Diagnosis and management of concurrent metastatic melanoma and chronic myelomonocytic leukemia

While the association between chronic lymphocytic leukemia (CLL) and a higher incidence of melanoma is well documented, the diagnosis of concurrent high-risk chronic myelomonocytic leukemia (CMML) and metastatic melanoma (MM) has not previously been described. Moreover, the treatment of MM and CMML differ greatly in the mechanism of action of their corresponding antineoplastic therapies: treatment of MM frequently involves immune checkpoint inhibitors (ICI), while patients with CMML receive myelosuppressive agents. Simultaneous management of these malignancies can be nuanced due to the potential impact of one treatment's constituents on the activity of the other and the broad and nonoverlapping array of potential adverse effects of these agents. Here, we describe the clinical course of a patient who was diagnosed with concurrent MM and CMML and our approach to the challenging balance of delivering ICI concurrently with the hypomethylating agent azacitidine and the BCL-2 inhibitor venetoclax.