a non-accountable expense fee of $60,000 upon consummation of the Initial Closing and to reimburse Ceros for its reasonable out-of-pocket expenses incurred in connection with any subsequent closing, subject to a maximum aggregate reimbursement of $25,000.
Current report
We also agreed to issue to Ceros or its designees five-year warrants to purchase a number of shares of our common stock equal to 5% of the aggregate number of shares of common stock issuable upon exercise of the warrants issued in the August Private Placement, at an exercise price equal to 110% of the applicable warrant exercise price. In connection with the Initial Closing, we issued to Ceros’s designees placement agent warrants to purchase up to an aggregate of 75,000 shares of our common stock at an exercise price of $3.14 per share, subject to adjustment as provided therein.
Current report
We intend to use the net proceeds of the August Private Placement to fund clinical development and regulatory activities, as well as for working capital and other general corporate purposes.
Current report
Pursuant to the 2026 OID Secured Note SPA, we have agreed to prepare and file with the SEC, within 30 days following August 10, 2026, a registration statement covering the resale by the purchasers of their respective shares of our common stock issued and issuable upon conversion of the Secured Notes and exercise of the warrants and pre-funded warrants issued in the Initial Closing. We have agreed to use commercially reasonable efforts to cause such registration statement to be declared effective by the SEC no later than 120 days following August 10, 2026, and to keep such registration statement continuously effective until the earlier of (i) the date on which all such registrable securities have been sold and (ii) the date on which all such registrable securities may be sold without restriction or volume limitations pursuant to Rule 144. We have also agreed, within 30 days following each subsequent closing, to file such amendments, supplements or post-effective amendments to the registration statement as may be necessary to include additional registrable securities issued or issuable pursuant to the 2026 OID Secured Note SPA in connection with such subsequent closing.
Current report
We were able to apply for refunds of UK value-added tax (“VAT”) by filing VAT returns in April 2026 and August 2026. Prior to obtaining our VAT number, we were unable to recognize a receivable for the VAT and, accordingly, the VAT was included in research and development (“R&D”) expenses in 2025 and the first quarter of 2026. Upon obtaining our VAT number and becoming eligible to file VAT returns, we recognized the accumulated VAT as a refund receivable and recorded a reduction to R&D expenses of $1.96 million in the second quarter of 2026.
Current report
***Research and Development Expenses.***Research and development expenses were approximately $13.4 million for the six months ended June 30, 2026, compared to approximately $3.8 million for the six months ended June 30, 2025. This increase was primarily due to an increase in vendor expenses associated with our Phase IIb clinical trial, as we compiled data to submit to various governmental agencies. The increase was partially offset by the recognition of a $1.96 million VAT receivable in the second quarter of 2026. We determined that the input VAT associated with our UK subsidiary was realizable and, upon obtaining our VAT number and becoming eligible to file VAT returns, recognized the accumulated VAT as a receivable, resulting in a corresponding reduction in R&D expenses.
Current report
The following table summarizes our research and development expenses for the three and six months ended June 30, 2026 and 2025:
Current report
For the six months ended June 30, 2026 and 2025, the direct research and development expenses related to OST-HER2 were primarily lab fees, vendor expenses and staff payroll costs. In 2026, such expenses consisted primarily of lab fees and related clinical support of approximately $0.15 million attributable to preparation for our Phase IIb clinical trial, advisor fees of approximately $12.2 million, and legal costs of approximately $0.0 million, compared to 2025, when such expenses consisted primarily of lab fees and related clinical support of approximately $0.9 million attributable to preparation for our Phase IIb clinical trial, advisor fees of approximately $1.9 million, and legal costs of approximately $0.1 million.
Current report
For the three months ended June 30, 2026 and 2025, the direct research and development expenses related to OST-HER2 were primarily lab fees, vendor expenses and staff payroll costs. In 2026, such expenses consisted primarily of lab fees and related clinical support of approximately $0.1 million attributable to preparation for our Phase IIb clinical trial and advisor fees of approximately $5.5 million, compared to 2025, when such expenses consisted primarily of lab fees and related clinical support of approximately $0.6 million attributable to preparation for our Phase IIb clinical trial and advisor fees of approximately $1.4 million.
Current report
***Interest Expense.***Interest expense was approximately $0.1 million for the six months ended June 30, 2026, compared to $0.0 million for the six months ended June 30, 2025. Interest expense in 2026 primarily related to the amortization of debt issuance costs and accretion of interest on our March 2026 bridge convertible notes.
Current report
Leonite Secured Financing and Settlement. On June 30, 2026, we entered into the Leonite SPA and related transaction documents, pursuant to which we issued and sold to Leonite, in the Leonite Private Placement, the Leonite Note in an aggregate principal amount of up to $10,000,000, 275,000 Leonite Commitment Shares and the Leonite Warrant to purchase up to 1,750,000 shares of our common stock at an initial exercise price of $2.85 per share, subject to adjustment as provided therein. On July 2, 2026, Leonite funded the initial tranche in the principal amount of $1,600,000 (less $35,000 retained by Leonite for legal fees and expenses).
Current report
On August 6, 2026, we consummated the Leonite Settlement, pursuant to which we paid Leonite $1,900,000 in cash and issued to Leonite 500,000 Settlement Shares in full and complete satisfaction of all amounts outstanding under the Leonite Note and the other transaction documents related to the Leonite Private Placement.
Current report
In connection with the Leonite Settlement, we issued to an accredited investor the August Bridge Note in the principal amount of $2,200,000 for a purchase price of $2,190,000. In accordance with the terms of the August Bridge Note, we used the proceeds from the August Bridge Financing to fund the Settlement Payment.
Current report
Effective as of the closing of the Leonite Settlement: (i) the Leonite Note and all amounts outstanding thereunder were deemed fully paid, satisfied, discharged and cancelled, and all conversion rights thereunder terminated; (ii) the Leonite Warrant terminated and was cancelled in its entirety, unexercised; (iii) the Leonite Commitment Shares were surrendered by Leonite to us for cancellation; (iv) the Leonite SPA, the related security agreement and all other transaction documents entered into in connection with the Leonite Private Placement terminated and ceased to be of any further force or effect, including all rights of Leonite under the participation rights, rights of first refusal, future financing rights, disclosure rights relating to future financings, rollover rights and registration rights provisions of the Leonite SPA; and (v) all security interests, liens, pledges and other collateral granted to or for the benefit of Leonite were automatically, unconditionally and irrevocably released, terminated and discharged, and all assets assigned to Leonite by OSUK, including value-added tax repayments and research and development tax relief claims, reverted to OSUK free and clear of any claim or lien of Leonite.
Current report
2026 OID Secured Note Financing. On August 10, 2026, we consummated the Initial Closing of the August Private Placement, pursuant to which the purchasers thereto purchased an aggregate of $5,000,000 of Units (inclusive of the August Bridge Note conversion described below), and we issued to such purchasers (i) Secured Notes in an aggregate principal amount of $5,405,405.42, (ii) an aggregate of 600,000 shares of our common stock, (iii) pre-funded warrants to purchase up to an aggregate of 900,000 shares of our common stock and (iv) warrants to purchase up to an aggregate of 1,500,000 shares of our common stock.
Current report
At the Initial Closing, the August Bridge Note automatically converted, in accordance with the terms of the 2026 OID Secured Note SPA, into (i) a Secured Note in the principal amount of $2,378,378.38, (ii) a pre-funded warrant to purchase up to 660,000 shares of our common stock and (iii) a warrant to purchase 660,000 shares of our common stock. Upon such conversion, the August Bridge Note was automatically terminated, cancelled and satisfied in full.
Current report
In connection with the August Private Placement, Ceros acted as our exclusive placement agent. We paid Ceros a cash fee of $250,000 in connection with the Initial Closing. We also paid Ceros a non-accountable expense fee of $60,000 upon consummation of the Initial Closing. As additional consideration, we issued to Ceros’s designees placement agent warrants to purchase up to an aggregate of 75,000 shares of our common stock at an exercise price of $3.14 per share, subject to adjustment as provided therein.
Current report
We intend to use the net proceeds of the August Private Placement to fund clinical development and regulatory activities, as well as for working capital and other general corporate purposes.
Removed paragraphs (20)
Previous report
2026 Warrant Exercise Inducement and Exchange Offer
Previous report
On January 14, 2026, we closed on a warrant exercise inducement and exchange offer (the “2026 Inducement Offering”). The 2026 Inducement Offering was made to less than 10 accredited investors that held certain of our existing warrants to purchase up to an aggregate of 5,382,148 shares of our common stock having a then current exercise price of $3.00 or $2.10 per share during the period beginning January 10, 2026 and ending at 11:59 p.m., Eastern time, on March 2, 2026 (the “2026 Inducement Period”).
Previous report
During the 2026 Inducement Period, we entered into inducement offer letter agreements with such holders, pursuant to which such holders exercised for cash their existing warrants to purchase an aggregate of 2,499,558 shares of our common stock at a reduced exercise price of $1.40 per share and in exchange we issued to such holders new warrants (the “2026 Warrants”) to purchase up to an aggregate of 2,499,558 shares of our common stock (the “2026 Warrant Shares”) at an exercise price of $1.40 per share, subject to adjustment as provided therein. The 2026 Warrants are exercisable for a period of five years from the date of issuance.
Previous report
We engaged Ceros Financial Services, Inc. (“Ceros”) to act as our exclusive warrant solicitation agent in connection with the 2026 Inducement Offering and paid Ceros a cash fee equal to 8.0% of the total gross cash proceeds received from the exercise by the holders of their respective warrants during the 2026 Inducement Period and in connection with the 2026 Inducement Offering. We also paid Ceros $25,000 for its legal and other expenses.
Previous report
The gross proceeds to us from the 2026 Inducement Offering, before deducting transaction fees and other 2026 Inducement Offering expenses, were approximately $3.5 million. We are using the net proceeds from the 2026 Inducement Offering to support U.S. and international regulatory and pre-commercial efforts aimed at securing marketing authorizations for OST-HER2 in the prevention or delay of recurrent, fully resected, lung metastatic Osteosarcoma, provide funding for our wholly owned subsidiary OS Animal Health’s proposed spinoff transaction preparations, and for general corporate purposes.
Previous report
Privately Negotiated Warrant Exercise Inducement and Exchange Agreements
Previous report
From January 10, 2026 through February 2026, we entered into privately negotiated inducement offer letters, pursuant to which certain holders of our existing warrants having a then current exercise price of $3.00 or $2.10 per share exercised for cash their existing warrants to purchase an aggregate of 123,216 shares of our common stock at a reduced exercise price of $1.40 per share and in exchange we issued 2026 Warrants to purchase up to an aggregate of 123,216 shares of our common stock at an exercise price of $1.40 per share, subject to adjustment as provided therein (such transactions, the “Private Inducement Transactions”). The 2026 Warrants are exercisable for a period of five years from the date of issuance. We received gross proceeds of approximately $172,502 from the Private Inducement Transactions.
Previous report
2026 Bridge Financing
Previous report
On March 4, 2026, pursuant to a securities purchase agreement (the “Bridge SPA”), we issued to certain accredited investors in a private placement transaction (i) 10.0% original issue discount unsecured convertible promissory notes in an aggregate principal amount of $2,200,000 (the “Bridge Notes”) and (ii) warrants to purchase up to an aggregate of 1,666,667 shares of our common stock (the “Bridge Warrants” and such private placement transaction, the “Bridge Financing”), for aggregate gross proceeds of $2,000,000, before deducting placement agent fees and other Bridge Financing expenses. The Bridge Notes were scheduled to mature on March 4, 2027 and accrued interest at a rate of 4.0% per annum. The Bridge Warrants were immediately exercisable upon issuance, expire five years from the date of issuance and have an exercise price of $1.40 per share, subject to adjustment as provided therein.
Previous report
The Bridge Notes were sold at a 10% original issue discount, such that for each $100,000 invested by a purchaser, such purchaser received a Bridge Note in the principal amount of $110,000. The Bridge Notes were convertible into shares of our common stock or other of our securities under certain circumstances. Upon the consummation of a “Qualified Offering,” defined as a registered public offering or registered direct offering resulting in at least $2.5 million in gross proceeds from new money investments, the outstanding principal, together with all accrued and unpaid interest, were to automatically convert into the securities sold in such offering at the offering price. Additionally, prior to any such Qualified Offering or repayment of the Bridge Notes, holders could elect to convert the Bridge Notes, in whole or in part, into shares of our common stock at a conversion price equal to 90% of the average daily volume-weighted average price of our common stock during the 10 trading days immediately preceding the holder’s conversion notice, subject to adjustment.
Previous report
We are using the net proceeds of the Bridge Financing to fund clinical development activities, including ongoing and planned clinical trials, and advance our research and development programs, as well as for working capital and general corporate purposes.
Previous report
We engaged Ceros to act as the exclusive placement agent for the Bridge Financing. In connection with the Bridge Financing, we paid to Ceros (a) a cash fee equal to 7.0% of the aggregate gross cash proceeds received by us in connection with the Bridge Financing and (b) a one-time expense reimbursement of $25,000 for its legal and other expenses incurred in connection with the Bridge Financing.
Previous report
Warrant Exercise Inducement and Exchange Offers. On July 11, 2025, we completed a final closing of a warrant exercise inducement and exchange offer. On September 2, 2025, we closed on a second warrant exercise inducement and exchange offer. On January 14, 2026, we closed on a third warrant exercise inducement and exchange offer. The first inducement offering and second inducement offering were made to holders of certain of our Series A warrants issued in connection with our PIPE financing in December 2024 and January 2025 to purchase shares of our common stock having a then current exercise price of $1.12 per share.
Previous report
Pursuant to certain inducement offer letter agreements, holders of such warrants exercised for cash their warrants to purchase an aggregate of 7,154,338 shares of our common stock at the then current exercise price of $1.12 per share and in exchange we issued to such holders new warrants to purchase up to an aggregate of 7,154,338 shares of our common stock at an exercise price of $3.00 per share, subject to adjustment as provided therein.
Previous report
The third inducement offering was made to less than 10 accredited investors that held warrants issued in connection with the first and second inducement offerings to purchase up to an aggregate of 5,382,148 shares of our common stock having a then current exercise price of $3.00 or $2.10 per share. Pursuant to certain inducement offer letter agreements, such holders of such warrants exercised for cash their warrants to purchase 2,499,558 shares of our common stock at a reduced exercise price of $1.40 per share and in exchange we issued to such holders new warrants to purchase up to an aggregate of 2,499,558 shares of our common stock at an exercise price of $1.40 per share, subject to adjustment as provided therein.
Previous report
We engaged a Ceros to act as our exclusive warrant solicitation agent in connection with these inducement offerings and paid Ceros a cash fee equal to 5.0%, 1.5% and 8.0% of the total gross cash proceeds received from the exercise by the holders of their respective warrants in connection with the first inducement offering, second inducement offering and third inducement offering, respectively. We also paid Ceros $15,000 and $25,000 for its reasonable legal and other expenses in connection with the first inducement offering and third inducement offering, respectively.
Previous report
The gross proceeds to us from these inducement offerings, before deducting transaction fees and other offering expenses, were approximately $11.5 million. We are using the net proceeds from the inducement offerings to support U.S. and international regulatory and pre-commercial efforts aimed at securing marketing authorizations for OST-HER2 in the prevention or delay of recurrent, fully resected, pulmonary metastatic Osteosarcoma, provide funding for our wholly owned subsidiary OS Animal Health’s proposed spin-off transaction preparations, and for general corporate purposes.
Previous report
Privately Negotiated Warrant Exercise Inducement and Exchange Agreements. From January 10, 2026 through March 2026, we entered into privately negotiated inducement offer letters, pursuant to which certain remaining holders of warrants issued in the first and second inducement offerings exercised for cash their warrants to purchase an aggregate of 123,216 shares of our common stock at a reduced exercise price of $1.40 per share and in exchange we issued new warrants to purchase up to an aggregate of 123,216 shares of our common stock at an exercise price of $1.40 per share, subject to adjustment as provided therein. We received gross proceeds of approximately $172,502 from the exercise of these new warrants.
Previous report
2026 Bridge Financing. On March 4, 2026, pursuant to the Bridge SPA, we issued to certain accredited investors in the Bridge Financing (i) Bridge Notes in an aggregate principal amount of $2,200,000 and (ii) Bridge Warrants to purchase up to an aggregate of 1,666,667 shares of our common stock, for aggregate gross proceeds of $2,000,000, before deducting placement agent fees and other Bridge Financing expenses. The Bridge Notes were sold at a 10% original issue discount, such that for each $100,000 invested by a purchaser, such purchaser received a Bridge Note in the principal amount of $110,000. We are using the net proceeds of the Bridge Financing to fund clinical development activities, including ongoing and planned clinical trials, and advance our research and development programs, as well as for working capital and general corporate purposes.
Previous report
We engaged Ceros to act as the exclusive placement agent for the Bridge Financing. In connection with the Bridge Financing, we paid to Ceros (a) a cash fee equal to 7.0% of the aggregate gross cash proceeds received by us in connection with the Bridge Financing and (b) a one-time expense reimbursement of $25,000 for its legal and other expenses incurred in connection with the Bridge Financing.
Reworded paragraphs (24)
Previous wording
In 2021, we opened a clinical study to produce data for the U.S. Food and Drug Administration (FDA) to evaluate the safety and efficacy of OST-HER2 in patients after resection of recurrent Osteosarcoma, which achieved full enrollment of 41 patients in October 2023. In the first quarter of 2025, we announced that our Phase IIb clinical trial achieved its primary endpoint with statistical significance. In October 2025, we announced final two-year overall survival data from the Phase IIb trial, in which 75% (27 of 36 evaluable patients) of OST-HER2-treated patients achieved two-year overall survival from the most recent pulmonary resection, compared with 40% in historical control patients (p < 0.0001). OST-HER2 was observed to be well-tolerated in the study. In January 2026, we announced positive immune biomarker data from the Phase IIb trial indicating that activation of immune blood biomarkers in the interferon gamma pathway correlated with, and was predictive of, overall survival, distinguishing long-term survivors (≥ two years) from short-term survivors (< one year). These biomarker findings are based on exploratory analyses and have not been validated as surrogate endpoints for clinical benefit.
Current wording
In 2021, we opened a clinical study to produce data for the U.S. Food and Drug Administration (FDA) to evaluate the safety and efficacy of OST-HER2 in patients after resection of recurrent Osteosarcoma, which achieved full enrollment of 41 patients in October 2023. In the first quarter of 2025, we announced that our Phase IIb clinical trial achieved its primary endpoint with statistical significance. In October 2025, we announced final two-year overall survival data from the Phase IIb trial, in which 75% (27 of 36 evaluable patients) of OST-HER2-treated patients achieved two-year overall survival from the most recent pulmonary resection, compared with 60% in historical control patients (p = 0.034). OST-HER2 was observed to be well-tolerated in the study. In January 2026, we announced positive immune biomarker data from the Phase IIb trial indicating that activation of immune blood biomarkers in the interferon gamma pathway correlated with, and was predictive of, overall survival, distinguishing long-term survivors (≥ two years) from short-term survivors (< one year). These biomarker findings are based on exploratory analyses and have not been validated as surrogate endpoints for clinical benefit. In May 2026, we announced that the Phase IIb trial demonstrated a statistically significant overall survival benefit at the 2.5-year timepoint, with 75% overall survival in OST-HER2-treated patients compared with 47% in pooled historical control patients (p = 0.003). No new patient deaths were reported in the OST-HER2-treated group between the two-year and 2.5-year analyses.
Previous wording
We have engaged in ongoing regulatory interactions with the FDA, the United Kingdom Medicines and Healthcare products Regulatory Agency (MHRA), and the European Medicines Agency (EMA) regarding the clinical and biomarker data for OST-HER2 in recurrent, fully resected pulmonary metastatic Osteosarcoma. We anticipate submitting the clinical Biologics License Application (BLA) module following an expected Type B meeting with the FDA in the second quarter of 2026 and completing conditional Marketing Authorization Application (MAA) submissions to both the MHRA and the EMA in the second quarter of 2026. We also anticipate releasing additional biomarker data in the second quarter of 2026 to further characterize immune pathway activation and its relationship to clinical outcomes. We expect to initiate confirmatory clinical studies in the third quarter of 2026 in support of conditional approval pathways. If OST-HER2 receives approval under the FDA’s Accelerated Approval Program prior to September 30, 2029, we would become eligible to receive a Priority Review Voucher under the Rare Pediatric Disease Designation Program.
Current wording
We have engaged in ongoing regulatory interactions with the FDA, the United Kingdom Medicines and Healthcare products Regulatory Agency (MHRA), and the European Medicines Agency (EMA) regarding the clinical and biomarker data for OST-HER2 in recurrent, fully resected pulmonary metastatic Osteosarcoma. We anticipate submitting the clinical Biologics License Application (BLA) module following an expected Type C meeting with the FDA in the September 2026 and completing conditional Marketing Authorization Application (MAA) submissions to both the MHRA and the EMA in the first quarter of 2027. We also anticipate releasing additional biomarker data in October 2026 to further characterize immune pathway activation and its relationship to clinical outcomes. We expect to initiate confirmatory clinical studies in October 2026 in support of conditional approval pathways. If OST-HER2 receives approval under the FDA’s Accelerated Approval Program prior to September 30, 2029, we would become eligible to receive a Priority Review Voucher under the Rare Pediatric Disease Designation Program.
Previous wording
On April 2, 2026, we completed a registered direct offering, pursuant to which we offered and sold to accredited investors an aggregate of 2,505,073 shares of our common stock and, in lieu thereof, pre-funded warrants to purchase up to 1,250,893 shares of our common stock, and accompanying common warrants to purchase up to 3,755,966 shares of our common stock (the “2026 Registered Direct Offering”). The combined purchase price for each share and common warrant in the 2026 Registered Direct Offering was $1.40, and the purchase price for each pre-funded warrant and common warrant in the 2026 Registered Direct Offering was $1.399, which was equal to the per share and common warrant purchase price, minus $0.001. We received net proceeds from the 2026 Registered Direct Offering of approximately $4.7 million. We are using the net proceeds to fund clinical development activities, including ongoing and planned clinical trials, advance our research and development programs, as well as for working capital and other general corporate purposes.
Current wording
On April 2, 2026, we completed a registered direct offering, pursuant to which we offered and sold to accredited investors an aggregate of 2,505,073 shares of our common stock and, in lieu thereof, pre-funded warrants to purchase up to 1,250,893 shares of our common stock, and accompanying common warrants to purchase up to 3,755,966 shares of our common stock (the “2026 Registered Direct Offering”). The combined purchase price for each share and common warrant in the 2026 Registered Direct Offering was $1.40, and the purchase price for each pre-funded warrant and common warrant in the 2026 Registered Direct Offering was $1.399, which was equal to the per share and common warrant purchase price, minus $0.001. We received net proceeds from the 2026 Registered Direct Offering of approximately $4.8 million. We are using the net proceeds to fund clinical development activities, including ongoing and planned clinical trials, advance our research and development programs, as well as for working capital and other general corporate purposes.
Previous wording
Upon consummation of the 2026 Registered Direct Offering (as defined below), the Bridge Notes, together with all accrued and unpaid interest thereon, automatically converted into an aggregate of 1,576,311 shares of our common stock and warrants to purchase up to 1,576,311 shares of our common stock. The warrants were issued on the same terms as the common warrants issued in the 2026 Registered Direct Offering.
Current wording
Upon consummation of the 2026 Registered Direct Offering, the 10.0% original issue discount unsecured convertible promissory notes in an aggregate principal amount of $2,200,000 issued in connection with our bridge financing in March 2026, together with all accrued and unpaid interest thereon, automatically converted into an aggregate of 1,576,311 shares of our common stock and warrants to purchase up to 1,576,311 shares of our common stock. The warrants were issued on the same terms as the common warrants issued in the 2026 Registered Direct Offering.
Previous wording
In connection with the 2026 Registered Direct Offering, Ceros acted as our exclusive placement agent. We paid Ceros a cash fee equal to 7.0% of the gross proceeds raised in the 2026 Registered Direct Offering. We also reimbursed Ceros up to $70,000 for its reasonable and documented out-of-pocket accountable expenses and up to $20,000 for its non-accountable expenses. We also issued to Ceros’s designees warrants to purchase up to an aggregate of 187,798 shares of our common stock. The placement agent warrants have an exercise price of $1.54 per share, are exercisable beginning September 2, 2026 and expire five years from April 2, 2026.
Current wording
In connection with the 2026 Registered Direct Offering, Ceros Financial Services, Inc. (“Ceros”) acted as our exclusive placement agent. We paid Ceros a cash fee equal to 7.0% of the gross proceeds raised in the 2026 Registered Direct Offering. We also reimbursed Ceros up to $70,000 for its reasonable and documented out-of-pocket accountable expenses and up to $20,000 for its non-accountable expenses. We also issued to Ceros’s designees warrants to purchase up to an aggregate of 187,798 shares of our common stock. The placement agent warrants have an exercise price of $1.54 per share, are exercisable beginning September 2, 2026 and expire five years from April 2, 2026.
Previous wording
Critical accounting policies are those that, in management’s view, are most important to the portrayal of a company’s financial condition and results of operations and most demanding on their calls on judgment, often as a result of the need to make estimates about the effect of matters that are inherently uncertain and may change in subsequent periods. Our significant accounting policies are described in more detail in Note 2 to our consolidated financial statements appearing elsewhere in this annual report. There were no critical accounting policies as of March 31, 2026.
Current wording
Critical accounting policies are those that, in management’s view, are most important to the portrayal of a company’s financial condition and results of operations and most demanding on their calls on judgment, often as a result of the need to make estimates about the effect of matters that are inherently uncertain and may change in subsequent periods. Our significant accounting policies are described in more detail in Note 2 to our consolidated financial statements appearing elsewhere in this annual report. There were no critical accounting policies and estimates as of June 30, 2026.
Previous wording
***Revenue.***We did not recognize revenues for the three months ended March 31, 2026 and 2025.
Current wording
***Revenue.***We did not recognize revenues for the six months ended June 30, 2026 and 2025.
Previous wording
***Income Taxes.***Since our inception, we have not recognized income tax benefits for the net operating losses (“NOLs”) incurred or the research and development (“R&D”) tax credits generated each year due to uncertainty regarding the realization of these benefits.
Current wording
***Income Taxes.***Since our inception, we have not recognized income tax benefits for the net operating losses (“NOLs”) incurred or the R&D tax credits generated each year due to uncertainty regarding the realization of these benefits.
Previous wording
Three Months Ended March 31, 2026 Compared to Three Months Ended March 31, 2025
Current wording
Three and Six Months Ended June 30, 2026 Compared to Three and Six Months Ended June 30, 2025
Previous wording
The following table summarizes our results of operations for the three months ended March 31, 2026 and 2025:
Current wording
The following table summarizes our results of operations for the three and six months ended June 30, 2026 and 2025:
Previous wording
***Research and Development Expenses.***Research and development expenses were approximately $7.4 million for the three months ended March 31, 2026 compared to approximately $1.3 million for the three months ended March 31, 2025. This increase was primarily due to an increase in vendor expenses associated with our Phase IIb clinical trial, as we compiled data to submit to various governmental agencies, and a decrease in vendor expenses associated with our OST-tADC platform technology.
Current wording
Research and development expenses were approximately $6.0 million for the three months ended June 30, 2026, compared to approximately $2.5 million for the three months ended June 30, 2025. This increase was primarily due to an increase in vendor expenses associated with our Phase IIb clinical trial, as we compiled data to submit to various governmental agencies. The increase was partially offset by the recognition of a $1.96 million VAT receivable in the second quarter of 2026. We determined that the input VAT associated with our UK subsidiary was realizable and, upon obtaining our VAT number and becoming eligible to file VAT returns, recognized the accumulated VAT as a receivable, resulting in a corresponding reduction in R&D expenses.
Previous wording
***General and Administrative Expenses.***General and administrative expenses for the three months ended March 31, 2026 were approximately $2.8 million compared to $3.7 million for the three months ended March 31, 2025. These expenses were primarily attributed to marketing and investor relations costs, advisory fees and other compensation related expenses.
Current wording
***General and Administrative Expenses.***General and administrative expenses were approximately $5.3 million for the six months ended June 30, 2026, compared to approximately $6.0 million for the six months ended June 30, 2025. These expenses were primarily attributable to marketing and investor relations costs, advisory fees and other compensation-related expenses.
Previous wording
***Interest Expense.***Interest expense for the three months ended March 31, 2026 was approximately $0.1 million compared to $0.0 million for the three months ended March 31, 2025. Interest expense related to amortization of debt issuance costs and accretion of interest on the Bridge Convertible Notes.
Current wording
Interest expense was approximately $0.1 million for the three months ended June 30, 2026, compared to $0.0 million for the three months ended June 30, 2025. Interest expense in 2026 primarily related to the amortization of debt issuance costs and accretion of interest on our March 2026 bridge convertible notes.
Previous wording
Non-Operating Expense. Non-operating expense for the three months ended March 31, 2026 was approximately $0.2 million compared to $0.0 million for the three months ended March 31, 2025 and related to losses on foreign currency transactions.
Current wording
Non-Operating Expense. Non-operating expense was approximately $0.2 million for the six months ended June 30, 2026, compared to $0.0 million for the six months ended June 30, 2025, and related to losses on foreign currency transactions.
Previous wording
***Change in Fair Value of Warrant.***The Series A warrants issued in connection with our PIPE financing in December 2024 and January 2025 were reclassified from liability to equity in April 2025. The adjustment of the fair value of the warrant liability was $0.0 million and $1.1 million for the three months ended March 31, 2026 and 2025, respectively.
Current wording
***Change in Fair Value of Warrant.***The Series A warrants issued in connection with our PIPE financing in December 2024 and January 2025 were reclassified from liability to equity in April 2025. As a result, there was no change in the fair value of the warrant liability for the six months ended June 30, 2026, compared to a $1.4 million adjustment to the fair value of the warrant liability for the six months ended June 30, 2025. For the three months ended June 30, 2026 and 2025, there was no change in the fair value of the warrant liability and a $0.3 million adjustment to the fair value of the warrant liability, respectively.
Previous wording
Since our inception, we have incurred significant operating losses. Our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful development and eventual commercialization of our product candidates. For the three months ended March 31, 2026 and 2025, we reported a net loss of approximately $10.4 million and $3.9 million, respectively, and had an accumulated deficit of approximately $77.4 million and $67.2 million, respectively. We expect to incur significant expenses at an increasing rate and increasing operating losses for the foreseeable future.
Current wording
Since our inception, we have incurred significant operating losses. Our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful development and eventual commercialization of our product candidates. For the six months ended June 30, 2026 and 2025, we reported a net loss of approximately $19.0 million and $8.4 million, respectively, and had an accumulated deficit of approximately $86.2 million and $67.2 million, respectively. We expect to incur significant expenses at an increasing rate and increasing operating losses for the foreseeable future.
Previous wording
As of March 31, 2026 and December 31, 2025, we had cash of approximately $0.9 million and $0.3 million, respectively. To date, we have primarily funded our operations through the sale of our securities in public offerings and private placements and warrant exercise inducement and exchange transactions, generating total gross proceeds of approximately $52.3 million as of May 15, 2026. We believe that the net proceeds from these transactions, together with our existing cash, will be sufficient to fund our operating expenses and capital expenditures for at least the next twelve months.
Current wording
As of June 30, 2026 and December 31, 2025, we had cash of approximately $0.2 million and $0.3 million, respectively. To date, we have primarily funded our operations through the sale of our securities in public offerings and private placements and through warrant exercise inducement and exchange transactions, generating total gross proceeds of approximately $52.3 million as of June 30, 2026. On August 10, 2026, we issued certain of our securities and received net proceeds of approximately $4.7 million in the August Private Placement, with the potential to receive an additional $5.0 million, if needed. However, our recurring losses and negative cash flows from operations since inception, together with cash of approximately $0.2 million as of June 30, 2026, were not sufficient to fund our operations for at least 12 months from the date these consolidated financial statements are issued. These conditions raise substantial doubt about our ability to continue as a going concern. Management’s plans to address these conditions include the August Private Placement, other equity or debt financings and managing operating expenditures.
Previous wording
The following table summarizes our sources and uses of cash for the three months ended March 31, 2026 and 2025:
Current wording
The following table summarizes our sources and uses of cash for the six months ended June 30, 2026 and 2025:
Previous wording
During the three months ended March 31, 2026 and 2025, operating activities used approximately $4.6 million and $3.4 million of cash, respectively, resulting from our net loss of approximately $10.4 million and $3.9 million, respectively, offset by net non-cash charges of approximately $1.9 million and $0.7 million, respectively, partially offset by net cash provided by changes in our operating assets and liabilities of approximately $3.9 million and ($0.3) million, respectively.
Current wording
During the six months ended June 30, 2026 and 2025, operating activities used approximately $10.1 million and $5.8 million of cash, respectively, resulting from our net loss of approximately $19.0 million and $8.4 million, respectively, offset by net non-cash charges of approximately $3.4 million and $1.5 million, respectively, partially offset by net cash provided by changes in our operating assets and liabilities of approximately $5.5 million and $1.2 million, respectively.
Previous wording
Net cash provided by changes in our operating assets and liabilities for the three months ended March 31, 2026 and 2025 consisted primarily of an increase (decrease) in accounts payable of approximately $2.1 million and $(0.05) million, respectively, and an increase (decrease) in accrued expenses of approximately $1.8 million and $(0.2) million, respectively.
Current wording
Net cash provided by changes in our operating assets and liabilities for the six months ended June 30, 2026 and 2025 consisted primarily of an increase in accounts payable of approximately $7.1 million and $1.0 million, respectively, and an increase (decrease) in accrued expenses of approximately $1.8 million and $(0.1) million, respectively.
Previous wording
Non-cash charges for the three months ended March 31, 2026 and 2025 were primarily the result of the changes in the fair value of our warrant liability of $0 million and $1.1 million, respectively, combined with our common stock shares issued for services and our stock-based compensation of approximately $1.4 million and $1.3 million, respectively. Changes in accounts payable, accrued expenses and other current liabilities and prepaid expenses and other current assets in all periods were generally due to growth in our business, the advancement of our research programs and the timing of vendor invoicing and payments.
Current wording
Non-cash charges for the six months ended June 30, 2026 and 2025 were primarily the result of the changes in the fair value of our warrant liability of $0 and $1.4 million, respectively, combined with our stock-based compensation of approximately $2.8 million and $1.8 million, respectively. Changes in accounts payable, accrued expenses and other current liabilities and prepaid expenses and other current assets in all periods were generally due to growth in our business, the advancement of our research programs and the timing of vendor invoicing and payments.
Previous wording
During the three months ended March 31, 2026 and 2025, net cash used in investing activities was approximately $0.0 million and $(0.2) million, respectively.
Current wording
During the six months ended June 30, 2026 and 2025, net cash used in investing activities was approximately $0.0 million and $(0.5) million, respectively.
Previous wording
For the three months ended March 31, 2026 and 2025, net cash provided by financing activities was approximately $5.2 million and $1.1 million, respectively. For three months ended March 31, 2026, we saw funds raised from our warrant inducement exercise offering of $3.4 million and net proceeds from the Bridge Financing of $1.8 million.
Current wording
For the six months ended June 30, 2026 and 2025, net cash provided by financing activities was approximately $10.0 million and $3.5 million, respectively. For six months ended June 30, 2026, we raised proceeds from our warrant inducement exercise offering of $3.4 million, from the Bridge Financing of $1.8 million, and from the 2026 Registered Direct Offering of $4.8 million.
Previous wording
For the three months ended March 31, 2026, we paid $6,515,059 in consulting fees, which includes refundable value-added tax (“VAT”) expenses. As of March 31, 2026, accounts payable related to consulting fees and VAT totaled $9,943,617.
Current wording
For the six months ended June 30, 2026 and 2025, we incurred consulting fee expenses of $14,357,276 and $459,485, respectively, which included refundable VAT expenses. As of June 30, 2026, accounts payable related to consulting fees and VAT totaled $12,998,803 and $7,323,386, respectively.
Rearranged current paragraphs (3)
Current report — wording carried from elsewhere
General and administrative expenses were approximately $2.5 million for the three months ended June 30, 2026, compared to approximately $2.3 million for the three months ended June 30, 2025. These expenses were primarily attributable to marketing and investor relations costs, advisory fees and other compensation-related expenses.
Current report — wording carried from elsewhere
Non-operating expense was approximately $0.1 million for the three months ended June 30, 2026, compared to $0.0 million for the three months ended June 30, 2025, and related to losses on foreign currency transactions.
Current report — wording carried from elsewhere
2026 Registered Direct Offering. On April 2, 2026, we completed the 2026 Registered Direct Offering, pursuant to which we offered and sold to accredited investors an aggregate of 2,505,073 shares of our common stock and, in lieu thereof, pre-funded warrants to purchase up to 1,250,893 shares of our common stock, and accompanying common warrants to purchase up to 3,755,966 shares of our common stock. The combined purchase price for each share and common warrant in the 2026 Registered Direct Offering was $1.40, and the purchase price for each pre-funded warrant and common warrant in the 2026 Registered Direct Offering was $1.399, which was equal to the per share and common warrant purchase price, minus $0.001. We received net proceeds from the 2026 Registered Direct Offering of approximately $4.8 million. We are using the net proceeds to fund clinical development activities, including ongoing and planned clinical trials, advance our research and development programs, as well as for working capital and other general corporate purposes.
Rearranged previous paragraphs (1)
Previous report — wording carried elsewhere
2026 Registered Direct Offering. On April 2, 2026, we the 2026 Registered Direct Offering. We received net proceeds from the 2026 Registered Direct Offering of approximately $4.7 million. We are using the net proceeds to fund clinical development activities, including ongoing and planned clinical trials, advance our research and development programs, as well as for working capital and other general corporate purposes.