Researchers have identified a potential new treatment strategy for osteoporosis that could help slow age-related bone loss and improve bone formation.

Scientists are investigating a drug candidate called CADD522, which works by inhibiting a protein known as RUNX2. Early research in mice suggests that blocking RUNX2 may help protect bones from the loss of mineral density associated with aging and menopause.

Osteoporosis develops when bones become weaker and more fragile, increasing the risk of fractures. Normally, bone is continuously renewed through a balance between two types of cells: osteoblasts, which build new bone, and osteoclasts, which break down old bone. As people age, bone breakdown can begin to outpace bone formation.

Current osteoporosis treatments mainly work by slowing bone breakdown or stimulating new bone formation. However, existing options have limitations. Some long-term antiresorptive treatments have been associated with rare complications, while certain bone-building drugs require regular injections. Other treatments may not be suitable for all patients because of potential side effects or safety concerns.

Researchers became interested in RUNX2 inhibition after earlier studies of CADD522 in cancer. RUNX2 plays an important role in bone development and has also been linked to cancer progression. Unexpectedly, researchers observed that CADD522 reduced bone damage associated with cancer, prompting them to investigate whether the compound could also help prevent osteoporosis.

Promising results in mice

In a study using female mice whose ovaries had been removed to model post-menopausal bone loss, researchers treated the animals with CADD522 three times a week for eight weeks.

The treatment was associated with several potentially beneficial effects:

• Increased bone formation
• Better preservation of the internal structure of bone
• Reduced loss of bone tissue
• Lower levels of fat accumulation in bone marrow and surrounding tissues

Additional studies examining how the compound behaves in the body found that CADD522 could be taken orally and showed favorable short-term tolerability. Researchers also found evidence that the compound directly interacts with RUNX2.

More research is needed

The findings suggest that targeting RUNX2 could represent a new approach to treating osteoporosis—one that aims to strengthen bones by increasing bone-building activity rather than focusing primarily on reducing bone breakdown.

However, the research is still at the preclinical stage. The results have so far been demonstrated in animal models, and further studies will be needed to determine whether CADD522 is safe and effective in humans.

Researchers say the findings support continued development of CADD522 as a potential treatment for osteoporosis and other diseases in which RUNX2 plays a role.