Treatment of acute lymphoblastic leukemia

Stratification of pediatric ALL by in vitro cellular responses to DNA double-strand breaks provides insight into the molecular mechanisms underlying clinical response

The molecular basis of different outcomes in pediatric acute lymphoblastic leukemia (ALL) remains poorly understood. We addressed the clinical significance and mechanisms behind in vitro cellular responses to ionizing radiation (IR)-induced DNA double-strand breaks in 74 pediatric patients with ALL. We found an apoptosis-resistant response in 36% of patients characterized by failure to cleave caspase-3, -7, -9, and PARP1 by 24 hours after IR and an apoptosis-sensitive response with the cleavage of the same substrates in the remaining 64% of leukemias. Resistance to IR in vitro was associated with poor early blast clearance at day 7 or 15 and persistent minimal residual disease (MRD) at day 28 of induction treatment. Global gene expression profiling revealed abnormal up-regulation of multiple prosurvival pathways in response to IR in apoptosis-resistant leukemias and differential posttranscriptional activation of the PI3-Akt pathway was observed in representative resistant cases. Importantly, pharmacologic inhibition of selected prosurvival pathways sensitized apoptosis-resistant ALL cells to IR in vitro. We suggest that abnormal prosurvival responses to DNA damage provide one of the mechanisms of primary resistance in ALL, and that they should be considered as therapeutic targets in children with aggressive disease.

Gene expression signatures predictive of early response and outcome in high-risk childhood acute lymphoblastic leukemia: A Children's Oncology Group Study [corrected]

PURPOSE

To identify children with acute lymphoblastic leukemia (ALL) at initial diagnosis who are at risk for inferior response to therapy by using molecular signatures.

PATIENTS AND METHODS

Gene expression profiles were generated from bone marrow blasts at initial diagnosis from a cohort of 99 children with National Cancer Institute-defined high-risk ALL who were treated uniformly on the Children's Oncology Group (COG) 1961 study. For prediction of early response, genes that correlated to marrow status on day 7 were identified on a training set and were validated on a test set. An additional signature was correlated with long-term outcome, and the predictive models were validated on three large, independent patient cohorts. Results We identified a 24-probe set signature that was highly predictive of day 7 marrow status on the test set (P = .0061). Pathways were identified that may play a role in early blast regression. We have also identified a 47-probe set signature (which represents 41 unique genes) that was predictive of long-term outcome in our data set as well as three large independent data sets of patients with childhood ALL who were treated on different protocols. However, we did not find sufficient evidence for the added significance of these genes and the derived predictive models when other known prognostic features, such as age, WBC, and karyotype, were included in a multivariate analysis.

CONCLUSION

Genes and pathways that play a role in early blast regression may identify patients who may be at risk for inferior responses to treatment. A fully validated predictive gene expression signature was defined for high-risk ALL that provided insight into the biologic mechanisms of treatment failure.

Therapeutic advances in leukemia and myelodysplastic syndrome over the past 40 years

Major therapeutic progress has been accomplished in leukemia and myelodysplastic syndrome (MDS) over the past 40 years, which may not be fully appreciated by the larger medical community. The objective of this review was to briefly highlight the treatment breakthroughs in leukemia and MDS. Therapeutic progress happened through better understanding of disease pathophysiologies and rational development of targeted agents, like imatinib mesylate in chronic myeloid leukemia (CML), and through astute, empirical discoveries in the clinic, like all-trans retinoic acid and arsenic trioxide in acute promyelocytic leukemia (APL) and chlorodeoxyadenosine in hairy cell leukemia (HCL). Today, the 5- to 10-year survival rates in patients with APL and HCL exceed 80%. In patients with CML, imatinib therapy has been associated with estimated 5- to 7-year survival rates from 85% to 90%. In patients with adult acute lymphocytic leukemia, modern intensive regimens have improved the 5-year survival rates from 20% up to 40%. In patients with chronic lymphocytic leukemia, chemoimmunotherapy recently produced high rates of quality responses and improved long-term outcome. In younger patients with acute myeloid leukemia (AML), the 5-year survival rates range from 40% to 50%, although elderly AML remains a therapeutic challenge. In patients with MDS, it was recently demonstrated that epigenetic therapy with hypomethylating agents improved survival. Much therapeutic progress has been witnessed in leukemia and MDS, and much more is expected to occur soon.

Long-term follow-up of renal function after high-dose methotrexate treatment in children

BACKGROUND

High-dose methotrexate (HD-MTX) is commonly used in treatment of pediatric leukemias and lymphomas. Transient deterioration in renal function is frequently noted during HD-MTX treatment, but possible long-term changes are less well known. In this study we aimed to study long-term renal prognosis after HD-MTX treatment, and to find possible underlying risk factors for reduced renal function.

PROCEDURE

Medical records of pediatric cancer patients treated with HD-MTX were reviewed retrospectively after follow-up of 1-10 years. Renal function before and after chemotherapy was investigated in a total of 28 patients. Assessment of glomerular and tubular function was prospectively evaluated in each case. Glomerular function was evaluated by either (51)Cr-EDTA or (99m)Tc-DTPA clearance methods, and by urinary albumin excretion. Tubular function was assessed by measuring blood electrolyte levels and urinary alpha(1)- or beta(2)-microglobulin.

RESULTS

A decrease in glomerular filtration rate (GFR) was statistically significant as follow-up time increased (P = 0.02). Age at the time of diagnosis and exposure to potentially nephrotoxic antibiotics during cancer treatment had no influence on GFR. However, albuminuria was observed more often in patients treated with amphotericin B or gentamycin (P = 0.04). No changes in tubular function were observed.

CONCLUSIONS

Our results show that HD-MTX treatment significantly decreases GFR and may cause albuminuria in pediatric cancer patients several years after treatment. Long-term renal follow-up of these patients is therefore important.

Prednisolone inhibits PDGF-induced nuclear translocation of NF-kappaB in human pulmonary artery smooth muscle cells

Pulmonary vascular remodeling, a major cause for the elevated pulmonary vascular resistance in patients with pulmonary arterial hypertension (PAH), is partially due to increased proliferation of pulmonary arterial smooth muscle cells (PASMC) in the media, resulting in vascular wall thickening. Platelet-derived growth factor (PDGF) is a potent mitogen that may be involved in the progression of PAH. Blockade of PDGF receptors has been demonstrated to have therapeutic potential for patients with severe pulmonary hypertension. Prednisolone is an immunosuppressant shown to have anti-inflammatory and antiproliferative effects on PASMC. This study was designed to investigate whether PDGF and prednisolone affect human PASMC proliferation by regulating the nuclear translocation of NF-kappaB (a transcription factor composed of 2 subunits, p50 and p65). Treatment of human PASMC with PDGF (10 ng/ml) significantly increased nuclear translocation of p50 and p65 subunits. Inhibition of NF-kappaB activation or nuclear translocation of p50/p65 significantly attenuated PDGF-induced PASMC proliferation (determined by [(3)H]thymidine incorporation). In the presence of prednisolone (200 microM), the PDGF-induced nuclear translocation of p50 and p65 subunits was markedly inhibited (P < 0.05 vs. the cells treated with PDGF alone). These results indicate that PDGF-induced nuclear translocation of NF-kappaB may play an important role in stimulating PASMC proliferation (and/or enhancing PASMC survival), whereas prednisolone may exert anti-inflammatory and antiproliferative effects on PASMC by inhibiting NF-kappaB nuclear translocation.

Transplantation for children with acute lymphoblastic leukemia

EFS for children with ALL continues to increase and is predicted to reach 90% with current therapy. Better understanding of leukemia cell biology and pharmacogenetics has led to the design of more effective treatment and also refined the prognostic features associated with a poor outcome. ALL characterized by the translocation t(9;22) or t(4;11), or by a hypodiploid karyotype or by an incomplete response to induction therapy is likely to relapse. SCT for ALL is largely used to treat patients failing primary chemotherapy but is selectively included as part of initial therapy for children at high risk for relapse. If SCT is going to become the primary therapy for children with ALL in first remission, the regimen-related mortality must approach 0%, and the risk for severe acute and chronic GVHD should be less than 5%. Salvage therapy after ALL relapse remains the major indication for SCT. The time required to find a suitable match has led to the use of cord blood and haploidentical related donors as stem cell sources. For children who relapse, SCT is likely to remain the principal option to promote survival. Efforts to reduce both the risk of relapse and the transplant regimen toxicity, both immediate and delayed, must continue.

Factors influencing survival after relapse from acute lymphoblastic leukemia: a Children's Oncology Group study

Despite great progress in curing childhood acute lymphoblastic leukemia (ALL), survival after relapse remains poor. We analyzed survival after relapse among 9585 pediatric patients enrolled on Children's Oncology Group clinical trials between 1988 and 2002. A total of 1961 patients (20.5%) experienced relapse at any site. The primary end point was survival. Patients were subcategorized by the site of relapse and timing of relapse from initial diagnosis. Time to relapse remains the strongest predictor of survival. Patients experiencing early relapse less than 18 months from initial diagnosis had a particularly poor outcome with a 5-year survival estimate of 21.0+/-1.8%. Standard risk patients who relapsed had improved survival compared with their higher risk counterparts; differences in survival for the two risk groups was most pronounced for patients relapsing after 18 months. Adjusting for both time and relapse site, multivariate analysis showed that age (10+ years) and the presence of central nervous system disease at diagnosis, male gender, and T-cell disease were significant predictors of inferior post-relapse survival. It can be noted that there was no difference in survival rates for relapsed patients in earlier vs later era trials. New therapeutic strategies are urgently needed for children with relapsed ALL and efforts should focus on discovering the biological pathways that mediate drug resistance.

Bone-marrow relapse in paediatric acute lymphoblastic leukaemia

Marrow relapse is the major obstacle to cure for 10-15% of young patients with acute lymphoblastic leukaemia (ALL). Recent investigations into the biology of minimal residual disease indicate that many early relapses derive from residual cells present at first diagnosis, but some late relapses might represent new mutations in leukaemic cells not eliminated by conventional therapy. Treatment of marrow relapse involves higher doses and more intensive schedules of the drugs used for initial therapy with or without haemopoietic stem cell transplantation. In most reports, transplantation is better than continuation chemotherapy in early marrow relapse, but its role in later relapse is less clear. Current therapy cures 10% of patients with early marrow relapses and 50% of those with late relapses, but outcomes have changed little in the past two decades. Understanding the molecular biology of ALL underlies development of improved risk stratification and new therapies. Although better drugs are needed, introduction of new agents into clinical trials in paediatric disease has been difficult. Innovative trial designs and use of valid surrogate endpoints may expedite this process.

Allo-hematopoietic cell transplantation for Ph chromosome-positive ALL: impact of imatinib on relapse and survival

The utility of imatinib in either the pre- or post-transplant period for Ph chromosome-positive (Ph+) ALL is uncertain. In addition, there have been recent concerns regarding imatinib and cardiac toxicity. We investigated the outcome of 32 patients with Ph+ ALL who received an allo-hematopoietic cell transplant (HCT) at the University of Minnesota between 1999 and 2006. The median age at HCT was 21.9 years (range: 2.8-55.2). All patients were conditioned with CY and TBI. GVHD prophylaxis was CsA based. Of the 32 patients, 15 received imatinib therapy pre- or post-HCT (imatinib group) and 17 patients received either no imatinib (n=11) or only after relapse (n=6) (non-imatinib group). Overall survival, relapse-free survival and relapse at 2 years was 61, 67 and 13% for the imatinib group as compared with 41, 35 and 35% for the non-imatinib group (P=0.19, 0.12 and 0.20, respectively). Cardiac toxicity and TRM at 2 years were similar between groups. Thus, patients treated with imatinib in either the pre- or post-transplant setting had trends toward improved outcomes and no increase in cardiac toxicity. We suggest that imatinib be included in the peri-transplant management of all patients with Ph+ ALL.

Genome-wide copy number profiling reveals molecular evolution from diagnosis to relapse in childhood acute lymphoblastic leukemia

The underlying pathways that lead to relapse in childhood acute lymphoblastic leukemia (ALL) are unknown. To comprehensively characterize the molecular evolution of relapsed childhood B-precursor ALL, we used human 500K single-nucleotide polymorphism arrays to identify somatic copy number alterations (CNAs) in 20 diagnosis/relapse pairs relative to germ line. We identified 758 CNAs, 66.4% of which were less than 1 Mb, and deletions outnumbered amplifications by approximately 2.5:1. Although CNAs persisting from diagnosis to relapse were observed in all 20 cases, 17 patients exhibited differential CNA patterns from diagnosis to relapse. Of the 396 CNAs observed in 20 relapse samples, only 69 (17.4%) were novel (absent in the matched diagnosis samples). EBF1 and IKZF1 deletions were particularly frequent in this relapsed ALL cohort (25.0% and 35.0%, respectively), suggesting their role in disease recurrence. In addition, we noted concordance in global gene expression and DNA copy number changes (P = 2.2 x 10(-16)). Finally, relapse-specific focal deletion of MSH6 and, consequently, reduced gene expression were found in 2 of 20 cases. In an independent cohort of children with ALL, reduced expression of MSH6 was associated with resistance to mercaptopurine and prednisone, thereby providing a plausible mechanism by which this acquired deletion contributes to drug resistance at relapse.

Long-term outcome of childhood acute lymphoblastic leukemia treated in China

BACKGROUND

To retrospectively determine the treatment outcome and causes of treatment failure of ALL children treated in a single institution at East China.

PROCEDURE

Between January 1998 and October 2004, 346 newly diagnosed ALL patients <or=16 years were admitted to our hospital. Of these, 248 patients received modified National Protocol of Childhood ALL in China 1997 (NPCAC97) for at least 2 weeks of treatment and were eligible for protocol evaluation.

RESULTS

Among the 346 newly diagnosed patients, 167 (48.3%) stopped treatment either at diagnosis or during therapy. The abandonment rates for urban area group (UAG) and rural area group (RAG) were 25.3% and 57.3%, respectively (P < 0.0001). The 5-year event-free survival (EFS) rate for the entire cohort was 38.5 +/- 2.7%. For 248 evaluable patients, the remission rate was 97.2%. The 5-year EFS and overall survival (OS) rates were 70.7 +/- 3.6% and 82.1 +/- 3.0%, respectively. The 5-year EFS for standard-risk group (n = 196) was significantly higher than that of high-risk group (n = 52) (75.9 +/- 3.9% vs. 50.7 +/- 8.0%, P = 0.0002). Prognostic factor analysis showed that poor response to remission induction therapy and a poor socioeconomic status were predictive for an inferior outcome.

CONCLUSION

Abandonment of chemotherapy was the most common cause of treatment failure, which was strongly related to poor socioeconomic status and financial support. For patients who could adhere to the treatment protocol, a relatively good outcome was achieved.

[Cytogenetic and FISH findings are complementary in childhood ALL]

Primary genetic abnormalities of leukemia cells have important prognostic significance in childhood acute leukemia. In the last two years 30 newly diagnosed or recurrent childhood ALL bone marrow samples were analyzed for chromosomal abnormalities with conventional G-banding and interphase-fluorescence in situ hybridization (I-FISH) using probes to detect BCR/ABL fusions, cryptic TEL/AML1 and MLL rearrangements and p16(9p21) tumor suppressor gene deletions. G-banded karyotype analysis found clonal chromosomal aberrations in 50% of cases. With the use of complementary I-FISH techniques, ALL-specific structural and numerical changes could be identified in 70% of the patients. Nine cases (30%) had subtle chromosomal aberrations with prognostic importance that had not been detected in G-banded analysis. Conventional G-banding yielded additional information (rare and complex structural aberrations) in 19% of patients. The most common aberration (30%) was AML1 copy number increase present in G-banded hyperdiploid karyotype as a chromosome 21 tetrasomy in the majority of cases; one case displayed 5-6 copies and in another case amplification of AML1 gene on der(21) was combined with TEL/AML1 fusion of the homologue AML1 gene and deletion of the remaining TEL allele. High hiperdiploidy was detected in 6 cases, in one patient with normal G-banding karyotype. TEL/AML1 fusion signals were identified in four patients. Deletion of p16 locus was found in eight cases (23%), of which only two had cytogenetically visible rearrangements. G-banding in combination with I-FISH has produced major improvements in the sensitivity and accuracy of cytogenetic analysis of ALL patients and this method helps to achieve a more precise identification of different risk categories in order to choose the optimal treatment.

Risk factors for readmission after initial diagnosis in children with acute lymphoblastic leukemia

BACKGROUND

Specific hospital discharge criteria following the initial diagnosis of children with acute lymphoblastic leukemia (ALL) have not been reported. This retrospective cohort study was designed to identify risk factors for readmission during induction therapy, to assist with development of discharge guidelines.

PROCEDURE

We reviewed the records of 142 consecutive children with newly diagnosed B-precursor ALL and found 129 eligible patients. Chi square, t-test, and multivariate logistic regression analysis were used to compare differences in absolute neutrophil count (ANC), NCI risk status, age, type of corticosteroid administered, and other potential risk factors for readmission during induction therapy.

RESULTS

ANC at initial hospital discharge was the only significant predictor of readmission for fever during induction therapy (P = 0.006) by multivariate analysis. Specifically an ANC <or=200/mm(3) at discharge had the strongest association with readmission for fever (OR 3.3, 95% CI 1.422, 7.729).

CONCLUSION

An ANC >200/mm(3), in a clinically stable patient, is associated with minimal risk of readmission during induction therapy following the initial diagnosis of ALL.

Oral mucositis in acute lymphoblastic leukaemia: analysis of 169 paediatric patients

Chemotherapy-induced oral mucositis is a frequent therapeutic challenge in cancer patients. The purpose of this retrospective study was to estimate the prevalence and risk factors of oral mucositis in 169 acute lymphoblastic leukaemia (ALL) patients treated according to different chemotherapeutic trials at the Darcy Vargas Children's Hospital from 1994 to 2005. Demographic data, clinical history, chemotherapeutic treatment and patients' follow-up were recorded. The association of oral mucositis with age, gender, leucocyte counts at diagnosis and treatment was assessed by the chi-squared test and multivariate regression analysis. Seventy-seven ALL patients (46%) developed oral mucositis during the treatment. Patient age (P = 0.33), gender (P = 0.08) and leucocyte counts at diagnosis (P = 0.34) showed no correlation with the occurrence of oral mucositis. Multivariate regression analysis showed a significant risk for oral mucositis (P = 0.009) for ALL patients treated according to the ALL-BFM-95 protocol. These results strongly suggest the greater stomatotoxic effect of the ALL-BFM-95 trial when compared with Brazilian trials. We concluded that chemotherapy-induced oral mucositis should be systematically analysed prospectively in specialized centres for ALL treatment to establish the degree of toxicity of chemotherapeutic drugs and to improve the quality of life of patients based on more effective therapeutic and prophylactic approaches for prevention of its occurrence.

Inhibition of the Akt/survivin pathway synergizes the antileukemia effect of nutlin-3 in acute lymphoblastic leukemia cells

The phosphatidylinositol 3-kinase (PI3K)/Akt and p53 pathways play antiapoptotic and proapoptotic roles in cell death, respectively. Cancer cell growth and progression are associated with high levels of PI3K/Akt activation by loss of PTEN expression and the inactivation of p53 by MDM2 overexpression. We report that inhibition of PI3K/Akt, either by the PI3K inhibitor Ly294002 or by expression of PTEN, synergized the ability of the MDM2 antagonist nutlin-3 to induce apoptosis in acute lymphoblastic leukemia (ALL). We used a set of ALL cell lines with wild-type p53 and MDM2 overexpression, but different status of PTEN expression/PI3K/Akt activation, to test the ability of nutlin-3 to induce p53 and apoptosis. Nutlin-3 activated p53 in all the ALL cell lines; however, induction of apoptosis was dependent on PTEN status. Nutlin-3 induced potent apoptosis in cells with PTEN expression but not in those without PTEN, suggesting that PTEN/PI3K/Akt pathway may play a role in this process. Furthermore, nutlin-3 significantly down-regulated survivin expression in PTEN-positive cells but not in PTEN-negative cells. When these nutlin-3-resistant cells were either pretransfected with the PTEN gene or simultaneously treated with the PI3K inhibitor Ly294002, survivin was down-regulated and sensitivity to nutlin-3 was increased. Furthermore, direct silencing of survivin by small interfering RNA also increased the proapoptotic effect of nutlin-3 on the PTEN-negative, nutlin-3-resistant ALL cells. Our results suggest that Akt-mediated survivin up-regulation in PTEN-negative ALL cells may counteract the proapoptotic effect of nutlin-3, and indicate that a combination of MDM2 antagonist and PI3K/Akt inhibitor may be a promising approach for treating refractory ALL.

Allogeneic SCT in refractory or relapsed adult ALL is effective without prior reinduction chemotherapy

We present 60 patients with refractory (n=8) or relapsed (n=52) adult ALL who received allogeneic hematopoietic SCT (HSCT) with (n=41) or without (n=19) prior reinduction chemotherapy. In our center, omission of reinduction is recommended if a suitable donor is promptly available, tumor burden is moderate and disease features suggest a highly aggressive course. Overall survival (OS) of the whole cohort at 1, 2 and 5 years was 42, 33 and 28%, respectively. Leukemia-free survival at 1, 2 and 5 years was 37, 33 and 24%. Deaths were due to relapse (n=25), acute or chronic GVHD (n=7), infections (n=8) or toxicity (n=4). Interestingly, patients who did not receive reinduction before HSCT had better outcomes than patients who received reinduction with OS at 1, 2 and 5 years being 58 vs 34%, 47 vs 25% and 47 vs 18%, respectively (P=0.039). Importantly, even achievement of a second CR after reinduction was not associated with improved survival compared to patients directly proceeding to HSCT. We conclude that patients who undergo HSCT for refractory or relapsed ALL can achieve long-term survival. In selected patients, reinduction chemotherapy can be omitted if immediate HSCT is feasible.

Cloning of genes involved in chromosomal translocations by high-resolution single nucleotide polymorphism genomic microarray

High-resolution single nucleotide polymorphism genomic microarray (SNP-chip) is a useful tool to define gene dosage levels over the whole genome, allowing precise detection of deletions and duplications/amplifications of chromosomes in cancer cells. We found that this new technology can also identify breakpoints of chromosomes involved in unbalanced translocations, leading to identification of fusion genes. Using this technique, we found that the PAX5 gene was rearranged to a variety of partner genes including ETV6, FOXP1, AUTS2, and C20orf112 in pediatric acute lymphoblastic leukemia (ALL). The 3' end of the PAX5 gene was replaced by the partner gene. The PAX5 fusion products bound to PAX5 recognition sequences as strongly as wild-type PAX5 and suppressed its transcriptional activity in a dominant-negative fashion. In human B cell leukemia cells, binding of wild-type PAX5 to a regulatory region of BLK, one of the direct downstream target genes of PAX5, was diminished by expression of the PAX5-fusion protein, leading to repression of BLK. Expression of PAX5-fusion genes in murine bone marrow cells blocked development of mature B cells. PAX5-fusion proteins may contribute to leukemogenesis by blocking differentiation of hematopoietic cells into mature B cells. SNP-chip is a powerful tool to identify fusion genes in human cancers.

Molecularly targeted therapies for pediatric acute myeloid leukemia: progress to date

While acute myeloid leukemia (AML) is significantly less common than acute lymphoblastic leukemia (ALL) in childhood, it is significantly more deadly with only half as many children likely to be cured with standard therapy. In addition, the typical treatment for AML is among the most toxic of treatments for pediatric cancer; it includes intensive multiagent chemotherapy and, often, hematopoietic stem cell transplantation. Given the poor prognosis of pediatric AML and the significant toxicity of standard AML therapy, novel therapies are needed. Improved understanding of the molecular and cellular biology of leukemia has facilitated the development of molecularly targeted therapies. In this article, we review progress to date with agents that are showing promise in the treatment of pediatric AML including targeted immunoconjugates, inhibitors of signaling molecules (e.g. FMS-like tyrosine kinase 3 [FLT3], farnesyltransferase, and mammalian target of rapamycin [mTOR]), agents that target epigenetic regulation of gene expression (DNA methyltransferase inhibitors and histone deacetylase inhibitors), and proteasome inhibitors. For the specific agents in each of these classes, we summarize the published preclinical data and the clinical trials that have been completed, are in progress, or are being planned for children with AML. Finally, we discuss potential challenges to the success of molecularly targeted therapy including demonstrating adequate targeting of leukemia stem cells, developing synergistic and tolerable combinations of agents, and designing adequately powered clinical trials to test efficacy in molecularly defined subsets of patients.

Molecular-genetic insights in paediatric T-cell acute lymphoblastic leukaemia

Paediatric T-cell acute lymphoblastic leukaemia (T-ALL) is an aggressive malignancy of thymocytes that accounts for about 15% of ALL cases and for which treatment outcome remains inferior compared to B-lineage acute leukaemias. In T-ALL, leukemic transformation of maturating thymocytes is caused by a multistep pathogenesis involving numerous genetic abnormalities that drive normal T-cells into uncontrolled cell growth and clonal expansion. This review provides an overview of the current knowledge on onco- and tumor suppressor genes in T-ALL and suggests a classification of these genetic defects into type A and type B abnormalities. Type A abnormalities may delineate distinct molecular-cytogenetic T-ALL subgroups, whereas type B abnormalities are found in all major T-ALL subgroups and synergize with these type A mutations during T-cell pathogenesis.

Genetic polymorphism of inosine triphosphate pyrophosphatase is a determinant of mercaptopurine metabolism and toxicity during treatment for acute lymphoblastic leukemia

The influence of genetic polymorphism in inosine triphosphate pyrophosphatase (ITPA) on thiopurine-induced adverse events has not been investigated in the context of combination chemotherapy for acute lymphoblastic leukemia (ALL). This study investigated the effects of a common ITPA variant allele (rs41320251) on mercaptopurine metabolism and toxicity during treatment of children with ALL. Significantly higher concentrations of methyl mercaptopurine nucleotides were found in patients with the nonfunctional ITPA allele. Moreover, there was a significantly higher probability of severe febrile neutropenia in patients with a variant ITPA allele among patients whose dose of mercaptopurine had been adjusted for TPMT genotype. In a cohort of patients whose mercaptopurine dose was not adjusted for TPMT phenotype, the TPMT genotype had a greater effect than the ITPA genotype. In conclusion, genetic polymorphism of ITPA is a significant determinant of mercaptopurine metabolism and of severe febrile neutropenia, after combination chemotherapy for ALL in which mercaptopurine doses are individualized on the basis of TPMT genotype.

Extranodal NK/T-cell lymphoma: diagnosis and treatment cues

Extranodal NK/T-cell lymphoma, nasal type (ENKL) is mostly endemic to East Asia. It predominantly occurs in the nasal or paranasal areas and less frequently in the skin. Most of the tumours show NK-cell, but rarely T-cell, phenotypes. The Epstein-Barr virus (EBV) genome can be usually detected in lymphoma cells. Geographic localization of ENKL matches the endemic distribution of EBV, suggesting that EBV plays an important role in lymphomagenesis. Originally, NK-cell and T-cell types were believed to present the same clinicopathologic characteristics, but recent data suggest more aggressive characteristics for the NK-cell phenotype. Although ENKL is sensitive to radiotherapy, it shows a poorer response to chemotherapeutic agents than other lymphomas due to expression of p-glycoprotein. Therefore, new therapeutic approaches must be considered. Several new clinical trials are now being conducted in East Asia.

Development of gene therapy for blood disorders

The concept of introducing genes into human cells for therapeutic purposes developed nearly 50 years ago as diseases due to defects in specific genes were recognized. Development of recombinant DNA techniques in the 1970s and their application to the study of mouse tumor viruses facilitated the assembly of the first gene transfer vectors. Vectors of several different types have now been developed for specific applications and over the past decade, efficacy has been demonstrated in many animal models. Clinical trials began in 1989 and by 2002 there was unequivocal evidence that children with severe combined immunodeficiency could be cured by gene transfer into primitive hematopoietic cells. Emerging from these successful trials was the realization that proto-oncogene activation by retroviral integration could contribute to leukemia. Much current effort is focused on development of safer vectors. Successful gene therapy applications have also been developed for control of graft-versus-host disease and treatment of various viral infections, leukemias, and lymphomas. The hemophilias seem amenable to gene therapy intervention and informative clinical trials have been conducted. The hemoglobin disorders, an early target for gene therapy, have proved particularly challenging although ongoing research is yielding new information that may ultimately lead to successful clinical trials.

Completion of premaintenance phases in total therapies 2 and 3 improves clinical outcomes in multiple myeloma: an important variable to be considered in clinical trial designs

BACKGROUND

Total Therapy (TT) programs are complex and their execution over the course of several years is fraught with patient attrition due to failure and toxicity of therapy and patient/physician acceptance.

METHODS

The impact of completion versus noncompletion of intended treatment steps was examined in protocols TT2 (n=668) and TT3 (n=303) on overall survival (OS) and event-free survival (EFS).

RESULTS

By using appropriate landmarks of 36 months with TT2 and 18 months with TT3, representing the maxima to completion of premaintenance phases, postconsolidation OS was superior for 211 patients completing versus 311 patients not completing premaintenance steps on TT2 (P=.001), which also pertained to the 161 patients completing versus 47 not completing intended treatment steps on TT3 (P=.01). On multivariate analysis that included all patients, completion of therapy independently favored longer OS and EFS in the context of both standard prognostic factors and gene expression profiling-defined risk; in addition, TT3 prolonged EFS over results obtained with TT2.

CONCLUSIONS

1) Completion of intended therapy was a significant independent variable conferring superior OS and EFS in TT programs; and 2) after adjusting for completion of therapy, EFS was still superior with TT3 versus TT2, supporting the beneficial role of bortezomib included in TT3. Collectively, these data point to the importance of designing clinical trials that balance the treatment requirements for disease control with host acceptance and tolerance.

Improved outcome for children with acute lymphoblastic leukemia after risk-adjusted intensive therapy: a single-institution experience

BACKGROUND AND OBJECTIVE

Because of the need for more comprehensive information on the least toxic and most effective forms of therapy for children with acute lymphoblastic leukemia (ALL), we reviewed our experience in the treatment of children with ALL at King Faisal Specialist Hospital and Research Centre (KFSH&RC) and King Fahad National Center for Children's Cancer and Research (KFNCCC&R) over a period of 18 years with a focus on patient characteristics and outcome.

METHODS

During the period of 1981 to 1998, records of children with ALL were retrospectively reviewed with respect to clinical presentation, laboratory findings, risk factors, stratification, therapy and outcome. The protocols used in treatment included 4 local protocols (KFSH 81, 84, 87 and 90), and subsequently, Children's Cancer Group (CCG) protocols, and these were grouped as Era 1 (1981-1992) and Era 2 (1993-1998).

RESULTS

Of 509 children with ALL treated during this period, 316 were treated using local protocols and 193 using CCG protocols. Drugs used in Era 1 included a 4-drug induction using etoposid (VP-16) instead of L-asparaginase. Consolidation was based on high dose methotrexate (MTX) 1 g/m(2) and maintenance was based on oral mercaptopurine (6-MP) and MTX with periodic pulses using intravenous teniposide (VM-26), Ara-C, L-asparaginase, adriamycin, prednisone, VP-16 and cyclophosphamide. International protocols were introduced in Era 2, which was also marked by intensification of early treatment, a wider selection of cytoreductive agents, and the alternating use of non-cross-resistant pairs of drugs during the post-remission period. The end-of-induction remission rate improved from 90% in Era 1 to 95% in Era 2, which was of borderline statistical significance (P=.049). The 5-year event-free survival (EFS) improved from 30.6% in Era 1 to 64.2% in Era 2 (P<.001). Improvement in outcome was achieved without any significant increase in morbidity or mortality, due to improvement in both systemic therapy and supportive care. The most important independent prognostic factors were intensity of therapy, poor risk category assignment and CNS disease at diagnosis.

CONCLUSION

Outcome in children with ALL has improved because of intensification of treatment protocols and better supportive care.

Clinical utility of array comparative genomic hybridization for detection of chromosomal abnormalities in pediatric acute lymphoblastic leukemia

BACKGROUND

Accurate detection of recurrent chromosomal abnormalities is critical to assign patients to risk-based therapeutic regimens for pediatric acute lymphoblastic leukemia (ALL).

PROCEDURE

We investigated the utility of array comparative genomic hybridization (aCGH) for detection of chromosomal abnormalities compared to standard clinical evaluation with karyotype and fluorescent in situ hybridization (FISH). Fifty pediatric ALL diagnostic bone marrows were analyzed by bacterial artificial chromosome (BAC) array and findings compared to standard clinical evaluation.

RESULTS

Sensitivity of aCGH was 79% to detect karyotypic findings other than balanced translocations, which cannot be detected by aCGH because they involve no copy number change. aCGH also missed abnormalities occurring in subclones constituting less than 25% of cells. aCGH detected 44 additional abnormalities undetected or misidentified by karyotype with 21 subsequently validated by FISH, including abnormalities in 4 of 10 cases with uninformative cytogenetics. aCGH detected concurrent terminal deletions of both 9p and 20q in three cases, in two of which the 20q deletion was undetected by karyotype. A narrow region of loss at 7p21 was detected in two cases.

CONCLUSIONS

aCGH detects the majority of karyotypic findings other than balanced translocations, and may provide key prognostic information in the approximately 35% of cases with uninformative cytogenetics.

Neuropsychological Outcome in Chemotherapy-Only–Treated Children With Acute Lymphoblastic Leukemia

Purpose

To evaluate neuropsychological functioning over time in children treated for acute lymphoblastic leukemia (ALL) with chemotherapy only.

Patients and Methods

Forty-nine consecutive patients (median age at first assessment, 6.8 years; range, 4.0 to 11.8 years) treated with intrathecal and systemic chemotherapy were included in a nationwide, prospective-longitudinal, sibling-controlled study. Patients and siblings completed three extensive neuropsychological assessments: at diagnosis, 3 to 6 months after completion of (2-year) treatment and 4.5 years after diagnosis. Assessments included measures of learning, memory, attention, speed, executive functioning, visual-constructive functioning, and fine-motor functioning. Multilevel analyses were applied to evaluate patients' performances over time and to compare patients to 29 siblings (median age of siblings at first assessment, 8.2 years; range, 4.5 to 12.6 years) and to normative data.

Results

No major differences were found in neuropsychological performance between patients and siblings, with both groups performing mainly in the normal range. The patient group as a whole, however, scored significantly lower than the siblings on complex fine-motor functioning at the last evaluation. Large practice effects were found for both patients and siblings in four of 11 tasks. Patients who uttered physical complaints (ie, pain and/or tiredness) at the first pretreatment assessment scored significantly lower than siblings on attention and speed at the last two evaluations.

Conclusion

Despite intensive and potentially neurotoxic treatment, no evident negative, neuropsychological late effects were found 4.5 years after diagnosis, except for effects on complex fine-motor functioning. Both the large practice effects observed and the poorer performances on sustained attention for patients with physical complaints should be reckoned with in prospective, longitudinal neuropsychological research in children.

Initial leukemic gene expression profiles of patients with poor in vivo prednisone response are similar to those of blasts persisting under prednisone treatment in childhood acute lymphoblastic leukemia

Response to initial glucocorticoid (GC) treatment is a strong prognostic factor in childhood acute lymphoblastic leukemia (ALL). Patients with a poor prednisone response (PPR) have a poor event-free survival as compared to those with a good prednisone response (PGR). Causes of prednisone resistance are still not well understood. We hypothesized that GC resistance is an intrinsic feature of ALL cells which is reflected in the gene expression pattern and analyzed genome-wide gene expression using microarrays. A case-control study was performed comparing gene expression profiles from initial ALL samples of 20 patients with PPR and those of 20 patients with PGR. Differential gene expression of a subset of genes was confirmed by real-time quantitative polymerase chain reaction analysis and validation was performed in a second independent patient sample (n=20). We identified 121 genes that clearly distinguished prednisone-resistant from sensitive ALL samples (FDR<5%, fold change>or=1.5). Differential gene expression of 21 of these genes could be validated in a second independent set. Of importance, there was a remarkable concordance of genes identified by comparing expression signatures of PPR and PGR cells at diagnosis and those previously described to be up- or downregulated in leukemic cells persisting under GC treatment. Thus, GC resistance seems at least in part to be an intrinsic feature of leukemic cells. Leukemic cells of patients with PPR are characterized by gene expression pattern which are similar to those of resistant cells persisting under glucocorticoid treatment.

Survival and predictors of outcome in patients with acute leukemia admitted to the intensive care unit

BACKGROUND

Predictors of outcome and rates of successful discharge have not been defined for patients with acute leukemia admitted to intensive care units (ICUs) in the US.

METHODS

This is a retrospective analysis of 90 patients with acute leukemia (no history of bone marrow transplant) admitted to an ICU from 2001-2004. The primary endpoints were improvement and subsequent discharge from the ICU, discharge from the hospital, and 2-month survival after hospital discharge. Secondary endpoints were 6- and 12-month survival. Univariate and multivariate logistic regression analyses were performed to identify factors predicting outcome.

RESULTS

The median age of patients was 54 years and 48 (53%) were male. The most common reason for ICU transfer for all patients was respiratory compromise. The majority of all patients (68%) were eventually placed on ventilator support and approximately half required pressors. During the ICU course, 29 patients (32%) improved and subsequently resumed aggressive leukemia management, and 24 patients (27%) survived to be discharged from the hospital. The 2-, 6-, and 12-month overall survival was 24 (27%), 16 (18%), and 14 (16%), respectively. Higher APACHE II score, use of pressors, undergoing bone marrow transplantation preparative regimen, and adverse cytogenetics predicted worse outcome. Newly diagnosed leukemia, type of leukemia, or age did not.

CONCLUSIONS

One of 4 patients with acute leukemia survived an ICU admission to be discharged from the hospital and were alive 2 months later. A diagnosis of acute leukemia should not disqualify patients from an ICU admission.

Diabetic ketoacidosis during therapy for pediatric acute lymphoblastic leukemia

BACKGROUND

Hyperglycemia is common during therapy for acute lymphoblastic leukemia (ALL), but diabetic ketoacidosis (DKA) occurs rarely. Morbidity due to DKA in children with ALL has not been systematically studied.

PROCEDURES

We reviewed risk factors and clinical consequences of DKA in patients undergoing therapy for ALL at SJCRH between 1991 and 2006.

RESULTS

DKA occurred in 6 of 797 evaluable patients. Only older age at diagnosis of ALL was a risk factor for DKA. Four of six patients with DKA as compared to 232 of the other 791 patients were older than 10 years (P = 0.03). Race, sex, body mass index, leukemia immunophenotype, ALL risk category, white blood cell count at diagnosis, and treatment protocol were not associated with DKA. All patients were managed with intravenous fluids, dietary modification, and short-term use of insulin. Patients were hospitalized for 4-12 days, with a median ICU stay of 1 day. In two patients, correction of hyperglycemia was too rapid, and two others experienced hypoglycemia due to insulin therapy. There were no permanent complications of DKA or its treatment. No patient required long-term insulin use. No patient had recurrent DKA; only one of the six patients had a subsequent hyperglycemia episode. All six patients are alive in remission 6-13 years after diagnosis.

CONCLUSIONS

Patients with hyperglycemia during treatment for ALL should be screened for clinical evidence of DKA, which may require more intensive supportive care than those without ketoacidosis. The occurrence of DKA should not lead to alteration of ALL treatment.

Phase II study of topotecan in combination with dexamethasone, asparaginase, and vincristine in pediatric patients with acute lymphoblastic leukemia in first relapse

BACKGROUND

The authors evaluated the response rate, toxicity, and pharmacokinetics of topotecan given before standard induction therapy for childhood acute lymphoblastic leukemia (ALL) in first relapse.

METHODS

Patients received topotecan (2.4 mg/m(2) daily as a 30-minute infusion) for 5 days before induction therapy with dexamethasone, vincristine, and asparaginase (native or pegylated Escherichia coli). The pharmacokinetics of topotecan were measured with the first dose of treatment in 23 patients.

RESULTS

Twenty-eight of 31 patients with circulating blast cells were evaluable for response to topotecan. Twenty-five patients (89.3%) had a response (>25% decrease in circulating blast cells). The leukocyte count (P = .0001) and blast cell count (P = .0009) declined significantly during topotecan therapy. The median (range) topotecan lactone area under the concentration-time curve after the first dose was 85.4 L/hour/m(2) (range, 38.7-229.3 L/hour/m(2)). At the end of induction, 23 patients (74.2%) had a complete response, 1 patient (3.2%) had a partial response, 5 patients (16.1%) had no response, and 2 patients had died of infection. Six of the 17 patients who were studied for minimal residual disease (MRD) achieved MRD-negative status at the end of induction. The main toxicities were hematologic, gastrointestinal, and hepatic. The estimated 5-year survival rate, event-free survival rate, and cumulative incidence of second relapse were 24.1% +/- 7.9%, 18.2% +/- 7.4%, and 22.8% +/- 8.7%, respectively, in the 29 patients who had a hematologic first relapse.

CONCLUSIONS

A regimen comprising single-agent topotecan given with a standard 3-drug combination was effective in inducing remission in pediatric patients with relapsed ALL and was tolerated well.

Thalidomide arm of Total Therapy 2 improves complete remission duration and survival in myeloma patients with metaphase cytogenetic abnormalities

Total Therapy 2 examined the clinical benefit of adding thalidomide up-front to a tandem transplant regimen for newly diagnosed patients with multiple myeloma. When initially reported with a median follow-up of 42 months, complete response rate and event-free survival were superior among the 323 patients randomized to thalidomide, whereas overall survival was indistinguishable from that of the 345 patients treated on the control arm. With further follow-up currently at a median of 72 months, survival plots segregated 5 years after initiation of therapy in favor of thalidomide (P = .09), reaching statistical significance for the one third of patients exhibiting cytogenetic abnormalities (CAs; P = .02), a well-recognized adverse prognostic feature. The duration of complete remission was also superior in the cohort presenting with CAs such that, at 7 years from onset of complete remission, 45% remained relapse-free as opposed to 20% on the control arm (P = .05). These observations were confirmed when examined by multivariate analysis demonstrating that thalidomide reduced the hazard of death by 41% among patients with CA-positive disease (P = .008). Because two thirds of patients without CAs have remained alive at 7 years, the presently emerging separation in favor of thalidomide may eventually reach statistical significance as well.

Prospective analysis of TEL gene rearrangements in childhood acute lymphoblastic leukemia: a Children's Oncology Group study

PURPOSE

To prospectively determine the prognostic significance of the TEL-AML1 fusion in children with acute lymphoblastic leukemia (ALL).

PATIENTS AND METHODS

TEL gene status was determined for 926 patients with B-precursor ALL enrolled on the Pediatric Oncology Group ALinC 16 trials and patients were observed for a median time of 8 years.

RESULTS

Rearrangements of the TEL gene were detected in 244 patients (26%). The estimated 5-year event-free survival rate (+/- SE) for patients with TEL rearrangements was 86% +/- 2%, compared with 72% +/- 2% for those with germline TEL (P < .0001). TEL rearrangements were associated with a superior outcome among patients with standard-risk ALL, high-risk ALL, and rapid early responses to therapy. In a multivariate analysis that included risk group, sex, and day 15 marrow status, TEL status was an independent predictor of outcome (P = .0002).

CONCLUSION

We conclude that TEL gene status should be incorporated into risk classification schemes and suggest that patients who have standard-risk features, the TEL-AML1 fusion, and rapid early responses to therapy, should be treated with antimetabolite-based therapy designed to maintain their high cure rates and avoid late effects.

Implementing an intervention to improve bone mineral density in survivors of childhood acute lymphoblastic leukemia: BONEII, a prospective placebo-controlled double-blind randomized interventional longitudinal study design

The BONEII study is a large two-phase study. The baseline study (Study 1) aims to estimate the prevalence of diminished bone mineral density (BMD) in patients treated for childhood acute lymphoblastic leukemia (ALL) and identify risk factors for BMD deficits. The interventional phase (Study 2) of BONEII has a placebo-controlled double-blind randomized longitudinal design to evaluate the effects of nutritional counseling and calcium and vitamin D supplementation on changes in BMD and serum and urine markers of bone metabolism. The extensive information being collected through this large study will serve as a repository of relational data about BMD and bone turnover and will support further investigations to assess the association of calcium metabolism, bone turnover, nutritional intake, lifestyle factors (such as exercise and the use of alcohol and tobacco), and the specific agents used in ALL therapy in this rapidly increasing population of childhood cancer survivors.

Comparison of the results of the treatment of adolescents and young adults with standard-risk acute lymphoblastic leukemia with the Programa Español de Tratamiento en Hematología pediatric-based protocol ALL-96

PURPOSE

Retrospective studies have shown that adolescents and young adults with acute lymphoblastic leukemia (ALL) treated with pediatric protocols have better outcomes than similarly aged patients treated with adult protocols, but prospective studies comparing adolescents and young adults using pediatric schedules are scarce. The ALL-96 protocol was addressed to compare the toxicity and results of a pediatric-based protocol in adolescents (age 15-18 years) and young adults (age 19-30 years) with standard-risk (SR) ALL.

PATIENTS AND METHODS

Adolescents (n = 35) and young adults (n = 46) received a standard five-drug/5-week induction course followed by two cycles of early consolidation, maintenance with monthly reinforcement cycles up to 1 year in continuous complete remission (CR) and 1 year with standard maintenance chemotherapy up to 2 years in CR.

RESULTS

Adolescents and young adults were comparable in the main pretreatment ALL characteristics. The CR rate was 98% and. after a median follow-up of 4.2 years, 6-year event-free survival (EFS) and overall survival (OS) were 61% (95% CI, 51% to 72%) and 69% (95% CI, 59% to 79%), respectively, with no differences between adolescents and young adults. The hematologic toxicity in consolidation and reinforcement cycles was higher in young adults than in adolescents. Slow response to induction therapy was the only parameter associated with poor EFS (34% v 67%) and OS (40% v 76%).

CONCLUSION

The response to the pediatric ALL-96 protocol was identical in adolescents and young adults despite a slight increase in hematologic toxicity observed in adults. This justifies the age-unrestricted use of pediatric regimens to treat patients with SR ALL.

Influence of MTHFR and RFC1 polymorphisms on toxicities during maintenance chemotherapy for childhood acute lymphoblastic leukemia or lymphoma

We investigated preliminarily whether methylenetetrahydrofolate reductase (MTHFR) 677C/T or reduced folate carrier 1 (RFC1) 80G/A polymorphisms were associated with toxicities during maintenance chemotherapy with mercaptopurine (6MP) and methotrexate (MTX) in children with acute lymphoblastic leukemia or lymphoblastic lymphoma. The clinical records of 20 children (2 to 15-y old) who had received maintenance chemotherapy were reviewed retrospectively and their genomic DNA was genotyped to identify polymorphisms at MTHFR 677C/T, RFC1 80G/A, and thiopurine methyltransferase 719A/G. Maintenance chemotherapy with 6MP and MTX was repeated on a weekly basis, and any week during which 6MP and/or MTX dosing was withheld was counted as an interrupted episode. Associations between the risk of interruptions and polymorphisms were studied using a generalized estimating equation analysis. Patients with an increasing number of T alleles at MTHFR 677C/T experienced interruptions in both 6MP (P<0.01) and MTX (P=0.03) more frequently. Patients with an increasing number of A alleles at RFC1 80G/A experienced interruptions in 6MP (P=0.04) more frequently. This preliminary study does not prove but suggests that MTHFR 677C/T and RFC1 80G/A polymorphisms may serve as predictors of toxicity during maintenance chemotherapy.

CD34+CD38+CD19+ as well as CD34+CD38-CD19+ cells are leukemia-initiating cells with self-renewal capacity in human B-precursor ALL

The presence of rare malignant stem cells supplying a hierarchy of malignant cells has recently been reported. In human acute myelogenous leukemia (AML), the leukemia stem cells (LSCs) have been phenotypically restricted within the CD34+CD38- fraction. To understand the origin of malignant cells in primary human B-precursor acute lymphocytic leukemia (B-ALL), we established a novel in vivo xenotransplantation model. Purified CD34+CD38+CD19+, CD34+CD38-CD19+ and CD34+CD38-CD19- bone marrow (BM) or peripheral blood (PB) cells from three pediatric B-ALL patients were intravenously injected into sublethally irradiated newborn NOD/SCID/IL2rgamma(null) mice. We found that both CD34+CD38+CD19+ and CD34+CD38-CD19+ cells initiate B-ALL in primary recipients, whereas the recipients of CD34+CD38-CD10-CD19- cells showed normal human hematopoietic repopulation. The extent of leukemic infiltration into the spleen, liver and kidney was similar between the recipients transplanted with CD34+CD38+CD19+ cells and those transplanted with CD34+CD38-CD19+ cells. In each of the three cases studied, transplantation of CD34+CD38+CD19+ cells resulted in the development of B-ALL in secondary recipients, demonstrating self-renewal capacity. The identification of CD34+CD38+CD19+ self-renewing B-ALL cells proposes a hierarchy of leukemia-initiating cells (LICs) distinct from that of AML. Recapitulation of patient B-ALL in NOD/SCID/IL2rgamma(null) recipients provides a powerful tool for directly studying leukemogenesis and for developing therapeutic strategies.

In vivo response to methotrexate forecasts outcome of acute lymphoblastic leukemia and has a distinct gene expression profile

BACKGROUND

Childhood acute lymphoblastic leukemia (ALL) is the most common cancer in children, and can now be cured in approximately 80% of patients. Nevertheless, drug resistance is the major cause of treatment failure in children with ALL. The drug methotrexate (MTX), which is widely used to treat many human cancers, is used in essentially all treatment protocols worldwide for newly diagnosed ALL. Although MTX has been extensively studied for many years, relatively little is known about mechanisms of de novo resistance in primary cancer cells, including leukemia cells. This lack of knowledge is due in part to the fact that existing in vitro methods are not sufficiently reliable to permit assessment of MTX resistance in primary ALL cells. Therefore, we measured the in vivo antileukemic effects of MTX and identified genes whose expression differed significantly in patients with a good versus poor response to MTX.

METHODS AND FINDINGS

We utilized measures of decreased circulating leukemia cells of 293 newly diagnosed children after initial "up-front" in vivo MTX treatment (1 g/m(2)) to elucidate interpatient differences in the antileukemic effects of MTX. To identify genomic determinants of these effects, we performed a genome-wide assessment of gene expression in primary ALL cells from 161 of these newly diagnosed children (1-18 y). We identified 48 genes and two cDNA clones whose expression was significantly related to the reduction of circulating leukemia cells after initial in vivo treatment with MTX. This finding was validated in an independent cohort of children with ALL. Furthermore, this measure of initial MTX in vivo response and the associated gene expression pattern were predictive of long-term disease-free survival (p < 0.001, p = 0.02).

CONCLUSIONS

Together, these data provide new insights into the genomic basis of MTX resistance and interpatient differences in MTX response, pointing to new strategies to overcome MTX resistance in childhood ALL.

TRIAL REGISTRATIONS

Total XV, Therapy for Newly Diagnosed Patients With Acute Lymphoblastic Leukemia, http://www.ClinicalTrials.gov (NCT00137111); Total XIIIBH, Phase III Randomized Study of Antimetabolite-Based Induction plus High-Dose MTX Consolidation for Newly Diagnosed Pediatric Acute Lymphocytic Leukemia at Intermediate or High Risk of Treatment Failure (NCI-T93-0101D); Total XIIIBL, Phase III Randomized Study of Antimetabolite-Based Induction plus High-Dose MTX Consolidation for Newly Diagnosed Pediatric Acute Lymphocytic Leukemia at Lower Risk of Treatment Failure (NCI-T93-0103D).

Interaction of acute lymphopblastic leukemia cells with C-type lectins DC-SIGN and L-SIGN

The C-type lectins DC-SIGN (CD209) and L-SIGN (CD299) recognize defined carbohydrates expressed on pathogens and cells. Those lectins are expressed on dendritic cells (DC) and/or on liver-sinusoidal endothelial cells. Both cell types modulate immune responses. In acute lymphoblastic leukemia (ALL), aberrant glycosylation of blast cells can alter their interaction with the C-type lectins DC-SIGN and L-SIGN, thereby affecting their immunological elimination. We investigated whether recombinant DC-SIGN and L-SIGN bind to blood or bone marrow cells from B- and T-ALL patients and compared that with binding of peripheral blood lymphocytes from healthy donors. It was found that increased binding of ALL cells to DC-SIGN and L-SIGN was observed compared to cells from healthy donors. Furthermore, L-SIGN bound a higher percentage of leukemic and normal cells than DC-SIGN. B-ALL bone marrow cells showed the highest binding to L-SIGN. DC-SIGN bound equally well to B-ALL and T-ALL cells. Within ALL subtypes, DC-SIGN binding was higher with mature T-ALL. Interestingly, our data demonstrate that increased binding of DC-SIGN and L-SIGN to peripheral leukemic cells from B-ALL patients is associated with poor survival. These data demonstrate that high binding of B-ALL peripheral blood cells to DC-SIGN and L-SIGN correlates with poor prognosis. Apparently, when B-ALL cells enter the blood circulation and are able to interact with DC-SIGN and L-SIGN the immune response is shifted toward tolerance. Additional studies are necessary to ascertain the possible role of these results in terms of disease pathogenesis and their potential as target to eradicate leukemic cells.

The genetics of cancer survivorship

Constitutional (hereditary) genetic variation and somatic genetic alterations acquired during transformation to the neoplastic phenotype are both critical determinants of cancer outcome, and can ultimately have a significant effect on cancer survivorship. This article discusses the role of constitutional and somatic genetics in determining outcome and survivorship following a diagnosis of cancer using illustrative examples primarily from the hematologic malignancies.

Effects of prednisolone on specifically expressed genes in pediatric acute B-lymphoblastic leukemia

Although glucocorticoid is essential in the treatment of pediatric acute lymphoblastic leukemia (ALL), their precise mechanisms of action remain unclear. We used DNA microarray to evaluate prednisolone-regulated genes in pre-B-ALL cells from 2 pediatric patients. We found up-regulation of 26 genes in ALL cells from both patients, compared with peripheral normal B lymphocytes before maintenance chemotherapy. Treatment with prednisolone for 48 hours induced down-regulation of 5 genes (terminal deoxynucleotidyl transferase, heparin-binding epidermal growth factorlike growth factor, pre-B-lymphocyte genes 1 and 3, and immunoglobulin lambda-like polypeptide) among 26 specifically expressed genes in pre-B-ALL cells from both patients.

Outcomes of a modified CALGB 19802 regimen in adult acute lymphoblastic leukemia

We analyzed the efficacy and toxicity of a modified Cancer and Leukemia Group B (CALGB) 19802 regimen in adult acute lymphoblastic leukemia (ALL). From February 2002 to August 2005, 25 adults with untreated ALL were enrolled in the study. Compared to the original regimen, the modified CALGB 19802 regimen consisted of a 4-drug induction (cyclophosphamide, daunorubicin, vincristine, and prednisone) instead of a 5-drug induction (L-asparaginase was added to the previous regimen). This was followed by high-dose methotrexate (1,000 mg/m(2) x 3 days) and cytarabine (2,000 mg/m(2) x 4 days) for the consolidation cycles. High-dose systemic and intrathecal methotrexate was given for central nervous system prophylaxis. Twenty-three patients (92%) achieved a complete remission (CR), and two patients (8%) had refractory disease. With a median follow-up of 21.5 months, 10 patients (40%) were alive and continued to be in CR. The 3-yr probability of an event-free survival and the overall survival were 39.0% and 47.4%, respectively. Treatment related mortality and major grade 3 to 4 neurotoxicity occurred in 1 patient and 3 patients, respectively. The modified CALGB 19802 regimen demonstrated a high remission rate and a favorable survival rate.