The ODYSSEY TRIAL Phase IV Trial Evaluating the Palliative Benefit of Pamidronate or Zoledronic Acid in Breast Cancer

Overview

Metastatic breast cancer patients with bone involvement who are at high-risk of subsequent skeletal related event (SRE), defined as radiotherapy or surgery to the bone, pathological fracture, spinal cord compression, or hypercalcemia (as reflected through: elevated sCTX or bone pain or a prior SRE despite receiving standard bisphosphonate therapy) should experience a decrease in the surrogate marker, sCTX, at week 12 if switched to zoledronic acid compared with those patients who continue on intravenous pamidronate (i.e. current standard of care). The investigators propose that a drop in sCTX will correlate with improved pain, quality of life and a reduced incidence of further SREs.

This study will be a prospective, randomized, double-blind, placebo controlled, Phase IV study of pamidronate vs. zoledronic acid in women with breast cancer and bone metastases. Patients who are at high-risk of subsequent SREs will be screened for entry into this study. High-risk will be defined as fulfilling one or more of the following criteria: elevated sCTX (\>400ng/L) and/or bone pain and/or a prior SRE and/or progression of bone disease (by imaging) despite at least 3 months of pamidronate therapy. Patients who meet the eligibility criteria, will be randomized to receive 3 cycles of intravenous zoledronic acid (4mg intravenously over 15 minutes) or to continue their standard dose of pamidronate. Both treatments will be given at 4 week intervals. Patients will be stratified according to whether or not they have had a SRE prior to study entry, progressive bone disease or bone pain. In order for the study to be double-blind, patients will receive two infusions simultaneously, at each study visit, one of the active drug and another of the placebo. After completing 3 cycles of study treatment, patients will resume their monthly intravenous pamidronate infusions as per current standard of care.