Search

With improved contemporary therapy, we reassess long-term outcome in patients completing treatment for childhood acute lymphoblastic leukemia (ALL) to determine when cure can be declared with a high degree of confidence. In six successive clinical trials between 1984 and 2007, 1291 (84.5%) patients completed all therapies in continuous complete remission. The post-therapy cumulative risk of relapse or development of a second neoplasm and the event-free survival rate and overall survival were analyzed according to the presenting features and the three treatment periods defined by relative outcome. Over the three treatment periods, there has been progressive increase in the rate of event-free survival (65.2% vs 74.8% vs 85.1% (P<0.001)) and overall survival (76.5% vs 81.1% vs 91.7% (P<0.001)) at 10 years. The most important predictor of outcome after completion of therapy was the type of treatment. In the most recent treatment period, which omitted the use of prophylactic cranial irradiation, the post-treatment cumulative risk of relapse was 6.4%, death in remission 1.5% and development of a second neoplasm 2.3% at 10 years, with all relapses except one occurring within 4 years of therapy. None of the 106 patients with the t(9;22)/BCR-ABL1, t(1;19)/TCF3-PBX1 or t(4;11)/MLL-AFF1 had relapsed after 2 years from completion of therapy. These findings demonstrate that with contemporary effective therapy that excludes cranial irradiation, approximately 6% of children with ALL may relapse after completion of treatment, and those who remain in remission at 4 years post treatment may be considered cured (that is, less than 1% chance of relapse). [ABSTRACT FROM AUTHOR]

ETV6-RUNX1 fusion is the most common genetic aberration in childhood acute lymphoblastic leukemia (ALL). To evaluate whether outcomes for this drug-sensitive leukemia are improved by contemporary risk-directed therapy, we studied clinical features, response and adverse events of 168 children with newly diagnosed ETV6-RUNX1-positive ALL on St Jude Total Therapy studies XIIIA (N=36), XIIIB (N=38) and XV (N=94). Results were compared with 494 ETV6-RUNX1-negative B-precursor ALL patients. ETV6-RUNX1 was associated with age 1-9 years, pre-treatment classification as low risk and lower levels of minimal residual disease (MRD) on day 19 of therapy (P<0.001). Event-free survival (EFS) or overall survival (OS) did not differ between patients with or without ETV6-RUNX1 in Total XIIIA or XIIIB. By contrast, in Total XV, patients with ETV6-RUNX1 had significantly better EFS (P=0.04; 5-year estimate, 96.8±2.4% versus 88.3±2.5%) and OS (P=0.04; 98.9±1.4% versus 93.7±1.8%) than those without ETV6-RUNX1. Within the ETV6-RUNX1 group, the only significant prognostic factor associated with higher OS was the treatment protocol Total XV (versus XIIIA or XIIIB) (P=0.01). Thus, the MRD-guided treatment schema including intensive asparaginase and high-dose methotrexate in the Total XV study produced significantly better outcomes than previous regimens and demonstrated that nearly all children with ETV6-RUNX1 ALL can be cured. [ABSTRACT FROM AUTHOR]

Minimal residual disease (MRD) is an independent prognostic factor in childhood acute lymphoblastic leukemia (ALL). The most widely applied MRD assays in ALL are flow cytometric identification of leukemia immunophenotypes and polymerase chain reaction (PCR) amplification of antigen-receptor genes. We measured MRD by both assays in 227 patients with childhood B-lineage ALL. Of 1375 samples (736 bone marrow and 639 peripheral blood) examined, MRD was <0.01% in 1200, and ≥0.01% in 129 by both assays; MRD levels measured by the two methods correlated well. Of the remaining 46 samples, 28 had MRD ≥0.01% by flow cytometry but <0.01% by PCR. However, PCR (which had a consistent sensitivity of 0.001%) detected leukemic gene rearrangements in 26 of these 28 samples. Conversely, in 18 samples, MRD was ≥0.01% by PCR but <0.01% by flow cytometry. In nine of these samples, flow cytometry had a sensitivity of 0.001%, and detected aberrant immunophenotypes in eight samples. Therefore, the two most widely used methods for MRD detection in ALL yield concordant results in the vast majority of cases, although the estimated levels of MRD may vary in some. The use of the two methods in tandem ensures MRD monitoring in all patients. [ABSTRACT FROM AUTHOR]

Deficient expression of BLNK, an adaptor molecule crucial for normal B-cell development, is associated with increased pro-B/ pre-B-cell expansion in mice. It has been proposed that BLNK deficiency is a primary cause of B-lineage acute lymphoblastic leukemia (ALL). We studied BLNK expression in the leukemic cells from 352 patients with childhood ALL (309 B-lineage; 43 T-lineage). By HG_U95Av2 Affymetrix GeneChip analysis, BLNK was expressed in 275 of 284 (96.8%) B-lineage ALL samples but in only one of 43 (2.3%) T-lineage ALL samples. Of 118 B-lineage ALL samples analyzed with the HG_U133A GeneChip, 117 (99.2%) expressed BLNK. All 30 primary B-lineage ALL samples studied by RT-PCR expressed BLNK transcripts; all 19 samples studied by Western blotting or flow cytometry expressed BLNK protein. Levels of BLNK in B-lineage ALL were as high as those of their normal counterparts; they were not related with genetic subgroups or differentiation stage. These results indicate that BLNK deficiency is a rare occurrence in childhood B-lineage ALL and is unlikely to be a common leukemogenic event as previously proposed. [ABSTRACT FROM AUTHOR]

Using flow cytometric techniques capable of detecting 0.01% leukemic cells, we prospectively studied minimal residual disease (MRD) in patients with acute lymphoblastic leukemia (ALL) after first relapse. At the end of remission reinduction, 41 patients had a bone marrow sample adequate for MRD studies; 35 of these were in morphologic remission. Of the 35 patients, 19 (54%) had MRD ?0.01%, a finding that was associated with subsequent leukemia relapse. The 2-year cumulative incidence of second leukemia relapse was 70.2±12.3% for the 19 MRD-positive patients and 27.9±12.4% for the 16 MRD-negative patients (P=0.008). Among patients with a first relapse off therapy, 2-year second relapse rates were 49.1±17.8% in the 12 MRD-positive and 0% in the 11 MRD-negative patients (P=0.014); among those who received only chemotherapy after first relapse, the 2-year second relapse rates were 81.5±14.4% (n=12) and 25.0±13.1% (n=13), respectively (P=0.004). Time of first relapse and MRD were the only two significant predictors of outcome in a multivariate analysis. We conclude that MRD assays should be used to guide the selection of postremission therapy in patients with ALL in first relapse.Leukemia (2004) 18, 499-504. doi:10.1038/sj.leu.2403283 [ABSTRACT FROM AUTHOR]

We examined Fc receptor expression and function in normal and leukemic human immature B cells. Fc receptor expression increased with normal B cell maturation: CD32[sup +] cells composed 8.1%±1.2% (mean±s.d.) of the least mature (CD34[sup +]CD10[sup +]), 19.2% q 5.7% of intermediate (CD34[sup -]CD10[sup +]), and 82.4% ± 5.0% of mature (CD34[sup -]CD10[sup -]) bone marrow CD19[sup +] B cells. Forty-five of 57 primary B-lineage acute lymphoblastic leukemia samples and all six cell lines studied expressed Fc receptors. By RTPCR and antibody staining, FcγRIIA was the Fc receptor predominantly expressed in these cells. FcγRIIA ligation in RS4;11 and 380 cells induced tyrosine phosphorylation of CD32, CD19, CBL, SYK, P13-K p85 and SHIP, as well as RasGAP association with tyrosine-phosphorylated p62[sup dok]. These signalling events resulted in a marked suppression of leukemia cell growth. After s 7-day exposure to anti-CD32, the recovery of ALL cells cocultured with stroms was reduced to 5.5% ± 2.8% of control values in 380 cells (n=14), 19.4%±6.1% (n=8) in RS4;11, and 4.0% ± 1.3% (n = 6) in KOPN55bi. CD32 ligation also reduced cell recovery in five of seven CD32[sup +] primary leukemia samples. Thus, FcγRIIA mediates signals that suppress the growth of lymphoid leukemia cells. [ABSTRACT FROM AUTHOR]

Clotrimazole is an antimycotic imidazole derivative that interferes with cellular Ca[sup 2+] homeostasis. We investigated the effects of clotrimazoie on acute lymphoblastic leukemia (ALL) cells. Treatment with 10 µM clotrimazole (a concentration achievable in vivo) reduced cell recovery from cultures of all nine ALL cell lines studied (B-lineage: OP-1, SUP-B15, RS4;11, NALM6, REH, and 380; T-lineage: MOLT4, CCRF-CEM, and CEM-C7). After 4 days of culture, median cell recovery was 10% (range, <1% to 37%) of cell recovery in parallel untreated cultures. Clotrimazole also inhibited recovery of primary ALL cells cultured on stromal feeder layers. After leukemic cells from 16 cases of ALL were cultured for 7 days with 10 µM clotrimazole, median cell recovery was <1% (range, <1% to 16%) of that in parallel untreated cultures. Clotrimazole was active against leukemic cells with genetic abnormalities associated with poor response to therapy and against multidrug-resistant cell lines. In contrast, mature T lymphocytes and bone marrow stromal cells were not affected. Clotrimazole induced depletion of intracellular Ca[sup 2+] stores in ALL cells, which was followed by apoptosis, as shown by annexin V binding and DNA fragmentation. Thus, clotrimazole is cytotoxic to ALL cells at concentrations achievable in vivo. [ABSTRACT FROM AUTHOR]

Children with acute lymphoblastic leukemia (ALL) with > or = 0.01% leukemic cells in the bone marrow after remission induction are at a greater risk of relapse. The most promising methods of detecting minimal residual disease (MRD) are flow cytometric identification of leukemia-associated immunophenotypes and polymerase chain reaction (PCR) amplification of antigen-receptor genes. However, neither assay can be applied to all patients. Moreover, both assays carry the risk of false-negative findings due to clonal evolution. The simultaneous use of both assays might resolve these problems, but the correlation between the methods is unknown. We studied serial dilutions of normal and leukemic cells by flow cytometry and PCR amplification of IgH genes and found the two methods highly sensitive (one leukemic cell among 10(4) or more normal cells), accurate (r2 was 0.999 for flow cytometry and 0.960 for PCR by regression analysis) and concordant (r2 = 0.962). We then examined 62 bone marrow samples collected from children with ALL in clinical remission. In 12 samples, both techniques detected MRD levels > or = 1 in 10(4). The percentages of leukemic cells measured by the two methods correlated well (r2 = 0.978). Of the remaining 50 samples, 48 had MRD levels < 1 in 10(4). In only two samples results were discordant: 2 in 10(4) and 5 in 10(4) leukemic cells by PCR but < 1 in 10(4) by flow cytometry. We conclude that immunologic and molecular techniques can be used in tandem for universal monitoring of MRD in childhood ALL. [ABSTRACT FROM AUTHOR]

This article focuses on the development of a regional flow cytometry center for diagnosis of childhood leukemia in Central America. Assessment of immunophenotype and DNA content of leukemia is important for diagnosis and risk assessment, but requires costly equipment, reagents and technical expertise. Samples from 1118 children in Central America were sent for flow cytometric examination to a reference laboratory in Guatemala City. Immunophenotyping of leukemias is necessary for diagnosis and risk-directed therapy.

Presents a reply to a letter to the editor addressing the application of minimal residual disease as a predictor outcome in children with first relapse of acute lymphocytic leukemia.

Discusses the detection of minimal residual disease (MRD) in acute lymphoblastic leukemia (ALL). Methods of MRD detection; Reason behind the non-usage of polymerase chain reaction gene amplification as routine MRD essay; Cause of extending benefits of MRD monitoring to all ALL patients; Clinical and biological parameters which are considered during treatment.

Presents methods for the exchange of flow cytometric data between remote locations. Effective means of communication between locations; Brief description of the software Timbuktu Pro used for establishing communication; Methods of using Timbuktu Pro.