Role of free testosterone levels in patients with metastatic castration-resistant prostate cancer receiving second-line therapy

Prognostic role of docetaxel-induced suppression of free testosterone serum levels in metastatic prostate cancer patients

To date, only few data concerning the biologically active, free form of testosterone (FT) are available in metastatic prostate cancer (mPC) and the impact of FT on disease, therapy and outcome is largely unknown. We retrospectively studied the effect of docetaxel on FT and total testosterone (TT) serum levels in 67 mPC patients monitored between April 2008 and November 2020. FT and TT levels were measured before and weekly during therapy. The primary endpoint was overall survival (OS). Secondary endpoints were prostate-specific antigen response and radiographic response (PSAR, RR), progression-free survival (PFS), FT/TT levels and safety. Median FT and TT serum levels were completely suppressed to below the detection limit during docetaxel treatment (FT: from 0.32 to < 0.18 pg/mL and TT: from 0.12 to < 0.05 ng/mL, respectively). Multivariate Cox regression analyses identified requirement of non-narcotics, PSAR, complete FT suppression and FT nadir values < 0.18 pg/mL as independent parameters for PFS. Prior androgen-receptor targeted therapy (ART), soft tissue metastasis and complete FT suppression were independent prognostic factors for OS. FT was not predictive for treatment outcome in mPC patients with a history of ART.

Serum testosterone levels and testosterone 'bounce' phenomenon predict response to novel anti-androgen therapies in castration-resistant prostate cancer

BACKGROUND

The relevance of continuous testosterone (TT) monitoring in castration-resistant prostate cancer (CRPC) remains in question.

OBJECTIVE

To determine if TT levels before and during novel anti-androgen therapies (NAAT), and the TT 'bounce' phenomenon may predict treatment response in CRPC.

MATERIALS AND METHODS

From 2014 through 2018, we identified 92 CRPC patients treated with either Abiraterone or Enzalutamide from a prospectively maintained cancer registry. The TT levels measured before and during NAAT were correlated with the oncological outcomes, determined by PSA response (% change), PSA progression-free survival (PFS) and overall survival (OS).

RESULTS AND LIMITATIONS

At CRPC, 58 (63.0%) and 34 (37.0%) patients opted for Abiraterone and Enzalutamide respectively. Median TT levels at CRPC status before and during NAAT were 10.37 ng/dl and 20.46 ng/dl respectively. PSA response was superior in patients with a higher TT before NAAT (P:0.048, median difference: 18.22%, 95% CI 0.70 - 40.37) and longer time to CRPC (P: 0.041, median difference: 15.31%, 95% CI 1.84 -34.84), with a trend towards lower TT during NAAT (P: 0.062). Over a follow up of 33.0 months, 65 patients (70.7%) developed PSA progression. PSA PFS was longer in patients with higher TT before NAAT (16.3 vs. 10.8 months; P: 0.023), lower TT during NAAT (17.0 vs. 9.1 months; P: 0.001), and longer time to CRPC (13.4 vs. 8.0 months; P: 0.032). Importantly, better OS was observed in lower TT during NAAT (45.0 vs. 33.0 months; P:0.029) and longer time to CRPC (43.0 vs. 31.0 months; P: 0.025). The TT 'bounce' phenomenon was observed in 28 patients (33.3%), and was associated with a poorer PSA response (P: 0.029, median difference: 18.90%, 95% CI 3.83 - 41.45), shorter PSA PFS (8.6 vs 15.2 months, P: 0.002) and shorter OS (29.0 vs. 45.0 months, P: 0.012).

CONCLUSION

In CRPC patients, TT behaviors before and during NAAT, and the 'bounce' phenomenon continue to predict treatment response and could guide clinical decisions.

Deficiency of NEIL3 Enhances the Chemotherapy Resistance of Prostate Cancer

Acquired treatment resistance is an important cause of death in prostate cancer, and this study aimed to explore the mechanisms of chemotherapy resistance in prostate cancer. We employed castration-resistant prostate cancer (CRPC), neuroendocrine prostate cancer (NEPC), and chemotherapy-resistant prostate cancer datasets to screen for potential target genes. The Cancer Genome Atlas (TCGA) was used to detect the correlation between the target genes and prognosis and clinical characteristics. Nei endonuclease VIII-like 3 (NEIL3) knockdown cell lines were constructed with RNA interference. Prostate cancer cells were treated with enzalutamide for the androgen deprivation therapy (ADT) model, and with docetaxel and cisplatin for the chemotherapy model. Apoptosis and the cell cycle were examined using flow cytometry. RNA sequencing and western blotting were performed in the knockdown Duke University 145 (DU145) cell line to explore the possible mechanisms. The TCGA dataset demonstrated that high NEIL3 was associated with a high T stage and Gleason score, and indicated a possibility of lymph node metastasis, but a good prognosis. The cell therapy models showed that the loss of NEIL3 could promote the chemotherapy resistance (but not ADT resistance) of prostate cancer (PCa). Flow cytometry revealed that the loss of NEIL3 in PCa could inhibit cell apoptosis and cell cycle arrest under cisplatin treatment. RNA sequencing showed that the knockdown of NEIL3 changes the expression of neuroendocrine-related genes. Further western blotting revealed that the loss of NEIL3 could significantly promote the phosphorylation of ATR serine/threonine kinase (ATR) and ATM serine/threonine kinase (ATM) under chemotherapy, thus initiating downstream pathways related to DNA repair. In summary, the loss of NEIL3 promotes chemotherapy resistance in prostate cancer, and NEIL3 may serve as a diagnostic marker for chemotherapy-resistant patients.

[Current data on the target value of testosterone lowering and the associated research since the first administration of LHRH (GnRH) analogues to patients 40 years ago]

When LH-RH (now: GNRH) analogues were first used for the treatment of prostate cancer, the castration level was arbitrarily defined as a testosterone level of less than 50 ng/dl. Since then, numerous studies have shown that a permanent lowering of the testosterone level, e. g. by buserelin, to values lower than 20 ng/dl is associated with a significant improvement in outcomes. This has been proven in recent studies. Therefore, a castration level with testosterone values of less than 20 ng/dl is required. In addition, hormone withdrawal with GNRH analogues continues to provide the basic therapy for new treatment options, e. g. with abiraterone, enzalutamide or apalutamide.

Emerging promising biomarkers for treatment decision in metastatic castration-resistant prostate cancer

Prostate cancer is one of the most common causes of death in males. Even if treatment is often of curative intent in early stages of the disease, up to 50% of patients relapse after primary therapy. Moreover, 10% to 15% of patients present in a primary metastatic stage of disease. In the past years the treatment landscape of metastatic castration-resistant prostate cancer expanded due to the development of second-generation antiandrogens (abiraterone acetate, enzalutamide), chemotherapeutic agents and radium-223. With the availability of several therapeutic lines, we are now confronted with the problem of choosing the most suitable therapy in each state of disease. As often observed in clinical routine, prostate specific antigen is not sufficient for early prediction of a therapy response. Furthermore, biomarkers for prediction of the optimal first-line therapy are badly needed in order to avoid primary resistance. Therefore, the present short review article gives an overview of currently available clinical and preclinical biomarkers for treatment response to metastatic castration-resistant prostate cancer therapeutic agents with the aim of providing support for a personalized decision-making process in everyday use.

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.

How do we define "castration" in men on androgen deprivation therapy?

Androgen deprivation therapy (ADT) is the mainstay for the treatment of advanced prostate cancer. Since the clinical evolution from surgical orchiectomy, we have typically used ADT and orchiectomy to be synonymous terms for castration. The goal of this study is to determine if, in contemporary medical practice, surgical and chemical castration provide for similar levels of diminishment of total and free testosterone. Further, what approaches should be used to most accurately measure testosterone levels in men with advanced prostate cancer and what cutoff values, for example for total testosterone 50 ng dl^-1 or 20 ng dl^-1, should be utilized. Studies available in the literature have been analyzed and compiled to address these questions. Finally, evidence is provided that free testosterone, the biologically active component, should be utilized to provide clinically relevant state of castration.

Screening of Drug Repositioning Candidates for Castration Resistant Prostate Cancer

Purpose: Most prostate cancers (PCs) initially respond to androgen deprivation therapy (ADT), but eventually many PC patients develop castration resistant PC (CRPC). Currently, available drugs that have been approved for the treatment of CRPC patients are limited. Computational drug repositioning methods using public databases represent a promising and efficient tool for discovering new uses for existing drugs. The purpose of the present study is to predict drug candidates that can treat CRPC using a computational method that integrates publicly available gene expression data of tumors from CRPC patients, drug-induced gene expression data and drug response activity data. Methods: Gene expression data from tumoral and normal or benign prostate tissue samples in CRPC patients were downloaded from the Gene Expression Omnibus (GEO) and differentially expressed genes (DEGs) in CRPC were determined with a meta-signature analysis by a metaDE R package. Additionally, drug activity data were downloaded from the ChEMBL database. Furthermore, the drug-induced gene expression data were downloaded from the LINCS database. The reversal relationship between the CRPC and drug gene expression signatures as the Reverse Gene Expression Scores (RGES) were computed. Drug candidates to treat CRPC were predicted using summarized scores (sRGES). Additionally, synergic effects of drug combinations were predicted with a Target Inhibition interaction using the Minimization and Maximization Averaging (TIMMA) algorithm. Results: The drug candidates of sorafenib, olaparib, elesclomol, tanespimycin, and ponatinib were predicted to be active for the treatment of CRPC. Meanwhile, CRPC-related genes, in this case MYL9, E2F2, APOE, and ZFP36, were identified as having gene expression data that can be reversed by these drugs. Additionally, lenalidomide in combination with pazopanib was predicted to be most potent for CRPC. Conclusion: These findings support the use of a computational reversal gene expression approach to identify new drug and drug combination candidates that can be used to treat 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.

ADT with antiandrogens in prostate cancer induces adverse effect of increasing resistance, neuroendocrine differentiation and tumor metastasis

Prostate cancer (PCa) is the most common cancer and the 2nd leading cause of cancer-related deaths among men in the United States. Androgen-deprivation-therapy (ADT) with antiandrogens to target the androgens/androgen receptor (AR) signals remains the standard therapy for advanced PCa. However, most of the PCa patients who received ADT with antiandrogens, including the recently developed Enzalutamide (Enz) that might extend PCa patients survival an extra 4.8 months, will still develop the castration (or antiandrogen) resistance. Mechanism dissection studies suggest these antiandrogen resistances may involve the induction of AR splicing variants and/or AR mutants. Further preclinical in vitro/in vivo studies suggest ADT-antiandrogens may also enhance the neuroendocrine differentiation (NED) and PCa cell invasion, and these unwanted side-effects may function through various mechanisms including altering the infiltrating inflammatory cells within the prostate tumor microenvironment. This review summarizes these unwanted ADT-induced side-effects and discusses multiple approaches to overcome these side-effects to better suppress the PCa at the castration resistant stage.

Taking the first steps in establishing recommendations for testosterone monitoring in men with prostate cancer on androgen-deprivation therapy

The paper by Shayegan et al in this issue of CUAJ represents an important initial step in establishing recommendations for hormonal monitoring in men with prostate cancer on androgen-deprivation therapy (ADT). As with most subjects related to the actions of testosterone, the survey adds to the controversies, but also opens the opportunity to explore several of the concerns relevant to the hormonal management of prostate cancer.