Setmelanotide in patients aged 2-5 years with rare MC4R pathway-associated obesity (VENTURE): a 1 year, open-label,...

Setmelanotide, a melanocortin-4 receptor (MC4R) agonist, has been shown to reduce hunger and weight in patients aged 6 years and older with proopiomelanocortin (POMC) deficiency (including biallelic variants in proprotein convertase subtilisin/kexin type 1 [PCSK1]), leptin receptor (LEPR) deficiency, or Bardet-Biedl syndrome (BBS). No approved therapies for patients younger than 6 years old currently exist. The phase 3, open-label VENTURE trial aimed to evaluate the efficacy and safety of setmelanotide in patients aged 2-5 years with POMC or LEPR deficiency or BBS.

This phase 3, open-label, multicentre trial, conducted across six sites in the USA, the UK, Spain, and Australia, enrolled eligible patients aged 2-5 years who had hyperphagia and obesity due to biallelic POMC (including PCSK1) or LEPR variants or genetically confirmed BBS. Open-label subcutaneous setmelanotide was administered once daily for 52 weeks, starting at 0·5 mg with doses increasing every 2 weeks in 0·5 mg increments until reaching the maximum dose based on weight. The co-primary endpoints at week 52 were the percentage of patients reaching a 0·2-point decrease or greater in BMI Z score (a statistical measure used to assess BMI in paediatric patients considering a patient's BMI and comparing it to reference values for the same age and sex) and mean percent change in BMI. Additional endpoints measured safety, hunger, weight-related outcomes, and caregiver burden. The study is registered at ClinicalTrials.gov (NCT04966741) and is complete.

Between March 8, 2022, and Sept 18, 2023, 13 patients were screened at the six sites, and 12 patients were enrolled in the study (seven with POMC or LEPR and five with BBS); one patient with BBS was excluded as their BMI was not at the 97th percentile or above. Of the 12 patients enrolled, most were male (seven [58%] vs five [42%] for female) and the mean age was 3·6 years (SD 0·9). 11 patients completed the trial. Ten (83%) of the 12 overall participants reached a 0·2-point reduction or more in BMI Z score per WHO methodology at week 52 (95% CI 58·7-99·8). The mean percent change in BMI from baseline at week 52 was -18% (SD 13) in the overall safety population. Mean percent change in BMI at week 52 was -26% (SD 11) in patients with POMC or LEPR deficiency and -10% (9) in patients with BBS. Mean reductions in secondary endpoints of BMI Z score (3·4 [2·5]) and percent of the BMI 95th percentile (32·5 [22·9]) were seen at Week 52. 91% of caregivers reported that patients were less hungry than at baseline. All adverse events were mild or moderate; skin hyperpigmentation, vomiting, nasopharyngitis, upper respiratory tract infection, and injection site reactions were most common. No serious adverse events or adverse events leading to study discontinuation or death were reported.

To our knowledge this is the first trial of setmelanotide in patients younger than 6 years old. These results support the benefit of the drug as an early intervention to manage obesity in this population.

Rhythm Pharmaceuticals.