Oncolytics Biotech Inc. Announces Updated Randomized Phase 2 Data from BRACELET-1 Metastatic Breast Cancer Trial That Show Pelareorep Driving Robust Increases in Progression-Free Survival and Confirmed Overall Response Rate

Oncolytics Biotech Inc. announced updated results from BRACELET-1, a randomized phase 2 trial in HR+/HER2- metastatic breast cancer, which include data featured in an oral presentation at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting, as well as additional new data and analyses. BRACELET-1 enrolled 48 patients, including 45 that were randomized and well-balanced across three cohorts evaluating: (1) paclitaxel monotherapy; (2) paclitaxel in combination with pelareorep; and (3) paclitaxel plus pelareorep in combination with the anti-PD-L1 checkpoint inhibitor, avelumab (Bavencio). A three-patient safety run-in was also conducted with patients receiving pelareorep, paclitaxel, and avelumab prior to randomization.

All participants enrolled in the trial had previously progressed on at least one hormone-based therapy with a CDK 4/6 inhibitor. No patients in BRACELET-1 received chemotherapy for metastatic disease prior to enrolling in the trial. Updated data from BRACELET-1 showed a median progression-free survival (mPFS) of 9.5 months in the paclitaxel plus pelareorep cohort vs.

6.3 months in the paclitaxel monotherapy cohort for a hazard ratio of 0.29 as of a March 3, 2023 cut-off date. Confirmed overall response rate (ORR) in these cohorts was 37.5% and 13.3%, respectively. As previously reported, ORR at week-16 (the trial's primary endpoint) in the pelareorep plus paclitaxel and paclitaxel monotherapy cohorts was 31.3% and 20%, respectively.

Overall survival data from the trial continue to mature. Key biomarker and safety findings from BRACELET-1 include: Association between T cell expansion and efficacy measures: A statistically significant increase in T cell fraction, a measure of T cell expansion, was observed in cohort 2 (paclitaxel + pelareorep) but not cohort 3 (paclitaxel + pelareorep + avelumab); Generally favorable and manageable safety profile: Pelareorep displayed a manageable safety profile consistent with what has been observed in prior clinical trials that have collectively treated over 1,100 patients.