NEW YORK – Oncolytics Biotech on Thursday said it is seeking funds for a registration-enabling study of pelareorep-based therapy in advanced or metastatic breast cancer.
Pelareorep is a virus-based investigational agent that Oncolytics believes could help to trigger immune reactions to cancer cells, inflaming "cold" tumors so they turn "hot."
The move toward a registration-directed study follows positive results from the three-arm Phase II BRACELET-1 study of pelareorep plus paclitaxel chemotherapy versus pelareorep plus chemo and Merck KGaA and Pfizer's monoclonal antibody Bavencio (avelumab) versus chemo alone. Oncolytics randomized 45 patients with previously treated, hormone receptor (HR)-positive, HER2-negative advanced breast cancer into one of these arms.
After two years of follow-up, the firm said that adding pelareorep to chemo significantly benefited patients compared to just chemo, but not so much when Bavencio was included in the regimen. "The activation of cytotoxic T cells by pelareorep, critical for its anti-tumor effect, was suppressed by the addition of avelumab," Oncolytics said in a statement. "This likely resulted from avelumab's ability to bind Fc receptors, leading to the elimination of pelareorep-induced immune responses through antibody-dependent cellular cytotoxicity and other mechanisms."
As for the benefit seen with pelareorep and chemotherapy versus chemo alone, the median overall survival among patients who received the combined treatment was not reached at the time of data analysis versus 18.2 months among those receiving only chemo. The two-year overall survival rate for patients on pelareorep-chemo was 64 percent versus 33 percent on chemo alone.
When researchers looked at patients' progression-free survival, they found that patients on pelareorep-chemo lived a median of 12.1 months versus 6.4 months on chemo. The overall response rate was 37.5 percent on the combination treatment versus 13.3 percent on chemo.
The overall survival results from BRACELET-1 combined with the positive data from a previously conducted randomized trial, called IND-213, support the benefit of adding pelareorep to chemotherapy as a treatment for HR-positive, HER2-negative breast cancer, Oncolytics said. According to the Canadian firm, if the BRACELET-1 trial had continued to follow patients, the median overall survival in the pelareorep-chemo arm would have been 32.1 months.
Beyond HR-positive, HER2-negative advanced breast cancer, Oncolytics is also evaluating pelareorep in combination with other treatments in various solid tumor indications, including in gastric cancers.
The firm recently met with the US Food and Drug Administration to discuss key design elements for the upcoming registration-directed trial for pelareorep, Oncolytics Chief Medical Officer Thomas Heineman said in a statement.