SAN DIEGO — September 29, 2026
Oncolytics Biotech Inc. announced the publication of preclinical data supporting pelareorep’s ability to alter the immunosuppressive tumor microenvironment in hepatocellular carcinoma (HCC). The findings, published in Proceedings of the National Academy of Sciences, show that pelareorep infection increased markers associated with immune activation, including CD8+ T-cell density, PD-L1 expression and ICOSL levels in liver cancer models. The company said the findings support its broader development strategy of using pelareorep as a potential backbone immunotherapy to make immunologically inactive tumors more responsive to immune-based and other anticancer treatments. Oncolytics does not currently plan to pursue liver cancer as a clinical indication.
Pelareorep Converts Immunologically Inactive Tumor Environment
The published research examined mechanisms contributing to the immunosuppressive microenvironment found in hepatocellular carcinoma. HCC can be characterized by low levels of CD8+ T-cell infiltration and ICOSL alongside signaling associated with immunosuppression, including TGF-β, SOCS1 and YAP1. In the preclinical models described in the publication, pelareorep infection reversed several of these features, producing increases in CD8+ T-cell infiltration, PD-L1 expression and ICOSL signaling. These changes are consistent with a shift from an immunologically “cold” tumor environment toward a more immune-active phenotype. The findings provide mechanistic evidence for Oncolytics’ broader hypothesis that pelareorep can reshape tumor biology in ways that may facilitate immune-mediated tumor cell killing.
Immune Activation Could Support Combination Therapies
Pelareorep is being developed as an intravenous, systemically active immunotherapy designed to stimulate both innate and adaptive antitumor immune responses. The therapy selectively replicates in tumor cells while promoting inflammatory signaling, expansion of tumor-infiltrating lymphocytes and formation of tertiary lymphoid structures. Oncolytics believes these effects could create a more favorable tumor environment for combination approaches involving checkpoint inhibitors, chemotherapy, RAS-targeted therapies and other anticancer treatments. However, the newly published liver-cancer findings are preclinical and do not establish clinical efficacy in patients with HCC. The company is instead advancing pelareorep in clinical programs focused on other solid tumors, particularly gastrointestinal cancers.
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Oncolytics Advances Pelareorep Clinical Strategy
Oncolytics is currently evaluating pelareorep in combination with chemotherapy and/or checkpoint inhibitors in metastatic gastrointestinal cancers, including colorectal, anal and pancreatic cancer. The investigational therapy has received FDA Fast Track designation in colorectal, anal and pancreatic cancer, while previous clinical studies have evaluated pelareorep across breast, pancreatic, anal and colorectal cancers. More than 1,200 patients have received pelareorep across clinical studies, according to the company. The new HCC publication adds further preclinical evidence to Oncolytics’ proposed mechanism of using pelareorep to modify the tumor microenvironment and potentially enhance the activity of other cancer therapies. The company is also pursuing strategic partnerships to support further development of pelareorep across its clinical programs.
Source :Oncolytics Biotech press release
