Hengrui Pharma and biotechnology startup Kailera Therapeutics announced that their experimental dual-acting obesity drug succeeded in a Phase 3 trial in China, positioning the companies to seek regulatory approval and begin global late-stage testing. The once-weekly injection, designated HRS9531, achieved approximately 18% weight loss in treated participants after 48 weeks, roughly 16% more than those receiving placebo.
Clinical Trial Results
The Phase 3 study enrolled 567 adults with obesity or who are overweight with at least one weight-related medical condition in Shanghai. Participants were randomized to receive either 2 milligram, 4 milligram, or 6 milligram weekly injections of HRS9531, or placebo, for 48 weeks.
The trial met its primary endpoint, with HRS9531 demonstrating superior weight loss across all three doses compared to placebo. Nearly 9 in 10 people given HRS9531 lost at least 5% of their body weight, and over 44% achieved at least 20% weight loss. A pre-specified analysis showed patients on the highest tested dose lost up to 19.2% of their body weight after 48 weeks.
According to the companies, the drug's effects hadn't plateaued, suggesting they could improve with extended treatment duration.
Safety Profile
The companies reported that most treatment-emergent adverse events were mild to moderate and gastrointestinal-related, consistent with GLP-1 based treatments and previously reported Phase 2 clinical data. Detailed safety data were not disclosed, with full results to be presented at a future medical meeting.
Previous Phase 2 data announced in January showed 21.1% placebo-adjusted average weight loss after 36 weeks, with adverse events described as "mild" and gastrointestinal-related events linked to dose escalation.
Regulatory and Development Plans
Hengrui will file a new drug application for chronic weight management in China based on these results. Meanwhile, Kailera will initiate global studies involving higher doses and longer treatment duration, according to CEO Ron Renaud.
"This is a huge step forward in providing innovative solutions to meet the needs of people living with obesity," said Hong Chen, head of the metabolism department at Hengrui. "Based on these robust and encouraging clinical results, we are accelerating our efforts to advance this highly promising candidate."
Mechanism and Competitive Landscape
HRS9531, like Eli Lilly's Zepbound and other drugs in clinical development, targets a pair of gut hormones called GLP-1 and GIP. Kailera CEO Renaud claims the drug has "best-in-class potential."
However, the companies have not yet proven their drug in the type of larger and longer global studies that supported Zepbound's U.S. approval. In late-stage trials enrolling more than 3,000 people with obesity or diabetes, Lilly's drug was associated with up to about 21% weight loss after 72 weeks.
Partnership Background
Kailera launched in October 2024 with $400 million in funding, representing a novel strategy of licensing drugs from China for global development. In May, the company licensed rights outside of Greater China to multiple Hengrui candidates in return for more than $100 million in upfront and near-term payments, a 20% equity stake, and nearly $6 billion in future milestones.
The drug is being advanced outside of China under the name KAI-9531. Kailera is among eight drug companies since late 2023 to turn to China in search of obesity drugs, joining established players like Merck & Co., Novo Nordisk, and Regeneron Pharmaceuticals in this strategy.
