Two BRAF-V600 mutant melanoma cell lines (A375 and SAN) and their in-vitro vemurafenib and cobimetinib resistant derivatives (A375-VRCR and SAN-VRCR, respectively), two NRAS mutant melanoma cell lines (SK-MEL-2 and WM1366) and one BRAF/NRAS wild type melanoma cell line (MeWo) have been treated with AZD6738, olaparib and their combination. MTT assays have shown that all four BRAF-V600 mutant cell lines are equally sensitive to AZD6738 (IC50: 1-1,5 μM), independently from acquired in-vitro resistance to vemurafenib and cobimetinib. Combination of AZD6738 and olaparib has shown drug synergism in all these four cell lines.