Cytomegalovirus infection among patients with cancer receiving immune checkpoint inhibitors

Background Immune checkpoint inhibitors (ICIs), used for the treatment of solid and hematologic malignancies, come with the risk of immune-related adverse events (irAEs). Opportunistic infections (e.g., cytomegalovirus [CMV]) mimic irAE symptoms and are understudied in this population. We aimed to describe the incidence, characteristics, treatment and outcomes of CMV infection in ICI-treated patients. Methods We conducted a single-center retrospective review of all adult patients who were CMV-positive after ICI therapy between 06/2011 and 05/2020. A CMV-positive non-ICI cohort was matched to the ICI group based on age, sex and cancer type. Variables of interest were collected through electronic medical records. Results The study population comprised 192 patients overall. CMV infection incidence was 7.7% in ICI patients and 12.9% in non-ICI patients (P<0.001). Rates of infection clearance (83% vs. 50%, P=0.002) and recurrence (20% vs. 3%, P=0.037) were higher in ICI patients with hematologic vs. solid tumors, despite similar treatments. All-cause mortality was higher in solid rather than hematologic malignancies in ICI patients (83% vs. 54%, P=0.009); CMV-related mortality was low (3-4%) in both groups. Conclusions CMV infection occurred in about 7.7% of the ICI-treated cancer population. The infection can be disseminated in multiple organs and has a wide spectrum of clinical symptoms. ICI-treated patients with a hematologic malignancy had higher viral clearance and recurrence than those with solid tumors. In this study, CMV itself did not lead to high mortality in cancer patients. Further study is needed to investigate the role of CMV infection in patients’ irAEs and cancer outcome.