Infectious complications among patients receiving ibrutinib for the treatment of hematological malignancies.

PURPOSE: Ibrutinib is a Bruton's tyrosine kinase inhibitor used to treat multiple hematologic malignancies and graft-versus-host disease. Though less myelosuppressive than cytotoxic chemotherapy, increased infections, including invasive fungal infections (IFIs), have been reported with ibrutinib use. This study aimed to determine the characteristics and risk factors for infection associated with ibrutinib at our institution. METHODS: Patients who received ibrutinib between June 2014 and August 2019 were included. Primary endpoints were the incidence of any infection and the incidence of serious infection (defined as hospitalization, parenteral antimicrobial therapy, or pneumonia regardless of hospitalization). Infection risk factors were assessed using logistic regression. RESULTS: One hundred thirty-two patients were identified (78% male; median age, 71 years). The most common indications for ibrutinib were chronic lymphocytic leukemia (67%) and mantle cell lymphoma (12%). Infection and serious infection occurred in 94 (71%) and 47 (36%) patients, respectively; when pneumonia was excluded as a criterion for serious infection, the serious infection rate was 27%. The median time from ibrutinib initiation to first infection was 125 days. Prior allogeneic hematopoietic stem cell transplantation (allo-HSCT) (odds ratio [OR], 4.60; 95% CI, 1.22-17.4) and corticosteroid use (OR, 5.55; 95% CI, 1.52-20.3) were significant risk factors for serious infection. IFIs were diagnosed in 7 patients (5%): 5 had Pneumocystis jirovecii pneumonia and 2 were infected with invasive molds. CONCLUSION: Serious infection and IFI rates are high but similar to those previously described. Risk factors for serious infection included allo-HSCT and corticosteroid use. Targeted antimicrobial prophylaxis should be evaluated in prospective studies in patients on ibrutinib to reduce serious infections and IFI.