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February 11, 2026

Influenza Vaccination Among Patients With Cancer Treated With Checkpoint Inhibitors: Association With Survival Outcomes and Immune-Related Adverse Events

Key Points

To determine if influenza vaccination affects survival outcomes and immune-related adverse events in cancer patients on checkpoint inhibitors.
Retrospective cohort study across three Swedish cancer centers
Included patients with metastatic cancer treated with PD-1/PD-L1 inhibitors or combination immunotherapy
Used time-dependent Cox regression and landmark analyses to address immortal time bias
Influenza-vaccinated patients showed a 41% reduction in hazard of progression-free survival (HR, 0.59) compared to unvaccinated patients
No significant difference in overall occurrence of immune-related adverse events (48.4% vs 51.2%)
Survival benefit was more pronounced in patients with cutaneous malignant melanoma compared to non-small cell lung cancer

Abstract

PURPOSE Patients with cancer receiving immune checkpoint inhibitors (CPIs) may experience immune-related adverse events (IRAEs) due to immune system overactivation. Concurrently, infections such as seasonal influenza can be more severe in cancer patients because of their compromised immune function, making influenza vaccination particularly important. In this multicenter retrospective study, we investigated whether influenza vaccination during CPI treatment influences CPI effectiveness and rates of IRAEs. PATIENTS AND METHODS We conducted a retrospective cohort study across three Swedish centers involving patients with metastatic cancer treated with CPIs—either PD-1/PD-L1 inhibitors or combination immunotherapy—between January 1, 2016, and December 31, 2021. To address immortal time bias in time-to-event outcomes, different statistical strategies were employed including time-dependent Cox regression and landmark analyses. RESULTS In total, 587 patients treated with CPIs during the study period were identified. The most common malignancy was non–small cell lung cancer (NSCLC; 34.4%), followed by cutaneous malignant melanoma (CMM; 32.5%). Time-dependent Cox regression analysis showed that real-world progression-free survival was significantly longer in influenza-vaccinated patients compared with unvaccinated in overall cohort (hazard ratio HR, 0.59 95% CI, 0.44 to 0.79). No statistically significant differences in the occurrence of any grade IRAEs (48.4% v 51.2%, P = .455) or multiple IRAEs (15.1% v 19.2%, P = .297) between the vaccinated and unvaccinated groups were observed. The survival benefit was more pronounced in patients with CMM, whereas no statistically significant effect was observed in patients with NSCLC. CONCLUSION Our findings suggest a potential association between influenza vaccination and improved survival in CPI-treated patients, without a corresponding increase in IRAEs, supporting current vaccination recommendations. The observed association in patients with CMM may reflect underlying biological mechanisms and is hypothesis-generating for further investigation.

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Cite This Study

Koliadi et al. (Mon,) studied this question.

synapsesocial.com/papers/698c1cd3267fb587c655f90e https://doi.org/https://doi.org/10.1200/op-25-00660

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