Oncolytics Biotech Reports Positive Preclinical Data for Pelareorep Combined with RAS Inhibitor

Oncolytics Biotech Inc. (Nasdaq: ONCY) announced on September 10, 2026, the results of a preclinical study evaluating its investigational immunotherapy pelareorep in combination with a pan-RAS inhibitor in a RAS-driven colorectal cancer model. The study aimed to determine if pelareorep activity is maintained when used alongside RAS-targeted therapies.

During the initial treatment period, when pelareorep was administered every other day, all treatment groups—including pelareorep alone, the pan-RAS inhibitor alone, and the combination—showed reduced tumor growth compared to the control group. The greatest reductions in tumor size were observed in the groups receiving the pan-RAS inhibitor and the combination therapy. The company noted that pelareorep activity was maintained in the presence of RAS inhibition, with no evidence of antagonism between the two therapies.

Following a transition to less frequent weekly dosing of pelareorep, the incremental activity associated with the drug became less evident. Oncolytics stated that these findings support further evaluation of optimized pelareorep dosing schedules with RAS inhibitors. The company believes sustained pelareorep activity could potentially deepen or prolong responses to RAS-targeted therapy and delay the emergence of treatment resistance.

The findings are consistent with previously published independent research indicating that RAS inhibitors do not interfere with the mechanism through which pelareorep selectively infects tumor cells. The company plans to expand its preclinical evaluation of pelareorep with RAS inhibitors across additional dosing schedules and RAS-driven tumor models.

Pelareorep is an intravenously delivered, systemically active investigational immunotherapy. It is designed to selectively replicate in tumor cells while activating innate and adaptive anti-tumor immune responses. The company notes that pelareorep has been administered to over 1,200 patients and has received Fast Track designation from the FDA for colorectal, anal, and pancreatic cancer.