Two primary cancers appeared after discontinuation of nivolumab in the course of treating Hodgkin lymphoma: a case report.

Background: Nivolumab is a human monoclonal antibody against programmed death-1 (PD-1) that blocks interactions of PD-1 with both PD-L1 and PD-L2 and upregulates tumor antigen-specific T cell to develop appropriate immune response against cancer cells. It has been approved by the US Food and Drug Administration (FDA) in the treatment of various malignancies including Hodgkin lymphoma (HL). Case Description: Our patient is a 75-year-old man diagnosed with nodular sclerosis HL. After relapse of disease on several lines of treatment including autologous stem cell transplant, Nivolumab was started as part of a clinical trial. Partial response (PR) was noted on nivolumab for a few years which was eventually discontinued due to disease progression. A few weeks later, the patient was noted to have a suspicious lesion on the right earlobe and another on the base of the tongue, which were pathologically diagnosed as Merkel cell carcinoma (MCC) and oropharyngeal squamous cell carcinoma (SCC), respectively. Conclusions: Immune checkpoint inhibitors (ICIs) like nivolumab have demonstrated anti-tumor efficacy in several cancers to date. We describe here a unique observation of nivolumab suppressing the growth of two separate malignancies apart from the primary malignancy, discontinuation of which has then contributed to their growth and subsequent diagnosis. Our case report showcases the broad activity of ICIs and brings attention to the possibility of uncovering new malignancies after discontinuation of ICIs in high-risk patients.