Optimizing targeted therapy and developing novel outcome measures for patients with advanced prostate cancer at Memorial Sloan-Kettering Cancer Center

New drugs in prostate cancer

PURPOSE OF REVIEW

The survival of hormone-refractory metastatic prostate cancer patients has improved with the use of docetaxel-based chemotherapy. The survival benefits, however, are modest suggesting that rationally designed therapeutic approaches are needed. We discuss recent developments in the therapeutic approach to advanced metastatic hormone-refractory prostate cancer, including molecularly targeted therapy, signal transduction inhibitors, stem-cell targeted therapy, anti-angiogenic compounds, vaccines and immunomodulating agents, differentiation agents, cytotoxics, and pro-apoptotic agents.

RECENT FINDINGS

Over 200 compounds have entered clinical development for use in advanced prostate cancer, alone or in combination with cytotoxic agents such as docetaxel, or in other combinations. This article will review the results of emerging targets since the approval of docetaxel in 2004, concentrating on some of those compounds that, in our opinion, have the greatest potential and rationale for use.

SUMMARY

The growing field of targeted molecular therapy of prostate cancer has opened up numerous opportunities for therapeutic impact. Knowledge of the molecular determinants of progression, relapse after local therapy, chemotherapeutic resistance, and hormone refractoriness remains essential in the rational design of clinical trials of these agents. Given the complexity, heterogeneity, and crosstalk of molecular pathways and the molecular lesions in prostate cancer, combination or sequential therapy may be a necessary step towards significant therapeutic progress. Novel translational clinical trial methodologies may assist in a more rapid identification of active compounds at biologically active doses for phase-III testing.

Present status and perspectives in the treatment of hormone-refractory prostate cancer

The cornerstone in the treatment of de novo or recurrent metastatic prostate cancer is androgen deprivation. Unfortunately, nearly all patients will develop androgen-independent ('hormone-refractory') disease with progressive clinical deterioration and ultimately death. Chemotherapy has been shown to palliate symptoms of hormone-refractory disease but not to improve survival. Recently, two large phase III trials have demonstrated an overall survival advantage for patients treated with docetaxel-based regimens as compared to the best standard of care. Indeed, investigations into the pathophysiology of this malignancy, novel biological agents, skeletal protectants and radiopharmaceuticals are expanding the clinician's armamentarium and improving the patient's outcome.

DC therapy for prostate cancer

The wide range of currently available treatments for metastatic prostate cancer have demonstrated a modest palliative effect, but none to date has shown an increase in overall survival. The immune system has evolved to protect against infection, however, the modulation of this system represents the possibility of allowing it to identify and destroy cancer cells. The immune system is capable of inciting a powerful immune response against tissues, in the form of transplant rejection, and the potential exists to harness these powers to fight against tumors. Modest clinical responses have been seen in patients with metastatic prostate cancer treated with DC therapies; however, no increase in overall survival has been demonstrated. The current state of DC immunotherapy for prostate cancer is reviewed.