Actimed Therapeutics has finished enrolling patients in its PROACT Phase 2a study, setting up a near-term readout on whether S-pindolol benzoate (ACM 001.1) can do something GLP-1 drugs do not: preserve muscle while fat comes off. That gap is the trial’s entire rationale. Semaglutide and other approved weight-management agents drive substantial weight loss, but a meaningful share of the weight lost is lean mass, not fat, and completing recruitment means Actimed now has the patient population to test that problem directly.
PROACT is a two-part, randomized, double-blind, placebo-controlled design. Part one runs ACM 001.1 alongside active semaglutide therapy; part two studies patients who have already discontinued it. That second arm is the commercially interesting one. Weight regain after stopping GLP-1 therapy is well documented, and the muscle-loss component of that rebound is poorly addressed. If S-pindolol benzoate blunts catabolism and supports lean mass through both windows, Actimed has a clinical story that reaches patients on-drug and patients who cycle off.
The mechanism behind ACM 001.1 is worth tracking because it is not a receptor agonist layered on top of semaglutide. Preclinical and early-stage work shows S-pindolol acts as an anti-catabolic, pro-anabolic agent: nonselective beta-blockade reduces muscle breakdown while partial beta-2 agonism promotes anabolic signaling. The compound was originally developed in cancer cachexia, which is a harder muscle-wasting context than GLP-1-induced lean mass loss, so the biology at least translates directionally. Whether it does so at a clinically meaningful scale in obese adults is what PROACT is built to answer.
The GLP-1 obesity market has expanded fast since Wegovy’s 2021 FDA approval, and the number of patients cycling on and off these agents will only grow as access broadens. The PROACT readout will be the first real signal on whether a muscle-preservation adjunct can hold up to a controlled trial, and the post-discontinuation arm will be the number to watch.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
