The bisphosphonate incadronate for bone metastases of breast cancer

Background. Bisphosphonates are bone resorption inhibitors which are effective in the treatment of diseases of increased bone turnover, such as hypercalcemia of malignancy and osteolytic bone metastasis. The safety and efficacy of incadronate, a third-generation bisphosphonate, were evaluated in breast cancer patients with bone metastases. Methods. Fifteen breast cancer patients with bone metastasis were enrolled. Incadronate's safety, its effectiveness in relieving bone pain, and its effects on bone metabolic markers and a tumor marker were assessed in 8 patients treated with a 10-mg IV infusion once a week for 5 weeks (10 mg × 5), 3 patients treated with a single 20-mg IV infusion (20 mg × 1), and 4 patients treated with a 20-mg IV infusion once a week for 5 weeks (20 mg × 5). Pain assessment was performed only in the patients with the repeated infusion regimens. Results. All incadronate treatment regimens were administered without any serious adverse reactions. Minimal fever was noted in 6 patients, but it subsided without any treatment. Incadronate relieved bone pain in 10 of the 12 patients who received repeated infusions. Levels of bone resorption markers dropped transiently, but the decreases in the individual markers of bone resorption varied. Levels of bone formation markers did not change significantly. Levels of a tumor marker specific to breast cancer, carbohydrate antigen (CA)15-3 decreased in patients whose metastases were limited to bone. Conclusion. The third-generation bisphosphonate, incadronate, was administered safely at dosages of up to 20 mg once a week for 5 weeks. Incadronate reduced bone pain, bone resorption marker levels, and CA15-3 tumor marker levels in breast cancer patients with bone metastases. Received: November 9, 1999 / Accepted: March 6, 2000