Phase 2 Study of Androgen Deprivation Therapy (ADT) Plus Chemotherapy as Initial Treatment for Local Failures or Advanced Prostate Cancer

As a working hypothesis, investigators suspect that the transformation from an androgen-dependent to an androgen-independent phenotype is mediated by expansion of an androgen-independent clone already present at the time of ADT that continues to grow while androgen-sensitive clones are being suppressed. It is thus desirable to bring treatment to bear on the androgen-independent component while the corresponding tumor burden remains minimal and prolong the time to hormone resistance. Investigators view the androgen-independent component as analogous to "microscopic residual" or "micro-metastatic" disease, for which adjuvant chemotherapy has been shown to be effective in other contexts, even when the same drugs had little or no impact on survival in the setting of more advanced disease.

By treating all components of the tumor initially, investigators anticipate that the emergence of androgen-independent growth will be delayed, ultimately prolonging patient survival. Additionally, instead of treating patients empirically with an identical regimen, as in investigator's previous work, these patient subsets were designed to ensure a level of treatment appropriate to their individual disease, thus potentially lessening the burden of treatment (such as the long-term adverse effects of ADT). Investigators have chosen 3, 4, or 5 cycles of chemotherapy to be administered on the basis of tumor burden, a treatment selection method long established in germ cell tumors and used by this PI. Sub-analyses of previous data have raised the concern that treating patients with varying levels of disease the same way does not produce optimal results. Therefore, investigators seek to improve outcomes by tailoring treatment to tumor burden. In this study, patients with less tumor burden will receive 3 cycles of chemotherapy and 12 months of ADT, those with moderate tumor burden will receive 4 cycles and 18 months of treatment, and those with the greatest tumor burden will receive 5 cycles and 24 months of treatment. Additionally, this regimen of administering treatment sequentially, including a 2-week break, reduces toxicity.