CDC20 is a novel potential therapeutic target in NF1-mutant melanoma.

Abstract

e22075 Background: NF1-mutant melanoma (NF1-MT) is a distinct molecular subtype with worse overall prognosis than NF1-wild melanoma (NF1-WT). Despite its prevalence in 20% of patients and associated clinical disadvantage, there is no specific targeted therapy available to treat NF1-MT as its biological impact remains understudied. We tested the hypothesis that NF1-MT possess distinct genomic and transcriptomic characteristics from NF1-WT, which can potentially inform therapeutic innovation. Methods: Tumor DNA from metastatic melanoma (MM) patients treated with checkpoint inhibition at NYU was genotyped using exome sequencing. Microenvironment-related transcripts (n = 770) were then compared in NF1-MT versus NF1-WT using unsupervised clustering, differential gene expression, and gene set enrichment analyses. Verification of genomic and transcriptional findings was performed using qPCR and immunohistochemistry (IHC). TCGA melanoma (SKCM) data were analyzed as an independent cohort. Results: Pathogenic NF1 mutations were detected in 31/121 (27%) cases and were significantly associated with higher tumor mutational burden (P = 0.02). NF1-MT showed recurrent homozygous deletion in the membrane regulatory gene SYT1 and amplifications in oncogenes including CCND1 and MDM2, verified by qPCR. NF1-MT showed upregulation of proliferation with significantly increased expression of Ki-67 and cell division cycle protein 20 CDC20 (P = 0.03) validated by IHC (P = 0.03). Cell cycle was the top enriched pathway in NF1-MT (P = 0.003, FDR = 0.04). Analysis of TCGA melanoma data (n = 440) corroborated upregulation of MKI67 and CDC20 in NF1-MT melanoma (P = 0.01, P = 0.03). Conclusions: NF1-MT is associated with a hyper-proliferative tumor phenotype that cannot be only attributed to MAP kinase activation. Our data suggest that NF1-MT may be vulnerable to pharmacological inhibitors of cell cycle progression and proliferation, such as those targeting CDC20 or CDK4/6.