Infants o1 year of age have a high prevalence of prognostically unfavorable leukemias and a presumed susceptibility to treatment-related toxicities. A total of 125 infants with acute myeloid leukemia (AML) were treated in studies AML-BFM-98 (n ¼ 59) and -2004 (n ¼ 66). Treatment regimens of both studies were comparable, consisting of intensive induction followed by four courses (mainly high-dose cytarabine and anthracyclines). Allogeneic-hematopoietic stem-cell-transplantation (allo-HSCT) in 1st remission was optional for high-risk (HR) patients. Most infants (120/125 ¼ 96%) were HR patients according to morphological, cytogenetic/molecular genetic and response criteria. Five-year overall survival was 66±4%, and improved from 61±6% in study-98 to 75±6% in study-2004 (P logrank 0.14) and event-free survival rates were 44±6% and 51±6% (P logrank 0.66), respectively. Results in HR infants were similar to those of older HR children (1-o2-or 2-o10-year olds, P logrank 0.90 for survival). Survival rates of HSCT in 1st remission, initial partial response and after relapse were high (13/14, 2/8 and 20/30 patients, respectively). The latter contributes to excellent 5-year survival after relapse (50±8%). Despite more severe infections and pulmonary toxicities in infants, treatment-related death rate was identical to that of older children (3%). Our data indicate that intensive frontline and relapse AML treatment is feasible in infants, toxicities are manageable, and outcome is favorable.

We studied the differentiation profiles of B cell precursors Materials and methods(BCP) in normal and post-chemotherapy pediatric bone marrow (BM) using multiparameter flow cytometry. The goal of our Sample description study was to draw a comprehensive phenotypic map of the three major maturational BCP stages in BM. By correlating lineage-associated markers, CD45RA, and several adhesion molPediatric bone marrow (BM) samples (n = 44) were obtained ecules, the stage-specific patterns were found to differ in cerfrom children undergoing diagnostic BM aspiration for the foltain details from previously published concepts. Among the lowing diagnoses in the absence of BM involvement at the earliest BCP, a subset of CD34 + CD10 lo precursors was repeattime of immunologic investigation: suspicion of storage disedly observed in addition to the well characterized ease (n = 1), bacterial lymphadenitis (n = 1), neuroblastoma CD34 + CD10 hi CD19 + majority of cells. Only two-thirds of these CD34 + CD10 lo cells expressed CD19. However, uniformity of (n = 1), severe aplastic anemia in remission (n = 2), single sys- observation time from BM aspiration to final evaluation was 1 2 12 years (range: 1 month to 2 6 12 years). The two patients with the shortest follow-up (1 and 2 months) have been in conIntroduction firmed remission for 3 3 12 years and 4 months, respectively. All leukemia/lymphoma patients described in this paper were The mainstays in defining the phenotypic patterns of B cell treated according to BFM (Berlin-Frankfurt-Mü nster) treatdifferentiation have already been documented during the last ment protocols. In brief, for ALL a multi-agent induction thertwo decades. [1][2][3][4] In brief, the CD19 antigen is expressed apy administered in three cycles over the first six months was throughout all stages of B cell maturation, 1,5 while CD10 is followed by a low-dose maintenance therapy until completion highly expressed in the most immature (CD34 + ) B cell precurof the second therapy year. All data concerning these patients sors (BCP), 3 and is lost at a later stage concomitantly with gain were obtained from the Austrian study center of the of surface expression of CD20, IgM and CD22. 2 More international BFM study group. recently, this classical model of B cell differentiation was challenged, as new antigenic patterns, 6-8 new insights into the sequence of antigen acquisition in B cell ontogeny, 9 and Antibodies tissue-related differences in the coordinate patterns of B lymphoid antigen expression were documented. 10,11 In the present study, our aim was comprehensively to redeFluorescein isothiocyanate (FITC)-, and phycoerythrin (PE)-fine the phenotypic patterns of the early stages of normal B labeled, or unconjugated pure monoclonal antibodies cell differentiation in postnatal bone marrow by multi-(MoAbs) were used: CD7 (DK24-FITC), CD10 (SS2/36-PE), parameter flow cytometry. By comparing normal and postCD11a (MHM24 pure), CD19 (HD37-FITC, pure), CD20 (Bchemotherapy bone marrow, we focused on sample-inherent Ly1-F...

The ETV6/RUNX1 (E/R) gene fusion is generated by the t(12;21) and found in approximately 25% of childhood B-cell precursor acute lymphoblastic leukemia. In contrast to the overwhelming evidence that E/R is critical for the initiation of leukemia, its relevance for the maintenance of overt disease is less clear. To investigate this issue, we suppressed the endogenous E/R fusion protein with lentivirally transduced short hairpin RNA in the leukemia cell lines REH and AT-2, and found a distinct reduction of proliferation and cell survival. In line with the observed concurrent inactivation of the phosphoinositide 3-kinase (PI3K)/AKT/ mammalian target of rapamycin (mTOR) pathway, pharmacological inhibition diminished the phosphorylation of AKT and ribosomal protein S6, and significantly increased the apoptosis rate in E/R-positive leukemias. Moreover, PI3K/mTOR inhibitors sensitized glucocorticoid-resistant REH cells to prednisolone, an observation of potential relevance for improving treatment of drug-resistant relapses. Of note, knockdown of the E/R fusion gene also severely impaired the repopulation capacity of REH cells in non-obese deficient/severe combined immunodeficient mice. Collectively, these data demonstrate that the E/R fusion protein activates the PI3K/AKT/mTOR pathway and is indispensible for disease maintenance. Importantly, these results provide a first rationale and justification for targeting the fusion gene and the PI3K/AKT/mTOR pathway therapeutically.

In the management of the childhood acute lymphoblastic leukemia (ALL), 5% of failures are due to induction death and treatment-related deaths in first complete remission. We retrospectively analyzed the incidence, pattern and causes of death and its risk factors for 896 children with ALL enrolled into five Austrian (A) Berlin-Frankfurt-Münster (BFM) trials between 1981 and 1999. The estimated 10-year cumulative incidence of death significantly decreased from 6+/-1% (n=16/268) in trials ALL-BFM-A 81 and ALL-A 84 to 2+/-1% (n=15/628) in trials ALL-BFM-A 86, 90 and 95 (P=0.006). A significant reduction of death was evident during induction therapy (2.2% in trials ALL-BFM-A 81 and ALL-A 84 and 0.2% in trials ALL-BFM-A 86, 90 and 95, P=0.001). Of 31 patients, 21 (68%) patients died from infectious and 10 (32%) from noninfectious complications. Treatment in trial ALL-BFM-A 81, infant age and female gender were independent predictors of an enhanced risk for death. Conclusively, we found a progressive reduction of death rates that may be explained by the increasing experience in specialized hemato-oncologic centers and improved supportive and intensive care. We also identified a distinct subset of patients who are especially prone to death and may need a special focus when receiving intense chemotherapy.

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