Additional Analysis of the Secondary End Point of Biochemical Recurrence Rate in a Phase 3 Trial (CS21) Comparing Degarelix 80mg Versus Leuprolide in Prostate Cancer Patients Segmented by Baseline Characteristics

An update on the use of gonadotropin-releasing hormone antagonists in prostate cancer

Androgen deprivation therapy (ADT) is the main treatment approach in advanced prostate cancer and in recent years has primarily involved the use of gonadotropin-releasing hormone (GnRH) agonists. However, despite their efficacy, GnRH agonists have several drawbacks associated with their mode of action. These include an initial testosterone surge and testosterone microsurges on repeat administration. GnRH antagonists provide an alternative approach to ADT with a more direct mode of action that involves immediate blockade of GnRH receptors. Antagonists produce a more rapid suppression of testosterone (and prostate-specific antigen [PSA]) without a testosterone surge or microsurges and appear to offer an effective and well tolerated option for the hormonal treatment of prostate cancer. Comparisons with GnRH agonists have shown GnRH antagonists to be at least as effective in achieving and maintaining castrate testosterone levels in patients with prostate cancer. Furthermore, with antagonists, the lack of an initial testosterone surge (which may cause clinical flare) may allow more rapid relief of symptoms related to prostate cancer, avoid the need for concomitant antiandrogens to prevent clinical flare (so avoiding any antiandrogen-associated adverse events) and allow GnRH antagonist use in patients with high tumour burden and/or acute problems such as spinal cord compression. Although several antagonists have been investigated, only degarelix and abarelix are currently available for clinical use in prostate cancer. Currently, degarelix is the most extensively studied and widely available agent in this class. Degarelix is one of a newer generation of antagonists which, in a comprehensive and ongoing clinical development programme, has been shown to provide rapid, profound and sustained testosterone suppression without the systemic allergic reactions associated with earlier antagonists. This review examines the currently available data on GnRH antagonists in prostate cancer.

EAU guidelines on prostate cancer. Part II: Treatment of advanced, relapsing, and castration-resistant prostate cancer

OBJECTIVES

Our aim is to present a summary of the 2010 version of the European Association of Urology (EAU) guidelines on the treatment of advanced, relapsing, and castration-resistant prostate cancer (CRPC).

METHODS

The working panel performed a literature review of the new data emerging from 2007 to 2010. The guidelines were updated, and the levels of evidence (LEs) and/or grades of recommendation (GR) were added to the text based on a systematic review of the literature, which included a search of online databases and bibliographic reviews.

RESULTS

Luteinising hormone-releasing hormone (LHRH) agonists are the standard of care in metastatic prostate cancer (PCa). Although LHRH antagonists decrease testosterone without any testosterone surge, their clinical benefit remains to be determined. Complete androgen blockade has a small survival benefit of about 5%. Intermittent androgen deprivation (IAD) results in equivalent oncologic efficacy when compared with continuous androgen-deprivation therapy (ADT) in well-selected populations. In locally advanced and metastatic PCa, early ADT does not result in a significant survival advantage when compared with delayed ADT. Relapse after local therapy is defined by prostate-specific antigen (PSA) values >0.2 ng/ml following radical prostatectomy (RP) and >2 ng/ml above the nadir after radiation therapy (RT). Therapy for PSA relapse after RP includes salvage RT at PSA levels <0.5 ng/ml and salvage RP or cryosurgical ablation of the prostate in radiation failures. Endorectal magnetic resonance imaging and (11)C-choline positron emission tomography/computed tomography (CT) are of limited importance if the PSA is <2.5 ng/ml; bone scans and CT can be omitted unless PSA is >20 ng/ml. Follow-up after ADT should include screening for the metabolic syndrome and an analysis of PSA and testosterone levels. Treatment of castration-resistant prostate cancer (CRPC) includes second-line hormonal therapy, novel agents, and chemotherapy with docetaxel at 75 mg/m(2) every 3 wk. Cabazitaxel as a second-line therapy for relapse after docetaxel might become a future option. Zoledronic acid and denusomab can be used in men with CRPC and osseous metastases to prevent skeletal-related complications.

CONCLUSION

The knowledge in the field of advanced, metastatic, and CRPC is rapidly changing. These EAU guidelines on PCa summarise the most recent findings and put them into clinical practice. A full version is available at the EAU office or online at www.uroweb.org.

[New perspectives in prostate cancer management]

The treatment of prostate cancer is experiencing important innovations. Hormone therapy includes a new class of drugs: LHRH antagonists, which induce a rapid, fast and sustained reduction of testosterone levels. Active surveillance enables to avoid an aggressive treatment without decreasing survival, provided that strict eligibility and follow-up criteria are applied. New imaging techniques and laboratory assays lead to early diagnosis of small size tumors. Lastly, focal therapy has the potential to target localized cancers without deterioration of surrounding structures. These concomitant improvements offer the clinician and the patient attractive options for prostate cancer management. However, they are not devoid of limitations and constraints. Thus, it is crucial to define the most appropriate patient's profile for each therapeutic option, taking into account the objective characteristics of the tumor and the psychological features of the patient.

Androgen-Deprivation Therapy in Prostate Cancer: Clinical Evidence and Future Perspectives

Androgens are involved in the development and progression of prostate cancer even if the mechanism is not well-recognized. For this reason androgen-deprivation therapy remains a milestone for the treatment of patients with advanced and metastatic disease and, in the last years, in conjunction with radiotherapy and surgery in locally advanced tumors. Alternative options, such as intermittent deprivation suppression, seem to be promising in terms of clinical benefits and toxicity profile. However, current therapies present side effects, such as testosterone surge with consequent clinical flare-up, metabolic syndrome and hormone-resistance, which develops after a variable number of years. Novel therapies such as LH-RH antagonists and prolonged depot LH-RH analogues have been developed in order to avoid clinical flare-up and testosterone microsurges. Novel androgen synthesis inhibitors, such as abiraterone acetate and MDV3100, have been recently discovered and tested as promising hormonal second-line agents in patients with castration-resistant prostate cancer. Finally, long-term side effects from androgen deprivation, such as osteoporosis, sarcopenic obesity and cardiovascular morbidity should be carefully monitored and properly treated.

Evaluation of degarelix in the management of prostate cancer

Medical castration using gonadotropin-releasing hormone (GnRH) receptor agonists currently provides the mainstay of androgen deprivation therapy for prostate cancer. Although effective, these agents only reduce testosterone levels after a delay of 14 to 21 days; they also cause an initial surge in testosterone that can stimulate the cancer and lead to exacerbation of symptoms ("clinical flare") in patients with advanced disease. Phase III trial data for the recently approved GnRH receptor blocker, degarelix, demonstrated that it is as effective and well tolerated as GnRH agonists. However, it has a pharmacological profile more closely matching orchiectomy, with an immediate onset of action and faster testosterone and PSA suppression, without a testosterone surge or microsurges following repeated injections. As a consequence, with this GnRH blocker, there is no risk of clinical flare and no need for concomitant antiandrogen flare protection. Degarelix therefore provides a useful addition to the hormonal armamentarium for prostate cancer and offers a valuable new treatment option for patients with hormone-sensitive advanced disease. Here, we review key preclinical and clinical data for degarelix, and look at patient-focused perspectives in the management of prostate cancer.