Scholar Rock drug preserves muscle in obesity trial

Scholar Rock drug preserves muscle in obesity trial

By, Admin 20 June 2025

While the results were an important proof point for so-called anti-myostatin drugs, Scholar Rock executives indicated the company may look for a partner in obesity while focusing on rare diseases. 

Dive Brief:

  • A medicine developed to treat a genetic muscle-wasting disease can improve results for patients taking GLP-1 weight-loss medicines, according to a new Phase 2 study.
  • Scholar Rock has already applied for Food and Drug Administration approval of the drug, dubbed apitegromab, for patients with spinal muscular atrophy based on a Phase 3 trial that showed it could preserve muscle and improve motor function for patients with the genetic condition. The company expects to receive an answer on its submission by Sept. 22.
  • The new Embraze trial compared the effects of apitegromab with a placebo in patients taking tirzepatide, the active ingredient in Eli Lilly’s obesity drug Zepbound. The weight loss in patients who received apitegromab was 85% from fat and 15% from lean mass, compared with 70% fat and 30% from lean mass for those who got a placebo, Scholar Rock said Wednesday.

Dive Insight:

  • The results suggest the medicine could help certain patients taking the immensely popular GLP-1 drugs, which can spur both rapid weight loss and shrink muscle mass. 
  • A number of different companies are looking at ways to address that issue because of its ramifications for future weight gain, overall metabolism and frailty, particularly among older people.

The Race to Boost Muscle Growth: Targeting Myostatin and Beyond

  • Scholar Rock, Roche, Regeneron, and Biohaven are developing therapies that inhibit myostatin, a protein that naturally limits muscle growth.
  • These approaches are being explored in conditions like SMA, muscular dystrophies, and obesity-related muscle loss.
  • Veru reported positive results with its experimental drug enobosarm, which takes a different route as a SARM (Selective Androgen Receptor Modulator) to support muscle growth.
  • The field remains competitive but challenging—BioAge Labs experienced setbacks, reflecting the complexities in translating muscle-targeting therapies into clinical success.

Scholar Rock’s Strategic Shift Following Embraze Study Results

  • Shares surged 15% after the release of positive data from the Embraze Phase 2 trial, which evaluated apitegromab in combination with tirzepatide for preserving lean mass during weight loss.
  • Despite the success, Scholar Rock is not immediately pursuing obesity as a core focus.
  • The company is exploring partnerships to advance apitegromab or its follow-on candidate SRK-439 in the obesity space.
  • Executives emphasized their continued commitment to neuromuscular diseases, particularly spinal muscular atrophy (SMA) and other severe conditions.
  • CEO David Hallal noted that obesity-focused development may be better suited to companies with deep cardiometabolic expertise, while Scholar Rock remains disciplined in its rare disease mission.

Words from the CEO: Scholar Rock

We love the results that we see today, but we think that this is an undertaking that may be better placed with those companies a little bit more focused on the cardiometabolic and obesity space,” CEO David Hallal said on the conference call. “We really want to stay disciplined here.”

Scholar Rock’s Muscle-Preserving Therapy in Obesity

  • Add-on therapies like apitegromab may appeal to only 5%–10% of patients, according to RBC Capital Markets analyst Leonid Timashev.
  • The primary niche is expected to be older adults at risk of frailty and falls due to muscle mass loss during weight reduction.
  • Scholar Rock’s Embraze trial met the critical requirement of a clean safety profile:

No serious adverse events were reported.

Adverse events were similar between the apitegromab and placebo groups.

  • These findings support the potential for selective use of myostatin inhibitors in vulnerable populations undergoing GLP-1–induced weight loss.

Side effects

No serious side effects were observed in the study, and adverse events were generally similar between the patients who randomly received placebo and those who got apitegromab, Scholar Rock said.

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