Treatment of childhood acute myelogenous leukemia with an intensive regimen (AML-87) that individualizes etoposide and cytarabine dosages: short- and long-term effects

The Role of NcRNAs to Regulate Immune Checkpoints in Cancer

At present, the incidence of cancer is becoming more and more common, but its treatment has always been a problem. Although a small number of cancers can be treated, the recurrence rates are generally high and cannot be completely cured. At present, conventional cancer therapies mainly include chemotherapy and radiotherapy, which are the first-line therapies for most cancer patients, but there are palliatives. Approaches to cancer treatment are not as fast as cancer development. The current cancer treatments have not been effective in stopping the development of cancer, and cancer treatment needs to be imported into new strategies. Non-coding RNAs (ncRNAs) is a hot research topic at present. NcRNAs, which include microRNAs (miRNAs), circular RNAs (circRNAs), and long non-coding RNAs (lncRNAs), participate in all aspects of cancer biology. They are involved in the progression of tumors into a new form, including B-cell lymphoma, glioma, or the parenchymal tumors such as gastric cancer and colon cancer, among others. NcRNAs target various immune checkpoints to affect tumor proliferation, differentiation, and development. This might represent a new strategy for cancer treatment.

Hearing Status in Survivors of Childhood Acute Myeloid Leukemia Treated With Chemotherapy Only: A NOPHO-AML Study

BACKGROUND

As more children survive acute myeloid leukemia (AML) it is increasingly important to assess possible late effects of the intensive treatment. Hearing loss has only sporadically been reported in survivors of childhood AML. We assessed hearing status in survivors of childhood AML treated with chemotherapy alone according to 3 consecutive NOPHO-AML trials.

PROCEDURE

A population-based cohort of children treated according to the NOPHO-AML-84, NOPHO-AML-88, and NOPHO-AML-93 trials included 137 eligible survivors among whom 101 (74%) completed a questionnaire and 99 (72%) had otologic and audiologic examination performed including otoscopy (72%), pure tone audiometry (70%), and tympanometry (60%). Eighty-four of 93 (90%) eligible sibling controls completed a similar questionnaire.

RESULTS

At a median of 11 years (range, 4 to 25) after diagnosis, hearing disorders were rare in survivors of childhood AML and in sibling controls, with no significant differences. None had severe or profound hearing loss diagnosed at audiometry. Audiometry detected a subclinical hearing loss ranging from slight to moderate in 19% of the survivors, 5% had low-frequency hearing loss, and 17% had high-frequency hearing loss.

CONCLUSIONS

The frequency of hearing disorders was low, and hearing thresholds in survivors of childhood AML were similar to background populations of comparable age.

POST: A framework for set-based association analysis in high-dimensional data

Evaluating the differential expression of a set of genes belonging to a common biological process or ontology has proven to be a very useful tool for biological discovery. However, existing gene-set association methods are limited to applications that evaluate differential expression across k⩾2 treatment groups or biological categories. This limitation precludes researchers from most effectively evaluating the association with other phenotypes that may be more clinically meaningful, such as quantitative variables or censored survival time variables. Projection onto the Orthogonal Space Testing (POST) is proposed as a general procedure that can robustly evaluate the association of a gene-set with several different types of phenotypic data (categorical, ordinal, continuous, or censored). For each gene-set, POST transforms the gene profiles into a set of eigenvectors and then uses statistical modeling to compute a set of z-statistics that measure the association of each eigenvector with the phenotype. The overall gene-set statistic is the sum of squared z-statistics weighted by the corresponding eigenvalues. Finally, bootstrapping is used to compute a p-value. POST may evaluate associations with or without adjustment for covariates. In simulation studies, it is shown that the performance of POST in evaluating the association with a categorical phenotype is similar to or exceeds that of existing methods. In evaluating the association of 875 biological processes with the time to relapse of pediatric acute myeloid leukemia, POST identified the well-known oncogenic WNT signaling pathway as its top hit. These results indicate that POST can be a very useful tool for evaluating the association of a gene-set with a variety of different phenotypes. We have developed an R package named POST which is freely available in Bioconductor.

The miR-125a-3p Inhibits TIM-3 Expression in AML Cell Line HL-60 In Vitro

Acute Myeloid Leukemia is a cancer of leukemic stem cells (LSCs) with a rapid progression. It is characterized by overproduction of immature myeloid cells in bone marrow which crowds out normal hematopoietic stem cells (HSC). TIM-3, an immune regulatory molecule, is an LSC specific surface marker in AML with high expression on these cells compared to HSCs. Studies have indicated that micro RNAs (miRNAs) may play an important role in either cancer progression or suppression. Based on bioinformatics assessments, we have predicted that miR-125a-3p could be a miRNA with high suppressive activity on TIM-3 expression. The purpose of this study was to investigate the inhibitory effect of miR-125a-3p on TIM-3 gene expression in an AML cell line, HL-60, in vitro. HL-60 cells were cultured in RPMI 1640 supplied with 10 % FBS. TIM-3 expression was induced on the cells using phorbol miristate acetate. The cells were transfected with miR-125-3p for 24 h and the gene and protein expression of TIM-3 were measured using q-RT-PCR and flow-cytometery methods, respectively. The results of this study showed that miR-125a-3p has a strong silencing effect on TIM-3 gene and protein expression on HL-60 cell line. Based to our results, miR125a-3p can strongly silence TIM-3 expression in AML cell line. Thus, our results have confirmed the bioinformatics prediction of suppressive effect of miR-125a-3p on TIM-3with Mirwalk and Target Scan softwares.

Definition of cure in childhood acute myeloid leukemia

BACKGROUND

A better understanding of when cure can be declared in childhood acute myeloid leukemia (AML) would reduce anxiety and improve quality of life of AML survivors. The authors determined the likelihood that patients with AML would maintain long-term remission after the completion of therapy.

METHODS

The cumulative risk of relapse, the time to relapse, event-free survival, and overall survival were analyzed for 604 patients with AML who were enrolled in 7 successive clinical trials divided into 3 treatment eras (1976-1991, 1991-1997, and 2002-2008).

RESULTS

The median time to relapse did not change over time (0.93 years vs 0.76 years vs 0.8 years, respectively, for each consecutive era; P = .22), but the risk of relapse decreased significantly (5-year cumulative incidence of relapse: 52.6% ± 3.1% vs 31.5% ± 3.9% vs 22% ± 3%, respectively, for each consecutive era; P < .001). Among patients who were in remission 4 years from diagnosis, the probabilities of relapse were 1.7%, 2.9%, and 0.9%, respectively, for each consecutive era. In the most recent era, all but 1 of 44 relapses occurred within 4 years of diagnosis.

CONCLUSIONS

Children with AML who receive treatment with contemporary therapy and remain in remission 4 years from diagnosis probably are cured. Although late relapses and late deaths from other causes are rare, long-term follow-up of survivors is necessary for the timely management of late adverse effects.

Effect of body mass index on the outcome of children with acute myeloid leukemia

BACKGROUND

The effect of body mass index (BMI) on the treatment outcomes of children with acute myeloid leukemia (AML) is unclear and needs further evaluation.

METHODS

Children with AML (n = 314) who were enrolled in 4 consecutive St. Jude protocols were grouped according to BMI (underweight, <5th percentile; healthy weight, 5th to 85th percentile; and overweight/obese, ≥ 85th percentile).

RESULTS

Twenty-five patients (8%) were underweight, 86 patients (27.4%) were overweight/obese, and 203 patients (64.6%) had healthy weight. The 5-year overall survival rate of overweight/obese patients (46.5% ± 7.3%) was lower than the rate of patients with healthy weight (67.1% ± 4.3%; P < .001); underweight patients also tended to have lower survival rates (50.6% ± 10.7%; P = .18). In a multivariable analysis that was adjusted for age, leukocyte count, French-American-British classification, and study protocols, patients with healthy weight had the best survival rate among the 3 groups (P = .01). When BMI was considered as continuous variable, patients with lower or higher BMI percentiles had worse survival (P = .03). There was no difference in the occurrence of induction failure or relapse among BMI groups, although underweight and overweight/obese patients had a significantly higher cumulative incidence of treatment-related mortality, especially because of infection (P = .009).

CONCLUSIONS

An unhealthy BMI was associated with worse survival and more treatment-related mortality in children with AML. Meticulous supportive care with nutritional support and education, infection prophylaxis, and detailed laboratory and physical examination is required for these patients. These measures, together with pharmacokinetics-guided chemotherapy dosing, may improve outcome.

Prognostic significance of myeloperoxidase expression in childhood acute myeloid leukemia

BACKGROUND

The percentage of myeloperoxidase (MPO)-positive blast cells is associated with prognosis in adult acute myeloid leukemia (AML), but this association is unsubstantiated in pediatric AML.

PROCEDURE

We retrospectively compared cytochemical MPO results with outcome in 154 patients younger than 21 years treated on three consecutive institutional protocols for newly diagnosed AML (1987-2001). Patients with FAB M0 and M7 AML (no MPO expression) or M3 AML (100% MPO expression) and Down's syndrome were excluded.

RESULTS

Median MPO expression was higher in FAB M2 subtype than in other subtypes (P < 0.0001) and differed significantly across cytogenetic risk groups (P = 0.002) with highest MPO expression among those with favorable karyotypes. The percentage of MPO-positive blasts was not significantly associated with the probability of complete remission (P = 0.97), event-free survival (P = 0.72), or survival (P = 0.76) in multivariate analyses that accounted for age, FAB subtype, presenting WBC count, cytogenetic and protocol treatment risk group. In analysis limited to patients with intermediate-risk cytogenetics, higher MPO expression appeared to be associated with improved EFS (P = 0.06) but was not associated with remission induction rate (P = 0.16) or overall survival (P = 0.38).

CONCLUSIONS

The percentage of MPO-positive blast cells is related to FAB subtype in pediatric AML but has limited prognostic relevance.

Clinical and imaging characteristics of orbital leukemic tumors

PURPOSE

To characterize the clinical and imaging features of orbital leukemic tumors in 27 patients seen and treated at St. Jude Children's Research Hospital.

METHODS

A retrospective review was performed on the clinical and imaging records of 27 consecutive patients with a diagnosis of orbital leukemic tumors. The following data were extracted from the patients' records: age at diagnosis of orbital leukemic tumors, sex, race, national origin, type of leukemia, temporal relationship of orbital disease to diagnosis of leukemia, survival from diagnosis of orbital leukemic tumor, laterality of the orbital disease, location of the mass within the orbit, imaging features of the mass, chemotherapeutic protocol, treatment with bone marrow transplant, and orbital radiation.

RESULTS

The median age at diagnosis of orbital leukemic tumor was 8 years (range, 1-18 years). Nineteen of the 27 patients were male, and 21 patients were born and lived in the United States. Twenty-one patients had acute myeloid leukemia, five had acute lymphoblastic leukemia, and one had chronic myelogenous leukemia. In 85% of patients (n = 23), the diagnosis of leukemia was based on the bone marrow examination findings. Orbital imaging revealed homogenous masses that molded to one or more orbital walls without bony destruction. Nine patients had bilateral orbital involvement. All patients received multiagent systemic chemotherapy, and 14 underwent bone marrow transplantation. Five patients received external beam radiation for the treatment of orbital disease. Fifteen (55.6%) of the 27 patients were alive at the time of the study. The median survival for all patients was 4.75 years (range, 0.1-24 years) after the diagnosis of orbital disease.

CONCLUSIONS

Orbital leukemic tumors occur most commonly in the first decade of life, in association with acute myeloid leukemia. They appear as homogenous masses along the orbital walls. Although the overall survival rate for patients with leukemia has improved over the past 3 decades, the mortality of patients who develop orbital leukemic tumors remains high.

Effect of race on outcome of white and black children with acute myeloid leukemia: the St. Jude experience

BACKGROUND

The association between race and outcome of treatment for childhood acute myeloid leukemia (AML) has not been adequately studied.

PROCEDURE

We compared the clinical characteristics, biological features, and outcomes between white and black children with AML who were treated on five consecutive clinical protocols (1980-2002) at St. Jude Children's Research Hospital. We used proportional hazards modeling to investigate the relation between race and outcome.

RESULTS

We observed no statistically significant differences between the 229 white and 58 black patients in clinical characteristics, FAB subtype, cytogenetic features, or outcome. There were no significant differences in event-free survival (EFS) or overall survival (OS) between the two race groups in individual clinical trials or in all studies combined. For the study group as a whole, the 5-year survival estimate was 39.2% +/- 3.6% for white patients and 33.8% +/- 6.5% for black patients. However, on our most recent trial (AML-97), there was a trend towards inferior outcome among black patients: the 5-year survival estimates were 55.6% +/- 12.3% and 27.3% +/- 13.5% for whites and blacks, respectively.

CONCLUSIONS

Although we detected no differences in treatment outcome between white and black children with AML over the entire study period, black children appear to have worse outcomes than white children during more recent studies. Improved treatment is needed for all children with AML.

Etoposide pharmacokinetics in children treated for acute myeloid leukemia

We studied the pharmacokinetics of etoposide in 45 children treated for newly diagnosed acute myeloid leukemia. Etoposide, 100 mg/m body surface area/24 h, was administered by 96-h continuous intravenous infusion. Concomitantly, the children received cytarabine 200 mg/m/24 h by intravenous infusion and 6-thioguanine 100 mg/m twice daily orally. Median total body clearance in children 0.5-1.8 (n=4) and 2.3-17.7 years old (n=36) without Down's syndrome was 17.1 and 17.6 ml/min/m, respectively (P=0.96). Five children with Down's syndrome had a median clearance of 13.6 ml/min/m (P=0.067 compared with non-Down's syndrome children). Eighteen of the children received a second identical treatment course 3-4 weeks later; there was a significant correlation between individual clearance values (rho=0.56; P=0.017). We found no significant correlation between etoposide pharmacokinetics and the remission rate or the relapse rate. In conclusion, our findings indicate that special dose-calculation guidelines for infants above 3 months old are not substantiated by age-dependent pharmacokinetics of etoposide. Down's syndrome children might be candidates for dose reduction if our data are confirmed in larger numbers of patients. Low course-to-course variability indicates that pharmacokinetically guided dosing of etoposide might be clinically relevant, if larger studies can demonstrate that this approach decreases toxicity or increases response rates.

Impact of age on outcome of pediatric acute myeloid leukemia: a report from 2 institutions

BACKGROUND

The prognostic significance of age among pediatric patients with acute myeloid leukemia (AML) was investigated.

METHODS

The authors reviewed the outcome of 424 patients who were <or=21 years of age at the time of diagnosis of AML (excluding acute promyelocytic leukemia) between 1983 and 2002 at St. Jude Children's Research Hospital (n=288) or the M. D. Anderson Cancer Center (n=136). Two treatment eras (1983-1989 and 1990-2002) were examined because of the greater intensity of treatment during the recent era.

RESULTS

After controlling for the effects of cytogenetics, white blood cell (WBC) count, French-American-British (FAB) subtype, and treatment era, they observed that age and treatment era interacted significantly in relation to event-free survival (EFS) (P=.033). Patients 10 years of age or older were at greater risk of an adverse event than younger patients in the recent era (hazard ratio=1.8; 95% confidence interval [CI]: 1.3-2.6; P=.005) but not in the early era. The rate of adverse events (death or recurrence) increased significantly with each year of age in the recent era (4.3%/year; 95% CI: 1.9-6.8%; P=.001) but not in the early era. The rate of death increased significantly with each year of age in both eras (4.4%/year; 95% CI: 2.3-6.5%; P<.001). EFS and survival showed no association with study site, and the effects of age were similar at the 2 sites.

CONCLUSIONS

These results suggest that age is an independent prognostic factor in childhood AML and that children younger than 10 years benefit more than older children from newer intensive therapies.

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.

Pharmacokinetic studies in children with cancer

We reviewed the current status of our knowledge of pharmacokinetics and pharmacodynamics of some anti-neoplastic drugs, used in the treatment of childhood cancer. Extrapolation of data from pharmacokinetic studies in adults to the paediatric population is often not feasible. Specific studies in children are needed. Of all reviewed anti-neoplastic drugs methotrexate appears to be most extensively studied. Methotrexate pharmacokinetics is correlated with toxicity and response to therapy, and it has been shown that individualized adaptive dosing of methotrexate is correlated with a better response to therapy without increasing toxicity in children with ALL and osteosarcoma. Of most of the other reviewed anti-neoplastic drugs it is demonstrated that pharmacokinetics is correlated with toxicity, and of some drugs a relationship of pharmacokinetics with response to therapy is demonstrated as well. In case of cytarabine, etoposide, and teniposide, individualized dosing also appears to be feasible. However, there is no evidence that this strategy improves response to therapy. Specifically data on pharmacokinetic and pharmacodynamic correlations and effect of pharmacokinetically guided, individualized dosing are important for the design of optimal cancer chemotherapy for individual patients. Unfortunately for a considerable number of anti-neoplastic drugs these specific data are lacking in children and future research is needed.

Gene expression profiling of pediatric acute myelogenous leukemia

Contemporary treatment of pediatric acute myeloid leukemia (AML) requires the assignment of patients to specific risk groups. To explore whether expression profiling of leukemic blasts could accurately distinguish between the known risk groups of AML, we analyzed 130 pediatric and 20 adult AML diagnostic bone marrow or peripheral blood samples using the Affymetrix U133A microarray. Class discriminating genes were identified for each of the major prognostic subtypes of pediatric AML, including t(15;17)[PML-RARα], t(8;21)[AML1-ETO], inv16 [CBFβ-MYH11], MLL chimeric fusion genes, and cases classified as FAB-M7. When subsets of these genes were used in supervised learning algorithms, an overall classification accuracy of more than 93% was achieved. Moreover, we were able to use the expression signatures generated from the pediatric samples to accurately classify adult de novo AMLs with the same genetic lesions. The class discriminating genes also provided novel insights into the molecular pathobiology of these leukemias. Finally, using a combined pediatric data set of 130 AMLs and 137 acute lymphoblastic leukemias, we identified an expression signature for cases with MLL chimeric fusion genes irrespective of lineage. Surprisingly, AMLs containing partial tandem duplications of MLL failed to cluster with MLL chimeric fusion gene cases, suggesting a significant difference in their underlying mechanism of transformation.

Inhibition of cardiac HERG currents by the DNA topoisomerase II inhibitor amsacrine: mode of action

1 The topoisomerase II inhibitor amsacrine is used in the treatment of acute myelogenous leukemia. Although most anticancer drugs are believed not to cause acquired long QT syndrome (LQTS), concerns have been raised by reports of QT interval prolongation, ventricular fibrillation and death associated with amsacrine treatment. Since blockade of cardiac human ether-a-go-go-related gene (HERG) potassium currents is an important cause of acquired LQTS, we investigated the acute effects of amsacrine on cloned HERG channels to determine the electrophysiological basis for its proarrhythmic potential. 2 HERG channels were heterologously expressed in human HEK 293 cells and Xenopus laevis oocytes, and the respective potassium currents were recorded using patch-clamp and two-microelectrode voltage-clamp electrophysiology. 3 Amsacrine blocked HERG currents in HEK 293 cells and Xenopus oocytes in a concentration-dependent manner, with IC50 values of 209.4 nm and 2.0 microm, respectively. 4 HERG channels were primarily blocked in the open and inactivated states, and no additional voltage dependence was observed. Amsacrine caused a negative shift in the voltage dependence of both activation (-7.6 mV) and inactivation (-7.6 mV). HERG current block by amsacrine was not frequency dependent. 5 The S6 domain mutations Y652A and F656A attenuated (Y652A) or abolished (F656A, Y652A/F656A) HERG current blockade, indicating that amsacrine binding requires a common drug receptor within the pore-S6 region. 6 In conclusion, these data demonstrate that the anticancer drug amsacrine is an antagonist of cloned HERG potassium channels, providing a molecular mechanism for the previously reported QTc interval prolongation during clinical administration of amsacrine.

Clinical significance of central nervous system involvement at diagnosis of pediatric acute myeloid leukemia: a single institution's experience

To determine the clinical significance of central nervous system (CNS) involvement at the time of diagnosis of pediatric acute myeloid leukemia (AML), we analyzed clinical features and outcomes of 290 patients treated consecutively on four institutional trials (AML80, AML83, AML87, and AML91). CNS status was classified as CNS1 (no blast cells in CSF; n=205), CNS2 (<5 WBC/mul CSF with blast cells; n=37), or CNS3 (>/=5 WBC/mul CSF with blast cells, or signs of CNS involvement; n=48). Patients with CNS3 status were significantly younger than others (P=0.016) and significantly more likely to have the favorable cytogenetic features t(9;11), t(8;21), or inv(16) (P<0.001). The CNS3 group had a significantly greater probability (+/-s.e.) of 5-year event-free survival (43.7+/-7.0%) than did the CNS1 (27.8+/-3.2%, P=0.015) and CNS2 (24.3+/-7.5%, P=0.032) groups. However, after adjustment for favorable genetic features, there was no significant difference in EFS between the CNS3 and the combined CNS1+CNS2 groups (P=0.075). In all, 10 of 151 patients treated on AML80 and AML83, but none of 139 treated on AML87 and AML91, had primary CNS relapse. CNS involvement had no adverse prognostic significance, and patients with CNS2 status had similar outcome to CNS1 patients in this large group of pediatric patients with AML, treated at a single institution.

Death during induction therapy and first remission of acute leukemia in childhood

BACKGROUND

Despite improvements in supportive care, death due to treatment toxicity remains a significant problem for children treated for acute leukemia.

METHODS

To determine the causes of and risk factors for death unrelated to refractory leukemia, to disease recurrence, or to second malignancy, the authors reviewed the records of 1011 patients with acute lymphoblastic leukemia (ALL) and 260 patients with acute myeloid leukemia (AML) treated between 1984 and 1999 and between 1983 and 2002, respectively, at St. Jude Children's Research Hospital (Memphis, TN). Data for patients who underwent stem cell transplantation were censored at the time of transplantation.

RESULTS

For patients with ALL, the estimated 10-year cumulative incidence of death was 2.9% +/- 5.3%. Age was the only predictor of death. Patients with ALL 1-9 years old had a significantly lower risk of death than did younger or older patients (P = 0.002). For patients with AML, the estimated 5-year cumulative incidence of death was 7.6% +/- 1.9%. Increasing age and increasing leukocyte count were significantly associated with increased risk of death. For patients with ALL and with AML, the incidence of death remained relatively constant during the time periods studied. Infection was the most common cause of death.

CONCLUSIONS

In the current study, the authors determined that children > or = 10 years of age are at increased risk of death during therapy for ALL and AML.

Selective activation of deoxycytidine kinase by thymidine-5'-thiosulphate and release by deoxycytidine in human lymphocytes

Deoxycytidine kinase (dCK) catalyses the rate-limiting step of the salvage of three natural deoxyribonucleosides as well as several therapeutic nucleoside analogues, which in turn can enhance its enzymatic activity [Biochem Pharmacol 56 (1998) 1175], improving the efficacy of the cytostatic therapy. Here, we measured the effect of the 5'-thiosulphate (5'-TS) derivatives of four deoxyribonucleosides (deoxyadenosine, deoxycytidine (dCyd), azidothymidine, thymidine) and two ribonucleosides (ribopurine, ribouridine (Urd)) on the activity of the two main salvage deoxynucleoside kinases, and on the salvage of dCyd and deoxythymidine (dThd). It turned out that only 2'-deoxythymidine-5'-thiosulphate (dThd-5'-TS) can potentiate the dCK activity, without influencing the thymidine kinase isoenzymes during short-time treatments of human peripheral blood and tonsillar lymphocytes. The enhancement of dCK activity by dThd-5'-TS can be reversed by dCyd, but dThd had no effect on the enzyme activation in cells. Neither dThd-5'-TS nor Urd-5'-TS had any effect on the dCK and thymidine kinase activities tested in cell-free extracts. The stimulation of dCK activity in cells was accompanied by an imbalance in the dThd and dCyd metabolism. The incorporation of 3H-dThd into DNA was suppressed by 90% in cells by dThd-5'-TS, while Urd-5'-TS only slightly influenced the same process. The 3H-dCyd incorporation into DNA was inhibited only to 50% of the control, while the 3H-dCyd labelling of the nucleotide fraction was enlarged in dThd-5'-TS-treated cells, as a consequence of the increased dCK activity. We suggest that the enhancement of dCK activity is a compensatory mechanism in cells that might be induced by different "inhibitors" of DNA synthesis leading to damage of DNA. The increased dCK activity is able to supply the repair of DNA with dNTPs in quiescent cells; this suggestion seems to be supported by the counteracting effect of extracellular dCyd, too.

Interim comparison of a continuous infusion versus a short daily infusion of cytarabine given in combination with cladribine for pediatric acute myeloid leukemia

PURPOSE

To identify the optimal schedule for infusion of cytarabine (ara-C) given with cladribine (2-CdA) to pediatric patients with acute myeloid leukemia (AML), and to compare the effects of the two schedules on the pharmacokinetics of ara-C triphosphate (ara-CTP) in leukemic cells.

PATIENTS AND METHODS

Forty-nine pediatric patients with newly diagnosed primary AML received a 5-day course of ara-C 500 mg/m(2)/d and 2-CdA 9 mg/m(2)/d. They were randomly assigned to receive ara-C as either a 2-hour daily infusion (arm A) or a continuous infusion (arm B). Cellular pharmacokinetics were studied on days 1 and 2. All patients then received two courses of remission induction chemotherapy with daunorubicin, ara-C, and etoposide (DAV).

RESULTS

Thirty-two percent of patients (seven of 22) in arm A and 63% (17 of 27) in arm B entered complete remission (P =.045) after ara-C and 2-CdA therapy. Coadministration of 2-CdA increased the intracellular concentration of ara-CTP in 20 of 36 patients, although we found no statistically significant difference between the treatment arms in this effect (P =.63). The incidence of toxicity did not differ significantly between the two treatment arms (P =.53). After two courses of DAV, the rate of complete remission was 91% in arm A and 96% in arm B (P =.58).

CONCLUSION

Intracellular accumulation of ara-CTP is increased when 2-CdA is given with ara-C, but no schedule-dependent differences in this effect were seen. The combination of 2-CdA and ara-C seems to be effective therapy for pediatric AML.

Characteristics and outcome of t(8;21)-positive childhood acute myeloid leukemia: a single institution's experience

To elucidate the clinical and biological features of childhood acute myeloid leukemia (AML) with the t(8;21), we reviewed the records of patients with AML treated at St Jude Children's Research Hospital over a 17-year period (1980 to 1996). Of 298 patients with AML, 40 (13%) had blast cells that contained the t(8;21). This translocation was associated with a high frequency of French-American-British M2 morphology (82%) and the presence of granulocytic sarcoma (23%). Molecular analysis detected the AML1-ETO fusion transcript in all 25 cases with the t(8;21) tested, but failed to identify additional cases with AML1-ETO among the 127 cases with other cytogenetic findings. Compared to patients with other genetic abnormalities, those with the t(8;21) were less likely to have internal tandem duplications of the FLT3 gene (none of 10 vs 16 of 68). The 6-year overall survival estimate was 55% +/- 9% and the event-free survival estimate, 33% +/- 7%. Of the clinical and biological features examined, only gender was prognostically significant: the 6-year overall survival estimate for males was 68% +/- 10%, compared to 33% +/- 11 for female patients (P = 0.03). Treatment outcome was not influenced by the chemotherapy regimen used or by the use of autologous hematopoietic stem cell transplantation. These results suggest that t(8;21)-positive AML represents a heterogeneous disease with variable outcome. The reported favorable outcome for t(8;21)-positive AML in other studies may be due to the use of high-dose cytarabine.

Impact of treatment on the outcome of acute myeloid leukemia with inversion 16: a single institution's experience

To identify treatment factors that may affect the survival of children with inv(16)(p13.1q22), we compared the outcomes of 19 patients with this genetic feature treated at our institution during two treatment eras. Nine patients were treated during era 1 (1980 to 1987), and 10 were treated during era 2 (1988 to 1996). All entered complete remission (CR) with induction therapy. Eight of the nine children treated in era 1 died, seven of relapsed leukemia. In contrast, three of 10 patients treated during era 2 have died, all of non-disease-related causes. Event-free survival (EFS) estimates were significantly higher for patients treated during era 2 than for those treated during era 1 (P = 0.03); the 6-year estimates were 70 +/- 15% (s.e.) and 11 +/- 7%, respectively. Era 2 treatment protocols differed from those of era 1 in their use of higher doses of cytarabine and etoposide during induction and consolidation chemotherapy and in their use of 2-chlorodeoxyadenosine (2-CDA). These results suggest that dose intensification of cytarabine benefits children with AML and inv(16), as is the case in adults. They also suggest that dose intensification of etoposide and addition of 2-CDA may also offer an advantage. This study underscores the dependence of the prognostic impact of cytogenetic features on the efficacy of treatment.

Recent publications in hematological oncology

In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of hematological oncology. Each bibliography is divided into 14 sections: 1 Books, Reviews & Symposia; 2 General; Leukemias: 3 Lymphoblastic; 4 Myeloid & Myelodysplastic Syndromes; 5 Chronic; 6 Others; Lymphomas: 7 Hodgkin's; 8 Non-Hodgkin's; 9 Plasmacytomas/Multiple Myelomas; 10 Others; 11 Bone Marrow Transplantation; 12 Cytokines; 13 Diagnosis; 14 Cytogenetics. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted.

Biology and outcome of childhood acute megakaryoblastic leukemia: a single institution's experience

To describe the clinical and biologic features of pediatric acute megakaryoblastic leukemia (AMKL) and to identify prognostic factors, experience at St Jude Children's Research Hospital was reviewed. Of 281 patients with acute myeloid leukemia treated over a 14-year period, 41 (14.6%) had a diagnosis of AMKL. Six patients had Down syndrome and AMKL, 6 had secondary AMKL, and 29 had de novo AMKL. The median age of the 22 boys and 19 girls was 23.9 months (range, 6.7-208.9 months). The rate of remission induction was 60.5%, with a 48% rate of subsequent relapse. Patients with Down syndrome had a significantly higher 2-year event-free survival (EFS) estimate (83%) than did other patients with de novo AMKL (14%) or with secondary AMKL (20%; P < or =.038). Among patients who had de novo AMKL without Down syndrome, 2-year EFS was significantly higher after allogeneic bone marrow transplantation (26%) than after chemotherapy alone (0%; P =.019) and significantly higher when performed during remission (46%) than when performed during persistent disease (0%; P =.019). The 5-year survival estimates were significantly lower for de novo AMKL (10%) than for other forms of de novo AML (42%; P <.001). Treatment outcome is very poor for patients with AMKL in the absence of Down syndrome. Remission induction is the most important prognostic factor. Allogeneic transplantation during remission offers the best chance of cure; in the absence of remission, transplantation offers no advantage over chemotherapy alone. (Blood. 2001;97:3727-3732)

Second malignancy after treatment of childhood acute myeloid leukemia

To investigate the cumulative incidence of second malignancy and the competing risk of death due to any other cause in patients who were treated for childhood acute myeloid leukemia (AML), we analyzed the outcomes in a cohort of 501 patients who were treated at St Jude Children's Research Hospital between 1970 and 1996. Five patients developed a second cancer (two carcinomas of the parotid gland, one non-Hodgkin's lymphoma, one supratentorial primitive neuroectodermal tumor, one acute lymphoblastic leukemia) as compared with 0.47 expected in the general population (standardized incidence ratio, 10.64; 95% confidence interval, 3.28 to 22.34). A third neoplasm (meningioma) developed in one patient. At 15 years after the diagnosis of AML, the estimated cumulative incidence of second malignancy was 1.34% +/- 0.61%, whereas the cumulative incidence of death due to any other cause was 72.96% +/- 2.14%. We concluded that although a more than 10-fold increased risk of development of cancer was found in survivors of childhood AML as compared to the general population, the risk of this late complication is small when compared to the much larger risk of death because of the primary leukemia or the early complications of its treatment. Future studies should focus on improving treatments for primary AML while preventing second malignancies.