Doxorubicin and dose-escalated cyclophosphamide with granulocyte colony-stimulating factor for the treatment of hormone-resistant prostate cancer

Angiogenesis and prostate cancer: MicroRNAs comes into view

Angiogenesis, the formation of new blood vessels, is an important stage in the growth of cancer. Extracellular matrix, endothelial cells, and soluble substances must be carefully coordinated during the multistep procedure of angiogenesis. Inducers and inhibitors have been found to control pretty much every phase. In addition to benign prostatic hyperplasia, prostatic intraepithelial neoplasia, and angiogenesis have a critical role in the initiation and progression of prostate cancer. MicroRNA (miRNA) is endogenous, short, non-coding RNA molecules of almost 22 nucleotides play a role in regulating cellular processes and regulating several genes' expression. Through controlling endothelial migration, differentiation, death, and cell proliferation, miRNAs have a significant function in angiogenesis. A number of pathological and physiological processes, particularly prostate cancer's emergence, depend on the regulation of angiogenesis. Investigating the functions played with miRNAs in angiogenesis is crucial because it might result in the creation of novel prostate cancer therapies that entail regulating angiogenesis. The function of several miRNAs and its targeting genes engaged in cancer of the prostate angiogenesis will be reviewed in this review in light of the most recent developments. The potential clinical utility of miRNAs potentially a novel therapeutic targets will also be explored, as well as their capacity to control prostate cancer angiogenesis and the underlying mechanisms.

Angiogenesis and Anti-Angiogenic Treatment in Prostate Cancer: Mechanisms of Action and Molecular Targets

Prostate cancer (PC) is the most common cancer in men and the second leading cause of cancer-related death worldwide. Many therapeutic advances over the last two decades have led to an improvement in the survival of patients with metastatic PC, yet the majority of these patients still succumb to their disease. Antiagiogenic therapies have shown substantial benefits for many types of cancer but only a marginal benefit for PC. Ongoing clinical trials investigate antiangiogenic monotherapies or combination therapies. Despite the important role of angiogenesis in PC, clinical trials in refractory castration-resistant PC (CRPC) have demonstrated increased toxicity with no clinical benefit. A better understanding of the mechanism of angiogenesis may help to understand the failure of trials, possibly leading to the development of new targeted anti-angiogenic therapies in PC. These could include the identification of specific subsets of patients who might benefit from these therapeutic strategies. This paper provides a comprehensive review of the pathways involved in the angiogenesis, the chemotherapeutic agents with antiangiogenic activity, the available studies on anti-angiogenic agents and the potential mechanisms of resistance.

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 of hormone-refractory prostate cancer

Objective. An increasing number of patients with prostate cancer develop hormone-refractory disease after standard treatment modalities. In these patients, early clinical trials with chemotherapy produced disappointing response rates. However, clinical trials that employ response criteria such as prostate-specific antigen (PSA) and clinical benefit response have produced encouraging responses. This article reviews current and future treatment options for the management of hormone-refractory prostate cancer.

Data Sources. A MEDLINE search for the years 1978 to 1998 was completed. The following terms were used in our search: prostate cancer, hormone-refractory, treatment, and chemotherapy. Relevant articles referenced in the literature obtained in our MEDLINE search were reviewed.

Study Selection. Randomized and nonrandomized clinical trials were used in our review. Clinical trials using prostate-specific antigen or a palliation of symptoms as primary criteria for response were given priority.

Data Synthesis. Several genetic alterations, including the overexpression of bcl-2 or mutations in p53, may lead to the development of hormone-refractory prostate cancer. Agents such as estramustine and taxanes, which affect microtubule function and potentially modulate bcl-2, appear to be particularly active in the treatment of hormone-refractory prostate cancer. In addition, mitoxantrone as well as other agents has been shown to be beneficial in improving the quality of life in patients with hormone-refractory prostate cancer.

Conclusion. Hormone-refractory prostate cancer is not a chemotherapy-resistant disease as once believed; significant progress in the treatment of hormone-refractory prostate cancer has been made with new combinations of chemotherapy agents. Promising new treatments are currently under evaluation to assess their potential benefit over the standard treatment modalities that are currently available.

High-resolution flow cytometry: a suitable tool for monitoring aneuploid prostate cancer cells after TMZ and TMZ-BioShuttle treatment

If metastatic prostate cancer gets resistant to antiandrogen therapy, there are few treatment options, because prostate cancer is not very sensitive to cytostatic agents. Temozolomide (TMZ) as an orally applicable chemotherapeutic substance has been proven to be effective and well tolerated with occasional moderate toxicity especially for brain tumors and an application to prostate cancer cells seemed to be promising. Unfortunately, TMZ was inefficient in the treatment of symptomatic progressive hormone-refractory prostate cancer (HRPC). The reasons could be a low sensitivity against TMZ the short plasma half-life of TMZ, non-adapted application regimens and additionally, the aneuploid DNA content of prostate cancer cells suggesting different sensitivity against therapeutical interventions e.g. radiation therapy or chemotherapy. Considerations to improve this unsatisfying situation resulted in the realization of higher local TMZ concentrations, sufficient to kill cells regardless of intrinsic cellular sensitivity and cell DNA-index. Therefore, we reformulated the TMZ by ligation to a peptide-based carrier system called TMZ-BioShuttle for intervention. The modular-composed carrier consists of a transmembrane transporter (CPP), connected to a nuclear localization sequence (NLS) cleavably-bound, which in turn was coupled with TMZ. The NLS-sequence allows an active delivery of the TMZ into the cell nucleus after transmembrane passage of the TMZ-BioShuttle and intra-cytoplasm enzymatic cleavage and separation from the CPP. This TMZ-BioShuttle could contribute to improve therapeutic options exemplified by the hormone refractory prostate cancer. The next step was to syllogize a qualified method monitoring cell toxic effects in a high sensitivity under consideration of the ploidy status. The high-resolution flow cytometric analysis showed to be an appropriate system for a better detection and distinction of several cell populations dependent on their different DNA-indices as well as changes in proliferation of cell populations after chemotherapeutical treatment.

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.

Histone deacetylase inhibitors sensitize prostate cancer cells to agents that produce DNA double-strand breaks by targeting Ku70 acetylation

This study reports a histone deacetylation-independent mechanism whereby histone deacetylase (HDAC) inhibitors sensitize prostate cancer cells to DNA-damaging agents by targeting Ku70 acetylation. Ku70 represents a crucial component of the nonhomologous end joining repair machinery for DNA double-strand breaks (DSB). Our data indicate that pretreatment of prostate cancer cells with HDAC inhibitors (trichostatin A, suberoylanilide hydroxamic acid, MS-275, and OSU-HDAC42) led to increased Ku70 acetylation accompanied by reduced DNA-binding affinity without disrupting the Ku70/Ku80 heterodimer formation. As evidenced by increased Ser(139)-phosphorylated histone H2AX (gammaH2AX), impaired Ku70 function diminished cellular capability to repair DNA DSBs induced by bleomycin, doxorubicin, and etoposide, thereby enhancing their cell-killing effect. This sensitizing effect was most prominent when cells were treated with HDAC inhibitors and DNA-damaging agents sequentially. Mimicking acetylation was done by replacing K282, K317, K331, K338, K539, or K542 with glutamine via site-directed mutagenesis, which combined with computer docking analysis was used to analyze the role of these lysine residues in the interactions of Ku70 with DNA broken ends. Mutagenesis of K282, K338, K539, or K542 suppressed the activity of Ku70 to bind DNA, whereas mutagenesis of K317 or K331 with glutamine had no significant effect. Moreover, overexpression of K282Q or K338Q rendered DU-145 cells more susceptible to the effect of DNA-damaging agents on gammaH2AX formation and cell killing. Overall, the ability of HDAC inhibitors to regulate cellular ability to repair DNA damage by targeting Ku70 acetylation underlies the viability of their combination with DNA-damaging agents as a therapeutic strategy for prostate cancer.

Vinorelbine, doxorubicin, and prednisone in androgen-independent prostate cancer

BACKGROUND

Ultimately, patients with metastatic prostate cancer progress on androgen ablation therapy. The investigation of new chemotherapeutic regimens for the treatment of androgen-independent prostate cancer (AIPC) is essential. The authors conducted a Phase II trial with vinorelbine, doxorubicin, and daily prednisone (NAP) to investigate the antitumor activity and palliative response of this regimen in patients with AIPC.

METHODS

Forty-six patients entered this Phase II combination chemotherapy trial. Patients were treated with both vinorelbine and doxorubicin at doses of 20 mg/m2 on Days 1, 8, and 15 every 28 days and prednisone 5 mg twice daily. Endpoints included prostate-specific antigen (PSA) response and palliation, as measured by the Functional Assessment of Cancer Therapy-Prostate (FACT-P) instrument, the Brief Pain Inventory Scale, and a narcotic analgesic log.

RESULTS

The median follow-up for all 46 patients was 13.4 months. Fifty-two percent of patients had impaired performance status at baseline. One responding patient remained on NAP and was progression-free at 11.5 months. Thirty-nine patients progressed, 3 patients died prior to response assessment, and 3 patients refused therapy. The median overall survival was 57 weeks (95% confidence interval [95% CI], 36-76 weeks), and the median time to disease progression was 17 weeks (range, 11-24 weeks). The PSA response among the 36 patients who completed 3 cycles of NAP was 42% (95% CI, 26-59%). There was a statistically significant improvement in quality of life measured both by the FACT-General instrument (P = .03) and the FACT-P instrument (P = .0006) over the 3 months compared with baseline measurements. Pain medicine use also improved: The median morphine equivalents among patients who were taking pain medications at the time of study enrollment showed a substantial decline after 1 cycle of treatment that was maintained. Pain (as assessed by the Brief Pain Inventory) improved compared with baseline pain at the 2nd-month assessment (worst pain, P = .08; least pain, P = .02; and average pain, P = .003). Overall, the regimen was tolerated well. The most common side effects were mild fatigue and gastrointestinal complaints (all of which were Grade 1 or 2 [according to Version 2.0 of the Expanded Common Toxicity Criteria]). Seventeen patients (37%) experienced Grade 3 or 4 neutropenia. Five patients (11%) developed a cardiac ejection fraction of <50% during treatment and had doxorubicin discontinued. No patients developed clinical congestive heart failure.

CONCLUSIONS

The NAP combination produced substantive palliation and a moderate response rate in men with AIPC.

Continuous low-dose (metronomic) chemotherapy on rat prostate tumors evaluated using MRI in vivo and comparison with histology

Continuous low-dose (metronomic) therapy, based on cyclophosphamide (CTX) combined with thalidomide (Tha), was evaluated on Dunning prostate R3327-AT1 rat tumors. Significantly delayed tumor growth (P < .001) was observed with oral CTX alone at a low dose (metronomic cyclophosphamide or M-CTX; 30 mg/kg per day) or combined with Tha. To investigate dynamic changes in tumor physiology during early stages of treatment, magnetic resonance imaging (MRI) was applied before and during the M-CTX or M-CTX + Tha therapy. Dynamic contrast-enhanced MRI revealed significant changes in the tumor center by day 3 (P < .01); by day 7, only a thin peripheral tumor region showed high signal enhancement. There was a significant correlation between poorly enhancing fraction on day 7 and ultimate tumor growth delay (P < .02). The apparent transverse relaxation rate (R2*) showed similar baseline tumor heterogeneity, but no obvious changes with growth or therapy. Histology confirmed substantial necrosis in the tumor center, leaving a thin live peripheral rim. Immunohistochemistry showed a significant increase in vascular endothelial growth factor, and apoptotic tumor and vascular endothelial cells. These results show the efficacy of the metronomic CTX +/- Tha for delaying tumor growth and indicate that MRI provides insights into the mode of action and early indication of efficacy.

Unexpected response of hormone-refractory prostate cancer to treatment with an antileukemic chemotherapy regimen

Our patient was a 61-year-old man with hormone-refractory prostate cancer and a rapidly rising serum prostate-specific antigen level. During the course of therapy for prostate cancer, abnormal blood counts and subsequent bone marrow biopsy led to a diagnosis of acute lymphoblastic leukemia. He was treated with a chemotherapeutic regimen in standard use for lymphoblastic leukemia, which resulted in an unusual response of his prostate cancer, with declining serum prostate-specific antigen levels that had reached undetectable levels at the time of the patient's death from acute sepsis and leukemic relapse. Autopsy showed minimal evidence of prostate cancer, localized to the prostate.

Oral low-dose cyclophosphamide in metastatic hormone refractory prostate cancer (MHRPC)

The chemotherapeutic approach to hormone-refractory metastatic prostate cancer (MHRPC) for a long time included only estramustine. Then, attempts have been made with other various agents as cyclophosphamide, vinblastine, etoposide, taxanes and carboplatinum. Although the new drugs and combinations have increased the response rate of MHRPC, they have had no impact on the natural history of MHRPC, which is about 1 year as median time of survival. After an occasional observation of prolonged response in a patient with MHRPC treated with a very well tolerated oral low-dose of cyclophosphamide, from February 1996 to October 2002, seven more patients with MHRPC and progressive disease were consecutively recruited. Response to treatment was evaluated by conventional radiological procedures and/or serial serum PSA measurements. The decline of PSA value was considered to assess the response consistent with the response guidelines from the prostate specific antigen-working group. All eight studied patients continuously received oral low dose cyclophosphamide until progression or the occurrence of significant toxicity. So far three patients (37.5%) progressed (PD), two (25%) showed PR and the three remaining SD. Response rate was 25%, and clinical benefit occurred in 62.5% of the studied patients. In the five patients with clinical benefit on cyclophosphamide median duration of clinical benefit, PR and SD were 9, 24+ and 8 months, respectively. In these five patients median overall survival times from cyclophosphamide and from the first regimen of chemotherapy were 17 and 33+ months respectively, while in the three patients with PD they were 4 and 13 months. The same interval times in patients with > or =50% decline of serum PSA were 29 and 50.5 months, while in those with <50% decline of the same marker, they were 13 and 32 months, respectively. Grade 2 or 3 neutropenia were observed in all the studied patients. In four (50%) of them pulmonary and urinary infections that were easily cured by the common antibiotics occurred. These data suggest that the metronomic use of cyclophosphamide, given alone, has similar or higher activity with lower toxicity than when administered with other active drugs. So it can be an useful option before or after the use of other single or combined potentially active chemotherapeutic agents.

9-Nitrocamptothecin as second line chemotherapy for men with progressive, metastatic, hormone refractory prostate cancer: Results of the CALGB 99901

BACKGROUND

Institution of early hormone therapy in the PSA era coupled with demonstration of clinical benefit with chemotherapy in hormone refractory prostate cancer (HRPC) and acceptance of PSA decline as a surrogate for response has resulted in introduction of chemotherapy earlier in the natural history of disease. There now exists a need to identify, effective agents for second line chemotherapy. 9-nitrocamptothecin (9-NC) a novel, oral camptothecin analogue was tested as second line chemotherapy for patients with progressive hormone refractory prostate cancer.

PATIENTS AND METHODS

Eligible patients had metastatic hormone refractory prostate cancer with performance status (0-1) following progression on at least 1 prior cytotoxic chemotherapy. 9-NC was administered orally at the dose of 1.5 mg/m2/d for 5 days each week for 3 weeks, followed by rest for 1 week. Response was evaluated after 2 cycles according to the guidelines set forth for Phase II trials in HRPC by the PSA working group.

RESULTS

Thirty-five patients were recruited to the study within a period of 6 months; 33 were evaluable for analysis. No patients had a >50% decline in PSA levels. Two out of 8 (25%) patients with measurable disease and 5/25 (20%) patients with nonmeasurable disease showed stable disease. The median time to disease and PSA progression was 2 months [95% confidence interval (CI), 0.9-2.8]. The median overall survival was 10 months (95% CI = 5-12). Seven patients are alive after a median follow-up of 23 months.

CONCLUSIONS

9-nitrocamptothecin failed to elicit clinical or PSA responses. Further study in pretreated HRPC patients is not warranted.

Phase II trial of oral cyclophosphamide, prednisone, and diethylstilbestrol for androgen-independent prostate carcinoma

BACKGROUND

The authors evaluated the combination of oral cyclophosphamide, oral prednisone, and diethylstilbestrol (DES) in patients with androgen-independent prostate carcinoma (AIPC).

METHODS

Thirty-seven patients with prostate carcinoma refractory to androgen ablation who had undergone antiandrogen withdrawal (if previously treated with an antiandrogen) were enrolled in the current study. They were treated with oral cyclophosphamide 100 mg per day on Days 1-20, prednisone 10 mg per day continuously, and DES 1 mg continuously, on a 30-day cycle. Warfarin 1 mg per day was given as prophylaxis for thrombosis. Patient levels of prostate-specific antigen (PSA) were monitored on a monthly basis, with imaging studies every 3 months. Patients continued to receive therapy until disease progression or the occurrence of significant toxicity. The effect of therapy on the patient's quality of life was assessed using the Functional Assessment of Cancer Therapy-Prostate.

RESULTS

Thirty-six patients were evaluable for response. Of the 36 patients, 15 (42%) had a 50% or greater decline in PSA levels from pretreatment levels and 1 patient (6%) with measurable disease had a partial response to therapy. The median duration of response was 4.5 months (range, 4-18 months). The overall median survival period was 16.4 months. The treatment was well tolerated, with only three patients removed from the study for toxicities associated with treatment. One patient, who had been treated for more than 24 months, developed acute leukemia. Quality of life evaluation in 17 patients showed a significant improvement in responders, whereas nonresponders had no deterioration while receiving therapy.

CONCLUSIONS

Cyclophosphamide, prednisone, and DES represent a well tolerated, low-cost combination therapy with significant activity in the treatment of patients with AIPC.

Bi-weekly epirubicin, etoposide and low-dose dexamethasone for hormone-refractory prostate cancer

BACKGROUND

Recent studies have demonstrated the efficacy and favorable toxicity profile of chemotherapy regimens given at lower doses and frequent intervals. The aim of our study was to evaluate the efficacy and toxicity of a bi-weekly chemohormonal regimen consisting of epirubicin, etoposide, and low-dose dexamethasone (EED) in patients with hormone-refractory prostate cancer (HRPC).

METHODS

We treated a total of 32 patients who had failed hormonal therapy and antiandrogen withdrawal. Chemotherapy was given every 2 weeks and consisted of epirubicin (30 mg/m2 intravenously, day 1) and etoposide (50 mg/m2 orally, days 1-7). Dexamethasone (1.5 mg orally, every other day) was given continuously until disease progression. Twenty patients (63%) had received prior treatment with estramustine phosphate. Each patient's pain response was evaluated according to analgesic use. Toxicity was graded using the Common Toxicity Criteria (version 2.0).

RESULTS

Prostate-specific antigen (PSA) levels showed a decline of 50% or greater in 16 of 32 patients (50%, 95% confidence interval [CI], 32-68%) with a median time to biochemical progression of 5 months (range, 4-9 months). The median survival for all patients was 10.5 months (range, 3-35 months). Four of 10 patients (40%) with measurable soft tissue lesions achieved partial response according to standard criteria. Eleven of 23 symptomatic patients (48%, 95% CI, 27-69%) experienced an improvement in pain with a median duration of 6 months. The regimen was tolerated well by the patients, with only four patients (12%) having grade 3 leukopenia.

CONCLUSION

Chemohormonal EED regimen proved to be active and well-tolerated in patients with HRPC.

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.

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.

Liposomal Doxorubicin for the Treatment of Hormone-Refractory Prostate Cancer

There is a pressing need for new agents to treat hormone-refractory prostate cancer (HRPC). Doxorubicin has shown modest activity in this setting, but its use is limited by its toxicities. Liposomal encapsulation of doxorubicin appears to promote enhanced tumor accumulation in some tumor types, and toxicity appears to be reduced. A phase II trial of liposomal doxorubicin was therefore conducted in patients with HRPC. Fourteen patients with progressive HRPC were treated. For the first dose only, patients were randomized to receive either doxorubicin 50 mg/m2 or liposomal doxorubicin 50 mg/m2 in order to evaluate exploratory pharmacokinetics. For all subsequent cycles, all patients received liposomal doxorubicin 50 mg/m2. Response to therapy was assessed with serial measurements of serum prostate-specific antigen (PSA) and sequential imaging studies. All 14 patients were evaluable for response and toxicity. Two patients (14%) had declines in serum PSA of > or = 50%. The first patient had a baseline PSA of 34.7 ng/mL and a nadir of 17.0 ng/mL. The second patient had a baseline PSA of 5580.0 ng/mL and a nadir of 200.7 ng/mL. The latter of these 2 patients had an unambiguous improvement in bone scan and a reduction in pain. Treatment was well tolerated overall. One patient was removed from treatment after the development of a grade 3 infusion reaction with the first cycle of liposomal doxorubicin. Neutropenia was the most common toxicity; in only 1 case was it grade 3, and no cases of grade 4 were seen. Doxorubicin plasma concentrations were best fit by a linear, two-compartment model. Liposomal doxorubicin plasma concentrations were best fit by a linear, one-compartment model. Treatment with liposomal doxorubicin was well tolerated overall. While monotherapy with liposomal doxorubicin has only modest activity in the treatment of HRPC, it may be of interest to study this agent as part of combination chemotherapy.

Treatment options in hormone-refractory prostate cancer: current and future approaches

Prostate cancer is the second leading cause of cancer mortality among men in Western countries. The initial treatment of advanced prostate cancer is suppression of testicular androgen production by medical or surgical castration, but nearly all men with metastases will develop disease progression. Patients with hormone refractory prostate cancer (HRPC) have a median survival of approximately 18 months and no therapy has yet demonstrated a definitive survival advantage. However, in the past several years, a number of promising new treatment strategies have emerged. One of the most important new treatment strategies involves secondary hormonal manipulation after the failure of primary androgen deprivation. This approach is predicated on the recognition that HRPC is a heterogeneous disease and some patients may respond to alternative hormonal interventions despite the presence of castrate levels of testosterone. Until recently, cytotoxic chemotherapy was felt to be relatively ineffective in the treatment of HRPC. Combination regimens incorporating new active agents have demonstrated significant activity in this setting, renewing interest in the use of chemotherapy to treat HRPC. Recent advances in the understanding of prostate cancer biology have led to the development of drugs directed against precise molecular alterations in the prostate tumour cell. Biologic agents now in development include those capable of altering signal transduction, blocking angiogenesis, inhibiting cell cycle progression, and stimulating apoptosis. In addition, many types of immune therapies are showing promise. Evaluating these agents, and incorporating them into existing regimens, are major goals of ongoing clinical research in advanced prostate cancer.

The treatment challenge of hormone-refractory prostate cancer

BACKGROUND

Both the demographics and treatment of hormone-refractory prostate cancer (HRPC) are changing. Patients are younger and healthier, with fewer comorbidities. The "no treatment until symptoms" approach is disappearing. Chemotherapy is increasingly being utilized.

METHODS

The authors review the steps involved in hormone management before chemotherapy is considered. The roles for chemotherapy in current clinical trials are examined.

RESULTS

Effective hormonal management of the prostate cancer patient incorporates an understanding of the stages of hormone sensitivity and prescribing additional interventions beyond simple castration. Once hormone refractoriness is established, the combination of mitoxantrone and prednisone has become a standard chemotherapeutic approach. New agents such as docetaxel are being tested in phase III trials against mitoxantrone plus prednisone.

CONCLUSIONS

HRPC is now regarded as a chemotherapy-sensitive tumor. The goals of chemotherapy in HRPC are to decrease PSA level and improve quality of life. New agents and combinations are needed to improve survival.

Phase I trial of escalating doses of paclitaxel combined with fixed doses of cisplatin and doxorubicin in advanced endometrial cancer and other gynecologic malignancies: a Gynecologic Oncology Group study

PURPOSE

The primary objective of this phase I trial was to determine the feasibility of administering a combination of paclitaxel, cisplatin, and doxorubicin with or without granulocyte colony-stimulating factor (G-CSF) in patients with advanced endometrial and other gynecologic cancers.

PATIENTS AND METHODS

Patients were chemotherapy-naive. Doxorubicin was administered as a brief infusion, paclitaxel for 3 hours, and cisplatin for 60 minutes. Treatments were repeated every 3 weeks. For most dose levels, the cisplatin and doxorubicin were fixed at 60 mg/m(2) and 45 mg/m(2), whereas the paclitaxel was escalated in successive cohorts from 90 to 250 mg/m(2). Patients who had received previous radiotherapy to the whole pelvis were escalated separately from those who had not.

RESULTS

Eighty patients received 320 cycles of therapy. When G-CSF was not used, myelosuppression prevented escalation beyond the starting dose for patients with or without previous pelvic radiotherapy. When G-CSF was added, neurotoxicity became dose-limiting for both groups. Ten patients were removed from the study for asymptomatic declines in ejection fraction, but no symptomatic congestive heart failure was observed. Major antitumor responses occurred in 46% of patients (six of 13) with measurable endometrial carcinoma and 50% of patients (eight of 16) with measurable cervical carcinoma.

CONCLUSION

The combination of paclitaxel, doxorubicin, and cisplatin at relevant single-agent doses is active and feasible with the addition of G-CSF. A regimen of cisplatin 60 mg/m(2), doxorubicin 45 mg/m(2), and paclitaxel 160 mg/m(2) with G-CSF support is recommended for further testing.

Endothelium-derived factors as paracrine mediators of prostate cancer progression

BACKGROUND

Vascular endothelium represents a complex network of cells producing a large number of active substrates affecting physiologic, metabolic, and immunologic properties of the whole organism, as well as particular organs or tissues. The potential influence of endothelium-derived paracrine factors on prostate cancer progression has only begun to be examined.

METHODS

This review summarizes recent literature on endothelium-derived factors, including vasoactive agents, peptide growth factors, cytokines, and colony-stimulating factors, involved in the development and progression of prostate cancer.

RESULTS

Endothelial cells produce an array of active substrates, many of which have been shown to influence prostate cancer growth. Available data demonstrate the positive impact of such molecules as endothelin-1, basic FGF, TGF-beta, IL-6, and IL-8 on prostate cancer progression. Many other endothelium-derived factors NO, IGF, PDGF, IL-1, G-CSF, and GM-CSF (Nitric Oxide, Insulin-Like Growth Factor, Platelet-Derived Growth Factor, Interleukin-1, Granulocyte Colony Stimulating Factor, and Granulocyte-Macrophage Colony Stimulating Factor) are, at best, implicated in prostate cancer growth, and in most cases support cancer progression.

CONCLUSIONS

A better understanding of endothelium-derived factors, as paracrine mediators of prostate carcinogenesis and progression, should aid in the development of novel therapeutic strategies.

A phase II trial of irinotecan in hormone-refractory prostate cancer

Irinotecan is a DNA topoisomerase I inhibitor that has a wide spectrum of activity against human tumors in both preclinical and clinical studies. To evaluate the efficacy of irinotecan in hormone-refractory prostate cancer, we conducted a phase II study in 15 men with metastatic, PSA-progressive disease after primary androgen deprivation. Irinotecan was administered at a dose of 125 mg/m2 weekly for four weeks followed by a two-week rest period; cycles were repeated every six weeks. Response was assessed by evaluation of serial changes in the serum PSA. None of fifteen patients had a decline in PSA of greater than 50%; eight patients had stable disease as a best response. None of three patients with measurable disease had a partial or complete response. Toxicity was primarily hematologic and gastrointestinal, with 40% of patients requiring dose modification due to granulocytopenia and 20% requiring intravenous fluid supplementation after development of diarrhea. There were no treatment-related deaths. We conclude that irinotecan in the dose and schedule used in this trial does not have significant activity against hormone-refractory prostate cancer.

Chemotherapy for hormone refractory prostate cancer

New combinations have been developed that show significant activity in therapy for hormone refractory prostate cancer. Several of these are designed to address specific cellular targets unique to prostate cancer. To date, the major benefits of these therapies have been palliative in nature, resulting in an improvement in quality of life, particularly with the combination of mitoxantrone and prednisone. None of these agents or regimens have been shown to affect survival significantly, and none can be considered to be standard therapy for this disease. Nonetheless, the success of these regimens in inducing response has challenged the skepticism concerning the appropriateness of chemotherapy for patients with advanced prostate cancer. The ability to slow and even reverse the growth of far advanced disease raises the possibility that the application of these regimens earlier in the course of the disease will have a more significant impact on the morbidity and, in the long run, on the mortality of prostate cancer. It is hoped that the enrollment of patients into properly designed clinical trials of new agents and combinations will result in the development of therapy with proven efficacy in the near future.

Pyrazoloacridine for the treatment of hormone-refractory prostate cancer

There is a pressing need for new agents for the treatment of hormone-resistant prostate cancer (HRPC). Pyrazoloacridine (PZA) has antitumor activity in several in vitro and in vivo tumor systems, and was selected for testing in clinical trials by the National Cancer Institute (NCI). We conducted a phase II trial of PZA for the treatment of HRPC. Seventeen male patients with HRPC were treated with PZA at 750 mg/m2 i.v. given over a period of 3 hr every 3 weeks. Response to therapy was assessed with serial measurements of serum prostate-specific antigen (PSA) and sequential imaging studies. The 17 patients were treated and fully evaluable. One patient experienced a significant decrease in PSA, from over 10,000 ng/ml to 423 ng/ml, along with an improvement in bone scan findings. However, no other patient obtained an objective or PSA response (overall PSA response rate = 5.9%). Median survival duration was 15.3 months. Toxicity was moderate. If PSA is used as a marker of response, single-agent PZA appears to lack efficacy in the treatment of HRPC. However, the one unambiguous response, and the favorable toxicity profile observed, may warrant further evaluation of this agent.

Early clinical experience with liarozole (Liazal) in patients with progressive prostate cancer

Liarozole (Liazal) is the first retinoic acid (RA) metabolism blocking agent (RAMBA) in clinical practice. RAMBA therapy promotes differentiation and inhibits proliferation by increasing endogenous RA in tumours. Liarozole was investigated in two open-label pilot studies of 100 patients with progressive prostate cancer in relapse despite previous androgen ablation. Liarozole (150-300 mg twice daily, for > or = 1 month) produced > or = 50% reduction in prostate specific antigen (PSA) serum levels in 15 of 30 evaluable patients in study 1 (50%) and 10 of 55 patients in study 2 (18%). PSA responders had more marked reductions in prostatic acid phosphatase, alkaline phosphatase and symptom scores for bone pain and urological symptoms, and improved general well being. Plasma levels of adrenal androgens did not alter during chronic treatment with liarozole nor at adrenocorticotrophic hormone (ACTH) stimulation test. Liarozole did not alter plasma levels of adrenal androgens or cortisol. Cortisol response to ACTH stimulation was slightly blunted. Liarozole was generally well tolerated. Dermatological adverse events were probably related to increased intracellular RA. Liarozole appears to be a promising treatment option in prostate cancer.

Expression and function of colony-stimulating factors and their receptors in human prostate carcinoma cell lines

BACKGROUND

The predeliction for prostate carcinoma cells to metastasize to bone suggests the hypothesis that bone and/or bone marrow-derived factors may promote prostate carcinoma cell growth or survival, or serve as chemoattractants for these cells.

METHODS

We screened three prostate carcinoma cell lines, DU-145, PC-3, and LNCaP, for the expression of several hematopoiesis-associated colony-stimulating factors (CSFs) and their receptors using RT-PCR (reverse transcriptase-polymerase chain reaction) and immunohistochemical methods, and examined their functional effects.

RESULTS

All of these cell lines express granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF), and the DU-145 and PC-3 lines express stem-cell factor (SCF), as determined by RT-PCR and ELISA. Each of these cell lines expresses the receptors for SCF, GM-CSF, M-CSF, and granulocyte colony-stimulating factor (G-CSF). M-CSF enhanced the soft-agar clonogenicity of PC-3 and DU-145 cells, and GM-CSF stimulated all three cell lines. SCF stimulated the clonogenic growth of DU-145 cells. G-CSF marginally abrogated the induction of cell death in the PC-3 and LNCaP cell lines under serum-free conditions. GM-CSF and M-CSF stimulated modest chemotaxis of PC-3, DU-145, and LNCaP cells (most prominently in PC-3 cells).

CONCLUSIONS

These data suggest that 1) CSFs may be part of a network of paracrine and autocrine loops that modulate prostate carcinoma cell activity, and 2) the growth-stimulatory, survival-enhancing, and/or chemotactic actions of bone marrow-derived CSFs on prostate carcinoma cells may explain in part why bone is a preferential site of prostatic carcinoma metastases.