Nonsmall Cell Lung Carcinoma with Giant Cell FeaturesExpressing Programmed Death-Ligand 1: A Report of a PatientSuccessfully Treated with Pembrolizumab

Giant cell carcinoma, a rare variant of nonsmall cell lung carcinoma (NSCLC), is characterized by aggressive progression and poorresponse to conventional chemotherapy. *is report is the first to describe a patient with NSCLC and giant cell features who wassuccessfully treated with pembrolizumab, an antibody targeting programmed death-1 (PD-1). A 69-year-old woman was di-agnosed with NSCLC with multiple brain metastases. Histological evaluation of lung biopsy specimens revealed proliferation ofpleomorphic giant tumor cells with poor cohesiveness, findings consistent with giant cell carcinoma. Immunostaining showedthat a high proportion of the tumor cells were positive for expression of programmed death-ligand 1 (PD-L1). *e patient receivedstereotactic radiotherapy for the brain metastases, followed by administration of pembrolizumab. Treatment with pembrolizumabresulted in the rapid regression of the primary lung nodule, with the progression-free period maintained for at least four treatmentcycles. Immunotherapy targeting PD-1/PD-L1 may be an option for patients with PD-L1-positive NSCLC with giant cell features.