A melanoma mutation panel for individualized treatment of patient-derived melanoma cell cultures

Purpose: To identify new targets in melanoma for targeted treatment based on a mutational analysis of melanoma cell lines and subsequent individualized treatment combinations. Experimental Design: A series of 57 melanoma cell lines (mostly short-term cultures) are analyzed for their mutation pattern based on a mutation panel of 83 genes selected from the most abundant mutations (more than 5 % of samples). Of these, 28 cell lines are treated with small molecule inhibitors either as single-agent or combination therapy. Most effective therapies are estimated by Chou Talaley method, applied to multiple drug treatments, based on growth characteristics of melanoma cells during life-cell imaging. Results: In a number of cell lines, combination treatment showed better treatment response rates than monotherapy. BRAFi and an inhibitor of a further pathway is more efficient to induce an anti-proliferative effect than the standard therapy with a BRAFi-MEKi combination. Among these are PI3K/mTOR inhibitor apitolisib either together with a BRAFi or as triple combination with BRAFi/MEKi. A combination of BRAFi and CDK4/6 inhibitor palbociclib also showed significant synergy. The most promising drug combinations in NRASmut cell lines is a triple combination of MEKi, ERKi and and PI3K/mTOR apitolisib, or a combination of MEKi, apitolisib and aurora A kinase inhibitor alisertib. Transcriptomic analysis showed that BRAF and NRAS mutant cell lines could be differentiated by ARHGAP42 and DLD expression, both higher expressed in BRAFmut cell lines, and ARHGAP42 being a putative new target for BRAFmut melanoma cells. Conclusion: Combination treatment of melanoma cells with individual drug combinations based on mutational patterns are sometimes more effective than monotherapy or classical double-agent therapy and may thereby replace classical treatment approaches.