Long-term sequelae of therapy for childhood acute lymphoblastic leukaemia

Short stature in retinoblastoma survivors: a cross-sectional study of 138 patients

PURPOSE

Short stature has been reported in pediatric cancer survivors. Data on retinoblastoma survivors are limited. We conducted a cross-sectional study to assess the height in retinoblastoma survivors.

METHOD

The recorded height was compared with median height for age and sex as per the Indian Academy of Pediatrics. Z-score less than -2 was considered short statured.

RESULT

Thirty percent of the survivors were short statured. The mean height was shorter than the mean 50th percentile height (119.7 ± 14.8 vs 128.7 ± 15 cm, p < 0.001). Previous chemotherapy showed a trend toward association (p = 0.09).

CONCLUSION

Short stature affects a significant number of retinoblastoma survivors.

Potential toxicities of prophylactic cranial irradiation

Prophylactic cranial irradiation (PCI) with total doses of 20-30 Gy reduces the incidence of brain metastasis (BM) and increases survival of patients with limited and extensive-disease small-cell lung cancer (SCLC) that showed any response to chemotherapy. PCI is currently not applied in non-small-cell lung cancer (NSCLC) since it has not proven to significantly improve OS rates in stage IIIA/B, although novel data suggest that subgroups that could benefit may exist. Here we briefly review potential toxicities of PCI which have to be considered before prescribing PCI. They are mostly difficult to delineate from pre-existing risk factors which include preceding chemotherapy, patient age, paraneoplasia, as well as smoking or atherosclerosis. On the long run, this will force radiation oncologists to evaluate each patient separately and to estimate the individual risk. Where PCI is then considered to be of benefit, novel concepts, such as intensity-modulated radiotherapy and/or neuroprotective drugs with potential to lower the rates of side effects will eventually be superior to conventional therapy. This in turn will lead to a re-evaluation whether benefits might then outweigh the (lowered) risks.

Bone turnover in long-term survivors of childhood acute lymphoblastic leukemia

BACKGROUND

We investigated the effects of demographic, lifestyle (self-reported smoking status and physical activity levels), cancer-related treatment factors (radiation and chemotherapy), and diet (calcium and vitamin D intake) on bone turnover and the relationship of bone turnover to lumbar spine bone mineral density (BMD) Z-scores (LS-BMD Z-scores) determined by quantitative computed tomography (QCT) in 418 ≥5-year survivors of childhood acute lymphoblastic leukemia (ALL).

PROCEDURE

Bone turnover was assessed by biomarkers including serum bone-specific alkaline phosphatase (BALP), osteocalcin (OC), and urinary N-telopeptide of type I collagen indexed to creatinine (NTX/Cr). The 215 males ranged in age from 9 to 36 years (median age 17 years).

RESULTS

Age and tanner score were inversely associated with all biomarkers (BALP, OC, NTX/Cr) (P < 0.001). Males had higher BALP and OC than females (P < 0.001). Body mass index (BMI) was inversely associated with OC and NTX/Cr (P < 0.001). There was no significant association of biomarkers with lifestyle related factors, ALL treatment-related factors, dietary calcium, vitamin D, or LS-BMD Z-score.

CONCLUSIONS

In this population of long-term survivors of ALL, bone turnover was significantly associated with age, gender, tanner stage, and BMI. ALL-related treatments did not influence bone turnover and bone turnover was not predictive of volumetric LS-BMD Z-score.

Prediction of methotrexate CNS distribution in different species - influence of disease conditions

Children and adults with malignant diseases have a high risk of prevalence of the tumor in the central nervous system (CNS). As prophylaxis treatment methotrexate is often given. In order to monitor methotrexate exposure in the CNS, cerebrospinal fluid (CSF) concentrations are often measured. However, the question is in how far we can rely on CSF concentrations of methotrexate as appropriate surrogate for brain target site concentrations, especially under disease conditions. In this study, we have investigated the spatial distribution of unbound methotrexate in healthy rat brain by parallel microdialysis, with or without inhibition of Mrp/Oat/Oatp-mediated active transport processes by a co-administration of probenecid. Specifically, we have focused on the relationship between brain extracellular fluid (brainECF) and CSF concentrations. The data were used to develop a systems-based pharmacokinetic (SBPK) brain distribution model for methotrexate. This model was subsequently applied on literature data on methotrexate brain distribution in other healthy and diseased rats (brainECF), healthy dogs (CSF) and diseased children (CSF) and adults (brainECF and CSF). Important differences between brainECF and CSF kinetics were found, but we have found that inhibition of Mrp/Oat/Oatp-mediated active transport processes does not significantly influence the relationship between brainECF and CSF fluid methotrexate concentrations. It is concluded that in parallel obtained data on unbound brainECF, CSF and plasma concentrations, under dynamic conditions, combined with advanced mathematical modeling is a most valid approach to develop SBPK models that allow for revealing the mechanisms underlying the relationship between brainECF and CSF concentrations in health and disease.

Experience with high dose methotrexate therapy in childhood acute lymphoblastic leukemia in a tertiary care cancer centre of a developing country

BACKGROUND

Intensification of systemic chemotherapy with inclusion of high dose methotrexate (HDMTX) has helped omit cranial irradiation from standard risk acute lymphoblastic leukemia (ALL) protocols, thereby eliminating the adverse side effects associated with its use. Administration of HDMTX needs meticulous monitoring. Limitations in the availability of trained staff and adequate infrastructure often pose problems in the developing world. The aim of this study was (1) to treat childhood ALL with a protocol that would have reduced use of cranial irradiation and containing infusions of high-dose methotrexate HDMTX (5 g/m(2)) without compromising on survival, and (2) evaluate the experience with HDMTX in a tertiary care cancer centre in a developing country.

METHODS

A retrospective chart review was done of 41 consecutive children with a confirmed diagnosis of ALL who had received at least one cycle of HDMTX as part of their consolidation treatment with regard to the patient demographic profile, details of HDMTX infusion and leucovorin rescue, toxicity, additional hospitalization, delay in next cycle of chemotherapy and survival.

RESULTS

The clinically most significant toxicities observed were mucositis 39% (58/149) and fever 28% (42/149) together leading to additional hospital stay in 7% (11/149) cycles and neutropenia grade 3 or more in 24.8% (34/137) contributing to delay in next cycle of chemotherapy in 15% (23/149) cycles.

CONCLUSION

With this strategy, it was possible to omit or reduce the dose of cranial irradiation while maintaining survival outcomes. The administration of HDMTX therapy was found to be feasible and safe with the precautions described.

Assessment of bone mineral density and risk factors in children completing treatment for acute lymphoblastic leukemia

BACKGROUND

Reduced bone mineral density and increased fracture risk have been reported in children with cancer. In this study, we aimed to determine the growth and bone mineral density (BMD) of the children off chemotherapy for acute lymphoblastic leukemia, and the probable risk factors.

PROCEDURE

The age, anthropometric measurements, lumbar spine BMDs were recorded in 70 children. The risk factors on BMD; daily calcium intake, the time interval from the completion of the chemotherapy, cranial radiotherapy, cumulative steroid dose, decrease in physical activity were investigated. Serum calcium, phosphate, alkaline phosphates, magnesium, insulin-like growth factor-1 (IGF-1) and 25 (OH) vitamin D levels were determined.

RESULTS

The mean height percentile at the time of diagnosis was decreased from the value of 53 to a value of 47 at the beginning of the study (P=0.071). Of them; 44% had osteoporosis, 41% had osteopenia, and the rest had normal BMD. BMD z-scores were decreased during the first 2 years from the completion of the treatment. There was a positive correlation between BMD z-scores and daily calcium intake (CC=0.366, P=0.0015). A negative correlation was determined between the time spent on TV and computers and BMD z-scores (CC=-0.464, P=0.0019). Serum IGF-1 and 25 (OH) vitamin D levels of patients were significantly lower than controls (P=0.033).

CONCLUSIONS

Our data revealed that 85% of the survivors had bone mineralization defect. BMDs and z scores were decreased during the first 2 years from the completion of the treatment and then gradually began to increase. The most important risk factor for decreased BMD was low daily calcium intake. Therefore, patients and their families should be encouraged to take sufficient amount of calcium. Prophylactic vitamin D may also be supplemented.

Therapeutic targeting of NOTCH1 signaling in T-cell acute lymphoblastic leukemia

The recent identification of activating mutations in NOTCH1 in the majority of T-cell acute lymphoblastic leukemias (T-ALLs) has brought major interest toward targeting the NOTCH signaling pathway in this disease. Small-molecule gamma-secretase inhibitors (GSIs), which block a critical proteolytic step required for NOTCH1 activation, can effectively block the activity of NOTCH1 mutant alleles. However, the clinical development of GSIs has been hampered by their low cytotoxicity against human T-ALL and the development of significant gastrointestinal toxicity derived from the inhibition of NOTCH signaling in the gut. Improved understanding of the oncogenic mechanisms of NOTCH1 and the effects of NOTCH inhibition in leukemic cells and the intestinal epithelium are required for the design of effective anti-NOTCH1 therapies in T-ALL.

Intrathecal triple therapy decreases central nervous system relapse but fails to improve event-free survival when compared with intrathecal methotrexate: results of the Children's Cancer Group (CCG) 1952 study for standard-risk acute lymphoblastic leukemia, reported by the Children's Oncology Group

The Children's Cancer Group (CCG) 1952 clinical trial for children with standard-risk acute lymphoblastic leukemia (SR-ALL) compared intrathecal (IT) methotrexate (MTX) with IT triples (ITT) (MTX, cytarabine, and hydrocortisone sodium succinate [HSS]) as presymptomatic central nervous system (CNS) treatment. Following remission induction, 1018 patients were randomized to receive IT MTX and 1009 ITT. Multivariate analysis identified male sex, hepatomegaly, CNS-2 status, and age younger than 2 or older than 6 years as significant predictors of isolated CNS (iCNS) relapse. The 6-year cumulative incidence estimates of iCNS relapse are 3.4% +/- 1.0% for ITT and 5.9% +/- 1.2% for IT MTX; P = .004. Significantly more relapses occurred in bone marrow (BM) and testicles with ITT than IT MTX, particularly among patients with T-cell phenotype or day 14 BM aspirate containing 5% to 25% blasts. Thus, the estimated 6-year event-free survivals (EFS) with ITT or IT MTX are equivalent at 80.7% +/- 1.9% and 82.5% +/- 1.8%, respectively (P = .3). Because the salvage rate after BM relapse is inferior to that after CNS relapse, the 6-year overall survival (OS) for ITT is 90.3% +/- 1.5% versus 94.4% +/- 1.1% for IT MTX (P = .01). It appears that ITT improves presymptomatic CNS treatment but does not improve overall outcome.

Impact of Cranial Radiotherapy on Central Nervous System Prophylaxis in Children and Adolescents With Central Nervous System–Negative Stage III or IV Lymphoblastic Lymphoma

Purpose

In the Non-Hodgkin's Lymphoma–Berlin-Frankfurt-Munster (NHL-BFM) 95 trial, we tested, against the historical control of the combined trials NHL-BFM90 and NHL-BFM86, whether prophylactic cranial radiotherapy (PCRT) can be omitted for CNS-negative patients with stage III or IV lymphoblastic lymphoma (LBL) with sufficient early response.

Patients and Methods

Apart from the removal of PCRT in NHL-BFM95, the chemotherapy of the three trials was identical except for the amount of l-asparaginase and daunorubicin during induction. The therapy in NHL-BFM95 was accepted to be noninferior when compared with trials NHL-BFM90/86 if the lower limit of the one-sided 95% CI for the difference in the 2-year probability of event-free-survival (pEFS) between target patients of NHL-BFM95 and the historical controls of NHL-BFM90/86 did not exceed −14%. The target patient group consisted of stage III and IV patients who were CNS negative and responded well to induction therapy.

Results

The number of target patients was 156 in NHL-BFM95 (median age, 8.6 years; range, 0.2 to 19.5 years) and 163 in NHL-BFM90/86 (median age, 8.4 years; range, 0.6 to 16.6 years). For the target group, the pEFS rates at 2 and 5 years were 86% ± 3% and 82% ± 3%, respectively, in NHL-BFM95 (median follow-up time, 5.1 years; range, 2.1 to 9.1 years) compared with 91% ± 2% and 88% ± 3%, respectively in NHL-BFM90/86 (median follow-up time, 10.7 years; range, 5 to 15.4 years). The lower limit of the one-sided 95% CI for the difference in pEFS was −11% at 2 years and −13% at 5 years. In NHL-BFM95, one isolated and two combined CNS relapses occurred compared with one combined CNS relapse in NHL-BFM90/86. Five-year disease-free-survival rate was 88% ± 3% in NHL-BFM95 compared with 91% ± 2% in NHL-BFM90/86.

Conclusion

For CNS-negative patients with stage III or IV LBL and sufficient response to induction therapy, treatment without PCRT may be noninferior to treatment including PCRT.

Utility of cranial boost in addition to total body irradiation in the treatment of high risk acute lymphoblastic leukemia

PURPOSE

Total body irradiation (TBI) as part of a conditioning regimen before hematopoietic stem cell transplant (HSCT) is an important component in the management of acute lymphoblastic leukemia (ALL) that has relapsed or has other certain high-risk features. Controversy exists, however, as to whether a cranial boost in addition to TBI is necessary to prevent central nervous system (CNS) recurrences in these high-risk cases. Previous national trials have included a cranial boost in the absence of data to justify its use. Therefore, the aim of this study was to assess risk of CNS recurrence in ALL patients treated with TBI, to identify subsets of these high-risk patients at an increased or decreased risk of CNS recurrence after TBI, and to investigate whether regimens with higher doses of cranial irradiation further reduce the risk of CNS recurrence.

METHODS AND MATERIALS

Charts of 67 consecutively treated patients with ALL who received TBI before HSCT were reviewed. Data including patient demographics, clinical features at presentation, conditioning regimen, donor source, use of a cranial boost, remission stage at transplant, histologic subtype, cytogenetics, and extramedullary site of presentation were retrospectively collected and correlated with the risk of subsequent CNS recurrence.

RESULTS

At the time of analysis, 30 (45%) patients were alive with no evidence of disease, 8 (12%) were alive with recurrence of leukemia, 7 (10.5%) had recurrent ALL but with successful salvage, 7 (11%) died subsequent to recurrence, 14 (21%) died from complications related to HCST, and 1 patient was lost to follow-up (1.5%). Of the patients who recurred after HSCT, the relapses were hematologic in 13 (57%), CNS with or without simultaneous marrow involvement in 3 (13%), and other sites in 7 (30%). Forty-one (61%) patients did not receive an extracranial boost of irradiation with TBI. Two of these patients (4.9%) suffered CNS failures compared with 1 of 26 (3.8%) who received a cranial boost (p = 0.84). None of the 40 patients who presented only with hematologic disease developed a CNS recurrence despite the fact that only 13 of 40 of these patients received a cranial boost after TBI. Cranial boost was therefore not associated with a reduction in CNS recurrence, especially in patients with only hematologic disease at presentation for which there were no failures regardless of the use of additional cranial radiotherapy.

CONCLUSIONS

Patients who present with hematologic disease only at the time of HSCT have a low risk of CNS recurrence after TBI regardless of the use of a cranial boost, suggesting that a cranial boost may not be necessary in these patients.

Successful treatment without cranial radiotherapy of children receiving intensified chemotherapy for acute lymphoblastic leukaemia: results of the risk-stratified randomized central nervous system treatment trial MRC UKALL XI (ISRC TN 16757172)

Concern about late adverse effects of cranial radiotherapy (XRT) has led to alternative approaches to eliminate leukaemia from the central nervous system (CNS) in childhood acute lymphoblastic leukaemia (ALL). The Medical Research Council UKALL XI trial recruited 2090 children with ALL between 1990 and 1997. Median follow-up is 7 years 9 months; event-free survival (EFS) and overall survival were 63.1% and 84.6%, respectively, at 5 years and 59.8% and 79.4% at 10 years. The isolated CNS relapse rate was 7.0% at 10 years. Patients were randomized for CNS-directed therapy within white blood cell (WBC) groups. For WBC <50 x 10(9)/l, high-dose intravenous methotrexate (HDMTX) (6-8 g/m2) with intrathecal methotrexate (ITMTX) was compared with ITMTX alone, and was significantly better at preventing isolated and combined CNS relapse, but non-CNS relapses were similar. There was no significant difference in EFS at 10 years, 64.1% [95% confidence interval (CI) 60.4-67.8] with HDMTX plus ITMTX, and 63.0% (95% CI 59.5-66.5) with ITMTX alone. For WBC >/=50 x 10(9)/l, HDMTX with ITMTX was compared with XRT and a short course of ITMTX. CNS relapses were significantly fewer with XRT, but there was a non-significant increase in non-CNS relapses. EFS was not significantly different, being 55.2% (95% CI 47.8-62.6) at 10 years with XRT and 52.1% (95% CI 44.8-59.4) with HDMTX plus ITMTX.

Growth and puberty after treatment for acute lymphoblastic leukemia

Over the last 20 years, after combining treatment of chemotherapy and radiotherapy, there has been an improvement in the survival rate of acute lymphoblastic leukemia patients, with a current cure rate of around 70%. Children with the disease have been enrolled into international treatment protocols designed to improve survival and minimize the serious irreversible late effects. Our oncology unit uses the international protocol: GBTLI LLA-85 and 90, with the drugs methotrexate, cytosine, arabinoside, dexamethasone, and radiotherapy. However, these treatments can cause gonadal damage and growth impairment. PATIENTS AND METHOD: The authors analyzed 20 children off therapy in order to determine the role of the various doses of radiotherapy regarding endocrinological alterations. They were divided into 3 groups according to central nervous system prophylaxis: Group A underwent chemotherapy, group B underwent chemotherapy plus radiotherapy (18 Gy), and group C underwent chemotherapy plus radiotherapy (24 Gy). Serum concentrations of LH, FSH, GH, and testosterone were determined. Imaging studies included bone age, pelvic ultrasound and scrotum, and skull magnetic resonance imaging. RESULTS: Nine of the patients who received radiotherapy had decreased pituitary volume. There was a significant difference in the response to GH and loss of predicted final stature (Bayley-Pinneau) between the 2 irradiated groups and the group that was not irradiated, but there was no difference regarding the radiation doses used (18 or 24 Gy). The final predicted height (Bayley-Pinneau) was significantly less (P = 0.0071) in both groups treated with radiotherapy. Two girls had precocious puberty, and 1 boy with delayed puberty presented calcification of the epididymis. CONCLUSION: Radiotherapy was been responsible for late side effects, especially related to growth and puberty.

CNS-directed therapy for childhood acute lymphoblastic leukemia: Childhood ALL Collaborative Group overview of 43 randomized trials

PURPOSE

A collaborative meta-analysis was performed to clarify the relative effects on relapse and survival of different types of therapies directed at the CNS in childhood acute lymphoblastic leukemia.

MATERIALS AND METHODS

Data were sought for each individual patient in all trials started in or before 1993 that included unconfounded randomized comparisons of such treatments. Log-rank survival analyses were performed for each trial, and overall results for groups of trials addressing similar questions were obtained from the totals of the observed minus expected number of events and their variances.

RESULTS

Radiotherapy and long-term intrathecal therapy gave similar outcomes, with no significant difference in event-free survival despite random assignment of treatment to 2,848 patients, 1,001 of whom suffered relapse or death. Intravenous methotrexate reduced non-CNS rather than CNS relapses, and hence, the addition of intravenous methotrexate to a treatment regimen including radiotherapy or long-term intrathecal therapy improved event-free survival, with a 17% reduction in the event rate (95% confidence interval, 6% to 27%; P =.003). The event-free survival at 10 years in these trials was 61.9% without intravenous methotrexate and 68.1% with intravenous methotrexate. There was no significant difference in survival (14% death rate reduction; P =.09). There were insufficient randomly assigned patients to adequately address other questions, such as effect of different doses. No evidence was found of differences, between trials or between subgroups of different types of patients, in the relative effects of treatment.

CONCLUSION

Radiotherapy can be replaced by long-term intrathecal therapy. Intravenous methotrexate gives some additional benefit by reducing non-CNS relapses.

Minimal residual disease in early phase of chemotherapy reflects poor outcome in children with acute lymphoblastic leukemia--a retrospective study by the Children's Cancer and Leukemia Study Group in Japan

We analyzed the minimal residual disease (MRD) in 50 children with acute lymphoblastic leukemia (ALL) by amplifying the clonally rearranged T-cell receptor (TCR) gamma/delta chain and/or immunoglobulin (Ig) kappa chain gene using the allele-specific-PCR method. All children were treated according to the protocols of the Children's Cancer and Leukemia Study Group of Japan (CCLSG). The patients were stratified into four risk-groups according to the leukocyte count and age at diagnosis. We prospectively sampled the patients' bone marrow at 1 month (point 1) and 3 months (point 2) after the initiation of chemotherapy and quantitated the MRD retrospectively. The results of MRD were closely related with the clinical outcome. The relapse rate of the patients MRD-positive at points 1 and 2 was 46% (6/13) and 86% (6/7), respectively, whereas those MRD-negative results at point 1 and 2 were 13% (3/13) and 3% (3/30), respectively. We found significant differences in the event-free survival between MRD-positive children and MRD-negative children like the reports, which have been made by BFM and EORTC groups. We conclude that MRD in an early phase of chemotherapy can be a good predictor of the prognosis of childhood ALL regardless of the protocol of chemotherapy or race.

The effect of chemotherapy on the growing skeleton

With the increasing use of high dose (poly)chemotherapy schedules in the treatment of childhood cancer it is particularly important to know the adverse effects of these treatments. Growth is a complex mechanism affected not only by chemotherapy but also by the malignancy itself as well as nutritional status, the use of corticosteroids and (cranial) radiation. In vitro and animal studies are often the most useful in determining the effect of a single chemotherapeutic agent on the growing skeleton. In vitro studies have shown doxorubicin, actinomycin D and cisplatin to have a direct effect on growth plate chondrocytes that in animals results in decreased growth and final height. Clinical studies with multiagent chemotherapy have demonstrated that antimetabolites decrease bone growth and final height. Childhood cancer survivors are at risk of a reduced bone mineral density, mainly due to methotrexate, ifosfamide and corticosteroids. This reduced bone mineral density persists into adult life and may increase bone fracture risk at an older age.

Benefit of intensified treatment for all children with acute lymphoblastic leukaemia: results from MRC UKALL XI and MRC ALL97 randomised trials. UK Medical Research Council's Working Party on Childhood Leukaemia

Treatment of children with acute lymphoblastic leukaemia (ALL) aims to cure all patients with as little toxicity as possible and, if possible, to restrict further intensification of chemotherapy to patients with an increased risk of relapse. However in Medical Research Council (MRC) trial UKALL X two short myeloablative blocks of intensification therapy given at weeks 5 and 20 were of benefit to children in all risk groups. The successor trials, MRC UKALL XI and MRC ALL97, tested whether further intensification would continue to benefit all patients by randomising them to receive, or not, an extended third intensification block at week 35. After a median follow-up of 4 years (range 5 months to 8 years), 5 year projected event-free survival was superior at 68% for the 894 patients allocated a third intensification compared with 60% for the 887 patients who did not receive one (odds ratio 0.75, 95% CI 0.63-0.90, 2P = 0.002). This difference was almost entirely due to a reduced incidence of bone marrow relapses in the third intensification arm (140 of 891 in the third intensification arm vs. 171 of 883 in the no third intensification, 2P = 0.02). Subgroup analysis suggests benefit of the third intensification for all risk categories. Overall survival to date is no different in the two arms, indicating that a greater proportion of those not receiving a third intensification arm and subsequently relapsing can be salvaged. These results indicate that there is benefit of additional intensification for all risk subgroups of childhood ALL.

Incidence of TEL/AML1 Fusion Gene Analyzed Consecutively in Children With Acute Lymphoblastic Leukemia in Relapse

The translocation t(12; 21)(p13; q22) is difficult to detect by classic cytogenetics. However, using fluorescence in situ hybridization (FISH) and by screening for the TEL/AML1 rearrangement by the polymerase chain reaction (PCR), it has been demonstrated to be the most frequent known structural chromosomal abnormality in childhood acute lymphoblastic leukemia (ALL). It is closely correlated with a B-cell precursor (BCP) phenotype and is considered a favorable prognostic factor. However, little is known about the incidence of the translocation in relapsed patients and the duration of complete remission (CR) in children expressing the TEL/AML1 fusion gene. We therefore examined 49 bone marrow samples from children with ALL at first or second relapse that were consecutively mailed to our laboratory to test for the presence of t(12; 21) using reverse transcriptase (RT)-PCR. The TEL/AML1 rearrangement could be identified in nine of 44 (20%) of the patients, a result similar to the reported incidence at diagnosis. Most of the TEL/AML1–positive children showed no adverse clinical features at diagnosis (eg, white blood cell [WBC] count <100 × 109/L or age <10 years), and regarding these data, there were no differences versus children who were negative for the fusion gene. However, the period of remission was about 1 year longer in children expressing TEL/AML1 (P = .046), and the majority of relapses in this group appeared late (<2 years after diagnosis). Our findings therefore reinforce the urgent need for further prospective studies with a long follow-up period to determine the true prognostic significance of t(12; 21) and to avoid premature changes of treatment strategies.

Incidence of TEL/AML1 Fusion Gene Analyzed Consecutively in Children With Acute Lymphoblastic Leukemia in Relapse

The translocation t(12; 21)(p13; q22) is difficult to detect by classic cytogenetics. However, using fluorescence in situ hybridization (FISH) and by screening for the TEL/AML1 rearrangement by the polymerase chain reaction (PCR), it has been demonstrated to be the most frequent known structural chromosomal abnormality in childhood acute lymphoblastic leukemia (ALL). It is closely correlated with a B-cell precursor (BCP) phenotype and is considered a favorable prognostic factor. However, little is known about the incidence of the translocation in relapsed patients and the duration of complete remission (CR) in children expressing the TEL/AML1 fusion gene. We therefore examined 49 bone marrow samples from children with ALL at first or second relapse that were consecutively mailed to our laboratory to test for the presence of t(12; 21) using reverse transcriptase (RT)-PCR. The TEL/AML1 rearrangement could be identified in nine of 44 (20%) of the patients, a result similar to the reported incidence at diagnosis. Most of the TEL/AML1–positive children showed no adverse clinical features at diagnosis (eg, white blood cell [WBC] count <100 × 109/L or age <10 years), and regarding these data, there were no differences versus children who were negative for the fusion gene. However, the period of remission was about 1 year longer in children expressing TEL/AML1 (P = .046), and the majority of relapses in this group appeared late (<2 years after diagnosis). Our findings therefore reinforce the urgent need for further prospective studies with a long follow-up period to determine the true prognostic significance of t(12; 21) and to avoid premature changes of treatment strategies.

Role of folylpolygutamate synthetase (FPGS) in antifolate chemotherapy; a biochemical and clinical update

Even though folate antimetabolites were introduced over forty years ago, they continue to be the backbone of many active chemotherapeutic regimens used by medical and pediatric oncologists. The recognition of polyglutamylation by folylpolyglutamate synthetase (FPGS) as an important metabolic step in the "activation" of classical antifolates and novel drugs aimed at thymidylate synthase (TS) and de novo purine synthesis, has resulted in renewed interest in this class of drugs. In addition, the emergence of secondary neoplasms in patients treated with alkylating agents and topoisomerase inhibitors in contrast to the exceptional safety record of antimetabolites, underscores the need for clinical trials that incorporate new strategies with known active antimetabolites and novel promising agents. In that context, FPGS is an important target for further laboratory and clinical investigations.