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Background Wolman disease is a rare, lysosomal storage disorder in which biallelic variants in the LIPA gene result in reduced or complete lack of lysosomal acid lipase. The accumulation of the substrates; cholesterol esters and triglycerides, significantly impacts cellular function. Untreated patients die within the first 12 months of life. Clinically, patients present severely malnourished, with diarrhoea and hepatosplenomegaly, many have an inflammatory phenotype, including with hemophagocytic lymphohistiocytosis (HLH). Hematopoietic stem cell transplant (HCT) had been historically the only treatment available but has a high procedure-related mortality because of disease progression and disease-associated morbidities. More recently, enzyme replacement therapy (ERT) with dietary substrate reduction (DSR) has significantly improved patient survival. However, ERT is life long, expensive and its utility is limited by anti-drug antibodies (ADA) and the need for central venous access. Results We describe five Wolman disease patients diagnosed in infancy that were treated at Royal Manchester Children's Hospital receiving ERT with DSR then HCT—multimodal therapy. In 3/5 an initial response to ERT was attenuated by ADA with associated clinical and laboratory features of deterioration. 1/5 developed anaphylaxis to ERT and the other patient died post HCT with ongoing HLH. All patients received allogeneic HCT. 4/5 patients are alive, and both disease phenotype and laboratory parameters are improved compared to when they were on ERT alone. The gastrointestinal symptoms are particularly improved after HCT, with reduced diarrhoea and vomiting. This allows gradual structured normalisation of diet with improved tolerance of dietary fat. Histologically there are reduced cholesterol clefts, fewer foamy macrophages and an improved villous structure. Disease biomarkers also show improvement with ERT, immunotherapy and HCT. Three patients have mixed chimerism after HCT, indicating a likely engraftment-defect in this condition. Conclusion We describe combined ERT, DSR and HCT, multimodal treatment for Wolman disease. ERT and DSR stabilises the sick infant and reduces the formerly described prohibitively high, transplant-associated mortality in this condition. HCT abrogates the problems of ERT, namely attenuating ADA, the need for continuing venous access, and continuing high cost drug treatment. HCT also brings improved efficacy, particularly evident in improved gastrointestinal function and histology. Multimodal therapy should be considered a new paradigm of treatment for Wolman disease patients where there is an attenuated response to ERT, and for all patients where there is a well-matched transplant donor, in order to improve long term gut function, tolerance of a normal diet and quality of life.

CAR T-cell manufacturing failure (MF) is a situation where the manufacturing process fails to yield a product or results in one which is out-of-specification (OOS). We conducted a multicentre retrospective review of factors contributing to MF and patient outcomes. Of 981 large B-cell lymphoma (LBCL) patients approved for CAR T-cell therapy, 38 (3.87%) had MF. Eleven patients received delayed infusion with a product in-specification (delayed-infused) following 21 remanufacturing attempts. OOS product was infused in 13 (OOS-infused), and 14 were not infused. For comparison, we included 38 LBCL controls without MF; 29 received infusion (controls-infused). Prior bendamustine was the only baseline variable associated with MF risk, largely due to therapy within 6 months; 23.7% MF vs 0% controls ( P  = 0.0029). Overall survival (OS) and progression-free survival (PFS) were not significantly different for infused patients, with 1-year OS (PFS) of 52.8% (46.2%), 46.8% (24.2%) and 68.4% (41.4%) for OOS-infused, delayed-infused and controls-infused respectively (PFS HR OOS-infused vs controls-infused 1.41, P  = 0.40; delayed-infused vs controls-infused 1.64, P  = 0.25; and OOS-infused vs delayed-infused 0.86, P  = 0.76). CRS, ICANS and cytopenias were not significantly different between cohorts. Outcomes for OOS-infused LBCL patients following MF are encouraging. Remanufacturing led to infusion of a product in-specification in around 50% and may be an option for patients where a suitable OOS product is not available.

Myeloid chimerism better reflects donor stem cell engraftment than whole-blood chimerism in assessing graft function following allogeneic hematopoietic stem cell transplant (HCT). We describe our experience with 130 patients aged younger than 18 years, treated with allogeneic HCT using bone marrow or PBSC from HLA-matched donors for non-malignant diseases, whose pre-transplant conditioning therapy included alemtuzumab and who were monitored with lineage-specific chimerism after transplant. At 6 years post-transplant, overall survival (OS) was 91.1% and event-free survival (EFS) was 81.5%, with no grade III-IV acute GvHD or chronic GVHD observed. Recipient T-cells did not contribute to graft loss. Mixed T-cell chimerism (MC) did not affect EFS, and there was no connection between T-cell chimerism and myeloid chimerism in patients with MC or graft loss. MC significantly correlated with virus infection; more children with MC were CMV seropositive than those with complete chimerism (CC). Additionally, MC was more common in patients with CMV viramia post-transplant. CD8 T-cell reconstitution was affected by viral reactivation, including CMV, with CD8 T-cell counts higher in the MC group than in the CC group. Mixed T-cell chimerism is due to autologous, virus-specific, predominantly CD8, T-cell expansion, and is protective and not deleterious to the recipient.

Mucopolysaccharidosis type IH (MPSIH) is a lysosomal storage disorder whose untreated course involves progressive multisystem deterioration and death within the first decade of life. Allogeneic haematopoietic stem cell transplantation (HSCT) is an established treatment modality that improves functional outcome and long-term survival. Optimal outcome requires transplantation early in life and with myeloablative conditioning. Severe cardiomyopathy can be present at diagnosis and may seemingly preclude this approach. We performed a retrospective review of those cases transplanted in Manchester since 2000 that initially presented with established cardiomyopathy, with a view to identifying general management principles. Of 44 MPSIH children transplanted in this period, 6 had displayed moderate or severe cardiomyopathy at presentation; symptomatic cardiac failure was the predominant presenting feature in five of these. Echocardiographic and clinical improvement in cardiac function was observed with extended enzyme replacement therapy (ERT) in all cases, with recovery of fractional shortening to ≥25 % achieved in all patients before coming to transplant (after median 19 weeks ERT). All were transplanted successfully, with good functional and cardiologic outcomes. However, cyclophosphamide conditioning was implicated in acute post-transplant cardiac decompensation in several cases. Our experiences highlight three important messages: (1) A diagnosis of MPSIH should be considered in any infant presenting with unexplained severe cardiac failure; (2) ERT pre-transplant can improve cardiac function sufficiently to permit safe HSCT using myeloablative conditioning; and (3) High dose cyclophosphamide should be avoided in conditioning these patients.

Background Pseudohyperkalaemia is relatively uncommon in children, but needs to be considered in cases where extreme hyperkalaemia is associated with normal renal function. Case A previously well 12 year-old boy presented with new onset T cell acute lymphoblastic leukaemia associated with a high peripheral blood white cell count. Plasma biochemistry tests on a blood sample sent to the laboratory using a pneumatic tube system showed a high plasma potassium level of 16.6 mmol/l, with otherwise normal electrolytes and renal function. A 12-lead electrocardiogram was normal, with no changes suggestive of hyperkalaemia. Pseudohyperkalaemia was suspected, and further samples transported to the laboratory by foot showed normal plasma potassium levels. It was subsequently demonstrated that the pseudohyperkalemia was due to the lysis of leukaemic white cells during the transport of blood samples from the ward to the laboratory within the pneumatic tube system. Conclusions Paediatricians caring for children with haematological malignancies need to be aware of this cause of pseudohyperkalaemia so that unnecessary treatment, including the commencement of acute dialysis, is avoided. We recommend that blood samples collected from children with high white cell count malignancies are transported to the laboratory by foot rather than in pneumatic tube systems.

Niemann–Pick disease type C2 (NPC2) is caused by the inherited deficiency of a lysosomal cholesterol transport protein, NPC2 protein. Many cases of NPC2 present in early infancy with inflammatory lung disease, with subsequent severe neurological disease and death in early childhood. This disease is theoretically correctable by bone marrow transplantation (BMT), as the NPC2 protein is small and soluble and secreted and recaptured by the mannose-6-phosphate pathway. In this report we describe the first successful allogeneic bone marrow transplantation for this condition in a 16-month-old boy homozygous for the NPC2 p.E20X mutation, which has hitherto been reported to cause disease with a severe phenotype. During BMT there was an initial improvement of the established respiratory illness, with the immune suppression associated with transplant conditioning, but there was subsequent marked deterioration at the time of immune reconstitution and donor cell engraftment. This ‘graft versus substrate’ reaction was managed with intensive immune suppressant therapy, and it gradually resolved as the substrate was cleared by the engrafted donor macrophages. All immune suppression was withdrawn 18 months after transplantation, and his respiratory illness has resolved. He walked independently at 24 months and is continuing to reach developmental milestones after receiving his transplant. We conclude that the successful treatment of Niemann–Pick C2 therefore seems likely to be associated with a severe post-transplantation ‘graft versus substrate’ reaction that requires intense immune suppression before eventual resolution.

Chimeric antigen receptor (CAR)-modified T cells targeting CD19 demonstrate unparalleled responses in relapsed/refractory acute lymphoblastic leukemia (ALL) 1 – 5 , but toxicity, including cytokine-release syndrome (CRS) and neurotoxicity, limits broader application. Moreover, 40–60% of patients relapse owing to poor CAR T cell persistence or emergence of CD19 − clones. Some factors, including the choice of single-chain spacer 6 and extracellular 7 and costimulatory domains 8 , have a profound effect on CAR T cell function and persistence. However, little is known about the impact of CAR binding affinity. There is evidence of a ceiling above which increased immunoreceptor affinity may adversely affect T cell responses 9 – 11 . We generated a novel CD19 CAR (CAT) with a lower affinity than FMC63, the high-affinity binder used in many clinical studies 1 – 4 . CAT CAR T cells showed increased proliferation and cytotoxicity in vitro and had enhanced proliferative and in vivo antitumor activity compared with FMC63 CAR T cells. In a clinical study (CARPALL, NCT02443831 ), 12/14 patients with relapsed/refractory pediatric B cell acute lymphoblastic leukemia treated with CAT CAR T cells achieved molecular remission. Persistence was demonstrated in 11 of 14 patients at last follow-up, with enhanced CAR T cell expansion compared with published data. Toxicity was low, with no severe CRS. One-year overall and event-free survival were 63% and 46%, respectively. New low-affinity anti-CD19 CAR T cells exhibit peripheral expansion and persistence without inducing severe cytokine-response syndrome in pediatric patients with relapsed or refractory B cell acute lymphoblastic leukemia.

Chimeric antigen receptor (CAR) T cells targeting CD19 or CD22 have shown remarkable activity in B cell acute lymphoblastic leukemia (B-ALL). The major cause of treatment failure is antigen downregulation or loss. Dual antigen targeting could potentially prevent this, but the clinical safety and efficacy of CAR T cells targeting both CD19 and CD22 remain unclear. We conducted a phase 1 trial in pediatric and young adult patients with relapsed or refractory B-ALL ( n  = 15) to test AUTO3, autologous transduced T cells expressing both anti-CD19 and anti-CD22 CARs (AMELIA trial, EUDRA CT 2016-004680-39). The primary endpoints were the incidence of grade 3–5 toxicity in the dose-limiting toxicity period and the frequency of dose-limiting toxicities. Secondary endpoints included the rate of morphological remission (complete response or complete response with incomplete bone marrow recovery) with minimal residual disease-negative response, as well as the frequency and severity of adverse events, expansion and persistence of AUTO3, duration of B cell aplasia, and overall and event-free survival. The study endpoints were met. AUTO3 showed a favorable safety profile, with no dose-limiting toxicities or cases of AUTO3-related severe cytokine release syndrome or neurotoxicity reported. At 1 month after treatment the remission rate (that is, complete response or complete response with incomplete bone marrow recovery) was 86% (13 of 15 patients). The 1 year overall and event-free survival rates were 60% and 32%, respectively. Relapses were probably due to limited long-term AUTO3 persistence. Strategies to improve CAR T cell persistence are needed to fully realize the potential of dual targeting CAR T cell therapy in B-ALL. Bicistronic CAR T cells targeting CD19 and CD22 exhibit clinical activity and low toxicity in pediatric and young adult patients with B cell acute lymphoblastic leukemia, with relapses associated with limited CAR T cell persistence.

BackgroundFanconi anaemia (FA) is an inherited disease with bone marrow failure, variable congenital and developmental abnormalities, and cancer predisposition. With improved survival, non-haematological manifestations of FA become increasingly important for long-term management. While renal abnormalities are recognized, detailed data on patterns and frequency and implications for long-term management are sparse.MethodsWe reviewed clinical course and imaging findings of FA patients with respect to renal complications in our centre over a 25-year period to formulate some practical suggestions for guidelines for management of renal problems associated with FA.ResultsThirty patients including four sibling sets were reviewed. On imaging, 14 had evidence of anatomical abnormalities of the kidneys. Two cases with severe phenotype, including renal abnormalities, had chronic kidney disease (CKD) at diagnosis. Haematopoietic stem cell transplantation was complicated by significant acute kidney injury (AKI) in three cases. In three patients, there was CKD at long-term follow-up. All patients had normal blood pressure.ConclusionsEvaluation of renal anatomy with ultrasound imaging is important at diagnostic workup of FA. While CKD is uncommon at diagnosis, our data suggests that the incidence of CKD increases with age, in particular after haematopoietic stem cell transplantation. Monitoring of renal function is essential for management of FA. Based on these long-term clinical observations, we formulate some practical guidelines for assessment and management of renal abnormalities in FA.