Prostate Cancer Intensive, Non-Cross Reactive Therapy (PRINT) for Castration Resistant Prostate Cancer (CRPC)

This phase II clinical trial will explore the efficacy of rapidly cycling non-cross reactive treatment therapies in the treatment of patients with newly diagnosed mCRPC. The primary hypothesis is that the best chance of eliminating or controlling disease is when the cancer is treatment naïve, and has not yet developed therapeutic resistance. By finding an optimal drug deployment strategy of already approved and available treatments for mCRPC, the researchers believe providers can more effectively treat an intrinsically heterogeneous disease, delay/prevent drug resistance, as well as minimize treatment toxicity. All of the treatment agents selected have well-defined individual toxicity profiles from large phase III trials, but there is limited clinical data about the toxicity profiles of these drugs in combinations. While each agent is generally well tolerated, toxicities remain a significant concern given the older age of the typical mCRPC patient, the comorbid conditions common to this patient population, as well as those borne from previous chronic androgen deprivation therapy. Each drug in the proposed treatment regimen will be used at their FDA-approved dosing and indication, with the exception of cabazitaxel, which will be used prior to disease demonstration of docetaxel failure, and in combination with carboplatin. The proposed sequencing is rationally designed, and based on each drug's distinct mechanisms of action as well as their toxicity profiles. The rapidly-cycling treatment regimen contains three, separate, consecutive treatment modules, each lasting 3 months: 1. Abiraterone; 2. Cabazitaxel + Carboplatin; 3. Enzalutamide + Radium-223. Therapeutic agents are delivered as non-cross reactive combinations, in order to achieve optimal therapeutic dosing at each cycle and decrease possibility of significant adverse effects. To the researcher knowledge, no study has evaluated the use of rapidly cycling, non-cross reactive therapies for the treatment of mCRPC. The hypothesis is that the identification of optimal combinations and sequencing of rapidly cycling non-cross reactive therapies can help prevent or delay the development of therapeutic drug resistance, and can be safely tolerated. Primary objective is to evaluate the time to disease progression after completion of all modules of the rapidly-cycling, non-cross reactive regimen in patients with mCRPC. Secondary objectives are to evaluate overall survival, prostate-specific antigen (PSA) response rate with each treatment module, changes to alkaline phosphatase level, and assess safety of the rapidly-cycling, non-cross reactive regimen. Additional exploratory objective are to evaluate the correlation of a peripheral whole-blood RNA signature with clinical outcome measures during and after treatment, and to evaluate changes to AR-V7 expression in CTCs with different treatment modalities and clinical outcomes.