On September 10, 2026 Oncolytics Biotech Inc. (Nasdaq: ONCY) ("Oncolytics" or the "Company"), a clinical-stage immunotherapy company developing pelareorep, reported positive preclinical results evaluating pelareorep in combination with a pan-RAS inhibitor in a RAS-driven colorectal cancer model.
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During the initial treatment period, when pelareorep was administered every other day, pelareorep, the pan-RAS inhibitor and the combination each reduced tumor growth compared to the control. The greatest tumor reductions were observed in the RAS inhibitor and combination groups, demonstrating that pelareorep activity was maintained in the presence of RAS inhibition without evidence of antagonism between the two therapies.
Following the transition to less frequent weekly pelareorep dosing, the incremental activity associated with pelareorep became less evident. Together, these findings support further evaluation of optimized pelareorep dosing with RAS inhibitors and the hypothesis that sustained pelareorep activity could potentially deepen or prolong responses to RAS-targeted therapy and thereby delay the emergence of treatment resistance.
Importantly, the findings are consistent with previously published independent research demonstrating that RAS inhibitors do not interfere with the mechanism through which pelareorep selectively infects tumor cells. This biological compatibility provides a rationale for further evaluating whether pelareorep’s tumor-selective and immunologic activity can complement the direct antitumor effects of RAS inhibition and potentially delay the development of resistance.
"These results provide an encouraging first look at combining pelareorep with one of the most important emerging classes of targeted cancer therapies," said Thomas Heineman, MD, PhD, Chief Medical Officer of Oncolytics. "We observed pelareorep activity during the initial intensive dosing period as well as biologic compatibility between pelareorep and RAS inhibition, supporting the continued evaluation of pelareorep/RAS inhibitor combination therapy. Because acquired resistance remains a major limitation of RAS-targeted therapies, we believe these findings provide a compelling rationale to investigate whether sustained pelareorep activity can deepen and prolong responses to RAS inhibition and potentially delay the emergence of resistance. Similarly, pelareorep, because of its unique mechanism of action, may offer a treatment option for patients who become resistant to RAS inhibitors."
Oncolytics plans to expand its preclinical evaluation of pelareorep with RAS inhibitors across additional dosing schedules and RAS-driven tumor models. These studies will be designed to further characterize pelareorep’s contribution to the combination, including its potential impact on the depth and durability of tumor response and the development of resistance to RAS-targeted therapy.
About Pelareorep
Pelareorep is an intravenously delivered, systemically active, investigational immunotherapy with a dual mechanism of action that selectively replicates in tumor cells while activating both innate and adaptive anti-tumor immune responses, including the upregulation of key inflammatory cytokines resulting in the formation of tertiary lymphoid structures and the expansion of tumor-infiltrating lymphocytes. It has been administered to over 1,200 patients, and clinical studies have demonstrated pelareorep’s potential to enhance the activity of checkpoint inhibitors and other anti-cancer therapies across multiple solid tumor types.
(Press release, Oncolytics Biotech, SEP 10, 2026, View Source [SID1234670723])