Effects of serum testosterone levels after 6 months of androgen deprivation therapy on the outcome of patients with prostate cancer. Clin Genitourin Cancer. 2013;11:325-330.e1. [PMID: 23531429 DOI: 10.1016/j.clgc.2013.01.002]

Methods for Evaluating the Efficacy of Medical Castration: A Systematic Review

Measuring serum testosterone determination during medical castration is recommended by prostate cancer (PCa) guidelines to assess its efficacy and define castration resistance. It has been suggested that other biochemical compounds, such as free testosterone or luteinising hormone (LH), could also assess castration efficacy. We aimed to analyse the current evidence for serum biochemical compounds that could be appropriate candidates for evaluating medical castration efficacy. A systematic review was conducted after two investigators independently searched the literature in the PubMed, Cochrane Library, and EMBASE databases published between January 1980 and February 2023. Their searches used the medical subject headings 'prostatic neoplasms', 'testosterone and androgen antagonists', 'gonadotropin-releasing hormone/analogues and derivatives', 'free testosterone', and 'luteinising hormone'. Studies were selected according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria, and their eligibility was based on the Participants, Intervention, Comparator, and Outcome strategy. The search was limited to original articles published in English. Among the 6599 initially identified titles, 15 original studies analysing the clinical impact of serum testosterone levels in PCa patients undergoing androgen deprivation therapy (ADT) were selected for evidence acquisition. The risk of bias in individual studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. All selected studies used immunoassays to measure serum testosterone, although only methods based on liquid or gas chromatography and mass spectrometry are recommended to measure low testosterone concentrations. The reported series were not uniform in clinical stage, ADT types, and the time or number of serum testosterone measurements. Only some studies found low serum testosterone levels (<20 or <32 ng/dL) associated with greater survival free of biochemical progression and castration resistance. We conclude that little current evidence justifies the measurement of serum testosterone during ADT using no appropriate methods. No reported longitudinal studies have examined the clinical impact of serum testosterone measured using liquid chromatography with tandem mass spectrometry (LC-MSMS), free testosterone, or LH in PCa patients undergoing medical castration. We conclude that well-designed longitudinal studies examining the clinical impact of serum testosterone measured with LC-MSMS, serum-free testosterone, and LH on biochemical progression and castration resistance in PCa patients undergoing neo-adjuvant castration in radiation therapy or continuous castration are needed.

Mass spectrometry redefines optimal testosterone thresholds in prostate cancer patients undergoing androgen deprivation therapy

BACKGROUND

Androgen deprivation therapy (ADT) is the standard of care for prostate cancer treatment. Studies suggest that patients with testosterone levels below 0.7 nM have a longer time to castration resistance. Using the most accurate testosterone measurement method, namely mass spectrometry (MS), we sought to determine if a lower testosterone level under ADT could be associated with longer time to castration resistance.

METHODS

This retrospective study included 138 prostate cancer patients undergoing noncurative continuous ADT for which we had access to testosterone measurements assessed by MS. For 108 samples, paired immunoassays (IA) testosterone measurement was available. Primary outcome was time to castration-resistant prostate cancer (CRPC). The Contal and O'Quigley method was used to determine the optimal testosterone castration cut-off point considering the outcome and time-to-event variables. Relationship between testosterone levels assessed either by IA or MS and time to CRPC was evaluated using Cox regression.

RESULTS

Mean testosterone level was 0.370 nM by IA and 0.275 nM as assessed by MS. The optimal testosterone cut-off point identified to predict time to CRPC was of 0.705 nM for IA and of 0.270 nM for MS. While no significant difference for time to CRPC was found between patients showing IA testosterone level ≥0.705 nM versus <0.705 nM (hazard ratio [HR]: 1.579; 95% confidence interval [CI]: 0.908-2.745), patients with MS testosterone ≥0.270 nM had an increased risk of progression to CRPC compared to MS testosterone <0.270 nM in univariate (HR: 1.717; 95% CI: 1.160-2.541) and multivariate analysis (HR: 1.662; 95% CI: 1.043-2.648).

CONCLUSIONS

The higher sensitivity of MS testosterone measurement methods allows the identification of a lower castration threshold and leads to early identification of patients more likely to progress to CRPC. These patients would likely benefit from treatment intensification by androgen receptor axis-targeted therapies to delay disease progression.

Overall survival and cancer-specific survival were improved in local treatment of metastatic prostate cancer

Background

For metastatic prostate cancer (mPCa), radical prostatectomy (RP) and radiation therapy (RT) may improve overall survival (OS) and cancer-specific survival (CSS). Compared with RT, RP shows significant advantages in improving patient outcomes. External beam radiation therapy (EBRT) even slightly elevates CSM with no statistical difference in OS compared with no local treatment (NLT).

Objective

To evaluate OS and CSS after local treatment (LT) (including RP and RT) versus NLT in mPCa. Design, setting, and participants Within the Surveillance, Epidemiology and End Results (SEER) database (2000-2018), 20098 patients with metastatic prostate cancer were selected in this study, of which 19433 patients had no local treatment, 377 patients with radical prostate treatment, and 288 patients with RT.

Outcome measurements and statistical analysis

Multivariable competing risks regression analysis after propensity score matching (PSM) was used to calculate CSM. Multivariable Cox regression analysis was used to identify the risk factors. Kaplan-Meier methods were used to calculate OS.

Results and limitations

A total of 20098 patients were included: NLT (n = 19433), RP (n=377) and RT (n=288). In a competing risk regression analysis after PSM (ratio 1:1), RP resulted in a significantly lower CSM (hazard ratio [HR] 0.36, 95% confidence interval [CI] 0.29-0.45) than NLT, while RT showed a slightly lower CSM (HR 0.77, 95% CI 0.63-0.95). In a competing risk regression analysis after PSM (ratio 1:1), RP led to a lower CSM (HR 0.56, 95% CI 0.41-0.76) versus RT. As for all-cause mortality (ACM), RP (HR 0.37, 95% CI 0.31-0.45) and RT (HR 0.66, 95% CI 0.56-0.79). also showed a downward trend. In terms of OS, RP and RT significantly improved the survival probability compared with NLT, with the effect of RP being more pronounced. Obviously, older age, Gleason scores ≥8, AJCC T3-T4 stage, AJCC N1, AJCC M1b-M1c were all associated with higher CSM (P <0.05). The same results held true for ACM. The limitation of this article is that it is not possible to assess the effect of differences in systemic therapy on CSM in mPCa patients and clinical trials are needed to verify the results.

Conclusions

For patients with mPCa, both RP and RT are beneficial to patients, and the efficacy of RP is better than RT from the perspective of CSM and ACM. Older age, higher gleason scores and the more advanced AJCC TNM stage all put patients at higher risk of dying.

Patient summary

A large population-based cancer database showed that in addition to first-line therapy (hormonal treatment), RP and radiotherapy can also benefit patients with mPCa.

[Management of testosterone in advanced hormone-sensitive prostate cancer: still up to date?]

Androgen-deprivation therapy (ADT) is the standard therapy used for advanced or metastatic prostate cancer, either alone or in association with additional procedures and substances. The optimum value of testosterone postulated more than 40 years ago was arbitrarily set to be < 50 ng/dL or < 1.7 nmol/L and, from today's perspective, was defined by more insensitive measurement methods. Since then, more and more data has been generated, suggesting that a value of < 20 ng/dL would be prognostically relevant. Yet no guideline has been changed so far despite the call for lowering the target value. Measuring testosterone to evaluate the response to androgen suppression is not yet established in clinical routine. There are no specific recommendations in national and international guidelines. Based on the evolving evidence, the question about testosterone management during ADT is gaining importance. The current data is summarised in this paper.

Testosterone Therapy in Advanced Prostate Cancer

Androgen deprivation therapy is a mainstay of advanced prostate cancer (PCa) but the resulting low testosterone levels leave men susceptible to a multitude of adverse effects. These can include vasomotor symptoms, reduced sexual desire and performance, and mood changes. Testosterone therapy (TTh) in advanced PCa has historically been contraindicated since Huggins and Hodges reported that testosterone activates PCa. Although TTh has been demonstrated to be safe in patients who have undergone treatment for localized PCa, there is extremely limited evidence on its safety in advanced PCa. Despite the lack of evidence, some men with advanced PCa still inquire about TTh, and recent publications have described its use. In this article, we review the potential implications of TTh in men with advanced PCa, defined here as biochemical recurrence after localized therapy or metastatic PCa that is either hormone sensitive or castration resistant.

Prognostic value of testosterone castration levels following androgen deprivation and high-dose radiotherapy in localized prostate cancer: Results from a phase III trial

BACKGROUND/OBJECTIVE

The optimal prognostic value of testosterone following androgen deprivation therapy (ADT) is controversial. We studied the effect of serum testosterone levels on clinical outcome in localized prostate cancer (PCa) treated with ADT and high-dose radiotherapy (HRT).

PATIENTS AND METHODS

The DART01/05 trial randomized 355 men with intermediate and high-risk PCa to 4 months of ADT plus HRT (STADT, N = 178) or the same treatment followed by 24 months of ADT (LTADT, N = 177). This study included patients treated with LTADT who had at least 3 determinations of testosterone during ADT (N = 154). Patients were stratified into 3 subgroups by testosterone level: minimum <20 ng/dL; median 20-49 ng/dL; and maximum ≥50 ng/dL. Kaplan-Meyer and Cox regression analysis were used for overall survival (OS) and Fine & Gray regression model for metastasis free survival (MFS), biochemical disease-free survival (bDFS) and time to TT recovery.

RESULTS

There were no statistically significant differences in 10-year bDFS, MFS, or OS between the <20 ng/mL and 20-49 ng/dL subgroups. Multivariate analysis showed that a median testosterone ≥50 ng/dL was significantly associated with a decrease in bDFS (HR: 6.58, 95%CI 1.28-33.76, p = 0.03). Time to testosterone recovery after ADT did not correlate with bDFS, MFS, or OS and was not significantly associated with any of the testosterone subgroups.

CONCLUSIONS

Our results do not support the concept that additional serum testosterone suppression below 20 ng/dL is associated with better outcomes than 20-49 ng/dL. Time to testosterone recovery after ADT and HRT did not impact clinical failure.

Effectiveness and Distribution of Testosterone Levels within First Year of Androgen Deprivation Therapy in a Real-World Setting: Results from the Non-Interventional German Cohort LEAN Study

BACKGROUND

Observational studies generate information on real-world therapy and complement data from prospective randomized trials. LEAN is an open-label, non-interventional, multi-centre, German cohort study on leuprorelin in routine clinical practice.

OBJECTIVES

To extend knowledge on the use, effectiveness, and tolerability of HEXAL/Sandoz leuprorelin (in this article, the term Leuprone® HEXAL® covers Leuprorelin Sandoz® as well) solid implant in patients with prostate cancer (PCa) in a real-world setting.

METHODS

959 PCa patients scheduled for androgen deprivation therapy (ADT) received leuprorelin acetate implant. Metabolism, serum prostate-specific antigen (PSA), and testosterone data, if available, were collected at baseline and follow-up visits for ≥12 months.

RESULTS

Of 694 patients in the modified full analysis set, 26.4% received GnRH analogues ≤6 months before enrolment. Fifty-one percent of patients were treated for locally advanced or metastatic PCa. In 19.6% of patients, ADT was used in neoadjuvant or adjuvant settings and in 28.5% with rising PSA after definite therapy. Testosterone levels <0.5 ng/mL were achieved in >90% of patients. Safety profile was in line with the summary of product characteristics. Therapy was well tolerated, with patient-triggered therapy discontinuation in 3.6%.

CONCLUSIONS

This interim analysis confirmed previous efficacy findings for leuprorelin implant in a real-world setting. This contemporary cohort showed a shift in the use of ADT to non-metastatic PCa stages.

Polymorphisms in androgen metabolism genes with serum testosterone levels and prognosis in androgen-deprivation therapy

OBJECTIVE

Androgen metabolism is a key component in therapeutic resistance to androgen deprivation therapy (ADT). This study aimed to reveal the significance of genetic polymorphisms in genes involved in androgen metabolism, including CYP17A1, AKR1C3, and HSD17B, on serum testosterone levels during ADT, as well as the prognosis of men undergoing ADT for metastatic prostate cancer (CaP).

MATERIALS AND METHODS

This study included 104 Japanese patients with metastatic CaP, for whom serum testosterone data during ADT were available for 80 patients. The association of CYP17A1 (rs743572), AKR1C3 (rs12529), HSD17B1 (rs605059), HSD17B3 (rs2066479), and HSD17B4 (rs7737181) with serum testosterone levels during ADT and prognosis (progression-free survival and overall survival) was examined. Enzymatic activity in AKR1C3 H5Q was examined using recombinant protein.

RESULTS

Homozygous wild-type (GG allele; median [interquartile range], 12.0 ng/ml [8.0-19.0 ng/ml]) AKR1C3 rs12529 was associated with higher serum testosterone levels during ADT compared with variant-type (GC/CC alleles; median [interquartile range], 9.0 ng/ml [6.4-10.8 ng/ml]). Consistently, variant-type (GC/CC alleles) AKR1C3 rs12529 showed significantly lower risk of progression (hazard ratio [95% confidence interval], 0.47 [0.24-0.96], P = 0.039) compared with homozygous wild-type (GG allele) on multivariate analysis. Meanwhile, other genetic variations were associated with neither serum testosterone during ADT nor prognosis. Enzyme activity of wild-type AKR1C3 was comparable to the H5Q mutant.

CONCLUSIONS

Taken together, this study demonstrated that AKR1C3 polymorphism, which was associated with serum testosterone levels during ADT, may be a prognostic factor of the progression to castration-resistant prostate cancer in Japanese men with metastatic CaP.

Subcutaneous in situ gel delivered leuprolide acetate's consistent and prolonged drug delivery maintains effective testosterone suppression independent of age and weight in men with prostate cancer

Objectives

To assess the impact of patient age and weight on the pharmacokinetics (PK), testosterone (T) suppression and safety from four fixed dosing regimens (7.5, 22.5, 30, or 45 mg for 1‐, 3‐, 4‐, or 6‐months, respectively) of subcutaneous in situ gel delivered leuprolide acetate (Gel‐LA) injected via the ATRIGEL Delivery System in patients with prostate cancer (PCa).

Patients and methods

Two patient populations were specified for analysis: a small cohort of surgically castrated PCa patients and a large, pooled population of PCa patients from four pivotal trials of Gel‐LA. Two separate analyses of the impact of age and weight on study endpoints were conducted: (1) PK and safety of a single monthly dose of Gel‐LA in a Phase 1 study with PCa patients who had undergone bilateral surgical orchiectomy (“Bilaterally orchiectomized male study”); (2) PK/pharmacodynamic (PD) effects and safety using pooled data from four pivotal trials assessing 1‐, 3‐, 4‐, and 6‐month dosing of Gel‐LA in patients with advanced PCa, stratified by age and body weight (pivotal trials).

Results

Eight orchiectomized patients from the “Bilaterally orchiectomized male study” and 438 patients from the pivotal trials were included in the analyses. Age and body weight did not appear to affect the PK results in the orchiectomized patient population. Pooled pivotal trial data showed that serum T levels did not appear to be influenced by age or weight; ≥90% of patients across all age groups and ≥92% of patients across all weight groups achieved T ≤ 50 ng/dL by week 4. Median T levels for castration (T ≤ 50 ng/dL) were maintained from week 3 until the end of the study and all subgroups achieved median T ≤ 20 ng/dL by week 4. Patients from the orchiectomized patient study did not report any serious treatment‐related adverse events (AEs) and there were no AE‐related withdrawals from the study. The most common AEs were hot flashes and injection site events. The safety profiles from pivotal trials have been previously described and, as expected, were consistent with known effects of LHRH agonist therapy and suppression of T levels.

Conclusion

PK and PD of Gel‐LA appear to be unaffected by age and body weight, as demonstrated by persistence of effective drug levels through the dosing period and consistent T suppression across different ages and body weights.

Higher serum testosterone levels predict poor prognosis in castration-resistant prostate cancer patients treated with docetaxel

BACKGROUND

The role of testosterone as a prognostic factor for castration-resistant prostate cancer treated with docetaxel in Japan was investigated.

METHODS

A total of 164 patients with castration-resistant prostate cancer who received docetaxel treatment at Chiba University Hospital and an affiliated hospital were retrospectively analyzed. Testosterone and other clinical factors at the start of docetaxel treatment were evaluated with respect to overall survival and progression-free survival.

RESULTS

Of the 164 patients, 69 had high-volume tumors. The median prostatic-specific antigen was 27.0 ng/mL. The median testosterone was 13.0 ng/dL. The rates of bone and visceral metastases were 80.1% and 8.8%, respectively. For progression-free survival, testosterone ≥13 ng/dL was an independent prognostic factor only on univariate analysis (hazard ratio, 1.81; P = .0108). For overall survival, testosterone ≥ 1.3 ng/dL (hazard ratio, 3.37; P < .0001), high volume (hazard ratio, 3.06; P = .0009), and prostate-specific antigen ≥ 27.0 ng/mL (hazard ratio, 2.75; P = .0013) were independent prognostic factors on multivariate analysis. When assessing related clinical factors, higher serum testosterone was associated with visceral metastasis, high volume, and prostate-specific antigen. Based on three prognostic factors (testosterone, high volume, prostate-specific antigen), a risk classification was developed. The high-risk group (3 risk factors) showed a significantly shorter overall survival compared to the moderate-risk (2 risk factors) and low-risk (0-1 risk factor) groups (P < .0001).

CONCLUSIONS

The present study identified higher serum testosterone (≥13 ng/dL) as a significant prognostic factor in castration-resistant prostate cancer patients treated with docetaxel therapy.

Measuring testosterone and testosterone replacement therapy in men receiving androgen deprivation therapy for prostate cancer: A survey of UK uro-oncologists' opinions and practice

AIM

To explore the practice and attitudes of uro-oncologists in the UK regarding monitoring testosterone levels and the use of testosterone replacement therapy (TRT) in their prostate cancer patients treated with androgen deprivation therapy (ADT).

METHODS

An expert-devised online questionnaire was completed by the members of the British Uro-oncology Group (BUG).

RESULTS

Of 160 uro-oncologists invited, 84 completed the questionnaire. Before initiating ADT in patients with non-metastatic prostate cancer, only 45% of respondents measured testosterone levels and 61% did not measure testosterone at all during ADT in the adjuvant or neoadjuvant setting. However, in men with metastatic prostate cancer, 71% of the uro-oncologists measured testosterone before starting ADT and the majority continued testing during treatment. Approximately two-thirds of respondents did not prescribe TRT for their patients who were in remission following neo(adjuvant) ADT and who had castration levels of testosterone.

DISCUSSION

Among UK uro-oncologists, the measurement of testosterone levels before and during ADT was not typically part of routine practice in the management of patients with prostate cancer. However, testosterone levels were checked more frequently for patients with metastatic disease than disease at an earlier stage. Testing could be conducted in parallel with PSA measurement as testosterone levels are linked to biochemical failure. The majority of specialists participating in the survey did not prescribe TRT for their patients in remission following ADT.

CONCLUSION

Uro-oncologists in the UK do not generally measure testosterone as part of their patient management and they remain cautious about the possible benefits of TRT in men with prostate cancer.

Prognostic significance of castrate testosterone levels for patients with intermediate and high risk prostate cancer

BACKGROUND

Testosterone level of < 50 ng/dL has been used to define castrate level after surgery or after androgen deprivation treatment (ADT) in metastatic prostate cancer (PC).

AIM

To evaluate the effect of two different castrate testosterone levels, < 50 and < 20 ng/dL, on biochemical relapse free survival (BRFS) in patients with non-metastatic intermediate and high risk PC receiving definitive radiotherapy (RT) and ADT.

METHODS

Between April 1998 and February 2011; 173 patients with intermediate and high risk disease were treated. Radiotherapy was delivered by either three-dimensional-conformal technique to a total dose of 73.4 Gy at the ICRU reference point or intensity modulated radiotherapy technique to a total dose of 76 Gy. All the patients received 3 mo of neoadjuvant ADT followed by RT and additional 6 mo of ADT. ASTRO Phoenix definition was used to define biochemical relapse.

RESULTS

Median follow up duration was 125 months. Ninety-six patients (56%) had castrate testosterone level < 20 ng/dL and 139 patients (80%) had castrate testosterone level < 50 ng/dL. Both values are valid at predicting BRFS. However, patients with testosterone < 20 ng/dL have significantly better BRFS compared to other groups (P = 0.003). When we compare two values, it was found that using 20 ng/dL is better than 50 ng/dL in predicting the BRFS (AUC = 0.63 vs 0.58, respectively).

CONCLUSION

Castrate testosterone level of less than 20 ng/dL is associated with better BRFS and is better in predicting the BRFS. Further studies using current standard of care of high dose IMRT and longer ADT duration might support these findings.

Effectiveness of three different luteinizing hormone-releasing hormone agonists in the chemical castration of patients with prostate cancer: Goserelin versus triptorelin versus leuprolide

Purpose

To investigate the changes in testosterone levels and rates of chemical castration following androgen-deprivation therapy (ADT) with goserelin, triptorelin, and leuprolide.

Materials and Methods

We retrospectively reviewed the medical records of 125 patients with prostate cancer treated with luteinizing hormone-releasing hormone (LHRH) agonists between January 2009 and December 2015. Changes in testosterone concentration during 9 months of ADT with goserelin 11.34 mg, triptorelin 11.25 mg, and leuprolide 11.25 mg were analyzed using a mixed model. The number of patients with serum testosterone below castration levels defined as various values (<50 ng/dL, <20 ng/dL, or <10 ng/dL) at 3, 6, and 9 months were also evaluated.

Results

Of the 125 patients, 59 received goserelin, 44 received triptorelin, and 22 received leuprolide, respectively. The lowest mean testosterone levels during 9 months of treatment were achieved in patients treated with triptorelin, followed by those treated with leuprolide, and then by those treated with goserelin (p=0.001). Significant differences in chemical castration levels were observed only at <10 ng/dL, with 54.2% of goserelin, 93.2% of triptorelin, and 86.4% of leuprolide treated patients (p<0.001).

Conclusions

Three LHRH agonists showed comparable efficacy for achieving castration when the castration threshold was 50 or 20 ng/dL. However, triptorelin was the most potent LHRH agonist, achieving the lowest mean testosterone levels and the highest rate of chemical castration at <10 ng/dL testosterone.

Higher Serum Testosterone Levels Associated with Favorable Prognosis in Enzalutamide- and Abiraterone-Treated Castration-Resistant Prostate Cancer

Testosterone plays a significant role in maintaining the tumor microenvironment. The role of the target serum testosterone (TST) level in enzalutamide- (Enza) and abiraterone (Abi)-treated castration-resistant prostate cancer (CRPC) patients was studied. In total, 107 patients treated with Enza and/or Abi at Chiba University Hospital and affiliated hospitals were studied. The relationships between progression-free survival (PFS), overall survival (OS), and clinical factors were studied by Cox proportional hazard and Kaplan–Meier models. In the Abi and Enza groups overall, TST ≥ 13 ng/dL (median) (Hazard Ratio (HR) 0.43, p = 0.0032) remained an independent prognostic factor for PFS. In the Enza group, TST ≥ 13 ng/dL (median) was found to be a significant prognostic factor (HR 0.28, p = 0.0044), while, in the Abi group, TST ≥ 12 ng/dL (median) was not significant (HR 0.40, p = 0.0891). TST showed significant correlation with PFS periods (r = 0. 32, p = 0.0067), whereas, for OS, TST ≥ 13 ng/dL (median) showed no significant difference in the Abi and Enza groups overall. According to Kaplan–Meier analysis, a longer PFS at first-line therapy showed a favorable prognosis in the Enza group (p = 0.0429), while no difference was observed in the Abi group (p = 0.6051). The TST level and PFS of first-line therapy may be considered when determining the treatment strategy for CRPC patients.

Discordance between testosterone measurement methods in castrated prostate cancer patients

Failure to suppress testosterone below 0.7 nM in castrated prostate cancer patients is associated with poor clinical outcomes. Testosterone levels in castrated patients are therefore routinely measured. Although mass spectrometry is the gold standard used to measure testosterone, most hospitals use an immunoassay method. In this study, we sought to evaluate the accuracy of an immunoassay method to measure castrate testosterone levels, with mass spectrometry as the reference standard. We retrospectively evaluated a cohort of 435 serum samples retrieved from castrated prostate cancer patients from April to September 2017. No follow-up of clinical outcomes was performed. Serum testosterone levels were measured in the same sample using liquid chromatography coupled with tandem mass spectrometry and electrochemiluminescent immunoassay methods. The mean testosterone levels were significantly higher with immunoassay than with mass spectrometry (0.672 ± 0.359 vs 0.461 ± 0.541 nM; P < 0.0001). Half of the samples with testosterone ≥0.7 nM assessed by immunoassay were measured <0.7 nM using mass spectrometry. However, we observed that only 2.95% of the samples with testosterone <0.7 nM measured by immunoassay were quantified ≥0.7 nM using mass spectrometry. The percentage of serum samples experiencing testosterone breakthrough at >0.7 nM was significantly higher with immunoassay (22.1%) than with mass spectrometry (13.1%; P < 0.0001). Quantitative measurement of serum testosterone levels >0.7 nM by immunoassay can result in an inaccurately identified castration status. Suboptimal testosterone levels in castrated patients should be confirmed by either mass spectrometry or an immunoassay method validated at low testosterone levels and interpreted with caution before any changes are made to treatment management.

Subcastrate Testosterone Nadir and Clinical Outcomes in Intermediate- or High-Risk Localized Prostate Cancer

PURPOSE

It is unclear if additional serum testosterone suppression below the castrate threshold of 50 ng/dL improves clinical outcomes in patients with localized prostate cancer undergoing definitive therapy.

METHODS AND MATERIALS

We examined the association of subcastrate testosterone nadir with prostate-specific antigen (PSA) response and long-term clinical outcomes in 764 U.S. veterans with intermediate- or high-risk localized prostate cancer treated with androgen deprivation therapy and definitive radiation therapy from 2000 to 2015. Patients were categorized into testosterone nadir groups based on the minimum testosterone measurement during continuous gonadotropic-releasing hormone agonist therapy (<20 ng/dL vs 20-49 ng/dL). Outcomes included PSA response (3-month post-radiation therapy PSA and 2-year PSA nadir; multivariable linear regression) and long-term clinical outcomes (biochemical recurrence, metastasis, and prostate cancer-specific mortality; Fine-Gray competing risk regression).

RESULTS

A testosterone nadir of 20 to 49 ng/dL was associated with higher 3-month post-radiation therapy PSA compared to <20 ng/dL (ß = 0.16, 95% confidence interval [CI], 0.06-0.26, P = .001) and higher 2-year PSA nadir (ß = 0.12, 95% CI, 0.04-0.21, P = .005). Compared to the <20-ng/dL group, the 20 to 49-ng/dL group showed higher 10-year biochemical recurrence rates (28.1% vs 18.3%) and metastasis rates (12.9% vs 7.8%) persisting on multivariable analyses (biochemical recurrence: sub-distribution hazard ratio [SDHR], 1.62 for 20-49 ng/dL, 95% CI, 1.07-2.45, P = .02; metastasis: SDHR, 2.19, 95% CI, 1.21-3.94, P = .009). There was a trend toward inferior prostate cancer-specific mortality for the 20 to 49-ng/dL group (SDHR, 1.95, 95% CI, 0.90-4.22, P = .09).

CONCLUSIONS

Additional serum testosterone suppression below 50 ng/dL was associated with improved PSA responses and lower rates of biochemical recurrence and metastasis in this cohort of patients with localized prostate cancer.

Pharmacokinetic and pharmacodynamic comparison of subcutaneous versus intramuscular leuprolide acetate formulations in male subjects

BACKGROUND

The aim of this study was to compare the pharmacokinetics (PK) and pharmacodynamics (PD) of two distinct formulations of leuprolide acetate (LA); subcutaneous (SC) injection and intramuscular (IM) injection.

METHODS

A total of 32 healthy men were randomized to receive a single 7.5 mg injection of SC-LA (n = 16) or IM-LA (n = 16) in this phase I, open-label, parallel-group study. PK was assessed via LA concentrations, and PD via serum luteinizing hormone (LH) and testosterone (T) concentrations.

RESULTS

The initial surge of LA was higher for IM-LA than SC-LA (Cmax 27 ± 4.9 versus 19 ± 8.0 ng/ml, respectively), with a shorter tmax (1.0 ± 0.4 versus 2.1 ± 0.8 h). The duration of quantifiable LA concentration was longer for SC-LA (up to 56 versus 42 days for SC-LA and IM-LA, respectively). Median LH concentrations in both groups rapidly increased, followed by gradual decrease. However, SC-LA demonstrated a longer duration of LH suppression, with median levels remaining below 1.0 IU/l through Day 56 compared with IM-LA where LH started to rise by Day 35. Consequently, serum T began to increase by Day 42 in the IM-LA group, with only four subjects maintaining levels ⩽50 ng/dl, compared with 14 subjects in the SC-LA group. By Day 56, 13 SC-LA subjects maintained serum T levels ⩽50 ng/dl. Both SC-LA and IM-LA were well tolerated.

CONCLUSIONS

Both formulations demonstrated consistent delivery of drug over 1 month; however, SC-LA provided a longer duration of action than expected based on the dosing interval. This profile suggests that SC-LA will provide effective suppression of T over a longer period of time, permitting greater injection scheduling flexibility.

Practical differences between luteinizing hormone-releasing hormone agonists in prostate cancer: perspectives across the spectrum of care

BACKGROUND

Androgen deprivation therapy (ADT) with luteinizing hormone-releasing hormone (LHRH) agonists is well established for the treatment of men with metastatic prostate cancer. As clear differences in efficacy, safety, or tolerability between the available LHRH agonists are lacking, the healthcare management team needs to look to practical differences between the formulations when selecting therapy for their patients. Moreover, as the economic burden of prostate cancer rises alongside earlier diagnosis and improved survival, the possibility for cost savings by using products with specific features is growing in importance.

METHODS

A review was conducted to summarize the information on the different LHRH agonist formulations currently available and offer insight into their relative benefits and disadvantages from the perspectives of physicians, a pharmacist, and a nurse.

RESULTS

The leuprorelin acetate and goserelin acetate solid implants have the advantage of being ready to use with no requirement for refrigeration, whereas powder and microsphere formulations have to be reconstituted and have specific storage or handling constraints. The single-step administration of solid implants, therefore, has potential to reduce labor time and associated costs. Dosing frequency is another key consideration, as administering the injection provides an opportunity for face-to-face interaction between the patient and healthcare professionals to ensure therapy is optimized and give reassurance to patients. Prostate cancer patients are reported to prefer 3- or 6-monthly dosing, which aligns with the monitoring frequency recommended in European Association of Urology guidelines and has been shown to result in reduced annual costs compared with 1-month formulations.

CONCLUSIONS

A number of practical differences exist between the different LHRH agonist preparations available, which may impact on clinical practice. It is important for healthcare providers to be aware and carefully consider these differences when selecting treatments for their prostate cancer patients.

Testosterone suppression in the treatment of recurrent or metastatic prostate cancer - A Canadian consensus statement

Testosterone suppression, achieved through orchiectomy or medically induced androgen-deprivation therapy (ADT), is a standard treatment for men with recurrent and metastatic prostate cancer. Current assay methods demonstrate the capacity for testosterone suppression to <0.7 nmol/l, and clinical data support improved outcomes from ADT when lower levels are achieved. Practical clinical guidelines are warranted to facilitate adoption of 0.7 nmol/l as the new standard castrate testosterone level.A pan-Canadian group of experts, representing diverse clinical specialties, identified key clinical issues, searched and reviewed relevant literature, and developed consensus statements on testosterone suppression for the treatment of prostate cancer. The expert panel found that current evidence supports the clinical benefit of achieving low testosterone levels during ADT, and encourage adoption of ≤0.7 nmol/l as a new castrate level threshold. The panel recommends regular monitoring of testosterone (e.g., every 3-6 months) and prostate-specific antigen (PSA) levels as clinically appropriate (e.g., every 3-6 months) during ADT, with reassessment of therapeutic strategy if testosterone is not suppressed or if PSA rises regardless of adequate testosterone suppression. The panel also emphasizes the need for greater awareness and education regarding testosterone assay specifications, and strongly promotes the use of mass spectrometry-based assays to ensure accurate measurement of testosterone at castrate levels.

Serum Testosterone Levels in Prostate Cancer Patients Undergoing Luteinizing Hormone-Releasing Hormone Agonist Therapy

BACKGROUND

Serum testosterone measurement is recommended to assess the efficacy of androgen deprivation therapy (ADT) and to diagnose castration resistance in patients with prostate cancer (PCa). Currently, the accepted castrate level of serum testosterone is 50 ng/dL. Liquid chromatography and tandem mass spectrometry (LC MSMS) is the appropriate method to measure testosterone, especially at low levels. However, worldwide, chemiluminescent assays (CLIAs) are used in clinical laboratories, despite their lack of accuracy and reproducibility, because they are automatable, fast, sensitive, and inexpensive.

MATERIALS AND METHODS

We compared serum testosterone levels measured using LC MSMS and CLIAs in 126 patients with PCa undergoing luteinizing hormone-releasing hormone (LHRH) agonist therapy.

RESULTS

The median serum testosterone level was 14.0 ng/dL (range, 2.0-67.0 ng/dL) with LC MSMS and 31.9 ng/dL (range, 10.0-91.6 ng/dL) with CLIA (P < .001). The serum testosterone levels, measured using LC MSMS, were < 20 ng/dL in 83 patients (65.9%), 20 to 50 ng/dL in 40 (31.7%), and > 50 ng/dL in 3 patients (2.4%). These ranges were found in 34 (27%), 72 (57.1%), and 20 (15.9%) patients when testosterone was measured using CLIA (P < .001). The castrate level of serum testosterone using LC MSMS and CLIA was 39.8 ng/dL (95% confidence interval [CI], 37.1-43.4 ng/dL) and 66.5 ng/dL (95% CI, 62.3-71.2 ng/dL), respectively.

CONCLUSION

We found that CLIA overestimated the testosterone levels in PCa patients undergoing LHRH agonist therapy. Thus, the castration level was incorrectly considered inadequate with CLIA in almost 15% of patients. The true castration level of serum testosterone using an appropriate method is < 50 ng/dL.

Testosterone monitoring for men with advanced prostate cancer: Review of current practices and a survey of Canadian physicians

Androgen-deprivation therapy (ADT) is a standard of care in the treatment of advanced prostate cancer; however, testosterone monitoring practices for men undergoing ADT vary across Canada. Although a testosterone level of 1.7 nmol/L or lower has historically been defined as the accepted castrate level, newer assays with improved sensitivity have shown that both medical and surgical castration can suppress testosterone levels to below 0.7 nmol/L. This review explores the evidence supporting a redefinition of the castrate testosterone level as 0.7 nmol/L or lower, and presents results of a survey of testosterone monitoring practices among 153 Canadian urologists, uro-oncologists, and radiation oncologists who manage the treatment of men with hormone-sensitive prostate cancer.

Clinical Outcomes and Testosterone Levels Following Continuous Androgen Deprivation in Patients with Relapsing or Locally Advanced Prostate Cancer: A Post Hoc Analysis of the ICELAND Study

PURPOSE

Lower serum testosterone levels correlate with improved cause specific survival and longer time to progression in year 1 of continuous androgen deprivation in men with prostate cancer. ICELAND was a large European study demonstrating the efficacy of leuprorelin (Eligard®) during continuous androgen deprivation. In this post hoc analysis we investigated serum testosterone levels within year 1 of continuous androgen deprivation to determine survival and time to progression.

MATERIALS AND METHODS

In ICELAND (ClinicalTrials.gov NCT00378690) patients with locally advanced or relapsing nonmetastatic prostate cancer and with prostate specific antigen 1 ng/ml or less following 6-month induction with leuprorelin 3-month depot 22.5 mg (plus bicalutamide 50 mg per day for 1 month) were randomized 1:1 to continuous androgen deprivation (361) or intermittent androgen deprivation (340) with leuprorelin for 36 months. Patients receiving continuous androgen deprivation were stratified by minimum, median and maximum testosterone levels during year 1 of therapy into 20 or less, greater than 20 to 50 and greater than 50 ng/dl subgroups. Cause specific survival and time to prostate specific antigen (castrate resistant prostate cancer) progression were analyzed.

RESULTS

A total of 90.1%, 83.5% and 74.5% of patients receiving continuous androgen deprivation achieved minimum, median and maximum serum testosterone levels of 20 ng/dl or less, respectively. Cause specific survival rates and time to prostate specific antigen progression did not differ among the testosterone subgroups.

CONCLUSIONS

In patients receiving continuous androgen deprivation cause specific survival and time to prostate specific antigen progression did not differ according to testosterone levels in year 1 of therapy. This finding may in part be due to the induction period and the effectiveness of leuprorelin in lowering testosterone.

Testosterone suppression with a unique form of leuprorelin acetate as a solid biodegradable implant in patients with advanced prostate cancer: results from four trials and comparison with the traditional leuprorelin acetate microspheres formulation

BACKGROUND

There are two slow-release ready-to-use forms of leuprorelin acetate (1-month and 3-month) that are available as solid, biodegradable implants for the treatment of advanced, hormone-sensitive prostate cancer. These implants have been shown to be as effective as traditional leuprorelin acetate microspheres for achieving successful testosterone suppression (⩽0.5 ng/ml) and lowering prostate-specific antigen (PSA) levels. Here we further evaluate testosterone suppression levels from four clinical trials evaluating the 3-month leuprorelin implant, including analysis below the European Association of Urology (EAU) castration level (<0.2 ng/ml).

METHODS

Studies were conducted in patients with locally advanced/metastatic prostate cancer: (1) a randomised, controlled single-dose study comparing the leuprorelin implant with leuprorelin microspheres; (2) a single-arm, single-dose study of the leuprorelin implant; (3 and 4) two long-term studies with the leuprorelin implant administered twice, 12 or 16 weeks apart. Patients received 3-month leuprorelin (5 mg) implant or 3-month leuprorelin (10.72 mg) microspheres. Testosterone levels were analysed using radioimmunoassay or ultrasensitive liquid chromatography tandem mass spectrometry.

RESULTS

Both the leuprorelin implant and the leuprorelin microspheres achieved mean testosterone suppression (⩽0.5 ng/ml) within 4 weeks for >3 months. In both long-term, single-arm studies with the leuprorelin implant, median values of testosterone ⩽0.2 ng/ml were achieved at Week 4 and maintained until study completion (6 and 8 months); PSA decrease was also observed versus baseline.

CONCLUSIONS

Long-lasting steady serum levels of testosterone, comparable with orchiectomy and consistent with the EAU-recommended castration level (<0.2 ng/ml), were achieved at Week 4 and maintained up to 8 months in men with advanced prostate cancer who received the leuprorelin implant.

Serum testosterone level predicts the effective time of androgen deprivation therapy in metastatic prostate cancer patients

Androgen deprivation therapy (ADT) is the standard of care for patients with metastatic prostate cancer. However, whether serum testosterone levels, using a cut-off point of 50 ng dl⁻¹, are related to the effective time of ADT in newly diagnosed prostate cancer patients remains controversial. Moreover, recent studies have shown that some patients may benefit from the addition of upfront docetaxel chemotherapy. To date, no studies have been able to distinguish patients who will benefit from the combination of ADT and docetaxel chemotherapy. This study included 206 patients who were diagnosed with metastatic prostate cancer and showed progression to castrate-resistance prostate cancer (CRPC). Serum testosterone levels were measured prospectively after ADT for 1, 3, and 6 months. The endpoint was the time to CRPC. In univariate and multivariate analyses, testosterone levels <50 ng dl⁻¹ were not associated with the effective time of ADT. Receiver operating characteristic and univariate analysis showed that testosterone levels of ≤25 ng dl⁻¹ after the first month of ADT offered the best overall sensitivity and specificity for prediction of a longer time to CRPC (adjusted hazard ratio [HR], 1.46; 95% confidence interval [95% CI], 1.08–1.96; P = 0.013). Our results show that serum testosterone level of 25 ng dl⁻¹ plays a prognostic role in prostate cancer patients receiving ADT. A testosterone value of 25 ng dl⁻¹ after the first month of ADT can distinguish patients who benefit from ADT effectiveness for only a short time. These patients may need to receive ADT and concurrent docetaxel chemotherapy.

Efficacy of Testosterone Suppression with Sustained-Release Triptorelin in Advanced Prostate Cancer

Introduction

Androgen deprivation therapy (ADT) is a mainstay of treatment against advanced prostate cancer (PC). As a treatment goal, suppression of plasma testosterone levels to <50 ng/dl has been established over decades. Evidence is growing though that suppression to even lower levels may add further clinical benefit. Therefore, we undertook a pooled retrospective analysis on the efficacy of 1-, 3-, and 6-month sustained-release (SR) formulations of the gonadotropin-releasing hormone (GnRH) agonist triptorelin to suppress serum testosterone concentrations beyond current standards.

Methods

Data of 920 male patients with PC enrolled in 9 prospective studies using testosterone serum concentrations as primary endpoint were pooled. Patients aged 42–96 years had to be eligible for ADT and to be either naïve to hormonal treatment or have undergone appropriate washout prior to enrolment. Patients were treated with triptorelin SR formulations for 2–12 months. Primary endpoints of this analysis were serum testosterone concentrations under treatment and success rates overall and per formulation, based on a testosterone target threshold of 20 ng/dl.

Results

After 1, 3, 6, 9, and 12 months of treatment, 79%, 92%, 93%, 90%, and 91% of patients reached testosterone levels <20 ng/dl, respectively. For the 1-, 3-, and 6-month formulations success rates ranged from 80–92%, from 83–93%, and from 65–97% with median (interquartile range) serum testosterone values of 2.9 (2.9–6.5), 5.0 (2.9–8.7), and 8.7 (5.8–14.1) ng/dl at study end, respectively.

Conclusion

In the large majority of patients, triptorelin SR formulations suppressed serum testosterone concentrations to even <20 ng/dl. Testosterone should be routinely monitored in PC patients on ADT although further studies on the clinical benefit of very low testosterone levels and the target concentrations are still warranted.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-016-0466-7) contains supplementary material, which is available to authorized users.

Resistance to Hormonal Therapy in Prostate Cancer

Several therapeutic strategies are actually available in the management of prostate cancer: Targeting the androgen receptor (AR) is the goal both for initial androgen deprivation therapy (ADT) and second-generation androgen ablative agents (abiraterone and enzalutamide). Chemotherapy with taxanes, administered upon progression or as first line approach in association with ADT, is another therapeutic option. Unfortunately, none of these therapies is curative and patients are destined to develop a resistant phenotype.Progression to ADT leads to the attainment of a castration resistant disease whose mechanisms remain incompletely understood. Reactivation of AR has been shown to occur and second-generation of AR targeting drugs are usually prescribed. Upon progression to these agents AR signaling still remains the primary driver although it often becomes ligand independent, since it can be either restored through mutations on the ligand binding domain and/or formation of AR splicing variants or by passed through a cross talk with other oncogenic signaling pathways.AR-independent signaling pathways may represent additional mechanisms underlying castration resistant progression. It is clear that castration resistant prostate cancer is a group of diverse diseases and new treatment paradigms need to be developed.

Free Testosterone During Androgen Deprivation Therapy Predicts Castration-Resistant Progression Better Than Total Testosterone

BACKGROUND

The optimal degree of testosterone suppression in patients with prostate cancer undergoing androgen deprivation therapy remains in question. Furthermore, serum free testosterone, which is the active form of testosterone, seems to correlate with intraprostatic testosterone. Here we compared free and total serum testosterone as predictors of survival free of castration resistance.

METHODS

Total testosterone (chemiluminescent assay, lower sensitivity 10 ng/dl) and free testosterone (analogue-ligand radioimmunoassay, lower sensitivity 0.05 pg/ml) were determined at 6 months of LHRH agonist treatment in a prospective cohort of 126 patients with prostate cancer. During a mean follow-up of 67 months (9-120), 75 (59.5%) events of castration-resistant progression were identified. Multivariate analysis and survival analysis according to total testosterone cutoffs of 50, 32, and 20 ng/dl, and free testosterone cutoffs of 1.7, 1.1, and 0.7 pg/ml were performed.

RESULTS

Metastatic spread was the most powerful predictor of castration resistance, HR: 2.09 (95%CI: 1.18-3.72), P = 0.012. Gleason score, baseline PSA and PSA at 6 months were also independents predictors, but not free and total testosterone. Stratified analysis was conducted on the basis of the status of metastatic diseases and free testosterone was found to be an independent predictor of survival free of castration resistance in the subgroup of patients without metastasis, HR: 2.12 (95%CI: 1.16-3.85), P = 0.014. The lowest threshold of free testosterone which showed significant differences was 1.7 pg/ml, P = 0.003.

CONCLUSIONS

Free testosterone at 6 months of LHRH agonist treatment seems to be a better surrogate than total testosterone to predict castration resistance in no metastatic prostate cancer patients. Prostate 77:114-120, 2017. © 2016 Wiley Periodicals, Inc.

Maximal testosterone suppression in the management of recurrent and metastatic prostate cancer

INTRODUCTION

Testosterone suppression, or androgen-deprivation therapy (ADT), is an established treatment for recurrent and metastatic prostate cancer (PCa). Based on the accuracy and sensitivity of early assays (c. 1960-1970), the castrate testosterone level was set at ≤1.7 nmol/l. Improved sensitivity of testosterone assays shows that both surgical and medical castration can achieve levels <0.7 nmol/l. However, the clinical implications and importance of maximum testosterone suppression remains a subject of controversy. This evidence-based review assesses prospective and retrospective clinical data, linking maximum suppression of testosterone with improved outcomes from ADT.

METHODS

PubMed and conference proceedings were searched for studies assessing the impact of low testosterone on clinical outcomes from ADT. The key search terms included combinations of prostate cancer and testosterone, predictive/prognostic, and androgen deprivation. Results were limited to studies investigating the relationship between testosterone levels and clinical outcomes.

RESULTS

Both prospective and retrospective data support a relationship between testosterone levels below the historical standard of 1.7 nmol/l and improved outcomes. Eight studies showed significant improvements in survival-related outcomes, with the majority of data supporting a testosterone level cutoff of ≤0.7 nmol/l.

CONCLUSIONS

Tracking both testosterone and prostate-specific antigen (PSA) levels has significant clinical benefits, and the serum testosterone threshold of ≤0.7 nmol/l is a practical goal. The relative levels of testosterone and PSA may indicate continued hormone responsiveness or progression toward castration-resistant prostate cancer (CRPC) and should, therefore, inform treatment strategy. Standardization of assay methods and clinical coordination to facilitate widespread access to state-of the art laboratory equipment is necessary to ensure accurate decision-making.

Luteinizing Hormone-Releasing Hormone Agonists are Superior to Subcapsular Orchiectomy in Lowering Testosterone Levels of Men with Prostate Cancer: Results from a Randomized Clinical Trial

PURPOSE

Recent evidence suggests that reaching the lowest achievable levels of testosterone with androgen deprivation therapy delays disease progression and increases overall survival in men with advanced prostate cancer. The aim of this analysis was to compare posttreatment serum testosterone levels between patients undergoing subcapsular orchiectomy and patients treated with the luteinizing hormone-releasing hormone agonist triptorelin.

MATERIALS AND METHODS

In this randomized clinical trial we included 58 consecutive hormone naïve men diagnosed with advanced prostate cancer at Herlev and Gentofte University Hospital, Herlev, Denmark from September 2013 to March 2015. Followup was 48 weeks. Participants were randomly assigned 1:1 to subcapsular orchiectomy or triptorelin 22.5 mg given as 24-week depot injections. Androgen status was measured by liquid chromatography-tandem mass spectrometry prior to treatment and after 12, 24 and 48 weeks. Between group differences in achieved hormone levels were analyzed by longitudinal Tobit regression.

RESULTS

Triptorelin injections resulted in 29% lower testosterone levels (95% CI 17.2-41.7) compared to subcapsular orchiectomy (p <0.001). A significantly higher proportion of men receiving triptorelin had testosterone levels less than 20 ng/dl at 12 and 48 weeks compared to men undergoing orchiectomy (97% vs 79% and 100% vs 87%, respectively, p <0.05). There was no detectable difference in the adrenal androgen reduction between the treatment groups.

CONCLUSIONS

The use of 24-week depot triptorelin injections results in significantly lower testosterone levels compared to subcapsular orchiectomy. To our knowledge this is the first randomized study to demonstrate a difference in treatment effect between surgical and medical castration on testosterone levels.

Measurement of serum testosterone during androgenic suppression in patients with prostate cancer: A systematic review

INTRODUCTION

Clinical practice guidelines recommend measuring serum testosterone (ST) during androgenic suppression (AS) to assess its efficacy and define castration resistance (CR). The objectives of this systematic review were to assess the level of scientific evidence that justify checking ST levels during AS, when to perform it and for what purpose.

MATERIAL AND METHODS

We performed a search in PubMed with the following mesh terms: androgen suppression, testosterone, and prostate cancer. The search was narrowed to original articles published in English.

RESULTS

We found 8 publications that analysed the clinical impact of ST concentrations during AS. In all of the series, ST was measured using chemiluminescent assays. However, only indirect methods based on liquid or gas chromatography for its extraction and subsequent quantification using mass spectrometry are recommended, especially for measuring low levels. The endpoints were specific survival and CR-free survival. Six studies were retrospective. The series were not uniform in terms of clinical stage, types of AS and ST assessment methods. In general, low ST levels (<20ng/dL or <32ng/dL) were related to longer CR-free survival. The measurements were performed every 3 or 6 months. Four studies confirmed the beneficial effect of adding bicalutamide when detecting microelevations above 50ng/dL.

CONCLUSIONS

The level of scientific evidence justifying the measurement of ST during AS is low, and the methods employed for quantifying ST levels are inadequate. However, we consider it useful to check ST levels during AS, and there appears to be an association between low ST levels and better disease outcomes. In the event of microelevations above 50ng/dL, we recommend the administration of bicalutamide.

Intramuscular depot formulations of leuprolide acetate suppress testosterone levels below a 20 ng/dL threshold: a retrospective analysis of two Phase III studies

Introduction

Androgen deprivation therapy (ADT) with gonadotropin-releasing hormone (GnRH) analogs is a standard treatment for advanced prostate cancer. GnRH analog therapy can reduce testosterone to “castrate” levels, historically defined as <50 ng/dL. With the advent of newer assays, a lower threshold of <20 ng/dL has recently been proposed. We report the results of a retrospective analysis of two Phase III trials of 4- and 6-month depot microsphere formulations of leuprolide acetate (LA), a GnRH agonist that has previously demonstrated efficacy in testosterone suppression to <50 ng/dL in patients on ADT. This analysis investigates the ability of these LA formulations to suppress to ≤20 ng/dL levels.

Methods

In two of five AbbVie/Abbott clinical trials of microsphere formulations of LA for ADT, analytic technology permitting testosterone detection as low as 3 ng/dL was used and thus was selected for this analysis. Both trials were open-label, fixed-dose studies in prostate cancer patients, naïve to ADT. Patients received either 30 mg (4-month formulation; n=49) or 45 mg (6-month formulation; n=151) depot injections of LA microspheres. Treatment duration was up to 32 weeks for the 4-month formulation and 48 weeks for the 6-month formulation. The proportion of patients achieving the 20 ng/dL threshold was determined every 4 weeks.

Results

Pooled analysis showed that 152 of 193 (79%) of patients achieved serum testosterone levels of ≤20 ng/dL at 4 weeks, and sustained the improvement at week 24 (169/189, 89%). Additionally, in the 6-month study, 127/135 (94.1%) patients were suppressed to ≤20 ng/dL at 48 weeks.

Conclusion

Both 4- and 6-month intramuscular depot formulations of LA achieved and maintained mean serum testosterone levels ≤20 ng/dL in the vast majority of patients as early as 4 weeks following treatment initiation. Additional research on the clinical relevance of this lower testosterone threshold is warranted.

An Update on Triptorelin: Current Thinking on Androgen Deprivation Therapy for Prostate Cancer

Androgen deprivation therapy (ADT) is the mainstay palliative treatment for men with locally advanced and metastatic prostate cancer, and aims to reduce testosterone to levels obtained by surgical castration. Use of gonadotropin-releasing hormone (GnRH) agonists predominates among the ADT options. The GnRH agonist, triptorelin is a first-line hormonal therapy that has demonstrated efficacy and safety in clinical trials of patients with locally advanced non-metastatic or metastatic disease. Sustained-release 1-, 3- and 6-month formulations of triptorelin, administered intramuscularly or subcutaneously, have been developed to provide improved flexibility and convenience for the patient. Head-to-head studies of GnRH agonists are lacking in the field of prostate cancer. Despite the inevitable progression to castration-resistant prostate cancer (CRPC) in most patients receiving ADT, monitoring of testosterone levels needs to improve in routine practice and physicians should not overlook the benefits of continued ADT in their patients when introducing one of the various new treatment options for CRPC. For improved survival outcomes, there remains a need to tailor ADT treatment regimens, novel hormonal agents and chemotherapy according to the individual patient with advanced prostate cancer.

Extended release, 6-month formulations of leuprolide acetate for the treatment of advanced prostate cancer: achieving testosterone levels below 20 ng/dl

INTRODUCTION

Luteinizing hormone-releasing hormone agonists such as leuprolide acetate (LA) are the most frequently utilized treatment of advanced prostate cancer as the regimen for achieving androgen deprivation therapy (ADT). The efficacy of LA is determined by extent of testosterone (T) suppression in prostate cancer patients. Although, the historical castrate T suppression target has been defined as < 50 ng/dl, this level may not be as low as required to deliver equivalent suppression as achieved by surgical castration. Recent studies have demonstrated that a T level as low as 20 ng/dl may produce improved clinical outcomes.

AREAS COVERED

LA is available in long-acting formulations that deliver active drug over the course of 1-6 months from a single-dose administration. The technologies utilized to provide sustained drug delivery differ: one mode of administration uses microspheres, which encapsulate the drug and are injected as a suspension intramuscularly; another mode of administration uses a liquid polymer that creates a single, solid depot after injection subcutaneously. This article will review the safety and efficacy of both 6-month LA formulations, as well as their impact in prostate cancer treatment.

EXPERT OPINION

As the understanding of optimal T castrate level evolves and may be refined pending new data from contemporaneous trials, achievement and maintenance of T levels well below 50 ng/dl may be important in evaluating potential differences in ADT regimens.

Polymer-delivered subcutaneous leuprolide acetate formulations achieve and maintain castrate concentrations of testosterone in four open-label studies in patients with advanced prostate cancer

OBJECTIVE

To determine whether luteinising hormone-releasing hormone (LHRH) agonist, ATRIGEL^® polymer-delivered, subcutaneous, leuprolide acetate (ADSC-LA), formulations suppressed serum testosterone to concentrations of ≤20 ng/dL.

PATIENTS AND METHODS

Data from four open-label, fixed-dose studies were evaluated. Male patients aged 40-86 years with advanced prostatic adenocarcinoma, whom had not undergone prior androgen-deprivation therapy (ADT), were treated with a depot formulation of ADSC-LA: 7.5 mg (1-month, 120 patients), 22.5 mg (3-month, 117 patients), 30 mg (4-month, 90 patients), or 45 mg (6-month, 111 patients). Serum testosterone was sampled at screening, baseline, 2, 4, 8 h after dosing, 1, 2, 3, and 7 days, and every week until the next dose, at which time, the sampling schedule repeated until the end of study (24 weeks for 1- and 3-month formulations, 32 weeks for 4-month, and 48 weeks for the 6-month). The primary analyses were mean serum testosterone concentrations and proportion of patients who achieved concentrations of ≤20 ng/dL.

RESULTS

The mean (SE) serum testosterone concentrations at the end of study were consistently ≤20 ng/dL in each study, at 6.1 (0.4), 10.1 (0.7), 12.4 (0.8), and 12.6 (2.1) ng/dL for the 1-, 3-, 4-, and 6-month formulations, respectively. A high proportion of patients (94%, 90%, 92%, 96% for the 1-, 3-, 4-, and 6-month formulations, respectively) achieved testosterone concentrations of ≤20 ng/dL within 6 weeks, and 90-97% of patients in all studies maintained concentrations of ≤20 ng/dL from weeks 6-24.

CONCLUSIONS

Recent studies have shown improved outcomes in patients with prostate cancer who consistently attained a more rigorous level of testosterone suppression (≤20 ng/dL) with ADT than the historical standard (≤50 ng/dL). All doses of ADSC-LA rapidly achieved and maintained mean serum testosterone to the more rigorous target concentration of ≤20 ng/dL. These data suggest that ADSC-LA delivers equivalent testosterone suppression as achieved by surgical castration.

[Castration modalities in prostate cancer: Are they all equal?]

AIM

The aim of this literature review was to focus on the new highlights regarding oncologic and safety outcomes depending on the type of castration used.

MATERIAL

Literature search using various algorithms "prostate cancer", "castration", "agonist", "antagonist", "orchiectomy", "GnRH", "FSH", "androgen deprivation therapy" has been performed in April 2015, through the PubMed and Embase databases.

RESULTS

GnRH agonists and antagonists are both currently used in clinical practice. Nevertheless, differences regarding their pharmacologic properties have been highlighted in recent studies, specifically regarding the rapidity, sustainability and depth of the castration, but also the decrease in FSH level. Such differences may have oncological impact on the patient, regarding the disease biological control and the time to progression, and a tolerability impact, especially on the cardiovascular risks. The role of the depth and the sustainability of the castration in one hand, the FSH impact in the other hand, as well as a direct inhibition on extra-pituitary GnRH receptors by antagonist might explain these differences.

CONCLUSIONS

Recent studies suggest differences between GnRH agonists and antagonist that could impact the patient clinical outcomes. However, further high level of evidence comparative studies remains warranted.

Role of Hormonal Treatment in Prostate Cancer Patients with Nonmetastatic Disease Recurrence After Local Curative Treatment: A Systematic Review

CONTEXT

The relative benefits and harms of hormonal treatment (HT) versus no or deferred HT in patients with nonmetastatic prostate cancer (PCa) relapse after primary curative therapy are controversial.

OBJECTIVE

To assess the effectiveness of HT for nonmetastatic PCa relapse, prognostic factors for treatment outcome, timing of treatment, and the most effective treatment strategy to provide guidance for clinical practice.

EVIDENCE ACQUISITION

A systematic literature search was undertaken incorporating Medline, Embase, and the Cochrane Library (search ended March 2015). Studies were critically appraised for risk of bias. The outcomes included overall and cancer-specific survival, metastasis-free survival, symptom-free survival, progression to castrate resistance, adverse events, and quality of life.

EVIDENCE SYNTHESIS

Of 9687 articles identified, 27 studies were eligible for inclusion (2 RCTs, 8 nonrandomised comparative studies, and 17 case series). The results suggest that only a subgroup of patients, especially those with high-risk disease, may benefit from early HT. The main predictors for unfavourable outcomes were shorter PSA doubling time (<6-12 mo) and higher Gleason score (>7). Early HT may be warranted for patients with high-risk disease. An intermittent HT strategy appears feasible. Most studies had a moderate to high risks of bias.

CONCLUSIONS

HT for PCa relapse after primary therapy with curative intent should be reserved for patients at highest risk of progression and with a long life expectancy. The potential benefits of starting HT should be judiciously balanced against the associated harms.

PATIENT SUMMARY

This article summarises the evidence on the benefits and harms of hormonal treatment in prostate cancer (PCa) patients in whom the disease has recurred following earlier curative treatment. We found that only a select group of patients with aggressive PCa and a fast rising prostate-specific antigen may benefit from early hormonal treatment (HT), whereas in others HT may be more harmful than beneficial.

Nadir Testosterone after Long-Term Followup Predicts Prognosis in Patients with Prostate Cancer Treated with Combined Androgen Blockade

PURPOSE

We examined the clinical significance of long-term serum testosterone monitoring to predict the prognosis of patients with prostate cancer treated with combined androgen blockade.

MATERIALS AND METHODS

We retrospectively analyzed the records of 225 patients who underwent combined androgen blockade as first line therapy for prostate cancer. The prognostic values of testosterone and other clinical factors were evaluated with respect to prostate specific antigen progression-free and overall survival.

RESULTS

Median patient age was 73.0 years, median prostate specific antigen was 42.6 ng/ml and median followup was 45.8 months. No variable associated with testosterone was predictive of progression-free survival. With regard to overall survival on univariate analysis nadir testosterone less than 16 ng/dl (p = 0.0190), less than 20 ng/dl (p = 0.0020) and less than 32 ng/dl (p = 0.0146) were significant together with other clinical factors. In contrast, nadir testosterone less than 8 and less than 12 ng/dl were not significant. Multivariate analysis showed that nadir testosterone less than 20 ng/dl was the significant prognostic factor (p = 0.0048). In addition, time to nadir testosterone was about 1 year (11.3 months). Patients were divided into rapid and slow types based on time to testosterone less than 20 ng/dl before and after 6 months, respectively. No significant difference in overall survival was observed between the 2 types. The current results suggest that the critical factor for prognosis was not a rapid decrease but whether nadir testosterone achieved a level of less than 20 ng/dl.

CONCLUSIONS

Nadir testosterone 20 ng/dl was the most significant cutoff level for overall survival in Japanese patients with prostate cancer treated with combined androgen blockade.

Nadir testosterone within first year of androgen-deprivation therapy (ADT) predicts for time to castration-resistant progression: a secondary analysis of the PR-7 trial of intermittent versus continuous ADT

PURPOSE

Three small retrospective studies have suggested that patients undergoing continuous androgen deprivation (CAD) have superior survival and time to progression if lower castrate levels of testosterone (< 0.7 nmol/L) are achieved. Evidence from prospective large studies has been lacking.

PATIENTS AND METHODS

The PR-7 study randomly assigned patients experiencing biochemical failure after radiation therapy or surgery plus radiation therapy to CAD or intermittent androgen deprivation. The relationship between testosterone levels in the first year and cause-specific survival (CSS) and time to androgen-independent progression in men in the CAD arm was evaluated using Cox regression.

RESULTS

There was a significant difference in CSS (P = .015) and time to hormone resistance (P = .02) among those who had first-year minimum nadir testosterone ≤ 0.7, > 0.7 to ≤ 1.7, and ≥ 1.7 nmol/L. Patients with first-year nadir testosterone consistently > 0.7 nmol/L had significantly higher risks of dying as a result of disease (0.7 to 1.7 nmol/L: hazard ratio [HR], 2.08; 95% CI, 1.28 to 3.38; > 1.7 nmol/L: HR, 2.93; 95% CI, 0.70 to 12.30) and developing hormone resistance (0.7 to 1.7 nmol/L: HR, 1.62; 95% CI, 1.20 to 2.18; ≥ 1.7 nmol/L: HR, 1.90; 95% CI, 0.77 to 4.70). Maximum testosterone ≥ 1.7 nmol/L predicted for a higher risk of dying as a result of disease (P = .02).

CONCLUSION

Low nadir serum testosterone (ie, < 0.7 mmol/L) within the first year of androgen-deprivation therapy correlates with improved CSS and duration of response to androgen deprivation in men being treated for biochemical failure undergoing CAD.

Long-term tolerability and efficacy of degarelix: 5-year results from a phase III extension trial with a 1-arm crossover from leuprolide to degarelix

OBJECTIVE

To demonstrate the safety and efficacy of up to 5 years of degarelix treatment and the effects of crossing over from leuprolide to degarelix in the extension phase of a phase III pivotal 1-year trial.

METHODS

Patients receiving degarelix who completed the 1-year trial continued on 80 mg (n = 125) or 160 mg (n = 126) maintenance doses. Patients who received leuprolide were rerandomized to degarelix 240/80 mg (n = 69) or 240/160 mg (n = 65). Safety and tolerability were assessed (primary end point), as well as testosterone and prostate-specific antigen levels and prostate-specific antigen progression-free survival (secondary end points).

RESULTS

Adverse event frequency was similar between both the groups. Adverse events included initial injection site reactions, hot flushes, and increased weight. Testosterone and prostate-specific antigen values during the extension study were similar to those seen during the 1-year trial in patients who continued on degarelix or crossed over from leuprolide. The prostate-specific antigen progression-free survival hazard rate was decreased significantly after the crossover in the leuprolide to degarelix group (from 0.20 to 0.09; P = .002), whereas in patients who continued on degarelix, the rate did not change significantly. In patients with baseline prostate-specific antigen >20 ng/mL, the same hazard rate change pattern was observed on crossover (from 0.38 to 0.19; P = .019).

CONCLUSION

Degarelix was well tolerated; no safety concerns were identified. The significant prostate-specific antigen progression-free survival benefit established for degarelix over leuprolide during year 1 remained consistent at 5 years.

Might men diagnosed with metastatic prostate cancer benefit from definitive treatment of the primary tumor? A SEER-based study

BACKGROUND

Few data exist regarding the impact on survival of definitive treatment of the prostate in men diagnosed with metastatic prostate cancer (mPCa).

OBJECTIVE

To evaluate the survival of men diagnosed with mPCa based on definitive treatment of the prostate.

DESIGN, SETTING, AND PARTICIPANTS

Men with documented stage IV (M1a-c) PCa at diagnosis identified using Surveillance Epidemiology and End Results (SEER) (2004-2010) and divided based on definitive treatment of the prostate (radical prostatectomy [RP] or brachytherapy [BT]) or no surgery or radiation therapy (NSR).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Kaplan-Meier methods were used to calculate overall survival (OS). Multivariable competing risks regression analysis was used to calculate disease-specific survival (DSS) probability and identify factors associated with cause-specific mortality (CSM).

RESULTS AND LIMITATIONS

A total of 8185 patients were identified: NSR (n=7811), RP (n=245), and BT (n=129). The 5-yr OS and predicted DSS were each significantly higher in patients undergoing RP (67.4% and 75.8%, respectively) or BT (52.6 and 61.3%, respectively) compared with NSR patients (22.5% and 48.7%, respectively) (p<0.001). Undergoing RP or BT was each independently associated with decreased CSM (p<0.01). Similar results were noted regardless of the American Joint Committee on Cancer (AJCC) M stage. Factors associated with increased CSM in patients undergoing local therapy included AJCC T4 stage, high-grade disease, prostate-specific antigen ≥20 ng/ml, age ≥70 yr, and pelvic lymphadenopathy (p<0.05). The major limitation of this study was the lack of variables from SEER known to influence survival of patients with mPCa, including treatment with systemic therapy.

CONCLUSIONS

Definitive treatment of the prostate in men diagnosed with mPCa suggests a survival benefit in this large population-based study. These results should serve as a foundation for future prospective trials.

PATIENT SUMMARY

We used a large population-based cancer database to examine survival in men diagnosed with metastatic prostate cancer (mPCa) undergoing definitive therapy for the prostate. Local therapy (LT) appeared to confer a survival benefit. Therefore, we conclude that prospective trials are needed to further evaluate the role of LT in mPCa.