NCT06299891

Efficacy and Safety of Phentermine/Topiramate in Youth With Hypothalamic Obesity

Phentermine/Topiramate in Children, Adolescents, and Young Adults With Hypothalamic Obesity: a Pilot and Feasibility Study

• Status: Recruiting
• Phase: Phase 2
• Study type: Interventional
• Enrollment: 24 (estimated)
• Sponsor: Seattle Children's Hospital · Academic / Other
• Sex: All
• Age: 6 Years – 28 Years
• Healthy volunteers: Not accepted

Summary

Hypothalamic obesity (HO) refers to the substantial weight gain that often complicates hypothalamic brain tumors. Children with this treatment-recalcitrant form of obesity have excess rates of metabolic sequelae compared to otherwise healthy children with similar obesity, and later experience excess mortality related to cardiometabolic disease. In this pilot trial, our objective is to gather key preliminary data about phentermine/topiramate (Ph/T) that is FDA-approved for "common" obesity but has never been tested in HO. The subset of individuals with HO who experience hyperphagia or excess daytime sleepiness may benefit from the Ph/T-induced decrease in appetite and increase in alertness. Preliminary assessments of safety, adverse events, dosing (Aim 1), as well as of efficacy (% BMI loss, Aim 2) will be made in a 28-week parallel-arm double-blinded Phase 2 placebo-controlled clinical trial in 6-28-year-old individuals with HO.

Detailed description

STUDY OVERVIEW This is a two-center, double-blind (participant and assessor), randomized, parallel-arm 28-week clinical phase II trial, comparing changes from pre- to post treatment in two study arms of active drug (Qsymia®) vs. placebo capsules. Twenty-four 6-28-year-old participants will be randomized 1:1 into the two intervention groups. The study will have a single central IRB (CHOP). In this pilot trial, the objective is to gather key preliminary data about phentermine/topiramate (Ph/T), a promising option containing a sympathomimetic amine (Ph) combined with an appetite-suppressive epilepsy drug (T) that is FDA-approved for "common" obesity but has never been tested in HO. The subset of individuals with HO who experience hyperphagia or excess daytime sleepiness may benefit from the Ph/T-induced decrease in appetite and increase in alertness. Preliminary assessments of safety and dosing (adverse events and maximum tolerated dose - Aim 1), as well as of efficacy (% BMI loss - Aim 2) will be made in a 28-week parallel-arm double-blinded Phase 2 randomized placebo-controlled clinical trial in 6-28-year-old individuals with HO. The FDA-approved dose titration will be followed. Other efficacy and mechanistic outcomes will be measured as well. Specific Aims: Aim 1: To assess safety and maximum tolerated dose of Ph/T. Main outcomes: treatment-emergent adverse events (including any during withdrawal), maximum tolerated dose (weeks 0 to 28). Aim 2: To estimate the treatment effect of Ph/T with respect to weight loss in individuals with HO. Main outcome: % change in BMI (week 0 to 28) in response to Ph/T vs. placebo. Study Approach: Recruitment. Subjects will be required to travel to one of the two research sites (Seattle WA; Philadelphia PA). Each subject will be treated for 28 weeks plus 1 week of an appropriate taper in those participants who reached the highest dose at titration. Participants will be pre-screened for eligibility via medical record review. Once written informed consent is obtained, eligibility will be confirmed. Randomization. Eligible subjects will be assigned treatment using a permuted-block randomization (1:1) to drug vs. placebo for 28 weeks with varying block sizes constructed by the CHOP study statistician. Study visits. Each participant will have a screening visit and 5 in-person study visits: Weeks 1 (baseline), 3, 14, 16, 28 (end of randomized trial). There will be a remote contact one week (+/- 3 days) after dose initiation and/or dose escalation to assess dose tolerability. The remote contact at 29 weeks will be performed to assess for any withdrawal effects and will be done in-person if there are any safety concerns that are most appropriately assessed in person. Visits at 1 and 28 weeks will be used for main outcome collection. Interim visits are required for assessment of dose escalation. Weeks 3 and 16 visits could be done remotely to reduce burden, in particular for individuals traveling from a distance, if participants prefer and have no concerning safety signals. Participants will be compensated for their time and travel. Efforts will be made to schedule study appointments at times that will accommodate participants' schedules. Main outcome for Aim 1: Safety, as assessed by systematic collection of treatment-emergent adverse events using a safety monitoring uniform report form (SMURF), with adverse events graded according to Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Secondary outcome for Aim 1: Maximum tolerated dose of Ph/T, as defined by the dose of Ph/T that the participant is continuing to take at the week 28 visit, reflecting any dose individualization. Main outcome for Aim 2: % change in BMI between weeks 1 (baseline) and week 28 (end of treatment). Key secondary outcomes for Aim 2 (all assessed as change between weeks 1 and 28): proportion of participants who achieve at least 2.5% BMI reduction, proportion of participants who achieve at least 5% BMI reduction, change in fat mass and visceral fat (as assessed by DXA) from Baseline to Week 28.

Conditions

• Hypothalamic Obesity
• Hypothalamic Tumor
• Craniopharyngioma

Interventions

Type	Name	Description
DRUG	Phentermine / Topiramate Extended Release Oral Capsule [Qsymia]	To assess safety and maximum tolerated dose as well as efficacy on weight loss of Phentermine/Topiramate in individuals with hypothalamic obesity.
OTHER	Placebo	To assess safety and maximum tolerated dose as well as efficacy on weight loss of placebo treatment in individuals with hypothalamic obesity.

Timeline

• Start date: 2025-03-01
• Primary completion: 2026-02-28
• Completion: 2026-05-31
• First posted: 2024-03-08
• Last updated: 2025-07-28

Locations

2 sites across 1 country: United States

Regulatory

• FDA-regulated drug study