Oral mucosal melanoma (OMM) is a rare and aggressive subtype of melanoma with little known about its pathogenesis or carcinogenesis. We therefore performed whole-exome sequencing (WES) on 19 matched OMM tumor/normal pairs in order to gain insight into potential genetic drivers of tumor formation. For the first time, we describe the comprehensive mutational profile of OMM. Our data suggest that the genetic background of OMM differs from those of other melanoma subtypes. We identified recurrent mutations involving KIT, POLE, PTPRD, PTCHD2, and DMXL2. Notably, copy number analysis revealed recurrently amplified regions of 12q14 (57.9%, containing CDK4) and 5p15 (47.4%, containing TERT). CNV analysis in a separate cohort of 15 samples validated the frequent CNV in CDK4 and TERT. We also observed that the melanocyte development and pigmentation signaling pathway is frequently altered in OMM. Furthermore, our data suggest several altered genes that may be amenable for targeted therapy. We identified one patient with metastatic OMM in our cohort who was identified to harbor a targetable KIT mutation using our WES results. This patient was able to achieve complete remission following implementation of KIT-targeted therapy. These findings provide further insight into the genetic underpinnings of OMM development and suggest that patients with OMM may benefit from WES analysis to identify potential targetable genetic mutations. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

OBJECTIVEImmune checkpoint inhibitors (ICIs) improve survival in patients with advanced non–small cell lung cancer (NSCLC). Clinical trials examining the efficacy of ICIs in patients with NSCLC excluded patients with untreated brain metastases (BMs). As stereotactic radiosurgery (SRS) is commonly employed for NSCLC-BMs, the authors sought to define the safety and radiological and clinical outcomes for patients with NSCLC-BMs treated with concurrent ICI and SRS.METHODSA retrospective matched cohort study was performed on patients who had undergone SRS for one or more NSCLC-derived BMs. Two matched cohorts were identified: one that received ICI before or after SRS within a 3-month period (concurrent ICI) and one that did not (ICI naive). Locoregional tumor control, peritumoral edema, and central nervous system (CNS) adverse events were compared between the two cohorts.RESULTSSeventeen patients (45 BMs) and 34 patients (92 BMs) composed the concurrent-ICI and ICI-naive cohorts, respectively. There was no statistically significant difference in overall survival (HR 0.99, 95% CI 0.39–2.52, p = 0.99) or CNS progression-free survival (HR 2.18, 95% CI 0.72–6.62, p = 0.11) between the two groups. Similarly, the 12-month local tumor control rate was 84.9% for tumors in the concurrent-ICI cohort versus 76.3% for tumors in the ICI-naive cohort (p = 0.94). Further analysis did reveal that patients receiving concurrent ICI had increased rates of CNS complete response for BMs treated with SRS (8/16 [50%] vs 5/32 [15.6%], p = 0.012) per the Response Assessment in Neuro-Oncology (RANO) criteria. There was also a shorter median time to BM regression in the concurrent-ICI cohort (2.5 vs 3.1 months, p < 0.0001). There was no increased rate of radiation necrosis or intratumoral hemorrhage in the patients receiving concurrent ICI (5.9% vs 2.9% in ICI-naive cohort, p = 0.99). There was no significant difference in the rate of peritumoral edema progression between the two groups (concurrent ICI: 11.1%, ICI naive: 21.7%, p = 0.162).CONCLUSIONSThe concurrent use of ICI and SRS to treat NSCLC-BM was well tolerated while providing more rapid BM regression. Concurrent ICI did not increase peritumoral edema or rates of radiation necrosis. Further studies are needed to evaluate whether combined ICI and SRS improves progression-free survival and overall survival for patients with metastatic NSCLC.