Dosing and Adherence in Patients Taking Tyrosine Kinase Inhibitors

San Diego—According to a cross-sectional survey of patients with chronic myeloid leukemia (CML) in the United States and Europe, patients who took nilotinib were significantly more likely to have difficulty adhering to their treatment regimen compared with patients who took dasatinib or imatinib. The results, presented at the ASH meeting in a poster session, indicated that the difference was attributed to nilotinib having more dietary and dosing restrictions than the other therapies. The poster was titled Associations Between Treatment Restrictions, Patient-Reported Treatment Burden and Adherence to Tyrosine-Kinase Inhibitor Therapy Among Chronic Myeloid Leukemia Patients in the United States and Europe. Each drug is an oral tyrosine kinase inhibitor indicated as first-line therapy for CML, but recommendations for the drugs vary. Patients receiving a prescription for dasatinib are advised to take one 100-mg tablet once daily with or without a meal in the morning or evening. Meanwhile, nilotinib is taken twice daily at 12-hour intervals with food, and the product has a boxed warning indicating patients should not eat at least 2 hours before and 1 hour after a dose. Patients taking imatinib are told to take either 400 or 600 mg once daily or 400 mg twice daily, and they are advised to eat a meal and drink a large glass of water while taking each dose. Between November 2010 and May 2011, the authors collected data via a self-administered, Internet-based survey from 303 patients ≥18 years of age who had chronic-phase CML and were taking 1 of the 3 drugs. They used the following 5 questionnaires: Medical Outcomes Study 12-item Short Form Survey Instrument, MD Anderson Symptom Inventory, Work Productivity and Activity Impairment, Cancer Treatment Satisfaction Questionnaire, and Patient Health Questionnaire-9. They also asked 52 supplemental questions related to treatment burden, satisfaction, and adherence. Of the people who completed the survey, 68.6% were taking imatinib, 12.5% were taking dasatinib, 16.2% were taking nilotinib, and 2.7% were taking another treatment or declined to answer. Mean age was 51.5 years, mean time since CML diagnosis was 4.8 years, and median time on current CML treatment was 2.75 years. More than half of the respondents were from the United States, and 46.2% of patients were males. According to the authors, the survey participants taking nilotinib were significantly more likely to report treatment restrictions compared with those taking dasatinib or imatinib. The restrictions included having to take the medication at specific time intervals, with certain foods, twice daily, or ≥2 pills at a time. The survey found that 42.9% of patients in the nilotinib group missed a dose compared with 21.6% of patients in the imatinib group (P<.01), while 14.3% and 4.3% of the patients, respectively, took fewer doses than prescribed (P<.01). In addition, 3.7% of patients in the dasatinib group reported they had trouble following their treatment regimen compared with 22.9% in the imatinib group (P=.021) and 63.3% of patients in the nilotinib group (P<.001). The authors also performed a multivariate analysis. They concluded higher overall CML treatment restriction scores were associated with more difficulty taking the medication as required (P<.001) and that nonadherence increased when the treatment difficulty increased (P<.003). However, they indicated there was no statistically significant association between CML treatment restrictions and self-reported nonadherence (P=.24). This study was funded by Bristol-Myers Squibb.