Complete Response to Programmed Death-1 and Cytotoxic T-lymphocyte Associated Protein 4 Inhibitors Combined with Chemotherapy in Pulmonary Sarcomatoid Carcinoma Despite Programmed Death Ligand-1 Tumor Proportion Score Negativity

Background. Pulmonary sarcomatoid carcinoma (PSC) is often indicated by increased expression of programmed death ligand-1 (PD-L1) and responds to immunotherapy. However, the effectiveness of immunotherapy in PSC cases with a low PD-L1 expression is uncertain. Case. We herein report a patient with stage IV PSC and PD-L1-negative expression who was treated with a combination of immunotherapy and chemotherapy. Treatment was discontinued after 1 cycle due to grade 3 hepatic toxicity, yet the patient achieved complete remission, which persisted for 35 months. Conclusion. This case highlights the role of combination immunotherapy in PSC treatment and suggests the significance of exploring alternative mechanisms to activate the immune system within the tumor microenvironment.