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.