Accumulation of methotrexate and methotrexate polyglutamates in lymphoblasts and treatment outcome in children with B-progenitor-cell acute lymphoblastic leukemia: a Pediatric Oncology Group study.

We reported that children with B-progenitor-cell acute lymphoblastic leukemia (BpALL) treated in the early 1980s whose lymphoblasts accumulated high levels of methotrexate (MTX) and of methotrexate polyglutamates (MTXPGs) in vitro had an improved 5-year event-free survival (EFS) (65% (standard error (s.e.) 12%) vs 22% (s.e. 9%)). We repeated this study in children with BpALL treated in the early 1990s. The major change in treatment was the addition of 12 24-h infusions of 1 g/M2 MTX with leucovorin rescue (IDMTX). In 87 children treated on Pediatric Oncology Group (POG) study 9005 and POG 9006, the 5-year EFS for those whose lymphoblasts accumulated high levels of MTX and MTXPGs (79.2%, s.e. 8.3%) was not significantly different from that of patients with lesser accumulation of MTX and MTXPGs (77.7%, s.e. 5.4%). These findings support the notion that higher dose MTX therapy has contributed to increased cure, particularly for patients whose lymphoblasts accumulate the drug less well.

Minimal residual disease detection in childhood precursor-B-cell acute lymphoblastic leukemia: relation to other risk factors. A Children's Oncology Group study.

Minimal residual disease (MRD) can be detected in the marrows of children undergoing chemotherapy either by flow cytometry or polymerase chain reaction. In this study, we used four-color flow cytometry to detect MRD in 1016 children undergoing therapy on Children's Oncology Group therapeutic protocols for precursor-B-cell ALL. Compliance was excellent, with follow-up samples received at the end of induction on nearly 95% of cases; sensitivity of detection at this time point was at least 1/10,000 in more than 90% of cases. Overall, 28.6% of patients had detectable MRD at the end of induction. Patients with M3 marrows at day 8 were much more likely to be MRD positive (MRD+) than those with M2 or M1 marrows. Different genetically defined groups of patients varied in their prevalence of MRD. Specifically, almost all patients with BCR-ABL had high levels of end-of-induction MRD. Only 8.4% of patients with TEL-AML1 were MRD+>0.01% compared with 20.3% of patients with trisomies of chromosomes 4 and 10. Our results show that MRD correlates with conventional measures of slow early response. However, the high frequency of MRD positivity in favorable trisomy patients suggests that the clinical significance of MRD positivity at the end of induction may not be the same in all patient groups.

The association of the TEL-AML1 chromosomal translocation with the accumulation of methotrexate polyglutamates in lymphoblasts and with ploidy in childhood B-progenitor cell acute lymphoblastic leukemia: a Pediatric Oncology Group study.

Lymphoblasts from children with B-progenitor cell acute lymphoblastic leukemia (BpALL) with chromosomal hyperdiploidy and with translocations affecting chromosome 12p11-13, accumulate high and low levels of methotrexate polyglutamates (MTXPGs), respectively. Recently a cryptic translocation, t(12;21) (p13;q22), has been demonstrated by molecular and fluorescence in situ hybridization techniques in this disease. The chimeric TEL-AML1 transcript, which has been associated with this translocation, can be detected in up to 25% of children with BpALL. We detected the TEL-AML1 and/or the AML1-TEL transcript in 30 (33%) of 91 patients studied. Levels of lymphoblast MTXPGs were lower in those with than in those without the TEL-AML1 translocation (P = 0.004). Hyperdiploidy was rare in lymphoblasts with the TEL-AML1 translocation (P = 0.047). Both ploidy (P= 0.0015) and TEL-AML1 status (P= 0.0043) were independently and significantly correlated with the log of the lymphoblast MTXPG level. However, the presence of TEL-AML1 or of hyperdiploidy accounted for only 22% of the variation of this value. Our results imply that each of 1.16 > or = DI and the presence of the TEL-AML1 translocation confers a 50% decrease in lymphoblast MTXPG level. When planning reduction of therapy for either of the two excellent outcome categories of hyperdiploid or TEL-AML1 BpALL, one should consider the difference between these two subgroups in the ability of lymphoblasts to accumulate MTXPGs.

New recurring cytogenetic abnormalities and association of blast cell karyotypes with prognosis in childhood T-cell acute lymphoblastic leukemia: a pediatric oncology group report of 343 cases.

To further define the cytogenetic differences between B-cell lineage (B-lineage) acute lymphoblastic leukemia (ALL) and T-cell lineage ALL (T-ALL) and to determine the prognostic value of cytogenetics in childhood T-ALL, the blast cell karyotypes of 343 cases of pediatric T-ALL, the largest series reported to date, were evaluated. Cytogenetics were performed in a single central laboratory, and the children were treated using a single Pediatric Oncology Group protocol. Clear differences between the karyotypic characteristics of B-lineage ALL and T-ALL were confirmed. This study suggests that there may be survival differences associated with some T-ALL blast cell karyotypes. Better survival is associated with only normal karyotypes and with t(10;14) (translocation of chromosomes 10 and 14); worse survival is associated with the presence of any derivative chromosome. Two new recurring chromosome aberrations previously not reported in T-ALL were found: del(1)(p22) and t(8;12)(q13;p13). Ten aberrations found in this series, which were reported only once previously in T-ALL, can now be considered recurring abnormalities in T-ALL. All 12 of these new recurring aberrations are targets for discovery and characterization of new genes that are important in T-cell development and leukemogenesis.

Acute lymphoblastic leukemia with an unusual t(8;14)(q11.2;q32): a Pediatric Oncology Group Study.

We present the clinicopathologic findings and survival data on 10 patients with acute lymphoblastic leukemia (ALL) and a rare t(8;14)(q11.2;q32). There were five male and five female patients, nine Caucasians and one Black, aged 4-17 (median 10.9) years. Three had Down syndrome. Eight (80%) patients had a white blood cell (WBC) count <50 x 109/l at presentation. No patient had central nervous system involvement or a mediastinal mass. Two patients had concurrent splenomegaly and hepatomegaly. Adenopathy was absent in four, minimal in three, moderate in one and prominent in two patients. All eight cases where immunophenotyping was performed by flow cytometry showed a B-precursor phenotype with expression of CD10 (CALLA). Only one case exhibited t(8;14)(q11.2;q32) as the sole karyotypic abnormality. Three patients were classified as standard-risk and seven high-risk by NCI (National Cancer Institute) consensus risk group categories. All patients achieved complete remission and seven patients were in complete continuous remission (CCR) after chemotherapy designed for B-precursor ALL. Three patients relapsed after 23.5, 31.3 and 32.1 months of EFS; the first patient also had t(9;22)(q34;q11), the second had a WBC count of 126 x 109/l at presentation while the third patient had no high risk features except for age 10 years. Thus, from our data, the t(8;14)(q11.2;q32) does not appear to confer an increased risk of relapse. Further observations are needed to confirm this conclusion.

Racial differences in the survival of childhood B-precursor acute lymphoblastic leukemia: a Pediatric Oncology Group Study.

PURPOSE: We conducted a historic cohort study to test the hypothesis that, after adjustment for biologic factors, African-American (AA) children and Spanish surname (SS) children with newly diagnosed B-precursor acute lymphoblastic leukemia had lower survival than did comparable white children. PATIENTS AND METHODS: From 1981 to 1994, 4,061 white, 518 AA, and 507 SS children aged 1 to 20 years were treated on three successive Pediatric Oncology Group multicenter randomized clinical trials. RESULTS: AA and SS patients were more likely to have adverse prognostic features at diagnosis and lower survival than were white patients. The 5-year cumulative survival rates were (probability +/- SE) 81.9% +/- 0.6%, 68.6% +/- 2.1%, and 74.9% +/- 2.0% for white, AA, and SS children, respectively. Adjusting for age, leukocyte count, sex, era of treatment, and leukemia blast cell ploidy, we found that AA children had a 42% excess mortality rate compared with white children (proportional hazards ratio [PHR] = 1.42; 95% confidence interval [CI], 1.12 to 1. 80), and SS children had a 33% excess mortality rate compared with white children (PHR = 1.33; 95% CI, 1.19 to 1.49). CONCLUSION: Clinical presentation, tumor biology, and deviations from prescribed therapy did not explain the differences in survival and event-free survival that we observed, although differences seem to be diminishing over time with improvements in therapy. The disparity in outcome for AA and SS children is most likely related to variations in chemotherapeutic response to therapy and not to compliance. Further improvements in outcome may require individualized dosing based on specific pharmacogenetic profiles, especially for AA and SS children.

Childhood acute lymphoblastic leukemia with the MLL-ENL fusion and t(11;19)(q23;p13.3) translocation.

PURPOSE: To determine the molecular characteristics, clinical features, and treatment outcomes of children with acute lymphoblastic leukemia (ALL) and the t(11;19)(q23,p13.3) translocation. PATIENTS AND METHODS: A retrospective analysis of leukemic cell karyotypes obtained from patients with new diagnoses of ALL who were treated at St. Jude Children's Research Hospital or by the Pediatric Oncology Group was performed to identify cases with the t(11;19)(q23;p13.3) translocation. Molecular analyses were performed on these cases to determine the status of the MLL gene and the presence of the MLL-ENL fusion transcript. RESULTS: Among 3,578 patients with ALL and successful cytogenetic analysis, we identified 35 patients with the t(11;19)(q23;p13.3) translocation: 13 infants and 11 older children had B-precursor leukemia, whereas 11 patients had a T-cell phenotype. Although all of the cases examined had MLL rearrangements and MLL-ENL fusion transcripts, outcome varied according to age and immunophenotype. Among B-precursor cases, only two of the 13 infants remain in complete remission, compared with six of the 11 older children. Most strikingly, no relapses have occurred among B-precursor patients 1 to 9 years of age or among T-cell patients. CONCLUSION: Although MLL gene rearrangements are generally associated with a dismal outcome in ALL, two distinct subsets with MLL-ENL fusions have an excellent prognosis. Our results suggest that patients with this genetic abnormality who have T-cell ALL or are 1 to 9 years of age should not be considered candidates for hematopoietic stem-cell transplantation during their first remission.

Acute lymphoblastic leukemia with the (8;14)(q24;q32) translocation and FAB L3 morphology associated with a B-precursor immunophenotype: the Pediatric Oncology Group experience.

Five pediatric patients are described with acute lymphoblastic leukemia (ALL) who at presentation had clinical findings suggestive of B cell ALL and lymphoblasts with FAB L3 morphology and the characteristic t(8;14)(q24;q32). However, the leukemia cells of all five patients failed to express surface immunoglobulin (sIg) and kappa or lambda light chains. Based on initial immunophenotyping results consistent with B-precursor ALL, four of these cases were initially treated with conventional ALL chemotherapy. These four patients were switched to B cell ALL treatment protocols once cytogenetic results became available revealing the 8;14 translocation. The fifth case was treated with B cell ALL therapy from the outset. Four of the five patients are in complete remission at 64, 36, 29 and 13 months from diagnosis. One patient relapsed and died 6 months after initial presentation. These five unusual cases with clinical B cell ALL, the t(8;14), and FAB L3 morphology, but negative sIg, demonstrate the importance of careful and multidisciplinary evaluation of leukemic cells with morphology, cytochemistry, immunophenotyping and cytogenetic analysis. Future identification of patients with this profile will allow us to expand our knowledge regarding prognostic significance and optimal treatment for this rare subgroup of patients.

Surface antigen phenotype can predict TEL-AML1 rearrangement in childhood B-precursor ALL: a Pediatric Oncology Group study.

The t(12;21)(p13;q22) is the most common translocation in childhood B-precursor ALL. It results in a TEL-AML1 rearrangement and is associated with a good prognosis. Because many chromosomal alterations in leukemia are associated with distinct cell surface phenotypes, we investigated whether there was an association seen between surface marker expression and the TEL-AML1 rearrangement. Of 166 unselected cases of B-precursor ALL studied by Southern hybridization, 45 cases (27%) showed TEL rearrangement. Blasts of patients with TEL rearrangement were much more likely to be CD9-negative, CD45-positive, CD13 positive, and CD20 negative, but the predictive value of any of these markers for the rearrangement was very low. However, 93% of patients with the TEL rearrangement had blasts that were either negative or only partly positive for CD9; this phenotype was only seen in 27% of patients without the rearrangement. Only information about CD20 expression added to the predictive value of CD9 alone. The predictive value of the phenotype CD9 (negative or partly positive) and CD20 (negative or partly positive), for the TEL rearrangement was prospectively tested on an additional 223 cases, and found to be 88% sensitive and 71% specific for the rearrangement, with a positive predictive value of 47%. Hyperdiploidy, previously shown to correlate negatively with the rearrangement, was a slightly more sensitive indicator (94%) but had a much lower predictive value (28%). Three of eight cases found to be rearranged by Southern hybridization but lacking the characteristic phenotype failed to show evidence of the TEL-AML1 rearrangement by polymerase chain reaction, suggesting that at least some of the discordant cases may involve partner genes other than AML1 in the TEL rearrangement. We conclude that immunophenotyping is highly predictive of the TEL rearrangement. For every 100 patients with B-precursor ALL, we estimate that prescreening by phenotyping would eliminate the need for molecular testing on 57 patients and only two or three of an expected 24 patients with the TEL rearrangement would not be detected.

Consolidation therapy with antimetabolite-based therapy in standard-risk acute lymphocytic leukemia of childhood: a Pediatric Oncology Group Study.

PURPOSE: To develop antimetabolite-based consolidation regimens that minimize acute and long-term toxicities and improve the survival rate of children with standard-risk B-lineage acute lymphocytic leukemia (ALL). PATIENTS AND METHODS: Seven hundred twenty-seven eligible patients with standard-risk early pre-B ALL were registered onto the study. Seven hundred sixteen patients attained a complete remission (CR) after induction therapy. Of these, 114 patients were randomized to a different regimen and were the subject of a separate report. Six hundred two patients were randomized to receive one the following regimens: intermediate-dose methotrexate (IDMTX) with leucovorin rescue on weeks 7, 10, 13, 16, 19, and 22 (regimen A); regimen A plus asparaginase (ASP) administered intramuscularly (i.m.) weekly for 24 weeks (regimen B); or regimen A plus a 24-hour infusion of cytarabine (AraC) with each IDMTX (regimen C). After consolidation, patients were placed on maintenance therapy through week 156. Regimens A and C were opened in February 1986, and regimen B in May 1987. Comparisons are based on concurrently randomized patients (May 1987 to January 1991 between regimens A and B, and February 1986 to January 1991 between regimens A and C). RESULTS: The 5-year continuous CR (CCR) rates were not significantly different: A versus B, 78.1% (3.9 +/- SE) versus 83.3% +/- 3.5% and A versus C, 79.4% +/- 3.2% versus 83.5% +/- 2.9%; P by one-sided log-rank tests were .27 and .34, respectively. Significant treatment differences were not found with regard to sex, rate of testicular and CNS relapse, or CNS complications. During consolidation, regimen C had significantly more bacterial infections (P = .0032) and days spent in the hospital (P < .001) compared with regimen A. CONCLUSION: We were unable to show a statistical advantage of adding either ASP or AraC to IDMTX in terms of improvement in event-free survival (EFS).

Translocations involving chromosome 12p11-13, methotrexate metabolism, and outcome in childhood B-progenitor cell acute lymphoblastic leukemia: a Pediatric Oncology Group study.

Children with B-progenitor cell acute lymphoblastic leukemia whose lymphoblasts at diagnosis accumulate high levels of methotrexate (MTX) and MTX polyglutamates (MTXPGs) appear to have a good prognosis. This has been attributed to increased sensitivity of their blast cells to MTX. However, the proportion of children who are cured of B-progenitor cell acute lymphoblastic leukemia exceeds the number whose lymphoblasts accumulate high MTXPG levels. We report that lymphoblasts from patients with < 50 chromosomes who have translocations that involve the short arm of chromosome 12 accumulate low levels of MTXPGs. These patients appear to have an excellent survival because none of 14 patients with translocations affecting 12p has relapsed, 26-79 months following diagnosis.

E2A-PBX1 chimeric transcript status at end of consolidation is not predictive of treatment outcome in childhood acute lymphoblastic leukemias with a t(1;19)(q23;p13): a Pediatric Oncology Group study.

A t(1;19)(q23;p13) is detected cytogenetically in approximately 5% of childhood acute lymphoblastic leukemias (ALLs) and its presence has been associated with an increased risk of relapse in several previously-completed Pediatric Oncology Group (POG) clinical trials. The t(1;19) fuses E2A to PBX1 in more than 95% of cases and this molecular abnormality can be reliably identified by polymerase chain reaction (PCR)-mediated amplification of E2A-PBX1 chimeric mRNAs. We used a nested PCR assay, which reproducibly detected a 10(4)- to 10(5)-fold dilution of t(1;19)+ into t(1;19)- cells, to evaluate minimal residual disease (MRD) in 48 children with t(1;19)+ ALL enrolled in POG clinical trials for lower (POG 9005) and higher (POG 9006) risk ALL. Peripheral blood (PB) and bone marrow (BM) samples were collected prospectively at the end of consolidation (weeks 25 and 31 after end of induction) and the presence or absence of PCR-detectable MRD was correlated with clinical outcome. Overall, 41 of 148 (28%) samples were PCR+. Of the 65 time points with informative results from both PB and BM, PCR results were concordant for 51 pairs (10 PB+/BM+, 41 PB-/ BM-) and discordant for 14 (5 PB+/BM-, 9 PB-/BM+), indicating that assessment of only PB or only BM can inaccurately classify some PCR+ cases as PCR-. There were no significant differences in event-free survival between PCR+ and PCR- patients. We conclude that qualitative detection of MRD by amplification of E2A-PBX1 chimeric mRNAs at the end of consolidation was not significantly predictive of outcome for children treated on POG 9005/9006 and that such results should not be used to alter therapy for patients with t(1;19)+ ALL.

Accumulation of methotrexate polyglutamates, ploidy and trisomies of both chromosomes 4 and 10 in lymphoblasts from children with B-progenitor cell acute lymphoblastic leukemia: a Pediatric Oncology Group Study.

Levels of accumulation of methotrexate polyglutamates were measured in vitro in lymphoblasts obtained at diagnosis from children with B-progenitor cell acute lymphoblastic leukemia (pro-B ALL). They were compared to numerical and structural chromosomal abnormalities present in these leukemic cells. In a series of 95 patients, the percent with high lymphoblast methotrexate polyglutamate levels increased with the increase in modal number of total chromosomes (p<0.001). Thus, lymphoblast methotrexate polyglutamate accumulation appeared to be closely linked to the extent of hyperdiploidy in childhood pro-B ALL. Lymphoblasts from 35 (88%) of the 40 children with hyperdiploid (>50 chromosomes) and 23 (88%) of 26 with hyperdiploid (DNA Index >1.16) pro-B ALL accumulated high levels of methotrexate polyglutamate, suggesting that they were more sensitive to methotrexate cytotoxicity. While children with hyperdiploid (DNA Index >1.16) pro-B ALL have a good prognosis, those with trisomies of both chromosomes 4 and 10, almost all of whom are hyperdiploid, have an even better outcome. There was no significant difference in methotrexate polyglutamate levels in lymphoblasts from 19 children with and 21 without trisomies of both chromosomes 4 and 10 (p = 0.25). The improved response to multi-agent chemotherapy conferred by the presence of trisomies of both chromosomes 4 and 10 in such patients may be due to increased sensitivity of their lymphoblasts to one or more anti-leukemic agents in addition to methotrexate.

Lack of ETV6 (TEL) gene rearrangements or p16INK4A/p15INK4B homozygous gene deletions in infant acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) occurring in infants less than 1 year of age differs clinically and biologically from that observed in older children. Cytogenetically, 11q23 translocations are detected in approximately 50% of infant ALLs and fuse the 11q23 gene HRX with a variety of partner chromosomal loci. Overall, HRX rearrangements are detected molecularly in 70-80% of infant ALLs as compared to 5-7% of ALLs arising in older children. Two recently described molecular abnormalities in childhood ALL are ETV6 gene rearrangements and homozygous deletions of p16(INK4A) and/or p15(INK4B). Each of these abnormalities occurs in 15-20% of all childhood ALLs, and neither can be accurately identified by routine cytogenetic analyses. The incidence of these genetic abnormalities and their potential relationship to HRX gene status in infant ALL is unknown. Using Southern blot analyses, we determined ETV6 and p16(INK4A)/p15(INK4B) gene status in a cohort of infant ALLs. No ETV6 rearrangements or homozygous deletions (n=69) or homozygous p16(INK4A) and/or p15(INK4B) gene deletions (n=54) were detected in any of the infant ALLs. Therefore, ETV6 and p16(INK4A)/p15(INK4B) do not play a significant role in the pathogenesis of infant ALL, further emphasizing the distinctive biology of this subset of leukemias.

Prognostic significance of fluorescence intensity of surface marker expression in childhood B-precursor acute lymphoblastic leukemia. A Pediatric Oncology Group Study.

This report describes the prognostic significance of the intensity of surface membrane antigen expression in a series of 1,231 children older than 1 year with newly diagnosed B-precursor acute lymphoblastic leukemia (ALL) treated on Pediatric Oncology Group (POG) treatment protocols. All patients had dual-color flow cytometric immunophenotyping performed at a central reference laboratory with a standard panel of monoclonal antibodies. The flow cytometers used in the study were calibrated with a standard fluorescence microparticle that permitted conversion of relative fluorescence channels to standard units of mean equivalents of soluble fluorochrome (MESF). In univariate analysis, fluorescence intensity of CD45 and CD20 was significantly associated with event-free survival (EFS), whereas other markers showed no significant correlation with outcome. Patients whose blasts were greater than the 75th percentile of intensity for CD45 (corresponding to 18,000 MESF units with CD45-FITC, or about 8% of the intensity of normal lymphocytes) fared significantly worse than those with lower-density CD45, and those whose blasts were greater than the 25th percentile of intensity for CD20 (corresponding to 17,900 MESF units with CD20-PE) had a poorer EFS. The intensity of both CD45 and CD20 was independently correlated with outcome. There was no significant correlation between intensity of expression of either antigen and traditional clinical risk factors, ploidy, or t(9;22) or t(1;19). All patients with t(4;11) had CD45 intensity greater than the 75th percentile, but CD45 intensity retained its prognostic significance after adjusting for t(4;11). In multivariate analysis, both CD45 intensity greater than the 75th percentile and CD20 intensity greater than the 25th percentile were significantly correlated with poor outcome independently of previously reported poor prognostic factors including National Cancer Institute (NCI) risk group, ploidy, trisomies of 4 and 10, and adverse translocations including t(1;19), t(9;22), and t(4;11). We conclude that in childhood B-precursor ALL, the intensity of expression of CD20 and CD45 provides prognostic information not available from simple consideration of antigen expression as positive or negative, and adds to that obtained from traditional clinical and biologic risk factors.

Case-control study suggests a favorable impact of TEL rearrangement in patients with B-lineage acute lymphoblastic leukemia treated with antimetabolite-based therapy: a Pediatric Oncology Group study.

TEL gene rearrangement is the most common genetic lesion in pediatric acute lymphoblastic leukemia (ALL), occurring in about 25% of B-lineage cases. We previously showed that, among patients treated on St Jude protocols, TEL rearrangement independently conferred an excellent prognosis. To extend these results to patients treated with antimetabolite-based therapy, we performed Southern blot analysis to determine the TEL gene status of 104 cases of B-lineage ALL treated on Pediatric Oncology Group 8602, matched on age, gender, and leukocyte count. There were 52 failures among the 77 patients with germline TEL, compared with only 8 failures among 27 patients in the rearranged group. Based on a two-sided logistic regression analysis, stratified for age (subdivided at 10 years), leukocyte count (subdivided at 50,000), and gender, the estimated odds of failing by 4 years in the germline TEL group is 5.4 times that of the rearranged TEL group, with 95% confidence from 1.9 to 15.6, two-sided P = .0009. Thus, the presence of a rearranged TEL gene is also associated with an improved survival among patients treated with antimetabolite-based therapy. Our results indicate that all newly diagnosed ALL patients should be screened for TEL gene rearrangements and suggest that these patients are candidates for less intensive therapy.

Therapeutic trial for infant acute lymphoblastic leukemia: the Pediatric Oncology Group experience (POG 8493).

PURPOSE: Despite improved event-free survival of older children with acute lymphocytic leukemia (ALL), infants <1 year of age continue to have a very poor prognosis. A new therapy designed specifically for infants with ALL was initiated. PATIENTS AND METHODS: From 1984 until 1990, 82 eligible infants <1 year of age were entered on a Pediatric Oncology Group (POG) protocol 8493 for infant ALL. Compared to older patients, infants at diagnosis had more overt CNS leukemia (26%), higher initial WBC count (56% >50,000/microl), and a higher likelihood of CD-10 (CALLA) negative lymphoblasts (55%). A translocation involving chromosome 11 at band q23 was detected in 27 of 64 cytogenetically informative cases. Treatment was based upon two institutional pilot studies utilizing chemotherapy doses based upon body weight. Important components included remission induction with cyclophosphamide (Ctx), vincristine (Vcr), cytosine arabinoside (Ara-C), and prednisone (Pred) (COAP); consolidation therapy with teniposide (VM-26) and Ara-C; and continuation therapy with alternating pulses of COAP with VM-26/Ara-C separated by a methotrexate (Mtx) and 6-mercaptopurine (6-MP) backbone plus CNS therapy consisting of standard triple intrathecal therapy (TIT) (Mtx/hydrocortisone/Ara-C), which avoided the use of radiotherapy in this population. RESULTS: Seventy-six infants achieved a complete remission (93%). Fifty patients have relapsed: 35 isolated marrow relapses, five isolated CNS relapses, eight combined marrow and CNS relapses, and two other relapses. Actuarial event-free survival was 28% (SE = 5%) at 4 years. Infants >274 days (9 months) at diagnosis had a better outcome than those <274 days. CONCLUSIONS: This study represents a modest outcome improvement in comparison to previous experience with ALL for infants treated on POG trials. More effective therapy is still needed for infants with ALL.

Changes in red blood cell methotrexate pharmacology and their impact on outcome when cytarabine is infused with methotrexate in the treatment of acute lymphocytic leukemia in children: a pediatric oncology group study.

Since it is unclear whether methotrexate and cytarabine are synergistic or antagonistic in the treatment of acute lymphoblastic leukemia, the Pediatric Oncology Group studied the prognostic significance of a potential interaction between these agents. RBC methotrexate concentrations were compared from 140 patients at lower risk of relapse randomized to two treatment groups: one receiving six methotrexate infusions with overlapping cytarabine; the other, six methotrexate infusions alone. Samples from 248 patients from all risk groups were studied to determine whether patients with extremely low RBC methotrexate concentrations had inferior outcomes. Among low-risk patients studied 3 weeks after the sixth infusion, median RBC methotrexate concentrations were 0.13 nmol/ml RBCs (n = 71) for the methotrexate-only group and 0.02 nmol/ml RBCs (n = 69) for the methotrexate/cytarabine-treated low-risk patients, P < 0.001 by the two-sided Wilcoxon test. For low- and high-risk patients receiving methotrexate/cytarabine infusions, event-free survival at 1 and 3 years after RBC sampling was 97 +/- 2% and 90 +/- 3% for patients with concentrations greater than the median, and 88 +/- 3% and 78 +/- 4% for those with concentrations at or below the median. Log rank comparisons of event-free survival in the first year and overall yielded P = 0.005 and P = 0.04, respectively. Cytarabine altered methotrexate pharmacology when the drugs were infused together. Patients whose levels were extremely low had an adverse prognosis. Although this study could not assess efficacy of the methotrexate/cytarabine combination, it appears that concurrent administration is not optimal.

Comparison of two schedules of intermediate-dose methotrexate and cytarabine consolidation therapy for childhood B-precursor cell acute lymphoblastic leukemia: a Pediatric Oncology Group study.

PURPOSE: To compare efficacy and toxicity of two schedules of intermediate-dose methotrexate (IDM) and cytarabine (Ara-C) in remission consolidation of childhood acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS: In 1986, the Pediatric Oncology Group (POG) began a randomized trial to test two schedules of consolidation chemotherapy in children with newly diagnosed B-precursor cell ALL. MTX and Ara-C were given as overlapping 24-hour infusions. The dose and sequence of MTX and Ara-C administration were based on a preclinical model that had demonstrated synergism between these two agents. Two hundred fifteen patients in complete remission were randomized to front-loading consolidation therapy in which six MTX/Ara-C infusions were administered at 3-week intervals from the 7th through the 19th week of therapy. Two hundred thirteen patients in complete remission were randomized to receive standard consolidation therapy in which the six MTX/Ara-C infusions were given every 12 weeks from the 7th through the 67th week of therapy. RESULTS: Both regimens produced similar rates of adverse side effects, except for a higher incidence of CNS toxicity in individuals randomized to the front-loading arm (32 of 215 v 12 of 213 patients, P = .002). Leukoencephalopathy occurred in three patients on the front-loading regimen and was permanent in one. By Kaplan-Meier analysis, the probability of continuing in complete remission for 5 years was 79% (SE = 5%) and 85% (SE = 5%) for good-risk patients, and 66% (SE = 6%) and 61% (SE = 7%) for poor-risk patients randomized to front-loading and standard regimens, respectively. CONCLUSION: Although differences in complete remission durations were not statistically significant by log-rank analysis (P = .62 for good-risk patients, .89 for poor-risk patients, and .99 overall), the results are comparable to those in previous studies using more toxic agents as components of remission consolidation therapy.

Frequency and prognostic significance of HRX rearrangements in infant acute lymphoblastic leukemia: a Pediatric Oncology Group study.

Chromosome band 11q23, the location of the HRX gene, is a site of recurrent translocations in human malignancies. Infants with acute lymphoblastic leukemia (ALL) commonly have 11q23 translocations and have an especially poor prognosis despite intensive chemotherapy. We analyzed 96 cases of infant ALL treated on three consecutive Pediatric Oncology Group protocols to determine the frequency and prognostic significance of molecular rearrangements of HRX. Overall, 78 cases (81%) had HRX rearrangements detected by Southern blot analysis performed with a single HRX cDNA probe, whereas 18 cases (19%) had germline HRX. Of the 78 cases with HRX rearrangements, only 50 had abnormalities of 11q23 detected cytogenetically. Molecular abnormalities of HRX were associated with early treatment failure and a very poor outcome. Estimated event-free survival for patients with HRX rearrangements was 19% (SE, 7%) at 3 years, compared with 46% (SE, 17%) for patients with germline HRX (P = .033 by the two-sided logrank test). Therefore, infants with ALL and molecular abnormalities of HRX represent a group with an extremely high rate of failure who clearly need innovative or experimental treatment. Furthermore, cytogenetic analysis alone failed to detected 36% of HRX rearrangements, suggesting that molecular analysis be performed on all infants with ALL to identify this group of high-risk patients.