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Adjuvant Bondronat Therapy Plays Important Role in Prevention of Bone Metastases: Presented at IBCEF

By Chris Berrie

VIENNA, AUSTRIA -- February 20, 2006 -- Due to their ability to prevent bone metastases and potentially prolong survival, the bisphosphonates are expected to have a role in future breast cancer adjuvant therapy.

Here, further benefits may also be obtained from the use of oral ibandronate (Bondronat(R)), as this appears to be at least as effective as intravenous (IV) bisphosphonates in preventing skeletal-related events, and to show a low incidence of adverse effects and no renal toxicity, with a simple once-daily dosing.

Alexander H.G. Paterson, MD, Chair, Alberto Breast Cancer Programme, Department of Medicine and Oncology, Tom Baker Cancer Centre, University of Calgary, Alberto, Canada, discussed the pros and cons of bisphosphonate use, and ibandronate in particular, in the adjuvant setting. He made his presentation here on February 11^th at the International Breast Cancer Expert Forum: Milestones in Management, Confidence and Care (IBCEF).

The clinical consequences of bone metastases are bone pain, bone fracture and disability, hypercalcaemia and spinal cord compression syndromes. The use of adjuvant bisphosphonate should help to prevent bone metastasis, reduce skeletal complications, prevent secondary metastasis, and improve overall survival and patient quality of life, Dr. Paterson said.

Specific bisphosphonate agents currently available include IV ibandronate, zoledronic acid and pamidronate, and oral ibandronate and clodronate. However, Dr. Paterson indicated that while these agents have variously demonstrated effects in a metastatic setting, their potential in the adjuvant setting remains unknown. And while IV bisphosphonates have some advantages -- such as compliance, combination with other IV chemotherapy, precise dosing and minimised gastrointestinal adverse effects -- oral administration remains an important goal.

To illustrate the possibility of this route of administration, Dr. Paterson described a recent randomised, double-blind, placebo-controlled, multicentre trial of oral clodronate 1600 mg once daily in 1069 patients with operable breast cancer. The clodronate arm showed a significant reduction in incidence of bone metastases over the placebo group both at 2 years (hazard ratio [HR], 0.546; 95% confidence interval [CI], 0.312-0.954; P = .031) and at 5 years (HR, 0.692; 95% CI, 0.484-0.990; P = .043). This carried through to a consistent benefit against bone metastases in the subgroup analyses.

Similarly, Dr. Paterson and colleagues saw a significant improvement in overall survival in all patients treated with for clodronate (HR, 0.768; 95% CI, 0.591-0.999; P = .048), and a consistent survival benefit.

In patients who did develop bone metastases, the use of oral clodronate also showed improved overall survival and reduced skeletal events. This was accompanied by no increase in toxicity compared to placebo. Indeed, clodronate use reduced the incidence of skin rashes (14.3%, vs. 20.6% for placebo; P < .001), although there was an increase in diarrhoea (16.6%, vs. 7.4%; P < .001).

In discussing the clinical data on oral ibandronate in the adjuvant setting, Dr. Paterson said it is effective in the prevention of skeletal-related events and the relief of bone pain in metastatic breast cancer patients, and it is more convenient for long-term use, since it is administered once daily in a small tablet, it does not require regular hospital visits, and has no renal safety concerns.

Dr. Paterson outlined the ongoing trials of adjuvant oral ibandronate in early breast cancer, which include Southwest Oncology Group/National Surgical Adjuvant Breast and Bowel Project (SWOG/NSABP) S0307 study, which is comparing oral ibandronate, oral clodronate and IV zoledronic acid in stage I-III breast cancer; Ibandronate With or Without Capecitabine in Elderly Patients With Early Breast Cancer (ICE); and the German Adjuvant Intergroup Node-positive (GAIN) study.

Bisphosphonates, and potentially oral ibandronate, are expected to have a role in future breast cancer adjuvant therapy, with a view to preventing bone metastases and potentially prolonging patient survival, Dr. Paterson said. The full potential of these therapies will become clear with the conclusion of ongoing studies.

The conference was sponsored by Roche.


[Presentation title: Building on Success: Adjuvant Bondronat Therapy.]

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