Adverse Events Associated with Encorafenib Plus Cetuximab in Patients with BRAFV600E-mutant Metastatic Colorectal Cancer: An in-depth Analysis of the BEACON CRC Study

Background: The BRAF inhibitor encorafenib in combination with cetuximab was recently approved for patients with BRAFV600E- mutated (BRAF V600E mut) metastatic colorectal cancer (mCRC). Approval was based on positive results from the phase 3 BEACON CRC study in BRAFV600Emut mCRC patients who had progressed after 1-2 previous regimens. This analysis provides a detailed examination of the adverse events (AEs) of interest (AEIs) with encorafenib + cetuximab in the BEACON study to aid gastrointestinal oncologists, given the limited experience with this combination. Materials and Methods: AEIs, including dermatological AEs, arthral-gia/myalgia, nausea/vomiting, diarrhea, abdominal pain, fatigue/asthenia and nephrotoxicity, were examined in the doublet therapy group. Clinical characteristics associated with these AEs, AE grade, time to onset and time to resolution were also studied. Results: Safety analysis included 216/220 patients randomized to doublet therapy. The most commonly occurring AEI was dermatological toxicity (75.5%), followed by arthralgia/myalgia (56.0%) and fatigue/asthenia (56.0%). Other than nephrotoxicity (7 patients; 5/7 with Grade 3 or 4), most AEs were Grade 1 or 2. Most AEs were more common in women than men (nausea/vomiting, diarrhea, abdom-inal pain, dermatological AEs, and arthralgia/myalgia). Nausea/vomiting, abdominal pain and fatigue/asthenia were more common in patients aged >= 70 years. Most AEs developed early, within the first 1-2 months of treatment, and resolved within 1-2 weeks. In addition, survival outcomes were better in patients experiencing arthralgia/myalgia or dermatological toxicities. Conclusion: This analysis indicated that, except for rare cases of nephrotoxicity, encorafenib + cetuximab is well tolerated in most patients, with most AEIs being mild-to-moderate in sever ity, occurr ing ear ly and resolving rapidly.Clinical Trial Registration: the BEACON study (Clini-calTrials.gov, NCT02928224; EudraCT, 2015-005805-35)