The genetic evolution of treatment-resistant cutaneous, acral and uveal melanomas

Purpose: Melanoma is a biologically heterogeneous disease composed of distinct clinicopathologic subtypes that frequently resist treatment. To explore the evolution of treatment resistance and metastasis, we used a combination of temporal and multi-lesional tumor sampling in conjunction with whole exome sequencing of 110 tumors collected from seven patients with cutaneous (n=3), uveal (n=2) and acral (n=2) melanoma subtypes. Experimental Design: Primary tumors, metastases collected longitudinally, and autopsy tissues were interrogated. All but one patient died due to melanoma progression. Results: For each patient, we generated phylogenies and quantified the extent of genetic diversity among tumors, specifically among putative somatic alterations affecting therapeutic resistance. Conclusions: In four patients who received immunotherapy, we found 1-3 putative acquired and intrinsic resistance mechanisms coexisting in the same patient, including mechanisms that were shared by all tumors within each patient, suggesting that future therapies directed at overcoming intrinsic resistance mechanisms may be broadly effective.