On December 16, 2025 Oncolytics Biotech Inc. (Nasdaq: ONCY) ("Oncolytics" or the "Company"), a clinical-stage immunotherapy company developing pelareorep, reported clinical and translational findings supporting the development of pelareorep in second-line metastatic colorectal cancer ("mCRC"), specifically in patients with KRAS-mutant, microsatellite-stable ("MSS") disease. This represents one of the most difficult-to-treat and least responsive subgroups within colorectal cancer.
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In a previously completed clinical study evaluating pelareorep in combination with standard-of-care therapy, 33% of KRAS-mutant MSS patients achieved an objective response, compared to the well-established historical objective response rate ("ORR") of approximately 6–11% for Avastin (bevacizumab) + FOLFIRI in second-line mCRC.1, 2 In that same study, patients receiving the pelareorep, bevacizumab, and FOLFIRI treatment regimen more than doubled progression-free survival and overall survival compared to those receiving bevacizumab and FOLFIRI (click here for the PR).
In addition to the clinical activity, a separate translational analysis of paired tumor biopsies revealed that treatment with pelareorep led to a notable increase in KRAS-mutant–specific T-cell populations, indicating that pelareorep may directly enhance anti-tumor immune recognition in this genetically defined subgroup. These findings provide strong biological support for pursuing pelareorep as a precision immunotherapy capable of addressing a patient population that rarely benefits from checkpoint inhibitors or other immunotherapies. A complete analysis of the translational data will be presented at an upcoming medical meeting.
"Colorectal cancer is the core of our emerging GI tumor platform strategy for pelareorep, with a projected total addressable market of $20 billion by 2033,"3 said Jared Kelly, Chief Executive Officer of Oncolytics Biotech. "Pelareorep has clearly demonstrated the potential to become a transformational new treatment option in this underserved setting. With translational data supporting its unique activation of KRAS-specific T cells, pelareorep has delivered a 33 percent response rate in KRAS-mutant, MSS colorectal cancer."
Dr. Sanjay Goel, Professor of Medicine at Rutgers Cancer Institute of New Jersey and a leading investigator in GI oncology, commented: "These results are extremely encouraging. Achieving a 33% ORR in KRAS-mutant MSS colorectal cancer is highly unusual in this setting and warrants immediate further study. The translational findings strengthen the mechanistic rationale behind the clinical activity we’re observing. I am eager to move this program into a controlled study to validate the signal and help bring a much-needed therapeutic option to this patient population."
Together, the clinical and mechanistic data support advancing pelareorep into a controlled study in second-line KRAS-mutant MSS mCRC, which the company expects to initiate following consultation with key opinion leaders and regulatory authorities. The planned study is intended to confirm pelareorep’s potential to significantly outperform the current standard-of-care in a controlled setting and establish a new treatment paradigm for KRAS-mutant colorectal cancer. By sponsoring the study instead of pursuing an investigator-sponsored trial, Oncolytics will be able to provide an appropriate level of analytical rigor to support regulatory submissions that could lead to an approval in this indication. Additionally, the Company will have full control over data from the study and will be able to update investors, potential partners, and other stakeholders at its discretion. This change reflects the Company’s heightened interest in and focus on mCRC and pelareorep’s potential as a platform gastrointestinal immunotherapeutic agent.
(Press release, Oncolytics Biotech, DEC 16, 2025, View Source [SID1234661459])