Kohorst, Mira A.

There have been no large comparisons of the clinical and laboratory features of familial neonatal hemophagocytosis (f-nHLH) and infectious neonatal hemophagocytosis (i-nHLH). The objectives of this study were the following: (1) Describe the demographic, diagnostic, and clinical features of patients with familial nHLH (F-nHLH) and infectious HLH (i-nHLH). (2) Compare key variables between f-nHLH and i-nHLH. (3) Compare the clinical outcomes of f-nHLH and i-nHLH. (4) Summarize literature on cytokine levels in patients with nHLH. Data from a previously published nHLH meta-analysis report were used to describe and compare features of infants with f-nHLH versus i-nHLH. Variables were tested with the χ 2 test or Fisher exact test, Cochran-Armitage test, independent 2-sample t test, or Wilcoxon rank-sum test as appropriate. Odds ratios were calculated for any comparison with a P -value of <0.05. Data extracted from 99 cases of f-nHLH and 54 cases of i-nHLH were included in this analysis. Infants with f-HLH met HLH criteria at the following rates: fever (84%); organomegaly (100%); pancytopenia (75%); hypofibrinogenemia (84%); hypertriglyceridemia (48%); hypofibrinogenemia or hypertriglyceridemia (82%); hemophagocytosis (81%); hyperferritinemia (99%); low or absent NK cell activity (91%); and elevated soluble CCD25 (91%). Infants with i-nHLH had higher median ferritin levels (22,537 ng/mL) than infants with f-nHLH (7587 ng/mL) ( P =0.072). Infants with f-nHLH had higher rates of symptoms in utero, preterm birth, family history of HLH, and family history of infant death. The overall survival among infants with familial nHLH was lower than infectious nHLH ( P =0.037). Management of nHLH requires rapid diagnosis and prompt treatment, as current literature suggests nHLH has high mortality rates. Distinguishing between familial and infectious causes of nHLH can aid in determining the correct treatment of choice.

Abstract Background Revaccination is required for patients who receive a hematopoietic cell transplant (HCT) to reduce vaccine preventable illness. Revaccination requires an individualized plan due to differences in immunosuppressive therapy, immune reconstitution, age, and other challenges such as graft versus host disease. A structured approach is required to ensure prompt initiation of re-vaccinations and completion of the re-vaccination schedule. This study sought to evaluate the re-vaccination process at our center as a baseline for quality improvement. Methods We conducted a retrospective chart review of pediatric patients who received an autologous or allogeneic HCT between January 2019 and March 2024 to assess time to starting re-vaccination after post-HCT medical clearance and percentage of patients up to date within each series of vaccinations per internal protocol. Results A total of 64 patients were evaluated, of whom 23 were female and 35 underwent allogeneic stem cell transplant. For analysis, 13 were excluded due to death prior to clearance for vaccination. Among those included, 42 patients were cleared for restarting vaccines, and 37 (88%) of those have received at least one vaccine, while only 25 (59%) have completed the first series of recommended vaccines. The average time from transplant to administration of the first vaccine was 431 days for autologous HCT and 459 days for allogeneic HCT. The average time from medical clearance to the first vaccine was 66 days. The mean interval between the first and second vaccine doses was 97 days. Conclusion The majority of eligible patients initiated re-vaccination after transplant, but rates for the receipt of full recommended initial series remained suboptimal, with notable delays with notable delays between transplant and the day of clearance as well as clearance and the first vaccine administered. These findings highlight significant gaps in post-transplant immunization practices and underscore the need for targeted interventions to optimize protection for this vulnerable population. Disclosures All Authors: No reported disclosures

Abstract BACKGROUND Children exposed to poverty during frontline therapy for B-lymphoblastic leukemia (B-ALL) experience inferior overall survival (OS), higher relapse rates, and earlier relapse than their peers. Real-world data describing treatment patterns and survival after relapse of B-ALL are lacking and, as a result, the impact of poverty following relapse remains poorly understood. This study evaluated the association of poverty exposure, proxied by insurance status, with post-relapse survival and explored potential explanatory mechanisms, including disease biology and therapy utilization. METHODS Data from Retrospective Study of Contemporary Approaches to First Relapse in B-ALL (ReCALL-1), a multicenter retrospective cohort study of patients &lt; 30 years old with first relapse of B-ALL from 2018-2022, were used. The primary exposure was poverty, proxied by insurance status at relapse, categorized as any private insurance (poverty unexposed), public-only insurance (poverty exposed), no insurance, or unknown; the latter two were not included in comparative analyses due to low numbers. The primary outcome was OS. Secondary outcomes included measurable residual disease (MRD)-negative second complete remission (CR2), relapse after CR2, non-relapse mortality (NRM), with relapse treated as a competing risk, and receipt of cellular and immunotherapies. RESULTS Among 462 patients from 31 U.S. institutions, 41% had private insurance, 47% public-only insurance, 2% no insurance, and 10% unknown. Compared to privately insured patients, those with public insurance were more likely to be Hispanic (56% vs 19%, p&lt;0.001) and have non-English preferred language (30% vs 6%, p&lt;0.001). Non-Hispanic Black patients comprised 9% of those with public insurance and 5% of those with private insurance. Disease characteristics that differed by insurance status at relapse included: Ph-like cytogenetics, more common in publicly insured (23% vs 11%, p=0.002), and infant ALL, more common in privately insured patients (10% vs 5%, p=0.06). Publicly insured patients were more likely to have experienced major organ toxicity during frontline therapy (32% vs 18%, p=0.002) and very early relapse (&lt;18m from diagnosis: 43% vs 32%, p=0.07). Other demographic and disease characteristics, including relapse site and cytomolecular features, were similar by insurance status. With a median follow-up of 51 months from relapse, 4-year OS differed by insurance (log-rank p=0.02): 72% for private vs 56% for public insurance. After adjusting for race/ethnicity and language, public insurance increased the hazard of death by 65% (aHR 1.65 95% CI 1.13-2.42, p=0.004). The association remained, but was attenuated, when unbalanced disease characteristics (time to relapse, infant ALL, Ph-like cytogenetics, prior organ dysfunction) were included (aHR 1.47, 95% CI 1.00-2.16, p=0.05). Rates of MRD-negative CR2 were similar (85% public vs 87% private). However, point estimates suggested publicly insured patients had more relapse after CR2 (44% vs 37%, p=0.42) and higher 4-year NRM (16% vs 10%, Gray's test p=0.12), though neither were significant. Treatment choices for first relapse did not differ by insurance status. Utilization of intensive reinduction (91% vs 95% for public vs private, p=0.18) and clinical trial enrollment (22% for both) were similar. Receipt of cellular therapies did not significantly differ by public vs private insurance: Chimeric Antigen Receptor-T cells (CAR-T: 38% vs 34%, p=0.41), hematopoietic cell transplant (HCT: 42% vs 47%, p=0.32). Use of blinatumomab trended higher in those with private insurance (36% vs 45%, p=0.07), and inotuzumab was similar (11% for both, p=0.87). Median time from relapse to CAR-T or HCT was comparable (to CAR-T 102 vs 100 days, to HCT 117 vs 114 days). CONCLUSION This is the first study to demonstrate differential survival by insurance type, a proxy for poverty exposure, after first relapse of B-ALL. In this large multicenter, real-world cohort, patients with public insurance had worse OS after relapse than those with private insurance. The survival disparity existed independent of other SDOH factors. Adjustment for known high-risk disease features only partially accounted for the observed differences in OS. In contrast, rates of MRD-negative CR2 and receipt of CAR-T and HCT were comparable across insurance types. These findings highlight the urgent need to identify effective interventions that will ensure equitable outcomes after relapse.

Abstract Background Pediatric patients undergoing hematopoietic cell transplantation (HCT) may develop life-threatening complications and need for ICU admission (ICU). They may display more severe and/or unique manifestations of organ dysfunction syndromes, including acute respiratory failure, sepsis and delirium, compared to the general pediatric In this interim analysis of the POEM study, the utility of a p-MODS screening tool as a predictor of endotheliopathies and/or ICU is reported. Methods: NCT05090345 is a prospective multi-center registry/biorepository trial of children and adolescents/young adults (AYA) undergoing HCT to assess the impact of endotheliopathies on morbidity and mortality. Patients undergoing all HCT types are prospectively monitored for 100 days post-HCT for sinusoidal obstructive syndrome (SOS), thrombotic microangiopathy (TMA), capillary leak syndrome (CLS), diffuse alveolar hemorrhage (DAH) and ICU. The risk of p-MODS was assessed within 7 days of HCT admission and weekly for 4 weeks, to dynamically evaluate organ function across 8 systems: respiratory, cardiovascular, renal, hepatic, hematologic, neurologic, immune, and gastrointestinal. Each system was graded on a 0–5 scale based on clinical and laboratory parameters, with total pMODS calculated using the worst score per organ. Descriptive statistics were used to compare p-MODS score between groups with “events” (defined as endotheliopathy or ICU) versus “no events”. The “no event” comparison group was matched 1:1 by diagnosis, age, gender and HCT type. Results: Among all subjects (n=151), the median age was 11.3 (range: 0.2–26.9) years and the majority (64%) male and Caucasian ( 60%) and 20% Black. Most patients (86.8%) underwent allogeneic HCT. Common indications were hematologic malignancy (45%), solid tumors (19%) and hemoglobinopathies (8.6%).Events (n=50) were observed in 35 of 151 patients, including ICU (n=26), SOS (n=19), TMA (n=3) CLS (n=1) and DAH (n=1). Events occurred at a median of 16 (range: –7 to 85) days post-HCT. Median time to ICU was 15 (range: –7 to 82) days post-HCT. The median pMODS score at the time of ICU was 10 (range: 1–22). All three patients with TMA had preceding ICU admissions and 4 of 19 patients with SOS required ICU management. The median time to onset of endotheliopathy was 17 (range: 6–33) days post-HCT. The median pMODS score at the time of event was 11 (range: 7–18), compared to a median of 8 (range: 5–21) the week prior to onset. Patients who developed events exhibited progressively higher scores compared to matched controls starting at week 1 (p &lt; 0.05). This difference became more pronounced over time, reaching statistical significance at week 2 (p &lt; 0.001). Since physiologic decline may precede overt events, we next analyzed pMODS score change between Day 0 and week 1. A significant difference was observed with median increase of 2 (range: –2 to 16) in the event group versus 1 (range: –3 to 7) in the control group (p = 0.01). Analysis of individual organ system scores revealed notable differences between the event and control groups by Week 1, prior to median event onset. The event group had higher rates of indicators of organ dysfunction in 6 of 8 organ system. The event group had more subjects with acute kidney injury, elevated delirium scores, need for respiratory support, increased bilirubin, moderate to significant weight gain and infections. However, rates of neutropenia and lymphopenia were comparable between groups. Conclusion In this interim analysis, a significant increase in pMODS between Day 0 and week 1 post-HCT may reflect early physiologic decline, with notable changes in respiratory status, acute kidney injury, elevated CAPD scores, and infectious burden. These findings highlight the potential utility of pMODS as an early screening tool to identify pediatric HCT recipients at risk for clinical deterioration. Prospective and dynamic monitoring of pMODS may support timely intervention and improve outcomes in this vulnerable population.

Abstract Introduction Pronounced disparities in pediatric B-lymphoblastic leukemia (B-ALL) outcomes by race and ethnicity persist in the contemporary era. Gaps in overall survival (OS) from initial diagnosis are wider than event-free survival, suggesting that post-relapse mechanisms may contribute. However, data on treatment and outcomes after relapse are lacking. In a large, multicenter, real-world cohort of children and young adults with high-risk 1st relapse of B-ALL, we sought to (1) define survival outcomes by race/ethnicity and (2) explore if differences in therapy utilization drive outcomes. Methods We conducted an analysis within the Retrospective Study of Contemporary Approaches to 1st Relapse in B-ALL (ReCALL-1) cohort, which includes patients &lt;30 years who initiated 1st relapse therapy between 2018-2022. This analysis was restricted to patients treated at US centers for “high-risk” 1st relapse, defined as relapse for which hematopoietic cell transplant (HCT) is generally standard-of-care: Early relapse (medullary &lt;36m; isolated extramedullary &lt;18m), late relapse with persistent end of reinduction disease, Ph+ B-ALL or age ≥18 years. Patients with Trisomy 21, those who received cell therapy before relapse and those who died during reinduction were excluded. The primary exposure was race/ethnicity categorized as Hispanic, non-Hispanic Black (NHB), non-Hispanic White (NHW), and other/unknown. The primary outcome was OS from relapse. Multivariable Cox regression models were constructed to include other social drivers of health (SDOH; health insurance, preferred language) and disease characteristics. Results Of 479 patients in ReCALL-1, 311 from 31 centers met inclusion for this analysis (41% Hispanic, 7% NHB, 46% NHW, 5% NH-other/unknown). With a median follow-up of 47m, OS differed by race/ethnicity (log-rank p=0.017): Hispanic, 4y OS 59%; NHB, 37%; NHW, 68%. Compared to NHW patients, NHB patients had an increased hazard of death (HR 2.3, 95% CI 1.3-4.3, p=0.006), while Hispanic patients were more similar to NHW patients (HR 1.3, 95% CI 0.9-2.0, p=0.16). Adjustment for SDOH only marginally attenuated the risk for NHB patients (aHR 2.0, 95% CI, 1.1-3.7, p=0.031) and led to equivalent outcomes for Hispanic patients (aHR 0.9, 95% CI, 0.5-1.5, p=0.66). Adjusting for disease characteristics that differed by race/ethnicity at p&lt;0.2 (time to relapse, Ph+, Ph-like, KMT2Ar, age ≥18, or relapsed infant ALL) did not diminish the risk for NHB patients (aHR 2.0, 95% CI, 1.1-3.7, p=0.032) while outcomes remained equivalent for Hispanic patients (aHR 1.2, 95% CI, 0.8-1.8, p=0.40). Point estimates of cumulative incidence of non-relapse mortality (NRM) were highest in NHB patients (Hispanic, 4y NRM 13%, NHB 22%, NHW 11%), but this trend was not statistically significant (Gray’s p=0.52). Only 17% of patients initiated therapy for relapse on a clinical trial with no differences observed by race/ethnicity. Most patients received definitive treatment for relapse with either CAR T cell therapy (CART) or HCT: 79% overall, 74% Hispanic, 91% NHB, and 83% NHW. CART and HCT were utilized equally (39% and 40%, respectively) and the proportion that received each therapy did not vary by race/ethnicity. Time to CART/HCT, external referral for treatment, receipt of investigational v commercial CART, and use of post-CART consolidative HCT revealed no differences by race/ethnicity. Of the 66 patients (21%) who did not receive cell therapy, 26 had planned for CART or HCT, but did not receive due to disease progression or NRM (n=24; 12 Hispanic, 10 NHW), or insurance barriers (n=2, both Hispanic). After HCT, OS was worse for NHB patients (log-rank p=0.03) with 4y OS of 42% v 85% for NHW and 75% for Hispanic. Post-CART, 4y OS was 40% for NHB v 59% for NHW and 51% for Hispanic, but this difference was not statistically significant. Conclusion In a large real-world cohort of children with high-risk 1st relapse of B-ALL, we found a two-fold increased hazard of death for NHB patients compared to NHW patients, even after adjustment for other SDOH factors and high-risk disease features. In contrast to previous studies of adult patients, children appeared to have equal access to cell therapies across races/ethnicities. We found that Hispanic patients, who comprised &gt;40% of the cohort, had similar survival to NHW children, suggesting that availability of cellular and immunotherapies may be mitigating historically observed disparities for children with relapsed B-ALL.

Abstract INTRODUCTION Outcomes for 1st relapse of pediatric B-lymphoblastic leukemia (B-ALL), especially high/intermediate-risk (HR/IR) relapse, remain unacceptably poor. Limited enrollment of this population on cooperative group clinical trials has impeded our ability to study potentially effective regimens. In the current era, patients can access innovative immunotherapies commercially. However, there is no mechanism to capture outcomes for these off-study patients and no comparative effectiveness data to guide treatment selection. METHODS We conducted a multicenter, retrospective study of patients &lt;30 years who initiated 1st relapse therapy at a participating center from 2018-2022 (ReCALL-1 Study). Objectives were to define real-world survival outcomes, compare response rates of reinduction strategies, describe the post-reinduction treatment landscape, and, for patients with HR/IR relapse, assess the comparative effectiveness (CE) of blinatumomab to hematopoietic cell transplant (blina/HCT) v CD19 CAR T cells (CART). For the CE analysis, we emulated an open-label, randomized study of blina/HCT v CART who achieved an M1/M2 marrow at the end of an intensive reinduction (EoRI). Patients were classified by their intended treatment at EoRI. Cox regression models were used to adjust for unbalanced patient and disease features by arms. The primary outcome was overall survival (OS) from EoRI. RESULTS The full cohort included 479 patients from 33 centers (31 US, 2 international). Median time to relapse was 31 months (m); 77% had bone marrow (BM) involvement and 31% central nervous sytem involvement. With a median follow-up of 49m from relapse, 4 year (y) OS, event-free survival (EFS), and non-relapse mortality (NRM) were 64%, 43%, and 13%, respectively. Among patients with very early BM (&lt;18m, n=79), early BM (18-35m, n=76), late BM (≥36m, n=162), and isolated CNS (n=85) relapses, 4y OS/EFS were 29%/20%, 57%/35%, 78%/49%, and 84%/61%, respectively. Only 19% received reinduction therapy on a clinical trial. Among patients with BM disease, R3 reinduction (n=179) and VXLD (n=61) had identical MRD-negative (&lt;0.01%) CR rates of 38% (p=1.00) and equivalent treatment failure (TF; M3 or extramedullary disease) rates: R3, 8% v VXLD 7%, p=0.79. Blina (n=33) and inotuzumab-based (n=21) reinductions achieved MRD-negative CR rates of 39% and 52%, respectively, but higher TF rates of 39% and 24%. Reinduction mortality was 2%: R3, n=5; VXLD, n=3; 3-drug reinduction, n=1. Overall, as part of 1st relapse therapy, 36% received CART (78% commercial product), 44% HCT, 40% blina, and 11% inotuzumab. The emulated trial included 159 patients, 95 on blina/HCT and 64 on CART. Study arms were well matched by demographics, cytogenetics, and relapse sites, but CART patients were more likely to have relapsed &lt;18m from diagnosis (34% v 24%) and have EoRI M2 marrows (31% v 11%), and less likely to have private insurance (36% v 51%). Unadjusted OS was comparable between arms (log rank p=0.18): CART, 60% at 4y; blina/HCT, 71%, as was NRM (10% v 13% at 4y). EFS was lower for CART (p=0.049): 4y EFS 35% v 49% for blina/HCT. After adjustment for unbalanced covariates, the hazard of death was equivalent for CART as compared to blina/HCT (aHR 1.1, 95% CI 0.6-2.1, p=0.67) and EFS became more comparable (aHR 1.3, 95% CI 0.8-2.1, p=0.22). 91% of blina/HCT and 97% of CART received their intended cell therapy; time from EoRI to cell therapy was shorter for CART (67 v 86 days, p&lt;.001). In the CART arm, 34% underwent consolidative HCT; 1/3 were preplanned and 2/3 due to loss of B cell aplasia or NGS-MRD positivity. Of those with a 2nd relapse, CART patients were more likely to be CD19 negative (47% v 10%, p=0.003). CONCLUSION In this multicenter, real-world cohort of children treated for 1st relapse in the immunotherapy era, suboptimal outcomes for early BM relapse persisted, with particularly dismal 4y OS of 29% for relapses &lt;18m after diagnosis. In contrast, survival for late BM and isolated CNS relapses compared favorably to historic data. Only 1 in 5 patients initiated relapse therapy on a clinical trial and although 1st relapse is not an approved indication for commercial CART in pediatrics, 36% received CART. In an emulated trial of post-reinduction blina/HCT v CART, adjusted EFS and OS were comparable, suggesting that CART may be a viable alternative to HCT for select patients. Post hoc analyses will identify whether specific subgroups may benefit more from one strategy.

Summary Recipients of haploidentical and unrelated haematopoietic cell transplants (HCTs) historically had a higher risk for graft‐versus‐host disease (GvHD). However, with improved GvHD prophylaxis, recent data suggest adult patients undergoing transplantation from unrelated or mismatched donors now experience the rates of GvHD similar to those receiving matched related donor grafts. This finding is not yet explored in paediatric patients. The objectives of this study were to: (1) compare acute and chronic GvHD incidence, mortality and GvHD‐free relapse‐free survival (GRFS) among matched related donor (MRD), matched unrelated donor (MUD) and haploidentical paediatric HCT recipients in the era of enhanced GvHD prophylaxis for high‐risk patients, (2) identify independent risk factors for GvHD and (3) evaluate the efficacy of various GvHD prophylactic regimens in our cohort. We conducted a retrospective, single‐centre medical record abstraction among patients aged 0–25 years who underwent allogeneic HCT for any indication. The results demonstrated that 5‐year cumulative incidence rates of any GvHD, all‐cause mortality and GRFS are similar across the haploidentical, MRD and MUD groups. Tacrolimus‐containing doublet/triplet regimens were associated with decreased GvHD, as compared to ciclosporin. Adding alemtuzumab also decreased risk for GvHD, without increasing relapse rates. Prospective studies with larger cohorts are warranted to further optimize outcomes for paediatric allogeneic HCT patients.