Early mortality in patients with cancer treated with immune checkpoint inhibitors in routine practice.

Background: We sought to estimate the proportion of patients with cancer treated with immune checkpoint inhibitors (ICI) who die soon after starting ICI in the real world and examine factors associated with early mortality (EM).

Methods: We conducted a retrospective cohort study using linked health administrative data from Ontario, Canada. EM was defined as death from any cause within 60 days of ICI initiation. Patients with melanoma, lung, bladder, head and neck, or kidney cancer treated with ICI between 2012 and 2020 were included.

Results: A total of 7126 patients treated with ICI were evaluated. Fifteen percent (1075 of 7126) died within 60 days of initiating ICI. The highest mortality was observed in patients with bladder and head and neck tumors (approximately 21% each). In multivariable analysis, previous hospital admission or emergency department visit, prior chemotherapy or radiation therapy, stage 4 disease at diagnosis, lower hemoglobin, higher white blood cell count, and higher symptom burden were associated with higher risk of EM. Conversely, patients with lung and kidney cancer (compared with melanoma), lower neutrophil to lymphocytes ratio, and with higher body mass index were less likely to die within 60 days post ICI initiation. In a sensitivity analysis, 30-day and 90-day mortality were 7% (519 of 7126) and 22% (1582 of 7126), respectively, with comparable clinical factors associated with EM identified.

Conclusions: EM is common among patients treated with ICI in the real-world setting and is associated with several patient and tumor characteristics. Development of a validated tool to predict EM may facilitate better patient selection for treatment with ICI in routine practice.