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Nelson Chao

Publications and source records attributed to Nelson Chao.

8 recordsLinked to original sources
PubMed2006

Acute radiation injury: contingency planning for triage, supportive care, and transplantation.

Evaluation and management of victims of exposure to myelosuppressive radiation in a military, terrorist, or accidental event is challenging. The hematopoietic syndrome with marrow suppression and pancytopenia follows intermediate intensity radiation exposure and as such produces a clinical syndrome similar to that after myelosuppressive chemotherapy or stem cell transplantation. Therefore, hematologists, oncologists, and transplantation physicians have the opportunity and challenge to plan for care of irradiation victims. Management of the hematopoietic syndrome, as a component of acute radiation sickness, requires understanding its manifestations and implementation of clinical biodosimetry to provide appropriate therapeutic support. Hematopoietic growth factors may be of value if administered early as a component of supportive care. Planning for urgent stem cell transplantation for those with intermediate- to high-dose radiation (4-10 Gy) may be required. Establishing contingency plans for triage, assessment, supportive care, and treatment resembles the development of phase II trials, with defined eligibilities, treatment plans, and incorporated data collection to assess results and plan further improvements in care. The hematology/oncology community is most suited to participate in such contingency planning, and the necessary elements for its success are reviewed.

Anemia, Aplastic↗
PubMed2005

Enhancement of vaccine-mediated antitumor immunity in cancer patients after depletion of regulatory T cells.

In this study, we investigated whether elimination of CD4+/CD25+ Tregs using the recombinant IL-2 diphtheria toxin conjugate DAB(389)IL-2 (also known as denileukin diftitox and ONTAK) is capable of enhancing the immunostimulatory efficacy of tumor RNA-transfected DC vaccines. We show that DAB(389)IL-2 is capable of selectively eliminating CD25-expressing Tregs from the PBMCs of cancer patients without inducing toxicity on other cellular subsets with intermediate or low expression of CD25. DAB(389)IL-2-mediated Treg depletion resulted in enhanced stimulation of proliferative and cytotoxic T cell responses in vitro but only when DAB(389)IL-2 was omitted during T cell priming. DAB(389)IL-2 significantly reduced the number of Tregs present in the peripheral blood of metastatic renal cell carcinoma (RCC) patients and abrogated Treg-mediated immunosuppressive activity in vivo. Moreover, DAB(389)IL-2-mediated elimination of Tregs followed by vaccination with RNA-transfected DCs significantly improved the stimulation of tumor-specific T cell responses in RCC patients when compared with vaccination alone. Our findings may have implications in the design of immune-based strategies that may incorporate the Treg depletion strategy to achieve potent antitumor immunity with therapeutic impact.

Aged↗
PubMed2005

Umbilical cord blood transplantation in adults: results of the prospective Cord Blood Transplantation (COBLT).

The Cord Blood Transplantation study group conducted a prospective study of unrelated cord blood transplantation (CBT) to better define the role of this stem cell source for subjects requiring unrelated allogeneic transplantation. We report on 1 stratum of the study designated for adult subjects. The primary end point of the study was survival at 180 days. Secondary end points included engraftment, graft-versus-host disease, relapse, and long-term survival. Eligibility criteria for malignant and nonmalignant diseases were specified. Subjects with active central nervous system disease, Karnofsky performance status <70%, grade 3 or 4 or primary myelofibrosis, or suitable related donors were excluded. Enrollment required a single cord blood unit containing >10(7) nucleated cells per kilogram of recipient weight and matched at > or =4 HLA-A and -B (low or intermediate resolution) and -DRB1 (high resolution) types. Thirty-four subjects were entered, with a median age of 34.5 years (range, 18.2-55 years). Most subjects (n = 23) had a 4 of 6 match, 10 subjects had a 5 of 6 match, and 1 subject had a 6 of 6 match. Diagnoses at transplantation included acute myelogenous leukemia (n = 19), acute lymphoblastic leukemia (n = 9), chronic myelogenous leukemia (n = 3), myelodysplastic syndrome (n = 1), paroxysmal nocturnal hemoglobinuria (PNH) (n = 1), and non-Hodgkin lymphoma (n = 1); 94% were classified as poor risk according to National Marrow Donor Program criteria. Subjects received total body irradiation/cyclophosphamide (n = 27) or busulfan/melphalan (n = 7) conditioning regimens. Four subjects died before CBT and are described here but are not included in the main analysis. The cumulative incidence rates and median times to neutrophil (500/microL) and platelet (>20,000/microL) engraftment were 0.66 by day 42 (median, 31 days) and 0.35 by day 180 (median, 117 days). The cumulative incidence rate for grade II-IV GVHD was 0.34 by day 100. For the primary end point, survival at 180 days, Kaplan-Meier survival estimates were 0.30 (95% confidence interval, 0.14-0.46) by day 180 after transplantation. To date there are 2 survivors, and both are >36 months from enrollment. A retrospective analysis was performed by using high-resolution HLA-A and -B typing, which revealed that approximately one third of subjects had 1 or more additional HLA mismatches compared with results of low- or intermediate-resolution HLA typing. The findings of high treatment-related mortality and slow engraftment kinetics indicate that CBT should continue to be performed in specialized centers with a research focus on cord blood cells.

Adolescent↗
PubMed2004

Phase II feasibility and pharmacokinetic study of concurrent administration of trastuzumab and high-dose chemotherapy in advanced HER2+ breast cancer.

PURPOSE: To evaluate the safety of concurrent treatment with trastuzumab and high-dose chemotherapy (HDC), using cyclophosphamide, cisplatin, and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), with autologous hematopoietic progenitor cells support, in patients with HER2+ advanced breast cancer. EXPERIMENTAL DESIGN: Patients with HER2-overexpressing high-risk primary breast cancer (HRPBC; defined as > or =4 involved nodes or inflammatory disease), or metastatic breast cancer (MBC) were eligible. Treatment consisted of a loading dose of trastuzumab at 4 mg/kg (day -5), HDC (days -5 to -2), autologous hematopoietic progenitor cells infusion on day 0, and weekly maintenance trastuzumab (2 mg/kg) from day +1 (minimum of 9 doses). Cardiac monitoring included serial left ventricular ejection fraction measurements before treatment and on days +20 and +65. RESULTS: Thirty-three patients were prospectively enrolled (13 HRPBC, 20 MBC). Toxicity seemed similar to that expected with this HDC regimen alone. Neutrophils and platelets engrafted promptly. There were no cases of grade 4 or 5 toxicity. One patient experienced symptomatic grade 3 acute cardiac failure on day -4, responsive to treatment. Trastuzumab did not alter the pharmacokinetics of HDC. Eleven of twelve MBC patients with measurable disease (nine of them refractory to previous chemotherapy) experienced an objective response (9 complete and 2 partial responses). At median follow-up of 34 (13-58) months, all HRPBC patients remain alive and free of disease; the MBC group has event-free survival and overall survival rates of 45 and 70%, respectively. CONCLUSIONS: Incorporation of trastuzumab into HDC (cyclophosphamide, cisplatin, and BCNU) is feasible, with no apparent increased toxicity or pharmacokinetic interactions.

Adult↗
PubMed2003

Augmentation of umbilical cord blood (UCB) transplantation with ex vivo-expanded UCB cells: results of a phase 1 trial using the AastromReplicell System.

Allogeneic stem cell transplantation with umbilical cord blood (UCB) cells is limited by the cell dose a single unit provides recipients. Ex vivo expansion is one strategy to increase the number of cells available for transplantation. Aastrom Biosciences developed an automated continuous perfusion culture device for expansion of hematopoietic stem cells (HSCs). Cells are expanded in media supplemented with fetal bovine serum, horse serum, PIXY321, flt-3 ligand, and erythropoietin. We performed a phase 1 trial augmenting conventional UCB transplants with ex vivo-expanded cells. The 28 patients were enrolled on the trial between October 8, 1997 and September 30, 1998. UCB cells were expanded in the device, then administered as a boost to the conventional graft on posttransplantation day 12. While expansion of total cells and colony-forming units (CFUs) occurred in all cases, the magnitude of expansion varied considerably. The median fold increase was 2.4 (range, 1.0-8.5) in nucleated cells, 82 (range, 4.6-266.4) in CFU granulocyte-macrophages, and 0.5 (range, 0.09-2.45) in CD34+ lineage negative (lin-) cells. CD3+ cells did not expand under these conditions. Clinical-scale ex vivo expansion of UCB is feasible, and the administration of ex vivo-expanded cells is well tolerated. Augmentation of UCB transplants with ex vivo-expanded cells did not alter the time to myeloid, erythroid, or platelet engraftment in 21 evaluable patients. Recipients of ex vivo-expanded cells continue to have durable engraftment with a median follow-up of 47 months (range, 41-51 months). A randomized phase 2 study will determine whether augmenting UCB transplants with ex vivo-expanded UCB cells is beneficial.

Adolescent↗
PubMed2003

Depletion of host reactive T cells by photodynamic cell purging and prevention of graft versus host disease.

Graft versus Host Disease (GVHD) is the principal cause of morbidity and mortality in patients undergoing allogeneic stem cell transplant. T cell depletion has been recognized as a method of reducing the incidence of GVHD in allogeneic transplants. Until recently, most T cell depletion methods were non-selective in reducing lymphocytes. Rhodamine purging is one method, which selectively reduces alloreactive T cells preventing GVHD. We review here the methods of non-selective and selective T cell depletion, particularly the newer method of photodynamic purging utilizing rhodamine.

Animals↗
PubMed2003

New developments in allotransplant immunology.

After allogeneic stem cell transplantation, the establishment of the donor's immune system in an antigenically distinct recipient confers a therapeutic graft-versus-malignancy effect, but also causes graft-versus-host disease (GVHD) and protracted immune dysfunction. In the last decade, a molecular-level description of alloimmune interactions and the process of immune recovery leading to tolerance has emerged. Here, new developments in understanding alloresponses, genetic factors that modify them, and strategies to control immune reconstitution are described. In Section I, Dr. John Barrett and colleagues describe the cellular and molecular basis of the alloresponse and the mechanisms underlying the three major outcomes of engraftment, GVHD and the graft-versus-leukemia (GVL) effect. Increasing knowledge of leukemia-restricted antigens suggests ways to separate GVHD and GVL. Recent findings highlight a central role of hematopoietic-derived antigen-presenting cells in the initiation of GVHD and distinct properties of natural killer (NK) cell alloreactivity in engraftment and GVL that are of therapeutic importance. Finally, a detailed map of cellular immune recovery post-transplant is emerging which highlights the importance of post-thymic lymphocytes in determining outcome in the critical first few months following stem cell transplantation. Factors that modify immune reconstitution include immunosuppression, GVHD, the cytokine milieu and poorly-defined homeostatic mechanisms which encourage irregular T cell expansions driven by immunodominant T cell-antigen interactions. In Section II, Prof. Anne Dickinson and colleagues describe genetic polymorphisms outside the human leukocyte antigen (HLA) system that determine the nature of immune reconstitution after allogeneic stem cell transplantation (SCT) and thereby affect transplant outcomethrough GVHD, GVL, and transplant-related mortality. Polymorphisms in cytokine gene promotors and other less characterized genes affect the cytokine milieu of the recipient and the immune reactivity of the donor. Some cytokine gene polymorphisms are significantly associated with transplant outcome. Other non-HLA genes strongly affecting alloresponses code for minor histocompatibility antigens (mHA). Differences between donor and recipient mHA cause GVHD or GVL reactions or graft rejection. Both cytokine gene polymorphisms (CGP) and mHA differences resulting on donor-recipient incompatibilities can be jointly assessed in the skin explant assay as a functional way to select the most suitable donor or the best transplant approach for the recipient. In Section III, Dr. Nelson Chao describes non-pharmaceutical techniques to control immune reconstitution post-transplant. T cells stimulated by host alloantigens can be distinguished from resting T cells by the expression of a variety of activation markers (IL-2 receptor, FAS, CD69, CD71) and by an increased photosensitivity to rhodamine dyes. These differences form the basis for eliminating GVHD-reactive T cells in vitro while conserving GVL and anti-viral immunity. Other attempts to control immune reactions post-transplant include the insertion of suicide genes into the transplanted T cells for effective termination of GVHD reactions, the removal of CD62 ligand expressing cells, and the modulation of T cell reactivity by favoring Th2, Tc2 lymphocyte subset expansion. These technologies could eliminate GVHD while preserving T cell responses to leukemia and reactivating viruses.

Cytokines↗