Combination chemotherapy with docetaxel, estramustine and suramin for hormone refractory prostate cancer

100 Years of Suramin

Suramin is 100 years old and is still being used to treat the first stage of acute human sleeping sickness, caused by Trypanosoma brucei rhodesiense Suramin is a multifunctional molecule with a wide array of potential applications, from parasitic and viral diseases to cancer, snakebite, and autism. Suramin is also an enigmatic molecule: What are its targets? How does it get into cells in the first place? Here, we provide an overview of the many different candidate targets of suramin and discuss its modes of action and routes of cellular uptake. We reason that, once the polypharmacology of suramin is understood at the molecular level, new, more specific, and less toxic molecules can be identified for the numerous potential applications of suramin.

Synergistic Effects of Nobiletin and Sorafenib Combination on Metastatic Prostate Cancer Cells

Objective: Herein we, for the first time, investigated a potential synergistic effect of nobiletin (NOB) and sorafenib (SOR) on PC-3 prostate cancer and HUVEC control cell lines. Methods: In order to determine the cytotoxic and apoptotic effects of the combination of NOB and SOR, WST-1, Annexin V, and cell cycle analysis were performed. The potential molecular mechanism of apoptotic cell death was assessed by Bax, Bcl-2, CCDN1, Rb1, and CDKN1A gene expression and acridine orange (AO) and DAPI staining. Results: Our results indicated that NOB and SOR combination had a significant inhibitory effect on the viability of PC-3 cells with less toxicity on HUVEC cells than SOR alone (P < 0.01). NOB and SOR combination significantly caused much more apoptotic cell death and cell cycle arrest at G0/G1 phase by up-regulation of Bax, Rb1, and CDKN1A levels in PC-3 cells (P < 0.01). Therefore, strong synergistic effects between NOB and SOR were analyzed (CI < 1). Conclusion: NOB and SOR combination was more effective than SOR and NOB alone and reduced the exposure time for SOR and NOB in PC-3 cells. Combination strategy is a therapeutic potential to improve efficacy and reduce side-effect of SOR for the treatment of metastatic prostate cancer cells.

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.

Suramin protects from cisplatin-induced acute kidney injury

Cisplatin, a commonly used cancer chemotherapeutic, has a dose-limiting side effect of nephrotoxicity. Approximately 30% of patients administered cisplatin suffer from kidney injury, and there are limited treatment options for the treatment of cisplatin-induced kidney injury. Suramin, which is Federal Drug Administration-approved for the treatment of trypanosomiasis, improves kidney function after various forms of kidney injury in rodent models. We hypothesized that suramin would attenuate cisplatin-induced kidney injury. Suramin treatment before cisplatin administration reduced cisplatin-induced decreases in kidney function and injury. Furthermore, suramin attenuated cisplatin-induced expression of inflammatory cytokines and chemokines, endoplasmic reticulum stress, and apoptosis in the kidney cortex. Treatment of mice with suramin 24 h after cisplatin also improved kidney function, suggesting that the mechanism of protection is not by inhibition of tubular cisplatin uptake or its metabolism to nephrotoxic species. If suramin is to be used in the context of cancer, then it cannot prevent cisplatin-induced cytotoxicity of cancer cells. Suramin did not alter the dose-response curve of cisplatin in lung adenocarcinoma cells in vitro. In addition, suramin pretreatment of mice harboring lung adenocarcinomas did not alter the initial cytotoxic effects of cisplatin (DNA damage and apoptosis) on tumor cells. These results provide evidence that suramin has potential as a renoprotective agent for the treatment/prevention of cisplatin-induced acute kidney injury and justify future long-term preclinical studies using cotreatment of suramin and cisplatin in mouse models of cancer.

Sorafenib in progressive castrate-resistant prostate cancer. Can we talk about a new therapeutic option?

Castrate-resistant prostate cancer represents a significant clinical challenge. Currently, the standard treatment for patients with castrate-resistant prostate cancer is chemotherapy, after which patients only receive symptomatic treatment. The available results of phase II clinical trials of sorafenib in patients with hormone-refractory prostate cancer indicate that, despite a relatively short progression-free survival, the treatment may be associated with good outcomes in terms of overall survival and maintenance of a good quality of life. The study presents the authors' critical opinions and observations about the usefulness of sorafenib in patients with prostate cancer.

Phase II trial of estramustine phosphate and oral etoposide in patients with hormone-refractory prostate cancer

BACKGROUND

There is a need for active agents with a better safety profile than docetaxel, yet good activity, for patients with hormone-refractory prostate cancer (HRPC). We carried out a phase II trial to determine the activity and safety of estramustine plus oral etoposide in HRPC.

PATIENTS AND METHODS

Patients were given estramustine (280 mg twice daily) and etoposide (100 mg/day, days 1-21) in 28-day cycles until disease progression or unacceptable toxicity. Primary end points were overall response rate and safety, as determined by prostate-specific antigen (PSA) levels and lesion assessment.

RESULTS

From November 2001 to February 2007, 75 patients were enrolled. All patients were assessable for safety; 17 (22.6%) had grade 3/4 toxicity. PSA response was assessable in 69, 14 of whom had a >50% reduction in PSA. Of 10 patients with one or more measurable lesions, two (20%) had partial response and two (20%) disease stabilization. Overall, median time to progression was 4.4 months (range 1 week-43 months); median survival was 23 months (range 3 weeks-64+ months).

CONCLUSIONS

Estramustine plus etoposide is active and has a manageable safety profile in patients with HRPC. In asymptomatic patients with nonaggressive disease this combination could be useful to delay the start of more demanding treatments.

Safety and efficacy of sorafenib in patients with castrate resistant prostate cancer: a Phase II study

PURPOSE

We determined the safety and efficacy of sorafenib in patients with castrate resistant prostate cancer (CRPC).

METHODS

Sixty-four chemotherapy and radiotherapy naïve patients with CRPC received 400 mg sorafenib orally twice daily in 6-week cycles. All patients had bone metastasis, while 16 had lymph node-, 9 had liver-, and 10 had lung metastases. Treatment was continued until disease progression or excessive toxicity.

RESULTS

All patients were assessable for response. A median of 6.4 consecutive cycles was administered per patient. Median overall survival for all patients was 14.6 months (confidence interval [CI], 8.2-22.2). No complete response (CR) occurred. Of the 35 patients with measurable extraosseous disease, 7 (20%) had a partial response. Overall, 13 patients (20.3%; 95% CI, 4%-32%) achieved a 50% or greater reduction (partial response [PR]) in prostate-specific antigen (PSA) level after two cycles. The median response duration was 2.5 months (95% CI, 1.4 to 4.8), and the median time to progression was 5.9 months (95% CI 3.6 to 7.6). There was no treatment-related death. Toxicities were well tolerated.

CONCLUSIONS

Sorafenib demonstrated some antitumor activity. Further studies are necessary to determine a subgroup of patients who would likely respond better to sorafenib.

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

PURPOSE

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSION

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

Docetaxel, low-dose estramustine, and doxifluridine in hormone-refractory metastatic prostate cancer

PURPOSE

Advanced prostate cancer, which is one of the most common cancers, usually progresses to hormone-refractory prostate cancer (HRPC). A recent randomized trial of treatment with docetaxel demonstrated improved survival for patients with HRPC. The combination of docetaxel and estramustine phosphate (estramustine) has been reported to be effective for HRPC. Low-dose estramustine suppresses the pituitary-gonadal axis. Docetaxel plus 5-fluoro-5'-deoxyuridine (5'-dFUrd) had supra-additive cytotoxic effects on HRPC cells consistent with the molecular mechanism. Therefore, we examined the efficacy of adding 5'-dFUrd on the chemotherapy regimen, which consist docetaxel and estramustine.

METHODS

All of the HRPC patients were treated with estramustine 140 mg orally twice 5'-dFUrd 200 mg orally four times daily on days 1-21, and docetaxel 60 mg/m(2) was administered on day 1. We evaluated serum prostate-specific antigen (PSA) and measurable responses, the progression-free and overall survival, and the impact on adverse effects and the quality of life (QOL).

RESULTS

Of 34 patients with a median age of 72.3 years, 73% showed PSA responses and 70% showed measurable responses. The median progression-free survival was 18.0 and 5.8 months for PSA responders and non-responders and the overall survival was 19.4 months, respectively. There were few serious adverse effects. Grade 3/4 neutropenia occurred in 32.4% of the patients, and was easily managed with granulocyte colony-stimulating factor (G-CSF) injection. There was no significant change in the overall QOL scores serially.

CONCLUSIONS

This study shows that the combined regimen is tolerable and effective in Japanese HRPC patients.

Recent advances on multiple tumorigenic cascades involved in prostatic cancer progression and targeting therapies

Recent advances on differently-expressed gene products and their functions during the progression from localized androgen-dependent states into androgen-independent and metastatic forms of prostate cancer are reported. The expression levels of numerous oncogenes and tumor suppressor genes in distinct prostatic cancer epithelial cell lines and tissues relative to normal prostate cells are described. This is carried out to identify the signaling elements that are altered during the initiation, progression and metastatic process of prostate cancer. Additional information on the interactions between certain deregulated signaling pathways such as androgen receptor (AR), estrogen receptors, epidermal growth factor receptor (EGFR), hedgehog and Wnt/beta-catenin cascades in controlling the proliferation, survival and invasion of tumor prostate epithelial cells during the disease progression is described. The emphasis is on the critical functions of the AR and EGF-EGFR systems at all stages during prostate carcinogenesis. Of therapeutic interest, new strategies for the diagnosis and treatment of localized and metastatic forms of prostate cancer by targeting multiple tumorigenic signaling elements are also reported.