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ABSTRACT: Most prostate cancer-related deaths occur in patients with castration-resistant prostate cancer (CRPC). Recent preclinical and clinical studies have identified intracellular signaling pathways and changes in the tumor and bone microenvironment as potential key drivers of CRPC. This increased understanding of mechanisms associated with CRPC has driven the development of numerous new agents, many of which are poised to alter the current CRPC treatment landscape.
A review of literature was conducted to identify ongoing and planned phase III studies of novel agents to treat CRPC.
Multiple studies were identified, including novel androgen biosynthesis inhibitors (abiraterone, TAK-700), androgen-receptor inhibitors (MDV3100), angiogenesis inhibitors (aflibercept, tasquinimod), endothelin antagonists (zibotentan, atrasentan), a Src tyrosine kinase inhibitor (dasatinib), a novel radiotherapy (radium-223), and new immunotherapies (ipilimumab and ProstVac). In addition, both sipuleucel-T (an immunotherapy) and cabazitaxel (third-generation taxane) and the RANK-L inhibitor, denosumab, have recently been approved by the US Food and Drug Administration.
Various combinations of these agents could theoretically be used to treat future patients with CRPC by targeting multiple signaling pathways as well as aspects of the tumor and bone microenvironments. Additional research will be needed to understand how to best use these agents and individualize care to optimize CRPC patient outcomes.
The Prostate 07/2011; 72(3):338-49. · 3.48 Impact Factor
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ABSTRACT: During cancer progression, malignant cells undergo epithelial-mesenchymal transitions (EMT) and mesenchymal-epithelial transitions (MET) as part of a broad invasion and metastasis program. We previously observed MET events among lung metastases in a preclinical model of prostate adenocarcinoma that suggested a relationship between epithelial plasticity and metastatic spread. We thus sought to translate these findings into clinical evidence by examining the existence of EMT in circulating tumor cells (CTC) from patients with progressive metastatic solid tumors, with a focus on men with castration-resistant prostate cancer (CRPC) and women with metastatic breast cancer. We showed that the majority (> 80%) of these CTCs in patients with metastatic CRPC coexpress epithelial proteins such as epithelial cell adhesion molecule (EpCAM), cytokeratins (CK), and E-cadherin, with mesenchymal proteins including vimentin, N-cadherin and O-cadherin, and the stem cell marker CD133. Equally, we found that more than 75% of CTCs from women with metastatic breast cancer coexpress CK, vimentin, and N-cadherin. The existence and high frequency of these CTCs coexpressing epithelial, mesenchymal, and stem cell markers in patients with progressive metastases has important implications for the application and interpretation of approved methods to detect CTCs.
Molecular Cancer Research 06/2011; 9(8):997-1007. · 4.29 Impact Factor
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Daniel George
BJU International 10/2010; 106(7):945-6. · 2.84 Impact Factor
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James Mohler,
Robert R Bahnson,
Barry Boston,
J Erik Busby,
Anthony D'Amico,
James A Eastham,
Charles A Enke, Daniel George,
Eric Mark Horwitz,
Robert P Huben, [......],
Elizabeth R Plimack,
Julio M Pow-Sang,
Mack Roach,
Eric Rohren,
Bruce J Roth,
Dennis C Shrieve,
Matthew R Smith,
Sandy Srinivas,
Przemyslaw Twardowski,
Patrick C Walsh
Journal of the National Comprehensive Cancer Network: JNCCN 02/2010; 8(2):162-200. · 4.41 Impact Factor
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Michael J Morris,
Ethan M Basch,
George Wilding,
Maha Hussain,
Michael A Carducci,
Celestia Higano,
Philip Kantoff,
William K Oh,
Eric J Small, Daniel George,
Paul Mathew,
Tomasz M Beer,
Susan F Slovin,
Charles Ryan,
Christopher Logothetis,
Howard I Scher
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ABSTRACT: In 2005, the US Department of Defense, through the US Army Medical Research and Materiel Command, Office of the Congressionally Directed Medical Research Programs, created a funding mechanism to form a clinical trials consortium to conduct phase I and II studies in prostate cancer. This is the first report of the Prostate Cancer Clinical Trials Consortium (PCCTC).
The Department of Defense award supports a consortium of 10 prostate cancer research centers. Memorial Sloan-Kettering Cancer Center was awarded the Coordinating Center grant for the consortium and charged with creating an infrastructure to conduct early-phase multicenter clinical trials. Each participating center was required to introduce >or=1 clinical trial per year and maintain accrual of a minimum of 35 patients per year.
The PCCTC was launched in 2006 and now encompasses 10 leading prostate cancer research centers. Fifty-one trials have been opened, and 1386 patients have been accrued at member sites. Members share an online clinical trial management system for protocol tracking, electronic data capture, and data storage. A legal framework has been instituted, and standard operating procedures, an administrative structure, editorial support, centralized budgeting, and mechanisms for scientific review are established.
The PCCTC fulfills a congressional directive to create a clinical trials instrument dedicated to early-phase prostate cancer studies. The member institutions have built an administrative, informatics, legal, financial, statistical, and scientific infrastructure to support this endeavor. Clinical trials are open and accruing in excess of federally mandated goals.
Clinical Genitourinary Cancer 01/2009; 7(1):51-7. · 2.61 Impact Factor
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ABSTRACT: With the approval of sunitinib and sorafenib, 2 new multitargeted tyrosine kinase inhibitors, for the treatment of advanced renal cell carcinoma (RCC), the natural history and prognosis of patients with this disease has significantly improved. These drugs were approved based upon clinical data demonstrating robust, unprecedented response rates in one case and dramatic prolongation of progression-free survival in the other. In both cases, these results were seen in study patients in whom standard therapy had failed and who, on average, carried substantial disease burden. Important challenges today include integrating these therapies with other standard therapeutic options and into other advanced-stage RCC patient populations. This article addresses current data and practice patterns regarding the clinical use of tyrosine kinase inhibitors in patients with advanced-stage RCC, including dose modifications and alternative dosing, the current role of debulking nephrectomy, and use in patients with indolent disease. Finally, a summary of the more common side effects and management strategies for these is also discussed. Ultimately, more clinical data is needed to address the chronic use of these agents alone, in combination with other agents, with radiation therapy, and in sequence.
Clinical Genitourinary Cancer 01/2007; 5 Suppl 1:S24-30. · 2.61 Impact Factor
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ABSTRACT: Neoadjuvant administration of antineoplastic therapies is used to rapidly assess the clinical and biological activity of novel systemic treatments. To assess the feasibility of using microarrays to assess molecular end points following targeted treatment in a heterogeneous tumor, we measured global gene expression in localized prostate cancer before and following neoadjuvant treatment with imatinib mesylate.
Patients with intermediate-risk to high-risk prostate cancer were treated for 6 weeks with 200 to 300 mg of oral imatinib mesylate. Frozen tissue was obtained from pretreatment ultrasound-guided biopsies and posttreatment radical prostatectomy specimens. Oligonucleotide microarray analysis following laser capture microdissection (LCM) and RNA amplification was used to assess gene expression changes associated with imatinib mesylate therapy. Immunohistochemistry was used to measure protein expression of MKP1 and CD31 and to assess cellular apoptosis.
Of the 11 patients enrolled, high-quality microarray data was obtained from both biopsies (n = 7) and radical prostatectomy specimens (n = 9). Technically introduced intrasample gene expression variability was found to be significantly less than intertumor biological variability. Large gene expression differences were observed, and the gene with the most consistent differential expression (MKP1) was validated by immunohistochemistry. Gene set enrichment analysis suggests that imatinib mesylate therapy results in apoptosis of microvascular endothelial cells, an observation anecdotally supported by immunohistochemistry.
This study shows that high-quality microarray data can be generated using LCM and RNA amplification to discover potential mechanisms of targeted therapy in cancer.
Clinical Cancer Research 02/2006; 12(1):152-8. · 7.74 Impact Factor
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ABSTRACT: The objective of this study was to assess the biologic activity of rosiglitazone, a peroxisome proliferator-activated receptor gamma agonist that has been approved to treat type 2 diabetes, in men with recurrent prostate carcinoma using change in prostate specific antigen (PSA) doubling time (PSADT) as the primary outcome variable.
Men with histologically confirmed prostate carcinoma, no recent hormone therapy, a rising serum PSA level after radical prostatectomy and/or radiation therapy, and no radiographic evidence of metastases were assigned randomly to receive either oral rosiglitazone (4 mg twice daily) or placebo. The treatment was continued until the men developed disease progression or adverse effects. A positive outcome was defined as a posttreatment PSADT > 150% the baseline PSADT and no new metastases.
One hundred six men were enrolled. The median treatment duration was 315 days for men in the placebo group and 338 days for men in the rosiglitazone group (P = 0.28). Forty percent of men in the in the placebo group and 38% of men in the rosiglitazone group had a posttreatment PSADT > 150% of the baseline PSADT and no new metastases (P = 1.00). In exploratory analyses, the rate of a positive outcome remained higher than expected in the placebo group, even when a positive outcome was redefined using more stringent criteria. The time to disease progression was similar between the groups.
Rosiglitazone did not increase PSADT or prolong the time to disease progression more than placebo in men with a rising PSA level after radical prostatectomy and/or radiation therapy. The unexpected discordance between baseline and posttreatment PSADT in the placebo group reinforced the importance of randomized controlled trials in this setting.
Cancer 10/2004; 101(7):1569-74. · 4.77 Impact Factor
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ABSTRACT: First and second-generation aromatase inhibitors have shown activity in patients with androgen-independent prostate carcinoma. These early-generation aromatase inhibitors are nonselective, however, and inhibition of other steroidogenic enzymes may contribute to their reported clinical activity. The authors conducted a Phase II clinical study of letrozole to determine the safety and efficacy of a potent and selective third-generation aromatase inhibitor in men with androgen-independent prostate carcinoma.
Forty-three men with androgen-independent prostate carcinoma were treated with oral letrozole (2.5 mg daily). Treatment was continued until progressive disease or Grade 3 toxicity developed. Response and progressive disease were defined according to recommendations of the Prostate Specific Antigen Working Group.
In total, 380 weeks of treatment were administered to the 43 study patients. The median duration of treatment was 8 weeks. Forty men discontinued treatment due to progressive disease. Only one patient responded to treatment with a sustained decrease > 50% in serum prostate specific antigen (PSA) levels. Three other patients experienced transient minor decreases (< 50%) in serum PSA levels. There were no serious treatment-related adverse events.
Selective aromatase inhibition with letrozole is not active in men with androgen-independent prostate carcinoma.
Cancer 11/2002; 95(9):1864-8. · 4.77 Impact Factor
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Ph.D. Matthew R. Smith M.D,
Donald Kaufman M.D,
Daniel George M.D,
William K. Oh M.D,
Maryanne Kazanis,
Judith Manola M.S,
Philip W. Kantoff M.D,
Matthew R. Smith,
Donald Kaufman, Daniel George,
William K. Oh,
Judith Manola,
Philip W. Kantoff
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ABSTRACT: BACKGROUND
First and second-generation aromatase inhibitors have shown activity in patients with androgen-independent prostate carcinoma. These early-generation aromatase inhibitors are nonselective, however, and inhibition of other steroidogenic enzymes may contribute to their reported clinical activity. The authors conducted a Phase II clinical study of letrozole to determine the safety and efficacy of a potent and selective third-generation aromatase inhibitor in men with androgen-independent prostate carcinoma.METHODS
Forty-three men with androgen-independent prostate carcinoma were treated with oral letrozole (2.5 mg daily). Treatment was continued until progressive disease or Grade 3 toxicity developed. Response and progressive disease were defined according to recommendations of the Prostate Specific Antigen Working Group.RESULTSIn total, 380 weeks of treatment were administered to the 43 study patients. The median duration of treatment was 8 weeks. Forty men discontinued treatment due to progressive disease. Only one patient responded to treatment with a sustained decrease > 50% in serum prostate specific antigen (PSA) levels. Three other patients experienced transient minor decreases (< 50%) in serum PSA levels. There were no serious treatment-related adverse events.CONCLUSIONS
Selective aromatase inhibition with letrozole is not active in men with androgen-independent prostate carcinoma. Cancer 2002;95:1864–8. © 2002 American Cancer Society.DOI 10.1002/cncr.10844
Cancer 10/2002; 95(9):1864 - 1868. · 4.77 Impact Factor
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ABSTRACT: Declines in serum hemoglobin (Hgb) levels occur from the use of androgen suppression therapy (AST) in the treatment of prostate cancer patients. We studied whether time to prostate specific antigen (PSA) failure following external beam radiation therapy (RT) and AST could be predicted by the rate of decline in the Hgb level following the administration of neoadjuvant AST or by the Hgb level at presentation or at the start of RT.
The study cohort comprised 110 intermediate or high-risk prostate cancer patients who were managed using three-dimensional conformal RT (70 Gy) and 6 months of AST (2 months neoadjuvant, concurrent, and adjuvant). A Cox regression multivariable analysis was performed to evaluate the ability of the rate of decline of the Hgb from baseline to the start of RT, baseline PSA level, Gleason score, percent positive biopsies, and T-category to predict time to PSA failure.
A decline in the Hgb level of 1 g/dL or more during the first month of AST was the only significant predictor of time to PSA failure (P = 0.02) on multivariable analysis. The relative risk of PSA failure (95% confidence interval) for patients with a decline in Hgb level during the first month (> or = 1 g/dL vs. < 1 g/dL) was 6.3 (2.4, 8.3) and the 3-year estimate of PSA outcome was 66% versus 82% (P = 0.04), respectively. There were no imbalances in the pretreatment prognostic factors or length of follow-up in each of these groups.
A decline of 1 g/dL or more in Hgb level during the first month of neoadjuvant AST was a predictor of early PSA failure following RT and AST in intermediate and high-risk prostate cancer patients.
Cancer 08/2002; 95(2):275-80. · 4.77 Impact Factor
