医药生物-医药生物行业全球前沿创新专题报告(六)：ActR通路阻断的临床应用之增肌

Investment Rating - The report maintains a "Positive" investment rating for the industry [1] Core Insights - The report highlights the significant potential of blocking the Activin receptor (ActR) signaling pathway to promote muscle growth, particularly in treating muscle atrophy-related diseases [4][9] - There is a substantial unmet clinical need for muscle-targeted therapies, especially for patients with spinal muscular atrophy (SMA) and those experiencing muscle loss due to aging or weight management [4][29] - The market for muscle-targeted therapies is projected to be large, with current SMA therapies generating approximately $4.5 billion in sales, indicating a significant opportunity for new treatments [4][33] Summary by Sections 1. ActR Pathway - The ActR pathway plays a crucial role in regulating muscle, blood, and bone through members of the TGFβ superfamily, including Myostatin [9] - Blocking the ActR pathway can effectively treat muscle atrophy by inhibiting Myostatin, which negatively regulates muscle growth [4][10] 2. Clinical Applications of ActR Pathway Blockade: Spinal Muscular Atrophy (SMA) - SMA is a genetic neuromuscular disease caused by mutations in the SMN1 gene, leading to severe muscle atrophy and respiratory failure [22][23] - Current SMA therapies primarily target SMN protein, but they have limitations, highlighting the need for combined therapies that also address muscle atrophy [25][29] 3. Clinical Applications of ActR Pathway Blockade: Weight Management - Muscle loss is a significant issue not only in genetic diseases but also in aging populations, with a 1% annual muscle loss in individuals over 60 [36] - The widespread use of GLP-1RA medications has been linked to 25-40% muscle loss in users, creating a demand for therapies that preserve or enhance muscle mass during weight management [36] 4. Targeted ActRII Pathway Drugs - Apitegromab, developed by Scholar Rock, is a monoclonal antibody targeting latent Myostatin, showing promising results in Phase 3 trials for SMA and expected to submit for FDA approval [38][39] - Taldefgrobep, developed by BIOHAVEN, targets active Myostatin but did not meet primary endpoints in its Phase 2 trial for SMA, although it showed trends of benefit in certain subgroups [57][62] - GYM329, developed by Roche, specifically targets latent Myostatin and is currently undergoing clinical trials for various indications, demonstrating potential for muscle mass increase [69]