Efficacy-effectiveness analysis on survival in a population-based real-world study of BRAF-mutated metastatic colorectal cancer patients treated with encorafenib-cetuximab

Encorafenib-cetuximab has been approved for pretreated BRAF^V600E-mutated metastatic colorectal cancer (mCRC) patients based on efficacy demonstrated in the randomized phase III BEACON trial. The aim of this real-world effectiveness study is to improve knowledge on the generalizability of trial results.

This population-based real-world study includes all mCRC patients in the Netherlands treated with encorafenib-cetuximab since approval. Individual patient data and pathology reports were collected. Overall survival (OS) was compared to BEACON and subgroup analyses were conducted for patients who would have been eligible and ineligible for BEACON.

166 patients were included with a median follow-up time of 14.5 months. Median OS was 6.7 months (95% CI:6.0–8.3) and differed from BEACON (9.3 months; 95% CI:8.0–11.3, p-value 0.002). Thirty-six percent of real-world patients would have been ineligible for the BEACON trial. Trial ineligible subgroups with symptomatic brain metastases and WHO performance status ≥2 had the poorest median OS of 5.0 months (95% CI:4.0-NR) and 3.9 months (95% CI:2.4-NR).

This real-world cohort of mCRC patients treated with encorafenib-cetuximab showed a clinically relevant efficacy-effectiveness gap for OS. The chance of survival benefit from encorafenib-cetuximab in patients with brain metastases and/or WHO performance status ≥2 is negligible as neither efficacy nor effectiveness has been demonstrated.