Ascletis Pharma on Sunday reported encouraging top-line results from an early-stage study of its ultra-long-acting, muscle-preserving THRβ agonist ASC47 in combination with Novo Nordisk’s GLP-1 agonist semaglutide — marketed as Ozempic or Wegovy — demonstrating significant weight reduction relative to semaglutide monotherapy.The Phase I ASC47-103 trial randomised 28 participants with obesity in the US to receive one of three doses of ASC47 administered as a single-dose subcutaneous depot, or placebo, alongside once-weekly semaglutide 0.5 mg over a four-week treatment period.Results showed that on day 29, a single 30-mg dose of ASC47 plus semaglutide led to a 56.2% greater relative reduction in body weight versus placebo plus semaglutide, while the 60-mg combination achieved a 15.1% greater reduction; relative weight reduction with the lowest 10-mg dose was insignificant. Moreover, in pooled analysis, the ASC47 combination regimen demonstrated a 31.6% greater relative reduction compared with semaglutide monotherapy.Notably, ASC47’s ultra-long-acting depot showed a half-life of up to 30 days, cutting the likelihood of weight rebound after discontinuation. At day 57, the 30-mg and 60-mg groups maintained 157.1% and 110.4% greater weight reductions, respectively versus semaglutide, while the pooled cohort showed a 129.9% greater reduction.On the safety front, the combination showed superior gastrointestinal (GI) tolerability than semaglutide monotherapy, the incidence of vomiting being 6.7% and 57.1%, respectively. Additionally, all thyroid function parameters remained within normal limits, with no thyroid-related adverse events reported.“We're very encouraged that the addition of…an adipose-targeting THRβ agonist, to an incretin regimen led to a significant synergy in terms of body weight reduction,...and a substantial improvement in GI tolerability," said Jinzi Jason Wu, chief executive of Ascletis.The Hong Kong-based biotech noted that forthcoming Phase IIb studies may test once-monthly ASC47 with GLP-1R/GIPR agonist ASC35, and an oral ASC47 formulation with once-daily oral ASC30 — which earlier this year delivered up to 6.5% placebo-adjusted weight loss in a Phase Ib study.