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.).

Allogeneic Hematopoietic Cell Transplantation Using Treosulfan-Based Conditioning for Treatment of Marrow Failure Disorders.

Hematopoietic cell transplantation (HCT) is effective in the treatment of inherited marrow failure disorders and other nonmalignant diseases. Conventional myeloablative conditioning regimens have been associated with high transplant-related mortality, particularly in patients with comorbid conditions. Here we report on 14 patients with marrow failure disorders (Shwachman-Diamond syndrome, n = 3; Diamond Blackfan anemia, n = 4; GATA2 deficiency, n = 2; paroxysmal nocturnal hemoglobinuria, n = 4; and an undefined marrow failure disorder, n = 1) who underwent HCT on a prospective, phase II, multicenter clinical trial. Patients were given HLA-matched related (n = 2) or unrelated (n = 12) grafts after conditioning with treosulfan (42 g/m2), fludarabine (150 mg/m2), ± thymoglobulin (n = 11; 6 mg/kg). All patients engrafted. At a median follow-up of 3 years, 13 patients are alive with complete correction of their underlying disease. These results indicate that the combination of treosulfan, fludarabine, and thymoglobulin is effective at establishing donor engraftment with a low toxicity profile and excellent disease-free survival in patients with marrow failure disorders.

Rapid progression and mortality of lysosomal acid lipase deficiency presenting in infants.

PURPOSE: The purpose of this study was to enhance understanding of lysosomal acid lipase deficiency (LALD) in infancy. METHODS: Investigators reviewed medical records of infants with LALD and summarized data for the overall population and for patients with and without early growth failure (GF). Kaplan-Meier survival analyses were conducted for the overall population and for treated and untreated patients. RESULTS: Records for 35 patients, 26 with early GF, were analyzed. Prominent symptom manifestations included vomiting, diarrhea, and steatorrhea. Median age at death was 3.7 months; estimated probability of survival past age 12 months was 0.114 (95% confidence interval (CI): 0.009-0.220). Among patients with early GF, median age at death was 3.5 months; estimated probability of survival past age 12 months was 0.038 (95% CI: 0.000-0.112). Treated patients (hematopoietic stem cell transplant (HSCT), n = 9; HSCT and liver transplant, n = 1) in the overall population and the early GF subset survived longer than untreated patients, but survival was still poor (median age at death, 8.6 months). CONCLUSIONS: These data confirm and expand earlier insights on the progression and course of LALD presenting in infancy. Despite variations in the nature, onset, and severity of clinical manifestations, and treatment attempts, clinical outcome was poor.Genet Med 18 5, 452-458.

The outcome of allogeneic hematopoietic cell transplantation for children with FMS-like tyrosine kinase 3 internal tandem duplication-positive acute myelogenous leukemia.

FMS-like tyrosine kinase 3 (FLT3) internal tandem duplication (ITD) is a somatic mutation associated with poor outcome when treated with chemotherapy alone. In children, hematopoietic stem cell transplantation (HSCT) is recommended, but very limited data on outcome are reported. We determined the outcome of 29 children with FLT3/ITD-positive acute myelogenous leukemia (AML) who underwent allogeneic HSCT in 4 pediatric centers. Eleven patients (38%) received matched related donor hematopoietic stem cells and 18 (62%) received alternative donors. Eighteen patients (62%) received total body irradiation (TBI)-based regimens. No patients experienced transplantation-related mortality. Eleven patients (38%) experienced relapsed disease. The cumulative incidence of relapse at 2 years was 34.7% (95% confidence interval [CI], 20.4% to 54.9%). Two-year disease-free survival (DFS) and overall survival (OS) were 65.3% (95% CI, 45.1% to 79.6%) and 82.2% (95% CI, 58.5% to 91.3%), respectively. There was no difference in the DFS of patients who received transplants from related donors versus the DFS of those who received transplants from alternative donors (hazard ratio [HR], 2.64; 95% CI, .79 to 8.76; P = .10), using univariate analysis. Patients with higher FLT3/ITD ratio at diagnosis had significantly worse DFS (HR, 1.42; 95% CI, 1.04 to 1.93; P = .03). The use of TBI in the preparative regimen was associated with superior DFS (HR, .29; 95% CI, .08 to .99; P = .04) and OS (HR, .07; 95% CI, .01 to .62; P = .002). We conclude that allogeneic HSCT improves DFS and OS in children with FLT3/ITD-positive AML compared with what has been reported in those treated with chemotherapy alone.

Human rhinovirus C infections in pediatric hematology and oncology patients.

Children with cancer and HSCT recipients are at high risk for common viral infections. We sought to define the viral etiology of ARI and identify risk factors. Nasal wash samples were collected from pediatric hematology-oncology patients and HSCT recipients with ARI during the 2003-2005 winter seasons. Real-time RT-PCR was performed to detect Flu A, influenza B, RSV, PIV 1-3, human MPV, and HRV. HRV specimens were sequenced and genotyped. Seventy-eight samples from 62 children were included. Viruses were detected in 31 of 78 samples (40%). HRV were detected most frequently, in 16 (52%) including five HRVC; followed by seven (22%) RSV, five (16%) Flu A, four (13%) MPV, and two (6%) PIV2. There was a trend toward higher risk of viral infection for children in day care. Only 8% of the study children had received influenza vaccine. HRV, including the recently discovered HRVC, are an important cause of infection in pediatric oncology and HSCT patients. Molecular testing is superior to conventional methods and should be standard of care, as HRV are not detected by conventional methods.

Treosulfan-based conditioning and hematopoietic cell transplantation for nonmalignant diseases: a prospective multicenter trial.

Hematopoietic cell transplantation is an effective treatment for patients with nonmalignant diseases and for many is the only known cure. Conventional myeloablative regimens have been associated with unacceptably high early transplant-related mortality (TRM), particularly in patients with comorbid conditions. This prospective multicenter trial was designed to determine the safety and engraftment efficacy of treosulfan-based conditioning in patients with nonmalignant diseases. Thirty-one patients received HLA-matched related (n = 4) or unrelated (n = 27) grafts after conditioning with treosulfan (total dose, 42 g/m(2)), fludarabine (total dose, 150 mg/m(2)), ± thymoglobulin (6 mg/kg; n = 22). Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus and methotrexate. All patients engrafted. Day-100 TRM was 0%. With a median follow-up of 2 years, the 2-year survival was 90%. Three patients died of GVHD, recurrent hemophagocytic lymphohistiocytosis, and a surgical complication, respectively. The cumulative incidences of grades II to IV and III to IV acute GVHD at day 100 and chronic GVHD at 2 years were 62%, 10%, and 21%, respectively. Patients who received thymoglobulin had a significantly lower incidence of grades III to IV acute GVHD (0% versus 33%; P = .005). These results indicate that the combination of treosulfan, fludarabine, and thymoglobulin is effective at establishing donor engraftment with low toxicity and improved survival in patients with nonmalignant diseases and support the need for future disease-specific clinical trials.

Allogeneic hematopoietic stem cell transplantation for infants with idiopathic myelofibrosis.

IMF is a rare disease in children that can present during infancy and has a protracted course. The only known curative approach for this disease in adult patients is allogeneic HSCT. There are very few reports describing the long-term outcome of young children following stem cell transplantation for IMF. We report on eight patients less than two yr of age with IMF that did not resolve with supportive care measures. All patients underwent myeloablative conditioning regimen with busulfan and cyclophosphamide ± ATG followed by HSCT from matched related (n = 6) or unrelated donor (n = 2). All patients achieved neutrophil and platelet engraftment. Four patients had grade II-III acute GVHD, and chronic GVHD developed in five patients (three mild and two severe). At a median follow-up of eight and a half yr (0.7-9), all patients are alive with complete resolution of their hematologic manifestations. At the last follow-up, all patients had normal endocrine function except for one patient who developed hypothyroidism. To date, this is the largest cohort of young children with IMF treated successfully with HSCT, with the longest duration of follow-up. In conclusion, our study showed that HSCT is a curative option for infants with IMF.

New allergies after cord blood transplantation.

BACKGROUND AIMS: Umbilical cord blood transplantation (CBT) is an effective treatment for benign and malignant diseases. Late effects of CBT are not well described in the literature. In the present study, we present our experience of new-onset allergies in long-term survivors after CBT. METHODS: After an initial patient had a severe peanut allergic reaction after CBT, all CBT patients were prospectively followed for new allergy development. Fifty patients received CBT between March 2006 and June 2011. RESULTS: The median follow-up after CBT was 447 days (range, 12-2022). At the time of analysis, 30 patients were alive, with 3-year survival of 55.5%; median follow-up of surviving patients was 910 days (range, 68-2022). The allergic syndrome developed in five patients, with the cumulative incidence of new allergies at 2 years of 18.4% (95% confidence interval, 10.8-26). The median time to onset of new allergy after transplantation was 298 days (range, 250-809). CONCLUSIONS: Allergy development has been linked to a delayed maturation of the immune system in several studies. We present the first case series of patients who had new allergies after CBT. Further study of this novel complication as well as counseling of patients after CBT would be important.

t(17;19) in Children with Acute Lymphocytic Leukemia: A Report of 3 Cases and a Review of the Literature.

Several cytogenetic abnormalities identified in patients with childhood acute lymphocytic leukemia (ALL) have been associated with a poor prognosis. There are several case reports in the literature describing t(17;19) in children with ALL. This translocation has been associated with hypercalcemia, coagulopathy, and poor outcome. We present three cases of ALL with t(17;19) treated at our institution and review the outcome of children reported in the medical literature.

Effect of acute graft-versus-host disease on the outcome of second allogeneic hematopoietic stem cell transplant in children.

Studies have shown second allogeneic hematopoietic stem cell transplant (HSCT) to have a potential role in treating relapse after HSCT. We sought to evaluate the outcome of second allogeneic HSCT for children with relapsed leukemia with focus on factors that potentially improve outcome. Thirty-eight children were identified. The median time between transplants was 18.6 months (range 6.7-50.1 months). With median follow-up of 44 months the 2-year overall survival (OS) was 59.1 ± 8.2%. The leukemia-free survival was 51.8 ± 8.2% and the non-relapse mortality 30.8 ± 7.9%. Eleven patients (30%) died of non-relapse mortality at a median of 37 days (range 16-260 days) from second HSCT. Twenty-one patients developed acute graft-versus-host disease (aGVHD) after second HSCT. Patients who developed aGVHD had lower risk for mortality compared to patients who did not have aGVHD, with a hazard ratio (HR) of 0.27 (95% confidence interval [CI] 0.095-0.788, p-value 0.0163). Similarly, patients who developed aGVHD following second HSCT had lower risk for relapse (HR = 0.21, 95% CI 0.051-0.857, p-value 0.0297). Patients who developed aGVHD after first HSCT were less likely to benefit from second HSCT compared to patients without aGVHD after first HSCT. Our experience suggests that second HSCT for pediatric relapsed leukemia can result in acceptable survival and aGVHD is associated with improved outcome.

Comparison of pre-cryopreserved and post-thaw-and-wash-nucleated cell count on major outcomes following unrelated cord blood transplant in children.

Engraftment and OS after umbilical CBT is highly dependent on the TNC. The contribution of the wash step to cell loss and ultimately the dose of cells available for transplant is not well described. To investigate the amount of cell loss after washing and its impact on major outcomes compared to pre-cryopreserved TNC, we analyzed data from patients prospectively enrolled on a National Heart, Lung and Blood Institute sponsored cord blood transplant study between 1999 and 2003. There were 310 patients ≤18 yr of age with malignant (N = 218) or non-malignant (N = 92) disease enrolled on this trial. Only single CBU were used. All CBU were thawed and washed using an identical process. The median TNC after thawing and washing (PTW) was 5.43 × 10(7) /kg (79% recovery of cells). The cumulative incidence of neutrophil engraftment was significantly higher in patients receiving a PTW TNC ≥2.5 × 10(7) /kg (p = 0.01). The cumulative incidence of TRM was higher among patients receiving post-thaw-and-wash TNC <2.5 × 10(7) /kg (p = 0.039). In conclusion, receiving a PTW TNC of <2.5 × 10(7) /kg resulted in worse neutrophil engraftment and increased transplant-related mortality compared to a PTW TNC of ≥2.5 × 10(7) /kg.

Long-term follow-up and management guidelines in pediatric patients after allogenic hematopoietic stem cell transplantation.

Over the past 50 years there has been considerable progress and success in the field of allogeneic hematopoietic stem cell transplant (HSCT) in children. In addition there has been significant improvement in transplant outcomes for both malignant and nonmalignant indications. These improved outcomes have resulted in many long-term survivors who are experiencing substantial long-term morbidities. There are limited data examining the long-term complications of transplant on the various organs. This issue is complicated by the fact that children receive their transplant at different stages of their growth and development (ie, infant, toddler, child, adolescent, and young adult). Each of these developmental stages has different sensitivities to treatment and can result in different sets of complications. We summarize the long-term side effects of allogeneic HSCT in children.

A case of pediatric PTLD following autologous stem cell transplantation and review of the literature.

The development of PTLD is a rare severe adverse event following ASCT. We report on a child with DS who developed PTLD following autologous transplant for relapsed Hodgkin's disease. He was successfully treated with cyclophosphamide, prednisone and rituximab. We also present a comprehensive review of the literature of PTLD in pediatric patients following ASCT.

Incidence, risk factors, and outcome of pneumatosis intestinalis in pediatric stem cell transplant recipients.

BACKGROUND: Pneumatosis Intestinalis (PI) is a rare complication following hematopoietic stem cell transplant (HSCT). We sought to assess the incidence, risk factors, and outcome associated with PI. PROCEDURE: We retrospectively reviewed the incidence of PI among 178 patients who underwent allogeneic HSCT between September 1999 and February 2010. RESULTS: Eighteen of 178 children (10.1%) who received allogeneic HSCT developed PI at a median of 94 days (range, 11-1169) after transplant. All patients presented with either abdominal pain or distention, and half of the patients had free air on radiographs. Patients who developed PI had a significantly higher proportion of acute (83% vs. 44%, P = 0.002) and chronic graft versus host disease (GVHD; 56% vs. 18%, P < 0.001). Only 39% of patients with PI had GVHD involving the gasterointestinal track. All patients were managed conservatively without surgery. Transplant related mortality (TRM) was significantly higher in patients who developed PI compared to those who did not (OR 4.3, 95% CI: 1.3-13.1; P = 0.007), but no deaths were attributable to PI. CONCLUSIONS: We conclude that PI is a common complication associated with treatment of GVHD after HSCT, and patients who develop PI experience higher TRM. Patients who develop PI should be managed medically.

A unique clinical presentation of X-linked lymphoproliferative syndrome with a novel mutation in SH2D1A and review of the literature.

X-linked lymphoproliferative syndrome is a well-described syndrome often characterized by progression to fatal infectious mononucleosis. Many mutations of the SH2D1A gene have been identified in patients with X-linked lymphoproliferative syndrome. These mutations are often associated with either decreased or impaired function of the protein product, signaling lymphocytic activation molecule-associated protein. We describe a patient with a novel missense mutation in SH2D1A. We report on his unique presentation, clinical course and subsequent successful treatment with a matched unrelated donor bone marrow transplant.

Early lymphocyte reconstitution is associated with improved transplant outcome after cord blood transplantation.

BACKGROUND AIMS: Previous studies have shown that rapid recovery of the absolute lymphocyte count (ALC) is associated with improved transplant outcomes after related and unrelated donor allogeneic stem cell transplantation (allo-SCT). No consistent association has been reported between lymphocyte recovery and transplant outcome after cord blood transplantation (CBT). METHODS: We reviewed the records of 40 consecutive CBT patients at our institution to determine the impact of lymphocyte recovery on transplant outcome. RESULTS: The majority of patients (83%) received CBT for hematologic malignancies. Patients with ALC ≥150/µL at 30 days post-CBT had decreased non-relapse mortality (NRM) (P = 0.011) and improved survival (P = 0.013) compared with ALC <150/µL. Patients with ALC <100/µL at 30 days post-CBT had a significantly higher rate of graft failure than those with ALC ≥100/µL (four of 10 versus one of 29; P = 0.011). ALC was positively correlated with the nucleated cell dose and inversely correlated with the patient's age. There was no relationship between disease risk, type of conditioning regimen, anti-thymocyte globulin and number of cord units on ALC recovery. CONCLUSIONS: Our results indicate that ALC 30 days post-CBT is a surrogate for engraftment, and that low ALC (<150/µL) identifies an 'at-risk' population of patients after CBT. Studies are needed to determine ways to increase ALC cell numbers post-CBT, including ex vivo-expanded natural killer cells using adoptive immunotherapy, which might improve outcome after CBT.