Loading Dose Ibandronate Versus Standard Oral Ibandronate in Patients With Bone Metastases From Breast Cancer

Abstract

IntroductionIn this phase II trial, the efficacy and safety of loading-dose I.V. ibandronate in patients with breast cancer with bone metastases were evaluated. Patients and MethodsThirty-four patients were randomized to receive a loading dose of 12 mg I.V. ibandronate on day 1 then oral ibandronate 50 mg daily (arm A), or standard oral therapy of 50 mg ibandronate daily from day 1 (arm B). The primary end point was percentage change in serum C-terminal crosslinking telopeptide of type I collagen (S-CTX) from baseline by day 5 of study. Secondary/exploratory end points included percentage change in other bone turnover markers (N-terminal cross-linking telopeptides of type I collagen [NTX], procollagen type I N propeptide, bone alkaline phosphatase) and change in average bone pain score. ResultsThere was a significantly greater reduction in S-CTX at day 5 in arm A compared with arm B (median difference, 15.82%; P = .005). There was also a significantly greater reduction in urine NTX/creatinine at day 5 (P = .009) and at the end of weeks 1 to 8 (averaged; P = .006). Average bone pain score was lower in arm A at the end of 8 weeks (P = .012). There were no additional adverse events after administration of 12 mg I.V. loading dose of ibandronate. ConclusionA 12-mg dose of I.V. ibandronate rapidly reduced markers of bone turnover and can be administered without additional toxicity.