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Background Patients with severe combined immunodeficiency disease who have matched sibling donors (MSDs) can proceed to hematopoietic cell transplantation (HCT) without conditioning chemotherapy. Objective We sought to determine whether the results of HCT without chemotherapy-based conditioning from matched unrelated donors (URDs), either from volunteer adults or umbilical cord blood, are comparable with those from MSDs.

Significance: Our study demonstrates the use of "IF-THEN" SynNotch-gated CAR-T cells targeting CD33 and CD123 in AML reduces off-tumor toxicity. This strategy enhances T-cell phenotype, improves expansion, preserves HSPCs, and mitigates cytokine release syndrome-addressing critical limitations of existing AML CAR-T therapies., (©2024 American Association for Cancer Research.)

Abstract: We hypothesized that the inferior disease-free survival (DFS) seen in older patients who underwent αβ-T-cell/CD19-depleted (AB-TCD) haploidentical hematopoietic cell transplantation (HCT) for hematologic malignancies is caused by excessive exposure to rabbit antithymocyte globulin (rATG; Thymoglobulin). Between 2015 and 2023, 163 patients with a median age of 13 years (range, 0.4-27.4) underwent AB-TCD haploidentical HCT for the treatment of acute lymphoblastic leukemia (n = 98), acute myeloid leukemia/myelodysplastic syndrome (n = 49), or other malignancies (n = 16) at 9 centers in 2 prospective trials. Exposures to rATG before and after HCT were predicted using a validated pharmacokinetic model. Receiver operating characteristic curves were used to identify the optimal target windows for rATG exposure in terms of outcomes. We identified 4 quadrants of rATG exposure, namely quadrant 1 (n = 52) with a high pre-HCT area under curve (AUC; ≥50 arbitrary units [AU] per day per milliliter) and a low post-HCT AUC (<12 AU per day per liter); quadrant 2 (n = 47) with a low pre- and post-HCT AUC; quadrant 3 (n = 13) with a low pre-HCT and a high post-HCT AUC; and quadrant 4 (n = 51) with a high pre- and post-HCT AUC. Quadrant 1 had a 3-year DFS of 86.5%, quadrant 2 had a DFS of 64.6%, quadrant 3 had a DFS of 32.9%, and for quadrant 4 it was 48.2%. An adjusted regression analysis demonstrated additional factors that were associated with an increased hazard for worse DFS, namely minimal residual disease (MRD) positivity and cytomegalovirus (CMV) R+/D- serostatus. Nonoptimal rATG exposure exhibited the strongest effect in unadjusted and adjusted (MRD status or CMV serostatus) analyses. High exposure to rATG after HCT was associated with inferior DFS following AB-TCD haploidentical HCT for pediatric patients with hematologic malignancies. Model-based dosing of rATG to achieve optimal exposure may improve DFS. These trials were registered at www.ClinicalTrials.gov as #NCT02646839 and #NCT04337515., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Allogeneic hematopoietic cell transplantation (HCT) is a potentially curative treatment for severe aplastic anemia (SAA). Existing guidance about HCT in SAA is primarily derived from expert reviews, registry data and societal guidelines; however, transplant-specific guidelines for SAA are lacking. A panel of SAA experts, both pediatric and adult transplant physicians, developed consensus recommendations using Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) methodology employing a GRADE guideline development tool. The panel agrees with previous recommendations for the preferential use of bone marrow as a graft source and the use of rabbit over horse antithymocyte globulin (ATG) for HCT conditioning. Fludarabine containing regimens are preferred for patients at high risk of graft failure and those receiving matched unrelated or haploidentical donor transplant. Given advancements in HCT, the panel does not endorse the historical 40-year age cut-off for considering upfront HCT in adults, acknowledging that fit older patients may also benefit from HCT. The panel also endorses increased utilization of HCT by prioritizing matched unrelated or haploidentical donor HCT over immunosuppressive therapy in children and adults who lack a matched related donor. Finally, the panel suggests either calcineurin inhibitor plus methotrexate or post-transplant cyclophosphamide-based graft-versus-host disease (GVHD) prophylaxis for matched related or matched unrelated donor recipients. These recommendations reflect a significant advancement in transplant strategies for SAA and highlight the importance of ongoing and further research to revisit current evidence in terms of donor choice, conditioning chemotherapy, GVHD prophylaxis and post-transplant immunosuppression., (Copyright © 2024 The American Society for Transplantation and Cellular Therapy. All rights reserved.)

Himatiichnus mangano igen. et isp. nov., a new trace fossil from the late Ediacaran Huns Member of the Urusis Formation, southern Namibia, comprises intertwining tubes exhibiting dual lineation patterns and reminiscent of both modern and early Cambrian examples of priapulid worm burrows. These similarities support the interpretation of a total-group scalidophoran tracemaker for H. mangano , thus providing direct evidence for the first appearance date of Scalidophora in the late Ediacaran ca 539 Ma. This new material is thus indicative of the presence of total-group scalidophorans below the Cambrian boundary and supports inference of a lengthy Precambrian fuse for the Cambrian explosion., Competing Interests: We declare we have no competing interests., (© 2024 The Author(s).)

Background: Almost all acquired severe aplastic anaemia is immune mediated and characterised by hypocellular bone marrow and ≥2 affected haematopoietic lineages. The optimal preparartive regimen for unrelated donor transplantation remains to be established. We aimed to study long-term outcomes after unrelated donor transplantation for severe aplastic anaemia with de-escalation of cyclophosphamide (Cy) dose in steps of 50 mg/kg (150, 100, 50, 0 mg/kg) in combination with total body irradiation (TBI) 2 Gy, anti-thymocyte globulin (ATG) and fludarabine., Methods: Ninety-six patients with severe aplastic anaemia aged ≤65 years with adequate organ function enrolled on a trial of human leukocyte antigen (HLA)-matched or 1 HLA-locus mismatched unrelated donor marrow transplantation conducted between 02/2006 and 12/2013 in the United States (NCT00326417). Exclusion criteria were Karnofsky performance status of less than 60, clonal cytogenetic abnormalities and inherited marrow failure syndormes. The primary outcome was day-100 engraftment (achievement of absolute neutrophil recovery to at least 0.5 × 10 9 /L without subsequent decline) and day-100 survival. The trial determined the lowest effective Cy dose as 50 mg/kg (n = 38) for day-100 engraftment and survival. Cy dose 100 mg/kg (n = 41) was also acceptable. Accrual to Cy doses 150 mg/kg (n = 15) and 0 mg/kg (n = 3) was terminated early for toxicities. The current study is an extended follow up of patients enrolled on the trial (NCT00326477) and includes 76 of 96 patients alive ≥1 year after transplantation. There were 20 deaths in the first year after transplantation (Cy 0 mg/kg [n = 2], Cy 50 mg/kg [n = 1], Cy 100 mg/kg [n = 10], Cy 150 mg/kg [n = 7]). Patients were followed prospectively from transplantation and data reported using standardized data collection forms until death, loss to follow up or last contact through November 2023. The incidence of graft failure was calculated using the cumulative incidence estimator and the probability of survival using the Kaplan-Meier estimator., Findings: The median follow up of the cohort is 8.02 (IQR) 5.16-10.12) years. With Cy 50 mg/kg, there was one graft failure and five deaths ≥1 year after transplantation. With Cy 100 mg/kg there was only one late death and no graft failure. The 8-year probabilities of survival were 85.0% (95% CI 67.3-93.5) and 75.6% (95% CI 59.4-86.1) after Cy 50 mg/kg and 100 mg/kg, respectively, P = 0.31. With Cy 0 mg/kg and 150 mg/kg, there were no graft failures or death ≥1 year after transplantation. Regardless of Cy dose 12 of 15 patients aged ≥50 years died., Interpretation: Cy 50 mg/kg or 100 mg/kg with TBI 2 Gy, ATG and fludarabine are effective conditioning regimens for unrelated donor marrow transplants for aplastic anaemia. Identification of an optimized transplantation approach for patients aged ≥50 years is needed., Funding: US National Institutes of Health., Competing Interests: MAP: Consulting fees from Pfizer, Cargo, Noavartis, Bluebird Bio, Vertex, Medexus, Equillium. Honoraria serving as DSMB member (Autlolos). SDR: Serves on the Community Advisory Board (SIRPant Immunotherapeutics) and stock options (SIRPant Immunotherapeutics). Other authors declare no competing interest., (© 2024 The Author(s).)

Abstract: Allogeneic hematopoietic cell transplantation is a life-saving procedure used to treat a variety of devastating diseases. It requires hematopoietic stem cells collected via filgrastim-mobilized peripheral blood stem cells (PBSCs) or bone marrow (BM) harvest from volunteer unrelated donors (URDs). There is a paucity of safety data regarding donors' long-term adverse events. This prospective, observational study combined PBSC donors enrolled in the NMDP Investigational New Drug trial and BM donors between 1 July 1999 and 30 September 2015. The primary objective was to describe the long-term incidence of myeloid malignancies. The secondary objectives included describing the long-term incidence of lymphoid malignancies, nonhematologic malignancies, autoimmune disorders, and thrombotic events. A total of 21 643 donors (14 530 PBSCs and 7123 BM) were included. The incidence rate of myeloid disorders per 100 000 person-years in donors of PBSCs was 2.53 (95% confidence interval [CI], 0.82-7.84) and in donors of BM, it was 4.13 (95% CI, 1.33-12.8). The incidence rate ratio of PBSCs/BM donors was 0.61 (95% CI, 0.12-3.03; P = .55). The incidence of other malignancies, autoimmunity, and thrombosis did not differ between the donor types. This comprehensive study of the long-term effects of filgrastim in URDs of PBSCs provides strong evidence that donors who receive filgrastim are not at an increased risk of these events compared with BM donors. It also provides reassurance to current donors undergoing stem cell mobilization as well as individuals considering joining stem cell registries, such as NMDP., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Infants with B-cell acute lymphoblastic leukemia (B-ALL) continue to have significantly worse outcomes compared to older children with B-ALL, and those with relapsed or refractory (R/R) infant ALL have especially dismal outcomes with conventional treatment. CD19-targeting chimeric antigen receptor (CAR) T-cell therapy has demonstrated remarkable success in the treatment of R/R childhood B-ALL, though the majority of reports have been in non-infant patients. Barriers to the successful implementation of CAR T-cell therapy in infant B-ALL include challenges related to apheresis, product manufacturing and disease-specific considerations such as lineage switch. We describe our experience utilizing two experimental CD19-CAR T-cell products, SCRI-CAR19 or SCRI-CAR19x22, for 19 patients with R/R infant B-ALL enrolled on three clinical trials. CAR T-cell products were successfully manufactured in 18/19 (94.7%) patients, with a median age of 22.5 months at enrollment (range, 14.5-40.1 months). Sixteen of 17 (94.1%) treated patients achieved a complete remission without detectable minimal residual disease. The 1-year leukemia free survival was 75% and 1-year overall survival was 76.5%, with a median follow up time of 35.8 months (range, 1.7-83.6 months). Cytokine release syndrome (CRS) occurred in 14/17 (82.4%) patients, with only 1 patient experiencing Grade 3 CRS. Neurotoxicity occurred in 2/17 (11.8%) patients with all events ≤ Grade 2. With the successful early clinical experience of CAR T-cell therapy in this population, more systematic evaluation specific to infant ALL is warranted., (Copyright © 2024 American Society of Hematology.)

Abstract: Measurable residual disease (MRD) evaluation by multiparameter flow cytometry (MFC) or quantitative polymerase chain reaction methods is an established standard of care for assessing risk of relapse before or after hematopoietic cell transplantation (HCT) for acute lymphoblastic leukemia (ALL). Next-generation sequencing (NGS)-MRD has emerged as a highly effective approach that allows for the detection of lymphoblasts at a level of <1 in 106 nucleated cells, increasing sensitivity of ALL detection by 2 to 3 logs. Early studies have shown superior results compared with MFC and suggest that NGS-MRD may allow for the determination of patients in whom reduced toxicity transplant preparative approaches could be deployed without sacrificing outcomes. Many centers/study groups have implemented immune modulation approaches based on MRD measurements that have resulted in improved outcomes. Challenges remain with NGS-MRD, because it is not commercially available in many countries, and interpretation of results can be complex. Through patient case review, discussion of relevant studies, and detailed expert opinion, we share our approach to NGS-MRD testing before and after HCT in pediatric and adult ALL. Improved pre-HCT risk classification and post-HCT monitoring for relapse in bone marrow and less invasive peripheral blood monitoring by NGS-MRD may lead to alternative approaches to prevent relapse in patients undergoing this challenging procedure., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Hematopoietic cell transplantation (HCT) uses cytotoxic chemotherapy and/or radiation followed by intravenous infusion of stem cells to cure malignancies, bone marrow failure and inborn errors of immunity, hemoglobin and metabolism. Lung injury is a known complication of the process, due in part to disruption in the pulmonary microenvironment by insults such as infection, alloreactive inflammation and cellular toxicity. How microorganisms, immunity and the respiratory epithelium interact to contribute to lung injury is uncertain, limiting the development of prevention and treatment strategies. Here we used 278 bronchoalveolar lavage (BAL) fluid samples to study the lung microenvironment in 229 pediatric patients who have undergone HCT treated at 32 children's hospitals between 2014 and 2022. By leveraging paired microbiome and human gene expression data, we identified high-risk BAL compositions associated with in-hospital mortality (P = 0.007). Disadvantageous profiles included bacterial overgrowth with neutrophilic inflammation, microbiome contraction with epithelial fibroproliferation and profound commensal depletion with viral and staphylococcal enrichment, lymphocytic activation and cellular injury, and were replicated in an independent cohort from the Netherlands (P = 0.022). In addition, a broad array of previously occult pathogens was identified, as well as a strong link between antibiotic exposure, commensal bacterial depletion and enrichment of viruses and fungi. Together these lung-immune system-microorganism interactions clarify the important drivers of fatal lung injury in pediatric patients who have undergone HCT. Further investigation is needed to determine how personalized interpretation of heterogeneous pulmonary microenvironments may be used to improve pediatric HCT outcomes., (© 2024. The Author(s).)

Acute graft versus host disease (GVHD) is a common and serious complication of allogeneic hematopoietic cell transplantation (HCT) in children but overall clinical grade at onset only modestly predicts response to treatment and survival outcomes. Two tools to assess risk at initiation of treatment were recently developed. The Minnesota risk system stratifies children for risk of nonrelapse mortality (NRM) according to the pattern of GVHD target organ severity. The Mount Sinai Acute GVHD International Consortium (MAGIC) algorithm of 2 serum biomarkers (ST2 and REG3α) predicts NRM in adult patients but has not been validated in a pediatric population. We aimed to develop and validate a system that stratifies children at the onset of GVHD for risk of 6-month NRM. We determined the MAGIC algorithm probabilities (MAPs) and Minnesota risk for a multicenter cohort of 315 pediatric patients who developed GVHD requiring treatment with systemic corticosteroids. MAPs created 3 risk groups with distinct outcomes at the start of treatment and were more accurate than Minnesota risk stratification for prediction of NRM (area under the receiver operating curve (AUC), .79 versus .62, P = .001). A novel model that combined Minnesota risk and biomarker scores created from a training cohort was more accurate than either biomarkers or clinical systems in a validation cohort (AUC .87) and stratified patients into 2 groups with highly different 6-month NRM (5% versus 38%, P < .001). In summary, we validated the MAP as a prognostic biomarker in pediatric patients with GVHD, and a novel risk stratification that combines Minnesota risk and biomarker risk performed best. Biomarker-based risk stratification can be used in clinical trials to develop more tailored approaches for children who require treatment for GVHD., (Copyright © 2024 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Background: P47phox (neutrophil cytosolic factor-1) deficiency is the most common cause of autosomal recessive chronic granulomatous disease (CGD) and is considered to be associated with a milder clinical phenotype. Allogeneic hematopoietic cell transplantation (HCT) for p47phox CGD is not well-described., Objectives: We sought to study HCT for p47phox CGD in North America., Methods: Thirty patients with p47phox CGD who received allogeneic HCT at Primary Immune Deficiency Treatment Consortium centers since 1995 were included., Results: Residual oxidative activity was present in 66.7% of patients. In the year before HCT, there were 0.38 CGD-related infections per person-years. Inflammatory diseases, predominantly of the lungs and bowel, occurred in 36.7% of the patients. The median age at HCT was 9.1 years (range 1.5-23.6 years). Most HCTs (90%) were performed after using reduced intensity/toxicity conditioning. HCT sources were HLA-matched (40%) and -mismatched (10%) related donors or HLA-matched (36.7%) and -mismatched (13.3%) unrelated donors. CGD-related infections after HCT decreased significantly to 0.06 per person-years (P = .038). The frequency of inflammatory bowel disease and the use of steroids also decreased. The cumulative incidence of graft failure and second HCT was 17.9%. The 2-year overall and event-free survival were 92.3% and 82.1%, respectively, while at 5 years they were 85.7% and 77.0%, respectively. In the surviving patients evaluated, ≥95% donor myeloid chimerism at 1 and 2 years after HCT was 93.8% and 87.5%, respectively., Conclusions: Patients with p47phox CGD suffer from a significant disease burden that can be effectively alleviated by HCT. Similar to other forms of CGD, HCT should be considered for patients with p47phox CGD., (Copyright © 2024 American Academy of Allergy, Asthma & Immunology. All rights reserved.)

Chronic graft-versus-host-disease (cGVHD) is divided into two subtypes: classic (absence of acute GVHD features) and overlap cGVHD ('ocGVHD'), in which both chronic and acute GVHD clinical features are present simultaneously. While worse outcomes with ocGVHD have been reported, there are few recent analyses. We performed a secondary analysis of data from the ABA2 trial (N = 185), in which detailed GVHD data were collected prospectively and systematically adjudicated. Analyses included cumulative incidence of classic versus ocGVHD, their specific organ manifestations, global disease severity scores, non-relapse mortality (NRM), disease-free survival (DFS) and overall survival (OS) in these two cGVHD subtypes. Of 92 patients who developed cGVHD, 35 were classified as ocGVHD. The 1-year cumulative incidence, organ involvement, and global severity of classic and ocGVHD were similar between ABA2 patients receiving CNI/MTX+placebo and CNI/MTX+abatacept; thus, cohorts were combined for ocGVHD evaluation. This analysis identified ocGVHD as having significantly higher severity at presentation and at maximum global severity compared to classic cGVHD. OS and DFS were significantly lower for ocGVHD versus classic cGVHD. OcGVHD is associated with increased cGVHD severity scores, and is associated with decreased OS and DFS compared to classic cGVHD, underscoring the high risks with this cGVHD subtype., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Viral infections remain a major risk in immunocompromised pediatric patients, and virus-specific T cell (VST) therapy has been successful for treatment of refractory viral infections in prior studies. We performed a phase II multicenter study (NCT03475212) for the treatment of pediatric patients with inborn errors of immunity and/or post allogeneic hematopoietic stem cell transplant with refractory viral infections using partially-HLA matched VSTs targeting cytomegalovirus, Epstein-Barr virus, or adenovirus. Primary endpoints were feasibility, safety, and clinical responses (>1 log reduction in viremia at 28 days). Secondary endpoints were reconstitution of antiviral immunity and persistence of the infused VSTs. Suitable VST products were identified for 75 of 77 clinical queries. Clinical responses were achieved in 29 of 47 (62%) of patients post-HSCT including 73% of patients evaluable at 1-month post-infusion, meeting the primary efficacy endpoint (>52%). Secondary graft rejection occurred in one child following VST infusion as described in a companion article. Corticosteroids, graft-versus-host disease, transplant-associated thrombotic microangiopathy, and eculizumab treatment correlated with poor response, while uptrending absolute lymphocyte and CD8 T cell counts correlated with good response. This study highlights key clinical factors that impact response to VSTs and demonstrates the feasibility and efficacy of this therapy in pediatric HSCT., (© 2024. The Author(s).)

Although unrelated-donor (URD) hematopoietic cell transplantation (HCT) is associated with many toxicities, a detailed analysis of adverse events, as defined by the Common Terminology Criteria for Adverse Events (CTCAE), has not previously been curated. This represents a major unmet need, especially as it relates to assessing the safety of novel agents. We analyzed a detailed AE database from the "ABA2" randomized, double-blind, placebo-controlled clinical trial of abatacept for acute graft-versus-host disease (AGVHD) prevention, for which the FDA mandated a detailed AE assessment through Day +180, and weekly neutrophil and platelet counts through Day +100. These were analyzed for their relationship to key transplant outcomes, with a major focus on the impact of AGVHD on the development/severity of AEs. A total of 2102 AEs and 1816 neutrophil/platelet counts were analyzed from 142 8/8-HLA-matched URD HCT recipients on ABA2 (placebo cohort, n = 69, abatacept cohort, n = 73). This analysis resulted in 2 major observations. (1) Among graft source, conditioning intensity, age, and Grade 2 to 4 AGVHD, only AGVHD impacted Grade 3 to 5 AE acquisition after the first month post-transplant. (2) The development of Grade 3 to 4 AGVHD was associated with thrombocytopenia. We have created a detailed resource for the transplant community by which to contextualize clinical toxicities after transplant. It has identified AGVHD as a major driver of post-HCT Grade 3 to 5 AEs, and underscored a link between AGVHD and thrombocytopenia. This establishes a critical safety framework upon which the impact of novel post-transplant AGVHD therapeutics should be evaluated. This trial was registered at www.clinicaltrials.gov (#NCT01743131)., (Copyright © 2024. Published by Elsevier Inc.)

Severe combined immunodeficiency (SCID) is characterized by a severe deficiency in T cell numbers. We analyzed data collected (n = 307) for PHA-based T cell proliferation from the PIDTC SCID protocol 6901, using either a radioactive or flow cytometry method. In comparing the two groups, a smaller number of the patients tested by flow cytometry had <10% of the lower limit of normal proliferation as compared to the radioactive method (p = 0.02). Further, in patients with CD3+ T cell counts between 51 and 300 cells/μL, there was a higher proliferative response with the PHA flow assay compared to the 3 H-T assay (p < 0.0001), suggesting that the method of analysis influences the resolution and interpretation of PHA results. Importantly, we observed many SCID patients with profound T cell lymphopenia having normal T cell proliferation when assessed by flow cytometry. We recommend this test be considered only as supportive in the diagnosis of typical SCID., Competing Interests: Declaration of competing interest RSA has been on the advisory board for Horizon Pharma (now Amgen) and Sobi in the past 2 years but is not currently serving in that capacity. RM is an employee of Pharming Healthcare Inc., Warren, NJ. JWL is an employee and shareholder of Bluebird Bio, and has been a speaker/consultant and on the advisory board for Sobi, Inc., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Virus-specific T cells (VST) from partially-HLA matched donors have been effective for treatment of refractory viral infections in immunocompromised patients in prior studies with a good safety profile, but rare adverse events have been described. Here we describe a unique and severe adverse event of VST therapy in an infant with severe combined immunodeficiency, who receives, as part of a clinical trial (NCT03475212), third party VSTs for treating cytomegalovirus viremia following bone marrow transplantation. At one-month post-VST infusion, rejection of graft and reversal of chimerism is observed, as is an expansion of T cells exclusively from the VST donor. Single-cell gene expression and T cell receptor profiling demonstrate a narrow repertoire of predominantly activated CD4 + T cells in the recipient at the time of rejection, with the repertoire overlapping more with that of peripheral blood from VST donor than the infused VST product. This case thus demonstrates a rare but serious side effect of VST therapy., (© 2024. The Author(s).)

Background: The Primary Immune Deficiency Treatment Consortium (PIDTC) enrolled children in the United States and Canada onto a retrospective multicenter natural history study of hematopoietic cell transplantation (HCT)., Objective: We investigated outcomes of HCT for severe combined immunodeficiency (SCID)., Methods: We evaluated the chronic and late effects (CLE) after HCT for SCID in 399 patients transplanted from 1982 to 2012 at 32 PIDTC centers. Eligibility criteria included survival to at least 2 years after HCT without need for subsequent cellular therapy. CLE were defined as either conditions present at any time before 2 years from HCT that remained unresolved (chronic), or new conditions that developed beyond 2 years after HCT (late)., Results: The cumulative incidence of CLE was 25% in those alive at 2 years, increasing to 41% at 15 years after HCT. CLE were most prevalent in the neurologic (9%), neurodevelopmental (8%), and dental (8%) categories. Chemotherapy-based conditioning was associated with decreased-height z score at 2 to 5 years after HCT (P < .001), and with endocrine (P < .001) and dental (P = .05) CLE. CD4 count of ≤500 cells/μL and/or continued need for immunoglobulin replacement therapy >2 years after transplantation were associated with lower-height z scores. Continued survival from 2 to 15 years after HCT was 90%. The presence of any CLE was associated with increased risk of late death (hazard ratio, 7.21; 95% confidence interval, 2.71-19.18; P < .001)., Conclusion: Late morbidity after HCT for SCID was substantial, with an adverse impact on overall survival. This study provides evidence for development of survivorship guidelines based on disease characteristics and treatment exposure for patients after HCT for SCID., (Copyright © 2023. Published by Elsevier Inc.)

Chronic granulomatous disease (CGD) is a primary immunodeficiency characterized by life-threatening infections and inflammatory conditions. Hematopoietic cell transplantation (HCT) is the definitive treatment for CGD, but questions remain regarding patient selection and impact of active disease on transplant outcomes. We performed a multi-institutional retrospective and prospective study of 391 patients with CGD treated either conventionally (non-HCT) enrolled from 2004 to 2018 or with HCT from 1996 to 2018. Median follow-up after HCT was 3.7 years with a 3-year overall survival of 82% and event-free survival of 69%. In a multivariate analysis, a Lansky/Karnofsky score <90 and use of HLA-mismatched donors negatively affected survival. Age, genotype, and oxidase status did not affect outcomes. Before HCT, patients had higher infection density, higher frequency of noninfectious lung and liver diseases, and more steroid use than conventionally treated patients; however, these issues did not adversely affect HCT survival. Presence of pre-HCT inflammatory conditions was associated with chronic graft-versus-host disease. Graft failure or receipt of a second HCT occurred in 17.6% of the patients and was associated with melphalan-based conditioning and/or early mixed chimerism. At 3 to 5 years after HCT, patients had improved growth and nutrition, resolved infections and inflammatory disease, and lower rates of antimicrobial prophylaxis or corticosteroid use compared with both their baseline and those of conventionally treated patients. HCT leads to durable resolution of CGD symptoms and lowers the burden of the disease. Patients with active infection or inflammation are candidates for transplants; HCT should be considered before the development of comorbidities that could affect performance status. This trial was registered at www.clinicaltrials.gov as #NCT02082353.

Background: Chronic granulomatous disease (CGD) is caused by defects in any 1 of the 6 subunits forming the nicotinamide adenine dinucleotide phosphate oxidase complex 2 (NOX2), leading to severely reduced or absent phagocyte-derived reactive oxygen species production. Almost 50% of patients with CGD have inflammatory bowel disease (CGD-IBD). While conventional IBD therapies can treat CGD-IBD, their benefits must be weighed against the risk of infection. Understanding the impact of NOX2 defects on the intestinal microbiota may lead to the identification of novel CGD-IBD treatments., Objective: We sought to identify microbiome and metabolome signatures that can distinguish individuals with CGD and CGD-IBD., Methods: We conducted a cross-sectional observational study of 79 patients with CGD, 8 pathogenic variant carriers, and 19 healthy controls followed at the National Institutes of Health Clinical Center. We profiled the intestinal microbiome (amplicon sequencing) and stool metabolome, and validated our findings in a second cohort of 36 patients with CGD recruited through the Primary Immune Deficiency Treatment Consortium., Results: We identified distinct intestinal microbiome and metabolome profiles in patients with CGD compared to healthy individuals. We observed enrichment for Erysipelatoclostridium spp, Sellimonas spp, and Lachnoclostridium spp in CGD stool samples. Despite differences in bacterial alpha and beta diversity between the 2 cohorts, several taxa correlated significantly between both cohorts. We further demonstrated that patients with CGD-IBD have a distinct microbiome and metabolome profile compared to patients without CGD-IBD., Conclusion: Intestinal microbiome and metabolome signatures distinguished patients with CGD and CGD-IBD, and identified potential biomarkers and therapeutic targets., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Although CD19-directed chimeric antigen receptor (CAR) T cell therapy (CAR-T) for relapsed/refractory B cell acute lymphoblastic leukemia (B-ALL) has been transformative in inducing and sustaining remission, relapse rates remain unacceptably high, with approximately 50% of children and young adults experiencing relapse within the first year postinfusion. Emerging strategies to extend the durability of remission involve the use of prognostic biomarkers to identify those at high risk of relapse or incorporate strategies aimed to enhancing functional CAR T cell persistence. Nonetheless, with antigen loss/down-regulation or evolution to lineage switch as major mechanisms of relapse, optimizing single antigen targeting alone is insufficient. Here, with a focus on relapse prevention strategies, including postinfusion surveillance and treatment approaches being explored to optimize post-CAR-T management (eg, combinatorial antigen targeting strategies, preemptive hematopoietic cell transplantation), we review the current state of the art in the prevention and management of post CAR-T relapse. We highlight the advancements in the field and identify gaps in the literature to guide future research in optimizing the prevention and management of post-CAR-T relapse in children and young adults with B-ALL., (Copyright © 2023. Published by Elsevier Inc.)

Chimeric antigen receptor (CAR) T cell therapy (CAR-T) targeting the CD19 antigen on B cell acute lymphoblastic leukemia (B-ALL) has transitioned from a highly investigational therapy with limited access to a commercial therapy with established toxicities, response and survival rates, and access in numerous countries. With more than a decade of clinical study and 5 years of commercial access, data showing associations with success and failure have emerged. To address functional limitations of CAR-T and overcome constrained sample sizes when studying single-trial or single-center data, collaborative groups, including the Pediatric Real World CAR Consortium, the CAR-Multicenter Analysis, the Center for International Blood and Marrow Transplant Research, and the International BFM Study Group, among others, have been retrospectively interrogating the amassed clinical experience. The high patient numbers and varied clinical experiences compiled by these groups have defined clinical variables impacting CAR-T outcomes. Here we review published CAR-T trials and consortium/collaborative outcomes to establish variables associated with optimal response to CAR-T in children and young adults with B-ALL. We focus on findings with clinical relevance that have emerged, including data implicating pretreatment disease burden, presence of extramedullary disease, nonresponse to prior CD19 antigen targeting (blinatumomab therapy), CAR T cell dose, and fludarabine pharmacokinetics as factors impacting post-CAR-T survival. Additionally, we address the role of collaborative efforts going forward in guiding clinical practice evolution and further optimizing post-CAR-T outcomes., (Copyright © 2023 The American Society for Transplantation and Cellular Therapy. All rights reserved.)

Promising results have been reported for adult patients with high-risk hematologic malignancies undergoing haploidentical bone marrow transplant (haploBMT) with posttransplant cyclophosphamide (PTCy). To our knowledge, we report results from the first multicenter trial for pediatric and young adult patients with high-risk acute leukemias and myelodysplastic syndrome (MDS) in the Pediatric Transplantation and Cellular Therapy Consortium. Nine centers performed transplants in 32 patients having acute leukemias or MDS, with myeloablative conditioning (MAC), haploBMT with PTCy, mycophenolate mofetil, and tacrolimus. The median patient age was 12 years. Diagnoses included AML (15), ALL (11), mixed-lineage leukemia (1), and MDS (5). Transplant-related mortality (TRM) at 180 days was 0%. The cumulative incidence (CuI) of grade 2 acute graft-versus-host disease (aGVHD) on day 100 was 13%. No patients developed grades 3-4 aGVHD. The CuI of moderate-to-severe chronic GVHD (cGVHD) at 1 year was 4%. Donor engraftment occurred in 27 patients (84%). Primary graft failures included 3 patients who received suboptimal bone marrow grafts; all successfully engrafted after second transplants. The CuI of relapse at 1 year was 32%, with more relapse among patients MRD positive pre-BMT vs MRD negative. Overall survival rates at 1 and 2 years were 77% and 73%, and event-free survival rate at 1 and 2 years were 68% and 64%. There was no TRM or severe aGVHD, low cGVHD, and favorable relapse and survival rates. This successful pilot trial has led to a phase 3 trial comparing MAC haploBMT vs HLA-matched unrelated donor BMT in the Children's Oncology Group. This trial was registered at www.clinicaltrials.gov as #NCT02120157., (Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

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., (© 2023 Wiley Periodicals LLC.)

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology , to patients seen in their own clinical practice., Background: The Children's Oncology Group (COG) AALL1331 trial demonstrated improved survival and less toxicity in children with high-/intermediate-risk relapsed ALL receiving blinatumomab compared with intensive chemotherapy before hematopoietic stem-cell transplant (HSCT). The low-risk arm of AALL1331 compared addition of three cycles of blinatumomab to chemotherapy alone, but a survival improvement was not noted. Secondary analyses showed improvement in disease-free survival (DFS) and overall survival (OS) of low-risk patients with bone marrow disease ± extramedullary (EM) involvement (4-year DFS 72.7% ± 5.8% v 53.7% ± 6.7%; 4-year OS 97.1% ± 2.1% v 84.8% ± 4.8%), but failed to show an advantage with blinatumomab for patients with isolated EM relapse. Of note, DFS of isolated CNS (iCNS) relapse was worse than previous studies at 24% on both arms, likely because of decreases in CNS-intensive therapy compared with previous approaches and inadequacy of blinatumomab for controlling CNS disease., Case: Our case of late isolated CNS B-cell ALL relapse outlines challenges for clinicians attempting to decrease toxicity and avoid HSCT: (1) defining of low risk appropriately, (2) attempting to reduce the treatment burden of past protocols, and (3) understanding approach and timing of cranial irradiation., Approach: Although AALL1331 therapy without blinatumomab leads to excellent survival in patients with isolated testicular relapse, we recommend a modified AALL02P2 backbone of chemotherapy with 1,800 cGy cranial radiotherapy for patients with late iCNS relapse. Future studies integrating chimeric antigen receptor T cells, which have better CNS penetration, may help decrease the intensive treatment burden for patients with late iCNS recurrence.

In the ABA2 study, the T-cell costimulation blockade agent, abatacept, was safe and effective in preventing acute graft-versus-host disease (aGVHD) after unrelated-donor hematopoietic cell transplant (HCT), leading to US Food and Drug Administration approval. Here, we performed a determination of abatacept pharmacokinetics (PK), which enabled an examination of how abatacept exposure-response relationships affected clinical outcomes. We performed a population PK analysis of IV abatacept using nonlinear mixed-effect modeling and assessed the association between abatacept exposure and key transplant outcomes. We tested the association between the trough after dose 1 (Ctrough&#95;1) and grade (GR) 2 or 4 aGVHD (GR2-4 aGVHD) through day +100. An optimal Ctrough&#95;1 threshold was identified via recursive partitioning and classification tree analysis. This demonstrated that abatacept PK was characterized by a 2-compartment model with first-order elimination. The ABA2 dosing regimen was based on previous work targeting a steady-state abatacept trough of 10 μg/mL. However, a higher Ctrough&#95;1 (≥39 μg/mL, attained in ∼60% of patients on ABA2) was associated with a favorable GR2-4 aGVHD risk (hazard ratio, 0.35; 95% confidence interval, 0.19-0.65; P < .001), with a Ctrough&#95;1 <39 μg/mL associated with GR2-4 aGVHD risk indistinguishable from placebo (P = .37). Importantly, no significant association was found between Ctrough&#95;1 and key safety indicators, including relapse, and cytomegalovirus or Epstein-Barr virus viremia. These data demonstrate that a higher abatacept Ctrough&#95;1 (≥39 μg/mL) was associated with a favorable GR2-4 aGVHD risk, without any observed exposure-toxicity relationships. This trial was registered at www.clinicaltrials.gov as #NCT01743131., (© 2023 by The American Society of Hematology.)

The National Institutes of Health Consensus criteria for chronic graft-versus-host disease (cGVHD) diagnosis can be challenging to apply in children, making pediatric cGVHD diagnosis difficult. We aimed to identify diagnostic pediatric cGVHD biomarkers that would complement the current clinical criteria and help differentiate cGVHD from non-cGVHD. The Applied Biomarkers of Late Effects of Childhood Cancer (ABLE) study, open at 27 transplant centers, prospectively evaluated 302 pediatric patients after hematopoietic cell transplant (234 evaluable). Forty-four patients developed cGVHD. Mixed and fixed effect regression analyses were performed on diagnostic cGVHD onset blood samples for cellular and plasma biomarkers, with individual markers declared relevant if they met 3 criteria: an effect ratio ≥1.3 or ≤0.75; an area under the curve (AUC) of ≥0.60; and a P value <5.814 × 10-4 (Bonferroni correction) (mixed effect) or <.05 (fixed effect). To address the complexity of cGVHD diagnosis in children, we built a machine learning-based classifier that combined multiple cellular and plasma biomarkers with clinical factors. Decreases in regulatory natural killer cells, naïve CD4 T helper cells, and naïve regulatory T cells, and elevated levels of CXCL9, CXCL10, CXCL11, ST2, ICAM-1, and soluble CD13 (sCD13) characterize the onset of cGVHD. Evaluation of the time dependence revealed that sCD13, ST2, and ICAM-1 levels varied with the timing of cGVHD onset. The cGVHD diagnostic classifier achieved an AUC of 0.89, with a positive predictive value of 82% and a negative predictive value of 80% for diagnosing cGVHD. Our polyomic approach to building a diagnostic classifier could help improve the diagnosis of cGVHD in children but requires validation in future prospective studies. This trial was registered at www.clinicaltrials.gov as #NCT02067832., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Overall survival after reduced-intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (HCT) using alemtuzumab, fludarabine, and melphalan is associated with high rates of mixed chimerism (MC) and secondary graft failure (GF). We hypothesized that peritransplantation alemtuzumab levels or specific patterns of inflammation would predict these risks. We assessed samples from the Bone Marrow Transplant Clinical Trials Network 1204 (NCT01998633) to study the impact of alemtuzumab levels and cytokine patterns on MC and impending or established secondary GF (defined as donor chimerism <5% after initial engraftment and/or requirement of cellular intervention). Thirty-three patients with hemophagocytic lymphohistiocytosis (n = 25) and other IEIs (n = 8) who underwent HCTs with T-cell-replete grafts were included. Patients with day 0 alemtuzumab levels ≤0.32 μg/mL had a markedly lower incidence of MC, 14.3%, vs 90.9% in patients with levels >0.32 μg/mL (P = .008). Impending or established secondary GF was only observed in patients with day 0 alemtuzumab levels >0.32 μg/mL (P = .08). Unexpectedly, patients with impending or established secondary GF had lower CXCL9 levels. The cumulative incidence of impending or established secondary GF in patients with a day 14+ CXCL9 level ≤2394 pg/mL (day 14+ median) was 73.6% vs 0% in patients with a level >2394 pg/mL (P = .002). CXCL9 levels inversely correlated with alemtuzumab levels. These data suggest a model in which higher levels of alemtuzumab at day 0 deplete donor T cells, inhibit the graft-versus-marrow reaction (thereby suppressing CXCL9 levels), and adversely affect sustained engraftment in the nonmyeloablative HCT setting. This trial was registered at www.clinicaltrials.gov as #NCT01998633., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

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 χ 2 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., Competing Interests: Declaration of interests MST is a member of the Scientific Advisory Board for Proteios Technology. JMP has received royalties from Up-To-Date, and her spouse is employed by and owns stock in Invitae (a DNA sequencing company). MJC has received royalties from Up-to-Date and is on the scientific board of Homology Medicines, a gene therapy company, and is a data and safety monitoring board (DSMB) member for Bluebird Bio, Chiesi USA, and Rocket Pharmaceuticals. LFS is a member of the adjudication committee for Orchard Therapeutics and has received consulting fees from Takeda, CSL Behring, ADMA Biologics, Grifols, and Horizon. JH is on an Investigator-initiated grant at CSL Behring; is a consultant for ADMA, Horizon, and CIRM; and a clinical trial primary investigator (industry sponsored research) for Regeneron. LMB has received clinical trial support through the Fred Hutchinson Cancer Research Center by Medac including supply of treosulfan), is a member of the DSMB for clinical trials with Rocket Pharmaceuticals and Jasper Therapeutics, and has served on an advisory board for Horizon Therapeutics USA. BDS has undertaken ad-hoc consultancies for Sobi and Orchard Therapeutics. ShC is a member on the advisory board for SOBI. JJB is a member of an advisory board for Sobi and Horizon Therapeutics. GDEC has received consultancy fees from Miltenyi Biotech. FDG has received consultancy fees from GLG and Guidepoint Global, and is on the advisory board for Omerus. EBS is on the speaker's bureau for Sobi. EHC is an advisory board member for Pfizer. SP has received funding for the conduct of sponsored trials Atara Biotherapeutics, AlloVir, and Jasper Therapeutics and is on the advisory board for ADMA and Neovii; and is the inventor of IP Licensed to Atara with all rights assigned to Memorial Sloan Kettering Cancer Center. KES has served as a consultant for Enzyvant and the Immune Deficiency Foundation. AP is on the advisory boards for Orchard (MLD GT), Horizon, and Enzyvant, serves on the DSMB for ExCellTheraMK, and is a consultant for Enzyvant (2020). TCQ has been on the speaker's bureau and advisory board for Alexion Pharmaceuticals. SS is on the advisory board and provides consultancy for Graphite, Takeda, Janssen, Bristol Myers Squibb, data and safety monitoring committee for the National Heart, Lung, and Blood Institute (NHLBI), and Aruvant Sciences. HD was an advisor on an Eli Lilly Canada Scientific Advisory Board in April 2020. JWL in the past 12 months has been a speaker and consultant for Sobi; has been a speaker and consultant, and has received research funding from Horizon Therapeutics; has been a speaker, consultant, and on an advisory board for Pharming; has been a speaker and consultant for CSL Behring; is on the advisory board for ADMA Biologics; and is the site primary investigator for Therapure and a GreenCross employee and shareholder at Bluebird Bio. MAP has served on the advisory boards of Novartis, Medexus, Equillium, and Mesoblast; has received clinical study support from Adaptive and Miltenyi Biotech; and has received financial support for educational lectures for Miltenyi Biotech and Novartis. DBK is an inventor for the UC Regents on a lentiviral vector for gene therapy of ADA-SCID and is a member of the DSMB for Revcovi PEG-ADA (Chiesi USA). EH has received consultancy fees from JASPERS, Takeda, CSL-Behring, Octapharma, and Leadiant Biosciences. CCD is a member of the DSMB for Revcovi PEG-ADA and is a consultant for Orchard Therapeutics. All other authors declare no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

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 >3.6×10 6 /kg CD34 + cells experienced superior PFS (p = .04) and OS (p = .04) compared to children receiving ≤3.6 × 10 6 /kg. Relapse rates were lower in patients receiving >3.6 × 10 6 /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 × 10 8 /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., (Copyright © 2023 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Purpose: To report the incidence and risk factors for secondary neoplasm after transplantation for sickle cell disease., Methods: Included are 1,096 transplants for sickle cell disease between 1991 and 2016. There were 22 secondary neoplasms. Types included leukemia/myelodysplastic syndrome (MDS; n = 15) and solid tumor (n = 7). Fine-Gray regression models examined for risk factors for leukemia/MDS and any secondary neoplasm., Results: The 10-year incidence of leukemia/MDS was 1.7% (95% CI, 0.90 to 2.9) and of any secondary neoplasm was 2.4% (95% CI, 1.4 to 3.8). After adjusting for other risk factors, risks for leukemia/MDS (hazard ratio, 22.69; 95% CI, 4.34 to 118.66; P = .0002) or any secondary neoplasm (hazard ratio, 7.78; 95% CI, 2.20 to 27.53; P = .0015) were higher with low-intensity (nonmyeloablative) regimens compared with more intense regimens. All low-intensity regimens included total-body irradiation (TBI 300 or 400 cGy with alemtuzumab, TBI 300 or 400 cGy with cyclophosphamide, TBI 200, 300, or 400 cGy with cyclophosphamide and fludarabine, or TBI 200 cGy with fludarabine). None of the patients receiving myeloablative and only 23% of those receiving reduced-intensity regimens received TBI., Conclusion: Low-intensity regimens rely on tolerance induction and establishment of mixed-donor chimerism. Persistence of host cells exposed to low-dose radiation triggering myeloid malignancy is one plausible etiology. Pre-existing myeloid mutations and prior inflammation may also contribute but could not be studied using our data source. Choosing conditioning regimens likely to result in full-donor chimerism may in part mitigate the higher risk for leukemia/MDS.

Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative treatment for acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). While many factors influence the outcomes of allo-HCT, the independent impact of donor-recipient ABO mismatching remains unclear. Using the Center for International Blood and Marrow Transplant Research (CIBMTR) database, we identified patients aged ≥18 years with AML or ALL who underwent allo-HCT between 2008 and 2018. Our objectives were to analyze the outcomes of allo-HCT based on the donor-recipient ABO status (match, minor mismatch, major mismatch, bidirectional mismatch). Among 4946 eligible patients, 2741 patients (55.4%) were ABO matched, 1030 patients (20.8%) had a minor ABO mismatch, 899 patients (18.1%) had a major ABO mismatch, and 276 patients (5.6%) had a bidirectional ABO mismatch. In multivariable analyses, compared to ABO matched allo-HCT, the presence of a major ABO mismatch was associated with worse overall survival (HR 1.16, 95% CI 1.05-1.29; p = 0.005), inferior platelet engraftment (HR 0.83, 95% CI 0.77-0.90; p < 0.001), and higher primary graft failure (HR 1.60, 95% CI 1.12-2.30, p = 0.01). Relapse, acute graft versus host disease (GVHD) grades III-IV and chronic GVHD were not significantly associated with ABO status. While donor age was not significantly associated with outcomes, older recipient age was associated with worse survival and non-relapse mortality. Our study demonstrates that donor-recipient ABO status is independently associated with survival and other post-transplantation outcomes in acute leukemia. This underscores the importance of considering the ABO status in donor selection algorithms and its impact in acute leukemia., (© 2023 Wiley Periodicals LLC.)

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported. In the primary analysis of the global phase II ELIANA trial (ClinicalTrials.gov identifier: NCT02435849), tisagenlecleucel provided an overall remission rate of 81% in pediatric and young adult patients with relapsed or refractory B-cell acute lymphoblastic leukemia (R/R B-ALL), with 59% of responders remaining relapse-free at 12 months. Here, we report an update on efficacy, safety, and patient-reported quality of life in 79 pediatric and young adult patients with R/R B-ALL following a median follow-up of 38.8 months. The overall remission rate was 82%. The median event-free survival was 24 months, and the median overall survival was not reached. Event-free survival was 44% (95% CI, 31 to 57) and overall survival was 63% (95% CI, 51 to 73) at 3 years overall (most events occur within the first 2 years). The estimated 3-year relapse-free survival with and without censoring for subsequent therapy was 52% (95% CI, 37 to 66) and 48% (95% CI, 34 to 60), respectively. No new or unexpected long-term adverse events were reported. Grade 3/4 adverse events were reported in 29% of patients > 1 year after infusion; grade 3/4 infection rate did not increase > 1 year after infusion. Patients reported improvements in quality of life up to 36 months after infusion. These findings demonstrate favorable long-term safety and suggest tisagenlecleucel as a curative treatment option for heavily pretreated pediatric and young adult patients with R/R B-ALL., Competing Interests: Theodore W. LaetschStock and Other Ownership Interests: Advanced MicrobubblesConsulting or Advisory Role: Novartis, Bayer, Cellectis, Aptitude Health, Clinical Education Alliance, Deciphera, Jumo Health, Massive Bio, Med Learning Group, Medscape, Physicans' Education Resource, Y-mAbs Therapeutics, AI Therapeutics, Jazz Pharmaceuticals, GentiBio, Menarini, Pyramid BiosciencesResearch Funding: Pfizer (Inst), Novartis (Inst), Bayer (Inst), AbbVie (Inst), Amgen (Inst), Atara Biotherapeutics (Inst), Bristol Myers Squibb (Inst), Lilly (Inst), Epizyme (Inst), GlaxoSmithKline (Inst), Janssen (Inst), Jubilant Pharmaceuticals (Inst), Novella Clinical (Inst), Servier (Inst), Foundation Medicine (Inst), Merck Sharp & Dohme (Inst), Turning Point Therapeutics (Inst) Shannon L. MaudeConsulting or Advisory Role: Novartis, KiteResearch Funding: Novartis (Inst), Wugen, Inc (Inst)Patents, Royalties, Other Intellectual Property: PCT/US2017/044425: Combination Therapies of Car and PD-1 InhibitorsTravel, Accommodations, Expenses: Novartis Susana RivesHonoraria: Novartis, Kite/Gilead, Celgene/Bristol Myers Squibb, Shire/ServierConsulting or Advisory Role: Servier, Amgen, Novartis, Kite/Gilead, Shire/Servier, Celgene/Bristol Myers Squibb, Cellectis, Jazz PharmaceuticalsSpeakers' Bureau: NovartisResearch Funding: Novartis (Inst)Travel, Accommodations, Expenses: Novartis, Shire/Servier, Cellectis, Jazz Pharmaceuticals Hidefumi HiramatsuHonoraria: Novar PharmaConsulting or Advisory Role: Novartis Henrique BittencourtConsulting or Advisory Role: Novartis Canada Pharmaceuticals Inc, Jazz PharmaceuticalsSpeakers' Bureau: Novartis Oncology Canada Peter BaderHonoraria: Medac (Inst), Riemser (Inst), Neovii (Inst)Consulting or Advisory Role: Novartis (Inst), Amgen (Inst), Miltenyi (Inst), Servier (Inst)Speakers' Bureau: Novartis (Inst), Amgen (Inst), Riemser (Inst), Medac (Inst), Miltenyi (Inst), Servier (Inst)Research Funding: Medac (Inst), Neovii (Inst), Riemser (Inst)Patents, Royalties, Other Intellectual Property: Patent on MSC licensend to Medac André BaruchelLeadership: DBV Technologies, lysogen, Medday Pharmaceuticals, Ascendis PharmaStock and Other Ownership Interests: DBV Technologies, Ascendis PharmaHonoraria: Novartis, Kite, a Gilead company, AstraZenecaConsulting or Advisory Role: Jazz Pharmaceuticals, Novartis, Servier, CelgeneResearch Funding: Jazz Pharmaceuticals (Inst), Servier (Inst)Travel, Accommodations, Expenses: Jazz Pharmaceuticals, Sanofi, Servier Michael BoyerHonoraria: NovartisEmployment: Thunder BiotechLeadership: Thunder Biotech Barbara De MoerlooseConsulting or Advisory Role: NovartisUncompensated Relationships: Novartis (Inst), Gilead Sciences (Inst), Articulate Science, Jazz Pharmaceuticals Muna QayedHonoraria: Novartis, Vertex, Medexus, Jazz Pharmaceuticals, MesoblastConsulting or Advisory Role: NovartisTravel, Accommodations, Expenses: Novartis Jochen BuechnerHonoraria: Novartis, Pfizer, KiteConsulting or Advisory Role: Novartis, Janssen (Inst), Amgen (Inst)Speakers' Bureau: Novartis Michael A. PulsipherThis author is a member of the Journal of Clinical Oncology Editorial Board. Journal policy recused the author from having any role in the peer review of this manuscript.Honoraria: Novartis, MesoblastConsulting or Advisory Role: Novartis, Medexus Pharmaceuticals, Equillium, Gentibio, Vertex, Bluebird BioResearch Funding: Adaptive Biotechnologies, Miltenyi Biotec Gary Douglas MyersHonoraria: NovartisConsulting or Advisory Role: NovartisSpeakers' Bureau: NovartisResearch Funding: Novartis (Inst) Heather E. StefanskiConsulting or Advisory Role: NovartisSpeakers' Bureau: Novartis Paul L. MartinConsulting or Advisory Role: Neovii Biotech GmbH, Genentech, Enlivex Therapeutics, and PharmacyclicsResearch Funding: Novartis (Inst), Bluebird Bio (Inst), AbGenomics (Inst) Eneida NemecekConsulting or Advisory Role: Novartis, Medexus, Atara Bio Christina PetersHonoraria: Neovii, Jazz Pharmaceuticals, NovartisConsulting or Advisory Role: Amgen, Neovii, NovartisSpeakers' Bureau: Medac, Riemser, AmgenResearch Funding: Medac (Inst), Neovii (Inst), Riemser (Inst), Jazz Pharmaceuticals (Inst), Amgen (Inst)Travel, Accommodations, Expenses: Neovii, Jazz Pharmaceuticals, Novartis Seong Lin KhawHonoraria: Novartis Kara L. DavisHonoraria: NovartisResearch Funding: Jazz Pharmaceuticals Joerg KruegerEmployment: JanssenConsulting or Advisory Role: Novartis, Kite/Gilead, SOBIOther Relationship: Canadian Agency for Drugs and Technologies in Health (CADTH) Adriana BalduzziSpeakers' Bureau: Novartis, Amgen, MedacTravel, Accommodations, Expenses: Novartis, Medac, Neovii Nicolas BoisselHonoraria: Amgen, ARIAD/Incyte, Novartis, Servier, Astellas Pharma, Bristol Myers Squibb, Jazz Pharmaceuticals, Celgene, Sanofi, PfizerConsulting or Advisory Role: Amgen, Novartis, Servier, PfizerResearch Funding: Amgen, Novartis, Bristol Myers Squibb, Jazz PharmaceuticalsExpert Testimony: Amgen Ranjan TiwariEmployment: Novartis Darragh O’DonovanEmployment: Novartis Ireland LtdStock and Other Ownership Interests: Novartis Stephan A. GruppHonoraria: TCR2 Therapeutics, Eureka Therapeutics, CellectisConsulting or Advisory Role: Novartis, Jazz Pharmaceuticals, Janssen, Cellular Biomedicine Group, Roche, Adaptimmune, Alimera Sciences, Cabaletta Bio, CRISPR Therapeutics/VertexResearch Funding: Novartis (Inst), Kite/Gilead (Inst), Servier (Inst), Jazz Pharmaceuticals (Inst), Vertex (Inst)Patents, Royalties, Other Intellectual Property: UPenn Toxicity management patent (Inst)Expert Testimony: Juno TherapeuticsNo other potential conflicts of interest were reported.

By overcoming chemotherapeutic resistance, chimeric antigen receptor (CAR) T cells facilitate deep, complete remissions and offer the potential for long-term cure in a substantial fraction of patients with chemotherapy refractory disease. However, that success is tempered with 10% to 30% of patients not achieving remission and over half of patients treated eventually experiencing relapse. With over a decade of experience using CAR T cells in children, adolescents, and young adults (AYA) to treat relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL) and 5 years since the first US Food and Drug Administration approval, data defining the nuances of patient-specific risk factors are emerging. With the commercial availability of 2 unique CD19 CAR T-cell constructs for B-ALL, in this article, we review the current literature, outline our approach to patients, and discuss how individual factors inform strategies to optimize outcomes in children and AYA receiving CD19 CAR T cells. We include data from both prospective and recent large retrospective studies that offer insight into understanding when the risks of CAR T-cell therapy failure are high and offer perspectives suggesting when consolidative hematopoietic cell transplantation or experimental CAR T-cell and/or alternative immunotherapy should be considered. We also propose areas where prospective trials addressing the optimal use of CAR T-cell therapy are needed.

Relapse following chimeric antigen receptor (CAR) T-cell therapy directed against CD19 for relapsed/refractory B-acute lymphoblastic leukemia (r/r B-ALL) remains a significant challenge. Three main patterns of relapse predominate: CD19 positive (CD19pos) relapse, CD19 negative (CD19neg) relapse, and lineage switch (LS). Development and validation of risk factors that predict relapse phenotype could help define potential pre- or post-CAR T-cell infusion interventions aimed at decreasing relapse. Our group sought to extensively characterize preinfusion risk factors associated with the development of each relapse pattern via a multicenter, retrospective review of children and young adults with r/r B-ALL treated with a murine-based CD19-CAR construct. Of 420 patients treated with CAR, 166 (39.5%) relapsed, including 83 (50%) CD19pos, 68 (41%) CD19neg, and 12 (7.2%) LS relapses. A greater cumulative number of prior complete remissions was associated with CD19pos relapses, whereas high preinfusion disease burden, prior blinatumomab nonresponse, older age, and 4-1BB CAR construct were associated with CD19neg relapses. The presence of a KMT2A rearrangement was the only preinfusion risk factor associated with LS. The median overall survival following a post-CAR relapse was 11.9 months (95% CI, 9-17) and was particularly dismal in patients experiencing an LS, with no long-term survivors following this pattern of relapse. Given the poor outcomes for those with post-CAR relapse, study of relapse prevention strategies, such as consolidative hematopoietic stem cell transplantation, is critical and warrants further investigation on prospective clinical trials., (Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

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 × 10 9 /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 × 10 9 /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., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Severe combined immunodeficiency (SCID) results from defects in the differentiation of hematopoietic stem cells into mature T lymphocytes, with additional lymphoid lineages affected in particular genotypes. In 2014, the Primary Immune Deficiency Treatment Consortium published criteria for diagnosing SCID, which are now revised to incorporate contemporary approaches. Patients with typical SCID must have less than 0.05 × 10 9 autologous T cells/L on repetitive testing, with either pathogenic variant(s) in a SCID-associated gene, very low/undetectable T-cell receptor excision circles or less than 20% of CD4 T cells expressing naive markers, and/or transplacental maternally engrafted T cells. Patients with less profoundly impaired autologous T-cell differentiation are designated as having leaky/atypical SCID, with 2 or more of these: low T-cell numbers, oligoclonal T cells, low T-cell receptor excision circles, and less than 20% of CD4 T cells expressing naive markers. These patients must also have either pathogenic variant(s) in a SCID-associated gene or reduced T-cell proliferation to certain mitogens. Omenn syndrome requires a generalized erythematous rash, absent transplacentally acquired maternal engraftment, and 2 or more of these: eosinophilia, elevated IgE, lymphadenopathy, hepatosplenomegaly. Thymic stromal defects and other causes of secondary T-cell deficiency are excluded from the definition of SCID. Application of these revised Primary Immune Deficiency Treatment Consortium 2022 Definitions permits precise categorization of patients with T-cell defects but does not imply a preferred treatment strategy., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)