INTRODUCTION
Successful treatment of pediatric acute lymphoblastic leukemia (ALL) requires at least two-years of risk-directed therapy built on a backbone of oral chemotherapy, including 6-mercaptopurine (6MP) and dexamethasone. Studies from the Children’s Oncology Group (COG) demonstrated that less than 90% adherence to 6MP during maintenance therapy was associated with up to a 3.9-fold increased relapse risk.1 Non-adherence in these studies was associated with lack of routine surrounding medication taking, patient race/ethnicity and age, household structure, and parent educational attainment.1 Little is known about 6MP adherence rates in the context of non-COG ALL treatment regimens—where different treatment schedules and modes of chemotherapy delivery (e.g. oral versus intravenous [IV] administration of chemotherapy agents) may impact frequency and reasons for non-adherence.
Compared to the continuous daily 6MP, oral weekly methotrexate and repeating 4-week cycles in COG ALL trials, Dana-Farber Cancer Institute (DFCI) ALL Consortium protocols utilize 14-day pulses of 6MP with weekly IV methotrexate throughout maintenance in repeating 3-week cycles.2 This chemotherapy delivery approach requires more frequent contact between families and healthcare providers and reduces the number of oral chemotherapy agents. We explored whether the “higher-touch” of every 3-week clinic visits for cycle initiation along with use of IV methotrexate–necessitating weekly clinic visits or visiting nurse administration—might reduce the frequency of 6MP non-adherence on the DFCI regimen as compared to published COG data.3 Specifically, we aimed to explore the prevalence of parent-reported 6MP non-adherence in the context of DFCI ALL Consortium-based therapy utilizing a cross-sectional survey, and to identify whether sociodemographic factors, medication-taking logistics or chemotherapy comprehension impacted adherence rates in a DFCI cohort.