http://repub.eur.nl/res/aut/7810/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/27286/ 2010-10-14T00:00:00Z To define a role for hematopoietic stem cell transplantation (HSCT) in infants with acute lymphoblastic leukemia and rearrangements of the mixed-lineage-leukemia gene (MLL+), we compared the outcome of MLL+patients from trial Interfant-99 who either received chemotherapy only or HSCT. Of 376 patients with a known MLL status in the trial, 297 (79%) were MLL+. Among the 277 of 297 MLL+patients (93%) in first remission (CR), there appeared to be a significant difference in disease-free survival (adjusted by waiting time to HSCT) between the 37 (13%) who received HSCT and the 240 (87%) who received chemotherapy only (P = .03). However, the advantage was restricted to a subgroup with 2 additional unfavorable prognostic features: age less than 6 months and either poor response to steroids at day 8 or leukocytes more than or equal to 300 g/L. Ninety-seven of 297 MLL+patients (33%) had such high-risk criteria, with 87 achieving CR. In this group, HSCT was associated with a 64% reduction in the risk of failure resulting from relapse or death in CR (hazard ratio = 0.36, 95% confidence interval, 0.15-0.86). In the remaining patients, there was no advantage for HSCT over chemotherapy only. In summary, HSCT seems to be a valuable option for a subgroup of infant MLL+acute lymphoblastic leukemia carrying further poor prognostic factors. The trial was registered at www. clinicaltrials.gov as #NCT00015873 and at www.controlled-trials.com as #ISRCTN24251487. http://repub.eur.nl/res/pub/27644/ 2010-04-08T00:00:00Z Acute lymphoblastic leukemia (ALL) in infants (< 1 year) is characterized by a poor prognosis and a high incidence of MLL translocations. Several studies demonstrated the unique gene expression profile associated with MLL-rearranged ALL, but generally small cohorts were analyzed as uniform patient groups regardless of the type of MLL translocation, whereas the analysis of translocationnegative infant ALL remained unacknowledged. Here we generated and analyzed primary infant ALL expression profiles (n = 73) typified by translocations t(4;11), t(11;19), and t(9;11), or the absence of MLL translocations. Our data show that MLL germline infant ALL specifies a gene expression pattern that is different from both MLL-rearranged infantALL and pediatric precursor B-ALL. Moreover, we demonstrate that, apart from a fundamental signature shared by all MLL-rearranged infant ALL samples, each type of MLL translocation is associated with a translocation-specific gene expression signature. Finally, we show the existence of 2 distinct subgroups among t(4;11)-positive infant ALL cases characterized by the absence or presence of HOXA expression, and that patients lacking HOXA expression are at extreme high risk of disease relapse. These gene expression profiles should provide important novel insights in the complex biology of MLL-rearranged infant ALL and boost our progress in finding novel therapeutic solutions. http://repub.eur.nl/res/pub/28052/ 2010-04-01T00:00:00Z http://repub.eur.nl/res/pub/19401/ 2010-03-01T00:00:00Z Background. There is an extreme paucity of pharmacokinetic data for anticancer agents in infants. Therefore, we aimed at characterizing the pharmacokinetics for daunorubicin in infants and examined their relationship to age, body weight, and body surface area. Procedure. Leukemia patients treated according to the Interfant 99 protocol received 30 mg/m2 daunorubicin, with dose reduction to 3/4 for patients 6-12 months old and 2/3 for patients <6 months, respectively. Plasma samples from 21 patients (aged 0.05-1.88 years) were collected and analyzed for daunorubicin and daunorubicinol. Samples from 12 children (age 1.6-18.8 years), who received daunorubicin in an earlier investigation, were used for pharmacokinetic model building using the software NONMEM. Results. Plasma concentration time profiles could be described using a two compartment model. Daunorubicin clearance was 43.9 L hr-1m-2±65% and central volume of distribution 16.4 Lm-2±46%, whereas apparent clearance of daunorubicinol was 19.1 L hr-1m-2±32% and apparent volume of distribution 228 Lm-2±80% (mean± interindividual variability). No age-dependency in any of the BSA-normalized pharmacokinetic parameters was observed. Consequently, due to the empirical dose reduction in infants the overall exposure to daunorubicinol in infants was smaller than would be expected from older children. Patients aged <6 months experienced more infections in the induction phase than the group aged 6-12 months at diagnosis. Other toxicities were similar in both groups. Conclusion. We observed no indication of an age-dependency in the pharmacokinetics of daunorubicin. http://repub.eur.nl/res/pub/27448/ 2010-02-04T00:00:00Z MLL-rearranged acute lymphoblastic leukemia (ALL) represents an unfavorable type of leukemia that often is highly resistant to glucocorticoids such as prednisone and dexamethasone. Because response to prednisone largely determines clinical outcome of pediatric patients with ALL, overcoming resistance to this drug may be an important step toward improving prognosis. Here, we show how gene expression profiling identifies high-level MCL-1 expression to be associated with prednisolone resistance in MLL-rearranged infant ALL, as well as in more favorable types of childhood ALL. To validate this observation, we determined MCL-1 expression with quantitative reverse transcription-polymerase chain reaction in a cohort of MLL-rearranged infant ALL and pediatric noninfant ALL samples and confirmed that high-level MCL-1 expression is associated with prednisolone resistance in vitro. In addition, MCL-1 expression appeared to be significantly higher in MLL-rearranged infant patients who showed a poor response to prednisone in vivo compared with prednisone good responders. Finally, down-regulation of MCL-1 in prednisolone-resistant MLL-rearranged leukemia cells by RNA interference, to some extent, led to prednisolone sensitization. Collectively, our findings suggest a potential role for MCL-1 in glucocorticoid resistance in MLL-rearranged infant ALL, but at the same time strongly imply that high-level MCL-1 expression is not the sole mechanism providing resistance to these drugs. http://repub.eur.nl/res/pub/25332/ 2009-12-24T00:00:00Z MLL-rearranged infant acute lymphoblastic leukemia (ALL) remains the most aggressive type of childhood leukemia, displaying a unique gene expression profile. Here we hypothesized that this characteristic gene expression signature may have been established by potentially reversible epigenetic modifications. To test this hypothesis, we used differential methylation hybridization to explore the DNA methylation patterns underlying MLL-rearranged ALL in infants. The obtained results were correlated with gene expression data to confirm gene silencing as a result of promoter hypermethylation. Distinct promoter CpG island methylation patterns separated different genetic subtypes of MLL-rearranged ALL in infants. MLL translocations t(4;11) and t(11;19) characterized extensively hypermethylated leukemias, whereas t(9;11)-positive infant ALL and infant ALL carrying wild-type MLL genes epigenetically resembled normal bone marrow. Furthermore, the degree of promoter hypermethylation among infant ALL patients carrying t(4; 11) or t(11;19) appeared to influence relapse-free survival, with patients displaying accentuated methylation being at high relapse risk. Finally, we show that the demethylating agent zebularine reverses aberrant DNA methylation and effectively induces apoptosis in MLL-rearranged ALL cells. Collectively these data suggest that aberrant DNA methylation occurs in the majority of MLL-rearranged infant ALL cases and guides clinical outcome. Therefore, inhibition of aberrant DNA methylation may be an important novel therapeutic strategy for MLL-rearranged ALL in infants. http://repub.eur.nl/res/pub/25325/ 2009-10-29T00:00:00Z Acute lymphoblastic leukemia (ALL) diagnosed in the first month of life (congenital ALL) is very rare. Although congenital ALL is often assumed to be fatal, no studies have been published on outcome except for case reports. The present study reports the outcome of 30 patients with congenital ALL treated with the uniform Interfant-99 protocol, a hybrid regimen combining ALL treatment with elements designed for treatment of acute myeloid leukemia. Congenital ALL was characterized by a higher white blood cell count and a strong trend for higher incidence ofMLLrearrangements and CD10-negative B-lineageALLcompared with older infants. Induction failure rate was 13% and not significantly different from that in older infants (7%, P = .14), but relapse rate was significantly higher in congenital ALL patients (2-year cumulative incidence [SE] was 60.0 [9.3] vs 34.2 [2.3], P < .001). Two-year event-free survival and survival of congenital ALL patients treated with this protocol was 20% (SE 9.1%). Early death in complete remission and treatment delays resulting from toxicity were not different. The survival of 17% after last follow-up, combined with a toxicity profile comparable with that in older infants, justifies treating congenital ALL with curative intent. This trial was registered at www.clinicaltrials.gov as no. NCT 00015873, and at www.controlled-trials. com as no. ISRCTN24251487. http://repub.eur.nl/res/pub/24109/ 2009-05-01T00:00:00Z Background. Interfant-99 was an international collaborative treatment protocol for infants with acute lymphoblastic leukemia (ALL). Procedure. We collected data on 103 infants at the time of their first treatment with high-dose methotrexate (HD MTX), 5 g/m2. Children <6 months of age received two-third of the calculated dose based on body surface area (BSA), children 6-12 months three- fourth of the calculated dose, and children >12 months full dose. Results. The median steady-state MTX concentration at the end of the 24-hr infusion was 57.8 mM (range 9.5-313). The median systemic clearance was 6.22 L/hr/m2BSA, and tended to increase with age (P = 0.099). Boys had higher clearance than girls, 6.77 and 5.28 L/hr/ m2(P = 0.030), and tended to have lower median MTX concen-tration at 24 hr. Eight infants had MTX levels below 20 mM, a level judged to be sufficient in B-lineage ALL in children >1 year of age. All infants tolerated the dose well enough to receive a second dose of HD MTX without dose reduction. We found no significant effect on disease-free survival for MTX steady-state concentration, MTX clearance, or time to MTX below 0.2 mM. Conclusions. Our data provide no support for a change in the dosing rules for MTX used in Interfant-99. However, in view of the poor treatment results for infants, one might consider increase in the dose for patients who reach plasma levels below median after the first MTX dose. http://repub.eur.nl/res/pub/15748/ 2009-02-13T00:00:00Z Acute lymphoblastic leukemia (ALL) in infants younger than 1 year is a rare but relatively homogeneous disease (∼80% MLL gene rearranged, ∼70% CD10-negative) when compared with childhood and adult ALL. Several studies in children and adults with ALL have shown that minimal residual disease (MRD) status is a strong and independent prognostic factor. We therefore evaluated the prognostic significance of MRD in infant ALL. Ninety-nine infant patients treated according to the Interfant-99 protocol were included in this study. MRD was analyzed by real-time quantitative PCR analysis of rearranged immunoglobulin genes, T-cell receptor genes and MLL genes at various time points (TP) during therapy. Higher MRD levels at the end of induction (TP2) and consolidation (TP3) were significantly associated with lower disease-free survival. Combined MRD information at TP2 and TP3 allowed recognition of three patients groups that significantly differed in outcome. All MRD-high-risk patients (MRD levels ≥10-4 at TP3; 26% of patients) relapsed. MRD-low-risk patients (MRD level <10-4 at both TP2 and TP3) constituted 44% of patients and showed a relapse-rate of only 13%, whereas remaining patients (MRD-medium-risk patients; 30% of patients) had a relapse rate of 31%. Comparison between the current Interfant-06 stratification at diagnosis and the here presented MRD-based stratification showed that both stratifications recognized different subgroups of patients. These data indicate that MRD diagnostics has added value for recognition of risk groups in infant ALL and that MRD diagnostics can be used for treatment intervention in infant ALL as well.Leukemia advance online publication, 12 February 2009; doi:10.1038/leu.2009.17. http://repub.eur.nl/res/pub/35177/ 2007-10-01T00:00:00Z http://repub.eur.nl/res/pub/35768/ 2007-07-21T00:00:00Z Background: Acute lymphoblastic leukaemia in infants younger than 1 year is rare, and infants with the disease have worse outcomes than do older children. We initiated an international study to investigate the effects of a new hybrid treatment protocol with elements designed to treat both acute lymphoblastic leukaemia and acute myeloid leukaemia, and to identify any prognostic factors for outcome in infants. We also did a randomised trial to establish the value of a late intensification course. Methods: Patients aged 0-12 months were enrolled by 17 study groups in 22 countries between 1999 and 2005. Eligible patients were stratified for risk according to their peripheral blood response to a 7-day prednisone prophase, and then given a hybrid regimen based on the standard protocol for acute lymphoblastic leukaemia, with some elements designed for treatment of acute myeloid leukaemia. Before the maintenance phase, a subset of patients in complete remission were randomly assigned to receive either standard treatment or a more intensive chemotherapy course with high-dose cytarabine and methotrexate. The primary outcomes were event-free survival (EFS) for the initial cohort of patients and disease-free survival (DFS) for the patients randomly assigned to a treatment group. Data were analysed on an intention-to-treat basis. This trial was registered with ClinicalTrials.gov, number NCT 00015873, and at controlled-trials.com, number ISRCTN24251487. Findings: In the 482 enrolled patients who underwent hybrid treatment, 260 (58%) were in complete remission at a median follow-up of 38 (range 1-78) months, and EFS at 4 years was 47·0% (SE 2·6, 95% CI 41·9-52·1). Of 445 patients in complete remission after 5 weeks of induction treatment, 191 were randomised: 95 patients to receive a late intensification course, and 96 to a control group. At a median follow-up of 42 (range 1-73) months, 60 patients in the treatment group and 57 controls were disease-free. DFS at 4 years did not differ between the two groups (60·9% [SE 5·2] for treatment group vs 57·0% [5·5] for controls; p=0·81). During the intensification phase, of 71 patients randomly assigned to the treatment group, and for whom toxicity data were available, 35 (49%) had infections, 21 (30%) patients had mucositis, 22 (31%) patients had toxic effects on the liver, and 2 (3%) had neurotoxicity. All types of rearrangements in the (mixed lineage leukaemia) MLL gene, very high white blood cell count, age of younger than 6 months, and a poor response to the prednisone prophase were independently associated with inferior outcomes. Interpretation: Patients treated with our hybrid protocol, and especially those who responded poorly to prednisone, had higher EFS than most reported outcomes for treatment of infant ALL. Delayed intensification of chemotherapy did not benefit patients. http://repub.eur.nl/res/pub/8242/ 2005-01-01T00:00:00Z Acute lymphoblastic leukemia (ALL) in infants is characterized by rearrangements of the mixed lineage leukemia (MLL) gene, drug resistance, and a poor treatment outcome. Therefore, novel therapeutic strategies are needed to improve prognosis. Recently, we showed that FLT3 is highly expressed in MLL rearranged ALL (MLL). Here we demonstrate FLT3 expression in infants with MLL (n = 41) to be significantly higher compared to both infant (n = 8; P < .001) and noninfant patients with ALL (n = 23; P = .001) carrying germline MLL genes. Furthermore, leukemic cells from infants with MLL were significantly more sensitive to the Fms-like tyrosine kinase 3 (FLT3) inhibitor PKC412 (N-benzoyl staurosporine) than noninfant ALL cells, and at least as sensitive as internal tandem duplication-positive (ITD+) AML cells. Surprisingly, activation loop mutations only occurred in about 3% (1 of 36) of the cases and no FLT3/ITDs were observed. However, measuring FLT3 phosphorylation in infants with MLL expressing varying levels of wild-type FLT3 revealed that high-level FLT3 expression is associated with ligand-independent FLT3 activation. This suggests that infant MLL cells displaying activated FLT3 as a result of overexpression can be targeted by FLT3 inhibitors such as PKC412. However, at concentrations of PKC412 minimally required to fully inhibit FLT3 phosphorylation, the cytotoxic effects were only fractional. Thus, PKC412-induced apoptosis in infant MLL cells is unlikely to be a consequence of FLT3 inhibition alone but may involve inhibition of multiple other kinases by this drug.