Rhythm Pharmaceuticals on Monday said a late-stage trial evaluating its MC4R agonist Imcivree (setmelanotide) in patients with rare, genetically-driven obesities failed to meet pre-specified primary goals across all four genetic substudies, sending the company's stock sliding nearly 5%.The Phase III EMANATE trial assessed Imcivree's efficacy — measured as mean percentage change in body mass index (BMI) from baseline to week 52 in the modified intent-to-treat population — against placebo among 295 participants carrying heterozygous (Hets) variants of the POMC/PCSK1, leptin receptor (LEPR), SRC1 (NCOA1), and SH2B1 genes.Top-line findings showed that placebo-adjusted BMI reductions with Imcivree were -4.3% in the POMC/PCSK1 Hets substudy, -3.6% in LEPR Hets, -4.0% in SRC1 and -1.7% in SH2B1, none of which achieved statistical significance.Rhythm, however, noted that in post hoc analyses using last observation carried forward for missing values, Imcivree delivered significant BMI reductions in the POMC/PCSK1 Hets (-5.5%) and SRC1 (-6.2%) substudies. Moreover, among participants completing the full 52-week treatment period, placebo-adjusted BMI reductions reached -9.7% and -8.0% in the respective substudies."While we are disappointed the EMANATE substudies did not meet their primary endpoint, we are encouraged by compelling signals from additional analyses of…POMC/PCSK1 and SRC1 substudies and learnings that sharpen our ability to identify true loss-of-function variants," said David Meeker, chief executive of Rhythm.In terms of safety, no signals were identified; the most common treatment-emergent adverse events, including skin hyperpigmentation, injection site reactions, nausea, vomiting, and headache, were consistent with the drug's established profile.As next steps, the biotech intends to pursue clinical development in SRC1 and POMC indications using its next-generation MC4R agonists, bivamelagon (LB54640) — licensed from LG Chem — and RM-718, while continuing to explore MC4R agonism across gene families identified in the mid-stage DAYBREAK trial, including SEMA3, PHIP, TBX3, and the PLXNA family.Imcivree was first approved by the FDA in 2020 for chronic weight management in adults and children aged six and older with obesity due to POMC, PCSK1 or LEPR deficiencies, with a subsequent approval for obesity due to Bardet-Biedl Syndrome in individuals aged six and above, and later for patients as young as 2 years across all indications.Rhythm is also awaiting an FDA decision on the drug's acquired hypothalamic obesity indication, due this month, after facing a delay. In December, the company also touted favourable Phase II data for the MC4R agonist in Prader-Willi syndrome.