van Herpen CML, Agarwala SS, Hauschild A, Berking C, Beck JT, Schadendorf D, Jansen R, Queirolo P, Ascierto PA, Blank CU, Heinrich MC, Pal RR, Derti A, Antona V, Nauwelaerts H, Zubel A, and Dummer R
BRAF and RAS are the most frequently mutated mitogen-activated protein kinase (MAPK) genes in melanoma. Binimetinib is a highly selective MAPK kinase (MEK) 1/2 inhibitor with clinical antitumor activity in NRAS - and BRAF V600 -mutant melanoma. We performed a nonrandomized, open-label phase II study, where 183 metastatic melanoma patients received binimetinib 45 mg / 60 mg twice-daily ( BRAF arms), or binimetinib 45 mg twice-daily ( NRAS arm). Biomarker analyses were prespecified as secondary and exploratory objectives. Here we report the extent of MAPK pathway inhibition by binimetinib, genetic pathway alterations of interest, and potential predictive markers for binimetinib efficacy. Twenty-five fresh pre- and post-dose tumor sample pairs were collected for biomarker analyses, which included assessment of binimetinib on MEK/MAPK signaling by pharmacodynamic analysis of pERK and DUSP6 expression in pre- vs post-dose tumor biopsies; identification of pERK and DUSP6 expression/efficacy correlations; assessment of baseline tumor molecular status; and exploration of potential predictive biomarkers of efficacy of binimetinib. The postbaseline pERK and DUSP6 expression decreased across all arms; no association between reduced pERK or DUSP6 levels with clinical efficacy was observed. Genetic aberrations were similar to previously reported data on clinical melanoma samples. Genetic pathway alterations occurred predominantly within CDKN2A/B , PTEN , and TRRAP ( BRAF -mutation) and CDKN2A/B , TP53 , and NOTCH2 ( NRAS -mutation). Several patients with BRAF mutations had amplification of genes on chromosome 7q; these patients tended to have shorter progression-free survival than other patients with BRAF -mutant melanoma. Further analysis of genetic alterations, including amplifications of growth factor genes, will determine utility as biomarkers for efficacy., Competing Interests: CONFLICTS OF INTEREST CvH reports grants from Astra Zeneca, Merck, MSD, Novartis outside the submitted work. AH reports grants from Amgen, BMS, Celgene, Eisai, GSK, Merck Serono, MSD/Merck, Novartis, Roche, other from Amgen, BMS, MedImmune, MSD/Merck, Nektar Therapeutics, Novartis, Oncosec, Philogen, Provectus, Regeneron, Roche outside the submitted work; CB reports personal fees from Amgen, GSK, personal fees and non-financial support from Merck Sharp & Dohme, Novartis, BMS, and from Roche, personal fees from AstraZeneca, outside the submitted work; DS reports personal fees and other from Amgen, grants, personal fees and other from BMS, personal fees and other from Novartis, Roche, and Array, grants, personal fees and other from Merck/MSD, personal fees from Pfizer, outside the submitted work; PAA reports grants and personal fees from BMS, Roche-Genentech, Ventana, and Array, personal fees from Novartis, Amgen, and from Merck Sharp & Dohme, outside the submitted work; MCH reports grants and personal fees from Novartis, personal fees from MolecularMD, during the conduct of the study; grants and personal fees from Blueprint Medicines, personal fees from Pfizer, outside the submitted work; RRP, AD, VA, HN, AZ were employed by Novartis; RD reports research funding from Novartis, MSD, BMS, Roche, GSK, and has consultant or advisory board relationship with Novartis, MSD, BMS, Roche, GSK, and Amgen. All remaining authors have declared no conflicts of interest.