A Single- and Multiple-Ascending Dose Study of SRK-439 in Healthy Adults

Key Inclusion Criteria:

• Male or female participants, ≥18 to ≤55 years of age, at the time of informed consent
• BMI of ≥18 kg/m2 to ≤35 kg/m2 (inclusive) at screening

Exclusion criteria

• Previous treatment with SRK-439 or apitegromab, or with other anti-myostatin therapies, including ACTR antagonists.
• History of immunosuppressive, chemotherapeutic, or radiation treatment within 12 months prior to screening.
• Current or prior use of anabolic steroids, growth hormones, or other substances with known effects on muscle.
• Use of therapies with potentially significant muscle effects (eg, insulin-like growth factor, systemic beta-agonist, neurotoxins, or muscle relaxants or muscle-enhancing supplements) in any form within 3 months prior to screening or during the study.
• Any history of exposure to a mAb or Fc domain-bearing recombinant protein within 5 years prior to screening with any prior history of hypersensitivity reactions from exposure
• Treatment with other investigational drugs or devices in a clinical study or exposure to a biologic therapeutic within 3 months or 5 half-lives, whichever is longer, prior to screening.