Safety of Inactivated Influenza Vaccine in Cancer Patients Receiving Immune Checkpoint Inhibitors

Area of Science:

• Oncology
• Immunology
• Vaccinology

Background:

• Cancer patients face increased risk of flu complications.
• The safety of flu vaccination in patients on immune checkpoint inhibitors (ICIs) is not well understood.
• Potential for flu vaccine to exacerbate immune events in patients on ICIs requires investigation.

Purpose of the Study:

• To assess the safety of the inactivated influenza vaccine in advanced cancer patients treated with ICIs.
• To determine if flu vaccination increases immune-related adverse events (IRAEs) in patients on ICIs.
• To compare IRAE rates in patients newly treated with anti-programmed cell death protein 1 (PD-1) agents and vaccinated with the flu vaccine against published clinical trial data.

Main Methods:

• Retrospective review of advanced cancer patients on ICIs who received the flu vaccine over three consecutive seasons (2014-2017).
• Primary outcome: incidence of new-onset immune-related adverse events (IRAEs).
• Subset analysis of patients newly treated with anti-PD-1 agents (nivolumab or pembrolizumab) to assess IRAE rates.

Main Results:

• 370 patients met criteria for ICI and flu vaccination within approximately 2 months.
• 20% of the entire cohort experienced any grade IRAE, with 8% experiencing grade 3 or 4 toxicity.
• In a subset of 170 patients newly treated with anti-PD-1 agents, IRAE rates were 18% overall and 7.6% for grade 3/4 events, comparable to published data.

Conclusions:

• Inactivated influenza vaccination is safe for patients on ICIs, with no increased incidence or severity of IRAEs observed.
• IRAE rates in newly treated anti-PD-1 patients were comparable to clinical trials, regardless of vaccination timing.
• Routine seasonal flu vaccination is recommended for patients undergoing treatment with ICIs.