Real-world effectiveness and safety of ibrutinib in patients with chronic lymphocytic leukemia in Japan: the Orbit study.

Ibrutinib is a first-in-class Bruton's tyrosine kinase inhibitor that is approved for the treatment of chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) in Japan based on randomized clinical trial data. The aim of the real-world, retrospective Orbit study was to describe long-term clinical outcomes and management in adults (aged ≥ 20 years) with CLL/SLL treated with ibrutinib, either as first-line (1L) treatment or for relapsed or refractory (RR) disease, in routine clinical practice in Japan between July 2018 and December 2020. A total of 246 patients were registered, and the safety and per-protocol sets included 237 and 234 patients, respectively. After a median follow-up of 35.7 months, the 36-month progression-free survival rate was 80.9% in the 1L CLL cohort and 67.2% in the RR CLL cohort, and the 36-month overall survival rates were 90.8% and 83.7%, respectively. Common Terminology Criteria for Adverse Events (CTCAE) Grade ≥ 3 adverse events of special interest were atrial fibrillation (2.1%), infections (herpesvirus infection, fungal infection, or Pneumocystis jiroveci pneumonia; 1.7%), bleeding (3.8%), and second primary malignancy (2.5%). These findings confirm the long-term, real-world effectiveness and safety of ibrutinib for the treatment of Japanese patients with newly diagnosed or RR CLL/SLL.