Pediatric Oncology Group (POG) studies of acute myeloid leukemia (AML): a review of four consecutive childhood AML trials conducted between 1981 and 2000.

From 1981 to 2000, a total of 1823 children with acute myeloid leukemia (AML) enrolled on four consecutive Pediatric Oncology Group (POG) clinical trials. POG 8101 demonstrated that the induction rate associated with the 3+7+7 combination of daunorubicin, Ara-C, and 6-thioguanine (DAT) was greater than that associated with an induction regimen used to treat acute lymphoblastic leukemia (82 vs 61%; P=0.02). Designed as a pilot study to determine the feasibility of administration of noncross-resistant drug pairs and later modified to assess the effect of dose intensification of Ara-C during the second induction course, POG 8498 confirmed the high initial rate of response to DAT (84.2%) and showed that dose intensification of Ara-C during the second induction course resulted in a trend toward higher event-free survival (EFS) estimates than did standard-dose DAT (2+5) during the second induction course (5 year EFS estimates, 22 vs 27%; P=0.33). Age <2 years and leukocyte count <100 000/mm3 emerged as significantly good prognostic factors. The most significant observation made in the POG 8498 study was the markedly superior outcome of children with Down's syndrome who were treated on the high-dose Ara-C regimen. POG 8821 compared the efficacy of autologous bone marrow transplantation (BMT) with that of intensive consolidation chemotherapy. Intent-to-treat analysis revealed similar 5-year EFS estimates for the group that underwent autologous BMT (36+/-4.7%) and for the group that received only intensive chemotherapy (35+/-4.5%) (P=0.25). There was a high rate of treatment-related mortality in the autologous transplantation group. The study demonstrated superior results of allogeneic BMT for patients with histocompatible related donors (5-year EFS estimate 63+/-5.4%) and of children with Down's syndrome (5-year EFS estimate, 66+/-8.6%). The POG 9421 AML study evaluated high-dose Ara-C as part of the first induction course and the use of the multidrug resistance modulator cyclosporine. Preliminary results showed that patients receiving both high-dose Ara-C for remission induction and the MDR modulator for consolidation had a superior outcome (5-year EFS estimate, 42+/-8.2%) than did patients receiving other treatment; however, the difference was not statistically significant. These four studies demonstrate the importance of dose intensification of Ara-C in the treatment of childhood AML; cytogenetics as the single most prognostic factor and the unique curability of AML in children with Down's syndrome.

Deferoxamine inhibition of human neuroblastoma viability and proliferation.

Patients with widespread neuroblastoma (NB) frequently have elevated serum ferritin levels, and recently anti-NB effects of the iron chelator deferoxamine (DFO) have been reported. We have investigated the effect of DFO on human bone marrow NB cells from two untreated children with Evans Stage IV disease. DFO treatment caused dose- and time-dependent cytotoxicity of NB cells, with maximal killing at exposure to 50 micron DFO for 72 h. Cytotoxicity was prevented by cotreatment with stoichiometric amounts of iron salts and reversible by removal of DFO or addition of iron salts within 48 h of treatment. Additionally, DFO inhibited clonal growth of human bone marrow NB cells in methylcellulose in a time- and dose-dependent manner. These effects were also prevented by cotreatment with iron salts. Thus, DFO has potent antitumor effects on human NB cells which appear to be related to iron deprivation. DFO should be considered for further preclinical evaluation as an anti-NB agent.

Antileukemic effects of deferoxamine on human myeloid leukemia cell lines.

Deferoxamine (DFO) possesses antiproliferative activity against mitogen-stimulated lymphocytes, several tumor cell lines, and human leukemia and neuroblastoma cells. We have investigated its effects on the human myeloid leukemia lines HL-60, HEL, and U-937. In suspension culture, DFO causes a dose-dependent inhibition of proliferation of each cell line, with maximal inhibition observed at concentrations greater than 20 microM. These effects were prevented by cotreatment with iron salts and were at least partially reversible by removal of DFO from the culture system or addition of iron before 48 h of DFO exposure. Similar results were obtained in methylcellulose cultures of leukemic cells, with complete abolition of cell aggregates at day 7 in concentrations of 20 microM DFO or higher. DFO treatment caused a dose- and time-related decrease in DNA synthesis as measured by [3H]thymidine uptake, which was also reversed by treatment with iron salts. DFO caused slight reduction in RNA synthesis and did not affect protein synthesis. DFO caused significant antiproliferative effects on three myeloid leukemia cell lines, associated with inhibition of DNA synthesis, with in vitro effects observed at concentrations attainable in vivo. Evaluation of the antileukemic properties of DFO should continue.

Secondary acute myelogenous leukemia following safe exposure to etoposide.

PURPOSE: To present two patients as illustrations of the risk of developing secondary acute myelogenous leukemia (sAML) when theoretically safe doses of etoposide (VP-16) are used. PATIENTS AND METHODS: Patient no. 1 was a 15-year-old white girl diagnosed with stage IIa Hodgkin's disease. She was treated with a combination of vincristine, doxorubicin, bleomycin, and VP-16 (2 g/m2 total) over 4 months, followed by 25.5 Gy of involved-field radiotherapy. Patient no. 2 was an 11-year-old white boy diagnosed with virus-associated hemophagocytic syndrome (VAHS). He was treated with VP-16 intravenously (IV) and orally (0.3 g and 2.8 g/m2, respectively). RESULTS: Patient no. 1 developed AML 16 months from the diagnosis of Hodgkin's disease. Patient no. 2 developed AML 26 months from diagnosis. Both bone marrows were consistent with French-American-British (FAB) M4 disease. Both patients had abnormalities of the long arm of chromosome 11. CONCLUSION: The use of low-dose or oral VP-16 can be associated with the development of sAML. Clinicians should be cautious in the use of VP-16 in low-risk diseases.

Interleukin-12 (IL-12) enhances lysis of non-lymphoid leukemia cell lines in vitro.

IL-2 augments the ability of natural killer (NK) cells to kill myeloid leukemia cells in vitro, and may have a role in the eradication of minimal residual disease (MRD) in AML patients. The ability to enhance lysis of AML cells without the toxicity of IL-2 would be a significant improvement in the use of biologics against AML. Recent interest in IL-12 suggested that this cytokine might meet these criteria. The aim of this study was to evaluate the ability of IL-12 to enhance the in vitro lysis of the non-lymphoid leukemia cell lines in a standard 51Chromium release assay. Effector cells from normal volunteers were incubated with varying concentrations of IL-12 or IL-2 for 18-20 h, then the 51Cr-labeled target cells from five different cell lines of AML origin were added for 4 h. Percent lysis was determined and plotted over four effector:target (E:T) ratios. Our results indicated that IL-12 was able to enhance lysis of all cell lines tested at > or =5 units/ml. When IL-2 was added to the culture at a low dose along with IL-12, there appeared to be a synergistic effect. Although anti-gamma interferon was able to inhibit the cytolytic potential of effectors activated by IL-12, the lysis could not be completely blocked. Thus, it appears that IL-12 has the ability to stimulate NK lysis indirectly through the induction of gamma interferon as well as an alternate mechanism not related to gamma interferon. Thus, IL-12 may have a beneficial role in the treatment of non-lymphoid leukemia.

Pharmacokinetic interactions of cyclosporine with etoposide and mitoxantrone in children with acute myeloid leukemia.

The purpose of this study was to assess the effect of the multidrug resistance modulator cyclosporine (CsA) on the pharmacokinetics of etoposide and mitoxantrone in children with de novo acute myeloid leukemia (AML). Serial blood samples for pharmacokinetic studies were obtained in 38 children over a 24-h period following cytotoxin treatment with or without CsA on days 1 and 4. Drug concentrations were quantitated using validated HPLC methods, and pharmacokinetic parameters were determined using compartmental modeling with an iterative two-stage approach, implemented on ADAPT II software. Etoposide displayed a greater degree of interindividual variability in clearance and systemic exposure than mitoxantrone. With CsA treatment, etoposide and mitoxantrone mean clearance declined by 71% and 42%, respectively. These effects on clearance, in combination with the empiric 40% dose reduction for either cytotoxin, resulted in a 47% and 12% increases in the mean AUC for etoposide and mitoxantrone, respectively. There were no differences in the rates of stomatitis or infection between the two groups. CsA treatment resulted in an increased incidence of hyperbilrubinemia, which rapidly reversed upon conclusion of drug therapy. The variability observed in clearance, combined with the empiric 40% dose reduction of the cytotoxins, resulted in statistically similar systemic exposure and similar toxicity.

BP1, a new homeobox gene, is frequently expressed in acute leukemias.

Aberrant expression of homeobox genes has been described in primary leukemia blasts. We recently cloned a new cDNA, BP1, which is a member of the homeobox gene family. BP1 expression was investigated in bone marrow samples from acute myeloid leukemia (AML), acute T cell lymphocytic leukemia (ALL) and pre-B cell ALL. Expression levels of two apparent isoforms of BP1, DLX7 and DLX4, were measured in the same samples. They are weakly if at all detectable in normal bone marrow, PHA-stimulated T cells or B cells. BP1 RNA was highly expressed in 63% of AML cases, including 81% of the pediatric and 47% of the adult cases, and in 32% of T-ALL cases, but was not found in any of the pre-B ALL cases. Coexpression of BP1, DLX7 and DLX4 occurred in a significant number of leukemias. Our data, including co-expression of BP1 with c-myb and GATA-1, markers of early progenitors, suggest that BP1 expression occurs in primitive cells in AML. Analysis of CD34+ and CD34- normal bone marrow cells revealed BP1 is expressed in CD34- cells and virtually extinguished in CD34+ cells. Ectopic expression of BP1 in the leukemia cell line K562 increased clonogenicity, consistent with a role for BP1 in leukemogenesis. The presence of BP1 RNA in leukemic blasts may therefore be a molecular marker for primitive cells and/or may indicate that BP1 is an important upstream factor in an oncogenic pathway.

KRN5500 induces apoptosis (PCD) of myeloid leukemia cell lines and patient blasts.

The purpose of this study was to determine if KRN5500, a spicamycin derivative with a unique acyl tail, would induce programmed cell death (PCD) of myeloid leukemia cell lines and cryopreserved leukemic blasts from newly diagnosed children with acute leukemia (AL). Cells were incubated with varying concentrations (0-5 ng/ml) of KRN5500 and the percent PCD determined using a modified in situ end labeling (ISEL) technique with Klenow fragment. The percent PCD was calculated using the formula: Percent PCD (% PCD)=[number of apoptotic cells/(viable cells+apoptotic cells)]x100. DMSO (0.30% w/v) was added to the cells in culture as the positive control for PCD; the negative control was media or albumin. KRN5500 increased the amount of PCD significantly in all five of the tested cell lines; U937 41+/-1.8%, KG1a 40+/-0.3%, HEL 14+/-2.2%, HL-60 41+/-0. 9%, K562 36+/-2% (mean PCD+/-SD). Patient blasts exposed to KRN5500 had an increase in PCD when exposed to 2 ng/ml of agent from 2 to 8 h; acute myeloid leukemia patients 7.5+/-0.5% at 2 h to 43.5+/-1.6% at 8 h, and acute lymphocytic leukemia patients rose from 12.4+/-3.8% at 2 h to 29.9+/-11.6% after 8 h (mean+/-SE). Overall the PCD for the patient samples was 3.7 versus 28+/-4% at 2 and 8 h, respectively. PCD was proportional to the dose of KRN5500 and incubation time. Further pre-clinical and clinical studies are required.

9p- in a girl with acute lymphocytic leukemia and sickle cell disease.

A 4 year old girl with sickle cell disease developed acute lymphocytic leukemia null cell type. The bone marrow karyotype was 46,XX,del(9)(p13). This girl is among the few patients with acute lymphocytic leukemia and abnormalities of #9 to have an isolated 9p-.

Natural history of histiocytosis-X.

Histiocytosis-X can involve many organs and tissues in all age groups and in both sexes and occurs most often in caucasians. The signs and symptoms observed in the patient are directly related to the infiltration of Langerhans histiocytes, which compress or displace normal tissues and cause destruction of the tissues and organs involved. The disease tends to be benign and self-limiting when the involvement is limited to only one site. When more than one site is involved, the disease course can be chronic or acute. The chronic course tends to smolder for years, causing significant morbidity and disability but not death. The acute form tends to cause significant morbidity and early mortality.

Management of complicated hemangiomas with vincristine/vinblastine: Quantitative response to therapy using MRI.

PURPOSE: To quantify the efficacy of vincristine and vinblastine in the treatment of complicated hemangiomas. DESIGN: Retrospective review. METHODS: Charts were reviewed to identify patients treated with vincristine or vinblastine for complicated hemangiomas from August 2002 to October 2007. Only patients who received both a pre and post-treatment magnetic resonance imaging (MRI) were considered. A database was created which includes patient gender, age at treatment initiation, rationale for treatment, hemangioma location, number of cycles of chemotherapy received, and complications of treatment. A single pediatric radiologist calculated lesion volumes from both pre and post-treatment MRI which were compared to quantify treatment response. RESULTS: Seven patients (2 male, 5 female) met criteria. Mean age at treatment initiation was 20 weeks (median 14, range 5-60). Rationale for treatment included four patients (57%) with proptosis/orbital compromise and one patient each (14%) with heart failure, airway compression, and hemangiomatosis with rapid growth of multiple lesions. Patients received a mean of 2.86 cycles of chemotherapy (median 3, range 1-5). Twelve lesions were identified and analyzed for pre and post-treatment volume on MRI in the seven patients. Eleven of twelve (92%) lesions decreased in size after treatment. The mean volume ratio of hemangiomas at the conclusion of chemotherapy was 0.45 compared to pre-treatment size (median 0.18, range 0-2.19) Orbital compromise, airway compression, and cardiac failure either improved or resolved in all patients. Three complications of treatment were seen in seven patients (42%) including bacteremia with anemia, peripheral neuropathy and motor delay. All complications resolved after cessation of chemotherapy. CONCLUSIONS: Treatment of complicated hemangiomas with vincristine or vinblastine can control growth and improve symptoms in the majority of patients. Treatment often requires multiple cycles of chemotherapy. Complications of treatment are common, but reversible.

Prophylactic treatment with activated prothrombin complex concentrate (FEIBA) reduces the frequency of bleeding episodes in paediatric patients with haemophilia A and inhibitors.

Orthopaedic complications are among the most disabling sequelae occurring in patients with haemophilia and inhibitors. Recurrent or refractory joint bleeds can lead to joint damage, limiting mobility and causing permanent disability. Activated prothrombin complex concentrates (aPCCs) are effective in controlling acute, intraoperative and postoperative bleeding in patients with haemophilia and inhibitors. The relatively long, dosing interval and safety profile distinguish aPCCs as a well-suited option for prophylaxis. Therefore, it is postulated that long-term routine aPCC administration will decrease the frequency of recurrent bleeds, prevent damage to normal joints, and slow the progression of existing joint disease in patients with inhibitors. To test this hypothesis, a retrospective chart audit was performed. In four treatment centres, five patients were identified who received aPCC [Factor Eight Inhibitor Bypassing Activity, Anti-Inhibitor Coagulant Complex (FEIBA); Baxter AG, Vienna, Austria] prophylactically for > or = 6 months to prevent or reduce further joint deterioration, reduce bleeding and prevent postsurgical bleeding. Median treatment duration was 15 months and included administration of >1300 doses of aPCC. Dosages ranged from 50 to 75 U kg(-1) three times per week in four patients; one patient received 100 U kg(-1) daily. Orthopaedic status was maintained in four patients and improved in one; the frequency of bleeding episodes was reduced in all patients. No adverse events or thrombotic complications were reported. This case series demonstrates that routine aPCC administration may be used safely and effectively to reduce the occurrence of bleeding episodes and to maintain or improve clinical joint status in some patients.

Use of factor VIII replacement during open heart surgery in a patient with haemophilia A.

We present a patient with haemophilia undergoing cardiac surgery treated with continuous infusion factor VIII.

An infant girl with severe autoimmune hemolytic anemia: apparent anti-Vel specificity.

Autoantibodies directed against the common red-cell antigen Vel are unusual, with only 2 previous cases reported. This report describes an infant girl with steroid-resistant autoimmune hemolytic anemia whose serum contained an antibody with apparent specificity for Vel antigen. Transfusion with Vel-positive cells resulted in a massive hemolytic transfusion reaction. Survival of labelled Vel-negative cells was normal up to 8 h following transfusion, and no transfusion reaction followed subsequent use of Vel-negative cells. There was no evidence of a collagen vascular disease, an immunodeficiency syndrome, or a malignancy. Although rare, anti-Vel should be considered in unexplained autoimmune hemolytic anemia.