MET alterations as resistance mechanisms of dabrafenib-trametinib in BRAF p.V600E mutated non-small cell lung cancer patient.

The combination of BRAF and MEK inhibitors demonstrated significant clinical benefit in patients with BRAF-mutant non-small cell lung cancer (NSCLC). However, the molecular mechanisms of acquired resistance to BRAF and MEK inhibition in NSCLC are still unknown. Herein, we report a case of a 76-year-old man with a history of smoking who was diagnosed with BRAF V600E-mutant lung adenocarcinoma (PD-L1 > 50%) and subsequently candidate to first-line therapy with pembrolizumab. After 18 months since the start of immunotherapy, computed tomography scan showed disease progression and a second-line therapy with dabrafenib and trametinib was initiated. Seven months later, due to a suspect disease progression, a left supraclavicular lymphadenectomy was performed and next-generation sequencing analysis revealed the appearance of MET exon 14 skipping mutation, while fluorescence in situ hybridization analysis showed MET amplification. The patient is still on BRAF and MEK inhibitor treatment. Our case highlights the relevance of performing tumor tissue rebiopsy at the time of progression during treatment with BRAF/MEK inhibition with the aim of identifying putative mechanisms of resistance.