Induction Therapy For Acute Lymphoblastic Leukemia Research Articles

No evidence that G6PD deficiency affects the efficacy or safety of daunorubicin in acute lymphoblastic leukemia induction therapy.

Anthracyclines are used in induction therapy of pediatric acute lymphoblastic leukemia (ALL) and are known to generate oxidative stress; whether this translates into enhanced antileukemic activity or hemolytic effects in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency is unknown. Among 726 pediatric patients with newly diagnosed ALL treated at St. Jude Children's Research Hospital, 22 had deficient G6PD activity. We compared the prevalence of positive minimal residual disease (MRD) ≥1% at Day 15/Day 19 of induction or ≥0.01% at Day 42/Day 46 (end of induction) and the number of red blood cell (RBC) transfusions after daunorubicin in induction between patients with or without G6PD deficiency, adjusting for ALL risk group, treatment protocol, age, and gender. There was no difference in Day 15/19 (P=1) or end of induction MRD (P=0.76) nor in the number of RBC transfusions (P=0.73); the lack of association with MRD was confirmed in a dataset of 1192 newly diagnosed male patients enrolled in a Children's Oncology Group trial (P=0.78). We found no evidence that G6PD deficiency affects daunorubicin activity during induction treatment for ALL.

Minimal Residual Disease Risk-Stratification in Pediatric Mixed Phenotype Acute Leukemia: Results of a Multi-Center Cohort Study

BACKGROUNDMixed phenotype acute leukemia (MPAL) is a rare form of leukemia in children. Current evidence supports the use of acute lymphoblastic leukemia (ALL)-directed regimens as initial therapy for MPAL; Children's Oncology Group (COG) ALL regimens are commonly used for pediatric ALL in the United States. Data for the predictive value of minimal residual disease (MRD) to risk-stratify therapy for pediatric MPAL is sparse overall and currently unknown in the context of COG ALL regimens. The primary objective for this study was to therefore examine the predictive value of MRD for event-free and overall survival (EFS, OS) in a centrally-reviewed, strictly-defined pediatric MPAL cohort treated according to COG ALL regimens. METHODSA retrospective cohort of pediatric MPAL treated from 2008-2016 was assembled from six institutions in the United States. All sites submitted primary diagnostic flow cytometry for central review. Two independent hematopathologists blinded to clinical outcomes confirmed the diagnosis of MPAL according to the WHO2008 and/or WHO2016 classification and assigned a MPAL phenotype. MRD was assessed by multi-parameter flow cytometry (“negative” defined as <0.01%). Endpoints of interest included presenting features of MPAL, MRD levels at end of induction and consolidation (EOI, EOC), role of hematopoietic stem cell transplantation (HSCT) in complete remission (CR), EFS, and OS. Kaplan-Meier analyses were performed stratified by predictors of interest. Stepwise multivariable Cox proportional hazard models inclusive of MRD and candidate predictors were used to evaluate EFS and OS for patients with complete data. Analyses were repeated in the subset of patients with “neutral” cytogenetics (i.e. no favorable [double trisomy, ETV6-RUNX1] or adverse [hypodiploid, BCR-ABL1, KMT2Ar, Ph-like, iAMP21, FLT3-ITD] features). All tests were 2-sided with significance set at p <0.05. RESULTSOf the 112 cases diagnosed by institutions as MPAL, 94 (84%) fulfilled strict WHO criteria. The majority of MPAL patients were B/Myeloid (89%), with a single blast population (87%), and without hyperleukocytosis (WBC≥50K/uL) or central nervous system involvement at presentation (Table 1). Within the cohort, 85/94 were treated with a COG ALL regimen with EOI MRD available (1/85 suffered an induction death prior to MRD assessment). ALL induction therapy resulted in a MRD-negative CR in 72% (61/85); three MRD-negative patients nonetheless converted to non-ALL therapy. Of those EOI MRD+ (≥0.01%), 12 of 14 who continued with COG ALL therapy achieved an EOC MRD-negative CR (i.e. 70/85 [82%] were MRD-negative by EOC). Induction failure (IF) occurred in 7% (6/85) and was defined as disease progression prior to EOI (n=2) or by EOI MRD ≥5% (n=4). The two patients with early disease progression were successfully “salvaged” with AML therapy (<21 days from initial diagnosis) and achieved a MRD-negative CR following one cycle. Patients achieving MRD-negative remissions at EOI and/or EOC with ALL chemotherapy had excellent EFS and OS (Figure 1). Multivariable analysis confirmed the predictive value of MRD at EOI (hazard ratio ±SE for EFS and OS = 3.77±1.67 and 3.54±2.09; p=0.032 and p=0.024 respectively). Only a few patients receiving ALL therapy proceeded to HSCT in CR1, all were alive at time of reporting. Use of HSCT was not associated with improved EFS or OS (p>0.50 for both); five-year EFS and OS for ALL chemotherapy without HSCT (n=73) were 78±6% and 90±4%, respectively. The presence of multiple blast populations of distinct lineages at diagnosis was similarly rare and was potentially associated with worse OS on multivariable analysis (p=0.024). No other candidate predictors were associated with EFS or OS. No difference in the predictive value of MRD was present when analyses were limited to patients with “neutral” cytogenetics. CONCLUSIONIn a retrospective analysis of pediatric MPAL, the majority of patients treated with ALL chemotherapy achieved a MRD-negative CR by EOC (~week 12 of therapy); overall survival in this group was excellent. Further prospective validation of MRD is essential to refine risk-stratified therapy for pediatric MPAL. Optimal salvage for those who fail to achieve remission with ALL chemotherapy is unknown and requires further study. DisclosuresO'Gorman:Becton Dickinson: Consultancy.

Incidence and Risk Factors for Hypertension During Childhood Acute Lymphoblastic Leukemia Therapy

To determine the incidence of hypertension among children during the induction and re-induction phases of acute lymphoblastic leukemia (ALL) therapy and association with possible risk factors. A retrospective analysis of 208 consecutive pediatric (age <18 y) ALL patients, treated per BFM-95 protocol between January 2009 and December 2013. Data were analyzed to determine the incidence of hypertension and risk factors for its development. Incidence of hypertension requiring antihypertensive medication, was 29% (61/208) during induction and 17% (33/198) during re-induction (P=0.003). Median (range) age of patients developing hypertension was 4 y (4 mo to 8 y). Age <10 y and presence of constipation were independently predictive of hypertension by multivariate analysis. The present study reports a high incidence of hypertension among children undergoing ALL induction therapy.

BSH Guideline: management of thrombotic and haemostatic issues in paediatric malignancy.

BSH Guideline: management of thrombotic and haemostatic issues in paediatric malignancy.

Efficacy of ALL Therapy for WHO2016-Defined Mixed Phenotype Acute Leukemia: A Report from the Children's Oncology Group

There remains uncertainty regarding the optimal treatment for mixed phenotype acute leukemia (MPAL), an uncommon leukemia that represents ~3% of de novo acuteleukemia. Because of the dearth of clinical trials, varying approaches are employed: acute lymphoblastic leukemia (ALL) regimens as well as more intensive acute myeloid leukemia (AML) and hybrid therapies. The evolution in the prevailing diagnostic criteria from the EGIL classification to the more narrowly defined WHO2008 and WHO2016 criteria has made the existing literature difficult to interpret. Increasing insight into the molecular heterogeneity of MPAL adds further complexity. Recently published studies (retrospective clinical case series), however, are beginning to suggest that ALL therapy may be the most appropriate form of initial therapy for MPAL.To further assess the efficacy of ALL therapy for pediatric MPAL, we reviewed the Children's Oncology Group (COG) experience. Possible MPAL cases were identified through the ALL biology studies (both AALL03B1 and AALL08B1 were open to MPAL) and from AAML0531, the phase 3 trial for de novo AML (patients enrolled on this trial subsequently found to have MPAL were taken off study). All identified cases were reviewed centrally. In cases where the original flow cytometry testing was inadequate to establish the diagnosis, flow cytometry was repeated with an expanded antibody panel using banked diagnostic specimens. Only cases meeting WHO2016 criteria were retained. Patients were treated per physician discretion and not on a therapeutic clinical trial. Supplemental data on treatment and outcomes were collected.From the study databases, 97 potential MPAL cases were identified; of these, 54 cases (56%) were confirmed to be MPAL via central review. Patients were diagnosed between 2003 and 2016. The majority of patients were <10 years of age and B/Myeloid MPAL (B/My) was the most common phenotype. Fewer than a third of patients presented with hyperleukocytosis, adverse recurrent cytogenetics, or central nervous system involvement (Table 1). In the cohort, 38 patients (70%) received ALL induction therapy, 12 (22%) AML induction, and 3 hybrid induction; 14 (28%) patients received hematopoietic stem cell transplantation (HSCT). The CR rate was 71.1% [27/38], 66.7% (8/12) and 100% (3/3) in patients receiving ALL, AML and hybrid induction, respectively (p=0.761). CR was achieved in 78.8% of B/My cases [26/33], 68.4% T/My cases [13/19], and no B/T cases (0/2, p=0.074). Treatment became more heterogeneous further into therapy due to varying incorporation of ALL, AML and hybrid elements and the varying use of HSCT. Three-year EFS was 65±17% in patients started on ALL therapy and 53±26% in patients started on AML therapy (p=0.169, Fig. 1A); 3-year OS was 79±15% and 60±27% respectively (p=0.510, Fig. 1B). SCT was not associated with a difference in EFS (p=0.935) or OS (p=0.726). In 20 patients receiving ALL therapy alone without SCT, 3-year EFS was 59±22% and OS 79±18%.This series represents a large cohort of centrally-reviewed pediatric MPAL cases diagnosed according to the most recent WHO2016 criteria and treated with COG-style chemotherapy. Our results add to the growing body of literature suggesting that ALL regimens may be effective for pediatric MPAL. It also suggests, however, that induction failure and relapse are still relatively common with ALL therapy and that alternative forms of treatment are necessary for some. The limited size of the sample and its heterogeneity preclude any conclusions regarding the relative efficacy of AML therapy and role for HSCT. Given the greater morbidity and mortality associated with these forms of therapy, consideration should be given to reserving their use for patients with a suboptimal response to ALL therapy. Continued variability in accurately diagnosing and treating MPAL as seen here also underscores the necessity of well-delineated clinical trials with integrated central review to advance MPAL therapy. Our results therefore further support the basis for the first-ever prospective evaluation of high risk ALL therapy for pediatric MPAL in a trial now being planned within the COG. In this trial, minimal residual disease testing with multiparameter flow cytometry will be employed to identify patients responding well to ALL therapy versus those who may benefit from more intensive AML therapy and transplantation. [Display omitted] DisclosuresMullighan:Loxo Oncology: Research Funding; Amgen: Consultancy. Hunger:Erytech Pharmaceuticals: Consultancy; Novartis: Consultancy; Jazz Pharmaceuticals: Honoraria; Amgen: Consultancy, Equity Ownership. Berman:AGADA Therapeutics: Research Funding. Zweidler-McKay:ImmunoGen: Employment.

Vincristine toxicity with co-administration of fluconazole during induction therapy for pediatric acute lymphoblastic leukemia.

Antifungal prophylaxis is recommended for patients with acute lymphoblastic leukemia (ALL) during high-risk periods such as induction; however, increased vincristine toxicities have been reported with the co-administration of triazole antifungals. We sought to determine whether vincristine-associated toxicities are higher among children with ALL concurrently given fluconazole prophylaxis compared to no prophylaxis. Using a retrospective cohort design, we reviewed records of pediatric patients treated for newly diagnosed ALL from 2003 to 2013. Patients were classified by fluconazole exposure during induction. The development of vincristine-associated toxicity and vincristine dose adjustment were the primary outcomes evaluated. The adjusted risk difference (RD) for vincristine-related toxicity associated with triazole exposure was determined. We identified 197 patients meeting inclusion criteria for evaluation, 160 (81%) of whom received fluconazole prophylaxis. Among patients receiving fluconazole, 36/160 (22%) developed vincristine toxicity compared to 7/37 (19%) among those not receiving prophylaxis (RD: 3%, 95% confidence interval [CI] -11 to 18%). Adjusting for patient age and race, no statistically significant increased risk for vincristine-associated toxicity with fluconazole exposure was observed (RD 5%, 95% CI -8 to 17%). An increased risk for vincristine-associated toxicity was independently associated with age 10 years or older (RD 19%, 95% CI 4-34%). Co-administration of fluconazole during induction therapy for pediatric ALL does not significantly increase the risk for vincristine-associated toxicities; however, patients 10 years or older are at an increased risk for toxicity independent of fluconazole exposure. Prophylaxis with fluconazole during induction therapy for pediatric ALL, if warranted, appears to be a safe clinical practice.

Posterior Reversible Encephalopathy Syndrome after Paralytic Ileus during B-Cell Precursor Acute Lymphoblastic Leukemia Induction Therapy

Posterior Reversible Encephalopathy Syndrome after Paralytic Ileus during B-Cell Precursor Acute Lymphoblastic Leukemia Induction Therapy

Implementation of a simplified flow cytometric assays for minimal residual disease monitoring in childhood acute lymphoblastic leukemia.

Monitoring minimal residual disease (MRD) in B-lineage acute lymphoblastic leukemia (ALL) to assess treatment response is crucial for risk assignment. Flow cytometry can be used to monitor MRD in ALL but the implementation of this approach requires extensive expertise. If resources are limited, the costs of full flow cytometric MRD testing might be prohibitive. We evaluated the applicability of a previously reported simplified MRD assay, designed to distinguish leukemic from normal lymphoblastic during remission induction therapy. Fifty-nine samples from children with ALL, enrolled in the RE-LLA study at a pediatric oncology center in Recife (Brazil), were evaluated for MRD on day 19 and on day 26 of remission induction therapy. We compared results obtained by a trainee in Recife and an expert. The method was implemented successfully and the concordance between results obtained by the trainee and the expert was practically absolute at the end of the study. It is possible to implement reliable measurements of MRD during remission induction therapy in childhood ALL despite limited resources. The simplicity of the MRD method used in this study does not require extensive prior training in leukemia immunophenotyping. © 2016 International Clinical Cytometry Society.

Effectiveness of Dexamethasone compared with Prednisolone in Induction Therapy of Childhood Acute Lymphoblastic Leukemia

Background: Corticosteroids are an essential component of treatment for acute lymphoblastic leukemia (ALL). Prednisolone is the most commonly used steroid. There is increasing evidence that, even in equipotent dosage for glucocorticoid effect, dexamethasone has enhanced lymphoblast cytotoxicity and penetration of central nervous system compared with prednisolone.Objectives: To determine the effect of dexamethasone and prednisolone and to compare them in induction therapy of ALL in Children.Material &amp; Methods: A total of 60 newly diagnosed cases of ALL confirmed by bone marrow study, children of either sex with age &gt;1 year were included in this study. Variables studied were age, sex, presenting features, neutrophil count, blast cell count, platelet count, bone marrow status at diagnosis, on D15 &amp; D29 of induction and side effects.Results: Mean age of the patients of group A was 6.28 years &amp; that of group B was 7.2 years. Out of all patients of group A 19 (63.3%) were male and 11 (36.7%) were female. In group B 21 (70.0%) patients were male and rests 9 (30.3%) were female. No statistically significant difference was observed in both groups in terms of age, sex &amp; presenting features. After induction significant difference was observed in liver &amp; spleen size at day 7 and day 15. All patients of both groups had M3 marrow status at diagnosis. Overall, in group A 93.3% patients achieved M1 marrow status (fewer than 5% blasts) and 6.7% had M2 marrow status (5-25% blasts) at day 15 of induction. On the other side 66.7% patients of group B achieved M1 status and 33.3% M2 status at day 15. Statistically significant difference was observed between groups on day 15 in term of achieved marrow status (p&lt;0.05). No statistically significant difference was observed between groups in term of infection in difference days of induction. On day 16 of induction maximum incidence of infection was observed in both groups.Conclusion: Dexamethasone may be an effective alternative option to prednisolone for the treatment of acute lymphoblastic leukemia in children.J. Paediatr. Surg. Bangladesh 6(1): 3-9, 2015 (Jan)

Urinary retention in acute lymphoblastic leukemia induction therapy: Two distinct pathologies

Intrathecal chemotherapy and systemic chemotherapy are used for both prophylaxis and treatment of central nervous system disease in hematologic malignancies. We presented two children with urinary retention due to neurotoxicity with two distinct drugs and reasons. The main presenting complaints were urinary retention and incontinence in both patients. Before the adverse clinical event, the patients had received vincristine intravenously and triple therapy with hydrocortisone, cytosine arabinoside, and methotrexate intrathecally. The clinical event resolved, and vincristine and intrathecal chemotherapy were deleted from the patients subsequent therapy until recovery was achieved.

Bacillus Cereus Bacteremia and Multiple Brain Abscesses During Acute Lymphoblastic Leukemia Induction Therapy

Bacillus cereus can cause serious infections in immunosuppressed patients. This population may be susceptible to B. cereus pneumonia, bacteremia, cellulitis, and rarely cerebral abscess. Here we report an 8-year-old boy undergoing induction therapy for acute lymphoblastic leukemia who developed multifocal B. cereus cerebral abscesses, highlighting the propensity for B. cereus to develop cerebral abscesses. A review of the literature over the past 25 years identified another 11 cases (3 children and 8 adults) of B. cereus cerebral abscess in patients undergoing cancer therapy. B. cereus cerebral abscesses were associated with a high mortality rate (42%) and significant morbidity. Notably, B. cereus bacteremia with concomitant cerebral abscess was associated with induction chemotherapy for acute leukemia in both children and adults (10 of 12 case reports). Our case report and review of the literature highlights the propensity for B. cereus to develop cerebral abscess(es). Therefore, early consideration for neuroimaging should be given for any neutropenic cancer patient identified with B. cereus bacteremia, in particular those with acute leukemia during induction therapy.

Smac Mimetic-Mediated Sensitization Of Childhood ALL Cells For Drug-Induced Apoptosis Independent Of TNFα and NFκB Signaling Pathways

Targeting inhibitor of apoptosis proteins (IAPs) using small molecular Smac mimetics (SM) has been shown to offer a novel promising treatment strategy for resistant malignant diseases including childhood acute lymphoblastic leukemia (ALL). The effect of SM alone has been shown to be associated with endogenous TNFα expression, therefore tumor cells can be classified into sensitive or resistant against apoptosis induction by SM alone. In SM sensitive tumor cells the effect of SM has been shown to be mediated mainly by degradation of cellular IAP (cIAP) and activation of TNFα and NFκB signaling pathways but not inhibition of XIAP.We show here, that sensitivity of ALL cells to SM alone (as well as TNFα expression) is highly variable. Nevertheless even in ALL cells resistant against SM alone, treatment with SM resulted in significant sensitization for drugs used within standard induction therapy for childhood ALL. Sensitization for drug-induced apoptosis by SM was not only mediated by activation of the intrinsic (cleavage of caspase 9) but also extrinsic apoptosis pathway (cleavage of caspase 8). Surprisingly, SM-induced cIAP degradation alone was not sufficient for caspase 8 activation and apoptosis induction. Consistently, SM-mediated sensitization for drug-induced apoptosis was independent of TNFα and NFκB signaling pathways. We demonstrate that caspase 8 activation by combined treatment with SM and cytostatic drugs is blocked by inhibition of caspase 3 and caspase 9 and therefore occurs downstream of intrinsic apoptosis pathway activation.In conclusion, our data argue for a model comprising inhibition of XIAP-mediated blockade of caspase 3/9 as the central effect of SM in chemo-sensitization of childhood ALL cells resistant against SM-alone. Disclosures:No relevant conflicts of interest to declare.

Successful coil embolization for life‐threatening hemorrhage in childhood leukemia induction therapy

An 11-year-old boy was experienced severe life-threatening hemorrhage from a branch of the superior mesenteric artery (SMA) after acute lymphoblastic leukemia induction therapy. The patient had a history of attention deficit hyperactivity disorder (ADHD), diagnosed at 3 years of age. Subsequent to discontinuing his psychotropic medication, the patient's mental status deteriorated and treatment with midazolam for 3 weeks was necessary to allow the completion of the leukemia induction regimen. On day 51, although there was no indication of thrombocytopenia or a coagulation disorder, the patient began to hemorrhage suddenly from anal with resulting hypovolemic shock, and large-volume blood transfusion was initiated. Although upper and lower endoscopy failed to determine the location of the hemorrhage, angiography enabled us to determine that it was a branch of the SMA (the middle colic artery #6), and selective arterial embolization was used to arrest the bleeding. There could have been underlying causes, such as, a probable malformation or aneurysm in that area, although there was no indication before or after the event. This is a rare case of arterial hemorrhage from a branch of the SMA that occurred in a pediatric patient idiopathically during the induction therapy of leukemia.

Cerebral aspergillus infection in pediatric acute lymphoblastic leukemia induction therapy

Angioinvasive pulmonary infection from filamentous fungi is not an uncommon occurrence in immunocompromised patients like acute lymphoblastic leukemia (ALL). Rarely, these lesions can spread via the hematogenous route and involve multiple visceral organs. We report a case of a 14-year-old boy with ALL who developed angioinvasive pulmonary aspergillosis early in the course of induction therapy, which was followed by hematogenous dissemination and formation of multiple brain abscesses. The patient was treated with intravenous amphotericin B. There was no response to the therapy and the patient succumbed to disseminated infection. Postmortem lung biopsy confirmed angioinvasive pulmonary aspergillosis. Poor penetration of amphotericin B across the blood-brain barrier could be one of the contributory factors for poor response to antifungal therapy. We discuss the various antifungal agents with respect to their penetration in brain.

Hyperactivated mTOR Signaling Is a Characteristic Feature of High Risk Acute Lymphoblastic Leukemia and Can Be Effectively Targeted in a Preclinical NOD/SCID/huALL Xenograft Mouse Model

Abstract 2572Treatment of acute lymphoblastic leukemia (ALL), the most frequent malignant disease in children and adolescents, is increasingly successful. Stratification based on prognostic factors assigning the patients to treatment protocols of different intensity and intensification of chemotherapy regimens have improved patient outcome with present cure rates above 80%. However, about 20% of the patients suffer from relapse which is associated with inferior outcome, especially if occurring early. Importantly, despite the efforts achieved by stratification strategies including detection of minimal residual disease, the majority of relapse patients are initially stratified into non-high risk groups and not identified upfront by current markers. This clearly emphasizes the need for additional prognostic markers which should ideally reflect features of leukemia biology pointing to novel therapeutic targets.In a recent study we described a strong association of the engraftment phenotype observed in a series of transplanted primary patient B cell precursor (BCP) ALL samples in a NOD/SCID/huALL mouse model and early patient relapse. This rapid engraftment phenotype (time to leukemia, TTLshort) is characterized by a gene expression profile pointing to pathways involved in cell growth and proliferation.Since mammalian target of rapamycin (mTOR) is a key survival pathway and was identified in the gene profile we now investigated this pathway on a functional level. For this purpose, ALL xenograft samples previously characterized with respect to their engraftment phenotype (TTLshort/early relapse, n=3 or TTLlong/no or late relapse, n=4) were re-transplanted onto NOD/SCID mice. At disease onset ALL cells were harvested from leukemia bearing recipients and mTOR pathway activation was analyzed by flow cytometry assessing phosphorylation of ribosomal protein S6 (P-S6), a molecule downstream of mTOR. Increased P-S6 levels were detected in TTLshort compared to TTLlong xenografts (T-test, P=.009) indicating constitutive mTOR hyperactivation in TTLshort/early relapse leukemia. Furthermore, the effects of the mTOR inhibitor rapamycine and the PI3K/mTOR dual inhibitor BEZ235 were investigated. Xenograft leukemia cells were incubated with rapamycine, BEZ235 or solvent and P-S6 was analyzed. Interestingly, both inhibitors led to a significant decrease of pathway activation in TTLshort but not in TTLlong xenografts indicating that the hyperactivated mTOR pathway of this high risk ALL subtype can be successfully targeted.Moreover, the effect of mTOR inhibition on individual patient derived ALL was also analyzed in vivo. Since in a clinical setting high risk disease is unlikely to be treated employing a novel strategy on its own, we investigated the effect of mTOR inhibition in addition to multiagent drug treatment resembling ALL induction therapy. NOD/SCID mice were transplanted with TTLshort (n=2) or TTLlong (n=1) leukemia. Upon appearance of leukemia in the peripheral blood treatment with either rapamycine, multiagent chemotherapy, combination of chemotherapy and rapamycin or solvent was initiated (8 mice per group) and the time until reoccurrence of leukemia defined by presence of 25% or more human ALL cells in the recipients blood was assessed. In both TTLshort leukemias a significant delay of ALL onset was observed upon combination treatment compared to chemotherapy alone, however the TTLlong leukemia showed onset at similar time points irrespective of treatment modalities. Importantly, also a significant reduction in leukemia load (as measured by decreased spleen weights despite similar high percentage leukemia infiltration) was observed in TTLshort but not TTLlong leukemias upon in vivo combination therapy.Taken together, we demonstrated that TTLshort/early relapse leukemia is associated with an hyperactivated mTOR pathway and can effectively be targeted by mTOR inhibitors ex vivo. Most importantly, a significant delay of leukemia onset upon in vivo mTOR inhibition combined with conventional chemotherapy was achieved in a preclinical NOD/SCID/huALL xenograft model. Thus, mTOR inhibition is a successful novel therapeutic strategy for the treatment of high risk ALL. Disclosures:No relevant conflicts of interest to declare.

Lack of Prognostic Significance of Absolute Lymphocyte Count After Intensive Induction Therapy in Childhood Acute Lymphoblastic Leukemia

Abstract 4909 Introduction:Previous work has shown that the function and number of lymphocytes are vital for the patient's immune system to mount an effective response against cancer cells. Multiple recent studies have demonstrated the prognostic value of absolute lymphocyte count (ALC) in a wide range of malignancies. In children with acute lymphoblastic leukemia (ALL), ALC during induction chemotherapy have been shown to be an independent predictor of adverse outcome, even in the era of minimal residual disease (MRD). Most of the previous studies used Children Oncology Group (COG) based regimens with 3 or 4 drugs induction. We hypothesized that with more intensive induction regimens with 5 or 7 drugs, ALC would lose its prognostic value due to more intensive chemotherapy induced leukopenia. Patients/methods:We reviewed 136 Jordanian pediatric patients (Arabic ethnicity) with newly diagnosed ALL, age 1–18 years, from 2007 to 2009. The patients were treated at a single institution on modified St. Jude total XIII and VX protocols, with a median follow up of 35 months (range: 2–54 months). The induction phase was composed of 7 drugs regimen. Variables analyzed included ALC at diagnosis, day15, day 36 end of induction chemotherapy and at time of post induction marrow recovery, white blood cells at diagnosis, age at diagnosis, gender, immunophenotype, cytogenetics, risk group and MRD status at end of induction. ALC at each time-point was evaluated for prognostic ability by univariate and multivariate analysis. Results:We found that ALC at day15, day 36 end of induction chemotherapy and at time of post induction marrow recovery failed to have any prognostic effect on event-free survival (EFS) or overall survival (OS). We analyzed ALC as continuous and dichomatous variable, but without any prognostic significance. In contrast to our hypothesis, children with ALL intensive induction regimen did not have profound lymphopenia, with ALC day15 median of 1260 cells/ml (range: 0–9450), ALC day36 median of 866 (range: 100–3476), and ALC (post induction marrow recovery) median of 1145 cells/ml (range: 85–9676). Our cohort confirmed several known prognostic factors in childhhod ALL. For EFS outcome we found MRD35, age, phenotype and risk group to have a significant prognostic effect with P values of (0.016, 0.005, 0.006, 0.001) respectively. For OS outcome we found both age and phenotype to have a significant prognostic P value of (0.006 and <0.001) respectively. Conclusions:In this study we failed to replicate the previous work that showed the independent prognostic value of ALC during induction therapy in childhood ALL. In contrast to our hypothesis, the reason for the lack of significance was not due to more profound lymphopenia. The lack of ALC prognostic significance in our cohort could be protocol related or patient population (ethnicity) related. Further studies are needed in children with ALL with different ethnic backgrounds to validate the previous work regarding ALC significance before its incorporation in ALL prognostic models, especially in middle or low income countries. Disclosures:No relevant conflicts of interest to declare.

Symptomatic severe hypertriglyceridaemia with asparaginase therapy in acute lymphoblastic leukaemia (ALL) and lymphoblastic lymphoma: is rechallenging safe?

Severe hyperlipidaemia with asparaginase therapy is rare. We report six cases, four of which developed significant problems with severe hyperlipidaemia during induction therapy for ALL and lymphoblastic lymphoma. The median triglyceride level was 22.3 mmol/L and the median cholesterol level was 12.3 mmol/L. None of the patients showed signs or symptoms of pancreatitis. Three children were re-exposed with Peg asparaginase, and one with Erwinia asparaginase, without recurrence of hyperlipidaemia or other symptoms. These cases highlight the dilemma in managing such rare cases of symptomatic hypertriglyceridaemia secondary to asparaginase and steroid therapy.

Dexamethasone versus prednisone for induction therapy in childhood acute lymphoblastic leukemia: a systematic review and meta-analysis

This systematic review and meta-analysis compared the efficacy and toxicity of dexamethasone (DEX) versus prednisone (PRED) for induction therapy in childhood acute lymphoblastic leukemia (ALL). We searched biomedical literature databases and conference proceedings for randomized controlled trials comparing DEX and PRED during induction therapy for childhood ALL. A total of eight studies were eligible for inclusion in this meta-analysis. DEX, in comparison with PRED, reduced events (that is, death from any cause, refractory or relapsed leukemia, or second malignancy; risk ratio (RR) 0.80; 95% confidence interval (CI), 0.68-0.94) and central nervous system relapse (RR 0.53; 95% CI, 0.44-0.65), but did not alter bone marrow relapse (RR 0.90; 95% CI, 0.69-1.18) or overall mortality (RR 0.91; 95% CI, 0.76-1.09). Patients receiving DEX had a higher risk of mortality during induction (RR 2.31; 95% CI, 1.46-3.66), neuro-psychiatric adverse events (RR 4.55; 95% CI, 2.45-8.46) and myopathy (RR 7.05; 95% CI, 3.00-16.58). There was no statistically significant difference in the risk of osteonecrosis, sepsis, fungal infection, diabetes or pancreatitis. DEX in induction therapy for children with ALL is more efficacious than PRED. However, DEX is also associated with more toxicity, and currently it remains unclear whether short-term superiority of DEX will also result in better overall survival.

A high circulating copy number of HHV-6 due to chromosomal integration in a child with acute lymphoblastic leukemia

We report a case of a 3.5-year-old female with a very high copy number of human herpesvirus 6 (HHV-6) detected by PCR in blood during acute lymphoblastic leukemia induction therapy. The patient was unsuccessfully treated with antiviral drugs. HHV-6 genome was shown to be constitutively integrated into chromosome 22q-tel, likely to be inherited from the mother who was found to carry high HHV-6 copy number. This case highlights the importance of excluding HHV-6 chromosomal integration before diagnosing HHV-6 infection or reactivation in immunocompromised patients.

Quantification of free total plasma DNA and minimal residual disease detection in the plasma of children with acute lymphoblastic leukemia

The analysis of total plasma DNA and the monitoring of leukemic clone-specific immunoglobulin and/or T-cell receptor gene rearrangements for the evaluation of minimal residual disease (MRD) in the plasma may be useful tools for prognostic purposes or for early detection of subclinical disease recurrence in children with acute lymphoblastic leukemia (ALL). The aim of this paper is to establish reference ranges for total plasma DNA concentrations and to test the feasibility of MRD measurements employing plasma DNA from children with ALL by using real-time quantitative (RQ)-PCR. Despite wide inter-individual variation, the median concentrations of total plasma DNA for 12 healthy donors (57 ng/ml), 21 children with ALL after day 4 of treatment initiation (62 ng/ml) and 13 children with other malignancies (76 ng/ml) were similar. However, ALL patients had significantly higher concentrations at diagnosis (277 ng/ml) and on treatment day 3 (248 ng/ml) before returning to normal afterwards. Early plasma DNA MRD kinetics could be established for 15 ALL patients and showed good concordance with bone marrow MRD. Plasma DNA was higher in children with ALL at diagnosis but returned to normal within the first four treatment days. Despite low concentrations of DNA, it is feasible to measure MRD kinetics in plasma DNA during ALL induction therapy by adapted real-time PCR methodologies.