A VLP-based immunogen that elicits selective anti-Myostatin antibodies, enhances muscle mass and strength, and reduces adiposity

Myostatin (MSTN) is a TGF{beta} family ligand that restricts muscle growth. Genetic loss-of-function in MSTN increases muscle mass, reduces fat accumulation, and improves metabolic health in mice and humans, with no known adverse phenotypes. Thus, depleting MSTN has therapeutic potential for obesity, sarcopenia, and other muscle wasting conditions. Recently developed monoclonal antibodies (mAbs) targeting MSTN or its receptors are expensive, require frequent injections/infusions, and risk a loss of efficacy from the development of anti-drug antibodies. Here, we report a comparatively inexpensive and durable alternative to mAbs, a virus-like particle (VLP)-based active immunotherapy, termed "MS2.87-97", that elicits an antibody response against a discrete and unique epitope in mature MSTN protein, with no cross-reactivity to GDF11. Compared to controls, MS2.87-97-treated mice had less age-associated weight gain and exhibited significantly reduced body fat by DEXA scan. MS2.87-97-treated mice also had significantly improved bodyweight-adjusted grip strength, and upon dissection, they were found to have increased muscle mass. No major safety concerns were identified. Echocardiography revealed no evidence of functional impairment of the heart, and histological analysis showed no change in myocardial collagen deposition (fibrosis). These initial findings support the continued preclinical development of MS2.87-97 as an immunotherapeutic for treating obesity, sarcopenia, and muscle wasting.