Background: The impact of the order of treatment with checkpoint inhibitors or BRAF/MEK inhibitors on the development of brain metastases in patients with metastatic unresectable BRAFV600-mutant melanoma is unknown. The SECOMBIT trial examined the impact of the order of receipt of these treatments in such patients.
Methods: In this three-arm trial, we reviewed patients without brain metastases who received the BRAF/MEK inhibitors encorafenib and binimetinib until they had progressive disease followed by the immune checkpoint inhibitors ipilimumab and nivolumab (arm A); or treatment with ipilimumab and nivolumab until they had progressive disease followed by encorafenib and binimetinib (arm B); or treatment with encorafenib and binimetinib for 8 weeks followed by ipilimumab and nivolumab until they had progressive disease followed by retreatment with encorafenib arm binimetinib (arm C).
Results: Brain metastases were discovered during the trial in 23/69 patients in arm A, 11/69 in arm B, and 9/68 in arm C. At a median follow-up of 56 months, the 60-month brain metastases-free survival rates were 56% for arm A, 80% for arm B (hazard ratio [HR] vs. A: 0.40, 95% confidence interval [CI] 0.23 to 0.58), and 85% for arm C (HR vs. A: 0.35, 95% CI 0.16 to 0.76).
Conclusions: In patients with unresectable metastatic melanoma, the treatment sequence of immune checkpoint inhibition followed by BRAF/MEK inhibitors was associated with longer periods of new brain metastases-free survival than the reverse sequence. A regimen in which immune checkpoint inhibition was sandwiched between BRAF/MEK inhibition also appeared to be protective against brain metastases. (ClinicalTrials.gov number NCT02631447.).