Epirubicin combined with estramustine phosphate in hormone-resistant prostate cancer: a phase II study

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.

The role of doxorubicin and epirubicin in the treatment of patients with metastatic hormone-refractory prostate cancer

Advanced hormone-refractory prostate cancer (HRPC) is characterized by prevalently osteoblastic bone metastases which are what mostly affect these patients' quality of life and make the assessment of response to treatment particularly difficult by commonly used criteria. HRPC cannot be cured by any available therapeutic option, and chemotherapy has to be still considered as a palliative treatment. The anthracyclines doxorubicin (Dox) and epirubicin (Epi), alone or in combination with other agents, have been extensively used in the treatment of HRPC, but controversial results have been reported. The majority of reviewed studies reported a pain reduction in >50% of patients receiving Dox or Epi, suggesting a substantial palliative effect by their use in metastatic HRPC. The weekly schedule of anthracyclines seemed to achieve similar results to the 3-weekly schedule but with a better toxicity profile. Although the toxic adverse effects were usually manageable when anthracyclines were combined with other agents, toxicity was severe by a number of aggressive regimens. Docetaxel is today approved for the treatment of HRPC, and must be considered the standard platform on which new agents may be combined. Given that HRPC includes a heterogeneous group of patients with variable rates of tumour growth, the combination of docetaxel with active agents such as anthracyclines may deserve further clinical investigation.

New standards in the chemotherapy of metastatic hormone-refractory prostate cancer

Hormone-refractory prostate cancer (HRPC) is a major issue in Western countries and the second leading cause of cancer death in North American men. In the prostate-specific antigen era, most HRPCs are currently diagnosed in asymptomatic patients based on biochemical failure, with increasing demand for active treatment. Until recently, chemotherapy for HRPC patients was not considered a standard of care due to the absence of clear data evidencing an overall survival benefit. In fact, few Phase III studies conducted in the 1980s and early 1990s had documented a superiority over corticosteroids alone in terms of biochemical response (declines in serum prostate-specific antigen levels) and quality of life, but not survival. Due to their impact on pain control, mitoxantrone and prednisone were long considered the best regimen for symptomatic HRPC patients. In recent years, more chemotherapeutic agents have been tested, among which the microtubule inhibitors (vinca alkaloids and taxanes) have obtained the most promising results in Phase II trials and have entered Phase III testing. Two well-designed randomized trials have changed this scenario. Both compared docetaxel (with or without estramustine) against mitoxantrone and prednisone, and demonstrated a significant advantage not only in terms of response, pain control and quality of life, but also in terms of overall survival. Which patients need to be treated, the regimen of choice and duration of chemotherapy will be the next questions to be answered in the coming years in the field of HRPC, along with the role of new signal transduction inhibitors and other targeted therapies.

A phase II study of vinorelbine and estramustine in patients with hormone-resistant prostate cancer

INTRODUCTION

This phase II study was designed to evaluate the efficacy of vinorelbine in combination with estramustine in patients with chemotherapy-naïve hormone-refractory prostate cancer.

MATERIAL AND METHODS

Patients received vinorelbine (i.v. 25 mg/m2) on days 1 and 8 every 3 weeks and estramustine (oral, 600 mg/m2) daily. Eligible patients were required to have progressive metastatic disease following the first hormonal manipulation.

RESULTS

Of the 51 patients enrolled (median age = 69 years), 84% presented bone involvement and 75% had at least two organs involved at the time of study entry and 47 were evaluable for treatment efficacy. Prostate specific antigen (PSA) response (> or =50% decrease) which was the primary efficacy criterion was reported in 21 patients (41.2%) in the intent-to-treat (ITT) population and in 20 patients (48.8%) in the per protocol (PP) population. Of the 7 patients with measurable disease, 2 achieved partial response. Median progression-free survival and overall survival were 4.7 months (range: 1.9-8.6) and 14.3 months (range: 4.2-21.2), respectively. Grade 3-4 neutropenia was reported in 6.1% of patients and in 1% of cycles. The incidence of complicated neutropenia (febrile neutropenia reported in 1 patient and septic shock with severe neutropenia reported in 2 patients) was 5.8%. The most frequent grade 3-4 non-haematological events (% of patients > or =5%) included anorexia (10%), thrombosis/embolism (8%), vomiting and hypotension (6% each). There were 3 toxic deaths (5.9 %) resulting from pulmonary embolism, angina pectoris, and septic shock. The impact of combined chemotherapy on the quality-of-life (QL) of the patients was assessed between baseline and the first evaluation scheduled at 6 weeks indicated a marked reduction in pain while the rest of the symptoms remained stable. Overall, health status improved slightly over the treatment period.

CONCLUSIONS

This study confirmed that the combination of vinorelbine and estramustine is an active regimen in patients with hormone-resistant prostate cancer who had not been treated previously with chemotherapy. Main toxicities included complicated neutropenia even though the incidence of severe neutropenia was low. We observed a higher incidence of toxic deaths which could have been related to the regimen of estramustine used in the study.

Thromboembolic events with estramustine phosphate-based chemotherapy in patients with hormone-refractory prostate carcinoma: results of a meta-analysis

BACKGROUND

Combinations of cytotoxic chemotherapy with estramustine phosphate (EMP), a nornitrogen mustard-estrogen conjugate, are used to treat patients with hormone-refractory prostate carcinoma (HRPC). However, thromboembolic events (TE), including deep venous thrombosis (DVT), pulmonary embolism, stroke, myocardial infarction, and arterial thrombosis, are significant toxicities of these regimens. The current study sought to establish the rate of TE and to determine risk factors for TE.

METHODS

A MEDLINE-based search identified EMP-based clinical trials published in the English-language peer-reviewed literature after 1990 in which > or = 20 patients with HRPC were enrolled and TE were clearly documented. Patient characteristics and the dose of EMP given were analyzed to determine their association with the rate of TE.

RESULTS

Twenty-three studies, enrolling a total of 896 patients, were included in the analysis. The overall risk of TE was 0.07 (95% confidence interval [95% CI], 0.05-0.11). The risk of DVT was 0.06 (95% CI, 0.04-0.09). The risks of all other types of TE were <0.01. Using univariate logistic regression analysis, the dose of EMP administered, baseline patient age, and baseline prostate-specific antigen level were not found to be associated with the total risk of TE. The rates of total TE and DVT may be inflated because one of the analyzed studies initially had a very high rate of DVT (25%) when compared with the others.

CONCLUSIONS

The rate of TE in men with HRPC who are treated with EMP-based regimens is significant, but it does not appear to be related to the dose of EMP. Whether TE can be prevented with anticoagulant prophylaxis remains to be determined.

Synergistic and antagonistic combinations of drugs in human prostate cancer cell lines in vitro

Microtubulin binding agents such as docetaxel have significant preclinical and clinical activity in the treatment of hormone-refractory prostate cancer. We have previously used median-effect analysis to define both synergistic and antagonistic drug combinations which may be of value in management of human disease. These studies extend our findings in defined prostate cancer cell lines. A semi-automated microtiter culture system was used. Docetaxel was combined with 18 other agents, incubated with DU 145, LnCaP or PC 3 prostate cancer cell lines for 72 h and the cells then incubated with MTT to determine cytotoxic effect. Both doublet and triplet combinations were examined. Synergy and antagonism as measured by the combination index were determined for each combination. The non-mutually exclusive criterion was applied. Docetaxel demonstrated cytotoxic additive effects or synergy with -retinoic acid, cyclosporin A and vinorelbine in all three cell lines. Docetaxel combined with either epirubicin or doxorubicin displayed cytotoxic synergistic effects in hormone-refractory DU 145 and PC 3 cell lines. In contrast, drugs which have been combined clinically to treat hormone-refractory prostate cancer, i.e. cisplatin, carboplatin or etoposide, were antagonistic when combined with docetaxel. We conclude that combinations of docetaxel with either -retinoic acid or vinorelbine may offer an enhanced cytotoxic effect in the management of hormone-refractory prostate cancer and need to be evaluated for therapeutic effect. The combination of docetaxel with an anthracycline was also synergistic in the two hormone-refractory cell lines, DU 145 and PC3, thus suggesting a potential role in advanced disease after endocrine failure. Combinations of docetaxel with platinum or etoposide may lead to subadditive effects in treatment.

Weekly epirubicin in patients with hormone-resistant prostate cancer

The aim of this study was to investigate the benefit of weekly epirubicin in the treatment of metastatic hormone-resistant prostate cancer. One hundred and forty-eight patients with metastatic hormone-resistant prostate cancer received weekly 30-min intravenous infusions of epirubicin 30 mg m(2) of body surface area. The primary end-point was palliative response, defined as a reduction in pain intensity and an improvement in performance status. The secondary end-points were the duration of the palliative response, quality of life and survival. Fifty-seven (44%) of the 131 evaluable patients met the primary criterion of palliative response after six treatment cycles and 73 (56%) after 12 cycles; the median duration of the response was 9 months (range 1-11). The median global quality of life improved in 52% of the patients after six cycles and in 68% after 12 cycles. The 12- and 18-month survival rates were respectively 56 and 31%, with a median survival of 13+ months (range 1-36). The treatment was well tolerated: grade 3 neutropenia was observed in 8% of the patients, grade 3 anaemia in 7%, and grade 3 thrombocytopenia in 3%. None of the patients developed grade 4 toxicity or congestive heart failure. Weekly epirubicin chemotherapy can lead to a rapid and lasting palliative result in patients with metastatic HRPC, and have a positive effect on the quality of life and survival.

Chemotherapy in advanced androgen-independent prostate cancer 1990-1999: a decade of progress?

BACKGROUND AND PURPOSE

A great number of clinical research studies have been reported in the field of chemotherapy for advanced androgen-independent prostate cancer during the last ten years. The aims of the present review were to assess their impact on management of the disease and on survival of patients.

METHODS

The review of full published reports was facilited by the use of a MEDLINE computer search.

RESULTS

Clinical research studies have focused on defining guidelines for eligibility criteria and accurate endpoints for patients to be enrolled onto clinical trials and developing new agents or combination of drugs including estramustine phosphate. Any combination of current chemotherapy has no impact on overall survival of patients. Among drugs in development, only the promising activity observed with docetaxel deserves randomized trials to assess its impact on survival. The major innovative advance of the 90s is the demonstration of the impact of chemotherapy (mitoxantrone + prednisone) on quality of life as compared to prednisone alone. A greater and longer-lasting improvement in quality of life along with a concomitant decrease in costs was observed.

CONCLUSIONS

At the present time, chemotherapy should be considered as a palliative treatment in patients with symptomatic androgen-independent disease. The enrollment of patients into clinical trials dealing with quality of life as primary endpoint is strongly solicited. A standard methodology should be used in phase II trials with a primary goal of selection of agents which should progress to randomized trials using survival as an endpoint. Hopefully new specific strategies targeted to reverse the molecular changes that underlie prostate tumorigenesis should rapidly impact the multimodality management of AIPC in the third millenium.

Recent advances in the treatment of prostate cancer

As new evidence for prostate cancer treatment has emerged in the last few years, longstanding controversies in the treatment of prostate cancer have resurfaced. A number of long-held tenets of prostate cancer therapy have been revisited, sometimes with surprising and challenging results. Although neoadjuvant hormonal therapy prior to radical prostatectomy decreases positive surgical margin rates, longer follow-up is needed to support survival improvement of this combined modality therapy. Androgen deprivation combined with radiation therapy appears to improve disease-free survival (and survival in one series) in patients with locally advanced cancer. Another approach to locally advanced prostate cancer using three-dimensional conformal radiation therapy may improve long term outcome. The data are currently insufficient to conclude that interstitial low dose rate brachytherapy is equivalent to conventional treatments: patients with small tumor volumes and low Gleason grade seem to obtain more benefit, whereas for large tumors with higher gleason grades this approach seems inferior to conventional treatments. In advanced prostate cancer recent data suggest that immediate hormonal therapy improves survival. In this group of patients the use of maximum androgen blockade remains controversial but may adversely affect quality of life compared to orchiectomy alone. Intermittent hormonal therapy may improve quality of life, although effect upon survival is unknown. Chemotherapy in combination with androgen deprivation is currently being studied as front-line therapy in advanced prostate cancer. Palliative benefit of chemotherapy for hormone refractory prostate cancer remains an important endpoint; survival advantage has not been seen in any randomized trials. Suramin may delay disease progression in hormone refractory prostate cancer. Many aspects of prostate cancer treatment will remain controversial until results of large, randomized trials with longer follow-up are available.

Evaluation of estramustine phosphate combined with weekly doxorubicin in patients with androgen-independent prostate cancer

Thirty-one patients with progressive metastatic prostate cancer refractory to first- or second-line hormonal therapy were treated with a combination of daily oral estramustine phosphate (600 mg) and weekly intravenous doxorubicin (20 mg/m2). Eighteen (58%) patients demonstrated a biologic response with a 50% or more serum prostate-specific antigen decline. The median duration of biologic response was three months. Five (45%) of the 11 patients with measurable lesions achieved a partial response in liver or retroperitoneal lymph nodes. The median duration of these objective responses was four months. Of 22 patients who required analgesics at the onset of the study, six (27%) achieved a significant reduction of pain. The combination of doxorubicin and estramustine phosphate was tolerated on an outpatient schedule. The occurrence of severe toxicities required suspension of therapy in six patients. At the end of the observation time, all patients but one had died, 29 of progressive prostatic cancer and one of toxicity. The median survival time from the onset of chemotherapy was 12 months. The administration of weekly doxorubicin with phosphate estramustine appears to be a safe combination for those patients with hormone-resistant prostate cancer who require chemotherapy. The benefit of chemotherapy should be investigated using relevant quality-of-life criteria in future trials.