Oncolytics details REO 033 colorectal trial design ahead of ESMO presentation

Oncolytics Biotech said on October 20, 2026 that it is presenting a trial-in-progress abstract and e-poster discussing the REO 033 study at the European Society for Medical Oncology Congress 2026.¹

REO 033 is a randomized study evaluating pelareorep in combination with folinic acid, fluorouracil, and irinotecan (FOLFIRI) and bevacizumab versus standard-of-care FOLFIRI and bevacizumab as second-line treatment for RAS-mutant, microsatellite-stable metastatic colorectal cancer patients.¹ The company said the study is designed to validate the encouraging efficacy signals observed in REO 022 while generating the controlled clinical data necessary to support future regulatory interactions and potential registration.¹

The open-label study is enrolling patients with RAS-mutated, MSS mCRC who have progressed on first-line oxaliplatin-based therapy,¹ with thirty patients per arm randomized to receive either pelareorep plus FOLFIRI and bevacizumab, or FOLFIRI and bevacizumab.¹ The primary endpoint is objective response rate, with secondary endpoints including overall survival, progression-free survival, disease control rate, duration of response, and safety and tolerability.¹ Blood and tumor samples are being collected for biomarker evaluations.¹

The company said recent FDA interactions have provided the opportunity to initiate a pivotal expansion of the REO 033 study (Part B) that would build upon the trial currently enrolling (Part A) and could support an accelerated approval submission based on ORR and a full approval based on PFS.¹

In an earlier trial, REO 022 evaluated second-line KRAS-mutant, MSS mCRC patients with treatment histories similar to those of patients enrolled in the current study, and the ORR, median PFS, median OS, and median DOR were more than doubled in patients treated with pelareorep plus FOLFIRI and bevacizumab compared to historical outcomes for patients treated with FOLFIRI and bevacizumab alone.¹

Lead investigator Sanjay Goel of Rutgers Cancer Institute said he is thrilled to see the recent momentum in the REO 033 study among sites, physicians, and patients.¹ CEO Jared Kelly said mCRC is growing faster than almost every cancer in the U.S. with only minimally effective options for second-line patients, calling it a multi-billion-dollar market that is being largely ignored because nothing works better than the standard of care.¹

The company described pelareorep as 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.¹ Oncolytics noted that pelareorep has received Fast Track designation from the U.S. Food and Drug Administration for colorectal, anal, and pancreatic cancer.¹