Background: Immune checkpoint inhibitor (ICI) therapy has significantly improved outcomes across a range of malignancies. While infections are a well-known contributor to morbidity and mortality amongst patients receiving systemic chemotherapy regimens, little is known about the impact of infections on patients receiving ICI therapy. This study aims to assess incidence, risk factors, and outcomes in patients who develop infections while on pembrolizumab-based therapies for non-small cell lung cancer (NSCLC). Methods: Patients receiving pembrolizumab for stage III/IV NSCLC from 1/1/2017-8/1/2021 across seven hospitals were identified. Incidence and type of infection were characterized. Covariates including baseline demographics, treatment information, treatment toxicities, and immunosuppressive use were collected and compared between infected and non-infected patients. Outcomes included the rate of infections, all-cause hospital admissions, median number of treatment cycles, overall survival (OS), and progression free survival (PFS). Univariable and multivariable analysis with reported odds ratio (OR) and 95% confidence intervals (CI) were utilized to evaluate infection risks. OS and PFS were analyzed by Kaplan–Meier analysis and tested by log-rank test. p-value < 0.05 was considered statistically significant. Results: There were 243 NSCLC patients that met the inclusion criteria. Of these, 111 (45.7%) had one documented infection, and 36 (14.8%) had two or more. Compared to non-infected patients, infected patients had significantly more all-cause Emergency Department (ED) [37 (33.3%) vs. 26 (19.7%), p = 0.016], hospital [87 (78.4%) vs. 53 (40.1%), p < 0.001], and ICU visits [26 (23.4%) vs. 5 (3.8%), p < 0.001], and had poorer median OS (11.53 [95% CI 6.4–16.7] vs. 21.03 [95% CI: 14.7–24.2] months, p = 0.033). On multivariable analysis, anti-infective therapy (OR 3.32, [95% CI: 1.26–8.76], p = 0.015) and ECOG of >1 (OR 5.79, [95% CI 1.72–19.47], p = 0.005) at ICI initiation conferred an increased risk for infections. At last evaluation, 74 (66.7%) infected and 70 (53.0%) non-infected patients died (p = 0.041). Conclusion: Infections occurred in nearly half of patients receiving pembrolizumab-based therapies for NSCLC. Infected patients had frequent hospitalizations, treatment delays, and poorer survival. ECOG status and anti-infective use at ICI initiation conferred a higher infection risk. Infection prevention and control strategies are needed to ameliorate the risk for infections in patients receiving ICIs.

4573 Background: Over the past decade, studies have shown the benefit of immune checkpoint inhibitors (IO) in patients with advanced urothelial cancer. These agents work by reconditioning the adaptive anti-cancer immune response within the tumor microenvironment. Immune-related adverse events have been well documented, but there is limited data evaluating infections in patients treated with IO. We performed a retrospective analysis to assess the incidence of infection and its effect on morbidity and mortality in patients treated with pembrolizumab for advanced urothelial cancer. Methods: Data was collected from a network of 7 hospitals for patients who received pembrolizumab for advanced urothelial cancer from 1/1/2017-8/1/2021. Date of last follow up was 12/1/2021. Covariates compared among infected and non-infected cohorts included age, gender, race, comorbidities, ECOG, anti-infective therapy at IO initiation, and line of therapy (1L, 2L, > 2L). Univariable analysis with reported odds ratio (OR) and 95% confidence interval (CI) was used to assess risk factors for infection. Outcome measures included all-cause emergency department (ED) visits, inpatient and intensive care unit (ICU) admissions, median number of IO cycles, and overall survival (OS). OS was evaluated using the Kaplan-Meier model. All analyses were deemed statistically significant if the p-value was < 0.05. Results: A total of 51 patients were identified. Of these, 34 (66.7%) had at least one documented infection and 17 (33.3%) had no reported infections. Baseline characteristics were similar across cohorts. Compared to non-infected patients, infected patients received fewer cycles of IO (median 4 vs 8, p = 0.016). At last follow-up, 20 (58.8%) patients in the infected cohort and 4 (23.5%) in the non-infected cohort died (p = 0.017). Median OS was 7.4 months (95% CI: 3.4-24.9) among patients with infection while not reached in those without infection (p = 0.014). ED visits (p = 1.00), inpatient admissions (p = 0.21), and ICU admissions (p = 0.17) did not significantly differ between cohorts. Univariable analysis did not identify significant risks among covariates. Conclusions: The incidence of infection in patients treated with pembrolizumab for advanced urothelial cancer is high and associated with fewer cycles of IO therapy and shorter OS. Further study of infectious process prevention is of value to maximize immunotherapy benefit.

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