1360PIntracranial anti-tumour activity in melanoma brain metastases with encorafenib plus binimetinib: A multicenter, retrospective analysis

Abstract Background Over 60% of patients (pts) with stage IV melanoma may develop brain metastases, resulting in a significantly increased morbidity and poor overall prognosis. Clinical data for melanoma brain metastases (MBM) treatments are limited, as controlled studies often exclude pts with untreated brain metastases. Methods We conducted a multicenter, retrospective case series investigation with consecutive pts with BRAF-mutant MBM who were treated with BRAF inhibitor encorafenib plus MEK inhibitor binimetinib to evaluate the antitumor response with this combination. Assessments included intracranial, extracranial & global objective response rates (ORRs; percentage of complete [CR] + partial [PR] responses) evaluated by modified RECIST version 1.1; clinical benefit rate (CBR; percentage of CR + PR + stable disease [SD] as best response); time to response, duration of response, and safety. Results A total of 17 pts with stage IV BRAF-mutant MBM who received encorafenib plus binimetinib in centers in the United States were included. Pts had received a median of 2 prior lines of treatment over a median of 520 days since their melanoma diagnosis (median of 55 days since diagnosis of MBM). Of the patients included, 82% had prior treatment with BRAF/MEK inhibitors. The intracranial ORR was 35% (with 3 CRs and 3 PRs) and CBR was 76%, with a median duration of response of 17 weeks. Eight pts with either stable disease or a response were still ongoing treatment at the time of this analysis. Among the 14 MBM pts with prior BRAF/MEK inhibitor treatment, the intracranial ORR was 21% and CBR was 71%. Similar outcomes were observed for extracranial and global responses. The safety profile for encorafenib plus binimetinib was similar to that observed in pts with melanoma without brain metastases. Conclusions Combination therapy with encorafenib plus binimetinib elicited intracranial activity in pts with BRAF-mutant MBM, including in pts previously treated with BRAF/MEK inhibitors. Further prospective studies are warranted. *K. Holbrook and J. Lutzky are co-first authors. Editorial acknowledgement Editorial assistance was provided by JD Cox and Mayville Medical Communications, with funding from Array Biopharma. Legal entity responsible for the study Array BioPharma Inc. Funding Array BioPharma. Disclosure J. Lutzky: Advisory / Consultancy, Speaker Bureau / Expert testimony: Array BioPharma; Advisory / Consultancy, Speaker Bureau / Expert testimony: Regeneron; Advisory / Consultancy, Speaker Bureau / Expert testimony: Novartis; Advisory / Consultancy: Bristol-Myers Squibb. A. Amin: Advisory / Consultancy, Speaker Bureau / Expert testimony: Novartis; Advisory / Consultancy, Speaker Bureau / Expert testimony: Bristol-Myers Squibb; Advisory / Consultancy: Merck; Speaker Bureau / Expert testimony: Regeneron. J.M. Davis: Speaker Bureau / Expert testimony: Exelixis Inc; Advisory / Consultancy: Array BioPharma. M.A. Davies: Advisory / Consultancy: Array BioPharma; Advisory / Consultancy: GSK; Advisory / Consultancy: Roche/Genentech; Advisory / Consultancy: Novartis; Advisory / Consultancy: Bristol-Myers Squibb; Advisory / Consultancy: Sanofi; Advisory / Consultancy: Vaccinex; Advisory / Consultancy: Syndax; Non-remunerated activity/ies: Nanostring. A. Diab: Advisory / Consultancy: Array BioPharma. I.C. Glitza: Advisory / Consultancy, Research grant / Funding (institution): Bristol-Myers Squibb; Research grant / Funding (institution): Merck; Advisory / Consultancy, Speaker Bureau / Expert testimony: Array BioPharma. R.N. Amaria: Research grant / Funding (institution): Merck; Research grant / Funding (institution): Bristol-Myers Squibb; Research grant / Funding (institution): Genentech; Research grant / Funding (institution): Array BioPharma; Research grant / Funding (institution): Iovance. S. Patel: Research grant / Funding (institution): Bristol-Myers Squibb; Advisory / Consultancy: Cardinal Health; Advisory / Consultancy: Castle Biosciences; Research grant / Funding (institution): Deciphera; Advisory / Consultancy, DSMB: Immunocore; Advisory / Consultancy: Incyte; Speaker Bureau / Expert testimony: Merck; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Provectus; Advisory / Consultancy, Research grant / Funding (institution), DSMB: Reata. H.A. Tawbi: Advisory / Consultancy, Research grant / Funding (institution): Merck; Advisory / Consultancy: Novartis; Advisory / Consultancy, Research grant / Funding (institution): Genentech; Advisory / Consultancy, Research grant / Funding (institution): Bristol-Myers Squibb; Advisory / Consultancy: Array BioPharma; Research grant / Funding (institution): Celgene; Research grant / Funding (institution): GSK. All other authors have declared no conflicts of interest.