BONE MINERAL DENSITY IN MEN TREATED WITH SYNTHETIC GONADOTROPIN-RELEASING HORMONE AGONISTS FOR PROSTATIC CARCINOMA:

Discovery of an Orally Bioavailable Gonadotropin-Releasing Hormone Receptor Antagonist

We developed a compound library for orally available gonadotropin-releasing hormone (GnRH) receptor antagonists that were based on a uracil scaffold. On the basis of in vitro activity and CYP inhibition profile, we selected 18a (SKI2496) for further in vivo studies. Compound 18a exhibited more selective antagonistic activity toward the human GnRH receptors over the GnRHRs in monkeys and rats, and this compound also showed inhibitory effects on GnRH-mediated signaling pathways. Pharmacokinetic and pharmacodynamic evaluations of 18a revealed improved bioavailability and superior gonadotropic suppression activity compared with Elagolix, the most clinically advanced compound. Considering that 18a exhibited highly potent and selective antagonistic activity toward the hGnRHRs along with favorable pharmacokinetic profiles, we believe that 18a may represent a promising candidate for an orally available hormonal therapy.

Changes in muscle, fat and bone mass after 36 weeks of maximal androgen blockade for prostate cancer

OBJECTIVE

To assess the effects of androgen deprivation therapy (ADT) on whole-body and regional muscle, fat and bone mass in men with prostate cancer without metastatic bone disease.

PATIENTS AND METHODS

Seventy-two men aged 44-88 years underwent spine, hip and whole-body dual-energy X-ray absorptiometry scans at baseline and after 36 weeks of ADT. The change in whole-body and regional lean mass (LM), fat mass (FM), and bone mineral content and density (BMD) were determined. In addition, the prostate specific antigen (PSA), serum testosterone and haemoglobin levels were measured, and the level of physical activity and fatigue assessed using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-30.

RESULTS

The upper limb, lower limb, trunk and whole-body LM decreased by a mean (sem) of 5.6 (0.6)%, 3.7 (0.5)%, 1.4 (0.5)% and 2.4 (0.4)% (P < 0.01), respectively, while FM increased by 20.7 (3.3)%, 18.7 (2.7)%, 12.0 (2.5)% and 13.8 (2.3)% (P < 0.001). Hip, spine, whole-body and upper limb BMD decreased by 1.9 [corrected] (0.3)% [corrected], 3.3 [corrected] (0.4)%, 1.6 [corrected] (0.3)% and 1.3 (0.3%) (P < 0.001), but not lower limb BMD. Serum testosterone, PSA and haemoglobin levels decreased by 93.3 (0.4)%, 98.2 (0.5)%, and 8.8 (0.9)% (P < 0.001), respectively. In addition, physical activity levels decreased and levels of fatigue increased.

CONCLUSION

After 36 weeks of ADT there was a significant decrease in whole-body and regional LM and bone mass, while whole-body and regional FM increased in older men with prostate cancer. Strategies to counteract changes in soft tissue and bone mass during ADT should be formulated to minimize the risk of sarcopenia, osteoporosis and obesity.

Fracture risk in Danish men with prostate cancer: a nationwide register study

OBJECTIVE

To assess the risk of fracture attributable to prostate cancer, and the impact of exposure to prescribed gonadotrophin-releasing hormone agonists and antiandrogens on this risk in a nationwide, population-based case-control study.

PATIENTS AND METHODS

Data from the Danish National Hospital Discharge Register, the National Bureau of Statistics, and the National Prescriptions Database were merged. The analysis covered 15 716 men aged >50 years presenting with a fracture at any hospital in Denmark in 2000, and 47 149 age-matched control men. A previous diagnosis of prostate cancer had been recorded in 1.3% of controls and 2.5% of those with a fracture.

RESULTS

Prostate cancer was associated with an increased odds ratio (95% confidence interval) for all fractures of 1.8 (1.6-2.1), for hip fractures of 3.7 (3.1-4.4), but no increased risk of vertebral fractures. The increased fracture risk became apparent early after diagnosis and remained pronounced even in long-term survivors. Androgen deprivation therapy (ADT) with an odds ratio of 1.7 (1.2-2.5; P < 0.01) and orchidectomy, at 1.7 (1.2-2.4; P < 0.01) added to the overall fracture risk. In all, 3.1% of hip fractures in Danish men aged >50 years are attributable to prostate cancer.

CONCLUSION

Prostate cancer, orchidectomy and the use of ADT are associated with a markedly greater risk of fractures, especially of the hip. The risk of hip fracture is not confined to the very old, neither is the risk made negligible by the excess mortality in patients with advanced prostate cancer.

Contemporary use of hormonal therapy in prostate cancer: managing complications and addressing quality-of-life issues

While both short- and long-term androgen deprivation therapy (ADT) are effective for treating prostate cancer, with the clinical benefits patients can often have significant side-effects. It is important that these complications are recognized and managed appropriately so that adverse effects on the patient's quality of life (QoL) are minimized. The incidence of deaths from prostate cancer has decreased over the last decade, probably as a result of various factors including improved screening and diagnosis, improved treatments, and better risk assessment to help guide therapy. A meta-analysis of prostate cancer trials comparing the use of early vs late hormonal therapy found that 10-year overall survival increased by up to 20% between 1990 and 2000, and this was attributed to the earlier use of hormone therapy (HT) in these patients. Data from the USA Cancer of the Prostate Strategic Urological Research Endeavor database also suggest a significant decrease in risk in the last two decades in the USA, with more patients being identified with low-risk disease at diagnosis. In addition, there has been an increase in recent years in the use of HT at all stages of prostate cancer. The extensive use of ADT has raised concerns about potential adverse effects. ADT might be associated with a range of adverse effects that vary in their degree of morbidity and effect on the patient's QoL. They include hot flashes, osteoporosis, loss of libido or impotence, and psychological effects, e.g. depression, memory difficulties or emotional lability. Effective strategies are available for managing the major side-effects of HT, but to many patients these unwanted effects are often less important than the benefits of treatment. An investigation of health-related QoL found that men with prostate cancer receiving ADT had a poorer QoL than those not receiving ADT, but the difference was less pronounced after controlling for comorbidities. Many new therapies are currently under investigation which aim to maximize the clinical effects of ADT while reducing the adverse effects.

Long-term side-effects of intermittent androgen suppression therapy in prostate cancer: results of a phase II study

OBJECTIVE

To assess the feasibility and tolerability of intermittent androgen suppression therapy (IAS) in prostate cancer.

PATIENTS AND METHODS

Patients with recurrent or metastic prostate cancer received cyclical periods of treatment with leuprolide acetate and nilutamide for 8 months, and rest periods. Cycles were repeated at progression until the treatment failed to achieve normal prostate-specific antigen (PSA) levels. Patients were followed with PSA level, testosterone level, haemoglobin level, weight and bone mineral density evaluations. The median time to treatment failure, recovery from anaemia, or normalization of testosterone level was estimated by the Kaplan-Meier method.

RESULTS

In all, 95 patients received 245 cycles; the median duration of rest periods was 8 months and median time to treatment failure 47 months. Testosterone recovery during rest periods was documented in 117 (61%) of cycles. Anaemia was mild and reported in 33%, 44% and 67% of cycles 1, 2 and 3, respectively. Sexual function recovered during the rest periods in 47% of cycles. There was no significant overall change in body mass index at the end of the treatment period. Osteoporosis was documented in at least one site evaluated in 41 patients (37%).

CONCLUSIONS

IAS has the potential to reduce side-effects, including recovery of haemoglobin level, return of sexual function and absence of weight gain at the end of the study period.