A Histologically Complete Response to Immunotherapy UsingPembrolizumab in a Patient with Giant Cell Carcinoma of theLung: An Additional Report and Literature Review

We previously reported a case of giant cell carcinoma in the lung, in which the use of antiprogrammed death 1 (PD-1)immunotherapy resulted in substantial tumor reduction. In the present study, we describe an additional clinical course. A 69-year-old woman was diagnosed with giant cell carcinoma of the lung in clinical stage IVB (T2bN0M1c, BRA). The tumorexpressed programmed death ligand 1 (PD-L1) in a high proportion. The patient received stereotactic radiotherapy for two sitesof small brain metastases, followed by immunotherapy using anti-PD-1 antibodies (pembrolizumab). The treatment exerted asubstantial tumor reduction through four cycles. However, treatment was withdrawn due to renal dysfunction. The primarylung tumor continued to regress for an additional four months without any further therapy, resulting in a clinical stage ofT1aN0M0. Salvage thoracic surgery was then performed to remove the tumor residue in the lung. Microscopic examination ofthe sample revealed no residual cancer. The patient was free from recurrence at 16 months post surgery. We thencomprehensively reviewed lung sarcomatoid carcinoma cases in the literature, in which anti-PD-1 antibodies were implemented.The current literature and our ownfindings suggest sarcomatoid carcinomas express high levels of tumoral PD-L1 and can beeffectively treated with anti-PD-1 antibodies.