TKI Persistence Rates at VHA Over Time

ELK GROVE, CA — How is chronic myeloid leukemia (CML) treated over an extended period at the VHA, including the use of tyrosine kinase inhibitor (TKI) therapy with imatinib, dasatinib and nilotinib?

A retrospective cohort study published in the journal Pharmacotherapy sought to answer that question.1

The study, led by California Northstate University researchers with participation from the South Texas Veterans Health Care System in San Antonio, involved 2,873 VHA beneficiaries aged 18-89 years who had at least one encounter at any of the about 150 VHA hospitals and 800 VHA clinics, had a diagnosis code for CML, and filled at least one prescription for imatinib, nilotinib or dasatinib between Oct. 1, 2001, and Sept. 30, 2010.

With primary study end points including change in TKI treatment, gaps in TKI treatment, TKI treatment persistence and patient survival, persistence for each line of treatment was defined as the time of continuous therapy, quantified by the number of days covered by the drug from treatment initiation until a 60-day gap in treatment was identified or a switch in treatment occurred.

Results indicated that, of the 2,873 patients receiving first-line TKI treatment, 586 (20.4%) switched to a different TKI, constituting second-line treatment. Overall, 245 patients (8.5%) were switched again to third-line treatment.

At the same time, only 4.4% of patients receiving first-line treatment experienced a gap in therapy of 60 or more days.

The study determined that first-line treatment persistence rates were 75%, 65% and 55% for the first, second and third years of treatment, respectively. The five-year survival with first-line treatment was calculated at 62%.

“In this national cohort of VHA patients, one-year persistence of first-line TKI treatment was similar to that in prior studies,” study authors concluded. “Five-year survival was comparable with that in other observational studies but was lower than that in prospective clinical trials. Persistence rates declined after the introduction of the new TKIs.”

  1. Kreys ED, Frei CR, Villarreal SM, Bollinger MJ, Jones X, Koeller JM. Evaluation of Long-Term Chronic Myeloid Leukemia Treatment Practices with Tyrosine Kinase Inhibitors in a National Cohort of Veterans. Pharmacotherapy. 2017 Mar;37(3):278-286. doi: 10.1002/phar.1893. Epub 2017 Feb 22. PubMed PMID: 28052354.

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