Pilot study of idarubicin-based intensive-timing induction therapy for children with previously untreated acute myeloid leukemia: Children's Cancer Group Study 2941

Genomic Variants of Cytarabine Sensitivity Associated with Treatment-Related Mortality in Pediatric AML: A Report from the Children's Oncology Group

PURPOSE

Cytarabine is an effective treatment for AML with associated toxicities including treatment related mortality (TRM). The purpose is to determine the clinical relevance of SNPs identified through the use of HapMap lymphoblastoid cell-based models, in predicting cytarabine response and toxicity in AML.

EXPERIMENTAL DESIGN

We tested clinical significance of SNPs associated with cytarabine sensitivity in children with AML treated on Children's Oncology Group regimens (CCG 2941/2961). Endpoints included overall survival (OS), event-free survival (EFS), and TRM. Patients who received bone marrow transplant were excluded. We tested 124 SNPs associated with cytarabine sensitivity in HapMap cell lines in 348 children to determine whether any associated with treatment outcomes. In addition, we tested five SNPs previously associated with TRM in children with AML in our independent dataset of 385 children.

RESULTS

Homozygous variant genotypes of rs2025501 and rs6661575 had increased in vitro cellular sensitivity to cytarabine and were associated with increased TRM. TRM was particularly increased in children with variant genotype randomized to high-dose cytarabine (rs2025501: P = 0.0024 and rs6661575 P = 0.0188). In analysis of previously reported SNPs, only the variant genotype rs17202778 C/C was significantly associated with TRM (P < 0.0001).

CONCLUSIONS

We report clinical importance of two SNPs not previously associated with cytarabine toxicity. Moreover, we confirm that SNP rs17202778 significantly impacts TRM in pediatric AML. Cytarabine sensitivity genotypes may predict TRM and could be used to stratify to standard versus high-dose cytarabine regimens, warranting further study in prospective AML trials.

Pediatric acute myeloid leukemia: updates on biology, risk stratification, and therapy

PURPOSE OF REVIEW

Despite advances in therapy over the past decades, overall survival for children with acute myeloid leukemia (AML) has not exceeded 70%. In this review, we highlight recent insights into risk stratification for patients with pediatric AML and discuss data driving current and developing therapeutic approaches.

RECENT FINDINGS

Advances in cytogenetics and molecular profiling, as well as improvements in detection of minimal residual disease after induction therapy, have informed risk stratification, which now relies heavily on these elements. The treatment of childhood AML continues to be based primarily on intensive, conventional chemotherapy. However, recent trials focus on limiting treatment-related toxicity through the identification of low-risk subsets who can safely receive fewer cycles of chemotherapy, allocation of hematopoietic stem-cell transplant to only high-risk patients and optimization of infectious and cardioprotective supportive care.

SUMMARY

Further incorporation of genomic and molecular data in pediatric AML will allow for additional refinements in risk stratification to enable the tailoring of treatment intensity. These data will also dictate the incorporation of molecularly targeted therapeutics into frontline treatment in the hope of improving survival while decreasing treatment-related toxicity.

Central nervous system disease in pediatric acute myeloid leukemia: A report from the Children's Oncology Group

BACKGROUND

The prognostic impact of central nervous system (CNS) involvement in children with acute myeloid leukemia (AML) has varied in past trials, and controversy exists over the degree of involvement requiring intensified CNS therapy. Two recent Children's Oncology Group protocols, AAML03P1 and AAML0531, directed additional intrathecal (IT) therapy to patients with CNS2 (≤5 white blood cell [WBC] with blasts) or CNS3 (>5 WBC with blasts or CNS symptoms) disease at diagnosis.

METHODS

We examined disease characteristics and outcomes of the 1,344 patients on these protocols, 949 with CNS1 (no blasts), 217 with CNS2, and 178 with CNS3, with the latter two receiving additional IT therapy.

RESULTS

Young age (P = 0.003), hyperleukocytosis (P < 0.001), and the presence of inversion 16 (P < 0.001) were the only factors more prevalent in patients with CNS2 or CNS3 disease. Complete remission at the end of induction (EOI) 2 was achieved less often in patients with CNS involvement (P < 0.001). From diagnosis, event-free survival (EFS) for patients with CNS involvement was significantly worse (P < 0.001), whereas overall survival (OS) was not (P = 0.16). From the EOI1, there was a higher relapse rate (RR) and worse disease-free survival (DFS), but less impact on OS (CNS1:DFS 58.9%, RR 34.1%, OS 69.3%; CNS2:DFS 53.2%, RR 40.9%, OS 74.7%; CNS3:DFS 45.2%, RR 48.8%, OS 60.8%; P = 0.006, P < 0.001, P = 0.045, respectively). Multivariable analysis showed that independently CNS2 and CNS3 status adversely affected RR and DFS. Traumatic diagnostic lumbar puncture was not associated with worse outcome.

CONCLUSIONS

CNS leukemia confers greater relapse risk despite more aggressive locally directed therapy. Novel approaches need to be investigated in this group of patients.

KIT mutations correlate with adverse survival in children with core-binding factor acute myeloid leukemia

The prevalence and clinical relevance of KIT mutations in childhood core-binding factor (CBF) acute myeloid leukemia (AML) have not been well characterized. In this study, a total of 212 children with de novo AML were enrolled from a Chinese population and 50 (23.5%) of the patients were deemed CBF-AML. KIT mutations were identified in 30% of the CBF-AML cohort. The KIT mutations were clustered in exon 17 and exon 8, and KIT mutations in exons 8 and 17 were correlated with a shorter overall survival (OS) (5-year OS: 30.0 ± 14.5% vs. 73.0 ± 8.5%, p = .007) and event-free survival (EFS) (5-year EFS: 30.0 ± 14.5% vs. 73.0 ± 8.5%, p = .003). Multivariate analysis revealed KIT mutations as an independent risk factor in CBF-AML. Our results suggest that KIT mutations are a molecular marker for an inferior prognosis in pediatric CBF-AML.

Copy-neutral loss of heterozygosity is prevalent and a late event in the pathogenesis of FLT3/ITD AML

Patients with high FLT3 internal tandem duplication allelic ratios (FLT3/ITD-ARs) have a poor prognosis. Single-nucleotide polymorphism/comparative genomic hybridization, single-cell PCR and colony-forming assays were used to evaluate genotypic evolution of high FLT3/ITD-ARs in 85 acute myeloid leukemia (AML) patients. Microarrays were used to examine molecular pathways disrupted in leukemic blasts with high FLT3/ITD-ARs. Copy-neutral loss of heterozygosity (CN-LOH) was identified at the FLT3 locus in diagnostic samples with high FLT3/ITD-ARs (N=11), but not in samples with low FLT3/ITD-ARs (N=24), FLT3-activating loop mutations (N=11) or wild-type FLT3 (N=39). Single-cell assays showed that homozygous FLT3/ITD genotype was present in subsets of leukemic blasts at diagnosis but became the dominant clone at relapse. Less differentiated CD34⁺/CD33⁻ progenitor colonies were heterozygous for FLT3/ITD, whereas more differentiated CD34⁺/CD33⁺ progenitor colonies were homozygous for FLT3/ITD. Expression profiling revealed that samples harboring high FLT3/ITD-ARs aberrantly expressed genes within the recombination/DNA repair pathway. Thus, the development of CN-LOH at the FLT3 locus, which results in high FLT3/ITD-ARs, likely represents a late genomic event that occurs after the acquisition of the FLT3/ITD. Although the etiology underlying the development of CN-LOH remains to be clarified, the disruption in recombination/DNA repair pathway, which is present before the development of LOH, may have a role.

Differences in outcomes of newly diagnosed acute myeloid leukemia for adolescent/young adult and younger patients: a report from the Children's Oncology Group

BACKGROUND

Studies comparing survival of adolescent and young adult (AYA) patients to that of younger patients with newly diagnosed acute myeloid leukemia (AML) have yielded conflicting results. In order to more accurately characterize relative survival and other outcomes of AYA patients, a cross-study analysis was conducted using data from recent trials conducted by the Children's Cancer Group (CCG) and Children's Oncology Group (COG).

METHODS

Data were combined from the CCG-2891, CCG-2941, CCG-2961, and AAML03P1 trials. The data set included 1840 patients, comprising 238 AYA and 1602 younger patients.

RESULTS

Overall survival was not significantly different in the 2 groups (AYA, 49% ± 7% versus younger, 54% ± 3% (± 2 standard errors), P = .058). Relapse was lower in AYA patients (30% ± 7% versus 41% ± 3%, P = .002), but treatment-related mortality (TRM) was higher (25% ± 6% versus 12% ± 2%, P < .001). After adjustment for other factors, older age remained strongly associated with TRM (hazard ratio = 2.30, 95% CI = 1.59-3.33, P < .001). Infection accounted for the excess TRM in AYA patients.

CONCLUSIONS

Survival in AYA and younger patients with newly diagnosed AML is similar; however, older patients are at higher risk for TRM. More effective strategies for preventing mortality from infection in AYA patients are needed.

Outcome of adolescents and young adults with acute myeloid leukemia treated on COG trials compared to CALGB and SWOG trials

BACKGROUND

A retrospective meta-analysis of adolescents and young adults (AYAs) with acute myeloid leukemia (AML) was performed to determine if differences in outcome exist following treatment on pediatric versus adult oncology treatment regimens.

METHODS

Outcomes were compared of 517 AYAs with AML aged 16 to 21 years who were treated on Children's Oncology Group (COG), Cancer and Leukemia Group B (CALGB), and Southwest Oncology Group (SWOG) frontline AML trials from 1986 to 2008.

RESULTS

There was a significant age difference between AYA cohorts in the COG, CALGB, and SWOG trials (median, 17.2 versus 20.1 versus 19.8 years, P < .001). The 10-year event-free survival of the COG cohort was superior to the combined adult cohorts (38% ± 6% versus 23% ± 6%, log-rank P = .006) as was overall survival (45% ± 6% versus 34% ± 7%), with a 10-year estimate comparison of P = .026. However, the younger age of the COG cohort is confounding, with all patients aged 16 to 18 years doing better than those aged 19 to 21 years. Although the 10-year relapse rate was lower for the COG patients (29% ± 6% versus 57% ± 8%, Gray's P < .001), this was offset by a higher postremission treatment-related mortality of 26% ± 6% versus 12% ± 6% (Gray's P < .001). Significant improvements in 10-year event-free survival and overall survival were observed for the entire cohort in later studies.

CONCLUSIONS

Patients treated on pediatric trials had better outcomes than those treated on adult trials, but age is a major confounding variable, making it difficult to compare outcomes by cooperative group.

Randomized trial comparing liposomal daunorubicin with idarubicin as induction for pediatric acute myeloid leukemia: results from Study AML-BFM 2004

AML induction with liposomal daunorubicin (80 mg/m2 per day for 3 days) shows antileukemic activity comparable to idarubicin (12 mg/m2 per day for 3 days). Liposomal daunorubicin promises to be more active in the t(8;21) subgroup and causes less treatment-related toxicity.

A phase I study of liposomal-encapsulated docetaxel (LE-DT) in patients with advanced solid tumor malignancies

BACKGROUND

Docetaxel is a taxane anticancer drug used in a wide variety of solid tumors. Liposomes are versatile drug carriers that may increase drug solubility, serve as sustained release systems, provide protection from drug degradation and toxicities, and help overcome multidrug resistance. This phase I study was conducted to determine the maximum tolerated dose, dose-limiting toxicities (DLTs), pharmacokinetics (PK), and clinical response of liposomal-encapsulated docetaxel (LE-DT) in patients with advanced solid tumor malignancies.

METHODS

LE-DT was administered using a standard 3 + 3 dose escalation schema with dose levels of 50, 65, 85, 110, and 132 mg/m(2) IV on a 3-week cycle. Toxicities were assessed using the NCI-CTCAE version 3.0, and response was assessed using RECIST criteria (version 1.0). PK samples were drawn during cycle 1 and analyzed using a non-compartmental analysis.

RESULTS

Twenty-four patients were treated for 1-30 cycles (median = 4). No DLTs were experienced through dose levels of 50, 65, 85, and 110 mg/m(2). Two out of two patients experienced grade 4 neutropenia at the 132 mg/m(2) dose level. When an additional three patients were treated at the expanded 110 mg/m(2) dose level, two experienced grade 4 neutropenia. The 85 mg/m(2) dose level was reassessed with an expanded group of three additional patients, and only one of three patients experienced grade 4 neutropenia. The protocol was amended to allow G-CSF during cycle 1, and an additional three patients were treated at 110 mg/m(2) with no DLTs experienced. No patient experienced significant neuropathy, even patients treated for 19, 20, and 30 cycles. PK followed a two-compartment elimination pattern; there was no correlation between PK and toxicity. Two patients with thyroid and neuroendocrine cancer had partial responses (PR, 8%), and one patient with non-small-cell lung cancer had an unconfirmed PR. Eight patients (33%) had stable disease lasting more than 3 months, for a clinical benefit rate of 41%.

CONCLUSION

LE-DT was well tolerated with expected toxicities of neutropenia, anemia, and fatigue, but without neuropathy or edema. Clinical benefit (SD + PR) was observed in 41% of the patients. The recommended phase II dose of LE-DT is 85 mg/m(2) without G-CSF or 110 mg/m(2) with G-CSF.

Superior outcome of pediatric acute myeloid leukemia patients with orbital and CNS myeloid sarcoma: a report from the Children's Oncology Group

BACKGROUND

Extramedullary leukemia (EML) is common in pediatric acute myeloid leukemia (AML) and occurs as leukemia cells within the cerebrospinal fluid (CSF) or as a solid tumor (myeloid sarcoma-MS). The effect of MS on survival is unknown.

METHODS

Patients on CCG protocols 2861, 2891, 2941, and 2961 being treated for AML with intensive-timing chemotherapy were classified for the presence of EML (CSF leukemia, CNS-MS, orbital-MS, or non-CNS MS). CSF leukemia was classified as CNS3 (>5 WBC in the CSF with blasts) and non-CSF leukemia as CNS1/2 (<5 WBC in the CSF with or without blasts). Characteristics and outcomes of these patients were compared.

RESULTS

Of the 1,459 total patients, 1,206 (82%) had no EML, 154 (11%) had CSF leukemia, 19 (1%) had CNS-MS, 23 (2%) had orbital-MS, and 57 (4%) had non-CNS MS. The CR rate was significantly higher in patients with orbital-MS and CNS-MS than in those with non-MS and non-CNS MS (96% and 95% vs. 78% and 78%, P = 0.034). Patients with orbital-MS and CNS-MS had significantly higher overall survival than patients with non-CNS MS (92% and 73% vs. 38%, P < 0.001), CNS3 patients (92% and 73% vs. 51, P < 0.001), and CNS1/2 patients (92% and 73% vs. 50%, P < 0.001). Patients with orbital-MS had a significantly lower relapse rate.

CONCLUSION

Patients with MS involving orbital and CNS sites had a significantly better survival than patients with non-CNS MS, with CSF leukemia, or with no EML.

Response-guided induction therapy in pediatric acute myeloid leukemia with excellent remission rate

PURPOSE

To evaluate the early treatment response in children with acute myeloid leukemia (AML) using a response-guided induction strategy that includes idarubicin in the first course.

PATIENTS AND METHODS

All Nordic children with AML younger than 15 years (n = 151) were treated on the Nordic Society for Pediatric Hematology and Oncology (NOPHO) AML 2004 protocol. After the first course of idarubicin, cytarabine, etoposide, and 6-thioguanin, patients with good response were allowed hematologic recovery before the second course, whereas patients with a poor (≥ 15% blasts) or intermediate (5% to 14.9% blasts) were recommended to proceed immediately with therapy. Patients not in remission after the second course received fludarabine, cytarabine, and granulocyte colony-stimulating factor. Poor responders received allogeneic stem-cell transplantation (SCT) as consolidation.

RESULTS

Seventy-four percent of patients had good response, 17% had intermediate response, and 7% had poor response after the first course. The overall remission frequency was 97.4%, with 92% in remission after the second course. The rate of induction death was 1.3%. Patients with an intermediate response had a lower event-free survival of 35% compared with good (61%) and poor responders (82%).

CONCLUSION

The NOPHO-AML 2004 induction strategy gives an excellent remission rate with low toxic mortality in an unselected population. Outcome is worse in patients with intermediate response but may be improved by intensifying consolidation in this group using SCT.

The presence of central nervous system disease at diagnosis in pediatric acute myeloid leukemia does not affect survival: a Children's Oncology Group study

BACKGROUND

The presence of central nervous system (CNS) disease in pediatric acute myeloid leukemia (AML) is often thought to confer a worse prognosis. This study examined the outcome of children with AML who had CNS disease at diagnosis.

METHODS

Patients enrolled on Children's Cancer Group protocols 2861, 2891, 2941, and 2961 being treated for de novo AML were classified for the presence of CNS disease at diagnosis as CNS1 (<5 WBC in the CSF without blasts), CNS2 (<5 WBC in the CSF with blasts), or CNS3 (> or =5 WBC in the CSF with blasts). CNS disease at diagnosis was then analyzed regarding patient characteristics and outcome.

RESULTS

There was an incidence of CNS disease (i.e., CNS3 status) of 11% in the 1,459 patients analyzed in this study. The risk factors found are young age, high white cell count, hepatomegaly or splenomegaly at diagnosis, M4 subtype, chromosome 16 abnormalities, and hyperdiploid cytogenetics. There were no significant differences in overall survival, event free survival, or remission rates between the groups; however, a significant difference was seen between the CNS1 and CNS3 groups in disease free survival and isolated CNS relapse risk.

CONCLUSIONS

Patients with CNS disease at diagnosis have similar survival to those without CNS disease, although they have an increased incidence of isolated CNS relapse. Patients with CNS disease at diagnosis may warrant more aggressive CNS directed therapy.

MDM2 polymorphism increases susceptibility to childhood acute myeloid leukemia: a report from the Children's Oncology Group

BACKGROUND

The variant polymorphism in the gene MDM2, SNP309, leads to increased level of mdm2 protein and subsequent downregulation of p53 tumor suppressor pathway. Presence of this single nucleotide polymorphism (SNP) has been associated with earlier tumorigenesis in patients with Li-Fraumeni syndrome, as well as decreased survival in patients with CLL. In addition, cells homozygous (G/G) for SNP 309 were found to have 10-fold increase resistance to topoisomerase II inhibitors in vitro.

PROCEDURE

We genotyped children (n = 575) with de novo acute myeloid leukemia (AML) treated on three Children's Oncology Group protocols (CCG 2941/2961/AAML 03P1) for the presence of SNP309. Healthy blood donors were genotyped as control population.

RESULTS

The variant G/G genotype was associated with an increased susceptibility to AML (OR 1.5; P = 0.049). However, the presence of the variant allele at SNP309 did not modify disease response or toxicity in children treated on CCG protocols 2941/2961.

CONCLUSIONS

The variant SNP 309 influences susceptibility to pediatric AML, but does not impact overall response to therapy.

Prevalence and prognostic significance of KIT mutations in pediatric patients with core binding factor AML enrolled on serial pediatric cooperative trials for de novo AML

KIT receptor tyrosine kinase mutations are implicated as a prognostic factor in adults with core binding factor (CBF) acute myeloid leukemia (AML). However, their prevalence and prognostic significance in pediatric CBF AML is not well established. We performed KIT mutational analysis (exon 8 and exon 17) on diagnostic specimens from 203 pediatric patients with CBF AML enrolled on 4 pediatric AML protocols. KIT mutations were detected in 38 (19%) of 203 (95% CI, 14%-25%) patient samples of which 20 (52.5%) of 38 (95% CI, 36%-69%) involved exon 8, 17 (45%) of 38 (95% CI, 29%-62%) involved exon 17, and 1 (2.5%; 95% CI, 0%-14%) involved both locations. Patients with KIT mutations had a 5-year event-free survival of 55% (+/- 17%) compared with 59% (+/- 9%) for patients with wild-type KIT (P = .86). Rates of complete remission, overall survival, disease-free survival, or relapse were not significantly different for patients with or without KIT mutations. Location of the KIT mutation and analysis by cytogenetic subtype [t(8;21) vs inv(16)] also lacked prognostic significance. Our study shows that KIT mutations lack prognostic significance in a large series of pediatric patients with CBF AML. This finding, which differs from adult series and a previously published pediatric study, may reflect variations in therapeutic approaches and/or biologic heterogeneity within CBF AML. Two of 4 studies included in this analysis are registered at http://clinicaltrials.gov as NCT00002798 (CCG-2961) and NCT00070174 (COG AAML03P1).

FAS promoter polymorphism: outcome of childhood acute myeloid leukemia. A children's oncology group report

PURPOSE

FAS is a cell surface receptor involved in apoptotic signal transmission. Deregulation of this pathway results in down-regulation of apoptosis and subsequent persistence of a malignant clone. A single nucleotide polymorphism resulting in guanine-to-adenine transition in the FAS promoter region (position -1377) is thought to reduce stimulatory protein 1 transcription factor binding and decrease FAS expression. Previous work has shown increased risk of developing acute myeloid leukemia (AML) in adult patients with a variant allele at this site. The same authors have shown that the presence of an adenine residue rather than a guanine residue at -1,377 bp significantly attenuates transcription factor stimulatory protein 1 binding and may contribute to a reduction in FAS expression and ultimately to the enrichment of apoptosis-resistant clones in AML. We hypothesized that FAS genotype by altering susceptibility to apoptosis might affect outcome of childhood AML therapy.

EXPERIMENTAL DESIGN

Four hundred forty-four children treated for de novo AML on a uniform protocol were genotyped for FAS 1377.

RESULTS

There were no significant differences in overall survival, event-free survival, treatment-related mortality, or relapse rate between patients with FAS 1377GG genotype versus 1377GA/1377AA genotypes.

CONCLUSIONS

FAS 1377 genotype does not alter outcome of de novo AML in children.

Cytidine deaminase genotype and toxicity of cytosine arabinoside therapy in children with acute myeloid leukemia

Cytosine arabinoside (ara-C) is irreversibly deaminated to a non-toxic metabolite by cytidine deaminase (CDA). A common polymorphism, A79C, in the gene encoding cytidine deaminase (CDA) changes a lysine residue to glutamine resulting in decreased enzyme activity. CDA A79C genotypes were determined in 457 children with acute myeloid leukaemia (AML) treated on the Children's Cancer Group (CCG) 2941 and 2961 protocols and analyzed the impact of CDA genotype on therapy outcomes. Postinduction treatment-related mortality (TRM) was significantly elevated in children with the CC genotype (5-year TRM 17 +/- 13% CC vs. 7 +/- 4% AA, 5 +/- 4% AC, P = 0.05). This was more notable in children who received idarubicin, fludarabine, ara-C, and granulocyte colony-stimulating factor (IDA-FLAG; ara-C = 7590 mg/m2) (5-year TRM 24 +/- 21% CC vs. 6 +/- 6% AA, 6 +/- 7% AC, P = 0.07) as consolidation therapy compared to idarubicin, dexamethasone, cytarabine, thioguanine, etoposide and daunomycin (IDA-DCTER; ara-C = 800 mg/m2) (5-year TRM 15 +/- 20% CC vs. 8 +/- 6% AA, 4 +/- 6% AC; P = 0.29). Relapse-free survival was non-significantly increased in children with the CC genotype treated with IDA-FLAG (76 +/- 20% CC vs. 59 +/- 12% AA and 55 +/- 14% AC; P = 0.40). These data indicate that children with a low activity CDA genotype are at increased risk of TRM with ara-C based therapy for AML.

DNA repair polymorphisms and outcome of chemotherapy for acute myelogenous leukemia: a report from the Children's Oncology Group

Polymorphisms of DNA repair genes RAD51 and XRCC3 increase susceptibility to acute myeloid leukemia (AML) in adults, an effect enhanced by deletion of the glutathione-S-transferase M1 (GSTM1) gene. In this study, we genotyped 452 children with de novo AML treated on CCG protocols 2941 and 2961 and compared genotype frequencies with those of normal blood donors, and analyzed the impact of genotype on outcome of therapy. XRCC3 Thr241Met, RAD51 G135C and GSTM1 genotypes did not increase susceptibility to AML when assessed singly. In contrast, when XRCC3 and RAD51 genotypes were examined together a significant increase in susceptibility to AML was seen in children with variant alleles. Analysis of outcome of therapy showed that patients heterozygous for the XRCC3 Thr241Met allele had improved post-induction disease-free survival compared to children homozygous for the major or minor allele, each of whom had similar outcomes. Improved survival was due to reduced relapse in the heterozygous children, and this effect was most marked in children randomized to therapy likely to generate DNA double-strand breaks (etoposide, daunomycin), compared with anti-metabolite (fludarabine, cytarabine) based therapy. In contrast, RAD51 G135C and the GSTM1 deletion polymorphism did not influence outcome of AML therapy in our study population.

Outcomes in CCG-2961, a children's oncology group phase 3 trial for untreated pediatric acute myeloid leukemia: a report from the children's oncology group

CCG-2961 incorporated 3 new agents, idarubicin, fludarabine and interleukin-2, into a phase 3 AML trial using intensive-timing remission induction/consolidation and related donor marrow transplantation or high-dose cytarabine intensification. Among 901 patients under age 21 years, 5-year survival was 52%, and event-free survival was 42%. Survival improved from 44% between 1996 and 1998 to 58% between 2000 and 2002 (P = .005), and treatment-related mortality declined from 19% to 12% (P = .025). Partial replacement of daunomycin with idarubicin in the 5-drug induction combination achieved a remission rate of 88%, similar to historical controls. Postremission survival was 56% in patients randomized to either 5-drug reinduction or fludarabine/cytarabine/idarubicin. For patients with or without a related donor, respective 5-year disease-free survival was 61% and 50% (P = .021); respective survival was 68% and 62% (P = .425). Donor availability conferred no benefit on those with inv(16) or t(8;21) cytogenetics. After cytarabine intensification, patients randomized to interleukin-2 or none experienced similar outcomes. Factors predictive of inferior survival were age more than 16 years, non-white ethnicity, absence of related donor, obesity, white blood cell count more than 100 000 x 10(9)/L, -7/7q-, -5/5q-, and/or complex karyotype. No new agent improved outcomes; experience may have contributed to better results time.

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

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

Clinical implications of FLT3 mutations in pediatric AML

Activating mutations of the FLT3 gene occur because of an internal tandem duplication of the juxta-membrane domain (FLT3/ITD) or point mutation of the activation loop domain (FLT3/ALM). The presence of FLT3 mutations as well as the allelic ratio of FLT3/ITD (ITD-AR, mutant-wild type ratio) may have prognostic significance. FLT3 mutation status of 630 children with de novo acute myeloid leukemia (AML) treated on CCG-2941 and -2961 was determined, and ITD-AR was calculated for patients with FLT3/ITD. Clinical characteristics and outcomes for patients with FLT3/ALM and FLT3/ITD at varying ITD-ARs was determined and compared with those without FLT3 mutations (FLT3/WT). FLT3/ITD and FLT3/ALM were detected in 77 (12%) and 42 (6.7%) of the patients. Progression-free survival (PFS) was similar in patients with FLT3/ALM and FLT3/WT (51% versus 55%, P = .862). In contrast, PFS at 4 years from study entry for patients with FLT3/ITD was inferior to that of patients with FLT3/WT (31% versus 55%, P < .001). PFS decreased with increasing FLT3/ITD-AR (P < .001), and those with ITD-AR greater than 0.4 had a significantly worse PFS than those with lower ITD-AR (16% versus 72%, P = .001) or with FLT3/WT (55%, P < .001). ITD-AR defines the prognostic significance in FLT3/ITD-positive AML, and ITD-AR greater than 0.4 is a significant and independent prognostic factor for relapse in pediatric AML.

FLT3 internal tandem duplication in CD34+/CD33- precursors predicts poor outcome in acute myeloid leukemia

Acute myeloid leukemia (AML) is a clonal disease characterized by heterogeneous involvement of hematopoietic stem cell/progenitor cell populations. Using FLT3 internal tandem duplication (FLT3/ITD) as a molecular marker, we tested the hypothesis that clinical outcome in AML correlates with disease involvement of CD34(+)/CD33(-) precursors. Diagnostic specimens from 24 children with FLT3/ITD-positive AML were sorted by fluorescence-activated cell sorting (FACS), and resultant CD34(+)/CD33(-) and CD34(+)/CD33(+) progenitors were analyzed directly and after colony-forming cell (CFC) assay for the presence of FLT3/ITD. FLT3/ITD was present in all CD34(+)/CD33(+) patient samples. In contrast, FLT3/ITD was detected in CD34(+)/CD33(-) progenitors in only 19 of 24 samples. A bipotent progenitor was affected in a subset of patients, as evidenced by the presence of FLT3/ITD in both granulocyte-macrophage colony-forming unit (CFU-GM) and erythroid burst-forming unit (BFU-E) colonies. Those patients in whom CD34(+)/CD33(-) precursors harbored the FLT3/ITD had worse clinical outcome; actuarial event-free survival (EFS) at 4 years from study entry for those patients with and without FLT3/ITD detection in CD34(+)/CD33(-) progenitors was 11% +/- 14% versus 100% +/- 0%, respectively (P = .002). This study suggests that FLT3/ITD involvement in CD34(+)/CD33(-) precursors is heterogeneous and that detection of the mutation in the less-mature progenitor population may be associated with disease resistance.

Long-term results of children with acute myeloid leukemia: a report of three consecutive Phase III trials by the Children's Cancer Group: CCG 251, CCG 213 and CCG 2891

The Children's Cancer Group (CCG) conducted three Phase III prospective clinical trials for children with de novo acute myeloid leukemia between the years 1979 and 1995. A total of 1903 eligible children ages birth to 21 years of age were enrolled on CCG 251 (n=485), CCG 213 (n=532) and CCG 2891 (n=886). Follow-up is ongoing, with medians of 7.9, 10.9 and 8.6 years, respectively. These three clinical trials developed dose- and time-intensive induction regimens based upon high-dose cytarabine and daunomycin and randomly assigned patients to allogeneic bone marrow transplantation in first remission if an HLA-matched related donor was identified. Despite dose- and time-intensive induction regimens, remission induction rates remained relatively stable at 77-78%. However, overall survival, event-free survival and disease-free survival (DFS) increased for patients receiving intensive-timing induction therapy in comparison to patients who received standard-timing induction, regardless of the type of postremission therapy. Outcomes were best for patients receiving intensive-timing induction followed by matched related donor allogeneic transplantation with DFS of 65+/-9% at 6 years. These three clinical trials have established a strong foundation for the development of future studies focusing on further risk group stratification and the development of novel, molecularly-targeted therapies.

XPD Lys751Gln polymorphism in the etiology and outcome of childhood acute myeloid leukemia: a Children's Oncology Group report

Genetic polymorphisms result in interindividual variation in DNA repair capacity and may, in part, account for susceptibility of a cell to genotoxic agents and to malignancy. Polymorphisms in XPD, a member of the nucleotide excision repair pathway, have been associated with development of treatment-related acute myeloid leukemia (AML) and with poor outcome of AML in elderly patients. We hypothesized that XPD Lys751Gln polymorphism may play a role in causation of AML in children and, as shown in adults, may affect the outcome of childhood AML therapy. Genotyping of 456 children treated for de novo AML was performed at XPD exon 23. Genotype frequencies in patients were compared with healthy control subject frequencies, and patient outcomes were analyzed according to genotype. Gene frequencies in AML patients and healthy controls were similar. There were no significant differences in overall survival (P = .82), event-free survival (P = .78), treatment-related mortality (P = .43), or relapse rate (RR) (P = .92) between patients with XPD751AA versus 751AC versus 751CC genotypes, in contrast to reports in adult AML. These data, representing the only data in pediatric AML, suggest that XPD genotype does not affect the etiology or outcome of childhood AML.

Obesity in pediatric oncology

Today's obesity pandemic began in the United States, spread to Western Europe and other developed regions, and is emerging in developing countries. Its influences on outcomes of childhood cancer are unknown. A recent Children's Oncology Group symposium considered epidemiology of obesity, pharmacology of chemotherapy and outcomes in obese adults with cancer, excess mortality in obese pediatric patients with acute myeloid leukemia (AML), and complications in obese survivors. The salient points are summarized herein. Body mass index (BMI) is the accepted index of weight for height and age. In the US, obesity prevalence (BMI > 95th centile) is increasing in all pediatric age groups and accelerating fastest among black and Hispanic adolescents. Pharmacologic investigations are few and limited: half-life, volume of distribution, and clearance in obese patients vary between drugs. Obese adults with solid tumors generally experience less toxicity, suggesting underdosing. For patients undergoing bone marrow transplantation, obese adults generally experience greater toxicity. In pediatric acute myeloblastic leukemia, obese patients have greater treatment-related mortality (TRM), similar toxicity and relapse rates, and inferior survival compared with patients who are not obese. An excess of female survivors of childhood leukemia who received cranial irradiation are obese. Ongoing treatment effects of childhood cancer may predispose to a sedentary lifestyle. These findings call for measures to prevent obesity, retrospective and prospective studies of chemotherapy pharmacology of analyzed according to BMI and outcomes, additional studies of the obesity impact on outcomes in pediatric cancer, and promotion of a healthy lifestyle among survivors.