Novel targeted therapies for prostate cancer

This article reviews the concepts and rationale behind targeted agents that are currently in clinical testing for patients with castration resistant prostate cancer (CRPC). Advances in our understanding of the molecular mechanisms underlying prostate cancer progression has translated into a variety of treatment approaches. Agents targeting androgen receptor activation and local steroidogenesis, angiogenesis, apoptosis, chaperone proteins, the insulinlike growth factor pathway, RANK ligand, endothelin receptors, and Src family kinases are entering, or have recently completed, accrual to phase III trials for patients with CRPC. There has also been interest generated by data from early-phase studies evaluating multitargeted tyrosine kinase inhibitors, agents effecting signal transduction pathways, and novel cytotoxics.

Castration-resistant prostate cancer: from new pathophysiology to new treatment targets

CONTEXT

Castration-resistant prostate cancer (CRPC) refers to patients who no longer respond to surgical or medical castration. Standard treatment options are limited.

OBJECTIVE

To review the concepts and rationale behind targeted agents currently in late-stage clinical testing for patients with CRPC.

EVIDENCE ACQUISITION

Novel targeted therapies in clinical trials were identified from registries. The MEDLINE database was searched for all relevant reports published from 1996 to October 2009. Bibliographies of the retrieved articles and major international meeting abstracts were hand-searched to identify additional studies.

EVIDENCE SYNTHESIS

Advances in our understanding of the molecular mechanisms underlying prostate cancer (PCa) progression has translated into a variety of treatment approaches. Agents targeting androgen receptor (AR) activation and local steroidogenesis, angiogenesis, immunotherapy, apoptosis, chaperone proteins, the insulin-like growth factor (IGF) pathway, RANK-ligand, endothelin receptors, and the Src family kinases are entering or have recently completed accrual to phase 3 trials for patients with CRPC.

CONCLUSIONS

A number of new agents targeting mechanisms of PCa progression with early promising results are in clinical trials and have the potential to provide novel treatment options for CRPC in the near future.

Histone deacetylase inhibitors as anti-neoplastic agents

Histone deacetylase inhibitors (HDACIs) constitute a novel class of targeted drugs that alter the acetylation status of histones and other important cellular proteins. These agents modulate chromatin structure leading to transcriptional changes, induce pleiotropic effects on functional pathways and activate cell death signaling in cancer cells. Anti-neoplastic activity in vitro was shown in several experimental models of cancer, but the exact mechanism of cytotoxicity and responses are not clearly understood. Phase I/II clinical trials of various HDACIs as single agents conducted to date have shown substantial activity in cutaneous T cell lymphoma (CTCL), preliminary activity in Hodgkin's disease and modest activity in myeloid neoplasms. Responses have been rare in solid tumors. Several agents are being tested in combination therapy clinical trials, either as chemosensitizers for cytotoxic chemotherapy or radiation therapy, or in association with DNA methylation inhibitors based on in vitro synergy. In this review, we focus on recent basic and clinical data that highlight the anti-neoplastic role of HDACIs.