Exploratory analysis of the visceral disease subgroup in a phase III study of abiraterone acetate in metastatic castration-resistant prostate cancer

Differences in clinical outcome between docetaxel and abiraterone acetate as the first-line treatment in chemo-naïve metastatic castration-resistant prostate cancer patients with or without the ineligible clinical factors of the COU-AA-302 study

Background

This study aimed to compare the efficacy of abiraterone acetate (AA) versus docetaxel (T) as first-line treatment in chemo-naïve metastatic castration-resistant prostate cancer (mCRPC) patients with or without the ineligible factors of the COU-AA-302 study (presence of visceral metastases, symptomatic disease, and/or Eastern Cooperative Oncology Group performance status ≥ 2).

Materials and methods

The clinical records of chemo-naïve mCRPC patients who received AA in six public oncology centers or T in two of these centers between 2003 and 2014 were reviewed. The survival time was compared among four subgroups of patients: those with ineligible factors administered AA (Group Ineligible–AA) or T (Group Ineligible–T), and those without ineligible factors and administered AA (Group Eligible–AA) or T (Group Eligible–T).

Results

During the study period, we identified 115 mCRPC patients who received AA or T, among whom 29, 36, 29, and 21 patients were classified as Groups Ineligible–AA, Ineligible–T, Eligible–AA, and Eligible–T, respectively. Both Group Ineligible–AA and Group Eligible–AA had significantly longer progression-free survival (PFS) and similar overall survival (OS) as Group Ineligible–T and Group Eligible–T (Ineligible, PFS: 6.3 vs. 5.9 months, P = 0.0234, OS: 7.8 vs. 15.7 months, P = 0.1601; Eligible, PFS: 9.8 vs. 5.6 months, P = 0.0437, OS: 20.5 vs. 18.2 months, P = 0.7820).

Conclusions

Compared to T, AA treatment resulted in longer PFS and similar OS in chemo-naïve mCRPC patients, irrespective of the presence of ineligible factors, suggesting that the initial treatment by AA may still be beneficial to those with the aforementioned ineligible factors.

Management of metastatic castration-resistant prostate cancer: Insights from urology experts in Thailand

Treatment options for castration-resistant prostate cancer (CRPC) are available, but clear instructions for the selection of appropriate treatment are lacking. A meeting of urology experts based in Thailand was convened with the following objectives: (1) to reach a consensus and share real-life experiences about how to identify CRPC; (2) to choose the appropriate treatment for CRPC patients; (3) to evaluate disease progression using novel inhibitors of the androgen receptor pathway; (4) to identify the frequency of monitoring disease; and (5) to promote rational use of corticosteroids in CRPC patients. This consensus document can provide guidance to other urologists in Thailand to provide appropriate treatment to metastatic CRPC patients in a timely manner.

Indirect comparison between abiraterone acetate and enzalutamide for the treatment of metastatic castration-resistant prostate cancer: a systematic review

This study was designed to evaluate the efficacy, tolerability, and sequential administration of abiraterone acetate (AA) and enzalutamide (Enz) for metastatic castration-resistant prostate cancer (mCRPC). A literature search was performed with PubMed, Embase, and Web of Science databases to identify relevant studies. Reviewed literature included published phase III trials of AA or Enz in mCRPC and studies regarding their sequential administration. Given the difference in control arms in AA (active comparator) and Enz (true placebo) randomized phase III studies, indirect comparisons between AA and Enz in mCRPC showed no statistically significant difference in overall survival in prechemotherapy and postchemotherapy settings (HR: 0.90, 95% CI, 0.73-1.11; HR: 0.85, 95% CI, 0.68-1.07). Compared with AA, Enz may better outperform control arms in treating mCRPC both before and after chemotherapy regarding secondary endpoints based on indirect comparisons: time to prostate-specific antigen (PSA) progression (HR: 0.34, 95% CI, 0.28-0.42; HR: 0.40, 95% CI, 0.30-0.53), radiographic progression-free survival (HR: 0.37, 95% CI, 0.28-0.48; HR: 0.61, 95% CI, 0.50-0.74), and PSA response rate (OR: 18.29, 95% CI, 11.20-29.88; OR: 10.69, 95% CI, 3.92-29.20). With regard to the effectiveness of Enz following AA or AA following Enz, recent retrospective case series reported overall survival and secondary endpoints for patients with mCRPC progression after chemotherapy. However, confirmatory head-to-head trials are necessary to determine the optimal sequencing of these agents.

A new model of multi-visceral and bone metastatic prostate cancer with perivascular niche targeting by a novel endothelial specific adenoviral vector

While modern therapies for metastatic prostate cancer (PCa) have improved survival they are associated with an increasingly prevalent entity, aggressive variant PCa (AVPCa), lacking androgen receptor (AR) expression, enriched for cancer stem cells (CSCs), and evidencing epithelial-mesenchymal plasticity with a varying extent of neuroendocrine transdifferentiation. Parallel work revealed that endothelial cells (ECs) create a perivascular CSC niche mediated by juxtacrine and membrane tethered signaling. There is increasing interest in pharmacological metastatic niche targeting, however, targeted access has been impossible. Here, we discovered that the Gleason 7 derived, androgen receptor negative, IGR-CaP1 cell line possessed some but not all of the molecular features of AVPCa. Intracardiac injection into NOD/SCID/IL2Rg -/- (NSG) mice produced a completely penetrant bone, liver, adrenal, and brain metastatic phenotype; noninvasively and histologically detectable at 2 weeks, and necessitating sacrifice 4-5 weeks post injection. Bone metastases were osteoblastic, and osteolytic. IGR-CaP1 cells expressed the neuroendocrine marker synaptophysin, near equivalent levels of vimentin and e-cadherin, all of the EMT transcription factors, and activation of NOTCH and WNT pathways. In parallel, we created a new triple-targeted adenoviral vector containing a fiber knob RGD peptide, a hexon mutation, and an EC specific ROBO4 promoter (Ad.RGD.H5/3.ROBO4). This vector was expressed in metastatic microvessels tightly juxtaposed to IGR-CaP1 cells in bone and visceral niches. Thus, the combination of IGR-CaP1 cells and NSG mice produces a completely penetrant metastatic PCa model emulating end-stage human disease. In addition, the metastatic niche access provided by our novel Ad vector could be therapeutically leveraged for future disease control or cure.

Gallium-68 Prostate-Specific Membrane Antigen PET Imaging

The role of gallium-68 (⁶⁸Ga) prostate-specific membrane antigen (PSMA) PET imaging is evolving and finding its place in the imaging armamentarium for prostate cancer (PCa). Despite the progress of conventional imaging strategies, significant limitations remain, including identification of small-volume disease and assessment of bone. Clinical studies have demonstrated that ⁶⁸Ga-PSMA is a promising tracer for detection of PCa metastases, even in patients with low prostate-specific antigen. To provide an accurate interpretation of ⁶⁸Ga-PSMA PET/computed tomography, nuclear medicine specialists and radiologists should be familiar with physiologic ⁶⁸Ga-PSMA uptake, common variants, patterns of locoregional and distant spread of PCa, and inherent pitfalls.

Enzalutamide in castration-resistant prostate cancer patients with visceral disease in the liver and/or lung: Outcomes from the randomized controlled phase 3 AFFIRM trial

BACKGROUND

Patients with metastatic castration-resistant prostate cancer (mCRPC) and visceral metastases have a worse prognosis than those with nonvisceral metastases. Treatment with the androgen receptor inhibitor enzalutamide in the phase 3 AFFIRM trial led to significant improvements in outcomes for patients with mCRPC. For the current report, the authors analyzed the efficacy of enzalutamide among patients from the AFFIRM trial who had visceral disease.

METHODS

Patients who had liver and/or lung metastases at baseline were selected for prespecified overall survival (OS) and exploratory post hoc analyses, including prostate-specific antigen (PSA) response and the time to PSA and radiographic progression.

RESULTS

In patients who had liver metastases (n = 92), enzalutamide was associated with a lower risk of radiographic progression (hazard ratio [HR], 0.645; 95% confidence interval [CI], 0.413-1.008), improved 12-month OS (37.7% vs 20.6%) and radiographic progression-free survival (rPFS) (11.6% vs 3.0%) rates, and higher PSA response rates (35.1% vs 4.8%) compared with placebo. Enzalutamide-treated patients who had lung metastases (n = 104) had improved median OS (HR, 0.848; 95% CI, 0.510-1.410), a substantially reduced risk of radiographic progression (HR, 0.386; 95% CI, 0.259-0.577), improved 12-month OS (65.1% vs 55.3%) and rPFS (30.9% vs 8.2%) rates, increased time to PSA progression (HR, 0.358; 95% CI, 0.204-0.627), and a better PSA response rate (52.1% vs 4.9%) compared with those who received placebo. No increase in treatment-related adverse events was observed for the visceral metastases cohort compared with the nonvisceral metastases cohort.

CONCLUSIONS

Across multiple endpoints, patients who have visceral metastases have better outcomes with enzalutamide than with placebo. Cancer 2017;123:253-262. © 2016 American Cancer Society.

Abiraterone for castration-resistant prostate cancer: adherence, survival and hospitalization : Analysis of a medical claims database

Objective

To analyze the drug adherence rates and overall survival for in patients treated with arbiraterone acetate (AA) for castration-resistant prostate cancer (CRPC).

Methods

The database of the largest insurance company in Austria (Wiener Gebietskrankenkasse) was analyzed. Data on all CRPC patients with at least one prescription of AA between November 2011 and December 2014 in the postchemotherapy setting were collated and compared to the Austrian death and hospital admission statistics. Drug adherence was estimated by the medication possession ratio (MPR).

Results

Data of 270 patients (mean age 73.5 ± 8.9 years) were analyzed. The mean duration of AA treatment was 9.8 months (range 1–38 months). The duration of AA treatment was as follows: 0–2 months 53 patients (19.6 %), 3–5 months 73 patients (28.1 %), 6–10 months 67 patients (24.8 %) and >10 months 97 patients (35.9 %). The median MPR was 100 % and in 241 (89.2 %) the MPR exceeded ≥80 %. The median overall survival (OS) was 11 months. Based on Kaplan-Meier analysis, the 6 month OS was 61 %, 12 month OS 43 %, 18 month OS 35 % and >24 month OS 24 %. The OS was strongly correlated to patient age and the duration of AA treatment. Of all 270 patients, only 19 (7 %) were not hospitalized during their remaining life span and 71 (26.2 %) spent more than 50% of their remaining life span in hospital care.

Conclusion

The OS was shorter than in phase III trials and strongly correlated to patient age and the duration of AA treatment. The high mortality rate within the first 6 months of AA treatment in this real-life setting suggests a less stringent patient selection than in a phase III trial.

In Men with Castration-Resistant Prostate Cancer, Visceral Metastases Predict Shorter Overall Survival: What Predicts Visceral Metastases? Results from the SEARCH Database

BACKGROUND

Although visceral metastases (VMs) are widely recognized to portend worse prognoses compared with bone and lymph metastases in men with metastatic castration-resistant prostate cancer (mCRPC), little is known about what predicts VMs and the extent to which men with VMs do worse.

OBJECTIVE

To determine whether men with VMs at initial mCRPC diagnosis have worse overall survival (OS) and identify predictors of VMs.

DESIGN, SETTING, AND PARTICIPANTS

We analyzed 494 men diagnosed with castration-resistant prostate cancer post-1999 and no known metastases from five Veterans Affairs hospitals of the Shared Equal Access Regional Cancer Hospital (SEARCH) database who later developed metastases. Radiology scans within 30 d of initial metastasis diagnosis were reviewed to collect information on bone, visceral, and lymph node metastases. We analyzed the 236 men who had a computed tomography scan performed.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Predictors of VMs and OS were evaluated using logistic regression and Cox models, respectively.

RESULTS AND LIMITATIONS

Of the 236 mCRPC patients, 38 (16%) had VMs. Regarding VMs, 19 patients (50%), 8 patients (21%), and 16 patients (42%) had metastases in the liver, lungs, and other locations, respectively. VMs were a predictor of OS on crude analysis (hazard ratio [HR]: 1.88; 95% confidence interval [CI], 1.30-2.72; p=0.001) and after risk adjustment (HR: 1.84; 95% CI, 1.24-2.72; p=0.002). Age, year, treatment center, prostate-specific antigen (PSA), and time from CRPC to metastases were significant in predicting OS (all p<0.05). None of the variables tested were associated with having VMs (all p > 0.09). Prospective studies and larger cohorts are needed to validate our findings.

CONCLUSIONS

Demographic, tumor, and PSA kinetic characteristics were not predictive of having VMs, but VMs predicted worse OS.

PATIENT SUMMARY

Because patients with VMs have worse overall survival, further research is needed to develop better biomarkers and thus diagnose those with VMs at earlier stages in their disease course.

Liver metastatic disease: new concepts and biomarker panels to improve individual outcomes

Liver cancer, one of the leading causes of all cancer related deaths, belongs to the most malignant cancer types. In fact, the secondary hepatic malignancies (liver metastases) are more common than the primary ones. Almost all solid malignancies can metastasise to the liver. It is well justified that the "treat and wait" approach in the overall management of the liver cancer is not up-to-date and so creation of complex individual patient profiles is needed. This review is specifically focused on the liver metastases originating from the colorectum, breast and prostate cancer. Innovative multilevel diagnostics may procure specific panels of validated biomarkers for predisposition, development and progression of metastatic disease. Creation of the patient specific "molecular portrait" is an essential part of the diagnostic strategy. Contextually, analysis of molecular and cellular patterns in blood samples as the minimally invasive diagnostic tool and construction of diagnostic windows based on individual patient profiling is highly recommended for patient cohorts predisposed to and affected by the liver metastatic disease. Summarised information on risk assessment, predictive and prognostic panels for diagnosis and treatments of the liver metastatic disease in colorectal, breast and prostate cancer is provided.

An imaging agent to detect androgen receptor and its active splice variants in prostate cancer

Constitutively active splice variants of androgen receptor (AR-Vs) lacking ligand-binding domain (LBD) are a mechanism of resistance to androgen receptor LBD-targeted (AR LBD-targeted) therapies for metastatic castration-resistant prostate cancer (CRPC). There is a strong unmet clinical need to identify prostate cancer patients with AR-V-positive lesions to determine whether they will benefit from further AR LBD-targeting therapies or should receive taxanes or investigational drugs like EPI-506 or galeterone. Both EPI-506 (NCT02606123) and galeterone (NCT02438007) are in clinical trials and are proposed to have efficacy against lesions that are positive for AR-Vs. AR activation function-1 (AF-1) is common to the N-terminal domains of full-length AR and AR-Vs. Here, we provide proof of concept for developing imaging compounds that directly bind AR AF-1 to detect both AR-Vs and full-length AR. ¹²³I-EPI-002 had specific binding to AR AF-1, which enabled direct visualization of CRPC xenografts that express full-length AR and AR-Vs. Our findings highlight the potential of ¹²³I-EPI-002 as an imaging agent for the detection of full-length AR and AR-Vs in CRPC.

GRK3 is a direct target of CREB activation and regulates neuroendocrine differentiation of prostate cancer cells

Neuroendocrine prostate cancer (NEPC) is an aggressive subtype of prostate cancer that commonly arises through neuroendocrine differentiation (NED) of prostate adenocarcinoma (PAC) after therapy, such as radiation therapy and androgen deprivation treatment (ADT). No effective therapeutic is available for NEPC and its molecular mechanisms remain poorly understood. We have reported that G protein-coupled receptor kinase 3 (GRK3, also called ADRBK2) promotes prostate cancer progression. In this study, we demonstrate that the ADT-activated cAMP response element binding protein (CREB) directly targets and induces GRK3. We show GRK3 expression is higher in NEPC than in PAC cells and mouse models, and it positively correlates with the expression and activity of CREB in human prostate cancers. Notably, overexpression of GRK3 in PAC cells increased the expression of NE markers in a kinase activity dependent manner. Conversely, silencing GRK3 blocked CREB-induced NED in PAC cells, reversed NE phenotypes and inhibited proliferation of NEPC cells. Taken together, these results indicate that GRK3 is a new critical activator of NE phenotypes and mediator of CREB activation in promoting NED of prostate cancer cells.

Factors predicting efficacy and adverse effects of enzalutamide in Japanese patients with castration-resistant prostate cancer: results of retrospective multi-institutional study

BACKGROUND

We aimed to evaluate the factors predicting efficacy and adverse effects of enzalutamide in patients with castration-resistant prostate cancer.

METHODS

We retrospectively evaluated data on 345 patients who had received enzalutamide for castration-resistant prostate cancer in 20 hospitals (Kyoto University Hospital and other satellite hospitals). Cox proportional hazards regression analysis was performed to identify factors predicting prostate-specific antigen (PSA) progression after enzalutamide treatment and logistic regression analysis for those associated with development of adverse effects.

RESULTS

PSA titers decreased by >50 % in 197 patients (57 %). The median PSA progression free survival was 163 days. Gleason score >8 (HR 2.078, 95 % CI 1.37-3.153, P = 0.00058), performance status ≥1 (HR 2.292, 95 % CI 1.463-3.592, P = 0.000296), presence of bone metastasis (HR 1.774, 95 % CI 1.019-3.090, P = 0.0429), visceral metastasis (HR 2.127, 95 % CI 1.215-3.722, P = 0.00823), previous steroid treatment (HR 1.780, 95 % CI 1.207-2.626, P = 0.00361) and docetaxel treatment (HR 1.602, 95 % CI 1.051-2.442, P = 0.0284) significantly predicted the efficacy of enzalutamide. Adverse effects, including fatigue or appetite loss, occurred in 169 patients (49 %), 48 (18 %) of whom stopped enzalutamide. Age >75 years (HR 1.980, 95 % CI 1.270-3.09, P = 0.00246) and lower enzalutamide dose (HR 0.437, 95 % CI 0.255-1.270, P = 0.00249) were significantly associated with development of adverse effects.

CONCLUSIONS

Enzalutamide treatment is effective in patients with castration-resistant prostate cancer with low Gleason scores, good performance status, without bone or visceral metastasis and no prior steroid or docetaxel treatment. Lower doses of enzalutamide decrease the incidence of adverse effects, especially in older patients.

Abiraterone acetate in metastatic castration-resistant prostate cancer - the unanticipated real-world clinical experience

Background

There is much interest in confirming whether the efficacy of abiraterone acetate (AA) demonstrated within the trial setting is reproducible in routine clinical practice. We report the clinical outcome of metastatic castration-resistant prostate cancer (mCRPC) patients treated with AA in real-life clinical practice.

Methods

The clinical records of mCRPC patients treated with AA from all 6 public oncology centers in Hong Kong between August 2011 and December 2014 were reviewed. The treatment efficacy and its determinants, and toxicities were determined.

Results

A total of 110 patients with mCRPC were treated with AA in the review period, of whom 58 were chemo-naive and 52 had received prior chemotherapy (post-chemo). The median follow-up time was 7.5/11.4 months for chemo-naive/post-chemo patients. 6.9/15.4 % of chemo-naive/post-chemo patients had visceral metastases. The median overall survival (OS) and progression-free survival (PFS) were 18.1/15.5 months and 6.7/6.4 months for chemo-naive/post-chemo patients, respectively. Among chemo-naive patients, those with visceral diseases had significantly inferior OS (2.8 vs 18.0 p = 0.0007) and PFS (2.8 vs 6.8 months, p = 0.0088) than those without. Pain control was comparable in both groups of patients. The most common grade 3 or above toxicities were hypertension (6.9/5.8 %) and hypokalemia (3.4/3.8 %) in chemo-naive/post-chemo patients. In multivariate analysis, the presence of prostate-specific antigen (PSA) response (≥50 % drop of PSA from baseline) within the first 3 months of therapy was associated with favorable OS and PFS in both chemo-naive and post-chemo group.

Conclusions

In clinical practice outside the trial setting, OS after AA in our chemo-naive patient cohort (18.1 months) was considerably shorter than that reported in the COU-AA-302 trial (34.7 months), and the OS was particularly short in those with visceral metastases (2.8 months). Conversely, AA was efficacious in post-chemo patients. AA resulted in comparable pain control in both groups of patients. The presence of PSA response within the first 3 months of treatment was a significant determinant of survival.

Does Gleason score at initial diagnosis predict efficacy of abiraterone acetate therapy in patients with metastatic castration-resistant prostate cancer? An analysis of abiraterone acetate phase III trials

BACKGROUND

The usefulness of Gleason score (<8 or ≥8) at initial diagnosis as a predictive marker of response to abiraterone acetate (AA) plus prednisone in patients with metastatic castration-resistant prostate cancer (mCRPC) was explored retrospectively.

PATIENTS AND METHODS

Initial diagnosis Gleason score was obtained in 1048 of 1195 (COU-AA-301, post-docetaxel) and 996 of 1088 (COU-AA-302, chemotherapy-naïve) patients treated with AA 1 g plus prednisone 5 mg twice daily by mouth or placebo plus prednisone. Efficacy end points included radiographic progression-free survival (rPFS) and overall survival (OS). Distributions and medians were estimated by Kaplan-Meier method and hazard ratio (HR) and 95% confidence interval (CI) by Cox model.

RESULTS

Baseline characteristics were similar across studies and treatment groups. Regardless of Gleason score, AA treatment significantly improved rPFS in post-docetaxel [Gleason score <8: median, 6.4 versus 5.5 months (HR = 0.70; 95% CI 0.56-0.86), P = 0.0009 and Gleason score ≥8: median, 5.6 versus 2.9 months (HR = 0.58; 95% CI 0.48-0.72), P < 0.0001] and chemotherapy-naïve patients [Gleason score <8: median, 16.5 versus 8.2 months (HR = 0.50; 95% CI 0.40-0.62), P < 0.0001 and Gleason score ≥8: median, 13.8 versus 8.2 months (HR = 0.61; 95% CI 0.49-0.76), P < 0.0001]. Clinical benefit of AA treatment was also observed for OS, prostate-specific antigen (PSA) response, objective response and time to PSA progression across studies and Gleason score subgroups.

CONCLUSION

OS and rPFS trends demonstrate AA treatment benefit in patients with pre- or post-chemotherapy mCRPC regardless of Gleason score at initial diagnosis. The initial diagnostic Gleason score in patients with mCRPC should not be considered in the decision to treat with AA, as tumour metastases may no longer reflect the histology at the time of diagnosis.

CLINICAL TRIALS NUMBER

COU-AA-301 (NCT00638690); COU-AA-302 (NCT00887198).

68Ga-PSMA-HBED-CC PET for Differential Diagnosis of Suggestive Lung Lesions in Patients with Prostate Cancer

In prostate cancer (PC) patients, the differentiation between lung metastases and lesions of different origin, for example, primary lung cancer, is a common clinical question. Herein, we investigated the use of Glu-NH-CO-NH-Lys(Ahx)-HBED-CC ((68)Ga-PSMA-HBED-CC) for this purpose.

METHODS

PC patients (n = 1,889) undergoing (68)Ga-PSMA PET/CT or PET/MR scans were evaluated retrospectively for suggestive lung lesions. For up to 5 lesions per patient, location, CT diameter, CT morphology, and SUVmax were determined. The standard for classification was either histopathologic evaluation or, in the case of PC metastases, responsivity to antihormone therapy. A comparison of the different classes was executed by Student t test. Prostate-specific antigen and prostate-specific membrane antigen (PSMA) immunohistochemistry were performed if histologic samples were available; (68)Ga-PSMA autoradiography was performed on an exemplary case of PET-positive lung cancer.

RESULTS

Eighty-nine lesions in 45 patients were identified, of which 76 were classified as PC (39 proven, 37 highly probable), 7 as primary lung cancer, and 2 as activated tuberculosis; 4 lesions remained unclear. The mean SUVmax was 4.4 ± 3.9 for PC metastases and 5.6 ± 1.6 for primary lung cancer (P = 0.408). Additionally, substantial differences in SUVmax intraindividually were detected. The 2 tuberculous lesions showed an SUVmax of 7.8 and 2.5. Using immunohistochemistry, we could demonstrate PSMA expression in the neovasculature of several PSMA PET-positive lung cancers as well as in tuberculous lesions from our histologic database.

CONCLUSION

Quantitative (SUV) analysis of (68)Ga-PSMA PET was not able to discriminate reliably between pulmonary metastases and primary lung cancer in PC patients. The reason for the unexpectedly high tracer uptake in non-PC lesions is not completely clear. PSMA expression in neovasculature provides a possible explanation for this finding; however, other contributing factors, such as tracer binding to proteins other than PSMA, cannot be excluded at present.

Abiraterone in the management of castration-resistant prostate cancer prior to chemotherapy

The treatment armamentarium for metastatic castration-resistant prostate cancer (mCRPC) has increased significantly over the past several years. Approved drugs associated with improved survival include androgen pathway-targeted agents (abiraterone acetate and enzalutamide), chemotherapeutics (docetaxel and cabazitaxel), an autologous vaccine (sipuleucel-T) and a radiopharmaceutical (radium-223). Abiraterone acetate, a prodrug of abiraterone, inhibits the CYP17A enzyme, a critical enzyme in androgen biosynthesis. Abiraterone has regulatory approval in mCRPC in both chemotherapy-naïve patients and in the post-docetaxel setting based on results from two randomized phase III studies. In the COU-AA-302 trial, abiraterone demonstrated significant improvement in the coprimary endpoints of radiographic progression-free survival and overall survival, as well as in a number of secondary endpoints including time until initiation of chemotherapy, time until opiate use for cancer-related pain, prostate-specific antigen progression-free survival and decline in performance status. Abiraterone is well-tolerated, although adverse events associated with this agent include abnormalities in liver function testing and mineralocorticoid-associated adverse events. This review evaluates the use of abiraterone in mCRPC prior to the use of chemotherapy.

Impact of visceral metastases on outcome to abiraterone after docetaxel in castration-resistant prostate cancer patients

BACKGROUND

The objective of this study was to analyze the impact of visceral metastases in castration-resistant prostate cancer (CRPC) treated with abiraterone.

MATERIALS & METHODS

All CRPC patients received abiraterone 1000 mg daily plus prednisone 10 mg orally daily. Liver and lung metastases were considered as visceral metastases.

RESULTS

Of 265 CRPC patients, 49 had visceral metastases. Results on progression-free survival were not significantly different in patients with or without visceral metastases. Conversely, the median overall survival between the two groups was 12.4 and 18.5 months (p = 0.01), respectively, and median overall survival of patients with liver-only disease versus other sites was 10.5 versus 18.5 months (p = 0.006), respectively.

CONCLUSION

Visceral disease appears to be an important predictor of clinical outcome in CRPC patients treated with abiraterone.

Treating Patients with Metastatic Castration Resistant Prostate Cancer: A Comprehensive Review of Available Therapies

PURPOSE

The availability of newly approved treatment options for metastatic castration resistant prostate cancer is not matched with conclusive data on optimal sequencing strategies and resistance patterns. A comprehensive review of efficacy and safety data for new agents and current knowledge regarding treatment sequencing would enable treating physicians to make rational drug selections in patients with metastatic castration resistant prostate cancer.

MATERIALS AND METHODS

We searched MEDLINE® and relevant congresses for data on cabazitaxel, docetaxel, 223radium dichloride, abiraterone, enzalutamide and sipuleucel-T, focusing on sequencing strategies, resistance mechanisms and biomarkers of response.

RESULTS

Abiraterone and enzalutamide target the androgen axis with different mechanisms of action. Abiraterone blocks cytochrome P450 17, inhibiting androgen synthesis, whereas enzalutamide inhibits androgen receptor, reducing nuclear translocation of the androgen receptor complex and subsequent DNA binding. Both agents provide improved overall survival in patients with metastatic castration resistant prostate cancer who received prior docetaxel treatment and in those who are chemotherapy naïve. Cabazitaxel provides improved overall survival in patients with metastatic castration resistant prostate cancer with prior docetaxel therapy. Sipuleucel-T provides improved overall survival in asymptomatic patients and (223)radium provides improved overall survival in chemotherapy naïve and chemotherapy treated patients with symptomatic bone metastases. Selecting the correct treatment with metastatic castration resistant prostate cancer is complex as no head-to-head trials have been done and comparison between existing trials is difficult due to differences in study populations and a lack of validated biomarkers. Factors to consider include prior therapy, symptom burden, metastasis type, performance status, comorbidities, adverse event profiles and patient preference. Another consideration is treatment sequence since some agents affect responses to subsequent choices. For example, resistance to abiraterone or enzalutamide may result in limited responses to subsequent androgen targeted agents. Identifying factors predictive of resistance is an area of ongoing research with androgen receptor variants representing a good candidate. Prognostic factors for survival are also likely to be useful and are currently being studied.

CONCLUSIONS

New therapies for metastatic castration resistant prostate cancer have brought new challenges with regard to treatment selection and sequencing. While hormonal agents provide good therapeutic responses, resistance may be intrinsic without prior drug exposure. Identifying predictors of response and relevant biomarkers will allow therapies to be more precisely tailored to individual patient profiles.

Gastrointestinal metastases from prostate cancer: a review of the literature

ABSTRACT 

The availability of active new drugs for the treatment of advanced castration-resistant prostate cancer has significantly prolonged overall survival, thus changing the natural history of the disease and raising the likelihood of observing metastases in atypical sites. This review of the literature describes the frequency, clinical-pathological features and presenting symptoms of non-liver gastrointestinal metastases (GIm) from prostate cancer. Its purpose is to increase clinical awareness of the increasing incidence of such GIm, contributing to the early detection, accurate diagnosis and, when feasible, appropriate management.

Radium-223 dichloride: a new paradigm in the treatment of prostate cancer

Radionuclides have been widely used for cancer treatment. Recently, new research about radium-223 dichloride has been conducted in prostate cancer, which reveals that it is the first radiopharmaceutical to demonstrate an improvement in overall survival and time to first symptomatic skeletal event in patients with castration resistant prostate cancer with symptomatic bone metastases. This fact has created a new paradigm in the treatment of prostate cancer landscape, where only chemotherapy and hormone therapy had a role, while β-emitters had been confined exclusively to the role of pain relief with no impact on survival. The aim of this review is to outline current treatment approaches for advanced prostate cancer with a focus on the role of radium-223 dichloride, reviewing patients' profile that make them suitable to therapy and chances for further studies.

Parotid gland metastasis from prostate cancer: is docetaxel still the best treatment option?

Metastases of prostate cancer originating from the parotid gland are rare. However, this presentation raises the question of the management of visceral metastasis in castration-resistant prostate cancer. We report the case of an 87-year-old man who presented with a right painless parotid mass in the context of castration-resistant prostate cancer, indicating progression of the disease. He received medical treatment based on docetaxel. Here, we discuss the impact of new hormonotherapies such as enzalutamide and abiraterone acetate, which may be used for the management of these patients.

ECF chemotherapy for liver metastases due to castration-resistant prostate cancer

INTRODUCTION

Most men with metastatic castration-resistant prostate cancer (CRPC) have biochemical response to docetaxel, but the objective response rate is low. Liver metastases are uncommon with CRPC and associated with shorter survival. More active treatment might benefit these patients. Epirubicin, cisplatin and flurouracil (ECF) is a standard regimen for gastric cancer and response in CRPC liver metastases has been reported. We reviewed our experience with ECF in CRPC with the primary objective of determining its anti-tumour activity in patients with liver metastatic CRPC.

METHODS

Men with CRPC treated with ECF were identified from electronic databases and data were extracted from medical records. Men with tumours showing neuroendocrine features were excluded.

RESULTS

In total, we identified 14 CRPC patients treated with ECF were identified, of which 8 had liver metastases. The median age was 56 (range: 42-76) and all had multiple poor prognostic features. A median of 6 cycles of ECF were administered (range: 1-10) and toxicities were similar to previous reports. Of the 8 patients with liver metastases, 5 had partial remission.

CONCLUSIONS

ECF was highly active in this small selected group of younger men with liver metastases from CRPC and multiple poor prognostic features. Despite important limitations, this is the third report of high objective response rates with ECF in CRPC. Objective response rates are low with current monotherapies. A higher probability of ORR is preferred for critical organ disease, therefore the anti-tumour activity should encourage testing of ECF in comparison to the most active current therapies.

Visceral metastases and prostate cancer treatment: 'die hard,' 'tough neighborhoods,' or 'evil humors'?

Men with metastatic castration-resistant prostate cancer have multiple treatment options, and the expanding palate of available therapies renders careful patient selection imperative. Men with visceral (especially hepatic) metastases have a particularly poor prognosis, regardless of the treatment selected. Retrospective analyses of datasets from large phase III randomized trials showed that men with visceral metastases appear to derive clinical benefit from second-generation antiandrogens as well as from docetaxel chemotherapy, but not from immunotherapy. The mechanistic underpinnings of these observations are currently not clear, but could involve factors that are intrinsic to the tumor cell, the tumor microenvironment, and/or systemic factors. Regardless of the underlying mechanism(s), a better understanding of the basic biology of visceral vs bone metastases will be critical in improving prostate cancer treatment in the setting of advanced disease.

Bioclinical parameters driving decision-making of subsequent lines of treatment in metastatic castration-resistant prostate cancer

Different options are available as second-line treatment of metastatic castrate-resistant prostate cancer: cabazitaxel, abiraterone, and enzalutamide. Phase III studies evaluating cabazitaxel and the two hormonal agents have been shown to significantly prolong overall survival compared to mitoxantrone and placebo, respectively. Several studies have also demonstrated feasibility and activity of docetaxel rechallenge in case of a sufficient progression-free interval (3-6 months), good performance status, and previous acceptable safety profile, thus providing an additional treatment option in clinical practice. Clinical and biological parameters should be considered to tailor II line treatment. In clinical practice, we can primarily evaluate patients' fitness according to age, performance status, symptomatic disease, comorbidities, and expected safety profile of each drug. Different prognostic/predictive factors may be considered, such as presence of bone-limited or visceral metastases, length of androgen deprivation therapy (ADT) before chemotherapy, time to progression after docetaxel, Gleason score, PSA doubling time, and serum testosterone, even if their clinical relevance is still debated. This review will discuss current options of innovative drugs sequencing and selection according to bioclinical parameters.

Practical guide to the use of abiraterone in castration resistant prostate cancer

INTRODUCTION

While androgen deprivation therapy remains the primary treatment modality for patients with metastatic prostate cancer, treatment is uniformly marked by progression to castration resistant prostate cancer (CRPC). Abiraterone is the first new drug to enter clinical practice in a series of novel agents designed to potently target adrenal and tumor androgen production.

MATERIALS AND METHODS

Herein, we review the mechanism of action of abiraterone and the phase III data supporting its approval for patients with metastatic CRPC. We discuss practical treatment considerations, including the incidence and management of side effect and monitoring requirements, and conclude by discussing future directions in the use of abiraterone, including early data supporting an expanded role for abiraterone in castration sensitive disease.

RESULTS

Accumulating data emphasize that "androgen independent" or "hormone refractory" tumors remain sensitive to hormonal activation and suggest that despite suppression of circulating testosterone (T), residual tumor androgens play a prominent role in mediating CRPC progression.

CONCLUSIONS

Accordingly, therapeutic strategies such abiraterone that more effectively target production of intratumoral androgens are necessary.

Visceral disease in castration-resistant prostate cancer

Metastatic involvement of the viscera in men with advanced castration-resistant prostate cancer (CRPC) has been poorly characterised to date. In 359 CRPC patients treated between June 2003 and December 2011, the frequency of radiologically detected visceral metastases before death was 32%. Of the 92 patients with computed tomography performed within 3 mo of death, 49% had visceral metastases. Visceral metastases most commonly involved the liver (20%) and lung (13%). Median survival from diagnosis of visceral disease was 7.1 mo (95% confidence interval, 5.9-8.3). Survival was affected by the degree of bone involvement at detection of visceral disease, varying from 6.1 mo in men with more than six bone metastases to 18.2 mo in men with no bone metastases (p=0.001). Heterogeneity was noted in clinical phenotypes and prostate-specific antigen trends at development of visceral metastases. Visceral metastases are now more commonly detected in men with CRPC, likely due to the introduction of novel survival-prolonging treatments.