Patients receiving amphotericin B (AmphoB), commonly used to fight systemic fungal infections, may be functionally immunocompromised and more vulnerable to influenza, according to the results of a murine study published in the Cell Press journal Cell Reports.

Investigators found AmphoB prevents interferon-induced transmembrane protein 3 (IFITM3), an antiviral protein in cells, from fending off the influenza A virus (IAV).

AmphoB-treated mice exposed to IAV became very ill and lost more than 25% of their body weight. According to researchers, the symptoms were similar to those seen in animals without the protective IFITM3 protein.

“Many critically ill cancer and bone marrow transplant patients are treated with Amphotericin B-based therapies each year,” said Abraham L. Brass, MD, PhD, of the University of Massachusetts Medical School (UMMS). “Given these results in cells and mice, it may be worthwhile to consider that patients receiving, or who may receive, Amphotericin B-based therapies be appropriately vaccinated against influenza virus.”

Brass continued: “Also, clinical consideration may be given to close monitoring of patients receiving Amphotericin B-based therapies for any symptoms suggestive of flu so that they might be considered for the early administration of an antiflu therapy.”

AmBisome is a first-line therapy for systemic fungal infections with an estimated $330 million in annual sales worldwide, according to researchers.