Overview

Capmatinib (Tabrecta) is an oral MET inhibitor and the first therapy approved by the FDA specifically for metastatic non-small cell lung cancer whose tumors carry a mutation leading to MET exon 14 (METex14) skipping. Because the drug works only in tumors driven by this alteration, patient selection is the decisive factor in its use. This article explains which patients are considered and how the relevant population is identified through biomarker testing.

Identifying the METex14 Population

MET exon 14 skipping is a recognized oncogenic driver that occurs in roughly 3 to 4 percent of newly diagnosed metastatic NSCLC, corresponding to several thousand patients annually in the United States. Capmatinib received accelerated FDA approval in May 2020, and that approval was paired with a companion diagnostic, reflecting a model in which the drug and its test are authorized together as a targeted pair. It appears across ages and histories but is enriched in certain subgroups, including older adults and patients with a smoking background in some series. Importantly, METex14 is a distinct target from EGFR, ALK or ROS1 alterations, so it must be tested for specifically rather than assumed. The defining molecular event is the exclusion of exon 14 from the MET transcript, which removes a negative-regulatory juxtamembrane domain and leads to sustained MET signaling through RAS, PI3K-AKT and other growth pathways.

Biomarker Testing Approaches

Selection begins with comprehensive biomarker testing at diagnosis or at disease progression. Next-generation sequencing panels can detect METex14 skipping from tumor tissue and, increasingly, from blood (liquid biopsy) when tissue is insufficient. RT-PCR and targeted RNA assays also identify the splice alteration. The FDA approved the FoundationOne CDx assay as a companion diagnostic for capmatinib, underscoring that a validated test is part of appropriate use. Testing should be broad enough to capture METex14 alongside other actionable drivers so that the most appropriate targeted therapy is chosen rather than a single-gene result. Because METex14 can be missed by assays that only look for point mutations, RNA-based methods or exome-level sequencing are often preferred for reliable detection.

FAQ

Q: Who is considered for capmatinib? A: Adults with metastatic NSCLC whose tumors have a MET exon 14 skipping alteration confirmed by an FDA-approved test, regardless of prior treatment line.

Q: How common is METex14 skipping in lung cancer? A: It is seen in approximately 3 to 4 percent of newly diagnosed metastatic NSCLC, making broad testing necessary to find eligible patients.

Q: Can liquid biopsy detect METex14 skipping? A: Yes. NGS-based plasma testing can identify METex14 skipping when tissue is limited, though tissue remains the preferred specimen when available.