Ractigen's saRNA Candidate LiCO-saUcp1 Demonstrates High-Quality Weight Loss Without Muscle Wasting or Rebound in Preclinical Obesity Models
Key Insights
Ractigen Therapeutics' first-in-class saRNA therapy LiCO-saUcp1 (search) reduced fat mass by 45% in diet-induced obese mice while fully preserving lean muscle mass, unlike semaglutide which caused 19% lean mass loss.
Treated animals sustained a 46% fat mass reduction for two months after drug withdrawal, eliminating the rapid weight rebound typically seen with incretin therapies.
When combined with semaglutide, LiCO-saUcp1 (search) synergistically achieved a 69% reduction in fat mass without worsening GLP-1-associated muscle depletion.
Ractigen Therapeutics announced today that a late-breaking abstract on LiCO-saUcp1 (search), its first-in-class small activating RNA (saRNA) candidate for obesity (search), has been accepted for poster presentation at the American Diabetes Association (ADA) 86th Scientific Sessions in New Orleans. The preclinical data reveal a potentially transformative approach to obesity treatment—one that drives profound fat loss while preserving lean muscle mass and preventing the rapid weight regain that plagues current incretin-based therapies.
The findings arrive at a critical juncture for the obesity (search) field. While GLP-1 receptor agonists such as semaglutide have revolutionized weight management, they are increasingly associated with two significant drawbacks: the loss of lean muscle mass and rapid weight rebound upon treatment discontinuation. Ractigen's data suggest that saRNA technology may directly address both challenges by activating a fundamentally different biological mechanism.
A New Mechanism: Turning on the Thermogenic Switch
LiCO-saUcp1 (search) leverages Ractigen's proprietary Lipid-Conjugated Oligonucleotide (LiCO™) delivery platform to target and upregulate the Ucp1 (search) gene—a master driver of metabolic thermogenesis that has long been considered "undruggable" by conventional small-molecule or antibody-based pharmaceuticals. By activating Ucp1 expression, the therapy effectively converts white adipose tissue into calorie-burning brown fat, harnessing the body's own energy-expenditure machinery.
"The obesity (search) market is urgently looking for the 'next generation' of therapeutics that go beyond simply suppressing appetite," said Long-Cheng Li, MD, Founder and Chief Executive Officer of Ractigen Therapeutics. "saRNA opens an entirely new frontier in obesity control. By activating the body's own thermogenic switch, we are changing the fundamental composition of weight loss."
Head-to-Head Data Against Standard of Care
In diet-induced obesity (search) (DIO) models, LiCO-saUcp1 (search) slashed fat mass by 45% while completely preserving lean muscle mass. In a direct comparison, semaglutide—the current standard of care—caused a detrimental 19% loss in lean mass. This stark contrast underscores what Ractigen terms "high-quality weight loss": the selective elimination of adipose tissue without sacrificing metabolically active muscle.
The durability data were equally striking. Animals treated with LiCO-saUcp1 (search) maintained their body weight and sustained a 46% fat mass loss for two full months after the drug was withdrawn. This stands in sharp contrast to the rapid weight regain observed upon semaglutide withdrawal, suggesting that saRNA-mediated Ucp1 (search) activation may reprogram metabolic set points rather than merely suppressing appetite transiently.
Synergy with Incretin Therapies
Perhaps most compelling for the future treatment landscape, LiCO-saUcp1 (search) demonstrated best-in-class synergy when combined with semaglutide. The combination drove a remarkable 69% reduction in fat mass, compared to 47% with semaglutide alone—and critically, this enhanced efficacy did not worsen the muscle depletion typically caused by GLP-1 receptor agonists. This positions LiCO-saUcp1 as both a potential standalone therapy and an ideal combination partner for existing incretin-based regimens.
Liver Health Benefits
Beyond adipose-specific effects, LiCO-saUcp1 (search) demonstrated significant metabolic benefits in the liver. The therapy dose-dependently reduced liver triglycerides by up to 79%, indicating deep resolution of hepatic steatosis (search), or fatty liver disease—a common comorbidity in obesity (search) that currently lacks robust pharmacologic treatment options.
Presentation and Next Steps
The abstract, titled "Activating the Adipose Thermogenic Switch: A First-in-Class Ucp1 (search) saRNA Drives Durable, High-Quality Weight Loss in Diet-Induced Obese Mice," will be presented by Moorim Kang, PhD, Chief Technology Officer of Ractigen Therapeutics, on Sunday, June 7, 2026, at the Ernest N. Morial Convention Center in New Orleans (Poster Number: 3066-LB).
Ractigen Therapeutics is a clinical-stage biopharmaceutical company focused on next-generation RNA therapeutics built on its clinically validated RNA activation (RNAa) platform. Beyond obesity (search), the company is advancing a pipeline addressing unmet needs in oncology, neurological diseases, and genetic disorders, leveraging additional proprietary delivery platforms including SCAD™ and GLORY™.