8-K: Rhythm Pharma EMANATE Trial Misses Primary Endpoints

Rhythm Pharmaceuticals announced that its Phase 3 EMANATE trial for setmelanotide did not meet primary endpoints in four substudies, though post hoc analyses showed significant BMI reductions in two patient populations.

Summary

• Rhythm Pharmaceuticals announced topline results from its Phase 3 EMANATE trial for setmelanotide on March 16, 2026.
• The four substudies of the EMANATE trial, evaluating setmelanotide in patients with obesity due to heterozygous variants of POMC/PCSK1, LEPR, SRC1 (NCOA1), and SH2B1 genes, did not meet their pre-specified primary endpoints.
• The primary endpoint was the difference in mean percent change in BMI from baseline to Week 52 versus placebo, analyzed in the modified intent-to-treat (ITT) population using prespecified multiple imputation.
• Topline primary endpoint results were: POMC/PCSK1 Hets (N=78) 4.3% placebo-adjusted BMI reduction (p=0.15); LEPR Hets (N=23) 3.6% (p=0.94); SRC1 (NCOA1) (N=73) 4.0% (p=0.12); and SH2B1 (N=121) 1.7% (p=0.43).
• Post hoc analyses based on last observation carried forward (LOCF) for missing values showed setmelanotide achieved statistically significant and clinically meaningful BMI reductions at Week 52 in the modified ITT populations for POMC/PCSK1 Hets (5.5% least-squares mean difference, p=0.0010) and SRC1 (NCOA1) (6.2% least-squares mean difference, p<0.0001).
• Post hoc analyses of genetically confirmed patients who completed 52 weeks of treatment showed statistically significant BMI reductions in POMC/PCSK1 Hets (9.7% placebo-adjusted reduction, p=0.0002) and SRC1 (NCOA1) (8.0% placebo-adjusted reduction, p=0.0158).
• No new safety signals were observed with setmelanotide in the EMANATE trial, and the safety profile was consistent with prior clinical studies and commercial experience.
• The most common treatment-emergent adverse events included skin hyperpigmentation, injection site reactions, nausea, vomiting, and headache.
• High discontinuation rates across all four substudies (48% in placebo, 42% in setmelanotide arms) negatively affected topline results, driven by factors such as subject decision, adverse events, and withdrawal of consent.

Sentiment

Score: 4

Explanation: StockSavvy.ai views this as a mixed but predominantly negative outcome. While the primary endpoints were missed, the statistically significant results in post hoc analyses for specific patient groups offer a glimmer of hope and a refined development path, preventing a complete failure.

Positives

• Post hoc analyses demonstrated statistically significant and clinically meaningful BMI reductions in POMC/PCSK1 Hets patients (5.5% least-squares mean difference, p=0.0010 in mITT; 9.7% placebo-adjusted reduction in completers, p=0.0002).
• Post hoc analyses demonstrated statistically significant and clinically meaningful BMI reductions in SRC1 (NCOA1) patients (6.2% least-squares mean difference, p<0.0001 in mITT; 8.0% placebo-adjusted reduction in completers, p=0.0158).
• No new safety signals were observed with setmelanotide, and its safety profile was consistent with prior clinical studies and commercial experience.
• The company gained a deeper understanding of MC4R pathway genetics and variant classification, which will inform future development of next-generation MC4R agonists.

Negatives

• All four substudies (POMC/PCSK1 Hets, LEPR Hets, SRC1 (NCOA1), and SH2B1) of the EMANATE trial did not meet their pre-specified primary endpoints.
• The primary endpoint analysis, using prespecified multiple imputation, was potentially confounded by a placebo effect and high discontinuation rates.
• High discontinuation rates were observed across all four substudies, with 48% in the placebo arm and 42% in the setmelanotide arm (all substudies combined).
• The LEPR Hets substudy showed a very high p-value (0.94) for the primary endpoint, indicating no significant effect.
• The SH2B1 substudy showed a low placebo-adjusted reduction (1.7%) and high p-value (0.43) for the primary endpoint, with no significant difference in post-hoc analysis of completers.

Risks

• Ability to enroll patients in clinical trials.
• The design and outcome of clinical trials.
• The impact of competition.
• The ability to achieve or obtain necessary regulatory approvals.
• Risks associated with data analysis and reporting.
• The ability to successfully commercialize setmelanotide.
• Liquidity and expenses.
• The ability to retain key employees and consultants, and to attract, retain and motivate qualified personnel.
• General economic conditions.
• Disturbance in Sexual Arousal, including spontaneous penile erections in males and sexual adverse reactions in females.
• Depression and Suicidal Ideation, requiring monitoring for new onset or worsening symptoms.
• Hypersensitivity Reactions, such as anaphylaxis, which may require discontinuation.
• Skin Hyperpigmentation, darkening of pre-existing nevi, and development of new melanocytic nevi, requiring periodic full body skin examinations.
• Risk of Serious Adverse Reactions Due to Benzyl Alcohol Preservative in Neonates and Low Birth Weight Infants, as IMCIVREE is not approved for this population.
• Treatment with IMCIVREE is not recommended when breastfeeding.
• Discontinue IMCIVREE when pregnancy is recognized unless the benefits of therapy outweigh the potential risks to the fetus.

Future Outlook

Rhythm plans to continue analyzing the EMANATE dataset and evaluate potential clinical development paths forward with SRC1 (NCOA1) and POMC using its next-generation MC4R agonists, bivamelagon and RM-718. The company will also continue to evaluate the potential for MC4R agonism in genes and gene families previously identified through the exploratory Phase 2 DAYBREAK trial, including the SEMA3 family, PHIP, TBX3, or PLXNA family. Additionally, Rhythm is advancing a broad clinical development program for setmelanotide in other rare diseases, as well as investigational MC4R agonists bivamelagon and RM-718, and a preclinical suite of small molecules for the treatment of congenital hyperinsulinism.

Management Comments

• "We are grateful to the patients with rare, genetically-driven MC4R pathway diseases and investigators who participated in this trial." David Meeker, MD, Chair, President and Chief Executive Officer.
• "While we are disappointed the EMANATE substudies did not meet their primary endpoint, we are encouraged by compelling signals from additional analyses of the heterozygous POMC/PCSK1 and SRC1 substudies and learnings that sharpen our ability to identify true loss-of-function variants and inform the development of our next-generation MC4R agonists in rare genetically driven obesity indications." David Meeker, MD.
• "These patients continue to face a profound unmet medical need, with no approved treatment options that target the underlying biology of their disease. These results provide important insights that support our commitment to advancing targeted therapies for patients with rare genetic obesities." David Meeker, MD.

Industry Context

StockSavvy.ai notes that the failure of primary endpoints in a Phase 3 trial for a rare disease treatment like setmelanotide is a significant setback, potentially impacting Rhythm's market position in the specialized MC4R pathway obesity segment. However, the encouraging post hoc analyses in specific genetic subgroups (POMC/PCSK1 Hets and SRC1) suggest a path forward for targeted therapies, aligning with a broader industry trend towards precision medicine in rare diseases. The focus on next-generation MC4R agonists (bivamelagon and RM-718) indicates a strategic pivot to leverage learnings and refine drug development for these complex genetic conditions, potentially mitigating the impact of this trial's primary outcome.

Stakeholder Impact

• Shareholders: Potential negative impact due to primary endpoint failure, but mitigated by positive post-hoc data and future development plans. Increased uncertainty regarding setmelanotide's broader applicability.
• Patients: Continued unmet medical need for those with rare genetic obesities, but potential for future targeted therapies based on refined understanding of loss-of-function variants.
• Employees: Continued focus on R&D for next-generation agonists and other indications.

Next Steps

• Continue analysis of the EMANATE dataset.
• Evaluate potential clinical development paths forward with SRC1 (NCOA1) and POMC using next-generation MC4R agonists bivamelagon and RM-718.
• Continue to evaluate the potential for MC4R agonism in genes and gene families identified through the exploratory Phase 2 DAYBREAK trial (SEMA3 family, PHIP, TBX3, PLXNA family).
• Host a live conference call and webcast on March 16, 2026, at 4:30 p.m. ET to discuss the update.
• Advance a broad clinical development program for setmelanotide in other rare diseases.
• Advance investigational MC4R agonists bivamelagon and RM-718.
• Advance a preclinical suite of small molecules for the treatment of congenital hyperinsulinism.
• Initiate Ph1/2 trial with RM-718 for Prader-Willi Syndrome.
• Plan Ph3 trial with bivamelagon by YE 2026 for Hypothalamic Obesity.

Key Dates

Recommendation

The primary endpoint failure is a significant negative, typically leading to a "sell" recommendation. However, the statistically significant and clinically meaningful results from the post-hoc analyses in specific patient subgroups (POMC/PCSK1 Hets and SRC1) provide a potential path forward and demonstrate some efficacy. This mixed outcome, coupled with the company's commitment to next-generation agonists and other pipeline programs, suggests that while the immediate outlook is challenging, there is still long-term potential. A "hold" recommendation allows investors to monitor the company's refined development strategy and further data analysis before making a definitive buy or sell decision.

Keywords

Rhythm Pharmaceuticals, RYTM, EMANATE trial, setmelanotide, obesity, rare genetic obesity, MC4R pathway, POMC/PCSK1, SRC1 (NCOA1), LEPR, SH2B1, BMI reduction, clinical trial, Phase 3, biopharmaceutical, neuroendocrine diseases, IMCIVREE, bivamelagon, RM-718