The biology, pathogenesis and clinical aspects of acute lymphoblastic leukemia in children with Down syndrome.

Children with Down syndrome (DS) are at a 20-fold increased risk for acute lymphoblastic leukemia (DS-ALL). Although the etiology of this higher risk of developing leukemia remains largely unclear, the recent identification of CRLF2 (cytokine receptor like factor 2) and JAK2 mutations and study of the effect of trisomy of Hmgn1 and Dyrk1a (dual-specificity tyrosine phosphorylation-regulated kinase 1A) on B-cell development have shed significant new light on the disease process. Here we focus on the clinical features, biology and genetics of ALL in children with DS. We review the unique characteristics of DS-ALL on both the clinical and molecular levels and discuss the differences in treatments and outcomes in ALL in children with DS compared with those without DS. The identification of new biological insights is expected to pave the way for novel targeted therapies.

Second malignancies after autologous hematopoietic cell transplantation in children.

Childhood autologous hematopoietic cell transplant (auto-HCT) survivors can be at risk for secondary malignant neoplasms (SMNs). We assembled a cohort of 1487 pediatric auto-HCT recipients to investigate the incidence and risk factors for SMNs. Primary diagnoses included neuroblastoma (39%), lymphoma (26%), sarcoma (18%), central nervous system tumors (14%) and Wilms tumor (2%). Median follow-up was 8 years (range, <1-21 years). SMNs were reported in 35 patients (AML/myelodysplastic syndrome (MDS)=13, solid cancers=20, subtype missing=2). The overall cumulative incidence of SMNs at 10 years from auto-HCT was 2.60% (AML/MDS=1.06%, solid tumors=1.30%). We found no association between SMNs risk and age, gender, diagnosis, disease status, time since diagnosis or use of TBI or etoposide as part of conditioning. OS at 5-years from diagnosis of SMNs was 33% (95% confidence interval (CI), 16-52%). When compared with age- and gender-matched general population, auto-HCT recipients had 24 times higher risks of developing SMNs (95% CI, 16.0-33.0). Notable SMN sites included bone (N=5 SMNs, observed (O)/expected (E)=81), thyroid (N=5, O/E=53), breast (N=2, O/E=93), soft tissue (N=2, O/E=34), AML (N=6, O/E=266) and MDS (N=7, O/E=6603). Risks of SMNs increased with longer follow-up from auto-HCT. Pediatric auto-HCT recipients are at considerably increased risk for SMNs and need life-long surveillance for SMNs.

Comparison of native E. coli and PEG asparaginase pharmacokinetics and pharmacodynamics in pediatric acute lymphoblastic leukemia.

Asparaginase (ASP) is used routinely in frontline clinical trials for the treatment of childhood acute lymphoblastic leukemia (ALL). The goals of this study were to assess the pharmacokinetics and pharmacodynamics of ASP and to mathematically model the dynamics between ASP and asparagine (ASN) in relapsed ALL. Forty children were randomized to receive either native or polyethylene glycolated (PEG) Escherichia coli ASP during reinduction therapy. Serial plasma ASP and ASN, cerebrospinal fluid (CSF) ASN, and serum anti-ASP antibody samples were collected. The ASP clearance was higher (P = 0.001) for native vs. PEG ASP. Patients with antibodies to PEG ASP had faster PEG ASP clearance (P = 0.004) than did antibody-negative patients. Patients who were positive for antibodies had higher CSF ASN concentrations than did those who were negative (P = 0.04). The modeling suggests that by modifying dosages, comparable ASN depletion is achievable with both preparations. At relapse, there were significant pharmacokinetic and pharmacodynamic differences attributable to ASP preparation and antibody status.

A multi-center phase I study of clofarabine, etoposide and cyclophosphamide in combination in pediatric patients with refractory or relapsed acute leukemia.

This Phase I study of clofarabine with etoposide and cyclophosphamide for children with relapsed/refractory acute lymphoblastic leukemia (ALL) or acute myelogenous leukemia (AML) was conducted to determine the maximum tolerated dose (MTD), dose-limiting toxicities and the recommended phase 2 doses (RP2Ds). All three drugs were administered for five consecutive days in induction and four consecutive days in consolidation, for a maximum of eight cycles. A total of 25 patients (20 ALL and 5 AML) were enrolled in five cohorts. An MTD was not reached. The RP2Ds of clofarabine, cyclophosphamide and etoposide were 40, 440 and 100 mg/m(2)/day, respectively. Complete remission (CR) was achieved in 10 patients (ALL: nine; AML: one), and CR without platelet recovery in six patients (ALL: two; AML: four) for an overall response rate of 64% (ALL: 55%; AML: 100%). Of the 16 responders, 9 patients proceeded to hematopoietic stem cell transplantation. In conclusion, the combination of clofarabine, etoposide and cyclophosphamide was well tolerated and effective in pediatric patients with relapsed/refractory leukemia. Of note, the phase II portion of the trial was amended after the occurrence of unexpected hepatotoxicity. The ongoing phase II study will evaluate the efficacy and safety of this regimen in ALL patients.

Effective treatment of advanced-stage childhood lymphoblastic lymphoma without prophylactic cranial irradiation: results of St Jude NHL13 study.

There has been a steady improvement in cure rates for children with advanced-stage lymphoblastic non-Hodgkin's lymphoma. To further improve cure rates whereas minimizing long-term toxicity, we designed a protocol (NHL13) based on a regimen for childhood T-cell acute lymphoblastic leukemia, which features intensive intrathecal chemotherapy for central -nervous system-directed therapy and excludes prophylactic cranial irradiation. From 1992 to 2002, 41 patients with advanced-stage lymphoblastic lymphoma were enrolled on the protocol. Thirty patients had stage III and 11 had stage IV disease. Thirty-three cases had a precursor T-cell immunophenotype, five had precursor B-cell immunophenotype and in three immunophenotype was not determined. Out of the 41 patients, 39 (95%) achieved a complete remission. The 5-year event-free rate was 82.9+/-6.3% (s.e.), and 5-year overall survival rate was 90.2+/-4.8% (median follow-up 9.3 years (range 4.62-13.49 years)). Adverse events included two induction failures, one death from typhlitis during remission, three relapses and one secondary acute myeloid leukemia. The treatment described here produces high cure rates in children with lymphoblastic lymphoma without the use of prophylactic cranial irradiation.

Genome-wide microRNA expression profiling in renal cell carcinoma: significant down-regulation of miR-141 and miR-200c.

We investigated expression profiles of microRNA (miRNA) in renal cell carcinoma [clear cell carcinomas (CCC) and chromophobe renal cell carcinomas (ChCC)] and in normal kidneys by using a miRNA microarray platform which covers a total of 470 human miRNAs (Sanger miRBase release 9.1). Unsupervised hierarchical cluster analysis revealed that CCC and ChCC were separable and that no subgroups were identified in CCCs. We found that 43 miRNAs were differentially expressed between CCC and normal kidney, of which 37 were significantly down-regulated in CCC and the other 6 were up-regulated. We also found that 57 miRNAs were differentially expressed between ChCC and normal kidney, of which 51 were significantly down-regulated in ChCC and the other 6 were up-regulated. Together, these observations indicate that expression of miRNAs tends to be down-regulated in both CCC and ChCC compared with normal kidney. We observed that miR-141 and miR-200c were the most significantly down-regulated miRNAs in CCCs. Indeed, in all cases of CCC analysed, both miR-141 and miR-200c were down-regulated in comparison with normal kidney. Microarray data and quantitative RT-PCR showed that these two miRNAs were expressed concordantly. TargetScan algorithm revealed that ZFHX1B mRNA is a hypothetical target of both miR-141 and -200c. We established by quantitative RT-PCR that, in CCCs in which miR-141 and miR-200c were down-regulated, ZFHX1B, a transcriptional repressor for CDH1/E-cadherin, tended to be up-regulated. Furthermore, we found that overexpression of miR-141 and miR-200c caused down-regulation of ZFHX1B and up-regulation of E-cadherin in two renal carcinoma cell lines, ACHN and 786-O. On the basis of these findings, we suggest that down-regulation of miR-141 and miR-200c in CCCs might be involved in suppression of CDH1/E-cadherin transcription via up-regulation of ZFHX1B.

Genome-wide analysis of DNA copy number alterations and gene expression in gastric cancer.

Genomic copy number aberrations (CNAs) are believed to play a major role in the development and progression of human cancers. Although many CNAs have been reported in gastric cancer, their genome-wide transcriptional consequences are poorly understood. In this study, to reveal the impact of CNAs on genome-wide expression in gastric cancer, we analysed 30 cases of gastric cancers for their CNAs by array comparative genomic hybridization (array CGH) and 24 of these 30 cases for their expression profiles by oligonucleotide-expression microarray. We found that with the application of laser microdissection, most CNAs were detected at higher frequency than in previous studies. Notably, gain at 20q13 was detected in almost all cases (97%), suggesting that this may play an important role in the pathogenesis of gastric cancer. By comparing the array CGH data with expression profiles of the same samples, we showed that both genomic amplification and deletion strongly influence the expression of genes in altered genomic regions. Furthermore, we identified 125 candidate genes, consisting of 114 up-regulated genes located in recurrent regions (>10%) of amplification and 11 down-regulated genes located in recurrent regions of deletion. Up-regulation of several candidate genes, such as CDC6, SEC61G, ANP32E, BYSL and FDFT1, was confirmed by immunohistochemistry. Interestingly, some candidate genes were localized at genomic loci adjacent to well-known genes such as EGFR, ERBB2 and SMAD4, and concordantly deregulated by genomic alterations. Based on these results, we propose that our list of candidate genes may contain novel genes involved in the pathogenesis of advanced gastric cancer.

Successive clinical trials for childhood acute myeloid leukemia at St Jude Children's Research Hospital, from 1980 to 2000.

Despite substantial progress in the management of childhood acute myeloid leukemia (AML), only about 50% of patients are cured by intensive chemotherapy. The long-term results of clinical trials may reveal principles that can guide the development of future therapy. From 1980 to 2000, 251 patients <15 years of age with newly diagnosed AML were enrolled on one of the five consecutive St Jude AML studies. The median age of the 128 boys and 123 girls was 6.2 years; 193 were white, 45 black, and 13 of other racial groups. With the exception of one protocol (AML-83), outcomes improved in general over the two decades. The estimated 5-year event-free survival (+/-s.e.) was 30.8+/-5.6% for AML-80; 11.1+/-4.3% for AML-83; 35.9+/-7.4% for AML-87; 43.5+/-6.2% for AML-91; and 45.0+/-11.1% for AML-97. Resistant or relapsed AML caused the great majority of treatment failures. Increasing the intensity of chemotherapy (AML-87) did not improve outcome, partially because of toxicity, nor did prolonging postremission therapy by adding sequential myeloablative (AML-80) or nonmyeloablative (AML-83) chemotherapy cycles. We conclude that subtype-specific therapies are needed to replace the 'one size fits all' strategy of the past two decades.

Overt testicular disease at diagnosis of childhood acute lymphoblastic leukemia: lack of therapeutic role of local irradiation.

To assess the prognosis of overt testicular disease at diagnosis of acute lymphoblastic leukemia, and any therapeutic role of irradiation for this involvement, we reviewed the data of 811 boys treated on St Jude studies Total X--XI (early period) and Total XII-XIV (recent period). In all, 19 boys (2.3%) had testicular disease at diagnosis. In the early period, patients with testicular leukemia had a poorer overall survival (OS) (P=0.003), event-free survival (EFS) (P=0.064), and higher cumulative incidence of relapse (P=0.041) than did other patients. During the recent period, patients with and without overt testicular leukemia did not differ in OS (P=0.257), EFS (P=0.102), or cumulative incidence of relapse (P=0.51). In a multivariate analysis, OS was lower for patients with testicular disease than for those without the involvement in the early period (P=0.047) but not in the recent one (P=0.75). Both patients who received irradiation for residual testicular disease at the end of induction subsequently died of leukemia. Of the other 17 patients who did not receive irradiation, only one developed testicular relapse in combination with bone marrow relapse. In conclusion, the prognostic impact of overt testicular disease has diminished. Irradiation appears to provide no survival advantage to this patient population.