Addition of estramustine to chemotherapy and survival of patients with castration-refractory prostate cancer: a meta-analysis of individual patient data

Pterostilbene-isothiocyanate reduces miR-21 level by impeding Dicer-mediated processing of pre-miR-21 in 5-fluorouracil and tamoxifen-resistant human breast cancer cell lines

Converging evidences identifies that microRNA-21 (miR-21) is responsible for drug resistance in breast cancer. This study aims to evaluate the miR-21-modulatory potential of a hybrid compound, pterostilbene-isothiocyanate (PTER-ITC), in tamoxifen-resistant MCF-7 (TR/MCF-7) and 5-fluorouracil-resistant MDA-MB 231 (5-FUR/MDA-MB 231) breast cancer cell lines, established by repeated exposure to gradually increasing the concentrations of tamoxifen and 5-fluorouracil, respectively. The outcome of this study shows that PTER-ITC effectively reduced the TR/MCF-7 (IC50: 37.21 µM) and 5-FUR/MDA-MB 231 (IC50: 47.00 µM) cell survival by inducing apoptosis, inhibiting cell migration, colony and spheroid formations in TR/MCF-7 cells, and invasiveness of 5-FUR/MDA-MB 231 cells. Most importantly, PTER-ITC significantly reduced the miR-21 expressions in these resistant cell lines. Moreover, the downstream tumor suppressor target gene of miR-21 such as PTEN, PDCD4, TIMP3, TPM1, and Fas L were upregulated after PTER-ITC treatment, as observed from transcriptional (RT-qPCR) and translational (immunoblotting) data. In silico and miR-immunoprecipitation (miR-IP) results showed reduced Dicer binding to pre-miR-21, after PTER-ITC treatment, indicating inhibition of miR-21 biogenesis. Collectively, the significance of this study is indicated by preliminary evidence for miR-21-modulatory effects of PTER-ITC that highlights the potential of this hybrid compound as an miR-21-targeting therapeutic agent.

Activity and safety of KEES - an oral multi-drug chemo-hormonal metronomic combination regimen in metastatic castration-resistant prostate cancer

BACKGROUND

Metastatic castration-resistant prostate cancer (mCRPC) remains a therapeutic challenge and evidence for late-line treatments in real-life is limited. The present study investigates the efficacy and safety of an oral metronomic chemo-hormonal regimen including cyclophosphamide, etoposide, estramustine, ketoconazole and prednisolone (KEES) administered in a consecutive biweekly schedule.

METHODS

A retrospective cohort study in two Swedish regions was conducted. Overall (OS) and progression-free survival (PFS), biochemical response rate (bRR) and toxicities were analyzed.

RESULTS

One hundred and twenty-three patients treated with KEES after initial treatment with at least a taxane or an androgen-receptor targeting agents (ARTA) were identified. Of those, 95 (77%) had received both agents and were the primary analysis population. Median (95% CI) OS and PFS in the pre-treated population were 12.3 (10.1-15.0) and 4.4 (3.8-5.5) months, respectively. Biochemical response, defined as ≥ 50% prostate-specific antigen (PSA) reduction, occurred in 26 patients (29%), and any PSA reduction in 59 (65%). PFS was independent of prior treatments used, and KEES seemed to be effective in late treatment lines. The bRR was higher compared to historical data of metronomic treatments in docetaxel and ARTA pre-treated populations. In multivariable analyses, performance status (PS) ≥ 2 and increasing alkaline phosphatase (ALP) predicted for worse OS. Nausea, fatigue, thromboembolic events and bone marrow suppression were the predominant toxicities.

CONCLUSIONS

KEES demonstrated meaningful efficacy in heavily pre-treated CRPC patients, especially those with PS 0-1 and lower baseline ALP, and had an acceptable toxicity profile.

Precision Targets for Intercepting the Lethal Progression of Prostate Cancer: Potential Avenues for Personalized Therapy

Organ-confined prostate cancer of low-grade histopathology is managed with radiation, surgery, active surveillance, or watchful waiting and exhibits a 5-year overall survival (OS) of 95%, while metastatic prostate cancer (PCa) is incurable, holding a 5-year OS of 30%. Treatment options for advanced PCa-metastatic and non-metastatic-include hormone therapy that inactivates androgen receptor (AR) signaling, chemotherapy and genome-targeted therapy entailing synthetic lethality of tumor cells exhibiting aberrant DNA damage response, and immune checkpoint inhibition (ICI), which suppresses tumors with genomic microsatellite instability and/or deficient mismatch repair. Cancer genome sequencing uncovered novel somatic and germline mutations, while mechanistic studies are revealing their pathological consequences. A microRNA has shown biomarker potential for stratifying patients who may benefit from angiogenesis inhibition prior to ICI. A 22-gene expression signature may select high-risk localized PCa, which would not additionally benefit from post-radiation hormone therapy. We present an up-to-date review of the molecular and therapeutic aspects of PCa, highlight genomic alterations leading to AR upregulation and discuss AR-degrading molecules as promising anti-AR therapeutics. New biomarkers and druggable targets are shaping innovative intervention strategies against high-risk localized and metastatic PCa, including AR-independent small cell-neuroendocrine carcinoma, while presenting individualized treatment opportunities through improved design and precision targeting.

In vitro Anticancer Effects of JI017 on Two Prostate Cancer Cell Lines Involve Endoplasmic Reticulum Stress Mediated by Elevated Levels of Reactive Oxygen Species

Prostate cancer is the second most commonly diagnosed cancer, and prostate cancer is the second most common cause of cancer death in United States men after lung cancer. Many therapies are used to treat prostate cancer, and chemotherapy is one of the most relevant treatments. However, chemotherapy has many side effects, and repeated administration of chemotherapeutic agents leads to acquired resistance. Thus, new drugs with few side effects are needed. We investigated the molecular mechanism of action of JI017 in human prostate cancer cells. We identified an endoplasmic reticulum (ER) stress pathway that depended on the reactive oxygen species (ROS) pathway and played a crucial role in JI017-induced apoptosis. We measured cell viability by the MTS assay to determine the effect of JI017. Analysis of apoptosis, mitochondrial dysfunction, and cell cycle features was performed by flow cytometry. We used western blot and RT-PCR to measure the levels of the proteins of the unfolded protein response (UPR) pathway and apoptosis markers. Immunoprecipitation assay and transfection were used to determine the expression levels of proteins interacting with the pathways influenced by JI017 in prostate cancer cells. The anticancer effects induced by JI017 were evaluated. JI017 induced cell death that regulated apoptotic molecules and caused cell cycle arrest that inhibited the proliferation of cancer cells. Moreover, JI017 generated ROS. Accumulation of ROS caused ER stress through the PERK-eIF2α-CHOP and IRE1α-CHOP pathways. Furthermore, persistent activation of the UPR pathway induced by JI017 treatment triggered mitochondrial dysfunction, including dissipation of mitochondrial membrane potential, which activated intrinsic apoptotic pathway in human prostate cancer cells. The data indicated that N-acetyl-L-cysteine diminished apoptosis. We demonstrated that JI017 induced ER stress and cell death. Anticancer properties of JI017 in prostate cancer cells and in a human prostate cancer model involved ROS-mediated ER stress. Thus, JI017 treatment provides a new strategy for chemotherapy of prostate cancer.

Novel Carbazole-Piperazine Hybrid Small Molecule Induces Apoptosis by Targeting BCL-2 and Inhibits Tumor Progression in Lung Adenocarcinoma in Vitro and Xenograft Mice Model

Lung cancer is a type of deadly cancer and a leading cause of cancer associated death worldwide. BCL-2 protein is considered as an imperative target for the treatment of cancer due to their significant involvement in cell survival and death. A carbazole-piperazine hybrid molecule ECPU-0001 was designed and synthesized as a potent BCL-2 targeting agent with effective anticancer cancer activity. Interaction of ECPU-001 has been assessed by docking, molecular dynamics (MD) simulation, and thermal shift assay. Further, in vitro and in vivo anticancer activity was executed by cytotoxicity assay, FACS, colony formation and migration assay, western blotting, immunocyto/histochemistry and xenograft nude mice model. Molecular docking and MD simulation study confirmed that ECPU-0001 nicely interacts with the active site of BCL-2 by displaying a Ki value of 5.72 µM and binding energy (ΔG) of -8.35 kcal/mol. Thermal shift assay also validated strong interaction of this compound with BCL-2. ECPU-0001 effectively exerted a cytotoxic effect against lung adenocarnoma cells A459 with an IC50 value of 1.779 µM. Molecular mechanism of action have also been investigated and found that ECPU-0001 induced apoptosis in A459 cell by targeting BCL-2 to induce intrinsic pathway of apoptosis. Administration of ECPU-0001 significantly inhibited progression of tumor in a xenograft model without exerting severe toxicity and remarkably reduced tumor volume as well as tumor burden in treated animals. Our investigation bestowed ECPU-0001 as an effective tumoricidal agent which exhibited impressive anticancer activity in vitro as well as in vivo by targeting BCL-2 associated intrinsic pathway of apoptosis. Thus, ECPU-0001 may provide a valuable input for therapy of lung adenosarcoma in future, however, further extensive investigation of this compound will be needed.

Impact of missing individual patient data on 18 meta-analyses of randomised trials in oncology: Gustave Roussy experience

OBJECTIVE

To compare the characteristics, quality and treatment effects of randomised clinical trials (RCTs) by individual patient data (IPD) availability, in trials eligible for 18 IPD meta-analyses (MA).

DESIGN

Trial characteristics, risk of bias (RoB) and hazard ratio (HR) for overall survival were extracted from IPD-MA publications and/or RCTs publications. Data for the RoB assessment were extracted for a subset of 73 RCTs. Two investigators blinded to whether IPD was available or not evaluated the RoB for these trials. Treatment effects were compared using ratios of global HRs (RHRs) of IPD-unavailable trials and IPD-available trials. RHR were pooled using a fixed-effect model.

DATA SOURCES

We examined the IPD availability for each trial eligible for each IPD-MA; when the IPD was not available for a trial, we used information from published sources.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

We selected all published IPD-MAs conducted at Gustave Roussy and the RCTs eligible for each.

RESULTS

349 RCTs (73 018 patients) from 18 MAs were eligible: 60 RCTs (5890 patients) had unavailable IPD and 289 RCTs (67 128 patients) had available IPD. The main reason for IPD unavailability was data loss by investigators. IPD-unavailable trials were smaller (p<0.001), more often monocentric (p<0.001) and non-international (p=0.0004) than IPD-available trials. Geographical areas differed (p=0.054) between IPD-unavailable IPD-available trials. RoB was higher in IPD-unavailable RCTs for random sequence generation (p=0.007) and allocation concealment (p=0.006). The HR and 95% confidence interval (CI) for overall survival were extractable from publications in 23/60 IPD-unavailable trials included in 10 different MAs. Treatment effects were significantly greater for IPD-unavailable trials compared with IPD-available trials (RHR=0.86 (95% CI 0.75 to 0.98)).

CONCLUSIONS

IPD-unavailable RCTs were significantly different from IPD-available RCTs in terms of trial characteristics and were at greater RoB. IPD-unavailable RCTs had a significantly greater treatment effect.

Taxane-based Combination Therapies for Metastatic Prostate Cancer

CONTEXT

Multiple single-agent therapies improving survival are approved for the treatment of metastatic castration-resistant prostate cancer (mCRPC), including two chemotherapies, two androgen-signaling axis-targeting agents, an immunotherapeutic vaccine, and a radiopharmaceutical. Combination therapy can target multiple oncogenic pathways simultaneously, while potentially curbing the development of treatment resistance.

OBJECTIVE

To provide a succinct overview of taxane-based combination therapies currently being evaluated for the treatment of metastatic prostate cancer.

EVIDENCE ACQUISITION

We searched MEDLINE/PubMed^® and relevant congress databases for literature focused on taxane-based combination therapies being evaluated for the treatment of metastatic prostate cancer. In addition, a systematic search of www.clinicaltrials.gov was performed to gather information regarding ongoing taxane-based combination trials in prostate cancer. This search included phase II or III trials starting after January 1, 2010, which included the terms "docetaxel" or "cabazitaxel" and "prostate", and was then manually filtered for combination studies.

EVIDENCE SYNTHESIS

Single-agent therapy yields modest increments in survival. The success of combining docetaxel with androgen deprivation to improve overall survival (OS) for metastatic hormone-sensitive disease suggests the potential of similar approaches in mCRPC. Several classes of biological drugs have previously been combined with docetaxel for mCRPC in clinical trials without improvement in OS. However, combining docetaxel or cabazitaxel with newer agents with established single-agent benefit, such as radium-223, second-generation androgen pathway-targeted agents, or other chemotherapies, has the potential to benefit patients when compared with taxane chemotherapy alone. Our search revealed that the majority of trials currently assessing taxanes are focused on combination therapies: a combination approach is being evaluated in 37 of 47 trials assessing docetaxel and in 18 of 34 trials assessing cabazitaxel.

CONCLUSIONS

Despite prior failures, novel taxane-based combination therapies have the potential to improve outcomes in mCRPC. Challenges include the absence of validated predictive biomarkers for the selection of suitable patients and the potential for enhanced toxicity.

PATIENT SUMMARY

Patients with metastatic prostate cancer have access to multiple therapies improving survival. Many advanced epithelial cancers are treated with combinations of drugs; however, prostate cancer has remained an exception. A number of clinical studies have shown that combining chemotherapy with other classes of therapy may improve patient outcomes in prostate cancer. Here, we summarize the various combinations that are tested in the clinic and review the results.

The evolution of chemotherapy for the treatment of prostate cancer

Chemotherapy has been explored as a treatment option for metastatic prostate cancer since the early 1980s. Docetaxel, a taxane chemotherapeutic, was approved for the treatment of men with metastatic castration-resistant prostate cancer in 2004, and is now standard of care for late stage disease. Recent clinical studies demonstrated that patients with metastatic castration-sensitive disease, and possibly those with high-risk localized prostate cancer also benefit from docetaxel administration, expanding the role of chemotherapy in the prostate cancer treatment landscape. Another taxane, cabazitaxel, is approved for post-docetaxel metastatic castration-resistant prostate cancer. Taxanes and other chemotherapeutics, such as carboplatin, are now being tested in combination regimens. This review presents an outline of recent and ongoing clinical studies assessing docetaxel and its derivative cabazitaxel at different stages of the disease, and in various combinations with other agents. We summarize current knowledge on biomarkers predictive of response to chemotherapy, which may in future be used to guide individualized treatment decisions.

Phase 2 Study of Weekly Paclitaxel Plus Estramustine in Metastatic Hormone-Refractory Prostate Carcinoma: ECOG-ACRIN Cancer Research Group (E1898) Trial

INTRODUCTION

This multicenter phase 2 study assessed the combination of estramustine and weekly paclitaxel with metastatic castration-resistant prostate cancer (CRPC).

PATIENTS AND METHODS

We enrolled 77 patients who had received no prior chemotherapy for CRPC between 1998 and 2000; a total of 74 subjects were eligible for the study. Each 8-week cycle included paclitaxel 90 mg/m² provided intravenously weekly for 6 weeks, followed by 2 weeks off therapy and oral estramustine 280 mg twice daily for 3 days beginning 24 hours before the first dose of paclitaxel. The primary end point was rate of objective or prostate-specific antigen (PSA) response at 16 weeks. A 50% response rate was considered of further interest.

RESULTS

Eligible patients received a median of 3 cycles (range, 1-10 cycles). The response rate among patients with measurable disease was 34% (95% confidence interval [CI], 19-52). The PSA response rate was 58% (95% CI, 47-70). Clinical benefit rate was 45% (95% CI, 33-57). The median progression-free survival was 5.9 months (95% CI, 4.4-6.7). The median overall survival was 17.6 months (95% CI, 14.6-20.8). The most common clinical grade 3/4 toxicities were fatigue (14%) and sensory neuropathy (7%). Grade 3/4 hematologic toxicities included lymphopenia (21%) and anemia (9%). There was one toxicity-related death. Quality-of-life scores improved by week 8, but the change was not statistically significant.

CONCLUSION

The combination has activity defined by PSA declines in CRPC but did not meet the protocol-specified end point for efficacy as defined by objective response rate. Since this study was conducted, more effective, better-tolerated regimens have been developed.

Safety and Efficacy of Docetaxel, Bevacizumab, and Everolimus for Castration-resistant Prostate Cancer (CRPC)

BACKGROUND

Previous data suggests that co-targeting mammalian target of rapamycin and angiogenic pathways may potentiate effects of cytotoxic chemotherapy. We studied combining mammalian target of rapamycin and vascular endothelial growth factor inhibition with docetaxel in castrate-resistant prostate cancer (CRPC).

METHODS

Eligible patients had progressive, metastatic, chemotherapy-naive CRPC. Docetaxel and bevacizumab were given intravenously day 1 with everolimus orally daily on a 21-day cycle across 3 dose levels (75:15:2.5, 75:15:5, and 65:15:5; docetaxel mg/m2, mg/kg bevacizumab, and mg everolimus, respectively). Maintenance therapy with bevacizumab/everolimus without docetaxel was allowed after ≥ 6 cycles.

RESULTS

Forty-three subjects were treated across all dose levels. Maximal tolerated doses for the combined therapies observed in the phase 1B portion of the trial were: docetaxel 75 mg/m2, bevacizumab 15 mg/kg, and everolimus 2.5 mg. Maximal prostate-specific antigen decline ≥ 30% and ≥ 50% was achieved in 33 (79%) and 31 (74%) of patients, respectively. Best response by modified Response Evaluation Criteria In Solid Tumors criteria in 25 subjects with measurable disease at baseline included complete or partial response in 20 (80%) patients. The median progression-free and overall survival were 8.9 months (95% confidence interval, 7.4-10.6 months) and 21.9 months (95% confidence interval, 18.4-30.3 months), respectively. Hematologic toxicities were the most common treatment-related grade ≥ 3 adverse events including: febrile neutropenia (12; 28%), lymphopenia (12; 28%), leukocytes (10; 23%), neutrophils (9; 21%), and hemoglobin (2; 5%). Nonhematologic grade ≥ 3 adverse events included: hypertension (8; 19%), fatigue (3; 7%), pneumonia (3; 7%), and mucositis (4; 5%). There was 1 treatment-related death owing to neutropenic fever and pneumonia in a patient treated at dose level 3 despite dose modifications and prophylactic growth factor support.

CONCLUSIONS

Docetaxel, bevacizumab, and everolimus can be safely administered in CRPC and demonstrate a significant level of anticancer activity, meeting the predetermined response criteria. However, any potential benefit of combined therapy must be balanced against increased risk for toxicities. Our results do not support the hypothesis that this combination of agents improves upon the results obtained with docetaxel monotherapy in an unselected population of chemotherapy-naive patients with CRPC.

Low-Dose Oral Ethinylestradiol With Concomitant Low-Dose Acetylsalicylic Acid for Advanced Castrate-Resistant Prostate Cancer

BACKGROUND

The aim of the present study was to evaluate the activity and tolerability of low-dose oral ethinylestradiol (EE) and luteinizing hormone-releasing hormone analogue with concomitant low-dose acetylsalicylic acid (ASA) as a thromboprophylactic agent for advanced castrate-resistant prostate cancer (CRPC).

PATIENTS AND METHODS

The patients received an EE dose of 150 μg daily (50 μg 3 times daily) and an ASA dose of 100 mg once daily. The primary endpoint was the prostate-specific antigen response.

RESULTS

A total of 32 patients were enrolled. A PSA response was observed in 19 patients (59.3%; 95% confidence interval [CI], 41%-76%). The median progression-free survival was 9.4 months (95% CI, 6.5-14.1 months). The treatment was generally well tolerated and no grade 3-4 toxicity was observed. Only 1 patient interrupted EE because of a cardiac event and 1 patient experienced grade 2 nausea and vomiting. No major bleeding occurred.

CONCLUSION

Low-dose EE with concomitant low-dose ASA is safe, showing potential activity in patients with advanced CRPC, and should be investigated further.

Chemotherapy with or without estramustine for treatment of castration-resistant prostate cancer: A systematic review and meta-analysis

BACKGROUND

Recently, increasing relevant studies researched the efficacy of castration resistant prostate cancer (CRPC) patients using chemotherapy with or without estramustine, in order to assess the efficacy and toxicity of combining estramustine with chemotherapy for the treatment of CRPC.

METHODS

Relevant randomized clinical trials were systematically searched from the databases Pubmed, Embase, and Web of science up to April 1, 2016. Data were centrally extracted and analyzed from the previous studies by 2 independent reviewers. The primary endpoint was overall survival (OS) with pooled hazard ratios. Secondary endpoints were prostate-specific antigen (PSA) response and grade 3 or 4 toxicity using pooled odds ratios. Stata version 12.0 software was used for statistical analysis.

RESULTS

Overall, this meta-analysis identified 9 eligible articles, including a total of 956 patients, who had been accrued between January 1, 1993 and December 1, 2010 and randomly divided into chemotherapy with estramustine and without estramustine. Chemotherapy (with or without estramustine) consisted of docetaxel, paclitaxel, ixabepilone, epirubicin, and vinblastine. Patients who received chemotherapy with estramustine had a better improvement in PSA response rate, comparing those without estramustine (OR = 1.84, 95% CI = 1.20-2.80). However, OS between the 2 groups indicated no significant differences (HR = 0.90, 95% CI = 0.77-1.05). Besides, these results of meta-analysis showed no obvious differences between these 2 groups in grade 3 or 4 adverse effects, including anemia (OR = 0.78, 95% CI = 0.38-1.57), neutropenia (OR = 0.91, 95% CI = 0.59-1.43), thrombocytopenia (OR = 0.68, 95% CI = 0.19-2.42), nausea (OR = 2.34, 95% CI = 0.81-6.72), vomiting (OR = 2.43, 95% CI = 0.69-8.51), diarrhea (OR = 3.45, 95% CI = 0.93-12.76), fatigue (OR = 0.67, 95% CI = 0.32-1.41), neuropathy (OR = 0.54, 95% CI = 0.21-1.44), allergic reaction (OR = 1.60, 95% CI = 0.37-6.84), thromboembolic event (OR = 2.18, 95% CI = 0.86-5.51), and edema (OR = 1.02, 95% CI = 0.18-5.95).

CONCLUSIONS

This meta-analysis indicated chemotherapy with additional estramustine increased the PSA response rate. However, OS and grade 3 or 4 toxicity were not improved for these patients with CRPC.

A Randomised Phase II Trial Comparing Docetaxel Plus Prednisone with Docetaxel Plus Prednisone Plus Low-Dose Cyclophosphamide in Castration-Resistant Prostate Cancer

BACKGROUND

Docetaxel plus prednisone is a standard treatment for castration-resistant prostate cancer. Cyclophosphamide may be an effective combination partner.

METHODS

This randomised, multicentre, phase II trial compared the combination therapy of docetaxel plus prednisone plus cyclophosphamide with the standard therapy of docetaxel plus prednisone.

RESULTS

Thirty-three patients received six 3-week treatment cycles (in total 171 cycles). During treatment, an adequate decline in prostate-specific antigen was seen in both groups (p = 0.068) without between-group differences (p = 0.683). No relevant differences between within-group changes were observed for blood pressure, weight, pain score, laboratory variables or quality of life. There were no serious side effects apart from leucopenia requiring treatment (docetaxel + prednisone + cyclophosphamide arm) and no drug-related withdrawals; all three fatalities were considered to be cancer related.

CONCLUSIONS

The oncological effectiveness and tolerability of docetaxel plus prednisone were supported; an additional effect of cyclophosphamide was not detected. However, the small number of patients and short observation period restrict the generalisability of the results.

Bias and precision of measures of survival gain from right-censored data

In cost-effectiveness analyses of drugs or health technologies, estimates of life years saved or quality-adjusted life years saved are required. Randomised controlled trials can provide an estimate of the average treatment effect; for survival data, the treatment effect is the difference in mean survival. However, typically not all patients will have reached the endpoint of interest at the close-out of a trial, making it difficult to estimate the difference in mean survival. In this situation, it is common to report the more readily estimable difference in median survival. Alternative approaches to estimating the mean have also been proposed. We conducted a simulation study to investigate the bias and precision of the three most commonly used sample measures of absolute survival gain--difference in median, restricted mean and extended mean survival--when used as estimates of the true mean difference, under different censoring proportions, while assuming a range of survival patterns, represented by Weibull survival distributions with constant, increasing and decreasing hazards. Our study showed that the three commonly used methods tended to underestimate the true treatment effect; consequently, the incremental cost-effectiveness ratio (ICER) would be overestimated. Of the three methods, the least biased is the extended mean survival, which perhaps should be used as the point estimate of the treatment effect to be inputted into the ICER, while the other two approaches could be used in sensitivity analyses. More work on the trade-offs between simple extrapolation using the exponential distribution and more complicated extrapolation using other methods would be valuable.

Chemotherapy plus estramustine for management of castration-resistant prostate cancer: meta-analysis of randomized controlled trials

OBJECTIVE

Estramustine, an agent with both hormonal and non-hormonal effects in men, is supposed to be effective in treating castration-resistant prostate cancer. However, previous studies have reported conflicting results. We conducted this meta-analysis to evaluate the efficacy and toxicity of additional estramustine to chemotherapy.

METHODS

Data sources including PubMed, Medline, EMBASE, and Cochrane Controlled Trials Register were searched to identify potentially relevant randomized controlled trials. Prostate specific antigen (PSA) response, overall survival, and grade 3 to 4 toxicity were analyzed.

RESULTS

Seven randomized controlled trials, a total of 839 patients, were enrolled. The pooled odds ratio for PSA response was 3.02 (95% CI=1.69-5.39, P=.0002); the pooled hazard ratio for overall survival was .95 (95% CI=.80-1.14, P=.58); the pooled odds ratio for nausea/vomiting and cardiovascular toxicity were 3.90 (95% CI=1.05-14.45, P=.04) and 2.22 (95% CI=1.15-4.30, P=.02). No significant difference was detected for neutropenia, anemia, thrombocytopenia, diarrhea, fatigue, or neuropathy (P>.05).

CONCLUSIONS

According to this meta-analysis, chemotherapy with additional estramustine increased the PSA response rate. However, it increased the risk of grade 3 or 4 adverse effects such as nausea/vomiting and cardiovascular events, and the overall survival was not improved for castration-resistant prostate cancer patients.

Taxanes in the management of metastatic castration-resistant prostate cancer: efficacy and management of toxicity

Androgen deprivation is the therapy of choice in the majority of patients with metastatic prostate cancer. However, a state of castration resistance ultimately occurs after hormone therapy, thus defining metastatic castration-resistant prostate cancer (mCRPC). mCRPC has historically been considered a relatively chemoresistant tumor. However, due to its ability to improve survival and the quality of life in comparison with mitoxantrone, docetaxel has been established as the standard chemotherapeutic agent for first-line therapy since 2004. Moreover, recent results have shown that the novel taxane cabazitaxel is able to prolong the overall survival of patients with mCRPC previously treated with docetaxel. Even though these taxanes display a favorable toxicity profile, their routine use in clinical practice requires knowledge about the most frequent and distinct adverse events that may result from their administration.

Tumor models for prostate cancer exemplified by fibroblast growth factor 8-induced tumorigenesis and tumor progression

Prostate cancer is a very common malignancy among Western males. Although most tumors are indolent and grow slowly, some grow and metastasize aggressively. Because prostate cancer growth is usually androgen-dependent, androgen ablation offers a therapeutic option to treat post-resection tumor recurrence or primarily metastasized prostate cancer. However, patients often relapse after the primary response to androgen ablation therapy, and there is no effective cure for cases of castration-resistant prostate cancer (CRPC). The mechanisms of tumor growth in CRPC are poorly understood. Although the androgen receptors (ARs) remain functional in CRPC, other mechanisms are clearly activated (e.g., disturbed growth factor signaling). Results from our laboratory and others have shown that dysregulation of fibroblast growth factor (FGF) signaling, including FGF receptor 1 (FGFR1) activation and FGF8b overexpression, has an important role in prostate cancer growth and progression. Several experimental models have been developed for prostate tumorigenesis and various stages of tumor progression. These models include genetically engineered mice and rats, as well as induced tumors and xenografts in immunodeficient mice. The latter was created using parental and genetically modified cell lines. All of these models greatly helped to elucidate the roles of different genes in prostate carcinogenesis and tumor progression. Recently, patient-derived xenografts have been studied for possible use in testing individual, specific responses of tumor tissue to different treatment options. Feasible and functional CRPC models for drug responsiveness analysis and the development of effective therapies targeting the FGF signaling pathway and other pathways in prostate cancer are being actively investigated.

[Hormonal treatment in prostate cancer]

AIM

To describe drugs used in the hormonal treatment (hormonotherapy) of prostate cancer.

MATERIAL

Bibliographical search was performed from the database Medline (National Library of Medicine, PubMed) and websites of the HAS and the ANSM. The search was focused on the characteristics, the mode of action, the efficiency and the side effects of the various drugs concerned.

RESULTS

LHRH analogs and the antiandrogens remain the cornerstone in the treatment of locally advanced and metastatic prostate cancer. New therapeutic classes emerged recently (inhibitor of the synthesis of the androgen, the new antiandrogens) and allowed to grow again the limits of the hormone resistance and define the concept castration-resistant prostate cancer.

CONCLUSION

The hormonal treatment of the prostate cancer grew rich of new therapeutic classes which are going to change the medical care of the prostate cancer in the coming years and the urologist must play its full part.

[The non-hormonal treatment of metastatic prostate cancer]

AIM

To describe drugs used in the non-hormonal treatment of metastatic prostate cancer.

MATERIAL

Bibliographical search was performed from the database Medline (National Library of Medicine, PubMed) and websites of the HAS and the ANSM. The search was focused on the characteristics, the mode of action, the efficiency and the side effects of the various drugs concerned.

RESULTS

The metabolic radiotherapy although under-used for this indication, kept a place at the beginning of the disease. Radium-223 chloride seems to have to occupy an important place in the coming years. The chemotherapy, the only recourse until very recently in the castration-resistant prostate cancer, must redefine its place partially. The denosumab provide an interesting alternative to bisphosphonates.

CONCLUSION

The non-hormonal treatment of the metastatic disease of the prostate cancer is changing rapidly with the emergence of new molecules. Urologist must know perfectly these new drugs.

Tubulin-targeted agents including docetaxel and cabazitaxel

Microtubules are dynamic filamentous cytoskeletal proteins that are responsible for cellular integrity and architecture, mitosis, intracellular transport, cell signaling, and gene expression. Tubulin exists in the cell as dimers of α and β subunits, which complexes with a variety of regulatory proteins. There is a dynamic equilibrium between free and polymerized tubulin causing a state called "dynamic instability," which is a target of anticancer drugs, which inhibit tubulin through polymerization (taxanes, epothilones) or depolymerization (vinca alkaloids). Docetaxel-based therapy was the first such treatment to demonstrate a survival benefit in men with castration-resistant prostate cancer. Cabazitaxel, an antitubulin agent, which demonstrates activity in multidrug- and docetaxel-resistant cancer cell lines, demonstrates a survival benefit over mitoxantrone and prednisone in patients who have failed docetaxel-based chemotherapy. This article reviews the use of antitubulin agents in patients with castration-resistant prostate cancer.

Promise and challenges in drug discovery and development of hybrid anticancer drugs

BACKGROUND

Because cancer is a complex disease, it is unlikely that a single mono functional 'targeted' drug will be effective for treating this most advanced disease. Combined drugs that impact multiple targets simultaneously are better at controlling complex disease systems, are less prone to drug resistance and are the standard of care in cancer treatment. In order to improve the efficiency of using a two-drug cocktail, one approach involves the use of the so-called hybrid drugs, which comprises the incorporation of two drugs in a single molecule with the intention of exerting dual drug action.

OBJECTIVE

In the present article, we discuss the design, synthesis and various applications of anticancer hybrid agents and the developments in this field during the last few decades. Additionally, we describe different types of linkers and their role in contributing towards biological effects and the in vivo mechanism of drug release. We also depict some challenges from scientific and regulatory perspectives in the hybrid drug development process.

CONCLUSION

In the era of increasing drug resistance in cancer patients, the discovery of hybrid drugs could provide an effective strategy to create chemical entities likely to be more efficacious and less prone to resistance. However, some technical and regulatory challenges will have to be surmounted before hybrid drugs succeed in the clinical settings and justify the considerable promise of this novel concept.

Weekly, low-dose docetaxel combined with estramustine for Japanese castration-resistant prostate cancer: its efficacy and safety profile compared with tri-weekly standard-dose treatment

BACKGROUND

We retrospectively investigated the efficacy and safety profile of weekly low-dose docetaxel (DTX) with estramustine in comparison with triweekly standard-dose DTX treatment for Japanese patients with castration-resistant prostate cancer (CRPC).

METHODS

Between April 2002 and January 2011, 75 CRPC patients were treated with triweekly DTX (60-75 mg/m(2) every 3 weeks) (standard-dose group), and 76 CRPC patients were treated with weekly low-dose DTX (20-30 mg/m(2) on days 2 and 9 with estramustine 560 mg on days 1-3 and 8-10) every 3 weeks (low-dose group). Prostate-specific antigen (PSA) response and progression-free and overall survival were analyzed in each group.

RESULTS

Median serum PSA level of the standard-dose group and low-dose group was 25.0 and 35.5 ng/ml, respectively. In the standard-dose and low-dose groups, 57.8 and 65.2 % of patients, respectively, achieved a PSA decline ≥ 50 %. There was no significant difference in either median time to progression between the standard-dose group (10.0 months) and low-dose group (7.1 months) or in median duration of survival between the standard-dose group (24.2 months) and low-dose group (30.6 months). Multivariate analysis with a Cox proportional hazards regression model showed that DTX treatment protocol did not influence the risk of death. Incidences of grade 3-4 neutropenia, febrile neutropenia, and thrombocytopenia were significantly higher in the standard-dose versus low-dose group (58.7 vs. 7.9 %, 16.0 vs. 3.9 %, and 8.0 vs. 0 %, respectively).

CONCLUSION

For Japanese CRPC patients, weekly low-dose DTX combined with estramustine has similar efficacy to standard-dose DTX but with fewer adverse events.

Abiraterone acetate for treatment of metastatic castration-resistant prostate cancer: final overall survival analysis of the COU-AA-301 randomised, double-blind, placebo-controlled phase 3 study

BACKGROUND

Abiraterone acetate improved overall survival in metastatic castration-resistant prostate cancer at a preplanned interim analysis of the COU-AA-301 double-blind, placebo-controlled phase 3 study. Here, we present the final analysis of the study before crossover from placebo to abiraterone acetate (after 775 of the prespecified 797 death events).

METHODS

Between May 8, 2008, and July 28, 2009, this study enrolled 1195 patients at 147 sites in 13 countries. Patients were eligible if they had metastatic castration-resistant prostate cancer progressing after docetaxel. Patients were stratified according to baseline Eastern Cooperative Oncology Group (ECOG) performance status, worst pain over the past 24 h on the Brief Pain Inventory-Short Form, number of previous chemotherapy regimens, and type of progression. Patients were randomly assigned (ratio 2:1) to receive either abiraterone acetate (1000 mg, once daily and orally) plus prednisone (5 mg, orally twice daily) or placebo plus prednisone with a permuted block method via an interactive web response system. The primary endpoint was overall survival, analysed in the intention-to-treat population. This study is registered with ClinicalTrials.gov, number NCT00091442.

FINDINGS

Of the 1195 eligible patients, 797 were randomly assigned to receive abiraterone acetate plus prednisone (abiraterone group) and 398 to receive placebo plus prednisone (placebo group). At median follow-up of 20·2 months (IQR 18·4-22·1), median overall survival for the abiraterone group was longer than in the placebo group (15·8 months [95% CI 14·8-17·0] vs 11·2 months [10·4-13·1]; hazard ratio [HR] 0·74, 95% CI 0·64-0·86; p<0·0001). Median time to PSA progression (8·5 months, 95% CI 8·3-11·1, in the abiraterone group vs 6·6 months, 5·6-8·3, in the placebo group; HR 0·63, 0·52-0·78; p<0·0001), median radiologic progression-free survival (5·6 months, 5·6-6·5, vs 3·6 months, 2·9-5·5; HR 0·66, 0·58-0·76; p<0·0001), and proportion of patients who had a PSA response (235 [29·5%] of 797 patients vs 22 [5·5%] of 398; p<0·0001) were all improved in the abiraterone group compared with the placebo group. The most common grade 3-4 adverse events were fatigue (72 [9%] of 791 patients in the abiraterone group vs 41 [10%] of 394 in the placebo group), anaemia (62 [8%] vs 32 [8%]), back pain (56 [7%] vs 40 [10%]), and bone pain (51 [6%] vs 31 [8%]).

INTERPRETATION

This final analysis confirms that abiraterone acetate significantly prolongs overall survival in patients with metastatic castration-resistant prostate cancer who have progressed after docetaxel treatment. No new safety signals were identified with increased follow-up.

Docetaxel in combination with estramustine and prednisolone for castration-resistant prostate cancer

BACKGROUND

The aim of this study was to investigate the efficacy and toxicity of docetaxel-based chemotherapy, and to investigate pretreatment factors that can predict overall survival (OS) in patients with castration-resistant prostate cancer (CRPC).

METHODS

From June 2005 to July 2010, 70 patients with CRPC underwent docetaxel-based chemotherapy at Wakayama Medical University and related hospitals. Docetaxel was given at a dose of 70 mg/m(2) once every 3 weeks or 35 mg/m(2) twice every 3 weeks. Oral estramustine 560 mg was given concurrently for five consecutive days during weeks 1 and 2 of each cycle, and prednisolone 10 mg was given every day. Dexamethasone 8 mg was premedicated intravenously before docetaxel administration.

RESULT

The patients received a median of four cycles of treatment (range 1-31). In the serum prostate-specific antigen response, 13 (18.6%) patients achieved a complete response and 29 (41.4%) achieved a partial response. Median OS and time to progression were 14 months and 6 months, respectively. Median follow-up period was 9.5 months. Two independent pretreatment risk factors that predicted OS were visceral metastasis including lymph node metastasis and anemia. Grade 3/4 neutropenia and anemia occurred in 25.7 and 8.6% of the patients, respectively. Four treatment-related deaths were seen during the observation period.

CONCLUSION

The combination of docetaxel, estramustine and prednisolone was effective in Japanese patients with CRPC; however, this combination therapy should be carefully indicated to elderly and/or poor performance status patients due to its toxicity. Visceral metastasis and anemia were identified as independent risk factors which could predict OS.

Weekly low-dose docetaxel combined with estramustine and dexamethasone for Japanese patients with metastatic castration-resistant prostate cancer

BACKGROUND

A low-dose chemotherapy consisting of docetaxel, estramustine and dexamethasone was investigated for its beneficial effect and feasibility in Japanese patients with metastatic castration-resistant prostate cancer (CRPC).

METHODS

Seventy-two Japanese patients with metastatic CRPC were enrolled to receive docetaxel (25 mg/m(2) on days 2 and 9), estramustine phosphate (280 mg orally twice daily from day 1 to day 3 and from day 8 to day 10) and dexamethasone (0.5 mg orally twice daily) every 21 days.

RESULTS

The median age of the patients was 72 years and 64 patients (89 %) had ≥grade 1 anemia at entry. The median total number of courses administered was 8.5 (range 1-93). Forty-two patients (58 %) had a prostate-specific antigen (PSA) decline of ≥50 %. The median progression-free survival and overall survival were 6 and 23 months, respectively. Fifteen patients (21 %) improved and 53 patients (74 %) were stable in their performance status. Of the 40 patients with bone pain, 25 patients (63 %) showed pain reduction. Among 71 patients assessable for their hemoglobin levels, 21 patients (30 %) achieved an increase of at least 1.0 g/dl. Of the 5 patients who terminated treatment because of ≥grade 3 toxicity, 4 patients had pneumonitis and one patient had anemia. Only one patient developed ≥grade 3 neutropenia.

CONCLUSIONS

The low-dose combination of docetaxel, estramustine and dexamethasone is active and tolerable with beneficial effects on serum PSA levels, performance status, anemia and bone pain in Japanese patients with CRPC. This regimen is a reasonable option for elderly patients with bone disease at risk of hematologic toxicity.

[Strategy in advanced castration-resistant prostate cancer]

If androgen deprivation, chemical with LH-RH analogs or surgical with bilateral orchiectomy, still remains the stone edge of treatment of prostate cancer, in the metastatic setting, this hormonosensitivity, most of the time long, finally move on in hormonal-failure. If rare changes in the therapeutic strategy have been achieved in this setting since 2004 and the arrival of docetaxel, it is the global perception of the disease that has been modified and the definition of one specific entity: the castrate-resistant prostate cancer. This new definition and the changes of design and end-points of clinical trials testing new agents with strong recruitment during the past years have conducted to a real revolution in the management of castrate-refractory prostate cancer. The place of secondary hormonal manipulations, such as withdrawal of the anti-androgen, oestrogen or ketoconazole, still exists for a selected group of patients. In case of aggressive disease and symptoms, chemotherapy should be selected, docetaxel, in a three weeks schedule, and may be combined with Estracyt. It is time to consider the revolution of the post-chemotherapy setting with the arrival of two new drugs ; a cytotoxic one, the cabazitaxel and hormonal for the second one, the abiraterone acetate. The place of the immunotherapy with the sipuleucel-T may be more difficult to precise, especially in Europe, even if it has been finally indicated in the United States in the metastatic setting. Concerning bone metastasis, zoledronic acid was during a long time the only bone-targeted agent, effective in reducing the incidence of skeletal related events, and was recently exceeded by the denosumab, an anti-RANK ligand. Finally, let us hope that other changes will be achieved in the near future, with the cabazitaxel-docetaxel confrontation in the first-line setting, and the introduction of the abiraterone acetate before chemotherapy with docetaxel, already tested in ongoing trials.

[Prostate cancer and chemotherapy: standards care and perspectives]

Docetaxel is a reference treatment of metastatic prostate cancer castration-resistant. Until now, the different associations were studied without benefit when compared to docetaxel as monotherapy. Cabazitaxel showed efficacy in second-line in patients with progressive disease during or after docetaxel chemotherapy. Other molecules are being evaluated in second-line post-docetaxel. Abiraterone acetate is an alternative treatment to cabazitaxel in metastatic second-line resistant to castration. Predictive factors to choice treatment must be evaluated and proposed to personalize treatment in the future. Docetaxel activity was also studied in early stage of prostate cancer and seems to be promising. A cabazitaxel activity in early stage of cancer is also being evaluated.

Docetaxel with or without estramustine for estramustine refractory castration-resistant prostate cancer: a single institution experience

BACKGROUND

The significance of combination of docetaxel (DTX) with estramustine phosphate (EMP) in castration-resistant prostate cancer (CRPC) patients remains unclear. In this study, we aimed to retrospectively evaluate the efficacy and toxicity of DTX with or without EMP and to elucidate the significance of DTX and EMP combination therapy in Japanese EMP-refractory CRPC patients.

METHODS

To compare the efficacy and toxicity of DTX and EMP, we divided CRPC patients, who were confirmed to be resistant to EMP, into the following two groups: group D (n = 28), which included patients treated with DTX (60 mg/m2, once in every four weeks) alone, and group DE (n = 33), which included patients treated with a combination of DTX (60 mg/m2, once in every four weeks) and EMP (twice daily oral administration at 280 mg).

RESULTS

Prostate specific antigen (PSA) response (> 50% decline in PSA) was observed in six patients (21%) in group D and eight patients (24%) in group DE. The median time to progression (TTP) was 12.0 months and 6.2 months and the median overall survival (OS) was 26.4 months and 24.3 months in group D and DE, respectively. There was no statistical difference between the two groups in terms of PSA response, TTP, and OS. The incidence of adverse events of grade 3/4 was low in both the groups, and there was no statistical difference between the two groups.

CONCLUSIONS

Although treatment with DTX at 60 mg/m2 was effective and highly tolerated in EMP-refractory Japanese CRPC patients, the DTX and EMP combination therapy might not exhibit any survival benefit for CRPC patients.

Cabazitaxel for the treatment of castration-resistant prostate cancer

Treatment with docetaxel-based chemotherapy results in improved survival in patients with metastatic castration-resistant prostate cancer. However, all patients eventually develop progressive disease associated with poor outcomes. In this article, we discuss the available second-line therapeutic options following docetaxel, with a special focus on cabazitaxel, which is the first agent to yield extended survival as second-line therapy following docetaxel. Cabazitaxel, a novel semi-synthetic taxane, is effective even in docetaxel-resistant model systems. Recently, results of the Phase III TROPIC trial demonstrated improved survival with cabazitaxel plus prednisone compared with mitoxantrone and prednisone in patients with progressive metastatic castration-resistant prostate cancer, following prior docetaxel, which led to approval by the US FDA.

Ten years of docetaxel-based therapies in prostate adenocarcinoma: a systematic review and meta-analysis of 2244 patients in 12 randomized clinical trials

BACKGROUND

Chemotherapy can reduce serum prostate-specific antigen (PSA) levels and relieve pain in some patients with castration-resistant prostate cancer (CRPC). To improve therapeutic efficacy numerous randomized trials have investigated docetaxel-based combination regimens. The present analysis tries to overcome the statistical limitations of the individual trials and investigates the treatment effects in total and in various combination groups.

METHODS

The Medline, Embase, Cancerlit, and American Society of Clinical Oncology Abstract databases were searched for published randomized placebo-controlled trials evaluating the use of docetaxel-based regimens in patients with CRPC. The outcomes assessed were overall survival, overall response rate, PSA response rate, and adverse effects.

RESULTS

Twelve articles (2244 participants) were included in the meta-analysis. The analysis demonstrates a higher PSA response rate from docetaxel-based combinations when compared with docetaxel alone (relative risk [RR] = 1.16; P = .010). The estimated median survival in docetaxel-based combinations was statistically significantly longer than in the docetaxel-alone group (22.0 vs. 18.4 months; P = .037). Grade 3 or 4 neutropenia as well as grade 3 or 4 thromboembolic events were similar in both arms (overall RR, 0.87 [confidence interval (CI) 0.71-1.07]; P = .20 and overall RR 1.52 [0.79 - 2.90]; P = .21, respectively).

CONCLUSION

The analysis of 12 randomized trials provides evidence in favor of docetaxel-based combination chemotherapy for patients with CRPC and good performance status.

Oncological outcome of docetaxel-based chemotherapy for Japanese men with metastatic castration-resistant prostate cancer

OBJECTIVES

To retrospectively review the oncologic outcomes of docetaxel-based chemotherapy in Japanese men with metastatic castration-resistant prostate cancer (mCRPC).

MATERIALS AND METHODS

This study included 257 consecutive Japanese patients with mCRPC who were treated with docetaxel-based chemotherapy between April 2007 and March 2010. The prognostic significance of several clinicopathologic factors in these patients was analyzed.

RESULTS

In these 257 patients, the median age and serum value of prostate-specific antigen (PSA) prior to docetaxel-based chemotherapy were 72 years and 43.0 ng/ml, respectively. Of these patients, 64 (24.9%) and 193 (75.1%) received docetaxel as a weekly (30 mg/m(2)) and 3-weekly (70-75 mg/m(2)) regimen, respectively, and estramustine (EM) was administered in combination with docetaxel in 137 (53.3%). PSA decline was observed in 205 patients (79.8%), including 143 (55.6%) achieving PSA decline ≥ 50%. The median progression-free survival and overall survival (OS) were 4.3 and 25.4 months, respectively. Of several factors examined, univariate analysis identified performance status (PS), PSA value, significant clinical pain, bone metastasis, prior treatment with EM, treatment cycle, and PSA response as significant predictors of OS, of which only PS, significant clinical pain, prior treatment with EM, treatment cycle, and PSA response appeared to be independently related to OS on multivariate analysis. Furthermore, there were significant differences in OS according to positive numbers of these 5 independent risk factors.

CONCLUSIONS

Oncologic outcomes in Japanese mCRPC patients receiving docetaxel-based chemotherapy is generally favorable, and the risk stratification presented in this study may contribute to precisely predicting the prognosis of such patients.

The use of estramustine phosphate in the modern management of advanced prostate cancer

What's known on the subject? and What does the study add? Estramustine phosphate has anti-tumour properties and it improves patient outcomes if combined with other chemotherapy agents such as docetaxel. The efficacy of estramustine phosphate in selected patients and its safety profile, provided used with any low-molecular-weight heparin support its use as a second-line treatment in hormone-resistant prostate cancer.

OBJECTIVES

•  Estramustine phosphate is a nitrogen mustard derivative of estradiol-17β-phosphate and has anti-tumour properties. •  Interest in estramustine has been renewed because of the results of clinical studies showing improved patient outcomes if estramustine is combined with other chemotherapy agents such as docetaxel.

PATIENTS AND METHODS

•  Relevant clinical studies using chemotherapy combinations including estramustine are discussed. •  Efficacy and safety outcomes are summarized.

RESULTS

•  Combination therapy with estramustine and docetaxel can increase PSA response rates, improve quality of life and increase median patient survival compared with chemotherapy regimens that do not include estramustine. •  Although the overall tolerability of estramustine is favourable, its use can be associated with an increased risk of thromboembolic events.

CONCLUSIONS

•  The identification of suitable patient groups and the effective management of the risk of thromboembolism with the adjunct of low-molecular-weight heparins support the use of estramustine as an effective second-line treatment strategy in hormone-resistant prostate cancer. •  These promising findings warrant further investigation in a randomized clinical trial.

Targeting continued androgen receptor signaling in prostate cancer

Prostate cancer is the most common cancer and the second leading cause of death from cancer in males in most Western countries. Prostate cancer has an exquisite sensitivity to androgen deprivation therapy and is the most endocrine-sensitive solid neoplasm, although advanced disease eventually progresses to castration-resistant prostate cancer (CRPC). Recent evidence has shown that cancer progression at the CRPC stage is often mediated by androgen receptor signaling, so that subsequent androgen receptor targeting may further contribute to disease control and, eventually, survival improvement. Abiraterone acetate, an androgen biosynthesis inhibitor, was tested in patients with CRPC pretreated with docetaxel in a phase III trial with demonstration of an overall survival benefit, confirming that CRPC remains hormone driven, even in advanced stages of the disease. Several novel agents also targeting androgen receptor signaling are currently being evaluated, including MDV3100 and orteronel (TAK-700). With the availability of newer endocrine treatments and also nonendocrine treatments (e.g., chemotherapy, immunotherapy, and bone-targeting agents), data supporting a more rational use of therapeutic agents are urgently required in patients with CRPC. It is likely that molecular characterization of prostate cancer will lead to the identification of different subsets of prostate cancer disease with a different natural history, sensitivity, and resistance to treatment; efforts to develop, validate, and implement predictive biomarkers in clinical trials and eventually in routine care should now be strongly supported.

Current and emerging treatment modalities for metastatic castration-resistant prostate cancer

Docetaxel-based therapy is established as the standard first-line chemotherapy in patients with metastatic castration-resistant prostate cancer (mCRPC), based on results from two landmark Phase III studies. However, prognosis remains poor, with a median survival of less than 2 years. There is no standard of care for patients who progress during or after docetaxel treatment, which represents a real unmet medical need. Several small retrospective studies suggest that patients with mCRPC who responded to first-line docetaxel-based therapy are sensitive to re-treatment, but a survival benefit in prospective randomized trials has not been demonstrated. Epithelial-stromal interactions in the tumour microenvironment appear to play a central role in prostate cancer progression and response to therapy. Recent insights into the molecular mechanisms that underpin prostate cancer progression have allowed the identification of potential therapeutic targets. New agents, including angiogenesis inhibitors, hormone therapies, chemotherapies, bone targeting agents, vaccines and immunotherapies are currently undergoing clinical development in advanced prostate cancer using docetaxel as a backbone. Several Phase III studies have now been completed. Sipuleucel-T prolonged survival compared with placebo in asymptomatic or minimally symptomatic patients with mCRPC. Cabazitaxel plus prednisone prolonged survival in patients with mCRPC who progressed during or after docetaxel-based therapy compared with the active agent mitoxantrone, plus prednisone. Multidisciplinary management and optimization of the role and timing of new agents in this evolving treatment continuum will be critical to maximizing patient outcomes. Identification of predictive markers and better gene expression profiling will be critical to tailoring therapies to individual patients and disease states, whereas validated surrogate markers of overall survival will help accelerate drug approval.

New strategies for medical management of castration-resistant prostate cancer

Although advanced prostate cancer patients respond very well to front-line androgen deprivation, failure to hormonal therapy most often occurs after a median time of 18-24 months. The care of castration-resistant prostate cancer (CRPC) has significantly evolved over the past decade, with the onset of first-line therapy with docetaxel. Although numerous therapy schedules have been investigated alongside docetaxel, in either first-line or salvage therapy, results were dismal. However, CRPC chemotherapy is currently evolving, with, on the one hand, new agents targeting androgen metabolism and, on the other hand, significant progress in chemotherapy drugs, particularly for second-line therapy. The aim of the present review is to describe the current treatments for CRPC chemotherapy alongside their challengers that might shortly become new standards. In this article, we discuss the most recent data from clinical trials to provide the reader with a comprehensive, state-of-the-art overview of CRPC chemotherapy and hormonal therapy.

Effective oral combination metronomic chemotherapy with low toxicity for the management of castration-resistant prostate cancer

Prostate cancer (PC) was previously believed to be a chemoresistant disease. In recent years taxane-based chemotherapy has been shown to prolong survival in patients with castration-resistant prostate cancer (CRPC). It remains to be shown, however, which type of chemotherapy provides the most beneficial effect with the least amount of side effects. Seventeen patients with chemonaive CRPC were enrolled in a pilot study evaluating an orally administered chemo-hormonal treatment regimen using a weekly sequential combination called KEES; consisting of ketoconazole in combination with cyclophosphamide or etoposide in combination with estramustine administered on alternate weeks. Prednisone was administered throughout the treatment period. Prostate-specific antigen (PSA) response and acute and chronic toxicities were evaluated. Seventeen patients with CRPC were treated; eleven patients demonstrated a median reduction in PSA of 87% (range 26-99%). Ten (59%) patients responded with a decrease in PSA >50%. Thrombocytopenia and anaemia were the most common side effects. One study fatality was reported, however, it was unclear whether this was treatment related. In conclusion, KEES may be a promising option for patients with CRPC, resulting in a clear reduction in PSA with limited toxicity. Further clinical evaluation of this metronomic chemohormonal combination is underway.