Monotherapy of PD-1 Inhibitor Camrelizumab Reverses Advanced Lung Squamous Cell Carcinoma with Low PD-1 Expression: A Case Report

Introduction: Chemotherapy plus immunotherapy is the standard treatment worldwide for advanced lung squamous cell carcinoma with high programmed cell death protein-1 (PD-1) expression. The use of immunotherapy alone against advanced lung squamous cell carcinoma is rarely reported, and data on PD-1 inhibitor camrelizumab are missing. We report the first case of camrelizumab monotherapy, which can be a reference for the clinical applications of camrelizumab in a wider context. Case Presentation: We herein present a 69-year-old male case of advanced squamous cell carcinoma with low PD-1 expression, in which camrelizumab monotherapy was administered every 3 weeks. Camrelizumab monotherapy reversed advanced lung squamous cell carcinoma without recurrence or obvious side effects during 26 months of follow-up. The patient is alive and in good conditions to date; thus, progression-free survival and overall survival are not determined. Conclusion: This case report provides evidence of the efficacy of camrelizumab monotherapy and highlights the feasibility of camrelizumab alone against advanced lung squamous cell carcinoma when chemotherapy is not applicable.