Pelareorep Plus Atezolizumab Shows Durability, Survival at 1 Year in Anal Cancer

Responses to the investigational immunotherapy pelareorep combined with atezolizumab (Tecentriq) were durable in patients with previously treated squamous cell anal carcinoma (SCAC), and all patients with responses were alive beyond 1 year, according to updated data from the phase 1/2 GOBLET study.¹

In cohort 4 of GOBLET, which enrolled patients with SCAC in the second line or later, the median duration of response (DOR) was approximately 15 months, according to Oncolytics Biotech, the sponsor. Median overall survival (OS) had not been reached, and several responders had survived longer than 24 months.

"We see anal cancer as the starting point for building a pelareorep plus checkpoint inhibitor platform across HPV-driven cancers," said Jared Kelly, chief executive officer of Oncolytics, in a news release.

Study Design

Pelareorep is an intravenously administered oncolytic reovirus that selectively replicates in tumor cells and is designed to activate innate and adaptive antitumor immune responses, according to the company.

GOBLET is an open-label, multicohort study of pelareorep combined with atezolizumab, with or without other agents, in patients with advanced or metastatic gastrointestinal cancers ongoing at 17 sites in Germany. Its coprimary end points are overall response rate (ORR) and/or disease control rate and safety. Cohort 4 is evaluating pelareorep plus atezolizumab in patients with advanced, unresectable anal cancer after prior treatment; other cohorts include patients with pancreatic and colorectal cancers.

Earlier Cohort 4 Results

In January 2026, the company reported a 29% ORR among 14 evaluable patients treated in the third line, with 2 complete and 2 partial responses and a median DOR of approximately 17 months. In second-line patients, the combination was associated with an ORR of 30% and a median DOR of 15.5 months.²

As a historical comparator, the company cited the 9.5-month DOR reported for retifanlimab (Zynyz) monotherapy in the phase 2 POD1UM-202 trial (NCT03597295) in a similar patient population of patients with SCAC that progressed after platinum-based chemotherapy.³

Next Steps and Regulatory Path

Pelareorep received FDA fast track designation in second-line and later anal cancer in July 2026. After recent discussions with the FDA, Oncolytics intends to pursue further trials in this setting, potentially alongside a checkpoint inhibitor developer, to support registration for approval in SCAC.¹ The company said that durable responses could support an accelerated approval pathway and that OS could serve as confirmatory evidence for full approval, depending on agreement from the FDA.

More than 90% of SCAC cases are associated with human papillomavirus (HPV), according to the company. Consequently, Oncolytics also plans to evaluate whether the approach can be extended to HPV-associated head and neck squamous cell carcinoma, in which pelareorep has shown signs of activity but has not yet been studied with a checkpoint inhibitor.

REO 033 (NCT07446322), a second-line trial of folinic acid, fluorouracil, and irinotecan plus bevacizumab (Avastin) with or without pelareorep in microsatellite-stable RAS-mutant colorectal cancer launched earlier this year and presented its study design in a poster at the 2026 ESMO Congress.⁴

REFERENCES

1. Oncolytics Biotech® Reports Strong Durability and Survival Data in Anal Cancer, Positioning Pelareorep as Potential Backbone Immunotherapy Across HPV-Driven Cancers. News release. Oncolytics Biotech. October 27, 2026. Accessed October 28, 2026. https://tinyurl.com/c5njjhp9

2. Oncolytics Biotech® announces updated clinical data from GOBLET cohort 4 demonstrating activity of pelareorep plus atezolizumab in third-line anal cancer. News release. Oncolytics Biotech. January 12, 2026. Accessed October 28, 2026. https://tinyurl.com/y79zuw58

3. Rao S, Capdevila J, Gilbert D, et al. Phase II study of retifanlimab in patients (pts) with squamous carcinoma of the anal canal (SCAC) who progressed following platinum-based chemotherapy. Ann Oncol. 2020. doi:10.1016/j.annonc.2020.08.2272

4. Goel S, Mahalingam D, Morris V, et al. Phase 2 randomized, controlled study of pelareorep combined with 5-fluorouracil/leucovorin/ irinotecan (FOLFIRI) + bevacizumab (bev) for the second-line treatment of RAS-mutated, microsatellite-stable (MSS) metastatic colorectal cancer. Presented at: 2026 ESMO Congress; October 23-27, 2026; Madrid, Spain. Poster 994eTiP.