An estimated 25% of children in remission from acute lymphocytic leukemia (ALL) are missing too many doses of the oral agent mercaptopurine, a maintenance medication that minimizes their risk of relapse when taken every day for 2 years, according to a study recently published online in Blood.1 The study also reports that maintenance medication adherence was lower in African American and Asian children in remission from ALL than in non-Hispanic white children, with 46% of African Americans and 28% of Asians not taking enough to prevent relapse, compared with 14% of non-Hispanic whites.
“While we don’t yet know why children of different races have significantly different survival rates for ALL, we know that their adherence to their maintenance medication is a critical factor in their survival,” said senior study author Smita Bhatia, MD, MPH, of City of Hope in Duarte, California.
Dr. Bhatia and a team of investigators began their research studying differences in mercaptopurine adherence among different racial groups of children in remission from ALL in 2012, reporting that Hispanic children did not follow their prescribed mercaptopurine maintenance regimen as consistently as non-Hispanic whites.
To examine mercaptopurine adherence in African American, Asian, and non-Hispanic white children in remission from ALL, the research team enrolled 298 patients from 77 institutions in a study that tracked mercaptopurine drug levels in the bloodstream, responses from a questionnaire administered to their families, and, an electronic method for monitoring maintenance. Each patient enrolled in the study, who was prescribed mercaptopurine, was provided with a pill bottle equipped with a microprocessor chip in the cap that recorded each date and time the bottle was opened for a period of 6 months.
Of all three groups, the African American children took their mercaptopurine the least often, with 46% of them taking 90% or less of their medication, the threshold for nonadherence at which risk of relapse became statistically significant. While the Asian children in the study group took their medication more consistently, 28% of them did not take at least 90% of their medication.
Non-Hispanic white children were more adherent to their maintenance therapy regimen than any other group; however, 14% still did not take enough mercaptopurine to meet researchers’ criterion for drug adherence. Taken together, approximately 25% of the children enrolled in the study did not take their mercaptopurine at least 90% of the time, tripling their relapse risk, according to investigators.
Further Study Needed
Dr. Bhatia noted in a news release that “our data demonstrate that one in four children in remission from ALL does not take the medicine needed to remain cancer free, and in an overwhelming majority, the primary reason why is that they forget to take their pills each day.” She added, “These results are the basis for further studies that will examine how physicians can successfully intervene using technology, for example, to ensure that children do not experience an increased risk of relapse because they did not take their oral chemotherapy.” ■
Disclosure: For full disclosures of the study authors, visit bloodjournal.hematologylibrary.org.
1. Bhatia S, Landier W, Hageman L, et al: Adherence to oral 6-mercaptopurine in African American and Asian children with acute lymphoblastic leukemia: A Children’s Oncology Group study. Blood. June 2, 2014 (early release online).