Adherence and persistence to second-generation tyrosine kinase inhibitors in patients with chronic myeloid leukemia.

Abstract

e17009 Background: Some studies have demonstrated the correlation between adherence and persistence to therapy and the effectiveness of that therapy, thereby reinforcing the need to optimize both as a core treatment strategy. Because available data are limited, we examined real world adherence and persistence to the 2nd generation tyrosine kinase inhibitors (TKIs) used to treat chronic myeloid leukemia (CML). Methods: An observational retrospective study was conducted using pooled Invision Data Mart and Pharmetrics claims data. Adult CML patients with at least two prescriptions for a 2nd generation TKI between July 1, 2006 and December 31, 2010 were identified and followed for a maximum of 6 months from their index date (first observed prescription date). Dasatinib and nilotinib patients with prior imatinib use in 6 month pre-index period were classified as second-line and those with no prior use as first-line patients. Adherence to treatment was defined by the medication possession ratio (MPR) and persistence as the proportion of patients refilling prescriptions within 1.5 times the days supply during the follow-up period. Results: Of the 276 CML patients identified, 179 received dasatinib (n=50 first-line; n=129 second-line) and 97 received nilotinib (n=27 first-line; n=70 second-line). Patient characteristics were similar across treatment groups. Proportions with MPR ≥85% were 64% and 75% for first- and second-line dasatinib and 48% and 61% for first- and second-line nilotinib. Persistence rates were 36% and 47% for first- and second-line dasatinib and 26% and 39% for first- and second-line nilotinib. Conclusions: In both first- and second-line use, dasatinib was associated with higher adherence and persistence than the corresponding nilotinib-treated group. The reason for the difference between these TKIs is not known and will require further study.