Immunotherapy with pembrolizumab in a patient with advanced non-small-cell lung cancer with high PD-L1 expression and MET exon 14 splice site mutation

Lung cancer is one of the major oncological problems in Poland. Pembrolizumab monotherapy can be applied as first-line treatment in patients with advanced non-small-cell lung cancer (NSCLC) with the expression of programmed death ligand 1 (PD-L1) in ≥ 50% of tumor cells. The article presents a case report of a female patient with advanced lung adenocarcinoma and high PD-L1 expression and an additional MET exon 14 skipping mutation. Despite the advanced stage of the disease, the patient benefited spectacularly from pembrolizumab administered following stereotactic radiotherapy for central nervous system (CNS) metastases. Partial remission followed by long-term stabilization of the disease was achieved. Unfortunately, the therapy was discontinued due to grade-3 pulmonary toxicity observed after 3 years of treatment. Despite the discontinuation of the pembrolizumab therapy, the disease has currently been stabilized and inflammatory changes have slowly resolved upon administration of corticosteroid