Donor-type bone marrow aplasia following hematopoietic stem cell transplantation in a child with a novel SAMD9L variant

Pathogenic variants in the genes SAMD9 (sterile a-motif domain containing protein - 9) and SAMD9L (SAMD9-like) cause bone marrow failure with characteristic syndromic features. We report a case of a previously healthy, 3-year-old boy with no dysmorphology, who presented with severe aplastic anemia and a novel variant in the SAMD9L gene. His father, elder brother and sister who harbored the same variant were completely healthy. In the absence of a matched unrelated donor, he underwent a stem cell transplant from his sister, a 10/10 match. Almost 2 years later he developed donor type aplasia and succumbed to an invasive fungal infection after a failed haplograft from his mother. This case highlights the pathogenicity of this previously undescribed germline variation of uncertain significance in the SAMD9L gene and the value of comprehensive genetic testing for inherited bone marrow failures even in the absence of a positive family history or characteristic congenital abnormalities.

Intention-to-treat outcomes utilising a stringent event definition in children and young people treated with tisagenlecleucel for r/r ALL through a national access scheme

CAR T-cell therapy has transformed relapsed/refractory (r/r) B-cell precursor acute lymphoblastic leukaemia (B-ALL) management and outcomes, but following CAR T infusion, interventions are often needed. In a UK multicentre study, we retrospectively evaluated tisagenlecleucel outcomes in all eligible patients, analysing overall survival (OS) and event-free survival (EFS) with standard and stringent definitions, the latter including measurable residual disease (MRD) emergence and further anti-leukaemic therapy. Both intention-to-treat and infused cohorts were considered. We collected data on feasibility of delivery, manufacture, toxicity, cause of therapy failure and followed patients until death from any cause. Of 142 eligible patients, 125 received tisagenlecleucel, 115/125 (92%) achieved complete remission (CR/CRi). Severe cytokine release syndrome and neurotoxicity occurred in 16/123 (13%) and 10/123 (8.1%), procedural mortality was 3/126 (2.4%). The 2-year intent to treat OS and EFS were 65.2% (95%CI 57.2-74.2%) and 46.5% (95%CI 37.6-57.6%), 2-year intent to treat stringent EFS was 35.6% (95%CI 28.1-44.9%). Median OS was not reached. Sixty-two responding patients experienced CAR T failure by the stringent event definition. Post failure, 1-year OS and standard EFS were 61.2% (95%CI 49.3-75.8) and 55.3% (95%CI 43.6-70.2). Investigation of CAR T-cell therapy for B-ALL delivered on a country-wide basis, including following patients beyond therapy failure, provides clinicians with robust outcome measures. Previously, outcomes post CAR T-cell therapy failure were under-reported. Our data show that patients can be successfully salvaged in this context with good short-term survival.

Blinatumomab for First-Line Treatment of Children and Young Persons With B-ALL

PURPOSE

We tested whether blinatumomab (Blina) is effective as a toxicity-sparing alternative to first-line intensive chemotherapy in children and young persons (CYP) with B-ALL who were chemotherapy-intolerant or chemotherapy-resistant.

METHODS

Data were collected for consecutive CYP (age 1-24 years) with Philadelphia chromosome-positive or Philadelphia chromosome-negative B-ALL who received Blina as first-line therapy. Blina was given as replacement for postremission intensive chemotherapy to patients with chemotherapy intolerance or resistance. Blina responders received further chemotherapy (Blin-CT) or first remission hematopoietic stem-cell transplant (Blin-HSCT) if indicated. Event-free survival (EFS) and overall survival (OS) of the Blin-CT group were compared with those of matched controls treated with standard chemotherapy in the UKALL 2003 trial. Events were defined as death, relapse, or secondary cancer.

RESULTS

From February 2018 to February 2023, 105 patients were treated, of whom 85 were in the Blin-CT group and 20 were in the Blin-HSCT group. A majority of Blin-CT patients received Blina for chemotherapy intolerance (70 of 85, 82%), and the group had a higher-risk profile than unselected patients with B-ALL. Blina was well tolerated with only one patient having a grade 3/4-related toxicity event, and of the 60 patients who were minimal residual disease-positive pre-Blina, 58 of 60 (97%) responded. At a median follow-up of 22 months, the 2-year outcomes of the 80 matched Blin-CT group patients were similar to those of 192 controls (EFS, 95% [95% CI, 85 to 98] v 90% [95% CI, 65 to 93] and OS, 97% [95% CI, 86 to 99] v 94% [95% CI, 89 to 96]). Of the 20 in the HSCT group, three died because of transplant complications and two relapsed.

CONCLUSION

Blina is safe and effective in first-line treatment of chemotherapy-intolerant CYP with ALL.

Can I go home now? The safety and efficacy of a new UK paediatric febrile neutropenia protocol for risk-stratified early discharge on oral antibiotics

OBJECTIVE

To evaluate a new protocol of risk stratification and early discharge for children with febrile neutropenia (FN).

DESIGN

Prospective service evaluation from 17 April 2020 to 16 April 2021.

SETTING

13 specialist centres in the UK.

PATIENTS

405 children presenting with FN.

INTERVENTION

All children received intravenous antibiotics at presentation. Risk stratification was determined using the Australian-UK-Swiss (AUS) rule and eligibility for homecare assessed using criteria including disease, chemotherapy, presenting features and social factors. Those eligible for homecare could be discharged on oral antibiotics after a period of observation proportional to their risk group.

MAIN OUTCOME MEASURES

Median duration of admission and of intravenous antibiotics, and percentage of patients with positive blood cultures, significant infection, readmission within 7 days of initial presentation, intensive care unit (ICU) admission, death from infection and death from other causes.

RESULTS

13 centres contributed 729 initial presentations of 405 patients. AUS rule scores were positively correlated with positive blood cultures, significant infection, ICU admission and death. 20% of children were eligible for homecare with oral antibiotics, of which 55% were low risk (AUS 0-1). 46% low-risk homecare eligible patients were discharged by 24 hours vs 2% homecare ineligible. Homecare readmission rates were 14% overall and 16% for low-risk cases (similar to a meta-analysis of previous studies). No child eligible for homecare was admitted to ICU or died.

CONCLUSIONS

Use of the AUS rule and homecare criteria allow for safe early outpatient management of children with FN.

A multifarious exploration of synaptic tagging and capture hypothesis in synaptic plasticity: Development of an integrated mathematical model and computational experiments

The synaptic tagging and capture (STC) hypothesis not only explain the integration and association of synaptic activities, but also the formation of learning and memory. The synaptic pathways involved in the synaptic tagging and capture phenomenon are called STC pathways. The STC hypothesis provides a potential explanation of the neuronal and synaptic processes underlying the synaptic consolidation of memories. Several mechanisms and molecules have been proposed to explain the process of memory allocation and synaptic tags, respectively. However, a clear link between the STC hypothesis and memory allocation is still missing because the encoding of memories in neural circuits is mainly associated with strongly recurrently connected groups of neurons. To explore the mechanisms of potential synaptic tagging candidates and their involvement in the process of memory allocation, we develop a mathematical model for a single dendritic spine based on five essential criteria of a synaptic tag. By developing a mathematical model, we attempt to understand the roles of the potentially critical molecular networks underlying the STC and the essential attributes of a synaptic tag. We include essential memory molecules in the STC model that have been identified in earlier studies as crucial for STC pathways. CaMKII activation is critical for the setting of the initial tag; however, coordinated activities with other kinases and the biochemical pathways are necessary for the tag to be stable. PKA modulates NMDAR-mediated Ca²⁺ signalling. Similarly, PKA and ERK crosstalk is essential for Ca²⁺ - mediated protein synthesis during l-LTP. Our theoretical model explains the quantitative contribution of Tags and protein synthesis during l-LTP in synaptic strength.

Time to Cure for Childhood and Young Adult Acute Lymphoblastic Leukemia Is Independent of Early Risk Factors: Long-Term Follow-Up of the UKALL2003 Trial

PURPOSE

The aim of the randomized trial, UKALL2003, was to adjust treatment intensity on the basis of minimal residual disease (MRD) stratification for children and young adults with acute lymphoblastic leukemia. We analyzed the 10-year randomized outcomes and the time for patients to be considered cured (ClinicalTrials.gov identifier: NCT00222612).

METHODS

A total of 3,113 patients were analyzed including 1,054 patients who underwent random assignment (521 MRD low-risk and 533 MRD high-risk patients). Time to cure was defined as the point at which the chance of relapse was < 1%. The median follow-up time was 10.98 (interquartile range, 9.19-13.02) years, and survival rates are quoted at 10 years.

RESULTS

In the low-risk group, the event-free survival was 91.7% (95% CI, 87.4 to 94.6) with one course of delayed intensification versus 93.7% (95% CI, 89.9 to 96.1) with two delayed intensifications (adjusted hazard ratio, 0.73; 95% CI, 0.38 to 1.40; P = .3). In the high-risk group, the event-free survival was 82.1% (95% CI, 76.9 to 86.2) with standard therapy versus 87.1% (95% CI, 82.4 to 90.6) with augmented therapy (adjusted hazard ratio, 0.68; 95% CI, 0.44 to 1.06; P = .09). Cytogenetic high-risk patients treated on augmented therapy had a lower relapse risk (22.1%; 95% CI, 15.1 to 31.6) versus standard therapy (52.4%; 95% CI, 28.9 to 80.1; P = .016). The initial risk of relapse differed significantly by sex, age, MRD, and genetics, but the risk of relapse for all subgroups quickly coalesced at around 6 years after diagnosis.

CONCLUSION

Long-term outcomes of the UKALL2003 trial confirm that low-risk patients can safely de-escalate therapy, while intensified therapy benefits patients with high-risk cytogenetics. Regardless of prognosis, the time to cure is similar across risk groups. This will facilitate communication to patients and families who pose the question "When am I/is my child cured?"

Can Machine Learning Models Predict Asparaginase-associated Pancreatitis in Childhood Acute Lymphoblastic Leukemia

Asparaginase-associated pancreatitis (AAP) frequently affects children treated for acute lymphoblastic leukemia (ALL) causing severe acute and persisting complications. Known risk factors such as asparaginase dosing, older age and single nucleotide polymorphisms (SNPs) have insufficient odds ratios to allow personalized asparaginase therapy. In this study, we explored machine learning strategies for prediction of individual AAP risk. We integrated information on age, sex, and SNPs based on Illumina Omni2.5exome-8 arrays of patients with childhood ALL (N=1564, 244 with AAP 1.0 to 17.9 yo) from 10 international ALL consortia into machine learning models including regression, random forest, AdaBoost and artificial neural networks. A model with only age and sex had area under the receiver operating characteristic curve (ROC-AUC) of 0.62. Inclusion of 6 pancreatitis candidate gene SNPs or 4 validated pancreatitis SNPs boosted ROC-AUC somewhat (0.67) while 30 SNPs, identified through our AAP genome-wide association study cohort, boosted performance (0.80). Most predictive features included rs10273639 (PRSS1-PRSS2), rs10436957 (CTRC), rs13228878 (PRSS1/PRSS2), rs1505495 (GALNTL6), rs4655107 (EPHB2) and age (1 to 7 y). Second AAP following asparaginase re-exposure was predicted with ROC-AUC: 0.65. The machine learning models assist individual-level risk assessment of AAP for future prevention trials, and may legitimize asparaginase re-exposure when AAP risk is predicted to be low.

Clinical Utility of Radiologic Disease Reassessment in the Management of Pediatric B-Cell Non-Hodgkin Lymphoma

Although outcomes for children with B-cell non-Hodgkin lymphoma are excellent, between 20% and 40% demonstrate residual radiologic abnormalities at disease assessment during consolidation therapy, the significance of which remains uncertain. The authors report the outcomes for all children treated for B-cell non-Hodgkin lymphoma at our center over an 11-year period. Twenty-four of 64 (38%) children had residual radiologic abnormalities at disease remission assessment. Seven (29%) underwent histologic biopsies that were normal. No children with residual radiologic abnormalities experienced disease relapse or death, suggesting that imaging at this time point creates clinical uncertainty without indicating residual disease or predicting relapse.

Congenital acute myeloid leukemia: challenges and lessons. A 15-year experience from the UK

Congenital Acute Myeloid leukemia (CAML) is a rare leukemia diagnosed within the first 28 days of life. Dismal survival rates of approximately 25% at two years from diagnosis have not improved despite multiple treatment protocols, and there lacks international consensus for optimal management of these vulnerable patients. We report a retrospective analysis of our fifteen-year experience from a large UK tertiary pediatric center, focusing on treatment modalities and outcomes, including late therapeutic toxicities. To our knowledge, this is the first UK series of congenital leukemia patients reported. Twelve patients with a median age of 16.4 days (1-60) were diagnosed with CAML in fifteen years. All patients presented unwell; 92% demonstrating skin involvement. 10 (83%) received chemotherapy; with 1 death at presentation and 1 spontaneous remission. 5 (42%) received subsequent stem cell transplant. Only 4 (33%) remain alive, with 5 (42%) dying in disease remission with treatment-related mortality. Documented cardiotoxicity was observed in 3 (25%) patients, with a further 2 (17%) suspected but not receiving postmortem. Treatment of congenital AML raises challenging diagnostic, therapeutic and ethical questions and requires multi-center, international collaboration to see improvements.

Adjuvant tyrosine kinase inhibitor therapy improves outcome for children and adolescents with acute lymphoblastic leukaemia who have an ABL-class fusion

Patients with an ABL-class fusion have a high risk of relapse on standard chemotherapy but are sensitive to tyrosine kinase inhibitors (TKI). In UKALL2011, we screened patients with post-induction MRD ≥1% and positive patients (12%) received adjuvant TKI. As the intervention started during UKALL2011, not all eligible patients were screened prospectively. Retrospective screening of eligible patients allowed the outcome of equivalent ABL-class patients who did and did not receive a TKI in first remission to be compared. ABL-class patients who received a TKI in first remission had a reduced risk of relapse/refractory disease: 0% vs. 63% at four years (P = 0·009).

A validated novel continuous prognostic index to deliver stratified medicine in pediatric acute lymphoblastic leukemia

Risk stratification is essential for the delivery of optimal treatment in childhood acute lymphoblastic leukemia. However, current risk stratification algorithms dichotomize variables and apply risk factors independently, which may incorrectly assume identical associations across biologically heterogeneous subsets and reduce statistical power. Accordingly, we developed and validated a prognostic index (PIUKALL) that integrates multiple risk factors and uses continuous data. We created discovery (n = 2405) and validation (n = 2313) cohorts using data from 4 recent trials (UKALL2003, COALL-03, DCOG-ALL10, and NOPHO-ALL2008). Using the discovery cohort, multivariate Cox regression modeling defined a minimal model including white cell count at diagnosis, pretreatment cytogenetics, and end-of-induction minimal residual disease. Using this model, we defined PIUKALL as a continuous variable that assigns personalized risk scores. PIUKALL correlated with risk of relapse and was validated in an independent cohort. Using PIUKALL to risk stratify patients improved the concordance index for all end points compared with traditional algorithms. We used PIUKALL to define 4 clinically relevant risk groups that had differential relapse rates at 5 years and were similar between the 2 cohorts (discovery: low, 3% [95% confidence interval (CI), 2%-4%]; standard, 8% [95% CI, 6%-10%]; intermediate, 17% [95% CI, 14%-21%]; and high, 48% [95% CI, 36%-60%; validation: low, 4% [95% CI, 3%-6%]; standard, 9% [95% CI, 6%-12%]; intermediate, 17% [95% CI, 14%-21%]; and high, 35% [95% CI, 24%-48%]). Analysis of the area under the curve confirmed the PIUKALL groups were significantly better at predicting outcome than algorithms employed in each trial. PIUKALL provides an accurate method for predicting outcome and more flexible method for defining risk groups in future studies.

Long-term outcome of a randomized controlled study in patients with newly diagnosed severe aplastic anemia treated with antithymocyte globulin and cyclosporine, with or without granulocyte colony-stimulating factor: a Severe Aplastic Anemia Working Party Trial from the European Group of Blood and Marrow Transplantation

This follow-up study of a randomized, prospective trial included 192 patients with newly diagnosed severe aplastic anemia receiving antithymoglobulin and cyclosporine, with or without granulocyte colony-stimulating factor (G-CSF). We aimed to evaluate the long-term effect of G-CSF on overall survival, event-free survival, probability of secondary myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML), clinical paroxysmal nocturnal hemoglobinuria, relapse, avascular osteonecrosis and chronic kidney disease. The median follow-up was 11.7 years (95% CI, 10.9-12.5). The overall survival rate at 15 years was 57±12% in the group given G-CSF and 63±12% in the group not given G-CSF (P=0.92); the corresponding event-free survival rates were 24±10% and 23±10%, respectively (P=0.36). In total, 9 patients developed MDS or AML, 10 only a clonal cytogenetic abnormality, 7 a solid cancer, 18 clinical paroxysmal nocturnal hemoglobinuria, 8 osteonecrosis, and 12 chronic kidney disease, without any difference between patients treated with or without G-CSF. The cumulative incidence of MDS, AML or isolated cytogenetic abnormality at 15 years was 8.5±3% for the G-CSF group and 8.2±3% for the non-G-CSF group (P=0.90). The cumulative incidence of any late event including myelodysplastic syndrome or acute myeloid leukemia, isolated cytogenetic abnormalities, solid cancer, clinical paroxysmal nocturnal hemoglobinuria, aseptic osteonecrosis, chronic kidney disease and relapse was 50±12% for the G-CSF group and 49±12% for the non-G-CSF group (P=0.65). Our results demonstrate that it is unlikely that G-CSF has an impact on the outcome of severe aplastic anemia; nevertheless, very late events are common and eventually affect the prognosis of these patients, irrespectively of their age at the time of immunosuppressive therapy (NCT01163942).

Impact of dose and duration of therapy on dexamethasone pharmacokinetics in childhood acute lymphoblastic leukaemia-a report from the UKALL 2011 trial

INTRODUCTION

The use of dexamethasone in acute lymphoblastic leukaemia therapy contributes to short- and long-term toxicities. The UKALL 2011 randomised trial investigated whether a more intense dexamethasone dose (10 mg/m2/d x 14d, short vs 6 mg/m2/d x 28d, standard) would lead to a more rapid cytoreduction and reduced adverse effects associated with longer durations of steroids in induction. The impact of dose and duration on dexamethasone pharmacokinetics was investigated.

METHODS

Blood samples were obtained on one of the first three and last three days of induction dexamethasone dosing at time points up to 8 h after oral administration. Plasma dexamethasone levels were quantified in 1084 plasma samples obtained from 174 children and a population pharmacokinetic model developed.

RESULTS

Drug exposure varied significantly between patients, with a >12-fold variation in AUC0-12h values and a marked overlap in dexamethasone exposures between dose levels. Intuitively, AUC0-12h was significantly higher with short dosing (10 mg/m2/d), but cumulative exposure was significantly higher with standard dosing over 28 days, after a higher cumulative dose. Concomitant rasburicase administration was associated with a 60% higher dexamethasone clearance. Day 8 bone marrow response was comparable between dosing arms, but those with <5% blast count exhibited a greater mean dexamethasone exposure than those with >5%. No statistical differences were observed between arms in terms of steroid-related toxicity or minimal residual disease at the end of induction.

CONCLUSION

The potential significance of dexamethasone AUC0-12h on early response and higher cumulative exposure on the standard arm suggest that duration of therapy and exposure may be more important factors than absolute dose from a clinical pharmacology perspective.

Haemophagocytic lymphohistiocytosis complicating visceral leishmaniasis in the UK: a case for detailed travel history, a high index of suspicion and timely diagnostics

A 4-month-old male infant presented acutely unwell with fever. He was initially treated for sepsis but failed to improve with IV broad spectrum antibiotics. Haemophagocytic lymphohistiocytosis (HLH) was diagnosed due to his fever, pancytopenia, splenomegaly, hypertriglyceridaemia, hypofibrinogenaemia and significant hyperferritinaemia. An array of differentials for HLH including both immunological and infectious causes were considered and excluded. He had travelled to Madrid, and hence visceral leishmaniasis (VL) was suspected, but was not confirmed on the initial bone marrow aspirate (BMA) microscopy or culture. He improved with empirical treatment with dexamethasone and liposomal amphotericin B. VL was later confirmed on BMA PCR. He made a good recovery and remained well at 12 month follow-up. Non-endemic countries need rapid and sensitive VL diagnostics. A thorough travel history and high clinical index of suspicion are necessary to avoid the pitfall of treatment with intense immunosuppression recommended in treatment guidelines for HLH.

Trypsin-encoding PRSS1-PRSS2 variations influence the risk of asparaginase-associated pancreatitis in children with acute lymphoblastic leukemia: a Ponte di Legno toxicity working group report

Asparaginase-associated pancreatitis is a life-threatening toxicity to childhood acute lymphoblastic leukemia treatment. To elucidate genetic predisposition and asparaginase-associated pancreatitis pathogenesis, ten trial groups contributed remission samples from patients aged 1.0-17.9 years treated for acute lymphoblastic leukemia between 2000 and 2016. Cases (n=244) were defined by the presence of at least two of the following criteria: (i) abdominal pain; (ii) levels of pancreatic enzymes ≥3 × upper normal limit; and (iii) imaging compatible with pancreatitis. Controls (n=1320) completed intended asparaginase therapy, with 78% receiving ≥8 injections of pegylated-asparaginase, without developing asparaginase-associated pancreatitis. rs62228256 on 20q13.2 showed the strongest association with the development of asparaginase-associated pancreatitis (odds ratio=3.75; P=5.2×10-8). Moreover, rs13228878 (OR=0.61; P=7.1×10-6) and rs10273639 (OR=0.62; P=1.1×10-5) on 7q34 showed significant association with the risk of asparaginase-associated pancreatitis. A Dana Farber Cancer Institute ALL Consortium cohort consisting of patients treated on protocols between 1987 and 2004 (controls=285, cases=33), and the Children's Oncology Group AALL0232 cohort (controls=2653, cases=76) were available as replication cohorts for the 20q13.2 and 7q34 variants, respectively. While rs62228256 was not validated as a risk factor (P=0.77), both rs13228878 (P=0.03) and rs10273639 (P=0.04) were. rs13228878 and rs10273639 are in high linkage disequilibrium (r2=0.94) and associated with elevated expression of the PRSS1 gene, which encodes for trypsinogen, and are known risk variants for alcohol-associated and sporadic pancreatitis in adults. Intra-pancreatic trypsinogen cleavage to proteolytic trypsin induces autodigestion and pancreatitis. In conclusion, this study finds a shared genetic predisposition between asparaginase-associated pancreatitis and non-asparaginase-associated pancreatitis, and targeting the trypsinogen activation pathway may enable identification of effective interventions for asparaginase-associated pancreatitis.

Impact of T-cell depletion strategies on outcomes following hematopoietic stem cell transplantation for idiopathic aplastic anemia: A study on behalf of the European blood and marrow transplant severe aplastic anemia working party

We retrospectively analyzed the outcomes of 1837 adults and children with severe aplastic anemia (SAA) who underwent matched sibling donor (MSD) and matched unrelated donor (MUD) hemopoietic stem cell transplantation (HSCT) between 2000 and 2013. Patients were grouped by transplant conditioning containing either anti-thymocyte globulin (ATG) (n = 1283), alemtuzumab (n = 261), or no serotherapy (NS) (n = 293). The risks of chronic GvHD were significantly reduced when ATG or alemtuzumab were compared with NS (P = .021 and .003, respectively). Acute GVHD was significantly reduced in favor of alemtuzumab compared with ATG (P = .012) and NS (P < .001). By multivariate analysis, when compared with ATG, alemtuzumab was associated with a lower risk of developing acute (OR 0.262; 95% CI 0.14-0.47; P < .001) and chronic GVHD (HR 0.58; 95% CI 0.35-0.94; P = .027). OS was significantly better in ATG and alemtuzumab patients compared with NS (P = .010 and .025). Our data shows inclusion of serotherapy in MSD and MUD HSCT for patients with SAA reduces chronic GVHD and provides a survival advantage over patients not receiving serotherapy. Notably, alemtuzumab reduced the risk of acute and chronic GvHD compared with ATG and indicates that alemtuzumab might be the serotherapy of choice for MSD and MUD transplants for SAA.

Galactose protects against cell damage in mouse models of acute pancreatitis

Acute pancreatitis (AP), a human disease in which the pancreas digests itself, has substantial mortality with no specific therapy. The major causes of AP are alcohol abuse and gallstone complications, but it also occurs as an important side effect of the standard asparaginase-based therapy for childhood acute lymphoblastic leukemia. Previous investigations into the mechanisms underlying pancreatic acinar cell death induced by alcohol metabolites, bile acids, or asparaginase indicated that loss of intracellular ATP generation is an important factor. We now report that, in isolated mouse pancreatic acinar cells or cell clusters, removal of extracellular glucose had little effect on this ATP loss, suggesting that glucose metabolism was severely inhibited under these conditions. Surprisingly, we show that replacing glucose with galactose prevented or markedly reduced the loss of ATP and any subsequent necrosis. Addition of pyruvate had a similar protective effect. We also studied the effect of galactose in vivo in mouse models of AP induced either by a combination of fatty acids and ethanol or asparaginase. In both cases, galactose markedly reduced acinar necrosis and inflammation. Based on these data, we suggest that galactose feeding may be used to protect against AP.

Molecular remission of infant B-ALL after infusion of universal TALEN gene-edited CAR T cells

Autologous T cells engineered to express chimeric antigen receptor against the B cell antigen CD19 (CAR19) are achieving marked leukemic remissions in early-phase trials but can be difficult to manufacture, especially in infants or heavily treated patients. We generated universal CAR19 (UCART19) T cells by lentiviral transduction of non-human leukocyte antigen-matched donor cells and simultaneous transcription activator-like effector nuclease (TALEN)-mediated gene editing of T cell receptor α chain and CD52 gene loci. Two infants with relapsed refractory CD19⁺ B cell acute lymphoblastic leukemia received lymphodepleting chemotherapy and anti-CD52 serotherapy, followed by a single-dose infusion of UCART19 cells. Molecular remissions were achieved within 28 days in both infants, and UCART19 cells persisted until conditioning ahead of successful allogeneic stem cell transplantation. This bridge-to-transplantation strategy demonstrates the therapeutic potential of gene-editing technology.

iPSC modeling of severe aplastic anemia reveals impaired differentiation and telomere shortening in blood progenitors

Aplastic Anemia (AA) is a bone marrow failure (BMF) disorder, resulting in bone marrow hypocellularity and peripheral pancytopenia. Severe aplastic anemia (SAA) is a subset of AA defined by a more severe phenotype. Although the immunological nature of SAA pathogenesis is widely accepted, there is an increasing recognition of the role of dysfunctional hematopoietic stem cells in the disease phenotype. While pediatric SAA can be attributable to genetic causes, evidence is evolving on previously unrecognized genetic etiologies in a proportion of adults with SAA. Thus, there is an urgent need to better understand the pathophysiology of SAA, which will help to inform the course of disease progression and treatment options. We have derived induced pluripotent stem cell (iPSC) from three unaffected controls and three SAA patients and have shown that this in vitro model mimics two key features of the disease: (1) the failure to maintain telomere length during the reprogramming process and hematopoietic differentiation resulting in SAA-iPSC and iPSC-derived-hematopoietic progenitors with shorter telomeres than controls; (2) the impaired ability of SAA-iPSC-derived hematopoietic progenitors to give rise to erythroid and myeloid cells. While apoptosis and DNA damage response to replicative stress is similar between the control and SAA-iPSC-derived-hematopoietic progenitors, the latter show impaired proliferation which was not restored by eltrombopag, a drug which has been shown to restore hematopoiesis in SAA patients. Together, our data highlight the utility of patient specific iPSC in providing a disease model for SAA and predicting patient responses to various treatment modalities.

Genotype-Specific Minimal Residual Disease Interpretation Improves Stratification in Pediatric Acute Lymphoblastic Leukemia

Purpose Minimal residual disease (MRD) and genetic abnormalities are important risk factors for outcome in acute lymphoblastic leukemia. Current risk algorithms dichotomize MRD data and do not assimilate genetics when assigning MRD risk, which reduces predictive accuracy. The aim of our study was to exploit the full power of MRD by examining it as a continuous variable and to integrate it with genetics. Patients and Methods We used a population-based cohort of 3,113 patients who were treated in UKALL2003, with a median follow-up of 7 years. MRD was evaluated by polymerase chain reaction analysis of Ig/TCR gene rearrangements, and patients were assigned to a genetic subtype on the basis of immunophenotype, cytogenetics, and fluorescence in situ hybridization. To examine response kinetics at the end of induction, we log-transformed the absolute MRD value and examined its distribution across subgroups. Results MRD was log normally distributed at the end of induction. MRD distributions of patients with distinct genetic subtypes were different ( P < .001). Patients with good-risk cytogenetics demonstrated the fastest disease clearance, whereas patients with high-risk genetics and T-cell acute lymphoblastic leukemia responded more slowly. The risk of relapse was correlated with MRD kinetics, and each log reduction in disease level reduced the risk by 20% (hazard ratio, 0.80; 95% CI, 0.77 to 0.83; P < .001). Although the risk of relapse was directly proportional to the MRD level within each genetic risk group, absolute relapse rate that was associated with a specific MRD value or category varied significantly by genetic subtype. Integration of genetic subtype-specific MRD values allowed more refined risk group stratification. Conclusion A single threshold for assigning patients to an MRD risk group does not reflect the response kinetics of the different genetic subtypes. Future risk algorithms should integrate genetics with MRD to accurately identify patients with the lowest and highest risk of relapse.

Calcium and adenosine triphosphate control of cellular pathology: asparaginase-induced pancreatitis elicited via protease-activated receptor 2

Exocytotic secretion of digestive enzymes from pancreatic acinar cells is elicited by physiological cytosolic Ca²⁺ signals, occurring as repetitive short-lasting spikes largely confined to the secretory granule region, that stimulate mitochondrial adenosine triphosphate (ATP) production. By contrast, sustained global cytosolic Ca²⁺ elevations decrease ATP levels and cause necrosis, leading to the disease acute pancreatitis (AP). Toxic Ca²⁺ signals can be evoked by products of alcohol and fatty acids as well as bile acids. Here, we have investigated the mechanism by which l-asparaginase evokes AP. Asparaginase is an essential element in the successful treatment of acute lymphoblastic leukaemia, the most common type of cancer affecting children, but AP is a side-effect occurring in about 5–10% of cases. Like other pancreatitis-inducing agents, asparaginase evoked intracellular Ca²⁺ release followed by Ca²⁺ entry and also substantially reduced Ca²⁺ extrusion because of decreased intracellular ATP levels. The toxic Ca²⁺ signals caused extensive necrosis. The asparaginase-induced pathology depended on protease-activated receptor 2 and its inhibition prevented the toxic Ca²⁺ signals and necrosis. We tested the effects of inhibiting the Ca²⁺ release-activated Ca²⁺ entry by the Ca²⁺ channel inhibitor GSK-7975A. This markedly reduced asparaginase-induced Ca²⁺ entry and also protected effectively against the development of necrosis.

This article is part of the themed issue ‘Evolution brings Ca²⁺ and ATP together to control life and death’.

Asparaginase-associated pancreatitis in childhood acute lymphoblastic leukaemia: an observational Ponte di Legno Toxicity Working Group study

BACKGROUND

Survival for childhood acute lymphoblastic leukaemia surpasses 90% with contemporary therapy; however, patients remain burdened by the severe toxic effects of treatment, including asparaginase-associated pancreatitis. To investigate the risk of complications and risk of re-exposing patients with asparaginase-associated pancreatitis to asparaginase, 18 acute lymphoblastic leukaemia trial groups merged data for this observational study.

METHODS

Patient files from 26 trials run by 18 trial groups were reviewed on children (aged 1·0-17·9 years) diagnosed with t(9;22)-negative acute lymphoblastic leukaemia between June 1, 1996, and Jan 1, 2016, who within 50 days of asparaginase exposure developed asparaginase-associated pancreatitis. Asparaginase-associated pancreatitis was defined by at least two criteria: abdominal pain, pancreatic enzymes at least three times the upper limit of normal (ULN), and imaging compatible with pancreatitis. Patients without sufficient data for diagnostic criteria were excluded. Primary outcomes were defined as acute and persisting complications of asparaginase-associated pancreatitis and risk of re-exposing patients who suffered an episode of asparaginase-associated pancreatitis to asparaginase. Data were collected from Feb 2, 2015, to June 30, 2016, and analysed and stored in a common database at Rigshospitalet, Copenhagen, Denmark.

FINDINGS

Of 465 patients with asparaginase-associated pancreatitis, 33 (8%) of 424 with available data needed mechanical ventilation, 109 (26%) of 422 developed pseudocysts, acute insulin therapy was needed in 81 (21%) of 393, and seven (2%) of 458 patients died. Risk of assisted mechanical ventilation, need for insulin, pseudocysts, or death was associated with older age (median age for patients with complications 10·5 years [IQR 6·4-13·8] vs without complications 6·1 years [IQR 3·6-12·2], p<0·0001), and having one or more affected vital signs (fever, hypotension, tachycardia, or tachypnoea; 96 [44%] of 217 patients with affected vital signs vs 11 [24%] of 46 patients without affected vital signs, p=0·02). 1 year after diagnosis of asparaginase-associated pancreatitis, 31 (11%) of 275 patients still needed insulin or had recurrent abdominal pain or both. Both the risk of persisting need for insulin therapy and recurrent abdominal pain were associated with having had pseudocysts (odds ratio [OR] 9·48 [95% CI 3·01-35·49], p=0·0002 for insulin therapy; OR 11·79 [4·30-37·98], p<0·0001 for recurrent abdominal pain). Within 8 years of asparaginase-associated pancreatitis, risk of abdominal symptoms dropped from 8% (26 of 312) to 0% (0 of 35) but the need for insulin therapy remained constant (9%, three of 35). 96 patients were re-exposed to asparaginase, including 59 after a severe asparaginase-associated pancreatitis (abdominal pain or pancreatic enzymes at least three times the ULN or both lasting longer than 72 h). 44 (46%) patients developed a second asparaginase-associated pancreatitis, 22 (52%) of 43 being severe. Risk of persisting need for insulin or abdominal pain after having had two versus one asparaginase-associated pancreatitis did not differ (three [7%] of 42 vs 28 [12%] of 233, p=0·51). Risk of a second asparaginase-associated pancreatitis was not associated with any baseline patient characteristics.

INTERPRETATION

Since the risk of a second asparaginase-associated pancreatitis was not associated with severity of the first asparaginase-associated pancreatitis and a second asparaginase-associated pancreatitis did not involve an increased risk of complications, asparaginase re-exposure should be determined mainly by the anticipated need for asparaginase for antileukaemic efficacy. A study of the genetic risk factors identifying patients in whom asparaginase exposure should be restricted is needed.

FUNDING

The Danish Childhood Cancer Foundation and The Danish Cancer Society (R150-A10181).

Use of Minimal Residual Disease Assessment to Redefine Induction Failure in Pediatric Acute Lymphoblastic Leukemia

Purpose

Our aim was to determine the role of end-of-induction (EOI) minimal residual disease (MRD) assessment in the identification and stratification of induction failure in patients with pediatric acute lymphoblastic leukemia (ALL) and to identify genetic abnormalities that drive disease in these patients.

Patients and Methods

Analysis included 3,113 patients who were treated in the Medical Research Council UKALL2003 multicenter randomized trial (NCT00222612) between 2003 and 2011. MRD was measured by using standardized real-time quantitative PCR. Median follow-up was 5 years 9 months.

Results

Fifty-nine patients (1.9%) had morphologic induction failure with 5-year event-free survival (EFS) of 50.7% (95% CI, 37.4 to 64.0) and 5-year overall survival of 57.7% (95% CI, 44.2 to 71.2). Of these, a small proportion of patients with M2 marrow (6 of 44) and a low EOI MRD level (< 0.01%) had 5-year EFS of 100%. Conversely, among patients with morphologic remission 2.3% (61 of 2,633) had high MRD (≥ 5%) and 5-year EFS of 47.0% (95% CI, 32.9 to 61.1), which was similar to those with morphologic induction failure. Redefining induction failure to include morphologic induction failure and/or MRD ≥ 5% identified 3.9% (120 of 3,133 patients) of the trial cohort with 5-year EFS of 48.0% (95% CI, 39.3 to 58.6). Induction failure (morphologic or MRD ≥ 5%) occurred most frequently in T-ALL (10.1%; 39 of 386 T-ALL cases) and B-other ALL, that is, lacking established chromosomal abnormalities (5.6%; 43 of 772 B-other cases). Genetic testing within the B-other group revealed the presence of PDGFRB gene fusions, particularly EBF1-PDGFRB, in almost one third of B-other ALL cases.

Conclusion

Integration of EOI MRD level with morphology identifies induction failure more precisely than morphology alone. Prevalence of EBF1-PDGFRB fusions in this group highlights the importance of genetic screening to identify abnormalities that may be targets for novel agents.

A system of recurrent neural networks for modularising, parameterising and dynamic analysis of cell signalling networks

In this paper, we show how to extend our previously proposed novel continuous time Recurrent Neural Networks (RNN) approach that retains the advantage of continuous dynamics offered by Ordinary Differential Equations (ODE) while enabling parameter estimation through adaptation, to larger signalling networks using a modular approach. Specifically, the signalling network is decomposed into several sub-models based on important temporal events in the network. Each sub-model is represented by the proposed RNN and trained using data generated from the corresponding ODE model. Trained sub-models are assembled into a whole system RNN which is then subjected to systems dynamics and sensitivity analyses. The concept is illustrated by application to G1/S transition in cell cycle using Iwamoto et al. (2008) ODE model. We decomposed the G1/S network into 3 sub-models: (i) E2F transcription factor release; (ii) E2F and CycE positive feedback loop for elevating cyclin levels; and (iii) E2F and CycA negative feedback to degrade E2F. The trained sub-models accurately represented system dynamics and parameters were in good agreement with the ODE model. The whole system RNN however revealed couple of parameters contributing to compounding errors due to feedback and required refinement to sub-model 2. These related to the reversible reaction between CycE/CDK2 and p27, its inhibitor. The revised whole system RNN model very accurately matched dynamics of the ODE system. Local sensitivity analysis of the whole system model further revealed the most dominant influence of the above two parameters in perturbing G1/S transition, giving support to a recent hypothesis that the release of inhibitor p27 from Cyc/CDK complex triggers cell cycle stage transition. To make the model useful in a practical setting, we modified each RNN sub-model with a time relay switch to facilitate larger interval input data (≈20min) (original model used data for 30s or less) and retrained them that produced parameters and protein concentrations similar to the original RNN system. Results thus demonstrated the reliability of the proposed RNN method for modelling relatively large networks by modularisation for practical settings. Advantages of the method are its ability to represent accurate continuous system dynamics and ease of: parameter estimation through training with data from a practical setting, model analysis (40% faster than ODE), fine tuning parameters when more data are available, sub-model extension when new elements and/or interactions come to light and model expansion with addition of sub-models.

Concise Review: Getting to the Core of Inherited Bone Marrow Failures

Bone marrow failure syndromes (BMFS) are a group of disorders with complex pathophysiology characterized by a common phenotype of peripheral cytopenia and/or hypoplastic bone marrow. Understanding genetic factors contributing to the pathophysiology of BMFS has enabled the identification of causative genes and development of diagnostic tests. To date more than 40 mutations in genes involved in maintenance of genomic stability, DNA repair, ribosome and telomere biology have been identified. In addition, pathophysiological studies have provided insights into several biological pathways leading to the characterization of genotype/phenotype correlations as well as the development of diagnostic approaches and management strategies. Recent developments in bone marrow transplant techniques and the choice of conditioning regimens have helped improve transplant outcomes. However, current morbidity and mortality remain unacceptable underlining the need for further research in this area. Studies in mice have largely been unable to mimic disease phenotype in humans due to difficulties in fully replicating the human mutations and the differences between mouse and human cells with regard to telomere length regulation, processing of reactive oxygen species and lifespan. Recent advances in induced pluripotency have provided novel insights into disease pathogenesis and have generated excellent platforms for identifying signaling pathways and functional mapping of haplo‐insufficient genes involved in large‐scale chromosomal deletions–associated disorders. In this review, we have summarized the current state of knowledge in the field of BMFS with specific focus on modeling the inherited forms and how to best utilize these models for the development of targeted therapies. Stem Cells2017;35:284–298

Impact of Conditioning Regimen on Outcomes for Children with Acute Myeloid Leukemia Undergoing Transplantation in First Complete Remission. An Analysis on Behalf of the Pediatric Disease Working Party of the European Group for Blood and Marrow Transplantation

Hematopoietic stem cell transplantation (HSCT) represents the cornerstone of treatment in pediatric high-risk and relapsed acute myeloid leukemia (AML). The aim of the present study was to compare outcomes of pediatric patients with AML undergoing HSCT using 3 different conditioning regimens: total body irradiation (TBI) and cyclophosphamide (Cy); busulfan (Bu) and Cy; or Bu, Cy, and melphalan (Mel). In this retrospective study, registry data for patients > 2 and <18 years age undergoing matched allogeneic HSCT for AML in first complete remission (CR1) in 204 European Group for Blood and Marrow Transplantation centers between 2000 and 2010 were analyzed. Data were available for 631 patients; 458 patients received stem cells from a matched sibling donor and 173 from a matched unrelated donor. For 440 patients, bone marrow was used as stem cell source, and 191 patients received peripheral blood stem cells. One hundred nine patients received TBICy, 389 received BuCy, and 133 received BuCyMel as their preparatory regimen. Median follow-up was 55 months. Patients receiving BuCyMel showed a lower incidence of relapse at 5 years (14.7% versus 31.5% in BuCy versus 30% in TBICy, P < .01) and higher overall survival (OS) (76.6% versus 64% versus 64.5%, P = .04) and leukemia-free survival (LFS) (74.5% versus 58% versus 61.9%, P < .01), with a comparable nonrelapse mortality (NRM) (10.8% versus 10.5% versus 8.1%, P = .79). Acute graft-versus-host disease (GVHD) grades III and IV but not chronic GVHD, was higher in patients receiving BuCyMel. Older age at HSCT had an adverse impact on NRM and the use of peripheral blood as stem cell source was associated with increased chronic GVHD and NRM as well as lower LFS and OS. Among pediatric patients receiving HSCT for AML in CR1, the use of BuCyMel conditioning proved superior to TBICy and BuCy in reducing relapse and improving LFS.

Evolving hematopoietic stem cell transplantation strategies in severe aplastic anemia

PURPOSE OF REVIEW

Significant improvements in unrelated donor hematopoietic stem cell transplantation (HSCT) in recent years have solidified its therapeutic role in severe aplastic anemia (SAA) and led to the evolution of treatment algorithms, particularly for children.

RECENT FINDINGS

Advances in understanding the genetics of inherited bone marrow failure syndromes (IBMFS) have allowed more confidence in accurately diagnosing SAA and avoiding treatments that could be dangerous and ineffective in individuals with IBMFS, which can be diagnosed in 10-20% of children presenting with a picture of SAA. Additionally long-term survival after matched sibling donor and matched unrelated donor HSCT now exceed 90% in children. Late effects after HSCT for SAA are minimal with current strategies, and compare favorably to late effects after upfront immunosuppressive therapy, except for patients with chronic graft versus host disease.

SUMMARY

Careful assessment for signs or symptoms of IBMFS, along with genetic screening for these disorders, is of major importance. Matched sibling donor HSCT is already considered the standard of care for upfront therapy and some groups are evaluating matched unrelated donor HSCT as primary therapy. Ongoing studies will continue to challenge treatment algorithms and may lead to an even more expanded role for HSCT in SAA.

Similar outcome of upfront-unrelated and matched sibling stem cell transplantation in idiopathic paediatric aplastic anaemia. A study on behalf of the UK Paediatric BMT Working Party, Paediatric Diseases Working Party and Severe Aplastic Anaemia Working Party of EBMT

We explored the feasibility of unrelated donor haematopoietic stem cell transplant (HSCT) upfront without prior immunosuppressive therapy (IST) in paediatric idiopathic severe aplastic anaemia (SAA). This cohort was then compared to matched historical controls who had undergone first-line therapy with a matched sibling/family donor (MSD) HSCT (n = 87) or IST with horse antithymocyte globulin and ciclosporin (n = 58) or second-line therapy with unrelated donor HSCT post-failed IST (n = 24). The 2-year overall survival in the upfront cohort was 96 ± 4% compared to 91 ± 3% in the MSD controls (P = 0·30) and 94 ± 3% in the IST controls (P = 0·68) and 74 ± 9% in the unrelated donor HSCT post-IST failure controls (P = 0·02).The 2-year event-free survival in the upfront cohort was 92 ± 5% compared to 87 ± 4% in MSD controls (P = 0·37), 40 ± 7% in IST controls (P = 0·0001) and 74 ± 9% in the unrelated donor HSCT post-IST failure controls (n = 24) (P = 0·02). Outcomes for upfront-unrelated donor HSCT in paediatric idiopathic SAA were similar to MSD HSCT and superior to IST and unrelated donor HSCT post-IST failure. Front-line therapy with matched unrelated donor HSCT is a novel treatment approach and could be considered as first-line therapy in selected paediatric patients who lack a MSD.

Outcome of aplastic anaemia in children. A study by the severe aplastic anaemia and paediatric disease working parties of the European group blood and bone marrow transplant

This study analysed the outcome of 563 Aplastic Anaemia (AA) children aged 0-12 years reported to the Severe Aplastic Anaemia Working Party database of the European Society for Blood and Marrow Transplantation, according to treatment received. Overall survival (OS) after upfront human leucocyte antigen-matched family donor (MFD) haematopoietic stem cell transplantation (HSCT) or immunosuppressive treatment (IST) was 91% vs. 87% (P 0·18). Event-free survival (EFS) after upfront MFD HSCT or IST was 87% vs. 33% (P 0·001). Ninety-one of 167 patients (55%) failed front-line IST and underwent rescue HSCT. The OS of this rescue group was 83% compared with 91% for upfront MFD HSCT patients and 97% for those who did not fail IST up-front (P 0·017). Rejection was 2% for MFD HSCT and HSCT post-IST failure (P 0·73). Acute graft-versus-host disease (GVHD) grade II-IV was 8% in MFD graft vs. 25% for HSCT post-IST failure (P < 0·0001). Chronic GVHD was 6% in MFD HSCT vs. 20% in HSCT post-IST failure (P < 0·0001). MFD HSCT is an excellent therapy for children with AA. IST has a high failure rate, but remains a reasonable first-line choice if MFD HSCT is not available because high OS enables access to HSCT, which is a very good rescue option.

Modelling the dynamics of CaMKII-NMDAR complex related to memory formation in synapses: the possible roles of threonine 286 autophosphorylation of CaMKII in long term potentiation

A synaptic protein, Ca(2+)/Calmodulin dependent protein kinase II (CaMKII), has complex state transitions and facilitates the emergence of long term potentiation (LTP), which is highly correlated to memory formation. Two of the state transitions are critical for LTP: (1) threonine 286 autophosphorylation of CaMKII; and (2) binding to N-methyl-d-aspartate receptor (NMDAR) in the postsynaptic density (PSD) to form CaMKII-NMDAR complex. Both of these state transitions retain the activity of CaMKII when the induction signal disappears which is very important for the long-lasting characteristics of LTP. However, the possible relationships between the state transitions in the emergence of LTP are not well understood. We develop a mathematical model of the formation of CaMKII-NMDAR complex with the full state transitions of CaMKII, including the autophosphorylation, based on ordinary differential equations. In addition, we formulate a probabilistic framework for the binding between CaMKII and NMDAR. The model gives accurate predictions of the behaviours of CaMKII in comparisons to the experimental observations. Using the model, we show that: (1) the formation of CaMKII-NMDAR complex is dependent not only on the binding affinity between CaMKII and NMDAR, but also on the translocation of CaMKII into PSD; and (2) the autophosphorylation is not a requirement for the formation of CaMKII-NMDAR complex, but is important for the rapid formation of CaMKII-NMDAR complex during LTP.

The meiotic-mitotic initiation switch in budding yeast maintains its function robustly against sensitive parameter perturbations

Experiments show that the meiotic-mitotic initiation switch in budding yeast functions robustly during the early hours of meiosis initiation. In this study, we explain these experimental observations first by understanding how this switching occurs during the early hours of meiosis by studying the temporal variation of this switch at the gene expression level. Then, we investigate the effects on this meiotic-mitotic switching from the perturbations of the most sensitive parameters in budding yeast meiosis initiation network. We use a mathematical model of meiosis initiation in budding yeast for this task and find the most sensitive group of parameters that influence the expressions of meiosis and mitosis initiators at all stages of the meiotic-mitotic switch. The results indicate that the transition region of the switch, where a double negative feedback loop between meiosis (Ime2) and mitosis (Cdk1/Cln3) initiators plays a major role, shows lower robustness. Feedback loops are frequently observed serving as a major robust adaption mechanism in many biological networks. Consequences of this less robust region appear in the transition region of the resulting switches. Most importantly, despite the differences observed in the transition region, we find that the meiotic-mitotic switch robustly maintains its main function of transition from meiosis to mitosis when the nutrients are re-supplied, against the perturbations in the sensitive parameters.