Intermittent androgen deprivation: clinical experience and practical applications

Cognitive impairment among prostate cancer patients: An overview of reviews

To identify and clarify definitions and methods of measuring cancer-related cognitive impairment among prostate cancer patients treated with androgen deprivation therapy (ADT) and to assess the incidence and prevalence of cognitive impairment. A systematic review of Medline, EMBASE, PubMed, PsycINFO and CINAHL up to December 2015 was undertaken to identify English-language reviews. A total of 28 reviews were identified describing 20 primary studies. There were no studies of incidence. Reported prevalence rates varied between 10% and 69%. Cognitive domains impaired by ADT included: verbal memory, visuospatial ability and executive functions. Cognitive impairment was infrequently defined and four definitions were reported. A variety of measures and methods were used to assess cognitive function including neuropsychological tests, self-report measures and clinical assessments. The finding that, often, one measure was used to assess more than one aspect of cognition is likely to have contributed to imprecise estimates. There is a need to agree a definition of cognitive impairment in the clinical epidemiology of cancer and to standardise the selection of measures in order to aid accurate assessment and fair comparisons across studies regarding the prevalence of cognitive impairment among prostate cancer patients.

5α-Reductase inhibition coupled with short off cycles increases survival in the LNCaP xenograft prostate tumor model on intermittent androgen deprivation therapy

PURPOSE

Intermittent androgen deprivation therapy in patients with prostate specific antigen progression after localized prostate cancer treatment is an alternative to standard continuous androgen deprivation therapy. Intermittent androgen deprivation therapy allows for testosterone recovery during off cycles. This stimulates regrowth and differentiation of the regressed prostate tumor, lessens the side effects of continuous androgen deprivation therapy and potentially prolongs survival. Previously intermittent androgen deprivation therapy coupled with finasteride was shown to prolong survival in animals bearing androgen sensitive prostate tumors when the off cycle duration was not prolonged but rather fixed at 10 to 14 days. Regressed prostate tumor xenografts with testosterone replacement were initially responsive to 5α-reductase inhibition but growth resumed after several days. In shorter off cycles of testosterone recovery 5α-reductase inhibition might maximize tumor growth inhibition during intermittent androgen deprivation therapy and perhaps increase survival.

MATERIALS AND METHODS

We used the LNCaP xenograft tumor model to evaluate the effectiveness of short off cycles of 4 days coupled with 5α-reductase inhibition on survival and tumor regrowth while on intermittent androgen deprivation therapy.

RESULTS

Dutasteride inhibited initial testosterone induced tumor regrowth off cycles 1 and 2, and significantly increased survival.

CONCLUSIONS

These results further support the potential for intermittent androgen deprivation therapy combined with 5α-reductase inhibition to improve survival in patients with prostate cancer when off cycle duration is short or very short.

Novel synthesis and biological evaluation of enigmols as therapeutic agents for treating prostate cancer

Enigmol is a synthetic, orally active 1-deoxysphingoid base analogue that has demonstrated promising activity against prostate cancer. In these studies, the pharmacologic roles of stereochemistry and N-methylation in the structure of enigmols were examined. A novel enantioselective synthesis of all four possible 2S-diastereoisomers of enigmol (2-aminooctadecane-3,5-diols) from l-alanine is reported, which features a Liebeskind-Srogl cross-coupling reaction between l-alanine thiol ester and (E)-pentadec-1-enylboronic acid as the key step. In vitro biological evaluation of the four enigmol diastereoisomers and 2S,3S,5S-N-methylenigmol against two prostate cancer cell lines (PC-3 and LNCaP) indicates that all but one diastereomer demonstrate potent oncolytic activity. In nude mouse xenograft models of human prostate cancer, enigmol was equally effective as standard prostate cancer therapies (androgen deprivation or docetaxel), and two of the enigmol diastereomers, 2S,3S,5R-enigmol and 2S,3R,5S-enigmol, also caused statistically significant inhibition of tumor growth. A pharmacokinetic profile of enigmol and N-methylenigmol is also presented.

Evidence-based medicine: comparative analysis of luteinizing hormone-releasing hormone analogues in combination with external beam radiation and surgery in the treatment of carcinoma of the prostate

What's known on the subject? and What does the study add? Luteinizing hormone-releasing hormone analogues are a cornerstone in the management of many clinical situations in prostate cancer patients. The multiplicity of drugs make it difficult to decide which is the best drug to prescribe to each patient. Whether or not the different luteinizing hormone-releasing hormone analogues belong to the same drug class is only merely supposed. This study adds a systematic review of the literature in order to determine whether or not the luteinizing hormone-releasing hormone analogues available for prescription belong to the same drug class (same family, similar chemical structure, mechanism of action, and efficacy). The current evidence available is not enough to support a presumed drug class effect of the various analogues in the treatment of prostate carcinoma.

OBJECTIVE

• To study whether luteinizing hormone-releasing hormone (LHRH) analogues are agents of the same pharmacological class, i.e. whether they have the same clinical effect, using an evidence-based medicine approach.

MATERIAL AND METHODS

• We reviewed the evidence on the alleged 'drug class effect' among analogues and the existing bibliographic support for their use in various medical indications. We used PubMed as the main search source. Evidence level and degree of recommendation were assigned to each conclusion based on the 'Scottish Intercollegiate Guidelines Network'.

RESULTS

• There are no studies designed to answer the question of class effect between LHRH analogues or agonists. Reviews and meta-analyses have been performed on many other issues related to therapeutic management either with analogues alone, or in combination with radiation therapy and surgery. • Direct comparisons do not allow definitive conclusions to be reached. Indirect evidence is obtained from randomized studies comparing the different LHRH analogues with other treatments used to obtain androgen deprivation. Other issues related to pharmacokinetics and pharmacodynamics that can support either the existence or non-existence of class effect were evaluated.

CONCLUSION

• The current available evidence is not enough to support a presumed class effect of the drug among the different analogues in the treatment of prostate carcinoma in its various clinical situations.

Management of anaemia in prostate cancer

Anaemia is a frequent complication of prostate cancer and of its treatments. In Europe prostate cancer accounts for the 10.8% of all malignant neoplasms. Iatrogenic hypogonadism and age-related physiologic changes along with nutritional deficits contribute to increase prevalence of prostate cancer related anaemia. The reason of the present review is to provide clinicians with all aspects of a frequent and multifactorial co-morbidity, whose effects are often underestimated. Erythropoiesis pathology and causes of anaemia in prostate cancer are reviewed. Critical issues of clinical management of anaemia in prostate cancer are discussed.

Prolongation of off-cycle interval by finasteride is not associated with survival improvement in intermittent androgen deprivation therapy in LNCaP tumor model

BACKGROUND

We have previously reported that finasteride administration in intermittent androgen deprivation therapy (IADT) can improve survival of nude mice bearing LNCaP xenograft tumors when the duration of off-cycle in IADT was fixed. A recent retrospective study showed that addition of finasteride doubled the duration of the off-cycle, without changing progression to castration resistance. In view of the above difference, we attempted to investigate the relationship of 5alpha-reductase inhibition with the off-cycle interval and overall survival in a murine model.

METHODS

Subcutaneous LNCaP tumors were established in nude mice (Balb/C-Nu). After the tumors reached a size of 0.5 cm in diameter, the mice were castrated and followed up for 2 weeks after which they were randomized to continuous androgen deprivation (CAD), CAD plus finasteride, IADT, and IADT plus finasteride. The off-cycle was discontinued when the tumor volume was doubled. Subsequent cycles were carried out similarly.

RESULTS

Use of finasteride during the off-cycle of IADT doubled the first off-cycle duration. However, prolongation of the off-cycle by finasteride did not translate into an increase in overall survival.

CONCLUSIONS

The survival advantage of IADT + finasteride over IADT that we previously reported was lost when the off-cycle prolongation by finasteride was allowed. Maximum possible lengthening of the off-cycle by 5alpha-reductase inhibition is not associated with survival improvement in this animal model.

Androgen deprivation therapy: progress in understanding mechanisms of resistance and optimizing androgen depletion

Androgen deprivation therapy remains a critical component of treatment for men with advanced prostate cancer, and data support its use in metastatic disease and in conjunction with surgery or radiation in specific settings. Alternatives to standard androgen deprivation therapy, such as intermittent androgen suppression and estrogen therapy, hold the potential to improve toxicity profiles while maintaining clinical benefit. Current androgen deprivation strategies seem to incompletely suppress androgen levels and androgen-receptor-mediated effects at the tissue level. Advances in the understanding of mechanisms that contribute to castration-resistant prostate cancer are leading to rationally designed therapies targeting androgen metabolism and the androgen receptor. The results of large trials investigating the optimization of primary androgen deprivation therapy, including evaluation of intermittent androgen suppression and phase III studies of novel androgen synthesis inhibitors, such as abiraterone acetate, are eagerly awaited.

A double-blind randomized crossover study of oral thalidomide versus placebo for androgen dependent prostate cancer treated with intermittent androgen ablation

PURPOSE

We determined whether thalidomide can prolong progression-free survival in men with biochemically recurrent prostate cancer treated with limited androgen deprivation therapy.

MATERIALS AND METHODS

A total of 159 patients were enrolled in a double-blind randomized trial to determine if thalidomide can improve the efficacy of a gonadotropin-releasing hormone agonist in hormone responsive patients with an increasing prostate specific antigen after primary definitive therapy for prostate cancer. Patients were randomized to 6 months of gonadotropin-releasing hormone agonist followed by 200 mg per day oral thalidomide or placebo (oral phase A). At the time of prostate specific antigen progression gonadotropin-releasing hormone agonist was restarted for 6 additional months. Patients were then crossed over to the opposite drug and were treated until prostate specific antigen progression (oral phase B). Testosterone and dihydroxytestosterone were likewise monitored throughout the study.

RESULTS

During oral phase A the median time to prostate specific antigen progression was 15 months for the thalidomide group compared to 9.6 months on placebo (p = 0.21). The median time to prostate specific antigen progression during oral phase B for the thalidomide group was 17.1 vs 6.6 months on placebo (p = 0.0002). No differences in time to serum testosterone normalization between the thalidomide and placebo arms were documented during oral phase A and oral phase B. Thalidomide was tolerable although dose reductions occurred in 47% (58 of 124) of patients.

CONCLUSIONS

Despite thalidomide having no effect on testosterone normalization, there was a clear effect on prostate specific antigen progression during oral phase B. This is the first study to our knowledge to demonstrate the effects of thalidomide using intermittent hormonal therapy.

[Role of hormonotherapy in the treatment of metastatic prostate cancer]

Androgen privation is considered as the referent first line treatment for metastatic prostate cancer. Based on LHRH agonist, different therapeutic schedule included maximum androgenic blockage, intermittent treatment and associations with other drugs like oestrogen leading to possible hormonal manipulations. Since metastasis is confirmed, immediate treatment with continue LHRH agonist is the French Association of Urology (AFU) AFU recommendations treatment for metastatic prostate cancer but intermittent treatment can be considered as an option.

Androgen deprivation therapy for prostate cancer

Androgen deprivation continues to play a crucial role in the treatment of advanced and metastatic prostate cancer. In the 65 years since its use was first described, urologists and medical oncologists have developed new and innovative ways to manipulate the hypothalamic-pituitary-gonadal axis with the goal of alleviating symptoms and prolonging the life of men with prostate cancer. Despite the successes that androgen deprivation therapy has brought, each method and regimen possesses unique benefits and burdens, of which the clinician and patient must be cognizant. This review discusses the first-line androgen deprivation methods and regimens presently in use with special attention paid to their side effects and the management of them, as well as the question of when to initiate androgen deprivation therapy.

The role of gonadotropin releasing hormone in normal and pathologic endocrine processes

PURPOSE OF REVIEW

Gonadotropin releasing hormone is the hypothalamic hormone that activates pituitary gonadotropin production and, ultimately, determines reproductive competence. This review will highlight advances in the basic biology of the gonadotropin releasing hormone neuron that give insight into disorders of pubertal development, and clinical studies with gonadotropin releasing hormone analogs in infertility and prostate cancer treatment.

RECENT FINDINGS

Factors that control gonadotropin releasing hormone neuronal migration such as fibroblast growth factor receptor-1 and others that modulate secretion at puberty including kisspeptin/G-protein-coupled receptor 54 have been identified. Mutations in these pathways cause disorders during puberty. Clinical trials have defined the utility of gonadotropin releasing hormone agonists and antagonists for ovulation induction, and the effects of long-term administration for prostate cancer.

SUMMARY

Research into the role of the fibroblast growth factor receptor-1 and kisspeptin/G-protein-coupled receptor 54 pathways in gonadotropin releasing hormone neuronal development may identify the molecular defects in idiopathic hypogonadotropic hypogonadism and refine our understanding of normal negative and positive feedback by sex steroids. Clarification of the advantages and disadvantages of gonadotropin releasing hormone analog use in ovulation induction may improve the cost and success of infertility treatment. Insight into long-term effects of gonadotropin releasing hormone analogs in prostate cancer may lead to directed therapies to combat these consequences. Together these studies outline effects of modulation of gonadotropin releasing hormone in normal and pathophysiologic states.

Rapid androgen cycling as treatment for patients with prostate cancer

PURPOSE

To investigate the safety and feasibility of rapid androgen cycling for men with progressive prostate cancer.

EXPERIMENTAL DESIGN

Schedule 1 included a 4-week induction of androgen depletion, followed by 4-week treatment cycles of a monthly gonadotropin-releasing hormone agonist, testosterone on days 1 to 7, and an estrogen patch on days 8 to 21. Schedule 2 included a 12-week induction of androgen depletion followed by 4-week cycles of gonadotropin-releasing hormone agonist and testosterone, but no estrogens for patients with a prostate-specific antigen (PSA) nadir <1 ng/mL after induction. The primary end point was serially declining PSA trough values over six treatment cycles.

RESULTS

Thirty-six patients were treated; 27 were evaluable after cycling, of whom 8 of 12 (67%) and 9 of 15 (60%) on schedules 1 and 2, respectively, reached the end point. Five patients with PSA >1 ng/mL following induction did not cycle. No patient progressed radiographically or clinically during cycling. Three posttherapy PSA patterns were observed: a decline followed by a rapid increase in trough levels, a sustained decline with a plateau at a detectable nadir, and a decline to an undetectable nadir. Mean testosterone levels were castrate at the time of trough and in the normal physiologic range following androgen repletion. Major toxicities included grades 1 and 2 fatigue, hepatitis, gynecomastia, and hot flashes.

CONCLUSIONS

Rapid hormonal cycling is feasible and well tolerated, and successive declines in PSA troughs are achievable. Although the sample size was small, the proportion of patients achieving declining PSA at the end of six cycles was comparable with that reached with continuous androgen depletion therapy.