12497 Stage 1 Results Of The Phase 2 Daybreak Trial Assessing Setmelanotide In Patients With Early-onset, Severe Obesity And Hyperphagia Who Carried A Confirmed Variant Related To The Melanocortin-4 Receptor Pathway

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Abstract Disclosure: G. Ortiz: Speaker; Self; Rhythm Pharmaceuticals, Inc. S.B. Ten: Advisory Board Member; Self; Rhythm Pharmaceuticals, Inc. Speaker; Self; Rhythm Pharmaceuticals, Inc. W. Herring: Advisory Board Member; Self; Rhythm Pharmaceuticals, Inc, Novo Nordisk. O. Pinhas-Hamiel: None. E.A. Oral: Consulting Fee; Self; Rhythm Pharmaceuticals, Inc., Akcea Therapeutics, Ionis Pharmaceuticals Inc., Morphic Medical, Fractyl Laboratories, Regeneron Pharmaceuticals, Amryt Pharmaceuticals (now Chiesi), Third Rock Ventures, Rejuvenate Bio, NIDDK. Other; Self; Has patents for use of metreleptin in lipodystrophy and recombinant leptin or analogues in NASH. N. Rosano: Consulting Fee; Self; Novo Nordisk. Speaker; Self; Rhythm Pharmaceuticals, Inc. D. Koren: Employee; Self; Rhythm Pharmaceuticals, Inc.. Stock Owner; Self; Rhythm Pharmaceuticals, Inc. H. Lee: Employee; Self; Rhythm Pharmaceuticals, Inc.. Stock Owner; Self; Rhythm Pharmaceuticals, Inc. J. Garrison: Employee; Self; Rhythm Pharmaceuticals, Inc.. Stock Owner; Self; Rhythm Pharmaceuticals, Inc. O. Ohayon: Employee; Self; Rhythm Pharmaceuticals, Inc.. Stock Owner; Self; Rhythm Pharmaceuticals, Inc. P. Sleiman: Employee; Self; Rhythm Pharmaceuticals, Inc.. Stock Owner; Self; Rhythm Pharmaceuticals, Inc. M. Wabitsch: Consulting Fee; Self; Rhythm Pharmaceuticals, Inc.. Speaker; Self; Rhythm Pharmaceuticals, Inc.. Other; Self; Rhythm Pharmaceuticals, Inc. E. van den Akker: Speaker; Self; Federatie Medisch Specialisten, Stichting Kwaliteitsgelden Medisch Specialisten, Medialane TV, Pfizer, Inc.. Other; Self; Nederlandse Hartstichting/ZonMW, Stichting Erasmus Trustfonds, Rhythm Pharmaceuticals, Inc. J. Argente: Advisory Board Member; Self; Rhythm Pharmaceuticals, Inc. Speaker; Self; Rhythm Pharmaceuticals, Inc.. I. Farooqi: None. Background: DAYBREAK (NCT04963231) was designed to evaluate setmelanotide in individuals who carried a confirmed variant in ≥1 of 31 genes with strong or very strong relevance to the melanocortin-4 receptor (MC4R) pathway, which regulates energy balance and satiety. Methods: DAYBREAK is a 2-stage, double-blind, placebo-controlled trial conducted at 37 sites across 8 countries. Individuals aged 6 to 65 years with body mass index (BMI) ≥40 kg/m2 (aged ≥18 years) or ≥97th percentile (aged ≥6 to <18 years) and hyperphagia who carried variants classified as uncertain significance (VUS), likely pathogenic, or pathogenic according to the American College of Medical Genetics (ACMG) criteria in ≥1 of the 31 genes were eligible. Individuals with ≥5% BMI reduction from baseline (ie, responders) at the end of the 16-week, open-label run-in period (Stage 1) were eligible to enter a 24-week, double-blind, randomized, placebo-controlled period (Stage 2). The primary endpoint of Stage 1 was the proportion of responders per gene cohort at the end of the Stage. Results: A total of 164 individuals were enrolled; 100 patients who completed Stage 1 and 12 who discontinued treatment within a prespecified 2 weeks before the end of Stage 1 were included in the completers analysis. Participants were divided into 15 gene cohorts; of 7 cohorts with ≥5 patients, 6 (SEMA3[A-G], PLXNA[1-4], PHIP, TBX3, MAGEL2, and SIM1) showed potential setmelanotide efficacy (KSR2 did not). Response rates across cohorts (range, 25.0%-56.3%), intracohort response magnitudes (percent BMI change from baseline to Week 16; range, −6.4% to −4.0%), and intracohort variant types varied. While response rate was highest in the PHIP cohort (56.3% of the full cohort and 69.2% of completers), ≥1 patient per cohort achieved ≥10% BMI reduction. Because ∼80% of VUS are eventually reclassified to benign or likely benign, the inclusion of VUS may have contributed to response variability. An ad hoc analysis showed an increased response rate with updated versus starting ACMG variant classification. Overall, 49 responders across 6 gene cohorts were randomized into Stage 2. Setmelanotide was well tolerated with no new safety concerns. Conclusions: DAYBREAK Stage 1 identified 6 additional genes or gene families in the MC4R pathway that respond to setmelanotide. Response was associated with predicted variant pathogenicity, allowing for further refinement of patient selection. Stage 2 results will further elucidate Stage 1 findings. Presentation: 6/3/2024