Prognostic significance of serum testosterone level in patients with castration-resistant prostate cancer treated with cabazitaxel

BACKGROUND

Serum testosterone level is a potential prognostic marker for castration-resistant prostate cancer. However, its role as a prognostic marker in cabazitaxel chemotherapy remains unclear. This study aimed to elucidate the clinical significance of serum testosterone levels before cabazitaxel chemotherapy.

METHODS

This single-institution, retrospective study included 47 patients with metastatic castration-resistant prostate cancer (mCRPC) who received cabazitaxel therapy. Serum testosterone levels were measured before the initiation of cabazitaxel therapy.

RESULTS

Progression-free survival and overall survival (OS) were not significantly different between patients with high and low serum testosterone levels. Analysis of patients aged <70 years revealed that those with high serum testosterone levels (total testosterone level > 0.055 ng/mL) had significantly longer OS than those with low serum testosterone levels (total testosterone level < 0.055 ng/mL, p = 0.012). Multivariate analysis revealed that low serum testosterone levels (hazard ratio [HR] = 11.874, 95% confidence interval [CI] 2.076-67.953, p = 0.005) and high prostate-specific antigen levels (HR = 18.051, 95% CI 2.462-132.347, p = 0.004) in the pretreatment phase were independent prognostic factors for OS in patients receiving cabazitaxel therapy.

CONCLUSIONS

Serum testosterone level may be a prognostic marker for cabazitaxel therapy in patients with mCRPC who are younger than 70 years, and high serum testosterone levels may lead to longer survival.

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.

Retrospective analysis of serum testosterone levels by LC-MS/MS in chemically castrated prostate cancer patients: Biological variation and analytical performance specifications

BACKGROUND

A sensitive liquid chromatography tandem-mass spectrometry (LC-MS/MS) method was used to monitor serum testosterone levels in castrated prostate cancer patients. We subsequently performed an observational and retrospective study to estimate the within- and between-subject biological variation of these patients.

METHODS

In total, 474 samples from 72 prostate cancer patients in the Netherlands receiving either chemical castration (CAS) or castration plus enzalutamide (ENZA) treatment were selected for data analysis. ANOVA was performed to estimate analytical variation (CV_A) and within-patient variation (CV_I). A nested ANOVA was applied to estimate between-patient variation (CV_G). From these data, the reference change value (RCV) and analytical performance specifications (APS) were calculated.

RESULTS

Testosterone levels were significantly higher in the ENZA group (0.318 vs. 0.191 nmol/L, p < 0.005) than the CAS group. Overall, variation components were estimated at 6.1%, 24.6% and 60.3% for CV_A, CV_I and CV_G, respectively. Both groups showed high individuality (<0.6). The RCV was 70.3% for all patients. Desirable APS were 12.3% for imprecision, 16.3% for bias and 26.4% for total error.

CONCLUSION

The generated APS are valuable for sensitive testosterone assays and the high individuality indicates that castrated testosterone levels can be studied as a predictive or prognostic biomarker in prostate cancer patients.

Prognostic value of testosterone for the castration-resistant prostate cancer patients: a systematic review and meta-analysis

INTRODUCTION

This systematic review and meta-analysis aimed to assess the prognostic value of testosterone in patients with castration-resistant prostate cancer (CRPC).

MATERIALS AND METHODS

PubMed, Web of Science, and Scopus databases were systematically searched until December 2019, according to the Preferred Reporting Items for Systemic Review and Meta-analysis statement. The endpoints were progression-free survival (PFS) and overall survival (OS).

RESULTS

We identified 11 articles with 4206 patients for systematic review and nine articles with 4136 patients for meta-analysis. Higher testosterone levels were significantly associated with better OS (pooled HR 0.74, 95% CI 0.58-0.95) and better PFS (pooled HR 0.51, 95% CI 0.30-0.87). Subgroup analyses based on the treatment type revealed that higher testosterone levels were significantly associated with better OS in CRPC patients treated with androgen receptor-targeted agents (ARTAs) (pooled HR 0.64, 95% CI 0.55-0.75), but not in those treated with chemotherapy (pooled HR 0.78, 95% CI 0.53-1.14).

CONCLUSION

This meta-analysis demonstrated that the PFS and OS were significantly greater in patients with CRPC in those with higher testosterone levels than that of those with lower testosterone levels. In the subgroup analyses, lower testosterone levels were a consistently poor prognostic factor for OS in patients treated with ARTAs, but not in those treated with chemotherapy. Therefore, higher testosterone levels could be a useful biomarker to identify patient subgroups in which ARTAs should be preferentially recommended in the CRPC setting.

Serum testosterone level is a useful biomarker for determining the optimal treatment for castration-resistant prostate cancer

OBJECTIVE

Our aim was to evaluate the usefulness of serum testosterone to guide treatment decision for castration-resistant prostate cancer (CRPC).

METHODS

We conducted a retrospective analysis of 115 patients with CRPC treated with either abiraterone (n = 43) or enzalutamide (n = 72). A serum testosterone level was measured at time of starting of abiraterone or enzalutamide. We determined whether serum testosterone influenced the outcomes of androgen receptor (AR)-targeted therapy.

RESULTS

In the very-low testosterone group (<5 ng/dl), the rate of prostate-specific antigen (PSA) response was significantly higher among patients treated with abiraterone compared to enzalutamide (62 vs. 32%, respectively; P = 0.033), with no difference in the low testosterone group (5-<50 ng/dl) (93 vs. 81%, respectively; P = 0.429). During the median follow-up of 26 months, PSA progression-free survival was significantly longer in the low testosterone group than in the very-low testosterone group (12.2 vs. 4.5 months, P<0.001). In the very-low testosterone group, enzalutamide use (HR 3.07, 95% CI 1.36-6.94; P = 0.007), primary androgen deprivation therapy <12 months (HR 2.50, 95% CI 1.23-5.08; P = 0.011) and bone metastases (HR 2.60, 95% CI 1.20-5.64; P = 0.015) were significantly associated with PSA progression.

CONCLUSION

Patients with a serum testosterone level ≥5 ng/dl were more likely to receive therapeutic benefits from AR-targeted therapy compared to those with serum testosterone levels <5 ng/dl. However, even for those with a very low serum testosterone level, the efficacy of abiraterone was slightly higher than that of enzalutamide. Therefore, serum testosterone level is a useful biomarker for informing treatment selection for CRPC.

Serum testosterone level as possible predictive marker in androgen receptor axis-targeting agents and taxane chemotherapies for castration-resistant prostate cancer

PURPOSE

Currently, several therapeutic options for castration-resistant prostate cancer (CRPC) are available, for which predictive biomarkers have not been established. Therefore, we aimed to reveal the association between pretreatment serum testosterone level and antitumor outcomes when treated with androgen receptor axis-targeting agents and taxane chemotherapies for CRPC.

PATIENTS AND METHODS

The present study included Japanese patients with metastatic prostate cancer whose serum testosterone levels during androgen-deprivation therapy were available. The antitumor outcomes when treated with enzalutamide, abiraterone, docetaxel, and cabazitaxel with clinicopathological parameters including serum testosterone levels during androgen-deprivation therapy, as well as prognoses including progression-free survival and overall survival, were examined.

RESULTS

Progression-free survival among men with higher serum testosterone level was superior to that among men with lower serum testosterone level when treated with enzalutamide. On the contrary, progression-free survival and overall survival among men with higher serum testosterone level were significantly inferior to those among men with lower serum testosterone level when treated with docetaxel and cabazitaxel, respectively.

CONCLUSIONS

The present study indicated distinct prognostic values of serum testosterone level when treated with androgen receptor axis-targeting agent and taxane chemotherapy for CRPC, suggesting that serum testosterone level may be useful predictive biomarker to navigate the appropriate therapy in patients with CRPC.

Prognostic and predictive value of plasma testosterone levels in patients receiving first-line chemotherapy for metastatic castrate-resistant prostate cancer

BACKGROUND

Biomarkers for metastatic castration-resistant prostatic cancer (mCRPC) are an unmet medical need.

METHODS

The prognostic and predictive value for survival and response to salvage hormonal therapy (SHT) of baseline testosterone level (TL) was analysed in a cohort of 101 mCRPC patients participating in 9 non-hormonal first-line chemotherapy phase II-III trials. Inclusion criteria in all trials required a TL of <50 ng dl(-1).

RESULTS

Median age: 70 years; visceral metastases: 19.8%; median prostate-specific antigen (PSA): 50.7 ng ml(-1); median TL: 11.5 ng dl(-1). Median overall survival (OS; 24.5 months) was significantly longer if baseline TL was above (High TL; n=52) than under (Low TL; n=49) the TL median value (32.7 vs 22.4 months, respectively; P=0.0162, hazard ratio (HR)=0.6). The presence of anaemia was an unfavourable prognostic factor (median OS: 20.6 vs 28.4 months; P=0.0025, HR=1.88 (CI95%: 1.01-3.48)). Patients presenting both anaemia and low testosterone had a worse outcome compared to those with one or none of them (median OS: 17.9 vs 22.4 vs 38.1 months; P=0.0024). High vs Low TL was associated with PSA response rate (55.6% vs 21.7%) in 41 patients receiving SHT.

CONCLUSION

Testosterone level under castration range was a prognostic factor for survival mCRPC patients. The PSA response to SHT differed depending on TLs. Testosterone levels might help in treatment decision.

Serum testosterone levels after medical or surgical androgen deprivation: a comprehensive review of the literature

Androgens and the androgen receptor play a role in the progression of prostate cancer. Androgen deprivation therapy (ADT) is a mainstay in the treatment of metastatic prostate cancer. ADT is expected to reduce serum testosterone levels from a normal level of about 500 to 600 ng/dl (17.3-20.8 nmol) down to castration levels. Traditionally, castration was considered to be achieved if testosterone levels were lowered to a threshold of 50 ng/dl (1.73 nmol/l), a definition determined more by measurement methods derived from the use of old assay methods than by evidence. Serum testosterone levels in three-quarter patients after surgical castration drop to less than 20 ng/dl (0.69 nmol/l). Ineffective suppression of testosterone is currently poorly recognized and may possibly have an effect of prostate cancer mortality. Persistent levels of serum testosterone after castration are mainly derived from adrenal androgens. Furthermore, the arrival of new therapies targeting androgen synthesis and androgen receptor activity has renewed interest on serum testosterone. This review discusses the biosynthetic pathway for androgen synthesis in humans and provides a comprehensive review of serum testosterone levels after surgical or medical castration. This review assesses serum testosterone levels after surgical castration and different pharmacologic castration in patients with prostate cancer under ADT, and ineffective testosterone suppression. The author proposes methods to better lower serum testosterone levels during ADT.

Non-metastatic CRPC and asymptomatic metastatic CRPC: which treatment for which patient?

The introduction of early PSa-based diagnosis has profoundly impacted the epidemiology of castration-resistant prostate cancer (CRPC). Many patients enter the disease at an early stage when the only sign of resistance to androgen deprivation therapy (ADT) is a progressive elevation of prostate-specific antigen (PSA). This created a very heterogeneous population of non-metastatic (M0) CRPC. PSa kinetics is the most powerful indicator of aggressiveness in that population and can be used to trigger imaging investigation and enrollment in clinical trials. Several registered and near to come treatments have not been tested in that population but in men with more advanced metastatic and often symptomatic disease. Several agents have been investigated to delay the onset of the first bone metastasis but only one, denosumab, has reached its end-point. Because CRPC remains largely driven by the androgen receptor (AR), physicians have relied on second-line hormonal manipulations to delay the progression of the disease, including first generation antiandrogens, adrenal synthesis inhibitors, steroids and estrogens. The data however are mostly limited to phase II trials.

Testosterone in prostate cancer: the Bethesda consensus

OBJECTIVE

• Androgen stimulation of prostate cancer (PCa) cells has been extensively studied. The increasing trend of using serum testosterone as an absolute surrogate for castration state means that the diagnostic measurement of testosterone and the values potentially influencing prognosis must be better understood. This is especially important when PCa progresses from an endocrine to an intracrine status.

PATIENTS AND METHODS

• We performed a literature review using the MEDLINE database for publications on: (i) hormonal changes with androgen deprivation therapy (ADT); (ii) monitoring hormonal therapy with testosterone measurement; (iii) the efficacy of intermittent androgen deprivation (IAD) compared with continuous androgen deprivation; (iv) the underlying mechanisms of castration-resistance; and (v) novel treatments for castration-resistant PCa (CRPCa).

RESULTS

• The optimum serum castration levels to be achieved with ADT are still debated. Recently, the 50 ng/dL threshold has been questioned because of reports indicating worse outcomes when levels between 20 and 50 ng/dL were studied. Instead, a 20 ng/dL threshold for serum testosterone after ADT in patients with advanced prostate cancer was recommended.

CONCLUSION

• Understanding the mechanisms of androgen biosynthesis relating to PCa as well as prognostic implications might achieve a consensus regarding the role of ADT for both the androgen-sensitive and -insensitive disease state.