Oncolytics reports REO 033 site activation and FDA alignment

Substantially all planned clinical sites for the REO 033 study are now activated, with multiple patients currently enrolled in the randomized trial evaluating pelareorep in second-line RAS-mutant, microsatellite-stable metastatic colorectal cancer. Oncolytics Biotech Inc. (Nasdaq: ONCY) stated it expects to have sufficient Part A data to provide an interim clinical update by year-end 2026.

The REO 033 study is a randomized controlled trial assessing pelareorep in combination with folinic acid, fluorouracil, irinotecan, and bevacizumab against the same chemotherapy regimen without pelareorep. Part A is designed to enroll approximately 60 patients randomized between the two treatment arms. Objective response rate is the primary endpoint, with progression-free survival, overall survival, safety, and biomarker analyses serving as additional endpoints. John McAdory, Chief Operating Officer of Oncolytics, noted that the company's focus has shifted to accelerating enrollment and generating randomized clinical data to evaluate the contribution of pelareorep to the current standard-of-care regimen.

This phase follows earlier findings from the non-randomized REO 022 study, where pelareorep added to chemotherapy and bevacizumab showed an objective response rate of 33%, compared to historical second-line benchmarks of approximately 6-11%. Median progression-free survival in REO 022 was 16.6 months against historical benchmarks of about 5.7 months, and median overall survival was 27.0 months compared to approximately 11.2 months. Oncolytics emphasized that REO 033 is designed to prospectively test these efficacy signals in a randomized setting with a concurrent control arm to determine if the results can be replicated.

The company recently aligned with the U.S. Food and Drug Administration on a potential pivotal Part B expansion of REO 033. Under this proposed regulatory strategy, Part B would build upon the ongoing randomized study and could support a potential accelerated approval submission based on objective response rate. Progression-free survival would provide the basis for potential full approval. Data from Part A is expected to inform the final size and execution of this potential pivotal expansion.

Pelareorep is an investigational intravenously delivered immunotherapy that has been administered to over 1,200 patients. It has received Fast Track designation from the FDA for colorectal, anal, and pancreatic cancer.