PROJECT SUMMARY/ABSTRACT Excessive weight gain leading to obesity is common during the early phases of pediatric acute lymphoblastic leukemia (ALL) treatment, and results in higher risk of relapse, lower event-free survival rates, and more adverse events during treatment. Yet, effective preventive interventions for excessive weight gain during the early phases of ALL treatment are lacking. Aligned with NCI priorities, the long-term objective of this work is to mitigate weight- related disparities in pediatric cancer treatment outcomes. Guided by the ORBIT Model of Behavioral Intervention Development, the goal of this proposal is to adapt, refine, and pilot test a family-based health promotion intervention that aims to curb excessive weight gain among youth with ALL by integrating support for family coping with stress during the early phases of ALL treatment. Given that ALL is most prevalent in young children, families play an essential role in shaping youth’s health behaviors during treatment. In Aim 1a, the PI and her mentorship team will adapt an existing family-based health promotion intervention (NOURISH-T) to meet the specific needs of families of youth in the early phases of ALL treatment (NOURISH-ALL). Adaptations will incorporate family systems and cognitive behavioral intervention components to support healthy family coping with diagnosis and treatment stress. Additional, patient-centered adaptations regarding intervention content and delivery will be informed by semi-structured input from families and youth with ALL (n=10 at minimum) and multidisciplinary clinical experts (n=6 at minimum) until thematic saturation is reached. In Aim 1b, the investigative team will iteratively refine the NOURISH-ALL intervention through sequential testing with families and youth with ALL (n=5 at minimum) and structured participant feedback. Intervention refinement will be ongoing until >80% feasibility and acceptability ratings are achieved or until n=10 families complete the intervention and provide structured feedback. In Aim 2, the adapted and refined NOURISH-ALL intervention will be pilot tested in a single arm trial with 20 newly recruited families of youth in the early phases of ALL treatment. The research team will assess key components of participant engagement to inform the future, fully powered clinical trial, including recruitment rate, retention at treatment completion, and intended intervention dose received. By incorporating tailored strategies for health promotion during the early phases of ALL treatment, the proposed study seeks to shift clinical practice paradigms to prevent weight-related disparities in treatment outcomes. This K08 will provide opportunities for the PI to acquire skills and knowledge in: (1) the early phases of ALL treatment, (2) scientific adaptation and refinement of family-based behavior change interventions, and (3) the conduct of clinical trials focused on behavior change interventions. The research and career deve...