Rationalizing Use of Pembrolizumab/Bevacizumab in Recurrent Ovarian Cancer

Emese Zsiros, MD, PhD, FACOG, assistant professor of oncology, Department of Gynecologic Oncology, Center for Immunotherapy, Roswell Park Comprehensive Cancer Center, explains the rationale for the a phase II study, which combined pembrolizumab (Keytruda) with bevacizumab (Avastin) in patients with recurrent ovarian cancer. Zsiros presented data on the study in early 2019 at the Society of Gynecologic Oncology (SGO) Annual Meeting.

The rationale for the phase II open-label study of pembrolizumab plus bevacizumab versus pembrolizumab alone was to understand whether the efficacy seen with single-agent pembrolizumab can be enhanced with the addition of bevacizumab, an anti-angiogenic agent and an oral cyclophosphamide.

Investigators hypothesized that by adding bevacizumab to pembrolizumab, they could block the VEGF pathway, attract more T cells to the tumor microenvironment, and decrease the local immunosuppression. They also believed that the addition of low-dose oral cyclophosphamide was expected to deplete the regulatory T cells to potentially augment immunotherapeutic agents, says Zsiros.