Impact of adherence to ibrutinib on clinical outcomes in real-world patients with chronic lymphocytic leukemia.

Ibrutinib is an oral Bruton's tyrosine kinase inhibitor approved for treatment of chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL). Clinical trial data suggest that strict adherence is directly related to clinical outcomes. This retrospective, multicenter study aimed to evaluate ibrutinib adherence and its impact on clinical outcomes in patients with CLL/SLL treated in the real-world setting. The primary outcome was to quantify ibrutinib adherence rates in the real-world setting using the proportion of days covered (PDC) calculation. Secondary outcomes included the association of ibrutinib adherence with progression-free survival (PFS) and overall survival (OS). For the 100 patients in the primary analysis, the mean PDC was 95% (range: 65-100%). Patients who maintained PDC > 95% for each of the first 6 months experienced fewer PFS events ( = 1) compared to those with PDC ≤ 95% ( = 5; =.03). The correlation between adherence and OS was not assessed due to a low number of events.