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Oncolytics Biotech Inc, a clinical-stage immunotherapy company, has announced compelling survival data for its intravenously delivered oncolytic virus immunotherapy, pelareorep (Reolysin), across multiple tumor types, signaling a strategic shift toward registration-enabling clinical trials.1
The company highlights significant 2-year overall survival (OS) benefits in metastatic pancreatic ductal adenocarcinoma (mPDAC) and consistent survival improvements in hormone receptor-positive/HER2-negative (HR+/HER2–) metastatic breast cancer, both indications where immunotherapy options remain limited. This advancement underscores pelareorep’s potential to establish new therapeutic benchmarks and addresses critical unmet needs in difficult-to-treat malignancies.
In first-line mPDAC, pooled data from over 100 patients across 2 completed studies demonstrated a robust 2-year OS rate of 21.9% compared with a 9.2% historical benchmark. Specifically, the REO 017 study (NCT00998322), which evaluated pelareorep combined with gemcitabine, reported 1-year and 2-year survival rates of 45% and 24%, respectively, significantly higher than the gemcitabine benchmark of 22% and 4%.In the NCI 8601 study, pelareorep with paclitaxel/carboplatin also showed favorable 1-year (34% vs 28%) and 2-year (20% vs 6%) OS rates compared with the control arm.
Furthermore, the single-arm REO 029 study involving pelareorep, gemcitabine/nab-paclitaxel, and atezolizumab (Tecentriq) yielded a best-in-class 62% objective response rate (ORR) in 13 evaluable patients, exceeding the 23% benchmark. These results are particularly notable given the current absence of approved immunotherapies for first-line mPDAC, a cancer historically unresponsive to immune-based treatments.
Clinical activity for pelareorep has also been observed in HR+/HER2– metastatic breast cancer, a large patient population with substantial unmet medical need. Two randomized phase 2 studies, IND.213 (NCT01656538) and BRACELET-1 (NCT04215146), reported a median OS benefit exceeding 10 months when pelareorep was combined with standard-of-care chemotherapy. The IND.213 study showed a median OS of 21.0 months vs 10.8 months, while BRACELET-1 demonstrated a median progression-free survival (PFS) of 12.1 months with pelareorep plus paclitaxel, compared with 6.4 months for paclitaxel alone. These consistent improvements in both mPDAC and HR+/HER2– metastatic breast cancer suggest a broad therapeutic applicability for pelareorep.
Across more than 1100 patients enrolled in various studies, pelareorep has consistently exhibited a favorable and well-understood safety profile. The most common treatment-related adverse events (TRAEs) typically present as transient, manageable “flu-like” symptoms, including fever, chills, headache, and fatigue. Clinically significant grade ≥3 TRAEs were rare, reinforcing the drug’s tolerability.
Pelareorep operates as an immunotherapeutic agent by inducing anticancer immune responses and transforming immunologically “cold” tumors into “hot” inflamed phenotypes, making them more susceptible to immune-mediated attack.2 This mechanism allows pelareorep to synergize with various approved oncology treatments, creating new avenues for immune-based combination therapies in cancers traditionally resistant to immunotherapy.
“Pelareorep represents a tipping point for immunotherapy in cold tumors,” said Thomas Heineman, MD, chief medical officer of Oncolytics, in a press release.1 “It is delivering consistent immunologic and clinical responses in multiple tumor types. Most impressively, pelareorep activates the immune system to produce clinical benefits in cancers that are typically unresponsive to immunotherapies like mPDAC and unresectable HR+/HER2– breast cancer, creating new oncology entry points for immune-based combination therapies.”
The compelling efficacy and favorable safety profile have prompted Oncolytics to streamline its development strategy, focusing directly on registration-enabling trials. Pelareorep has received fast track designations from the FDA for metastatic breast cancer and mPDAC in combination with chemotherapy and atezolizumab. Additionally, it holds orphan drug designations from both the FDA and the European Medicines Agency for pancreatic cancer.