Research Summary

Influenza Vaccination Linked to Longer Progression-Free Survival in Metastatic Cancer Patients During Checkpoint Therapy

Edited by:
Brian McCurdy

Key Highlights

  • Vaccinated patients had longer real-world progression-free survival than unvaccinated patients (HR, 0.59; 95% CI, 0.44–0.79).
  • Any-grade immune-related adverse events occurred in 48.4% of vaccinated patients versus 51.2% of unvaccinated patients.
  • The survival association was more pronounced in cutaneous malignant melanoma; no statistically significant effect was observed in non–small cell lung cancer.
  • The authors characterized the melanoma finding as hypothesis-generating and supported current vaccination recommendations.

Influenza vaccination during immune checkpoint inhibitor treatment was associated with longer real-world progression-free survival in patients with metastatic cancer in a multicenter Swedish study published in JCO Oncology Practice. Investigators found no statistically significant differences in any-grade or multiple immune-related adverse events (IRAEs) between vaccinated and unvaccinated patients.

The investigators examined whether vaccination during checkpoint inhibitor therapy was associated with treatment effectiveness or immune-related toxicity. Their rationale reflected 2 clinical concerns: checkpoint inhibitors can cause IRAEs through immune overactivation, while influenza can be more severe in patients with cancer because of compromised immune function.

The retrospective cohort included patients treated at 3 Swedish centers between January 1, 2016, and December 31, 2021. Eligible patients had metastatic cancer and received PD-1/PD-L1 inhibitors or combination immunotherapy. Researchers compared outcomes according to influenza vaccination status during treatment.

Study Findings

The cohort comprised 587 patients. Non–small cell lung cancer (NSCLC) was the most common malignancy, accounting for 34.4% of patients, followed by cutaneous malignant melanoma (CMM), at 32.5%. In the overall cohort, time-dependent Cox regression showed significantly longer real-world progression-free survival among influenza-vaccinated patients than among unvaccinated patients (hazard ratio, 0.59; 95% CI, 0.44–0.79).

Any-grade IRAEs occurred in 48.4% of vaccinated patients and 51.2% of unvaccinated patients (P = .455). Multiple IRAEs occurred in 15.1% and 19.2%, respectively (P = .297). Neither difference was statistically significant. The survival association was more pronounced among patients with CMM, whereas no statistically significant effect was observed among those with NSCLC. The abstract did not provide subgroup hazard ratios or confidence intervals.

Clinical Implications

According to the authors, the findings suggest a potential association between influenza vaccination and improved survival during checkpoint inhibitor treatment without a corresponding increase in IRAEs. They interpreted these results as supporting current vaccination recommendations. They also suggested that the melanoma association may reflect underlying biological mechanisms, while emphasizing its hypothesis-generating nature.

Expert Commentary

“The observed association in patients with CMM may reflect underlying biological mechanisms and is hypothesis-generating for further investigation,” the researchers concluded.

Reference

Koliadi A, Digkas E, El-Naggar AI, Ullenhag G, Valachis A. Influenza vaccination among patients with cancer treated with checkpoint inhibitors: association with survival outcomes and immune-related adverse events. JCO Oncol Pract. 2026;22(10):1805-1811. doi:10.1200/OP-25-00660