Osteonecrosis (ON) happens when blood flow to the bone is reduced or blocked. This causes bone cells to die, leading to changes in the bone's structure and collapse. Patients may feel hip pain and have trouble moving. ON is often caused by long-term steroid use or drinking too much alcohol. It can affect many joints, but hip joint damage (ONFH) is the most common type. ON is hard to treat and often seen in orthopedic clinics.

ONFH mostly affects people aged 30–59. Recent studies show there are over 30 million ONFH cases worldwide, with about 10 million in China. Each year, 300,000 to 500,000 new cases are added [1].

In 2003, steroids were widely used to treat SARS, causing ONFH in some patients and leading to high disability rates. Since 2020, steroids have also been used for severe COVID-19 patients, raising their risk of ON. Preventing and treating steroid-related ON is important to reduce long-term problems after COVID-19.

Currently, no effective drugs exist for ON globally. Surgery (like artificial joint replacement) is common, but it causes large wounds, side effects, slow recovery, and high costs. A new drug treatment would help fill this gap.

Rabpharma is developing RAB001, a new bone-targeting drug. It activates the body’s own mesenchymal stem cells (MSCs) and sends them to bones and joints. It also turns on bone-building cells, helps form new bone, improves blood flow to bone, and reduces swelling in damaged areas—helping bone regrow. Given as a monthly shot, RAB001 is safe, works well, and has few side effects. It treats hip bone damage (main focus), broken bone healing, jawbone repair, bone loss (osteoporosis), and joint swelling (e.g., rheumatoid arthritis).

Ref：【1】Meng K, Liu Y, Ruan L, et al. Suppression of apoptosis in osteocytes, the potential way of natural medicine in the treatment of osteonecrosis of the femoral head[J]. Biomedicine & Pharmacotherapy, 2023, 162: 114403.