The role of graft T-cell size in patients receiving alemtuzumab serotherapy for non-malignant disorders: results of an institutional protocol.

Although graft T cells assist in engraftment, mediate antiviral immune-reconstitution, and cause graft-versus-host disease, graft size is not determined by T-cell content of the graft. The conventional method of graft size determination based on CD34+ cells with alemtuzumab serotherapy is associated with delayed immune reconstitution, contributing to an increased risk of viral infections and graft failure. Alemtuzumab, a long half-life anti-CD52 monoclonal antibody is a robust T-cell depleting serotherapy, and relatively spares memory-effector T cells compared to naïve T cells. We therefore hypothesized that graft size based on T-cell content in patients receiving peripheral blood stem cell graft with alemtuzumab serotherapy would facilitate immune-reconstitution without increasing the risk of graft-versus-host disease. We retrospectively analysed twenty-six consecutive patients with non-malignant disorders grafted using alemtuzumab serotherapy and capping of graft T cells to a maximum of 600 million/kg. The graft T-cell capping protocol resulted in early immune-reconstitution without increasing the risk of severe graft-versus-host disease. Graft T-cell content correlated with CD4+ T-cell reconstitution and acute graft-versus-host disease. The course of CMV viraemia was predictable without recurrence and associated with early T-cell recovery. No patient developed chronic graft-versus-host disease. Overall survival at one year was 100% and disease-free survival was 96% at a median of 899 days (range: 243-1562). Graft size determined by peripheral blood stem cell graft T-cell content in patients receiving alemtuzumab serotherapy for non-malignant disorders is safe and leads to early T-cell immune-reconstitution with excellent survival outcomes.

Reduced toxicity conditioning and a high CD34+ cell dose can achieve full donor chimerism in DOCK8 deficiency.

Background: Biallelic mutations in the dedicator of cytokinesis 8 (DOCK8) gene were identified as the cause of combined immunodeficiency in 2009. Survival rates without hematopoietic stem cell transplant in patients with DOCK8 deficiency decline from 87% at 10 years to 33% at 30 years. Hematopoietic stem cell transplant is therefore the recommended treatment for cure of DOCK8 deficiency. However, patients with DOCK8 deficiency have multiple infectious comorbidities; hence, they cannot tolerate myeloablative conditioning. Reduced intensity conditioning reduces the risk of transplant-related mortality but increases the possibility of mixed chimerism. Mixed chimerism in children with immunodeficiency increases the risk of autoimmunity and the need for long-term immunoglobulin infusion. Objective: Here we have sought to devise a strategy for reducing the possibility of mixed chimerism without increasing the risk of transplant-related mortality. Methods: To balance the risk of transplant-related mortality and mixed chimerism, we used treosulfan-based reduced toxicity conditioning with a high CD34+ cell dose and differential T-cell capping for HLA-matched and haploidentical transplants. Results: We are able to report that by using the aforementioned novel strategy, we achieved excellent transplant outcomes in the first cohort of high-risk patients with DOCK8 deficiency from India. Conclusion: High CD34+ cell dose and reduced toxicity conditioning can achieve full donor chimerism in DOCK8 deficiency.

Changing outcomes of stem cell transplantation in primary immunodeficiencies: Results from a tertiary-care charitable trust hospital in Mumbai.

Background: Hematopoietic stem cell transplantation in primary immunodeficiency disorders has come a long way since the first transplant in 1968. In India, pediatric stem cell transplantation long-term survival outcomes range from 62.5% to 75%, compared to 90% in high-income countries. Objective: We present single-center data of primary immunodeficiency transplants with immune-reconstitution evaluation after transplantation from a charitable trust hospital. Methods: Retrospective data of children transplanted for primary immunodeficiency disorders from March 2019 to March 2022 in a newly established transplant unit were collected. Data of pretransplant infections and comorbidities, surveillance for carbapenem-resistant Enterobacteriaceae, transplant characteristics, donor source, graft-versus-host disease, posttransplant infections, immune reconstitution, overall survival at 1 year, and immunodeficiency-free survival were collated. Results: Twenty-one patients underwent transplantation for primary immunodeficiency disorders. The median age at transplantation was 3 years and 5 months (range, 7 months to 17 years). Seventy-five percent of the cohort had organ involvement, with lung being the most common organ involved, followed by central nervous system. Fifty-two percent of children had peritransplant infections, with most of them recognized at the pretransplant assessment. Among 20 of 21 children with engraftment, 94% had complete chimerism initially, with 33% developing mixed chimerism over time. The median duration of immunosuppression was 3 months after transplantation, and only 1 child required systemic graft-versus-host disease treatment for more than a year. Immune-reconstitution showed good T-cell recovery at 3 months and naive T-cell production at 6 months. There was no regimen-related or sepsis-related mortality. Overall survival of the cohort was 95% at 1-year follow-up. Immunodeficiency-free survival was 86% after a median follow-up of 20 months. Conclusions: Immunodeficiency-free and graft-versus-host disease-free survival can be achieved in the majority of children with primary immunodeficiencies using enhanced supportive care and the latest transplantation algorithms.

Narsoplimab for severe transplant-associated thrombotic microangiopathy.

BACKGROUND: Transplantation-associated thrombotic microangiopathy (TA-TMA) is an endothelial injury syndrome linked to the overactivation of complement pathways. It manifests with microangiopathic hemolytic anemia, consumptive thrombocytopenia, and microvascular thrombosis leading to ischemic tissue injury. Mannose residues on fungi and viruses activate the mannose-binding lectin complement pathway, and hence activation of the lectin pathway could be one of the reasons for triggering TA-TMA. Narsoplimab, a human monoclonal antibody targeting MASP-2 is a potent inhibitor of the lectin pathway. We describe the transplant course of a pediatric patient who developed TA-TMA following Candida-triggered macrophage activation syndrome and was treated with Narsoplimab. The data collection was performed prospectively. CASE PRESENTATION: The six-year-old girl underwent a human leucocyte antigen (HLA) haploidentical hematopoietic stem cell transplant using post-transplant Cyclophosphamide for severe aplastic anemia. In the second week of the transplant, the patient developed macrophage activation syndrome necessitating treatment with steroids and intravenous immunoglobulin. Subsequently, USG abdomen and blood fungal PCR revealed the diagnosis of hepatosplenic candidiasis. Candida-triggered macrophage activation syndrome responded to antifungals, steroids, intravenous immunoglobulin, and alemtuzumab. However, the subsequent clinical course was complicated by thrombotic microangiopathy. The patient developed hypertension in the 2nd week, followed by high lactate dehydrogenase (1010 U/L), schistocytes (5 per hpf), low haptoglobin (< 5 mg/dl), thrombocytopenia, and anemia in the 3rd week. Ciclosporin was stopped, and the patient was treated with 10 days of defibrotide without response. The course was further complicated by the involvement of the gastrointestinal tract and kidneys. She had per rectal bleeding with frequent but low-volume stools, severe abdominal pain, and hypoalbuminemia with a rising urine protein:creatinine ratio. Narsoplimab was started in the 5th week of the transplant. A fall in lactate dehydrogenase was observed after starting Narsoplimab. This was followed by the resolution of gastrointestinal symptoms, proteinuria, and recovery of cytopenia. The second episode of TA-TMA occurred with parvoviraemia and was also successfully treated with Narsoplimab. CONCLUSION: Lectin pathway inhibition could be useful in treating the fatal complication of transplant-associated thrombotic microangiopathy.

SLGT2 Inhibitor Rescues Myelopoiesis in G6PC3 Deficiency.

The energy metabolism of myeloid cells depends primarily on glycolysis. 1,5-Anhydroglucitol (1,5AG), a natural monosaccharide, is erroneously phosphorylated by glucose-phosphorylating enzymes to produce 1,5-anhydroglucitol-6-phosphate (1,5AG6P), a powerful inhibitor of hexokinases. The endoplasmic reticulum transporter (SLC37A4/G6PT) and the phosphatase G6PC3 cooperate to dephosphorylate 1,5AG6P. Failure to eliminate 1,5AG6P is the mechanism of neutrophil dysfunction and death in G6PC3-deficient mice. Sodium glucose cotransporter 2 (SLGT2) inhibitor reduces 1,5AG level in the blood and restores the neutrophil count in G6PC3-deficient mice. In the investigator-initiated study, a 30-year-old G6PC3-deficient woman with recurrent infections, distressing gastrointestinal symptoms, and multi-lineage cytopenia was treated with an SLGT2-inhibitor. A significant increase in all the hematopoietic cell lineages and substantial improvement in the quality of life was observed.

Cord blood CD8+ T-cell expansion following granulocyte transfusions eradicates refractory leukemia.

The action of hematopoietic cell transplantation in controlling leukemia is principally mediated by donor T cells directed against residual recipient malignant cells. However, its utility is limited by graft-versus-host disease (GVHD), where alloreactivity is extended beyond leukemic and marrow cells. In a human/murine chimeric model, we previously showed that the preferential infiltration of cord blood (CB) CD8+ T cells eradicates an Epstein-Barr virus-driven lymphoblastoid tumor without causing xenogeneic GVHD. In the clinic, however, cord blood CD8+ T-cell reconstitution is significantly delayed, and the observation of such a robust antileukemia effect mediated by cord blood CD8+ T cells has not been reported. We describe an observation of very early T-cell expansion in 4 high-risk pediatric leukemia patients receiving third-party, pooled granulocytes after T cell-replete CB transplantation (CBT). The T-cell expansion was transient but robust, including expansion of CD8+ T cells, in contrast to the delayed CD8+ T-cell expansion ordinarily observed after T cell-replete CBT. The CD8+ T cells were polyclonal, rapidly switched to memory phenotype, and had the ability to mediate cytotoxicity. This phenomenon is reproducible, and each patient remains in long-term remission without GVHD. The results suggest that fetal-derived CB CD8+ T cells can be exploited to generate robust antileukemia effects without GVHD.

Burden of adenoviraemia predicts survival in paediatric recipients of allogeneic haematopoietic stem cell transplant.

BACKGROUND: Adenoviraemia occurs in 15 to 30% of paediatric allogeneic haematopoietic stem cell transplant (HSCT) recipients, and is a significant cause of morbidity and mortality which lacks satisfactory therapeutic options. The relationship between burden of adenovirus and mortality is poorly defined in this patient group. OBJECTIVES: To determine the relationship between adenoviraemia and mortality in paediatric HSCT recipients. STUDY DESIGN: A retrospective review of blood adenovirus PCR results in paediatric HSCT recipients spanning February 2003 to September 2016 was conducted. Three measures of adenovirus burden were defined; number of days with significant viraemia, peak adenovirus load and Area under the Curve and related to outcome post-HSCT. RESULTS: A total of 62 patients with episodes of positive blood adenovirus PCR were identified for analysis. Adenoviraemia of more than 7 days, peak viral load of >8000 copies/ml and higher 16 week Area under the Curve were all significantly associated with higher non-relapse mortality in paediatric HSCT recipients. CONCLUSIONS: This retrospective analysis highlights the important predictive value of adenoviral load for non-relapse mortality in young allogeneic HSCT recipients. These data also suggest a possible role for use of these measures as end points in trials of novel adenoviral therapies.

Immune cytopenia post-cord transplant in Hurler syndrome is a forme fruste of graft rejection.

Umbilical cord blood (UCB) is the preferred donor cell source for children with Hurler syndrome undergoing transplant, and its use has been associated with improved "engrafted survival" rates. However, as in other pediatric recipients of UCB transplants for nonmalignant disease, immune-mediated cytopenia (IMC) is a significant complication. This article describes 8 episodes of IMC in 36 patients with Hurler syndrome undergoing UCB transplant. The incidence of IMC was increased in those with a higher preconditioning absolute lymphocyte count and in those conditioned with fludarabine-containing regimens rather than cyclophosphamide, and it included red cell alloantibodies directed at cord blood group antigens that are novel to the recipient. In several cases, IMC was a precursor to immune-mediated complete graft rejection. We describe IMC as part of a spectrum of graft rejection by a residual competent host immune system and a forme fruste of complete graft rejection.

Report of Resistant Varicella Zoster Infection Treated With Donor Lymphocyte Infusion in a Pediatric Oncology Patient.

We report an 8-year-old boy with disseminated, life-threatening, drug treatment-resistant varicella zoster infection occurring during standard treatment for neuroblastoma in whom viral clearance and cure was effected by donor Lymphocyte infusion from his HLA (Human leukocyte antigen)-identical twin sibling.

A decade of excellent transplant survival in children with inherited metabolic diseases: A report from a single metabolic transplant centre in Europe.

Hematopoietic cell transplantation (HCT) confers a long-term disease-modifying therapy for transplant-permissive inherited metabolic diseases (IMDs). We examined the overall survival (OS) and engrafted survival (ES) of children with IMDs, who received first HCT at Royal Manchester Children's hospital from 1985 to 2016. A total of 137 children with IMDs were included in this analysis (historical cohort [1985-2006], n＝65; current cohort [2007-2016], n＝72). Primary diagnoses included mucopolysaccharidoses (81%), X-linked adrenoleukodystrophy (6%), metachromatic leukodystrophy (4%), mannosidosis (3%), Wolman disease (2%), and other conditions (4%). The five-year OS has increased from 65% (95% confidence interval [CI], 52%-76%) in the historical cohort to 91% (95% CI, 81%-96%) in the current cohort (P<0.001). Moreover, the five-year ES, which was 64% (95 CI%, 56%-72%) for the entire cohort, has doubled from 41% (95% CI, 29%-53%) in the historical cohort to 85% (95% CI, 75%-92%) in the current cohort (P<0.001). The proportion of patients with graft failure has decreased from 37% in the historical cohort to 8% in the current cohort (P<0.001). In patients who received a second transplant, 13 out of 20 patients (65%) in the historical cohort and all four in the current cohort were alive and engrafted. Of 82 survivors followed-up at Manchester, 80% and 20% had full and mixed chimerism, respectively. Although this study was restricted to a single center, our findings show that HCT is an increasingly safe procedure and provides long-lasting endogenous enzyme replacement therapy for children with IMDs in the modern era of HCT.

Molecular monitoring of adenovirus reactivation in faeces after haematopoietic stem-cell transplantation to predict systemic infection: a retrospective cohort study.

BACKGROUND: Faecal shedding of adenovirus following allogeneic haematopoietic stem-cell transplantation (HSCT) is an early sign of loss of immune control over adenovirus, but there is no consensus on the role of monitoring of faecal adenoviral load by serial testing. We investigated whether serial faecal PCR monitoring could predict the risk of adenoviraemia and survival outcomes after HSCT. METHODS: We did a retrospective cohort study at the Royal Manchester Children's Hospital, Manchester, UK, of patients who had received their first allogeneic HSCT between Feb 1, 2003, and Sept 1, 2016, and adenovirus infection recorded in their medical records. We excluded patients who had received second or third transplants or autologous HSCT transplants. We obtained characteristics of patients and transplants, including mortality and adenoviral reactivation, from medical records and the hospital database. All patients had blood samples tested weekly for adenovirus by PCR until immunosuppression was stopped and CD3 T-cell count recovered to greater than 0·3 × 109/L. Faecal PCR was done before transplantation in all patients, and after transplantation in patients who had diarrhoea, at the onset of symptoms and weekly thereafter until diarrhoea resolved. We analysed all samples available before and after HSCT. We did subgroup analyses for patients undergoing HSCT for cancer versus non-malignant conditions. We also assessed whether 5 log10 copies per g faeces was a suitable predictive threshold for adenoviraemia. FINDINGS: We included 341 patients who had undergone a first allogeneic HSCT (median age 4·6 years, IQR 1·5-8·0, range 0-20·0). After HSCT, PCR was done in 4116 faecal samples from 293 (86%) patients who had diarrhoea and in 10 649 blood samples from 341 patients. Follow-up ended on July 14, 2017. 173 (59%) of 293 patients had adenovirus in faecal samples and 63 (18%) of 341 had adenovirus in blood samples. Maximum faecal viral load before adenoviraemia correlated significantly with maximum blood viral load (r=0·51, 95% CI 0·38-0·61, p<0·0001). Faecal adenoviral viral load greater than 5 log10 copies per g faeces was predictive of adenoviraemia (odds ratio 10·2, 95% CI 4·9-21·6, p<0·0001) with sensitivity 75·9% and specificity 74·8%. These values were increased further in patients with cancer, to 86·4% and 87·5%, respectively. Among the 28 patients who had positive faecal and blood samples and who had undergone serial faecal PCR monitoring after HSCT, the median time between reaching the faecal viral load threshold and onset of adenoviraemia was 8·0 days (IQR 2·3-21·8, 95% CI 4·0-16·0). Non-relapse mortality was not associated with adenovirus reactivation in faeces alone (9·2%, 95% CI 5·4-14·3 in patients without reactivation vs 7·8%, 3·8-13·7 in those with positive faeces only), but was significantly increased in patients who developed adenoviraemia (27·0%, 95% CI 16·7-38·4, p<0·0001). INTERPRETATION: We identified a threshold faecal viral load that can predict the risk of adenoviraemia. Our findings support proliferation of adenovirus in the gastrointestinal tract before viraemia develops. Faecal PCR is suitable for early detection of children and young adults at risk of adenoviraemia, and its use might help reduce non-relapse mortality in allogeneic HSCT recipients. FUNDING: None.

Management of adenovirus infection in patients after haematopoietic stem cell transplantation: State-of-the-art and real-life current approach: A position statement on behalf of the Infectious Diseases Working Party of the European Society of Blood and Marrow Transplantation.

The important insights gained over the past years in diagnosis and treatment of invasive adenoviral infections provide new paradigms for the monitoring and clinical management of these life-threatening complications. A meeting was held to discuss and subsequently disseminate the current advances in our understanding of the aetiology/pathogenesis and future treatment options facilitating effective control or prevention of adenovirus-related diseases in the allogeneic haematopoietic stem cell transplant setting. Invited experts in the field discussed recent progress with leading members of the Infectious Diseases Working Party of the European Society of Blood and Marrow Transplantation at the "State-of-the-art" Meeting in Poznan, Poland, in October 2017. In this review article, the panel of experts presents a concise summary of the current evidence based on published data from the last 15 years and on recent achievements resulting from real-life practice. The present position statement reflects an expert opinion on current approaches to clinical management of adenovirus infections in patients undergoing allogeneic haematopoietic stem cell transplant and provides graded recommendations of the panel for diagnostic approaches and preemptive therapy reflecting the present state of knowledge.

High transplant-related mortality associated with haematopoietic stem cell transplantation for paediatric therapy-related acute myeloid leukaemia (t-AML). A study on behalf of the United Kingdom Paediatric Blood and Bone Marrow Transplant Group.

Paediatric therapy-related acute myeloid leukaemia (t-AML) is rare and the outcome is poor. While allogeneic haematopoietic stem cell transplantation (HSCT) is generally the accepted modality of treatment, data regarding salvage chemotherapy, remission induction, conditioning regimens, transplant-related mortality and outcome is scarce. Between 2000 and2016, 36 children with t-AML were treated in seven UK paediatric HSCT centres. The most common salvage protocol for remission induction was FLAG with or without idarubicin and 28 patients were in complete morphological remission prior to BMT. Only 12 patients survived (33%). Transplant-related mortality (TRM) was the leading cause of death.

Brincidofovir is highly efficacious in controlling adenoviremia in pediatric recipients of hematopoietic cell transplant.

Cidofovir is preemptively used for controlling adenoviremia and preventing disseminated viral disease in hematopoietic cell transplant (HCT) recipients but does not lead to resolution of viremia without T-cell immune-reconstitution. The lipid-conjugated prodrug of cidofovir, brincidofovir, has improved oral bioavailability and achieves higher intracellular concentrations of active drug. We present retrospective multicenter data comparing the kinetics of viremia and toxicities following preemptive treatment with and brincidofovir in children and adolescents diagnosed with HCT-related adenoviremia. Forty-one episodes (18 = brincidofovir; 23 = cidofovir) of antiviral therapy were observed in 27 patients. The 2 groups had comparable immune-reconstitution and viral burden. Major (≥2 log-reduction in 2 weeks; n = 13) and minor (≥1 to ≤2 log-reduction in 2 weeks; n = 2) virological responses were observed in 15 (83%) brincidofovir episodes compared to only 2 (9%) major virological responses with cidofovir (P < .0001). Brincidofovir mediated major responses in 9 of 11 cidofovir-unresponsive patients and resulted in complete responses (CR) despite significant lymphopenia (Brincidofovir vs cidofovir; CR = 13 (80%) vs 8 (35%); median lymphocyte count = 320/µl vs 910/µl; P < .05). One patient experienced abdominal cramps and diarrhea necessitating interruption of brincidofovir and none developed nephrotoxicity with brincidofovir. Thus, brincidofovir is well-tolerated and highly efficacious in controlling adenoviremia during the lymphopenic phase of HCT.