Liver disease and transplantation in telomere biology disorders: An international multicenter cohort.

BACKGROUND: Patients with telomere biology disorders (TBD) develop hepatic disease, including hepatitis, cirrhosis, and hepatopulmonary syndrome. No specific treatment exists for TBD-related liver disease, and the role of liver transplantation (LT) remains controversial. Our study objectives were to describe the clinical characteristics, management, and outcomes in patients with TBD-related liver disease, and their LT outcomes. METHODS: Data from 83 patients with TBD-associated liver disease were obtained from 17 participating centers in the Clinical Care Consortium of Telomere-Associated Ailments and by self-report for our retrospective, multicenter, international cohort study. RESULTS: Group A ("Advanced") included 40 patients with advanced liver disease. Of these, 20 underwent LT (Group AT). Group M ("Mild") included 43 patients not warranting LT evaluation, none of whom were felt to be medically unfit for liver transplantation. Supplemental oxygen requirement, pulmonary arteriovenous malformation, hepatopulmonary syndrome, and higher bilirubin and international normalized ratio values were associated with Group A. Other demographics, clinical manifestations, and laboratory findings were similar between groups. Six group A patients were declined for LT; 3 died on the waitlist. Median follow-up post-LT was 2.9 years (range 0.6-13.2 y). One-year survival post-LT was 73%. Median survival post-LT has not been reached. Group AT patients had improved survival by age compared to all nontransplant patients (log-rank test p = 0.02). Of 14 patients with pretransplant hypoxemia, 8 (57%) had improved oxygenation after transplant. CONCLUSIONS: LT recipients with TBD do not exhibit excessive posttransplant mortality, and LT improved respiratory status in 57%. A TBD diagnosis should not exclude LT consideration.

Wiskott-Aldrich syndrome: a study of 577 patients defines the genotype as a biomarker for disease severity and survival.

ABSTRACT: Wiskott-Aldrich syndrome (WAS) is a multifaceted monogenic disorder with a broad disease spectrum and variable disease severity and a variety of treatment options including allogeneic hematopoietic stem cell transplantation (HSCT) and gene therapy (GT). No reliable biomarker exists to predict disease course and outcome for individual patients. A total of 577 patients with a WAS variant from 26 countries and a median follow-up of 8.9 years (range, 0.3-71.1), totaling 6118 patient-years, were included in this international retrospective study. Overall survival (OS) of the cohort (censored at HSCT or GT) was 82% (95% confidence interval, 78-87) at age 15 years and 70% (61-80) at 30 years. The type of variant was predictive of outcome: patients with a missense variant in exons 1 or 2 or with the intronic hot spot variant c.559+5G>A (class I variants) had a 15-year OS of 93% (89-98) and a 30-year OS of 91% (86-97), compared with 71% (62-81) and 48% (34-68) in patients with any other variant (class II; P < .0001). The cumulative incidence rates of disease-related complications such as severe bleeding (P = .007), life-threatening infection (P < .0001), and autoimmunity (P = .004) occurred significantly later in patients with a class I variant. The cumulative incidence of malignancy (P = .6) was not different between classes I and II. It confirms the spectrum of disease severity and quantifies the risk for specific disease-related complications. The class of the variant is a biomarker to predict the outcome for patients with WAS.

Gaps in diagnosing suspected infection in immunocompromised children with cancer: A systematic review.

While the survival of children with cancer has improved over time, infection remains a major morbidity and mortality risk. We conducted a systematic literature review to determine the unmet needs in diagnosing infection in immunocompromised children with cancer. The comprehensive search strategy followed the guidelines established by the Cochrane Handbook for Systematic Reviews of Interventions and the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) 2020 statement, and spanned multiple bibliographic databases and other public sources from January 1, 2012 to June 23, 2022. From 5188 records, 34 unique pediatric-focused studies met inclusion criteria. This review highlights the lack of published data on infectious disease testing in pediatric oncology patients, and the need for well-designed clinical impact and cost-effectiveness studies of both existing and novel diagnostic platforms. Such studies are necessary to optimize diagnostic and antimicrobial stewardship, leading to improvement in patient outcomes.

CRISPR screen identifies CEBPB as contributor to dyskeratosis congenita fibroblast senescence via augmented inflammatory gene response.

Aging is the consequence of intra- and extracellular events that promote cellular senescence. Dyskeratosis congenita (DC) is an example of a premature aging disorder caused by underlying telomere/telomerase-related mutations. Cells from these patients offer an opportunity to study telomere-related aging and senescence. Our previous work has found that telomere shortening stimulates DNA damage responses (DDRs) and increases reactive oxygen species (ROS), thereby promoting entry into senescence. This work also found that telomere elongation via TERT expression, the catalytic component of the telomere-elongating enzyme telomerase, or p53 shRNA could decrease ROS by disrupting this telomere-DDR-ROS pathway. To further characterize this pathway, we performed a CRISPR/Cas9 knockout screen to identify genes that extend life span in DC cells. Of the cellular clones isolated due to increased life span, 34% had a guide RNA (gRNA) targeting CEBPB, while gRNAs targeting WSB1, MED28, and p73 were observed multiple times. CEBPB is a transcription factor associated with activation of proinflammatory response genes suggesting that inflammation may be present in DC cells. The inflammatory response was investigated using RNA sequencing to compare DC and control cells. Expression of inflammatory genes was found to be significantly elevated (P < 0.0001) in addition to a key subset of these inflammation-related genes [IL1B, IL6, IL8, IL12A, CXCL1 (GROa), CXCL2 (GROb), and CXCL5]. which are regulated by CEBPB. Exogenous TERT expression led to downregulation of RNA/protein CEBPB expression and the inflammatory response genes suggesting a telomere length-dependent mechanism to regulate CEBPB. Furthermore, unlike exogenous TERT and p53 shRNA, CEBPB shRNA did not significantly decrease ROS suggesting that CEBPB's contribution in DC cells' senescence is ROS independent. Our findings demonstrate a key role for CEBPB in engaging senescence by mobilizing an inflammatory response within DC cells.

Measuring the effect of newborn screening on survival after haematopoietic cell transplantation for severe combined immunodeficiency: a 36-year longitudinal study from the Primary Immune Deficiency Treatment Consortium.

BACKGROUND: Severe combined immunodeficiency (SCID) is fatal unless durable adaptive immunity is established, most commonly through allogeneic haematopoietic cell transplantation (HCT). The Primary Immune Deficiency Treatment Consortium (PIDTC) explored factors affecting the survival of individuals with SCID over almost four decades, focusing on the effects of population-based newborn screening for SCID that was initiated in 2008 and expanded during 2010-18. METHODS: We analysed transplantation-related data from children with SCID treated at 34 PIDTC sites in the USA and Canada, using the calendar time intervals 1982-89, 1990-99, 2000-09, and 2010-18. Categorical variables were compared by χ2 test and continuous outcomes by the Kruskal-Wallis test. Overall survival was estimated by the Kaplan-Meier method. A multivariable analysis using Cox proportional hazards regression models examined risk factors for HCT outcomes, including the variables of time interval of HCT, infection status and age at HCT, trigger for diagnosis, SCID type and genotype, race and ethnicity of the patient, non-HLA-matched sibling donor type, graft type, GVHD prophylaxis, and conditioning intensity. FINDINGS: For 902 children with confirmed SCID, 5-year overall survival remained unchanged at 72%-73% for 28 years until 2010-18, when it increased to 87% (95% CI 82·1-90·6; n=268; p=0·0005). For children identified as having SCID by newborn screening since 2010, 5-year overall survival was 92·5% (95% CI 85·8-96·1), better than that of children identified by clinical illness or family history in the same interval (79·9% [69·5-87·0] and 85·4% [71·8-92·8], respectively [p=0·043]). Multivariable analysis demonstrated that the factors of active infection (hazard ratio [HR] 2·41, 95% CI 1·56-3·72; p<0·0001), age 3·5 months or older at HCT (2·12, 1·38-3·24; p=0·001), Black or African-American race (2·33, 1·56-3·46; p<0·0001), and certain SCID genotypes to be associated with lower overall survival during all time intervals. Moreover, after adjusting for several factors in this multivariable analysis, HCT after 2010 no longer conveyed a survival advantage over earlier time intervals studied (HR 0·73, 95% CI 0·43-1·26; p=0·097). This indicated that younger age and freedom from infections at HCT, both directly driven by newborn screening, were the main drivers for recent improvement in overall survival. INTERPRETATION: Population-based newborn screening has facilitated the identification of infants with SCID early in life, in turn leading to prompt HCT while avoiding infections. Public health programmes worldwide can benefit from this definitive demonstration of the value of newborn screening for SCID. FUNDING: National Institute of Allergy and Infectious Diseases, Office of Rare Diseases Research, and National Center for Advancing Translational Sciences.

The impacts of total body irradiation on umbilical cord blood hematopoietic stem cell transplantation.

Background: Umbilical cord blood hematopoietic stem cells are commonly used for hematopoietic system reconstitution in recipients after umbilical cord blood transplantation (UCBT). However, the optimal conditioning regimen for UCBT remains a topic of debate. The exact impact of total body irradiation (TBI) as a part of conditioning regimens remains unknown. Objectives: The aim of this study was to evaluate the impacts of TBI on UCBT outcomes. Design: This was a multi-institution retrospective study. Methods: A retrospective analysis was conducted on the outcomes of 136 patients receiving UCBT. Sixty-nine patients received myeloablative conditioning (MAC), in which 33 underwent TBI and 36 did not, and 67 patients received reduced-intensity conditioning (RIC), in which 43 underwent TBI and 24 did not. Univariate and multivariate analyses were conducted to compare the outcomes and the post-transplant complications between patients who did and did not undergo TBI in the MAC subgroup and RIC subgroup, respectively. Results: In the RIC subgroup, patients who underwent TBI had superior overall survival (adjusted hazard ratio [aHR] = 0.25, 95% confidence interval [CI]: 0.09-0.66, p = 0.005) and progression-free survival (aHR = 0.26, 95% CI: 0.10-0.66, p = 0.005). However, in the MAC subgroup, there were no statistically significant differences between those receiving and not receiving TBI. Conclusion: In the setting of RIC in UCBT, TBI utilization can improve overall survival and progression-free survival. However, TBI does not show superiority in the MAC setting.

The diagnosis of severe combined immunodeficiency: Implementation of the PIDTC 2022 Definitions.

BACKGROUND: Shearer et al in 2014 articulated well-defined criteria for the diagnosis and classification of severe combined immunodeficiency (SCID) as part of the Primary Immune Deficiency Treatment Consortium's (PIDTC's) prospective and retrospective studies of SCID. OBJECTIVE: Because of the advent of newborn screening for SCID and expanded availability of genetic sequencing, revision of the PIDTC 2014 Criteria was needed. METHODS: We developed and tested updated PIDTC 2022 SCID Definitions by analyzing 379 patients proposed for prospective enrollment into Protocol 6901, focusing on the ability to distinguish patients with various SCID subtypes. RESULTS: According to PIDTC 2022 Definitions, 18 of 353 patients eligible per 2014 Criteria were considered not to have SCID, whereas 11 of 26 patients ineligible per 2014 Criteria were determined to have SCID. Of note, very low numbers of autologous T cells (<0.05 × 109/L) characterized typical SCID under the 2022 Definitions. Pathogenic variant(s) in SCID-associated genes was identified in 93% of patients, with 7 genes (IL2RG, RAG1, ADA, IL7R, DCLRE1C, JAK3, and RAG2) accounting for 89% of typical SCID. Three genotypes (RAG1, ADA, and RMRP) accounted for 57% of cases of leaky/atypical SCID; there were 13 other rare genotypes. Patients with leaky/atypical SCID were more likely to be diagnosed at more than age 1 year than those with typical SCID lacking maternal T cells: 20% versus 1% (P < .001). Although repeat testing proved important, an initial CD3 T-cell count of less than 0.05 × 109/L differentiated cases of typical SCID lacking maternal cells from leaky/atypical SCID: 97% versus 7% (P < .001). CONCLUSIONS: The PIDTC 2022 Definitions describe SCID and its subtypes more precisely than before, facilitating analyses of SCID characteristics and outcomes.

Severe, life-threatening, and fatal chronic health conditions after allogeneic blood or marrow transplantation in childhood.

BACKGROUND: A comprehensive assessment of morbidity after allogeneic bone marrow transplantation (BMT) performed in childhood remains understudied. METHODS: Seven hundred eighty-nine allogeneic BMT recipients who had survived ≥2 years after BMT performed between 1974 and 2014 at age <22 years and 690 siblings completed a 255-item survey self-reporting sociodemographics and chronic health conditions. A severity score (grade 3 [severe], 4 [life-threatening], or 5 [fatal]) was assigned to the conditions using Common Terminology Criteria for Adverse Events, version 5.0. For the BMT cohort, the cumulative incidence of chronic health conditions was calculated as a function of time from BMT. Proportional subdistribution hazards models were used to determine predictors of grade 3-5 conditions. Logistic regression was used to estimate the risk of grade 3-4 conditions in BMT recipients who were alive at the time of this study compared with siblings. RESULTS: The median age at transplantation was 11.3 years (range, 0.4-22.0 years), and the median length of follow-up was 11.7 years (range, 2.0-45.3 years). The most prevalent primary diagnoses were acute lymphoblastic leukemia (30.7%), and acute myeloid leukemia/myelodysplastic syndrome (26.9%). At age 35 years, the cumulative incidence of a grade 3-4 condition was 53.8% (95% CI, 46.7%-60.3%). The adjusted odds ratio of a grade 3-4 condition was 15.1 in survivors (95% CI, 9.5-24.0) compared with siblings. The risk of a grade 3-5 condition increased with age at BMT (hazard ratio [HR], 1.03; 95% CI, 1.01-1.05) and was higher among females (HR, 1.27; 95% CI, 1.02-1.59), patients who received total body irradiation (HR, 1.71; 95% CI, 1.27-2.31), and those reporting chronic graft-versus-host disease (HR, 1.38; 95% CI, 1.09-1.74). CONCLUSIONS: Two-year survivors of allogeneic BMT in childhood have an increased risk of grade 3-4 chronic health conditions compared with siblings, suggesting the need for long-term follow-up.

Combinatorial suicide gene strategies for the safety of cell therapies.

Gene-modified cellular therapies carry inherent risks of severe and potentially fatal adverse events, including the expansion of alloreactive cells or malignant transformation due to insertional mutagenesis. Strategies to mitigate uncontrolled proliferation of gene-modified cells include co-transfection of a suicide gene, such as the inducible caspase 9 safety switch (ΔiC9). However, the activation of the ΔiC9 fails to completely eliminate all gene-modified cells. Therefore, we tested a two suicide gene system used independently or together, with the goal of complete cell elimination. The first approach combined the ΔiC9 with an inducible caspase 8, ΔiC8, which lacks the endogenous prodomain. The rationale was to use a second caspase with an alternative and complementary mechanism of action. Jurkat cells co-transduced to co-express the ΔiC8, activatable by a BB homodimerizer, and the ΔiC9 activatable by the rapamycin analog sirolimus were used in a model to estimate the degree of inducible cell elimination. We found that both agents could activate each caspase independently, with enhanced elimination with superior reduction in cell regrowth of gene-modified cells when both systems were activated simultaneously. A second approach was employed in parallel, combining the ΔiC9 with the RQR8 compact suicide gene. RQR8 incorporates a CD20 mimotope, targeted by the anti-CD20 monoclonal antibody rituxan, and the QBend10, a ΔCD34 selectable marker. Likewise, enhanced cell elimination with superior reduction in cell regrowth was observed when both systems were activated together. A dose-titration effect was also noted utilizing the BB homodimerizer, whereas sirolimus remained very potent at minimal concentrations. Further in vivo studies are needed to validate these novel combination systems, which may play a role in future cancer therapies or regenerative medicine.

Outcomes following treatment for ADA-deficient severe combined immunodeficiency: a report from the PIDTC.

Adenosine deaminase (ADA) deficiency causes ∼13% of cases of severe combined immune deficiency (SCID). Treatments include enzyme replacement therapy (ERT), hematopoietic cell transplant (HCT), and gene therapy (GT). We evaluated 131 patients with ADA-SCID diagnosed between 1982 and 2017 who were enrolled in the Primary Immune Deficiency Treatment Consortium SCID studies. Baseline clinical, immunologic, genetic characteristics, and treatment outcomes were analyzed. First definitive cellular therapy (FDCT) included 56 receiving HCT without preceding ERT (HCT); 31 HCT preceded by ERT (ERT-HCT); and 33 GT preceded by ERT (ERT-GT). Five-year event-free survival (EFS, alive, no need for further ERT or cellular therapy) was 49.5% (HCT), 73% (ERT-HCT), and 75.3% (ERT-GT; P < .01). Overall survival (OS) at 5 years after FDCT was 72.5% (HCT), 79.6% (ERT-HCT), and 100% (ERT-GT; P = .01). Five-year OS was superior for patients undergoing HCT at <3.5 months of age (91.6% vs 68% if ≥3.5 months, P = .02). Active infection at the time of HCT (regardless of ERT) decreased 5-year EFS (33.1% vs 68.2%, P < .01) and OS (64.7% vs 82.3%, P = .02). Five-year EFS (90.5%) and OS (100%) were best for matched sibling and matched family donors (MSD/MFD). For patients treated after the year 2000 and without active infection at the time of FDCT, no difference in 5-year EFS or OS was found between HCT using a variety of transplant approaches and ERT-GT. This suggests alternative donor HCT may be considered when MSD/MFD HCT and GT are not available, particularly when newborn screening identifies patients with ADA-SCID soon after birth and before the onset of infections. This trial was registered at www.clinicaltrials.gov as #NCT01186913 and #NCT01346150.

Trends in Late Mortality and Life Expectancy After Autologous Blood or Marrow Transplantation Over Three Decades: A BMTSS Report.

PURPOSE: We determined trends in life expectancy and cause-specific late mortality after autologous blood or marrow transplantation (BMT) performed over a 30-year period, using the BMT Survivor Study. METHODS: We constructed a cohort of 4,702 individuals with hematologic neoplasms who lived ≥ 2 years after autologous BMT performed between 1981 and 2014 at three transplant centers. The end of follow-up was April 19, 2021. The primary exposure variable was autologous BMT performed in four eras: 1981-1999; 2000-2005; 2006-2010; and 2011-2014. Vital status and cause of death were obtained from National Death Index Plus program and Accurinct databases. RESULTS: The median age at BMT was 53 years (range, 0-78 years), 58.7% were male, 67.8% were non-Hispanic White, and 28.3% had undergone transplantation between 2011 and 2014. Autologous BMT recipients experienced a 7-year reduction in life expectancy. The adjusted hazard of 5-year all-cause mortality declined over the four eras (reference: 1981-1999; hazard ratio [HR]2000-2005 = 0.77; 95% CI, 0.62 to 0.94; HR2006-2010 = 0.64; 95% CI, 0.51 to 0.79; HR2011-2014 = 0.56; 95% CI, 0.45 to 0.71; Ptrend < .001), as did years of life lost (5.0 years to 1.6 years). The reduction in all-cause mortality was most pronounced among those transplanted for Hodgkin lymphoma or plasma cell dyscrasias, but was not observed among those transplanted for non-Hodgkin lymphoma or those conditioned with total-body irradiation. We also observed a decline in late deaths because of infection (Ptrend < .0001; primarily for BMTs before 2006) and subsequent neoplasms (Ptrend = .03; confined to decline in therapy-related myeloid neoplasm-related mortality) but not because of cardiovascular or renal disease. CONCLUSION: Late mortality among autologous BMT recipients has declined over a 30-year period. However, ongoing efforts are needed to mitigate development of infections, subsequent neoplasms, and cardiovascular and renal disease to further reduce late mortality.

Retrospective Application of Sinusoidal Obstruction Syndrome/Veno-occlusive Disease Diagnostic Criteria in a Pediatric Hematopoietic Stem Cell Transplant Cohort.

Sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) posthematopoietic stem cell transplantation (HSCT) is often diagnosed using the modified Seattle (MS) or European Society for Blood and Marrow Transplantation (EBMT) criteria. We hypothesized that strict application of these criteria could affect the timing of diagnosis and incidence of SOS/VOD. We collected data on 215 transplants performed in 184 patients at a single pediatric hematopoietic stem cell transplantation center, which were divided into 3 cohorts. Clinical diagnosis and treatment of SOS/VOD was documented in 13% of transplants (cohort 1). On retrospective review, 49% of transplant events met either MS and/or EBMT criteria, however, were not diagnosed with SOS/VOD (cohort 2); remaining 38% of transplant events did not meet MS or EBMT criteria and were not diagnosed with SOS/VOD (cohort 3). Day+100 overall survival was significantly inferior for cohort 1 (78%) compared with cohorts 2 or 3 (92% and 95%, P=0.01) with no difference between cohorts 2 and 3 (P=0.5). Patients diagnosed with SOS/VOD >day+13 had worse day+100 overall survival when compared with those diagnosed ≤day13 (64.3% and 100%, respectively, P=0.02). This study highlights the value of careful clinical assessment to guide diagnosis and the need to refine diagnostic criteria for SOS/VOD in children.

Trends in Late Mortality and Life Expectancy After Allogeneic Blood or Marrow Transplantation Over 4 Decades: A Blood or Marrow Transplant Survivor Study Report.

IMPORTANCE: The past 4 decades have seen substantial changes in allogeneic blood or marrow transplantation (BMT) practice, with the overarching goal of expanding the eligible patient pool while optimizing disease-free survival. OBJECTIVE: To determine trends in life expectancy and cause-specific late mortality after allogeneic BMT performed over a 40-year period. DESIGN, SETTING, AND PARTICIPANTS: A retrospective cohort study of 4741 individuals who lived 2 or more years after allogeneic BMT performed between January 1, 1974, and December 31, 2014, was conducted at City of Hope, University of Minnesota, or University of Alabama at Birmingham. The end of follow-up was March 23, 2020. EXPOSURES: Allogeneic BMT performed in 3 eras: 1974-1989, 1990-2004, and 2005-2014. MAIN OUTCOMES AND MEASURES: All-cause, recurrence-related, and nonrecurrence-related mortality and projected reduction in life expectancy. Information regarding vital status and cause of death was obtained from the National Death Index Plus and Accurint databases. RESULTS: Of the 4741 individuals included in the study, 2735 (57.7%) were male; median age at BMT was 33 years (range, 0-75 years). The cumulative incidence of recurrence-related mortality plateaued at 10 years, reaching 12.2% (95% CI, 11.0%-13.4%) at 30 years from BMT. In contrast, the incidence of nonrecurrence-related mortality continued to increase and was 22.3% (95% CI, 20.4%-24.3%) at 30 years. Leading causes of nonrecurrence-related mortality included infection (30-year cumulative incidence, 10.7%; standardized mortality ratio [SMR], 52.0), subsequent malignant neoplasms (30-year cumulative incidence, 7.0%; SMR, 4.8), cardiovascular disease (30-year cumulative incidence, 4.6%; SMR, 4.1), and pulmonary disease (30-year cumulative incidence, 2.7%; SMR, 13.9). Compared with the general population, the relative mortality remained higher at 30 or more years after BMT (SMR, 5.4; 95% CI, 4.0-7.1). The cohort experienced a 20.8% reduction in life expectancy (8.7 years of life lost). Compared with 1974-1989 (reference), the adjusted 10-year hazard ratio (HR) of all-cause mortality declined over the 3 eras (1990-2004: HR, 0.67; 95% CI, 0.53-0.85; 2005-2014: HR, 0.52; 95% CI, 0.39-0.69; P < .001 for trend), as did years of life lost (1974-1989: 9.9 years [reference]; 1990-2004: 6.5 years; and 2005-2014: 4.2 years). The reduction in late mortality was most pronounced among individuals who underwent transplantation at ages younger than 18 years (1990-2004: HR, 0.62; 95% CI, 0.40-0.96; 2005-2014: HR, 0.30; 95% CI, 0.16-0.54; reference: 1974-1989; P < .001 for trend) and those who received bone marrow (1990-2004: HR, 0.70; 95% CI, 0.54-0.90; 2005-2014: HR, 0.45; 95% CI, 0.29-0.69; reference: 1974-1989; P < .001 for trend). CONCLUSIONS AND RELEVANCE: This cohort study noted that late mortality among recipients of allogeneic BMT has decreased over the past 40 years; however, life expectancy was not restored to expected rates compared with the general US population. Furthermore, the reduction in risk of late mortality appeared to be confined to those who underwent transplantation at a younger age or those who received bone marrow. Further efforts to mitigate disease recurrence, infections, subsequent neoplasms, cardiovascular disease, and pulmonary disease may be useful in this population.

Genotype-phenotype association and variant characterization in Diamond-Blackfan anemia caused by pathogenic variants in RPL35A.

Diamond Blackfan anemia (DBA) is predominantly an autosomal dominant inherited red cell aplasia primarily caused by pathogenic germline variants in ribosomal protein genes. DBA due to pathogenic RPL35A variants has been associated with large 3q29 deletions and phenotypes not common in DBA. We conducted a multi-institutional genotype-phenotype study of 45 patients with DBA associated with pathogenic RPL35A germline variants and curated the variant data on 21 additional cases from the literature. Genotype-phenotype analyses were conducted comparing patients with large deletions versus all other pathogenic variants in RPL35A. Twenty-two of the 45 cases had large deletions in RPL35A. After adjusting for multiple tests, a statistically significant association was observed between patients with a large deletion and steroid-resistant anemia, neutropenia, craniofacial abnormalities, chronic gastrointestinal problems, and intellectual disabilities (p<0.01) compared with all other pathogenic variants. Non-large deletion pathogenic variants were spread across RPL35A with no apparent hot spot and 56% of the individual family variants were observed more than once. In this, the largest known study of DBA patients with pathogenic RPL35A variants, we determined that patients with large deletions have a more severe phenotype that is clinically different from those with non-large deletion variants. Genes of interest also deleted in the 3q29 region that could be associated with some of these phenotypic features include LMLN and IQCG. Management of DBA due to large RPL35A deletions may be challenging due to complex problems and require comprehensive assessments by multiple specialists including immunologic, gastrointestinal, and developmental evaluations to provide optimal multidisciplinary care.

Gastrointestinal Hemorrhage: A Manifestation of the Telomere Biology Disorders.

OBJECTIVE: To describe the clinical features, therapeutic interventions, and patient outcomes of gastrointestinal (GI) hemorrhage in individuals with a telomere biology disorder, including dyskeratosis congenita, Hoyeraal-Hreidarsson syndrome, Revesz syndrome, and Coats plus. STUDY DESIGN: Clinical Care Consortium for Telomere Associated Ailments members were invited to contribute data on individuals with telomere biology disorders at their institutions who experienced GI bleeding. Patient demographic, laboratory, imaging, procedural, and treatment information and outcomes were extracted from the medical record. RESULTS: Sixteen patients who experienced GI hemorrhage were identified at 11 centers. Among 14 patients who underwent genetic testing, 8 had mutations in TINF2, 4 had mutations in CTC1 or STN1, and 1 patient each had a mutation in TERC and RTEL1. Ten patients had a history of hematopoietic cell transplantation. The patients with Coats plus and those without Coats plus had similar clinical features and courses. Angiodysplasia of the stomach and/or small bowel was described in 8 of the 12 patients who underwent endoscopy; only 4 had esophageal varices. Various medical interventions were trialed. No single intervention was uniformly associated with cessation of bleeding, although 1 patient had a sustained response to treatment with bevacizumab. Recurrence was common, and the overall long-term outcome for affected patients was poor. CONCLUSIONS: GI bleeding in patients with telomere biology disorders is associated with significant morbidity and with vascular ectasias rather than varices.

Excellent outcomes following hematopoietic cell transplantation for Wiskott-Aldrich syndrome: a PIDTC report.

Wiskott-Aldrich syndrome (WAS) is an X-linked disease caused by mutations in the WAS gene, leading to thrombocytopenia, eczema, recurrent infections, autoimmune disease, and malignancy. Hematopoietic cell transplantation (HCT) is the primary curative approach, with the goal of correcting the underlying immunodeficiency and thrombocytopenia. HCT outcomes have improved over time, particularly for patients with HLA-matched sibling and unrelated donors. We report the outcomes of 129 patients with WAS who underwent HCT at 29 Primary Immune Deficiency Treatment Consortium centers from 2005 through 2015. Median age at HCT was 1.2 years. Most patients (65%) received myeloablative busulfan-based conditioning. With a median follow-up of 4.5 years, the 5-year overall survival (OS) was 91%. Superior 5-year OS was observed in patients <5 vs ≥5 years of age at the time of HCT (94% vs 66%; overall P = .0008). OS was excellent regardless of donor type, even in cord blood recipients (90%). Conditioning intensity did not affect OS, but was associated with donor T-cell and myeloid engraftment after HCT. Specifically, patients who received fludarabine/melphalan-based reduced-intensity regimens were more likely to have donor myeloid chimerism <50% early after HCT. In addition, higher platelet counts were observed among recipients who achieved full (>95%) vs low-level (5%-49%) donor myeloid engraftment. In summary, HCT outcomes for WAS have improved since 2005, compared with prior reports. HCT at a younger age continues to be associated with superior outcomes supporting the recommendation for early HCT. High-level donor myeloid engraftment is important for platelet reconstitution after either myeloablative or busulfan-containing reduced intensity conditioning. (This trial was registered at www.clinicaltrials.gov as #NCT02064933.).

Novel Engraftment and T Cell Differentiation of Human Hematopoietic Cells in ART-/-IL2RG-/Y SCID Pigs.

Pigs with severe combined immunodeficiency (SCID) are an emerging biomedical animal model. Swine are anatomically and physiologically more similar to humans than mice, making them an invaluable tool for preclinical regenerative medicine and cancer research. One essential step in further developing this model is the immunological humanization of SCID pigs. In this work we have generated T- B- NK- SCID pigs through site directed CRISPR/Cas9 mutagenesis of IL2RG within a naturally occurring DCLRE1C (ARTEMIS)-/- genetic background. We confirmed ART-/-IL2RG-/Y pigs lacked T, B, and NK cells in both peripheral blood and lymphoid tissues. Additionally, we successfully performed a bone marrow transplant on one ART-/-IL2RG-/Y male SCID pig with bone marrow from a complete swine leukocyte antigen (SLA) matched donor without conditioning to reconstitute porcine T and NK cells. Next, we performed in utero injections of cultured human CD34+ selected cord blood cells into the fetal ART-/-IL2RG-/Y SCID pigs. At birth, human CD45+ CD3ε+ cells were detected in cord and peripheral blood of in utero injected SCID piglets. Human leukocytes were also detected within the bone marrow, spleen, liver, thymus, and mesenteric lymph nodes of these animals. Taken together, we describe critical steps forwards the development of an immunologically humanized SCID pig model.

Hematopoietic Cell Transplantation in Patients With Primary Immune Regulatory Disorders (PIRD): A Primary Immune Deficiency Treatment Consortium (PIDTC) Survey.

Primary Immune Regulatory Disorders (PIRD) are an expanding group of diseases caused by gene defects in several different immune pathways, such as regulatory T cell function. Patients with PIRD develop clinical manifestations associated with diminished and exaggerated immune responses. Management of these patients is complicated; oftentimes immunosuppressive therapies are insufficient, and patients may require hematopoietic cell transplant (HCT) for treatment. Analysis of HCT data in PIRD patients have previously focused on a single gene defect. This study surveyed transplanted patients with a phenotypic clinical picture consistent with PIRD treated in 33 Primary Immune Deficiency Treatment Consortium centers and European centers. Our data showed that PIRD patients often had immunodeficient and autoimmune features affecting multiple organ systems. Transplantation resulted in resolution of disease manifestations in more than half of the patients with an overall 5-years survival of 67%. This study, the first to encompass disorders across the PIRD spectrum, highlights the need for further research in PIRD management.