Impact of the influenza vaccination on cancer patients undergoing therapy with immune checkpoint inhibitors (ICI).

3053 Background: Immune checkpoint inhibitors (ICI) are standard of care for many cancer patients (pts). There have been conflicting reports on the effect of the influenza (flu) vaccines (flu-V) on pts being treated with ICI, and some suggest that flu-V may impact survival outcomes in ICI treated pts. Methods: We conducted a retrospective review of patients at Vanderbilt Ingram Cancer Center treated with ICI from 2010-2017. Data collected included age, gender, race, cancer type, comorbidities, type of ICI (single v. combo), time of drug administration, time of flu-V, rate of flu prodromal, rate of admissions for flu related complications, rate of immune related adverse events (irAE) and admissions, and the impact of flu-V on PFS and OS. Statistical analysis was performed using Graph PAD prism and SPSS. Results: 534 patients were included, 72.1% received flu vaccine. Median age was 54, 76% male, 64.1% stage IV. Cancer types included were lung (37%), melanoma (34%), GU (18%), breast 7.2%, and lymphoma (3.4%). 93% received single agent ICI. Vaccinated and unvaccinated pts (37.4 v. 42.6, p = 0.067) developed equal rates of irAEs. Unvaccinated pts who developed irAEs were more likely to develop pneumonitis (37.23 v. 17.17, p = 0.023) and more likely to be admitted than vaccinated pts (41.53% v. 23.2% p = 0.016). Unvaccinated pts were less likely to experience flu prodrome (32.2 % v 43.7%, p = 0.067), but were more likely to be admitted for influenza related complications (62.4% 23.2 %, p = 0.032). Most common reason for admission was sepsis. Flu-V did not change PFS (vaccinated 47.2 m vs. unvaccinated 43.2 m, p = 0.0621) but improved OS (vaccinated 72 months v. 62 months unvaccinated, p < 0.001). In multivariate analysis, age and abstaining from flu-V were predictive for developing irAEs. Type and stage of malignancy, # of prior lines of therapy, type of ICI, and timing of flu-V was not predictive for developing for irAE. Conclusions: Our results suggest that seasonal flu vaccination is safe and beneficial for patients on ICI and reduces the rate of hospital admissions from flu related and irAEs. Furthermore, our study also demonstrates that vaccination with influenza may improve OS in patients receiving ICI.