Impact of Adherence to Ibrutinib on Clinical Outcomes in Real-World Patients With Chronic Lymphocytic Leukemia

• Published in: Journal of the advanced practitioner in oncology Vol. 12; no. 1; pp. 20 - 28
• Main Authors: M. Garner, PharmD, BCPPS, Lauren, Kline, PharmD, BCPS, BCCP, Theresa, Miller, PharmD, BCOP, CPP, Jordan, Deal, MS, Allison, Zhu, MS, PhD(c), Anqi, R. Sketch, PharmD, MPH, Margaret, C. Coombs, MD, Catherine, Muluneh, PharmD, BCOP, CPP, Benyam
• Format: Journal Article
• Language: English
• Published: United States Harborside Press LLC 01.01.2021
• Subjects: Research & Scholarship
• ISSN: 2150-0878; 2150-0886
• DOI: 10.6004/jadpro.2021.12.1.2

Background: Chronic lymphocytic leukemia (CLL) is a B-cell neoplasm with clonal expansion of small lymphocytes. Ibrutinib, an irreversible inhibitor of Bruton tyrosine kinase (BTK), is a first-line treatment option, and recent data suggest that strict adherence is directly related to clinical outcomes. Objectives: The primary objective of this study was to quantify ibrutinib adherence rates in real-world patients with CLL on ibrutinib; secondary outcomes included progression-free survival and overall survival. Methods: This retrospective study included subjects who were treated at a large academic medical center over approximately 5 years. Subjects were at least 18 years, diagnosed with CLL or small lymphocytic lymphoma, and treated with ibrutinib monotherapy for at least 6 months. Adherence was quantified using the medication possession ratio (MPR), which is the ratio of the sum of days’ supply of medication in a period over the number of days in that period, and was based on fill history from the medical center’s specialty pharmacy. Results: For the 32 subjects in this study, the mean ibrutinib adherence rate was 91.7% (range, 84.4%–100%). Only 3 subjects had disease progression, and 1 death was recorded while on therapy (all with MPR < 95%); therefore, analyses of clinical outcomes were unable to be assessed due to a low number of events. There were no statistically significant differences in rates of adherence based on baseline characteristics and adverse drug events. Conclusion: In patients with CLL treated with ibrutinib, mean adherence was 91.7%, which is lower than rates seen in clinical trials.