Mutation Frequencies In A Gene Panel Among Primary Tumors And Metastases In Patients With Melanoma.

e21554 Background: The prevalence of mutations in main genes involved in tumorigenesis during melanoma progression remains a controversial issue. Different melanoma tissues from the same patients were investigated for prevalence and distribution of mutations in these genes. Methods: Ninety-eight tumor tissues from 36 patients with metastatic melanoma patients were screened for sequence variants in a panel of 25 genes associated with cell cycle progression, cell differentiation, angiogenesis, and tumor growth by next generation sequencing (NGS) assays. Paired samples of primary melanomas (n = 36) and synchronous or asynchronous metastases from the same patients (n = 62) were included. Secondary lesions included lymph nodal (n = 28), subcutaneous (n = 19), and visceral (n = 15) tumor samples. Results: BRAF, CDKN2A, RAS, and TP53 genes were the most frequently mutated genes. Deleterious mutations were also found in also in ARID2, CDK4, NF1, CCND1, and PTEN genes. Of 28 patients with lymph node metastases, 23 (82%) presented consistent mutation patterns in paired primary and secondary tumor samples. For visceral metastases, 11/15 (73%) patients showed a similar mutation spectrum between primary and secondary tumors. A significantly less consistency was observed in skin metastases (11/19; 58%). Conclusions: Our findings are consistent with previous studies from our group (Colombino, JCO 2012; Casula JID 2016) indicating a low heterogeneity in matched primary and lymph node metastatic samples. Assessment of the prevalence of mutations in genes involved in melanomagenesis among paired tumor lesions from patients with metastatic melanoma may further improve the management of such a disease.