Cancer patients often present a dilemma for pharmacists and other vaccinators when it comes to influenza prevention. On the one hand, they are at higher risk for developing flu-related complications. On the other hand are concerns that the vaccine could exacerbate immune events in patients treated with certain therapies, such as immune checkpoint inhibitors (ICIs).

To try to resolve those issues, a study team including researchers from Columbia University and Memorial Sloan-Kettering conducted a retrospective review of advanced cancer patients taking ICIs who received the flu vaccine during three consecutive seasons: 2014-2015, 2015-2016, and 2016-2017.

The study published in Clinical Infectious Disease notes that the primary outcome assessed was any new-onset immune-related adverse event (IRAE). The researchers also included a subset analysis of vaccinated patients newly treated with antiprogrammed cell death protein 1 (PD-1) agents, nivolumab or pembrolizumab, to assess overall IRAE rates for comparison with published clinical trials.

Over the three seasons, 370 patients met criteria for ICI and vaccination within approximately 2 months (65 days). The largest group of participants (46%) had lung cancer, followed by melanoma (19%).

Most of the participants received an anti–PD-1 agent only, although in the entire cohort 20% experienced an IRAE (any grade), with incidence of grade 3/4 toxicity at 8%. No grade 5 events occurred.

At the same time, in the subset of 170 patients newly treated with anti–PD-1 agents, the overall IRAE rate was 18%, with grade 3/4 events occurring in 7.6%. Influenza was diagnosed in two patients, the study notes.

Based on the results, the study authors encourage seasonal flu vaccination in patients treated with ICIs, adding, “No increase in incidence or severity of IRAE was detected in patients on ICIs who received the inactivated influenza vaccine within ~ 2 months of ICI. For newly treated patients on anti–PDI agents, IRAE rates were comparable to published clinical trials and did not vary with order of administration.”

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