Sabrina Martyr
National Institutes of Health
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Featured researches published by Sabrina Martyr.
Nature Medicine | 2003
Kenyatta Cosby; Kristine Partovi; Jack H. Crawford; Rakesh P. Patel; Christopher D. Reiter; Sabrina Martyr; Benjamin K. Yang; Myron A. Waclawiw; Gloria Zalos; Xiuli Xu; Kris T. Huang; Howard Shields; Daniel B. Kim-Shapiro; Alan N. Schechter; Richard O. Cannon; Mark T. Gladwin
Nitrite anions comprise the largest vascular storage pool of nitric oxide (NO), provided that physiological mechanisms exist to reduce nitrite to NO. We evaluated the vasodilator properties and mechanisms for bioactivation of nitrite in the human forearm. Nitrite infusions of 36 and 0.36 μmol/min into the forearm brachial artery resulted in supra- and near-physiologic intravascular nitrite concentrations, respectively, and increased forearm blood flow before and during exercise, with or without NO synthase inhibition. Nitrite infusions were associated with rapid formation of erythrocyte iron-nitrosylated hemoglobin and, to a lesser extent, S-nitroso-hemoglobin. NO-modified hemoglobin formation was inversely proportional to oxyhemoglobin saturation. Vasodilation of rat aortic rings and formation of both NO gas and NO-modified hemoglobin resulted from the nitrite reductase activity of deoxyhemoglobin and deoxygenated erythrocytes. This finding links tissue hypoxia, hemoglobin allostery and nitrite bioactivation. These results suggest that nitrite represents a major bioavailable pool of NO, and describe a new physiological function for hemoglobin as a nitrite reductase, potentially contributing to hypoxic vasodilation.
Lancet Oncology | 2015
Mohammed Farooqui; Janet Valdez; Sabrina Martyr; Georg Aue; Nakhle S. Saba; Carsten U. Niemann; Sarah E. M. Herman; Xin Tian; Gerald E. Marti; Susan Soto; Thomas Hughes; Jade Jones; Andrew Lipsky; Stefania Pittaluga; Maryalice Stetler-Stevenson; Constance Yuan; Yuh Shan Lee; Lone Bredo Pedersen; Christian H Geisler; Katherine R. Calvo; Diane C. Arthur; Irina Maric; Richard Childs; Neal S. Young; Adrian Wiestner
BACKGROUND Patients with chronic lymphocytic leukaemia (CLL) with TP53 aberrations respond poorly to first-line chemoimmunotherapy, resulting in early relapse and short survival. We investigated the safety and activity of ibrutinib in previously untreated and relapsed or refractory CLL with TP53 aberrations. METHODS In this investigator-initiated, single-arm phase 2 study, we enrolled eligible adult patients with active CLL with TP53 aberrations at the National Institutes of Health Clinical Center (Bethesda, MD, USA). Patients received 28-day cycles of ibrutinib 420 mg orally once daily until disease progression or the occurrence of limiting toxicities. The primary endpoint was overall response to treatment at 24 weeks in all evaluable patients. This study is registered with ClinicalTrials.gov, number NCT01500733, and is fully enrolled. FINDINGS Between Dec 22, 2011, and Jan 2, 2014, we enrolled 51 patients; 47 had CLL with deletion 17p13.1 and four carried a TP53 mutation in the absence of deletion 17p13.1. All patients had active disease requiring therapy. 35 enrolled patients had previously untreated CLL and 16 had relapsed or refractory disease. Median follow-up was 24 months (IQR 12.9-27.0). 33 previously untreated patients and 15 patients with relapsed or refractory CLL were evaluable for response at 24 weeks. 32 (97%; 95% CI 86-100) of 33 previously untreated patients achieved an objective response, including partial response in 18 patients (55%) and partial response with lymphocytosis in 14 (42%). One patient had progressive disease at 0.4 months. 12 (80%; 95% CI 52-96) of the 15 patients with relapsed or refractory CLL had an objective response: six (40%) achieved a partial response and six (40%) a partial response with lymphocytosis; the remaining three (20%) patients had stable disease. Grade 3 or worse treatment-related adverse events were neutropenia in 12 (24%) patients (grade 4 in one [2%] patient), anaemia in seven (14%) patients, and thrombocytopenia in five (10%) patients (grade 4 in one [2%] patient). Grade 3 pneumonia occurred in three (6%) patients, and grade 3 rash in one (2%) patient. INTERPRETATION The activity and safety profile of single-agent ibrutinib in CLL with TP53 aberrations is encouraging and supports its consideration as a novel treatment option for patients with this high-risk disease in both first-line and second-line settings. FUNDING Intramural Research Program of the National Heart, Lung, and Blood Institute and the National Cancer Institute, Danish Cancer Society, Novo Nordisk Foundation, National Institutes of Health Medical Research Scholars Program, and Pharmacyclics Inc.
British Journal of Haematology | 2005
Roberto F. Machado; Sabrina Martyr; Gregory J. Kato; Robyn J. Barst; Anastasia Anthi; Michael R. Robinson; Lori A. Hunter; Wynona Coles; James S. Nichols; Christian J. Hunter; Vandana Sachdev; Oswaldo Castro; Mark T. Gladwin
Pulmonary hypertension is a frequent complication of sickle cell disease that is associated with haemolysis, impaired nitric oxide bioavailability and high mortality. We sought to evaluate the safety and efficacy of selective pulmonary vasodilators and antiproliferative agents in this at‐risk population. After optimising sickle cell disease therapy to stabilise haemoglobin and fetal haemoglobin levels, we evaluated the safety and efficacy of sildenafil in 12 patients with sickle cell disease and pulmonary hypertension. Sildenafil therapy (mean duration 6 ± 1 months) decreased the estimated pulmonary artery systolic pressure [50 ± 4 to 41 ± 3 mmHg; difference 9 mmHg, 95% confidence interval (CI): 0·3–17, P = 0·043] and increased the 6‐min walk distance (384 ± 30 to 462 ± 28 m; difference 78 m, 95% CI: 40–117, P = 0·0012). Transient headaches occurred in two patients and transient eye‐lid oedema in four patients. No episodes of priapism occurred in the three men in the study; two of them were on chronic exchange transfusions and one had erectile dysfunction. In conclusion: (1) sickle cell disease patients with anaemia and pulmonary hypertension have significant exercise limitation; (2) the 6‐min walk distance may be a valid endpoint in this population; (3) therapy with sildenafil appears safe and improves pulmonary hypertension and exercise capacity. Additional phase I studies in males with sickle cell disease followed by phase II/III placebo controlled trials evaluating the safety and efficacy of sildenafil therapy in sickle cell disease patients with pulmonary hypertension are warranted.
British Journal of Haematology | 2005
Gregory J. Kato; Sabrina Martyr; William C. Blackwelder; James S. Nichols; Wynona Coles; Lori A. Hunter; Marie Luise Brennan; Stanley L. Hazen; Mark T. Gladwin
Endothelial cell adhesion molecules orchestrate the recruitment and binding of inflammatory cells to vascular endothelium. With endothelial dysfunction and vascular injury, the levels of endothelial bound and soluble adhesion molecules increase. Such expression is modulated by nitric oxide (NO), and in patients with sickle cell disease (SCD), these levels are inversely associated with measures of NO bioavailability. To further evaluate the role of endothelial dysfunction in a population study of SCD, we have measured the levels of soluble endothelium‐derived adhesion molecules in the plasma specimens of 160 adult patients with SCD during steady state. Consistent with a link between endothelial dysfunction and end‐organ disease, we found that higher levels of soluble vascular cell adhesion molecule‐1 (sVCAM‐1) were associated with markers indicating renal dysfunction and hepatic impairment. Analysis of soluble intercellular cell adhesion molecule‐1 (sICAM‐1), sE‐selectin and sP‐selectin levels indicated partially overlapping associations with sVCAM‐1, with an additional association with inflammatory stress and triglyceride levels. Importantly, increased soluble adhesion molecule expression correlated with severity of pulmonary hypertension, a clinical manifestation of endothelial dysfunction. Soluble VCAM‐1, ICAM‐1, and E‐selectin were independently associated with the risk of mortality in this cohort. Our data are consistent with steady state levels of soluble adhesion molecules as markers of pulmonary hypertension and risk of death.
British Journal of Haematology | 2007
Roberto F. Machado; A. Kyle Mack; Sabrina Martyr; Christopher F. Barnett; Peter H. MacArthur; Vandana Sachdev; Inez Ernst; Lori A. Hunter; Wynona Coles; James P. Nichols; Gregory J. Kato; Mark T. Gladwin
Pulmonary hypertension is associated with sudden death and is a risk factor for mortality in adult patients with sickle cell disease. The high mortality despite only mild‐to‐moderate increases in pulmonary vascular resistance remains an unresolved paradox. Accordingly, little is known about the cardiovascular effects of stressors, such as vaso‐occlusive pain crisis (VOC) and exercise, which may acutely increase pulmonary pressures and impair right heart function. We therefore evaluated pulmonary artery pressures by echocardiogram in 25 patients with sickle cell disease in steady‐state and during VOC, and by right heart catheterisation with exercise in a second cohort of 21 patients to determine whether pulmonary hypertension worsens during acute cardiopulmonary stress. TRV increased during VOC (P < 0·001), and the increased pulmonary pressures during VOC were associated with decreases in haemoglobin levels (P < 0·001), and increases in lactate dehydrogenase (P < 0·001) and plasma haemoglobin levels (P = 0·03). During exercise stress performed during cardiac catheterisation, mean pulmonary artery pressures (P < 0·001) and pulmonary vascular resistance increased (P < 0·001) in all subjects. These data suggest that acute elevations in pulmonary pressures during VOC or exercise may contribute to morbidity and mortality in patients with sickle cell disease.
Leukemia | 2014
Sarah E. M. Herman; Carsten U. Niemann; Mohammed Farooqui; Jade Jones; Rashida Z. Mustafa; Andrew Lipsky; Nakhle S. Saba; Sabrina Martyr; Susan Soto; Janet Valdez; Jennifer Gyamfi; Irina Maric; Katherine R. Calvo; Lone Bredo Pedersen; Christian H. Geisler; Delong Liu; Gerald E. Marti; Georg Aue; Adrian Wiestner
Ibrutinib and other targeted inhibitors of B-cell receptor signaling achieve impressive clinical results for patients with chronic lymphocytic leukemia (CLL). A treatment-induced rise in absolute lymphocyte count (ALC) has emerged as a class effect of kinase inhibitors in CLL and warrants further investigation. Here we report correlative studies in 64 patients with CLL treated with ibrutinib. We quantified tumor burden in blood, lymph nodes (LNs), spleen and bone marrow, assessed phenotypic changes of circulating cells and measured whole-blood viscosity. With just one dose of ibrutinib, the average increase in ALC was 66%, and in>40% of patients the ALC peaked within 24 h of initiating treatment. Circulating CLL cells on day 2 showed increased Ki67 and CD38 expression, indicating an efflux of tumor cells from the tissue compartments into the blood. The kinetics and degree of the treatment-induced lymphocytosis was highly variable; interestingly, in patients with a high baseline ALC the relative increase was mild and resolution rapid. After two cycles of treatment the disease burden in the LN, bone marrow and spleen decreased irrespective of the relative change in ALC. Whole-blood viscosity was dependent on both ALC and hemoglobin. No adverse events were attributed to the lymphocytosis.
Haematologica | 2015
Andrew Lipsky; Mohammed Farooqui; Xin Tian; Sabrina Martyr; Ann M. Cullinane; Khanh Nghiem; Clare Sun; Janet Valdez; Carsten U. Niemann; Sarah E. M. Herman; Nakhle S. Saba; Susan Soto; Gerald E. Marti; Gulbu Uzel; Steve M. Holland; Jay N. Lozier; Adrian Wiestner
Ibrutinib is associated with bleeding-related adverse events of grade ≤2 in severity, and infrequently with grade ≥3 events. To investigate the mechanisms of bleeding and identify patients at risk, we prospectively assessed platelet function and coagulation factors in our investigator-initiated trial of single-agent ibrutinib for chronic lymphocytic leukemia. At a median follow-up of 24 months we recorded grade ≤2 bleeding-related adverse events in 55% of 85 patients. No grade ≥3 events occurred. Median time to event was 49 days. The cumulative incidence of an event plateaued by 6 months, suggesting that the risk of bleeding decreases with continued therapy. At baseline, von Willebrand factor and factor VIII levels were often high and normalized on treatment. Platelet function measured via the platelet function analyzer (PFA-100™) was impaired in 22 patients at baseline and in an additional 19 patients on ibrutinib (often transiently). Collagen and adenosine diphosphate induced platelet aggregation was tested using whole blood aggregometry. Compared to normal controls, response to both agonists was decreased in all patients with chronic lymphocytic leukemia, whether on ibrutinib or not. Compared to untreated chronic lymphocytic leukemia patients, response to collagen showed a mild further decrement on ibrutinib, while response to adenosine diphosphate improved. All parameters associated with a significantly increased risk of bleeding-related events were present at baseline, including prolonged epinephrine closure time (HR 2.74, P=0.012), lower levels of von Willebrand factor activity (HR 2.73, P=0.009) and factor VIII (HR 3.73, P=0.0004). In conclusion, both disease and treatment-related factors influence the risk of bleeding. Patients at greater risk for bleeding of grade ≤2 can be identified by clinical laboratory tests and counseled to avoid aspirin, non-steroidal anti-inflammatory drugs and fish oils. ClinicalTrials.gov identifier NCT01500733
European Journal of Haematology | 2009
Jane A. Little; Kristine Partovi Hauser; Sabrina Martyr; Amy Harris; Irina Maric; Claudia R. Morris; Jung H. Suh; James O. Taylor; Oswaldo Castro; Roberto Machado; Gregory J. Kato; Mark T. Gladwin
Objectives: Fetal hemoglobin (HbF) induction involves NO‐cGMP signaling pathways. l‐arginine, an NO precursor, and the phosphodiesterase (PDE) 5 inhibitor sildenafil, which potentiates cGMP, were studied in adults with sickle cell disease (SCD) who were stably on HU.
Clinical Cancer Research | 2016
Carsten U. Niemann; Sarah E.M. Herman; Irina Maric; Julio Gomez-Rodriguez; Angélique Biancotto; Betty Y. Chang; Sabrina Martyr; Maryalice Stetler-Stevenson; Constance Yuan; Katherine R. Calvo; Raul C. Braylan; Janet Valdez; Yuh Shan Lee; Deanna H. Wong; Jade Jones; Clare Sun; Gerald E. Marti; Mohammed Farooqui; Adrian Wiestner
Purpose: Chronic lymphocytic leukemia (CLL) cells depend on microenvironmental interactions for proliferation and survival that are at least partially mediated through B-cell receptor (BCR) signaling. Ibrutinib, a Bruton tyrosine kinase inhibitor, disrupts BCR signaling and leads to the egress of tumor cells from the microenvironment. Although the on-target effects on CLL cells are well defined, the impact on the microenvironment is less well studied. We therefore sought to characterize the in vivo effects of ibrutinib on the tumor microenvironment. Experimental Design: Patients received single-agent ibrutinib on an investigator-initiated phase II trial. Serial blood and tissue samples were collected pretreatment and during treatment. Changes in cytokine levels, cellular subsets, and microenvironmental interactions were assessed. Results: Serum levels of key chemokines and inflammatory cytokines decreased significantly in patients on ibrutinib. Furthermore, ibrutinib treatment decreased circulating tumor cells and overall T-cell numbers. Most notably, a reduced frequency of the Th17 subset of CD4+ T cells was observed concurrent with reduced expression of activation markers and PD-1 on T cells. Consistent with direct inhibition of T cells, ibrutinib inhibited Th17 differentiation of murine CD4+ T cells in vitro. Finally, in the bone marrow microenvironment, we found that ibrutinib disaggregated the interactions of macrophages and CLL cells, inhibited secretion of CXCL13, and decreased the chemoattraction of CLL cells. Conclusions: In conjunction with inhibition of BCR signaling, these changes in the tumor microenvironment likely contribute to the antitumor activity of ibrutinib and may impact the efficacy of immunotherapeutic strategies in patients with CLL. Clin Cancer Res; 22(7); 1572–82. ©2015 AACR. See related commentary by Bachireddy and Wu, p. 1547
Clinical Cancer Research | 2016
Martin Skarzynski; Carsten U. Niemann; Yuh Shan Lee; Sabrina Martyr; Irina Maric; Dalia A. Salem; Maryalice Stetler-Stevenson; Gerald E. Marti; Katherine R. Calvo; Constance Yuan; Janet Valdez; Susan Soto; Mohammed Farooqui; Sarah E.M. Herman; Adrian Wiestner
Purpose: Clinical trials of ibrutinib combined with anti-CD20 monoclonal antibodies (mAb) for chronic lymphocytic leukemia (CLL) report encouraging results. Paradoxically, in preclinical studies, in vitro ibrutinib was reported to decrease CD20 expression and inhibit cellular effector mechanisms. We therefore set out to investigate effects of in vivo ibrutinib treatment that could explain this paradox. Experimental Design: Patients received single-agent ibrutinib (420 mg daily) on an investigator-initiated phase II trial. Serial blood samples were collected pretreatment and during treatment for ex vivo functional assays to examine the effects on CLL cell susceptibility to anti-CD20 mAbs. Results: We demonstrate that CD20 expression on ibrutinib was rapidly and persistently downregulated (median reduction 74%, day 28, P < 0.001) compared with baseline. Concomitantly, CD20 mRNA was decreased concurrent with reduced NF-κB signaling. An NF-κB binding site in the promoter of MS4A1 (encoding CD20) and downregulation of CD20 by NF-κB inhibitors support a direct transcriptional effect. Ex vivo, tumor cells from patients on ibrutinib were less susceptible to anti-CD20 mAb-mediated complement-dependent cytotoxicity than pretreatment cells (median reduction 75%, P < 0.001); however, opsonization by the complement protein C3d, which targets cells for phagocytosis, was relatively maintained. Expression of decay-accelerating factor (CD55) decreased on ibrutinib, providing a likely mechanism for the preserved C3d opsonization. In addition, ibrutinib significantly inhibited trogocytosis, a major contributor to antigen loss and tumor escape during mAb therapy. Conclusions: Our data indicate that ibrutinib promotes both positive and negative interactions with anti-CD20 mAbs, suggesting that successfully harnessing maximal antitumor effects of such combinations requires further investigation. Clin Cancer Res; 22(1); 86–95. ©2015 AACR.