Encorafenib and binimetinib followed by radiotherapy for patients with BRAFV600-mutant melanoma and brain metastases (E-BRAIN/GEM1802 phase II study).

Background: Encorafenib plus binimetinib (EB) is a standard-of-care treatment for advanced BRAFV600-mutant melanoma. We assessed the efficacy and safety of encorafenib plus binimetinib in patients with BRAFV600-mutant melanoma and brain metastasis (BM) and explored if radiotherapy improves the duration of response.

Methods: E-BRAIN/GEM1802 was a prospective, multicenter, single-arm, phase II trial that enrolled patients with melanoma BRAFV600-mutant and BM. Patients received encorafenib 450 mg once daily plus binimetinib 45 mg BID, and those who achieved a partial response or stable disease at first tumor assessment were offered radiotherapy. Treatment continued until progression. Primary endpoint was intracranial response rate (icRR) after 2 months of EB, establishing a futility threshold of 60%.

Results: The study included 25 patients with no BM symptoms and 23 patients with BM symptoms regardless of using corticosteroids. Among them, 31 patients (64.6%) received sequential radiotherapy. After 2 months, icRR was 70.8% (95% CI: 55.9-83.1); 10.4% complete response. Median intracranial progression-free survival (PFS) and OS were 8.5 (95% CI: 6.4-11.8) and 15.9 (95% CI: 10.7-21.4) months, respectively (8.3 months for icPFS and 13.9 months OS for patients receiving RDT). Most common grades 3-4 treatment-related adverse event was alanine aminotransferase (ALT) increased (10.4%).

Conclusions: Encorafenib plus binimetinib showed promising clinical benefit in terms of icRR, and tolerable safety profile with low frequency of high-grade TRAEs, in patients with BRAFV600-mutant melanoma and BM, including those with symptoms and need for steroids. Sequential radiotherapy is feasible but it does not seem to prolong response.