The study evaluated real‑world clinical outcomes among Medicare Fee‑for‑Service beneficiaries aged 65 years or older with chronic lymphocytic leukemia or small lymphocytic lymphoma who initiated first‑line Bruton tyrosine kinase inhibitor monotherapy.

This retrospective cohort study used de‑identified Medicare Fee‑for‑Service claims data from January 1, 2020, through June 30, 2025. Eligible patients were adults aged ≥65 years with a diagnosis of chronic lymphocytic leukemia or small lymphocytic lymphoma who initiated first‑line Bruton tyrosine kinase inhibitor monotherapy and had at least 12 months of continuous enrollment before treatment initiation. The reported outcomes included real‑world overall survival, time to next treatment or death, and time to treatment discontinuation or death from the start of first‑line therapy.

A total of 10,523 patients were included in the analysis (zanubrutinib, n=3006; acalabrutinib, n=4309; ibrutinib, n=3208). The median age at first‑line therapy was 77 years for both zanubrutinib and acalabrutinib, and 76 years for ibrutinib. Median follow‑up was 16 months (range, 0–61) for zanubrutinib, 21 months (range, 0–69) for acalabrutinib, and 35 months (range, 0–69) for ibrutinib. Median overall survival was not reached for any treatment group. Median time to next treatment or death was not reached for zanubrutinib (95% CI, 45–NR), 40 months (95% CI, 38–42) for acalabrutinib, and 30 months (95% CI, 29–32) for ibrutinib. Median time to treatment discontinuation or death was not reached for zanubrutinib (NR–NR), 24 months (95% CI, 22–25) for acalabrutinib, and 14 months (95% CI, 13–15) for ibrutinib.