A feasibility, acceptability, and optimization protocol for a mobile health intervention to reduce sedentary behavior among adolescents and early young adults receiving treatment for acute lymphoblastic leukemia: Part 1 of the ReSeT in ALL trial (Preprint)

BACKGROUND Sedentary behavior (SB) is highly prevalent among adolescents and early young adults (eAYAs) with acute lymphoblastic leukemia (ALL) during treatment and contributes to cardiometabolic complications and morbidity among long-term survivors. SB is distinct from physical inactivity and independently associated with adverse health outcomes, yet few interventions in pediatric oncology have directly targeted reducing SB. OBJECTIVE The ReSeT in ALL trial was designed as a two-part study to address this research gap. This protocol describes Part 1 (1A and 1B, feasibility trial and optimization phase, respectively), including trial design, analysis plan, and anticipated approach to intervention refinement. METHODS Part 1A was a 12-week, single-arm feasibility trial evaluating a multi-component mobile health (mHealth) intervention to reduce SB among 20 eAYA patients (ages 12–21) with ALL receiving maintenance therapy at Children’s Hospital Los Angeles. The intervention included a Fitbit tracker with inactivity-triggered prompts, three individualized coaching sessions, and a novel app-based peer support group. Primary outcomes were feasibility (retention, enrollment, tracker wear time) and acceptability (exit surveys and interviews). Secondary outcomes included accelerometer-measured sedentary time and self-reported sitting time. Exploratory outcomes included cardiometabolic biomarkers, anthropometrics, health-related quality of life, and psychosocial/environmental correlates of SB. Part 1B was a synthetic step in which participant feedback and outcome data from Part 1A guided optimization of the intervention prior to being tested via randomized controlled trial in the future Part 2. RESULTS The study received initial funding in 2024. Participant enrollment, data collection, and data analysis have been completed. The manuscript reporting the primary trial outcomes is currently under peer review. CONCLUSIONS Part 1 (1A and 1B) of the ReSeT in ALL trial provides the foundation for evaluation of a novel on-therapy SB intervention, integrating wearable technology, individualized coaching, and peer support, while using a stepwise design to optimize intervention components for rigorous testing in Part 2 and future efficacy trials. CLINICALTRIAL ClinicalTrials.gov NCT06182163. Registered December 13, 2023, https://www.clinicaltrials.gov/study/NCT06182163.