Bio

Clinical Focus


  • lymphoblastic lymphoma, childhood
  • ALL, childhood and adolescent/young adult
  • AML, childhood and adolescent/young adult
  • Hematology/Oncology
  • Hematology/Oncology/Stem Cell Transplant, Pediatric
  • Oncology (Cancer), Pediatric

Academic Appointments


Administrative Appointments


  • Myeloid Steering Committee, Children's Oncology Group (2007 - Present)
  • Member, Cancer Center (2007 - Present)

Honors & Awards


  • Molecular and Pharmacologic Correlates of Acute Myeloid Leukemia in Down Syndrome, NIH ROI subcontract from Wayne State University (01/09-04/16)
  • Banking Acute Leukemia Specimens at Lucile Packard Children’s Hospital: Hyundai Infrastructure Grant, Hyundai Foundation (10/11-09/12)
  • New Approaches in Pediatric Myeloid Leukemia, V Foundation (10/09-09/12)
  • Member, Alpha Omega Alpha (1990)

Professional Education


  • Internship:UCSF Medical Center (1990) CA
  • Residency:UCSF Medical Center (1992) CA
  • Board Certification: Hematology/Oncology, American Board of Pediatrics (1996)
  • Fellowship:Stanford University Medical Center (1995) CA
  • Medical Education:UCSF School of Medicine (1989) CA
  • MD, U.C., San Francisco, Medicine (1989)
  • BA, U. C., Berkeley, Biochemistry (1985)

Research & Scholarship

Current Research and Scholarly Interests


Pediatric Hematology/Oncology, Phase I drug studies for refractory and relapsed leukemia; genomic studies, biologic risk-stratification and treatment of acute myeloid leukemia; prediction or induction response and risk of relapse using phosphoproteomics in childhood AML; novel MRD techniques in childhood ALL.

Clinical Trials


  • Efficacy and Safety of Donepezil Hydrochloride in Preadolescent and Adolescent Children With Attention Impairment Following Cancer Treatment Not Recruiting

    The purpose of this study is to evaluate the efficacy, safety and tolerability of donepezil in children with persistent attention impairment that is present at least 12 months after the completion of cancer treatment.

    Stanford is currently not accepting patients for this trial. For more information, please contact Jennifer Lew, (650) 725 - 4318.

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  • Ixabepilone in Treating Young Patients With Refractory Solid Tumors Not Recruiting

    This phase II trial is studying how well ixabepilone works in treating young patients with refractory solid tumors. Drugs used in chemotherapy, such as ixabepilone, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing.

    Stanford is currently not accepting patients for this trial. For more information, please contact Norman Lacayo, (650) 723 - 5535.

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  • Treatment of Patients With Newly Diagnosed Acute Myeloid Leukemia or Myelodysplasia Not Recruiting

    The purpose of this study is to compare the effectiveness of two multi-agent chemotherapy regimens using different dosages of cytarabine to eliminate all detectable leukemia.

    Stanford is currently not accepting patients for this trial. For more information, please contact LPCH New Patient Coordinator, (650) 725 - 1072.

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  • A Pharmacokinetic (PK) Study of Nilotinib in Pediatric Patients With Philadelphia Chromosome-positive (Ph+) Chronic Myelogenous Leukemia (CML) or Acute Lymphoblastic Leukemia (ALL) Recruiting

    This study will assess the pharmacokinetics of nilotinib in Ph+ CML pediatric patients that are newly diagnosed or resistant or intolerant to imatinib or dasatinib or refractory or relapsed Ph+ ALL compared to the adult populations. It will also evaluate safety and activity of nilotinib as secondary objectives.

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  • Sorafenib (BAY 43-9006) to Treat Children With Solid Tumors or Leukemias Not Recruiting

    Background: - Sorafenib is an experimental anti-cancer drug that works by blocking proteins thought to be important for tumor growth. It has blocked the growth of tumors in test tubes and in some animal models. - Sorafenib is approved for the treatment of advanced kidney cancer. - This is the first time sorafenib is being tested in children with cancer. Objectives: - To determine the highest dose of sorafenib that can be safely given to children and young adults with cancer. - To determine the side effects and benefits, if any, of sorafenib in children and young adults with cancer. - To study how the body handles sorafenib and the drug's effects on cells and proteins in the blood. Eligibility: -Patients between 2 and 21 years of age with solid tumors or leukemias that do not respond to standard treatment. Patients between 2 and 21 years of age with AML and FLT3-ITD mutation for Part C of the study. Design: - Patients take sorafenib tablets every day about every 12 hours in 28-day treatment cycles for a maximum of 24 cycles. - The dose is increased in succeeding groups of 3 to 6 children until serious side effects occur. Subsequent patients then receive the drug at lower doses. - Patients have a physical exam, blood and urine tests, and CT or MRI scans periodically to monitor safety and treatment effects. Leukemia patients also have bone marrow aspirates. Patients with a solid tumor may have an MRI. Children whose bones are still growing have X-rays of the lower legs periodically to monitor bone structure. - Patients have additional blood studies to determine the amount of sorafenib in the blood, the effect of the drug on proteins and cells in the blood, and genetic differences that affect how individuals respond to the drug.

    Stanford is currently not accepting patients for this trial. For more information, please contact Jennifer Lew, (650) 725 - 4318.

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  • A Study of Clofarabine in Combination With Etoposide and Cyclophosphamide in Children With Acute Leukemias. Not Recruiting

    Clofarabine (injection) is approved by the Food and Drug Administration (FDA) for the treatment of pediatric patients 1 to 21 years old with relapsed or refractory acute lymphoblastic leukemia (ALL) who have had at least 2 prior treatment regimens. This use is based on the induction of complete responses. Randomized trials demonstrating increased survival or other clinical benefit have not been conducted. The purpose of the phase 1 portion of this study was to determine if clofarabine added to a combination of etoposide and cyclophosphamide is safe in children with relapsed or refractory acute lymphoblastic leukemia (ALL) or acute myelogenous leukemia (AML). The purpose of the phase 2 portion of the study was to measure the effectiveness of the combination therapy in children with ALL.

    Stanford is currently not accepting patients for this trial. For more information, please contact Min Wang, (650) 736 - 4281.

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  • Genome, Proteome and Tissue Microarray in Childhood Acute Leukemia Recruiting

    We will study gene and protein expression in leukemia cells of children diagnosed with acute leukemia. We hope to identify genes or proteins which can help us grade leukemia at diagnosis in order to: (a) develop better means of diagnosis and (b) more accurately choose the best therapy for each patient.

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Teaching

2013-14 Courses


Publications

Journal Articles


  • Development and validation of a single-cell network profiling assay-based classifier to predict response to induction therapy in paediatric patients with de novo acute myeloid leukaemia: a report from the Children's Oncology Group BRITISH JOURNAL OF HAEMATOLOGY Lacayo, N. J., Alonzo, T. A., Gayko, U., Rosen, D. B., Westfall, M., Purvis, N., Putta, S., Louie, B., Hackett, J., Cohen, A. C., Cesano, A., Gerbing, R., Ravindranath, Y., Dahl, G. V., Gamis, A., Meshinchi, S. 2013; 162 (2): 250-262

    Abstract

    Single cell network profiling (SCNP) is a multi-parameter flow cytometry technique for simultaneous interrogation of intracellular signalling pathways. Diagnostic paediatric acute myeloid leukaemia (AML) bone marrow samples were used to develop a classifier for response to induction therapy in 53 samples and validated in an independent set of 68 samples. The area under the curve of a receiver operating characteristic curve (AUCROC ) was calculated to be 0·85 in the training set and after exclusion of induction deaths, the AUCROC of the classifier was 0·70 (P = 0·02) and 0·67 (P = 0·04) in the validation set when induction deaths (intent to treat) were included. The highest predictive accuracy was noted in the cytogenetic intermediate risk patients (AUCROC 0·88, P = 0·002), a subgroup that lacks prognostic/predictive biomarkers for induction response. Only white blood cell count and cytogenetic risk were associated with response to induction therapy in the validation set. After controlling for these variables, the SCNP classifier score was associated with complete remission (P = 0·017), indicating that the classifier provides information independent of other clinical variables that were jointly associated with response. This is the first validation of an SCNP classifier to predict response to induction chemotherapy. Herein we demonstrate the usefulness of quantitative SCNP under modulated conditions to provide independent information on AML disease biology and induction response.

    View details for DOI 10.1111/bjh.12370

    View details for Web of Science ID 000321211300012

    View details for PubMedID 23682827

  • Prognostic features in acute megakaryoblastic leukemia in children without Down syndrome: a report from the AML02 multicenter trial and the Children's Oncology Group Study POG 9421 LEUKEMIA O'Brien, M. M., Cao, X., Pounds, S., Dahl, G. V., Raimondi, S. C., Lacayo, N. J., Taub, J., Chang, M., Weinstein, H. J., Ravindranath, Y., Inaba, H., Campana, D., Pui, C. H., Rubnitz, J. E. 2013; 27 (3): 731-734

    View details for DOI 10.1038/leu.2012.223

    View details for Web of Science ID 000316587300031

    View details for PubMedID 22918081

  • AKT Signaling as a Novel Factor Associated with In Vitro Resistance of Human AML to Gemtuzumab Ozogamicin PLOS ONE Rosen, D. B., Harrington, K. H., Cordeiro, J. A., Leung, L. Y., Putta, S., Lacayo, N., Laszlo, G. S., Gudgeon, C. J., Hogge, D. E., Hawtin, R. E., Cesano, A., Walter, R. B. 2013; 8 (1)

    Abstract

    Gemtuzumab ozogamicin (GO), an immunoconjugate between an anti-CD33 antibody and a calicheamicin-?(1) derivative, induces remissions and improves survival in a subset of patients with acute myeloid leukemia (AML). As the mechanisms underlying GO and calicheamicin-?(1) resistance are incompletely understood, we herein used flow cytometry-based single cell network profiling (SCNP) assays to study cellular responses of primary human AML cells to GO. Our data indicate that the extent of DNA damage is quantitatively impacted by CD33 expression and drug efflux activity. However, although DNA damage is required for GO-induced cytotoxicity, it is not sufficient for effective cell kill, suggesting that downstream anti-apoptotic pathways may function as relevant resistance mechanisms. Supporting this notion, we found activated PI3K/AKT signaling to be associated with GO resistance in vitro in primary AML cells. Consistently, the investigational AKT inhibitor MK-2206 significantly sensitized various human AML cells to GO or free calicheamicin-?(1) with particularly pronounced effects in otherwise GO or free calicheamicin-?(1)-resistant cells. Likewise, MK-2206 also sensitized primary AML cells to calicheamicin-?(1). Together, our findings illustrate the capacity of SCNP assays to discover chemotherapy-related biological pathways and signaling networks relevant to GO-induced genotoxic stress. The identification of AKT signaling as being associated with GO resistance in vitro may provide a novel approach to improve the in vivo efficacy of GO/calicheamicin-?(1) and, by extrapolation, other DNA damage-based therapeutics.

    View details for DOI 10.1371/journal.pone.0053518

    View details for Web of Science ID 000313429800056

    View details for PubMedID 23320091

  • Massive evolution of the immunoglobulin heavy chain locus in children with B precursor acute lymphoblastic leukemia BLOOD Gawad, C., Pepin, F., Carlton, V. E., Klinger, M., Logan, A. C., Miklos, D. B., Faham, M., Dahl, G., Lacayo, N. 2012; 120 (22): 4407-4417

    Abstract

    The ability to distinguish clonal B-cell populations based on the sequence of their rearranged immunoglobulin heavy chain (IgH) locus is an important tool for diagnosing B-cell neoplasms and monitoring treatment response. Leukemic precursor B cells may continue to undergo recombination of the IgH gene after malignant transformation; however, the magnitude of evolution at the IgH locus is currently unknown. We used next-generation sequencing to characterize the repertoire of IgH sequences in diagnostic samples of 51 children with B precursor acute lymphoblastic leukemia (B-ALL). We identified clonal IgH rearrangements in 43 of 51 (84%) cases and found that the number of evolved IgH sequences per patient ranged dramatically from 0 to 4024. We demonstrate that the evolved IgH sequences are not the result of amplification artifacts and are unique to leukemic precursor B cells. In addition, the evolution often follows an allelic exclusion pattern, where only 1 of 2 rearranged IgH loci exhibit ongoing recombination. Thus, precursor B-cell leukemias maintain evolution at the IgH locus at levels that were previously underappreciated. This finding sheds light on the mechanisms associated with leukemic clonal evolution and may fundamentally change approaches for monitoring minimal residual disease burden.

    View details for DOI 10.1182/blood-2012-05-429811

    View details for Web of Science ID 000313111300023

    View details for PubMedID 22932801

  • Assessing signaling pathways associated with in vitro resistance to cytotoxic agents in AML LEUKEMIA RESEARCH Rosen, D. B., Cordeiro, J. A., Cohen, A., Lacayo, N., Hogge, D., Hawtin, R. E., Cesano, A. 2012; 36 (7): 900-904

    Abstract

    This study uses single cell network profiling (SCNP) to characterize biological pathways associated with in vitro resistance or sensitivity to chemotherapeutics commonly used in acute myeloid leukemia (AML) (i.e. cytarabine/daunorubicin, gemtuzumab ozogamicin (GO), decitabine, azacitidine, clofarabine). Simultaneous measurements at the single cell level of changes in DNA damage, apoptosis and signaling pathway responses in AML blasts incubated in vitro with the above drugs showed distinct profiles for each sample and mechanistically different profiles between distinct classes of agents. Studies are ongoing to assess the clinical predictive value of these findings.

    View details for DOI 10.1016/j.leukres.2012.02.022

    View details for Web of Science ID 000304353400030

    View details for PubMedID 22521550

  • Circular RNAs Are the Predominant Transcript Isoform from Hundreds of Human Genes in Diverse Cell Types PLOS ONE Salzman, J., Gawad, C., Wang, P. L., Lacayo, N., Brown, P. O. 2012; 7 (2)

    Abstract

    Most human pre-mRNAs are spliced into linear molecules that retain the exon order defined by the genomic sequence. By deep sequencing of RNA from a variety of normal and malignant human cells, we found RNA transcripts from many human genes in which the exons were arranged in a non-canonical order. Statistical estimates and biochemical assays provided strong evidence that a substantial fraction of the spliced transcripts from hundreds of genes are circular RNAs. Our results suggest that a non-canonical mode of RNA splicing, resulting in a circular RNA isoform, is a general feature of the gene expression program in human cells.

    View details for DOI 10.1371/journal.pone.0030733

    View details for Web of Science ID 000301977500016

    View details for PubMedID 22319583

  • Dorsolateral Midbrain MRI Abnormalities and Ocular Motor Deficits Following Cytarabine-Based Chemotherapy for Acute Myelogenous Leukemia JOURNAL OF NEURO-OPHTHALMOLOGY Doan, T., Lacayo, N., Fisher, P. G., Liao, Y. J. 2011; 31 (1): 52-53

    View details for DOI 10.1097/WNO.0b013e3181e91174

    View details for Web of Science ID 000287238700013

    View details for PubMedID 20881617

  • A pilot study of an online cognitive rehabilitation program for executive function skills in children with cancer-related brain injury BRAIN INJURY Kesler, S. R., Lacayo, N. J., Jo, B. 2011; 25 (1): 101-112

    Abstract

    Children with a history of cancer are at increased risk for cognitive impairments, particularly in executive and memory domains. Traditional, in-person cognitive rehabilitation strategies may be unavailable and/or impractical for many of these children given difficulties related to resources and health status. The feasibility and efficacy of implementing a computerized, home-based cognitive rehabilitation curriculum designed to improve executive function skills was examined in these children.A one-arm open trial pilot study of an original executive function cognitive rehabilitation curriculum was conducted with 23 paediatric cancer survivors aged 7-19.Compliance with the cognitive rehabilitation program was 83%, similar to that of many traditional programs. Following the cognitive intervention, participants showed significantly increased processing speed, cognitive flexibility, verbal and visual declarative memory scores as well as significantly increased pre-frontal cortex activation compared to baseline.These results suggest that a program of computerized cognitive exercises can be successfully implemented at home in young children with cancer. These exercises may be effective for improving executive and memory skills in this group, with concurrent changes in neurobiologic status.

    View details for DOI 10.3109/02699052.2010.536194

    View details for Web of Science ID 000288101700011

    View details for PubMedID 21142826

  • Minimal residual disease-directed therapy for childhood acute myeloid leukaemia: results of the AML02 multicentre trial LANCET ONCOLOGY Rubnitz, J. E., Inaba, H., Dahl, G., Ribeiro, R. C., Bowman, W. P., Taub, J., Pounds, S., Razzouk, B. I., Lacayo, N. J., Cao, X., Meshinchi, S., Degar, B., Airewele, G., Raimondi, S. C., Onciu, M., Coustan-Smith, E., Downing, J. R., Leung, W., Pui, C., Campana, D. 2010; 11 (6): 543-552

    Abstract

    We sought to improve outcome in patients with childhood acute myeloid leukaemia (AML) by applying risk-directed therapy that was based on genetic abnormalities of the leukaemic cells and measurements of minimal residual disease (MRD) done by flow cytometry during treatment.From Oct 13, 2002, to June 19, 2008, 232 patients with de-novo AML (n=206), therapy-related or myelodysplasia-related AML (n=12), or mixed-lineage leukaemia (n=14) were enrolled at eight centres. 230 patients were assigned by block, non-blinded randomisation, stratified by cytogenetic or morphological subtype, to high-dose (18 g/m(2), n=113) or low-dose (2 g/m(2), n=117) cytarabine given with daunorubicin and etoposide (ADE; induction 1). The primary aim of the study was to compare the incidence of MRD positivity of the high-dose group and the low-dose group at day 22 of induction 1. Induction 2 consisted of ADE with or without gemtuzumab ozogamicin (GO anti-CD33 monoclonal antibody); consolidation therapy included three additional courses of chemotherapy or haematopoietic stem-cell transplantation (HSCT). Levels of MRD were used to allocate GO and to determine the timing of induction 2. Both MRD and genetic abnormalities at diagnosis were used to determine the final risk classification. Low-risk patients (n=68) received five courses of chemotherapy, whereas high-risk patients (n=79), and standard-risk patients (n=69) with matched sibling donors, were eligible for HSCT (done for 48 high-risk and eight standard-risk patients). All 230 randomised patients were analysed for the primary endpoint. Other analyses were limited to the 216 patients with AML, excluding those with mixed-lineage leukaemia. This trial is closed to accrual and is registered with ClinicalTrials.gov, number NCT00136084.Complete remission was achieved in 80% (173 of 216 patients) after induction 1 and 94% (203 of 216) after induction 2. Induction failures included two deaths from toxic effects and ten cases of resistant leukaemia. The introduction of high-dose versus low-dose cytarabine did not significantly lower the rate of MRD-positivity after induction 1 (34%vs 42%, p=0.17). The 6-month cumulative incidence of grade 3 or higher infection was 79.3% (SE 4.0) for patients in the high-dose group and 75.5% (4.2) for the low-dose group. 3-year event-free survival and overall survival were 63.0% (SE 4.1) and 71.1% (3.8), respectively. 80% (155 of 193) of patients achieved MRD of less than 0.1% after induction 2, and the cumulative incidence of relapse for this group was 17% (SE 3). MRD of 1% or higher after induction 1 was the only significant independent adverse prognostic factor for both event-free (hazard ratio 2.41, 95% CI 1.36-4.26; p=0.003) and overall survival (2.11, 1.09-4.11; p=0.028).Our findings suggest that the use of targeted chemotherapy and HSCT, in the context of a comprehensive risk-stratification strategy based on genetic features and MRD findings, can improve outcome in patients with childhood AML.National Institutes of Health and American Lebanese Syrian Associated Charities (ALSAC).

    View details for DOI 10.1016/S1470-2045(10)70090-5

    View details for Web of Science ID 000279019500026

    View details for PubMedID 20451454

  • Phase I Study of Valspodar (PSC-833) With Mitoxantrone and Etoposide in Refractory and Relapsed Pediatric Acute Leukemia: A Report From the Children's Oncology Group PEDIATRIC BLOOD & CANCER O'Brien, M. M., Lacayo, N. J., Lum, B. L., Kshirsagar, S., Buck, S., Ravindranath, Y., Bernstein, M., Weinstein, H., Chang, M. N., Arceci, R. J., Sikic, B. I., Dahl, G. V. 2010; 54 (5): 694-702

    Abstract

    Valspodar, a non-immunosuppressive analog of cylosporine, is a potent P-glycoprotein (MDR1) inhibitor. As MDR1-mediated efflux of chemotherapeutic agents from leukemic blasts may contribute to drug resistance, a phase 1 study of valspodar combined with mitoxantrone and etoposide in pediatric patients with relapsed or refractory leukemias was performed.Patients received a valspodar-loading dose (2 mg/kg) followed by a 5-day continuous valspodar infusion (8, 10, 12.5, or 15 mg/kg/day) combined with lower than standard doses of mitoxantrone and etoposide. The valspodar dose was escalated using a standard 3 + 3 phase I design.Twenty-one patients were evaluable for toxicity and 20 for response. The maximum tolerated dose (MTD) of valspodar was 12.5 mg/kg/day, combined with 50% dose-reduced mitoxantrone and etoposide. The clearance of mitoxantrone and etoposide was decreased by 64% and 60%, respectively, when combined with valspodar. Dose-limiting toxicities included stomatitis, ataxia, and bone marrow aplasia. Three of 11 patients with acute lymphoblastic leukemia (ALL) had complete responses while no patient with acute myeloid leukemia (AML) had an objective response. In vitro studies demonstrated P-glycoprotein expression on the blasts of 5 of 14 patients, although only 1 had inhibition of rhodamine efflux by valspodar.While this regimen was tolerable, responses in this heavily pretreated population were limited to a subset of patients with ALL.

    View details for DOI 10.1002/pbc.22366

    View details for Web of Science ID 000275935700009

    View details for PubMedID 20209646

  • Prevalence and prognostic significance of KIT mutations in pediatric patients with core binding factor AML enrolled on serial pediatric cooperative trials for de novo AML BLOOD Pollard, J. A., Alonzo, T. A., Gerbing, R. B., Ho, P. A., Zeng, R., Ravindranath, Y., Dahl, G., Lacayo, N. J., Becton, D., Chang, M., Weinstein, H. J., Hirsch, B., Raimondi, S. C., Heerema, N. A., Woods, W. G., Lange, B. J., Hurwitz, C., Arceci, R. J., Radich, J. P., Bernstein, I. D., Heinrich, M. C., Meshinchi, S. 2010; 115 (12): 2372-2379

    Abstract

    KIT receptor tyrosine kinase mutations are implicated as a prognostic factor in adults with core binding factor (CBF) acute myeloid leukemia (AML). However, their prevalence and prognostic significance in pediatric CBF AML is not well established. We performed KIT mutational analysis (exon 8 and exon 17) on diagnostic specimens from 203 pediatric patients with CBF AML enrolled on 4 pediatric AML protocols. KIT mutations were detected in 38 (19%) of 203 (95% CI, 14%-25%) patient samples of which 20 (52.5%) of 38 (95% CI, 36%-69%) involved exon 8, 17 (45%) of 38 (95% CI, 29%-62%) involved exon 17, and 1 (2.5%; 95% CI, 0%-14%) involved both locations. Patients with KIT mutations had a 5-year event-free survival of 55% (+/- 17%) compared with 59% (+/- 9%) for patients with wild-type KIT (P = .86). Rates of complete remission, overall survival, disease-free survival, or relapse were not significantly different for patients with or without KIT mutations. Location of the KIT mutation and analysis by cytogenetic subtype [t(8;21) vs inv(16)] also lacked prognostic significance. Our study shows that KIT mutations lack prognostic significance in a large series of pediatric patients with CBF AML. This finding, which differs from adult series and a previously published pediatric study, may reflect variations in therapeutic approaches and/or biologic heterogeneity within CBF AML. Two of 4 studies included in this analysis are registered at http://clinicaltrials.gov as NCT00002798 (CCG-2961) and NCT00070174 (COG AAML03P1).

    View details for DOI 10.1182/blood-2009-09-241075

    View details for Web of Science ID 000275981900010

    View details for PubMedID 20056794

  • WT1 Expression at Diagnosis Does Not Predict Survival in Pediatric AML: A Report From the Children's Oncology Group PEDIATRIC BLOOD & CANCER Noronha, S. A., Farrar, J. E., Alonzo, T. A., Gerbing, R. B., Lacayo, N. J., Dahl, G. V., Ravindranath, Y., Arceci, R. J., Loeb, D. M. 2009; 53 (6): 1136-1139

    Abstract

    WT1 is a transcription factor that is aberrantly overexpressed in acute and chronic leukemias. Overexpression of WT1 in pediatric acute myeloid leukemia has been reported, but the prognostic significance is unclear because sample sizes in these studies have been relatively small. WT1 expression was measured by quantitative RT-PCR in samples obtained at diagnosis from 155 pediatric AML patients treated on a cooperative group protocol. Neither overall survival nor event-free survival was correlated with WT1 expression.

    View details for DOI 10.1002/pbc.22142

    View details for Web of Science ID 000270440900043

    View details for PubMedID 19618455

  • Speeding the Flow Toward Personalized Therapy in Childhood Acute Leukemia PEDIATRIC BLOOD & CANCER Simonds, E. F., Davis, K. L., Lacayo, N. J. 2009; 53 (4): 525-526

    View details for DOI 10.1002/pbc.22180

    View details for Web of Science ID 000269295500001

    View details for PubMedID 19642213

  • Molecular inversion probes reveal patterns of 9p21 deletion and copy number aberrations in childhood leukemia CANCER GENETICS AND CYTOGENETICS Schiffman, J. D., Wang, Y., McPherson, L. A., Welch, K., Zhang, N., Davis, R., Lacayo, N. J., Dahl, G. V., Faham, M., Ford, J. M., Ji, H. P. 2009; 193 (1): 9-18

    Abstract

    Childhood leukemia, which accounts for >30% of newly diagnosed childhood malignancies, is one of the leading causes of death for children with cancer. Genome-wide studies using microarray chips to identify copy number changes in human cancer are becoming more common. In this pilot study, 45 pediatric leukemia samples were analyzed for gene copy aberrations using novel molecular inversion probe (MIP) technology. Acute leukemia subtypes included precursor B-cell acute lymphoblastic leukemia (ALL) (n=23), precursor T-cell ALL (n=6), and acute myeloid leukemia (n=14). The MIP analysis identified 69 regions of recurring copy number changes, of which 41 have not been identified with other DNA microarray platforms. Copy number gains and losses were validated in 98% of clinical karyotypes and 100% of fluorescence in situ hybridization studies available. We report unique patterns of copy number loss in samples with 9p21.3 (CDKN2A) deletion in the precursor B-cell ALL patients, compared with the precursor T-cell ALL patients. MIPs represent an attractive technology for identifying novel copy number aberrations, validating previously reported copy number changes, and translating molecular findings into clinically relevant targets for further investigation.

    View details for DOI 10.1016/j.cancergencyto.2009.03.005

    View details for Web of Science ID 000268922900002

    View details for PubMedID 19602459

  • Genomics of childhood leukemias: The virtue of complexity JOURNAL OF CLINICAL ONCOLOGY Sikic, B. I., Tibshirani, R., Lacayo, N. J. 2008; 26 (27): 4367-4368

    View details for DOI 10.1200/JCO.2008.16.4285

    View details for Web of Science ID 000259350700002

    View details for PubMedID 18802145

  • Tissue microarrays from bone marrow aspirates for high-throughput assessment of immunohistologic markers in pediatric acute leukemia PEDIATRIC AND DEVELOPMENTAL PATHOLOGY Hazard, F. K., Zhao, S., Schiffman, J. D., Lacayo, N. J., Dahl, G. V., Natkunam, Y. 2008; 11 (4): 283-290

    Abstract

    Gene expression profiling studies have been employed to investigate prognostic subgroups in pediatric acute leukemia. Tissue microarrays (TMAs) are useful for high-throughput analysis of protein expression of target genes in acute leukemia samples and for validation of gene microarray analysis. Using cryopreserved samples of pediatric acute leukemia bone marrow aspirates, we constructed TMA from as few as 1 million cells. Bone marrow core biopsies from the same patients were included on the same TMA for comparison. A panel of 15 immunohistochemical markers typically used for diagnosis as well as those targeting recently characterized, prognostically relevant molecules of interest in pediatric acute leukemia was used to evaluate protein expression. Staining results confirm that suspension cells from bone marrow aspirates can be effectively used to derive protein expression data from multiple cases simultaneously with comparable efficacy to that of biopsy tissue. This method allows for new markers of diagnostic, prognostic, or therapeutic importance to be screened on large numbers of study patients. Furthermore, this technique may facilitate the inclusion of small samples, aspirates, and body fluids in large-scale studies of protein expression in clinical trials and protocols in which tissue biopsies are often unavailable.

    View details for DOI 10.2350/07-04-0253.1

    View details for Web of Science ID 000259353300005

    View details for PubMedID 17990919

  • Acute leukemia in children DM DISEASE-A-MONTH O'Brien, M. M., Lacayo, N. J. 2008; 54 (4): 202-225
  • The incidence and clinical significance of nucleophosmin mutations in childhood AML BLOOD Brown, P., McIntyre, E., Rau, R., Meshinchi, S., Lacayo, N., Dahl, G., Alonzo, T. A., Chang, M., Arceci, R. J., Small, D. 2007; 110 (3): 979-985

    Abstract

    Frameshift mutations in exon 12 of the nucleophosmin gene (NPM1) result in aberrant cytoplasmic localization of the NPM protein (NPMc(+)) and occur in 25% to 35% of adult acute myeloid leukemia (AML). In adults with AML, NPMc(+) has been associated with normal karyotype, FLT3/ITD mutations, high remission induction rates, and improved survival (particularly in patients lacking FLT3/ITD). NPMc(+) has not been well characterized in childhood AML. This study examines the incidence and clinical significance of NPMc(+) in 295 children with newly diagnosed AML treated on a large cooperative group clinical trial (POG-9421). We find that NPMc(+) is relatively uncommon in childhood AML (23 of 295 patients, 8%); and is significantly associated with FLT3/ITD mutations (P = .046), female sex (P = .029), older age (P = .047), and normal cytogenetics (P < .001). There is a favorable impact of NPMc(+) on survival in children lacking FLT3/ITD (5-year EFS, 69% vs 35%; hazard ratio, 0.39; P = .051), which is similar in magnitude to the favorable impact of t(8;21) and inv(16). We conclude that NPMc(+) is relatively rare in childhood AML, particularly in younger children. NPMc(+) does not abrogate the negative prognostic influence of FLT3/ITD mutations, but may contribute to risk stratification in children who lack FLT3/ITD mutations by identifying a group with superior prognosis.

    View details for DOI 10.1182/blood-2007-02-076604

    View details for Web of Science ID 000248514700035

    View details for PubMedID 17440048

  • Differential gene expression patterns and interaction networks in BCR-ABL-positive and -negative adult acute lymphoblastic leukemias JOURNAL OF CLINICAL ONCOLOGY Juric, D., Lacayo, N. J., Ramsey, M. C., Racevskis, J., Wiernik, P. H., Rowe, J. M., Goldstone, A. H., O'Dwyer, P. J., Paietta, E., Sikic, B. I. 2007; 25 (11): 1341-1349

    Abstract

    To identify gene expression patterns and interaction networks related to BCR-ABL status and clinical outcome in adults with acute lymphoblastic leukemia (ALL).DNA microarrays were used to profile a set of 54 adult ALL specimens from the Medical Research Council UKALL XII/Eastern Cooperative Oncology Group E2993 trial (21 p185BCR-ABL-positive, 16 p210BCR-ABL-positive and 17 BCR-ABL-negative specimens).Using supervised and unsupervised analysis tools, we detected significant transcriptomic changes in BCR-ABL-positive versus -negative specimens, and assessed their validity in an independent cohort of 128 adult ALL specimens. This set of 271 differentially expressed genes (including GAB1, CIITA, XBP1, CD83, SERPINB9, PTP4A3, NOV, LOX, CTNND1, BAALC, and RAB21) is enriched for genes involved in cell death, cellular growth and proliferation, and hematologic system development and function. Network analysis demonstrated complex interaction patterns of these genes, and identified FYN and IL15 as the hubs of the top-scoring network. Within the BCR-ABL-positive subgroups, we identified genes overexpressed (PILRB, STS-1, SPRY1) or underexpressed (TSPAN16, ADAMTSL4) in p185BCR-ABL-positive ALL relative to p210BCR-ABL-positive ALL. Finally, we constructed a gene expression- and interaction-based outcome predictor consisting of 27 genes (including GRB2, GAB1, GLI1, IRS1, RUNX2, and SPP1), which correlated with overall survival in BCR-ABL-positive adult ALL (P = .0001), independent of age (P = .25) and WBC count at presentation (P = .003).We identified prominent molecular features of BCR-ABL-positive adult ALL, which may be useful for developing novel therapeutic targets and prognostic markers in this disease.

    View details for DOI 10.1200/JCO.2006.09.3534

    View details for Web of Science ID 000245851900009

    View details for PubMedID 17312329

  • CpG island methylator phenotype and childhood leukemia CLINICAL CANCER RESEARCH Lacayo, N. J., Di Martino, J. F., Wei, M. C., Dahl, G. V. 2006; 12 (16): 4787-4789
  • Low or absent SPARC expression in acute myeloid leukemia with MLL rearrangements is associated with sensitivity to growth inhibition by exogenous SPARC protein LEUKEMIA DiMartino, J. F., Lacayo, N. J., Varadi, M., Li, L., Saraiya, C., Ravindranath, Y., Yu, R., Sikic, B., Raimondi, S. C., Dahl, G. 2006; 20 (3): 426-432

    Abstract

    Secreted protein, acidic and rich in cysteine (SPARC), is a matricellular glycoprotein with growth-inhibitory and antiangiogenic functions. Although SPARC has been implicated as a tumor suppressor in humans, its function in normal or malignant hematopoiesis has not previously been studied. We found that the leukemic cells of AML patients with MLL gene rearrangements express low to undetectable amounts of SPARC whereas normal hematopoietic progenitors and most AML patients express this gene. SPARC RNA and protein levels were also low or undetectable in AML cell lines with MLL translocations. Consistent with its tumor suppressive effects in various solid tumor models, exogenous SPARC protein selectively reduced the growth of cell lines with MLL rearrangements by inhibiting cell cycle progression from G1 to S phase. The lack of SPARC expression in MLL-rearranged cell lines was associated with dense promoter methylation. However, we found no evidence of methylation-based silencing of SPARC in primary patient samples. Our results suggest that low or absent SPARC expression is a consistent feature of AML cells with MLL rearrangements and that SPARC may function as a tumor suppressor in this subset of patients. A potential role of exogenous SPARC in the therapy of MLL-rearranged AML warrants further investigation.

    View details for DOI 10.1038/sj.leu.2404102

    View details for Web of Science ID 000235537800007

    View details for PubMedID 16424866

  • Randomized use of cyclosporin A (CsA) to modulate P-glycoprotein in children with AML in remission: Pediatric Oncology Group Study 9421 BLOOD Becton, D., Dahl, G. V., Ravindranath, Y., Chang, M. N., Behm, F. G., Raimondi, S. C., Head, D. R., Stine, K. C., Lacayo, N. J., Sikic, B. I., Arceci, R. J., Weinstein, H. 2006; 107 (4): 1315-1324

    Abstract

    Relapse is a major obstacle in the cure of acute myeloid leukemia (AML). The Pediatric Oncology Group AML Study 9421 tested 2 different strategies to improve event-free survival (EFS) and overall survival (OS). Patients were randomized to receive standard-dose DAT (daunorubicin, cytarabine, and thioguanine) or high-dose DAT during induction. To interfere with P-glycoprotein (P-gp)-dependent drug efflux, the second randomization tested the benefit of cyclosporine (CsA) added to consolidation chemotherapy. Of the 282 children randomly assigned to receive standard DAT induction, 248 (87.9%) achieved remission compared to 253 (91%) of the 278 receiving high-dose DAT (P = ns). Children with HLA-identical sibling donors who achieved a complete remission received an allogeneic bone marrow transplant as consolidation. For the 83 patients receiving a matched related donor bone marrow transplantation (BMT), the 3-year disease-free survival (DFS) is 67%. Of the 418 children who achieved remission and went on to consolidation with and without CsA, the DFS was 40.6% and 33.9%, respectively (P = .24). Overexpression of P-gp was infrequent (14%) in this pediatric population. In this study, intensifying induction with high-dose DAT and the addition of CsA to consolidation chemotherapy did not prolong the durations of remission or improve overall survival for children with AML.

    View details for DOI 10.1128/blood-2004-08-3218

    View details for Web of Science ID 000235296100018

    View details for PubMedID 16254147

  • Gene expression profiles at diagnosis in de novo childhood AML patients identify FLT3 mutations with good clinical outcomes BLOOD Lacayo, N. J., Meshinchi, S., Kinnunen, P., Yu, R., Wang, Y., Stuber, C. M., Douglas, L., Wahab, R., Becton, D. L., Weinstein, H., Chang, M. N., Willman, C. L., Radich, J. P., Tibshirani, R., Ravindranath, Y., Sikic, B. I., Dahl, G. V. 2004; 104 (9): 2646-2654

    Abstract

    Fms-like tyrosine kinase 3 (FLT3) mutations are associated with unfavorable outcomes in children with acute myeloid leukemia (AML). We used DNA microarrays to identify gene expression profiles related to FLT3 status and outcome in childhood AML. Among 81 diagnostic specimens, 36 had FLT3 mutations (FLT3-MUs), 24 with internal tandem duplications (ITDs) and 12 with activating loop mutations (ALMs). In addition, 8 of 19 specimens from patients with relapses had FLT3-MUs. Predictive analysis of microarrays (PAM) identified genes that differentiated FLT3-ITD from FLT3-ALM and FLT3 wild-type (FLT3-WT) cases. Among the 42 specimens with FLT3-MUs, PAM identified 128 genes that correlated with clinical outcome. Event-free survival (EFS) in FLT3-MU patients with a favorable signature was 45% versus 5% for those with an unfavorable signature (P = .018). Among FLT3-MU specimens, high expression of the RUNX3 gene and low expression of the ATRX gene were associated with inferior outcome. The ratio of RUNX3 to ATRX expression was used to classify FLT3-MU cases into 3 EFS groups: 70%, 37%, and 0% for low, intermediate, and high ratios, respectively (P < .0001). Thus, gene expression profiling identified AML patients with divergent prognoses within the FLT3-MU group, and the RUNX3 to ATRX expression ratio should be a useful prognostic indicator in these patients.

    View details for DOI 10.1182/blood-2004-12-4449

    View details for Web of Science ID 000224795700014

    View details for PubMedID 15251987

  • Modulation of resistance to idarubicin by the cyclosporin PSC 833 (valspodar) in multidrug-resistant cells. Journal of experimental therapeutics & oncology Lacayo, N. J., Duran, G. E., Sikic, B. I. 2003; 3 (3): 127-135

    Abstract

    Idarubicin (IDA) is an anthracycline anticancer drug utilized in the treatment of acute leukemias. There are conflicting data published with regard to the cross-resistance of IDA in multidrug-resistant (MDR) cells expressing P-glycoprotein (P-gp). We evaluated the cytotoxicity and cellular accumulation of IDA in a panel of anthracycline-selected MDR cell lines. Leukemia K562/R7 cells and sarcoma MES-SA/Dx5 cells expressing high levels of the MDR1 (ABCB1) gene were resistant to IDA (42-fold and 150-fold, respectively). In both of these cell lines, resistance to IDA was equivalent to that for doxorubicin, the drug used to select for the MDR variants. The P-gp inhibitor PSC 833 (valspodar) at 2 microM completely restored sensitivity to IDA. IDA accumulation was decreased 12-fold in MES-SA/Dx5 cells vs parental cell line, and drug uptake was restored to control levels by PSC 833. Reduced intracellular IDA was correlated with P-gp content by flow cytometry. Experiments in NIH3T3 murine cells transfected with the human MDR1 gene substantiated the findings of cross-resistance to IDA and reversal of resistance by PSC 833. Our data indicate that IDA is a high-affinity substrate for P-gp.

    View details for PubMedID 14641819

  • Preferential expression of a mutant allele of the amplified MDR1 (ABCB1) gene in drug-resistant variants of a human sarcoma GENES CHROMOSOMES & CANCER Chen, G. K., Lacayo, N. J., Duran, G. E., Wang, Y., Bangs, C. D., Rea, S., Kovacs, M., Cherry, A. M., Brown, J. M., Sikic, B. I. 2002; 34 (4): 372-383

    Abstract

    Activation of the MDR1 (ABCB1) gene is a common event conferring multidrug resistance (MDR) in human cancers. We investigated MDR1 activation in MDR variants of a human sarcoma line, some of which express a mutant MDR1, which facilitated the study of allelic gene expression. Structural alterations of MDR1, gene copy numbers, and allelic expression were analyzed by cytogenetic karyotyping, oligonucleotide hybridization, Southern blotting, polymerase chain reaction, and DNA heteroduplex assays. Both chromosome 7 alterations and several cytogenetic changes involving the 7q21 locus are associated with the development of MDR in these sarcoma cells. Multistep-selected cells and their revertants contain three- to six-fold MDR1 gene amplification compared with that of the drug-sensitive parental cell line MES-SA and single-step doxorubicin-selected mutants. MDR1 gene amplification precedes the emergence of a mutant allele in cells that were coselected with doxorubicin and a cyclosporin inhibitor of P-glycoprotein (P-gp). Allele-specific oligonucleotide hybridization showed that the endogenous mutant allele was present as a single copy, with multiple copies of the normal allele. Reselection of revertant cells with doxorubicin in either the presence or the absence of the P-gp inhibitor resulted in exclusive reexpression of the mutant MDR1 allele, regardless of the presence of multiple wild-type MDR1 alleles. These data provide new insights into how multiple alleles are regulated in the amplicon of drug-resistant cancer cells and indicate that increased expression of an amplified gene can result from selective transcription of a single mutant allele of the gene.

    View details for DOI 10.1002/gcc.10067

    View details for Web of Science ID 000176495400004

    View details for PubMedID 12112526

  • Pharmacokinetic interactions of cyclosporine with etoposide and mitoxantrone in children with acute myeloid leukemia LEUKEMIA Lacayo, N. J., Lum, B. L., Becton, D. L., Weinstein, H., Ravindranath, Y., Chang, M. N., Bomgaars, L., Lauer, S. J., Sikic, B. I., Dahl, G. V. 2002; 16 (5): 920-927

    Abstract

    The purpose of this study was to assess the effect of the multidrug resistance modulator cyclosporine (CsA) on the pharmacokinetics of etoposide and mitoxantrone in children with de novo acute myeloid leukemia (AML). Serial blood samples for pharmacokinetic studies were obtained in 38 children over a 24-h period following cytotoxin treatment with or without CsA on days 1 and 4. Drug concentrations were quantitated using validated HPLC methods, and pharmacokinetic parameters were determined using compartmental modeling with an iterative two-stage approach, implemented on ADAPT II software. Etoposide displayed a greater degree of interindividual variability in clearance and systemic exposure than mitoxantrone. With CsA treatment, etoposide and mitoxantrone mean clearance declined by 71% and 42%, respectively. These effects on clearance, in combination with the empiric 40% dose reduction for either cytotoxin, resulted in a 47% and 12% increases in the mean AUC for etoposide and mitoxantrone, respectively. There were no differences in the rates of stomatitis or infection between the two groups. CsA treatment resulted in an increased incidence of hyperbilrubinemia, which rapidly reversed upon conclusion of drug therapy. The variability observed in clearance, combined with the empiric 40% dose reduction of the cytotoxins, resulted in statistically similar systemic exposure and similar toxicity.

    View details for DOI 10.1038/sj/leu/2402455

    View details for Web of Science ID 000175631200020

    View details for PubMedID 11986955

  • Mitoxantrone, etoposide, and cyclosporine therapy in pediatric patients with recurrent or refractory acute myeloid leukemia JOURNAL OF CLINICAL ONCOLOGY Dahl, G. V., Lacayo, N. J., Brophy, N., Dunussi-Joannopoulos, K., Weinstein, H. J., Chang, M. R., Sikic, B. I., Arceci, R. J. 2000; 18 (9): 1867-1875

    Abstract

    To determine the remission rate and toxicity of mitoxantrone, etoposide, and cyclosporine (MEC) therapy, multidrug resistance-1 (MDR1) status, and steady-state cyclosporine (CSA) levels in children with relapsed and/or refractory acute myeloid leukemia.MEC therapy consisted of mitoxantrone 6 mg/m(2)/d for 5 days, etoposide 60 mg/m(2)/d for 5 days, and CSA 10 mg/kg for 2 hours followed by 30 mg/kg/d as a continuous infusion for 98 hours. Because of pharmacokinetic interactions, drug doses were decreased to 60% of those found to be effective without coadministration of CSA. MDR1 expression was evaluated by reverse transcriptase polymerase chain reaction, flow cytometry, and the ability of CSA at 2.5 micromol/L to increase intracellular accumulation of (3)H-daunomycin in blasts from bone marrow specimens.The remission rate was 35% (n = 23 of 66). Overall, 35% of patients (n = 23) achieved complete remission (CR), 12% of patients (n = 8) achieved partial remission, and 9% of patients (n = 6) died of infection. Exposure to CSA levels of greater than 2,400 ng/mL was achieved in 95% of patients (n = 56 of 59). Toxicities included infection, cardiotoxicity, myelosuppression, stomatitis, and reversible increases in serum creatinine and bilirubin. In most who had relapsed while receiving therapy or whose induction therapy had failed, response was not significantly different for MDR1-positive and MDR1-negative patients.Serum levels of CSA capable of reversing multidrug resistance are achievable in children with acceptable toxicity. The CR rate of 35% achieved in this study is comparable to previously reported results using standard doses of mitoxantrone and etoposide. The use of CSA may have improved the response rate for the MDR1-positive patients so that it was not different from that for the MDR1-negative patients.

    View details for Web of Science ID 000086873900008

    View details for PubMedID 10784627

  • Loss of cyclosporin and azidopine binding are associated with altered ATPase activity by a mutant p-glycoprotein with deleted Phe(335) MOLECULAR PHARMACOLOGY Chen, G. K., Lacayo, N. J., Duran, G. E., Cohen, D., Sikic, B. I. 2000; 57 (4): 769-777

    Abstract

    In this study, we further characterize a mutant P-glycoprotein (P-gp) that has a deletion of Phe(335) and is resistant to inhibition by cyclosporins. Photoaffinity labeling with [(3)H]cyclosporine and [(3)H]azidopine revealed markedly decreased binding to the mutant P-gp compared with wild-type P-gp. Expression of the mutant P-gp in multidrug-resistant variant cell line MES-SA/DxP (DxP) cells was associated with a 2-fold higher basal ATPase activity relative to multidrug-resistant cell line MES-SA/Dx5 (Dx5) cells with wild-type P-gp. Cyclosporine inhibited ATPase activity in both cell types, whereas the cyclosporin D analog valspodar (PSC 833), vinblastine, and dactinomycin stimulated ATPase activity in Dx5 but not in mutant DxP cells. Moreover, the cell lines differed in their responses to verapamil, which produced greater stimulation of ATPase in Dx5 than DxP cells. Verapamil significantly reversed the [(3)H]daunorubicin accumulation defect in wild-type Dx5 cells, but it had no significant effect on [(3)H]daunorubicin accumulation in the mutant DxP cells. Verapamil was not transported by cells expressing either mutant or wild-type P-gp. Vanadate trapping of azido-ATP was markedly impaired in mutant P-gp. In conclusion, our data demonstrate that Phe(335) of transmembrane 6 is an important amino acid residue for the formation of cyclosporine and azidopine drug-binding site(s). Phe(335) also plays a role in the coupling of verapamil binding and modulation of daunorubicin intracellular accumulation in wild-type P-gp. In addition, Phe(335) in transmembrane 6 may play a role in coupling drug binding to ATPase activity. The deletion of Phe(335) results in a significant increase in the basal ATPase activity with a concomitant decrease in its ability to trap ATP and transport some P-gp substrates.

    View details for Web of Science ID 000086066500017

    View details for PubMedID 10727524

  • Multidrug-resistant human sarcoma cells with a mutant P-glycoprotein, altered phenotype, and resistance to cyclosporins JOURNAL OF BIOLOGICAL CHEMISTRY Chen, G., Duran, G. E., Steger, K. A., Lacayo, N. J., Jaffrezou, J. P., Dumontet, C., Sikic, B. I. 1997; 272 (9): 5974-5982

    Abstract

    A variant of the multidrug-resistant human sarcoma cell line Dx5 was derived by co-selection with doxorubicin and the cyclosporin D analogue PSC 833, a potent inhibitor of the multidrug transporter P-glycoprotein. The variant DxP cells manifest an altered phenotype compared with Dx5, with decreased cross-resistance to Vinca alkaloids and no resistance to dactinomycin. Resistance to doxorubicin and paclitaxel is retained. The multidrug resistance phenotype of DxP cells is not modulated by 2 microM PSC 833 or cyclosporine. DxP cells manifest a decreased ability to transport [3H]cyclosporine. DNA heteroduplex analysis and sequencing reveal a mutant mdr1 gene (deletion of a phenylalanine at amino acid residue 335) in the DxP cell line. The mutant P-glycoprotein has a decreased affinity for PSC 833 and vinblastine and a decreased ability to transport rhodamine 123. Transfection of the mutant mdr1 gene into drug-sensitive MES-SA sarcoma cells confers resistance to both doxorubicin and PSC 833. Our study demonstrates that survival of cells exposed to doxorubicin and PSC 833 in a multistep selection occurred as a result of a P-glycoprotein mutation in transmembrane region 6. These data suggest that Phe335 is an important binding site on P-glycoprotein for substrates such as dactinomycin and vinblastine and for inhibitors such as cyclosporine and PSC 833.

    View details for Web of Science ID A1997WK74700086

    View details for PubMedID 9038218

Conference Proceedings


  • Gene expression profiling and FLT3 status correlate with outcome in de novo acute myeloid leukemia (AML) with normal karyotype: Results of children's oncology group (COG) study POG #9421. Lacayo, N., Meshinchi, S., Raimondi, S., Saraiya, C., O'Brien, M., Yu, R., Juric, D., Chang, M., Willman, C., Tibshirani, R., Ravindranath, Y., Sikic, B., Weinstein, H., Dahl, G. V. AMER SOC HEMATOLOGY. 2005: 667A-667A

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