Dr. Bekaii-Saab on the Addition of Atezolizumab to Capecitabine/Bevacizumab in MSS mCRC

Tanios S. Bekaii-Saab, MD, FACP, medical oncologist, medical director, Cancer Clinical Research Office, vice chair and section chief, Medical Oncology, Department of Internal Medicine, Mayo Clinic, discusses the results of the phase II BACCI trial evaluating the addition of atezolizumab (Tecentriq) to capecitabine plus bevacizumab (Avastin) versus capecitabine/bevacizumab plus placebo in patients with microsatellite stable (MSS) metastatic colorectal cancer.

In the trial, 133 patients were randomized 2:1 to receive capecitabine/bevacizumab/placebo (n = 46; arm A) or capecitabine/bevacizumab/atezolizumab (n = 82; arm B). Patients enrolled on the trial had progressed on fluorouracil, oxaliplatin, irinotecan, bevacizumab, and anti-EGFR therapy. Prior treatment with PD-1/PD-L1 inhibitors was not allowed. The primary endpoint of the trial was progression-free survival (PFS).

The study was reported to have reached its prespecified primary endpoint at the 2019 ESMO Congress. The addition of atezolizumab to capecitabine/bevacizumab led to a significantly longer PFS. Specifically, in patients with MSS disease, the hazard ratio for PFS was 0.67 (0.44-1.03), which was very impressive, says Bekaii-Saab. With further analysis, Bekaii-Saab believes that the combination will eventually be evaluated in a phase III randomized trial.