Phase II trial of GM-CSF + thalidomide in patients with androgen-independent metastatic prostate cancer

BACKGROUND: Androgen-independent metastatic prostate cancer is a major therapeutic dilemma. Granulocyte-macrophage colony stimulating factor (GM-CSF) and thalidomide have some biologic activity as single agents in this disease subset. We performed a Phase II trial of this combination to assess its toxicity and potential utility as an immunomodulatory approach to management of advanced prostate cancer. METHODS: Twenty-two patients were treated with GM-CSF 250 microg administered SC on Monday, Wednesday and Friday of each week. Thalidomide was escalated to reach the study dose of 200 mg/day. Patients were assessed every 4 weeks with therapy continuing to a maximum of 6 months. RESULTS: All 22 patients had a decrement in PSA at 2 weeks postinitiation of therapy. Five patients had a > or =50% decline (56, 64,66,66, and 94%, respectively) from baseline verified at 4 weeks post best response. This corresponds to an observed response rate of 23% (95% confidence interval 8-45%). Therapy was well tolerated with the majority of patients experiencing only one event. CONCLUSIONS: The combination of GM-CSF + thalidomide is relatively well tolerated and has the potential to produce antitumor activity in a population of patients with metastatic, androgen independent prostate cancer. This nonchemotherapy combination should be explored in a subset of patients with less advanced disease.