Serious Infections in Patients Receiving Ibrutinib for Treatment of Lymphoid Malignancies.

Background: Ibrutinib is a Bruton's tyrosine kinase inhibitor that is used for the treatment of lymphoid malignancies, including chronic lymphocytic leukemia (CLL), Waldenström's macroglobulinemia and mantle cell lymphoma (MCL). Several case series have described opportunistic infections among ibrutinib recipients, but the full extent of these infections is unknown. We sought to determine the spectrum of serious infections associated with ibrutinib treatment.

Methods: We reviewed the electronic medical records of patients with lymphoid malignancies at Memorial Sloan Kettering Cancer Center who received ibrutinib during a five-year period from January 1, 2012 to December 31, 2016. Serious infections were identified by review of the relevant microbiology, clinical laboratory, and radiology data. Risk factors for infection were determined by univariate and multivariate analyses.

Results: 378 patients with lymphoid malignancies who received ibrutinib were analyzed. The most common underlying malignancies were CLL and MCL. 84% of patients received ibrutinib as monotherapy. Serious infection developed in 43 patients (11.4%), primarily during the first year of ibrutinib treatment. Of these, 23 (53.5%) developed invasive bacterial infections, and 16 (37.2%) developed invasive fungal infections (IFI). The majority of those who developed IFI on ibrutinib therapy (62.5%) lacked classical clinical risk factors for fungal infection (i.e., neutropenia, lymphopenia, and receipt of corticosteroids). Infection resulted in death in six of the 43 patients (14%).

Conclusions: Patients with lymphoid malignancies receiving ibrutinib treatment are at risk for serious infections, including IFI.