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

Abstract

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.

Real-World Comparison of First-Line Treatment Adherence Between Single-Agent Ibrutinib and Acalabrutinib in Patients with Chronic Lymphocytic Leukemia

“…One retrospective chart review study found that among patients treated at North Carolina Cancer Hospital for at least 6 months, the mean adherence rate measured by MPR was 91.7% (range: 84.4% to 100%). 32 A second follow-up study reported a mean PDC of 95% (range: 65–100%) among patients treated with ibrutinib for at least 6 months. 33 The mean PDC and MPR reported in the current study for patients treated with ibrutinib with at least 6 months of LOT duration were similarly high at 85% and may be more generalizable, as the data came from a larger cohort of 1374 patients treated with ibrutinib in 15 academic and 12 non-teaching hospital systems across 15 US states (compared to only 32–149 patients from one or two centers).…”

Impact of initiating oral anticancer agents for leukemia on adherence to medications for multiple chronic conditions

“…[6][7][8][9][10][11][12][13] The literature documenting adherence in patients with CLL is comparatively less robust, but the limited evidence available suggests that while adherence may be higher in this population, optimal medication use remains a pressing issue given its observed relationship with reaching progression-free survival. 14,15 Given the extension to life afforded patients prescribed and adhering to OAAs, medication nonadherence challenges are not limited solely to cancer management. Comorbid chronic disease is common among patients with either CML or CLL, and high comorbidity burden has been associated with poorer survival outcomes.…”

“…6–13 The literature documenting adherence in patients with CLL is comparatively less robust, but the limited evidence available suggests that while adherence may be higher in this population, optimal medication use remains a pressing issue given its observed relationship with reaching progression-free survival. 14,15…”