Obesity Treatment With Phentermine-Topiramate ER in AYA Surviving Leukemia and Lymphoma

Survivors of childhood leukemia and lymphoma are at increased risk for obesity and cardiometabolic complications during treatment and early survivorship. The OPTIMAL study is evaluating whether adding the FDA-approved weight-loss medication phentermine-topiramate extended release (ER) to healthy lifestyle counseling is practical, safe, and may improve weight-related outcomes in survivors of leukemia and lymphoma with obesity. The study will enroll participants ages 12 to under 25 years who are in remission from acute lymphoblastic leukemia (ALL), Hodgkin lymphoma, or non-Hodgkin lymphoma and are completing outpatient therapy or are within approximately 2 years of therapy completion. Participants assigned to the intervention arm will receive daily phentermine-topiramate ER with dose escalation according to FDA-approved obesity treatment guidelines in addition to counseling every 4 weeks. Participants assigned to the control arm will receive counseling alone. The intervention period lasts 24 weeks, followed by an observational follow-up visit at week 52 to assess durability of response. Researchers will assess study participation and completion rates, medication safety and tolerability, and changes in body weight and BMI. The study will also explore effects on body composition, heart and metabolic health, physical activity, eating habits, cognitive function, and quality of life. Primary Objective: * Determine the feasibility of obesity treatment using combination phentermine and extended-release topiramate plus health behavior and lifestyle counselling (PHEN/TOP) compared to health behavior and lifestyle counselling alone as standard of care (SOC) in adolescent and young adult patients with ALL or lymphoma and obesity who have achieved remission and are completing outpatient, maintenance therapy or in the first 2 years of survivorship. Secondary Objective: * Determine the tolerability of PHEN/TOP compared to SOC alone in adolescent and young adult patients with ALL or lymphoma and obesity. * Estimate preliminary efficacy of PHEN/TOP compared to SOC for change in body mass index (BMI) in adolescent and young adult patients with ALL or lymphoma and obesity.