A phase 2 study of high-activity 186Re-HEDP with autologous peripheral blood stem cell transplant in progressive hormone-refractory prostate cancer metastatic to bone.

PURPOSE: We investigated the potential for improvement in disease control by use of autologous peripheral blood stem cell transplant (PBSCT) to permit administration of high activities of (186)Re-hydroxyethylidene diphosphonate (HEDP) in patients with progressive hormone-refractory prostate cancer (HRPC).
METHODS: Eligible patients had progressive HRPC metastatic to bone, good performance status and minimal soft tissue disease. Patients received 5,000 MBq of (186)Re-HEDP i.v., followed 14 days later by PBSCT. Response was assessed using PSA, survival, pain scores and quality of life.
RESULTS: Thirty-eight patients with a median age of 67 years (range 50-77) and a median PSA of 57 ng/ml (range 4-3,628) received a median activity of 4,978 MBq (186)Re-HEDP (range 4,770-5,100 MBq). The most serious toxicity was short-lived grade 3 thrombocytopenia in 8 (21%) patients. The median survival of the group is 21 months (95%CI 18-24 months) with Kaplan-Meier estimated 1- and 2-year survival rates of 83% and 40% respectively. Thirty-one patients (81%, 95% CI 66-90%) had stable or reduced PSA levels 3 months post therapy while 11 (29%, 95% CI 15-49%) had PSA reductions of >50% lasting >4 weeks. Quality of life measures were stable or improved in 27 (66%) at 3 months.
CONCLUSION: We have shown that it is feasible and safe to deliver high-activity radioisotope therapy with PBSCT to men with metastatic HRPC. Response rates and survival data are encouraging; however, further research is needed to define optimal role of this treatment approach.