Immune checkpoint inhibitor toxicity in the clinical practice setting.

e14128 Background: Immune checkpoint inhibitors (ICIs) are changing the landscape of treatment in oncology. The use of ICIs is growing rapidly as the indications for these medications broaden and new ICIs become approved. Given the rapid growth and relative infancy of the use of ICIs, much information stands to be gained on their use in the clinical practice setting, especially regarding toxicity. Methods: The primary objective of this project was to examine the incidence and severity of immune-related adverse events (irAEs), after treatment with single-agent or combination ICIs at a multi-site community cancer center. A retrospective chart review was conducted on all patients who had received ipilimumab, nivolumab, pembrolizumab, atezolizumab, or ipilimumab plus nivolumab from May 1, 2011 to June 30, 2017. Data collected included patient demographics, disease state, treatment information, preexisting autoimmune disease, previous immunotherapy, and adverse event details. The results were analyzed using descriptive statistics. Results: Data was collected on 383 patients. Dermatologic irAEs were common across single agent ICIs (overall incidence 23%). Diarrhea and/or colitis incidence was highest with CTLA-4 inhibitor ipilimumab (26% at 3 mg/kg and 22% at 10 mg/kg) versus the other monotherapy PD-1/PDL-1 inhibitors. Endocrinopathies were most common with ipilimumab 10 mg/kg (55%) and pneumonitis incidence was highest with nivolumab (6%). ICI toxicity occurred in 63% of patients with preexisting autoimmune disease versus 54% of those without a baseline autoimmune disease. Incidence of hospitalization and treatment holds due to irAEs was higher with combination therapy (57% and 66%, respectively) than with monotherapy (10% and 24%, respectively). Conclusions: Overall, there was increased incidence in ICI toxicity in patients at this oncology institution versus what has been reported in clinical trials. Patients with preexisting autoimmune diseases appeared to have mainly low-grade toxicities with slightly increased incidence of irAE compared with those without pre-existing autoimmune disease. Treatment holds and hospitalizations were higher in patients treated with combination therapy ICIs compared to monotherapy ICIs.