Weekly 1-hour infusion of paclitaxel. Clinical feasibility and efficacy in patients with hormone-refractory prostate carcinoma

Crosstalk between Microtubule Stabilizing Agents and Prostate Cancer

A variety of microtubule-stabilizing cytotoxic agents (MSA) with diverse chemical scaffolds have been discovered from marine sponges, microorganisms, and plants. Two MSAs, docetaxel and cabazitaxel, are the exclusive chemotherapeutics that convey a survival benefit in patients with castration-resistant prostate cancer (CRPC). Additional MSAs have been investigated for their potential in treating prostate cancer in both clinical and preclinical settings. Independent of promoting mitotic arrest, MSAs can suppress the nuclear accumulation of androgen receptor (AR), which is the driving force for prostate cancer cell growth and progression. The alternative mechanism not only helps to better understand the clinical efficacy of docetaxel and cabazitaxel for AR-driven CRPC but also provides an avenue to seek better treatments for various forms of prostate cancer. The dual mechanisms of action enable MSAs to suppress AR-null prostate cancer cell proliferation by cell mitosis pathway and to interfere with the AR signaling pathway in AR positive cells. MSA chemotherapeutics, being administered alone or in combination with other therapeutics, may serve as the optimal therapeutic option for patients with either castration-sensitive or castration-resistant prostate cancer. This review provides an overview of the anti-prostate cancer profiles (including preclinical and clinical studies, and clinical use) of diverse MSAs, as well as the mechanism of action.

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.

Treatment Options in Hormone-refractory Metastatic Prostate Carcinoma

Prostate cancer represents one of the most important health problems in industrialized countries. It is the second leading cause of cancer-related death in the United States. Therapeutic options are different according to the stage of the disease at the diagnosis. Patients with localized disease may be treated with surgery or radiation, whereas the treatment for patients with a metastatic disease is purely palliative. Hormonal treatment represents the standard therapy for stage IV prostate cancer, but patients ultimately become unresponsive to androgen ablation and are classified as hormone-refractory prostate cancer patients. The molecular mechanisms involved in progression in hormone resistance are characterized by mutations, down and up-regulation in the androgen receptor gene, mutations in p53 and over-expression of Bcl2 and other alterations in genes and in gene expression. The important thing is that we understand these mechanisms to define potential therapeutic agents for the treatment of hormone-refractory prostate cancer patients. Conventional options for patients with hormone-refractory prostate cancer include secondary hormone therapy, radiotherapy and cytotoxic chemotherapy. The commonest antineoplastic agents are mitoxantrone, estramustine and taxanes. Despite an improvement In the palliative benefit, none of these agents has demonstrated a beneficial impact on the overall survival of patients. Therefore, there is no standard therapy for these patients, thus we need new approaches which should be studied in clinical trials. The evaluation and incorporation of new agents into current treatment regimens could have a role in the treatment of hormone-refractory prostate cancer, but their efficacy has not yet been demonstrated.

Taxanes in the management of metastatic castration-resistant prostate cancer: efficacy and management of toxicity

Androgen deprivation is the therapy of choice in the majority of patients with metastatic prostate cancer. However, a state of castration resistance ultimately occurs after hormone therapy, thus defining metastatic castration-resistant prostate cancer (mCRPC). mCRPC has historically been considered a relatively chemoresistant tumor. However, due to its ability to improve survival and the quality of life in comparison with mitoxantrone, docetaxel has been established as the standard chemotherapeutic agent for first-line therapy since 2004. Moreover, recent results have shown that the novel taxane cabazitaxel is able to prolong the overall survival of patients with mCRPC previously treated with docetaxel. Even though these taxanes display a favorable toxicity profile, their routine use in clinical practice requires knowledge about the most frequent and distinct adverse events that may result from their administration.

Phase II trial of weekly ixabepilone in men with metastatic castrate-resistant prostate cancer (E3803): a trial of the Eastern Cooperative Oncology Group

Ixabepilone is an epothilone B analogue with activity in a variety of solid malignancies, including prostate cancer. The main dose-limiting toxicity of ixabepilone is myelosuppression when administered by using an every 3-week schedule. Here we evaluate the activity of a weekly ixabepilone in men with metastatic castrate-resistant prostate cancer to minimize hematologic toxicity.

PURPOSE

BMS-247550 (ixabepilone) is an epothilone B analogue with activity in taxane-resistant cancer cell lines. Here we report the activity and toxicity of ixabepilone, administered by using a weekly schedule, in men with metastatic castrate-resistant prostate cancer (CRPC).

EXPERIMENTAL DESIGN

Patients with metastatic CRPC received ixabepilone at 20 mg/m(2) intravenous weekly x 3, in 4-week cycles. This noncomparative study stratified patients to either a chemotherapy naive (CN), prior taxane (Tax) only, or 2 prior cytotoxic (TCx) chemotherapy arm. The primary endpoint was prostate-specific antigen response by using PCWG (Prostate Cancer Working Group) 1 criteria. Secondary endpoints included radiographic response when using RECIST (Response Evaluation Criteria In Solid Tumors).

RESULTS

In total, 124 patients were enrolled, of whom, 109 were eligible (35 CN, 42 Tax, and 32 TCx) for the primary response determination in this study. Prostate-specific antigen responses were seen in 12 (34.3%) of 35, 12 (28.6%) of 42, and 7 (21.9%) of 32 patients with the partial objective response in 5 (22.7%) of 22, 2 (8.0%) of 25, and 0 (0.0%) of 24 patients for the CN, Tax, and TCx arms, respectively. Significant (grade 3/4) neutropenia was seen in 6 (15.4%), 7 (14.6%), and 9 (25.0%); and grade 3/4 sensory neuropathy was seen in 8 (20.5%), 12 (25.0%), and 12 (33.3%) for CN, Tax, and TCx, respectively. Grade 3/4 thrombocytopenia was infrequent and seen in only one patient on the CN and the TCx arm.

CONCLUSION

Ixabepilone was found to have an acceptable toxicity profile when administered by using a weekly schedule with less myelosuppression compared with prior studies when using the every 3-week schedule. Single-agent activity was observed and met prespecified activity levels for the Tax treated arm.

Pilot trial of adjuvant paclitaxel plus androgen deprivation for patients with high-risk prostate cancer after radical prostatectomy: results on toxicity, side effects and quality-of-life

Therapeutic strategy remains unclear with no clear consensus for men with high-risk prostate cancer (PCa) after radical prostatectomy. We aimed to evaluate into a prospective randomized trial the effectiveness and feasibility of adjuvant weekly paclitaxel combined with androgen deprivation therapy (ADT) in these patients. A total of 47 patients with high-risk PCa were randomized 6 weeks after radical prostatectomy: ADT alone versus combination of ADT and weekly paclitaxel. Toxicity, quality-of-life and functional results were compared between the two arms. All 23 patients completed eight cycles of paclitaxel. Toxicity was predominantly of grade 1-2 severity. There were no differences in EORTC QLQ-C30 scores between the two groups and between baseline and last assessment at 24 months after surgery. Urinary continence was complete at 1 year after surgery for all patients and no significant differences were noted at each assessment between the two groups. The interim analysis of this trial confirms the feasibility of weekly paclitaxel in combination with ADT in men at high-risk PCa with curative intent. This adjuvant combined therapy does not alter quality-of-life and continence recovery after surgery plus ADT. A larger cohort is awaited to determine the oncological outcomes of this strategy.

Phase II trial of weekly patupilone in patients with castration-resistant prostate cancer

BACKGROUND

Drug resistance mechanisms can reduce response rate and duration in men with castration-resistant prostate cancer (CRPC) receiving docetaxel-based therapy. Patupilone (epothilone B), a microtubule-targeting agent, may be unaffected by some resistance mechanisms. Therefore, a phase II study assessed the patupilone safety and activity in CRPC patients with and without previous chemotherapy.

METHODS

CRPC patients received patupilone 2.5 mg/m(2) weekly for 3 weeks of a 4-week cycle. Patients were required to have measurable disease or prostate-specific antigen (PSA) progression (levels>20 ng/ml).

RESULTS

All 45 enrolled patients (median age, 69 years) were safety and response assessable. Sixty-four percent had previous chemotherapy (55% had previous taxane therapy). Patients received a median of three patupilone cycles. Patupilone was generally well tolerated. Ten (22%) patients experienced grade 3 diarrhea, six (13%) grade 3 fatigue, and one (2%) grade 3 neuropathy with no neutropenia or thrombocytopenia incidence. Six (13%) patients had >or= 50% decline in PSA (three had previous taxane therapy). No patient with measurable disease had a response. Median overall survival was 13.4 months.

CONCLUSIONS

The safety profile of weekly patupilone in CRPC patients compares favorably with that of other microtubule inhibitors. At the dose and schedule tested, patupilone demonstrated minimal activity in CRPC.

Activity of Weekly Paclitaxel in Advanced Hormone-Refractory Prostate Cancer

OBJECTIVE

We evaluated efficacy and toxicity of weekly paclitaxel in metastatic hormone-refractory prostate cancer (HRPC).

MATERIALS AND METHODS

Patients received weekly paclitaxel 80 mg/m2 by 1-hour intravenous infusion. A course of therapy consisted of 6 weekly treatments and 2 weeks rest. PSA response was defined as a PSA decrease not less than 50%, maintained for 4 weeks with stable or improved performance status.

RESULTS

The study enrolled 43 patients with metastatic HRPC diagnosed a median of 10.5 months before. Median age was 69 years (range, 58-86 years). Five had previous radioisotopes treatment for bone pain, 15 had previous treatment of metastatic hormone-refractory disease, mainly estramustine. The median number of weeks of therapy delivered each patient was 8 (range, 1-24 weeks; cumulative, 369 weeks). PSA response was registered in 13 patients of 36 evaluable for PSA response (36.1%; 95% confidence interval [CI], 20.8-53.8), with a median duration of 4.2 months. Among 16 patients evaluable for objective response, 5 partial responses (31.2%; 95% CI, 11.0-58.7) and 9 stable diseases were registered. Eleven (42.3%) of 26 patients presenting with cancer-related symptoms had improvement. Median survival time was 12.8 months (95% CI, 10.1-15.5) Therapy was associated with acceptable hematological toxicity (anemia grade 3, 16%; neutropenia grade 3-4, 12%) and moderate nonhematologic toxicities (thrombosis/embolism 10%; fatigue all grades, 60%).

CONCLUSION

Docetaxel every 3 weeks is the standard of care for metastatic HRPC, but our results suggest some activity and an acceptable toxicity of weekly paclitaxel.

Weekly paclitaxel and high-dose 5-fluorouracil plus leucovorin in hormone-refractory prostate cancer: In vitro combined effects and a Phase II trial

PURPOSE

Paclitaxel and 5-fluorouracil have been used to treat hormone-refractory prostate cancer with some success. In vitro data suggest that the combined cytotoxicity may be sequence dependent. Thus, we explored the combined effects of the 2 agents, both in vitro and in vivo.

PATIENTS AND METHODS

The combined cytotoxicity of paclitaxel and 5-fluorouracil, and the possible schedule dependence were studied in vitro using PC-3 and DU145 cells and the microculture tetrazolium assay. There were 23 patients with hormone-refractory prostate cancer treated with the regimen T-HDFL: paclitaxel 90 mg/m2 intravenously 1 hour on days 1 and 8; 5-fluorouracil 2000 mg/m2; and leucovorin 300 mg/m2 intravenous 24-hour infusion on days 2 and 9, which repeated every 21 days. The allowed percentage of bone marrow irradiation was 50%.

RESULTS

Significant synergistic cytotoxicity was seen only when paclitaxel was given 24 hours before 5-fluorouracil. With the T-HDFL regimen, 11 (52%) of the 21 evaluable patients had > or = 50% reduction of prostate-specific antigen, lasting for 6 weeks. Of the 7 patients with measurable disease, 2 had a partial response. Median overall survival was 14.1 months. Grade III/IV leukopenia occurred in 2 patients. There was no treatment-related death. Toxicities were well tolerated.

CONCLUSIONS

The combined cytotoxicity of paclitaxel and 5-fluorouracil is schedule dependent. It is feasible to administer weekly paclitaxel and high-dose 5-fluorouracil infusions in patients with hormone-refractory prostate cancer. Our findings may serve as an important rationale for future trial design.

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.

Current Indications for Chemotherapy in Prostate Cancer Patients

Recently, data from two randomized studies, TAX327 and SWOG 9916, which compared docetaxel-based chemotherapy to mitoxantrone-based therapy, have demonstrated that treatment with docetaxel can prolong life in a statistically significant way in patients with hormone refractory prostate cancer (HRPC). In the TAX237 trial the median overall survival rates for patients treated with docetaxel every 3 wk was 18.9 mo, compared with 16.4 mo for the patients in the control arm (p=0.009). Patients treated with the combination of docetaxel and estramustine in the SWOG trial had a significant improvement in median survival (18 mo vs 16 mo, p=0.01), longer progression-free survival (6 mo compared with 3 mo, p<0.0001), and a 20% reduction in the risk of death. The optimal timing of docetaxel-based chemotherapy is still unknown because there are no prospective clinical trials indicating whether earlier treatment is more effective than delayed treatment. There are now increasing options also for second-line therapies in the palliative treatment of HRPC, and ongoing studies on new drugs such as satraplatin and ixabepilone will define the role of these agents in this setting. Preliminary neoadjuvant and adjuvant chemotherapy studies in high-risk prostate cancer patients have demonstrated that these approaches are feasible and do not add morbidity to surgery or radiotherapy, but their impact on survival still needs to be proven in randomized studies.

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.

[Hormone-refractory prostate cancer. Modifications of the therapeutic strategies since chemotherapy proved its usefulness]

Back in the 90's it was difficult to have access to the conclusions of publications on HRPC. Homogeneity was very scarce regarding issues as significant as the definition of HRPC itself, patient selection, or evaluation of the responses to therapy. Consensus has currently been reached on such matters, and it is described in this text. Two works were published in late 2004 showing that docetaxel-based chemotherapy improved metastatic HRPC survival. Until then, the different treatments used could only provide symptomatic relief. But probably not all of the HRPC patients are eligible for primary docetaxel chemotherapy. The current debate focuses on determinating to which patients should chemotherapy be administered and at which time should it start, in order to exclude those patients at risk of experiencing its adverse effects without benefitting from its clinical advantages. Non-metastatic HRPC patients may be candidates to receiving secondary hormone manoeuvres before starting with chemotherapy. We will analyse in this review the changes occurred in the therapeutic strategies ever since chemotherapy showed its value, and we shall also disclose our attitude regarding treatment of these patients in daily practice.

Changing perspectives of the role of chemotherapy in advanced prostate cancer

The use of cytotoxic chemotherapy in advanced prostate adenocarcinoma has been validated by the recent demonstration of survival benefit in two large randomized phase III trials. Before publication of these landmark trials, SWOG 9916 and TAX 327, no chemotherapeutic regimen had shown survival benefit in the treatment of androgen independent prostate cancer (AIPC). These trials provide new encouragement for the use of chemotherapy in all stages of disease. Improved communication between medical and urologic oncologists and early patient referral for clinical trial participation remains essential for identifying new chemotherapeutic regimens with improved activity in AIPC and for defining the role of chemotherapy in earlier-stage disease. This article discusses the role of chemotherapy as the current standard of care for the treatment of AIPC and provides a historical perspective of the trials that preceded the development of current docetaxel-based regimens.

[Treatment options for hormone-refractory prostate cancer]

Surgical or medical androgen deprivation therapy in its multiple variants represents the standard therapeutic approach in the management of metastatic prostate cancer resulting in a primary response rate of about 90%. However, about 90% of the men treated will develop PSA progression within 3-4 years resulting in androgen-independent and later on hormone-refractory prostate cancer. Management of AIPCA and HRPCA still represents a therapeutic challenge despite the development of new and effective treatment options. PSA progression following primary ADT defines an androgen-refractory but still hormone-sensitive PCA which might respond to secondary hormonal manipulations such as antiandrogen withdrawal, addition of nonsteroidal antiandrogens, and administration of estrogens, ketoconazole and hydrocortisone, and somatostatin analogues. Secondary hormonal manipulations will result in a PSA decline >50% in about 60-80% of the patients with a mean duration of 7-17 months depending on the type of treatment. PSA progression following secondary endocrine treatment defines hormone-refractory prostate cancer (HRPCA) which might be treated by systemic chemotherapy. Based on the results of two prospective, randomized clinical phase III trials comparing docetaxel and mitoxantrone, docetaxel results in a statistically significant survival benefit of 2.5 months, a significantly higher PSA and pain response, and represents the treatment of choice in the management of HRPCA. Bisphosphonates such as zoledronate represent another cornerstone in the management of PSA-progressive PCA demonstrating a significant benefit with regard to the prevention of skeletal-related events. Furthermore, bisphosphonates might be indicated in the treatment of symptomatic bone pain as has been demonstrated for ibandronate and zoledronate. The current article critically reflects on the various therapeutic options in the management of PSA progression following primary androgen deprivation for advanced prostate cancer. The development, rationale, and results of systemic chemotherapy are discussed critically and a therapeutic algorithm is demonstrated.

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.

Randomized phase II study comparing paclitaxel and carboplatin versus mitoxantrone in patients with hormone-refractory prostate cancer

OBJECTIVES

Mitoxantrone/prednisone was the 2002 palliative reference treatment for hormone-refractory prostate cancer (HRPC). Paclitaxel and carboplatin has demonstrated antitumor activity in HRPC. The therapeutic benefit of such treatment was compared with that of mitoxantrone.

METHODS

A randomized Phase II study was conducted that included 40 patients with HRPC who had not undergone chemotherapy. Patients in arm A received paclitaxel (175 mg/m2 every 3-week cycle) and carboplatin (area under the curve of 5 every 3-week cycle). Patients in arm B received mitoxantrone (12 mg/m2 every 3-week cycle). All the patients treated were receiving low-dose prednisone. The primary endpoint was the prostate-specific antigen response.

RESULTS

The prostate-specific antigen response to paclitaxel and carboplatin was significantly greater (40% [95% confidence interval 18.5% to 61.5%] versus 10% [95% confidence interval 1% to 32%], P = 0.031) and more durable (8.6 versus 2 months, P = 0.015) than the response to mitoxantrone. A tendency was noted for patients with measurable disease who were receiving paclitaxel and carboplatin to have a somewhat greater objective response rate than those who received mitoxantrone (23% [95% confidence interval 5.3% to 55%] versus no objective response, P = 0.060). The median overall survival was 14.5 months for the paclitaxel and carboplatin arm compared with 11.1 months for the mitoxantrone arm. The group given paclitaxel and carboplatin had significantly greater rates of sensitive neuropathy (50% versus 0%, P = 0.00026).

CONCLUSIONS

The 3-week regimen of paclitaxel and carboplatin induced a greater and more durable prostate-specific antigen response than did mitoxantrone for HRPC treatment. The major additive toxicity induced was peripheral neuropathy due to paclitaxel. Investigations with paclitaxel and carboplatin regimens merit large Phase III studies.

Phase II trial evaluating a docetaxel-capecitabine combination as treatment for hormone-refractory prostate cancer

BACKGROUND

Docetaxel is a well-recognized drug in patients with hormone-refractory prostate cancer (HRPC), either alone or combined with estramustine. In this indication, a Phase II trial was conducted investigating a docetaxel-capecitabine combination.

METHODS

Forty-six patients presenting with documented HRPC were enrolled in the study. The treatment regimen consisted of docetaxel (D) at a dose of 35 mg /m2/week (intravenously, 3 consecutive weeks) plus oral capecitabine (C) at a dose of 625 mg/m2 twice daily (Days 5-18) every 28 days for 4 cycles. The primary endpoint was the biological response defined as a reduction in prostate-specific antigen (PSA) level > or =50%. Secondary endpoints were overall survival, safety, and quality of life.

RESULTS

Thirty of 44 assessable patients (68.2%) achieved a biological response, 14 of whom (31.8%) normalized their PSA value. The median overall survival time was 17.7 months (95% confidence interval, 15.8 to not reached). Four treatment cycles were completed by 87% of the patients. Hematologic toxicity was mild. The main Grade 3-4 toxicities were cutaneous toxicity (13.1%) and changes in nails (6.5%). Physical functioning and role scales were higher before treatment (P = .02 and P = .003, respectively), fatigue and diarrhea were more frequent during and after treatment (P = .0003 and P = .03, respectively), and pain was lower during and after treatment.

CONCLUSIONS

The results of the current study demonstrated the high efficacy of the DC combination in patients with HRPC, and the associated good tolerability. This combination offers a new alternative to the docetaxel-estramustine combination. Further randomized trials are warranted.

Phase II trial of oral uracil/tegafur plus leucovorin in patients with hormone-refractory prostate carcinoma

BACKGROUND

The current study evaluated the efficacy of oral uracil/tegafur (UFT) and leucovorin (LV) in patients with hormone-refractory metastatic prostate carcinoma.

METHODS

Twenty-eight patients with hormone-refractory metastatic carcinoma of the prostate who had undergone antiandrogen withdrawal and no more than 1 prior chemotherapy treatment were enrolled on a single-institution Phase II trial. Patients were treated with oral UFT at a dose of 300 mg/m2/d and oral LV at a dose of 90 mg/day for 28 days followed by 7 days off therapy on a 35-day cycle regimen.

RESULTS

Twenty-six patients were evaluable for response and toxicity. There was no response by objective criteria in 9 patients with measurable disease. Four responses by prostate-specific antigen (PSA) criteria (i.e., PSA decrease by > 50%) were noted (15%) lasting a mean of 20.5 weeks. Therapy was generally well tolerated, with 2 patients developing Grade 4 toxicity (1 patient each with diarrhea and hand-foot syndrome) and 4 patients having significant Grade 3 toxicity (anemia, hyperbilirubinemia, and vomiting) (Toxicity was graded according to the National Cancer Institute Common Toxicity Criteria). Six patients had stable disease by clinical, laboratory, and radiologic criteria for an average of 5 cycles of treatment (25 wks).

CONCLUSIONS

Although UFT and LV are generally well tolerated in the setting of hormone-refractory metastatic prostate carcinoma, the combination has a low level of activity. Its toxicity and activity is similar to that observed when intravenous 5-fluorouracil or capecitabine are given alone. It may be an option for further investigations in combination regimens.

Ixabepilone (Epothilone B Analogue BMS-247550) Is Active in Chemotherapy-Naive Patients With Hormone-Refractory Prostate Cancer: A Southwest Oncology Group Trial S0111

Purpose

The epothilones are a new class of tubulin-polymerizing agents with activity in taxane-sensitive and resistant tumor models. We evaluated ixabepilone (BMS-247550) in patients with metastatic hormone-refractory prostate cancer (HRPC).

Methods

Eligible patients had chemotherapy-naive metastatic HRPC, a Zubrod performance status of 0 to 2, and adequate organ function. All patients received BMS-247550 at 40 mg/m2 over 3 hours every 3 weeks. The primary end point was proportion of patients achieving a prostate-specific antigen (PSA) response.

Results

Forty-eight patients with metastatic HRPC were registered. Forty-two patients were eligible, with a median age of 73 years and a median PSA level of 111 ng/mL; 78% had bone-only or bone and soft tissue metastases, and 88% had objective radiologic disease progression at registration. Grade 3 and 4 adverse events (AEs) occurred in 16 and three patients, respectively. All grade 4 toxicities were neutropenia or leukopenia. The most frequent grade 3 AEs were neuropathy (eight patients), hematologic toxicity (seven patients), flu-like symptoms, and infection (five patients each). There were no grade 3/4 thrombocytopenia or grade 5 AEs. There were 14 confirmed PSA responses (33%; 95% CI, 20% to 50%); 72% of PSA responders had declines greater than 80%, and two patients achieved an undetectable PSA. The estimated median progression-free survival is 6 months (95% CI, 4 to 8 months), and the median survival is 18 months (95% CI, 13 to 24 months).

Conclusion

Ixabepilone has demonstrated activity in patients with chemotherapy-naive metastatic HRPC. Major toxicities were neutropenia and neuropathy. Further testing to define its activity relative to standard therapy is warranted.

Therapeutic options in androgen-independent prostate cancer: building on docetaxel

Of men with metastatic prostate cancer who undergo androgen ablation, 70-80% respond rapidly to therapy, as manifested by a reduction in prostate cancer-related symptoms and declines in serum prostate-specific antigen (PSA) level. Unfortunately, after a median of 18-24 months, nearly all patients with metastatic prostate cancer will progress to androgen independence. Until recently the standard of care for treating hormone-refractory prostate cancer (HRPCa) was the combination of mitoxantrone and prednisone, which palliated bone pain but did not extend survival. Two randomized trials with > 1700 patients showed for the first time a survival benefit for patients with HRPC treated with chemotherapy; when compared with mitoxantrone-based therapy, docetaxel based-therapy reduced the risk of death by 20-24%. Future trials in HRPC are attempting to improve the efficacy of docetaxel by incorporating new agents targeting angiogenesis, apoptosis, and signal transduction pathways; there is promising activity for these novel combinations in phase I and II studies. Concepts are also being refined about definitions of response and progressive disease, patient eligibility criteria, and the validity of surrogate markers of efficacy and survival, as shown by changes in PSA level.

Present status and perspectives in the treatment of hormone-refractory prostate cancer

The cornerstone in the treatment of de novo or recurrent metastatic prostate cancer is androgen deprivation. Unfortunately, nearly all patients will develop androgen-independent ('hormone-refractory') disease with progressive clinical deterioration and ultimately death. Chemotherapy has been shown to palliate symptoms of hormone-refractory disease but not to improve survival. Recently, two large phase III trials have demonstrated an overall survival advantage for patients treated with docetaxel-based regimens as compared to the best standard of care. Indeed, investigations into the pathophysiology of this malignancy, novel biological agents, skeletal protectants and radiopharmaceuticals are expanding the clinician's armamentarium and improving the patient's outcome.

In vitro assessment of cytotoxic agent combinations for hormone-refractory prostate cancer treatment

We have investigated new drug combinations of potential clinical value for treatment of hormone-refractory prostate cancer. Combinations of paclitaxel, carboplatin and mitoxantrone, and combinations of these three drugs with compounds targeting important pathways for cancer progression, 13-cis-retinoic acid and chelerythrine, were assessed. The drugs combinations were incubated for 72 h in steroid-free conditions with two androgen-independent cell lines, DU145 and PC3. Cytotoxicity assay was performed using resazurin and Hoescht 33342. Synergism and antagonism were measured by the combination index, and calculated for each combination by the median-effect method. All six compounds exhibited cytotoxic effects when tested alone. Paclitaxel exhibited the highest and 13-cis-retinoic acid the lowest effect on both cell lines. Paclitaxel demonstrated synergism or additivity with 13-cis-retinoic acid in both cell lines, whereas antagonistic effects were observed when it was tested in combination with carboplatin. Chelerythrine showed additive effects with mitoxantrone in both cell lines and with paclitaxel in PC3 cells. Our results suggest that combination of paclitaxel and 13-cis-retinoic acid, and of chelerythrine with mitoxantrone and paclitaxel, may have clinical value for the treatment of hormone-refractory prostate cancer.

[Current status of the prognostic value of molecular markers in patients with colorectal cancer and the prediction of response to adjuvant therapy]

Colorectal cancer is one of the best studied of all malignant diseases in terms of genetics and/or molecular prognostic factors. These factors, and relationships with prognosis, may have important implications especially in the design of surgical and adjuvant chemo-radiotherapy options. However, the true prognostic significance of all known factors has yet to be realised. We have reviewed the literature with specific focus on the role of molecular markers involved in prognosis and the prediction of response to adjuvant treatment.

The current role of chemotherapy in metastatic hormone-refractory prostate cancer

Since the publication of the Southwest Oncology Group (SWOG) 99-16 and TAX 327 studies, which demonstrated a survival benefit for docetaxel-based therapy, clinicians for the first time have a therapy to offer men with metastatic prostate cancer that is not merely palliative in its effects. Phase 2 and phase 3 trials are now building on the findings of SWOG 99-16 and TAX 327 by evaluating the potential of combination taxane-based therapies, such as docetaxel plus high-dose calcitriol, docetaxel-estramustine-bevacizumab, and docetaxel-thalidomide. The optimal timing of docetaxel-based chemotherapy is still unknown, as there are no prospective clinical trial data to indicate whether earlier treatment (eg, at the time of prostate-specific antigen failure) is more or less effective than later treatment (eg, in metastatic and/or symptomatic disease).

A phase II trial of docetaxel and vinorelbine in patients with hormone-refractory prostate cancer

Recent studies of docetaxel have demonstrated improved survival over mitoxantrone and prednisone in patients with hormone-refractory prostate cancer (HRPC), supporting the study of novel docetaxel-containing regimens as primary therapy or following initial docetaxel-based therapy. To evaluate the combination of docetaxel and vinorelbine in the treatment of patients with HRPC, 40 patients with proven adenocarcinoma of the prostate with progressive metastatic disease despite androgen ablation were enrolled onto this phase II trial. Patients were treated with docetaxel 60 mg/m2 on day 1 and vinorelbine 15 mg/m2 on days 1 and 8 of a 21-day cycle. All patients received dexamethasone 8 mg twice daily for 4 days starting 1 day prior to the docetaxel infusion. After the first three patients were enrolled, filgrastim was added on days 2-6 and 9-13. Of the 40 patients enrolled, 19 had no prior chemotherapy and 21 had received at least one prior chemotherapy regimen. Of the 19 patients without prior chemotherapy and the 21 with prior chemotherapy, 7 (37%) and 6 (29%) , respectively, demonstrated a decrease in prostate specific antigen by > 50% maintained for at least 4 weeks. Out of eight patients with measurable disease, one achieved a partial response and four demonstrated stable disease. There was one patient with deep vein thrombosis, and febrile neutropenia was noted in only three patients after the protocol was modified to include filgrastim support. The combination of docetaxel and vinorelbine with filgrastim was well tolerated and active against HRPC in patients with or without prior chemotherapy.

Novel cytotoxic and biological agents for prostate cancer: Where will the money be in 2005?

In 2004, docetaxel-based chemotherapy became the first treatment capable of extending life in androgen-independent prostate cancer. The era of therapeutic nihilism in this disease has thus been put to rest and a broad range of agents is being tested with the goal of improving on the successes of 2004. Lessons learned from other tumour types will need to be applied to prostate cancer in order to harness the bounty of available ideas. Target amplification or activating mutations and not merely the presence of a target are likely to be important to the success of targeted agents. Thus, the promise of the current crop of targeted agents is most likely to be realised when pursued in the context of well-credentialed targets and tested in highly translational clinical trials that are capable not only of assessing tumour response, but also of evaluating the status of the targeted pathway. The most promising agents in clinical development are reviewed.

Clinical trials in metastatic prostate cancer – Has there been real progress in the past decade?

Hormone refractory prostate cancer remains a challenge. While only palliative treatment strategies were available for the past several decades, many promising agents have been investigated over the past decade. Of those the taxanes appeared with significant anti-tumor activity and recently, two large randomized controlled trials demonstrated for the first time, a survival and palliative benefit with docetaxel based chemotherapy. In the current era, recurrent disease after local treatment for localized disease is diagnosed long before evidence of systemic disease. With earlier institution of hormonal treatments, patients are becoming "hormone refractory" earlier in the course of their disease with considerable long life expectancy. Hence, there is a greater need than ever for more treatment options for this expanding group of patients. A number of new systemic therapies have recently emerged, based on a deeper understanding of prostate cancer biology. Novel chemotherapeutics such as the epothilones, molecularly targeted therapies against angiogenesis, the proteosome and endothelin receptor antagonists, as well as biological agents such as anti-sense oligonucleotides are being tested as part of the armamentarium. Key to progress in the therapy of this fatal disease is the commitment and timely enrolment of prostate cancer patients in clinical trials.

Chemotherapy for androgen-independent prostate cancer

The evolution of taxanes as treatment for androgen-independent prostate cancer hes emerged from both the laboratory and clinic. Docetaxel is a potent in vitro inhibitor of Bcl-2, an antiapoptotic gene. Phase I and II studies with docetaxel alone or in combination with estramustine demonstrated promissing median survivals of 14--23 months, higher than what would have been expected for historic controls. Two randomized trials have proven the superiority of docetaxel based treatment in improving survival in men with androgen-independent prostate cancer. SWOG 99-16 and TAX 327 found that docetaxel-based therapy reduced the risk of death by 20--24% when compared to mitoxantrone-based therapy. Future trials will build on docetaxel-based combinations with novel targeted agents.

Is there a role for chemotherapy in prostate cancer?

There is evidence from randomised-controlled trials that patients with symptomatic hormone-refractory prostate cancer may experience palliative benefit from chemotherapy with mitoxantrone and prednisone. This treatment is well tolerated, even by elderly patients, although the cumulative dose of mitoxantrone is limited by cardiotoxicity. Treatment with docetaxel or paclitaxel, with or without estramustine, appears to convey higher rates of prostate-specific antigen response in phase II trials, but is more toxic. Large phase III trials comparing docetaxel with mitoxantrone have completed accrual. There is no role for chemotherapy in earlier stages of disease except in the context of a well-designed clinical trial.

Phase II Randomized Trial of Weekly Paclitaxel with or Without Estramustine Phosphate in Progressive, Metastatic, Hormone-Refractory Prostate Cancer

This study was conducted to determine the similarity of response rates and safety produced by weekly paclitaxel with or without oral estramustine in patients with metastatic hormone-refractory prostate cancer. Between December 1998 and December 1999, 163 patients were randomized to receive 28-day cycles of paclitaxel 100 mg/m2 on days 2, 9, and 16 plus estramustine 280 mg orally 3 times a day on days 1-3, 8-10, and 15-17, or to receive paclitaxel 100 mg/m2 alone on days 1, 8, and 15. Objective response was defined as a > oe = 50% decrease in prostate-specific antigen (PSA) maintained for 4 weeks with stable or improved performance status. Response rates included 37 partial responses for paclitaxel/estramustine (47%) and 22 partial responses for paclitaxel (27%; P < 0.01). Median duration of response was 15.1 months for paclitaxel/estramustine and 15.5 months for paclitaxel; median survival was 16.1 months and 13.1 months, respectively (P = 0.049). Common toxicities for both treatments included neutropenia, gastrointestinal events, neuropathy, and asthenia. Thromboembolic events were more frequent in the paclitaxel/estramustine arm (no prophylactic anticoagulants). The rate of PSA decline for paclitaxel/estramustine was almost 2 times that of paclitaxel (47% vs. 27%), with acceptable toxicity. Multivariate analysis of prognostic factors affecting survival was not significant for treatment arm (P = 0.08). Although the incidence of thromboembolic events appeared to be increased in the paclitaxel/ estramustine arm, the addition of estramustine was responsible for a 20% increase in the rate of PSA decline. Neither treatment arm had significant impact on quality of life as measured by the Functional Assessment of Cancer Therapy-Prostate quality of life questionnaire. This study produced encouraging data; further studies of paclitaxel/ estramustine are recommended.

[Taxanes in the chemotherapy of hormone-refractory prostate carcinoma]

Prostate cancer represents one of the most prevalent malignancies in men. Standard therapy of metastatic prostate cancer consists of androgen deprivation, which is a palliative therapy yielding a clinical response of limited duration. In hormone-refractory prostate cancer (HRPC), response to chemotherapy with regimens available until about ten years ago has been disappointing. Nowadays, due to increasing life expectancy and earlier diagnosis and therapy of prostate cancer, more patients with hormone-refractory disease are still in relatively good overall condition. With the taxanes, much more effective cytostatic substances for chemotherapy of HRPC are available today. Using modern taxane-based chemotherapy, effective palliation of pain can be achieved in 50-70% of patients with HRPC, while retaining an acceptable quality of life. There is also evidence for improved overall survival after taxane-based chemotherapy, although this remains to be proven by ongoing studies. This article presents an overview of current studies investigating the outcome after taxane-based chemotherapy, as well as new therapeutic approaches in combination with docetaxel.

[Chemotherapy of hormone refractory prostate carcinoma]

An increasing life expectancy and the growing number of largely healthy older men have lead to more patients with hormone insensitive relapses after palliative hormone or curative therapy for prostate cancer. After 10 years without therapeutic improvement for hormone refractory prostate cancer, the introduction of new substances has led to a revival of chemotherapy. Although a definitive cure is still not possible, such chemotherapy fulfils important palliative criteria-good toleration and an improvement in quality of life-in addition to distinct long-term remission. For example, taxane as a monotherapy or in combination with estramustine is effective and well tolerated while mitoxantrone in combination with prednisolone, although of limited effectiveness, leads to a substantial reduction in symptoms. Although evidence for increased longevity through modern chemotherapy is available, this has still not been definitively demonstrated. The substantial reduction in pain and therapy related morbidity frequently makes chemotherapy for hormone refractive prostate cancer a superior alternative to simple pain and complication management.

Weekly paclitaxel plus estramustine combination therapy in hormone-refractory prostate cancer: a pilot study

BACKGROUND

Paclitaxel used in combination with estramustine has been shown to exert synergistic cytotoxicity in patients with hormone-refractory prostate cancer (HRPC). There have been few reports of this therapy in an Asian male population.

METHODS

Nine patients with progressive metastatic HRPC completed at least one cycle of combination therapy employing weekly paclitaxel plus estramustine. Paclitaxel was given weekly for 3 weeks as a 2-h intravenous infusion at a dose of 100 mg/infusion. The cycle was repeated every 4 weeks. A dose of 280 mg of oral estramustine was administrated twice daily for 21 days from the first day of each cycle. Both efficacy and toxicity were recorded.

RESULTS

Grade 1 sensory neuropathy was seen in three patients (33%) and grade 4 thrombopenia/anemia was seen in one patient (11%). Performance status improved in three of seven patients (43%), while six patients (67%) showed a 50% or greater decline in prostate-specific antigen levels. Two of these patients experienced significant improvement in bone pain. One patient died of cardiac infarction during this trial and another died of disseminated intravascular coagulopathy subsequent to gastrointestinal bleeding. An additional patient suffered non-fatal pulmonary infarction. The one-year median survival rate was 22.2% and the overall survival period was 36 weeks.

CONCLUSION

Although weekly paclitaxel plus estramustine may pose a significant risk, this combination may have a beneficial effect on the quality of life HRPC patients. A well-designed phase I-II trial in an Asian male population is highly recommended.

Current strategies in the management of hormone refractory prostate cancer

Prostate cancer is the most common cancer diagnosed in American males, and is the second leading cause of cancer-related deaths. Most patients who develop metastatic disease will initially respond to androgen deprivation, but response is invariably temporary. Most patients will develop androgen-independent ("hormone-refractory") disease that results in progressive clinical deterioration and ultimately death. This progression to androgen independence is accompanied by increasingly evident DNA instability and alterations in genes and gene expression, including mutations in p53, over-expression of Bcl2, and mutations in the androgen receptor gene, among others. Treatment options for hormone refractory disease include intensive supportive care, radiotherapy, bisphosphonates, second-line hormonal manipulations, cytotoxic chemotherapy and investigational agents. A post-treatment reduction in the level of prostate specific antigen (PSA) by 50% has been shown to correlate with survival and has been accepted by consensus as a valid endpoint in clinical trials. Chemotherapeutic agents such as mitoxantrone, estramustine, and the taxanes have yielded improved response rates and palliative benefit, but not improved survival. Therefore, current efforts must be focused on enrolling patients onto clinical trials of investigational agents with novel mechanisms of action, and on using survival, time to progression, and quality of life as end points in routine clinical practice.

Pharmacotherapy of hormone refractory prostate cancer: new developments and challenges

Hormone refractory prostate cancer (HRPC) remains a challenge in the management of prostate cancer patients. With the widespread use of PSA (prostate specific antigen), recurrent disease after local treatment for localised prostate cancer is usually diagnosed long before evidence of metastatic disease. In many cases, hormonal manipulations are started at the time of biochemical relapse and therefore, patients become 'hormone refractory' earlier in the course of their disease, frequently with a good performance status, often with no evidence of metastatic disease, and they still face a considerably long life expectancy. Despite these changes, the need for more options in the treatment of HRPC is obvious. The pharmacological treatments that are in use and those that are under investigation for this group of patients will be discussed and include: cytotoxic agents including the microtubule inhibitors, alone and in combination with other conventional or experimental therapies such as calcitriol or thalidomide; treatment with epothilone analogues; endothelin receptor antagonists; palliative therapy with bisphosphonates, bone-targeted radiopharmaceuticals and other developing treatments such as vaccines, gene therapies and monoclonal antibodies.

What's new in the treatment of advanced prostate cancer?

Increased insight into the biology of prostate cancer and the emergence of new therapeutic strategies and chemotherapeutic agents has changed approaches in treating patients with advanced prostate cancer. After secondary hormonal manipulations, new approaches include: second-line hormonal therapy, chemotherapy, immunotherapy with granulocyte macrophage-colony stimulating factor (GM-CSF) therapy, dendritic cell therapy, gene vaccination therapy, inhibition and/or blockade of growth factor receptors or growth factor receptor pathways, inhibition of neo-angiogenesis and inhibition of invasion and metastases.

Pharmacological treatments for prostate cancer

Recently, chemotherapy for prostate cancer has been primarily reserved for the palliation of symptoms secondary to prostate cancer. Chemotherapy regimens and new approaches are being developed that offer new hope of response and improved survival to men with prostate cancer. This paper discusses pharmacological strategies that are under investigation: cytotoxic agents and biological or targeted therapies, including the microtubule inhibitors (taxane/taxoids, vinorelbine) alone and in novel combinations with other experimental agents such calcitriol, thalidomide or flavopiridol (cell-cycle inhibitor) and treatment with epothilone analogues; endothelin receptor antagonists; other novel strategies such as vaccine therapy (GVAX; Cell Genesys) and prostate-specific membrane antibodies; and bisphosphonates.

An active regimen of weekly paclitaxel and estramustine in metastatic androgen-independent prostate cancer

OBJECTIVES

The efficacy of weekly high-dose paclitaxel in androgen-independent prostate carcinoma and its cytotoxic synergy with estramustine led to the evaluation of a weekly schedule of paclitaxel and estramustine in this Phase II trial.

METHODS

Patients were eligible if they had metastatic prostate adenocarcinoma with objective progression or rising prostate-specific antigen (PSA) levels despite androgen deprivation therapy and antiandrogen withdrawal. Prior radiation and/or one prior chemotherapy regimen was permitted. A Zubrod performance status of 2 or less and adequate bone marrow and hepatic and renal function were required. Estramustine was administered orally at a dose of 280 mg three times daily on days 1 to 3, 8 to 10, and 15 to 17. Paclitaxel (150 mg/m2) was administered as a 1-hour intravenous infusion on days 2, 9, and 16. Therapy was repeated every 28 days (one cycle).

RESULTS

Twenty-eight patients were enrolled (median age 71.5 years). Fifteen patients had measurable disease (nine nodal and seven visceral) and 13 had bone-only metastases. A total of 116 cycles of therapy were delivered (median 4 cycles per patient, range 1 to 12). Nine patients required dose reduction. The predominant toxicities consisted of grade 3 neuropathy in 6 patients and grade 3 and 4 neutropenia in 4 patients, with one hospitalization for febrile neutropenia. Three patients had thrombotic manifestations: one deep venous thrombosis and two non-Q wave myocardial infarctions. Of the 28 patients, 26 were assessable for response. Of 13 patients with measurable disease, 5 demonstrated a partial response (1 in the liver and 4 in the lymph nodes), and 8 of 13 patients with bone-only metastases had a 50% or greater decrease in PSA level. Three patients had a 90% or greater decline in PSA. The overall PSA response rate was 61.53% (95% confidence interval 38.1% to 74.2%). The median time to progression was 4.64 months, and the median survival was 13 months.

CONCLUSIONS

The combination of weekly estramustine and paclitaxel is active in metastatic androgen-independent prostate cancer.

State-of-the-art treatment of metastatic hormone-refractory prostate cancer

Initial therapy for advanced prostate cancer includes androgen ablation by surgical or medical castration. Still, nearly all men with metastases will progress to hormone-refractory prostate cancer (HRPC). Current U.S. Food and Drug Administration-approved agents for the treatment of HRPC include mitoxantrone and estramustine, although the vinca alkaloids and the taxanes have shown promising activity in single-agent phase II trials. Combinations of these agents induce a biochemical response in greater than 50% of patients, but the median duration of response is approximately 6 months. Overall survival of patients treated with these combinations is approximately 18-24 months. Studies are ongoing to develop novel therapies that target specific molecular pathways or mechanisms of chemotherapy resistance. Novel agents under development include growth factor receptor inhibitors, antisense oligonucleotides, bisphosphonates, and cell differentiating agents. Evaluation and incorporation of these agents into existing treatment regimens will guide us in the development of more active regimens in the treatment of HRPC.

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.

Phase I trial of oral estramustine and 3-hr infusional paclitaxel for the treatment of hormone refractory prostate cancer

PRECIS

Estramustine 600 mg/m2 can be administered safely with 225 mg/m2 of paclitaxel if administered as a 3-hr infusion for the treatment of hormone refractory prostate cancer. Significant anti-tumor activity has been reconfirmed despite the change in schedule of administration of the paclitaxel.

PURPOSE

This phase I study was conducted to identify the maximum tolerated dosage of paclitaxel administered as a 3-hr infusion combined with a stable dosage of estramustine capsules daily in men with hormone refractory prostate cancer. A secondary endpoint was to assess anti-tumor efficacy in this targeted patient population.

PATIENTS AND METHODS

Twenty-six male patients, all with hormone refractory prostate cancer were enrolled in this trial. Estramustine was administered at a dosage of 600 mg/m2 daily, and paclitaxel was dose-escalated in cohorts from 125 to 250 mg/m2 administered as an infusion over 3 hr every 21 days. Patients were treated until maximum response was achieved, or toxicity or progressive disease precluded further treatment. Toxicity to determine maximum tolerated dose was assessed only during the first 3-week cycle.

RESULTS

The maximum tolerated dose of paclitaxel on this schedule was 225 mg/m2 based on unacceptable dose-limiting fatigue observed at the next higher dosage level. Other grade 3 or 4 events included myelosuppression, left ventricular dysfunction, elevated liver function tests, deep venous thrombosis, vomiting, and development of depression. Using a response criteria of prostate specific antigen decline of > 50% persisting for a minimum of 6 weeks, eight of 26 patients responded (30.8%). Two of seven patients with documented soft-tissue disease experienced > 50% reductions in size of lesions or number of sites. The median response duration was 6 months, and the median survival time was 16 months.

CONCLUSION

The recommended phase II dose of paclitaxel is 225 mg/m2 when administered over 3 hr in combination with estramustine. This regimen has an acceptable toxicity profile, is a convenient schedule, and results in significant antitumor activity even in a heavily pre-treated population of patients.

Highlights of contemporary issues in the medical management of prostate cancer

This paper highlights contemporary issues in the medical management of prostate cancer. Controversies surrounding adjuvant and neo-adjuvant hormonal therapy in localized prostate cancer are reviewed, as well as the use of chemohormonal therapy in high risk localized disease. The latent period of asymptomatic biochemical progression prior to clinical progression is an opportunity to evaluate new non-toxic therapies. In patients with advanced metastatic disease hormonal therapy and new alternatives are discussed. Chemotherapy in hormone refractory prostate cancer (HRPC) is extensively covered as well as the emerging role of molecular-targeted therapies.

Pharmacodynamics of non-break weekly paclitaxel (Taxol) and pharmacokinetics of Cremophor-EL vehicle: results of a dose-escalation study

We characterized the toxicity and determined the maximum tolerated dose of non-break weekly paclitaxel (Taxol) in chemotherapy-naive cancer patients, and studied pharmacokinetics of the formulation vehicle Cremophor-EL with this schedule. Twenty-three patients with primary refractory solid tumors received weekly paclitaxel at the dose range of 70-200 mg/m2. As dose-limiting toxicity we defined granulocytopenia grade > or =2 causing a treatment delay for more than 2 weeks, or febrile neutropenia or grade >2 organ-specific toxicity. Plasma kinetics of Cremophor-EL were analyzed over the first five courses of treatment. Non-break weekly paclitaxel was feasible at doses up to 110 mg/m2, while granulocytopenia precluded scheduled administration of doses > or =130 mg/m2. Clinically relevant peripheral neurotoxicity tended to occur at around 1500 mg/m2 cumulative dosage at weekly doses > or =110 mg/m2. Detectable Cremophor-EL levels were found in all pre-dose samples, but there was no evidence of accumulation up to the sixth course. Our results, discussed in the light of an overview of published data, suggest that chronic weekly administration of paclitaxel is feasible and with a lack of significant accumulation of Cremophor-EL levels at doses up to 90 mg/m2.