Administration restrictions on oral mercaptopurine (6-MP) are unnecessary and may impair adherence among children with acute lymphoblastic leukemia (ALL), according to a study published in the Journal of Clinical Oncology.1
Maintenance therapy with 6-MP is standard of care for children with ALL, though previous studies showed low levels of patient adherence. Patients are typically directed to take 6-MP at night without food or dairy products. The purpose of this study was to determine if administration habits of 6-MP affect adherence and risk of relapse.
In this prospective, observational study, 441 children with ALL receiving maintenance therapy with 6-MP were evaluated for adherence, administration habits, and relapse. Adherence was monitored by the Medication Event Monitoring System, and administration habits were parent-reported by questionnaire at 4 study time points.
At study entry, the median age was 6 and 67% were male. The cohort consisted of 33.8% non-Hispanic whites, 35.8% Hispanics, 145.4% Asians, and 15% African Americans. All patients harbored the wild-type variant of TPMT.
The study found that 43.8% of children were non-adherent, defined as an adherence rate of less than 95%. Taking 6-MP with dairy (odds ratio [OR], 1.9; 95% CI, 1.3-2.9; P = .003) and at varying times (OR, 3.4; 95% CI, 1.8-6.3; P = .0001) was significantly associated with non-adherence.
6-MP administration habits — taken with food or dairy, taken at night or at varying times — were not associated with risk of relapse, after adjusting for adherence and other prognostic factors.
Red cell thioguanine nucleotide levels were not affected by administration habits among adherent children.
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The authors recommend that simpler administration may improve adherence. “Recommendations to take 6-MP in the evening in a fasting state — aimed at enhancing 6-MP absorption — may present barriers to adherence and are probably unnecessary,” the authors wrote.
- Landier W, Hageman L, Chen Y, et al. Mercaptopurine ingestion habits, red cell thioguanine nucleotide levels, and relapse risk in children with acute lymphoblastic leukemia: a report from the Children’s Oncology Group Study AALL03N1. J Clin Oncol. 2017 March 24. doi: 10.1200/JCO.2016.71.7579 [Epub ahead of print]