Association of co-administration of a vaccine with immune checkpoint inhibitors with survival.

Abstract

11151 Background: Patients undergoing chemotherapy are less likely to complete recommended routine vaccination. Vaccination during immune checkpoint inhibitor (ICI) therapy elicits a significant cytokine response, which could enhance antitumor effects. This study investigates whether co-administration of vaccination with ICI improves cancer patient survival. Methods: Using the California Immunization Registry and Scripps Health’s electronic medical record, we validated vaccination status for patients at a large healthcare system in San Diego and conducted an observational cohort study of all ICI recipients from January 1, 2018, to June 1, 2024. Overall Kaplan-Meier survival curves were compared between patients who received vaccination within 100 days of ICI initiation and those who did not using log rank test. Subgroup analyses focused on patients with stage IV non-small cell lung cancer (NSCLC) and stage IV melanoma. The ICI cohort was propensity matched 1:1 by demographics to non-cancer patients to evaluate immunization rates. Results: 1,854 ICI-treated patients and 1,854 matched patients without cancer were identified for analysis. Vaccination within 100 days of ICI initiation was associated with improved overall survival (HR: 0.43, 95% CI: 0.37 – 0.49, p <.0001). Among NSCLC patients ( n =241), overall survival improved when any vaccination was administered within 100 days of ICI initiation (HR 0.37, p <.0001), with benefits observed specifically for COVID-19 (HR: 0.43, p <.0001) and influenza (HR: 0.38, p <.0001) vaccinations. Similarly, melanoma patients ( n =216) demonstrated improved overall survival with COVID-19 (HR: 0.53, p =.0214) and influenza (HR: 0.59, p =.0468) vaccinations. Findings remained robust upon censoring deceased unvaccinated patients within 100 days of ICI initiation to mitigate guarantee-time bias. No significant differences were observed in demographics, BMI, smoking status, medical comorbidities, PD-L1 expression (for NSCLC), or LDH levels (for melanoma) between patients who had received a vaccine within 100 days of ICI initiation and those that did not, that would otherwise explain this difference in mortality. There was no difference between the vaccinated and unvaccinated groups in terms of vaccination-related infection mortality. Active ICI patients were more likely to receive routine vaccinations than non-cancer patients (Influenza 2023 OR: 1.51, p= .0016), though vaccination rates have declined since their 2020 peak (Influenza vaccination rate: 2020, 71%; 2023, 59%). Conclusions: Co-administration of vaccination with ICI therapy improves survival, independent of infection-related outcomes. The associated cytokine response from vaccination during ICI therapy may enhance antitumor effects. Vaccination rates among ICI-treated patients have declined since 2020, highlighting the need for interventions to improve uptake and outcomes.