A first-line multi-drug combination therapy surprised researchers when it did not meet the study’s progression-free survival (PFS) primary endpoint for metastatic colorectal cancer (CRC), according to a study the Annual Society for Immunotherapy of Cancer (SITC).

The 12-month PFS for adding the PD-1/L1 inhibitor avelumab and the EGFR inhibitor cetuximab to chemotherapy was 57% but only resulted in 40%. However, the disease control rate was 92% and approximately 80% of patients had partial response.

Joseph Tintelnot, MD, of the University of Hamburg-Eppendorf in Germany that over 80% of patients were alive after median follow-up of 16.2 months.

Single-agent anti-PD-1/L1 treatment demonstrated activity in patients with tumors with high microsatellite instability, so researchers postulated that adding avelumab to first-line-cetuximab therapy would demonstrate significant results.

The goal of ongoing studies will focus on determining the disconnect between response and the PFS endpoint.

Source: Binder M, et al “Avelumab and cetuximab in combination with FOLFOX in patients with previously untreated metastatic colorectal cancer: Final results of the phase II AVETUX trial” SITC 2019; Abstract O16.