Theriva Biologics, Inc.

APPENDIX

20 SEASONED LEADERSHIP TEAM Manel Cascall ó PhD General Director, EU Subsidiary Expertise in oncolytic adenovirus clinical development, received several patents for the use of adenovirus as antitumoral agents and authored many peer - reviewed scientific publications Deep regulatory experience and serves as an independent expert for the European Medicines Agencies (EMA) Steven Shallcross Chief Executive Officer, Chief Financial Officer Served as the Company’s CEO since 2018 and CFO since joining the Company in 2015 Deep operational, financial and international biotech industry experience and proven track record of leading the financial development and strategy in the public sector Vince Wacher PhD Head Corporate Development Nearly 30 years leading corporate strategy, partnering, research, clinical development, and intellectual property programs for start - ups, small companies, and new business units within large companies Development experience across oncology, infection, GI, metabolic diseases, transplantation, and drug delivery

21 VCN - 01 IS A UNIQUELY ENGINEERED HUMAN ADENOVIRUS 5 Cancer Associated Fibroblast Stroma Tumor Surrounded by STROMA VCN - 01 1 SYSTEMIC delivers VCN - 01 to the primary tumor and metastases and detargets the liver SELECTIVE replication at very high levels lyses tumor cells directly without harming healthy tissues 2

22 VCN - 01 DESIGNED TO HAVE MULTIPLE ANTI - TUMOR ACTIONS PH20 PH20 PH20 PH20 PH20 PH20 PH20 PH20 Neoantigen Cancer Associated Fibroblast Stroma STROMA degradation by PH20 facilitates solid tumor access and destruction by coadministered cancer therapies 3 4 IMMUNOGENIC actions of VCN - 01 turn “cold” tumors “hot” and elicit an anti - tumor immune response VCN - 01 nab - paclitaxel gemcitabine T - Cells Tumor Stroma Degraded

23 VCN - 01 EXTENSIVE CLINICAL EXPERIENCE 142 patients treated with VCN - 01 in multiple indications and combinations HEAD & NECK – IV + Durvalumab (20) PANCREATIC - IV + Gemcitabine / Abraxane ® Phase 1 (26) and Phase 2b (53)* COLORECTAL – IV Alone (15) PANCREATIC - IT + Gemcitabine / Abraxane ® (8) PANCREATIC, OVARIAN - IV + huCART - meso cells (9)* BRAIN TUMORS – IV (1)* HEAD & NECK – IV alone (1) *On - going study. Abraxane® - nab - paclitaxel. Durvalumab (IMFINZI ® , AstraZeneca) is an anti - PD - L1 mAb immune checkpoint inhibitor. huCART - meso are autologous T cells engineered to express an extracellular single chain variable fragment (scFv) with mesothelin specificity. IT - intratumoral. IV - intravenous. IVit - intravitreal. Rb - retinoblastoma. See Appendix for study registry numbers and publications. Rb – IVit alone (9) (Number of VCN - 01 Patients Treated in Parentheses) Preparing for Phase 3

24 VCN - 01 COMPARED TO OTHER ONCOLYTIC VIRUSES IN DEVELOPMENT REPLIMMUNE ONCOLYTICS BIOTECH GENELUX CG ONCOLOGY THERIVA BIOLOGICS COMPANY NASDAQ: REPL NASDAQ:ONCY NASDAQ: GNLX NASDAQ: CGON NYSE MKT: TOVX Ticker $753.9M $48.5M $102.3M $2.07B $3.7M Market Cap ¹ RP1, RP2 Pelareorep Olvi - Vec Cretostimogene grenadenorepvec VCN - 01 Product Herpes Simplex Reovirus Vaccinia Adenovirus 5 Adenovirus 5 Virus DNA (enveloped) RNA DNA (enveloped) DNA DNA Type Low tumor IFN ICP34.5 deletion Low tumor IFN Ras activation Low tumor IFN TK deletion Selective replication (Rb - E2F dysfunction) Selective replication (Rb - E2F dysfunction) Tumor selectivity mechanism GM - CSF, GALV - GP R( - ), anti - CTLA - 4 .. .. GM - CSF PH20 Therapeutic Transgene Melanoma (3) Pancreatic, GI (2b) Ovarian (3) Bladder (3) Pancreatic (2b) Lead Indication (Ph) IT IV IP IVESIC IV Route 1x10 7 pfu/mL 4.5x10 10 TCID 50 3x10 9 pfu 1x10 12 vp 1x10 13 vp ² Dose No No No No Yes Stroma Degrading .. .. β - GAL, β - GLU, GFP .. PH20 Biomarker ¹At 30Apr2025 per yahoo! finance. ² Approximately 7x10 11 TCID 50 . References describing the different OV product candidates are provided in the appendix; information is also available on each company’s website and clinicaltrials.gov

25 THERIVA OV PORTFOLIO HIGHLIGHTS Multiple modes of action, indications and combinations • Highly differentiated OVs designed to have multiple antitumor effects • Systemic administration, selective tumor replication, stroma degradation • Multiple potential value opportunities for lead asset VCN - 01 • Preparing Phase 3 trial with SoC in first - line metastatic PDAC; planning Phase 2/3 trial in retinoblastoma • Phase 1 data support additional indications (HNSCC, CRC) and diverse combinations (chemotherapy, CPI, CAR - T) • Regulatory status expected to facilitate VCN - 01 development • PDAC: Orphan Drug Designation (FDA, EMA), Fast Track designation (FDA) • Retinoblastoma: Orphan Drug Designation (EMA; FDA); Rare Pediatric Disease Designation (FDA: potential access to priority review voucher) • Leading OV discovery engine advancing diverse new product candidates • Potent tumor killing with potential single agent efficacy CPI immune checkpoint inhibitor. CRC colorectal cancer. HNSCC head and neck squamous cell carcinoma. PDAC pancreatic ductal a den ocarcinoma. SoC standard of care (gemcitabine + nab - paclitaxel in PDAC).