Scholar Rock’s SMA drug helps Zepbound patients retain muscle in phase 2 trial

Scholar Rock's investigational SMA drug, apitegromab, significantly helped patients taking Eli Lilly’s Zepbound (tirzepatide) retain muscle mass during weight loss in a phase 2 clinical trial134.

In obese patients treated with tirzepatide alone, 30.2% of the total weight lost was lean mass, compared to only 14.6% in those who also received apitegromab, effectively halving the proportion of muscle lost over 24 weeks1.

The fat to lean mass loss ratio improved with the combination:
patients on both drugs lost 85% fat and 15% lean mass, versus 70% fat and 30% lean mass in those on tirzepatide and placebo1.

Patients receiving apitegromab with tirzepatide preserved a significant amount of lean mass (+4.2 lbs), representing a 54.9% preservation rate over the 24-week period2.

Total weight loss was comparable between groups (12.3% for apitegromab-tirzepatide vs 13.4% for tirzepatide-placebo), suggesting the combination optimizes weight quality without reducing efficacy1.

The FDA is reviewing apitegromab for SMA, but these findings suggest broader use in obesity and metabolic health1.

Sources:

1. https://www.fiercebiotech.com/biotech/scholar-rocks-sma-drug-helps-patients-zepbound-retain-muscle-phase-2-trial

2. https://investors.scholarrock.com/news-releases/news-release-details/scholar-rock-reports-positive-phase-2-embraze-trial-results

3. https://firstwordpharma.com/story/5973730

4. https://www.biopharmadive.com/news/scholar-rock-apitegromab-obesity-muscle-results/751016/