Phase II trial of cyclophosphamide, vincristine, and dexamethasone in the treatment of androgen-independent prostate carcinoma

Programmed cell death, redox imbalance, and cancer therapeutics

Cancer cells are disordered by nature and thus featured by higher internal redox level than healthy cells. Redox imbalance could trigger programmed cell death if exceeded a certain threshold, rendering therapeutic strategies relying on redox control a possible cancer management solution. Yet, various programmed cell death events have been consecutively discovered, complicating our understandings on their associations with redox imbalance and clinical implications especially therapeutic design. Thus, it is imperative to understand differences and similarities among programmed cell death events regarding their associations with redox imbalance for improved control over these events in malignant cells as well as appropriate design on therapeutic approaches relying on redox control. This review addresses these issues and concludes by bringing affront cold atmospheric plasma as an emerging redox controller with translational potential in clinics.

Exceptional response to cyclophosphamide and dexamethasone in a patient with metastatic castrate-resistant prostate cancer and RB1 mutation

Rates of prostate cancer relapsing from anti-androgen therapies are increasing in the United States and worldwide. It has been suggested that this is caused by variant and altered lineage marker expression within the tumor, allowing for lineage plasticity that then facilitates therapeutic resistance. The genomic landscape of castrate-resistant prostate cancer has been well-defined with the advent of next-generation sequencing, but the clinical applications of these findings as measured by patient outcomes remains poorly understood. Here, we report on a patient with recurrent, metastatic castrate-resistant prostate cancer and identified RB1 mutation with progressive symptomatology, who was treated with cyclophosphamide and dexamethasone after other standard treatment regimens failed. After completing 2 years of treatment, he experienced complete resolution of his symptoms. Disease remission was confirmed on multiple imaging modalities and through serial measurements of prostate-specific antigen levels that showed a reduction of 99%. Our patient's case supports ongoing research that genetic profiling can help elucidate key biological and molecular tumor components, which can then inform targeted, individualized treatment approaches in the management of recurrent, castrate-resistant prostate cancer.

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.

A Randomised Phase II Trial Comparing Docetaxel Plus Prednisone with Docetaxel Plus Prednisone Plus Low-Dose Cyclophosphamide in Castration-Resistant Prostate Cancer

BACKGROUND

Docetaxel plus prednisone is a standard treatment for castration-resistant prostate cancer. Cyclophosphamide may be an effective combination partner.

METHODS

This randomised, multicentre, phase II trial compared the combination therapy of docetaxel plus prednisone plus cyclophosphamide with the standard therapy of docetaxel plus prednisone.

RESULTS

Thirty-three patients received six 3-week treatment cycles (in total 171 cycles). During treatment, an adequate decline in prostate-specific antigen was seen in both groups (p = 0.068) without between-group differences (p = 0.683). No relevant differences between within-group changes were observed for blood pressure, weight, pain score, laboratory variables or quality of life. There were no serious side effects apart from leucopenia requiring treatment (docetaxel + prednisone + cyclophosphamide arm) and no drug-related withdrawals; all three fatalities were considered to be cancer related.

CONCLUSIONS

The oncological effectiveness and tolerability of docetaxel plus prednisone were supported; an additional effect of cyclophosphamide was not detected. However, the small number of patients and short observation period restrict the generalisability of the results.

Antimitotic agents for the treatment of patients with metastatic castrate-resistant prostate cancer

INTRODUCTION

Metastatic castrate-resistant prostate cancer (mCRPC) is the second deadliest cancer in men. The group of taxanes, which target microtubules of mitotic cells, is currently the only chemotherapy which has proven to increase overall survival in mCRPC patients. Other mitotic inhibitors are being explored for their clinical potential in mCRPC treatment.

AREAS COVERED

In this review, we summarize recent developments in the application of mitotic inhibitors for mCRPC from a clinical perspective. The four main groups of mitotic inhibitors currently being tested in clinical trials are microtubule-inhibitors, polo-like kinase 1 inhibitors, aurora kinase inhibitors and kinesin-spindle protein inhibitors. Compounds of these groups of inhibitors that are in clinical development for mCRPC are discussed. For this extensive overview, relevant literature was searched in PubMed and retrieved from clinicaltrials.gov and presentations at ASCO/AACR meetings.

EXPERT OPINION

In general, mitotic inhibitors are clinically well tolerated but exert limited antitumor activity compared to preclinical study results. However, efficacy of mitotic inhibitors is improving, either by personalizing treatment, by introducing more active compounds, by decreasing resistance of cancer cells against mitotic inhibitors or by using mitotic inhibitors in combination therapies.

Diagnosis and management of metastatic cervical spine tumors

The bony spine is overall the third most common site for distant cancer metastasis, with the cervical spine involved in approximately 8 to 20% of metastatic spine disease cases. Diagnosis and management of metastatic spine disease requires disease categorization into the compartment involved, pathology of the lesion, and anatomic region involved. The diagnostic approach should commence with careful physical examination, and the workup should include plain radiographs, magnetic resonance imaging, computed tomography, and bone scintigraphy. Management ranges from palliative nonoperative to aggressive surgical treatment. Optimal management requires proper patient selection to individualize the most appropriate treatment modality.

Prolonged remission of fulminant castrate-resistant prostate cancer: a case report

Castrate-resistant prostate cancer (CRPC) is the main cause of prostate cancer (PC) morbidity and mortality. Newer therapies have only modestly improved survival. CRPC patients’ various comorbidities mean one must treat them cautiously. Cyclophosphamide, vincristine, and dexamethasone (CVD) therapy has a favorable risk-benefit profile, and diethylstilbestrol (DES) was used widely in PC. The patient we describe responded remarkably to combination treatment with CVD plus DES. The 77-year-old man had fulminant CRPC with multiple comorbidities and bony metastases in March 2008. In May 2008, his prognosis was dismal: performance status score, 4; pancytopenia; 51 × 109/l platelets; abnormal coagulation profile consistent with disseminated intravascular coagulopathy; and cranial images consistent with dural metastases. We administered one dose of CVD (cyclophosphamide [300 mg/m2 IV], vincristine [1 mg IV], and dexamethasone [0.75 mg PO b.i.d.]) plus DES (1 mg PO b.i.d.). He responded quickly with no clinically significant toxicity. His performance status improved and platelet count increased to 89,000 × 109/l. We administered maintenance CVD (cyclophosphamide, 150 mg/day PO for 21 days every 28 days; vincristine, 1 mg IV weekly; dexamethasone, 0.5 mg PO b.i.d.) plus DES (1 mg PO b.i.d.) for 5 months. In January 2011, nearly 3 years after his initial treatment, he remained alive and well. CVD plus DES may help selected patients with advanced CRPC who are too ill to tolerate or benefit from other therapies.

The epothilones: new therapeutic agents for castration-resistant prostate cancer

The management of castration-resistant prostate cancer (CRPC) presents a clinical challenge because of limitations in efficacy and durability with currently available therapeutics. The epothilones represent a novel class of anticancer therapy that stabilizes microtubules, causing cell death and tumor regression in preclinical models. The structure of the tubulin-binding site for epothilones is distinct from that of the taxanes. Moreover, preclinical studies suggest nonoverlapping mechanisms of resistance between epothilones and taxanes. In early-phase studies in patients with CRPC, treatment with ixabepilone, a semisynthetic analog of epothilone B, induced objective responses and prostate-specific antigen declines in men previously progressing on docetaxel-based regimens. Clinical activity has been observed in nonrandomized trials for patients with CRPC using ixabepilone in the first- and second-line settings as a single agent and in combination with estramustine. Patupilone and sagopilone were also shown to have promising efficacy in phase II clinical trials of patients with CRPC. All three epothilones appear to be well tolerated, with modest rates of neutropenia and peripheral neuropathy. The lack of crossresistance between epothilones and taxanes may allow sequencing of these agents. Evaluating epothilones in phase III comparative trials would provide much-needed insight into their potential place in the management of patients with CRPC.

Assessing outcomes in prostate cancer clinical trials: a twenty-first century tower of Babel

BACKGROUND

Because of the osseous distribution of prostate cancer metastases, progression is more readily identified than response in prostate cancer clinical trials. As a result, there is an increased focus on progression-free survival (PFS) as a phase 2 endpoint. PFS, however, is vulnerable to inter-study design variability. The authors sought to identify and quantify this variability and the resultant error in PFS across prostate cancer clinical trials.

METHODS

The authors reviewed phase 2 clinical trials of cytotoxic agents in castration-resistant metastatic prostate cancer over 5 years to evaluate the policies determining extent of disease and the definitions of disease progression. A simulation model was created to define the degree of error in estimating PFS in 3 hypothetical cohorts (median PFS of 12, 24, and 36 weeks) when the frequency of outcome assessments varies.

RESULTS

Imaging policies for trial entry were heterogeneous, as were the type, timing, and indications for outcome assessments. In the simulation, error in the reported PFS varied according to the interval between assessments. The difference between the detected and the true PFS could vary as much as 6.4 weeks per cycle, strictly resulting from the variability of assessment schedules tested.

CONCLUSIONS

Outcome assessment policies are highly variable in phase 2 studies of castration-resistant prostate cancer patients, despite published guidelines designed to standardize authentication of disease progression. The estimated error in PFS can exceed 6 weeks per cycle, exclusively because of variations in the assessment schedules. Comparisons of PFS times from different studies must be made with circumspection.

Chemotherapy for the treatment of hormone-refractory prostate cancer

AIMS

This review aims at analysing the published literature on chemotherapy for hormone-refractory prostate cancer (HRPC) to provide recommendations for the treatment of this important patient group.

METHODS

The information for this review was compiled using the PubMed and Medline databases and the Proceedings of the American Society of Clinical Oncology annual meetings to search for articles, abstracts and presentations up to 1 March 2007. Electronic early-release publications were also included. Only articles published in English were considered. The search terms included hormone-refractory prostate cancer, docetaxel, mitoxantrone, satraplatin, ixabepilone, cyclophosphamide, vinorelbine, atrasentan, calcitriol, bevacizumab and targeted therapies. Priority was given to studies in high impact factor journals when available.

RESULTS AND CONCLUSION

Two recent trials (TAX 327 and SWOG 9916) have shown that docetaxel chemotherapy can significantly improve survival for HRPC. Docetaxel has become the standard of care for first-line chemotherapy for HRPC and has been approved for use in the United States and Europe. Many patients with HRPC will require second- and even third-line treatment upon progression and more data are required in this setting. It is likely that the future management of patients with HRPC will build on the success of docetaxel using a sequence of chemotherapy and targeted therapies to reduce the risk of death, prevent or improve disease-related symptoms and improve quality of life for this important condition.

Taxane refractory prostate cancer

PURPOSE

Although docetaxel based therapy has become established as a front line therapy choice based on large, randomized studies, published studies of second line therapy for taxane refractory disease are limited.

MATERIAL AND METHODS

The literature on the biology of taxane resistance and studies applied to prostate cancer were reviewed using a PubMed(R) search and proceedings from recent symposia.

RESULTS

Although taxane resistance invariably emerges in the treatment of prostate cancer, a consensus working definition or classification does not exist. Although there is a body of knowledge on the mechanisms of action of taxanes and resistance pathways, there are few clinical or translational studies in prostate cancer adequately assessing the modulation of these mechanisms. Results of additional clinical trials are needed to define and improve the standard of care in the second line setting for castration resistant prostate cancer after docetaxel failure.

CONCLUSIONS

The validation of the microtubule as a target in prostate cancer implies that a finer understanding of specific mechanisms of efficacy and resistance may yield novel strategies. Taxane analogues that have greater antitumor activity and/or are less susceptible to drug resistance mechanisms than their prototypes are in development, as are nontaxane microtubule targeting agents and other agents directed against the mitotic spindle. Combinations of such agents may yield added efficacy but potentially added neurotoxicity. In contrast, combinations with drugs that inhibit cellular mechanisms of taxane resistance and vascular endothelial or tumor-stromal prosurvival interactions may have lower neurotoxic profiles. Although alternate classes of cytotoxic agents, eg satraplatin, are being studied, there is a strong imperative for translational studies in this setting.

Weekly high-dose calcitriol and docetaxel in patients with metastatic hormone-refractory prostate cancer previously exposed to docetaxel

OBJECTIVE

To evaluate the activity and tolerability of weekly high-dose calcitriol and docetaxel in patients with metastatic hormone-refractory prostate cancer (HRPC) previously exposed to docetaxel, as patients who progress after docetaxel treatment might be considered for second-line chemotherapy, but with no standard salvage therapy available we hypothesised that high-dose calcitriol might restore sensitivity to chemotherapy.

PATIENTS AND METHODS

The study comprised 26 patients who had progressed after first-line treatment with docetaxel-based chemotherapy had failed. Treatment cycles consisted of calcitriol (32 microg orally as 0.5 microg tablets) on day 1 and docetaxel (30 mg/m(2) intravenous) on day 2, administered for six consecutive weeks followed by a 2-week rest interval for a maximum of 24 cycles.

RESULTS

There was a response in prostate-specific antigen (PSA) level in eight patients (31%); seven (27%) had a stable PSA level for >/= 12 weeks. The median time to PSA progression was 4.2 months and the median survival was 9.3 months. The regimen was generally well tolerated; there was grade 2 hypercalcaemia, probably related to calcitriol, in one patient after six treatment cycles.

CONCLUSION

Weekly high-dose calcitriol and docetaxel seems to be an effective and well-tolerated treatment option for patients with metastatic HRPC previously exposed to docetaxel-based chemotherapy.

Hormone-Refractory Prostate Cancer

This article addresses the current status of therapeutic options in the management of hormone-refractory prostate cancer (HRPC). Following the publication of two landmark randomised trials, docetaxel chemotherapy is now the standard of care for men with metastatic HRPC. However, the benefit of this treatment is limited. Trials are now focusing on improving the efficacy of docetaxel by combining it with novel biological agents. Several new docetaxel-based combinations are under evaluation and promising results have been found for the combination of docetaxel with angiogenesis inhibitors. Early phase III trial data for atrasentan appear interesting. New cytotoxic agents such as satraplatin and ixabepilone are being investigated in several ongoing studies in order to define their role as second-line treatments of HRPC. Vaccine therapy offers an active immunological approach for combating malignancy in a targeted manner.

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.

Phase II study of capecitabine combined with gemcitabine in the treatment of androgen-independent prostate cancer previously treated with taxanes

BACKGROUND

The primary objective of the current study was to evaluate the effectiveness of capecitabine and gemcitabine in the treatment of patients with androgen-independent prostate cancer (AIPCa) who experienced disease progression after taxane therapy. The secondary objective was to evaluate the safety and tolerability of the combination of capecitabine and gemcitabine in these patients.

METHODS

Patients with AIPCa, either metastatic or unresectable disease, and prior taxane therapy were eligible. Patients were treated with 800 mg/m2 of capecitabine orally twice daily (1600 mg/m2 per day) for 14 days, and 800 mg/m2 of gemcitabine intravenously on Days 1 and 8. This regimen was repeated every 21 days. Response to therapy was determined by measuring prostate-specific antigen concentration.

RESULTS

Sixteen patients participated in this study from June 2003 to January 2004. There were no responses as defined by a 50% decline in prostate-specific antigen. The study was terminated early because the response rate was not projected to exceed 30% (rejection error of 10%). Toxicities were notable: 3 patients had Grade 3 thrombocytopenia, 4 patients had Grade 3 neutropenia, and 3 patients had Grade 3 infections (according to the National Cancer Institute Common Toxicity Criteria [version 2.0]). Eight patients (50%) required dose reduction or treatment interruption.

CONCLUSIONS

The combination of capecitabine and gemcitabine for the salvage treatment of patients with AIPCa was associated with significant toxicities and was ineffective for induction of disease regression.

Management of Advanced Prostate Cancer After First-Line Chemotherapy

Hormone refractory prostate cancer (HRPC) causes substantial morbidity and mortality. There are increasing options for both first- and second-line therapy in the palliative treatment of patients with HRPC. Medications to control symptoms should first be optimized in patients with late-stage disease, and radiotherapy applied to dominant painful bone lesions. Docetaxel, mitoxantrone, satraplatin, and ixabepilone are active chemotherapeutic agents in the first- and/or second-line setting for patients with HRPC, and this may be true also of older drugs such as oral cyclophosphamide and vinorelbine. Radioisotopes such as strontium and samarium are useful for treatment of more generalized bone pain. Third-line hormonal maneuvers including glucocorticoids, ketoconazole, and estrogens can lead to further palliation in some patients, and there are provocative data that chemotherapy might restore hormonal sensitivity in a subset of patients.

Therapy Tolerance in Selected Patients With Androgen-Independent Prostate Cancer Following Strontium-89 Combined With Chemotherapy

Purpose

Clinicians may have reservations about using strontium-89 for the treatment of bone metastases because of concerns that it may limit future use of chemotherapy. We assessed the rate of bone marrow failure in patients with prostate cancer who had received a dose of strontium-89.

Patients and Methods

This subgroup analysis involved 34 patients with androgen-independent prostate cancer who had been given a dose of strontium-89 and six weekly doses of doxorubicin after response to induction chemotherapy. We assessed subsequent hematotoxicity in terms of bone marrow failure and the ability to tolerate additional treatments during a median of 25 months (range, 7 to 76 months) after the strontium-89 was administered.

Results

No patients developed bone marrow failure within 6 months of receiving strontium-89. Five (15%) of 34 patients developed bone marrow failure at a median 23 months (range, 6 to 53 months) after the strontium-89 treatment. Bone marrow biopsy performed in two of these five patients showed complete replacement of the marrow by tumor. Thirty-one patients (91%) received subsequent cytotoxic treatments at a median 11 months (range, 1 to 33 months) after the strontium-89 treatment.

Conclusion

This analysis demonstrated that a single dose of strontium-89 combined with chemotherapy did not affect the delivery of subsequent courses of chemotherapy in a select group of patients. However, a majority of these therapies were given off protocol and were administered at a dose schedule that might be considered inappropriate or inadequate. The clinical role and safety profile of radiopharmaceuticals combined with chemotherapy in prostate cancer therapy deserve further exploration.