Flutamide versus prednisone in patients with prostate cancer symptomatically progressing after androgen-ablative therapy: a phase III study of the European organization for research and treatment of cancer genitourinary group

Optimized Synthesis of Poly(Lactic Acid) Nanoparticles for the Encapsulation of Flutamide

Biopolymeric nanoparticles (NPs) have gained significant attention in several areas as an alternative to synthetic polymeric NPs due to growing environmental and immunological concerns. Among the most promising biopolymers is poly(lactic acid) (PLA), with a reported high degree of biocompatibility and biodegradability. In this work, PLA NPs were synthesized according to a controlled gelation process using a combination of single-emulsion and nanoprecipitation methods. This study evaluated the influence of several experimental parameters for accurate control of the PLA NPs' size distribution and aggregation. Tip sonication (as the stirring method), a PLA concentration of 10 mg/mL, a PVA concentration of 2.5 mg/mL, and low-molecular-weight PLA (Mw = 5000) were established as the best experimental conditions to obtain monodisperse PLA NPs. After gelification process optimization, flutamide (FLU) was used as a model drug to evaluate the encapsulation capability of the PLA NPs. The results showed an encapsulation efficiency of 44% for this cytostatic compound. Furthermore, preliminary cell viability tests showed that the FLU@PLA NPs allowed cell viabilities above 90% up to a concentration of 20 mg/L. The comprehensive findings showcase that the PLA NPs fabricated using this straightforward gelification method hold promise for encapsulating cytostatic compounds, offering a novel avenue for precise drug delivery in cancer therapy.

Corticosteroids for the management of cancer-related fatigue in adults with advanced cancer

BACKGROUND

Fatigue is the most commonly reported symptom in people with advanced cancer. Cancer-related fatigue (CRF) is pervasive and debilitating, and can greatly impact quality of life (QoL). CRF has a highly variable clinical presentation, likely due to a complex interaction of multiple factors. Corticosteroids are commonly used to improve CRF, but the benefits are unclear and there are significant adverse effects associated with long-term use. With the increasing survival of people with metastatic cancer, the long-term effects of medications are becoming increasingly relevant. Since the impact of CRF can be immensely debilitating and can negatively affect QoL, its treatment warrants further review.

OBJECTIVES

To determine the benefits and harms of corticosteroids compared with placebo or an active comparator in adults with advanced cancer and CRF.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, Science Citation Index (ISI Web of Science), LILACS, and two clinical trial registries from inception to 18 July 2022.  SELECTION CRITERIA: We included randomised controlled trials in adults aged ≥18 years. We included participants with advanced cancer who were suffering from CRF. We included trials that randomised participants to corticosteroids at any dose, by any route, administered for the relief of CRF; compared to placebo or an active comparator, including supportive care or non-pharmacological treatments.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed titles identified by the search strategy; two review authors assessed risk of bias; and two extracted data. We extracted the primary outcome of participant-reported fatigue relief using validated scales and secondary outcomes of adverse events, serious adverse events and QoL. We calculated the risk ratio with 95% confidence intervals (CIs) between groups for dichotomous outcomes. We measured arithmetic mean and standard deviation, and reported the mean difference (MD) with 95% CI between groups for continuous outcomes. We used standardised mean difference (SMD) with 95% CIs when an outcome was measured with different instruments measuring the same construct. We used a random-effects model to meta-analyse the outcome data. We rated the certainty of the evidence using GRADE and created two summary of findings tables.  MAIN RESULTS: We included four studies with 297 enroled participants; data were available for only 239 participants. Three studies compared corticosteroid (equivalent ≤ 8 mg dexamethasone) to placebo. One study compared corticosteroid (dexamethasone 4 mg) to an active comparator (modafinil 100 mg). There were insufficient data to evaluate subgroups, such as dose and duration of treatment. One study had a high risk of performance and detection bias due to lack of blinding, and one study had a high risk of attrition bias. Otherwise, we assessed risks of bias as low or unclear. Comparison 1: corticosteroids compared with placebo Participant-reported fatigue relief The was no clear difference between corticosteroids and placebo (SMD -0.46, 95% CI -1.07 to 0.14; 3 RCTs, 165 participants, very low-certainty evidence) for relief of fatigue at one week of the intervention. We downgraded the certainty of the evidence three times for study limitations due to unclear risk of bias, imprecision, and inconsistency. Adverse events There was no clear difference in the occurrence of adverse events between groups, but the evidence is very uncertain (3 RCTs, 165 participants; very low-certainty evidence). Serious adverse events There was no clear difference in the occurrence of serious adverse events between groups, but the evidence is very uncertain (2 RCTs, 118 participants; very low-certainty evidence). Quality of lIfe One study reported QoL at one week using the Edmonton Symptom Assessment System (ESAS) well-being, and found no clear difference in QoL between groups (MD -0.58, 95% CI -1.93 to 0.77). Another study measured QoL using the Quality of Life Questionnaire for Cancer Patients Treated with Anticancer Drugs (QoL-ACD), and found no clear difference between groups. There was no clear difference between groups for either study, but the evidence is very uncertain (2 RCTs, 118 participants; very low-certainty evidence).  Comparison 2: corticosteroids compared with active comparator (modafinil) Participant-reported fatigue relief There was improvement in fatigue from baseline to two weeks in both groups (modafinil MD 10.15, 95% CI 7.43 to 12.87; dexamethasone MD 9.21, 95% CI 6.73 to 11.69), however no clear difference between the two groups (MD -0.94, 95% CI -4.49 to 2.61; 1 RCT, 73 participants, very low-certainty evidence). We downgraded the certainty of the evidence three times for very serious study limitations and imprecision. Adverse events There was no clear difference in the occurrence of adverse events between groups, but the evidence is very uncertain (1 RCT, 73 participants; very low-certainty evidence).  Serious adverse events There were no serious adverse events reported in either group (1 RCT, 73 participants; very low-certainty evidence).  Quality of lIfe One study measured QoL at two weeks, using the ESAS-well-being. There was marked improvement in QoL from baseline in both groups (modafinil MD -2.43, 95% CI -2.88 to -1.98; dexamethasone MD -2.16, 95% CI -2.68 to -1.64), however no clear difference between the two groups (MD 0.27, 95% CI -0.39 to 0.93; 1 RCT, 73 participants, very low-certainty evidence).

AUTHORS' CONCLUSIONS

There is insufficient evidence to support or refute the use of systemic corticosteroids in adults with cancer and CRF. We included four small studies that provided very low-certainty of evidence for the efficacy of corticosteroids in the management of CRF. Further high-quality randomised controlled trials with larger sample sizes are required to determine the effectiveness of corticosteroids in this setting.

Targeting signaling pathways in prostate cancer: mechanisms and clinical trials

Prostate cancer (PCa) affects millions of men globally. Due to advances in understanding genomic landscapes and biological functions, the treatment of PCa continues to improve. Recently, various new classes of agents, which include next-generation androgen receptor (AR) signaling inhibitors (abiraterone, enzalutamide, apalutamide, and darolutamide), bone-targeting agents (radium-223 chloride, zoledronic acid), and poly(ADP-ribose) polymerase (PARP) inhibitors (olaparib, rucaparib, and talazoparib) have been developed to treat PCa. Agents targeting other signaling pathways, including cyclin-dependent kinase (CDK)4/6, Ak strain transforming (AKT), wingless-type protein (WNT), and epigenetic marks, have successively entered clinical trials. Furthermore, prostate-specific membrane antigen (PSMA) targeting agents such as ¹⁷⁷Lu-PSMA-617 are promising theranostics that could improve both diagnostic accuracy and therapeutic efficacy. Advanced clinical studies with immune checkpoint inhibitors (ICIs) have shown limited benefits in PCa, whereas subgroups of PCa with mismatch repair (MMR) or CDK12 inactivation may benefit from ICIs treatment. In this review, we summarized the targeted agents of PCa in clinical trials and their underlying mechanisms, and further discussed their limitations and future directions.

Revision of Pharmacological Treatment Recommendations for Cancer Pain: Clinical Guidelines from the Japanese Society of Palliative Medicine

Background: Pain is one of the most common symptoms in cancer patients. The Japanese Society for Palliative Medicine (JSPM) first published its clinical guidelines for the management of cancer pain in 2010. Since then, more research on cancer pain management has been reported, and new drugs have become available in Japan. Thus, the JSPM has now revised the clinical guidelines using a validated methodology. Methods: This guideline was developed through a systematic review, discussion, and the Delphi method, following a formal guideline development process. Results: Thirty-five recommendations were created: 19 for the pharmacological management of cancer pain, 6 for the management of opioid-induced adverse effects, and 10 for pharmacological treatment procedures. Due to the lack of evidence that directly addressed our clinical questions, most of the recommendations had to be based on consensus among committee members and other guidelines. Discussion: It is critical to continue to build high-quality evidence in cancer pain management, and revise these guidelines accordingly.

An exploratory first-in-man study to investigate the pharmacokinetics and safety of liposomal dexamethasone at a 2- and 1-week interval in patients with metastatic castration resistant prostate cancer

Dexamethasone has antitumor activity in metastatic castration resistant prostate cancer (mCRPC). We aimed to investigate intravenous liposome-encapsulated dexamethasone disodium phosphate (liposomal dexamethasone) administration in mCRPC patients. In this exploratory first-in-man study, patients in part A received a starting dose of 10 mg followed by five doses of 20 mg liposomal dexamethasone at 2-week intervals. Upon review of part A safety, patients in part B received 10 weekly doses of 18.5 mg. Primary outcomes were safety and pharmacokinetic profile, secondary outcome was antitumor efficacy. Nine mCRPC patients (5 part A, 4 part B) were enrolled. All patients experienced grade 1-2 toxicity, one (part B) patient experienced grade 3 toxicity (permanent bladder catheter-related urosepsis). No infusion-related adverse events occurred. One patient had upsloping glucose levels ≤9.1 mmol/L. Trough plasma concentrations of liposomal- and free dexamethasone were below the lower limit of quantification (LLOQ) in part A, and above LLOQ in three patients in part B (t1/2 ~50 h for liposomal dexamethasone), trough concentrations of liposomal- and free dexamethasone increased toward the end of the study. In seven of nine patients (78%) patients, stable disease was observed in bone and/or CT scans at follow-up, and in one (part B) of these seven patients a >50% PSA biochemical response was observed. Bi- and once weekly administrations of IV liposomal dexamethasone were well-tolerated. Weekly dosing enabled trough concentrations of liposomal- and free dexamethasone >LLOQ. The data presented support further clinical investigation in well-powered studies. Clinical trial registration: ISRCTN 10011715.

Quality of life in men with metastatic castration-resistant prostate cancer treated with enzalutamide or abiraterone: a systematic review and meta-analysis

BACKGROUND

Enzalutamide and abiraterone acetate plus prednisone (AAP) have similar efficacy in metastatic castration-resistant prostate cancer (mCRPC), but different mechanisms of action. The aim was to compare patient-reported health-related quality of life (HRQoL) in men treated with enzalutamide vs AAP for mCRPC.

METHODS

We systematically reviewed the literature in June 2020 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations. Patient-reported outcomes (PROs) until the last follow-up were summarised in a narrative synthesis. Short-term changes (12 weeks) in HRQoL, measured by the Functional Assessment of Cancer Therapy-Prostate total score (FACT-P), were compared between treatment groups and were analysed for enzalutamide and AAP in separate meta-analyses. Higher FACT-P scores indicate better HRQoL.

RESULTS

Eight studies were included in the systematic review, four of which were randomised clinical trials (RCTs) eligible for the meta-analyses. The meta-analyses showed mean within-subject FACT-P changes from baseline to week 12 of -1.3 points (95% confidence interval [CI] -2.7; 0.1) for enzalutamide and 4.7 points (95% CI -0.1; 9.6) for AAP. One RCT and three non-randomised studies directly compared enzalutamide with AAP. The RCT showed better short-term HRQoL for AAP (6.8 FACT-P-points, 95% CI 1.7; 11.8) and better long-term HRQoL for AAP in men ≥75 years (7.35 FACT-P-points, 95% CI 2.59; 12.11). The non-randomised studies showed no difference in long-term HRQoL but had all a serious risk of bias. Limitations of the included studies include that the PRO in the included trials were inconsistently reported and that only one study defined the HRQoL measures in their published protocol.

CONCLUSIONS

AAP seems to be associated with better short-term HRQoL than enzalutamide. This difference was not apparent at longer follow-up, but the long-term studies had serious risks of bias.

Inter- and intra-patient variability in pharmacokinetics of abiraterone acetate in metastatic prostate cancer

PURPOSE

This study examined the inter- and intra-patient variability in pharmacokinetics of AA and its metabolites abiraterone and Δ(4)-abiraterone (D4A), and potential contributing factors.

METHODS

AA administered daily for ≥4 weeks concurrently with androgen deprivation therapy (ADT) for mCRPC were included. Pharmacokinetic evaluation was performed at two consecutive visits at least 4 weeks apart. Plasma samples were collected 24 h after last dose of AA to obtain drug trough level (DTL) of two active metabolites, abiraterone and D4A.

RESULTS

39 plasma samples were obtained from 22 patients, with 17 patients had repeat DTL measurement. Considerable inter-patient variability in DTL was seen, with initial DTL for abiraterone ranging between 1.5 and 25.4 ng/ml (CV 61%) and for D4A between 0.2 and 2.5 ng/ml (CV 61%). Intra-patient variability in DTL for abiraterone varied between 0.85 and 336% and for D4A between 1.14 and 199%. There was no increase in AA exposure with use of dexamethasone (n = 5; DTL 13.9) compared with prednisone (n = 17; DTL 11.0 p = 0.5), dosing in fasted state (n = 13, DTL 12.1) compared to dosing in fed state (n = 9; DTL 11.1, p = 0.8), or chemotherapy-exposed (n = 10; DTL 8.9) compared to chemotherapy naïve (n = 12; DTL 14.0, p = 0.1).

CONCLUSIONS

Our cohort demonstrated high inter- and intra-patient variability in both abiraterone and D4A with fixed dosing of AA, with no effect from choice of corticosteroids, prior use of chemotherapy, or dosing in fasting state. Monitoring DTL of AA may be necessary to minimise risk of patients being under-dosed and earlier development of resistance.

Molecular underpinnings of enzalutamide resistance

Prostate cancer (PCa) is among the most common adult malignancies, and the second leading cause of cancer-related death in men. As PCa is hormone dependent, blockade of the androgen receptor (AR) signaling is an effective therapeutic strategy for men with advanced metastatic disease. The discovery of enzalutamide, a compound that effectively blocks the AR axis and its clinical application has led to a significant improvement in survival time. However, the effect of enzalutamide is not permanent, and resistance to treatment ultimately leads to development of lethal disease, for which there currently is no cure. This review will focus on the molecular underpinnings of enzalutamide resistance, bridging the gap between the preclinical and clinical research on novel therapeutic strategies for combating this lethal stage of prostate cancer.

Effectiveness of Deferred Combined Androgen Blockade Therapy Predicts Efficacy in Abiraterone Acetate Treated Metastatic Castration-Resistant Prostate Cancer Patients after Docetaxel

Introduction: Conventional anti-androgen regimens were widely used as an initiation or combined androgen blockade (CAB) therapy in advanced prostate cancer patients. Currently, new androgen pathway inhibitors such as abiraterone acetate (AA) and enzalutamide had been proven effective in metastatic castration resistant prostate cancer. In this study, we attempt to analyze the role of conventional anti-androgen drugs as deferred CAB therapy in castration-resistant prostate cancer patients.

Materials and Methods: From 2012 to 2017, 48 metastatic castration-resistant prostate cancer (CRPC) patients who received sequential treatments with primary androgen blockade, oral anti-androgen regimens, and docetaxel followed by AA treatment were included. We defined effective deferred CAB as any decline of PSA after add-on antiandrogen after CRPC. Patients were separated into effective and ineffective deferred CAB. Comparison between two groups in the first line androgen deprivation therapy duration, CRPC PSA level, pre-AA PSA level, chemotherapy dosages, duration, and patients progression free survival and overall survival after AA treatment were analyzed.

Results: Twenty-three patients (47.9%) achieved PSA decline after deferred CAB. Among total 48 patients, 24 patients experienced PSA decline more than 50% after AA treatment. The median PSA progression-free survival and overall survival after AA treatment in the total cohort of 48 patients were 4.4 and 24.3 months, respectively. The effective deferred CAB group showed significantly lower PSA level, lower percentage of PSA progression, higher total follow-up duration, higher percentage of surviving patients, better progression free survival, and overall survival estimate after AA treatment. Of the eight variables analyzed, effectiveness in deferred CAB showed positive association to progression free survival (HR 0.29, 95% CI 0.12–0.67, p = 0.004) and overall survival (HR 0.24, 95% CI 0.07–0.81, p = 0.022). First line androgen deprivation therapy (ADT) duration also showed positive association to overall survival (HR 0.95, 95% CI 0.91–0.99, p = 0.023).

Conclusions: Effectiveness of deferred CAB therapy was positively associated with progression free survival and overall survival of AA treatment after docetaxel. It can be used as a pre-treatment predictor.

Second-Line Hormonal Therapy for Men With Chemotherapy-Naïve, Castration-Resistant Prostate Cancer: American Society of Clinical Oncology Provisional Clinical Opinion

Purpose ASCO provisional clinical opinions (PCOs) offer direction to the ASCO membership after publication or presentation of potential practice-changing data. This PCO addresses second-line hormonal therapy for chemotherapy-naïve men with castration-resistant prostate cancer (CRPC) who range from being asymptomatic with only biochemical evidence of CRPC to having documented metastases but minimal symptoms. Clinical Context The treatment goal for CRPC is palliation. Despite resistance to initial androgen deprivation therapy, most men respond to second-line hormonal therapies. However, guidelines have neither addressed second-line hormonal therapy for nonmetastatic CRPC nor provided specific guidance with regard to the chemotherapy-naïve population. Recent Data Six phase III randomized controlled trials and expert consensus opinion inform this PCO. Provisional Clinical Opinion For men with CRPC, a castrate state should be maintained indefinitely. Second-line hormonal therapy (eg, antiandrogens, CYP17 inhibitors) may be considered in patients with nonmetastatic CRPC at high risk for metastatic disease (rapid prostate-specific antigen doubling time or velocity) but otherwise is not suggested. In patients with radiographic evidence of metastases and minimal symptoms, enzalutamide or abiraterone plus prednisone should be offered after discussion with patients about potential harms, benefits, costs, and patient preferences. Radium-223 and sipuleucel-T also are options. No evidence provides guidance about the optimal order of hormonal therapies for CRPC beyond second-line treatment. Prostate-specific antigen testing every 4 to 6 months is reasonable for men without metastases. Routine radiographic restaging generally is not suggested but can be considered for patients at risk for metastases or who exhibit symptoms or other evidence of progression. Additional information is available at www.asco.org/genitourinary-cancer-guidelines and www.asco.org/guidelineswiki .

The role of glucocorticoid receptor in prostate cancer progression: from bench to bedside

Glucocorticoids are a common class of adjuvant drugs for the treatment of castration-resistant prostate cancer (CRPC) combined with antitumour or antiandrogen agents. Glucocorticoids are administered clinically because they ameliorate toxic side effects and have inhibitory effects on adrenal androgen production, acting as a pituitary suppressant. However, their effects on prostate cancer cells especially the castration resistance prostate cancer cells are poorly defined. Glucocorticoids exert effects depend to a great extent on glucocorticoid receptor. In addition to a number of glucocorticoid receptor isoforms determined, it is found that the actions of glucocorticoids through GRα are influenced by other isoforms, such as GRβ and GRγ. Recently, studies found GR confers resistance to androgen deprivation therapy, and various glucocorticoids exert distinct efficacy in CRPC. In this review, we summarized the mechanisms of glucocorticoids and its clinical appliances on the basis of present evidence.

A phase 2 clinical trial of everolimus plus bicalutamide for castration-resistant prostate cancer

BACKGROUND

The mammalian target of rapamycin (mTOR) pathway is up-regulated in castration-resistant prostate cancer (CRPC). Nevertheless, inhibition of mTOR is ineffective in inducing apoptosis in prostate cancer cells, likely because of the compensatory up-regulation of the androgen receptor (AR) pathway.

METHODS

Patients who were eligible for this study had to have progressive CRPC with serum testosterone levels <50 ng/dL. No prior bicalutamide (except to prevent flare) or everolimus was allowed. Treatment included oral bicalutamide 50 mg and oral everolimus 10 mg, both once daily, with a cycle defined as 4 weeks. The primary endpoint was the prostate-specific antigen (PSA) response (≥30% reduction) from baseline. A sample size of 23 patients would have power of 0.8 and an α error of .05 (1-sided) if the combination had a PSA response rate of 50% versus a historic rate of 25% with bicalutamide alone.

RESULTS

Twenty-four patients were enrolled. The mean age was 71.1 years (range, 53.0-87.0 years), the mean PSA level at study entry was 43.4 ng/dL (range, 2.5-556.9 ng/dL), and the mean length of treatment was 8 cycles (range, 1.0-23.0 cycles). Of 24 patients, 18 had a PSA response (75%; 95% confidence interval [CI], 0.53-0.90), whereas 15 (62.5%; 95% CI, 0.41-0.81) had a PSA decrease ≥50%. The median overall survival was 28 months (95% CI, 14.1-42.7 months). Fourteen patients (54%; 95% CI, 0.37-0.78) developed grade 3 (13 patients) or grade 4 (1 patient with sepsis) adverse events that were attributable to treatment.

CONCLUSIONS

The combination of bicalutamide and everolimus has encouraging efficacy in men with bicalutamide-naive CRPC, thus warranting further investigation. A substantial number of patients experienced everolimus-related toxicity. Cancer 2016;122:1897-904. © 2016 American Cancer Society.

Mechanisms of resistance in castration-resistant prostate cancer (CRPC)

Despite advances in prostate cancer diagnosis and management, morbidity from prostate cancer remains high. Approximately 20% of men present with advanced or metastatic disease, while 29,000 men continue to die of prostate cancer each year. Androgen deprivation therapy (ADT) has been the standard of care for initial management of advanced or metastatic prostate cancer since Huggins and Hodges first introduced the concept of androgen-dependence in 1972, but progression to castration-resistant prostate cancer (CRPC) occurs within 2-3 years of initiation of ADT. CRPC, previously defined as hormone-refractory prostate cancer, is now understood to still be androgen dependent. Multiple mechanisms of resistance help contribute to the progression to castration resistant disease, and the androgen receptor (AR) remains an important driver in this progression. These mechanisms include AR amplification and hypersensitivity, AR mutations leading to promiscuity, mutations in coactivators/corepressors, androgen-independent AR activation, and intratumoral and alternative androgen production. More recently, identification of AR variants (ARVs) has been established as another mechanism of progression to CRPC. Docetaxel chemotherapy has historically been the first-line treatment for CRPC, but in recent years, newer agents have been introduced that target some of these mechanisms of resistance, thereby providing additional survival benefit. These include AR signaling inhibitors such as enzalutamide (Xtandi, ENZA, MDV-3100) and CYP17A1 inhibitors such as abiraterone acetate (Zytiga). Ultimately, these agents will also fail to suppress CRPC. While some of the mechanisms by which these agents fail are unique, many share similarities to the mechanisms contributing to CRPC progression. Understanding these mechanisms of resistance to ADT and currently approved CRPC treatments will help guide future research into targeted therapies.

Androgen-glucocorticoid interactions in the era of novel prostate cancer therapy

Great strides have been made in the treatment of castration-resistant prostate cancer (CRPC) with the development of new antiandrogens (enzalutamide) and more potent androgen synthesis inhibitors (abiraterone) that have both improved patient outcomes. These new drugs have also helped unravel the complex biology of androgen-androgen receptor driven prostate cancer and brought into prominence various mechanisms triggering the development of drug resistance and tumour cell survival despite use of androgen deprivation therapy (ADT). The complex role of glucocorticoids in the treatment, management and progression of patients with CRPC is integral to these advances. Historically, glucocorticoid treatment has resulted in both subjective and objective responses in patients with advanced-stage prostate cancer. With the use of these new therapeutic agents, however, unexpected glucocorticoid-related mechanisms that can cause iatrogenic stimulation of prostate cancer growth have emerged, which might contribute to drug resistance and disease progression despite optimal ADT. For example, the upregulation of glucocorticoid receptors (GRs) during enzalutamide therapy results in glucocorticoid-GR-mediated regulation of androgen target genes, leading to escape from enzalutamide blockade. Thus, understanding the biological role of glucocorticoids in patients with prostate cancer is of major importance in the era of new and evolving antiandrogen therapies.

Advances in the Treatment of Metastatic Prostate Cancer

During the past several years, there has been substantial progress in the development of treatments for advanced prostate cancer with the approval of multiple new life-prolonging agents using different mechanisms of action. Such progress was attainable because of advances in our understanding of the biology behind mechanisms of androgen receptor pathway activation, complex tumor-microenvironment interaction of bone metastasis, antitumor immunology, and new oncogenic pathways. Continuous efforts are being made to develop new therapeutics with novel mechanisms of action, define the optimal sequences and/or combinations of current agents, and identify reliable surrogate end points to facilitate new drug development.

Corticosteroids in the management of prostate cancer: a critical review

Corticosteroids have been used in the management of prostate cancer for over 30 years. Although daily oral corticosteroids have frequently used in conjunction with chemotherapy for metastatic castration-resistant prostate cancer, their independent impact on survival is unclear. However, corticosteroids confer palliative benefits and are associated with objective responses and circulating tumor cell (CTC) and PSA declines in a small minority of patients, although toxicities such as osteoporosis and immunosuppression complicate long-term use. Following the demonstration of a palliative benefit for mitoxantrone combined with corticosteroids compared with corticosteroids alone, subsequent trials that demonstrated a benefit for first-line docetaxel over mitoxantrone, and second-line cabazitaxel over mitoxantrone, administered concurrent daily oral corticosteroids with all of these agents to maintain uniformity. Conversely, improved outcomes were demonstrated with docetaxel without corticosteroids for metastatic castration-sensitive prostate cancer. Daily oral corticosteroids are routinely combined with abiraterone to mitigate symptoms of mineralocorticoid excess. In contrast daily corticosteroids are not essential when administering enzalutamide or radium-223, and there is a concern of deleterious immune effects concurrently with sipuleucel-T. Given emerging evidence for promotion of resistance mechanisms, routine administration of daily oral corticosteroids in settings other than abiraterone administration and palliation of symptoms is probably not required.

Assessment of anticancer-treatment outcome in patients with metastatic castration-resistant prostate cancer-going beyond PSA and imaging, a systematic literature review

BACKGROUND

In the past years, there has been significant progress in anticancer drug development for patients with metastatic castration-resistant prostate cancer (CRPC). However, the current instruments to assess clinical treatment response have limitations and may not sufficiently reflect patient benefit. Our objective was to systematically identify tools to evaluate both patient benefit and clinical anticancer-treatment response as basis for an international consensus process and development of a specific pragmatic instrument for men with CRPC.

METHODS

PubMed, Embase and CINAHL were searched to identify currently available tools to assess anticancer-treatment benefit, other than standard imaging procedures and prostate-specific antigen measurements, namely quality of life (QoL), detailed pain assessment, physical function and objective measures of other complex cancer-related syndromes in patients with CRPC. Additionally, all CRPC phase III trials published in the last 5 years were reviewed as well as studies using physical function tools in a general cancer population. The PRIMSA statement was followed for the systematic review process.

RESULTS

The search generated 1096 hits, 185 full-text papers were screened and finally 73 publications were included. Additional 89 publications were included by hand-search. We identified a total of 98 tools used in CRPC trials and grouped these into three categories: 22 tools assessing QoL domains and subgroups, 47 tools for pain assessment and 29 tools for objective measures, mainly physical function and assessment of skeletal disease burden.

CONCLUSION

A wide variety of assessment tools and also efforts to standardize and harmonize patient-reported outcomes and pain assessment were identified. However, the specific needs of the increasing CRPC population living longer with their incurable cancer are insufficiently captured and objective physical outcome measures are under-represented. In the age of new anticancer drug targets and principles, new methods to monitor patient relevant outcomes of antineoplastic therapy are of utmost importance.

Corticosteroids for the management of cancer-related pain in adults

BACKGROUND

One of the most feared symptoms associated with cancer is pain. Opioids remain the mainstay of pain treatment but corticosteroids are often used concurrently as co- or adjuvant analgesics. Due to their anti-inflammatory mechanism of action, corticosteroids are said to provide effective analgesia for pain associated with inflammation and in the management of cancer-related complications such as brain metastasis and spinal cord compression. However, corticosteroids have a wide range of adverse effects that are dose and time dependent.

OBJECTIVES

To evaluate the efficacy of corticosteroids in treating cancer-related pain in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2014, Issue 4), MEDLINE (OVID) (1966 to 29 September 2014), EMBASE (OVID) (1970 to 29 September 2014), CINAHL (1982 to 29 September 2014), Science Citation Index (Web of Science) (1899 to 29 September 2014) and Conference Proceedings Citation Index - Science (Web of Science) (1990 to 29 September 2014).

SELECTION CRITERIA

Any randomised or prospective controlled trial that included patients over 18 years with cancer-related pain were eligible for the review. Corticosteroids were compared to placebo or usual treatment and/or supportive care.

DATA COLLECTION AND ANALYSIS

All review authors independently assessed trial quality and extracted data. We used arithmetic means and standard deviations for each outcome to report the mean difference (MD) with 95% confidence interval (CI).

MAIN RESULTS

Fifteen studies met the inclusion criteria, enrolling 1926 participants. The trial size varied from 20 to 598 patients. Most studies compared corticosteroids, particularly dexamethasone, to standard therapy. We included six studies with data at one week in the meta-analysis for pain intensity; no data were available at that time point for the remaining studies. Corticosteroid therapy resulted in less pain (measured on a scale of 0 to 10 with a lower score indicating less pain) compared to control at one week (MD 0.84 lower pain, 95% CI 1.38 to 0.30 lower; low quality evidence). Adverse events were poorly documented. Factors limiting statistical analysis included the lack of standardised measurements of pain and the use of different agents, dosages, comparisons and routes of drug delivery. Subgroup analysis according to type of cancer was not possible. The quality of this evidence was limited by the risk of bias of the studies and small sample size. The results were also compromised by attrition, with data missing for the enrolled patients.

AUTHORS' CONCLUSIONS

The evidence for the efficacy of corticosteroids for pain control in cancer patients is weak. Significant pain relief was noted in some studies, albeit only for a short period of time. This could be important for patients with poor clinical status. Further trials, with increased numbers of participants, are needed to evaluate the safety and effectiveness of corticosteroids for the management cancer pain in adults, and to establish an ideal dose, duration of therapy and route of administration.

Randomized phase II study of nintedanib in metastatic castration-resistant prostate cancer postdocetaxel

This open-label, phase II trial assessed the efficacy and safety of two doses of nintedanib, a triple angiokinase inhibitor targeting vascular endothelial growth factor, fibroblast growth factor, and platelet-derived growth factor signaling, in patients with metastatic castration-resistant prostate cancer (mCRPC) following progression on docetaxel-based regimens. Patients were randomized to nintedanib 150 mg (arm A, n=40) or 250 mg (arm B, n=41) twice daily for 6 months unless disease progression or adverse events (AEs) led to discontinuation. The primary endpoint was the prostate-specific antigen (PSA) response rate (confirmed PSA decline of ≥20% from baseline). Eighty-one patients were enrolled. The PSA response rate was 0% (0/32) in arm A versus 11.1% (4/36) in arm B (P=0.12); 5.6% of patients (2/36) in arm B showed a PSA reduction of at least 50%. In arm B, the rate of PSA increase was significantly decelerated on treatment versus before treatment (P=0.002). The median progression-free survival was 73.5 and 76.0 days for arm A and arm B, respectively (P=0.3). AEs included gastrointestinal disorders, asthenia, hypertension, and reversible elevated transaminases. The incidence of drug-related serious AEs (no drug-related deaths) was 20.0% (arm A) and 24.4% (arm B). The primary endpoint was not met. Nintedanib (250 mg) showed only modest activity with manageable AEs in patients with mCRPC post-docetaxel.

A randomised phase 2 trial of dexamethasone versus prednisolone in castration-resistant prostate cancer

BACKGROUND

Prednisolone is widely used as secondary hormonal treatment for castration-resistant prostate cancer (CRPC). We hypothesised that dexamethasone, another corticosteroid, is more active.

OBJECTIVE

To compare the activity of prednisolone and dexamethasone in CRPC.

DESIGN, SETTING, AND PARTICIPANTS

This single-centre, randomised, phase 2 trial was performed in 82 men with chemotherapy-naïve CRPC enrolled from 2006 to 2010.

INTERVENTION

Prednisolone 5mg twice daily versus dexamethasone 0.5mg once daily versus intermittent dexamethasone 8mg twice daily on days 1-3 every 3 wk.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The main end point was prostate-specific antigen (PSA) response rate. Secondary end points included time to PSA progression, radiologic response rate using Response Evaluation Criteria In Solid Tumors (RECIST), and safety.

RESULTS AND LIMITATIONS

The intermittent dexamethasone arm was dropped after no response was seen in seven patients. By intention to treat, confirmed PSA response was seen in 41% versus 22% for daily dexamethasone versus prednisolone, respectively (p=0.08). In evaluable patients, the PSA response rates were 47% versus 24% for dexamethasone and prednisolone, respectively (p=0.05). Median time to PSA progression was 9.7 mo on dexamethasone versus 5.1 mo on prednisolone (hazard ratio: 1.6; 95% confidence interval, 0.9-2.8). In 43 patients with measurable disease, the response rate by RECIST was 15% and 6% for dexamethasone and prednisolone, respectively (p=0.6). Of 23 patients who crossed over at PSA progression on prednisolone, 7 of the 19 evaluable (37%) had a confirmed PSA response to dexamethasone. Clinically significant toxicities were rare.

CONCLUSIONS

Dexamethasone may be more active than prednisolone in CRPC. In the absence of more definitive trials, dexamethasone should be used in preference to prednisolone.

PATIENT SUMMARY

We compared two different steroids used for treating men with advanced prostate cancer. Our results suggest that dexamethasone may be more effective than prednisolone and that both are well tolerated.

CLINICAL TRIAL REGISTRY

EUDRAC 2005-006018-16.

Circulating tumor cells in patients with metastatic castration resistant prostate cancer: exploratory findings at a tertiary referral hospital

Objectives

In patients with metastatic castration-resistant prostate cancer (mCRPC), the finding of less than five circulating tumor cells (CTCs)/7.5 mL blood before start of cytotoxic treatment or shortly thereafter indicates prolonged survival. In this descriptive pilot study, we investigated whether this association depends on the sequence of the therapeutic attempts.

Patients and methods

CTCs were determined in 41 mCRPC patients before and 2–3 months after starting first-line treatment with docetaxel (group 1) or second-line treatment with either radium-223 (group 2) or placebo/best supportive care (group 3). A “favorable” CTC count was defined as <5 CTC/7.5 mL blood. The results were related to overall survival.

Results

Pretreatment, six of ten men in group 1, three of 19 in group 2, and three of 12 patients in group 3 had a favorable CTC count, leading to a significant difference between first- and second-line therapy (P=0.04). Decrease of pretreatment elevated CTCs to a favorable CTC count was significantly more often observed in patients on first-line therapy (three of four patients) than on second-line treatment (two of 26 men) (P=0.03). A favorable CTC count before or shortly after treatment start was observed in nine of ten patients on first-line and in eight of 31 men on second-line therapy (P=0.01). A favorable CTC count pretreatment or 2–3 months after therapy start was associated with beneficial overall survival in the three groups combined and in each group analyzed separately.

Conclusion

In mCRPC, a favorable CTC count before or 2–3 months after start of therapy is associated with length of overall survival, though such favorable CTC counts are observed significantly less often in patients on second- than on first-line therapy.

Systemic therapy in men with metastatic castration-resistant prostate cancer:American Society of Clinical Oncology and Cancer Care Ontario clinical practice guideline

PURPOSE

To provide treatment recommendations for men with metastatic castration-resistant prostate cancer (CRPC).

METHODS

The American Society of Clinical Oncology and Cancer Care Ontario convened an expert panel to develop evidence-based recommendations informed by a systematic review of the literature.

RESULTS

When added to androgen deprivation, therapies demonstrating improved survival, improved quality of life (QOL), and favorable benefit-harm balance include abiraterone acetate/prednisone, enzalutamide, and radium-223 ((223)Ra; for men with predominantly bone metastases). Improved survival and QOL with moderate toxicity risk are associated with docetaxel/prednisone. For asymptomatic/minimally symptomatic men, improved survival with unclear QOL impact and low toxicity are associated with sipuleucel-T. For men who previously received docetaxel, improved survival, unclear QOL impact, and moderate to high toxicity risk are associated with cabazitaxel/prednisone. Modest QOL benefit (without survival benefit) and high toxicity risk are associated with mitoxantrone/prednisone after docetaxel. No benefit and excess toxicity are observed with bevacizumab, estramustine, and sunitinib.

RECOMMENDATIONS

Continue androgen deprivation (pharmaceutical or surgical) indefinitely. Abiraterone acetate/prednisone, enzalutamide, or (223)Ra should be offered; docetaxel/prednisone should also be offered, accompanied by discussion of toxicity risk. Sipuleucel-T may be offered to asymptomatic/minimally symptomatic men. For men who have experienced progression with docetaxel, cabazitaxel may be offered, accompanied by discussion of toxicity risk. Mitoxantrone may be offered, accompanied by discussion of limited clinical benefit and toxicity risk. Ketoconazole or antiandrogens (eg, bicalutamide, flutamide, nilutamide) may be offered, accompanied by discussion of limited known clinical benefit. Bevacizumab, estramustine, and sunitinib should not be offered. There is insufficient evidence to evaluate optimal sequences or combinations of therapies. Palliative care should be offered to all patients.

A phase 2 study of abiraterone acetate in Japanese men with metastatic castration-resistant prostate cancer who had received docetaxel-based chemotherapy

Objective

In this Phase 2 multicenter study the efficacy and safety of oral abiraterone acetate (1000 mg/once daily) plus prednisolone (5 mg/twice daily) was evaluated in metastatic castration-resistant prostate cancer patients from Japan who had previously received docetaxel-based chemotherapy.

Methods

Men (aged ≥20 years) with metastatic castration-resistant prostate cancer (prostate-specific antigen levels: ≥5 ng/ml), who had received 1 or 2 cytotoxic chemotherapies (with ≥1 regimen being docetaxel) for prostate cancer, were enrolled in this open-label, single-arm study. Primary efficacy endpoint was proportion of patients achieving a ≥50% prostate-specific antigen decline from baseline (prostate-specific antigen response rate) after 12-week treatment. Safety and pharmacokinetics were also assessed.

Results

Confirmed prostate-specific antigen response rate by Week 12 was 28.3% (90% confidence interval: 17.6%; 41.1%) or 13 out of 46 (full analysis set) treated patients. However, total prostate-specific antigen response rate including confirmed and unconfirmed responses was 34.8% (90% confidence interval: 23.2%; 47.9%). Secondary efficacy endpoints and outcomes were: improvement in Eastern Cooperative Oncology Group performance status score by ≥1 unit: 7/16 patients (43.8%); objective radiographic response: complete response, partial response and stable disease in 0, 1/22 (4.5%) and 9/22 (40.9%) patients, respectively; pain palliation response: 9/16 (56.3%) patients. The most common adverse events (>20% patients) were upper respiratory tract infection (13/47, 27.7% patients) and hepatic function abnormal (10/47, 21.3% patients, Grade 3: 8.5%). All mineralocorticoid-related toxicities were Grade 1/2.

Conclusions

Abiraterone acetate plus prednisolone showed favorable efficacy in metastatic castration-resistant prostate cancer Japanese patients who had received chemotherapy. Abiraterone acetate plus prednisolone had an acceptable safety profile.

Clinical trial registration no

NCT01795703.

Emerging mechanisms of enzalutamide resistance in prostate cancer

The majority of prostate cancers are hormone-dependent at diagnosis highlighting the central role of androgen signalling in this disease. Surprisingly, most forms of castration-resistant prostate cancer (CRPC) are still dependent on the androgen receptor (AR) for survival. Therefore, the advent of new AR-targeting drugs, such as enzalutamide, is certainly beneficial for the many patients with metastatic CRPC. Indeed, this compound provides a substantial survival benefit-but it is not curative. This Perspectives article describes the different ways through which cancer cells can become resistant to enzalutamide, such as AR truncation and other mutations, as well as by-pass of the AR dependence of prostate cancer cells through expression of the glucocorticoid receptor. The clinical relevance of these mechanisms and emerging questions concerning new therapeutic regimens in the treatment of metastatic CRPC are being discussed.

Advanced prostate cancer - patient survival and potential impact of enzalutamide and other emerging therapies

The advent of exponential growth of novel agents tested and approved for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) has brought about a need for understanding of the mechanism of action, side-effects, and clinical efficacy of these drugs as they relate to these patients. This review will provide a synopsis of the treatment landscape in mCRPC as varying agents such as abiraterone acetate, cabazitaxel, sipuleucel-T, radium, and selected emerging agents are presented. A distinct focus on the utilization of enzalutamide, its mechanism of action, key pivotal trials that brought about its US Food and Drug Administration approval, as well as patient-focused perspectives and clinical implications are discussed herein.

Strategies for targeting the androgen receptor axis in prostate cancer

Androgen receptor (AR) signaling plays a critical role in prostate cancer cell proliferation, survival, and differentiation. Therapeutic strategies targeting the androgen receptor have been developed for the treatment of metastatic hormone-naïve prostate cancer; however, despite effective targeting recent studies have demonstrated that during progression to a castrate-resistant phenotype there is restoration of AR target gene expression. On the basis of this observation, second-generation therapeutics have been developed to target AR in the castrate-resistant setting resulting in a survival benefit. In this review we will discuss the mechanisms promoting AR signaling and the development of second-generation therapeutics targeting AR in castrate-resistant prostate cancer.

Implementing newer agents for the management of castrate-resistant prostate cancer: what is known and what is needed?

Men receiving androgen-deprivation therapy will in time develop metastatic castrate-resistant prostate cancer (mCRPC). Whilst effective treatment options for mCRPC have traditionally been limited, new agents are becoming available. Since 2010, the number and class of agents available to treat mCRPC has increased dramatically. As such, there is a need for clear guidance on the optimum treatment and sequence of treatments for mCRPC before and after chemotherapy. This evidence-based statement, reflecting the views of the authors, provides suggestions on the continued relevance of conventional approaches to first- and second-line treatment in mCRPC, the potential role of novel treatments, and factors that may influence the choice of hormonal agents and/or chemotherapy.

Glucocorticoids and prostate cancer treatment: friend or foe?

Glucocorticoids have been used in the treatment of prostate cancer to slow disease progression, improve pain control and offset side effects of chemo- and hormonal therapy. However, they may also have the potential to drive prostate cancer growth via mutated androgen receptors or glucocorticoid receptors (GRs). In this review we examine historical and contemporary use of glucocorticoids in the treatment of prostate cancer, review potential mechanisms by which they may inhibit or drive prostate cancer growth, and describe potential means of defining their contribution to the biology of prostate cancer.

Metastatic castration resistant prostate cancer: current strategies of management in the Middle East

Although most patients with prostate cancer respond to initial androgen-deprivation therapy, progression to castration-resistant prostate cancer (CRPC) is almost inevitable. In 2004, the docetaxel/prednisone regimen was approved for the management of patients with metastatic CRPC, becoming the standard first-line therapy. Recent advances have also led to an unprecedented number of approved new drugs; thus, providing several treatment options for patients with metastatic CRPC. Five new drugs have received US Food and Drug Administration-approval between 2010 and 2012: sipuleucel-T, an immunotherapeutic agent; cabazitaxel, a novel microtubule inhibitor; abiraterone acetate, a new androgen biosynthesis inhibitor; enzalutamide, a novel androgen receptor inhibitor; and denosumab, a bone-targeting agent. Such drugs are either already marketed or about to be marketed in the Middle East. Data supporting the approval of each of these agents are described in this review, as are recent approaches to the treatment of metastatic CRPC.

Impact of prednisone on toxicities and survival in metastatic castration-resistant prostate cancer: A systematic review and meta-analysis of randomized clinical trials

We conducted a meta-analysis of randomized trials comparing regimens that included daily oral prednisone (P) in only one arm to investigate its impact on toxicities and outcomes in metastatic castration-resistant prostate cancer (mCRPC). Five trials were identified totaling 2939 patients, of whom 1471 were randomized to an arm not containing P and 1468 received therapy containing P. There was no difference between the non-P and P groups for severe toxicities (incidence rate ratio [IRR]=0.82, p=0.712, I(2)=97.9%). When examining toxicities as a reason for discontinuing therapy, the non-P groups were not different from the P groups (relative risk [RR]=1.24, p=0.413, I(2)=86.8%). The non-P groups demonstrated no difference in OS compared to the P groups (HR=1.09, p=0.531, I(2)=79.7%). The meta-analysis is limited by the trial level design and small number of trials.

[Corticotherapy in castration-resistant prostate cancer]

INTRODUCTION

Corticosteroids are commonly used in the treatment of prostate cancer resistant to castration (PCRC), partly due to the inhibitory effects on adrenal androgen production acting as a pituitary suppressant.

METHODS

A literature search was conducted in PubMed/MEDLINE database using the following key words: prostate cancer; castration resistance; metastasis; corticotherapy.

RESULTS

Corticosteroids exert direct anti-tumoral activities mediated by the glucocorticoids receptor and involving cellular/tissue functions as growth, apoptosis, inflammation, metastasis, differentiation and angiogenesis. As a pain relieving agents, corticosteroids significantly relieve PCRC clinical symptoms, especially those due to bone metastasis. In the comparative arm of phase II-III trials, corticosteroids administered daily produce a PSA decline. Among the adverse effects due to corticosteroids, bone loss and cardiovascular risk should be carefully monitored. In association with abiraterone acetate, corticosteroids increase overall survival in PCRC patients, and reduce the mineralocorticoid side effects of abiraterone.

CONCLUSION

Corticosteroids in monotherapy for PCRC have a limited efficacy. In association with abiraterone acetate it reduces the mineralocorticoid toxicity and enhances the androgenic suppression.

Enzalutamide, a second generation androgen receptor antagonist: development and clinical applications in prostate cancer

Enzalutamide, formerly known as MDV3100, is an oral second generation androgen receptor (AR) inhibitor that was chosen from a screen of agents and shown in preclinical studies to have greater affinity for the AR than its predecessors without any agonistic effects. The pre-clinical work that led to the interest in studying this agent and the history of the clinical development of enzalutamide from first in man phase 1 through phase 3 and regulatory approval are reviewed. Information about the toxicity profile and prescribing enzalutamide are discussed in detail. The availability of enzalutamide is put into context with the five other agents that modify survival outcomes in metastatic castration resistant prostate cancer. Some of the new challenges confronting the field regarding sequencing and combinations of these agents and the potential for a change in the natural history of the disease, are also discussed.

Effect of abiraterone acetate treatment on the quality of life of patients with metastatic castration-resistant prostate cancer after failure of docetaxel chemotherapy

BACKGROUND

In a recent randomised, double-blind, phase III clinical trial among 1195 patients with metastatic castration-resistant prostate cancer (mCRPC) who had failed docetaxel chemotherapy, abiraterone acetate was shown to significantly prolong overall survival compared with prednisone alone. Here we report on the impact of abiraterone therapy on the health-related quality of life (HRQoL) observed during this trial, assessed using the validated Functional Assessment of Cancer Therapy-Prostate (FACT-P) questionnaire.

METHODS

All analyses were conducted using prespecified criteria for clinically meaningful improvement and deterioration in FACT-P total score as well as subscale scores; all respective thresholds were defined using an accepted methodology. Improvement was assessed only in patients with clinically significant functional status impairment at baseline.

RESULTS

Significant improvements in the FACT-P total score were observed in 48% of patients receiving abiraterone versus 32% of patients receiving prednisone (p < 0.0001). Also, the median time to deterioration in FACT-P total score was longer (p < 0.0001) in patients receiving abiraterone (59.9 weeks versus 36.1 weeks). Similar differences were observed in all FACT-P subscales, with the exception of the social/family well-being domain. Median time to improvement in the physical well-being domain and the trial outcome index was significantly shorter (p < 0.01) with abiraterone when compared with the prednisone arm.

CONCLUSIONS

The previously demonstrated survival benefit for abiraterone is accompanied by improvements in patient-reported HRQoL and a significant delay in HRQoL deterioration when compared with prednisone.

Metastatic castration-resistant prostate cancer: critical review of enzalutamide

Enzalutamide, previously known as MDV300, is an oral, second-generation androgen receptor (AR) signaling inhibitor or antagonist that was approved by the Food and Drug Administration in 2012 for the treatment of metastatic castrate-resistant prostate cancer (mCRPC) postdocetaxel. Preclinical studies have demonstrated impressive affinity to the AR compared to the first-generation AR inhibitors. The landmark Phase III AFFIRM trial demonstrated improved overall survival benefit compared to placebo in addition to improvement in all tested parameters. Enzalutamide is currently being studied in several trials prechemotherapy and in earlier settings of prostate cancer. This review will discuss the mechanism of action of enzalutamide, its pharmacokinetics, the preclinical and clinical trials that led to its approval, the ongoing clinical trials, its safety and efficacy, as well as patterns of resistance, and discusses its place in therapy within the context of several recently approved agents for mCRPC.

Targeting the apoptosis pathway in prostate cancer

Important inroads have been made in the understanding and treatment of metastatic prostate cancer in recent years. However, the need for agents targeting novel pathways remains ever present. One such area with promise is through apoptosis or programmed cell death. Many perturbations within the apoptotic process have been associated with treatment resistance and progression in castration-resistant prostate cancer; thus, therapeutic potential exists with agents that can restore an effective apoptotic response to cellular stressors. This article focuses on agents in clinical development targeting apoptosis through the intrinsic and extrinsic pathways. We review the current status of agents that intervene at the Bcl2 checkpoints, humanized antibodies to death receptors, agents that target the inhibitors of apoptosis proteins, mimetics of small mitochondria-derived activator of caspases, and antisense therapies targeting cytoprotective chaperones. Although single-agent activity has been demonstrated with some of these agents, the clinical development path forward will see them coupled with standard hormonal therapy and chemotherapy. OGX-011 (custirsen), which inhibits expression of the cytoprotective chaperone protein clusterin, is the most mature of these agents and is being tested in combination with chemotherapy in phase III clinical trials for castration-resistant prostate cancer, and results are eagerly awaited.

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

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

Effect of abiraterone acetate on fatigue in patients with metastatic castration-resistant prostate cancer after docetaxel chemotherapy

BACKGROUND

Fatigue is a common, debilitating side-effect of prostate cancer and its treatment. Patient-reported fatigue was evaluated as part of COU-AA-301, a randomized, placebo-controlled, phase III trial of abiraterone acetate and prednisone versus placebo and prednisone in metastatic castration-resistant prostate cancer (mCRPC) patients after docetaxel chemotherapy. This is the first phase III study in advanced prostate cancer to evaluate fatigue outcomes using a validated fatigue-specific instrument.

PATIENTS AND METHODS

The Brief Fatigue Inventory (BFI) questionnaire was used to measure patient-reported fatigue intensity and fatigue interference with activities of daily life. All analyses were conducted using prespecified responder definitions of clinically meaningful changes.

RESULTS

A total of 797 patients were randomized to abiraterone acetate and prednisone, and 398 were randomized to placebo and prednisone. Compared with prednisone alone, in patients with clinically significant fatigue at baseline, abiraterone acetate and prednisone significantly increased the proportion of patients reporting improvement in fatigue intensity (58.1% versus 40.3%, P = 0.0001), improved fatigue interference (55.0% versus 38.0%, P = 0.0075), and accelerated improvement in fatigue intensity (median 59 days versus 194 days, P = 0.0155).

CONCLUSIONS

In patients with mCRPC progressing after docetaxel chemotherapy, abiraterone acetate and prednisone yielded clinically meaningful improvements in patient-reported fatigue compared with prednisone alone.

Antiandrogenic and growth inhibitory effects of ring-substituted analogs of 3,3'-diindolylmethane (ring-DIMs) in hormone-responsive LNCaP human prostate cancer cells

BACKGROUND

Cruciferous vegetables protect against prostate cancer. Indole-3-carbinol (I3C) and its major metabolite 3,3'-diindolylmethane (DIM), exhibit antitumor activities in vitro and in vivo. Several synthetic ring-substituted dihaloDIMs (ring-DIMs) appear to have increased anticancer activity.

METHODS

Inhibition of LNCaP prostate cancer cell growth was measured by a WST-1 cell viability assay. Cytoplasmic and nuclear proteins were analyzed by immunoblotting and immunofluorescence. Androgen receptor (AR) activation was assessed by measuring prostate-specific antigen (PSA) expression and using LNCaP cells containing human AR and an AR-dependent probasin promoter-green fluorescent protein (GFP) construct.

RESULTS

Like DIM, several ring-substituted dihaloDIM analogs, namely 4,4'-dibromo-, 4,4'-dichloro-, 7,7'-dibromo-, and 7,7'-dichloroDIM, significantly inhibited DHT-stimulated growth of LNCaP cells at concentrations ≥1 µM. We observed structure-dependent differences for the effects of the ring-DIMs on AR expression, nuclear AR accumulation and PSA levels in LNCaP cells after 24 hr. Both 4,4'- and 7,7'-dibromoDIM decreased AR protein and mRNA levels, whereas 4,4'- and 7,7'-dichloroDIM had minimal effect. All four dihaloDIMs (10 and 30 µM) significantly decreased PSA protein and mRNA levels. Immuofluorescence studies showed that only the dibromoDIMs increased nuclear localization of AR. All ring-DIMs caused a concentration-dependent decrease in fluorescence induced by the synthetic androgen R1881 in LNCaP cells transfected with wild-type human AR and an androgen-responsive probasin promoter-GFP gene construct, with potencies up to 10-fold greater than that of DIM.

CONCLUSION

The antiandrogenic effects of ring-DIMs suggest they may form the basis for the development of novel agents against hormone-sensitive prostate cancer, alone or in combination with other drugs.

A phase II study of sorafenib in combination with bicalutamide in patients with chemotherapy-naive castration resistant prostate cancer

PURPOSE

The objective of this trial was to evaluate the clinical effects of sorafenib, a multi-targeted kinase inhibitor, in combination with androgen receptor blockade in patients with castration-resistant prostate cancer.

METHODS

This was a multicenter, two-stage, phase 2 trial. Eligible patients had rising PSA, minimal symptoms and were chemotherapy-naïve. Sorafenib 400 mg twice daily was administered with bicalutamide 50 mg once daily on a 28-day cycle. The primary endpoint was PSA response (≥ 50% decline) or stable disease ≥ 6 months.

RESULTS

39 patients were enrolled including eight without clinical evidence of metastases. Eighteen (47%) patients have had either a PSA response or stable disease ≥ 6 months. PSA declines of ≥ 50% occurred in 12 (32%) of 38 assessable patients, including seven of 27 patients (26%) with prior anti-androgen use. Median time to treatment failure was 5.5 months (95%CI = 4.8.1-8.3). Grade ≥ 3 adverse events included fatigue, skin rash, and hand-foot syndrome.

CONCLUSIONS

PSA declines and stable disease were observed with a combination of sorafenib and bicalutamide including in patients previously progressing on bicalutamide. Strategies to combine multi-targeted kinase inhibitors with hormonal therapies warrant further study in patients with CRPC.