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New Drug Zometa Treats Complication of Breast Cancer, Seeking FDA Approval for Breast Cancer That Has Spread to Bone (dateline August 28, 2001)

The drug Zometa (brand name, zoledronic acid) recently received approval by the U.S. Food and Drug Administration (FDA) to treat elevated calcium levels (hypercalcemia of malignancy, HCM). HCM is a complication that can occur in cancer patients, including those with advanced breast cancer whose cancer has spread past the breast and lymph nodes to the bone. The FDA is also considering approving market authorization of Zometa to treat bone metastases (cancer that has spread to the bone) in patients with breast cancer and other cancers. Clinical trials of Zometa show that it may be more effective than the drug Aredia, the standard treatment for bone metastases.

When breast cancer spreads past the breast and axillary (armpit) lymph nodes, it often spreads first to the bone. These breast cancer tumors in the bone are called "bone metastases." As advanced breast cancer dissolves portions of bone, a variety of problems can occur. Bone metastases can cause pain, decreased physical activity, and potentially severe problems such as fractures. Other complications that can arise from bone metastases include the surgical treatment for fractures, HCM, and spinal cord compression (vertebral damage due to pressure on the spinal cord).

Zometa belongs to a class of drugs called bisphosphonates and has shown promise in treating complications from bone metastases. In particular, Zometa has received FDA approval to treat HCM, a condition that affects approximately 10% of cancer patients. HCM results when cancer cells over-stimulate bone-destroying cells called osteoclasts. In turn, the osteoclasts accelerate the breakdown of bone, which contributes to abnormally high levels of calcium in the blood that can overload the kidneys. HCM most often occurs in patients with breast cancer, lung cancer, and multiple myeloma (a type of blood cancer). Early diagnosis and treatment of HCM greatly improves the chances of survival.

In clinical trials prior to FDA approval, Zometa was shown to correct high calcium levels associated with HCM faster than Aredia, another drug used to treat HCM. Patients who were given Zometa also experienced longer periods before relapse than those who received Aredia (30 days for Zometa versus 17 days for Aredia). Zometa can be given during a 15-minute infusion time versus an infusion time of two to 24 hours that is necessary with Aredia.

In addition to treating high calcium levels (HCM), Zometa may soon be available as a treatment for several cancers that have spread to the bone, including breast, prostate, lung, and multiple myeloma. Data from three clinical trials involving more than 3,000 patients have shown that Zometa is effective at preventing or delaying complications such as bone fractures, compression of the spinal cord, and severe bone pain. Aredia is currently used to treat bone metastases in patients with breast cancer or multiple myeloma. However, it is not FDA approved for use in patients with cancers of the prostate, lung, or other solid tumors. Both Zometa and Aredia are manufactured by Novartis.

Possible side effects of Zometa for HCM may include:

  • Fever
  • Chills
  • Bone pain
  • Muscle or joint pain (myalgia/arthralygia)
  • Nausea or vomiting

According to an expert panel of the American Society of Clinical Oncology (ASCO), bisphosphonates (such as Zometa and Aredia) have shown benefits in reducing bone complications. However, bisphosphonates have not had an impact on patient survival (i.e., advanced cancer patients do not live longer if they take bisphosphonates). Thus, bisphosphonates are used to improve a patient’s quality of life rather than cure the disease. While bisphosphonates can be helpful, the ASCO believes they should not replace current standards of treatment for cancer pain due to bone metastases, such as local radiation therapy and other medications.

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