Post-marketing surveillance of encorafenib in combination with binimetinib in Japanese patients with BRAF-mutant melanoma.

backgroundA BRAF inhibitor, encorafenib, combined with a MEK inhibitor, binimetinib, was approved in Japan in early 2019 for the treatment of BRAF V600-mutant, unresectable malignant melanoma based on results of the global phase III trial, COLUMBUS, conducted in various countries including Japan. This post-marketing surveillance (PMS) assessed the combination in real-world clinical practice in Japan.

methodsWe performed a prospective, multicentre, 12-month PMS of the safety and effectiveness of encorafenib plus binimetinib for radically unresectable, BRAF-mutant malignant melanoma in Japan.

resultsAmong 174 survey forms collected from 85 centres between February 2019 and August 2020, 172 were included for safety and effectiveness analysis. Patients (male [52.3%], median age 62.0 years) had Eastern Cooperative Oncology Group Performance Status 0 or 1 (91.8%) and comorbidities (55.2%). Respective encorafenib and binimetinib median dosages were 450 mg/day and 90 mg/day; median treatment duration, 24.1 and 24.2 weeks, and discontinuation, 71.5% for each, primarily for disease progression (56.9%) and adverse drug reactions (ADRs, 38.2%). Safety assessment ADRs occurred in 99 patients (57.6%), including eye disorders (40.7%), hepatic dysfunction (20.3%), rhabdomyolysis (4.7%), haemorrhage (2.3%), palmar-plantar erythrodysaesthesia syndrome (1.7%), and hypertension (1.7%); 19.8% were grade ≥ 3, none were grade 5, most resolved with/without treatment modification. At 12 months, the objective response rate was 48.8% (95% CI 41.2, 56.6; complete [19.2%], partial [29.7%]), overall survival was 40.1%.

conclusionThe safety and effectiveness of encorafenib plus binimetinib in Japanese patients with BRAF-mutant malignant melanoma were similar to data reported in COLUMBUS; no new safety concerns were identified.