Infectious complications of immune checkpoint inhibitors in solid organ malignancies

Immune checkpoint inhibitors (ICIs) are targeted cancer therapies regarded to have less toxicity than chemotherapy. Immune-related adverse events (irAEs) of ICIs are well described in the literature but limited data exist on their infectious complications. The objective is to describe the spectrum and risk factors for developing serious infections in patients receiving ICIs.

Retrospective review of patients with melanoma, renal cell carcinoma, or nonsmall-cell lung cancer on nivolumab, pembrolizumab, and/or ipilimumab from January 1, 2017 to November 30, 2017. Exclusion: receipt of less than two ICI doses or history of other malignancy. Characteristics: age, sex, prior chemotherapy, steroid use, and temozolomide or infliximab use. Data identified from microbiology, radiography, serology, or physician note documentation. Serious infection is defined as infections requiring hospitalization and/or IV antibiotics from initiation of ICI until the end of the study period.

One hundred and eleven pts received ICIs. Suspected or confirmed bacterial infections occurred in 24% (27/111) with 8% (9/111) confirmed bacterial cultures. The overall serious infection rate was 14% (16/111) with 25% (4/16) confirmed bacterial cultures. Suspected or confirmed infection sites: genitourinary 20% (22/111), pneumonia 5% (7/111), skin/soft tissue 7% (8/111). Noninfectious pneumonitis (NIP) occurred in 5% (5/111). No association regarding the risk of infection between the type of malignancy and ICI used. Steroid use was the only risk factor significantly associated with serious infection: 12/16 (75%) on steroids versus 27/95 (28.4%) without steroid use (p = 0.0003).

The rate of serious infection with ICI was higher in our study compared with previous reports of pts treated with melanoma. Infectious complications are encountered with ICIs and correlate with steroid use.