The impact of levofloxacin prophylaxis on empiric intravenous antibiotic use in pediatric hematopoietic stem cell transplant recipients.

Levofloxacin prophylaxis during periods of neutropenia in pediatric hematopoietic stem cell transplant (HSCT) may reduce the number of febrile episodes and use of empiric intravenous antibiotics (EIA); however, the literature is conflicting. This retrospective review compared EIA use before and after implementation of levofloxacin prophylaxis at a children's hospital. Levofloxacin prophylaxis was associated with reduced use of certain EIA; however, did not reduce the number of positive blood cultures or clinical deteriorations. Therefore, levofloxacin prophylaxis may have implications for the stewardship of broad-spectrum intravenous antibiotics used in pediatric HSCT.

Exagamglogene Autotemcel for Transfusion-Dependent ß-Thalassemia.

BACKGROUND: Exagamglogene autotemcel (exa-cel) is a nonviral cell therapy designed to reactivate fetal hemoglobin synthesis through ex vivo clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 gene editing of the erythroid-specific enhancer region of BCL11A in autologous CD34+ hematopoietic stem and progenitor cells (HSPCs). METHODS: We conducted an open-label, single-group, phase 3 study of exa-cel in patients 12 to 35 years of age with transfusion-dependent ß-thalassemia and a ß0/ß0, ß0/ß0-like, or non-ß0/ß0-like genotype. CD34+ HSPCs were edited by means of CRISPR-Cas9 with a guide mRNA. Before the exa-cel infusion, patients underwent myeloablative conditioning with pharmacokinetically dose-adjusted busulfan. The primary end point was transfusion independence, defined as a weighted average hemoglobin level of 9 g per deciliter or higher without red-cell transfusion for at least 12 consecutive months. Total and fetal hemoglobin concentrations and safety were also assessed. RESULTS: A total of 52 patients with transfusion-dependent ß-thalassemia received exa-cel and were included in this prespecified interim analysis; the median follow-up was 20.4 months (range, 2.1 to 48.1). Neutrophils and platelets engrafted in each patient. Among the 35 patients with sufficient follow-up data for evaluation, transfusion independence occurred in 32 (91%; 95% confidence interval, 77 to 98; P<0.001 against the null hypothesis of a 50% response). During transfusion independence, the mean total hemoglobin level was 13.1 g per deciliter and the mean fetal hemoglobin level was 11.9 g per deciliter, and fetal hemoglobin had a pancellular distribution (≥94% of red cells). The safety profile of exa-cel was generally consistent with that of myeloablative busulfan conditioning and autologous HSPC transplantation. No deaths or cancers occurred. CONCLUSIONS: Treatment with exa-cel, preceded by myeloablation, resulted in transfusion independence in 91% of patients with transfusion-dependent ß-thalassemia. (Supported by Vertex Pharmaceuticals and CRISPR Therapeutics; CLIMB THAL-111 ClinicalTrials.gov number, NCT03655678.).

Exagamglogene Autotemcel for Severe Sickle Cell Disease.

BACKGROUND: Exagamglogene autotemcel (exa-cel) is a nonviral cell therapy designed to reactivate fetal hemoglobin synthesis by means of ex vivo clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 gene editing of autologous CD34+ hematopoietic stem and progenitor cells (HSPCs) at the erythroid-specific enhancer region of BCL11A. METHODS: We conducted a phase 3, single-group, open-label study of exa-cel in patients 12 to 35 years of age with sickle cell disease who had had at least two severe vaso-occlusive crises in each of the 2 years before screening. CD34+ HSPCs were edited with the use of CRISPR-Cas9. Before the exa-cel infusion, patients underwent myeloablative conditioning with pharmacokinetically dose-adjusted busulfan. The primary end point was freedom from severe vaso-occlusive crises for at least 12 consecutive months. A key secondary end point was freedom from inpatient hospitalization for severe vaso-occlusive crises for at least 12 consecutive months. The safety of exa-cel was also assessed. RESULTS: A total of 44 patients received exa-cel, and the median follow-up was 19.3 months (range, 0.8 to 48.1). Neutrophils and platelets engrafted in each patient. Of the 30 patients who had sufficient follow-up to be evaluated, 29 (97%; 95% confidence interval [CI], 83 to 100) were free from vaso-occlusive crises for at least 12 consecutive months, and all 30 (100%; 95% CI, 88 to 100) were free from hospitalizations for vaso-occlusive crises for at least 12 consecutive months (P<0.001 for both comparisons against the null hypothesis of a 50% response). The safety profile of exa-cel was generally consistent with that of myeloablative busulfan conditioning and autologous HSPC transplantation. No cancers occurred. CONCLUSIONS: Treatment with exa-cel eliminated vaso-occlusive crises in 97% of patients with sickle cell disease for a period of 12 months or more. (CLIMB SCD-121; ClinicalTrials.gov number, NCT03745287.).

Gut Immunomodulation with Vedolizumab prior to Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Patients with Inflammatory Bowel Disease.

Inborn errors of immunity (IEI) are often associated with inflammatory bowel disease (IBD). IEI can be corrected by allogeneic hematopoietic stem cell transplantation (HSCT); however, peritransplantation intestinal inflammation may increase the risk of gut graft-versus-host disease (GVHD). Vedolizumab inhibits the homing of lymphocytes to the intestine and may attenuate gut GVHD, yet its role in preventing GVHD in pediatric patients with IEI-associated IBD has not been studied. Here we describe a cohort of pediatric patients with IEI-associated IBD treated with vedolizumab before and during allogeneic HSCT. The study involved a retrospective chart review of pediatric patients with IEI-associated IBD treated with vedolizumab at 6 weeks, 4 weeks, and 1 week before undergoing HSCT. The conditioning regimen consisted of treosulfan, fludarabine, and cyclophosphamide with rabbit antithymocyte globulin, and GVHD prophylaxis included tacrolimus and steroids. Eleven patients (6 females) with a median age of 5 years (range, 0.4 to 14 years) with diverse IEI were included. IBD symptoms were characterized by abdominal pain, loose stools, and blood in stools. Four patients had developed a perianal fistula, and 1 patient had a rectal prolapse. One patient had both a gastrostomy tube and a jejunal tube in situ. Treatment of IBD before HSCT included steroids in 11 patients, anakinra in 2, infliximab in 4, sulfasalazine in 2, mesalazine in 2, and vedolizumab. IBD symptoms were considered controlled in the absence of abdominal pain, loose stools, or blood in stools. Graft sources for HSCT were unrelated donor cord in 5 patients (2 with a 5/8 HLA match, 2 with a 7/8 match, and 1 with a 6/8 match), peripheral blood stem cells in 5 patients (2 haploidentical, 1 with a 9/10 HLA match, and 2 with a 10/10 match), and bone marrow in 1 patient (10/10 matched sibling donor). The median number of vedolizumab infusions was 4 (range, 3 to 12) before HSCT and 1 (range, 1 to 3) after HSCT, and all were reported to be uneventful. All patients had engrafted. Acute GVHD occurred in 4 patients and was limited to grade I skin GVHD only. Chronic GVHD occurred in 1 patient and again was limited to the skin. There was no gut GVHD. Three patients experienced cytomegalovirus viremia, and 2 patients had Epstein-Barr virus viremia. At the time of this report, all patients were alive with no evidence of IBD at a median follow-up of 15 months (range, 3 to 39 months). Administration of vedolizumab pre- and post-HSCT in pediatric patients with IEI-associated IBD is well tolerated and associated with a low rate of gut GVHD. These findings provide a platform for the prospective study and use of vedolizumab for GVHD prophylaxis in pediatric patients with known intestinal inflammation as a pre-HSCT comorbidity.

Part 5: Allogeneic HSCT in refractory SJIA with lung disease; recent cases from centers in North America & Europe.

It has been increasingly recognized that there is a subset of patients with refractory systemic JIA, who have failed all available medications and may benefit from HSCT. The increasing experience with HSCT in SJIA, suggests that despite the complicated post-HSCT course, short-term, the transplanted patients either achieved SJIA remission or reduced burden of disease. Longer follow-up, however, is needed to better define the long-term outcomes. The discussion at the NextGen 2022 conference was focused on the optimal timing for the procedure, the need for a good control of inflammatory SJIA activity prior to HSCT, and the role of the reduced intensity conditioning regimens as there was a remote concern that such regimens might increase the risk of SJIA relapse after the transplantation. There was unanimous agreement about the importance of long-term registries to address these questions.

Intractable abdominal pain as the sole symptom of Varicella Zoster reactivation after allogeneic stem cell transplantation: brief case report and review of the literature.

After primary infection, Varicella Zoster (VZV) persists in sensory dorsal root ganglia and may be reactivated in periods of diminished T-cell immunity. Varicella Zoster reactivation post allogenic stem cell transplantation (HSCT) can be challenging to diagnose as it does not always present with characteristic skin lesions. We describe a pediatric patient who presented with isolated severe abdominal pain with no other symptoms. Cutaneous lesions appeared only 10 days later resulting in delayed diagnosis and treatment. He was successfully treated with intravenous acyclovir and recovered after a prolonged hospital stay with post-herpetic neuralgia. Abdominal pain in children post HSCT has a broad differential and VZV reactivation should be considered even in absence of cutaneous lesions. Early diagnosis and treatment are essential to reduce VZV-related morbidity and mortality. In this article we present a case report and review clinical presentation and outcome of similar cases in the literature.

Children's Oncology Group's 2023 blueprint for research: Cellular therapy and stem cell transplantation.

Since the publication of the last Cellular Therapy and Stem Cell Transplant blueprint in 2013, Children's Oncology Group cellular therapy-based trials advanced the field and created new standards of care across a wide spectrum of pediatric cancer diagnoses. Key findings include that tandem autologous transplant improved survival for patients with neuroblastoma and atypical teratoid/rhabdoid brain tumors, one umbilical cord blood (UCB) donor was safer than two UCB donors, killer immunoglobulin receptor (KIR) mismatched donors did not improve survival for pediatric acute myeloid leukemia when in vivo T-cell depletion is used, and the depth of remission as measured by next-generation sequencing-based minimal residual disease assessment pretransplant was the best predictor of relapse for acute lymphoblastic leukemia. Plans for the next decade include optimizing donor selection for transplants for acute leukemia/myelodysplastic syndrome, using novel engineered cellular therapies to target a wide array of malignancies, and developing better treatments for cellular therapy toxicities such as viral infections and graft-vs-host disease.

Effect of Autograft CD34+ Dose on Outcome in Pediatric Patients Undergoing Autologous Hematopoietic Stem Cell Transplant for Central Nervous System Tumors.

Consolidation with autologous hematopoietic stem cell transplantation (HSCT) has improved survival for patients with central nervous system tumors (CNSTs). The impact of the autologous graft CD34+ dose on patient outcomes is unknown. We wanted to analyze the relationship between CD34+ dose, total nucleated cell (TNC) dose, and clinical outcomes, including overall survival (OS), progression-free survival (PFS), relapse, non-relapse mortality (NRM), endothelial-injury complications (EIC), and time to neutrophil engraftment in children undergoing autologous HSCT for CNSTs. A retrospective analysis of the CIBMTR database was performed. Children aged <10 years who underwent autologous HSCT between 2008 to 2018 for an indication of CNST were included. An optimal cut point was identified for patient age, CD34+ cell dose, and TNC, using the maximum likelihood method and PFS as an endpoint. Univariable analysis for PFS, OS, and relapse was described using the Kaplan-Meier estimator. Cox models were fitted for PFS and OS outcomes. Cause-specific hazards models were fitted for relapse and NRM. One hundred fifteen patients met the inclusion criteria. A statistically significant association was identified between autograft CD34+ content and clinical outcomes. Children receiving >3.6×106/kg CD34+ cells experienced superior PFS (p = .04) and OS (p = .04) compared to children receiving ≤3.6 × 106/kg. Relapse rates were lower in patients receiving >3.6 × 106/kg CD34+ cells (p = .05). Higher CD34+ doses were not associated with increased NRM (p = .59). Stratification of CD34+ dose by quartile did not reveal any statistically significant differences between quartiles for 3-year PFS (p = .66), OS (p = .29), risk of relapse (p = .57), or EIC (p = .87). There were no significant differences in patient outcomes based on TNC, and those receiving a TNC >4.4 × 108/kg did not experience superior PFS (p = .26), superior OS (p = .14), reduced risk of relapse (p = .37), or reduced NRM (p = .25). Children with medulloblastoma had superior PFS (p < .001), OS (p = .01), and relapse rates (p = .001) compared to those with other CNS tumor types. Median time to neutrophil engraftment was 10 days versus 12 days in the highest and lowest infused CD34+ quartiles, respectively. For children undergoing autologous HSCT for CNSTs, increasing CD34+ cell dose was associated with significantly improved OS and PFS, and lower relapse rates, without increased NRM or EICs.

Abatacept-based Graft-Versus-Host Disease Prophylaxis in Haplo-identical Hematopoietic Cell Transplant in a High-risk Cohort.

BACKGROUND: There is insufficient guidance in using posttransplant cyclophosphamide in patients with organ dysfunctions. Abatacept (Aba), a T cell costimulation blockade, has recently been shown to prevent severe acute graft-versus-host disease (GVHD). OBSERVATION: We report adding Aba as GVHD prophylaxis in 4 pediatrics patients who received haplo-hematopoietic cell transplantation. Two patients had grade 2 acute GVHD and 2 had mild chronic GVHD. All 4 patients are alive with full donor chimerism, and 3 are off immunosuppressants. CONCLUSION: An Aba-based regimen can result in reliable engraftment and acceptable GVHD when concerns of organ dysfunction prevents the use of posttransplant cyclophosphamide in haplo-hematopoietic cell transplantation.

Outcome of Haploidentical Peripheral Blood Allografts Using Post-Transplantation Cyclophosphamide Compared to Matched Sibling and Unrelated Donor Bone Marrow Allografts in Pediatric Patients with Hematologic Malignancies: A Single-Center Analysis.

The introduction of post-transplantation cyclophosphamide (PTCy) as graft-versus-host disease (GVHD) prophylaxis has made haploidentical (haplo) hematopoietic stem cell transplantation (HSCT) a common approach in adults, but pediatric experience is limited. Based on the encouraging adult data and with the aim of decreasing the risk of graft failure, our center is increasingly using peripheral blood stem cells (PBSCs) from haplo donors with PTCy. Here we compare outcomes of bone marrow (BM) transplantation with traditional donor choices, including matched sibling donors (MSDs) and 10/10 HLA matched unrelated donors (MUDs), with those of haplo PBSC grafts in pediatric patients with hematologic malignancies. In this retrospective single-center study, the primary endpoint was the comparison of GVHD-free relapse-free survival (GRFS; defined as absence of acute GVHD [aGVHD] grade III-IV, relapse, death, or chronic GVHD [cGVHD] requiring systemic therapy) for the 3 cohorts. Secondary endpoints included overall survival (OS), relapse-free survival (RFS), nonrelapse mortality (NRM), and incidence of aGVHD and cGVHD). A total of 104 consecutive patients underwent first allogeneic (allo)-HSCT for a hematologic malignancy or myelodysplastic syndrome between January 2014 and December 2020 using a haplo family donor (PBSCs; n = 26), an MSD (BM; n = 31), or an MUD (BM; n = 47). Patient demographic and transplantation characteristics were not significantly different across the cohorts, apart from remission status, with the haplo cohort having more patients in third or later complete remission before HSCT (P < .01). The median duration of follow-up for the entire cohort was 573 days. The cumulative incidence of aGVHD (grade II-IV or grade III-IV) was not significantly different among the cohorts; however, the cumulative incidence of cGVHD at 18 months was highest in the MUD cohort (31.7%, versus 10.0% in the MSD cohort and 9.2% in the haplo cohort; P = .02). There were no differences in the 18-month cumulative incidence of relapse or NRM. OS and RFS at 18 months were 80.7% (95% confidence interval [CI], 61.7% to 100%) and 73.8% (95% CI, 55.5% to 98.1%) for the haplo cohort, 83.4% (95% CI, 72.8% to 95.5%) and 70.3% (95% CI, 57.9% to 85.3%) for the MUD cohort, and 80.9% (95% CI, 66.9% to 97.7%) and 66.5% (95% CI, 50.5% to 87.5%) for the MSD cohort, with no statistically significant differences among the cohorts. GRFS at 18 months was 61% (95% CI, 43.3% to 85.9%) for the haplo cohort, 44.6% (95% CI, 31.8% to 62.5%) for the MUD cohort, and 62.1% (95% CI, 45.7% to 84.3%) for the MSD cohort (P = .26). Haploidentical PBSC HSCT with PTCy had comparable outcomes to MSD and MUD BM HSCT and less cGVHD compared with MUD BM HSCT in children. The logistical advantages and lower resource burden of haplo HSCT with PBSCs make it a feasible alternative to MUD HSCT in children with hematologic malignancies. Given that this is a retrospective comparison of transplantation platforms rather than donor types, further prospective studies are warranted. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Safety of allogeneic umbilical cord blood infusions for the treatment of neurological conditions: a systematic review of clinical studies.

BACKGROUND AIMS: Umbilical cord blood (UCB) infusion is being investigated as a treatment for a range of neurological conditions, primarily because of its potent immunomodulatory effects mediated via paracrine signaling. Although initial research mainly utilized autologous UCB, allogeneic samples from a sibling or unrelated donor have now become more common. With the use of allogeneic UCB, questions have arisen surrounding the necessity for human leukocyte antigen (HLA) matching, preparative regimens and immunosuppressant drugs. To investigate the safety of allogeneic UCB for the treatment of neurological conditions and the impact of HLA mismatching and immunosuppresion, the authors conducted a systematic review of the safety of allogeneic UCB infusion for neurological conditions. METHODS: A systematic review of published and gray literature was conducted to investigate the safety of allogeneic UCB infusions for neurological conditions. RESULTS: Authors identified 10 studies using allogeneic UCB to treat autism spectrum disorder, cerebral palsy, stroke, traumatic brain injury and various other conditions. A total of 361 participants (with at least 442 UCB infusions) received a range of HLA-matched/untyped allogeneic units and cell doses, with the majority not administered post-infusion immunosuppression. There were no reported serious adverse events definitely or probably related to the allogeneic UCB infusion, nor later potential complications such as graft-versus-host disease or teratoma formation. CONCLUSIONS: Although variability between studies is high, the available data do not identify safety concerns with allogeneic UCB infusion for the treatment of neurological conditions, even with variable HLA matching or no immunosuppression.

Peripheral venous catheter collection of immune effector cells and hematopoietic stem cells is feasible and safe in older pediatric patients.

BACKGROUND: The Collection of hematopoietic stem cells (HSC) and immune effector cells (IEC) has unique challenges in children. To maintain adequate blood flow, central venous catheters (CVCs) remain the standard of care in many centers, but are associated with procedural risks and increased resource utilization. The goal of this study was to determine feasibility and safety of peripheral venous catheter (PVC) cell collection in older children. METHODS: Patients and donors requiring venous access with weight >25 kg, age >8 years were screened for PVC collection via 18G PVCs. Those with poor venous access (on history/exam/pre-screening ultrasound) or unable to maintain suitable procedural position were excluded. Comparison was made to CVC collections in a matched patient cohort. RESULTS: Thirty-eight individuals were screened and met age/weight criteria for PVC collection. Five did not have PVC collection attempted due to poor access (n = 4) or behavioral concerns (n = 1). Thirty-three had PVC collection attempt (HSC = 22; IEC = 11) with median age 15.3 year (range 9.7-18.0) and weight 58.5 kg (range 27.9-115.4). Thirty-two of 33 (97%) patients were collected successfully by PVC without adverse events. Comparing PVC to matched CVC collection cohort (n = 18), there was no significant difference in flow rate (48.2 mL/h vs 53.9 mL/h, p = 0.12), collection time (266 min vs 262 min, p = 0.85) or collection efficiency (IEC/CD3 60.9% vs 60.8% p = 0.99; HSC/CD34 53.6% vs 41.3% p = 0.05). CONCLUSION: PVC collection of HSC and IEC is feasible and safe in older children with comparable collection efficiency to CVC collections. Ultrasound screening may reduce failure rates. PVC collections can reduce the risk of CVC insertions and associated healthcare costs.

Sequential paternal haploidentical donor liver and HSCT in EPP allow discontinuation of immunosuppression post-organ transplant.

BACKGROUND: EPP is characterized by photosensitivity and by liver disease. When LT is performed in EPP, recurrence often occurs in the allograft due to ongoing protoporphyrin production in bone marrow. Therefore, curative treatment requires allogeneic HSCT after LT. Long-term immunosuppression could be spared by using the same donor for both transplants. METHODS: A 2-year-old girl with EPP in liver failure underwent liver transplant from her father. Transfusion and apheresis therapy were used to lower protoporphyrin levels before and after liver transplant. Ten weeks after liver transplant, she underwent HSCT, using the same donor. Conditioning was with treosulfan, fludarabine, cyclophosphamide, and ATG. GVHD prophylaxis was with abatacept, methotrexate, MMF, and tacrolimus. We followed the patient's erythrocyte protoporphyrin and liver and skin health for 2 years after transplant. RESULTS: After hematopoietic stem cell engraftment, a decline in protoporphyrin levels was observed, with clinical resolution of photosensitivity. Liver biopsies showed no evidence of EPP. Mild ACR occurred and responded to steroid pulse. Two years post-HSCT, the patient has been weaned off all immunosuppression and remains GVHD and liver rejection free. CONCLUSIONS: Sequential liver and HSCT from the same haploidentical donor are feasible in EPP. This strategy can allow for discontinuation of immune suppression.

Delirium in Children Undergoing Hematopoietic Cell Transplantation: A Multi-Institutional Point Prevalence Study.

Introduction: Delirium occurs frequently in adults undergoing hematopoietic cell transplantation, with significant associated morbidity. Little is known about the burden of delirium in children in the peri-transplant period. This study was designed to determine delirium rates, define risk factors (demographic and treatment related), and establish feasibility of multi-institutional bedside screening for delirium in children undergoing hematopoietic cell transplant. Methods: This is a multi-institutional point prevalence study. All subjects were prospectively screened for delirium twice daily using the Cornell Assessment of Pediatric Delirium over a 10-day period. De-identified data, including basic demographics and daily characteristics, were extracted from the electronic medical record. Results: Eleven North American institutions were included, 106 children were enrolled, and 883 hospital days were captured. Delirium screening was successfully completed on more than 98% of the study days. Forty-eight children (45%) developed delirium over the course of the 10-day study. Children were diagnosed with delirium on 161/883 study days, for an overall delirium rate of 18% per day. Higher delirium rates were noted in children <5 years old (aOR 0.41 for children over 5 years), and in association with specific medications (melatonin, steroids, and tacrolimus). Conclusion: Delirium was a frequent occurrence in our study cohort, with identifiable risk factors. Delirium screening is highly feasible in the pediatric hematopoietic cell transplant patient population. A large-scale prospective longitudinal study following children throughout their transplant course is urgently needed to fully describe the epidemiology of pediatric delirium, explore the effects of delirium on patient outcomes, and establish guidelines to prevent and treat delirium in the peri-transplant period.

A Novel Secondary Neoplasm Following Allogeneic Hematopoietic Stem Cell Transplant: Mixed Donor-Recipient Primitive Mesenchymal Proliferation of the Liver.

Post-hematopoietic stem cell transplant secondary solid neoplasms are uncommon and usually host-derived. We describe a 6-year-old female who developed a mixed donor-recipient origin mesenchymal stromal tumor-like lesion in the liver following an unrelated hematopoietic stem cell transplant complicated by severe graft-versus-host disease. This lesion arose early post-transplant in association with hepatic graft-versus-host disease. At 12 years post-transplant, the neoplasm has progressively shrunken in size and the patient remains well with no neoplasm-associated sequelae. This report characterizes a novel lesion of mixed origin post-transplant and offers unique insights into the contribution of bone marrow-derived cells to extra-medullary tissues.

CRISPR-Cas9 Gene Editing for Sickle Cell Disease and ß-Thalassemia.

Transfusion-dependent ß-thalassemia (TDT) and sickle cell disease (SCD) are severe monogenic diseases with severe and potentially life-threatening manifestations. BCL11A is a transcription factor that represses γ-globin expression and fetal hemoglobin in erythroid cells. We performed electroporation of CD34+ hematopoietic stem and progenitor cells obtained from healthy donors, with CRISPR-Cas9 targeting the BCL11A erythroid-specific enhancer. Approximately 80% of the alleles at this locus were modified, with no evidence of off-target editing. After undergoing myeloablation, two patients - one with TDT and the other with SCD - received autologous CD34+ cells edited with CRISPR-Cas9 targeting the same BCL11A enhancer. More than a year later, both patients had high levels of allelic editing in bone marrow and blood, increases in fetal hemoglobin that were distributed pancellularly, transfusion independence, and (in the patient with SCD) elimination of vaso-occlusive episodes. (Funded by CRISPR Therapeutics and Vertex Pharmaceuticals; ClinicalTrials.gov numbers, NCT03655678 for CLIMB THAL-111 and NCT03745287 for CLIMB SCD-121.).

Prevalence and Clinical Features of Inflammatory Bowel Diseases Associated With Monogenic Variants, Identified by Whole-Exome Sequencing in 1000 Children at a Single Center.

BACKGROUND & AIMS: A proportion of infants and young children with inflammatory bowel diseases (IBDs) have subtypes associated with a single gene variant (monogenic IBD). We aimed to determine the prevalence of monogenic disease in a cohort of pediatric patients with IBD. METHODS: We performed whole-exome sequencing analyses of blood samples from an unselected cohort of 1005 children with IBD, aged 0-18 years (median age at diagnosis, 11.96 years) at a single center in Canada and their family members (2305 samples total). Variants believed to cause IBD were validated using Sanger sequencing. Biopsies from patients were analyzed by immunofluorescence and histochemical analyses. RESULTS: We identified 40 rare variants associated with 21 monogenic genes among 31 of the 1005 children with IBD (including 5 variants in XIAP, 3 in DOCK8, and 2 each in FOXP3, GUCY2C, and LRBA). These variants occurred in 7.8% of children younger than 6 years and 2.3% of children aged 6-18 years. Of the 17 patients with monogenic Crohn's disease, 35% had abdominal pain, 24% had nonbloody loose stool, 18% had vomiting, 18% had weight loss, and 5% had intermittent bloody loose stool. The 14 patients with monogenic ulcerative colitis or IBD-unclassified received their diagnosis at a younger age, and their most predominant feature was bloody loose stool (78%). Features associated with monogenic IBD, compared to cases of IBD not associated with a single variant, were age of onset younger than 2 years (odds ratio [OR], 6.30; P = .020), family history of autoimmune disease (OR, 5.12; P = .002), extra-intestinal manifestations (OR, 15.36; P < .0001), and surgery (OR, 3.42; P = .042). Seventeen patients had variants in genes that could be corrected with allogeneic hematopoietic stem cell transplantation. CONCLUSIONS: In whole-exome sequencing analyses of more than 1000 children with IBD at a single center, we found that 3% had rare variants in genes previously associated with pediatric IBD. These were associated with different IBD phenotypes, and 1% of the patients had variants that could be potentially corrected with allogeneic hematopoietic stem cell transplantation. Monogenic IBD is rare, but should be considered in analysis of all patients with pediatric onset of IBD.