Journal of Clinical Oncology, 2005 ASCO Annual Meeting Proceedings.
Vol 23, No 16S (June 1 Supplement), 2005: 534
© 2005 American Society of Clinical Oncology

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Abstract

Effect of oral ibandronate versus intravenous (i.v.) zoledronic acid on markers of bone resorption in patients with breast cancer and bone metastases: Results from a comparative phase III trial

Université Libre de Bruxelles, Brussels, Belgium; NN Blokhin Russian Cancer Research, Moscow, Russian Federation; F. Hoffman La-Roche AG, Basel, Switzerland; Hoffmann-La Roche Inc., Nutley, NJ

534

Background: There is a correlation between suppression of bone resorption markers and the rate of reduction in skeletal-related events (SREs). Data for oral clodronate suggest that orally administered bisphosphonates may not be as effective as i.v. bisphosphonates. However, there have been no head-to-head randomized clinical trials. This multicenter, randomized, open-label, parallel group study directly compares oral ibandronate with i.v. zoledronic acid with respect to biochemical markers of bone turnover. Methods: Advanced breast cancer patients with at least one confirmed osteolytic or mixed bone lesion received oral ibandronate 50mg/day (n=114) or i.v. zoledronic acid 4mg (n=110), infused over 15 minutes every 4 weeks for 12 weeks. Eligibility criteria included: 18 years of age; life expectancy 6 months, WHO Performance Status of 0, 1 or 2; adequate renal function (serum creatinine 3.0 mg/dL). The primary endpoint was the mean percentage change in cross-linked C-terminal telopeptide of type I collagen in serum (S-CTX) at the end of the study. Bone specific alkaline phosphatase (BAP), the amino-terminal procollagen propeptides of type I collagen (P1NP), and osteocalcin (OC) were also measured. Results: Mean (CI) percent changes from baseline were as follows. S-CTX: ibandronate –77% (CI –82% to –73%) vs zoledronic acid –75% (CI –82% to –67%); BAP: ibandronate –35% (CI –43% to –28%) vs zoledronic acid –32% (CI –47% to –17%); P1NP: ibandronate –48% (CI –56% to –40%) vs zoledronic acid –42% (CI –55% to –29%); OC: ibandronate –35% (CI –40% to –30%) vs zoledronic acid –34% (CI –45% to –22%). Conclusion: In this head-to-head trial, oral ibandronate was statistically non-inferior to zoledronic acid for the primary endpoint of S-CTX. It also showed similar effects to that of zoledronic acid on serum BAP, P1NP and OC. Overall, a convenient oral ibandronate dose of 50mg/day is as effective as zoledronic acid in suppressing tumor induced bone resorption.

Author Disclosure

Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Roche Roche Roche Roche

Abstract presentation from the 2005 ASCO Annual Meeting