A phase II study of 5-aza-2'deoxycytidine (decitabine) in hormone independent metastatic (D2) prostate cancer

Aims and Background: Decitabine (5-aza-2'-deoxycytidine) is an S-phase- specific pyrimidine analog with hypomethylation properties. In laboratory models of prostate cancer (PC-3 and DU-145), decitabine induces cellular differentiation and enhanced expression of genes involved in tumor suppression, immunogenicity, and programmed cell death. Methods: We conducted a phase II study of decitabine in 14 men with progressive, metastatic prostate cancer recurrent after total androgen blockade and flutamide withdrawal. Decitabine was administered at a dose of 75 mg/m²/dose IV as a I hour infusion every 8 hours for three doses. Cycles of therapy were repeated every 5 to 8 weeks to allow for resolution of toxicity. Results: Two of 12 patients evaluable for response had stable disease with time to progression of more than 10 weeks. This activity was seen in 2 of 3 African-American patients. Toxicity was similar to previously reported experience. No significant changes in urinary concentrations of the angiogenic factor bFGF, a potential biomarker of tumor activity, were identified over time in 7 unselected patients with progressive disease. Conclusions: We conclude that decitabine is a well tolerated regimen with modest clinical activity against hormone-independent prostate cancer. Further investigations in patients of African-American origin may be warranted.