This study has been designed as a randomized, double-blind, single-dose, parallel-group study in healthy adult male subjects 28 years to 55 years old. The study will assess the PK, PD, safety, tolerability and immunogenicity of AVT03 compared to Prolia when administered as a single SC dose.

The study will consist of a 4 week screening period, a 252 day (36 weeks) treatment and assessment period, and an End of Study (EOS) visit on week 36 on Day 252. Subjects will undertake a screening visit between Day -28 and Day -1 to determine their eligibility for the study. On Day 1, eligible subjects will be randomized and will receive a single dose of AVT03 or Prolia as subcutaneous injection.

Inclusion Criteria:

• Male subjects who are 28 to 55 years old, inclusive
• Have a body weight of 50.0 to 90.0 kg (inclusive) and body mass index (BMI) of 17.0 to 32.0 kg/m2 (inclusive)at Screening and Day -1
• Medical history without evidence of a clinically significant disorder, condition, or disease that, in the opinion of the Investigator, would pose a risk to subject safety

Exclusion Criteria:

• Any evidence of clinically relevant pathology, especially prior diagnosis of bone disease, or any uncontrolled condition that will affect bone metabolism (such as, but not limited to osteoporosis, osteogenesis imperfecta, hyperparathyroidism, hyperthyroidism, hypothyroidism, osteomalacia, rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, current flare-up of osteoarthritis and/or gout, active malignancy, renal disease, Paget's disease of the bone, recent bone fracture [within 6 months], and malabsorption syndrome)
• Have osteonecrosis of the jaw (ONJ) or risk factors for ONJ such as invasive dental procedures (eg, tooth extraction, dental implants, oral surgery) within 6 months prior to Day 1 or intend to undergo such procedures during the study period, poor oral hygiene, periodontal, and/or pre existing dental disease
• Have bone fractures within 6 months prior to Day -1.
• Have a history of immunodeficiency
• Those with skin allergies, or are susceptible to autoinflammatory skin disorders, or prone to the development of allergic skin inflammation
• Abnormal serum calcium: current hypocalcemia or hypercalcemia at Screening. Serum calcium levels must be within reference ranges.
• Known vitamin D deficiency

Double Blind