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.

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.
Children with ALL are given restrictive guidelines on how to take their oral chemotherapy (6-mercaptopurine) in order to maximize medication bioavailability (in the evening, on empty stomach, without dairy) but which may interfere with chemo adherence. Due to the established link between outcome and adherence to oral chemotherapy, the COG conducted a prospective study (AALL03N1; 441 patients) to look at the association of ingestion habits and adherence, red cell thioguanine levels (TGN) and ultimately relapse.
Adherence was measured using a medication event monitoring system that recorded when medication bottles were opened along with questionnaires and institutional outcome data.
After adjusting for other prognostic factors (including adherence), there was no association between ingestion habits and relapse risk or red cell TGN levels. Taking medications at varying times of day was associated with non-adherence (43.8%).
This study was limited by its observational design, lack of data on reasons for varying ingestion patterns along with some missing prognostic information like MRD.
Overly restrictive guidelines around oral chemotherapy administration for children with ALL are not necessary and may in fact contribute to lower medication adherence which is known to be prognostic. The COG chemo guidelines as well as our local practice has changed to promote the importance of consistent medication administration above all else.