Management of Advanced Prostate Cancer After First-Line Chemotherapy

Functionalized PEG-PLA nanoparticles for brain targeted delivery of ketoconazole contribute to pregnane X receptor overexpressing in drug-resistant epilepsy

OBJECTIVE

To develop a functionalized PEG-PLA nanoparticle system containing ketoconazole (KCZ) to overcome the overactivity of pregnane X receptor (PXR) for the treatment of drug-resistant epilepsy (DRE).

SIGNIFICANCE

KCZ was developed as a therapy strategy for DRE limited by its lethal hepatotoxicity and minute brain concentration. KCZ-incorporated nanoparticles modified with angiopep-2 (NPs/KCZ) could reduce adverse effects of KCZ and achieve epileptic foci-targeted drug delivery.

METHODS

NPs/KCZ was prepared by thin-film hydration method and characterized in vitro and in vivo. The efficacy evaluation of NPs/KCZ was evaluated in a kainic acid (KA)-induced mice model of epilepsy with carbamazepine (CBZ) treatment.

RESULTS

The mean particle size and Zeta potential of NPs/KCZ were 17.84 ± 0.33 nm and - 2.28 ± 0.12 mV, respectively. The drug-loading (DL%) of KCZ in nanoparticles was 8.96 ± 0.12 % and the entrapment efficiency (EE%) was 98.56 ± 0.02 %. The critical value of critical micelle concentration was 10^-3.3 mg/ml. No obvious cytotoxicity was found in vitro. The behavioral and electrographic seizure activities were obviously attenuated in NPs/KCZ+CBZ group. The CBZ concentration of brain tissues in mice treated with NPs/KCZ+CBZ was significantly increased than those treated with CBZ alone (P = 0.0028). A significantly decreased expression level of PXR and its downstream proteins was observed in NPs/KCZ+CBZ group compared with that in the control and CBZ group (All P < 0.05).

CONCLUSION

Our results showed that NPs/KCZ achieved the epileptic foci-targeted delivery of KCZ and ameliorated the efficacy of CBZ on DRE by attenuating the overactivity of PXR.

Landmarks in prostate cancer

The field of prostate cancer has been the subject of extensive research that has resulted in important discoveries and shaped our appreciation of this disease and its management. Advances in our understanding of the epidemiology, natural history, anatomy, detection, diagnosis, grading, staging, imaging, and management of prostate cancer have changed clinical practice and influenced guideline recommendations. The development of the Gleason score and subsequent modifications enabled accurate prediction of prognosis. Increased anatomical understanding and improved surgical techniques resulted in the development of nerve-sparing surgery for radical prostatectomy. The advent of active surveillance has changed the management of low-risk disease, and chemotherapy and hormonal therapy have improved the outcomes of patients with distant disease. Ongoing research and clinical trials are expected to yield more practice-changing results in the near future.

Custirsen (OGX-011) combined with cabazitaxel and prednisone versus cabazitaxel and prednisone alone in patients with metastatic castration-resistant prostate cancer previously treated with docetaxel (AFFINITY): a randomised, open-label, international, phase 3 trial

BACKGROUND

Docetaxel and cabazitaxel improve overall survival compared with mitoxantrone in patients with metastatic castration-resistant prostate cancer. Custirsen (OGX011) is a second generation highly specific antisense oligonucleotide that inhibits the production of clusterin, an antiapoptotic protein that is upregulated in response to chemotherapy and that confers treatment resistance. We aimed to assess whether custirsen in combination with cabazitaxel and prednisone increases overall survival in patients with metastatic castration-resistant prostate cancer previously treated with docetaxel.

METHODS

In this randomised, open-label, international, phase 3 trial, men with radiographically documented metastatic castration-resistant prostate cancer that had progressed after docetaxel treatment with a Karnofsky performance status of more than 70% and who were fit for chemotherapy, were recruited from 95 cancer treatment centres in eight countries. Patients were randomly assigned (1:1) centrally using permuted blocks (block size 8) to receive cabazitaxel plus prednisone (cabazitaxel 25 mg/m² intravenously every 21 days plus oral prednisone 10 mg daily) with or without custirsen (640 mg intravenously on days 1, 8, and 15, plus three previous loading doses) until disease progression, unacceptable toxicity, or the completion of ten treatment cycles. Randomisation was stratified by use of opioids for prostate cancer-related pain at screening, disease progression following first-line docetaxel treatment established by radiographic evidence, and previous treatment with abiraterone or enzalutamide. The co-primary endpoints were overall survival in all randomly assigned patients and in a poor-prognosis subgroup. All analyses were intention to treat with the exception of safety, which was reported for patients who received any assigned treatment. The trial has been completed and the results presented here are the final analysis. This trial is registered with Clinicaltrials.gov, number NCT01578655.

FINDINGS

Between Sept 9, 2012, and Sept 29, 2014, 795 patients were screened for enrolment. 635 men were eligible for inclusion and were randomly assigned (n=317 in the cabazitaxel and prednisone plus custirsen group and n=318 in the cabazitaxel and prednisone group). Median follow up was 28·3 months (IQR 24·4-34·5) for the custirsen group and 29·8 months (IQR 25·3-35·2) for the control group. Median overall survival in all randomly assigned patients did not differ between the two groups (14·1 months [95% CI 12·7-15·9] in the curtisen group vs 13·4 months [12·1-14·9] in the control group; hazard ratio [HR] 0·95 [95% CI 0·80-1·12]; log-rank p=0·53). In the poor prognosis subgroup, median overall survival also did not differ between the two treatment groups (11·0 months [95% CI 9·3-13·3] in the custursin group vs 10·9 months [8·2-12·4] in the control group; HR 0·97 [95% CI 0·80-1·21]; two-sided p=0·80). The most frequently reported grade 3 or worse adverse events in the custirsen versus control groups were neutropenia (70 [22%] of 315 vs 61 [20%] of 312), anaemia (68 [22%] vs 49 [16%]), fatigue (23 [7%] vs 18 [6%]), asthenia (16 [5%] vs 8 [3%]), bone pain (16 [5%] vs 5 [2%]), and febrile neutropenia (16 [5%] vs 9 [3%]). Serious adverse events were reported in 155 (49%) versus 132 (42%). 27 patients died within 30 days of treatment in the cabazitaxel and prednisone plus custirsen group, seven of which were deemed to be treatment related, versus 17 in the cabazitaxel and prednisone group, eight of which were deemed to be treatment related. Of the 21 deaths reported, 15 were reported as complications related to study treatment, either chemotherapy (eight and three, respectively) or study drug (none and four, respectively).

INTERPRETATION

We noted no survival benefit in men with metastatic castration-resistant prostate cancer with the addition of custirsen to cabazitaxel and prednisone treatment. Cabazitaxel and prednisone remains the standard of care for patients with metastatic castration-resistant prostate cancer progressing after docetaxel chemotherapy.

FUNDING

OncoGenex Pharmaceuticals.

Knockdown of prostaglandin reductase 1 (PTGR1) suppresses prostate cancer cell proliferation by inducing cell cycle arrest and apoptosis

Chemoresistance is a serious problem for the treatment of androgen-independent prostate cancer (PC). The underlying molecular mechanisms by which androgen-independent PC cells acquire the capacity to proliferate remain largely unclear. The aim of this study was to investigate the biological role of prostaglandin reductase 1 (PTGR1) in prostate cancer. Data from the Oncomine database showed that PTGR1 is commonly upregulated in PC tissue in comparison to corresponding normal controls. Two PTGR1-specific short hairpin RNA (shRNA) sequences were used to block the expression of PTGR1 via a lentivirus-mediated system in the androgen-independent PC cell lines DU145 and PC 3. Functional analysis revealed that knockdown of PTGR1 significantly inhibited proliferation and colony formation by PC cells. The inhibition of cell proliferation was related to arrest of the cell cycle in the G0/G1 phase and increased apoptosis in response to PTGR1 knockdown as indicated by flow cytometry. PTGR1 silencing was found to mechanically enhance the expression of p21, caspase 3, and cleaved PARP and to decrease the level of cyclin D1. In conclusion, PTGR1 plays an essential role in PC cells and may be a potential therapeutic target for PC.

Outcome modeling techniques for prostate cancer radiotherapy: Data, models, and validation

Prostate cancer is a frequently diagnosed malignancy worldwide and radiation therapy is a first-line approach in treating localized as well as locally advanced cases. The limiting factor in modern radiotherapy regimens is dose to normal structures, an excess of which can lead to aberrant radiation-induced toxicities. Conversely, dose reduction to spare adjacent normal structures risks underdosing target volumes and compromising local control. As a result, efforts aimed at predicting the effects of radiotherapy could invaluably optimize patient treatments by mitigating such toxicities and simultaneously maximizing biochemical control. In this work, we review the types of data, frameworks and techniques used for prostate radiotherapy outcome modeling. Consideration is given to clinical and dose-volume metrics, such as those amassed by the QUANTEC initiative, and also to newer methods for the integration of biological and genetic factors to improve prediction performance. We furthermore highlight trends in machine learning that may help to elucidate the complex pathophysiological mechanisms of tumor control and radiation-induced normal tissue side effects.

Afzelin exhibits anti-cancer activity against androgen-sensitive LNCaP and androgen-independent PC-3 prostate cancer cells through the inhibition of LIM domain kinase 1

Prostate cancer presents high occurrence worldwide. Medicinal plants are a major source of novel and potentially therapeutic molecules; therefore, the aim of the present study was to investigate the possible anti-prostate cancer activity of afzelin, a flavonol glycoside that was previously isolated from Nymphaea odorata. The effect of afzelin on the proliferation of androgen-sensitive LNCaP and androgen-independent PC-3 cells was evaluated by performing a water soluble tetrazolium salt-1 assay. In addition, the effect of afzelin on the cell cycle of the LNCaP and PC-3 prostate cancer cell lines was evaluated. Western blot analysis was performed to evaluate the effect of afzelin on the kinases responsible for the regulation of actin organization. Afzelin was identified to inhibit the proliferation of LNCaP and PC3 cells, and block the cell cycle in the G₀ phase. The anticancer activity of afzelin in these cells was determined to be due to inhibition of LIM domain kinase 1 expression. Thus, the in vitro efficacy of afzelin against prostate cancer is promising; however, additional studies on different animal models are required to substantiate its anticancer potential.

Androgen Receptor Targeted Conjugate for Bimodal Photodynamic Therapy of Prostate Cancer in Vitro

Prostate cancer (PC) represents the most common type of cancer among males and is the second leading cause of cancer death in men in Western society. Current options for PC therapy remain unsatisfactory, since they often produce uncomfortable long-term side effects, such as impotence (70%) and incontinence (5-20%) even in the first stages of the disease. Light-triggered therapies, such as photodynamic therapy, have the potential to provide important advances in the treatment of localized and partially metastasized prostate cancer. We have designed a novel molecular conjugate (DR2) constituted of a photosensitizer (pheophorbide a, Pba), connected to a nonsteroidal anti-androgen molecule through a small pegylated linker. This study aims at investigating whether DR2 represents a valuable approach for PC treatment based on light-induced production of single oxygen and nitric oxide (NO) in vitro. Besides being able to efficiently bind the androgen receptor (AR), the 2-trifluoromethylnitrobenzene ring on the DR2 backbone is able to release cytotoxic NO under the exclusive control of light, thus augmenting the general photodynamic effect. Although DR2 is similarly internalized in cells expressing different levels of androgen receptor, the AR ligand prevents its efflux through the ABCG2-pump. In vitro phototoxicity experiments demonstrated the ability of DR2 to kill cancer cells more efficiently than Pba, while no dark toxicity was observed. Overall, the presented approach is very promising for further development of AR-photosensitizer conjugates in the multimodal photodynamic treatment of prostate cancer.

AR function in promoting metastatic prostate cancer

Prostate cancer (PCa) remains a leading cause of cancer-related death in the USA. While localized lesions are effectively treated through radical prostatectomy and/or radiation therapy, treatment for metastatic disease leverages the addiction of these tumors on the androgen receptor (AR) signaling axis for growth and disease progression. Though initially effective, tumors resistant to AR-directed therapeutics ultimately arise (a stage of the disease known as castration-resistant prostate cancer) and are responsible for PCa-specific mortality. Importantly, an abundance of clinical and preclinical evidence strongly implicates AR signaling cascades in the development of metastatic disease in both early and late stages, and thus a concerted effort has been made to delineate the AR-specific programs that facilitate progression to metastatic PCa. A multitude of downstream AR targets as well as critical AR cofactors have been identified which impinge upon both the AR pathway as well as associated metastatic phenotypes. This review will highlight the functional significance of these pathways to disseminated disease and define the molecular underpinnings behind these unique, AR-driven, metastatic signatures.

MD-miniRNA could be a more accurate biomarker for prostate cancer screening compared with serum prostate-specific antigen level

Prostate cancer and prostatic hyperplasia detection remains a great challenge, lacking of effective non-invasive and specific diagnostic biomarkers. In the current study, we aimed to identify the relative expression of plasma MD-miniRNA and its diagnostic performance in differentiating prostate cancer and prostatic hyperplasia patients from healthy controls, compared with serum prostate-specific antigen (PSA) level. All of the clinical participants (63 prostate cancer patients, 32 prostatic hyperplasia patients, and 50 healthy controls) were obtained from the Third Affiliated Hospital of Suzhou University in China between January 2013 and April 2014. Clinical characteristics were well matched. Plasma samples were extracted to test the relative expression of MD-miniRNA using the method of qRT-PCR. SPSS 22.0 statistical software package was used to analyze the data and GraphPad Prism 6.0 was used to generate the graphs. Relativity expression of plasma MD-miniRNA was significantly upregulated in prostate cancer, compared with prostatic hyperplasia patients and healthy controls. Serum PSA level revealed similar differences among these groups. MD-miniRNA presented a relatively high diagnostic accuracy with AUC of 0.86 (95 % CI 0.80-0.93) in differentiating prostate cancer patients from healthy controls. Simultaneously, MD-miniRNA was able to discriminate prostate cancer patients from prostatic hyperplasia controls with AUC of 0.79 (95 % CI 0.70-0.88). In addition, MD-miniRNA displayed a better diagnostic performance than PSA level. However, the panel of these two biomarkers revealed the best diagnostic performance, compared with either single biomarker. Results of this study showed that plasma MD-miniRNA could serve as a promising and noninvasive biomarker for diagnosing prostate cancer. Further large-scale studies are needed to confirm its clinical diagnosis accuracy.

miR-34a is an intracellular and exosomal predictive biomarker for response to docetaxel with clinical relevance to prostate cancer progression

BACKGROUND

Docetaxel-resistance limits successful treatment of castration resistant prostate cancer. We previously demonstrated that extracellular vesicles (exosomes) may play a role in regulating docetaxel resistance. Here, we investigated intracellular and extracellular (exosomal) miRNAs related to docetaxel resistance.

METHODS

Following global miRNA profiling of cell line models of docetaxel-resistance and their corresponding exosomes, we investigated the clinical relevance of four selected miRNAs (miR-598, miR-34a, miR-146a, miR-148a) in four publically available clinical cohorts representing both primary and advanced disease in tissue and urine specimens. One of these miRNAs, miR-34a was selected for functional evaluation by miRNA inhibition and over-expression in vitro. We further assessed the panel of miRNAs for their combined clinical relevance as a biomarker signature by examining their common predicted targets.

RESULTS

A strong correlation was found between the detection of miRNAs in exosomes and their corresponding cells of origin. Of the miRNAs chosen for further validation and clinical assessment, decreased miR-34a levels showed substantial clinical relevance and so was chosen for further analysis. Manipulating miR-34a in prostate cancer cells confirms that this miRNA regulates BCL-2 and may, in part, regulate response to docetaxel. When combined, these miRNAs are predicted to regulate a range of common mRNA targets, two of which (e.g., SNCA, SCL7A5) demonstrate a strong relationship with prostate cancer progression and poor prognosis.

CONCLUSIONS

This study supports the extracellular environment as an important source of minimally invasive predictive biomarkers representing their cellular origin. Using miR-34a as example, we showed that biomarkers identified in this manner may also hold functional relevance.

[New therapy concepts for castration-resistant prostate cancer: between hormone manipulation, targeted therapy and chemotherapy]

Within the last 2 years the therapeutic landscape of castration-resistant prostate cancer (CRPC) has dramatically changed. While chemotherapy with docetaxel has only shown a survival benefit in CRPC patients in the last 10 years, in the meantime 4 approved drugs are available for this indication and approval for immunotherapy with sipuleucel-T is expected. Docetaxel still plays a significant role in the treatment of CRPC but is also a cesura in the therapeutic sequence. For asymptomatic or minimally symptomatic, chemotherapy naive CRPC patients a significant survival benefit was shown for treatment with the androgen biosynthesis inhibitor abiraterone. Clinical data for the antiandrogen enzalutamide are expected shortly for this indication. For patients where docetaxel has failed abiraterone, enzalutamide and cabazitaxel have shown survival benefits in phase III trials. The radionuclide alpharadin not only palliated morbidity induced by bone metastases but also prolonged survival of CRPC patients. This review deals with the various drugs with respect to mode of action, clinical results and indications and will focus on new treatment options, such as targeted therapy with cabozantinib or immunotherapy with sipuleucel-T and prostvac.

Sequencing systemic therapies in metastatic castration-resistant prostate cancer

BACKGROUND

Men with prostate cancer will not die of the disease until it progresses to the metastatic castration resistant stage. At that stage, the median survival is 9 to 30 months.

METHODS

Recently approved and emerging treatments for metastatic castration-resistant prostate cancer (mCRPC) were reviewed based on their mechanisms of action, as well as sequencing and combining these treatments with existing options.

RESULTS

Advances in androgen deprivation therapy, immunotherapy, bone-targeted therapy, and chemotherapy have led to approvals of abiraterone acetate, sipuleucel-T, denosumab, and cabazitaxel for the treatment of mCRPC. Despite improvements in patient survival and quality of life, mCRPC remains incurable.

CONCLUSIONS

With the emerging new therapies, this is an unprecedented time in treating mCRPC. A better understanding of their mechanisms of action, the genetic makeup of each mCRPC, and the development of new prognostic and predictive biomarkers will help determine sequencing or different combination treatments for each individual patient.

A randomised phase 2 study combining LY2181308 sodium (survivin antisense oligonucleotide) with first-line docetaxel/prednisone in patients with castration-resistant prostate cancer

Castration-resistant prostate cancer (CRPC) is partially characterised by overexpression of antiapoptotic proteins, such as survivin. In this phase 2 study, patients with metastatic CRPC (n=154) were randomly assigned (1:2 ratio) to receive standard first-line docetaxel/prednisone (control arm) or the combination of LY2181308 with docetaxel/prednisone (experimental arm). The primary objective was to estimate progression-free survival (PFS) for LY2181308 plus docetaxel. Secondary efficacy measures included overall survival (OS), several predefined prostate-specific antigen (PSA)-derived end points, and Brief Pain Inventory (BPI) and Functional Assessment of Cancer Therapy-Prostate (FACT-P) scores. The median PFS of treated patients for the experimental arm (n=98) was 8.64 mo (90% confidence interval [CI], 7.39-10.45) versus 9.00 mo (90% CI, 7.00-10.09) in the control arm (n=51; p=0.755). The median OS for the experimental arm was 27.04 mo (90% CI, 19.94-33.41) compared with 29.04 mo (90% CI, 20.11-39.26; p=0.838). The PSA responses (≥ 50% PSA reduction), BPI, and FACT-P scores were similar in both arms. In the experimental arm, patients had a numerically higher incidence of grades 3-4 neutropenia, anaemia, thrombocytopenia, and sensory neuropathy. In conclusion, this study failed to detect a difference in efficacy between the two treatment groups.

Angiogenin mediates androgen-stimulated prostate cancer growth and enables castration resistance

The androgen receptor (AR) is a critical effector of prostate cancer development and progression. Androgen-dependent prostate cancer is reliant on the function of AR for growth and progression. Most castration-resistant prostate cancer (CRPC) remains dependent on AR signaling for survival and growth. Ribosomal RNA (rRNA) is essential for both androgen-dependent and castration-resistant growth of prostate cancer cells. During androgen-dependent growth of prostate cells, androgen-AR signaling leads to the accumulation of rRNA. However, the mechanism by which AR regulates rRNA transcription is unknown. Here, investigation revealed that angiogenin (ANG), a member of the secreted ribonuclease superfamily, is upregulated in prostate cancer and mediates androgen-stimulated rRNA transcription in prostate cancer cells. Upon androgen stimulation, ANG undergoes nuclear translocation in androgen-dependent prostate cancer cells, where it binds to the rDNA promoter and stimulates rRNA transcription. ANG antagonists inhibit androgen-induced rRNA transcription and cell proliferation in androgen-dependent prostate cancer cells. Interestingly, ANG also mediates androgen-independent rRNA transcription through a mechanism that involves its constitutive nuclear translocation in androgen-insensitive prostate cancer cells, resulting in a constant rRNA overproduction and thereby stimulating cell proliferation. Critically, ANG overexpression in androgen-dependent prostate cancer cells enables castration-resistant growth of otherwise androgen-dependent cells. Thus, ANG-stimulated rRNA transcription is not only an essential component for androgen-dependent growth of prostate cancer but also contributes to the transition of prostate cancer from androgen-dependent to castration-resistant growth status.

IMPLICATIONS

The ability of angiogenin to regulate rRNA transcription and prostate cancer growth makes it a viable target for therapy.

Radium-223 for the treatment of prostate cancer

INTRODUCTION

Bone metastases cause significant morbidity and mortality in castration-resistant prostate cancer (CRPC). Until recently, treatment options have been limited, but now six drugs are known to extend life expectancy, with docetaxel the current standard first-line cytotoxic therapy. Phase III studies have also shown a survival advantage for sipuleucel-T, cabazitaxel, abiraterone, enzalutamide and radium-223 . Radium-223 is unique among these agents, as the only bone-directed therapy shown to prolong survival in CRPC.

AREAS COVERED

This review covers the current standard of care for CRPC and recent drug developments that have demonstrated a survival benefit. It focuses on bone-directed therapies, in particular radium-223, the first-in-class alpha-emitting radionuclide and discusses the pivotal studies to date. A PubMed search using the keywords below was performed.

EXPERT OPINION

Radium-223 is set to become a new standard of care for the treatment of bony metastatic CRPC. It improves both survival and quality of life, delays skeletal events and is well tolerated. Its optimal use in the evolving treatment strategies for men with CRPC and bone metastases is yet to be determined.

A panel of five circulating microRNAs as potential biomarkers for prostate cancer

BACKGROUND

Circulating microRNA (miRNAs) have been shown to have the potential as noninvasive diagnosis markers in several types of cancers. In this study, we investigated whether circulating miRNAs could be used in the diagnosis of prostate cancer (CaP) in a Chinese patient population.

METHODS

Illumina's Human v2 miRNA microarray was used to analyze miRNAs levels in a small set of patients [25 CaP, 17 benign prostatic hyperplasia (BPH)] in an effort to identify CaP-specific miRNAs. The identified miRNAs were further examined by quantitative real-time PCR (qRT-PCR) in the same small set of patients. After the training phase of screening and selecting, the candidate miRNAs were validated in a larger independent cohort (80 CaP, 44 BPH, and 54 healthy controls) with qRT-PCR in the verification phase.

RESULTS

Five miRNAs were confirmed by qRT-PCR analysis in validation sets. Receiver operating characteristic (ROC) curve analysis showed all 5 miRNAs had diagnostic value. More importantly, further principal component analysis indicated component 1 extracted from expression data of the 5 miRNAs could differentiate CaP from BPH and healthy controls with high diagnosis performance, with an AUC of 0.924 and 0.860, respectively.

CONCLUSIONS

Our data suggested that circulating miRNAs could serve as biomarkers for CaP, and compared to single miRNA, the 5 miRNAs panel can accurately discriminate CaP from BPH and healthy controls with high sensitivity and specificity, and therefore, combined with routine PSA test, these 5 CaP-specific miRNAs may help improve CaP diagnosis in clinical application.

[Therapy of castration-resistant prostate cancer]

Within the last two years the therapy of castration resistant prostate cancer (CRPC) has made major advances. Both the COU-AA-301 phase III trial and the TROPIC trial showed a survival benefit for patients after docetaxel failure treated with abiraterone or cabazitaxel, respectively. With rising interest for chemotherapeutic options and novel drugs, our goal was to review within the context of a multidisciplinary team the available evidence and explore the standards for medical treatment of prostate cancer outside of clinical trials. From this background, we are carefully evaluating the current treatment recommendations, based on the available evidence, and highlight potential future treatment options but also discuss important clinical topics like treatment until progression versus the advantage of chemo holidays and definition of particular patient subgroups. Additionally, we focus on novel molecular entities, which will most likely be available in the near future, such as MDV3100 and Sipuleucel T. The role and importance of palliation with radiotherapy and proactive medical management of pain is also discussed, as well as new options for bone directed therapy. The multitude of treatment options for patients with advanced prostate cancer clearly asks for a close collaboration between urologists, medical oncologists and radiation therapists.

Castration-resistant prostate cancer: mechanisms, targets, and treatment

Patients with castration-resistant prostate cancer (CRPC), who progress after docetaxel therapy, had until very recently, only a few therapeutic options. Recent advances in this field brought about new perspectives in the treatment of this disease. Molecular, basic, and translational research has given us a better understanding on the mechanisms of CRPC. This great investment has turned into a more rational approach to the development of new drugs. Some of the new treatments are already available to our patients outside clinical trials and may include inhibitors of androgen biosynthesis; new chemotherapy agents; bone-targeted therapy; and immunotherapy. This paper aims to review the mechanisms of prostate cancer resistance, possible therapeutic targets, as well as new options to treat CRPC.

A phase II study of 2-methoxyestradiol (2ME2) NanoCrystal® dispersion (NCD) in patients with taxane-refractory, metastatic castrate-resistant prostate cancer (CRPC)

PURPOSE

2ME2 (Panzem®) is a non-estrogenic derivative of estradiol with antiproliferative and antiangiogenic activity. Preclinical data support antitumor activity in prostate cancer. This trial evaluated the efficacy of 2ME2 NCD in patients with taxane-refractory, metastatic CRPC.

EXPERIMENTAL DESIGN

Patients with metastatic CRPC who had progressed on only one prior taxane-based regimen were eligible. All patients received 2ME2 NCD at 1,500 mg orally four times daily, repeated in 28 day cycles. The primary endpoint was progression-free survival at month 6, with a secondary endpoint of PSA response. An exploratory endpoint was metabolic response on FDG-PET imaging.

RESULTS

A total of 50 pts was planned. The study was terminated after 21 pts when a futility analysis showed the primary endpoint was unlikely to be reached. The median number of cycles on study was 2 (range <1 to 12). Adverse events (AE) of grade ≥3 related to the study drug occurred in 7 unique patients (33%): elevations in liver function tests, fatigue or weakness, gastrointestinal hemorrhage, and hyponatremia. Paired FDG-PET scans were obtained for 11 pts. No metabolic responses were observed.

CONCLUSIONS

2ME2 NCD did not appear to have clinically significant activity in this study. 2ME2 NCD was well-tolerated and showed some evidence of biologic activity. Given the aggressive biology in this taxane-refractory population, the potential benefit from a cytostatic agent like 2ME2 might better be realized in the pre-chemotherapy (or rising PSA only) stage of CRPC.

Translating scientific advancement into clinical benefit for castration-resistant prostate cancer patients

In the past 12 months, three novel therapeutics-sipuleucel-T, cabazitaxel, and abiraterone acetate-were granted Food and Drug Administration regulatory approval for the treatment of metastatic castration-resistant prostate cancer (CRPC) patients based on phase III studies that showed a survival advantage. Other agents, including the novel antiandrogen MDV3100, are at an advanced stage of clinical phase III evaluation. The treatment paradigm for CRPC has now changed significantly, and this has introduced new challenges for physicians, including selecting patients for specific therapies, developing the best sequencing and combination regimens for the several new effective agents that have recently been approved or are in development, and dissecting mechanisms of resistance that will inform the development of a new generation of therapeutics. This Focus issue reviews the results obtained with immunotherapies, taxane cytotoxics, and androgen receptor targeting therapeutics for CRPC, as well as the postulated mechanisms of resistance to these protocols and proposed strategies for improvement. The use of biomarkers for patient selection, monitoring of treatment activity, and acceleration of drug approval will be critical for achieving further improvements in the treatment for CRPC, and is also discussed in detail.

The epothilones: new therapeutic agents for castration-resistant prostate cancer

The management of castration-resistant prostate cancer (CRPC) presents a clinical challenge because of limitations in efficacy and durability with currently available therapeutics. The epothilones represent a novel class of anticancer therapy that stabilizes microtubules, causing cell death and tumor regression in preclinical models. The structure of the tubulin-binding site for epothilones is distinct from that of the taxanes. Moreover, preclinical studies suggest nonoverlapping mechanisms of resistance between epothilones and taxanes. In early-phase studies in patients with CRPC, treatment with ixabepilone, a semisynthetic analog of epothilone B, induced objective responses and prostate-specific antigen declines in men previously progressing on docetaxel-based regimens. Clinical activity has been observed in nonrandomized trials for patients with CRPC using ixabepilone in the first- and second-line settings as a single agent and in combination with estramustine. Patupilone and sagopilone were also shown to have promising efficacy in phase II clinical trials of patients with CRPC. All three epothilones appear to be well tolerated, with modest rates of neutropenia and peripheral neuropathy. The lack of crossresistance between epothilones and taxanes may allow sequencing of these agents. Evaluating epothilones in phase III comparative trials would provide much-needed insight into their potential place in the management of patients with CRPC.

Novel therapies for metastatic castrate-resistant prostate cancer

Recent advances in tumor biology have made remarkable achievements in the development of therapy for metastatic castrate-resistant prostate cancer. These advances reflect a growing appreciation for the role of the tumor microenvironment in promoting prostate cancer progression. Prostate cancer is no longer viewed predominantly as a disease of abnormally proliferating epithelial cells but rather as a disease of complex interactions between prostate cancer epithelial cells (epithelial compartment) and the surrounding tissues (stromal compartment) in which they reside. For example, prostate cancers frequently metastasize to bone, an organ that contains a microenvironment rich in extracellular matrix proteins and stromal cells including hematopoietic cells, osteoblasts, osteoclasts fibroblasts, endothelial cells, adipocytes, immune cells, and mesenchymal stem cells. Multiple signaling pathways provide crosstalk between the epithelial and the stromal compartments to enhance tumor growth, including androgen receptor signaling, tyrosine kinase receptor signaling, and immune surveillance. The rationale to disrupt this "two-compartment" crosstalk has led to the development of drugs that target tumor stromal elements in addition to the cancer epithelial cell.

Bevacizumab and weekly docetaxel in patients with metastatic castrate-resistant prostate cancer previously exposed to docetaxel

Background. The aim of this paper was to evaluate the activity and tolerability of docetaxel (D) and bevacizumab (Bev) in patients with metastatic castrate-resistant prostate cancer (CRPC) previously exposed to D. Methods. Treatment consisted of D 30 mg/m(2) i.v. for four consecutive weekly administrations followed by a 2-week rest interval, in addition to Bev 5 mg/kg i.v. every 2 weeks. Results. Forty-three patients were enrolled: a PSA response was observed in 27 patients (62.7%, 95% CI: 0.41 to 0.91), and a palliative response was achieved in 31 patients (72.1%, 95%CI: 0.48 to 1.02). After a median followup of 11.3 months, only five patients had died. The regimen was generally well tolerated. Conclusion. Weekly D + biweekly Bev seems to be an effective and well-tolerated treatment option for patients with metastatic CRPC previously exposed to D-based chemotherapy.

Phase II study of docetaxel re-treatment in docetaxel-pretreated castration-resistant prostate cancer

OBJECTIVE

To determine the activity and tolerability of docetaxel re-treatment after first-line therapy with docetaxel in castration-resistant prostate cancer (CRPC).

PATIENTS AND METHODS

Between November 2005 and January 2009, 45 patients initially responding to docetaxel and then experiencing disease progression after a period of biochemical remission of at least 5 months were enrolled in a prospective multicenter study and re-treated with docetaxel. The primary endpoint was the biochemical response (biochemical partial response defined as > 50% prostate-specific antigen [PSA] decline); secondary endpoints were objective response, toxicity, progression-free survival (PFS) and overall survival (OS).

RESULTS

Partial PSA responses were observed in 11 patients (24.5%), 4 (25%) of whom also had an objective response. The treatment was well tolerated, with grade 1-2 neutropenia, thrombocytopenia, vomiting and peripheral neuropathy noted in 18 (40%), 11 (24.5%), 8 (17.8%), and 6 (13.3%) patients, respectively. The most common grade 3 toxicity was neutropenia, which was observed in 8 patients (17.8%). Median PFS was 5 months and median OS was 13 months.

CONCLUSIONS

Docetaxel re-treatment preserves anti-tumour activity and is well tolerated in a selected population of pretreated patients with CRPC. Further randomized trials are needed to confirm our preliminary results.

Synergistic antimicrotubule therapy for prostate cancer

Prostate cancer has been widely viewed as a chemoresistant neoplasm. Perhaps, the most prevalent antimicrotubule strategy involves docetaxel administration at its maximum-tolerated dose (MTD). Although the goal is to obtain total eradication of cancer cells, debilitating toxicities are presented by docetaxel therapy, including myelosuppression, immunosuppression, gastrointestinal toxicity and peripheral neuropathy. In addition, solubility limitations necessitate infusion of high-doses intravenously once or twice a week followed by a rest period, which allows recovery of normal proliferating cells to counter-balance efficacy. An emerging notion is that more of a toxic drug at its MTD is not necessarily better. It is likely that combinatorial antimicrotubule therapy with drugs occupying different sites on tubulin may enhance efficacy while reducing toxicity. Here we show that bromonoscapine (EM011), a microtubule-modulating noscapine analog, displays synergism with docetaxel as seen by cell viability and proliferation assays. Cell-cycle data demonstrated that lower dose-levels of docetaxel (25nM) in combination with EM011 caused an additive increase in proapoptotic activity. Since docetaxel alone caused severe mitotic arrest followed by mitotic slippage and endoreduplication, we strategized a sequential treatment regime that involved initial pretreatment with docetaxel followed by addition of EM011 to maximize mitotic arrest and subsequent apoptosis. In vivo studies with docetaxel and EM011 in combination showed a marked inhibition of tumor growth compared to docetaxel or EM011 as single-agents. Our studies suggest the potential usefulness of EM011 in the clinic to enhance docetaxel activity. This would reduce toxicity, thus improving the quality of life of docetaxel-treated patients.

Docetaxel reintroduction in patients with metastatic castration-resistant docetaxel-sensitive prostate cancer: a retrospective multicentre study

OBJECTIVE

To investigate the potential benefit of reintroducing docetaxel chemotherapy in patients with progressive metastatic castration-resistant prostate cancer (mCRPC) who had initially responded to first-line docetaxel-based regimen.

PATIENTS AND METHODS

Records were evaluated retrospectively from French patients with mCRPC who had been included in seven controlled clinical studies of docetaxel as first-line treatment. We identified patients who were confirmed as responders to first-line treatment, discontinued for reasons other than disease progression or unacceptable toxicity, and who received further docetaxel chemotherapy for disease progression. The primary objective was to assess efficacy in terms of the prostate-specific antigen (PSA) response after resuming a docetaxel-based chemotherapy. Secondary objectives were overall survival and tolerance.

RESULTS

Of the 148 patients who responded to first-line docetaxel, 50 received further therapy with docetaxel and were analysed. The median (range) response duration to first-line docetaxel was 10.3 (4.6-45.7) months and the median docetaxel-free interval was 18.4 (5.0-46.7) months. Docetaxel was reintroduced as second-line therapy in 52% of patients and as further lines in 48%. After docetaxel reintroduction, 24 patients (48%) had a 50% decrease in PSA level (95% confidence interval, CI, 34.1-61.8%). The median (95% CI) overall survival from docetaxel reintroduction was 16 (13-20) months. Re-treatment was well tolerated (6% of grade 3-4 haemotoxicity).

CONCLUSION

Docetaxel reintroduction appears to be effective, with favourable tolerance profiles, in patients with mCRPC having responded to first-line docetaxel, and should be prospectively assessed in clinical trials against alternative therapies or investigational agents given alone or in combination, to define further management.

Molecular and traditional chemotherapy: a united front against prostate cancer

Castrate resistant prostate cancer (CRPC) is essentially incurable. Recently though, chemotherapy demonstrated a survival benefit ( approximately 2months) in the treatment of CRPC. While this was a landmark finding, suboptimal efficacy and systemic toxicities at the therapeutic doses warranted further development. Smart combination therapies, acting through multiple mechanisms to target the heterogeneous cell populations of PC and with potential for reduction in individual dosing, need to be developed. In that, targeted molecular chemotherapy has generated significant interest with the potential for localized treatment to generate systemic efficacy. This can be further enhanced through the use of oncolytic conditionally replicative adenoviruses (CRAds) to deliver molecular chemotherapy. The prospects of chemotherapy and molecular-chemotherapy as single and as components of combination therapies are discussed.

Multinational, double-blind, phase III study of prednisone and either satraplatin or placebo in patients with castrate-refractory prostate cancer progressing after prior chemotherapy: the SPARC trial

PURPOSE

This multinational, double-blind, randomized, placebo-controlled, phase III trial assessed the efficacy and tolerability of the oral platinum analog satraplatin in patients with metastatic castrate-refractory prostate cancer (CRPC) experiencing progression after one prior chemotherapy regimen.

PATIENTS AND METHODS

Nine hundred fifty patients were randomly assigned (2:1) to receive oral satraplatin (n = 635) 80 mg/m(2) on days 1 to 5 of a 35-day cycle and prednisone 5 mg twice daily or placebo (n = 315) and prednisone 5 mg twice daily. Primary end points were progression-free survival and overall survival (OS). The secondary end point was time to pain progression (TPP).

RESULTS

A 33% reduction (hazard ratio [HR] = 0.67; 95% CI, 0.57 to 0.77; P < .001) was observed in the risk of progression or death with satraplatin versus placebo. This effect was maintained irrespective of prior docetaxel treatment. No difference in OS was seen between the satraplatin and placebo arms (HR = 0.98; 95% CI, 0.84 to 1.15; P = .80). Compared with placebo, satraplatin significantly reduced TPP (HR = 0.64; 95% CI, 0.51 to 0.79; P < .001). Satraplatin was generally well tolerated, although myelosuppression and GI disorders occurred more frequently with satraplatin.

CONCLUSION

Oral satraplatin delayed progression of disease and pain in patients with metastatic CRPC experiencing progression after initial chemotherapy but did not provide a significant OS benefit. Satraplatin was generally well tolerated. These results suggest activity for satraplatin in patients with CRPC who experience progression after initial chemotherapy.

Satraplatin for the therapy of castration-resistant prostate cancer

While docetaxel-based chemotherapy improves survival in patients with castration-resistant prostate cancer, all of these patient’s cancers will eventually progress and other active treatment agents are necessary. Satraplatin is a third-generation orally-available platinum analog that demonstrated a 33% reduction in the risk of progression in patients with metastatic castration-resistant prostate cancer following one prior chemotherapy regimen in the large Phase III Satraplatin and Prednisone Against Refractory Cancer (SPARC) trial. Satraplatin also demonstrated beneficial effects on pain and displayed evidence of biological activity with prostate-specific antigen level declines and objective response rates. Satraplatin did not significantly extend survival, although this analysis may have been confounded by post-study therapy. Further development is ongoing with the evaluation of combination regimens containing satraplatin in other solid tumors. In addition, efforts are ongoing to select patients who are more likely to benefit from satraplatin.

Androgen ablation augments prostate cancer vaccine immunogenicity only when applied after immunization

BACKGROUND

Androgen ablation (AA) causes apoptosis of normal and neoplastic prostate cells. It is a standard treatment for advanced prostate cancer. Androgen ablation-mediated immunological effects include bone marrow hyperplasia, thymic regeneration, T and B cell lymphopoeisis and restoration of age-related peripheral T cell dysfunction. Androgens also regulate the transcription of several cytokines. Dendritic cells (DC) are the most potent antigen presenting cells that can activate antigen-specific naïve T cells. Despite myriad clinical trials involving DC-based prostate cancer immunotherapies, the effects of AA on DC function remain largely uncharacterized. Therefore, we investigated the effects of AA on DC and whether it could improve the efficacy of prostate cancer immunotherapy.

METHODS

Cytokine expression changes due to AA were quantified by multiplex ELISA. Flow cytometry was used to assess AA-mediated effects on DC maturation and expression of costimulatory markers. Mixed leukocyte reactions and cell-mediated lysis assays elucidated the role of androgens in DC function. The effect of AA on the efficacy of vaccination against a prostate tumor-associated antigen was tested using Elispot assays.

RESULTS

Androgen ablation increased dendritic cell maturation and costimulatory marker expression, but had no effect on DC costimulatory function. However, DC isolated from castrated mice increased the expression of key cytokines by antigen-experienced T cells while decreasing their expression in naïve cells. Finally, androgen ablation improved immune responses to vaccination only when applied after immunization.

CONCLUSION

Androgen ablation causes differential effects of DC on primary and secondary T cell responses, thus augmenting vaccine immunogenicity only when applied after immunization.

(188)Re-HEDP combined with capecitabine in hormone-refractory prostate cancer patients with bone metastases: a phase I safety and toxicity study

Purpose

¹⁸⁸Re-HEDP is indicated for the treatment of pain in patients with painful osteoblastic bone metastases, including hormone-refractory prostate cancer patients. Efficacy may be improved by adding chemotherapy to the treatment regimen as a radiation sensitizer. The combination of ¹⁸⁸Re-HEDP and capecitabine (Xeloda®) was tested in a clinical phase I study.

Methods

Patients with hormone-refractory prostate cancer were treated with capecitabine for 14 days (oral twice daily in a dose escalation regimen with steps of 1/3 of 2,500 mg/m² per day in cohorts of three to six patients, depending on toxicity). Two days later patients were treated with 37 MBq/kg ¹⁸⁸Re-HEDP as an intravenous injection. Six hours after treatment post-therapy scintigraphy was performed. Urine was collected for 8 h post-injection. Follow-up was at least 8 weeks. The primary end-point was to establish the maximum tolerable dose (MTD) of capecitabine when combined with ¹⁸⁸Re-HEDP. Secondary end-points included the effect of capecitabine on the biodistribution and pharmacokinetics of ¹⁸⁸Re-HEDP.

Results

Three patients were treated in the first and second cohorts, each without unacceptable toxicity. One of six patients in the highest cohort experienced unacceptable toxicity (grade 4 thrombopaenia). The MTD proved to be the maximum dose of 2,500 mg/m² per day capecitabine. No unexpected toxicity occurred. Capecitabine had no effect on uptake or excretion of ¹⁸⁸Re-HEDP.

Conclusion

Capecitabine may be safely used in combination with ¹⁸⁸Re-HEDP in a dose of 2,500 mg/m² per day and 37 MBq/kg, respectively. Efficacy will be further studied in a phase II study using these dosages.

What is the real impact of bone pain on survival in patients with metastatic hormone-refractory prostate cancer treated with docetaxel?

OBJECTIVES

To determine the benefit of starting early chemotherapy with docetaxel (the recommended first-line treatment) for patients with asymptomatic metastatic hormone-refractory prostate cancer (HRPC).

PATIENTS AND METHODS

Data were analysed from 145 patients with HRPC treated with chemotherapy between February 2000 and June 2002 in one French centre. Eligible patients were categorized into three groups according to the bone pain at baseline, i.e. minimal/no pain, mild, and moderate/severe pain. The primary endpoint was the effect of bone pain on overall survival (OS).

RESULTS

Docetaxel was administered to 67% of patients. The risk of death was 1.56 and 2.11 times higher for patients with mild or moderate/severe pain than for those with minimal/no pain (P = 0.027). The median (95% confidence interval (CI)) OS was 23.1 (18.5-27.6) and 14.1 (8.9-19.2) months (P = 0.001, log-rank-test) for patients with minimal pain or no pain treated with docetaxel-based chemotherapy compared with mitoxantrone, respectively. The prostate-specific antigen doubling time (PSA-DT) had a significant effect on OS in patients with minimal/no pain, with a median of 32.4 and 16.5 months for a PSA-DT of >or=45 and <45 days, respectively (P < 0.001).

CONCLUSIONS

Our results suggest that patients with HRPC and minimal or no bone pain could have better survival than those with mild pain or moderate to severe pain, independent of the treatment administered. In addition, patients with HRPC and minimal or no bone pain treated with docetaxel-based chemotherapy have a significantly better OS than those treated with mitoxantrone. The PSA-DT can be useful to identify asymptomatic patients who are candidates for early treatment.

Docetaxel chemotherapy of Korean patients with hormone- refractory prostate cancer:comparative analysis between 1st-line and 2nd-line docetaxel

PURPOSE

This study was undertaken to investigate the outcomes associated with docetaxel treatment of Korean patients with hormone-refractory prostate cancer (HRPC) and to compare its clinical efficacies in 1st and 2nd-line settings.

PATIENTS AND METHODS

This study was retrospectively performed and included 47 patients with HRPC. The 1st-line group consisted of 19 patients who had not undergone prior chemotherapy, and the 2nd-line group consisted of 28 patients who underwent prior chemotherapy. All patients were treated with 75mg/m2 IV docetaxel every 3 weeks and 5mg of prednisone twice daily with a continuous androgen blockade.

RESULTS

Of 47 study subjects, 14 patients (29.8%) had > or = 50% PSA decline from baseline. PSA response was more common in the 1st-line group, but this was not statistically different (42.1% vs. 21.4%, p = 0.114). After a median follow up of 11 months (range, 6-24 months), the 1st-line group showed a longer time to PSA progression (4 vs. 2 months, p = 0.015) and survival (17 vs. 10 months, p = 0.037) than the 2nd-line group. In terms of toxicities, no difference was apparent between the 2 groups.

CONCLUSION

In a 1st-line setting, docetaxel is an effective and tolerable agent for Korean HRPC patients, and that its efficacy is limited, although 2nd-line docetaxel is tolerable.

[Chemotherapy for prostate cancer]

For many years the benefit of chemotherapy in patients with prostate cancer was thought to be limited to palliation of late-stage disease, and thus this treatment option only became involved in patient care towards the end of the disease process, if at all. However, two landmark phase-III trials with docetaxel-based therapy (TAX 327 and Southwest Oncology Group, SWOG, 9916) have shown a survival benefit for patients with hormone refractory prostate cancer (HRPC) thus prompting a change in patterns of care. With raising interest for chemotherapeutic options and clinical trials for new drugs and new indications (neoadjuvant therapy, adjuvant therapy, increasing PSA levels after local treatment, and hormone sensitive cancer) under way our goal was to review within the context of a multidisciplinary team the available evidence and explore the standard for the medical treatment of prostate cancer outside of clinical trials. We are carefully evaluating the current treatment recommendations based on the available evidence and highlight potential future treatment options but also discuss important clinical topics (treatment until progression versus the advantage of chemo holidays, definition of particular patient subgroups and potential second line options) for which there are no clear cut answers to date. The role and importance of radiotherapy, biphosphonate treatment and the medical management of pain and side effects is also discussed. The multitude of treatment options for patients with advanced prostate cancer clearly asks for a close collaboration between urologists, medical oncologists and radiation therapists.

Survival and PSA response of patients in the TAX 327 study who crossed over to receive docetaxel after mitoxantrone or vice versa

BACKGROUND

The TAX 327 study compared 3-weekly docetaxel, weekly docetaxel or 3-weekly mitoxantrone, each with prednisone, for 1006 patients with metastatic hormone-refractory prostate cancer. Survival and symptom control were superior following 3-weekly docetaxel as compared with mitoxantrone. At progression, many patients were treated with the other drug. Here, we provide a retrospective report of survival and prostate-specific antigen (PSA) response after second-line therapy.

METHODS

The TAX 327 database provided information about treatment after progression on first-line therapy, and survival has been updated. Investigators were asked to provide information about crossover treatment and serial PSA values.

RESULTS

We identified 232 crossover patients. Median survival after crossover was 10 months and did not depend on direction of crossover. Data on PSA response are available for 96 patients: PSA response (> or =50% reduction) occurred in 15% of 71 men receiving mitoxantrone after docetaxel and in 28% of 25 men receiving docetaxel after mitoxantrone. Median PSA progression-free survival was 3.4 months for mitoxantrone after docetaxel and 5.9 months for docetaxel after mitoxantrone.

CONCLUSIONS

One quarter of men received crossover therapy and survival was similar in the crossover groups. The PSA response rate to docetaxel after mitoxantrone was higher than that for mitoxantrone after docetaxel.

Biweekly doxorubicin/ketoconazole as second-line treatment in docetaxel-resistant, hormone-refractory prostate cancer

OBJECTIVES

Docetaxel is an effective first-line treatment for hormone-refractory prostate cancer. Nevertheless, the prognosis subsequent to progression after first-line therapy is poor and no second-line treatment has been established.

METHODS

A total of 34 patients with androgen-independent prostate cancer received doxorubicin, 30 mg/m(2), every 2 weeks and ketoconazole daily, 400 mg orally every 8 hours. All patients had been treated with docetaxel and had disease progression within 6 months after completion of first-line treatment.

RESULTS

Of the 32 evaluable patients, 13 (43.7%, 95% confidence interval [CI] 26.3% to 62.3%) had a prostate-specific antigen (PSA) response, and 4 (28%, 95% CI 8.4% to 58.1%) of 14 patients with measurable disease had a response to therapy. The median time to progression (TTP) was 3.9 months (95% CI 2.0 to 5.9), and the median overall survival (OS) was 13 months (95% CI 8.7 to 17.3). Toxicity was mild, with only 4 cases of nonhematologic grade 3 or 4 toxicity. The most frequent toxicity was nail changes (33 of 34 patients), which was mainly grade 1 (30 cases).

CONCLUSIONS

The combination of biweekly doxorubicin and ketoconazole is an effective, well-tolerated, second-line therapy for hormone-refractory prostate cancer.

Vascular targeting, chemotherapy and active immunotherapy: teaming up to attack cancer

Chemotherapy has been combined with therapeutic tumor-specific vaccination in an attempt to simultaneously debulk tumors, increase the effector lymphocyte:tumor cell ratio, and favor immune-mediated tumor rejection. However, chemotherapy is often inadequate because of insufficient and uneven drug penetration into tumors, and because it might also cause, in some instances, undesirable side effects and immunosuppression. Here, we suggest a combined approach based on targeted alteration of the endothelial barrier function with vascular disrupting agents, such as tumor necrosis factor-alpha (TNF-alpha), before chemotherapy and tumor-specific vaccination. This approach has the potential to empower chemoimmunotherapeutic strategies by improving cytotoxic drug penetration into tumors while exploiting the proinflammatory and immunostimulating activities of TNF-alpha and active immunotherapy.

Indium-111 capromab pendetide in the management of recurrent prostate cancer

The provision of accurate prognostic information is a long-standing goal for effective management of prostate adenocarcinoma. Nontargeted imaging modalities are less efficient at detecting slow-growing prostate cancers. Prostate-specific membrane antigen has emerged as a superior biomarker, especially for the evaluation of metastatic spread. Advances in imaging technology have focused clinical interest on indium-111 capromab ((111)In capromab) pendetide, a radioimmunoconjugate that detects prostate-specific membrane antigen expression in vivo. Single-photon emission computed tomography capromab pendetide images, fused with those generated by computed tomography or magnetic resonance, have engendered improvements in localization accuracy by correlating high signal intensity with anatomic structures. In long-term outcomes studies, fused (111)In capromab pendetide scans have delivered significant benefits for patient selection and improved treatment of prostate cancer.

Evidence of a novel docetaxel sensitizer, garlic-derived S-allylmercaptocysteine, as a treatment option for hormone refractory prostate cancer

The recent introduction of docetaxel in the treatment of hormone refractory prostate cancer (HRPC) has made a small but significant impact on patient survival. However, its effect is limited by intolerance and resistance. The aim of our study was to investigate if the garlic-derived compound, S-allylmercaptocysteine (SAMC), was able to act as a docetaxel sensitizing agent. First, the effect of SAMC on docetaxel sensitivity was examined on 3 HRPC cell lines by colony forming assay. We found that SAMC increased the efficacy of docetaxel on colony forming inhibition by 9-50% compared to single agent treatment. Second, using the HRPC CWR22R nude mice model, we found that the combination of SAMC and docetaxel was 53% more potent than docetaxel alone (p = 0.037). In addition, there was no additive toxicity in the mice treated with the combination therapy evidenced by histological and functional analysis of liver, kidney and bone marrow. These results suggest that SAMC is able to increase the anticancer effect of docetaxel without causing additional toxic effect in vivo. Third, flow cytometry and Western blotting analysis on HRPC cell lines demonstrated that SAMC promoted docetaxel-induced G2/M phase cell cycle arrest and apoptotic induction. In addition, immunohistochemistry on CWR22R xenograft revealed a suppression of Bcl-2 expression and upregulation of E-cadherin in the SAMC and docetaxel treated animals. These results suggest that SAMC may promote docetaxel-induced cell death through promoting G2/M cell cycle arrest and apoptosis. Our study implies a potential role for SAMC in improving docetaxel based chemotherapy for the treatment of HRPC.