Breast Cancer Program
Department of Medicine
Massachusetts General Hospital
Up to 75% of patients with metastatic breast cancer will develop bone metastases during the course of their disease. This number is even higher among those with hormone-receptor positive (ER+) breast cancer. Thus, there is a great need to evaluate novel agents that may effectively treat bone metastases; however, patients with bone-only metastatic disease have traditionally been excluded from clinical trials due to the difficulty of measuring tumor in bone.
The planned phase II clinical trial of cabozantinib in patients with hormone-receptor-positive breast cancer with bone metastases opened at Massachusetts General Hospital Cancer Center in fall 2011. Shortly afterwards the trial became available at the Harvard Cancer Center affiliates (Dana-Farber Cancer Institute and Beth Israel Deaconess Medical Center). Accrual continued steadily during 2012. Memorial Sloan Kettering Cancer Center opened as a study site in September 2012. To date 50 evaluable patients have been enrolled on the study.
While the primary and secondary objectives of the trial have not yet been reached, preliminary data will be available soon. Given the promising activity observed in the trial to date, Dr. Higgins has added an amendment to the study to allow the accrual of 20 additional patients with metastatic breast cancer to bone who will be treated with a combination of cabozantinib and the endocrine therapy fulvestrant. This portion of the study was set to open in summer 2013.
Dr. Higgins reports that 53 evaluable patients have been enrolled on the study and accrual to the first cohort is complete. Final analysis of the results from the first cohort is ongoing. Preliminarily, it seems the trial will reach its primary endpoint of 30% of patients achieving a bone scan response with cabozantinib treatment. Given the promising activity observed in the trial to date, the study was amended and expanded to allow the accrual of 20 further patients with metastatic breast cancer to bone who will be treated with a combination of cabozantinib and the endocrine therapy fulvestrant. This portion of the study opened in June 2013 and 8 patients have been accrued to date.