Is there a role for platinum chemotherapy in the treatment of patients with hormone-refractory prostate cancer?

Carboplatin in Metastatic Castrate Resistant Prostate Cancer: A Retrospective Study of Heavily Pretreated Patients (COMPACT)

INTRODUCTION

Many clinicians consider carboplatin monotherapy in advanced castrate-resistant prostate cancer (CRPC) patients who have progressed through all available hormonal and standard chemotherapy treatment options, despite the limited evidence to justify its use.

PATIENTS AND METHODS

This retrospective analysis aimed to evaluate the use of carboplatin monotherapy in patients with refractory prostate cancer in Australia. Efficacy (PSA response, duration, and survival) as well as toxicity was evaluated. Demographic data, PSA response rates, survival data and details of carboplatin treatment protocols, including dose and duration, were collected. Exploratory analyses were conducted on potential prognostic factors.

RESULTS

Fifty-one patients received carboplatin: median age 68 (range 55-86 years). Most patients (78.3%) received carboplatin AUC 5 at 3-week intervals. The median number of cycles of carboplatin received was 3 (range 1-17). The median duration of treatment was 63 days (range 1-441). The median overall survival was 6.8 months. Six (11.8%) patients had a PSA response ≥ 50%. The median time to PSA progression on carboplatin, as defined by PCWG,2 was 67 days (range 15-418). Sixteen patients (31%) required dose delays or reductions and 8 patients (15.6%) ceased carboplatin due to treatment toxicity.

CONCLUSION

Carboplatin is often used in Australia once all available standard treatment options have been exhausted in patients with CRPC. Toxicity is mild, and a minority of patients have responses, but these responses are rarely durable.

Combined Cabazitaxel and Carboplatin Treatment of Metastatic Castration Resistant Prostate Cancer Patients, With Innate or Acquired Resistance to Cabazitaxel Monotherapy

BACKGROUND

There is new interest in platinum-based treatment of patients with metastatic castration resistant prostate cancer (mCRPC), to which a subgroup responds. Although platinum sensitivity is suggested to be associated with aggressive disease features and distinct molecular profiles, identification of responders is a clinical challenge. In this study, we selected patients who displayed PSA progression during cabazitaxel monotherapy, for combined cabazitaxel and carboplatin treatment.

METHODS

In this retrospective study, mCRPC patients received carboplatin and cabazitaxel after biochemical progression following at least 2 cabazitaxel monotherapy cycles. We assessed PSA response, Time to PSA Progression (TTpsa) and Time to Radiographic Progression (TTrad). For a subset of patients, mutational analysis of BRCA-1, BRCA-2, ATM, PTEN, P53 and RB1 was performed.

RESULTS

Forty-five patients were included, after a median of 4 (3-6) cycles of cabazitaxel monotherapy. Patients received a median of 3 (2-5) cycles of combined cabazitaxel and carboplatin, on which 12 (26.6%) patients had a PSA decline ≥ 50% from baseline. TTpsa was 2 (1-5) months and TTrad 3 (2-6) months. Adverse events were predominantly grade 1-2. Of the 29 (64.4%) patients evaluable for molecular signature, 6 (13.3%) had BRCA1, BRCA2 or ATM mutations and 12 (26.7%) had a PTEN, P53 or RB1 mutations. The occurrence of these mutations was not associated with any clinical outcome measure.

CONCLUSIONS

In this study we showed that patients with PSA progression during cabazitaxel monotherapy could benefit from the addition of carboplatin to cabazitaxel, while prospective identification of these patients remains a clinical challenge.

Antibody-drug conjugates in urinary tumors: clinical application, challenge, and perspectives

Urinary tumors primarily consist of kidney, urothelial, and prostate malignancies, which pose significant treatment challenges, particularly in advanced stages. Antibody-drug conjugates (ADCs) have emerged as a promising therapeutic approach, combining monoclonal antibody specificity with cytotoxic chemotherapeutic payloads. This review highlights recent advancements, opportunities, and challenges in ADC application for urinary tumors. We discuss the FDA-approved ADCs and other novel ADCs under investigation, emphasizing their potential to improve patient outcomes. Furthermore, we explore strategies to address challenges, such as toxicity management, predictive biomarker identification, and resistance mechanisms. Additionally, we examine the integration of ADCs with other treatment modalities, including immune checkpoint inhibitors, targeted therapies, and radiation therapy. By addressing these challenges and exploring innovative approaches, the development of ADCs may significantly enhance therapeutic options and outcomes for patients with advanced urinary tumor.

Optimization Therapy by Coupling Intermittent Androgen Suppression with Impulsive Chemotherapy for a Prostate Cancer Model

Intermittent androgen suppression in the prostate cancer is often relapsed by the increasing of prostate specific antigen level during the on-treatment. Historically, chemotherapy has had a limited role in the treatment of prostate cancer. However, new agents are showing promise in patients with advanced disease. Intermittent androgen suppression plus chemotherapy in pulsed pattern has become an indispensable clinical scheme for prostate cancer, which is presented to describe the transformation mechanism for three kinds of cancer cells in this paper. The model is then extended to include the residual effect of chemotherapy which suppresses the cancer cells production, thereby preventing the relapse. The optimal controls represent the efficiencies of both intermittent androgen suppression and chemotherapy in suppressing relapse of prostate cancer. Based on an optimal algorithm, numerical simulations are implemented not only to show the optimal durations of on- and off-treatment and chemotherapy dosages but also to present the effectiveness of different strategies in inhibiting the relapse for three types of patients. Results reveal that the optimal intermittent androgen suppression scheme with alterable treatment cycles is pivotal for type I and II patients, in part because it can greatly reduce the on-treatment time and degrade the level of prostate specific antigen. Furthermore, optimal hybrid schedule even averts the relapse of prostate cancer for type II and III patients. Finally, comparing the prostate specific antigen under intermittent androgen suppression schedule with residual effect of chemotherapy to one without residual effect of chemotherapy demonstrates the validity of both our model and algorithms in lessening the prostate specific antigen and decreasing the chemotherapy dosages.

[Clinical efficacy of docetaxel combined with carboplatin in patients with metastatic castration-resistant prostate cancer]

OBJECTIVE

To observe the early efficacy and toxicity of docetaxel combined with carboplatin in patients with metastatic castration-resistant prostate cancer (mCRPC).

METHODS

From May 2017 to July 2019, fifteen patients with mCRPC treated in Peking University First Hospital were collected. The median age was 70 years (43-77 years), and the pathological types were all adenocarcinoma, which was confirmed as distant metastasis by imaging examination. They were given the chemotherapy of docetaxel combined with carboplatin. The specific method was as follows: each cycle was 28 days. Androgen deprivation therapy was administered routinely throughout the treatment period. Blood routine, liver and kidney function, blood clotting function and prostate-specific antigen (PSA) tests were performed before each cycle. Docetaxel was administered intravenously on the first day of each cycle at a dose of 75 mg/m², and carboplatin was administered intravenously on the second day at the dose calculated by Calvert formula. The main outcome measures including PSA decline range, pain remission rate and occurrence of adverse reactions were observed and analyzed.

RESULTS

Among the 15 patients, 12 had completed at least 4 cycles of chemotherapy and had short-term efficacy evaluation. PSA decline range > 50% was observed in 8 patients (66.7%). Among the 9 patients with bone pain, remarkable pain relief was observed in 4 patients (44.4%). Among the 4 patients with measurable metastatic lesions, 2 achieved partial response, 1 was evaluated as stable disease, and 1 was evaluated as progressive disease. The main adverse reactions of chemotherapy included bone marrow suppression, gastrointestinal reactions, fatigue and neurological disorders, and most of them were within the tolerable range.

CONCLUSION

This report is a case series study of docetaxel combined with carboplatin in the treatment of mCRPC reported in China and the conclusions are representative. The chemotherapy of docetaxel combined with carboplatin has positive short-term efficacy and high safety in patients with mCRPC, which is worthy of further promotion and exploration in clinical practice.

Prostate Cancer: Biology, Incidence, Detection Methods, Treatment Methods, and Vaccines

Cancer of the prostate are cancers in which most incidences are slow-growing, and in the U.S., a record of 1.2 million new cases of prostate cancer occurred in 2018. The rates of this type of cancer have been increasing in developing nations. The risk factors for prostate cancer include age, family history, and obesity. It is believed that the rate of prostate cancer is correlated with the Western diet. Various advances in methods of radiotherapy have contributed to lowering morbidity. Therapy for hormone- refractory prostate cancer is making progress, for almost all men with metastases will proceed to hormone-refractory prostate cancer. Smoking cigarettes along with the presence of prostate cancer has been shown to cause a higher risk of mortality in prostate cancer. The serious outcome of incontinence and erectile dysfunction result from the cancer treatment of surgery and radiation, particularly for prostate- specific antigen detected cancers that will not cause morbidity or mortality. Families of patients, as well as patients, are profoundly affected following the diagnosis of prostate cancer. Poor communication between spouses during prostate cancer increases the risk for poor adjustment to prostate cancer. The use of serum prostate-specific antigen to screen for prostate cancer has led to a greater detection, in its early stage, of this cancer. Prostate cancer is the most common malignancy in American men, accounting for more than 29% of all diagnosed cancers and about 13% of all cancer deaths. A shortened course of hormonal therapy with docetaxel following radical prostatectomy (or radiation therapy) for high-risk prostate cancer has been shown to be both safe and feasible. Patients treated with docetaxel-estramustine had a prostate-specific antigen response decline of at least 50%. Cancer vaccines are an immune-based cancer treatment that may provide the promise of a non-toxic but efficacious therapeutic alternative for cancer patients. Further studies will elucidate improved methods of detection and treatment.

Activity of Platinum-Based Chemotherapy in Patients With Advanced Prostate Cancer With and Without DNA Repair Gene Aberrations

IMPORTANCE

DNA repair gene aberrations occur in 20% to 30% of patients with castration-resistant prostate cancer (CRPC), and some of these aberrations have been associated with sensitivity to poly(ADP-ribose) polymerase (PARP) inhibition platinum-based treatments. However, previous trials assessing platinum-based treatments in patients with CRPC have mostly included a biomarker-unselected population; therefore, efficacy in these patients is unknown.

OBJECTIVE

To characterize the antitumor activity of platinum-based therapies in men with CRPC with or without DNA repair gene alterations.

DESIGN, SETTING, AND PARTICIPANTS

In this case series, data from 508 patients with CRPC treated with platinum-based therapy were collected from 25 academic centers from 12 countries worldwide. Patients were grouped by status of DNA repair gene aberrations (ie, cohort 1, present; cohort 2, not detected; and cohort 3, not tested). Data were collected from January 1986 to December 2018. Data analysis was performed in 2019, with data closure in April 2019.

EXPOSURE

Treatment with platinum-based compounds either as monotherapy or combination therapy.

MAIN OUTCOMES AND MEASURES

The primary end points were as follows: (1) antitumor activity of platinum-based therapy, defined as a decrease in prostate-specific antigen (PSA) level of at least 50% and/or radiological soft tissue response in patients with measurable disease and (2) the association of response with the presence or absence of DNA repair gene aberrations.

RESULTS

A total of 508 men with a median (range) age of 61 (27-88) years were included in this analysis. DNA repair gene aberrations were present in 80 patients (14.7%; cohort 1), absent in 98 (19.3%; cohort 2), and not tested in 330 (65.0%; cohort 3). Of 408 patients who received platinum-based combination therapy, 338 patients (82.8%) received docetaxel, paclitaxel, or etoposide, and 70 (17.2%) received platinum-based combination treatment with another partner. A PSA level decrease of at least 50% was seen in 33 patients (47.1%) in cohort 1 and 26 (36.1%) in cohort 2 (P = .20). In evaluable patients, soft tissue responses were documented in 28 of 58 patients (48.3%) in cohort 1 and 21 of 67 (31.3%) in cohort 2 (P = .07). In the subgroup of 44 patients with BRCA2 gene alterations, PSA level decreases of at least 50% were documented in 23 patients (63.9%) and soft tissue responses in 17 of 34 patients (50.0%) with evaluable disease. In cohort 3, PSA level decreases of at least 50% and soft tissue responses were documented in 81 of 284 patients (28.5%) and 38 of 185 patients (20.5%) with evaluable disease, respectively.

CONCLUSIONS AND RELEVANCE

In this study, platinum-based treatment was associated with relevant antitumor activity in a biomarker-positive population of patients with advanced prostate cancer with DNA repair gene aberrations. The findings of this study suggest that platinum-based treatment may be considered an option for these patients.

Synthesis and characterization of proanthocyanidin-chitosan nanoparticles: An assessment on human colorectal carcinoma HT-29 cells

Cancer nanotheranostic materials are helpful in monitoring drug delivery and efficacy against tumor cells. Current chemotherapeutic may have adverse side effects and this necessity to discover the new modern therapeutic nano-drugs. In the present study, we designed the new targeted and degradable polymer of bio-active chitosan nanoparticles with proanthocyanidin (PAC-CSNPs) and evaluated its apoptotic effects against human colorectal carcinoma cells (HT-29). The functional groups were characterized by Fourier-transform infrared spectroscopy and transmission electron microscope. Further, their dispersion of spherical form nanoparticle with an average size of 73.43 nm used for drug delivery system. The PAC-CSNPs were targeted to inhibit the cyclin-dependent kinases and prevent cell cycle/cell division in cancer cells. At high concentrations of PAC (25 μg/mL) exposure, cell viability of HT-29 cells was greater than 80%. However, at low concentrations of PAC-CSNPs (6.25 μg/mL) exposure, HT-29 cell mortality was high, which may be due to the efficient drug release by CSNPs. The percentage of reactive oxygen species (ROS) levels were 12 ± 2.52% (control), 39 ± 4.32% (PAC), and 85.06 ± 3.54% (PAC-CSNPs). The over production of ROS by PAC-CSNPs can prompt DNA damage, cell death and apoptosis in HT-29 cells. The in vivo toxicity of synthesized PAC-CSNPs was tested against zebra fish observed at dose-time-dependent intervals. In conclusion, the PAC-CSNPs enhanced HT-29 cell death and shows promise as a novel future nano-therapy for cancer.

Mitochondrial dysfunction mediated apoptosis of HT-29 cells through CS-PAC-AgNPs and investigation of genotoxic effects in zebra (Danio rerio) fish model for drug delivery

The present study reports the validation of cancer nanotherapy using proanthocyanidin (PAC). Nowadays, in vitro and in vivo deliveries of nanoparticle (NPs) drugs have been paid more attention, intensively. Moreover, the current chemotherapeutic drugs have few first rate drawbacks including lack of specificity and requirement of excessive drug doses. To overcome this problem of chemotherapy, the attainment of high drug loading in combination with degradable polymer nanoparticles (for instance,chitosan) is a trending research in cancer biology. Hence, in this study, the synthesized PAC-AgNPs were successfully crosslinked with chitosan nanoparticles (CS-PAC-AgNPs), which were found to be spherical or polygonal in shape with a median size of 70.68 nm and 52.16 nm as observed by FTIR, FESEM and TEM analysis; thus, being suitable for drug delivery. CS-PAC-AgNPs were taken up via endocytosis by cancer cells and enabled the release cytochrome-C from mitochondria, followed by dysregulation of anti-apoptotic protein Bcl2 family, inducing the apoptotic mediated activation of caspase 9 and 3. To identify the genotoxicity of the synthesized CS-PAC-AgNPs, the mortality, hatching rate, malformation and abnormalities of embryo/larvae of the vertebrate zebra fish model (Danio rerio) were observed in a dose-time-dependent manner. This improved cancer nanotherapy can thus be utilized as a novel nanocombination for inducing apoptosis in vitro and in vivo.

A randomised phase II trial of docetaxel versus docetaxel plus carboplatin in patients with castration-resistant prostate cancer who have progressed after response to prior docetaxel chemotherapy: The RECARDO trial

BACKGROUND

Docetaxel is standard first-line chemotherapy for patients with metastatic castration-resistant prostate carcinoma (mCRPC). Docetaxel re-challenge has never been tested in a prospective randomised controlled study. As some studies support the addition of carboplatin to docetaxel, we performed a phase II trial investigating the combination of docetaxel plus carboplatin versus docetaxel re-treatment in docetaxel pre-treated mCRPC patients.

METHODS

Patients with mCRPC with a progression-free interval of ≥3 months after initial docetaxel treatment were randomised between docetaxel 75 mg/m² or docetaxel 60 mg/m² plus carboplatin AUC4. The primary end-point was progression-free survival (PFS; PSA/RECIST).

RESULTS

Owing to insufficient recruitment, the study was discontinued early after inclusion of 75 patients (targeted 150) PFS and overall survival (OS) were comparable between both groups (median PFS 12.7 months (95% CI 9.9-17.5 months) with docetaxel monotherapy and 11.7 months (95% CI 8.5-21.0 months) with combination therapy (p = 0.98); OS 18.5 months (95% CI 11.8-24.5 months) versus 18.9 months (95% CI 16.0-23.7 months) (p = 0.79). An interim analysis (SEQTEST) showed that the null hypothesis could already be excepted, and no significant difference between both study arms was expected if inclusion would be completed. The incidence of grade 3-4 infections and gastrointestinal side-effects was numerical higher in the carboplatin arm (p = 0.056).

CONCLUSION

This early terminated study suggests no benefit from the addition of carboplatin to docetaxel re-treatment in patients with mCRPC, whereas the combination resulted in more toxicity. Re-treatment with docetaxel monotherapy appears to be feasible, save and effective for patients with mCRPC and an initial good response to docetaxel.

TRIAL REGISTRATION

NTR3070.

Anti-tumour activity of platinum compounds in advanced prostate cancer-a systematic literature review

BACKGROUND

For men with advanced castration-resistant prostate cancer (CRPC), several treatment options are available, including androgen receptor (AR) pathway inhibitors (abiraterone acetate, enzalutamide), taxanes (docetaxel, cabazitaxel) and the radionuclide (radium-223). However, cross-resistance is a clinically relevant problem. Platinum compounds have been tested in a number of clinical trials in molecularly unselected prostate cancer patients. Advances in CRPC molecular profiling have shown that a significant proportion of patients harbour DNA repair defects, which may serve as predictive markers for sensitivity to platinum agents.

OBJECTIVE

To systematically identify and analyse clinical trials that have evaluated platinum agents in advanced prostate cancer patients.

METHODS

PubMed was searched to identify published clinical trials of platinum agents in advanced prostate cancer. The PRIMSA statement was followed for the systematic review process. Identified trials are analysed for study design, statistical plan, assessments of anti-tumour activity and the potential value of predictive biomarkers.

RESULTS

A total of 163 references were identified by the literature search and 72 publications that met the selection criteria were included in this review; of these 33 used carboplatin, 27 cisplatin, 6 satraplatin, 4 oxaliplatin and 2 other platinum compounds. Overall, anti-tumour activity varies in the range of 10%-40% for objective response and 20%-70% for PSA decline ≥50%. Response seemed highest for the combinations of carboplatin with taxanes or oxaliplatin with gemcitabine. The interpretation of the clinical data is limited by differences in response criteria used and patient populations studied.

CONCLUSION

Platinum compounds have moderate anti-tumour activity in molecularly unselected patients with advanced prostate cancer. Translational evidence of DNA repair deficiency should be leveraged in future studies to select prostate cancer patients most likely to benefit from platinum-based therapy.

Functional analysis of the TMPRSS2:ERG fusion gene in cisplatin‑induced cell death

The TMPRSS2:E‑twenty‑six (ETS) gene fusion occurs frequently in a high proportion of patients with prostate cancer (PCa) in Western countries, and the aberrant expression of TMPRSS2: v‑ETS avian erythroblastosis virus E26 oncogene homolog (ERG), the most common form of the corresponding protein, can regulate cell migration and contribute to tumor invasion and metastasis. However, its association with other cellular events, and in particular, cell death, remain unknown. To examine the function of such fusion genes, an expression plasmid containing the TMPRSS2:ERG (T1/E5) sequence (ΔERG) from a patient sample was constructed and transiently transfected into DU145 cells, which do not express the fusion gene. It was found that the overexpression of ΔERG significantly inhibited the ability of cisplatin to induce apoptosis in DU145 cells. By contrast, VCaP cells, which do contain TMPRSS2:ERG, were sensitized to cisplatin‑induced apoptosis through siRNA inhibition of the fusion gene. To elucidate the underlying mechanism, a stable cell line expressing the ΔERG gene was constructed. Expression of ΔERG did not affect cell migration, but did protect cells from DNA damage and apoptosis induced by cisplatin. Furthermore, knockdown of ΔERG by short interfering RNA resulted in cells regaining their sensitivity to cisplatin. Finally, the gene coding for activating transcription factor 5, which is important for cell survival, may be upregulated by ΔERG. Taken together, these data point to a new function of the TMPRSS2:ERG fusion gene in regulating the apoptotic pathway.

Hydrogen bonding and anticancer properties of water-soluble chiral p-cymene Ru(II) compounds with amino-oxime ligands

The investigation of the hydrogen-bonding effect on the aggregation tendency of ruthenium compounds [(η⁶-p-cymene)Ru(κNHR,κNOH)Cl]Cl (R = Ph (1a), Bn (1b)) and [(η⁶-p-cymene)Ru(κ²NH(2-pic),κNOH)][PF₆]₂ (1c), [(η⁶-p-cymene)Ru(κNHBn,κNO)Cl] (2b) and [(η⁶-p-cymene)Ru(κNBn,κ²NO)] (3b), has been performed by means of concentration dependence ¹H NMR chemical shifts and DOSY experiments. The synthesis and full characterization of new compounds 1c, [(η⁶-p-cymene)Ru(κNPh,κ²NO)] (3a) and 3b are also reported. The effect of the water soluble ruthenium complexes 1a-1c on cytotoxicity, cell adhesion and cell migration of the androgen-independent prostate cancer PC3 cells have been assessed by MTT, adhesion to type-I-collagen and recovery of monolayer wounds assays, respectively. Interactions of 1a-1c with DNA and human serum albumin have also been studied. Altogether, the properties reported herein suggest that ruthenium compounds 1a-1c have considerable potential as anticancer agents against advanced prostate cancer.

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.

[Castration-resistant prostate cancer (CRPC)]

In merely a short period of time the comprehension of castration-resistant prostate cancer has evolved. It is now possible to clearly outline the exact definition and variance of the disease pattern. A wealth of new effective agents can be applied to extend the patient's life span and improve the quality of life. An understanding of the pharmacodynamics and side effects of each substance is of utmost importance for the practical application. In order to use these new medicines in a differentiated manner urologists require continuous education. The evaluation of response to treatment has yet to be satisfyingly verified. Molecular markers still need to be developed and evaluated.

Natural compounds to overcome cancer chemoresistance: toxicological and clinical issues

INTRODUCTION

Defects in initiating or executing cell death programs are responsible for cancer chemoresistance. The growing understanding of apoptotic programs suggests that compounds simultaneously inhibiting multiple signaling pathways might provide a better therapeutic outcome than that of individual inhibitors.

AREAS COVERED

Natural compounds can modulate different survival pathways, thus enhancing the therapeutic effects of anticancer treatments. This review provides an overview of the preclinical and clinical relevance of chemosensitization, giving special reference to curcumin (CUR) and sulforaphane (SFN) as agents to overcome apoptosis resistance against chemotherapy.

EXPERT OPINION

Even if CUR and SFN are common dietary constituents, they are characterized by several problems still unresolved and hampering their development as anticancer drugs. For a drug to be safe, it must be devoid of toxicity, and some studies conducted to date raises concern about CUR and SFN safety. Moreover, the efficacy of a drug, alone or in association, is usually determined by randomized, placebo-controlled, double-blind clinical trials. No such trials have shown CUR and SFN to be effective so far. Thus, caution should be exercised when suggesting the use of CUR or SFN for cancer-related therapeutic purpose, especially for very early stage of malignancy, or in patients who are undergoing chemotherapy.

Gemcitabine-oxaliplatin plus prednisolone is active in patients with castration-resistant prostate cancer for whom docetaxel-based chemotherapy failed

Background:

There has been no previous study on the activity of gemcitabine in combination with oxaliplatin (GemOx) for castration-resistant prostate cancer (CRPC).

Methods:

The GemOx was preclinically tested for cytotoxic activity in human prostate cancer cell lines. Clinically, patients with CRPC who failed prior docetaxel were treated with gemcitabine 1000 mg m⁻² and oxaliplatin 100 mg m⁻² intravenously every 2 weeks and prednisolone 5 mg orally twice daily. The primary end point was the prostate-specific antigen (PSA) response rate.

Results:

The GemOx displayed synergistic effects based on Chou and Talalay analysis. In the phase II study, 33 patients were accrued. The median dose of docetaxel exposure was 518 mg m⁻². A total of 270 cycles were administered with a median of eight cycles per patient. A PSA response rate was 55% (95% CI, 38–72) and radiologic response rate was 82% (9 out of 11). With a median follow-up duration of 20.5 months, the median time to PSA progression was 5.8 months (95% CI, 4.4–7.2) and the median overall survival was 17.6 months (95% CI, 12.6–22.6). The most frequently observed grade 3 or 4 toxicities were neutropenia (13%) and thrombocytopenia (13%).

Conclusions:

The GemOx is active and tolerable in patients with metastatic CRPC after docetaxel failure (NCT 01487720).

Cisplatin : an old drug with a newfound efficacy -- from mechanisms of action to cytotoxicity

INTRODUCTION

Cisplatin is a highly effective antineoplastic drug with an extremely current mechanism of action. Cisplatin-induced side effects are dose-dependent and limit the administration of increased dosages, thus compromising its therapeutic efficacy.

AREAS COVERED

This review aims to describe the emerging knowledge about the biochemical mechanisms that mediate cisplatin cytotoxicity and side effects. A specific section is devoted to discuss the pathogenesis of cisplatin-related toxicities and the potential measures to counteract them.

EXPERT OPINION

Although cisplatin has been used for a long time, only recently its exact mechanism of action has been better defined. The cytotoxic activity of cisplatin is largely dependent on the glycolytic metabolism of tumor cells: cisplatin redirects cancer cells to oxidative phosphorylation from the 'Warburg effect', which is considered one of the most important mechanisms of tumor cell survival. The interference of cisplatin with glucose metabolism is also a cause of its relevant toxicities. The emerging knowledge on the complex mechanisms, which mediate cisplatin cytotoxicity and side effect, may lead to a more appropriate and safe use of this drug. Further studies are warranted to define and implement its effectiveness in combination with targeted drugs able to interfere with cellular energy metabolism, such as mTOR inhibitors.

An open-label, dose-finding study of the combination of satraplatin and gemcitabine in patients with advanced solid tumors

Purpose: Satraplatin is a third generation oral platinum, which has demonstrated antitumor activity. The aim of this phase I study was to determine the maximum tolerated dose (MTD) of the combination of satraplatin and gemcitabine in patients previously treated with chemotherapy and in patients without prior chemotherapy. Patients and Methods: Two separate MTDs were planned in two different patient groups (those with and without prior chemotherapy treatment). Dose escalations were planned in cohorts of three patients. Tumor measurements were obtained every two cycles. Assessment of response was performed according to Response Evaluation Criteria in Solid Tumors (RECIST criteria v.1.0). Results: Thirty subjects were enrolled. A MTD of gemcitabine 1000 mg/m² days 1 and 8 plus satraplatin 60 mg/m² days 1–3, every 21 days was determined in the prior chemotherapy group. No MTD could be determined for the no prior chemotherapy group treated with this schedule. Five patients completed 12 treatment cycles; 22 serious adverse events (SAE) were observed. Although not an entry criteria, overall confirmed response was observed in 17 (24%) evaluable patients (complete response, CR = 1 and partial response, PR = 3) and in 3/7 (43%) patients with measure prostate cancer lesions. Conclusions: In this phase Ib study, the combination of satraplatin and gemcitabine demonstrated to be safe and efficacious in particular in patients with prostate cancer.

Evaluation of cisplatin in combination with β-elemene as a regimen for prostate cancer chemotherapy

Cisplatin is one of the most potent chemotherapeutic agents for the treatment of many types of solid tumours. Nevertheless, it is not the first-line drug for prostate cancer chemotherapy, because prostate tumour cells exhibit intrinsic and acquired resistance to cisplatin. We have previously demonstrated that β-elemene, a novel plant-derived anti-neoplastic with low toxicity, inhibits lung and ovarian carcinoma cell growth in vitro. In the present study, we explored the therapeutically chemosensitizing effect of β-elemene on cisplatin anti-tumour efficacy in androgen-independent prostate cancer cells as well as the underlying mechanism. β-Elemene significantly increased cisplatin cytotoxicity in the androgen-independent prostate carcinoma cell lines DU145 and PC-3. In addition, β-elemene markedly promoted cisplatin-induced apoptotic cell death in both cell lines, as determined by three different apoptosis assays. β-Elemene augmented the cisplatin-induced activation of caspase-3/7/10 and caspase-9, cleavage of caspase-3 and -9, suppression of Bcl-2 and Bcl-X(L) expression, and release of cytochrome c from mitochondria in these cells. Thus, β-elemene enhancement of cisplatin-induced apoptosis via mitochondrial activation of the caspase-mediated apoptotic pathway may account for the augmented anti-cancer potency of cisplatin in prostate cancer. Cisplatin combined with β-elemene as a chemosensitizer or adjuvant warrants further study and may be potentially useful as a first-line treatment of androgen-independent prostate carcinomas.

Cytotoxicity of triphenyltin(IV) methyl- and ethylisopropyldithiocarbamate compounds in chronic myelogenus leukemia cell line (K-562)

Studies on the discovery of new cancer treatment by using metal-based compounds such as tin (Sn) has now greatly being synthesized and evaluated to identify their effectiveness and suitability to be developed as a new anticancer drug.

APPROACH

This study was carried out to evaluate the cytotoxicity of triphenyltin(lV) methylisopropyldithiocarbamate (compound 1) and triphenyltin(IV) ethylisopropyldithiocarbamate (compound (2) on chronic myelogenus leukemia cells. The determination of their cytotoxicity (IC50) at different time of exposure and concentration was carried out through the employment of 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide (MTT) assay.

RESULTS

The IC50 values obtained for compound 1 and 2 following treatment at 24, 48 and 72 h were 0.660, 0.223, 0.370 microM and 0.677, 0.306, 0.360 microM, respectively. Cell morphological changes such as apoptotic and necrotic features were also been observed.

CONCLUSION

The compounds tested were found to give cytotoxic effect against chronic myelogenus leukemia (K-562) cell at a micromolar dose. Thus, further study on their specific mechanism of actions in the human cells should be carried out to elucidate their potential as an anticancer agent.

Second-line therapy for castrate-resistant prostate cancer: a literature review

Despite a survival benefit in the first-line treatment of castrate-resistant prostate cancer (CRPC) with docetaxel, the prognosis remains limited. There are increasing options available for patients with CRPC in the second-line setting, but there is currently little consensus regarding the optimal treatment. There have been numerous phase II and retrospective studies examining second-line options in CRPC, including retreatment with docetaxel, mitoxantrone, cyclophosphamide and carboplatin, which can be associated with meaningful responses in a significant minority of patients. In 2010 three randomized trials were published or presented which demonstrated a survival benefit in the second-line setting. These included cabazitaxel compared with mitoxantrone, sipuleucel-T (immunotherapy) and abiraterone acetate versus placebo. Ongoing research in the second-line setting of CRPC to optimize treatment options, with the objectives of survival prolongation, improvement in quality of life and pain management, is still needed.

Clinical and pharmacokinetic evaluation of satraplatin

INTRODUCTION

The toxicities of cisplatin, that is, nephrotoxicity, neurotoxicity and emesis, provided the impetus for the development of more tolerable platinum analogs. Satraplatin is an investigational third-generation orally available lipophilic platinum, which has demonstrated safety and antitumor activity in multiple settings.

AREAS COVERED

The clinical activity of satraplatin in metastatic castrate-resistant prostate cancer (mCRPC), breast, lung and other advanced solid tumors is discussed with a focus on its pharmacokinetic properties. The article was formulated using publications found through PubMed search in addition to presentations given at major conferences.

EXPERT OPINION

Satraplatin was associated with dose-limiting myelosuppression, but no significant ototoxicity, neurotoxicity or nephrotoxicity. Despite the activity of satraplatin in mCRPC, survival was not extended in an unselected population included in a Phase III trial. While further development of satraplatin in large Phase III trials is not planned at this time, efforts are ongoing to develop tailored therapy in mCRPC based on excision repair cross-complementing group 1 expression or BRCAness. Moreover, based on potentially better central nervous system penetration due to lipophilicity, evaluation in patients with brain tumors is ongoing. Given the favorable toxicity profile and convenient oral administration, satraplatin may warrant development in settings that preclude cisplatin, for example, underlying renal dysfunction, elderly age and poor performance status.

Cabazitaxel for the treatment of castration-resistant prostate cancer

Treatment with docetaxel-based chemotherapy results in improved survival in patients with metastatic castration-resistant prostate cancer. However, all patients eventually develop progressive disease associated with poor outcomes. In this article, we discuss the available second-line therapeutic options following docetaxel, with a special focus on cabazitaxel, which is the first agent to yield extended survival as second-line therapy following docetaxel. Cabazitaxel, a novel semi-synthetic taxane, is effective even in docetaxel-resistant model systems. Recently, results of the Phase III TROPIC trial demonstrated improved survival with cabazitaxel plus prednisone compared with mitoxantrone and prednisone in patients with progressive metastatic castration-resistant prostate cancer, following prior docetaxel, which led to approval by the US FDA.

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

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

Chemotherapy-based treatment for castration-resistant prostate cancer

Most men with metastatic prostate cancer respond to various types of androgen ablation but progress to castration-resistant disease. The TAX 327 and Southwest Oncology Group (SWOG) 99-16 clinical trials established docetaxel-based chemotherapy as preferred first-line treatment for most men with symptomatic metastatic castration-resistant prostate cancer (mCRPC). However, only about half receive benefit from docetaxel, and those who respond initially progress and eventually die of (or with) mCRPC. Both cellular mechanisms and the tumor microenvironment are implicated in the development of resistance to docetaxel. New agents are being evaluated for men with mCRPC, either as first-line treatment in combination with docetaxel, or in men progressing during or after treatment with docetaxel. Thus far, agents evaluated in phase III trials in combination with docetaxel have not improved outcome, including the vaccine GVAX, high-dose vitamin D (DN-101), and the antiangiogenic agent bevacizumab. In contrast, cabazitaxel, a taxane that is not cross-resistant to docetaxel, substantially improved the outcome of men progressing during or after treatment with docetaxel-based chemotherapy when compared with mitoxantrone and prednisone. However, translation of benefit of cabazitaxel demonstrated in the TROPIC (Treatment of Hormone-Refractory Metastatic Prostate Cancer) trial into general oncologic practice will be challenging because this agent may cause serious toxicity. With the approval of less toxic hormonal agents (eg, abiraterone acetate) in the setting of docetaxel-resistant mCRPC, clinicians will have an opportunity to balance benefits and harms of new agents in an individual patient and may be able to use different agents in sequence.

Germline BRCA mutation does not prevent response to taxane-based therapy for the treatment of castration-resistant prostate cancer

OBJECTIVE

• To investigate the relationship between BRCA mutation status and response to taxane-based chemotherapy, since BRCA mutation carriers with prostate cancer appear to have worse survival than non-carriers and docetaxel improves survival in patients with castration-resistant prostate cancer.

PATIENTS AND METHODS

• We determined BRCA mutation prevalence in 158 Ashkenazi Jewish (AJ) men with castration-resistant prostate cancer. Clinical data were collected as part of an institutional prostate cancer research database and through additional medical record review. • Clinical records and DNA samples were linked through a unique identifier, anonymizing the samples before genetic testing for the AJ BRCA1/2 founder mutations. • Response to taxane-based therapy was defined by the prostate-specific antigen nadir within 12 weeks of therapy.

RESULTS

• In all, 88 men received taxane-based treatment, seven of whom were BRCA carriers (three BRCA1, four BRCA2; 8%). Initial response to taxane was available for all seven BRCA carriers and for 69 non-carriers. • Overall, 71% (54/76) of patients responded to treatment, with no significant difference between carriers (57%) and non-carriers (72%) (absolute difference 15%; 95% confidence interval -23% to 53%; P= 0.4). • Among patients with an initial response, the median change in prostate-specific antigen was similar for BRCA carriers (-63%, interquartile range -71% to -57%) and non-carriers (-60%, interquartile range -78% to -35%) (P= 0.6). • At last follow-up, all seven BRCA carriers and 49 non-carriers had died from prostate cancer. One BRCA2 carrier treated with docetaxel plus platinum survived 37 months.

CONCLUSION

• In this small, hypothesis-generating study approximately half of BRCA carriers had a prostate-specific antigen response to taxane-based chemotherapy, suggesting that it is an active therapy in these individuals.

Prognostic significance of focal neuroendocrine differentiation in prostate cancer: cases with autopsy-verified cause of death

AIMS

This study was designed to evaluate the prognostic significance of focal chromogranin A (cgA) expression in prostate cancer in a series of cases with autopsy-verified cause of death.

METHODS AND RESULTS

Seventy seven autopsy-verified cases of prostate cancer were identified, 41 cases with metastatic disease and 36 with nonmetastatic disease at autopsy. Immunohistochemical analysis for cgA was performed in 40 cases on the archived diagnostic biopsies taken during the patients' lifetime. After exclusion of a single case of carcinoid tumor, 14 of the 18 (78%) metastatic and none of the 21 (0%) nonmetastatic tumors showed focal neuroendocrine differentiation (NED). The Gleason score and focal cgA expression further increased the accuracy of the prediction of the outcome, as all the cases with focal NED associated with high Gleason score had metastatic disease in contrast to cases without cgA-expression and low Gleason score, all of which were non-metastatic.

CONCLUSIONS

Focal NED seems to be a powerful negative prognostic parameter in prostate adenocarcinomas. The outcome of the disease in prostate cancer can be accurately predicted based on focal NED of the tumor cells either alone or in combination with Gleason score.

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

CONTEXT

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

OBJECTIVE

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

EVIDENCE ACQUISITION

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

EVIDENCE SYNTHESIS

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

CONCLUSIONS

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

Enhancing tumor-specific uptake of the anticancer drug cisplatin with a copper chelator

Uptake of the anticancer drug cisplatin is mediated by the copper transporter CTR1 in cultured cells. Here we show in human ovarian tumors that low levels of Ctr1 mRNA are associated with poor clinical response to platinum-based therapy. Using a mouse model of human cervical cancer, we demonstrate that combined treatment with a copper chelator and cisplatin increases cisplatin-DNA adduct levels in cancerous but not in normal tissues, impairs angiogenesis, and improves therapeutic efficacy. The copper chelator also enhances the killing of cultured human cervical and ovarian cancer cells with cisplatin. Our results identify the copper transporter as a therapeutic target, which can be manipulated with copper chelating drugs to selectively enhance the benefits of platinum-containing chemotherapeutic agents.

beta-Cyclodextrin-curcumin self-assembly enhances curcumin delivery in prostate cancer cells

Curcumin, a hydrophobic polyphenolic compound derived from the rhizome of the herb Curcuma longa, possesses a wide range of biological applications including cancer therapy. However, its prominent application in cancer treatment is limited due to sub-optimal pharmacokinetics and poor bioavailability at the tumor site. In order to improve its hydrophilic and drug delivery characteristics, we have developed a beta-cyclodextrin (CD) mediated curcumin drug delivery system via encapsulation technique. Curcumin encapsulation into the CD cavity was achieved by inclusion complex mechanism. Curcumin encapsulation efficiency was improved by increasing the ratio of curcumin to CD. The formations of CD-curcumin complexes were characterized by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA), scanning electron microscope (SEM), and transmission electron microscope (TEM) analyses. An optimized CD-curcumin complex (CD30) was evaluated for intracellular uptake and anti-cancer activity. Cell proliferation and clonogenic assays demonstrated that beta-cyclodextrin-curcumin self-assembly enhanced curcumin delivery and improved its therapeutic efficacy in prostate cancer cells compared to free curcumin.

Carboplatin plus weekly docetaxel as salvage chemotherapy in docetaxel-resistant and castration-resistant prostate cancer

BACKGROUND

There is no proven, effective, standard second-line chemotherapy for castration- and docetaxel-resistant prostate cancer (DRPC). Recent data suggest that carboplatin may be effective in combination with docetaxel in this setting; however, the optimal docetaxel/carboplatin-based regimen is still unclear.

AIM OF THE STUDY

We identified 43 consecutive patients with DRPC treated with carboplatin (AUC5 d1) and docetaxel (35 mg/m(2) d1, 8, 15 q4w i.v.) as a second-line or subsequent salvage chemotherapy until discontinuation of therapy due to disease progression or unacceptable toxicity.

RESULTS

Decreased prostate-specific antigen (> or =50% PSA) was observed in 22/43 (51.2%, 95% CI, 35.5, 66.7%) patients, with > or =90% reduction in 12/43 patients (27.9%). At the time of analysis, the median follow-up time for all patients was 10.4 months. Median progression-free survival (PFS) for all patients was 6.5 months (95% CI 4.1, 8.9), and median overall survival (OS) was 15.8 months (95% CI 12.1, 18.5). In PSA responders, PFS was 9.5 (95% CI 8.2, 19.0) months versus 3.3 (95% CI 2.6, 4.0) months in PSA non-responders (P < 0.0001; hazard ratio (HR) 0.108) and OS was 24.4 months (95% CI 19.5, 29.4) versus 7.8 (95% CI 5.2, 10.3) months (P = 0.001; HR 0.232). Established prognostic factors were associated with survival. This regimen was reasonably well tolerated, with leukopenia/neutropenia as the most common reversible grade 3/4 toxicity (41.9/39.5%).

CONCLUSION

These data suggest that weekly docetaxel plus carboplatin may be an important therapeutic second-line treatment option for patients with DRPC.

Docetaxel-ST1481 sequence exerts a potent cytotoxic activity on hormone-resistant prostate cancer cells by reducing drug resistance-related gene expression

BACKGROUND

The efficacy of current therapy for hormone-refractory prostate cancer is still unsatisfactory and new agents and therapeutic modalities are needed. The aims of the present work were to examine the in vitro activity and mechanisms of action of different antitumor drug combinations in hormone-resistant prostate cancer (HRPC) cell lines.

METHODS

The activity of docetaxel (Doc), cisplatin (Cis), oxaliplatin (Oxa), SN-38 and ST1481, singly or in combination, was assessed in different HRPC cell lines (PC3, parental DU145 and taxane-resistant DU145-R) by SRB test. Apoptosis was evaluated by TUNEL and ANN-V assays. Extrusion pump activity was studied by Hoechst 33342 assay, while gene expression related to drug efflux mechanisms and DNA damage repair was analyzed by RT-PCR.

RESULTS

Doc induced a high cytocidal effect in the HRPC cells, whereas Cis, Oxa, SN-38 and ST1481 exerted prevalently cytostatic activity. Doc followed by ST1481 proved to be the most effective drug sequence among those investigated, producing an important synergistic effect (R.I. from 2.0 to 5.2) in all the tested cell lines. Moreover, this sequence induced a significant downregulation of xenobiotic extrusion pump and DNA damage repair gene expression. ST1481 synergistically increased the cytocidal effect of Doc, probably through a downregulation of extrusion pump activity and DNA damage repair-related genes.

CONCLUSIONS

Our results show that the Doc --> ST1481 sequence effectively reduces the cancer cell population and restores Doc activity in taxane-resistant HRPC, indicating its potential usefulness as first- or second-line treatment of hormone-refractory prostate cancer.

Emerging drugs for prostate cancer

Prostate cancer mortality usually occurs as a result of castrate resistant disease. Many approaches are currently being evaluated to improve the treatment of this condition. These include drugs that induce androgen deprivation, that is, LHRH antagonists; more active or less toxic chemotherapy agents; immunologic approaches, including passive and active immunization; drugs that target the androgen receptor and/or androgen synthesis; drugs that target specific pathways, including tyrosine kinase inhibitors, angiogenesis inhibitors, endothelin antagonists and matrix metalloproteinase inhibitors; and antioxidants and cell cycle inhibitors. Many of these agents seem promising. The rationale, biologic activity and therapeutic results of these emerging drugs are reviewed.

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.

Enhancement of the activity of phenoxodiol by cisplatin in prostate cancer cells

Phenoxodiol is a novel isoflav-3-ene, currently undergoing clinical trials, that has a broad in vitro activity against a number of human cancer cell lines. Phenoxodiol alone inhibited DU145 and PC3 in a dose- and time-dependent manner with IC₅₀ values of 8±1 and 38±9 μM, respectively. The combination of phenoxodiol and cisplatin was synergistic in DU145, and additive in PC3, as assessed by the Chou–Talalay method. Carboplatin was also synergistic in combination with phenoxodiol in DU145 cells. The activity of the phenoxodiol and cisplatin combination was confirmed in vivo using a DU145 xenograft model in nude mice. Pharmacokinetic data from these mice suggest that the mechanism of synergy may occur through a pharmacodynamic mechanism. An intracellular cisplatin accumulation assay showed a 35% (P<0.05) increase in the uptake of cisplatin when it was combined in a ratio of 1 μM: 5 μM phenoxodiol, resulting in a 300% (P<0.05) increase in DNA adducts. Taken together, our results suggest that phenoxodiol has interesting properties that make combination therapy with cisplatin or carboplatin appealing.

PCPH/ENTPD5 expression confers to prostate cancer cells resistance against cisplatin-induced apoptosis through protein kinase Calpha-mediated Bcl-2 stabilization

Prostate cancer (PCa) frequently develops antiapoptotic mechanisms and acquires resistance to anticancer drugs. Therefore, identifying PCa drug resistance determinants should facilitate designing more effective chemotherapeutic regimens. Recently, we described that the PCPH protein becomes highly expressed in human prostatic intraepithelial neoplasia and in PCa, and that the functional interaction between PCPH and protein kinase Cdelta (PKCdelta) increases the invasiveness of human PCa. Here, we report that the functional interaction between PCPH and a different PKC isoform, PKCalpha, confers resistance against cisplatin-induced apoptosis to PCa cells. This interaction elicits a mechanism ultimately resulting in the posttranslational stabilization and subsequent elevated expression of Bcl-2. Stable knockdown of either PCPH, mt-PCPH, or PKCalpha in PCa cells decreased Ser70-phosphorylated Bcl-2 and total Bcl-2 protein, thereby increasing their cisplatin sensitivity. Conversely, forced expression of the PCPH protein or, in particular, of the mt-PCPH oncoprotein increased the levels of phosphorylated PKCalpha concurrently with those of Ser70-phosphorylated and total Bcl-2 protein, thus promoting cisplatin resistance. Consistently, Bcl-2 knockdown sensitized PCa cells to cisplatin treatment and, more importantly, reversed the cisplatin resistance of PCa cells expressing the mt-PCPH oncoprotein. Moreover, reexpression of Bcl-2 in PCPH/mt-PCPH knockdown PCa cells reversed the cisplatin sensitization caused by PCPH or mt-PCPH down-regulation. These findings identify PCPH and mt-PCPH as important participants in the chemotherapy response of PCa cells, establish a role for PCPH-PKCalpha-Bcl-2 functional interactions in the drug response process, and imply that targeting PCPH expression before, or simultaneously with, chemotherapy may improve the treatment outcome for PCa patients.

Current status and future prospects for satraplatin, an oral platinum analogue

Platinum drugs are major chemotherapeutic agents that are used alone or in combination with other systemic agents and/or radiation therapy in the management of many human malignancies. All three platinum drugs approved by the Food and Drug Administration, cisplatin, carboplatin, and oxaliplatin, are administrated intravenously. Satraplatin is the first orally administered platinum drug under active clinical investigation. Satraplatin and its major metabolite, JM118, have shown antineoplastic activity in in vitro, in vivo, and in clinical settings. Use of satraplatin as an alternative platinum cytotoxic agent is particularly attractive because of the convenience of administration, milder toxicity profile, lack of cross-resistance with cisplatin, theoretical advantage as a radiosensitizer, and activity in cancers historically nonresponsive to platinum drugs. The most mature clinical data for satraplatin come from the recently completed phase III trial that investigated the efficacy of satraplatin and prednisone on hormone-refractory prostate cancer patients who had failed a course of other chemotherapy agents. Preliminary reports show that the combination is statistically superior to placebo and prednisone in multiple end points, including progression-free survival, prostate-specific antigen response, objective tumor response, pain response, and duration of pain response. The difference in overall survival, however, did not reach statistical significance.

Molecular targeting of Bcl-2 overcomes prostate cancer cell adaptation to XIAP gene downregulation

X-linked inhibitor of apoptosis (XIAP) is a suppressor of apoptosis that supports an increased survival and resistance to chemotherapy of human prostate cancer (PCa) cells. Effects of transient (24 h) and chronic (beyond 1 month) downregulation of XIAP in DU145 hormone refractory prostate cancer (HRPC) cells were studied. We found that transient downregulation of XIAP by siRNAs resulted in an increase of apoptosis and a decrease in Bcl-2 levels and sensitized PCa cells to cisplatin. XIAP downregulation by shRNA vector stable transfection led to upregulation of Bcl-2 protein. Our results identify the adaptability of PCa cells to chronic loss of XIAP in part through upregulation of Bcl-2 and indicate that multitargeting approach is the most effective application in the chemotherapy of human HRPC.

Induction of multinucleated cells and apoptosis in the PC-3 prostate cancer cell line by low concentrations of polyethylene glycol 1000

Polyethylene glycol (PEG) has been reported to inhibit the development of colonic lesions in carcinogen-treated rats when administered orally. However, the precise mechanism for the chemopreventive activity of PEG remains largely elusive. Based on a characteristic feature of PEG as a 'fusogen', we investigated its potential as a chemotherapeutic agent through the induction of multinucleated cell formation and apoptosis induction in PC-3 prostate cancer cells. When PC-3 cells were treated with 0.5 and 1.0% PEG 1000, multinucleated cells were induced at a frequency of 8.4 and 13%, respectively, 36 h after PEG treatment under high cell density (1 x 10(6) cells in 100 microL PEG solution) in vitro. Although abnormality of cell cycle progression was not evident in PEG-treated PC-3 cells, multinucleated cells substantially disappeared at around 38 h due to apoptosis. In contrast, no apparent growth suppression was observed when PC-3 cells were exposed to up to 1.0% PEG at a much lower cell density, namely under ordinary culture conditions. Furthermore, injection of 0.5% PEG solution in vivo into PC-3 xenografts implanted in BALB/c-nu/nu male mice significantly suppressed tumor growth compared to phosphate-buffered saline injection. Multinucleated TdT-mediated dUTP-biotin nick end-labeling (TUNEL)-positive cells were observed inside the PEG-injected tumors. PEG was here demonstrated to have anticell proliferation and antitumor effects via induction of apoptosis, possibly by cell fusion. PEG injection therapy could therefore be adopted as an alternative chemotherapeutic strategy for localized prostate cancers, including those that become refractory to androgen-deprivation therapy.

Therapeutic options for hormone-refractory prostate cancer in 2007

Prostate cancer is the most commonly diagnosed cancer in American men and a major health problem. While localized disease has an excellent chance for cure, metastatic disease leads to androgen-independent progression and death within a few years. Although docetaxel represents an important therapeutic milestone and is the current standard of care for metastatic hormone-refractory prostate cancer (HRPC), most patients eventually progress because of clonal selection of therapy-resistant cells or the development of cells with a drug-resistant phenotype. By understanding the molecular basis of resistance to androgen withdrawal and chemotherapy, the rational design of targeted therapeutics is possible. Over the last few years, many gene targets that regulate apoptosis, proliferation, and cell signalling have been identified, and numerous novel compounds have entered clinical trials either as single agents or in combination with cytotoxic chemotherapy. Neoadjuvant trials in particular must be further encouraged since they allow detection of biological activity in the prostatectomy specimen. This article reviews new treatment options available for men with advanced prostate cancer. Even though HRPC remains incurable, it is not untreatable. Recent findings are very promising, but challenges remain in demonstrating effective anti-tumor activity and showing a clinically relevant survival benefit in Phase III trials.

Conjugated platinum(IV)-peptide complexes for targeting angiogenic tumor vasculature

The integrins alpha vbeta3 and alpha vbeta5 and the membrane-spanning surface protein aminopeptidase N (APN) are highly expressed in tumor-induced angiogenesis, making them attractive targets for therapeutic intervention. Both integrins and APN recognize a broad range of peptides containing RGD (Arg-Gly-Asp) and NGR (Asn-Gly-Arg) motifs, respectively. Here, we describe the design, synthesis, and characterization of a series of mono- and difunctionalized platinum(IV) complexes in which a conjugated peptide motif, containing RGD, (CRGDC)c, (RGDfK)c, or NGR, is appended as a "tumor-homing device" to target tumor endothelial cells selectively over healthy cells. Platinum(IV)-peptide complexes with nonspecific amino acids or peptide moieties were prepared as controls. Concentration-response curves of these compounds were evaluated against primary proliferating endothelial cells and tumor cell lines and compared to those of cisplatin, a well-described platinum-based chemotherapeutic agent. The Pt(IV)-RGD conjugates were highly and specifically cytotoxic to cell lines containing alpha vbeta3 and alpha vbeta5, approaching the activity of cisplatin. The Pt(IV)-NGR complexes were less active than Pt(IV)-RGD-containing compounds but more active than nonspecific Pt-peptide controls. Integrin alpha vbeta3 mediated, at least in part, the anti-proliferative effect of a Pt(IV)-RGD conjugate, as demonstrated by a decreased inhibitory response when endothelial cells were either (1) incubated with an excess of alpha vbeta3/alpha vbeta5-specific RGD pentapeptides or (2) transfected with RNAi for beta 3, but not beta 1, integrins. These results suggest a rational approach to improved chemotherapy with Pt(IV)-peptide conjugates by selective drug delivery to the tumor compartment.