Phase I trial of docetaxel with estramustine in androgen-independent prostate cancer

Circular RNAs and Drug Resistance in Genitourinary Cancers: A Literature Review

Simple Summary

Drug resistance to systematic treatment in genitourinary tumors severely aggravated the burden on patients and society. Multiple mechanisms were involved in drug resistance. As typical non-coding RNAs, circRNAs play a critical role in the onset and development of cancers and several studies implied their function in the regulation of drug resistance. Here, we reviewed the investigations of circRNAs’ behavior in drug resistance of genitourinary cancers and summarized the underlying mechanisms. This review emphasized the essential role of circRNAs in drug resistance development and also pointed out the potential topics that need further investigations in the future.

Abstract

In recent years, systematic treatment has made great progress in genitourinary tumors. However, some patients develop resistance to the treatments, resulting in an increase in mortality. Circular RNAs (circRNAs) form a class of non-coding RNAs with high stability and significant clinical relevance. Accumulating evidence indicates that circRNAs play a vital role in cancer development and tumor chemotherapy resistance. This review summarizes the molecular and cellular mechanisms of drug resistance mediated by circRNAs to common drugs used in the treatment of genitourinary tumors. Several circRNAs were identified to regulate the responsiveness to systemic treatments in genitourinary tumors, including chemotherapies such as cisplatin and targeted therapies such as enzalutamide. Canonically, cicrRNAs participate in the competing endogenous RNA (ceRNA) network, or in some cases directly interact with proteins, regulate downstream pathways, and even some circRNAs have the potential to produce proteins or polypeptides. Several cellular mechanisms were involved in circRNA-dependent drug resistance, including autophagy, cancer stem cells, epithelial-mesenchymal transition, and exosomes. The potential clinical prospect of circRNAs in regulating tumor drug resistance was also discussed.

Hormone Refractory Prostate Cancer (Hrpc): Present and Future Approaches of Therapy

The mainstay of therapy for patients with advanced prostate cancer still remains androgen deprivation, although response to this is invariably temporary. Most of the patients develop hormone-refractory disease resulting in progressive clinical deterioration and, ultimately, death. Until recently there has been no standard chemotherapeutic approach for hormone refractory prostate cancer (HRPC), the major benefits of chemotherapy being only palliative. The studies combining mitoxantrone plus a corticosteroid demonstrated that chemotherapy could be given to men with symptomatic HRPC with minimal toxicity and a significant palliation could be provided. Recently, results from 2 phase III randomized clinical trials demonstrating that a combination of docetaxel plus prednisone can improve survival in men with HRPC have propelled docetaxel-based therapy into the forefront of treatment options for these patients as the new standard of care. There is a promising activity of new drug combinations such as taxanes plus vinca alkaloids; bisphosphonates are assuming a prominent role in prostate therapy through their ability to prevent skeletal morbidity. Combinations of classic chemotherapeutic agents and biological drugs began to be tested in phase II-III trials and the first results appear interesting. This article focuses on combinations recently evaluated or under clinical development for the treatment of HRPC.

Is There a Standard Chemotherapeutic Regimen for Hormone-Refractory Prostate Cancer? Present and Future Approaches in the Management of the Disease

Prostate cancer that no longer responds to hormonal manipulation can be defined as hormone-refractory prostate cancer. Until recently, there has been no standard chemotherapeutic approach for hormone-refractory prostate cancer. The major benefits of chemotherapy in the treatment of the disease are palliative in nature, in terms of reduction of pain and use of analgesics and improvement of performance status, as followed in the most recent trials. Phase III studies are necessary to better evaluate the efficacy of the different regimens, because several old studies suffer for methodological deficits. There is a promising activity of new drug combinations, such as vinca alkaloids and taxanes. Phase I and II trial are testing combinations of classic chemotherapeutic agents and biologic drugs, and the first results appear interesting. In this article, recent advances in the treatment of hormone-refractory prostate cancer using chemotherapeutic regimens are critically reviewed.

Effect of dutasteride on castration-resistant prostate cancer

It has previously been demonstrated that the intratumoral generation of the potent androgen dihydrotestosterone (DHT), contributes critically to the progression of prostate cancer and its castration-resistant form, castration-resistant prostate cancer (CRPC). Circulating testosterone is converted into DHT by 5α-reductase (SRD5A). Dutasteride is a dual inhibitor of type I and II SRD5A. The present study assessed the effectiveness of dutasteride in the treatment of CRPC. Between 2010 and 2013, CRPC was diagnosed in 41 patients at the Tokyo Metropolitan Tama Medical Center. Following diagnosis, the patients received 0.5 mg dutasteride daily. The patients' median age was 77.3 years (range, 63-90). Bone metastases were recognized in 12 patients. All the patients received dexamethasone. Twenty-four (59%) patients had previously undergone chemotherapy, while 11 (27%) received docetaxel, and 24 (59%) estramustine. The prostatic-specific antigen (PSA) level declined in 17 (41%) patients from the baseline value, following dutasteride treatment. The median value for the PSA decrease was 23% (range, 4.3-89.8%), and the median duration of the response was 4 months (range, 1-10). The PSA response rate (defined as >50% decline in PSA from the baseline value) was recognized in 7 (17%) patients. The median duration of the response was 3 months (range, 2-10). Dutasteride was efficacious against CRPC in certain patients and may be a promising option in CRPC treatment. A prospective randomized trial is necessary to verify the efficacy of dutasteride.

Management of Androgen-Independent Prostate Cancer

Background

Although androgen withdrawal can control prostate cancer for long periods in many patients, controversy exists regarding management when the tumor becomes androgen independent. Several options are now available.

Methods

A review of the pertinent literature of the last 20 years was conducted to provide guidance in defining and managing hormone-refractory prostate cancer.

Results

Stage D prostate cancer can be subclassified to correlate tumor biology with disease stage. Secondary hormone manipulations may induce responses in patients after failure of initial androgen suppression, and chemotherapy with docetaxel has prolonged survival in patients with androgen-independent prostate cancer (AIPC). The weight of evidence supports the maintenance of castrate levels of testosterone in metastatic AIPC. Bisphosphonates decrease skeletal complications.

Conclusions

Secondary hormone therapy, chemotherapy, and bisphosphonate therapy may provide benefits for selected patients. Correlation of disease stage with biologic characteristics of the tumor and host facilitates proper choices of interventions. Docetaxel-based chemotherapy regimens should be considered for first-line treatment of patients with progressive metastatic AIPC.

Magnetically-actuated drug delivery device (MADDD) for minimally invasive treatment of prostate cancer: An in vivo animal pilot study

BACKGROUND

The vast majority of prostate cancer presents clinically localized to the prostate without evidence of metastasis. Currently, there are several modalities available to treat this particular disease. Despite radical prostatectomy demonstrating a modest prostate cancer specific mortality benefit in the PIVOT trial, several novel modalities have emerged to treat localized prostate cancer in patients that are either not eligible for surgery or that prefer an alternative approach.

METHODS

Athymic nude mice were subcutaneously inoculated with prostate cancer cells. The mice were divided into four cohorts, one cohort untreated, two cohorts received docetaxel (10 mg/kg) either subcutaneously (SC) or intravenously (IV) and the fourth cohort was treated using the magnetically-actuated docetaxel delivery device (MADDD), dispensing 1.5 μg of docetaxel per 30 min treatment session. Treatment in all three therapeutic arms (SC, IV, and MADDD) was administered once weekly for 6 weeks. Treatment efficacy was measured once a week according to tumor volume using ultrasound. In addition, calipers were used to assess tumor volume.

RESULTS

Animals implanted with the device demonstrated no signs of distress or discomfort, neither local nor systemic symptoms of inflammation and infection. Using an independent sample t-test, the tumor growth rate of the treated tumors was significant when compared to the control. Post hoc Tukey HSD test results showed that the mean tumor growth rate of our device cohort was significantly lower than SC and control cohorts. Moreover, IV cohort showed slight reduction in mean tumor growth rates than the ones from the device cohort, however, there was no statistical significance in tumor growth rate between these two cohorts. Furthermore, immunohistochemistry demonstrated an increased cellular apoptosis in the MADDD treated tumors and a decreased proliferation when compared to the other cohorts. In addition, IV cohort showed increased treatment side effects (weight loss) when compared to the device cohort. Finally, MADDD showed minimal expression of CD45 comparable to the control cohort, suggesting no signs of chronic inflammation.

CONCLUSIONS

In conclusion, this study showed for the first time that MADDD, clearly suppressed tumor growth in local prostate cancer tumors. This could potentially be a novel clinical treatment approach for localized prostate cancer.

Early use of chemotherapy in metastatic prostate cancer

Since 2010, five new antineoplastic therapies have been FDA approved for the treatment of metastatic prostate cancer. With additional treatment options, questions arose about the optimal sequence of these agents. Until recently, chemotherapy has been deferred until later in the disease course in favor of next-generation androgen deprivation therapy. Prior to the development of abiraterone acetate and enzalutamide, clinical trials were opened investigating the combination of chemotherapy with androgen deprivation therapy in patients with metastatic hormone-sensitive disease. With the development of new oral therapies used to treat castration-resistant disease, these trials were largely forgotten or felt to be obsolete. Recently, two trials have been reported showing an overall survival benefit of the early use of chemotherapy in patients with hormone-naive prostate cancer, changing the treatment paradigm for metastatic disease. Here we review the history of chemotherapy in treating prostate cancer and the emerging evidence favoring its use as first-line therapy against metastatic hormone-sensitive disease.

Cardiovascular toxicities of systemic treatments of prostate cancer

Prostate cancer is the most common cancer in men, with an incidence that is expected to increase in the coming years. Prostate cancer is usually diagnosed in men >65 years of age, thus the concurrent presence of cardiovascular diseases might influence the treatment, owing to the increased risk of cardiovascular mortality. The introduction of new drugs, such as abiraterone and enzalutamide for the management of metastatic disease has created further interest in treatment-related cardiovascular toxicities, although limited data from trials specifically designed to identify cardiovascular toxicities of these agents are currently available. The only available data are derived from published phase II-III study reports, expanded access or compassionate use programmes and meta-analyses of the effects of systemic therapies that are already approved for use in clinical practice or are in the early phases of development. These data are conflicting, although they seem to suggest that certain drugs are associated with an increased risk of cardiovascular adverse events. Clinical trial methodology could be improved by the enrolment of greater numbers of patients >65 years of age, and the use of comprehensive cardiological evaluations. Moreover, closer collaboration between oncologists and cardiologists is essential for the identification and/or management of cardiovascular adverse events in patients with prostate cancer.

Inter-patient variability in docetaxel pharmacokinetics: A review

Docetaxel is a frequently used chemotherapeutic agent in the treatment of solid cancers. Because of the large inter-individual variability (IIV) in the pharmacokinetics (PK) of docetaxel, it is challenging to determine the optimal dose in individual patients in order to achieve optimal efficacy and acceptable toxicity. Despite the established correlation between systemic docetaxel exposure and efficacy, the precise factors influencing docetaxel PK are not yet completely understood. This review article highlights currently known factors that influence docetaxel PK, and focusses on those that are clinically relevant. For example, liver impairment should be taken into account when calculating docetaxel dosages as this may decrease docetaxel clearance. In addition, drug-drug interactions may be of distinct clinical importance when using docetaxel. Particularly, drugs strongly inhibiting CYP3A4 such as ketoconazole should not be concurrently administered without dose modification, as they may decrease the clearance of docetaxel. Gender, castration status, and menopausal status might be of importance as potential factors influencing docetaxel PK. The role of pharmacogenetics in predicting docetaxel PK is still limited, since no polymorphisms of clinical importance have yet been established.

Whole Tumor Antigen Vaccines: Where Are We?

With its vast amount of uncharacterized and characterized T cell epitopes available for activating CD4⁺ T helper and CD8⁺ cytotoxic lymphocytes simultaneously, whole tumor antigen represents an attractive alternative source of antigens as compared to tumor-derived peptides and full-length recombinant tumor proteins for dendritic cell (DC)-based immunotherapy. Unlike defined tumor-derived peptides and proteins, whole tumor lysate therapy is applicable to all patients regardless of their HLA type. DCs are essentially the master regulators of immune response, and are the most potent antigen-presenting cell population for priming and activating naïve T cells to target tumors. Because of these unique properties, numerous DC-based immunotherapies have been initiated in the clinics. In this review, we describe the different types of whole tumor antigens that we could use to pulse DCs ex vivo and in vivo. We also discuss the different routes of delivering whole tumor antigens to DCs in vivo and activating them with toll-like receptor agonists.

Progress in the treatment of advanced prostate cancer

The androgen receptor (AR) is the most significant target for patients with metastatic castration-resistant prostate cancer (mCRPC). There is now irrefutable evidence that the AR axis is functional in most patients throughout the history of prostate cancer, is crucial from diagnosis to death, even in patients who have received hormonal manipulation, and represents a relevant therapeutic target in all phases of the disease. The potential mechanisms of tumor escape after castration are multifold, with each mechanism today representing a therapeutic opportunity. Phase III trials have been able to demonstrate improved overall survival (OS), improved quality of life, decreased skeletal-related events, and other important clinical benefits in young and elderly patients. After the initial positive results with docetaxel chemotherapy in improving OS, further research has resulted in five new treatments in the past few years. Immunotherapy with sipuleucel-T, cabazitaxel chemotherapy, the androgen biosynthesis inhibitor abiraterone acetate, the antiandrogen enzalutamide, and the radioisotope radium-223 have all been shown to improve OS in large-scale, well-conducted clinical trials. Proper understanding of mechanisms of resistance and of cross-resistance among these agents, sequencing, and combinations is now a priority.

Tubulin-targeted agents including docetaxel and cabazitaxel

Microtubules are dynamic filamentous cytoskeletal proteins that are responsible for cellular integrity and architecture, mitosis, intracellular transport, cell signaling, and gene expression. Tubulin exists in the cell as dimers of α and β subunits, which complexes with a variety of regulatory proteins. There is a dynamic equilibrium between free and polymerized tubulin causing a state called "dynamic instability," which is a target of anticancer drugs, which inhibit tubulin through polymerization (taxanes, epothilones) or depolymerization (vinca alkaloids). Docetaxel-based therapy was the first such treatment to demonstrate a survival benefit in men with castration-resistant prostate cancer. Cabazitaxel, an antitubulin agent, which demonstrates activity in multidrug- and docetaxel-resistant cancer cell lines, demonstrates a survival benefit over mitoxantrone and prednisone in patients who have failed docetaxel-based chemotherapy. This article reviews the use of antitubulin agents in patients with castration-resistant prostate cancer.

2-Weekly versus 3-weekly docetaxel to treat castration-resistant advanced prostate cancer: a randomised, phase 3 trial

BACKGROUND

Docetaxel administered every 3 weeks is a standard treatment for castration-resistant advanced prostate cancer. We hypothesised that 2-weekly administration of docetaxel would be better tolerated than 3-weekly docetaxel in patients with castration-resistant advanced prostate cancer, and did a prospective, multicentre, randomised, phase 3 study to compare efficacy and safety.

METHODS

Eligible patients had advanced prostate cancer (metastasis, a prostate-specific-antigen test result of more than 10·0 ng/mL, and WHO performance status score of 0-2), had received no chemotherapy (except with estramustine), had undergone surgical or chemical castration, and had been referred to a treatment centre in Finland, Ireland, or Sweden. Enrolment and treatment were done between March 1, 2004, and May 31, 2009. Randomisation was done centrally and stratified by centre and WHO performance status score of 0-1 vs 2. Patients were assigned 75 mg/m(2) docetaxel intravenously on day 1 of a 3-week cycle, or 50 mg/m(2) docetaxel intravenously on days 1 and 15 of a 4-week cycle. 10 mg oral prednisolone was administered daily to all patients. The primary endpoint was time to treatment failure (TTTF). We assessed data in the per-protocol population. This study is registered with ClinicalTrials.gov, number NCT00255606.

FINDINGS

177 patients were randomly assigned to the 2-weekly docetaxel group and 184 to the 3-weekly group. 170 patients in the 2-weekly group and 176 in the 3-weekly group were included in the analysis. The 2-weekly administration was associated with significantly longer TTTF than was 3-weekly administration (5·6 months, 95% CI 5·0-6·2 vs 4·9 months, 4·5-5·4; hazard ratio 1·3, 95% CI 1·1-1·6, p=0·014). Grade 3-4 adverse events occurred more frequently in the 3-weekly than in the 2-weekly administration group, including neutropenia (93 [53%] vs 61 [36%]), leucopenia (51 [29%] vs 22 [13%]), and febrile neutropenia (25 [14%] vs six [4%]). Neutropenic infections were reported more frequently in patients who received docetaxel every 3 weeks (43 [24%] vs 11 [6%], p=0·002).

INTERPRETATION

Administration of docetaxel every 2 weeks seems to be well tolerated in patients with castration-resistant advanced prostate cancer and could be a useful option when 3-weekly single-dose administration is unlikely to be tolerated.

FUNDING

Sanofi.

PR-104 a bioreductive pre-prodrug combined with gemcitabine or docetaxel in a phase Ib study of patients with advanced solid tumours

Background

The purpose of this phase Ib clinical trial was to determine the maximum tolerated dose (MTD) of PR-104 a bioreductive pre-prodrug given in combination with gemcitabine or docetaxel in patients with advanced solid tumours.

Methods

PR-104 was administered as a one-hour intravenous infusion combined with docetaxel 60 to 75 mg/m² on day one given with or without granulocyte colony stimulating factor (G-CSF) on day two or administrated with gemcitabine 800 mg/m² on days one and eight, of a 21-day treatment cycle. Patients were assigned to one of ten PR-104 dose-levels ranging from 140 to 1100 mg/m² and to one of four combination groups. Pharmacokinetic studies were scheduled for cycle one day one and ¹⁸F fluoromisonidazole (FMISO) positron emission tomography hypoxia imaging at baseline and after two treatment cycles.

Results

Forty two patients (23 females and 19 males) were enrolled with ages ranging from 27 to 85 years and a wide range of advanced solid tumours. The MTD of PR-104 was 140 mg/m² when combined with gemcitabine, 200 mg/m² when combined with docetaxel 60 mg/m², 770 mg/m² when combined with docetaxel 60 mg/m² plus G-CSF and ≥770 mg/m² when combined with docetaxel 75 mg/m² plus G-CSF. Dose-limiting toxicity (DLT) across all four combination settings included thrombocytopenia, neutropenic fever and fatigue. Other common grade three or four toxicities included neutropenia, anaemia and leukopenia. Four patients had partial tumour response. Eleven of 17 patients undergoing FMISO scans showed tumour hypoxia at baseline. Plasma pharmacokinetics of PR-104, its metabolites (alcohol PR-104A, glucuronide PR-104G, hydroxylamine PR-104H, amine PR-104M and semi-mustard PR-104S1), docetaxel and gemcitabine were similar to that of their single agents.

Conclusions

Combination of PR-104 with docetaxel or gemcitabine caused dose-limiting and severe myelotoxicity, but prophylactic G-CSF allowed PR-104 dose escalation with docetaxel. Dose-limiting thrombocytopenia prohibited further evaluation of the PR104-gemcitabine combination. A recommended dose was identified for phase II trials of PR-104 of 770 mg/m² combined with docetaxel 60 to 75 mg/m² both given on day one of a 21-day treatment cycle supported by prophylactic G-CSF (NCT00459836).

The experience with cytotoxic chemotherapy in metastatic castration-resistant prostate cancer

This article reviews the initial experience with chemotherapy in metastatic castration-resistant prostate cancer (mCRPC) and outlines some of the ongoing clinical trials in this area. In addition, the authors outline current knowledge on outcomes of patients treated with taxane-based chemotherapy on retrospective analysis of randomized trials. These data are intended to provide physicians and patients with a general idea on the outcomes of men with mCRPC that may facilitate clinical decisions as well as the design and evaluation of clinical trials.

Cediranib inhibits both the intraosseous growth of PDGF D-positive prostate cancer cells and the associated bone reaction

BACKGROUND

The major cause of death in prostate cancer (PCa) cases is due to distant metastatic lesions, with the bone being the most prevalent site for secondary colonization. Utilization of small molecule inhibitors to treat bone metastatic PCa have had limited success either as monotherapies or in combination with other chemotherapeutics due to intolerable toxicities. In the current study, we developed a clinically relevant in vivo intraosseous tumor model overexpressing the platelet-derived growth factor D (PDGF D) to test the efficacy of a newly characterized vascular endothelial growth factor receptor (VEGFR)/PDGFR inhibitor, cediranib (also called AZD2171).

METHODS

An intratibial-injection model was established utilizing DU145 cells with or without increased PDGF D expression. Tumor-bearing mice were treated by daily gavage administration of cediranib and/or weekly i.p. injection of docetaxel for 7 weeks. Tibiae were monitored by in vivo/ex vivo X-rays and histomorphometry analysis was performed to estimate tumor volume and tumor-associated trabecular bone growth.

RESULTS

Cediranib reduced intraosseous growth of prostate tumors as well as tumor-associated bone responses. When compared to the standard chemotherapeutic agent docetaxel, cediranib exhibited a stronger inhibition of tumor-associated bone response. The efficacy of cediranib was further enhanced when the drug was co-administered with docetaxel. Importantly, the therapeutic benefits of cediranib and docetaxel are more prominent in intraosseous prostate tumors overexpressing PDGF D.

CONCLUSION

These novel findings support the utilization of cediranib, either alone or in combination with docetaxel, to treat bone metastatic PCa exhibiting PDGF D expression.

Reduced-dose docetaxel for castration-resistant prostate cancer has no inferior impact on overall survival in Japanese patients

BACKGROUND

In clinical practice, an adapted regimen with dose reduction is applied to castration-resistant prostate cancer (CRPC) treated with docetaxel because of its toxicity. However, there are few reports on the impact of dose reduction on survival.

METHODS

Fifty-seven patients with CRPC treated with first-line docetaxel in a single institution from 2005 to 2008 were evaluated retrospectively.

RESULTS

The median follow-up period was 20.5 months. Twenty-eight patients (49 %) received a standard 60 mg/m(2) regimen (SR), and 29 patients (51 %) received an adapted regimen (AR) with dose reduction. There was no difference in their baseline characteristics. The prostate-specific antigen response rates were not significantly different between the SR and AR groups (50 vs. 62 %, p = 0.36). Progression-free survival (PFS) and overall survival (OS) were also not significantly different between the groups (PFS 5.3 vs. 7.3 months, p = 0.39; OS 26.4 vs. 27.1 months, p = 0.53, respectively). No significant difference in the incidence of grade 3 or 4 adverse events was noted between the groups (89 vs. 83 %, p = 0.70). In multivariate analysis, hemoglobin and alkaline phosphatase were significant predictive factors for OS (hazard ratios 2.81 and 2.39, p = 0.012 and 0.024, respectively).

CONCLUSIONS

A reduced-dose regimen of docetaxel has no inferior impact on OS. Further studies on the optimal dose of docetaxel for Japanese patients are required.

Adjuvants for enhancing the immunogenicity of whole tumor cell vaccines

Whole tumor cell lysates can serve as excellent multivalent vaccines for priming tumor-specific CD8(+) and CD4(+) T cells. Whole cell vaccines can be prepared with hypochlorous acid oxidation, UVB-irradiation and repeat cycles of freeze and thaw. One major obstacle to successful immunotherapy is breaking self-tolerance to tumor antigens. Clinically approved adjuvants, including Montanide™ ISA-51 and 720, and keyhole-limpet proteins can be used to enhance tumor cell immunogenicity by stimulating both humoral and cellular anti-tumor responses. Other potential adjuvants, such as Toll-like receptor agonists (e.g., CpG, MPLA and PolyI:C), and cytokines (e.g., granulocyte-macrophage colony stimulating factor), have also been investigated.

Concurrent and adjuvant docetaxel with three-dimensional conformal radiation therapy plus androgen deprivation for high-risk prostate cancer: preliminary results of a multicentre phase II trial

BACKGROUND AND PURPOSE

We evaluate the feasibility of concomitant and adjuvant docetaxel combined with three-dimensional conformal radiotherapy (3D-CRT) and androgen deprivation in high-risk prostate carcinomas.

METHODS

Fifty men with high-risk localized prostate cancer (16), locally advanced (28) or very high-risk prostate cancer (6) were included. Seventy Gy were delivered on prostate and seminal vesicles in 35 fractions, concurrently with weekly docetaxel (20mg/m(2)). Three weeks after the completion of 3D-CRT, docetaxel was given for 3 cycles (60mg/m(2)), every 3 weeks. Patients had to receive LHRH agonist during 3 years.

RESULTS

The intent to treat analysis shows that four patients out of 15 stopped prematurely the chemotherapy due to grade 3-4 acute toxicity. In the per protocol analysis, 46 patients completed a full-dose chemoradiation regimen representing 413 cycles: five patients experienced a grade 3 toxicity, and 15 patients experienced a grade 2 toxicity. With a median follow-up of 54 months, the 5-year clinical disease-free survival was 66.72% and the 5-year survival was 92.15%.

CONCLUSIONS

3D-CRT with androgen deprivation and concurrent weekly docetaxel, followed by three cycles of adjuvant docetaxel may be considered as feasible in high-risk prostate cancer and deserved to be evaluated in a phase III randomized trial.

Safety and efficacy of docetaxel, estramustine phosphate and hydrocortisone in hormone-refractory prostate cancer patients

OBJECTIVE

To assess the combination of docetaxel (DTX), estramustine phosphate (EMP) and hydrocortisone for patients with hormone-refractory prostate cancer (HRPC).

METHODS

A total of 63 patients with HRPC were treated with a chemotherapeutic regimen including DTX, EMP, and hydrocortisone. Clinical and pathological features were correlated to serum prostate-specific antigen (PSA) recurrence and survival rates. Incidence and degree of toxicities were also retrospectively reviewed.

RESULTS

A median of 11 courses of chemotherapy was administered per patient. PSA levels decreased by >50% in 32 (51%) patients and >90% in 18 (29%) patients. Median time to PSA progression was 6 months (range from 1 to 41 months) and median time of overall survival was 14 months (range from 1 to 56 months). In a univariate analysis to predict overall survival, PSA, hemoglobin, alkaliphosphatase, and performance status prior to the chemotherapy were significant factors. Despite grade 3-4 neutropenia in 87% of patients, grade 5 interstitial pneumonia in one patient and grade 4-5 myocardial infarction in two patients were recognized, the regimen seemed to be relatively safe.

CONCLUSIONS

Combination chemotherapy with DTX, EMP and hydrocortisone provides survival benefits for patients with HRPC with an acceptable toxicity profile. We need to further evaluate who might benefit most from this regimen.

Whole tumor antigen vaccines

Although cancer vaccines with defined antigens are commonly used, the use of whole tumor cell preparations in tumor immunotherapy is a very promising approach and can obviate some important limitations in vaccine development. Whole tumor cells are a good source of TAAs and can induce simultaneous CTLs and CD4(+) T helper cell activation. We review current approaches to prepare whole tumor cell vaccines, including traditional methods of freeze-thaw lysates, tumor cells treated with ultraviolet irradiation, and RNA electroporation, along with more recent methods to increase tumor cell immunogenicity with HOCl oxidation or infection with replication-incompetent herpes simplex virus.

Evaluation of docetaxel plus estramustine in the treatment of patients with hormone-refractory prostate cancer

OBJECTIVES

To investigate the feasibility and efficacy of docetaxel-based chemotherapy in patients with hormone-refractory prostate cancer (HRPC).

METHODS

Forty-six consecutive HRPC patients treated between January 2003 and March 2008 were included in this analysis. Docetaxel was given at a dose of 35 mg/m(2) twice every 3 weeks and oral estramustine concurrently for three consecutive days during weeks 1 and 2 of each cycle. During each treatment week, the dose of estramustine was 1260 mg on the first day, 980 mg on the second day and 840 mg on the third day. Patients were premedicated with 4 mg twice a day of oral dexamethasone for three consecutive days. Treatment was continued until evidence of disease progression or unacceptable toxicity. Prostate-specific antigen (PSA) levels were evaluated at least once every 4 weeks.

RESULTS

Patients received a median of three cycles of chemotherapy. Of the evaluable 46 patients, 25 (54%) had a >or=50% PSA decline and 12 (26%) had a >or=75% PSA decline. Median time to PSA progression and overall survival time were 10.1 and 27.0 months, respectively. Median follow-up was 15.0 months. Major severe toxicities were grade 3 or 4 leukopenia in five (11%) patients. Mild toxicities included grade 1 or 2 nausea in eight (17%) patients. Two patients could not continue the treatment because of interstitial pneumonitis and a gastric hemorrhage, respectively.

CONCLUSIONS

Docetaxel plus estramustine chemotherapy represents an active and well tolerated treatment for Japanese HRPC patients.

Docetaxel and Estramustine for Prostate Cancer

The complexity of cancer chemotherapy requires that pharmacists be familiar with the complicated regimens and highly toxic agents used. This column reviews various issues related to preparing, dispensing, and administering antineoplastic therapy and to the agents, commercially available and investigational, used to treat malignant diseases.

Docetaxel in the management of prostate cancer: current standard of care and future directions

BACKGROUND

Advanced and metastatic prostate cancer continues to represent a significant healthcare burden. Since the publication of two randomized trials that showed significant survival and palliative benefits for men treated with docetaxel, this drug has become the treatment of choice for patients with metastatic castration resistant prostate cancer (CRPC).

OBJECTIVE

This review discusses the development and current use of docetaxel in metastatic CRPC, as well as future clinical applications.

METHODS

The current literature, meeting abstracts and ClinicalTrials.gov have been reviewed. The most relevant studies involving patients with prostate cancer receiving therapy with docetaxel, alone or in combination with other agents, have been summarised.

CONCLUSION

Docetaxel monotherapy is the approved treatment for patients with metastatic CRPC, and its association with other agents, such as targeted therapies, is currently under study. Several trials are currently ongoing to investigate the use of docetaxel in the early stages of disease, particularly in the neoadjuvant and adjuvant settings for patients with high-risk disease.

Docetaxel-based chemotherapy in elderly patients (age 75 and older) with castration-resistant prostate cancer

BACKGROUND

There are no data on the patterns of care and outcome of very elderly patients with castration-resistant prostate cancer (CRPC) treated with docetaxel.

OBJECTIVE

To assess the routine use of first-line docetaxel-based chemotherapy in CRPC patients aged >75 yr.

DESIGN, SETTING, AND PARTICIPANTS

We reviewed the clinical files of 175 patients aged > or =75 yr with CRPC treated with first-line docetaxel in nine French tertiary care cancer centres from 2000 to 2007.

MEASUREMENTS

Response rate, survival, and adverse events (AE).

RESULTS AND LIMITATIONS

Median age was 78 yr. Ninety-five patients (54%) received a standard 3-wk regimen (SR), and 80 patients (46%) received an adapted regimen (AR) delivered on a weekly schedule with various times for rest periods. Patients treated with an AR were older (>80 yr) and had poorer performance status (PS; > or =2) than patients treated with the SR. The prostate-specific antigen (PSA) response rates were not significantly different between the standard and adapted treatment groups (71% vs 68%, p=0.79). The median progression-free survival (PFS) was 7.4 mo. The median overall survival (OS) was 15 mo. The incidence of grade 3 or 4 AEs was 46% and was correlated with poor PS and the presence of visceral disease but not with the regimen. Early discontinuation of treatment because of toxicity occurred more frequently in the AR group than in the SR group (30% vs 8.4%, p=0.0005). In multivariate analysis, only PS and the presence of visceral disease were predictors of OS.

CONCLUSIONS

Docetaxel is active and feasible in elderly patients with good PS. The optimal treatment of frail patients with CRPC remains to be established. Geriatric tools should be used to more accurately detect elderly CRPC patients who are unfit for chemotherapy. Age by itself should not be used as a criterion to deny patients with CRPC a potentially effective chemotherapy.

Combination chemotherapy with weekly docetaxel and estramustine for hormone refractory prostate cancer in Japanese patients

The aim is to evaluate the efficacy and toxicity of weekly docetaxel and estramustine for Japanese men with hormone refractory prostate cancer who were treated at a single institution. Twenty eligible patients had histologically proven adenocarcinoma of the prostate with metastases that were progressing despite complete androgen blockade and antiandrogen withdrawal. All of the patients received docetaxel 30 mg/m(2) weekly (days 1, 8, 15, 22, 29, and 36). After a two week break, the treatment schedule was repeated. Patients were scheduled to receive daily oral estramustine 560 mg/day throughout the protocol. In the serum prostate specific antigen (PSA) response, three (15%) patients achieved a complete response, and 8 (40%) acheived a partial response. Overall survival and time to progression were 13.4 months and 6.4 months, respectively, however sixty-seven percent of the patients had to discontinue treatment because of toxicity. The high toxicity of this protocol suggests that the regimen and/or the timing should be altered for Japanese patients.

Whole-cell cancer vaccination: from autologous to allogeneic tumor- and dendritic cell-based vaccines

The field of tumor vaccination is currently undergoing a shift in focus, from individualized tailor-made vaccines to more generally applicable vaccine formulations. Although primarily predicated by financial and logistic considerations, stemming from a growing awareness that clinical development for wide-scale application can only be achieved through backing from major pharmaceutical companies, these new approaches are also supported by a growing knowledge of the intricacies and minutiae of antigen presentation and effector T-cell activation. Here, the development of whole-cell tumor and dendritic cell (DC)-based vaccines from an individualized autologous set-up to a more widely applicable allogeneic approach will be discussed as reflected by translational studies carried out over the past two decades at our laboratories and clinics in the vrije universiteit medical center (VUmc) in Amsterdam, The Netherlands.

The Canadian Uro-Oncology Group multicentre phase II study of docetaxel administered every 3 weeks with prednisone in men with metastatic hormone-refractory prostate cancer progressing after mitoxantrone/prednisone

OBJECTIVE

To investigate the use of docetaxel 75 mg/m(2) intravenously every 3 weeks plus prednisone 5 mg orally twice daily in men with metastatic hormone-refractory prostate cancer (HRPC) progressing after first-line mitoxantrone/prednisone (MP), the primary outcome being progression-free survival with prostatic-specific antigen (PSA) and pain response, toxicity and quality of life (QoL) also assessed.

PATIENTS AND METHODS

Thirty patients from four centres were enrolled in the study; all had had previous MP for symptomatic, metastatic HRPC and all had castrate levels of testosterone maintained during therapy.

RESULTS

At enrolment, the median age was 69 years, the mean PSA level was 324 ng/dL, and 86% of patients reported pain. There was a PSA response in 57% of the men and a reduction in pain in >60%; the overall QoL was maintained. There were four cases of febrile neutropenia and two treatment-related deaths. The median progression-free and overall survival were 5 and 15 months, respectively.

CONCLUSION

Docetaxel was associated with high rates of PSA and pain response in this study. Non-haematological toxicity was similar to that during first-line treatment, but rates of febrile neutropenia and toxic death appeared to be slightly higher. In selected patients with progressive metastatic HRPC previously treated with mitoxantrone, docetaxel appears to be a beneficial therapeutic option.

Chemotherapy in hormone-refractory prostate cancer

The results of the TAX 327 and SWOG 99-16 trials for the first time showed an improvement in overall survival (OS) with docetaxel-based chemotherapy in patients with metastatic hormone-refractory prostate cancer. As such, 3-weekly (q3w) docetaxel plus low-dose prednisone is widely considered to be the treatment of choice for these patients. An updated survival analysis from TAX 327 confirms that benefits observed with docetaxel are sustained at 3 years. Furthermore, q3w docetaxel plus prednisone was effective in all patient subgroups investigated, regardless of age, presence or absence of pain, and performance status. Multivariate analysis has shown that prostate-specific antigen (PSA) concentrations and kinetics (pre-treatment PSA doubling time; PSADT) are independent prognostic factors for survival in the TAX 327 cohort, along with pain, number of metastatic sites and measurable disease. Patients with baseline PSA concentrations of <114 ng/mL and PSADT > or =55 days have a median overall survival of 25 months while those with PSA concentrations of > or =114 ng/mL and a PSADT of <55 days have a median overall survival of only 14 months. A PSA decline of > or 1=30% within 3 months' therapy with docetaxel is also a surrogate of OS. Measurements such as these, and the use of predictive nomograms, can assist the physician in identifying patients at high risk of disease progression who may benefit from earlier treatment with chemotherapy.

Long-term outcome of a phase II study of weekly docetaxel with a short course of estramustine and enoxaparine in hormone-resistant prostate cancer patients

OBJECTIVE

The objective was to define the toxicity and activity of weekly docetaxel administered with a short course of estramustine and enoxaparine in patients with hormone-resistant prostate cancer (HRPC).

PATIENTS AND METHODS

Twenty-four patients were treated with the next regimen: weekly docetaxel 36 mg/m(2) iv for three consecutive weeks every 28 days, and estramustine 280 mg three times a day for three consecutive days beginning the day before docetaxel (days 1-3, 8-10 and 15-17). In order to prevent thromboembolic events, 40 mg of subcutaneous enoxaparine was administered daily sc on the same days as estramustine. Primary endpoints were: toxicity, especially the presence of thromboembolic events, PSA response rate and response in measurable disease. Secondary endpoints were: time to PSA progression and overall survival.

RESULTS

Nineteen of 24 patients (79.1%, 95% CI 71-87%) had a PSA response = or >50%. Four of the eleven patients with measurable disease had a partial response. The median time to PSA progression was 7 months (CI 95%: 6.5-9) and the median survival was 19 months (IC 95%: 11-24). Toxicity was manageable with no treatment- related mortality. Only two patients had grade 4 neutropenia. Two patients had thrombotic events, one deep venous thrombosis and one stroke. The main grade 3 non-haematologic toxicity was diarrhoea and asthenia, both in 25% of patients.

CONCLUSIONS

Weekly docetaxel with a short course of estramustine and enoxaparine is active and tolerable in HRPC patients. The observed incidence of thrombosis was lower than previously reported but the association of enoxaparine was not enough to completely prevent the thromboembolic events.

Randomized phase II study of docetaxel plus estramustine and single-agent docetaxel in patients with metastatic hormone-refractory prostate cancer

BACKGROUND

Docetaxel (Taxotere)-based regimens are the new standard therapy in advanced hormone-refractory prostate cancer (HRPC). A synergistic activity has been shown with docetaxel in combination with estramustine in vitro; however, the benefit of this combination remains controversial in clinical practice. We assessed the activity and safety of docetaxel alone and docetaxel-estramustine in HRPC.

PATIENTS AND METHODS

Patients (n = 92) with metastatic HRPC and rising prostate-specific antigen (PSA) while receiving androgen suppression were randomized to 3-weekly treatment with either docetaxel 75 mg/m(2), day 1 (D), or docetaxel 70 mg/m(2), day 2, plus oral estramustine 280 mg twice daily, days 1-5 (DE).

RESULTS

Ninety-one patients were treated (DE 47, D 44). A PSA response occurred in 68% (primary endpoint met) and 30% of patients, respectively. Median PSA response duration was 6.0 months in both groups. Median time to progression was 5.7 and 2.9 months, and median survival was 19.3 and 17.8 months in the DE and D arms, respectively. Hematologic and non-hematologic toxic effects were mild and similar in both arms. One patient in each group withdrew due to toxicity. Quality of life was similar in both groups.

CONCLUSION

Combining estramustine with docetaxel in this schedule is an active and well-tolerated treatment option in HRPC.

Phase II study of low-dose docetaxel/estramustine in elderly patients or patients aged 18-74 years with hormone-refractory prostate cancer

PURPOSE

Chemotherapy is often poorly tolerated in elderly patients or patients with poor performance status. This trial was designed to determine whether low-dose weekly docetaxel/estramustine was efficacious with acceptable toxicity.

PATIENTS AND METHODS

Dexamethasone was administered as premedication. Subjects received docetaxel 25 mg/m2 intravenously on days 2, 9, and 16 and estramustine 140 mg orally twice daily on days 1-3, 8-10, and 15-17. Cycles were 28 days. Participants received < or = 6 cycles unless progression or intolerable toxicity occurred.

RESULTS

Fifty-eight subjects were enrolled at 31 sites in the US Oncology Network. Median age was 78 years (range, 64-92 years); performance status scores (0, 1, 2, and 3) were 36%, 38%, 24%, and 2%, respectively; 55 subjects received > or = 1 cycle of treatment; and 4 participants were nonevaluable because they completed < 2 cycles. Among the 56 treated subjects, 38 (68%) had a decreased prostate-specific antigen level (> or = 50% compared with baseline level and maintained for 4 weeks). There were 40 subjects with measurable tumor(s). Responses, assessed using Response Evaluation Criteria in Solid Tumors, were 1 complete response (2.5%), 7 partial responses (17.5%), 26 stable diseases (65%), and 6 progressive diseases (15%). At 1 year, 17% of participants were progression free; median progression-free survival was 5.3 months (range, 1-14.5 months); estimated 1-year survival was 65%. There were no grade 4 treatment-related events. Grade 3 treatment-related events included fatigue/asthenia (11%) and arrhythmia, dehydration, cerebral ischemia, thrombocytopenia, and dyspnea (4% each). There was 1 treatment-related death (acute respiratory distress syndrome).

CONCLUSION

These findings suggest that elderly men with advanced-stage prostate cancer tolerate this regimen, with significant responses and prolonged progression-free survival. These patients should not be excluded from chemotherapeutic interventions based on age alone.

Effect of diabetes mellitus on the epidemiology and outcomes of colon cancer

OBJECTIVES

To assess the effect of diabetes mellitus (DM) on the pathogenesis and outcomes from colon cancer.

METHODS

A retrospective chart review was conducted on 1853 patients with colon cancer.

RESULTS

A higher percentage of males than females with colon cancer had DM (16.2% vs 11.3%; p < 0.01). Males had a slightly lower risk of dying from colon cancer (RR - 0.88; p=0.08). There was no difference in the median age of diagnosis of colon cancer in patients with and without DM, but a larger proportion of patients with diabetes mellitus were >or=70 yr at diagnosis (50% vs 43%) (p=0.0004). No significant relationship was noted between stage of colon cancer or survival and presence of DM.

CONCLUSIONS

DM did not affect either the stage at diagnosis, or outcomes from colon cancer. More males with colon cancer tended to have DM and a larger proportion of patients with DM were >or=70 yr at the time of diagnosis.

Effective chemotherapy for hormone-refractory prostate cancer (HRPC): Present status and perspectives with taxane-based treatments

Prostate cancer is a significant health concern for men worldwide. It continues to be the most common lethal malignancy diagnosed in American men and the second leading cause of male cancer mortality. Hormone-refractory prostate cancer (HRPC) remains clinically challenging. Two large phase III studies have demonstrated a survival advantage in HRPC patients utilizing docetaxel chemotherapy, setting a new standard of care for this disease. This paper examines the progress that has been made in HRPC with the Taxanes (Docetaxel, Paclitaxel, and Epothilones) with a glimpse on mechanisms of resistance and on combinations able to overcome it. In addition, new targeted therapies under development in combination with taxanes are reviewed with an explanation of their molecular mechanisms of action.

Potentiation of antitumour activity of docetaxel by combination with trastuzumab in a human prostate cancer xenograft model and underlying mechanisms

Antitumour activity of docetaxel (Taxotere) in hormone-dependent (HD) and hormone-independent (HID) prostate cancer PAC120 xenograft model was previously reported, and its level was associated with HER2 protein expression. In the present study, we evaluate the antitumour effects of docetaxel combined with trastuzumab (Herceptin), an anti-HER2 antibody. Although trastuzumab alone had no effect on tumour growth, it potentiated the antitumour activity of docetaxel in HD tumours and more strongly in HID variants. Using the HID28 variant, we show that docetaxel treatment of tumour-bearing mice induces an increased HER2 mRNA expression of the tyrosine kinase receptor of 25-fold 24 h after docetaxel treatment, while HER2 protein and p-AKT decreased. This was followed by an increase of HER2 protein 3 days (two-fold) after docetaxel treatment and by a strong HER2 release in the serum of treated mice; expression of phospho-ERK, p27, BCL2 and HSP70 concomitantly increased. Similar molecular alterations were induced by docetaxel plus trastuzumab combination, except for that there was a transient and complete disappearance of AR and HSP90 proteins 24 h after treatment. We show that in addition to its known effects on tubulin and mitotic spindles, docetaxel induces complex signalisation pathway mechanisms in surviving cells, including HER2, which can be pharmacologically targeted. This study suggests that the docetaxel/trastuzumab combination may prove an effective therapeutic approach for HER2-expressing hormone-refractory prostate cancer.

Docetaxel treatment in the elderly patient with hormone refractory prostate cancer

Docetaxel is an anti-microtubular agent in the family of the taxanes, now FDA approved as first line chemotherapy for the treatment of hormone refractory metastatic prostate cancer. Recent data from two large randomized Phase III trials showed a survival advantage in hormone refractory prostate cancer patients treated with docetaxel. This discovery changed the perceptions about utilization of chemotherapy for this devastating disease and introduced a new paradigm/standard of care treatment for this patient population. The management of elderly patients with metastatic prostate cancer is an important issue because according to data from the Surveillance, Epidemiology, and End Results (SEER) program, the American Cancer Society, and the United Nations, the incidence of prostate cancer in elderly men is expected to increase since people are living longer. In this paper we will review the results of trials evaluating docetaxel in hormone refractory prostate cancer and the implications of these trials as they relate to diagnosis and management of this disease in the elderly man.

Phase I/II study of weekly docetaxel and vinblastine in the treatment of metastatic hormone-refractory prostate carcinoma

BACKGROUND

Phase II trials have shown that taxanes have clinical activity as single agents as well as in combination with microtubule inhibitors in the treatment of hormone-refractory prostate cancer. Recent phase III trials with docetaxel have reported a survival benefit. Most trials also report significant toxicity, including thromboembolic disease. We conducted a phase I/II study to evaluate the maximum-tolerated dose, response rate, and effects on quality of life of the combination of docetaxel and vinblastine.

METHODS

Twenty men with hormone-refractory prostate cancer were treated after experiencing hormonal failure. Patients were enrolled in cohorts of three and treated with three weekly doses of docetaxel (20, 25, 30, 35, or 40 mg/m2) administered as 30-minute infusion and vinblastine (3 mg/m2) bolus. Treatment cycles were repeated every 28 days. Follow-up assessments included prostate-specific antigen level determinations, computed tomographic scans, bone scans, Brief Pain Inventory, and Functional Assessment of Cancer Therapy-Prostate Instrument (FACT-P). Toxicity was graded by National Cancer Institute common toxicity criteria.

RESULTS

The maximum tolerated dose of docetaxel was 35 mg/m2. Twelve of the 19 patients (63%; 95% CI 38%-84%) evaluable patients achieved a 50% reduction in prostate-specific antigen level that persisted for 24-80 weeks. Four of eight patients with measurable soft tissue disease had a partial response. Median time to disease progression was 50 weeks. Sixteen patients completed the Brief Pain Inventory at least three times. Twelve patients reported moderate-to-severe pain scores (>or=4) at baseline. Of these 12 patients, 11 reported that their worst pain score improved by at least two levels, and five of the 12 reported decreased opioid requirements. Seventeen patients completed the FACT-P at baseline and on at least two additional visits. Nine of these 17 (53%) reported improvement in Trial Outcome Index (sum of physical, functional, prostate subscales) by >or=6 points. Anemia was common; 12/20 patients required epoetin, and two required transfusions. Venous thrombosis developed in four patients during treatment. Only two patients discontinued treatment because of toxicity.

CONCLUSIONS

This combination of weekly docetaxel and vinblastine is effective, well tolerated, and associated with improved quality of life in most of the patients treated. Although estramustine was not given, the risk of thromboembolic disease remains significant.

Hoosier Oncology Group randomized phase II study of docetaxel, vinorelbine, and estramustine in combination in hormone-refractory prostate cancer with pharmacogenetic survival analysis

PURPOSE

To determine the safety and efficacy of two docetaxel doublets in hormone-refractory prostate cancer (HRPC) patients and to examine the prognostic role of polymorphisms in host genes important to docetaxel metabolism and transport.

EXPERIMENTAL DESIGN

Sixty-four chemotherapy-naive patients with HRPC were randomized to docetaxel and vinorelbine (D, 20 mg/m2 i.v. days 1 and 8; V, 25 mg/m2 i.v. days 1 and 8) or docetaxel and estramustine phosphate (D, 60-70 mg/m2 i.v. day 1; E, 280 mg oral thrice daily days 1-5) administered q21d. Primary end point was clinically significant toxicity. A pharmacogenetic analysis of host genes was done in patients who received at least one cycle of docetaxel therapy.

RESULTS

Grade 3/4 toxicity occurred in 15.6% of DV patients and in 28.6% DE patients. Neither arm exceeded the threshold of clinically significant toxicity. In the DV arm, objective response rate was 33%, prostate-specific antigen response rate was 20%, and median survival was 16.2 months. In the DE arm, objective response rate was 67%, prostate-specific antigen response rate was 43%, and median survival was 19.7 months. Pharmacogenetic analyses showed a significant association between survival beyond 15 months and the ABCG2 421 C > A (Q141K) polymorphism compared with the wild-type (C/C) genotype (66% versus 27%; P = 0.05).

CONCLUSIONS

DV and DE doublets are active with a tolerable toxicity profile in patients with HRPC; however, efficacy does not seem superior to standard single-agent docetaxel. The ABCG2 421 C > A (Q141K) polymorphism may be an important predictor of response and survival in HRPC patients treated with docetaxel-based chemotherapy.

Chemotherapy for advanced prostate cancer: docetaxel and beyond

To place appropriately into context the current status of chemotherapy as a management option for patients with hormone-refractory metastatic prostate cancer, it is important to reflect on the widely held historical belief that advanced prostate cancer is a chemotherapeutic-insensitive neoplasm. This article focuses on three disease subsets: (1)metastatic, hormone-refractory, chemotherapy-naive prostate cancer;(2) metastatic, hormone-refractory, progressive prostate cancer after frontline chemotherapy; and (3) locally advanced prostate cancer. Yagoda and Petrylak evaluated the results of 26 phase II trials of antineoplastics in advanced prostate cancer published between 1987 and 1991 and found the average objective response rate was less than 10% with only a few studies having response rates in the 10% to 20%range.

Cytotoxic chemotherapy for prostate cancer: Who and when?

The survival benefit demonstrated by docetaxel-based therapy in two randomized trials, Southwest Oncology Group (SWOG) 99-16 and TAX 327, has changed the perception of chemotherapy in men with hormone-refractory prostate cancer from nihilism to optimism. These survival improvements are of similar magnitude to those found in trials that established chemotherapeutic regimens for metastatic breast, lung, or colorectal cancer. The timing of chemotherapy in the aforementioned solid tumors is much more clearly defined than in men with metastatic prostate cancer. Traditionally, chemotherapy in men with hormone-resistant prostate cancer was reserved for symptomatic patients only; the inclusion of symptomatic and asymptomatic patients in SWOG 99-16 and TAX 327 has raised several questions regarding the optimal use of chemotherapy in these patients. When is the best time to initiate docetaxel-based chemotherapy? Is it appropriate to use chemotherapy in high-risk patients as adjuvant therapy? Although retrospective analysis of current trials may provide hypothesis, only properly designed randomized clinical trials will answer these questions.

A phase I study of paclitaxel/doxorubicin/ thalidomide in patients with androgen- independent prostate cancer

PURPOSE

The antiangiogenic and immunomodulatory effects of thalidomide induce responses in patients with androgen-independent prostate cancer (AIPC). Paclitaxel and doxorubicin also have significant antitumor activity. A phase I dose-escalation study was conducted to evaluate the use of these agents in combination to enhance the chemotherapeutic effects of treatment for refractory cancer.

PATIENTS AND METHODS

Twelve men with AIPC (mean age, 64.5 years) and a median prostate-specific antigen (PSA) level of 30 ng/mL were enrolled. Patients received starting doses of weekly paclitaxel (100 mg/m(2)) as a 1-hour intravenous infusion, weekly doxorubicin (20 mg/m(2)) as a 24-hour intravenous infusion, and daily oral thalidomide at escalating dose levels of 200 mg (dose level 0), 300 mg (dose level +1), and 400 mg (dose level +2). Paclitaxel and doxorubicin were administered for 3 consecutive weeks of a 5-week cycle. Exposure to thalidomide was daily. Patients were evaluated weekly for dose-limiting toxicities to determine the maximum tolerated dose. In addition, PSA levels were measured before each cycle of treatment. Response to treatment was defined as a > or =50% decrease in baseline PSA levels associated with stable radiographic disease, improvement of bone scan results with plain radiograph correlation, or improvement in soft tissue disease.

RESULTS

Four patients were treated on dose level 0, 5 were treated on dose level +1, and 3 were treated on dose level +2. The thalidomide 400-mg dose level resulted in 3 of 3 patients experiencing grade 3 leukopenia. The maximum tolerated dose was 300 mg of thalidomide in combination with paclitaxel/doxorubicin. Nine of the 12 patients were evaluable for PSA response, with 88% exhibiting partial responses or stable disease. One patient (11%) had a significant response, with PSA levels decreasing > 90% from baseline values. Overall, PSA-level decreases ranged from 0.5 ng/mL to 39.5 ng/mL among the 9 evaluable patients. A maximum of 7 cycles of therapy were administered. Twelve patients were evaluable for toxicity: neutropenia (grade 3, 27%; grade 4, 54%), leukopenia (grade 3, 63%), constipation (grade 3, 27%), fatigue (grade 3, 27%), nausea (grade 3, 9%), and deep vein thrombosis (grade 3, 9%) were reported.

CONCLUSION

The combined dosing of paclitaxel (100 mg/m(2) weekly), doxorubicin (20 mg/m(2) weekly), and thalidomide (300 mg daily) is tolerated by men with AIPC and merits continued phase II study.

A randomized study of docetaxel and dexamethasone with low- or high-dose estramustine for patients with advanced hormone-refractory prostate cancer

OBJECTIVE

To test the combination of docetaxel with two different doses of estramustine in patients with hormone-refractory prostate cancer (HRPC), to improve response rates and to lower side-effects, as docetaxel-based chemotherapy is an increasing option for men with advanced HRPC, and alone or combined with estramustine, docetaxel improves median survival.

PATIENTS AND METHODS

In all, 72 patients with metastatic HRPC were randomly assigned to receive docetaxel (70 mg/m(2) intravenously, on day 2 every 21 days) and estramustine (3 x 280 mg/day oral starting 1 day before docetaxel, for 5 consecutive days) for arm A, or estramustine (3 x 140 mg/day oral starting 1 day before docetaxel, for 3 consecutive days) for arm B. Premedication with oral dexamethasone at a total daily dose of 16 mg, in divided doses twice a day was administered in arm A on day 1-5 and in arm B on day 1-3. Initially, six cycles were administered. Chemotherapy was restarted after a significant increase in prostate-specific antigen (PSA) level. Patients were monitored for any measurable PSA response and toxicity.

RESULTS

Between the arms there was no statistically significant difference in time to progression and overall survival. However, treatment B had less treatment-related toxicity than A. Independent prognostic variables were baseline factors like PSA level, haemoglobin level, Eastern Cooperative Oncology Group performance status, and bone pain at presentation.

CONCLUSIONS

In this randomized phase II study the combination of docetaxel and estramustine had substantial activity in HRPC, with a significant incidence of severe toxicity, both haematological and not. Nevertheless, treatment-related toxicity was predictable and manageable. There was no better effect with a higher dose of estramustine with docetaxel than for a lower dose. There was a slight tendency to higher toxicity for high-dose estramustine but this was not statistically significant. The present results support the assertion that estramustine is not necessary in docetaxel-based treatment regimens.

Docetaxel induces apoptosis in hormone refractory prostate carcinomas during multiple treatment cycles

Caspase-cleaved proteins are released from disintegrated apoptotic cells and can be detected in the circulation. We here addressed whether caspase-cleaved cytokeratin 18 (CK18-Asp396) can be used as a serum biomarker for assessment of the clinical efficiency of chemotherapy in hormone-refractory prostate cancer (HRPC). A total of 82 patients with HRPC were evaluated during 751 treatment cycles, either with estramustine (EMP)/vinorelbine or with EMP/docetaxel. The levels of CK18-Asp396 and of total CK18 were measured in patient serum before and during therapy by ELISA. Docetaxel induced significant increases in serum CK18-Asp396 (P<0.0001) and total CK18 (P<0.0002), suggesting induction of apoptosis. Similarly, vinorelbine induced increases in both CK18-Asp396 and CK18 (P<0.001 and 0.011). In contrast, EMP induced increases in total serum CK18 (P<0.0001), but not in CK18-Asp396 (P=0.13). The amplitudes of docetaxel-induced increases were associated with baseline prostate-specific antigen (PSA) and CK18 serum levels in these patients, consistent with tumoral origin of caspase-cleaved fragments. Docetaxel induced significant increases in CK18-Asp396 during second-, third- and fourth-line therapy and induced increased levels of CK18-Asp396 during treatment cycles 1–8. In contrast, vinorelbine induced significant increases only during cycles 1–3. In a subgroup of 32 patients that received EMP/vinorelbine in second line followed by EMP/docetaxel in third line, docetaxel induced stronger increases than vinorelbine (P=0.008). These results show that the CK18-Asp396 serum marker can be used to assess tumour apoptosis in vivo and suggest that the clinical efficiency of docetaxel in HRPC is due to induction of apoptosis during multiple treatment cycles.