Case Report: pembrolizumab monotherapy achieves durable disease control in a patient with BRAF V600E-mutant advanced lung adenocarcinoma and high PD-L1 expression intolerant to BRAF/MEK inhibition

Purpose To investigate the follow-up treatment options and prognosis in patient with non-small cell lung cancer (NSCLC) harboring a BRAF V600E mutation who is intolerant to targeted therapy. Case presentation A patient with a 30-year smoking history and well-controlled hypertension developed lung adenocarcinoma (left upper lobe; T2aN2MO, Stage IIIA; Karnofsky Performance Status: 90) after radical lung cancer surgery. The patient was later hospitalized for “recurrent hemoptysis” and received pemetrexed adjuvant chemotherapy combined with cisplatin. The patient, subsequently developed focal brain metastasis for which he received radiotherapy. However, the patient experienced recurrent pulmonary lesions. The genetic testing and immunohistochemistry analysis revealed the presence of a BRAF V600E mutation and high PD-L1 expression. Consequently, a targeted therapy regimen combining low to moderate doses of dabrafenib and trametinib was initiated. However, the patient developed severe and rare adverse reactions, prompting a switch to pembrolizumab monotherapy. Outcomes The patient exhibited significant symptomatic improvement, with a marked reduction in recurrent and metastatic lesions. Subsequent follow-up assessments indicated stable disease with no evidence of progression. Moreover, only one low-grade immune-related adverse event was observed during the course of immunotherapy. Conclusion Patients with advanced NSCLC and BRAF mutations who cannot tolerate targeted therapy are expected to benefit from immunotherapy.