Mechanism of Acquired Resistance to Nivolumab in Lung Squamous Cell Carcinoma: Case Report and Review of the Literature

Background: Immune checkpoint inhibitors targeting PD-1 and PD-L1 have noticeably improved the treatment landscape of advanced non-small-cell lung cancer, including lung squamous cell carcinoma (SCC). Although patients with immune checkpoint therapy can achieve long-term survival, acquired resistance has been recognized more frequently, while the underlying mechanisms are currently poorly understood. Materials and methods: Here, we report a patient with metastatic lung SCC treated with nivolumab as a first-line treatment for 28 months. Conclusion: The analysis of specimens prenivolumab and postnivolumab treatment suggests that genetic alterations in SOX2 and CDKN2A/CDKN2B and changes in the tumor microenvironment could be reasons for the acquired resistance to nivolumab observed in the lung SCC patient.