A 54-year-old female patient diagnosed with Stage IIIb squamous cell carcinoma (cT2aN3M0) initially received chemoradiotherapy. Two years after initial treatment, cancer relapse led to the administration of nivolumab, which was halted due to the development of drug-induced pneumonitis. Subsequent management with prednisolone and eight different cytotoxic agents failed to prevent metastasis to the cervical lymph nodes. The tumor's programmed death-ligand 1 (PD-L1) expression rate was recorded at 10%. Four years after her diagnosis, the patient received a ninth-line therapy combining cisplatin, gemcitabine, and necitumumab, followed by palliative neck radiation due to increasing lymph node size. Remarkable tumor regression occurred three months after introducing atezolizumab as the tenth-line treatment, suggesting that previous treatments, particularly radiotherapy and cisplatin, might have enhanced PD-L1 expression, aligning with the existing literature. This case highlights the urgent need for further research to elucidate the intricate interplay between treatment history and PD-L1 expression in squamous cell carcinoma, emphasizing the importance of accumulating case studies to inform therapeutic strategies.
Keywords: atezolizumab; immune checkpoint inhibitor; lung cancer.