Clinical Application of Next-Generation Sequencing-Based Panel to BRAF Wild-Type Advanced Melanoma Identifies Key Oncogenic Alterations and Therapeutic Strategies

Molecular profiling with next-generation sequencing (NGS) has been applied in multiple solid cancers to discover potential therapeutic targets. Here, we describe the results of a clinical NGS panel in patients with advanced melanoma. Thirty-six tumor tissues from patients with BRAF wild-type melanoma at Seoul National University Hospital (SNUH; Seoul, Republic of Korea) were collected and deep-sequenced using the SNUH FIRST-Cancer NGS panel to assess single-nucleotide variants, small insertions/deletions, copy number variations, and structural variations to estimate tumor mutation burden (TMB). We discovered 106 oncogenic alterations and most of the patients (n = 33, 92%) harbored at least one oncogenic alteration, including 2 patients who were initially diagnosed as BRAF V600E-negative but were later confirmed to be positive. Altogether, 36 samples were classified into RAS/BRAF/NF1-mutant (n = 14, 39%) or triple wild-type (n = 22, 61%) melanoma subtypes. The estimated median TMB was 8.2 mutations per Mb, ranging from 0 to 146.67 mutations per Mb. Of the 36 patients, 25 (70%) had actionable alterations with currently developed drugs, and 7 (19.4%) were enrolled in dinical trials with an RAF inhibitor, multiple receptor tyrosine kinase inhibitor, and anti-programmed cell death-1 (PD-1) antibody. TMB tended to associate with progression-free survival (PFS) of treatment with anti-PD-1/PDL-1 antibody (HR, 0.96; 95% confidence interval, 0.92-1.00; P = 0.07). High-TMB (>= 13) group was associated with longer PFS than the low-TMB group (median 34.0 vs. 11.0 weeks, P = 0.04). Overall, the dinical use of a NGS panel in patients with advanced melanoma shows association with clinical outcomes and several therapeutic strategies.N