Real-world use of BTK inhibitors for chronic lymphocytic leukemia in Japan: A retrospective observational database study.

Little is known about real-world treatment practices for chronic lymphocytic leukemia (CLL) in Japan. We aimed to assess the time to discontinuation/dose reduction of Bruton tyrosine kinase inhibitors (BTKis) in patients with CLL in a real-world clinical setting in Japan. This was a retrospective observational database study using data from the Medical Data Vision database (from 1 May 2016 to 30 September 2021). Among the 483 patients with CLL who were treated with BTKis, 182 (37.7%) started treatment with a reduced dose of BTKi (lower than the standard dose), 302 (62.5%) experienced at least one dose reduction during the study period, and 123 (25.5%) discontinued BTKi treatment early (for any reason) during the study period. The median time to BTKi discontinuation was 52.3 weeks in 286 patients who started treatment with a standard dose and 57.1 weeks in 182 patients who started treatment with a reduced dose. The use of prophylaxis with anti-infectives was similar during treatment with BTKis and non-BTKis. There was no major difference in the incidence rate of cardiovascular-related adverse events during treatment with BTKis and non-BTKis. This study provides valuable information for future research on the treatment of CLL patients in Japan.