Oncolytics Biotech said substantially all planned clinical sites for its REO 033 colorectal cancer study are now activated, with multiple patients enrolled and the company expecting enough Part A data to provide an interim clinical update by year-end 2026. The update, disclosed in a Sept. 28 SEC filing, marks the latest operational milestone for the randomized study of pelareorep in second-line RAS-mutant, microsatellite-stable metastatic colorectal cancer.
REO 033 is evaluating pelareorep in combination with FOLFIRI and bevacizumab against FOLFIRI and bevacizumab alone. Part A is designed to enroll approximately 60 patients across the two treatment arms, with objective response rate as its primary endpoint and progression-free survival, overall survival, safety and biomarker analyses among the additional endpoints. Oncolytics said the focus has now shifted from opening trial sites to accelerating enrollment and generating randomized clinical data.
The company expects the pace of enrollment to allow an interim Part A update by the end of 2026, based on the number of evaluable patients enrolled by the end of October. The timing is a company expectation rather than a guaranteed data release, and the Sept. 28 filing cautions that clinical development timelines and outcomes remain subject to trial execution, regulatory decisions and other risks.
The trial is also being developed with a potential regulatory pathway discussed with the U.S. Food and Drug Administration. Oncolytics said it has aligned with the FDA on the concept for a potential pivotal Part B expansion, under which objective response rate could support a potential accelerated approval application while progression-free survival could provide the basis for potential full approval. The company expects results from Part A to help determine the final size and execution of any Part B expansion.
The regulatory discussions build on written FDA feedback announced by Oncolytics in August. The company said that feedback supported the concept of expanding the ongoing randomized study into a pivotal Part B, while the proposed pathway remains subject to further regulatory discussions and clinical results. The potential approval routes described by the company are not an FDA approval of pelareorep or a determination that the drug is effective.
REO 033 follows earlier results from the company’s REO 022 study, a smaller non-randomized trial. Oncolytics reported an objective response rate of 33% in REO 022, with median progression-free survival of 16.6 months and median overall survival of 27.0 months for the pelareorep combination. The company has emphasized that comparisons with historical benchmarks have inherent limitations and that REO 033 is intended to test the treatment prospectively against a concurrent control arm.
Pelareorep is an investigational intravenous immunotherapy that Oncolytics is developing across gastrointestinal cancers. The company says the therapy is designed to activate innate and adaptive immune responses and has received FDA Fast Track designation for colorectal, anal and pancreatic cancer indications.
The clinical progress comes while Oncolytics continues to fund development as a clinical-stage biotechnology company. Its June 30 quarterly filing showed $4.1 million in cash and cash equivalents, compared with $5.2 million at the end of 2025, while the company reported an $18.7 million net loss for the first six months of 2026. Research and development expenses rose to $8.8 million from $4.7 million a year earlier, while general and administrative expenses increased to $9.8 million from $5.0 million.
Oncolytics had 127.5 million common shares outstanding as of Aug. 10, according to its second-quarter filing. The company has also used equity financing arrangements during 2026, underscoring the importance of capital access as it advances REO 033 and its other clinical programs.
The immediate milestone is therefore the expected Part A interim update rather than a regulatory filing for approval. If enrollment proceeds as planned, the year-end data will provide the first randomized clinical assessment of pelareorep’s contribution to the REO 033 treatment regimen and could inform the company’s next steps for the proposed pivotal Part B expansion.
