A Case of Immunotherapy Response to <scp> BRAF ^V600E </scp> ‐Mutant Lung Adenocarcinoma With Initial Resistance to Dabrafenib and Trametinib Combination Therapy

INTRODUCTION: The recommended first-line therapy for BRAF V600E mutant non-small cell lung cancer (NSCLC) is a combination of dabrafenib and trametinib. Most patients respond to the initial therapy, but some show resistance in the early stages. Additionally, immune checkpoint inhibitors (ICIs) are often used after resistance develops; however, the benefits of ICIs in patients with BRAF V600E mutant NSCLC remain unclear. CASE PRESENTATION: We report a case of a 67-year-old man who was clinically diagnosed with lung adenocarcinoma cT2aN3M1c (BRA) stage IVB (BRAF V600E mutation-positive, programmed death-ligand 1; 90%). The patient developed early resistance to the combination of dabrafenib and trametinib but responded well to ICI. CONCLUSION: This case suggests that ICI may provide durable clinical benefit even after early resistance to BRAF/MEK inhibition in selected patients with high PD-L1 expression.