Organization and Nature of Operations and Basis of Presentation	12 Months Ended
Dec. 31, 2025
Organization and Nature of Operations and Basis of Presentation
Organization and Nature of Operations and Basis of Presentation	1. Organization and Nature of Operations and Basis of Presentation Description of Business Theriva Biologics, Inc. (the “Company” or “Theriva Biologics”) is a diversified clinical-stage company developing therapeutics designed to treat cancer and related diseases in areas of high unmet need. As a result of the Company’s acquisition of Theriva Biologics, S.L. (“VCN”, formerly named VCN Biosciences, S.L.), in March 2022 described in more detail below (the “Acquisition”), we transitioned our strategic focus to oncology through the development of VCN’s new oncolytic adenovirus platform designed for intravenous and intravitreal delivery to trigger tumor cell death, to improve access of co-administered cancer therapies to the tumor, and to promote a robust and sustained anti-tumor response by the patient’s immune system. Our lead product candidate, VCN-01 (zabilugene almadenorepvec), is a clinical stage oncolytic human adenovirus that is modified for tumor-selective replication and to express an enzyme, PH20 hyaluronidase. VCN-01 has been evaluated in a Phase 2b clinical study for the treatment of pancreatic cancer (“VIRAGE”), and a Phase 1 clinical study for the treatment of retinoblastoma, as well as various other Phase 1 clinical studies for the treatment of other solid tumors including head and neck squamous cell carcinoma. Corporate Structure and Basis of Presentation On August 15, 2024, the Board of Directors of the Company approved a reverse stock split of the Company’s authorized, issued and outstanding shares of common stock, par value $0.001 per share (“Common Stock”), at a ratio of one (1) share of Common Stock for every twenty - five (25) shares of Common Stock (the “Reverse Stock Split”). The Reverse Stock Split went effective on August 26, 2024 (the “Effective Time). As a result of the Reverse Stock Split, each twenty - five (25) pre-split shares of Common Stock outstanding automatically combined into one (1) new share of common stock without any action on the part of the holders, and the number of outstanding shares of Common Stock was reduced from 25,131,230 shares to 1,005,249 shares and the number of authorized shares of Common Stock was reduced from 350,000,000 shares to 14,000,000 shares and then increased back to 350,000,000 shares of Common Stock after obtaining approval of the Company’s shareholders at the 2024 annual meeting of stockholders. Stockholders who otherwise were entitled to receive fractional shares because they held a number of pre-reverse stock split shares of the Company’s Common Stock not evenly divisible by 25, received, in lieu of a fractional share, that number of shares rounded up to the nearest whole share. The Reverse Stock Split did not alter the par value of the Company’s Common Stock or modify any voting rights or other terms of the Common Stock. In addition, pursuant to their terms, a proportionate adjustment was made to the per share conversion exercise price and number of shares issuable under all of the Company’s outstanding shares of convertible preferred stock and stock options and warrants to purchase shares of Common Stock, and the number of shares authorized and reserved for issuance pursuant to the Company’s equity incentive plans was reduced proportionately. All affected share amounts and exercise/conversion prices in the consolidated financial statements and footnotes below have been adjusted retroactively for the Reverse Stock Split. As of December 31, 2025, the Company had nine subsidiaries, Theriva Biologics, S.L., Pipex Therapeutics, Inc. (“Pipex Therapeutics”), Effective Pharmaceuticals, Inc. (“EPI”), Solovax, Inc. (“Solovax”), CD4 Biosciences, Inc. (“CD4”), Epitope Pharmaceuticals, Inc. (“Epitope”), Healthmine, Inc. (“Healthmine”), Putney Drug Corp. (“Putney”) and Synthetic Biomics, Inc. (“SYN Biomics”). Theriva Biologics, S.L.,Pipex Therapeutics, EPI, Healthmine, Putney and SYN Biomics are wholly owned, and Solovax, CD4, and Epitope are majority-owned. 1. Organization and Nature of Operations and Basis of Presentation – (continued) For financial reporting purposes, the outstanding Common Stock of the Company is that of Theriva Biologics, Inc. All statements of operations, equity and cash flows for each of the entities are presented as consolidated. All subsidiaries were formed under the laws of the State of Delaware on January 8, 2001, except for EPI, which was incorporated in Delaware on December 12, 2000; Epitope which was incorporated in Delaware in January 2002; Putney which was incorporated in Delaware in November 2006; Healthmine which was incorporated in Delaware in December 2007; SYN Biomics which was incorporated in Nevada in December 2013; and Theriva Biologics, S.L. which was incorporated in Spain in December 2022. Liquidity As of December 31, 2025, the Company had a significant accumulated deficit of $358.7 million, and the Company has experienced significant losses and incurred negative cash flows since inception. The Company expects to continue incurring losses for the foreseeable future, with the recognition of revenue being contingent on successful Phase 3 clinical trials and requisite approvals by the FDA or foreign equivalents. Historically, the Company has financed its operations primarily through public and private sales of its Common Stock and a private placement of its preferred stock as well as warrant exercises, and it expects to continue to seek to obtain required capital in a similar manner. The Company has spent, and expects to continue to spend, a substantial amount of funds in connection with implementing its business strategy, including planned product development efforts, clinical trials and research and discovery efforts. The Company’s cash and cash equivalents totaled $13.1 million as of December 31, 2025, an increase of $1.4 million from December 31, 2024. During the year ended December 31, 2025, the primary use of cash was for working capital requirements and operating activities which resulted in a net loss of $23.7 million. The Company believes it will be able to fund its operations into the first quarter of 2027. However, the actual amount of additional capital needed by the Company will also depend upon the costs to advance its VCN-01 (zabilugene almadenorepvec) clinical programs. At this time, the Company does not intend to continue to develop SYN-004 and/or SYN-020 internally due to the cost to do so and is seeking out-licenses or partners for such development. The Company may attempt to utilize the at-the-market offering facility (“ATM”) or seek to raise additional capital in other financing transactions, neither of which is guaranteed. Use of the ATM is limited by certain restrictions and management’s plan does not rely on additional capital from either of these sources. If the Company is not able to obtain additional capital (which is not assured at this time), its business plan may not be accomplished, and it may be forced to cease certain development activities. More specifically, the completion of any later stage clinical trial will require significant financing or a significant partnership.

Organization and Nature of Operations and Basis of Presentation

12 Months Ended

Dec. 31, 2025

Organization and Nature of Operations and Basis of Presentation

Organization and Nature of Operations and Basis of Presentation

1. Organization and Nature of Operations and Basis of Presentation

Description of Business

Theriva Biologics, Inc. (the “Company” or “Theriva Biologics”) is a diversified clinical-stage company developing therapeutics designed to treat cancer and related diseases in areas of high unmet need. As a result of the Company’s acquisition of Theriva Biologics, S.L. (“VCN”, formerly named VCN Biosciences, S.L.), in March 2022 described in more detail below (the “Acquisition”), we transitioned our strategic focus to oncology through the development of VCN’s new oncolytic adenovirus platform designed for intravenous and intravitreal delivery to trigger tumor cell death, to improve access of co-administered cancer therapies to the tumor, and to promote a robust and sustained anti-tumor response by the patient’s immune system. Our lead product candidate, VCN-01 (zabilugene almadenorepvec), is a clinical stage oncolytic human adenovirus that is modified for tumor-selective replication and to express an enzyme, PH20 hyaluronidase. VCN-01 has been evaluated in a Phase 2b clinical study for the treatment of pancreatic cancer (“VIRAGE”), and a Phase 1 clinical study for the treatment of retinoblastoma, as well as various other Phase 1 clinical studies for the treatment of other solid tumors including head and neck squamous cell carcinoma.

Corporate Structure and Basis of Presentation

On August 15, 2024, the Board of Directors of the Company approved a reverse stock split of the Company’s authorized, issued and outstanding shares of common stock, par value $0.001 per share (“Common Stock”), at a ratio of one (1) share of Common Stock for every twenty - five (25) shares of Common Stock (the “Reverse Stock Split”). The Reverse Stock Split went effective on August 26, 2024 (the “Effective Time).

As a result of the Reverse Stock Split, each twenty - five (25) pre-split shares of Common Stock outstanding automatically combined into one (1) new share of common stock without any action on the part of the holders, and the number of outstanding shares of Common Stock was reduced from 25,131,230 shares to 1,005,249 shares and the number of authorized shares of Common Stock was reduced from 350,000,000 shares to 14,000,000 shares and then increased back to 350,000,000 shares of Common Stock after obtaining approval of the Company’s shareholders at the 2024 annual meeting of stockholders. Stockholders who otherwise were entitled to receive fractional shares because they held a number of pre-reverse stock split shares of the Company’s Common Stock not evenly divisible by 25, received, in lieu of a fractional share, that number of shares rounded up to the nearest whole share. The Reverse Stock Split did not alter the par value of the Company’s Common Stock or modify any voting rights or other terms of the Common Stock. In addition, pursuant to their terms, a proportionate adjustment was made to the per share conversion exercise price and number of shares issuable under all of the Company’s outstanding shares of convertible preferred stock and stock options and warrants to purchase shares of Common Stock, and the number of shares authorized and reserved for issuance pursuant to the Company’s equity incentive plans was reduced proportionately.

All affected share amounts and exercise/conversion prices in the consolidated financial statements and footnotes below have been adjusted retroactively for the Reverse Stock Split.

As of December 31, 2025, the Company had nine subsidiaries, Theriva Biologics, S.L., Pipex Therapeutics, Inc. (“Pipex Therapeutics”), Effective Pharmaceuticals, Inc. (“EPI”), Solovax, Inc. (“Solovax”), CD4 Biosciences, Inc. (“CD4”), Epitope Pharmaceuticals, Inc. (“Epitope”), Healthmine, Inc. (“Healthmine”), Putney Drug Corp. (“Putney”) and Synthetic Biomics, Inc. (“SYN Biomics”). Theriva Biologics, S.L.,Pipex Therapeutics, EPI, Healthmine, Putney and SYN Biomics are wholly owned, and Solovax, CD4, and Epitope are majority-owned.

1. Organization and Nature of Operations and Basis of Presentation – (continued)

For financial reporting purposes, the outstanding Common Stock of the Company is that of Theriva Biologics, Inc. All statements of operations, equity and cash flows for each of the entities are presented as consolidated. All subsidiaries were formed under the laws of the State of Delaware on January 8, 2001, except for EPI, which was incorporated in Delaware on December 12, 2000; Epitope which was incorporated in Delaware in January 2002; Putney which was incorporated in Delaware in November 2006; Healthmine which was incorporated in Delaware in December 2007; SYN Biomics which was incorporated in Nevada in December 2013; and Theriva Biologics, S.L. which was incorporated in Spain in December 2022.

Liquidity

As of December 31, 2025, the Company had a significant accumulated deficit of $358.7 million, and the Company has experienced significant losses and incurred negative cash flows since inception. The Company expects to continue incurring losses for the foreseeable future, with the recognition of revenue being contingent on successful Phase 3 clinical trials and requisite approvals by the FDA or foreign equivalents. Historically, the Company has financed its operations primarily through public and private sales of its Common Stock and a private placement of its preferred stock as well as warrant exercises, and it expects to continue to seek to obtain required capital in a similar manner. The Company has spent, and expects to continue to spend, a substantial amount of funds in connection with implementing its business strategy, including planned product development efforts, clinical trials and research and discovery efforts.

The Company’s cash and cash equivalents totaled $13.1 million as of December 31, 2025, an increase of $1.4 million from December 31, 2024. During the year ended December 31, 2025, the primary use of cash was for working capital requirements and operating activities which resulted in a net loss of $23.7 million. The Company believes it will be able to fund its operations into the first quarter of 2027. However, the actual amount of additional capital needed by the Company will also depend upon the costs to advance its VCN-01 (zabilugene almadenorepvec) clinical programs. At this time, the Company does not intend to continue to develop SYN-004 and/or SYN-020 internally due to the cost to do so and is seeking out-licenses or partners for such development. The Company may attempt to utilize the at-the-market offering facility (“ATM”) or seek to raise additional capital in other financing transactions, neither of which is guaranteed. Use of the ATM is limited by certain restrictions and management’s plan does not rely on additional capital from either of these sources. If the Company is not able to obtain additional capital (which is not assured at this time), its business plan may not be accomplished, and it may be forced to cease certain development activities. More specifically, the completion of any later stage clinical trial will require significant financing or a significant partnership.