Dramatic intracranial response to tepotinib in a patient with lung adenocarcinoma harboring MET exon 14 skipping mutation.

Mesenchymal-epithelial transition (MET) pathway activation is associated with the mechanisms that influence properties affecting cancer cell survival and invasiveness. The MET exon 14 skipping mutation (METex14del) is found in 2%-3% of patients with non-small cell lung cancer (NSCLC). Previous studies reported that NSCLC patients harboring a METex14del responded well to MET-tyrosine kinase inhibitors (TKIs), including tepotinib. Tepotinib is a highly selective, once-daily oral MET inhibitor that has shown promising clinical activity in patients with NSCLC with METex14del. The Food and Drug Administration accepted a new drug application for tepotinib as a treatment for patients with metastatic NSCLC harboring METex14del in February 2021 [Correction added on 5 March 2021, after first online publication: the FDA approval date for tepotinib has been corrected from 'September 2019' to 'February 2021'.]. However, in the previous clinical trials involving MET-TKIs, only patients with stable central nervous system metastases were eligible, and those with untreated symptomatic brain metastases (BMs) were excluded. Therefore, the efficacy and safety of MET-TKIs in that population remains unknown. We herein report a case of dramatic intracranial response to tepotinib in a patient with symptomatic BMs from lung adenocarcinoma harboring METex14del. In the current report, the symptoms derived from multiple BMs (headache and loss of appetite) rapidly disappeared, and brain magnetic resonance imaging (MRI) examination showed that all the lesions were too small to measure only 23 days after the commencement of tepotinib. For NSCLC patients with multiple BMs, whole-brain irradiation is a standard-of-care therapy, but its adverse effects on neurocognition are concerning. Tepotinib might therefore be a therapeutic option for NSCLC patients with symptomatic multiple BMs harboring METex14del.