--- title: "HRS9531 (KAI-9531): Hengrui and Kailera's Injectable GLP-1/GIP Dual Agonist Posts Tirzepatide-Class Weight Loss in Phase 3 (September 4, 2026) | PepTracker Pro Blog" url: https://peptrackerpro.com/blog/hrs9531-kai-9531-hengrui-kailera-injectable-dual-glp1-gip-receptor-agonist-tirzepatide-class-gemini-1-phase-3-obesity-china-nmpa-weight-loss-8mg-10mg-global-program-september-4-2026 description: "HRS9531 - developed globally as KAI-9531 - is a once-weekly injectable dual GLP-1/GIP receptor agonist in the same class as tirzepatide. In the Phase 3 GEMINI-1 trial in China it produced about 17-19% mean weight loss at 48 weeks, and higher 8 mg and 10 mg doses are now in a global Phase 3 program." lang: en --- Skip to main content **Educational information only.** This site does not provide medical advice. Read full disclaimer (https://peptrackerpro.com/disclaimer) Research & Compounds Research & Compounds # HRS9531 (KAI-9531): Hengrui and Kailera's Injectable GLP-1/GIP Dual Agonist Posts Tirzepatide-Class Weight Loss in Phase 3 (September 4, 2026) PepTracker Pro Research Team September 4, 2026 9 min read ## Table of Contents - Another dual agonist enters the tirzepatide arena - What HRS9531 is - and how dual GLP-1/GIP agonism works - GEMINI-1: about 17-19% weight loss at 48 weeks - The responder numbers: most patients lost meaningful weight - Phase 2 hinted at even more at a higher dose - How it compares with tirzepatide (with the usual caveats) - Tolerability: familiar GI side effects, very few dropouts - The Hengrui-Kailera partnership and a China-to-global trend - What happens next: China filing and a global Phase 3 program - The bottom line ## Another dual agonist enters the tirzepatide arena For a few years, the top tier of obesity medicine has been defined by one mechanism: dual agonism of the GLP-1 and GIP receptors, embodied by Eli Lilly's tirzepatide (Zepbound for obesity, Mounjaro for type 2 diabetes). HRS9531 is a once-weekly injectable peptide that hits the same two incretin receptors - and in its pivotal Phase 3 trial in China it delivered weight loss in the same neighborhood as tirzepatide. Developed independently by Jiangsu Hengrui Pharmaceuticals, one of China's largest drugmakers, and licensed for global development (outside Greater China) to U.S. biotech Kailera Therapeutics under the code KAI-9531, HRS9531 has become one of the most closely watched 'fast-follower' incretin drugs in the obesity pipeline. ## What HRS9531 is - and how dual GLP-1/GIP agonism works HRS9531 is an engineered peptide that simultaneously activates the receptors for two gut hormones: glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). GLP-1 signaling reduces appetite, slows how quickly the stomach empties, and improves glucose-dependent insulin release; adding GIP activity appears to complement those effects and improve tolerability and metabolic outcomes. The net result of hitting both targets - the mechanism tirzepatide validated - is a large, sustained calorie deficit and substantial weight loss, along with better blood sugar control. HRS9531 is formulated for once-weekly subcutaneous injection and is being developed for both obesity and type 2 diabetes. ## GEMINI-1: about 17-19% weight loss at 48 weeks The pivotal study, GEMINI-1 (also called HRS9531-301; NCT06396429), was a multi-center, randomized, double-blind, placebo-controlled Phase 3 trial in China. It enrolled 567 adults (531 completed) with obesity (BMI at or above 28) or overweight (BMI at or above 24) plus at least one weight-related comorbidity, and without type 2 diabetes. Participants were randomized equally to once-weekly HRS9531 at 2 mg, 4 mg, or 6 mg, or to placebo, for 48 weeks. The trial met both co-primary endpoints. Under the per-protocol (hypothetical) estimand, mean weight loss was about 11.2% at 2 mg, 17.4% at 4 mg, and 19.2% at 6 mg, versus roughly 1.4% for placebo; under the more conservative treatment-policy estimand the figures were about 10.7%, 16.4%, and 17.7% (around 16.3% placebo-adjusted at the top dose). Importantly, weight loss had not plateaued by week 48. ## The responder numbers: most patients lost meaningful weight Beyond the averages, the responder rates tell the practical story. Between about 68% and 88% of treated participants lost at least 5% of their body weight - the threshold generally considered clinically meaningful - and about 44.4% of those on the 6 mg dose lost at least 20%. Treatment also improved a broad set of cardiometabolic risk factors, including blood pressure, lipids, measures of insulin resistance, and high-sensitivity C-reactive protein (hsCRP), a marker of inflammation. That combination - large weight loss plus improvements across the metabolic panel - is the signature benefit of the incretin class. ## Phase 2 hinted at even more at a higher dose GEMINI-1 tested doses up to 6 mg, but an earlier Phase 2 study (NCT06054698) had already pushed to 8 mg. In that trial, HRS9531 produced about 23.6% mean weight loss (roughly 21.7% placebo-adjusted) by week 36 - again with no plateau. That result is a large part of why Kailera's global program is now evaluating higher maintenance doses. If weight loss keeps climbing at 8 mg and above over longer durations, dual agonism may reach territory once associated with triple agonists or metabolic surgery. ## How it compares with tirzepatide (with the usual caveats) HRS9531's numbers land in a competitive range next to tirzepatide, which achieved about 20.9% weight loss at 36 weeks in its SURMOUNT program. But these are cross-trial comparisons, not head-to-head studies: the populations (GEMINI-1 was China-only), doses, durations, and statistical estimands all differ, so any ranking is approximate. The honest read is that HRS9531 has demonstrated tirzepatide-class efficacy in its own Phase 3 trial - a meaningful bar to clear - while a direct comparison would require a dedicated trial that has not been run. ## Tolerability: familiar GI side effects, very few dropouts Safety and tolerability were consistent with the GLP-1/incretin class. Most treatment-emergent adverse events were mild to moderate and gastrointestinal - nausea, vomiting, and diarrhea - the same effects seen with semaglutide and tirzepatide, usually dose-related and most common during dose escalation. Encouragingly, permanent discontinuations due to adverse events were very low: 0.7% at 2 mg, 0.7% at 4 mg, 1.4% at 6 mg, and 0% for placebo. More than 2,000 patients have now been dosed with HRS9531 across Phase 1, 2, and 3 studies in China, building a substantial early safety database - though long-term and non-Chinese population data are still needed. ## The Hengrui-Kailera partnership and a China-to-global trend HRS9531 is also a landmark business story. Hengrui developed the drug independently in China and then licensed ex-Greater China rights to Kailera Therapeutics, a Waltham, Massachusetts-based biotech launched specifically to bring Chinese-developed incretin drugs to global markets. Kailera is advancing the injectable as KAI-9531, its lead program, alongside an oral small-molecule GLP-1, KAI-7535 (Hengrui's HRS-7535). The arrangement is emblematic of a broader shift: a growing share of the obesity pipeline now originates in China and reaches Western patients through licensing deals, diversifying an area long dominated by Novo Nordisk and Eli Lilly. ## What happens next: China filing and a global Phase 3 program On the strength of GEMINI-1, Hengrui submitted a marketing authorization application to China's National Medical Products Administration (NMPA) for chronic weight management, and it has been accepted. Meanwhile, Kailera began a global Phase 3 program for KAI-9531 around the end of 2025, built as three trials: one in adults with a BMI above 30 (or above 27 with a comorbidity) without type 2 diabetes, one in adults with a BMI above 27 and type 2 diabetes, and one in adults with a BMI above 35 without type 2 diabetes. These studies are testing higher maintenance doses (8 mg and 10 mg) and at least 52 weeks of maintenance dosing - the data that will determine whether KAI-9531 can compete globally on both efficacy and durability. ## The bottom line HRS9531 (KAI-9531) is an investigational once-weekly injectable dual GLP-1/GIP receptor agonist that has shown tirzepatide-class weight loss - about 17-19% at 48 weeks, with higher doses still climbing - and a class-typical, mostly gastrointestinal safety profile in Phase 3 in China. It is under regulatory review in China and in early global Phase 3 development, but it is not approved anywhere and is not a supplement or research chemical; any product sold under these names outside a clinical trial is unverified. Its importance is twofold: it strengthens the case that dual incretin agonism can be reproduced and perhaps extended by new entrants, and it exemplifies how Chinese-originated obesity drugs are going global. Decisions about weight or metabolic treatment should be made with a qualified clinician using approved therapies. Ready to track your peptide research? Open PepTracker Pro (https://app.peptrackerpro.com/) PepTracker Pro Research Team The PepTracker Pro Research Team is an editorial group of science writers, pharmacologists, and clinical researchers dedicated to making peptide science accessible. Every article is reviewed for accuracy against peer-reviewed sources and updated as new evidence emerges. ## Citations 1. [1] Hengrui Pharma and Kailera Therapeutics Report Positive Topline Data from Phase 3 Obesity Trial in China of Dual GLP-1/GIP Receptor Agonist HRS9531 - Kailera (July 15, 2025) Source (https://www.kailera.com/press-release/hengrui-pharma-and-kailera-therapeutics-report-positive-topline-data-from-phase-3-obesity-trial-in-china-of-dual-glp-1-gip-receptor-agonist-hrs9531/) 2. [2] Hengrui Pharma and Kailera Therapeutics Announce Additional Data from Phase 3 Obesity Trial in China of Dual GLP-1/GIP Receptor Agonist HRS9531 - BioSpace (November 4, 2025) Source (https://www.biospace.com/press-releases/hengrui-pharma-and-kailera-therapeutics-announce-additional-data-from-phase-3-obesity-trial-in-china-of-dual-glp-1-gip-receptor-agonist-hrs9531) 3. [3] Hengrui's GLP-1/GIP agonist reports 18% weight loss in phase 3 trial, readies China push - Fierce Biotech (July 15, 2025) Source (https://www.fiercebiotech.com/biotech/hengruis-glp-1gip-agonist-reports-18-weight-loss-phase-3-trial-readies-china-push) 4. [4] GEMINI-1: A Study of HRS9531 Injection in Participants With Obesity or Overweight - ClinicalTrials.gov (NCT06396429) Source (https://clinicaltrials.gov/study/NCT06396429) 5. [5] Hengrui and Kailera report positive data from Phase III obesity treatment trial - Clinical Trials Arena (2025) Source (https://www.clinicaltrialsarena.com/news/hengrui-kailera-obesity-treatment/) 6. [6] A Study of HRS9531 Injection in Adults With Overweight or Obesity (Phase 2) - ClinicalTrials.gov (NCT06054698) Source (https://clinicaltrials.gov/study/NCT06054698) **Disclaimer:** This article is for educational purposes only and does not constitute medical advice. Always consult a licensed healthcare provider. 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