FALLS CHURCH, Va. — Response Pharmaceuticals reported positive 36-week Phase 2 data supporting its investigational therapy RDX-002 as a potential long-term option for maintaining weight loss after patients discontinue GLP-1 receptor agonist treatments.
The clinical-stage biopharmaceutical company said results from an open-label extension study suggest the therapy may help preserve weight loss and support long-term metabolic health in patients who stop GLP-1–based obesity medications.
“Obesity is increasingly recognized as a chronic, relapsing disease associated with significant, cumulative cardiometabolic risk and long-term morbidity and mortality,” said Professor Chris Packard of the Institute of Cardiovascular and Medical Sciences at the University of Glasgow. “Weight loss reduces cardiometabolic risk factors but has to be maintained to gain full benefit. There is a clear need for durable management strategies that maintain weight loss and the associated cardiometabolic treatment benefits over the long term.”
The Phase 2 study evaluated patients who had recently discontinued GLP-1 receptor agonists used for weight loss. Researchers found that patients treated with RDX-002 preserved an average of 57 percent of the weight loss achieved during prior GLP-1 therapy at 36 weeks.
“In a therapeutic landscape where tolerability and high discontinuation rates continue to limit long-term body weight management, these data position RDX-002 as a differentiated and potentially durable solution for chronic obesity management and care,” said Dr. William Sasiela, Chief Medical Officer of Response Pharmaceuticals. “While GLP-1 agonists are highly effective at reducing weight, 65 percent of patients discontinue GLP-1 agonist treatment within one year of starting according to a recent NIH cohort study of over 125,000 patients, with an average weight regain of 67 percent over 52 weeks. In practice, this often means that weight loss and initial cardiometabolic improvements are difficult to sustain, which poses clinical challenges for patients and healthcare providers.”
The study enrolled 68 participants following their planned discontinuation of GLP-1 therapy for weight management. It included a 12-week randomized, double-blind, placebo-controlled phase followed by a 24-week open-label extension period.
During the randomized portion of the study, the therapy met its primary endpoint by significantly reducing the postprandial triglyceride response to a standardized high-fat meal compared with placebo. Researchers also observed sustained benefits in weight maintenance during the extension phase.
Participants who initially received placebo but later switched to RDX-002 during the open-label extension also showed a reduced rate of weight regain. According to the company, the rate of weight regain fell from 0.58 percent per week to 0.14 percent per week after switching treatments.
Additional findings showed less total body fat gain among patients treated with RDX-002 compared with placebo over the first 12 weeks of treatment. Improvements were also observed in blood pressure and levels of high-sensitivity C-reactive protein.
RDX-002 was generally well tolerated in the study. The most common adverse events included mild or moderate diarrhea, upper respiratory tract infection, nausea and abdominal pain. One patient in each of the RDX-002 and placebo groups discontinued treatment due to an adverse event, and no serious adverse events were reported among patients receiving the investigational therapy.
Response Pharmaceuticals said the therapy’s gut-restricted mechanism is designed to minimize systemic exposure while maintaining metabolic benefits. The company believes the approach could address a growing need in obesity care as clinicians seek strategies to prevent weight regain after discontinuation of GLP-1 therapies such as Wegovy and Zepbound.
