1. Organization, 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 in areas of high unmet need. As a result of the acquisition in March 2022 of Theriva Biologics S.L. (“VCN”, formerly known as VCN Biosciences, S.L.) (the “Acquisition”), described in more detail below, the Company transitioned its 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. Prior to the Acquisition, the Company’s focus was on developing therapeutics designed to treat gastrointestinal (GI) diseases in areas which included its clinical development candidates: (1) SYN-004 (ribaxamase) which is designed to degrade certain commonly used intravenous (IV) beta-lactam antibiotics within the GI tract to prevent microbiome damage thereby preventing overgrowth and infection by pathogenic organisms such as Clostridioides difficile infection (CDI), and vancomycin resistant Enterococci (VRE), and reducing the incidence and severity of acute graft-versus-host-disease (aGVHD) in allogeneic hematopoietic cell transplant (HCT) recipients, and (2) SYN-020, a recombinant oral formulation of the enzyme intestinal alkaline phosphatase (IAP) produced under cGMP conditions and intended to treat both local GI and systemic diseases.

Basis of Presentation

The accompanying condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) for interim financial information. Accordingly, they do not include all the information and notes required by Accounting Principles Generally Accepted in the United States of America (“U.S. GAAP”) for complete financial statements. The accompanying condensed consolidated financial statements include all adjustments, comprised of normal recurring adjustments, considered necessary by management to fairly state the Company’s results of operations, financial position, and cash flows. The operating results for the interim periods are not necessarily indicative of results that may be expected for any other interim period or for the full year. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Company’s 2024 Form 10-K.

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 (the “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 was 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 was 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 Common Stock was reduced from 25,131,230 shares to 1,005,249 shares (subject to rounding of fractional shares) and the number of authorized shares of Common Stock was reduced from 350,000,000 share to 14,000,000 shares and then increased to 350,000,000 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 condensed consolidated financial statements and footnotes below have been adjusted retrospectively for the Reverse Stock Split.

The condensed consolidated financial statements are prepared in conformity with U.S. GAAP, which requires the use of estimates, judgments and assumptions that affect the amounts of assets and liabilities at the reporting date and the amounts of revenue and expenses in the periods presented. The Company believes that the accounting estimates employed are appropriate and the resulting balances are reasonable; however, due to the inherent uncertainties in making estimates, actual results may differ from the original estimates,

requiring adjustments to these balances in future periods. As of March 31, 2025, the Company has one operating segment (which includes the legacy Company business and the VCN business) and therefore one reporting segment.