Real-world adherence and discontinuation among Medicare beneficiaries initiating venetoclax vs. BTKis in relapsed/refractory chronic lymphocytic leukemia.

The treatment landscape for chronic lymphocytic leukemia (CLL) has been transformed by the availability of Bruton's tyrosine kinase inhibitors (BTKis) and the B-cell lymphoma 2 (BCL-2) inhibitor venetoclax. Despite clinical trial data supporting these novel oral agents, evidence evaluating real-world adherence is limited. This study used 2015-2019 Medicare claims data for elderly patients with relapsed/refractory CLL to assess differences in real-world adherence and discontinuation in the 12 months after treatment initiation. In the final sample of 711 venetoclax patients and 1,566 BTKi patients, we found that those initiating venetoclax tended to be younger (mean age 75.6 [SD 6.0] vs 77.6 [SD 6.9] years,  < .001) but had poorer clinical characteristics. After risk-adjustment, the venetoclax group had higher adherence (61.9% vs. 45.4%, < .0001) and lower discontinuation when compared to the BTKi group (28.5% vs. 47.4%,  < .001). These favorable real-world findings underscore the importance of developing well-tolerated novel combinations for older adults.