PD-1 inhibition in malignant melanoma and lack of clinical response in chronic lymphocytic leukemia in the same patients: a case series.

Chronic lymphocytic leukemia (cll) is the most common adult leukemia in the Western world. Unfortunately, affected patients are often immunosuppressed and at increased risk of infection and secondary malignancy. Previous meta-analysis has found that patients with cll have a risk of melanoma that is increased by a factor of 4 compared with the general population. Recent advances in the understanding of the PD receptor pathway have led to immunotherapies that target cancer cells. The use of PD-1 inhibitors is now considered first-line treatment for wild-type metastatic melanoma. Interestingly, early preclinical data suggest that inhibition of that pathway could also be used in the treatment of cll; however, recent clinical data did not support the effectiveness of that approach. In this case series, we highlight 2 cases in which patients with cll and concurrent malignant melanoma underwent treatment with PD-1 inhibitors and were found to experience reductions in their white blood cell counts without improvement in their hemoglobin. Those cases further illustrate that treatment of cll with PD-1 inhibitors is ineffective.