Exhibit 99.1 Theriva™ Biologics Reports First Quarter 2026 Operational Highlights and Financial Results – Alignment with the FDA on the Phase 3 trial design of VCN-01 (zabilugene almadenorepvec) for treatment of metastatic pancreatic ductal adenocarcinoma (PDAC) – – Additional data from VIRAGE Phase 2b clinical trial of VCN-01 in metastatic PDAC patients presented at the recent AACR Annual Meeting may reflect an immune-mediated mechanism of action and demonstrate improved outcomes in VCN-01 treated patients ...