Optimizing the use of docetaxel in men with castration-resistant metastatic prostate cancer

Maintenance Long-Term Multiple Cycles Treatment with Docetaxel in Metastatic Castration-Resistant Prostate Cancer: A Report of Three Cases

Prostate cancer (PCa) is one of the most common types of malignancy, most patients with PCa will eventually progress to metastatic castration-resistant prostate cancer (mCRPC), which has a poor prognosis. Since 2004, chemotherapy has been approved by the FDA as the first-line treatment for mCRPC, and docetaxel-based regimens have been shown to improve both the patients’ symptoms and overall survival (OS). 10 cycles of docetaxel therapy are usually given to patients with mCPRC, but there is still no consensus on the optimal number of treatment cycles. Here, we present three cases of mCRPC patients that received maintenance long-term multiple-cycles docetaxel treatment. We believe that this new treatment strategy may benefit carefully selected mCRPC patients and provide several key advantages such as maximum exposure to drugs, improvements in drug efficacy, and reduce the risk of developing drug resistance.

Cyclopentadienyl ruthenium(II) carbosilane metallodendrimers as a promising treatment against advanced prostate cancer

In searching for efficient and selective antitumour drugs, a new family of carbosilane metallodendrimers functionalized with [Ru(η⁵-C₅H₅)(PTA)Cl] (PTA = 1,3,5-triaza-7-phosphatricyclo-[3.3.1.1] decane) is reported. Experiments of the biophysical characterization showed an ability to interact with biological membranes, as well as with proteins (e.g. human serum albumin) without affecting their usual biological activity. These metallodendrimers possessed potent and selective anticancer activity in vitro in a panel of tumour cell lines. Importantly, the first generation metallodendrimer, bearing 4 Ru(II) complexes, was remarkably active towards resistant prostate cancer cells, inhibiting both cell proliferation and metastasis to bone tissues. Such promising antitumour activity can be further improved when given with docetaxel, with in vitro cytotoxicity being in the nanomolar range. Furthermore, its intravenous administration to an advanced prostate cancer mice model inhibited tumour growth up to 25% and 45% when given 10 mg/kg/week and 7.5 mg/kg/4-5 days, respectively.

Metastatic castration-resistant prostate cancer: time for innovation

Androgen deprivation is the mainstay of advanced prostate cancer treatment. Despite initial responses, almost all patients progress to castration-resistant prostate cancer (CRPC). The understanding of the biology of CRPC and the evidence that CRPC still remains driven by androgen receptor signaling led to the discovery of new therapeutic targets. In the last few years, large Phase III trials showed improvements in survival and outcomes and led to the approval of a CYP17 inhibitor (abiraterone), an androgen receptor antagonist (enzalutamide), the taxane cabazitaxel, an α-emitter (radium-223), the bone resorption-targeting drug denosumab and an immunotherapy (sipuleucel-T). This article describes the molecular mechanisms underlying castration resistance, discusses recent and ongoing trials and offers some insights into identifying the best sequence of new drugs.

Current Patterns of Management of Advanced Prostate Cancer in Routine Clinical Practice in Spain

Objective. To describe urologists' practice patterns when managing patients with advanced prostate cancer (PCa) in Spain. Methods. This was an observational study conducted by 120 urologists using retrospective data of advanced PCa patients attending hospitals and outpatient centers. Results. Urologists evaluated a total of 375 patients (mean age: 75 years; ECOG 0-1: 77%; mean serum PSA levels at study entry: 50.5 ng/Ml). Approximately 50% of patients had bone metastases, and 60.6% experienced pain as the main symptom of progressive disease. Primary androgen deprivation therapy (ADT) use was 99.7%, with continuous ADT as the dominant strategy (91.9%). After failure of initial ADT, antiandrogen withdrawal was the next method most commonly used in 57% of patients. Choice of secondary hormonal treatment was made mostly by urologists (96%), who continued to monitor patients. Patient follow-up after chemotherapy and supportive care were mainly done in urology units, although responsibility was shared with medical oncologists and radiologists. Conclusion. The urologists' attitudes towards management of PCa in the routine practice in Spain show the urologist as an integral component even when patients progress to advanced stages of the disease.

Diethylstilboestrol for the treatment of prostate cancer: past, present and future

The aim of this review was to discuss the most recent data from current trials of diethylstilboestrol (DES) to identify its present role in advanced prostate cancer treatment as new hormonal therapies emerge. The most relevant clinical studies using DES in castration-refractory prostate cancer (CRPC) were identified from the literature. The safety, efficacy, outcomes and mechanisms of action are summarized. In the age of chemotherapy this review highlights the efficacy of oestrogen therapy in CRPC. The optimal point in the therapeutic pathway at which DES should be prescribed remains to be established.

The hurdle of antiandrogen drug resistance: drug design strategies

INTRODUCTION

Prostate cancer is the second most common cancer death in men after lung cancer, due to distant metastases. While distant prostate cancer is typically castrate resistant, it is not necessarily androgen independent. For this reason, a review of the literature regarding the pathways involved in androgen signaling and therapeutic regimens to treat distant metastases is beneficial to increasing the survival rate of prostate cancer patients.

AREAS COVERED

In this article, the author reviews the literature from the past decade covering metastatic hormone refractory prostate cancer with the aim to examine and identify pathways, therapeutic targets and current therapies for treating castrate-resistant disease. As this area is lacking, the author aims to provide the reader with knowledge of the molecular consequences of castrate resistant prostate cancer, the current treatment paradigms and future directions.

EXPERT OPINION

While there have been advances in the treatment of castrate resistant prostate cancer, only minimal advances have been made in overall survival rate. Due to aberrant mutations and activation in the androgen receptor gene, and the complexity of cell signaling within prostate cancer, the androgen receptor should remain a main target for drug discovery efforts. This author believes that designing compounds that will reduce the activation of the androgen receptor may hold the key to a cure in the future.

The changing landscape in the treatment of metastatic castration-resistant prostate cancer

The past few years have brought increasing advances in the therapeutic management of metastatic castration-resistant prostate cancer with the approval of several agents, including vaccine therapy with sipuleucel-T, second-line chemotherapy with cabazitaxel, the bone-targeted pharmaceutical denosumab, and the novel antiandrogen therapy abiraterone acetate. There are ongoing developments with other agents in the pipeline such as MDV3100 and alpharadin that have shown promising results. This review describes the clinical trials that brought about the drug approvals of various agents and offers some insights regarding a rational approach to optimal treatment sequencing for these drugs since national guidelines are currently lacking.

Progress in emerging therapies for advanced prostate cancer

The landscape of prostate cancer treatment is rapidly changing as extensive research into potential therapies yields new options. In this article, the literature is reviewed to identify emerging therapies for advanced prostate cancer. Emphasis is placed on agents that have been approved in the United States of America (USA) and the European Union, or that have reached phase III clinical studies. Several new therapies have been approved in recent years across different stages of the natural history of the disease. Degarelix, a luteinizing hormone-releasing hormone antagonist, has been approved for reducing testosterone to castrate levels in hormone-sensitive disease. No new agents have been approved for use in combination with docetaxel chemotherapy, the current standard of care for metastatic castration-resistant prostate cancer. One immunotherapy, sipuleucel-T, has been approved (USA only) in the pre-docetaxel setting. Cabazitaxel, a next-generation taxane, and abiraterone acetate, an inhibitor of androgen biosynthesis, have both been approved as second-line agents following chemotherapy. Enzalutamide (MDV3100), an androgen receptor antagonist, has been shown to increase overall survival in the post-chemotherapy setting in metastatic disease. Denosumab, an antibody-based bone-targeted agent, has been approved for the prevention of skeletal-related events in patients with bone metastases. Radium-223 chloride, an α-emitting radiopharmaceutical, is likely to gain approval soon following promising results in a phase III trial. Clinical studies involving other promising agents are ongoing. The emergence of these therapies adds to the growing armamentarium against prostate cancer.

Chemotherapy for prostate cancer: when should a urologist refer a patient to a medical oncologist?

The last few years have seen considerable evolution in treatment options and therapeutic strategies for patients with castrate-resistant prostate cancer (CRPC). One major change was the expansion of chemotherapeutic options with the approval of cabazitaxel, representing the first chemotherapeutic therapy after docetaxel to demonstrate improved survival in patients with CRPC. A number of other noncytotoxic therapies have either recently been approved or are in advanced development for treating this patient population. Offering novel mechanisms of action, these new agents make considerably more expansive and complex the decisions regarding when to treat, which agents to use, and the order in which they are administered. A pivotal decision point for urologists who treat patients with advanced prostate cancer has been timing the patient's referral to an oncologist for chemotherapy. Although clinical guidelines regard chemotherapy as only appropriate for prostate cancer patients with symptomatic metastatic disease, increasing evidence points to the possibility that a subgroup of patients may benefit from an earlier introduction of chemotherapy. At the same time, additional treatment options that may either precede chemotherapy or follow initial chemotherapeutic failure mean that urologists must closely monitor their patients' health status to match specific clinical profiles with specific treatment options. With the increase in number and variety of therapeutic approaches, the role of the urologist has been expanded, in part, owing to the opportunity for urologists to administer treatments previously unavailable, and also owing to the growing importance of working cooperatively with oncologists and as a member of a multidisciplinary team.

Urologists and oncologists: adapting to a new treatment paradigm in castration-resistant prostate cancer (CRPC)

The treatment landscape for men with castration-resistant prostate cancer (CRPC) is undergoing significant changes; a redefinition of the respective roles of oncologists and urologists will probably occur. In addition, the advent of the multidisciplinary team or coordinated-care approach, which has been gathering momentum over the last decade, will become not simply a preference but a clear necessity. In the present review, we explore the current wave of new treatments and describe the possibility of more complex approaches to combined therapy. New treatment options include abiraterone acetate, cabazitaxel, MDV3100 (in development), radium-223 (in development) and sipuleucel-T. We also present the traditional roles of the urologist and oncologist in caring for patients with CRPC and discuss how these may change. Compounding the new potential for treatment success, as well as the complexity of therapeutic strategies, is the emergence of novel biomarkers to evaluate treatment efficacy and to assist in patient prognosis. The prospects for successful treatment of patients with CRPC have developed considerably so that these patients may soon have a reasonable expectation of therapeutic efficacy and meaningful extension of their lives.

MR-guided pulsed high intensity focused ultrasound enhancement of docetaxel combined with radiotherapy for prostate cancer treatment

The purpose of this study is to evaluate the efficacy of the enhancement of docetaxel by pulsed focused ultrasound (pFUS) in combination with radiotherapy (RT) for treatment of prostate cancer in vivo. LNCaP cells were grown in the prostates of male nude mice. When the tumors reached a designated volume by MRI, tumor bearing mice were randomly divided into seven groups (n = 5): (1) pFUS alone; (2) RT alone; (3) docetaxel alone; (4) docetaxel + pFUS; (5) docetaxel + RT; (6) docetaxel + pFUS + RT, and (7) control. MR-guided pFUS treatment was performed using a focused ultrasound treatment system (InSightec ExAblate 2000) with a 1.5T GE MR scanner. Animals were treated once with pFUS, docetaxel, RT or their combinations. Docetaxel was given by i.v. injection at 5 mg kg(-1) before pFUS. RT was given 2 Gy after pFUS. Animals were euthanized 4 weeks after treatment. Tumor volumes were measured on MRI at 1 and 4 weeks post-treatment. Results showed that triple combination therapies of docetaxel, pFUS and RT provided the most significant tumor growth inhibition among all groups, which may have potential for the treatment of prostate cancer due to an improved therapeutic ratio.

New therapies for castration-resistant prostate cancer: efficacy and safety

CONTEXT

Prostate cancer (PCa) is the most common noncutaneous malignancy and the second leading cause of cancer mortality amongst men in the Western world. Up to 40% of men diagnosed with PCa will eventually develop metastatic disease, and although most respond to initial medical or surgical castration, progression to castration resistance is universal. The average survival for patients with castration-resistant prostate cancer (CRPC) is 2-3 yr.

OBJECTIVE

To discuss the biologic rationale and evidence supporting current management of patients with CRPC and to review promising novel agents.

EVIDENCE ACQUISITION

Electronic databases (PubMed, ClinicalTrials.gov), relevant journals, and conference proceedings were searched manually for preclinical studies, clinical trials, and biomarker analyses focused on the treatment of CRPC. Keywords included castrate resistant prostate cancer and: targeted therapy, novel therapy, immunotherapy, androgen therapy, bone therapy, mechanisms, biomarkers, and trial endpoints; no time range was specified. Information pertaining to current studies was discussed with key opinion leaders.

EVIDENCE SYNTHESIS

We focus on the efficacy and safety of approved agents, promising therapies that have proceeded to phase 3 evaluation, and those that have enhanced our understanding of the biology of CRPC. Biomarkers are considered in the context of novel targeted agents and immunotherapy.

CONCLUSIONS

CRPC has many targets. Four new agents with different mechanisms of action have recently been shown to have positive results in large phase 3 randomized trials, and have already been approved in the United States for CRPC: cabazitaxel, sipuleucel-T, denosumab, and abiraterone acetate. With our improved understanding of tumor biology and the incorporation of new prognostic and molecular biomarkers into clinical trials, we are making progress in the management of patients with CRPC.

Second-line chemotherapy in metastatic docetaxel-resistant prostate cancer: a review

The results of cytotoxic therapy in the second-line setting of metastatic castration-resistant prostate cancer have demonstrated that disease is poorly controlled after taxane resistance with a time to progression of 3 months or less. Many trials of second-line chemotherapy have been disappointing. However, most of patients with docetaxel-pretreated castration-resistant disease receive a second-line chemotherapy. Molecular mechanism of castration resistance and docetaxel resistance is resumed, and clinical trials of second-line chemotherapy after docetaxel progression are reviewed. Reintroduction of docetaxel after a drug-free interval is an active treatment in docetaxel-pretreated patients, and only recently a prospective study documented a survival benefit of 2.4 months after second-line taxane-based chemotherapy of metastatic docetaxel-resistant prostate cancer. Although a second-line chemotherapy with a taxane could improve overall survival, a change of biology of castration-resistant prostate cancer after docetaxel is suggested, as inferred by the renewed hormonal sensitivity, whose role on survival remains unknown, and from the activity of antiangiogenic drugs.