A Noncanonical MET Exon 14 Splice-Site Variant in Pulmonary Sarcomatoid Carcinoma With Response to Capmatinib.

MET exon 14 skipping is an actionable oncogenic driver in non-small cell lung carcinoma (NSCLC); however, noncanonical splice-region variants are frequently classified as variants of unknown significance (VUS), which may result in missed therapeutic opportunities and highlight limitations in current DNA next-generation sequencing (NGS) reporting criteria. We report a patient with pulmonary sarcomatoid carcinoma harboring a noncanonical MET splice donor-proximal indel (c.3022_3028 + 13delinsA), initially interpreted as a VUS, who achieved a rapid and durable response to capmatinib. Subsequent RNA sequencing and droplet digital PCR (ddPCR) confirmed MET exon 14 skipping, supporting the value of orthogonal transcript-level validation for exon-adjacent variants.