Pamidronate infusions as single-agent therapy for bone metastases: a phase II trial in patients with breast cancer

Pamidronate is a potent biphosphonate which modulates tumour-induced osteolysis (TIO) by inhibiting osteoclast-mediated bone resorption. In a phase II trial, 69 breast cancer patients with symptomatic progressive bone metastases were given infusions of pamidronate 60 mg over 1 or 4 h every 2 weeks for a maximum of 13 infusions or until progressive disease (PD) at any site. No other systemic anticancer therapy was allowed. Pain was measured using a visual analogue scale, mobility using a detailed eight-point questionnaire and analgesic intake using a six-point scale. Improvements in pain, mobility and analgesic scores occurred in 61, 50 and 30% of patients, respectively, with 33, 21 and 16% achieving a 40% improvement for > or = 8 weeks. At trial discontinuation, baseline levels of pain and mobility had improved by 27% (P = 0.001) and 20% (P = 0.004), respectively, despite a one category reduction in analgesic intake in 27% of patients. Using this relatively high dose of pamidronate, symptomatic response was independent of the number of bone metastases and also of infusion rate. The infusions were well tolerated with no major toxicities reported. Pamidronate infusions provide useful palliation for breast cancer patients with symptomatic bone metastases.