Immune checkpoint inhibitors are currently employed for the treatment of various malignancies, including advanced melanoma and non-small cell lung cancer. As more patients are treated with checkpoint inhibitors, situations will arise in which early-stage disease may be subjected, intentionally or unintentionally, to these agents. This is especially relevant for patients presenting with multiple primary malignant tumors (MPMTs). Here we report the case of a patient presenting synchronously with metastatic melanoma to multiple regional lymph nodes and stage I lung adenocarcinoma with high Programmed-Death Ligand 1 (PD-L1) expression. Given the high-risk nature of his melanoma, he was treated with nivolumab monotherapy, and had a durable response of both malignancies to a PD-1 inhibitor. He remains disease-free, off therapy sixteen months after completing a 19-month course of treatment. This highlights the complexity of treating patients with MPMTs in the era of effective immunotherapy and raises the possibility of treating primary lung cancer with systemic immunotherapy in situations in which surgery is not feasible due to comorbidities or other circumstances.
Keywords: Immune checkpoint inhibitor; Lung cancer; Malignant tumor; Melanoma; Primary lesion; Therapy.