Overlap chronic GVHD is associated with adverse survival outcomes compared to classic chronic GVHD

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.

Immunophenotypic predictors of influenza vaccine immunogenicity in pediatric hematopoietic cell transplant recipients

ABSTRACT

Pediatric hematopoietic cell transplant (HCT) recipients exhibit poor serologic responses to influenza vaccination early after transplant. To facilitate the optimization of influenza vaccination timing, we sought to identify B- and T-cell subpopulations associated with influenza vaccine immunogenicity in this population. We used mass cytometry to phenotype peripheral blood mononuclear cells collected from pediatric HCT recipients enrolled in a multicenter influenza vaccine trial comparing high- and standard-dose formulations over 3 influenza seasons (2016-2019). We fit linear regression models to estimate relationships between immune cell subpopulation numbers before vaccination and prevaccination to postvaccination geometric mean fold rises in antigen-specific (A/H3N2, A/H1N1, and B/Victoria) serum hemagglutination inhibition antibody titers (28-42 days, and ∼6 months after 2 doses). For cell subpopulations identified as predictive of a response to all 3 antigens, we conducted a sensitivity analysis including time after transplant as an additional covariate. Among 156 HCT recipients, we identified 33 distinct immune cell subpopulations; 7 significantly predicted responses to all 3 antigens 28 to 42 days after a 2-dose vaccine series, irrespective of vaccine dose. We also found evidence that baseline absolute numbers of naïve B cells, naïve CD4+ T cells, and circulating T follicular helper cells predicted peak and sustained vaccine-induced titers irrespective of dose or timing of posttransplant vaccine administration. In conclusion, several B- and T-cell subpopulations predicted influenza vaccine immunogenicity in pediatric HCT recipients. This study provides insights into the immune determinants of vaccine responses and may help guide the development of tailored vaccination strategies for this vulnerable population.

The Adverse Event Landscape of Stem Cell Transplant: Evidence for aGVHD Driving Early Transplant Associated Toxicities

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).

Dabrafenib and trametinib in Langerhans cell histiocytosis and other histiocytic disorders

The standard treatment for Langerhans cell histiocytosis (LCH) is chemotherapy, although the failure rates are high. Since MAP-kinase activating mutations are found in most cases, BRAF- and MEK-inhibitors have been used successfully to treat patients with refractory or relapsed disease. However, data on long-term responses in children are limited and there are no data on the use of these inhibitors as first-line therapy. We treated 34 patients (26 with LCH, 2 with juvenile xanthogranuloma, 2 with Rosai-Dorfman disease, and 4 with presumed single site-central nervous system histiocytosis) with dabrafenib and/or trametinib, either as first line or after relapse or failure of chemotherapy. Sixteen patients, aged 1.3-21 years, had disease that was recurrent or refractory to chemotherapy, nine of whom had multisystem LCH with risk-organ involvement. With a median treatment duration of 4.3 years, 15 (94%) patients have sustained favorable responses. Eighteen patients, aged 0.2-45 years, received an inhibitor as first-line treatment. All of these have had sustained favorable responses, with a median treatment duration of 2.5 years. Three patients with presumed isolated central nervous system/pituitary stalk histiocytosis had stabilization or improvement of their disease. Overall, inhibitors were well tolerated. Five patients with single-system LCH discontinued therapy and remain off therapy without recurrence. In contrast, all four patients with multisystem disease who discontinued therapy had to restart treatment. Our data suggest that children suffering from histiocytoses can be treated safely and effectively with dabrafenib or trametinib. Additional studies are, however, needed to determine the long-term safety and optimal duration of therapy.

Virus-Specific T Cells for the Treatment of Systemic Infections Following Allogeneic Hematopoietic Cell and Solid Organ Transplantation

Viral infections are a major source of morbidity and mortality in the context of immune deficiency and immunosuppression following allogeneic hematopoietic cell (allo-HCT) and solid organ transplantation (SOT). The pharmacological treatment of viral infections is challenging and often complicated by limited efficacy, the development of resistance, and intolerable side effects. A promising strategy to rapidly restore antiviral immunity is the adoptive transfer of virus-specific T cells (VST). This therapy involves the isolation and ex vivo expansion or direct selection of antigen-specific T cells from healthy seropositive donors, followed by infusion into the patient. This article provides a practical guide to VST therapy by reviewing manufacturing techniques, donor selection, and treatment indications. The safety and efficacy data of VSTs gathered in clinical trials over nearly 30 years is summarized. Current challenges and limitations are discussed, as well as opportunities for further research and development.

The Durability of Antibody Responses of Two Doses of High-Dose Relative to Two Doses of Standard-Dose Inactivated Influenza Vaccine in Pediatric Hematopoietic Cell Transplant Recipients: A Multi-Center Randomized Controlled Trial

BACKGROUND

Our previous study established a 2-dose regimen of high-dose trivalent influenza vaccine (HD-TIV) to be immunogenically superior compared to a 2-dose regimen of standard-dose quadrivalent influenza vaccine (SD-QIV) in pediatric allogeneic hematopoietic cell transplant (HCT) recipients. However, the durability of immunogenicity and the role of time post-HCT at immunization as an effect modifier are unknown.

METHODS

This phase II, multi-center, double-blinded, randomized controlled trial compared HD-TIV to SD-QIV in children 3-17 years old who were 3-35 months post-allogeneic HCT, with each formulation administered twice, 28-42 days apart. Hemagglutination inhibition (HAI) titers were measured at baseline, 28-42 days following each dose, and 138-222 days after the second dose. Using linear mixed effects models, we estimated adjusted geometric mean HAI titer ratios (aGMR: HD-TIV/SD-QIV) to influenza antigens. Early and late periods were defined as 3-5 and 6-35 months post-HCT, respectively.

RESULTS

During 3 influenza seasons (2016-2019), 170 participants were randomized to receive HD-TIV (n = 85) or SD-QIV (n = 85). HAI titers maintained significant elevations above baseline for both vaccine formulations, although the relative immunogenic benefit of HD-TIV to SD-QIV waned during the study. A 2-dose series of HD-TIV administered late post-HCT was associated with higher GMTs compared to the early post-HCT period (late group: A/H1N1 aGMR = 2.16, 95% confidence interval [CI] = [1.14-4.08]; A/H3N2 aGMR = 3.20, 95% CI = [1.60-6.39]; B/Victoria aGMR = 1.91, 95% CI = [1.01-3.60]; early group: A/H1N1 aGMR = 1.03, 95% CI = [0.59-1.80]; A/H3N2 aGMR = 1.23, 95% CI = [0.68-2.25]; B/Victoria aGMR = 1.06, 95% CI = [0.56-2.03]).

CONCLUSIONS

Two doses of HD-TIV were more immunogenic than SD-QIV, especially when administered ≥6 months post-HCT. Both groups maintained higher titers compared to baseline throughout the season.

CLINICAL TRIALS REGISTRATION

NCT02860039.

Higher abatacept exposure after transplant decreases acute GVHD risk without increasing adverse events

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_1) and grade (GR) 2 or 4 aGVHD (GR2-4 aGVHD) through day +100. An optimal Ctrough_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_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_1 <39 μg/mL associated with GR2-4 aGVHD risk indistinguishable from placebo (P = .37). Importantly, no significant association was found between Ctrough_1 and key safety indicators, including relapse, and cytomegalovirus or Epstein-Barr virus viremia. These data demonstrate that a higher abatacept Ctrough_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.

1119. Covid-19 Mab Use in High-Risk Pediatric Patients

Background

Effective therapeutic agents for the treatment of COVID-19 have been investigated since the onset of the pandemic. Monoclonal antibodies targeting the spike protein of SARS-CoV-2 have been developed for treatment of mild or moderate COVID disease in high-risk populations. Despite widespread use in the adult population, data are limited on the safety and efficacy of monoclonal antibody infusions in the adolescent and young adult population.

Methods

Patients who received bamlanivimab, bamlanivimab-etesevimab, casirivimab-imdevimab, or sotrovimab for treatment of mild COVID disease at Cincinnati Children’s Hospital Medical Center from 5/1/2020 through 3/1/2022 were identified retrospectively. In accordance with the FDA EUA, patients were eligible for monoclonal antibody administration if they were ≥12 years of age, weighed ≥40kg, and were at high risk of progressing to severe disease or hospitalization.

Results

Ninety-four patients received monoclonal antibody therapy, of which 14 (13.5%) received either bamlanivimab or bamlanivimab-etesevimab, 54 (51.9%) received casirivimab-imdevimab, and 26 (25%) received sotrovimab. Ten patients (10.6%) experienced one or more adverse events. Of those, 2 (14.3%) received either bamlanivimab or bamlanivimab-etesivimab, 7 (12.9%) received casirivimab-imdevimab, and 1 (3.8%) received sotrovimab. Most common symptoms include rash, nausea, and throat irritation (table R1), the majority (90%) of which were mild, either self-resolving with infusion cessation (60%) or persistent but requiring no medical intervention (30%) (table R2). Of the patients who experienced adverse events, only 1 (10%) received medical intervention - epinephrine. No life-threatening events or deaths occurred. Within 90 days of receiving a monoclonal antibody, 15 patients (15.9%) required additional medical care for ongoing COVID symptoms (table R3). Eight (53.3%) of these were either hospitalized or received escalation of care while already in the hospital. Table R1.

Infusion-related adverse events. Of note, several patients had more than one symptom. Table R2.

Classification of adverse events by grade and monoclonal antibody. Grade I events are defined as mild and generally not bothersome. Grade II events are defined as moderate: bothersome, but not dangerous. Grade III events are defined as medically significant, but not immediately life-threatening, and often require medical intervention. Table R3.

Patients who required additional medical care for ongoing COVID-19 symptoms within 90 days of receiving a monoclonal antibody.

Conclusion

Overall, monoclonal antibodies are safe, largely well-tolerated COVID-19 therapies in high-risk adolescent and young adult populations.

Disclosures

Grant Schulert, MD, PhD, Novartis: Advisor/Consultant Paul Spearman, MD, CyanVac: Grant/Research Support|Meissa Vaccines: Grant/Research Support Grant C. Paulsen, MD, AstraZeneca: Grant/Research Support|Moderna: Grant/Research Support|Pfizer: Grant/Research Support Lara A. Danziger-Isakov, MD, Ansun BioPharma: Contracted clinical research|Astellas: Contracted clinical research|GSK: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Contracted clinical research|Pfizer: Contracted clinical research|Takeda: Grant/Research Support|Takeda: Contracted clinical research|Viracor: Grant/Research Support.

Granulocyte Colony-Stimulating Factor is Safe and Well Tolerated following Allogeneic Transplantation in Patients with Sickle Cell Disease

Granulocyte colony-stimulating factor (G-CSF) used after hematopoietic stem cell transplantation (HSCT) can enhance neutrophil recovery in patients rendered neutropenic by the preparative regimen. G-CSF is contraindicated in patients with sickle cell disease (SCD) as life-threatening complications can ensue in the presence of sickle vasculopathy. However, the safety profile of G-CSF after HSCT for SCD has not been previously described. We report clinical outcomes in the first 100 days post-HSCT in patients supported with G-CSF until neutrophil recovery on a clinical trial of reduced intensity transplantation for SCD. Patients (n=62) received G-CSF for a median of 9 days (range, 5-33) following transplant from the best available stem cell source. Preparation for transplant included a target hemoglobin S level of ≤45%. Neutrophil engraftment (ANC >0.5 × 10³/mL) was achieved at a median of 13 days (range,10-34) and platelet engraftment (>50 × 10³/mL) at a median of 19 days (range, 12-71). The median duration of inpatient hospitalization following stem cell infusion (day 0) was 21.5 days (range 11-33). No patient developed SCD related complications following G-CSF use. The most common organ toxicities encountered between G-CSF commencement (on day +7) and day +100 were anorexia (14), hypertension (11) and electrolyte imbalance requiring correction (9). Central nervous system related events were noted in 5 patients, all with pre-existing cerebral vasculopathy/moyamoya disease and attributed to reversible posterior leukoencephalopathy syndrome (RPLS) in the presence of calcineurin inhibitor therapy and hypertension. We conclude that G-CSF does not adversely impact SCD transplant recipients and can be safely used post-HSCT to enhance neutrophil recovery.

Case Report: Fatal Complications of BK Virus-Hemorrhagic Cystitis and Severe Cytokine Release Syndrome Following BK Virus-Specific T-Cells

BK virus (BKV)-hemorrhagic cystitis (HC) is a well-known and rarely fatal complication of hematopoietic stem cell transplantation (HSCT). Treatment for BKV-HC is limited, but virus-specific T-cells (VST) represent a promising therapeutic option feasible for use posttransplant. We report on the case of a 16-year-old male with dedicator of cytokinesis 8 (DOCK8) deficiency who underwent haploidentical HSCT complicated by severe BKV-HC, catastrophic renal hemorrhage, and VST-associated cytokine release syndrome (CRS). Gross hematuria refractory to multiple interventions began with initiation of posttransplant cyclophosphamide (PT/Cy). Complete left renal arterial embolization (day +43) was ultimately indicated to control intractable renal hemorrhage. Subsequent infusion of anti-BK VSTs was complicated by CRS and progressive multiorgan failure, with postmortem analysis confirming diagnosis of hepatic sinusoidal obstruction syndrome (SOS). This case illustrates opportunities for improvement in the management of severe BKV-HC posttransplant while highlighting rare and potentially life-threatening complications of BKV-HC and VST therapy.

Novel Treatment of Infant With COVID-19 With the Sialidase Fusion Protein, DAS181

We describe the successful treatment of a 10-month-old female with respiratory distress secondary to Coronavirus disease 2019 (COVID-19) with the nebulized investigational drug, DAS181. Therapy was well tolerated, and the patient had minimal side effects. The patient's respiratory distress and positive viral polymerase chain reaction rapidly resolved after initiation of therapy.

Phase II Trial of Costimulation Blockade With Abatacept for Prevention of Acute GVHD

PURPOSE

Severe (grade 3-4) acute graft-versus-host disease (AGVHD) is a major cause of death after unrelated-donor (URD) hematopoietic cell transplant (HCT), resulting in particularly high mortality after HLA-mismatched transplantation. There are no approved agents for AGVHD prevention, underscoring the critical unmet need for novel therapeutics. ABA2 was a phase II trial to rigorously assess safety, efficacy, and immunologic effects of adding T-cell costimulation blockade with abatacept to calcineurin inhibitor (CNI)/methotrexate (MTX)-based GVHD prophylaxis, to test whether abatacept could decrease AGVHD.

METHODS

ABA2 enrolled adults and children with hematologic malignancies under two strata: a randomized, double-blind, placebo-controlled stratum (8/8-HLA-matched URD), comparing CNI/MTX plus abatacept with CNI/MTX plus placebo, and a single-arm stratum (7/8-HLA-mismatched URD) comparing CNI/MTX plus abatacept versus CNI/MTX CIBMTR controls. The primary end point was day +100 grade 3-4 AGVHD, with day +180 severe-AGVHD-free-survival (SGFS) a key secondary end point. Sample sizes were calculated using a higher type-1 error (0.2) as recommended for phase II trials, and were based on predicting that abatacept would reduce grade 3-4 AGVHD from 20% to 10% (8/8s) and 30% to 10% (7/8s). ABA2 enrolled 142 recipients (8/8s, median follow-up = 716 days) and 43 recipients (7/8s, median follow-up = 708 days).

RESULTS

In 8/8s, grade 3-4 AGVHD was 6.8% (abatacept) versus 14.8% (placebo) (P = .13, hazard ratio = 0.45). SGFS was 93.2% (CNI/MTX plus abatacept) versus 82% (CNI/MTX plus placebo, P = .05). In the smaller 7/8 cohort, grade 3-4 AGVHD was 2.3% (CNI/MTX plus abatacept, intention-to-treat population), which compared favorably with a nonrandomized matched cohort of CNI/MTX (30.2%, P < .001), and the SGFS was better (97.7% v 58.7%, P < .001). Immunologic analysis revealed control of T-cell activation in abatacept-treated patients.

CONCLUSION

Adding abatacept to URD HCT was safe, reduced AGVHD, and improved SGFS. These results suggest that abatacept may substantially improve AGVHD-related transplant outcomes, with a particularly beneficial impact on HLA-mismatched HCT.

EBV-directed viral-specific T-lymphocyte therapy for the treatment of EBV-driven lymphoma in two patients with primary immunodeficiency and DNA repair defects

Children with ataxia telangiectasia (AT), a primary immunodeficiency caused by mutations in ATM, which is critical for repairing DNA defects, are at risk for the development of hematologic malignancy, frequently driven by infection with Epstein-Barr virus (EBV). Conventional chemotherapy is poorly tolerated by patients with AT, with excessive toxicity even when doses are reduced. Here, we report on two patients with AT and EBV-positive neoplasms who were treated with EBV-targeted viral-specific T cells (VST). One patient had a prolonged complete response to VSTs while the other had a partial response. Therapy was well tolerated without infusion toxicity or graft-versus-host disease.

Patient iPSC-Derived Macrophages to Study Inborn Errors of the IFN-γ Responsive Pathway

Interferon γ (IFN-γ) was shown to be a macrophage activating factor already in 1984. Consistently, inborn errors of IFN-γ immunity underlie Mendelian Susceptibility to Mycobacterial Disease (MSMD). MSMD is characterized by genetic predisposition to disease caused by weakly virulent mycobacterial species. Paradoxically, macrophages from patients with MSMD were little tested. Here, we report a disease modeling platform for studying IFN-γ related pathologies using macrophages derived from patient specific induced pluripotent stem cells (iPSCs). We used iPSCs from patients with autosomal recessive complete- and partial IFN-γR2 deficiency, partial IFN-γR1 deficiency and complete STAT1 deficiency. Macrophages from all patient iPSCs showed normal morphology and IFN-γ-independent functionality like phagocytic uptake of bioparticles and internalization of cytokines. For the IFN-γ-dependent functionalities, we observed that the deficiencies played out at various stages of the IFN-γ pathway, with the complete IFN-γR2 and complete STAT1 deficient cells showing the most severe phenotypes, in terms of upregulation of surface markers and induction of downstream targets. Although iPSC-derived macrophages with partial IFN-γR1 and IFN-γR2 deficiency still showed residual induction of downstream targets, they did not reduce the mycobacterial growth when challenged with Bacillus Calmette-Guérin. Taken together, we report a disease modeling platform to study the role of macrophages in patients with inborn errors of IFN-γ immunity.

2759. Immunogenicity of Inactivated Influenza Vaccines Given Early vs. Late After Pediatric Allogeneic Hematopoietic Cell Transplantation

Background

Pediatric hematopoietic cell transplant (HCT) recipients often fail to have robust responses to influenza (flu) vaccine. We conducted a blinded phase II trial comparing high-dose (HD) trivalent inactivated vaccine (TIV) vs. standard dose (SD) quadrivalent inactivated vaccine (QIV).

Methods

Children 3–17 years old and 3–35 months post-allogeneic HCT were enrolled at 9 centers and randomized to either 2 doses of HD-TIV or SD-QIV during the 2016–2017 flu season. We compared immune responses by hemagglutination inhibition (HAI) from children 3–11 (early) vs. 12–35 (late) months (m) post-HCT to 3 common flu vaccine antigens, irrespective of vaccine type. HAI responses were evaluated at baseline (visit 1), 1 m post dose 1 (visit 2) and dose 2 (visit 3), and 7 m post dose 2 (visit 4). Geometric mean titers (GMT) were adjusted for baseline log-titer values.

Results

Thirty-one children, median age 11 (7–15) years, were enrolled; 17 (55%) were immunized early and 14 (45%) late. Over 50% of patients had a potentially seroprotective (≥1:40) HAI titer at baseline, with no significant difference post-vaccination between early and late subjects. Table 1 compares early vs late subjects with HAI seroconversion (4-fold HAI titer rise). Post dose 1, late subjects, compared with early, had higher rates of seroconversion to all influenza strains. Post dose 2, early subjects, compared with late, had increased seroconversion. Late subjects had higher GMTs for H1N1 post dose 1 and 2, H3N2 after dose 1, and strain B/VIC post dose 1 and 2 (Figure 1). Although immunogenicity waned throughout flu season, higher seroconversion rates and GMT to H3N2 and strain B/VIC were retained in late subjects.

Conclusion

Compared with subjects in early post-HCT group, late post-HCT subjects had better flu vaccine immune responses as noted by higher GMT and HAI seroconversion. However, 2 doses seemed more beneficial in the early post-HCT group. Future analyses are underway, including comparing immunogenicity of HD vs. SD flu vaccine.

Disclosures

Jennifer E. Schuster, MD, Satchel Health: Shareholder Flor M. Munoz, M.D, Biocryst: Grant/Research Support; CDC: Research Grant; Moderna: Other Financial or Material Support, Safety Monitoring Board Member/Chair; NIH: Research Grant; Novavax: Research Grant; UP to Date: Author and Editor - Royalties, Other Financial or Material Support.

Xenon-129 MRI detects ventilation deficits in paediatric stem cell transplant patients unable to perform spirometry

BACKGROUND

Early detection of pulmonary morbidity following haematopoietic stem cell transplantation (HSCT) remains an important challenge for intervention, primarily due to the insensitivity of spirometry to early change, and in paediatrics, patient compliance provides additional challenges. Regional lung ventilation abnormalities in paediatric HSCT patients were quantified using hyperpolarised xenon-129 (129Xe) magnetic resonance imaging (MRI) and compared to spirometry.

METHODS

Medically stable, paediatric allogeneic HSCT patients (n=23, ages 6-16 years) underwent an outpatient MRI scan where regional ventilation was quantified with a breath-hold of hyperpolarised 129Xe gas. Ventilation deficits, regions of the lung that ventilate poorly due to obstruction, were quantified as a ventilation defect percentage (VDP) and compared to forced expiratory volume in 1 s (FEV1), FEV1/forced vital capacity (FVC) ratio, and forced expiratory flow at 25-75% of FVC (FEF25-75%) from spirometry using linear regression.

RESULTS

The mean±sd 129Xe VDP was 10.5±9.4% (range 2.6-41.4%). 129Xe VDP correlated with FEV1, FEV1/FVC ratio and FEF25-75% (p≤0.02 for all comparisons). Ventilation deficits were detected in patients with normal spirometry (i.e. FEV1 >80%), supporting the sensitivity of 129Xe MRI to early obstruction reported in other pulmonary conditions. Seven (30%) patients could not perform spirometry, yet ventilation deficits were observed in five of these patients, detecting abnormalities that otherwise may have gone undetected and untreated until advanced.

CONCLUSION

Lung ventilation deficits were detected using hyperpolarised 129Xe gas MRI in asymptomatic paediatric HSCT patients and in a subgroup who were unable to perform reliable spirometry. 129Xe MRI provides a reliable imaging-based assessment of pulmonary involvement in this potentially difficult to diagnose paediatric population.

SUN-266 Anti-Mullerian Hormone as a Marker of Ovarian Reserve in Female Pediatric Patients Undergoing Hematopoietic Stem Cell Transplantation

Background/Methods: Gonadal dysfunction leading to infertility is a common complication after hematopoietic stem cell transplant (HSCT). Previous work by our group has shown that there is a significantly higher risk of delayed puberty and premature ovarian insufficiency among girls who receive high intensity, myeloablative conditioning (MAC) regimens compared to reduced intensity conditioning (RIC) regimens. Anti-Müllerian Hormone (AMH) is not regulated by gonadotropins and has minimal inter-cycle variations; therefore, it can be used as a marker of follicular ovarian reserve and aid in fertility counseling. We sought to assess ovarian reserve utilizing AMH levels in a retrospective study of female pediatric patients undergoing HSCT from 2013-2017 who received either MAC or RIC regimens. Results: In total, 100 female patients with a median age of 7 years had AMH levels pre-HSCT, of whom 33 (33%) also had post-HSCT levels. A wide variety of diagnoses were included: 32% had malignancy; 19% had immunodeficiency; 17% had Fanconi anemia (FA), 17% had hemoglobinopathy; 12% had non-FA marrow failure, and 3% had a metabolic disorder. Among those with pre-HSCT AMH levels, 71 (71%) had normal AMH for age, and 29 (29%) had low AMH for age. Of the 33 patients who also had post-HSCT AMH, 24 (72%) had low levels following transplantation. Twenty-five patients had both a normal pre-HSCT AMH and subsequent post-HSCT levels performed, 13 of whom (52%) received a MAC regimen and 12 of whom (48%) received RIC regimen. All (13/13) of the patients who received a MAC regimen had low AMH post-HSCT, while only 25% (3/12) of the patients who received a RIC regimen had low AMH post-HSCT (p=0.0002). Eight patients had both a low pre-HSCT AMH and subsequent post-HSCT AMH levels performed, 5 of whom received a MAC regimen and 3 of whom received a RIC regimen. All subject with low pre-HSCT AMH levels additionally had low post-HSCT AMH regardless of conditioning regimen used. Conclusions: AMH levels can be a useful marker for detection of low ovarian reserve and fertility counseling, especially if trends are followed before and after exposure to alkylating agents used for HSCT preparation. Our data show a significantly higher risk of low, downtrending AMH after exposure to high intensity MAC regimens compared to RIC regimens during childhood HSCT, which likely indicates a greater potential for infertility in patients receiving MAC regimens. These data correlate with a previous analysis demonstrating a significantly higher incidence of premature ovarian insufficiency and delayed puberty among girls receiving MAC regimens vs RIC regimens. Long-term follow up of this cohort will provide more information to understand the effects of HSCT on ovarian function and the utility of AMH as a predictor of future fertility potential.

Immune Reconstitution and Infection Patterns after Early Alemtuzumab and Reduced Intensity Transplantation for Nonmalignant Disorders in Pediatric Patients

Hematopoietic stem cell transplantation (HSCT) is a therapeutic option for many nonmalignant disorders (NMD) and is curative or prevents disease progression. Reduced-intensity conditioning (RIC) in HSCT for NMD may reduce regimen-related acute toxicities and late complications. Myeloablation is often replaced by immune suppression in RIC regimens to support donor engraftment. The pace of immune reconstitution after immune suppression by RIC regimens is influenced by agents used, donor source, and graft-versus-host disease prophylaxis/treatment. In a multicenter trial (NCT 00920972) of HSCT for NMD, a RIC regimen consisting of alemtuzumab, fludarabine, and melphalan was substituted for myeloablation. Alemtuzumab was administered early (days -21 to -19) to mitigate major lymphodepletion of the incoming graft and the risk of graft rejection. Immune reconstitution and infectious complications were prospectively monitored for 1-year post-HSCT. Seventy-one patients met inclusion criteria for this report and received marrow or peripheral blood stem cell transplants. Immune reconstitution and infections are reported for related donor (RD) and unrelated donor (URD) transplants at 3 time-points (100days, 6 months, and 1 year post-HSCT). Natural killer cell recovery was rapid, and numbers normalized in both cohorts by day +100. Mean CD3, CD4, and CD8 T-lymphocyte numbers normalized by 6 months after RD HSCT and by 1 year in the URD group. CD4 and CD8 T-lymphocyte counts were significantly higher in patients who received RD HSCT at 6 months and at 1 year, respectively, post-HSCT compared with patients who received URD HSCT. The pace of CD19 B-cell recovery was markedly different between RD and URD cohorts. Mean B-cell numbers were normal by day 100 after RD HSCT but took 1 year post-HSCT to normalize in the URD cohort. Despite these differences in immune reconstitution, the timing and nature of infections did not differ between the groups, presumably because of comparable T-lymphocyte recovery. Immune reconstitution occurred at a faster pace than in prior reports using RIC with T-cell depletion. The incidence of infections was similar for both cohorts and occurred most frequently in the first 100days post-HSCT. Viral and fungal infections occurred at a lower incidence in this cohort, with "early" alemtuzumab compared with regimens administering serotherapy in the peritransplantation period. Patients were susceptible to bacterial infections primarily in the first 100days irrespective of donor source and had no increase in mortality from the same. The overall mortality rate from infections was 1.4% at 1 year. Close monitoring and prophylaxis against bacterial infections in the first 100days post-HSCT is necessary but is followed by robust immune reconstitution, especially in the T-cell compartment.

Unrelated Donor Transplantation in Children with Thalassemia using Reduced-Intensity Conditioning: The URTH Trial

Allogeneic hematopoietic stem cell transplantation (HSCT) can cure transfusion-dependent thalassemia (TDT). In a multicenter trial we investigated the efficacy of reduced-intensity conditioning (RIC) before unrelated donor (URD) HSCT in children with TDT. Thirty-three children, ages 1 to 17 years, received bone marrow (BM) or umbilical cord blood (UCB) allografts. Median time to neutrophil engraftment was 13 days (range, 10 to 25) and 24 days (range, 18 to 49) and platelet engraftment 23 days (range, 12 to 46) and 50 days (range, 31 to 234) after BM and UCB allografts, respectively. With a median follow-up of 58 months (range, 7 to 79), overall and thalassemia-free survival was 82% (95% CI, .64% to .92%) and 79% (95% CI, .6% to .9%), respectively. The cumulative incidence of grades II to IV acute graft-versus-host disease (GVHD) after BM and UCB allografts was 24% and 44%; the 2-year cumulative incidence of chronic extensive GVHD was 29% and 21%, respectively; 71% of BM and 91% of UCB recipients discontinued systemic immunosuppression by 2 years. Six patients who had Pesaro risk class 2 (n = 5) and class 3 (n = 1) died of GVHD (n = 3), viral pneumonitis (n = 2) and pulmonary hemorrhage (n = 1). Outcomes after this RIC compared favorably with URD HSCT outcomes for TDT and supported engraftment in 32 of 33 patients. Efforts to reduce GVHD and infectious complications are being pursued further.

Team-based approach to identify cardiac toxicity in critically ill hematopoietic stem cell transplant recipients

INTRODUCTION

We observed pulmonary hypertension (PH), pericardial effusions, and left ventricular systolic dysfunction (LVSD) in multiple critically ill hematopoietic stem cell transplant (HSCT) recipients. We implemented routine structured echocardiography screening for HSCT recipients admitted to the pediatric intensive care unit (PICU) using a standardized multidisciplinary process.

METHODS

HSCT recipients admitted to the PICU with respiratory distress, hypoxia, shock, and complications related to transplant-associated thrombotic microangiopathy were screened on admission and every 1-2 weeks thereafter. Echocardiography findings requiring intervention and/or further screening included elevated right ventricular pressure, LVSD, and moderate to large pericardial effusions. All echocardiograms were compared to the patient's routine pretransplant echocardiogram.

RESULTS

Seventy HSCT recipients required echocardiography screening over a 3-year period. Echo abnormalities requiring intervention and/or further screening were found in 35 (50%) patients. Twenty-four (34%) patients were noted to have elevated right ventricular pressure; 14 (20%) were at risk for PH, while 10 (14%) had PH. All patients with PH were treated with pulmonary vasodilators. LVSD was noted in 22 (31%) patients; 15/22 (68%) received inotropic support. Moderate to large pericardial effusions were present in nine (13%) patients, with six needing pericardial drain placement.

DISCUSSION

Echocardiographic abnormalities are common in critically ill HSCT recipients. Utilization of echocardiogram screening may allow for early detection and timely intervention for cardiac complications in this high-risk cohort.

Combination of High-Dose Methylprednisolone and Defibrotide for Veno-Occlusive Disease in Pediatric Hematopoietic Stem Cell Transplant Recipients

Veno-occlusive disease (VOD) is a serious complication of hematopoietic stem cell transplant (HSCT), with high mortality in severe cases and until recently very limited therapeutic options consisting largely of supportive care. Defibrotide was recently approved in the United States for the treatment of severe VOD in patients with renal or pulmonary dysfunction after HSCT. Our group previously published on the use of high-dose methylprednisolone (500 mg/m² per dose every 12 hours for 6 doses) in patients with VOD, showing good success. A small subset of these individuals were also treated with defibrotide, but additional studies using the combination of high-dose methylprednisolone and defibrotide for the treatment of VOD are lacking. We present a single-institution retrospective chart review of 15 HSCT patients with VOD treated with the combination of high-dose methylprednisolone and defibrotide. VOD developed at a median of 17 days post-HSCT, and combination therapy was initiated within 1 day of VOD diagnosis. Twelve of 15 patients (80%) had multiorgan failure. Our single-center experience using both high-dose methylprednisolone and defibrotide showed a day +100 survival rate of 73% and an overall VOD complete resolution rate of 66.7%, higher than the rates reported in the recent literature using defibrotide alone (40% to 50% day +100 overall survival). These data suggest that the combination of high-dose steroids and defibrotide may be superior to defibrotide alone and warrant further investigation.

The use of the NARA for assessing the reading ability of children with low vision

This paper summarises the reading ability data collected from 476 children with low vision using the Neale Analysis of Reading Ability (NARA). The project aimed to generate standard reading ages for pupils with low vision using the NARA reading test. This would enable children's reading to be assessed against their partially sighted peers as well as their fully sighted peers. Standardised reading ages were generated using a linear regression technique to smooth the data. The data shows that the average reading ages for accuracy, comprehension and speed for the sample are generally below their chronological age when the comparison is made with their fully sighted peers. Guidelines for using the NARA with low vision students are presented.

Successful matched sibling donor marrow transplantation following reduced intensity conditioning in children with hemoglobinopathies

Fifty-two children with symptomatic sickle cell disease sickle cell disease (SCD) (N = 43) or transfusion-dependent thalassemia (N = 9) received matched sibling donor marrow (46), marrow and cord product (5), or cord blood (1) allografts following reduced intensity conditioning (RIC) with alemtuzumab, fludarabine, and melphalan between March 2003 and May 2014*. The Kaplan-Meier probabilities of overall and event-free survival at a median of 3.42 (range, 0.75-11.83) years were 94.2% and 92.3% for the group, 93% and 90.7% for SCD, and 100% and 100% for thalassemia, respectively. Treatment-related mortality (all related to graft versus host disease, GVHD) was noted in three (5.7%) recipients, all 17-18 years of age. Acute and chronic GVHD was noted in 23% and 13%, respectively, with 81% of recipients off immunosuppression by 1 year. Graft rejection was limited to the single umbilical cord blood recipient who had prompt autologous hematopoietic recovery. Fourteen (27%) had mixed chimerism at 1 year and beyond; all had discontinued immunosuppression between 4 and 12 months from transplant with no subsequent consequence on GVHD or rejection. Infectious complications included predominantly bacteremia (48% were staphylococcus) and CMV reactivation (43%) necessitating preemptive therapy. Lymphocyte recovery beyond 6 months was associated with subsidence of infectious complications. All patients who engrafted were transfusion independent; no strokes or pulmonary complications of SCD were noted, and pain symptoms subsided within 6 months posttransplant. These findings support using RIC for patients with hemoglobinopathy undergoing matched sibling marrow transplantation (*www.Clinical Trials.gov: NCT00920972, NCT01050855, NCT02435901).

Experience with Alemtuzumab, Fludarabine, and Melphalan Reduced-Intensity Conditioning Hematopoietic Cell Transplantation in Patients with Nonmalignant Diseases Reveals Good Outcomes and That the Risk of Mixed Chimerism Depends on Underlying Disease, Stem Cell Source, and Alemtuzumab Regimen

Alemtuzumab, fludarabine, and melphalan reduced-intensity conditioning (RIC) regimens are increasingly used for the hematopoietic cell transplantation (HCT) of pediatric and young adult patients with nonmalignant diseases. Early experience suggests that these regimens are associated with good survival but a high incidence of mixed chimerism, which we have previously shown to be influenced by the alemtuzumab schedule. We hypothesized that the underlying diagnosis and donor graft source would also affect the development of mixed chimerism and that the majority of patients would survive RIC HCT without graft loss. To examine this, we conducted a retrospective study of 206 patients with metabolic diseases, non-Fanconi anemia marrow failure disorders, and primary immune deficiencies who underwent 210 consecutive RIC HCT procedures at Cincinnati Children's Hospital. Ninety-seven percent of the patients engrafted. Mixed donor and recipient chimerism developed in 46% of patients. Patients with marrow failure had a low risk of mixed chimerism (hazard ratio [HR], .208; 95% confidence interval [CI], .061 to .709; P = .012). The risk of mixed chimerism was high in patients who received a cord blood graft (HR, 3.122; 95% CI, 1.236 to 7.888; P = .016). As expected, patients who received a proximal or higher dose per kilogram of alemtuzumab schedule also experienced higher rates of mixed chimerism (all HR > 2, all P < .05). At the time of last follow-up (median, 654 days; range, 13 to 3337), over 75% of patients had greater than 90% whole blood donor chimerism. A second transplantation was performed in 5% of patients. Three-year survival without retransplantation was 84% (95% CI, 71% to 98%) for patients who underwent transplantation with an HLA-matched sibling donor. Survival without retransplantation was negatively affected by lack of a matched related donor, increasing age, and development of grades III and IV acute graft-versus-host disease. We conclude that alemtuzumab, fludarabine, and melphalan RIC HCT offers good results for many patients and that the risk of developing mixed chimerism is influenced by underlying diagnosis, graft source, and alemtuzumab dosing.

Secondary hemophagocytic lymphohistiocytosis (HLH) from a presumed brown recluse spider bite

Systemic loxoscelism is a rare complication after Loxosceles reclusa (brown recluse spider) envenomation. Loxosceles venom contains pro-inflammatory proteins, which have been shown to be elevated in patients with hemophagocytic lymph histiocytosis. We present a case of a 10-year-old male that developed presumed systemic loxoscelism, secondary hemophagocytic lymphohistiocytosis with hepatic dysfunction and renal failure. He was treated with dexamethasone and made a full recovery.

An intermediate alemtuzumab schedule reduces the incidence of mixed chimerism following reduced-intensity conditioning hematopoietic cell transplantation for hemophagocytic lymphohistiocytosis

Reduced-intensity conditioning (RIC) improves the outcomes of hematopoietic cell transplantation (HCT) in patients with hemophagocytic lymphohistiocytosis (HLH). Proximal (ie, close to graft infusion) dosing of alemtuzumab is associated with a high incidence of mixed chimerism, whereas distal (ie, distant from graft infusion) dosing is associated with less mixed chimerism but more acute graft-versus-host disease (GVHD). The alemtuzumab dose per kilogram of body weight also influences these outcomes. We hypothesized that an intermediate alemtuzumab dosing schedule would reduce mixed chimerism and maintain a low incidence of acute GVHD. In this study, 24 consecutive HCTs were performed in patients with HLH or a related disorder using a novel intermediate alemtuzumab schedule of 1 mg/kg starting on day -14. The cumulative incidences (CIs) of mixed chimerism, upfront acute GVHD grades II-IV, and receipt of additional hematopoietic cell products after HCT were compared in patients treated with a distal alemtuzumab schedule (n = 15) and those treated with a proximal alemtuzumab schedule (n = 33). All patients received fludarabine and melphalan. The CI of mixed chimerism was 31% in the intermediate group, 72% in the proximal group (P < .01), and 75% in the distal group patients who received ≥2 mg/kg alemtuzumab (P = .03). The CI of acute GVHD grades II-IV before the development of mixed chimerism was 4% in the intermediate group, 0% in the proximal group, and 13% in the distal group (P = .04, proximal versus distal). The 1-year CI of administration of additional hematopoietic cell products for mixed chimerism (donor lymphocyte infusion ± hematopoietic stem cell boost ± repeat HCT) was 14% in the intermediate group, 53% in the proximal group (P = .01), and 38% in the distal ≥2 mg/kg alemtuzumab group (P = .02). Our findings indicate that intermediate RIC reduces the incidence of mixed chimerism, is associated with a low incidence of upfront acute GVHD, and decreases the need for additional hematopoietic cell products after HCT.