The anticancer drug ibrutinib does not appear to inhibit response to the flu vaccine in patients with chronic lymphocytic leukemia (CLL), despite an impaired immune system, according to a new study. Researchers gave influenza vaccine to a small group of CLL patients participating in a clinical trial of ibrutinib. More than one-quarter of the patients showed evidence of a positive response to the flu vaccine three months after receiving it. The findings lend support to routine immunization against the flu in patients with CLL, the researchers said. The study, published in JAMA Oncology, was funded by NHLBI.