Temsirolimus to Reverse Androgen Insensitivity for Castration-resistant Prostate Cancer

Castration-resistant prostate cancer (CRPC) is also known as "androgen-insensitive" or "hormone-refractory" prostate cancer. While numerous therapies impact biochemical response in the setting of CRPC, there remains unmet medical need. New therapies that extend survival of patients beyond that provided by chemotherapy are needed. The mechanisms of tumor progression to castration-resistance are unclear, but preclinical studies suggest that functional loss of the tumor suppressor gene PTEN and subsequent up-regulation of Akt, which is upstream of mTOR, may be involved in prostate cancer progression and metastasis. Based on these observations, it is hypothesized that mTOR inhibitor temsirolimus may prolong hormone sensitivity and delay disease progression in castration-resistant prostate cancer patients before antiandrogen withdrawal. This study will assess efficacy on the basis of serum levels of PSA, an established surrogate endpoint for efficacy in prostate cancer.