Frequent Mutations of POT1 Distinguish Pulmonary Sarcomatoid Carcinoma From Other Lung Cancer Histologies.

INTRODUCTION: Pulmonary sarcomatoid carcinoma (PSC) is a rare subtype of non-small-cell lung cancer (NSCLC) harboring mutations in many canonical NSCLC-driver genes (eg, TP53, KRAS, MET). Protection of telomeres 1 (POT1) mutations are observed in angiosarcoma and chronic lymphocytic leukemia, but their frequency in other solid tumors, including NSCLC subtypes, has not been rigorously explored. MATERIALS AND METHODS: We analyzed next-generation sequencing data from 62,368 tumors, including 11,134 NSCLCs and 100 PSCs. We performed logistic regression to identify associations between POT1 mutation frequency and tumor histology across 184 tumor categories, adjusting for tumor mutational burden. We further explored co-occurring gene mutations in genes previously reported to underlie PSC tumorigenesis. RESULTS: Across 184 tumor categories, POT1 mutations were most frequent in PSC and were 14 times more common in PSC (28%) than in other tumor types (P = 1.23 × 10-31) and 6.7 times more common in PSC than other NSCLCs (P = 5.1 × 10-17). PSCs harboring KRAS mutations were significantly more likely to harbor POT1 mutations (P = 1.3 × 10-3), whereas those with TP53 mutations were less likely to harbor POT1 mutations (P = .037). One-fourth of POT1-mutated PSCs harbored a second POT1 mutation. Across all PSCs, 83% of POT1 mutations were in the OB1/OB2 (DNA-binding) domain (P = 1.5 × 10-5), an enrichment not observed in other tumor types. CONCLUSION: We report an unanticipated association between POT1 mutation and PSC. Unlike other molecular alterations that are frequent across NSCLC subtypes, POT1 mutations are largely unique to PSC. This finding may help to develop disease-defining molecular subgroups within PSC and presents opportunities for molecularly stratified prognostication and therapy.

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Author Rex Colle Bentley Pathology

Author Giselle Yvette López Pathology

Author Kyle Walsh Neurosurgery