Certain mercaptopurine ingestion habits might not impact outcome but could hinder adherence in children with acute lymphoblastic leukemia (ALL), according to a study involving 441 individuals.

Participants—who ranged between 2 and 20 years of age—had ALL and were on maintenance oral mercaptopurine therapy. Investigators monitored adherence over more than 48,000 patient-days, looking at whether mercaptopurine was ingested with or without food; with or without dairy; and in the evening, morning, or varying times. Among the results:

• 44% of patients were nonadherent.
• Children who took mercaptopurine with dairy were nearly twice as likely to be nonadherent.
• Those who took it at varying times were more than 3 times as likely to be nonadherent.
• After adjusting for certain variables, there was no link between mercaptopurine ingestion habits and relapse risk.
• In adherent patients, there was no link between red cell thioguanine nucleotide levels and taking mercaptopurine regardless of when or how ingested.