The effects of the dual 5alpha-reductase inhibitor dutasteride on localized prostate cancer--results from a 4-month pre-radical prostatectomy study

Concentration-dependent effects of dutasteride on prostate-specific membrane antigen (PSMA) expression and uptake of 177 Lu-PSMA-617 in LNCaP cells

BACKGROUND

Prostate-specific membrane antigen (PSMA)-based imaging and therapy are increasingly used in the management of prostate cancer. However, low PSMA surface expression in certain patients is a limitation for PSMA-based technologies. We have previously shown that high doses of dutasteride, a 5α-reductase inhibitor generally used for the treatment of benign prostatic enlargement, increase the PSMA expression in vitro. We now further analyzed the concentration- and time-dependent effects of dutasteride in LNCaP cells.

METHODS

Androgen receptor (AR) expressing prostate cancer cells (LNCaP) were treated for 7 to 14 days with vehicle control (0.1% dimethyl sulfoxide) or different concentrations of dutasteride (0.25 , 0.5 , 1 , and 5  μM). In addition to cell proliferation, PSMA surface expression was assessed using flow cytometry (FACS) and immunocytochemistry. Total PSMA and AR expression was analyzed by capillary western immunoassay (WES). In addition, tumor cell uptake and internalization assays of ¹⁷⁷ Lu-PSMA-617 were performed.

RESULTS

Dutasteride treatment resulted in a significant upregulation of PSMA surface expression compared to vehicle control after 7 days in all tested concentrations. After 14 days a further, concentration-dependent increase of PSMA surface expression was detectable. Total PSMA protein expression significantly increased after treatment of cells with high concentrations of dutasteride using 5  μM for 7 or 14 days. However, when lower concentrations were used total PSMA expression was not significantly altered compared to vehicle control. Further testing revealed a dose-dependent increase in uptake and internalization of ^177Lu -PSMA-617 after 7 and 14 days. Though, a significantly increased uptake was only observed using a 5  μM dutasteride concentration for 7 days as well as 1  and 5  μM for 14 days.

CONCLUSION

Our investigations revealed a concentration- and time-dependent effect of dutasteride on PSMA expression and uptake of ^177Lu -PSMA-617 in LNCaP cells. A short-term treatment of patients with high doses of dutasteride might increase the detection rate of PSMA-based imaging and increase the effect of ^177Lu -PSMA-617 therapy via upregulation of PSMA expression.

Sex steroids in serum and prostatic tissue of human cancerous prostate (STERKPROSER trial)

BACKGROUND

Currently, there is no consensus regarding the expected concentration levels of intra-prostatic sex steroids in patients with Prostate Cancer (PCa). Our objective was to assess the concentration levels of sex steroids in prostatic tissue and serum, in two cohorts of patients with localized PCa or benign prostatic hyperplasia (BPH).

METHODS

Between September 2014 and January 2017, men selected for radical cystectomy (for bladder cancer) or open prostatectomy (for BPH), and men selected for radical prostatectomy for localized PCa were included. Blood samples were collected at baseline before surgery, and steroid concentrations were assessed following the recommendations of the Endocrine Society. Intra-prostatic samples were collected from fresh surgical samples, and assessed by gas chromatography and mass spectrometry (GC/MS). Permanova analysis was performed. Analyses were adjusted for age, prostate weight, and prostate-specific antigen (PSA) level.

RESULTS

A total of 73 patients (41 patients with PCa and 32 patients with BPH) were included in this study. Patients with PCa were younger, and had smaller prostate volumes with higher levels of PSA. The levels of Total Testosterone (TT), Di-Hydro-Testosterone (DHT), and Estradiol (E2) in the serum were not significantly different between PCa and BPH. In PCa tissue, TT concentrations were significantly lower (0.11 ng/g vs 0.47 ng/g, P = 0.0002), however its derivative E2 had significantly higher concentrations (31.0 ng/g vs 22.3 ng/g, P = 0.01). DHT tissue concentrations were not significantly different between the two groups (5.55 ng/g vs 5.42 ng/g, P = 0.70). Intra-prostatic TT concentrations were significantly lower in the peripheral zone than in the central zone for the CaP group (0.07 ng/g vs 0.15 ng/g, P = 0.004).

CONCLUSIONS

Patients with PCa had lower intra-prostatic TT and higher E2 concentrations levels compared to the patients with BPH. PCa seem to consume more TT and produce more E2, especially in the peripheral zone.

Prognostic influence of 5 alpha reductase inhibitors in patients with localized prostate cancer under active surveillance

Objective

The incidence of prostate adenocarcinoma (PCa) is increased with the use of prostate-specific antigen (PSA). In the current study, we aimed to investigate the impact of 5- alpha- reductase inhibitors (5-ARI) on pathological progression in patients followed by active surveillance (AS).

Material and methods

Records of 69 patients with localized prostate cancer under AS (PSA ≤15 ng/mL, PSAD ≤0.20, ≤cT2c, Gleason sum ≤3+3, the number of cancer positive cores ≤3) were evaluated retrospectively. Patients were followed-up with quarterly PSA testing and semiannual digital rectal examination during the first 2 years, and semiannual PSA testing thereafter. Repeat biopsies were done annually and whenever indicated by clinical findings. Pathological progression was defined as increasing Gleason grade, number of cancer-positive cores, and/or increasing percentage of cancer in any core.

Results

Patients using (29/69: 42%) and not using (40/69: 58%) 5-ARI were followed for a median of 39 (IQR: 23-45) and 23.5 (IQR: 17-37.5) months, respectively. Pathological progression was observed in 32% (22/69) of the patients at a median of 25 (IQR: 18-39) months. Pathological progression was observed in 34.5% (10/29) and 30% (12/40) of the patients using and not using 5-ARI, respectively (Log-rank p=0.4151). Definitive treatment was done in 31% (9/29) and 47.5% (19/40) of the patients using and not using 5-ARI, respectively. Patients who did not use 5-ARI received definitive treatment earlier than 5-ARI users (Log-rank p=0.0342). On multivariate analysis, more than 2 cancer-positive cores (HR: 11.62) and age (HR: 0.94) were independently associated with pathological progression (p<0.05), rather than 5-ARI use (p=0.148).

Conclusion

More than 2 cancer- positive cores at the initial biopsy was the strongest covariate associated with pathological progression; these patients should not be offered AS. There was no impact of 5-ARI use on pathological progression in AS.

Computer vision detects subtle histological effects of dutasteride on benign prostate

OBJECTIVE

To determine whether a computer vision-based approach applied to haematoxylin and eosin (H&E) prostate biopsy images can distinguish dutasteride-treated tissue from placebo, and identify features associated with degree of responsiveness to 5α-reductase inhibitor (5ARI) therapy.

SUBJECTS AND METHODS

Our study population comprised 100 treatment-adherent men without prostate cancer assigned to dutasteride or placebo in the REDUCE trial, who had slides available from mandatory year-4 biopsies. Half of the men also provided slides from a year-2 biopsy. We obtained 20× whole-slide images and used specialized software to generate a library of 1 300 epithelial and stromal features from objects comprising superpixels and several types of nuclei, including spatial relations among objects between and within each hierarchical level. We used penalized logistic regression and fivefold cross-validation to find optimal combinations of histological features in the year-4 biopsies. Feature data from the year-2 biopsies were fitted to a final model for independent validation. Two pathologists, blinded to treatment, scored each image for focal atrophy and histological features previously linked to 5AR1 treatment.

RESULTS

Consensus classification by pathologists obtained a discrimination accuracy equivalent to chance. A 21-feature computer vision model gave a cross-validation area under the curve of 0.97 (95% confidence interval [CI] 0.95-0.99) in the year-4 biopsies and 0.79 (95% CI: 0.65-0.92) in the set-aside year-2 biopsies. Histology scores were not correlated with change in prostate-specific antigen level, serum dihydrotestosterone level or gland volume. Key features associated with dutasteride treatment included greater shape and colour uniformity in stroma, irregular clustering of epithelial nuclei, and greater variation in lumen shape.

CONCLUSION

The present findings show that a computer vision approach can detect subtle histological effects attributable to dutasteride, resulting in a continuous measure of responsiveness to the drug that could eventually be used to predict individual patient response in the context of BPH treatment or cancer chemoprevention.

Pre-radiotherapy PSA progression is a negative prognostic factor in prostate cancer patients using 5‑alpha-reductase inhibitors

OBJECTIVE

To investigate the impact of 5‑alpha-reductase inhibitor (5-ARI) use on radiotherapy outcomes for localized prostate cancer.

PATIENTS AND METHODS

We included 203 patients on a 5-ARI from our institutional database comprising over 2500 patients who had been treated with either external beam radiotherapy (EBRT) or brachytherapy for localized prostate cancer. Patients received a 5-ARI for urinary symptoms or active surveillance. Cancer progressions at the time of definitive treatment were analyzed according to the following criteria: (a) progression of Gleason score or increase in cancer volume on biopsy, (b) first biopsy positive for cancer after being treated for urinary symptoms with a 5-ARI, and (c) prostate-specific antigen (PSA) progression with or without a previous cancer diagnosis. Biochemical failure (BF) was defined by the Phoenix definition. Log-rank test was used for survival analysis.

RESULTS

At a median follow-up of 38.2 months (standard deviation 22.2 months), 10 (4.9%) patients experienced BF. Concerning prostate cancer progression criteria, 52% of men demonstrated none, 37% showed only one criterion, and 11% showed two. Using univariate analysis, PSA progression (p = 0.004) and appearance of a positive biopsy (p < 0.001) were significant predictive factors for BF, while Gleason progression (p = 0.3) was not. In multivariate analysis adjusted for cancer aggressiveness, rising PSA (hazard ratio, HR, 5.7; 95% confidence interval, CI, 1.1-28.8; p = 0.04) and the number of cancer progression factors (HR 2.9, 95% CI 1.2-7.0, p = 0.02) remained adverse risk factors.

CONCLUSION

PSA progression experienced during 5‑ARI treatment before radiotherapy is predictive of worse biochemical outcome. Such details should be considered when counseling men prior to radiation therapy.

Testosterone and dihydrotestosterone levels in the transition zone correlate with prostate volume

BACKGROUND

There is still no consensus regarding intraprostatic androgen levels and the accumulation of androgens in the hyperplastic prostatic tissue. The current opinion is that intraprostatic dihydrotestosterone (DHT) concentrations are maintained but not elevated in benign prostatic hyperplasia (BPH), while there is no similar data concerning intraprostatic testosterone (T).

METHODS

Tissue T (tT) and tissue DHT (tDHT) concentration were determined in 93 patients scheduled for initial prostate biopsy. The criteria for biopsy were abnormal DRE and/or PSA > 4 ng/mL. Total prostate volume (TPV) was determined by transrectal ultrasound (TRUS). During TRUS- guided prostate biopsy, 10-12 samples were collected from the peripheral zone (PZ) and two additional samples were collected from the transition zone (TZ). The samples from the TZ were immediately frozen in liquid nitrogen at -70°C, and transported for tissue androgen determination, using liquid chromatography mass spectrometry (LC-MS).

RESULTS

Pathological analysis revealed that prostate cancer (PCa) was present in 45 and absent in 48 patients. In the whole group, there were 42 men with small prostate (TPV < 30 mL) and 51 with enlarged prostate (TPV ≥ 31 mL). The overall average tT level was 0.79 ± 0.66 ng/g, while the average tDHT level was 10.27 ± 7.15 ng/g. There were no differences in tT and tDHT level in prostates with and without PCa. However, tT and tDHT levels were significantly higher in larger, than in smaller prostates (tT: 1.05 ± 0.75 and 0.46 ± 0.29 ng/g, and tDHT: 15.0 ± 6.09 and 4.51 ± 2.75 ng/g, respectively). There were strong correlations between tT and TPV (r = 0.71), and tDHT and TPV (r = 0.74).

CONCLUSIONS

The present study confirmed that both T and DHT accumulated in the stroma of enlarged prostates; the degree of accumulation correlated with prostate volume.

Co-clinical Analysis of a Genetically Engineered Mouse Model and Human Prostate Cancer Reveals Significance of NKX3.1 Expression for Response to 5α-reductase Inhibition

BACKGROUND

Although men on active surveillance for prostate cancer (PCa) may benefit from intervention with 5α-reductase inhibitors (5-ARIs), it has not been resolved whether 5-ARIs are effective for delaying disease progression and, if so, whether specific patients are more likely to benefit.

OBJECTIVE

To identify molecular features predictive of patient response to 5-ARIs.

DESIGN, SETTING, AND PARTICIPANTS

Nkx3.1 mutant mice, a model of early-stage PCa, were treated with the 5-ARI finasteride, and histopathological and molecular analyses were performed. Cross-species computational analyses were used to compare expression profiles for treated mice with those of patients who had received 5-ARIs before prostatectomy.

INTERVENTION

Finasteride administered to Nkx3.1 mutant mice. 5-ARI-treated patient specimens obtained retrospectively.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Endpoints in mice included histopathology, immunohistochemistry, and molecular profiling. GraphPad Prism software, R-studio, and Matlab were used for statistical and data analyses.

RESULTS AND LIMITATIONS

Finasteride treatment of Nkx3.1 mutant mice resulted in a significant reduction in prostatic intraepithelial neoplasia (PIN), as evident from histopathological and expression profiling analyses. Cross-species computational analysis comparing finasteride-treated mice with two independent 5-ARI-treated patient cohorts showed that reduced NKX3.1 expression is predictive of response to 5-ARI. A limitation of the study is that these retrospective human cohorts have relatively few patients with limited clinical outcome data. Future prospective clinical trials are needed to validate whether stratifying patients on the basis of NKX3.1 expression improves the benefit of 5-ARIs during active surveillance.

CONCLUSIONS

This co-clinical study implicates NKX3.1 status as a predictor of response to 5-ARIs, and suggests that molecular features, including NKX3.1 expression, may help to identify PCa patients most likely to benefit from 5-ARIs during active surveillance.

PATIENT SUMMARY

The aim of precision cancer prevention is to tailor interventions on the basis of individualized patient characteristics. We propose that patients with low NKX3.1 expression are optimal candidates for intervention with 5α-reductase inhibitors as an adjunct to active surveillance.

Early dutasteride monotherapy in men with detectable serum prostate-specific antigen levels following radical prostatectomy: A prospective trial

Purpose

To investigate the effects of early administration of dutasteride in patients with detectable serum prostate-specific antigen (PSA) levels after radical prostatectomy (RP).

Materials and Methods

A prospective open-label study, with a cumulative analysis of asymptomatic increase in PSA following RP, was conducted from January 2005 to December 2013. An early increase in PSA level was defined as detectable serum PSA level> 0.04 ng/mL. Patients with PSA level>0.04 ng/mL were treated with dutasteride 0.5 mg daily. Serum PSA level and biochemical recurrence (BCR) were monitored. We divided the patients into 2 groups based on the serum PSA response after dutasteride treatment.

Results

Eighty patients were included in the study. At the median follow-up of 51.8 months, 56 patients (70.0%) showed a decrease of greater than 10% in serum PSA level, and 24 showed increased PSA levels. Twelve of the 56 patients with PSA response showed subsequently increased PSA. Intergroup differences in preoperative PSA levels, PSA nadir levels, and Gleason score of 6 or less were significant (p=0.028, p=0.030, and p=0.035, respectively). A multivariate analysis revealed that Gleason score of 6 or less (p=0.018) and PSA nadir levels (p=0.011) were predictive factors for PSA response after early dutasteride treatment in men with increased PSA levels following RP.

Conclusions

Early monotherapy of dutasteride showed a decline in serum PSA levels in men with lower nadir PSA levels, and a Gleason score 6, when the serum PSA was detected after RP.

Is There a Future for Chemoprevention of Prostate Cancer?

The outcome of the Selenium and Vitamin E Cancer Prevention Trial, demonstrating harm and no preventive activity of selenomethionine and α-tocopherol for prostate cancer, and the lack of approval by the FDA for the use of 5α-reductase inhibitors to prevent prostate cancer have cast doubt about the future of chemoprevention of prostate cancer. This article attempts to critically assess whether the notion that chemoprevention of prostate cancer has no future is warranted. Risk of prostate cancer is modifiable and chemoprevention of prostate cancer, particularly fatal/lethal cancer, is both needed and possible. However, the approach to prostate cancer-chemopreventive agent development has not followed a rational and systematic process. To make progress, the following steps are necessary: (i) identification of intermediate biomarkers predictive of fatal/lethal disease; (ii) development of a rational approach to identification of candidate agents, including high-throughput screening and generation of information on mechanism and biology of candidate agents and potential molecular targets; and (iii) systematic evaluation of the predictive value of preclinical models, phase II trials, and intermediate biomarkers for the outcome of phase III trials. New phase III trials should be based on adequate preclinical and phase II studies. Cancer Prev Res; 9(8); 642-7. ©2016 AACR.

Tissue Effects in a Randomized Controlled Trial of Short-term Finasteride in Early Prostate Cancer

BACKGROUND

In the Prostate Cancer Prevention Trial, finasteride selectively suppressed low-grade prostate cancer and significantly reduced the incidence of prostate cancer in men treated with finasteride compared with placebo. However, an apparent increase in high-grade disease was also observed among men randomized to finasteride. We aimed to determine why and hypothesized that there is a grade-dependent response to finasteride.

METHODS

From 2007 to 2012, we randomized dynamically by intranet-accessible software 183 men with localized prostate cancer to receive 5mg finasteride or placebo daily in a double-blind study during the 4-6weeks preceding prostatectomy. As the primary end point, the expression of a predefined molecular signature (ERβ, UBE2C, SRD5A2, and VEGF) differentiating high- and low-grade tumors in Gleason grade (GG) 3 areas of finasteride-exposed tumors from those in GG3 areas of placebo-exposed tumors, adjusted for Gleason score (GS) at prostatectomy, was compared. We also determined androgen receptor (AR) levels, Ki-67, and cleaved caspase 3 to evaluate the effects of finasteride on the expression of its downstream target, cell proliferation, and apoptosis, respectively. The expression of these markers was also compared across grades between and within treatment groups. Logistic regression was used to assess the expression of markers.

FINDINGS

We found that the predetermined molecular signature did not distinguish GG3 from GG4 areas in the placebo group. However, AR expression was significantly lower in the GG4 areas of the finasteride group than in those of the placebo group. Within the finasteride group, AR expression was also lower in GG4 than in GG3 areas, but not significantly. Expression of cleaved caspase 3 was significantly increased in both GG3 and GG4 areas in the finasteride group compared to the placebo group, although it was lower in GG4 than in GG3 areas in both groups.

INTERPRETATION

We showed that finasteride's effect on apoptosis and AR expression is tumor grade dependent after short-term intervention. This may explain finasteride's selective suppression of low-grade tumors observed in the PCPT.

The DHEA-sulfate depot following P450c17 inhibition supports the case for AKR1C3 inhibition in high risk localized and advanced castration resistant prostate cancer

Prostate cancer is the second leading cause of cancer death in the United States. Treatment of localized high-risk disease and de novo metastatic disease frequently leads to relapse. These metastatic castration resistant prostate cancers (mCRPC) claim a high mortality rate, despite the extended survival afforded by the growing armamentarium of androgen deprivation, radiation and immunotherapies. Here, we review two studies of neoadjuvant treatment of high-risk localized prostate cancer prior to prostatectomy, the total androgen pathway suppression (TAPS) trial and the neoadjuvant abiraterone acetate (AA) trial. These two trials assessed the efficacy of the non-specific P450c17 inhibitor, ketoconazole and the specific P450c17 inhibitor, AA, to inhibit tissue and serum androgen levels. Furthermore, a novel and validated stable isotope dilution liquid chromatography electrospray ionization selected reaction monitoring mass spectrometry assay was used to accurately quantify adrenal and gonadal androgens in circulation during the course of these trials. The adrenal androgens, Δ(4)-androstene-3,17-dione, dehydroepiandrosterone and dehydroepiandrosterone sulfate were significantly reduced in the patients receiving ketoconazole or AA compared to those who did not. However, in both trials, a significant amount of DHEA-S (∼20 μg/dL) persists and thus may serve as a depot for intratumoral conversion to the potent androgen receptor ligands, testosterone (T) and 5α-dihydrotestosterone (DHT). The final step in conversion of Δ(4)-androstene-3,17-dione and 5α-androstanedione to T and DHT, respectively, is catalyzed by AKR1C3. We therefore present the case that in the context of the DHEA-S depot, P450c17 and AKR1C3 inhibition may be an effective combinatorial treatment strategy.

Histologic evaluation of human benign prostatic hyperplasia treated by dutasteride: a study by xenograft model with improved severe combined immunodeficient mice

OBJECTIVE

To evaluate histologic change in human prostate samples treated with dutasteride and to elucidate direct effects of dutasteride on human prostate tissue, the present study was conducted by using a xenograft model with improved severe combined immunodeficient (super-SCID) mice, although it is well known that dutasteride reduces prostate volume.

METHODS

After establishment of a xenograft model of human benign prostatic hyperplasia in morphology and function, samples implanted into super-SCID mice with and without dutasteride were evaluated pathohistologically at 2 and 6 months after initiation of dutasteride administration.

RESULTS

The proliferative index evaluated by Ki-67 staining was significantly lower in the dutasteride group than the control at 2 and 6 months after administration. Apoptotic index evaluated by the terminal transferase TdT-mediated dUTP-biotin nick end labeling staining was higher in the dutasteride group than the control at 2 and 6 months after administration. Quick scores in the dutasteride group for staining of both cyclooxygenase-2 (Cox-2) and Ras homolog gene family, member A (RhoA) were significantly lower than those in the control group at 2 and 6 months after administration.

CONCLUSION

Dutasteride inhibits cell proliferation and induces apoptosis of prostatic cells, causing a reduced prostate volume. Furthermore, decreased expression of Cox-2 and RhoA within benign prostatic hyperplasia tissue by dutasteride may induce an early effect on improvement of lower urinary tract symptoms, probably by attenuating inflammation reaction of the prostate and decreasing intraurethral pressure, other than the mechanism of reduced prostate volume.

Intratumoral steroidogenesis in castration-resistant prostate cancer: a target for therapy

Development of castration-resistant prostate cancer (CRPC) in a low androgen environment, arising from androgen deprivation therapy (ADT), is a major problem in patients with advanced prostate cancer (PCa). Several mechanisms have been hypothesized to explain the progression of PCa to CRPC during ADT, one of them is so called persistent intratumoral steroidogenesis. The existence of intratumoral steroidogenesis was hinted based on the residual levels of intraprostatic testosterone (T) and dihydrotestosterone (DHT) after ADT. Accumulating evidence has shown that the intraprostatic androgen levels after ADT are sufficient to induce cancer progression. Several studies now have demonstrated that PCa cells are able to produce T and DHT from different androgen precursors, such as cholesterol and the adrenal androgen, dehydroepiandrosterone (DHEA). Furthermore, up-regulation of genes encoding key steroidogenic enzymes in PCa cells seems to be an indicator for active intratumoral steroidogenesis in CRPC cells. Currently, several drugs are being developed targeting those steroidogenic enzymes, some of which are now in clinical trials or are being used as standard care for CRPC patients. In the future, novel agents that target steroidogenesis may add to the arsenal of drugs for CRPC therapy.

Improving intermittent androgen deprivation therapy: lessons learned from basic and translational research

Intermittent androgen deprivation therapy (IADT) is an alternative to continuous androgen deprivation therapy (ADT) in prostate cancer patients with nonmetastatic disease. ADT is associated with numerous side effects such as hot flashes, sexual dysfunction, anemia, fatigue, loss of muscle mass, osteoporosis, metabolic syndrome and premature cardiovascular disease. IADT was developed with the intention of improving the quality of life and to delay progression of prostate cancer to castration resistance. The benefits of slightly improved quality of life by IADT compared to ADT were demonstrated in multiple clinical trials. IADT was noted to be noninferior to ADT in patients with biochemical recurrence of prostate cancer but in studies performed in patients with metastatic prostate cancer, the results were inconclusive. Our recent studies suggested that the administration of 5 alpha-reductase inhibitors during the off-cycle of IADT can significantly prolong the survival of mice bearing androgen-sensitive prostate tumors when off-cycle duration was short. This review discusses the survival benefit of 5 alpha-reductase inhibition in IADT in animal models and the potential translation of this finding into clinic.

5α-reductase inhibition suppresses testosterone-induced initial regrowth of regressed xenograft prostate tumors in animal models

Androgen deprivation therapy (ADT) is the standard treatment for patients with prostate-specific antigen progression after treatment for localized prostate cancer. An alternative to continuous ADT is intermittent ADT (IADT), which allows recovery of testosterone during off-cycles to stimulate regrowth and differentiation of the regressed prostate tumor. IADT offers patients a reduction in side effects associated with ADT, improved quality of life, and reduced cost with no difference in overall survival. Our previous studies showed that IADT coupled with 5α-reductase inhibitor (5ARI), which blocks testosterone conversion to DHT could prolong survival of animals bearing androgen-sensitive prostate tumors when off-cycle duration was fixed. To further investigate this clinically relevant observation, we measured the time course of testosterone-induced regrowth of regressed LuCaP35 and LNCaP xenograft tumors in the presence or absence of a 5ARI. 5α-Reductase inhibitors suppressed the initial regrowth of regressed prostate tumors. However, tumors resumed growth and were no longer responsive to 5α-reductase inhibition several days after testosterone replacement. This finding was substantiated by bromodeoxyuridine and Ki67 staining of LuCaP35 tumors, which showed inhibition of prostate tumor cell proliferation by 5ARI on day 2, but not day 14, after testosterone replacement. 5α-Reductase inhibitors also suppressed testosterone-stimulated proliferation of LNCaP cells precultured in androgen-free media, suggesting that blocking testosterone conversion to DHT can inhibit prostate tumor cell proliferation via an intracrine mechanism. These results suggest that short off-cycle coupled with 5α-reductase inhibition could maximize suppression of prostate tumor growth and, thus, improve potential survival benefit achieved in combination with IADT.

The mouse as a model to investigate sex steroid metabolism in the normal and pathological prostate

Metabolism of sex steroids within the prostate is an important factor affecting its growth and pathology. Mouse models with genetic gain- and especially loss-of-function have characterised different steroid metabolic pathways and their contribution to prostate pathology. With reference to the human prostate, this review aims to summarize the steroidogenic pathways in the mouse prostate as the basis for using the mouse as a model for intraprostatic steroid signalling. In this review we summarize the current information for three main components of the steroid signalling pathway in the mouse prostate: circulating steroids, steroid receptors and steroidogenic enzymes with regard to signalling via androgen, estrogen, progesterone and glucocorticoid pathways. This review reveals many opportunities for characterisation steroid metabolism in various mouse models. The knowledge of steroid metabolism within prostate tissue and in a lobe (rodent)/region (human) specific manner, will give valuable information for future, novel hypotheses of intraprostatic control of steroid actions. This review summarizes knowledge of steroid metabolism in the mouse prostate and its relevance to the human.

Association of 5α-reductase inhibitor use and pathological features of prostate cancer in men undergoing radical prostatectomy

BACKGROUND

We investigated the association of 5α-reductase inhibitor (5-ARI) treatment with pathologic and biochemical outcome among the contemporary prostate cancer (PCa) patients undergoing radical prostatectomy.

METHODS

We reviewed records of 1,204 men who underwent radical prostatectomy from 2003 to 2010. We estimated association of 5-ARI use with high (≥7) pathologic Gleason score and pathologically nonorgan-confined disease (≥pT3) via logistic regression, and biochemical outcome via Cox proportional hazards regression.

RESULTS

Of 1,204 patients, 50 (4.2%) reported having history 5-ARI treatment before radical prostatectomy. Median duration of 5-ARI treatment among the 50 patients was 23.0 months. When adjusted for various factors including age, body mass index, prostate-specific antigen, clinical stage, biopsy Gleason, and prostate volume, history of 5-ARI treatment was revealed to be significantly associated with high (≥7) pathologic Gleason score (P = 0.015). Also, 5-ARI use was observed to significantly associated with higher rates of extraprostatic extension of tumor (P = 0.005) and seminal vesicle invasion (P = 0.003), respectively, when adjusted for same variables. However, 5-ARI use was not demonstrated to be a significant preoperative predictor of biochemical recurrence-free survival in multivariate analysis (P = 0.528).

CONCLUSIONS

Our results showed 5-ARI treatment may be associated with more aggressive PCa demonstrating higher pathologic Gleason score and advanced pathologic tumor stage in men undergoing radical prostatectomy. However, further investigations via larger-scale, prospective studies would be needed on the actual effect of 5-ARI treatment on PCa-specific morbidity and mortality.

Stellettin A induces endoplasmic reticulum stress in murine B16 melanoma cells

Isomalabaricanes are a small class of rearranged triterpenoids obtained from marine sponges. Most of these are cytotoxic to tumor cells, but the underlying mechanism is not clear. In this study, it was demonstrated that stellettin A (1), obtained from Geodia japonica, inhibited the growth of B16F10 murine melanoma cells by the induction of endoplasmic reticulum stress and accumulation of unfolded proteins. Immunoblotting analysis revealed abnormal glycosylation patterns of two melanoma marker proteins, tyrosinase and tyrosinase-related protein 1, and the retention of these proteins in the endoplasmic reticulum. Compound 1 induced the upregulation of the unfolded protein chaperone, glucose-regulated protein 78, in a dose-dependent manner. Increase of autophagosome-associated protein light chain 3 (LC3) in a membrane-bound form (LC3II) and its immunofluorescence co-localization with tyrosinase suggest the possible removal of deglycosylated and unfolded proteins by autophagy of the cells. There was no change in either the expression of the apoptosis marker protein Bcl-2 or the appearance of apoptotic nuclei in 1-treated cells. Taken together, 1 is an endoplasmic reticulum stressor that inhibits the growth of B16 melanoma cells by induction of abnormal protein glycosylation and autophagy.

Dutasteride in localised prostate cancer management: the REDEEM randomised, double-blind, placebo-controlled trial

BACKGROUND

We aimed to investigate the safety and efficacy of dutasteride, a 5α-reductase inhibitor, on prostate cancer progression in men with low-risk disease who chose to be followed up with active surveillance.

METHODS

In our 3 year, randomised, double-blind, placebo-controlled study, undertaken at 65 academic medical centres or outpatient clinics in North America, we enrolled men aged 48-82 years who had low-volume, Gleason score 5-6 prostate cancer and had chosen to be followed up with active surveillance. We randomly allocated participants in a one-to-one ratio, stratified by site and in block sizes of four, to receive once-daily dutasteride 0·5 mg or matching placebo. Participants were followed up for 3 years, with 12-core prostate biopsy samples obtained after 18 months and 3 years. The primary endpoint was time to prostate cancer progression, defined as the number of days between the start of study treatment and the earlier of either pathological progression (in patients with ≥1 biopsy assessment after baseline) or therapeutic progression (start of medical therapy). This trial is registered with ClinicalTrials.gov, number NCT00363311.

FINDINGS

Between Aug 10, 2006, and March 26, 2007, we randomly allocated 302 participants, of whom 289 (96%) had at least one biopsy procedure after baseline and were included in the primary analysis. By 3 years, 54 (38%) of 144 men in the dutasteride group and 70 (48%) of 145 controls had prostate cancer progression (pathological or therapeutic; hazard ratio 0·62, 95% CI 0·43-0·89; p=0·009). Incidence of adverse events was much the same between treatment groups. 35 (24%) men in the dutasteride group and 23 (15%) controls had sexual adverse events or breast enlargement or tenderness. Eight (5%) men in the dutasteride group and seven (5%) controls had cardiovascular adverse events, but there were no prostate cancer-related deaths or instances of metastatic disease.

INTERPRETATION

Dutasteride could provide a beneficial adjunct to active surveillance for men with low-risk prostate cancer.

FUNDING

GlaxoSmithKline.

Prostate cancers detected during 5α-reductase inhibitor use are smaller, de-differentiated, but confined when compared to controls

Rationale: To compare cancers detected during use of 5α-reductase inhibitors (5αRI) with cancers detected in untreated controls stratified for tumor size.

Methods: Prostate biopsies were performed on 235 consecutive patients “for cause” (elevated or rising PSA, positive digital rectal examination, or focal hypoechoic lesion). Fifty patients were excluded for a prior diagnosis of cancer, leaving 185 as the study group (5αRI=41, control=144). Patients in the 5αRI group had been treated for a mean of 3.5 years. Cancer was ultimately diagnosed in 114/185 patients.

Results: Cancer was diagnosed in 31/41 (76%) of patients treated with 5αRI and 83/144 (58%) of the control group (p=0.04). Control tumors were larger (14.3 mm) than those in 5αRI treated patients (9.4 mm, p=0.0007). No differences in mean PSA or PSA kinetics were detected between groups. For tumors less than 1.0 cm, the proportion of high grade cancers (Gleason 7-10 and Gleason 4+3-10) was higher in 5αRI subjects than in controls (p<0.05). Fewer 5αRI patients had proven extracapsular extension than controls, but this difference did not reach statistical significance (p=0.13). Normal DNA ploidy was more likely to be diagnosed in the 5αRI group versus controls, but this difference was not statistically significant (81% vs. 65%, p=0.14).

Conclusions: Cancers diagnosed in patients presenting “for cause” treated with 5αRI drugs are more likely to be de-differentiated compared to controls. However, these tumors are also smaller and less likely to have extracapsular extension and abnormal DNA ploidy than controls.

The 5 alpha-reductase isozyme family: a review of basic biology and their role in human diseases

Despite the discovery of 5 alpha-reduction as an enzymatic step in steroid metabolism in 1951, and the discovery that dihydrotestosterone is more potent than testosterone in 1968, the significance of 5 alpha-reduced steroids in human diseases was not appreciated until the discovery of 5 alpha-reductase type 2 deficiency in 1974. Affected males are born with ambiguous external genitalia, despite normal internal genitalia. The prostate is hypoplastic, nonpalpable on rectal examination and approximately 1/10th the size of age-matched normal glands. Benign prostate hyperplasia or prostate cancer does not develop in these patients. At puberty, the external genitalia virilize partially, however, secondary sexual hair remains sparse and male pattern baldness and acne develop rarely. Several compounds have been developed to inhibit the 5 alpha-reductase isozymes and they play an important role in the prevention and treatment of many common diseases. This review describes the basic biochemical properties, functions, tissue distribution, chromosomal location, and clinical significance of the 5 alpha-reductase isozyme family.

Intraprostatic testosterone and dihydrotestosterone. Part I: concentrations and methods of determination in men with benign prostatic hyperplasia and prostate cancer

Owing to inconsistencies and methodological differences, the present peer-reviewed literature lacks conclusive data on the intraprostatic levels of androgens, in particular dihydrotestosterone (DHT), in untreated benign prostatic hyperplasia (BPH) and prostate cancer. To date, no difference has been shown between DHT concentrations in normal prostatic tissue and BPH, and nor has a difference been shown in DHT concentrations between the histologically distinct regions of the prostate. Recent literature has also failed to show a consistent difference in androgen level between BPH and prostate cancer. The role of intraprostatic DHT in the pathogenesis of BPH and in the initiation and progression of prostate cancer thus remains to be established. Increased knowledge of the mechanisms of the androgenic steroid pathways in prostatic diseases, with a special focus on intraprostatic androgen levels may lead to more optimized and more personalized forms of treatment, and probably new therapeutic targets as well.

The role of 5-alpha reductase inhibitors in prostate pathophysiology: Is there an additional advantage to inhibition of type 1 isoenzyme?

Normal growth and function of the prostate are contingent on the reduction of testosterone to dihydrotestosterone (DHT) by 5-alpha reductase (5-AR) enzymes types 1 and 2. It has been theorized that an overabundance of DHT may be implicated in the pathogenesis of both benign prostatic hyperplasia (BPH) and prostate cancer. Inhibitors of 5-AR such as dutasteride and finasteride may therefore have an important role in the prevention and treatment of BPH and prostate cancer. Dutasteride provides greater suppression of DHT than finasteride, thereby underlying the hypothesis that inhibition of both type 1 and type 2 would provide correspondingly greater protection than inhibition of type 2 alone. We review the potential significance of the 5-AR inhibitors in reducing the risk of prostate cancer according to the basic biology of prostate disease.

Oral testosterone with and without concomitant inhibition of 5α-reductase by dutasteride in hypogonadal men for 28 days

PURPOSE

Co-administration of the 5α-reductase inhibitor dutasteride increases the oral testosterone bioavailability in men with experimentally induced hypogonadism. We examined oral testosterone with and without dutasteride administration in hypogonadal men for 28 days.

MATERIALS AND METHODS

We randomly assigned 43 hypogonadal men to twice daily oral doses of 150, 250 or 400 mg testosterone with 0.25 mg dutasteride, 400 mg testosterone alone or 0.25 mg dutasteride alone for 28 days in a multicenter study. Subjects underwent pharmacokinetic profiling of serum hormones on days 1 and 28. A total of 32 men completed all study procedures.

RESULTS

Serum testosterone increased in all groups on testosterone compared with that in the dutasteride only group. At the 400 mg dose the combination of testosterone and dutasteride resulted in average testosterone concentrations that were 2.7 and 4.6 times higher than in the testosterone only group on days 1 and 28, respectively (p <0.01). On day 28 average testosterone was 20% to 30% lower in all groups on testosterone and dutasteride, and 50% lower in the testosterone only group compared with day 1. Serum dihydrotestosterone was suppressed in all groups on dutasteride and increased in the testosterone only group.

CONCLUSIONS

Oral testosterone administration resulted in a therapeutic serum testosterone concentration in hypogonadal men. Dutasteride improved the oral bioavailability of testosterone while suppressing dihydrotestosterone. Compared with day 1, testosterone was decreased after 28 days of administration. Additional study is warranted of oral testosterone with dutasteride for testosterone deficiency.

Dutasteride monotherapy in men with serologic relapse following radical therapy for adenocarcinoma of the prostate: a pilot study

OBJECTIVE

The objective of this study was to assess the effect of dutasteride on serum prostate specific antigen (PSA) levels in men with serologic relapse following radical prostatectomy and/or radiation therapy for clinically localized adenocarcinoma of the prostate.

METHODS

A prospective, single institution, IRB approved trial was conducted. Entry criteria required that all participants have serologic disease relapse only with serum PSA levels between 0.4 and 10.0 ng/ml. Enrolled participants were treated with 0.5 mg dutasteride daily. The primary endpoints were serum PSA level and clinical recurrence. The rate of durable decline in PSA was assessed according to the recommendations of the Prostate-Specific Antigen Working Group.

RESULTS

Thirty-five patients provided informed consent and participated in the present study. At a median follow-up duration of 27 months (range, 4-42 months), 46% of enrolled men had a serum PSA decrease of greater than 10%, and 25% had a serum PSA decrease of greater than 50% (P < 0.001). Pre-study PSA doubling time (PSADT) (≥12 months vs. <12 months), and Gleason score (≤6 vs. ≥7) were associated with a better response to dutasteride, but only PSADT was statistically significant (P < 0.001). Thirty percent of patients experienced PSA progression (increase in serum PSA of greater than 50%). Two (6%) patients developed bone metastasis. No patient was removed from the study for drug-related toxicity.

CONCLUSIONS

In the present pilot study, treatment with dutasteride resulted in a significant decrease in serum PSA in men with serologic relapse following radical treatment for adenocarcinoma of the prostate. These data appear to suggest that dutasteride may delay or prevent progression of prostate cancer in some men with biochemical relapse after radical therapy. These findings require confirmation in the setting of a larger, longer trial.

The effect of short-term dutasteride intake in early-stage prostate cancer: analysis of 148 patients who underwent three-dimensional prostate mapping biopsy

OBJECTIVES

The effect of dutasteride on existing prostate cancer volume is largely unknown. In this study, we assessed the impact of dutasteride on tumor burden and Gleason score.

METHODS

A retrospective review of patients from our institution was performed, examining men interested in surveillance for prostate cancer, who underwent transperineal three-dimensional mapping (TP-3DM) biopsy within 3-6 months after their initial cancer diagnosis. The criteria to qualify for TP-3DM biopsy included prostate-specific antigen < 10 ng/mL, Gleason score ≤ 7, ≤ 2 positive cores out of 12. There were 2 cohorts of men--those who took dutasteride daily before the TP-3DM biopsy and those who did not receive any 5ARIs. Upstaging of prostate cancer diagnosis was defined as an increase in one or more positive cores or a change from unilateral to bilateral disease.

RESULTS

From 2006-2008, a cohort of 148 men underwent TP-3DM biopsy of the prostate. Ninety-one men received a treatment regime of dutasteride at least 3 months before TP-3DM biopsy. Fifty-seven men did not receive dutasteride or any other 5ARI. Approximately 74% of men who did not take dutasteride were upstaged and/or upgraded compared with 49.4% of men who received dutasteride (P = .0038).

CONCLUSIONS

We observed a 24.3% decrease in the proportion of upstaging and/or upgrading of prostate cancer in men who received dutasteride at least 3 months before 3D prostate TP-3DM biopsy. Thus, the effect of dutasteride on prostate cancer may have implications for its potential use as a secondary chemoprevention agent.

Effect of dutasteride on the risk of prostate cancer

BACKGROUND

We conducted a study to determine whether dutasteride reduces the risk of incident prostate cancer, as detected on biopsy, among men who are at increased risk for the disease.

METHODS

In this 4-year, multicenter, randomized, double-blind, placebo-controlled, parallel-group study, we compared dutasteride, at a dose of 0.5 mg daily, with placebo. Men were eligible for inclusion in the study if they were 50 to 75 years of age, had a prostate-specific antigen (PSA) level of 2.5 to 10.0 ng per milliliter, and had had one negative prostate biopsy (6 to 12 cores) within 6 months before enrollment. Subjects underwent a 10-core transrectal ultrasound-guided biopsy at 2 and 4 years.

RESULTS

Among 6729 men who underwent a biopsy or prostate surgery, cancer was detected in 659 of the 3305 men in the dutasteride group, as compared with 858 of the 3424 men in the placebo group, representing a relative risk reduction with dutasteride of 22.8% (95% confidence interval, 15.2 to 29.8) over the 4-year study period (P<0.001). Overall, in years 1 through 4, among the 6706 men who underwent a needle biopsy, there were 220 tumors with a Gleason score of 7 to 10 among 3299 men in the dutasteride group and 233 among 3407 men in the placebo group (P=0.81). During years 3 and 4, there were 12 tumors with a Gleason score of 8 to 10 in the dutasteride group, as compared with only 1 in the placebo group (P=0.003). Dutasteride therapy, as compared with placebo, resulted in a reduction in the rate of acute urinary retention (1.6% vs. 6.7%, a 77.3% relative reduction). The incidence of adverse events was similar to that in studies of dutasteride therapy for benign prostatic hyperplasia, except that in our study, as compared with previous studies, the relative incidence of the composite category of cardiac failure was higher in the dutasteride group than in the placebo group (0.7% [30 men] vs. 0.4% [16 men], P=0.03).

CONCLUSIONS

Over the course of the 4-year study period, dutasteride reduced the risk of incident prostate cancer detected on biopsy and improved the outcomes related to benign prostatic hyperplasia. (ClinicalTrials.gov number, NCT00056407.)

Variability in the androgen response of prostate epithelium to 5alpha-reductase inhibition: implications for prostate cancer chemoprevention

Inhibitors of 5alpha-reductase (SRD5A) that lower intraprostatic levels of dihydrotestosterone (DHT) reduce the overall incidence of prostate cancer (PCa), but there is significant variation in chemopreventive activity between individual men. In seeking molecular alterations that might underlie this variation, we compared gene expression patterns in patients with localized PCa who were randomized to prostatectomy alone versus treatment with two different doses of the SRD5A inhibitor dutasteride. Prostatic levels of DHT were decreased by >90% in both dutasteride-treated patient groups versus the untreated patient group. Despite significant and uniform suppression of tissue DHT, unsupervised clustering based on prostatic gene expression did not discriminate these groups. However, subjects could be resolved into distinct cohorts characterized by high or low expression of genes regulated by the androgen receptor (AR), based solely on AR transcript expression. The higher-dose dutasteride treatment group was found to include significantly fewer cancers with TMPRSS2-ERG genetic fusions. Dutasteride treatment was associated with highly variable alterations in benign epithelial gene expression. Segregating subjects based on expression of AR and androgen-regulated genes revealed that patients are differentially sensitive to SRD5A inhibition. Our findings suggest that AR levels may predict the chemopreventive efficacy of SRD5A inhibitors.

Stromal-epithelial interactions are responsible for prostate tumor progression through an androgen-related mechanism

While several hypotheses have been put forward to explain how prostate tumors become resistant to androgen deprivation therapy, the mechanism by which prostate tumors have increased androgen concentrations as compared to the serum has been poorly explored. Using a stromal/epithelial cell co-culture model, Mizokami et al. have demonstrated how prostate-, bone- and prostate tumor-derived stromal cells participate with tumor-derived epithelial cells (i.e., LNCaP cells) to produce active androgens from a readily available substrate during androgen deprivation therapy, dehydroepiandrosterone (DHEA). Although these experiments are conducted in vitro, they provide a basis for the possibility of intratumoral DHEA-mediated androgen synthesis mechanisms that may underlie androgen receptor reactivation during androgen deprivation in many prostate tumors. Moreover, Mizokami et al. have shown that dutasteride, previously considered an SRD5A inhibitor, also inhibits the interplay between stromal and epithelial cells in the synthesis of testosterone. Herein, we summarize this study and comment on therapeutic implications.

Reduced tumor necrosis factor receptor-associated death domain expression is associated with prostate cancer progression

By using LNCaP and its derivative cell lines, we first observed an association between tumor necrosis factor-alpha (TNF-alpha) resistance and hormone independence. Moreover, we found that the expression of tumor necrosis factor receptor-associated death domain (TRADD) was reduced in androgen deprivation-independent cells compared with that in androgen deprivation-dependent cells. TRADD is a crucial transducer for TNF-alpha-induced nuclear factor-kappaB (NF-kappaB) activation. Knocking down TRADD expression in LNCaP cells impaired TNF-alpha-induced NF-kappaB activation and androgen receptor repression, whereas overexpression of TRADD in C4-2B cells restored their sensitivity to TNF-alpha. Finally, we found that androgen deprivation reduces TRADD expression in vitro and in vivo, suggesting that androgen deprivation therapy may promote the development of TNF-alpha resistance by reducing TRADD expression during prostate cancer progression.

Reduction in the risk of prostate cancer: future directions after the Prostate Cancer Prevention Trial

The landmark Prostate Cancer Prevention Trial (PCPT) generated interest in the potential health benefits and cost of reducing prostate cancer risk--specifically, the potential role of 5alpha-reductase inhibitors. However, the PCPT raised several unanswered questions, including the cause and significance of the increased incidence of high-grade tumors associated with finasteride. In the present study, we review the PCPT findings and unanswered questions, next steps in this field, and ongoing prostate cancer prevention trials addressing these unanswered questions. Particular emphasis is placed on the design of the second large-scale trial of a 5alpha-reductase inhibitor, the REduction by DUtasteride of prostate Cancer Events (REDUCE) trial.

Preliminary evaluation of the effect of dutasteride on PCA3 in post-DRE urine sediments: a randomized, open-label, parallel-group pilot study

BACKGROUND

Dutasteride is commonly used in patients that are also at risk for prostate cancer (PCa). Therefore, the influence of dutasteride on PCa markers has to be studied. To date, only the effect of dutasteride on serum prostate-specific antigen (PSA) has been studied. This was the first study to investigate the effect of dutasteride on the new PCa marker PCA3, longitudinally and in a dose dependent manner.

METHODS

From April 25, 2005 to October 31, 2006, 16 subjects with benign prostatic hyperplasia (BPH) and 9 subjects with clinically localized PCa were enrolled at the urological outpatient clinics of one university hospital and one community hospital. Eight subjects with BPH and five with PCa received 0.5 mg dutasteride once daily for 3 months, eight with BPH and four with PCa received 3.5 mg. No subjects were withdrawn because of adverse effects.

RESULTS

In all four groups both 0.5 and 3.5 mg dutasteride had a variable effect on the PCA3 score. In contrast, its other effects were consistent as it rapidly reduced serum DHT by >or=90%, over time increased serum T by 20-30%, over time halved serum PSA and decreased prostate volume by 10-16%.

CONCLUSIONS

In this exploratory/pilot study the effect of dutasteride on the PCA3 score was variable. This should be taken into account while using PCA3 in diagnostics. As this study was exploratory, the influence of androgen-deprivation therapy on the PCA3 score should be analyzed further.

Key targets of hormonal treatment of prostate cancer. Part 2: the androgen receptor and 5alpha-reductase

OBJECTIVE

The inhibition of 5alpha-reductase (5AR) blocks the synthesis of the most powerful intracellular androgen, dihydrotestosterone (DHT). The prostate has two 5AR isoenzymes (5AR1 and 5AR2) that change in expression and cellular location during the development of prostate cancer and tumour progression. The objective of this review is to provide an understanding of the pharmacological properties and the potential clinical benefits of 5AR inhibition.

METHODS

We searched Pubmed for data obtained from pharmacological, preclinical and clinical studies.

RESULTS

5AR1 expression increases with increasing aggressiveness and extension of malignant prostatic disease. Conversely, 5AR2 expression decreases from benign prostatic tissue to localized prostate cancer. The efficacy of 5AR2 monotherapy with finasteride alone or in combination with an androgen receptor antagonist on more final outcome measures seems to be limited. Combining an androgen receptor antagonist with a 5AR inhibitor in patients with asymptomatic, locally advanced or recurrent prostate cancer might be a reasonable first therapeutic hormonal approach. As plasma testosterone levels are maintained, beneficial effects on quality of life, potency and sexual function are expected. From studies on the dual 5AR inhibitor dutasteride, the drug produces a biochemical response in some men who progressed under androgen-deprivation therapy, and is generally well tolerated.

CONCLUSIONS

Achieving more potent suppression of intracellular DHT synthesis by 5AR inhibition is expected to provide clinical benefit to patients. Previous studies have shown that 5AR inhibition, by dutasteride in particular, halts/delays the progression of disease, and might even cause regression of disease in patients with advanced prostate cancer.

A broader role for 5ARIs in prostate disease? Existing evidence and emerging benefits

5ARIs are recommended for men who have moderate-to-severe lower urinary tract symptoms (LUTS) and benign prostatic enlargement (BPE) secondary to benign prostatic hyperplasia. Studies have confirmed the utility of combining 5ARIs with alpha-blockers; the MTOPS study showed that risk of overall clinical progression was significantly reduced after 4.5 years with combination therapy (finasteride/doxazosin) in comparison with either monotherapy, while the ongoing CombAT trial (dutasteride/tamsulosin) has for the first time shown benefit in improving symptoms for combination therapy over monotherapies within 12 months of treatment. Data also suggest roles for 5ARIs in prostate cancer. Several studies indicate that treatment with a 5ARI improves the performance of PSA testing for identifying men with prostate cancer, while the PCPT showed a significant reduction in the risk of developing prostate cancer with finasteride. However, widespread use of finasteride in this setting has been tempered by an apparent increase in high-grade disease observed in the study. The ongoing REDUCE study will provide further insight into prostate cancer prevention with 5ARIs. 5ARI-containing regimens may have utility as less aggressive treatment options for patients who only have rising PSA after definitive local therapy, and in patients with disease resistant to androgen deprivation therapy who have PSA progression. Current evidence therefore shows that 5ARIs are effective in treating LUTS/BPE and preventing disease progression, and may also have a role in the prevention of prostate cancer. The overlap between BPE and prostate cancer may allow a more unified approach to managing these conditions, with 5ARIs having a central role.

Overexpression of 5 alpha-reductase type 1 increases sensitivity of prostate cancer cells to low concentrations of testosterone

INTRODUCTION

Conversion of testosterone to dihydrotestosterone (DHT) by the enzymes 5 alpha-reductase types 1 (5 alpha R1) and 2 (5 alpha R2) is important for normal and pathological growth of the prostate. The predominant isoenzyme in normal prostate is 5 alpha R2. However, prostate cancer (PCa) development is accompanied by a decrease in 5 alpha R2 and an increase in 5 alpha R1. The biological significance of increased 5 alpha R1 expression is not fully understood. Therefore, the aim of this study was to determine the effect of overexpression of 5 alpha R1 on growth and prostate-specific antigen (PSA) production in PCa cells.

MATERIALS AND METHODS

LNGK-9 PCa cells, transiently transfected with pTRE-5 alpha R1 or pTRE alone, were cultured in the presence or absence of testosterone at varying concentrations. Cell growth and PSA secretion were measured after 4-6 days. Cyclin E1, Ki67, and PSA mRNA levels were evaluated using RT-PCR after 24 hr of treatment.

RESULTS

10 pM testosterone increased growth of pTRE-5 alpha R1 transfectants by 54.1% over cells grown in the absence of testosterone, compared to 25.0% in pTRE transfectants (P < 0.01). Likewise, PSA secretion was increased by 56-fold in pTRE-5 alpha R1 transfectants treated with 10 pM testosterone, compared to 26-fold in pTRE transfectants (P < 0.01). At concentrations of testosterone above 10 pM, the stimulatory effect on growth and PSA secretion was not distinguishable between pTRE-5 alpha R1 and pTRE transfectants.

CONCLUSIONS

These results demonstrate that upregulation of 5 alpha R1 enhances the cellular response to low, but not high, concentrations of testosterone. This explains one mechanism by which castration-recurrent PCa can proliferate in the presence of castrate levels of circulating testosterone.

Can dutasteride delay or prevent the progression of prostate cancer in patients with biochemical failure after radical therapy? Rationale and design of the Avodart after Radical Therapy for Prostate Cancer Study

OBJECTIVE

To describe the Avodart after Radical Therapy for prostate cancer Study (ARTS), investigating the use of dutasteride (a dual 5alpha-reductase inhibitor that suppresses intraprostatic dihydrotestosterone, reduces tumour volume and improves other markers of tumour regression in prostate cancer) to prevent or delay disease progression in patients with biochemical recurrence after therapy with curative intent.

PATIENTS AND METHODS

An increasing serum prostate-specific antigen (PSA) level after radical prostatectomy (RP) or radiotherapy (RT) is indicative of recurrent prostate cancer and typically pre-dates clinically detectable metastatic disease by several years. ARTS is an ongoing European multicentre trial in which patients are stratified by previous therapy (RP with or without salvage RT vs primary RT) and randomized to double-blind treatment with dutasteride 0.5 mg or placebo once daily for 2 years. Eligible patients will have a PSA doubling time (DT) of 3-24 months. Biochemical recurrence is defined as three increases in PSA level from the nadir, with each increase > or =4 weeks apart and each PSA level > or =0.2 ng/mL, and a final PSA level of > or =0.4 ng/mL (after RP) or > or =2 ng/mL (after primary RT). Study endpoints include time to PSA doubling, time to disease progression, treatment response (PSA decrease or an increase of < or =15% from baseline), changes in PSA and PSADT, and changes in anxiety (Memorial Anxiety Scale for Prostate Cancer). CONCLUSIONS ARTS: will be the first study to evaluate the effects of dutasteride on PSADT, disease progression and treatment response in patients with biochemical failure after RP or RT, and should help to elucidate the potential role of dual 5alpha-reductase inhibition in prostate cancer.

Transcriptome sequencing to detect gene fusions in cancer

Recurrent gene fusions, typically associated with hematological malignancies and rare bone and soft tissue tumors1, have been recently described in common solid tumors2–9. Here we employ an integrative analysis of high-throughput long and short read transcriptome sequencing of cancer cells to discover novel gene fusions. As a proof of concept we successfully utilized integrative transcriptome sequencing to “re-discover” the BCR-ABL110 gene fusion in a chronic myelogenous leukemia cell line and the TMPRSS2-ERG2,3 gene fusion in a prostate cancer cell line and tissues. Additionally, we nominated, and experimentally validated, novel gene fusions resulting in chimeric transcripts in cancer cell lines and tumors. Taken together, this study establishes a robust pipeline for the discovery of novel gene chimeras using high throughput sequencing, opening up an important class of cancer-related mutations for comprehensive characterization.

5alpha-Reductase inhibitor treatment of prostatic diseases: background and practical implications

This literature review discusses the theoretical background of 5alpha-reductase inhibitor (5ARI) treatment and the resulting clinical implications. A Medline-based search for peer-reviewed articles addressing 5ARIs, benign prostatic hyperplasia and prostate cancer was performed. The 5ARIs Finasteride and Dutasteride, which specifically inhibit the production of dihydrotestosterone by acting as competitive inhibitors of 5alpha-reductase, are clinically well tolerated and represent an effective treatment option for benign prostatic obstruction. Finasteride is the first compound which has a proven efficacy in chemoprevention of prostate cancer. The aim of this review was to elucidate, if there are sufficient data available to point out clinically relevant differences between the drugs. Both compounds achieve a significant reduction of prostate volume, an improvement of symptoms and a lower risk of acute urinary retention. Whether the different pharmacokinetic and pharmacodynamic properties of Finasteride and Dutasteride are of clinical importance cannot be judged at this time.

[Histological modifications observed in prostate after preserving treatments for prostate cancer and their impact on Gleason score interpretation]

Total prostatectomy remains the main treatment for intermediate risk prostate cancer with a life expectancy greater than 10 years. In other cases non-surgical treatments can be proposed: external radiotherapy (exclusive or combined anti-androgen therapy), brachytherapy with permanent implants, high frequency ultrasounds (HIFU, Ablatherm), cryotherapy or exclusive hormonal treatment. For such patients in case of biological recurrence, prostate biopsies are usually performed in order to affirm the local recurrence. The histological confirmation of persistent tumor is usually required before any treatment: salvage surgery, cryotherapy, and brachytherapy or high intensity focused ultrasound (HIFU). Pathologists must be aware of the histological modifications induced by these different treatments in order to ensure an optimal interpretation of the biopsies. In this review, we describe the modifications observed in the normal prostate and in cancers after these various therapeutic methods, and also after alpha reductase inhibitors proposed as treatment of benign prostate hypertrophy and prostate cancer chemoprevention.