Allogeneic versus autologous versus peripheral stem cell transplantation in CR1 pediatric AML patients: a single center experience

Autologous Hematopoietic Stem Cell Transplant: A Potential Option for Relapsed Pediatric Acute Myeloid Leukemia With Lack of Matched Sibling Donor and Resource Challenge

Though allogeneic hematopoietic stem cell transplant (HSCT) is standard for relapsed pediatric acute myeloid leukemia, often it may not be accessible due to donor unavailability and resource limitations. We retrospectively analyzed outcomes of 26 children (mean age: 10.9±4.5 y) who underwent autologous HSCT in complete remission 2. Three-year event-free survival and overall survival were 50.1±10.7% and 63.3±9%, respectively; with 1 treatment-related death and 46% relapse rate. Notwithstanding the retrospective study design and somewhat favorable patient characteristics, the outcomes are comparable with those of other series and our own allogeneic HSCT data. Autologous HSCT is a potential alternative to allogeneic HSCT, especially in countries with poorly maintained donor registries.

Survival of Mexican children with acute myeloid leukaemia who received early intensification chemotherapy and an autologous transplant

Background. In Mexico and other developing countries, few reports of the survival of children with acute leukaemia exist. Objective. We aimed at comparing the disease-free survival of children with acute myeloid leukaemia who, in addition to being treated with the Latin American protocol of chemotherapy and an autologous transplant, either underwent early intensified chemotherapy or did not undergo such treatment. Procedure. This was a cohort study with a historical control group, forty patients, less than 16 years old. Group A (20 patients), diagnosed in the period 2005–2007, was treated with the Latin American protocol of chemotherapy with an autologous transplant plus early intensified chemotherapy: high doses of cytarabine and mitoxantrone. Group B (20 patients), diagnosed in the period 1999–2004, was treated as Group A, but without the early intensified chemotherapy. Results. Relapse-free survival for Group A was 90% whereas that for Group B it was 60% (P = 0.041). Overall survival for Group A (18, 90%) was higher than that for Group B (60%). Complete remission continued for two years of follow-up. Conclusions. Relapse-free survival for paediatric patients treated with the Latin American protocol of chemotherapy with an autologous transplant plus early intensified chemotherapy was higher than that for those who did not receive early intensified chemotherapy.

Hematopoetic stem cell transplantation in children

Bone marrow transplantation is called hematopoetic stem cell transplantation (HSCT), since peripheral blood and umbilical cord blood can also be used as sources of stem cell currently. In children, bone marrow transplantation is used as a definite treatment method in many diseases including hemoglobinopaties, immune deficiencies, bone marrow failure and congenital metabolic diseases in addition to hematological malignancies. In addition to the underlying disease, the most important factors which have an impact on prognosis include infections which develop during the process of transplantation and graft-versus-host disease. In this article, it was aimed to give brief information on stem cell sources, preparation therapies, HSCT indications and post-transplantation complications in children.

Low toxicity of a conditioning with 8-Gy total body irradiation, fludarabine and cyclophosphamide as preparative regimen for allogeneic hematopoietic stem cell transplantation in pediatric hematological malignancies

We here report the efficacy and toxicity of a conditioning regimen with fractionated 8-Gy TBI, fludarabine, and cyclophosphamide in allogeneic HSCT for pediatric hematological malignancies. Among 22 children who received related or unrelated HSCT, nine were transplanted with refractory disease and/or from HLA two or more loci-mismatched family donors. None of the patients developed graft failure. The Seattle grading system revealed that 18 patients had no RRT, and the remaining patients had grade I gastrointestinal toxicity alone. The estimated overall survival and leukemia-free survival at two yr were 57.1% and 48.0%, respectively, in 10 patients with acute lymphoblastic leukemia; 91.7% and 71.3%, respectively, in 12 patients with myeloid leukemia. The incidence of TRM was 4.8% at two yr. The rates of RRT above grade II and TRM in an 8-Gy TBI-containing regimen were significantly lower than the data of historical control patients who underwent 12-Gy TBI and cyclophosphamide with or without etoposide. The intermediate-dose TBI-based conditioning regimen may confer successful engraftment combined with minimized RRT, although its efficacy should be further evaluated.

The role of cytotoxic therapy with hematopoietic stem cell transplantation in the therapy of acute myeloid leukemia in children: an evidence-based review

Clinical research examining the role of hematopoietic stem cell transplantation (SCT) in the therapy of acute myeloid leukemia (AML) in children is presented and critically evaluated in this systematic evidence-based review. Specific criteria were used for searching the published literature and for grading the quality and strength of the evidence and the strength of the treatment recommendations. Treatment recommendations based on the evidence are presented in the table entitled "Summary of Treatment Recommendations Made by the Expert Panel for Pediatric Acute Myeloid Leukemia" and were reached unanimously by a panel of experts in AML. The identified priority areas of needed future research in pediatric AML include: What is the role of risk group stratification, including the role of cytogenetics, in selection of patients for allogeneic SCT, especially those in first CR? What is the appropriate timing and use of alternative donor SCT, given that matched unrelated donor SCT appears to yield outcomes equivalent to matched related donor SCT? What is the role of reduced intensity SCT (including the use of fludarabine-based preparative regimens) and/or other immunomodulatory approaches to maximize the graft-versus-leukemic effect? and What is the role of biologically targeted agents (ie, tyrosine kinase inhibitors, farnesyl transferase inhibitors, Flt-3 inhibitors, etc) in the treatment of AML, including induction, consolidation, conditioning regimens, and after SCT?

Leukemia: stem cells, maturation arrest, and differentiation therapy

Human myeloid leukemias provide models of maturation arrest and differentiation therapy of cancer. The genetic lesions of leukemia result in a block of differentiation (maturation arrest) that allows myeloid leukemic cells to continue to proliferate and/or prevents the terminal differentiation and apoptosis seen in normal white blood cells. In chronic myeloid leukemia, the bcr-abl (t9/22) translocation produces a fusion product that is an activated tyrosine kinase resulting in constitutive activation cells at the myelocyte level. This activation may be inhibited by imatinib mesylate (Gleevec, STI-571), which blocks the binding of ATP to the activated tyrosine kinase, prevents phosphorylation, and allows the leukemic cells to differentiate and undergo apoptosis. In acute promyelocytic leukemia, fusion of the retinoic acid receptor-alpha with the gene coding for promyelocytic protein, the PML-RAR alpha (t15:17) translocation, produces a fusion product that blocks the activity of the promyelocytic protein, which is required for formation of the granules of promyelocytes and prevents further differentiation. Retinoic acids bind to the retinoic acid receptor (RAR alpha) component of the fusion product, resulting in degradation of the fusion protein by ubiquitinization. This allows normal PML to participate in granule formation and differentiation of the promyelocytes. In one common type of acute myeloid leukemia, which results in maturation arrest at the myeloid precursor level, there is a mutation of FLT3, a transmembrane tyrosine kinase, which results in constitutive activation of the IL-3 receptor. This may be blocked by agents that inhibit farnesyl transferase. In each of these examples, specific inhibition of the genetically altered activation molecules of the leukemic cells allows the leukemic cells to differentiate and die. Because acute myeloid leukemias usually have mutation of more than one gene, combinations of specific inhibitors that act on the effects of different specific genetic lesions promises to result in more effective and permanent treatment.

Cord blood banking for potential future transplantation

In recent years, umbilical cord blood, which contains a rich source of hematopoietic stem and progenitor cells, has been used successfully as an alternative allogeneic donor source to treat a variety of pediatric genetic, hematologic, immunologic, and oncologic disorders. Because there is diminished risk of graft-versus-host disease after transplantation of cord stem cells using matched related donors, the use of less-than-completely matched HLA cord blood stem cells may incur less risk of graft-versus-host disease than mismatched cells from either a related or unrelated "walking" donor, although this remains to be proven. Gene-therapy research involving modification of autologous cord blood stem cells for the treatment of childhood genetic disorders, although experimental at the present time, may prove to be of value. These scientific advances have resulted in the establishment of not-for-profit and for-profit cord blood-banking programs for allogeneic and autologous cord blood transplantation. Many issues confront institutions that wish to establish or participate in such programs. Parents often seek information from their physicians about this new biotechnology option. This document is intended to provide information to guide physicians in responding to parents' questions about cord blood donation and banking and the types and quality of cord blood banks. Provided also are recommendations about appropriate ethical and operational standards, including informed consent policies, financial disclosures, and conflict-of-interest policies for physicians, institutions, and organizations that operate or have a relationship with cord blood-banking programs.