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Dive into the research topics where Robert S. Siegel is active.

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Featured researches published by Robert S. Siegel.


Journal of Clinical Oncology | 2010

Safety and efficacy of romiplostim in patients with lower-risk myelodysplastic syndrome and thrombocytopenia.

Hagop M. Kantarjian; Pierre Fenaux; Mikkael A. Sekeres; Pamela S. Becker; Adam M. Boruchov; David Bowen; Eva Hellström-Lindberg; Richard A. Larson; Roger M. Lyons; Petra Muus; Jamile Shammo; Robert S. Siegel; Kuolung Hu; Dietmar Berger

PURPOSE To assess the safety and efficacy of romiplostim, a peptibody that increases platelet production, for treatment of thrombocytopenic patients with myelodysplastic syndromes (MDS). PATIENTS AND METHODS Eligible patients had lower-risk MDS (International Prognostic Scoring System low or intermediate 1), a mean baseline platelet count <or= 50 x 10(9)/L, and were only receiving supportive care. Patients received three injections of 300, 700, 1,000, or 1,500 microg romiplostim at weekly intervals. After evaluation of platelet response at week 4, patients could continue to receive romiplostim in a treatment extension phase for up to 1 year. RESULTS All 44 patients who enrolled completed the treatment phase; 41 patients continued into the extension phase. Median platelet counts increased throughout the study, from fewer than 30 x 10(9)/L at baseline to 60, 73, 38, and 58 x 10(9)/L at week 4 for the 300-, 700-, 1,000-, and 1,500 -microg dose cohorts, respectively. A durable platelet response (per International Working Group 2000 criteria for 8 consecutive weeks independent of platelet transfusions) was achieved by 19 patients (46%). The incidence of bleeding events and platelet transfusions was less common among patients who achieved a durable platelet response than those who did not (4.3 v 39.3 per 100 patient-weeks). Forty-three patients (98%) reported one or more adverse events. Treatment-related serious adverse events were reported in five patients (11%), all of whom were in the 1,500-microg dose cohort. Two patients progressed to acute myeloid leukemia during the study. No neutralizing antibodies to either romiplostim or endogenous thrombopoietin were seen. CONCLUSION Romiplostim appeared well-tolerated in this study and may be a useful treatment for patients with MDS and thrombocytopenia.


British Journal of Haematology | 1992

Plasma factor VII and thrombin–antithrombin III levels indicate increased tissue factor activity in sickle cell patients

Joseph Kurantsin-Mills; Frederick A. Ofosu; Toufic K. Safa; Robert S. Siegel; Lawrence S. Lessin

Although the mechanisms involved in the persistent clinical complications of sickle cell disease have not yet been fully delineated, previous studies suggest that sickle cell (HbSS) patients have a disposition to generate more thrombin and plasmin in vivo than normal subjects. The reasons for the impaired regulation of haemostasis in HbSS patients is poorly understood. We report studies evaluating the extent to which in vivo coagulation and fibrinolysis are altered in HbSS patients in steady state. The concentrations of total factor VII (F(VII)t), factor VII zymogen (F(VII)z), thrombin–antithrombin III (TAT), fibrinopeptide A(FPA), and fibrin D‐dimer in plasmas of 50 normal controls (HbAA) and 45 HbSS steady state patients, were measured using sensitive and specific enzyme‐linked immunoassays. The average plasma concentration of F(VII)t, in sickle cell plasma was significantly lower than that of the control subjects (0·70 ± 0·19 U/ml versus 1·16 ± 0·41 U/ml), whereas F(VII)z in the patients and controls were 0·47 ± 0·15 U/ml and 1·15 ± 0·33 U/ml respectively, P<0·001. Both measures of factor VII suggest a higher factor VII turnover in sickle cell disease. The mean concentration of TAT in the plasma of HbSS patients were significantly higher than those of HbAA controls (371 ± 44 pM versus 42 ± 2 pM) (P<0·001), a difference that is strongly indicative of higher rates of in vivo thrombin generation by HbSS patients. Plasmas of HbSS patients had significantly higher concentrations of FPA compared to those of the control subjects (12·85 ± 1·96 ng/ml versus 4·22 ± 0·37 ng/ml) (P<0·001). The D‐dimer levels were also higher in the HbSS than control plasmas (1029·6 ± 58·6 ng/ml versus 224·3 ± 27·6 g/ml) (P<0·001), with the patients’values being indicative of enhanced fibrinolysis. These results strongly suggest accelerated in vivo coagulation and fibrinolysis in HbSS patients even during steady state. They are consistent with the hypothesis that haemostasis is less tightly regulated in the HbSS patients than in HbAA controls. The altered regulation of haemostasis may contribute to the initiation of vaso‐occlusive processes associated with sickle cell painful episodes.


British Journal of Haematology | 2013

Phase I/II trial assessing bendamustine plus bortezomib combination therapy for the treatment of patients with relapsed or refractory multiple myeloma

James R. Berenson; Ori Yellin; Alberto Bessudo; Ralph V. Boccia; Stephen J. Noga; Donald S. Gravenor; Dipti Patel-Donnelly; Robert S. Siegel; Tarun Kewalramani; Edward J. Gorak; Youram Nassir; Regina A. Swift; Debra Mayo

Bendamustine, active in multiple myeloma (MM), is a bifunctional mechlorethamine derivative with alkylating properties. Bortezomib, approved to treat MM, is effective in combination with alkylators. The tolerability and efficacy of bendamustine plus bortezomib in relapsed/refractory MM was assessed in an open‐label, dose‐escalating, phase I/II study. Patients aged ≥18 years received intravenous bendamustine 50, 70, or 90 mg/m2 (days 1 and 4) plus bortezomib 1·0 mg/m2 (days 1, 4, 8, and 11) for up to eight 28‐day cycles. No dose‐limiting toxicity was observed after cycle 1; bendamustine 90 mg/m2 plus bortezomib 1·0 mg/m2 was designated the maximum tolerated dose (MTD). The most common grade 3/4 adverse events were leucopenia (58%), neutropenia (50%), lymphopenia (45%), and thrombocytopenia (30%). Primary efficacy measure was overall response rate (ORR), which was the combined complete response (CR), very good partial response (VGPR), partial response (PR), and minimal response (MR). ORR was 48% (one CR, two VGPR, nine PR, and seven MR) for all 40 enrolled patients, 52% (16/31) at the MTD (90 mg/m2), and 42% and 46% for prior use of bortezomib (n = 31) or alkylators (n = 28) respectively. Bendamustine plus bortezomib was well tolerated with promising efficacy in this heavily pretreated population.


Oncotarget | 2016

miR-671-5p inhibits epithelial-to-mesenchymal transition by downregulating FOXM1 expression in breast cancer

Xiaohui Tan; Yebo Fu; Liang Chen; Woojin Lee; Yinglei Lai; M. Katayoon Rezaei; Sana Tabbara; Patricia S. Latham; Christine B. Teal; Yan-gao Man; Robert S. Siegel; Rachel F. Brem; Sidney W. Fu

MicroRNA (miRNA) dysfunction is associated with a variety of human diseases, including cancer. Our previous study showed that miR-671-5p was deregulated throughout breast cancer progression. Here, we report for the first time that miR-671-5p is a tumor-suppressor miRNA in breast tumorigenesis. We found that expression of miR-671-5p was decreased significantly in invasive ductal carcinoma (IDC) compared to normal in microdissected formalin-fixed, paraffin-embedded (FFPE) tissues. Forkhead Box M1 (FOXM1), an oncogenic transcription factor, was predicted as one of the direct targets of miR-671-5p, which was subsequently confirmed by luciferase assays. Forced expression of miR-671-5p in breast cancer cell lines downregulated FOXM1 expression, and attenuated the proliferation and invasion in breast cancer cell lines. Notably, overexpression of miR-671-5p resulted in a shift from epithelial-to-mesenchymal transition (EMT) to mesenchymal-to-epithelial transition (MET) phenotypes in MDA-MB-231 breast cancer cells and induced S-phase arrest. Moreover, miR-671-5p sensitized breast cancer cells to cisplatin, 5-fluorouracil (5-FU) and epirubicin exposure. Host cell reactivation (HCR) assays showed that miR-671-5p reduces DNA repair capability in post-drug exposed breast cancer cells. cDNA microarray data revealed that differentially expressed genes when miR-671-5p was transfected are associated with cell proliferation, invasion, cell cycle, and EMT. These data indicate that miR-671-5p functions as a tumor suppressor miRNA in breast cancer by directly targeting FOXM1. Hence, miR-671-5p may serve as a novel therapeutic target for breast cancer management.


International Journal of Antimicrobial Agents | 1999

Empiric antimicrobial therapy of febrile neutropenic patients undergoing haematopoietic stem cell transplantation

Bassema A. Antabli; Peter Bross; Robert S. Siegel; Connie D. Small; Imad A. Tabbara

This study was conducted to assess the efficacy and toxicity of intravenous (i.v.) ceftazidime and ciprofloxacin in neutropenic febrile patients undergoing high dose myeloablative therapy and hematopoietic stem cell transplantation (HSCT). All patients undergoing HSCT for leukaemia, lymphoma, multiple myeloma and solid tumours received open-label ceftazidime 2 g i.v. every 8 h and ciprofloxacin 400 mg i.v. every 12 h if they developed fever while they were neutropenic. Success with or without modification of this regimen was defined as survival through the neutropenic period; failure was defined as death secondary to infection. Of 106 patients treated with this regimen, the success rate was 99%. Sixty-one of the patients (57.5%) defervesced within 48-72 h and remained afebrile without regimen modification. In 41.5% of the cases (44/106), the regimen was modified because of persistent fever. One patient died secondary to sepsis. The combination of ceftazidime and ciprofloxacin as initial empiric antibacterial therapy in febrile neutropenic patients undergoing myeloablative therapy and HSCT is highly effective and is associated with minimal toxicity.


International Journal of Radiation Applications and Instrumentation. Part B. Nuclear Medicine and Biology | 1989

Indium-111 oxine labeled erythrocytes: Cellular distribution and efflux kinetics of the label

Joseph Kurantsin-Mills; Helena M. Jacobs; Robert S. Siegel; M.M. Cassidy; Lawrence S. Lessin

Indium-111 oxine label erythrocytes are useful in scintigraphic studies of splenic function because of the high yield of gamma-photons [172(90%) and 247(94%) keV] of indium-111. However, the effects of indium-111 oxine on the structural and functional integrity of erythrocytes which might influence their reticulo-endothelial (RE) sequestration are unknown. We examined the morphology of human and rat indium-111 labeled erythrocytes by SEM, the distribution of the label within the cell by analysis of the membrane and cytosol (hemoglobin solution) and the kinetics of efflux of indium-111 from erythrocytes incubated at 37 degrees C in plasma or physiological buffer. Indium-111 oxine labeled red cells retain their discocytic morphology and the cell indices, and density characteristics on phthalate ester are similar to those of the control cells. The efficiency of labeling may be as high as 97%. Human or rat erythrocyte membranes retain 33 and 41% of indium-111, and the cytosol contains 67 and 59%, respectively. About 98% of the indium-111 is bound to the membrane proteins and 1% to the lipid bilayer. Efflux of indium-111 from cells in autologous plasma showed a multiphasic release resulting in about 4-5% release of the label in 2 h and 11.5% in 20 h. Cells in PBS showed 1-5% release of the label during the incubation period. These findings suggest that indium-111 oxine labeling of erythrocytes does not grossly alter the structural and deformability integrity of the cells to induce selective RE sequestration, unless the cells have been damaged prior to or during the labeling procedure, or the spleen is hyperactive.


Orthopedics | 1989

The use of indium-111 labeled platelet scanning for the detection of asymptomatic deep venous thrombosis in a high risk population

Robert S. Siegel; Janice L. Rae; Nancy L Ryan; Cherie M Edwards; William P Fortune; Randall J Lewis; Richard C. Reba

Five hundred indium-111 labeled platelet imaging studies (387 donor and 113 autologous) were performed postoperatively in 473 patients who had undergone total hip replacement, total knee replacement, or internal fixation of a hip fracture to detect occult deep venous thrombosis. All patients had been anticoagulated prophylactically with aspirin, warfarin sodium (Coumadin), or dextran. Thirty-four possible cases of proximal deep venous thrombosis were identified in 28 asymptomatic patients. To verify the scan results, 31 venograms were performed in 25 patients (three refused). In 21 of 31 cases, totally occlusive thrombi were detected; in 5 cases, partially occlusive thrombi were detected; in 5 cases, no thrombus was seen. No patient who had a negative scan nor any patient who had a verified positive scan (and received appropriate heparin therapy) subsequently developed symptoms or signs of pulmonary embolism. One hundred forty-one indium study patients also underwent Doppler ultrasonography/impedance plethysmography (Doppler/IPG) as a comparative non-invasive technique. In 137 cases, the results of the indium study and Doppler/IPG studies were congruent. The indium study had no false negative results that were detected by Doppler/IPG. No patient had any clinically evident toxicity. These results suggest that indium-111 labeled platelet scanning is a safe, noninvasive means for identifying DVT in high risk patients.


Clinical Genitourinary Cancer | 2015

Circulating Tumor Cells in Biochemical Recurrence of Prostate Cancer

Jeanny B. Aragon-Ching; Robert S. Siegel; Harold Frazier; Ramez Andrawis; Frederick Hendricks; Michael Phillips; Thomas W. Jarrett; Hiwot Guebre-Xabiher; Steven R. Patierno; Samuel J. Simmens

OBJECTIVE Circulating tumor cells (CTCs) have known prognostic implications in metastatic castration-resistant prostate cancer, but little is known regarding its utility in biochemical recurrence (BR) of prostate cancer. The primary objectives were to determine whether CTCs are measurable in patients with BR and whether it can reliably predict prostate-specific antigen (PSA) increase and PSA doubling times (PSADTs). METHODS BR was identified in patients after prostatectomy or radiation or both, with a PSA increase of ≥ 0.2 for prior prostatectomy or > 2 mg/dL increase for post-nadir in prior radiotherapy. CTCs were enumerated at baseline at the time of study entry using the CellSearch (Janssen Diagnostics, Raritan, NJ) test. RESULTS The median age for all 36 patients accrued was 69.5 years (range, 51-91) with a median PSA of 1.65 ng/mL (range, 0.2-65.8). Gleason scores ranged from 5 to 9 (median, 7). The majority had prostatectomy (n = 25), external beam radiotherapy (n = 9), CyberKnife (Accuray, Sunnyvale, CA) (n = 1), and combined radiohormonal therapy (n = 1). PSADT ranged from 0.35 to 55 months, with a median of 7.43 months. The incidence of positive CTCs was 8.3% (3 patients), of whom 2 had biopsy-proven bony lesions on presenting with equivocal scans and PSADTs of 2.27 and 3.08 months, respectively. The third CTC-positive patient had a PSADT of 4.99 months. CONCLUSIONS Obtaining CTCs in unselected patients presenting with BR has a relatively low yield. However, obtaining a positive CTC raises the suspicion of the presence of metastatic disease and may have utility for longitudinal follow-ups of patients with BR.


Arthritis Care and Research | 2017

A 66 year old woman with hemoptysis

Falin B. Patel; Kara Couch; Sean McNish; Jonathan D. Miller; Robert S. Siegel; Samantha Easley; Victoria K. Shanmugam

Chief symptoms A 66-year-old Hispanic Caucasian woman with a 14-year history of diffuse scleroderma and a history of bilateral breast cancer presented for evaluation of a vasculitic rash and hemoptysis with positive proteinase 3 (PR3) serology, raising concern for possible granulomatosis with polyangiitis (Wegener’s) (GPA) or antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV).


Head and Neck-journal for The Sciences and Specialties of The Head and Neck | 2016

Neoadjuvant chemotherapy and transoral surgery as a definitive treatment for oropharyngeal cancer: A feasible novel approach.

Nader Sadeghi; Ning‐Wei Li; M. Reza Taheri; Samantha Easley; Robert S. Siegel

The purpose of this study was to present our evaluation of the outcome of oropharyngeal cancer managed with neoadjuvant chemotherapy and transoral surgery (TOS) with neck dissection as definitive treatment.

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Samuel J. Simmens

George Washington University

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Jeanny B. Aragon-Ching

Washington University in St. Louis

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Hiwot Guebre-Xabiher

Washington University in St. Louis

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Sidney W. Fu

George Washington University

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Frederick Hendricks

Washington University in St. Louis

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Harold Frazier

Washington University in St. Louis

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Imad A. Tabbara

Washington University in St. Louis

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