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Meir Wetzler

Publications and source records attributed to Meir Wetzler.

17 recordsLinked to original sources
PubMed2006

Arsenic trioxide affects signal transducer and activator of transcription proteins through alteration of protein tyrosine kinase phosphorylation.

PURPOSE: Arsenic trioxide decreases proliferation of acute myeloid leukemia (AML) cells, but its precise mechanism of action is unknown. EXPERIMENTAL DESIGN: We studied the effect of arsenic trioxide on patient samples and the AML cell line HEL, which, like leukemic blasts from 50% of AML cases, has constitutively activated signal transducer and activator of transcription (STAT) proteins. RESULTS: Arsenic trioxide induced mitotic arrest starting at 24 hours and significant cell death at 48 hours. These events were preceded by an arsenic trioxide dose-dependent down-regulation of activated STAT proteins starting at 6 hours. We hypothesized that arsenic trioxide inhibits protein tyrosine kinases (PTK), which, among others, phosphorylate and activate STATs. We therefore studied arsenic trioxide effects on Janus kinases and on three oncogenic PTKs that are known to activate STATs [FLT3, ZNF198/fibroblast growth factor receptor 1 (FGFR1), and BCR/ABL]. Arsenic trioxide reduced STAT3 activation by Janus kinases, altered phosphorylation and electrophoretic mobility of ZNF198/fibroblast growth factor receptor 1, reduced kinase protein level, and decreased STAT3 protein phosphorylation. Arsenic trioxide also reduced the phosphorylation of BCR/ABL and FLT3 with corresponding decreased STAT5 phosphorylation. CONCLUSIONS: These results suggest a selective activity of arsenic trioxide on PTKs and will assist in developing clinical trials in AML.

Antineoplastic Agents↗
PubMed2005

Sequential administration of irinotecan and cytarabine in the treatment of relapsed and refractory acute myeloid leukemia.

PURPOSE: Based on reported synergy of the topoisomerase-I (topo-I) inhibitor irinotecan with antimetabolites, irinotecan and cytarabine (Ara-C) were administered sequentially to patients with acute myeloid leukemia (AML) refractory to or relapsed following high-dose Ara-C and anthracycline therapy. Pharmacokinetic and pharmacodynamic studies were performed with the first irinotecan dose. EXPERIMENTAL DESIGN: In vitro synergy of irinotecan followed by Ara-C was confirmed in a human AML cell line as a basis for the clinical trial. Irinotecan was administered daily for 5 days, with Ara-C 1 g/m2 12 h after each irinotecan dose. Irinotecan was initiated at 5 mg/m2, and the dose was escalated by 5 mg/m2 increments in cohorts of three patients and in individual patients. Pre-treatment samples were studied for topo-I activity and serial samples after the first irinotecan dose were analyzed for pharmacokinetics and for pharmacodynamic effects, including DNA damage and DNA synthesis rate. RESULTS: The irinotecan dose reached 15 mg/m2 in three-patient cohorts without reaching the maximum tolerated dose, and reached 30 mg/m2 in individual patients. The AUC and Cmax of both irinotecan and its active metabolite SN38 increased linearly in proportion to dose, and the mean half-lives of irinotecan conversion to SN38 and SN38 elimination were 6.2 h (CV 171%) and 7.2 h (CV 48%). Irinotecan rapidly induced DNA damage, and DNA synthesis inhibition varied among patients and treatment cycles. All courses resulted in rapid cytoreduction, and two patients achieved complete remission. Topo-I activity did not predict response. CONCLUSION: Irinotecan can be safely administered with Ara-C. This combination is active in refractory AML and warrants further study.

Acute Disease↗
PubMed2005

T-Cell activation by t(9;22) acute lymphoblastic leukemia-derived dendritic-like cells is associated with increased tapasin expression.

Dendritic-like cells from t(9;22) acute lymphoblastic leukemia (ALL) blasts can activate T cells, while the original unmodified leukemic blasts cannot. To determine whether these functional differences were associated with differences in antigen-processing machinery (APM) component expression, we have measured the level of APM component expression in unmodified blasts and ALL-derived dendritic-like cells. Seven t(9;22) ALL patient samples and one cell line were studied for APM component expression utilizing a unique panel of recently developed monoclonal antibodies and a recently developed intracellular staining technique. In addition, the HLA class I antigen cell surface expression was measured. HLA class I antigens were similarly expressed on the unmodified blasts and on the autologous dendritic-like cells. Intracellular HLA class I antigen and tapasin expression (P=0.03 for both) were upregulated in all t(9;22) ALL-derived dendritic-like cells, in comparison to the unmodified blasts. These results provide a potential mechanism for the ability of t(9;22) ALL-derived dendritic-like cells to induce T-cell activation and, suggest that tapasin upregulation may serve as a marker to standardize and monitor the quality of the dendritic-like cells used in immunotherapy.

Antibodies, Monoclonal↗
PubMed2005

Genomic profiling of myeloid sarcoma by array comparative genomic hybridization.

Myeloid sarcoma (MS) is a tumor mass of myeloblasts or immature myeloid cells occurring in an extramedullary site. In this study, seven cases of MS [stomach (1), testis (1), skin (2), and lymph node (3)] and 3 synchronous and 1 follow-up bone marrow (BM) samples were studied for genomic abnormalities using array comparative genomic hybridization (array-CGH). Array-CGH construction used approximately 5,400 bacterial artificial chromosome clones from the RPCI-11 library, spanning the human genome. Data were analyzed using the DNAcopy software and custom heuristics. All MS cases had genomic abnormalities detected by array-CGH. Unbalanced genomic abnormalities in five MS cases were confirmed by conventional cytogenetics (CC) and/or fluorescence in situ hybridization (FISH); these abnormalities included loss of 4q32.1-q35.2, 6q16.1-q21, and 12p12.2-p13.2 and gain of 8q21.2-q24.3, 8, 11q21-q25, 13q21.32-q34, 19, and 21. Array-CGH was also invaluable in identifying possible deletions, partner translocations, and breakpoints that were questionable by CC. The remaining two MS cases had genomic aberrations detected by array-CGH, but were not studied further by CC/FISH. Chromosome 8 was most commonly abnormal (3/7 cases). Identical genomic abnormalities were demonstrated in MS and in synchronous BM in two cases. These results demonstrate that array-CGH is a powerful tool to screen MS tissue for unbalanced genomic abnormalities, allowing identification of chromosome abnormalities when concurrent BM is nonanalyzable or nonleukemic.

Adult↗
PubMed2005

Invasive filamentous fungal infections in allogeneic hematopoietic stem cell transplant recipients after recovery from neutropenia: clinical, radiologic, and pathologic characteristics.

Invasive filamentous fungal infection (IFFI) is an important cause of mortality in allogeneic hematopoietic stem cell transplant (HSCT) recipients. We reviewed 22 consecutive cases of IFFI in allogeneic HSCT recipients at Roswell Park Cancer Institute. IFFI was diagnosed after neutrophil recovery in 21 patients (95%). All had received corticosteroids within 1 month prior to IFFI diagnosis. Fourteen (64%) presented with dyspnea, and only 7 (32%) were febrile. Aspergillus species were isolated in 18 (82%) cases. Thirty day mortality after IFFI diagnosis was associated with a higher mean daily dose of corticosteroids (P=0.02) and receiving OKT3 (P=0.01) within 1 month prior to IFFI diagnosis and serum creatinine>2 mg/dl at the time of diagnosis (P=0.004). Histopathologic material from biopsy or autopsy was available in 15 patients (68%). In 8 (53%), the predominant lung histopathology was an acellular coagulative necrosis and hyphal angioinvasion was observed in some of these cases. These findings have generally been observed in neutropenic patients but not in non-neutropenic HSCT recipients. The predominance of coagulative necrosis in our series may reflect the high doses of corticosteroids used to treat graft-versus-host disease (GVHD), which may have disabled leukocyte trafficking and hyphal killing.

Adrenal Cortex Hormones↗
PubMed2004

Thrombotic microangiopathy after allogeneic blood and marrow transplantation is associated with dose-intensive myeloablative conditioning regimens, unrelated donor, and methylprednisolone T-cell depletion.

BACKGROUND: Allogeneic blood and marrow transplantation (BMT)-associated thrombotic microangiopathy (TM) contributes to transplant-related morbidity and mortality. This report examines the incidence of and risk factors for allogeneic BMT-associated TM in two patient cohorts treated before and after changes in myeloablative conditioning regimen intensity (high vs. standard intensity). METHODS: Cohort 1 includes 153 consecutive allogeneic BMT patients who underwent transplantation between April 1994 and October 1997 with an allogeneic BMT-associated TM crude incidence of 12%. Cohort 2 includes 75 consecutive allogeneic BMT patients who underwent transplantation from November 1997 to November 2000 with an allogeneic BMT-associated TM crude incidence of 1%. RESULTS: In cohort 1, matched unrelated donor transplant and methylprednisolone (MP) T-cell depletion (TCD) of donor bone marrow were significantly associated with allogeneic BMT-associated TM by univariate analysis; therefore, a logistic model incorporating these effects was constructed to calculate the expected number of allogeneic BMT-associated TM cases in cohort 2. Seven cases would have been expected, but only one was observed (P = 0.003; bayesian predictive test). The multivariate analysis of both cohorts yielded MP-TCD (P<0.001), high-intensity myeloablative conditioning regimens used in cohort 1 (P = 0.02), and matched unrelated donor (P = 0.03) as significant predictors of time to allogeneic BMT-associated TM. CONCLUSION: Avoidance of high-intensity conditioning regimens may decrease the incidence of allogeneic BMT-associated TM.

Adolescent↗
PubMed2004

Characterization of dendritic-like cells derived from t(9;22) acute lymphoblastic leukemia blasts.

We asked herein whether functional dendritic-like cells could be generated from t(9;22) acute lymphoblastic leukemia (ALL) blasts. We first determined that the combination of interleukin (IL)-1beta, IL-3, IL-7, tumor necrosis factor-alpha, stem cell factor and CD40 ligand was optimal for generating dendritic-like cells from t(9;22) ALL cell lines. Following 6 days in culture, four of five cell lines demonstrated dendrite-like morphology, upregulation of CCR7, CD54, CD80 and CD86, uptake of extracellular proteins and activation of T cells, and similar results were obtained with blasts from three t(9;22) ALL patients. The dendritic-like cells appeared to be composed of populations resembling both immature and mature dendritic cells (DCs), distinguished by CD80 expression. CD80-CD86+ cells were classified as immature DCs, demonstrating high endocytic capability and inducing minimal allogeneic T cell proliferation, while CD80+CD86+ cells were classified as mature DCs, exhibiting negligible endocytic capability and inducing robust allogeneic T cell proliferation. These mature dendritic-like cells induced autologous cytotoxic T cell responses against the unmodified blasts in a patient who achieved prolonged remission. In summary, CD80+CD86+ cells generated from t(9;22) ALL blasts may be useful in adoptive immunotherapy for t(9;22) ALL.

Antigens, CD↗
PubMed2004

Massive hyperdiploidy and tetraploidy in acute myelocytic leukemia and myelodysplastic syndrome.

Massive hyperdiploidy (>50 chromosomes) and tetraploidy (4n) are rare cytogenetic abnormalities in myelocytic malignancies, and their significance is unknown. We report on 11 patients with acute myelocytic leukemia (AML) and two patients with a myelodysplastic syndrome (MDS) with massive hyperdiploidy (10 patients) or tetraploidy (3 patients) seen at our institution over a 12-year period. Eleven patients were male and two were female. Age range was 44-84 years (median, 70 years). Only one AML patient had a previous MDS, and no patient had therapy-related disease. One or more copies of chromosomes 8 and 19 were gained in eight patients each; other frequently gained chromosomes included 13, 15, and 21. Eight patients had structural abnormalities in addition to chromosome gain; del(5q) was most common (five patients). Eleven patients received induction chemotherapy, but only four achieved complete remission. Survival ranged from 1 to 22 months, with a median of 6 months. We conclude that massive hyperdiploidy and tetraploidy are infrequent abnormalities in AML and MDS, are seen primarily in de novo disease in older male patients and are associated with a low remission rate and short survival. Massive hyperdiploidy and tetraploidy define a prognostically unfavorable cytogenetic group in de novo AML.

Adult↗
PubMed2004

Additional cytogenetic abnormalities in adults with Philadelphia chromosome-positive acute lymphoblastic leukaemia: a study of the Cancer and Leukaemia Group B.

We analysed the nature and prognostic significance of secondary cytogenetic changes in 111 newly diagnosed adults with acute lymphoblastic leukaemia (ALL) and t(9;22)(q34;q11.2) or its variants. Secondary aberrations were seen in 75 (68%) patients. They included, in order of descending frequency: +der(22)t(9;22), +21, abnormalities of 9p, high hyperdiploidy (>50 chromosomes), +8, -7, +X and abnormalities resulting in loss of material from 8p, gain of 8q, gain of 1q and loss of 7p. Eighty patients (72%) had > or =1 normal metaphase in their karyotype. There were four balanced and 12 unbalanced translocations previously unreported in ALL with t(9;22). The t(2;7)(p11;p13) and der(18)t(8;18)(q11.2;p11.2) were seen in two cases each, and have never before been reported in haematological malignancy. All but four patients were treated on front-line Cancer and Leukaemia Group B clinical protocols. The presence of -7 as a sole secondary abnormality was associated with a lower complete remission (CR) rate (P = 0.004), while the presence of > or =3 aberrations was associated with a higher CR rate (P = 0.009) and +der(22)t(9;22) with a higher cumulative incidence of relapse (P = 0.02). It will be of interest to see if newly diagnosed t(9;22)-positive adult ALL patients with these and other secondary aberrations respond differently to treatment regimens that include imatinib mesylate.

Adult↗
PubMed2004

Breast cancer resistance protein (BCRP/MXR/ABCG2) in adult acute lymphoblastic leukaemia: frequent expression and possible correlation with shorter disease-free survival.

Drugs used in treatment of adult acute lymphoblastic leukaemia (ALL) are substrates for breast cancer resistance protein (BCRP, MXR, ABCG2), which may thus play a role in resistance in this disease. Pretreatment blasts from 30 adult ALL patients were studied for BCRP mRNA by quantitative reverse transcription polymerase chain reaction analysis, BCRP protein by immunophenotyping with three antibodies and BCRP function by fumitremorgin C modulation of intracellular mitoxantrone retention, measured by flow cytometry. BCRP mRNA in all cases encoded wild type protein (BCRP(R482)), which mediates mitoxantrone and methotrexate resistance, but only low-level anthracycline resistance. The BXP-21, BXP-34 and anti-ABCG2 antibodies stained blasts in 13, 11 and 14 cases (43%, 37% and 47%); BXP-21 correlated well with BXP-34 and anti-ABCG2, but BXP-34 and anti-ABCG2 did not correlate, and antibody staining did not correlate with mRNA levels. BCRP function was seen in 21 cases (70%), but correlated poorly with antibody staining. An exploratory statistical analysis indicated that BXP-21 staining was predictive of shorter disease-free survival (DFS) (P = 0.0374) in this small patient population. Poor correlations between mRNA, protein and function indicate the complex biology of BCRP in adult ALL, and the possible correlation of BCRP expression with DFS should be studied in larger series.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

Linezolid-resistant Enterococcus faecalis isolated from a cord blood transplant recipient.

We report a linezolid-resistant Enterococcus faecalis infection in a cord blood stem cell transplant recipient previously treated with linezolid for bloodstream infections by vancomycin-resistant enterococci. Sequencing showed a G2576U mutation in the 23S rRNA gene. Because of the important niche of linezolid in cancer treatment, linezolid-resistant E. faecalis is noteworthy.

Acetamides↗
PubMed2004

Precursor B lymphoblastic leukemia with surface light chain immunoglobulin restriction: a report of 15 patients.

We describe 15 patients (9 children) with precursor B-cell (pB) acute lymphoblastic leukemia (ALL) with surface immunoglobulin (sIg) light chain restriction revealed by flow cytometric immunophenotyping (FCI). The same sIg+ immunophenotype was present at diagnosis and in 3 relapses in 1 patient. In 15 patients, blasts were CD19+ CD10+ (bright coexpression) in 14, CD34+ in 12, surface kappa+ in 12, surface lambda+ in 3; in 8 of 8, terminal deoxyribonucleotidyl transferase (TdT)+; and in 4, surface IgD+ in 2 and surface IgM+ in 1. The 3 CD34- cases included 1 TdT+ case, 1 with t(1;19)(q23;p13), and 1 infant with 70% marrow blasts. One adult had CD10- CD19+ CD20- CD22+ CD34+ TdT+ sIg+ blasts with t(2;11)(p21;q23). Blasts were L1 or L2 in all cases (French-American-British classification). Karyotypic analysis in 12 of 12 analyzable cases was negative for 8q24 (myc) translocation. Karyotypic abnormalities, confirmed by fluorescence in situ hybridization in 6 cases, included hyperdiploidy, t(1;19)(q23;p13), t(12;21)(p13;q22), t(9;22)(q34;q11), t(2;11)(p21;q23), and trisomy 12. The sIg light chain restriction in pB ALL might be present in neoplasms arising from the early, intermediate, and late stages of precursor B-cell maturation; sIg light chain restriction revealed by FCI does not necessarily indicate a mature B-cell phenotype, further emphasizing the importance of a multidisciplinary approach to diagnosing B-lymphoid neoplasms.

Adolescent↗
PubMed2002

Signal transducer and activator of transcription proteins in leukemias.

Signal transducer and activator of transcription (STAT) proteins are a 7-member family of cytoplasmic transcription factors that contribute to signal transduction by cytokines, hormones, and growth factors. STAT proteins control fundamental cellular processes, including survival, proliferation, and differentiation. Given the critical roles of STAT proteins, it was hypothesized that inappropriate or aberrant activation of STATs might contribute to cellular transformation and, in particular, leukemogenesis. Constitutive activation of mutated STAT3 has in fact been demonstrated to result in transformation. STAT activation has been extensively studied in leukemias, and mechanisms of STAT activation and the potential role of STAT signaling in leukemogenesis are the focus of this review. A better understanding of mechanisms of dysregulation of STAT signaling pathways may serve as a basis for designing novel therapeutic strategies that target these pathways in leukemia cells.

Animals↗
PubMed2002

Constitutive activity of signal transducer and activator of transcription 3 protein in acute myeloid leukemia blasts is associated with short disease-free survival.

Signal transducer and activator of transcription (STAT) proteins are involved in hematopoietic cytokine receptor signaling pathways that regulate cell proliferation, differentiation, and survival. STATs are dysregulated in acute myeloid leukemia (AML); mechanisms of dysregulation include constitutive activation and truncation of the C-terminal transactivation domain; the latter results in a beta isoform that has a trans-dominant negative effect on gene induction mediated by the full-length STAT alpha form. It was hypothesized that constitutive STAT activity might correlate with unfavorable treatment outcome in AML. Pretreatment bone marrow samples from 63 adult patients with AML were analyzed by electrophoretic mobility shift assay for the presence of STAT DNA-binding activity. Isoforms and relative levels of STAT proteins were determined by immunoblotting. Constitutive STAT3 activity was detected in samples from 28 (44%) patients. Pretreatment clinical characteristics, expression of STAT alpha/beta isoforms, and treatment regimens did not differ significantly between patients with and without constitutive STAT3 activity. Disease-free survival (DFS) was significantly shorter in patients with than in patients without constitutive STAT3 activity (median 8.7 vs 20.6 months; P =.01). Overall survival did not differ significantly. The subgroup of patients with constitutive STAT3 activity and the STAT3 beta isoform had the shortest DFS (P =.006) and shorter overall survival (P =.049) than all other patients. Whether adverse treatment outcome is attributable to constitutive STAT activity itself or to a process that leads to constitutive STAT activity remains to be determined. This is the first demonstration of a prognostic significance for STAT proteins in a malignancy.

Bone Marrow↗
PubMed2002

Pharmacodynamic modeling of thrombopoietin, platelet, and megakaryocyte dynamics in patients with acute myeloid leukemia undergoing dose intensive chemotherapy.

A proposed model of thrombopoietin (TPO) regulation is that of a constitutive production of TPO with circulating levels being predominately regulated by changes in platelet and megackaryocyte mass. Using a pharmacodynamic (PD) approach, the authors examined the validity of this model for patients with acute myeloid leukemia (AML) undergoing dose-intensive postinduction chemotherapy (HDT). TPO and platelet values were assayed weekly in AML patients undergoing HDT. A parsimonious dynamic model was then applied to these experimental data. The results (1) support the proposed model of TPO regulation, (2) model and quantify the effects of HDT on the megakaryocyte compartment, (3) characterize variables not amenable to direct measurement, and (4) have clinical utility as this model predicted that TPO given after HDT would not have a significant effect on platelet recovery, a finding borne out in clinical trials. This model provides information relevant to the interpretation of clinical trials of hematopoietic growth factors.

Adult↗
PubMedDate not supplied

Simvastatin-fluconazole causing rhabdomyolysis.

OBJECTIVE: To report a case of rhabdomyolysis after concomitant use of simvastatin, a commonly used hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, and fluconazole, an azole antifungal agent. CASE SUMMARY: An 83-year-old white man with a history of congestive heart failure and hyperlipidemia presented to the hospital 1 week following the addition of fluconazole to a medication regimen that included simvastatin 40 mg once daily. The patient had severe muscle weakness and a markedly elevated serum creatine kinase activity, which resolved following discontinuation of simvastatin and fluconazole. DISCUSSION: Rhabdomyolysis is a recognized adverse effect of HMG-CoA reductase inhibitors (statins), commonly caused by their interaction with other drugs, such as azole antifungals, that inhibit the cytochrome P450 isoenzyme family. An objective causality assessment revealed that the adverse drug event was probable. Although drug interactions have been described for combinations of other HMG-CoA reductase inhibitors and azole antifungals, rhabdomyolysis likely caused by the interaction between simvastatin and fluconazole has not yet been reported. This case reinforces the importance of being vigilant for drug interactions, particularly in connection with commonly prescribed medications such as statins. CONCLUSIONS: Patients receiving statins who have cancer may receive azole antifungals and other drugs that inhibit CYP3A4 during treatment, predisposing them to toxicity. These patients should therefore be monitored closely for drug interactions.

Aged↗