Drivers for change in the management of prostate cancer - guidelines and new treatment techniques

Clinical practice guidelines and new treatment techniques are of particular importance for the effective management of prostate cancer. In Europe, the European Association of Urology guidelines offer a regularly updated evidence-based source of recommendations for the optimal treatment of prostate cancer. This review examines recent changes to guidelines highlighting developments in diagnosis, hormonal therapy in advanced and metastatic disease, bone protection, the definition of new terminology such as castrate-resistant prostate cancer, treatment of relapse after hormonal therapy, and cytotoxic therapy for castrate-resistant prostate cancer. The review also examines new surgical and radiotherapeutic developments in prostate cancer. This includes minimally invasive techniques such as robot-assisted radical prostatectomy, which is becoming the surgical gold standard for clinically localized disease in many countries. Other promising techniques reviewed include cryosurgical ablation of the prostate, laser-induced interstitial thermotherapy, vascular-targeted photodynamic therapy, and high-intensity focused ultrasound; with the exception of cryotherapy, these approaches are not currently recommended for routine clinical use. Finally, we will review the evidence supporting intensity modulated radiotherapy, an optimized high-precision form of three-dimensional conformal radiotherapy which aims to allow homogeneously increased radiation doses, without increased toxicity to healthy at-risk organs. Novel techniques such as proton beam or carbon ion radiotherapy, which may offer improved and more localized dose distribution with reduced damage to normal tissue, are also examined.

Castration-resistant prostate cancer: new science and therapeutic prospects

There is a growing number of new therapies targeting different pathways that will revolutionize patient management strategies in castration-resistant prostate cancer (CRPC) patients. Today there are more clinical trial options for CRPC treatment than ever before, and there are many promising agents in late-stage clinical testing. The hypothesis that CRPC frequently remains driven by a ligand-activated androgen receptor (AR) and that CRPC tissues exhibit substantial residual androgen levels despite gonadotropin-releasing hormone therapy, has led to the evaluation of new oral compounds such as abiraterone and MDV 3100. Their results, coupled with promising recent findings in immunotherapy (eg sipuleucel-T) and with agents targeting angiogenesis (while awaiting the final results of the CALGB trial 90401) will most probably impact the management of patients with CRPC in the near future. Other new promising agents need further development. With our increased understanding of the biology of this disease, further trial design should incorporate improved patient selection so that patient populations are those who may be most likely to benefit from treatment.

A clinical trials outcome paradox: should survival prevail in the absence of clinical benefit?

A comparison was made using an established prognostic nomogram to determine the impact of survival on patients with castration-resistant prostate cancer using a pox-based vaccine. Survival in the treated cohort of 32 patients had improved compared with what was anticipated for the same group using an established nomogram. With a median follow-up of 44.6 months, the median overall survival for all 32 patients in the study was 26.6 months compared with a median nomogram-predicted survival of 17.4 months. The data suggested that there may be measures by which patients may be preselected and therefore may be more responsive candidates to a vaccine treatment approach. This study brings to light improved survival for patients, but the issue of how to reconcile a survival advantage in the absence of significant clinical anti-tumor response remains unsettled.

Horizon scanning for novel therapeutics for the treatment of prostate cancer

IMPORTANCE OF THE FIELD

Treatment options for patients with advanced prostate cancer (PCa) remain limited. Improved understanding of the underlying molecular drivers of prostate cancer pathogenesis, progression and resistance development has provided the fundamental basis for rational targeted drug design.

AREAS COVERED IN THIS REVIEW

This review will discuss the most recent developments in the field of prostate cancer therapies including key findings such as the identification of ETS gene rearrangements, the dissection of prostate cancer molecular heterogeneity and the discovery that castration-resistant prostate cancer (CRPC) remains androgen-driven despite the androgen-depleted milieu, thus making androgen receptor signaling a continued focus of molecularly targeted treatments. A multitude of new molecularly targeted agents are in clinical development and are highly likely to change the current treatment paradigm.

WHAT THE READER WILL GAIN

This review will outline the current clinical development of molecular targeted treatments in CRPC.

TAKE HOME MESSAGE

Unraveling the complex molecular biology that underpins this heterogeneous disease may pave the way to personalized therapy with a wide range of rationally targeted agents and combination treatments. In conclusion, we can predict that the rational clinical development of new targeted drugs will improve the outcome of men with prostate cancer in the years ahead.

Emerging therapies in castrate-resistant prostate cancer

Prostate cancer is the most common cancer in men in the United States, and despite screening and early treatment, more than 27,000 men are predicted to die of the disease this year, almost all of whom will die of castrate-resistant, metastatic cancers that have progressed despite androgen deprivation therapy, also known as hormonal therapy. In recent years, an increased understanding of molecular mechanisms of prostate cancer progression and castration resistance has led to improved treatment strategies. This review focuses on emerging therapies for the treatment of castrate-resistant prostate cancer, with an emphasis on the importance of the drug targets as well as the state of current clinical trials, including those utilizing hormonal therapies, biological agents, and immunotherapy that are underway or have recently been completed.

Immunologic and prognostic factors associated with overall survival employing a poxviral-based PSA vaccine in metastatic castrate-resistant prostate cancer

A concurrent multicenter, randomized Phase II trial employing a recombinant poxviral vaccine provided evidence of enhanced median overall survival (OS) (p = 0.0061) in patients with metastatic castrate-resistant prostate cancer (mCRPC). The study reported here employed the identical vaccine in mCRPC to investigate the influence of GM-CSF with vaccine, and the influence of immunologic and prognostic factors on median OS. Thirty-two patients were vaccinated once with recombinant vaccinia containing the transgenes for prostate-specific antigen (PSA) and three costimulatory molecules. Patients received boosters with recombinant fowlpox containing the same four transgenes. Twelve of 32 patients showed declines in serum PSA post-vaccination and 2/12 showed decreases in index lesions. Median OS was 26.6 months (predicted median OS by the Halabi nomogram was 17.4 months). Patients with greater PSA-specific T-cell responses showed a trend (p = 0.055) toward enhanced survival. There was no difference in T-cell responses or survival in cohorts of patients receiving GM-CSF versus no GM-CSF. Patients with a Halabi predicted survival of <18 months (median predicted 12.3 months) had an actual median OS of 14.6 months, while those with a Halabi predicted survival of > or =18 months (median predicted survival 20.9 months) will meet or exceed 37.3 months, with 12/15 patients living longer than predicted (p = 0.035). Treg suppressive function was shown to decrease following vaccine in patients surviving longer than predicted, and increase in patients surviving less than predicted. This hypothesis-generating study provides evidence that patients with more indolent mCRPC (Halabi predicted survival > or =18 months) may best benefit from vaccine therapy.