VCN-01 Gains FDA Phase III Nod for Pancreatic Cancer

Theriva Biologics (NYSE American: TOVX), a Rockville, Maryland–based clinical-stage company, announced that the US FDA has agreed to the proposed design of a Phase III trial evaluating VCN-01 in combination with gemcitabine and nab-paclitaxel for first-line treatment of metastatic pancreatic ductal adenocarcinoma. The regulatory alignment, following a Type B End-of-Phase 2 meeting, clears a path for Theriva to finalize its pivotal protocol and seek funding or partnerships to initiate the study — a consequential step for a company attempting to bring an oncolytic virus into late-stage pancreatic cancer development.

The proposed Phase III study is a randomized, double-blind trial comparing VCN-01 plus gemcitabine/nab-paclitaxel against gemcitabine/nab-paclitaxel plus placebo in patients with metastatic PDAC. The trial will use overall survival as its primary endpoint, with progression-free survival among the key secondary endpoints. The design incorporates an adaptive framework with pre-specified interim analyses, allowing for potential sample size re-estimation or early efficacy determination. The company said the FDA agreed on the proposed dosing of VCN-01 administered in repeated "macrocycles," enabling patients to receive more than two doses of the oncolytic virus across the course of treatment. No ClinicalTrials.gov identifier has been posted for the Phase III study.

The Phase III design tracks closely with the VIRAGE trial, a Phase IIb, open-label, randomized study that compared VCN-01 plus standard-of-care chemotherapy against chemotherapy alone in metastatic PDAC. Theriva reported in 2025 that VIRAGE met its primary endpoints, with patients receiving VCN-01 showing improved overall survival, progression-free survival, and duration of response relative to the chemotherapy-only arm. The company noted that patients who received two doses of VCN-01 had greater improvements in OS and PFS than those receiving a single dose. However, Theriva has not publicly disclosed hazard ratios, median survival times, or confidence intervals from the VIRAGE study, making independent assessment of the treatment effect difficult. Detailed safety data from the Phase IIb trial have also not been released in the public summary.

VCN-01, also known by its non-proprietary name zabilugene almadenorepvec, is a systemically administered oncolytic adenovirus engineered to selectively replicate within tumor cells. The virus expresses hyaluronidase, which degrades hyaluronic acid in the tumor stroma — a dense extracellular matrix that characterizes pancreatic tumors and acts as a physical barrier to drug delivery and immune cell infiltration. By lysing tumor cells and remodeling the stromal microenvironment, VCN-01 is designed to enhance the penetration of co-administered chemotherapy and increase tumor immunogenicity. Systemic intravenous delivery is intended to allow the virus to reach both primary tumors and metastatic sites. VCN-01 has been administered to 142 patients across multiple company- and investigator-sponsored trials in cancers including PDAC, head and neck squamous cell carcinoma, ovarian cancer, colorectal cancer, and retinoblastoma.

Metastatic PDAC remains among the most treatment-resistant solid tumors. The current first-line standard of care consists of either gemcitabine plus nab-paclitaxel or FOLFIRINOX (a combination of fluorouracil, leucovorin, irinotecan, and oxaliplatin), both of which were established as standards more than a decade ago. Median overall survival with gemcitabine/nab-paclitaxel in the metastatic setting is approximately 8.5 months based on the pivotal MPACT trial. No oncolytic virus therapy has been approved for pancreatic cancer, and few biologic agents have demonstrated survival benefits in this indication in randomized studies. Without detailed efficacy data from VIRAGE, it is not possible to quantify how VCN-01 compares numerically to these established benchmarks. Cross-trial comparisons are limited by differences in study design, duration, and patient populations.

The FDA's agreement on the Phase III protocol is consistent with scientific advice Theriva previously received from the Committee for Medicinal Products for Human Use of the European Medicines Agency. Both agencies indicated that a single, high-quality randomized trial could support a potential biologics licensing application for VCN-01 in metastatic PDAC, if results are positive. The dual regulatory alignment on a single pivotal study is notable, as it could streamline the development path if the company secures the necessary funding.

Theriva stated it is now finalizing the Phase III protocol and pursuing strategic funding opportunities and partnerships to support the trial. The company did not disclose a timeline for trial initiation or expected enrollment size. For a clinical-stage company with a market capitalization typical of small-cap oncology biotechs, the capital requirements of a randomized, double-blind Phase III study in metastatic PDAC — a setting that demands large patient numbers and extended follow-up for overall survival — represent a material challenge. The next milestones to watch are protocol finalization, any partnership or funding announcements, and the eventual disclosure of detailed VIRAGE data at a medical conference or in a peer-reviewed publication.

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