It is estimated that prostate cancer will affect one in every eight Canadian men at some point in their lives. With an estimated 18,200 new cases this year, prostate cancer is the most frequently occurring of all cancers among Canadian men.
If prostate cancer progresses to the advanced stage, the cancer can spread, or metastasize, to the bone resulting in severe bone pain, fractures, and even spinal cord compression, all of which can seriously impact a patient’s quality of life. In fact, for 75 per cent of advanced prostate cancer patients, the complications of bone metastases are a constant, painful reminder of their struggle with this disease.
With Health Canada’s approval of Zometa* (zoledronic acid for injection), for use in bone metastases due to prostate cancer, patients now have access to a treatment that can ease their pain and maintain their quality of life. Before the approval of Zometa* there was no effective treatment that specifically targeted the bone metastases resulting from prostate cancer.
The trial that led to the approval of Zometa*, and which was recently published in the Journal of the National Cancer Institute, involved 643 prostate cancer patients with a history of metastatic bone disease. The trial marks the first time any drug has demonstrated efficacy in preventing skeletal-related events (SRE’s) in patients with prostate cancer. SRE’s were defined as bone fractures, spinal cord compression or the need for radiotherapy, surgery or chemotherapy to treat bone complications.
Patients in the trial were given either a 15-minute infusion of Zometa*, or a placebo every three weeks for a period of 15 months. Results using zoledronic acid 4 mg showed that by the end of the trial, 25 per cent fewer patients experienced any skeletal-related events, compared to those taking placebo. It was also shown that Zometa* significantly delayed the time to the first skeletal-related event, and patients taking Zometa* experienced less bone pain than those taking placebo.
The results of the clinical trial are highly significant as they show that patients required significantly less therapy for bone complications and therefore their ability to be active was extended through treatment with Zometa*. For patients with advanced disease, this is an important addition to the limited options available to treat this potentially painful complication.
Zometa* belongs to a class of drugs called bisphosphonates which are often referred to as ‘bone builders’. Zometa* is the most powerful drug in this class of medications, and works in two distinct ways. Zometa* stops bones from weakening by inhibiting a process called resorption, and helps stabilize bone metabolism to keep bones strong.
In the clinical trial, Zometa* was generally well tolerated, with a safety profile similar to other bisphosphonates. Reported adverse events were slightly higher in the Zometa* treatment group. Commonly reported adverse experiences included nausea, fatigue, anemia, myalgia, and pyrexia which were well tolerated by patients and rarely led to stopping the medication. Given a 15-minute infusion (4 mg) there was no difference in renal function deterioration compared to placebo.
Zometa* was previously approved in Canada for the treatment of hypercalcemia of malignancy (HCM), also known as tumor-induced hypercalcemia (TIH), in August 2000.
Now, with the approval of Zometa* for the treatment of bone metastases in prostate cancer, patients and their physicians, for the first time, have access to a medication that specifically targets the bone metastases resulting from prostate cancer.