Secondary hormonal manipulations in prostate cancer

[New therapy concepts for castration-resistant prostate cancer: between hormone manipulation, targeted therapy and chemotherapy]

Within the last 2 years the therapeutic landscape of castration-resistant prostate cancer (CRPC) has dramatically changed. While chemotherapy with docetaxel has only shown a survival benefit in CRPC patients in the last 10 years, in the meantime 4 approved drugs are available for this indication and approval for immunotherapy with sipuleucel-T is expected. Docetaxel still plays a significant role in the treatment of CRPC but is also a cesura in the therapeutic sequence. For asymptomatic or minimally symptomatic, chemotherapy naive CRPC patients a significant survival benefit was shown for treatment with the androgen biosynthesis inhibitor abiraterone. Clinical data for the antiandrogen enzalutamide are expected shortly for this indication. For patients where docetaxel has failed abiraterone, enzalutamide and cabazitaxel have shown survival benefits in phase III trials. The radionuclide alpharadin not only palliated morbidity induced by bone metastases but also prolonged survival of CRPC patients. This review deals with the various drugs with respect to mode of action, clinical results and indications and will focus on new treatment options, such as targeted therapy with cabozantinib or immunotherapy with sipuleucel-T and prostvac.

Endocrine manipulations in cancer prostate: A review

Prostate cancer is an androgen dependent condition where Dihydrotestosterone promotes the growth of the neoplastic tissue. Androgen deprivation has been the mainstay of therapy for this condition. This can be achieved by surgical or medical means. Types of medical regimens are intermittent maximal or sequential androgen blockade.

An update on androgen deprivation therapy for prostate cancer

Androgen deprivation therapy (ADT) with gonadal testosterone depletion is the frontline treatment for advanced prostate cancer. Other hormonal interventions have a role in the treatment of prostate cancer. We sought to examine systematically the evidence for hormonal interventions in prostate cancer, risks of ADT, and interventions that mitigate these risks. Search results for therapeutic studies were focused primarily on randomized controlled clinical trials, and the Jadad scale criteria were used to evaluate the quality of these studies. Four trials of the efficacy of intermittent ADT versus continuous ADT were included. One randomized study analysis and six postrandomization analyses were included on the effects of ADT on cardiovascular mortality. Seven randomized controlled trials of pharmacologic interventions were included for the treatment of metabolic effects due to ADT. One randomized trial of GnRH antagonist versus GnRH agonist was included. Six phase I/II clinical trials of secondary hormonal therapies with novel mechanisms of action were included. Randomized studies completed to date indicate that intermittent ADT might be equivalent to continuous ADT. Although adverse effects of ADT include risk factors for cardiovascular disease, effects on cardiovascular mortality are uncertain. Bone loss and increased risk of fracture may be effectively treated with pharmacologic interventions. Benefits of ADT must be balanced with a consideration of the risks.

Rising prostate-specific antigen after primary treatment of prostate cancer: sequential hormone manipulation

OBJECTIVE

To evaluate systematically the current endocrine treatment options for patients with biochemical recurrence after radical prostatectomy or radiation therapy for localized prostate cancer.

METHODS

Literature search of PubMed documented publications and abstracts from international meetings. Key items included timing and type of salvage hormone therapy, length of its application and handling of side effects.

RESULTS

The majority of patients with isolated prostate-specific antigen (PSA) relapse are not candidates for salvage treatment with curative intent. The PSA threshold that triggers initiation of hormonal therapy is debatable and should be based also on pretreatment risk assessment. Intermittent androgen suppression is an emerging concept to circumvent the unresolved controversy of early versus deferred endocrine therapy. Since the tumor load at time of recurrence is low, peripheral androgen blockade with an antiandrogen and a 5alpha-reductase inhibitor is an acceptable first choice. In case of progression, addition of a LHRH analogue would be the next step. Antiandrogen withdrawal and second-line antiandrogens are clinically of limited value.

CONCLUSIONS

Biochemical-only progression after definitive treatment in curative intent is different from objective or even symptomatic relapse and allows for sequential hormonal therapy with a variety of compounds.

The role of hormonal treatment in prostate cancer

In 1941 Huggins and Hodges published for the first time the favorable effects of surgical castration and estrogen treatment on the progression of metastatic prostate cancer. However, this hormonal therapy is not without side effects. Since this pioneering milestone in history of prostate cancer, a further tremendous innovation did not take place. Today, due to intensive clinical, biochemical, nuclear-biological and molecular-biological research, many hormone active treatment variations are available. Besides traditional hormonal therapy, surgical or chemical castration, maximal androgen blockade, nontraditional forms of hormonal therapy, intermittent hormonal therapy, antiandrogens, 5-alpha-reductase inhibitors, and their combinations, we discuss options toward creating an increased number of side effect-oriented offers of hormonal treatment options, guaranteeing a longer and more comfortable exhaustion of the individual hormonal period of response and probably a longer survival. The prerequisite is a closer-than-ever monitoring by tumor marker and an early observation of symptomatic changes.