[Significance of PAX5 deletion in childhood B-lineage acute lymphoblastic leukemia without reproducible chromosomal abnormalities]

OBJECTIVE

To identify the incidence of PAX5 deletion in childhood B-lineage acute lymphoblastic leukemia (B-ALL) without reproducible chromosomal abnormalities and to investigate the association between PAX5 abnormalities and prognosis of ALL.

METHODS

Multiplex ligation-dependent probe amplification was used to determine the copy numbers of PAX5 gene in children newly diagnosed with B-ALL without reproducible chromosomal abnormalities between April 2008 and April 2013 and controls (children with non-hematologic diseases or tumors). The patients were classifiied into deletion group and non-deletion group based on the presence of PAX5 deletion.

RESULTS

Eighteen (21%) out of 86 children with B-ALL had PAX5 deletion. The deletion group had a significantly higher total white blood cell count at diagnosis than the non-deletion group (P=0.001). The Kaplan-Meier analysis demonstrated that the deletion group had a significantly lower disease-free survival (DFS) rate than the non-deletion group (0.69±0.12 vs 0.90±0.04; P=0.017), but there was no significant difference in the overall survival rate between the two groups (P=0.128). The Cox analysis showed that PAX5 deletion was a risk factor for DFS (P=0.03).

CONCLUSIONS

PAX5 deletion is an independent risk factor for DFS in B-ALL children without reproducible chromosomal abnormalities.

[Significance of IKZF1 gene copy number abnormalities in BCR/ABL-negative B-lineage acute lymphoblastic leukemia in children]

OBJECTIVE

To identify IKZF1 gene copy number abnormalities in BCR/ABL-negative B-lineage acute lymphoblastic leukemia (B-ALL) in children, and to investigate the association between such abnormalities and prognosis.

METHODS

Multiplex ligation-dependent probe amplification (MLPA) was applied to detect IKZF1 gene copy number abnormalities in 180 children diagnosed with BCR/ABL-negative B-ALL. These children were classified into IKZF1 deletion group and IKZF1 normal group according to the presence or absence of IKZF1 gene deletion. The association between IKZF1 copy number abnormalities and prognosis of children with BCR/ABL-negative B-ALL was analyzed retrospectively.

RESULTS

Among 180 children, 27 (15.0%) had IKZF1 deletion; among the 27 children, 4 had complete deletions of 8 exons of IKZF1 gene, 17 had deletion of exon 1, 3 had deletions of exons 4-7, and 3 children had deletions of exons 2-7. Compared with those in the IKZF1 normal group, children in the IKZF1 deletion group had higher white blood cell (WBC) count and percentage of individuals with high risk of minimal residual disease at the first visit. IKZF1 deletions often occurred in BCR/ABL-negative children with no special fusion gene abnormalities. They were frequently accompanied by abnormalities in chromosomes 11, 8, 5, 7, and 21. The analysis with Kaplan-Meier method showed that disease-free survival (DFS) in the IKZF1 deletion group was significantly lower than that in the IKZF1 normal group (0.740 ± 0.096 vs 0.905 ± 0.034; P=0.002). Cox analysis showed that after exclusion of sex, age, initial WBC count, cerebrospinal fluid state at the first visit, prednisone response, and chromosome karyotype, IKZF1 deletion still affected the children's DFS (P<0.05).

CONCLUSIONS

Some children with BCR/ABL-negative B-ALL have IKZF1 deletion, and IKZF1 deletion is an independent risk factor for DFS in children with BCR/ABL-negative B-ALL.

Antibodies: Immunoconjugates and autologous cellular therapy in acute lymphoblastic leukemia

Using a case study of a 57-year-old man with relapsed/refractory precursor-B (pre-B) acute lymphoblastic leukemia (ALL), this review discusses treatment with immunoconjugates and autologous therapy in acute ALL. Three therapies--blinatumomab, inotuzumab, and CAR T cells--are considered here, each with advantages in specific clinical situations. These therapies represent some of the exciting advances that have been made in the treatment of ALL over the last several years.

Minimal residual disease-based treatment is adequate for relapse-prone childhood acute lymphoblastic leukemia with an intrachromosomal amplification of chromosome 21: the experience of the ALL-BFM 2000 trial

BACKGROUND

Recently, the UK CCLG and COG reported that an intrachromosomal amplification of chromosome 21 (iAMP21) in acute lymphoblastic leukemia (ALL) loses its adverse prognostic impact with intensified therapy.

PATIENT AND METHODS

We evaluated the prognosis of iAMP21 among patients from the ALL-BFM (Berlin-Frankfurt-Münster) 2000 trial with 46 of 2 637 (2%) patients iAMP21+.

RESULTS

8-year event-free-survival (EFS, 64 ± 8% vs. 81 ± 1%, p=0.0026) and cumulative incidence of relapse (CIR, 29 ± 8% vs. 14 ± 1%, p=0.008) of the iAMP21 cases were significantly worse compared with non-iAMP21 patients. Within the MRD low-risk group, iAMP21 cases (n=14) had an inferior 8-year EFS (76 ± 12% vs. 92 ± 1%, p=0.0081), but no increased CIR (10 ± 10% vs. 6 ± 1%, p=0.624). Within the MRD intermediate-risk group, iAMP21 cases (n=27) had a worse 8-year EFS (56 ± 11% vs. 78 ± 2%, p=0.0077) and CIR (44 ± 11% vs. 20 ± 2%, p=0.003) with 6/10 relapses occurring after 2 years.

CONCLUSIONS

Conclusively, we believe that there is no necessity for enrolling all iAMP21 patients into the high-risk arm of ongoing ALL-BFM trials because MRD low-risk patients have a moderate relapse risk under current therapy. Whether the increased relapse risk in MRD intermediate-risk patients can be avoided by late treatment intensification remains to be answered by the AIEOP-BFM ALL 2009 trial randomly using protracted pegylated L-asparaginase during delayed intensification and early maintenance.

Targetable kinase-activating lesions in Ph-like acute lymphoblastic leukemia

BACKGROUND

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is characterized by a gene-expression profile similar to that of BCR-ABL1-positive ALL, alterations of lymphoid transcription factor genes, and a poor outcome. The frequency and spectrum of genetic alterations in Ph-like ALL and its responsiveness to tyrosine kinase inhibition are undefined, especially in adolescents and adults.

METHODS

We performed genomic profiling of 1725 patients with precursor B-cell ALL and detailed genomic analysis of 154 patients with Ph-like ALL. We examined the functional effects of fusion proteins and the efficacy of tyrosine kinase inhibitors in mouse pre-B cells and xenografts of human Ph-like ALL.

RESULTS

Ph-like ALL increased in frequency from 10% among children with standard-risk ALL to 27% among young adults with ALL and was associated with a poor outcome. Kinase-activating alterations were identified in 91% of patients with Ph-like ALL; rearrangements involving ABL1, ABL2, CRLF2, CSF1R, EPOR, JAK2, NTRK3, PDGFRB, PTK2B, TSLP, or TYK2 and sequence mutations involving FLT3, IL7R, or SH2B3 were most common. Expression of ABL1, ABL2, CSF1R, JAK2, and PDGFRB fusions resulted in cytokine-independent proliferation and activation of phosphorylated STAT5. Cell lines and human leukemic cells expressing ABL1, ABL2, CSF1R, and PDGFRB fusions were sensitive in vitro to dasatinib, EPOR and JAK2 rearrangements were sensitive to ruxolitinib, and the ETV6-NTRK3 fusion was sensitive to crizotinib.

CONCLUSIONS

Ph-like ALL was found to be characterized by a range of genomic alterations that activate a limited number of signaling pathways, all of which may be amenable to inhibition with approved tyrosine kinase inhibitors. Trials identifying Ph-like ALL are needed to assess whether adding tyrosine kinase inhibitors to current therapy will improve the survival of patients with this type of leukemia. (Funded by the American Lebanese Syrian Associated Charities and others.).

Variation at 10p12.2 and 10p14 influences risk of childhood B-cell acute lymphoblastic leukemia and phenotype

Acute lymphoblastic leukemia (ALL) is the major pediatric cancer diagnosed in economically developed countries with B-cell precursor (BCP)-ALL, accounting for approximately 70% of ALL. Recent genome-wide association studies (GWAS) have provided the first unambiguous evidence for common inherited susceptibility to BCP-ALL, identifying susceptibility loci at 7p12.2, 9p21.3, 10q21.2, and 14q11.2. To identify additional BCP-ALL susceptibility loci, we conducted a GWAS and performed a meta-analysis with a published GWAS totaling 1658 cases and 4723 controls, with validation in 1449 cases and 1488 controls. Combined analysis identified novel loci mapping to 10p12.2 (rs10828317, odds ratio [OR] = 1.23; P = 2.30 × 10(-9)) and 10p14 marked by rs3824662 (OR = 1.31; P = 8.62 × 10(-12)). The single nucleotide polymorphism rs10828317 is responsible for the N215S polymorphism in exon 7 of PIP4K2A, and rs3824662 localizes to intron 3 of the transcription factor and putative tumor suppressor gene GATA3. The rs10828317 association was shown to be specifically associated with hyperdiploid ALL, whereas the rs3824662-associated risk was confined to nonhyperdiploid non-TEL-AML1 + ALL. The risk allele of rs3824662 was correlated with older age at diagnosis (P < .001) and significantly worse event-free survivorship (P < .0001). These findings provide further insights into the genetic and biological basis of inherited genetic susceptibility to BCP-ALL and the influence of constitutional genotype on disease development.

[The abnormal expression of IKZF1 encoded protein-IKAROS in B-ALL children]

OBJECTIVE

To analyze the isoforms of IKAROS in the bone marrow samples from children with acute B-lineage lymphoblastic leukemia (B-ALL) and to investigate the relationship between frequency of dominant-negative (DN) IKAROS isoforms and prognosis of B-ALL, and to preliminarily study the relevant mechanism.

METHODS

A total of 137 children with newly diagnosed B-ALL, who sequentially entered the Department of Hematology and Oncology, Shanghai Children's Medical Center between January 2005 and September 2010, were included in the study. Nest-PCR, Sanger sequencing, and TA cloning were used to analyze the expression of IKAROS isoforms in these children. The relationship between frequency of DN IKAROS isoforms and prognosis of B-ALL was investigated.

RESULTS

Of the 137 children with newly diagnosed B-ALL, 16 had expression of IK6, 14 had expression of IK4, and 2 had expression of IK7. There was significant difference in 2.5-year event-free survival between the cohorts of DN IKAROS and non-DN IKAROS (P=0.01). Analysis of the 10 paired of diagnosis/relapse samples from 10 patients with recurrence showed that 8 of 10 paired diagnosis and relapse samples had inconsistent expression of IKAROS isoforms. The rate of IK6 expression in relapse samples from 21 relapse ALL patients was significantly higher than in the 137 children with newly diagnosed ALL (62% vs 12%, P<0.01).

CONCLUSIONS

Expression of DN IKAROS isoforms can be a poor prognostic factor in B-ALL and is closely associated with recurrence of B-ALL.

Implication of IRF4 aberrant gene expression in the acute leukemias of childhood

The most frequent targets of genetic alterations in human leukemias are transcription factor genes with essential functions in normal blood cell development. The Interferon Regulatory Factor 4 (IRF4) gene encodes a transcription factor important for key developmental stages of hematopoiesis, with known oncogenic implications in multiple myeloma, adult leukemias and lymphomas. Very few studies have reported an association of IRF4 with childhood malignancy, whereas high transcript levels have been observed in the more mature immunophenotype of ALL. Our aim was to investigate the expression levels of IRF4 in the diagnostic samples of pediatric leukemias and compare them to those of healthy controls, in order to determine aberrant gene expression and whether it extends to leukemic subtypes other than the relatively mature ALL subpopulation. Quantitative real-time RT-PCR methodology was used to investigate IRF4 expression in 58 children with acute leukemias, 4 leukemic cell lines and 20 healthy children. We show that aberrant IRF4 gene expression is implicated in a variety of leukemic subtypes; higher transcript levels appear in the more immature B-common ALL subtype and in T-cell than in B-cell leukemias, with the highest expression levels appearing in the AML group. Interestingly, we show that childhood leukemia, irrespective of subtype or cell maturation stage, is characterised by a minimum of approximately twice the amount of IRF4 gene expression encountered in healthy children. A statistically significant correlation also appeared to exist between high IRF4 expression and relapse. Our results show that ectopic expression of IRF4 follows the reverse expression pattern of what is encountered in normal B-cell development and that there might be a dose-dependency of childhood leukemia for aberrantly expressed IRF4, a characteristic that could be explored therapeutically. It is also suggested that high IRF4 expression might be used as an additional prognostic marker of relapse at diagnosis.

Targeting JAK1/2 and mTOR in murine xenograft models of Ph-like acute lymphoblastic leukemia

CRLF2 rearrangements, JAK1/2 point mutations, and JAK2 fusion genes have been identified in Philadelphia chromosome (Ph)-like acute lymphoblastic leukemia (ALL), a recently described subtype of pediatric high-risk B-precursor ALL (B-ALL) which exhibits a gene expression profile similar to Ph-positive ALL and has a poor prognosis. Hyperactive JAK/STAT and PI3K/mammalian target of rapamycin (mTOR) signaling is common in this high-risk subset. We, therefore, investigated the efficacy of the JAK inhibitor ruxolitinib and the mTOR inhibitor rapamycin in xenograft models of 8 pediatric B-ALL cases with and without CRLF2 and JAK genomic lesions. Ruxolitinib treatment yielded significantly lower peripheral blast counts compared with vehicle (P < .05) in 6 of 8 human leukemia xenografts and lower splenic blast counts (P < .05) in 8 of 8 samples. Enhanced responses to ruxolitinib were observed in samples harboring JAK-activating lesions and higher levels of STAT5 phosphorylation. Rapamycin controlled leukemia burden in all 8 B-ALL samples. Survival analysis of 2 representative B-ALL xenografts demonstrated prolonged survival with rapamycin treatment compared with vehicle (P < .01). These data demonstrate preclinical in vivo efficacy of ruxolitinib and rapamycin in this high-risk B-ALL subtype, for which novel treatments are urgently needed, and highlight the therapeutic potential of targeted kinase inhibition in Ph-like ALL.

[Analysis of clinical features and prognostic significance of childhood T-lineage acute lymphoblastic leukemia]

This study was aimed to explore the clinical features and prognosis outcome of childhood T-cell acute lymphoblastic leukemia (T-ALL). The clinical data of 38 cases of newly diagnosed T-ALL from Jan 2005 to Aug 2010 were analyzed retrospectively, and 78 cases of B-ALL with intermediate and high risk were collected as control group, then the sensitive rate of patients to prednisone pretreatment, complete remission (CR) rate at day 33 after induction chemotherapy, relapse rate and 3-year event-free survival (EFS) were compared between T-ALL and B-ALL children. The results showed that no significant statistic difference were found in distribution of age, infiltration of liver, spleen and lymph nodes as well as central nervous system disease, chromosome abnormality, expression level of fusion gene and so on between T-ALL and B-ALL groups (p > 0.05), but there were significant differences in sex and number of cases with WBC count ≥ 50 × 10(9)/L between them (p < 0.05). The sensitive rate of T-ALL and B-ALL patients to prednisone pretreatment was 51.9% and 89.3% respectively (p < 0.05). The ratio failed to achieve CR at day 33 after induction chemotherapy was 15.4% and 8.1% in the two groups (p > 0.05). The relapse rate of T-ALL and B-ALL cases was 30.8% (8/26) and 14.9% (11/74) respectively (p > 0.05). The time from CR to relapse was (9.78 ± 3.48) month and (21.28 ± 14.32) month (p < 0.05). The 3 year EFS of T-ALL cases with intermediate and high risk was (37.5 ± 17.1)% and (22.2 ± 9.8)%, while 3 year EFS of B-ALL cases was (66.7 ± 7)% and (51.7 ± 9.3)% respectively (p < 0.05) according to Kaplan-Meier survival curve. It is concluded that as compared with B-ALL cases, the male ratio and initial WBC count are higher, moreover the early response to prednisone pretreatment and 3 year EFS are poor in T-ALL cases, the prognosis outcome is poor also.

IKZF1 deletions predict a poor prognosis in children with B-cell progenitor acute lymphoblastic leukemia: a multicenter analysis in Taiwan

Despite current risk-directed therapy, approximately 15-20% of pediatric patients with acute lymphoblastic leukemia (ALL) have relapses. Recent genome-wide analyses have identified that an alteration of IKZF1 is associated with very poor outcomes in B-cell progenitor ALL. In this study, we determined the prognostic significance of IKZF1 deletions in patients with childhood ALL. This study analyzed 242 pediatric B-cell progenitor ALL patients in Taiwan. We developed a simple yet sensitive multiplex quantitative PCR coupled with capillary electrophoresis to accurately determine the allele dose of IKZF1, and high resolution melting was used for mutation screening for all coding exons of IKZF1. Twenty-six (10.7%) pediatric B-cell progenitor ALL patients were found to harbor these deletions. Most of the deletions were broader deletions that encompassed exon 3 to exon 6, consistent with previous reports. Genomic sequencing of IKZF1 was carried out in all cases and no point mutations were identified. Patients with IKZF1 deletions had inferior event-free survival (P < 0.001), and overall survival (P = 0.0016). The association between IKZF1 deletions and event-free survival was independent of age, leukocyte count at presentation, and cytogenetic subtype by multivariate Cox analysis (P = 0.003, hazard ratio = 2.45). This study indicates that detection of IKZF1 deletions upon diagnosis of B-cell progenitor ALL may help to identify patients at risk of treatment failure. IKZF1 deletions could be incorporated as a new high-risk prognostic factor in future treatment protocols. To the best of our knowledge, this is the first study to examine the poor prognosis of IKZF1 deletions in an Asian population.

[Prognostic significance of TEL/AML1 rearrangement and its additional genetic changes in Korean childhood precursor B-acute lymphoblastic leukemia]

BACKGROUND

TEL (ETV6)/AML1 (RUNX1) rearrangement is observed in approximately 20-25% of childhood precursor B-ALL and is associated with a favorable outcome. Additional genetic changes, associated with TEL/AML1, are frequently found. We evaluated the prevalence and prognostic significance of TEL/AML1 rearrangement and additional genetic changes in the TEL and AML1 genes in Korean childhood precursor B-ALL.

METHODS

We performed FISH using LSITEL/AML1 ES probe (Vysis, USA) in 123 children diagnosed as having precursor B-ALL and assessed clinical relevance of the TEL/AML1 rearrangement and additional genetic abnormalities.

RESULTS

The frequency of TEL/AML1 was 17.1% (21/123) in patients with precursor B-ALL. TEL/ AML1-positive group showed male predominance (P=0.012) and younger age of onset than TEL/ AML1-negative group by 1.6 yr (P=0.013). The outcome of TEL/AML1-positive group tended to show lower incidences of relapse (1/21 vs 20/102), death (1/21 vs 17/102) and longer event free survival. Among TEL/AML1-positive patients, unrearranged TEL deletion, AML1 gain, and unrearranged TEL deletion combined with AML1 gain were detected in 61.9%, 23.8%, and 9.5%, respectively. There were no significant differences in the clinical features and outcome according to the presence or absence of additional genetic changes.

CONCLUSIONS

The frequency of TEL/AML1 and additional genetic changes in TEL and AML1 is higher than previous studies in Korean children, and in close agreement with usually reported one, 20-25%. TEL/AML1-positive group showed a tendency toward better prognosis. Further study is needed to clarify the prognostic significance of additional changes in TEL and AML1 based on a large sample size.

Outcome of haematopoietic stem cell transplantation for paediatric acute lymphoblastic leukaemia in third complete remission: a vital role for graft-versus-host-disease/ graft-versus-leukaemia effect in survival

Children with acute lymphoblastic leukaemia (ALL) receiving haematopoietic stem cell transplantation (HSCT) in third complete remission (CR3) are at high risk for transplant-related mortality (TRM) and relapse. Twenty-two consecutive children with ALL in CR3 received HSCT between January 1994 and August 2005. Ten patients died of TRM, seven patients relapsed, six did not have graft-versus-host disease (GVHD). Five patients were long-term survivors, (median follow-up, 5.8 years; range 2.9-11.7). Three-year event-free survival was 0.32 (95% confidence interval 0.19 and 0.59). Survivors had moderate to severe GVHD. Allowing some GVHD or exploring means of inducing GVHD should be considered in CR3 patients.

Survivin and its prognostic significance in pediatric acute B-cell precursor lymphoblastic leukemia

BACKGROUND AND OBJECTIVES

Impaired apoptosis, mediated by members of the inhibitor of apoptosis proteins (IAP) family such as survivin, is thought to contribute to leukemic cell survival. In contrast to low expression of survivin in normal differentiated adult tissues, very high levels of survivin have been described in a number of different tumors. Overexpression of survivin was found to correlate with poor prognosis in a variety of cancers including hematologic malignancies. To date, however, there is no information available on the prognostic role of survivin in pediatric precursor B-cell acute lymphocytic leukemia (BCP-ALL), the most frequent malignancy in childhood.

DESIGN AND METHODS

In a retrospective study including 66 pediatric patients we analyzed the impact of survivin protein levels on outcome in BCP-ALL.

RESULTS

Survivin overexpression, with an up to ten-fold increase of the normal level, was detected in 65% of the leukemic samples in contrast to negligible expression in non-malignant hematopoietic cells. Despite considerable variety of expression levels in ALL cells, there was no association of survivin levels with established risk factors. However, patients suffering relapse of disease or death had significantly higher survivin expression than those with a favorable outcome. Overexpression of survivin is a significant prognostic marker for 3 year relapse free, event-free and overall survival, again independent of the established prognostic factors in ALL, such as age and leukocyte count at diagnosis as assessed in multivariate analysis.

INTERPRETATION AND CONCLUSIONS

Overexpression of survivin in BCP-ALL identifies patients with a high risk of early relapse. Upon confirmation in a prospective analysis, survivin expression may, in the future, serve to further refine treatment stratification with intensification of therapy in those patients prone to relapse.

Clearance of minimal residual disease after allogeneic stem cell transplantation and the prediction of the clinical outcome of adult patients with high-risk acute lymphoblastic leukemia

BACKGROUND AND OBJECTIVES

The molecular analysis of minimal residual disease (MRD) may provide information on the risk of recurrence in patients with acute lymphoblastic leukemia (ALL). The aim of this study was to correlate the kinetics of MRD clearance after allogeneic transplantation with the clinical outcome of adults with ALL.

DESIGN AND METHODS

MRD was evaluated by real-time quantitative polymerase chain reaction (RQ-PCR) using probes derived from fusion chimeric genes (BCR/ABL and MLL/AF4) (n=22) or rearrangements of the T-cell receptor or immunoglobulin genes (n=21). Forty-three adult patients with ALL were studied to correlate the kinetics of MRD clearance before and after allogeneic hematopoietic stem cell transplantation.

RESULTS

At 36 months, the overall survival of patients who underwent transplantation in hematologic remission (n= 37) was 80% for those who were PCR-negative before transplantation (n= 12) compared to 49% for PCR-positive patients (n= 25)(p=0.17). For the same patients the cumulative incidence of relapse was 0% and 46%, respectively (p=0.027). Moreover, the relapse rate of patients who were PCR-negative at day +100 after transplantation was remarkably low (7%) compared to that among patients who were PCR-positive (80%, p=0.0006).

INTERPRETATION AND CONCLUSIONS

The kinetics of MRD clearance may help to identify patients at high risk of leukemia relapse after allogeneic stem cell transplantation. Patients not achieving an early molecular remission after transplantation require prompt and appropriate pre-emptive treatments such as infusions of donor lymphocytes or new experimental drugs.

Prognostic significance of CD20 expression in childhood B-cell precursor acute lymphoblastic leukemia

CD20 expression is associated with inferior survival in adults with acute lymphoblastic leukemia (ALL). We analyzed the prognostic impact of CD20 expression in 353 children with B-cell precursor ALL treated in 3 consecutive St Jude Total Therapy studies. CD20 expression (> 20%) was found in 169 patients (48%) and was more frequent in patients between 1 and 10 years of age than in those younger than 1 or older than 10 years (P = .001). None of 14 patients with MLL-AF4 expressed CD20. There was no association between CD20 expression and E2A-PBX, TEL-AML1, ploidy, white blood cell count at diagnosis, or sex. In contrast to the experience in adult ALL, our patients with CD20 expression tended to have a better treatment outcome than those without the expression: 5-year event-free survival 84% +/- 2.9% versus 78% +/- 3.1% (P = .08). These data suggest that CD20 expression is not associated with inferior outcome in pediatric patients treated with contemporary regimens.

Risk- and response-based classification of childhood B-precursor acute lymphoblastic leukemia: a combined analysis of prognostic markers from the Pediatric Oncology Group (POG) and Children's Cancer Group (CCG)

The Children's Cancer Group (CCG) and the Pediatric Oncology Group (POG) joined to form the Children's Oncology Group (COG) in 2000. This merger allowed analysis of clinical, biologic, and early response data predictive of event-free survival (EFS) in acute lymphoblastic leukemia (ALL) to develop a new classification system and treatment algorithm. From 11 779 children (age, 1 to 21.99 years) with newly diagnosed B-precursor ALL consecutively enrolled by the CCG (December 1988 to August 1995, n=4986) and POG (January 1986 to November 1999, n=6793), we retrospectively analyzed 6238 patients (CCG, 1182; POG, 5056) with informative cytogenetic data. Four risk groups were defined as very high risk (VHR; 5-year EFS, 45% or below), lower risk (5-year EFS, at least 85%), and standard and high risk (those remaining in the respective National Cancer Institute [NCI] risk groups). VHR criteria included extreme hypodiploidy (fewer than 44 chromosomes), t(9;22) and/or BCR/ABL, and induction failure. Lower-risk patients were NCI standard risk with either t(12;21) (TEL/AML1) or simultaneous trisomies of chromosomes 4, 10, and 17. Even with treatment differences, there was high concordance between the CCG and POG analyses. The COG risk classification scheme is being used for division of B-precursor ALL into lower- (27%), standard- (32%), high- (37%), and very-high- (4%) risk groups based on age, white blood cell (WBC) count, cytogenetics, day-14 marrow response, and end induction minimal residual disease (MRD) by flow cytometry in COG trials.

The prognostic significance of CDKN2A, CDKN2B and MTAP inactivation in B-lineage acute lymphoblastic leukemia of childhood. Results of the EORTC studies 58881 and 58951

BACKGROUND AND OBJECTIVES

Deletion and methylation of the 9p21 chromosomal region are frequent in childhood acute lymphoblastic leukemia (ALL) but the prognostic significance is controversial. They inactivate CDKN2A, a gene encoding both p16INKa and p14ARF and, in some cases, contiguous genes that may influence chemosensitivity, such as CDKN2B encoding p15INKb or MTAP encoding methylthioadenosine phosphorylase.

DESIGN AND METHODS

CDKN2A inactivation by deletion or methylation was studied using gene dosage and methyl-specific polymerase chain reaction.

RESULTS

Bi-allelic and mono-allelic inactivation were found in, respectively, 38 (17%) and 31 (14%) of 227 children with B-lineage ALL enrolled in EORTC trials. Although CDKN2A inactivation was more often associated with poor prognostic features in B-lineage ALL, it failed to influence the outcome of the patients significantly. Bi-allelic CDKN2B and MTAP co-inactivation were found in 36 (16%) and 24 (11%) of patients, respectively, and did not influence the 6-year event-free survival rate either, even when the analysis was restricted to CDKN2A inactivated ALL.

INTERPRETATION AND CONCLUSIONS

In this study of 227 cases of childhood B-lineage ALL, inactivation of CDKN2A, CDKN2B and MTAP did not influences the patients' outcome.

Prospective analysis of TEL/AML1-positive patients treated on Dana-Farber Cancer Institute Consortium Protocol 95-01

In a retrospective analysis, we previously reported that children whose leukemia cells harbored the TEL/AML1 gene rearrangement have excellent outcomes. From 1996 to 2000, we conducted a prospective study to determine the incidence and outcomes of children with TEL/AML1-positive acute lymphoblastic leukemia (ALL). Children with newly diagnosed ALL were treated on DFCI ALL Consortium Protocol 95-01. Patients were risk stratified primarily by current National Cancer Institute (NCI)-Rome risk criteria. With a median follow-up of 5.2 years, the 5-year event-free survival for TEL/AML1-positive patients was 89% compared with 80% for TEL/AML1-negative B-precursor patients (P = .05). The 5-year overall survival rate was 97% among TEL/AML-positive patients compared with 89% among TEL/AML1-negative patients (P = .03). However, in a multivariable analysis, risk group (age and leukocyte count at diagnosis) and asparaginase treatment group, but not TEL/AML1 status, were found to be independent predictors of outcome. We conclude that TEL/AML1-positive patients have excellent outcomes, confirming our previous findings. However, factors such as age at diagnosis and presenting leukocyte count should be taken into consideration when treating this group of patients.

Genetic abnormalities associated with the t(12;21) and their impact in the outcome of 56 patients with B-precursor acute lymphoblastic leukemia

The ETV6/RUNX1 rearrangement is found in 20-30% of children with B-cell precursor acute lymphoblastic leukemia and is associated with a good outcome. To determine the cytogenetic and molecular abnormalities associated with the ETV6/RUNX1 rearrangement and the influence of this rearrangement in patients' evolution, we analyzed the molecular cytogenetic profiles of 56 children with this rearrangement and B-cell precursor acute lymphoblastic leukemia. Secondary changes detected with conventional cytogenetics and with fluorescence in situ hybridization were found in 71.4% of cases, the most frequent being the loss of the normal ETV6 allele, 12p aberrations, duplication of the fusion gene, and trisomy 21, as in replicating the results of previous studies. In this preliminary series, with a mean follow-up of 69.3 months, secondary abnormalities did not influence patients' outcome. It seems therefore that the prognostic value of the t(12;21) does not vary and that ETV6/RUNX1 rearrangement is an independent indicator of good prognosis.

Molecular detection of minimal residual disease is associated with early relapse in adult acute lymphoblastic leukemia

Several studies in childhood acute lymphoblastic leukemia (ALL) have documented that molecular detection of minimal residual disease (MRD) based on screening for T-cell receptor and immunoglobulin gene rearrangements can identify patients at a high risk of relapse. In our experience, evaluation of MRD in adult ALL can help to identify high risk patients.

High-dose daunorubicin as liposomal compound (Daunoxome) in elderly patients with acute lymphoblastic leukemia

Elderly acute lymphoblastic leukemia (ALL) is a rare condition associated with low complete remission (CR) rate and short survival. In order to improve these results, we evaluate the efficacy and toxicity of Daunoxome, a liposomal daunorubicin, exhibiting toxicity profile and pharmacokinetic indices better than standard daunorubicin. In total, 15 consecutive patients with nonmature ALL were enrolled on a prospective phase II study. No exclusion was made because of older age, poor performance status and organ dysfunctions. Median age was 69 years; performance status resulted >/=2 in nine patients (60%), six patients (40%) were bcr-abl positive and two-thirds of the patients had comorbidities. Induction therapy consisted of vincristine, Daunoxome and dexamethasone. Patients in CR received one or two consolidation cycles of cyclophosphamide, cytarabine and topotecan followed, in patients achieving CR, by a two-year rotating maintenance course including vincristine, Daunoxome, cyclophosphamide and prednisone. In all, 11 patients (73%) achieved CR, three patients (20%) died early during the induction phase and one patient (7%) had resistant disease. Five patients (33%) relapsed after 5-21 months. With a median follow-up of 20 months, disease free survival (DFS) and overall survival (OS) at 2 years were 36 and 38%, respectively. Major toxicity included myelosuppression and infection. Our experience demonstrates that a high dose of daunorubicin as liposomal compound can be safely administered in elderly ALL, exhibiting high antitumor activity. Our therapeutic program shows evidence of benefit in DFS and OS.

DNA microarrays for comparison of gene expression profiles between diagnosis and relapse in precursor-B acute lymphoblastic leukemia: choice of technique and purification influence the identification of potential diagnostic markers

Microarrays for gene expression profiling are rapidly becoming important research tools for the identification of novel markers, for example, for novel classification of leukemias and lymphomas. Here, we review the considerations and infrastructure for microarray experiments. These considerations are illustrated via a microarray-based comparison of gene expression profiles of paired diagnosis-relapse samples from patients with precursor-B acute lymphoblastic leukemia (ALL), who relapsed during therapy or after completion of treatment. Initial experiments showed that several seemingly differentially expressed genes were actually derived from contaminating non-leukemic cells, particularly myeloid cells and T-lymphocytes. Therefore, we purified the ALL cells of the diagnosis and relapse samples if their frequency was lower than 95%. Furthermore, we observed in earlier studies that extra RNA amplification leads to skewing of particular gene transcripts. Sufficient (non-amplified) RNA of purified and paired diagnosis-relapse samples was obtained from only seven cases. The gene expression profiles were evaluated with Affymetrix U95A chips containing 12 600 human genes. These diagnosis-relapse comparisons revealed only a small number of genes (n=6) that differed significantly in expression: mostly signaling molecules and transcription factors involved in cell proliferation and cell survival were highly upregulated at relapse, but we did not observe any increase in drug-resistance markers. This finding fits with the observation that tumors with a high proliferation index have a poor prognosis. The genes that changed between diagnosis and relapse are currently not in use as diagnostic or disease progression markers, but represent potential new markers for such applications. Leukemia (2003) 17, 1324-1332. doi:10.1038/sj.leu.2402974

Methotrexate polyglutamation may lack prognostic significance in children with B-cell precursor acute lymphoblastic leukemia treated with intensive oral methotrexate

BACKGROUND

The purpose of this study was to determine if a correlation exists between clinical outcome and accumulation and polyglutamation of methotrexate by lymphoblasts in vitro in children with B-cell precursor acute lymphoblastic leukemia (BCP-ALL).

PATIENTS AND METHODS

The amount of accumulated methotrexate and of long-chain methotrexate polyglutamates (MTXPG(3-7)) by lymphoblasts was determined in 52 children newly diagnosed with BCP-ALL after incubation with 1 micromol/L [(3)H]MTX for 24 hours in vitro. All patients then received intensive multiagent chemotherapy that used divided-dose oral methotrexate during consolidation and intensive continuation and standard oral weekly methotrexate during maintenance.

RESULTS

Eight patients had a bone marrow relapse at a median of 40.4 months (range 18.5-48.3 months) after diagnosis. The median follow-up for the remaining 44 patients is 69.0 months (range 22-92.8 months). There was no significant difference in the amount of accumulated methotrexate (1450.0 +/- 896.3 vs. 640 +/- 472.5 pmol/10 cells) or of accumulated MTXPG (1450.0 +/- 919.4 vs. 617.4 +/- 482.7 pmol/10(9) cells) (median +/- semi-interquartile ranges) between patients who relapsed and those who remained in continuous complete remission. The estimated 5-year event-free survival rate for patients whose lymphoblasts accumulated more than 500 pmol MTXPG(3-7)/10(9) cells was 80.0% +/- 7.3% versus 90.5% +/- 6.4% for those whose lymphoblasts accumulated less than 500 pmol MTXPG(3-7)/10(9) cells.

CONCLUSIONS

In the context of effective prolonged divided-dose oral methotrexate-based therapy in the treatment of BCP-ALL, methotrexate accumulation and polyglutamation no longer seem to have prognostic significance.