Pneumocystis Infection in Two Patients Treated with Both Immune Checkpoint Inhibitor and Corticoids

The introduction of immune checkpoint inhibitor (ICI) targeting cytotoxic T-lymphocyte-associated antigen-4 and programmed cell death receptor 1 has dramatically improved clinical outcome for cancer patients. Nevertheless, this treatment can be associated with immune-related adverse events (irAEs) which sometimes need management with prolonged immune suppression. In order to analyze the risk of Pneumocystis jiroveci pneumonia (PJP) in this population, all PJP cases at our oncological hospital between 2004 and 2019 were searched. Only two cases were found in patients treated with ICI (480 patients received ICI during that period). The first was treated with both ipilimumab and nivolumab for metastatic melanoma and required long-term corticosteroids plus infliximab for immune-related colitis. The second received both pembrolizumab and brentuximab for Hodgkin's lymphoma and received corticosteroids for macrophage-activating syndrome. These two cases illustrate that PJP is rare but might be severe in the ICI population and should be differentiated from tumor progression or irAE.