Publications by authors named "Ryan P Roop"

3 Publications

  • Page 1 of 1

A randomized phase II trial investigating the effect of platelet function inhibition on circulating tumor cells in patients with metastatic breast cancer.

Clin Breast Cancer 2013 Dec;13(6):409-15

Department of Medicine, Division of Oncology, Washington University School of Medicine in St. Louis, St. Louis, MO.

Background: Blockade of platelet activation and aggregation can inhibit metastasis in preclinical models and is associated with cancer prevention. To test whether disruption of platelet function with clopidogrel and aspirin would decrease the number of circulating tumor cells (CTCs) in patients with metastatic breast cancer, a randomized phase II study was performed.

Methods: Patients with metastatic breast cancer who were not currently receiving cytotoxic chemotherapy were eligible. Patients were randomized to receive either clopidogrel and aspirin or to a control group receiving no treatment. Phlebotomy was performed at baseline, at 2 and 4 weeks, and monthly thereafter to obtain specimens to assess CTC, platelet aggregation, and thrombin activity. The primary end point was the proportion of patients with detectable CTCs at 1 month.

Results: Forty-eight patients were enrolled and 42 were evaluable at 1 month. Baseline CTC numbers were ≥ 5 in 13% and ≥ 1 in 65% of patients. Despite adequate platelet function inhibition in the treatment group, the proportion of patients with detectable CTCs was similar between the clopidogrel/aspirin and control groups at baseline (P = .21) and 4 weeks (P = .75), showing no treatment effect. Measured endogenous thrombin potential did not correlate with CTC number. No bleeding-related serious adverse events (SAEs) occurred.

Conclusion: The baseline CTC numbers were lower than expected, decreasing the ability to detect an impact of platelet inhibition on CTCs. Clopidogrel and aspirin were well tolerated. Future studies evaluating the potential therapeutic role of antiplatelet therapy in breast cancer remain of interest, and they may be informed by these results.
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December 2013

Endocrine resistance in breast cancer: molecular pathways and rational development of targeted therapies.

Future Oncol 2012 Mar;8(3):273-92

Washington University School of Medicine in Saint Louis, Department of Medicine, Divisions of Hematology & Oncology, St Louis, MO, USA.

Endocrine resistance presents a major challenge in the management of estrogen receptor (ER)-positive breast cancer and is an area under intense investigation. Although the underlying mechanism is still poorly understood, many studies point towards the 'cross-talk' between ER and growth factor receptor signaling pathways as the key in the development of estrogen-independent growth in breast cancer. This review aims to provide the reader our current understanding of various molecular pathways that mediate endocrine resistance and that are being evaluated as therapeutic targets for ER-positive breast cancer. While most of the agents that target these pathways have only been tested in Phase I or small Phase II trials, some have shown encouraging results. A critical issue that remains is the development of research strategies and clinical trials that take into account the molecular heterogeneity of ER-positive breast cancer.
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March 2012

PARP inhibitors and their evolving role in breast cancer.

Oncology (Williston Park) 2011 Oct;25(11):1033-4

Division of Hematology/Oncology, Washington University School of Medicine, St. Louis, Missouri, USA.

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October 2011