Dabrafenib plus trametinib in patients with BRAFV600-mutant melanoma brain metastases (COMBI-MB): a multicentre, multicohort, open-label, phase 2 trial

Abstract

Summary Background Dabrafenib plus trametinib (D+T) improves outcomes in BRAF V600–mutant metastatic melanoma without brain metastases; however, activity of D+T has not been studied in active melanoma brain metastases (MBM). Here, we report results from the phase 2 trial COMBI-MB. Our aim was to build upon the current body of evidence of targeted therapy in melanoma brain metastases through an evaluation of D+T in patients with BRAF V600–mutant melanoma brain metastases. Methods This ongoing open-label, phase 2 study (NCT02039947) evaluated dabrafenib 150 mg twice daily plus trametinib 2 mg once daily in four melanoma patient cohorts: (A) BRAF V600E, asymptomatic MBM, no prior local brain therapy; (B) BRAF V600E, asymptomatic MBM, prior local brain therapy; (C) BRAF V600D/K/R, asymptomatic MBM, with or without prior local brain therapy; and (D) BRAF V600D/E/K/R, symptomatic MBM, with or without prior local brain therapy. The primary objective was to assess intracranial response rate (IRR) in cohort A in the all-treated-subjects population. Secondary endpoints included IRR in cohorts B–D; extracranial and overall response rates; disease control rates; duration of intracranial, extracranial, and overall response; progression-free survival; overall survival; and safety. Findings A total of 125 patients were enrolled (A: n=76; B: n=16; C: n=16; D: n=17). At the data cutoff (November 28, 2016; median follow-up 8·5 months) investigator-assessed IRR was 58% (n=44/76) in cohort A. Intracranial response by investigator assessment was also achieved in 9 (56%) of 16 patients in cohort B, 7 (44%) of 16 patients in cohort C, and 10 (59%) of 17 patients in cohort D. Safety results were consistent with prior D+T studies, with 60 (48%) of 125 patients across cohorts experiencing grade 3/4 adverse events. The most common serious adverse events across cohorts were pyrexia (n=9/125; 7%) and ejection fraction decreased (n=5/125; 4%). Interpretation D+T was active with a manageable safety profile in patients with BRAF V600–mutant MBMs, but the median duration of response was relatively short. These results provide evidence of clinical benefit with D+T and support the need for additional research to further improve outcomes in patients with MBMs. Funding Novartis.