Safety and clinical activity of BMS-986365 (CC-94676), a dual androgen receptor ligand-directed degrader and antagonist, in heavily pretreated patients with metastatic castration-resistant prostate cancer.

BACKGROUND: Metastatic castration-resistant prostate cancer (mCRPC) that progresses on androgen receptor pathway inhibitors (ARPIs) may continue to be driven by AR signaling. BMS-986365 is an orally administered ligand-directed degrader targeting the AR via a first-in-class dual mechanism of AR degradation and antagonism. CC-94676-PCA-001 (NCT04428788) is a phase 1 multicenter study of BMS-986365 in patients with progressive mCRPC. PATIENTS AND METHODS: Patients who progressed on androgen deprivation therapy, ≥ 1 ARPI, and taxane chemotherapy (unless declined/ineligible) were enrolled. The study included dose escalation (Part A) and expansion (Part B) of BMS-986365 up to 900 mg twice daily (BID). Primary objectives were safety, tolerability, and to define maximum tolerated dose (MTD) and/or recommended phase 2 dose (RP2D). Key secondary endpoints included decline in prostate-specific antigen ≥50% (PSA50) and radiographic progression-free survival (rPFS). RESULTS: Parts A and B enrolled 27 and 68 patients, respectively. In Part B, the median number of prior therapies was 4 (range 2-11). The most common treatment-related adverse events (TRAEs) were asymptomatic prolonged corrected QT interval (47%) and bradycardia (34%). Part A MTD was not reached and RP2D selection is ongoing. Across Part B three highest doses (400-900 mg BID, n = 60), PSA50 was 32% (n = 19), including 50% (n = 10/20) at 900 mg; median rPFS (95% CI) was 6.3 months (5.3-12.6), including 8.3 months (3.8-16.6) at 900 mg; and rPFS was longer in patients without versus with prior chemotherapy: 16.5 months (5.5-not evaluable) versus 5.5 months (2.7-8.3), respectively. Efficacy was observed in patients with AR ligand binding domain (LBD) WT or with AR LBD mutations. CONCLUSIONS: BMS-986365 was well tolerated, with a manageable safety profile, and demonstrated activity in heavily pretreated patients with potentially higher benefit in chemotherapy-naïve patients. These data show BMS-986365's potential to overcome resistance to current ARPIs, regardless of AR LBD mutation status.

Fragmentomic analysis of circulating tumor DNA-targeted cancer panels.

BACKGROUND: The isolation of cell-free DNA (cfDNA) from the bloodstream can be used to detect and analyze somatic alterations in circulating tumor DNA (ctDNA), and multiple cfDNA-targeted sequencing panels are now commercially available for Food and Drug Administration (FDA)-approved biomarker indications to guide treatment. More recently, cfDNA fragmentation patterns have emerged as a tool to infer epigenomic and transcriptomic information. However, most of these analyses used whole-genome sequencing, which is insufficient to identify FDA-approved biomarker indications in a cost-effective manner. PATIENTS AND METHODS: We used machine learning models of fragmentation patterns at the first coding exon in standard targeted cancer gene cfDNA sequencing panels to distinguish between cancer and non-cancer patients, as well as the specific tumor type and subtype. We assessed this approach in two independent cohorts: a published cohort from GRAIL (breast, lung, and prostate cancers, non-cancer, n = 198) and an institutional cohort from the University of Wisconsin (UW; breast, lung, prostate, bladder cancers, n = 320). Each cohort was split 70%/30% into training and validation sets. RESULTS: In the UW cohort, training cross-validated accuracy was 82.1%, and accuracy in the independent validation cohort was 86.6% despite a median ctDNA fraction of only 0.06. In the GRAIL cohort, to assess how this approach performs in very low ctDNA fractions, training and independent validation were split based on ctDNA fraction. Training cross-validated accuracy was 80.6%, and accuracy in the independent validation cohort was 76.3%. In the validation cohort where the ctDNA fractions were all <0.05 and as low as 0.0003, the cancer versus non-cancer area under the curve was 0.99. CONCLUSIONS: To our knowledge, this is the first study to demonstrate that sequencing from targeted cfDNA panels can be utilized to analyze fragmentation patterns to classify cancer types, dramatically expanding the potential capabilities of existing clinically used panels at minimal additional cost.

Development and validation of circulating tumour cell enumeration (Epic Sciences) as a prognostic biomarker in men with metastatic castration-resistant prostate cancer.

PURPOSE: To evaluate the prognostic significance of circulating tumour cell (CTC) number determined on the Epic Sciences platform in men with metastatic castration-resistant prostate cancer (mCRPC) treated with an androgen receptor signalling inhibitor (ARSI). PATIENTS AND METHODS: A pre-treatment blood sample was collected from men with progressing mCRPC starting either abiraterone or enzalutamide as a first-, second- or third-line systemic therapy at Memorial Sloan Kettering Cancer Center (Discovery cohort, N = 171) or as a first- or second-line therapy as part of the multicenter PROPHECY trial (NCT02269982) (Validation cohort, N = 107). The measured CTC number was then associated with overall survival (OS) in the Discovery cohort, and progression-free survival (PFS) and OS in the Validation cohort. CTC enumeration was also performed on a concurrently obtained blood sample using the CellSearch® Circulating Tumor Cell Kit. RESULTS: In the MSKCC Discovery cohort, CTC count was a statistically significant prognostic factor of OS as a dichotomous (<3 CTCs/mL versus ≥ 3 CTCs/mL; hazard ratio [HR] = 1.8 [95% confidence interval {CI} 1.3-3.0]) and a continuous variable when adjusting for line of therapy, presence of visceral metastases, prostate-specific antigen, lactate dehydrogenase and alkaline phosphatase. The findings were validated in an independent datas et from PROPHECY (HR [95% CI] = 1.8 [1.1-3.0] for OS and 1.7 [1.1-2.9] for PFS). A strong correlation was also observed between CTC counts determined in matched samples on the CellSearch® and Epic platforms (r = 0.84). CONCLUSION: The findings validate the prognostic significance of pretreatment CTC number determined on the Epic Sciences platform for predicting OS in men with progressing mCRPC starting an ARSI.

Development and validation of a prognostic model for overall survival in chemotherapy-naïve men with metastatic castration-resistant prostate cancer.

Background: Prognostic models are needed that reflect contemporary practice for men with metastatic castration-resistant prostate cancer (mCRPC). We sought to identify predictive and prognostic variables for overall survival (OS) in chemotherapy-naïve men with mCRPC treated with enzalutamide. Patients and methods: Patients from the PREVAIL trial database (enzalutamide versus placebo) were randomly split 2 : 1 into training (n = 1159) and testing (n = 550) sets. Using the training set, 23 predefined variables were analyzed and a multivariable model predicting OS was developed and validated in an independent testing set. Results: Patient characteristics and outcomes were well balanced between training and testing sets; median OS was 32.7 months in each. The final validated multivariable model included 11 independent prognostic variables. Median OS for low-, intermediate-, and high-risk groups (testing set) defined by prognostic risk tertiles were not yet reached (NYR) (95% CI NYR-NYR), 34.2 months (31.5-NYR), and 21.1 months (17.5-25.0), respectively. Hazard ratios (95% CI) for OS in the low- and intermediate-risk groups versus high-risk group were 0.20 (0.14-0.29) and 0.40 (0.30-0.53), respectively. Secondary outcomes of response and progression differed widely in model-defined risk groups. Enzalutamide improved outcomes in all prognostic risk groups. Conclusions: Our validated prognostic model incorporates variables routinely collected in chemotherapy-naïve men with mCRPC treated with enzalutamide, identifying subsets of patients with widely differing survival outcomes that provide useful information for external validation, patient care, and clinical trial design. Trial registration: ClinicalTrials.gov: NCT01212991.

Effect of Prophylactic Calcitriol Administration on Serum Ionized Calcium Concentrations after Parathyroidectomy: 78 Cases (2005-2015).

BACKGROUND: Prophylactic administration of calcitriol has been suggested to mitigate the risk of hypocalcemia after parathyroidectomy. The effect of calcitriol on postoperative serum ionized calcium concentrations has not been evaluated in dogs after parathyroidectomy. HYPOTHESIS/OBJECTIVES: To determine the effect of prophylactic calcitriol administration on postoperative serum ionized calcium (iCa) concentrations in dogs with primary hyperthyroidism (PHPTH) treated by parathyroidectomy. ANIMALS: Seventy-eight dogs with primary hyperparathyroidism treated surgically. METHODS: Multi-institutional retrospective case study. Medical records from 2005 to 2015 were evaluated. Dogs were included if they had a diagnosis of PHPTH and had surgery to remove parathyroid tissue. Serum iCa concentrations were monitored for a minimum of 2 days postoperatively. Two study groups were evaluated: calcitriol administration and no calcitriol administration. RESULTS: Serial postoperative iCa concentrations measured at 12-hour time intervals for 2 days postoperatively were positively associated with preoperative iCa concentrations. This association was evident at each time interval, and the effect of preoperative iCa concentrations on postoperative iCa concentrations decreased as time elapsed (12 hours, P < 0.0001; 24 hours, P < 0.0001; 36 hours, P < 0.04; and 48 hours, P = 0.01). Prophylactic calcitriol administration was not found to be significantly associated with postoperative iCa concentrations or its rate of decrease after parathyroidectomy. CONCLUSION AND CLINICAL IMPORTANCE: We found no protective value in administering calcitriol prophylactically to prevent hypocalcemia in the immediate postoperative period (48 hours) after parathyroidectomy. Preoperative iCa concentrations had a significant positive association with postoperative iCa concentrations throughout the monitoring period.

Achieving assessor accuracy on the International Standards for Neurological Classification of Spinal Cord Injury.

STUDY DESIGN: A retrospective audit of assessor accuracy using the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) in three multicentre randomised controlled trials (SCIPA: Spinal Cord Injury and Physical Activity) spanning 2010-2014 with standards revised in 2011. OBJECTIVES: To investigate assessor accuracy of neurological classification after spinal cord injury. SETTING: Australia and New Zealand. METHODS: ISNCSCI examinations were undertaken by trained clinicians prior to randomisation. Data were recorded manually and ISNCSCI worksheets circulated to panels, consensus reached and worksheets corrected. An audit team used a 2014 computerised ISNCSCI algorithm to check manual worksheets. A second audit team assessed whether the 2014 computerised algorithm accurately reflected pre- and post-2011 ISNCSCI standards. RESULTS: Of the 208 ISNCSCI worksheets, 24 were excluded. Of the remaining 184 worksheets, 47 (25.5%) were consistent with the 2014 computerised algorithm and 137 (74.5%) contained one or more errors. Errors were in motor (30.1%) or sensory (12.4%) levels, zone of partial preservation (24.0%), motor/sensory scoring (21.5%), ASIA Impairment Scale (AIS, 8.3%) and complete/incomplete classification (0.8%). Other difficulties included classification when anal contraction/sensation was omitted, incorrect neurological levels and violation of the 'motor follows sensory rule in non-testable myotomes' (7.4%). Panel errors comprised corrections that were incorrect or missed or incorrect changes to correct worksheets. CONCLUSION: Given inaccuracies in the manual ISNCSCI worksheets in this long-term clinical trial setting, continued training and a computerised algorithm are essential to ensure accurate scoring, scaling and classification of the ISNCSCI and confidence in clinical trials.

Androgen receptor variant-driven prostate cancer: clinical implications and therapeutic targeting.

While there are myriad mechanisms of primary and acquired resistance to conventional and next-generation hormonal therapies in prostate cancer, the potential role of androgen receptor splice variants (AR-Vs) has recently gained momentum. AR-Vs are abnormally truncated isoforms of the androgen receptor (AR) protein that lack the COOH-terminal domain but retain the NH2-terminal domain and DNA-binding domain and are thus constitutively active even in the absence of ligands. Although multiple preclinical studies have previously implicated AR-Vs in the development of castration resistance as well as resistance to abiraterone and enzalutamide, recent technological advances have made it possible to reliably detect and quantify AR-Vs from human clinical tumor specimens including blood samples. Initial clinical studies have now shown that certain AR-Vs, in particular AR-V7, may be associated with resistance to abiraterone and enzalutamide but not taxane chemotherapies when detected in circulating tumor cells. Efforts are now underway to clinically validate AR-V7 as a relevant treatment-selection biomarker in the context of other key genomic aberrations in men with metastatic castration-resistant prostate cancer. Additional efforts are underway to therapeutically target both AR and AR-Vs either directly or indirectly. Whether AR-Vs represent drivers of castration-resistant prostate cancer, or whether they are simply passenger events associated with aggressive disease or clonal heterogeneity, will ultimately be answered only through these types of clinical trials.

A phase 2 multimodality trial of docetaxel/prednisone with sunitinib followed by salvage radiation therapy in men with PSA recurrent prostate cancer after radical prostatectomy.

BACKGROUND: In men with high Gleason PC and rapid PSA progression after surgery, failure rates remain unacceptably high despite salvage radiation. We explored a novel multimodality approach of docetaxel with anti-angiogenic therapy before salvage radiotherapy (RT). METHODS: This was a phase 2 single-arm prospective open-label trial with historic controls. Eligible men had a rising PSA of 0.1-3.0 ng ml(-1) within 4 years of radical prostatectomy, no metastases except resected nodal disease, no prior androgen-deprivation therapy (ADT) and Gleason 7-10. Men received four cycles of docetaxel 70 mg m(-2) every 3 weeks with low dose prednisone and sunitinib 37.5 mg daily for 14/21 days each cycle, with no ADT. Salvage prostate bed RT (66 Gy) started at day 100. The primary end point was progression-free survival (PFS) rate at 24 months. Safety data, quality of life (QOL) and dose-limiting toxicities (DLTs) were measured over time. RESULTS: Thirty-four men accrued in this multi-institutional clinical trial: 24% of men were node positive, 47% were Gleason 8-10, median PSA at entry was 0.54. The trial was terminated prematurely owing to excess DLTs (nine) including grade 3 hand-foot syndrome (n=4), neutropenic fever (n=2), AST increase (n=1), fatigue (n=1) and vomiting with diarrhea (n=1). PFS rate at 24 months was 51% (95% CI: 33, 67%) with a median PFS of 26.2 months (95% CI: 12.5, -). Six men (17.6%) had an undetectable PSA at 2 years. CONCLUSIONS: Sunitinib and docetaxel/prednisone followed by salvage RT resulted in excess pre-specified DLTs. Although nearly half of the men experienced durable disease control, efficacy was not greater than expected with radiation alone. The use of the intermediate end point of PFS in this salvage setting permitted an early decision on further development of this combination.

Distinct routes to metastasis: plasticity-dependent and plasticity-independent pathways.

The cascade that culminates in macrometastases is thought to be mediated by phenotypic plasticity, including epithelial-mesenchymal and mesenchymal-epithelial transitions (EMT and MET). Although there is substantial support for the role of EMT in driving cancer cell invasion and dissemination, much less is known about the importance of MET in the later steps of metastatic colonization. We created novel reporters, which integrate transcriptional and post-transcriptional regulation, to test whether MET is required for metastasis in multiple in vivo cancer models. In a model of carcinosarcoma, metastasis occurred via an MET-dependent pathway; however, in two prostate carcinoma models, metastatic colonization was MET independent. Our results provide evidence for both MET-dependent and MET-independent metastatic pathways.

Evaluation of an epithelial plasticity biomarker panel in men with localized prostate cancer.

BACKGROUND: Given the potential importance of epithelial plasticity (EP) to cancer metastasis, we sought to investigate biomarkers related to EP in men with localized prostate cancer (PC) for the association with time to PSA recurrence and other clinical outcomes after surgery. METHODS: Men with localized PC treated with radical prostatectomy at the Durham VA Medical Center and whose prostatectomy tissues were included in a tissue microarray (TMA) linked to long-term outcomes. We performed immunohistochemical studies using validated antibodies against E-cadherin and Ki-67 and mesenchymal biomarkers including N-cadherin, vimentin, SNAIL, ZEB1 and TWIST. Association studies were conducted for each biomarker with baseline clinical/pathologic characteristics an risk of PSA recurrence over time. RESULTS: Two hundred and five men contributed TMA tissue and had long-term follow-up (median 11 years). Forty-three percent had PSA recurrence; three died of PC. The majority had high E-cadherin expression (86%); 14% had low/absent E-cadherin expression. N-cadherin was rarely expressed (<4%) and we were unable to identify an E-to-N-cadherin switch as independently prognostic. No associations with clinical risk group, PSA recurrence or Gleason sum were noted for SNAIL, ZEB1, vimentin or TWIST, despite heterogeneous expression between patients. We observed an association of higher Ki-67 expression with Gleason sum (P=0.043), National Comprehensive Cancer Network risk (P=0.013) and PSA recurrence (hazard ratio 1.07, P=0.016). CONCLUSIONS: The expression of EP biomarkers in this cohort of men with a low risk of PC-specific mortality was not associated with aggressive features or PSA relapse after surgery.

Efficacy and safety of enzalutamide in patients 75 years or older with chemotherapy-naive metastatic castration-resistant prostate cancer: results from PREVAIL.

BACKGROUND: Prostate cancer disproportionately affects older men. Because age affects treatment decisions, it is important to understand the efficacy and tolerability of therapies for advanced prostate cancer in elderly men. This analysis describes efficacy and safety outcomes in men aged ≥75 years who received enzalutamide, an androgen receptor inhibitor, in the phase III PREVAIL trial. PATIENTS AND METHODS: PREVAIL was a randomised, double-blind, multinational study of oral enzalutamide 160 mg/day (N = 872) versus placebo (N = 845) in chemotherapy-naive men with metastatic castration-resistant prostate cancer. Overall survival (OS) and radiographic progression-free survival (rPFS) were coprimary end points. Subgroup analysis of men aged ≥75 years (elderly) and men aged <75 years was pre-specified for the coprimary end points and adverse events (AEs). RESULTS: Among 609 elderly patients (35%) who participated in PREVAIL, median treatment duration was 16.6 and 5.0 months in the enzalutamide and placebo arms, respectively. In the elderly subgroup, OS was greater with enzalutamide than with placebo [32.4 months (95% confidence interval (CI) 27.7-not yet reached] versus 25.1 months (95% CI 22.6-28.0); hazard ratio (HR) = 0.61 (95% CI 0.47-0.79); P = 0.0001], as was rPFS [not yet reached (95% CI 12.3-not yet reached) versus 3.7 months (95% CI 3.6-5.3); HR = 0.17 (95% CI 0.12-0.24); P < 0.0001]. Irrespective of treatment assignment, incidence of AEs was similar between the two age groups, except for an overall higher incidence of falls among elderly patients than younger patients [84/609 (13.8%) versus 62/1106 (5.6%)] and among elderly patients receiving enzalutamide than those receiving placebo [61/317 (19.2%) versus 23/292 (7.9%)]. CONCLUSIONS: Elderly men benefited from treatment with enzalutamide in terms of OS and rPFS. Enzalutamide was well tolerated in the elderly subgroup and those aged <75 years. Age and enzalutamide treatment were associated with a higher incidence of falls. CLINICAL TRIAL IDENTIFIER: NCT01212991, ClinicalTrials.gov.

Reversal of PSA progression on abiraterone acetate through the administration with food in men with metastatic castration-resistant prostate cancer.

BACKGROUND: Owing to efficacy and tolerability, abiraterone acetate (AA) is a leading treatment for men with metastatic castration-resistant prostate cancer. Increased serum concentrations of AA, such as by taking AA with food, may lead to the inhibition of additional enzymes in the androgen synthesis pathway implicated in castration-resistant prostate cancer progression. METHODS: Medical records of men with metastatic castration-resistant prostate cancer (mCRPC) who received AA between 1 April 2011 and 31 December 2013 were retrospectively reviewed. The primary outcome was the percent of men with a rising PSA on AA who experienced any PSA decline within 3 months after changing the administration of AA from without food to with food. Secondary outcomes were median time on AA therapy in men who received AA therapy without food versus those that switched administration from without food to with food at PSA progression, and the percent of men who experienced any decline in serum testosterone concentration, and the rate of adverse events observed while taking AA with food. RESULTS: Nineteen men who switched AA administration from without food to with food and 41 patients who administered AA without food only were included in the study. Of those patients who took AA with food at PSA progression, a PSA decline was observed in 3 of the 19 (16%) men, including 3 of the 14 men who had an initial response to AA (21%). Testosterone declined in five out of seven patients from pre-food levels. The median time on AA therapy was increased by nearly 100 days in patients who switched AA administration from without food to with food. No increases in toxicity were observed. CONCLUSION: Some men with mCRPC may benefit from taking AA with food. Further prospective comparative studies are needed to determine if changing AA administration is beneficial.

Long-term survival and biomarker correlates of tasquinimod efficacy in a multicenter randomized study of men with minimally symptomatic metastatic castration-resistant prostate cancer.

PURPOSE: Tasquinimod (Active Biotech) is an oral immunomodulatory, anti-angiogenic, and anti-metastatic agent that delayed metastatic disease progression in a randomized placebo-controlled phase II trial in men with metastatic castration-resistant prostate cancer (mCRPC). Here, we report long-term survival with biomarker correlates from this trial. EXPERIMENTAL DESIGN: Two hundred and one (134 tasquinimod and 67 placebo) men with mCRPC were evaluated. Forty-one men randomized to placebo crossed over to tasquinimod. Survival data were collected with a median follow-up time of 37 months. Exploratory biomarker studies at baseline and over time were collected to evaluate potential mechanism-based correlates with tasquinimod efficacy including progression-free survival (PFS) and overall survival (OS). RESULTS: With 111 mortality events, median OS was 33.4 months for tasquinimod versus 30.4 months for placebo overall, and 34.2 versus 27.1 months in men with bone metastases (n = 136), respectively. Multivariable analysis demonstrated an adjusted HR of 0.52 [95% confidence interval (CI), 0.35-0.78; P = 0.001] for PFS and 0.64 (95% CI, 0.42-0.97; P = 0.034) for OS, favoring tasquinimod. Time-to-symptomatic progression was improved with tasquinimod (P = 0.039, HR = 0.42). Toxicities tended to be mild in nature and improved over time. Biomarker analyses suggested a favorable impact on bone alkaline phosphatase and lactate dehydrogenase (LDH) over time and a transient induction of inflammatory biomarkers, VEGF-A, and thrombospondin-1 levels with tasquinimod. Baseline levels of thrombospondin-1 less than the median were predictive of treatment benefit. CONCLUSIONS: The survival observed in this trial of men with minimally symptomatic mCRPC suggests that the prolongation in PFS with tasquinimod may lead to a survival advantage in this setting, particularly among men with skeletal metastases, and has a favorable risk:benefit ratio.

Pharmacodynamic study of disulfiram in men with non-metastatic recurrent prostate cancer.

BACKGROUND: Preclinical drug screens identified disulfiram as a potent in vitro inhibitor of prostate cancer (PCa) cell growth. Although many mechanisms for its anticancer activity have been proposed, tumor suppressor gene re-expression through promoter demethylation emerged as one of the more plausible. METHODS: We conducted an open-label, dose escalation trial of disulfiram in men with non-metastatic recurrent PCa after local therapy. Dose escalation occurred if a demethylating 'response' (that is, 10% decrease in peripheral blood mononuclear cell (PBMC) global 5-methyl cytosine (5(me)C) content) was observed in <3 patients in cohort 1. Cohorts 1 and 2 received disulfiram 250 mg and 500 mg daily, respectively. The primary end point was the proportion of subjects with a demethylation response. Secondary end points included the rate of PSA progression at 6 months, changes in PSA doubling time and safety/tolerability. RESULTS: Changes in global 5(me)C content were observed in two of nine patients (22.2%) in cohort 1 and 3 of 10 (30.0%) in cohort 2. Only five subjects were on trial for 6 months, all were in cohort 1 and all had PSA progression by 6 months. No changes in PSA kinetics were observed in either cohort. Disulfiram was poorly tolerated with six patients experiencing grade 3 adverse events (three per cohort). Three of the responders displayed pretreatment instability in their 5(me)C content. CONCLUSIONS: A minority of patients had transient global PBMC demethylation changes. Instability in 5(me)C may limit the reproducibility of these findings, limiting our ability to confirm our hypothesis. Given the toxicities and no clinical benefits, further development of disulfiram should not be pursued in this population.

Clinical activity of abiraterone acetate in patients with metastatic castration-resistant prostate cancer progressing after enzalutamide.

BACKGROUND: Abiraterone acetate and enzalutamide both improve outcomes in patients with metastatic castration-resistant prostate cancer (mCRPC). Optimal sequencing for these agents and whether cross-resistance occurs is unknown. METHODS: Multicentre review of patients with mCRPC treated with abiraterone acetate and prednisone after progressing on enzalutamide. Primary objective was to determine abiraterone acetate response. RESULTS: Thirty patients identified from four North American centres. At abiraterone initiation, median age was 70 years (56-84 years); 70% had ECOG performance status of 0-1; all had prior docetaxel. Median prior enzalutamide treatment duration was 41 weeks (6-95 weeks), with 70% (21 of 30) having a ≥30% prostate-specific antigen (PSA) decline. Median abiraterone acetate treatment duration was 13 weeks (1-52). No objective radiographic responses were observed. Median abiraterone time to progression (PSA, objective or symptomatic) was 15.4 weeks [95% confidence interval (CI) 10.7-20.2]. Median overall survival was 50.1 weeks (95% CI 28.3-72.0). Three patients had a ≥30% PSA decline with abiraterone. Two of these patients had PSA progression as best response with prior enzalutamide. CONCLUSIONS: In this study of patients progressing after enzalutamide, treatment with abiraterone was associated with a modest response rate and brief duration of effect. Primary progression on enzalutamide may not preclude a response to abiraterone.

Novel therapies for the treatment of advanced prostate cancer.

In recent years, great success has been achieved on many fronts in the treatment of men with metastatic castration-resistant prostate cancer (CRPC), including novel chemotherapeutics, immunotherapies, bone microenvironment-targeted agents, and hormonal therapies. Numerous agents are currently in early-phase clinical trial development for the treatment of advanced prostate cancer. These novel therapies target several areas of prostate tumor biology, including the upregulation of androgen signaling and biosynthesis, critical oncogenic intracellular pathways, epigenetic alterations, and cancer immunology. Importantly, the characterization of the prostate cancer genome offers the potential to exploit conserved genetic alterations, which may increase the efficacy of these targeted therapies. Predictive and prognostic biomarkers are urgently needed to maximize therapeutic efficacy and safety of these promising new treatments options in prostate cancer.

Emerging therapeutic approaches in the management of metastatic castration-resistant prostate cancer.

Although treatment options for men with castration-resistant prostate cancer (CRPC) have improved with the recent and anticipated approvals of novel immunotherapeutic, hormonal, chemotherapeutic and bone-targeted agents, clinical benefit with these systemic therapies is transient and survival times remain unacceptably short. Thus, we devote the second section of this two-part review to discussing emerging therapeutic paradigms and research strategies that are entering phase II and III clinical testing for men with metastatic CRPC. We will discuss a range of emerging hormonal, immunomodulatory, antiangiogenic, epigenetic and cell survival pathway inhibitors in current clinical trials, with an emphasis on how these therapies may complement our existing treatment options.

Evolving standards in the treatment of docetaxel-refractory castration-resistant prostate cancer.

The management of men with metastatic castration-resistant prostate cancer (CRPC) has taken several leaps forward in the past year, with the demonstration of improved overall survival with three novel agents (sipuleucel-T, cabazitaxel with prednisone and abiraterone acetate with prednisone), and a significant delay in skeletal-related events observed with denosumab. The pipeline of systemic therapies in prostate cancer remains strong, as multiple agents with a diverse array of mechanisms of action are showing preliminary signs of clinical benefit, leading to more definitive phase III confirmatory trials. In this review, which represents part 1 of a two-part series on metastatic CRPC, we will summarize the mechanisms of resistance to hormonal and chemotherapies and discuss the evolving landscape of treatment options for men with CRPC, with a particular focus on currently approved and emerging treatment options following docetaxel administration, as well as prognostic factors in this post-docetaxel state. As docetaxel remains the standard initial systemic therapy for men with metastatic CRPC for both palliative and life-prolonging purposes, knowledge of these evolving standards will help to optimize delivery of care and long-term outcomes.