Among men with prostate cancer that has stopped responding to hormonal therapy, the bone drug Xgeva™ (denosumab) delayed the spread of cancer to the bones. These results were recently published in The Lancet, and were previously presented at the 2011 European Multidisciplinary Cancer Conference.

Androgen deprivation therapy (ADT) often plays an important role in the treatment of prostate cancer. ADT slows or stops prostate cancer growth by reducing the exposure of the prostate to testosterone. Eventually, however, prostate cancer can become resistant to ADT. This is known as hormone-refractory prostate cancer.

Xgeva is a bone drug that targets a protein known as the RANK ligand. This protein regulates the activity of osteoclasts (cells that break down bone). Xgeva has been approved for the prevention of bone complications such as fracture in patients with bone metastases from solid (not blood-related) cancers. Some research has suggested that Xgeva may also have anti-cancer effects in the bone. If this proves to be correct, it could provide an important benefit for patients with cancers that tend to spread to the bone, such as prostate and breast cancers.

To evaluate the effect of Xgeva on the occurrence of bone metastases, researchers conducted a Phase III clinical trial among 1,432 men with hormone-refractory prostate cancer. The men had rapidly rising prostate-specific antigen (PSA) levels and/or high PSA levels but were free of bone metastases at the start of the study. Patients received either Xgeva or a placebo.

  • Xgeva delayed the occurrence of bone metastases. Men in the Xgeva group remained alive and free of bone metastases for more than four months longer than men in the placebo group.
  • Overall survival was similar in the two study groups.
  • Side effects that were more common in the Xgeva group than in the placebo group included hypocalcemia (low levels of calcium in the blood) and osteonecrosis of the jaw (death of bone in the jaw).

These results suggest that in addition to reducing the risk of complications from bone metastases, Xgeva may also delay the development of bone metastases in high-risk patients.

Reference: Smith MR, Saad F, Coleman R et al. Denosumab and bone-metastasis-free survival in men with castration-resistant prostate cancer: results of a phase 3, randomised, placebo-controlled trial. Lancet. Early online publication November 16, 2011.

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