A randomized phase 2 trial of oral vitamin A for graft-versus-host disease in children and young adults.

ABSTRACT: Vitamin A plays a key role in the maintenance of gastrointestinal homeostasis and promotes a tolerogenic phenotype in tissue resident macrophages. We conducted a prospective randomized double-blinded placebo-controlled clinical trial in which 80 recipients of hematopoietic stem cell transplantation (HSCT) were randomized 1:1 to receive pretransplant high-dose vitamin A or placebo. A single oral dose of vitamin A of 4000 IU/kg, maximum 250 000 IU was given before conditioning. The primary end point was incidence of acute graft-versus-host disease (GVHD) at day +100. In an intent-to-treat analysis, incidence of acute GVHD was 12.5% in the vitamin A arm and 20% in the placebo arm (P = .5). Incidence of acute gastrointestinal (GI) GVHD was 2.5% in the vitamin A arm (P = .09) and 12.5% in the placebo arm at day +180. Incidence of chronic GVHD was 5% in the vitamin A arm and 15% in the placebo arm (P = .02) at 1 year. In an "as treated" analysis, cumulative incidence of acute GI GVHD at day +180 was 0% and 12.5% in recipients of vitamin A and placebo, respectively (P = .02), and cumulative incidence of chronic GVHD was 2.7% and 15% in recipients of vitamin A and placebo, respectively (P = .01). The only possibly attributable toxicity was asymptomatic grade 3 hyperbilirubinemia in 1 recipient of vitamin A at day +30, which self-resolved. Absolute CCR9+ CD8+ effector memory T cells, reflecting gut T-cell trafficking, were lower in the vitamin A arm at day +30 after HSCT (P = .01). Levels of serum amyloid A-1, a vitamin A transport protein with proinflammatory effects, were lower in the vitamin A arm. The vitamin A arm had lower interleukin-6 (IL-6), IL-8, and suppressor of tumorigenicity 2 levels and likely a more favorable gut microbiome and short chain fatty acids. Pre-HSCT oral vitamin A is inexpensive, has low toxicity, and reduces GVHD. This trial was registered at www.ClinicalTrials.gov as NCT03202849.

Transcriptome analysis in acute gastrointestinal graft-versus host disease reveals a unique signature in children and shared biology with pediatric inflammatory bowel disease.

We performed transcriptomic analyses on freshly frozen (n=21) and paraffin-embedded (n=35) gastrointestinal (GI) biopsies from children with and without acute acute GI graft-versus-host disease (GvHD) to study differential gene expressions. We identified 164 significant genes, 141 upregulated and 23 downregulated, in acute GvHD from freshy frozen biopsies. CHI3L1 was the top differentially expressed gene in acute GvHD, involved in macrophage recruitment and bacterial adhesion. Mitochondrial genes were among the top downregulated genes. Immune deconvolution identified a macrophage cellular signature. Weighted gene co-expression network analysis showed enrichment of genes in the ERK1/2 cascade. Transcriptome data from 206 ulcerative colitis (UC) patients were included to uncover genes and pathways shared between GvHD and UC. Comparison with the UC transcriptome showed both shared and distinct pathways. Both UC and GvHD transcriptomes shared an innate antimicrobial signature and FCγ1RA/CD64 was upregulated in both acute GvHD (log-fold increase 1.7, P=0.001) and UC. Upregulation of the ERK1/2 cascade pathway was specific to GvHD. We performed additional experiments to confirm transcriptomics. Firstly, we examined phosphorylation of ERK (pERK) by immunohistochemistry on GI biopsies (acute GvHD n=10, no GvHD n=10). pERK staining was increased in acute GvHD biopsies compared to biopsies without acute GvHD (P=0.001). Secondly, plasma CD64, measured by enzyme-linked immunsorbant assay (n=85) was elevated in acute GI GvHD (P<0.001) compared with those without and was elevated in GVHD compared with inflammatory bowel disease (n=47) (P<0.001), confirming the upregulated expression seen in the transcriptome.

A case of treatment-resistant membranous nephropathy associated with graft versus host disease successfully treated with daratumumab.

BACKGROUND: Membranous nephropathy (MN) is the most common cause of glomerulopathy after hematopoietic cell transplantation (HCT), most often occurring in the setting of graft versus host disease (GVHD). Twenty percent of patients will fail to respond to standard therapy and may progress to end stage renal disease. Here we present the case of a pediatric patient who developed chronic oral GVHD more than one-year post-HCT, who subsequently developed nephrotic syndrome (anasarca, nephrotic range proteinuria, hypoalbuminemia) and had a renal biopsy consistent with MN. Treated with ibrutinib for her GVHD, and steroids, tacrolimus, and rituximab for her MN, she failed to achieve even partial remission of her kidney disease after 8 months. Due to steroid toxicity and 0% CD19 cells on lymphocyte subpopulation flow cytometry, the decision was made to trial plasma cell depletion therapy with daratumumab. METHOD: She received three doses of daratumumab at weeks 1, 4, and 17. RESULTS: Her nephrotic syndrome resolved and her serum albumin was greater than 3.0 gm/dl by week 10. She was weaned off of both steroids and tacrolimus by week 16, at which time she had near-complete remission of her renal disease. CONCLUSION: Daratumumab may be an important, novel therapeutic option for post-HCT MN patients who are not responsive to standard therapies.

Experience with a Reduced Toxicity Allogeneic Transplant Regimen for Non-CGD Primary Immune Deficiencies Requiring Myeloablation.

PURPOSE: A need exists for reduced toxicity conditioning regimens that offer less toxicity while maintaining myeloablation, especially for primary immune deficiencies where myeloablation or high donor myeloid chimerism is required to achieve cure. We adapted a busulfan and fludarabine regimen by Gungor et al. for children and young adults undergoing allogeneic HCT for non-CGD primary immune deficiencies requiring myeloablation or high donor myeloid chimerism, and herein report our experience. METHODS: We retrospectively reviewed records of 41 consecutive patients who underwent allogeneic HCT for Wiskott-Aldrich syndrome (n = 12), primary HLH/XLP (n = 10), CD40L deficiency (n = 7), or other (n = 12) primary immune deficiencies with a conditioning regimen containing pharmacokinetic-guided busulfan dosing which achieved a cumulative AUC between 57 and 74 mg/L × h (65-80% of conventional myeloablative exposure), along with fludarabine and alemtuzumab or anti-thymocyte globulin at 3 transplant centers between 2014 and 2019. RESULTS: Forty-one patients underwent a first (n = 33) or second (n = 8) allogeneic HCT. Median age was 2.3 years (range, 0.3 years-19.8 years). All but one patient (97.5%) achieved neutrophil recovery at a median of 14 days (range, 11-34 days). One patient developed sinusoidal obstruction syndrome and two patients developed diffuse alveolar hemorrhage. Four patients developed grades II-IV acute GVHD. Three patients developed chronic GVHD. One-year overall survival was 90% (95% confidence interval [CI] 81-99%) and event-free survival was 83% (95% CI 71-94%). CONCLUSIONS: Our experience suggests that a reduced toxicity busulfan-fludarabine regimen offers low toxicity, low incidence of grades 2-4 GVHD, durable myeloid engraftment, and excellent survival, and may be considered for a variety of primary immune deficiencies where myeloablative HCT is desired.

α4ß7 Integrin expression and blockade in pediatric and young adult gastrointestinal graft-versus-host disease.

BACKGROUND: We hypothesized that α4ß7 integrin expression on effector memory T cells (TEMs) would be elevated in pediatric hematopoietic stem cell transplant (HSCT) patients before and at diagnosis of acute gastrointestinal graft-versus-host disease (GI GVHD) symptoms compared to patients without GVHD, and that clinical blockade of α4ß7 integrin with vedolizumab would be effective in pediatric GI GVHD. METHODS: We analyzed surface expression of α4ß7 integrin on T cells from 48 pediatric allogeneic HSCT recipients from our biorepository with known clinical outcomes as follows: acute GI GVHD (n = 22), isolated skin GVHD (n = 12), and no GVHD (n = 14). T-cell analyses were performed 1 week before and at GVHD diagnosis in patients with GVHD, and day +30 after HSCT in patients without GVHD. We describe clinical outcomes of seven additional patients, different from above-described 48 patients, who received vedolizumab (anti-α4ß7 integrin antibody) for the treatment of steroid-refractory acute GI GVHD. RESULTS: Expression of α4ß7 integrin on CD8+ TEMs was upregulated in patients with GI GVHD compared to the no GI GVHD (skin GVHD + no GVHD) group 1 week prior to clinical symptoms (p = .02) and at acute GI GVHD diagnosis (p = .05). Four of seven treated patients with clinical steroid-refractory acute GI GVHD were evaluable for response to vedolizumab. One patient had a complete response at day +28, while two had a partial response, and one had no response. No adverse effects directly attributable to vedolizumab were observed. CONCLUSION: Our data suggest a rationale for the blockade of α4ß7 integrin for acute GI GVHD management in children.

Invasive fungal pharyngitis in a pediatric bone marrow transplant patient.

Invasive fungal disease of the head and neck is a potentially fatal infection most commonly seen in immunocompromised patients. Even in the setting of combined surgical and medical treatment, prognosis is generally poor. We report the first pediatric case of invasive fungal pharyngitis and summarize a review of the literature. A 10-year-old female patientwith aplastic anemia status post-bone marrow transplant and accompanying immunosuppression initially presented with a diagnosis of a peritonsillar abscess. Incision and drainage did not show purulence, but culture grew out Rhizopus species. Immediately after diagnosis, the patient was treated successfully with aggressive staged surgical debridement and antifungal medications and had an excellent functional outcome 2 years after initial presentation. Invasive fungal disease is most common in the sinonasal region, but alternative sites of disease must be considered in immunocompromised patients who present with atypical symptoms.

CD38brightCD8+ T Cells Associated with the Development of Acute GVHD Are Activated, Proliferating, and Cytotoxic Trafficking Cells.

We have previously reported that a peripheral blood absolute CD38brightCD8+ effector memory T cell (TEM) population expansion of >35 cells/µL predicts the development of acute graft-versus-host disease (GVHD). We hypothesized that these T cells are activated, proliferating, and cytotoxic trafficking cells that are not a response to viral reactivation and may be involved in acute GVHD. We characterized peripheral blood T cell populations at the time of maximum CD38brightCD8+ TEM expansion in patients from our originally reported pediatric allogeneic hematopoietic cell transplantation recipient cohort. Samples were incubated with fluorochrome-conjugated antibodies directed against CD3, CD8, CD38, HLA-DR (T cell activation), Ki-67 (T cell proliferation), granzyme B (marker of cytotoxic T cells), CLA (skin trafficking), CCR5 (visceral trafficking), and CXCR6 (liver trafficking). We also incubated samples with Epstein-Barr virus (EBV) and cytomegalovirus (CMV) peptide pools and measured IFN-γ production by flow cytometry and performed EBV and CMV tetramer staining. Higher median proportions of cell expression of HLA-DR, Ki-67, granzyme B, CLA, CCR5, and CXCR6 were observed for CD38brightCD8+ T cells compared with CD38nonbrightCD8+ T cells in patients with acute GVHD (P < .05) but not in patients without acute GVHD (P not significant). No IFN-γ production was observed after incubation with CMV and EBV peptide pools. EBV-specific tetramer populations of 6.85% and 3.17% were detected in 2 patients with acute GVHD, whereas a CMV-specific tetramer population of 3.77% was detected in 1 patient with acute GVHD. No EBV- or CMV-specific tetramer populations were detected in any patient without acute GVHD. We conclude that CD38brightCD8+ T cells associated with the development of acute GVHD are activated, proliferating, and cytotoxic trafficking cells that do not appear to respond to CMV or EBV reactivation. Further studies are needed to determine whether these cells are directly involved in acute GVHD pathogenesis.

Risk Factors for Graft-versus-Host Disease in Haploidentical Hematopoietic Cell Transplantation Using Post-Transplant Cyclophosphamide.

Post-transplant cyclophosphamide (PTCy) has significantly increased the successful use of haploidentical donors with a relatively low incidence of graft-versus-host disease (GVHD). Given its increasing use, we sought to determine risk factors for GVHD after haploidentical hematopoietic cell transplantation (haplo-HCT) using PTCy. Data from the Center for International Blood and Marrow Transplant Research on adult patients with acute myeloid leukemia, acute lymphoblastic leukemia, myelodysplastic syndrome, or chronic myeloid leukemia who underwent PTCy-based haplo-HCT (2013 to 2016) were analyzed and categorized into 4 groups based on myeloablative (MA) or reduced-intensity conditioning (RIC) and bone marrow (BM) or peripheral blood (PB) graft source. In total, 646 patients were identified (MA-BM = 79, MA-PB = 183, RIC-BM = 192, RIC-PB = 192). The incidence of grade 2 to 4 acute GVHD at 6 months was highest in MA-PB (44%), followed by RIC-PB (36%), MA-BM (36%), and RIC-BM (30%) (P = .002). The incidence of chronic GVHD at 1 year was 40%, 34%, 24%, and 20%, respectively (P < .001). In multivariable analysis, there was no impact of stem cell source or conditioning regimen on grade 2 to 4 acute GVHD; however, older donor age (30 to 49 versus <29 years) was significantly associated with higher rates of grade 2 to 4 acute GVHD (hazard ratio [HR], 1.53; 95% confidence interval [CI], 1.11 to 2.12; P = .01). In contrast, PB compared to BM as a stem cell source was a significant risk factor for the development of chronic GVHD (HR, 1.70; 95% CI, 1.11 to 2.62; P = .01) in the RIC setting. There were no differences in relapse or overall survival between groups. Donor age and graft source are risk factors for acute and chronic GVHD, respectively, after PTCy-based haplo-HCT. Our results indicate that in RIC haplo-HCT, the risk of chronic GVHD is higher with PB stem cells, without any difference in relapse or overall survival.

Ibrutinib for the treatment of chronic graft-vs-host disease in pediatric hematopoietic stem cell transplant patients: A single-center experience.

cGVHD is a significant cause of morbidity and mortality after transplant. Ibrutinib has been studied as treatment for cGVHD in the adult population. Pediatric dosing and safety of ibrutinib are unknown. We conducted a retrospective review on the use of ibrutinib in 22 children with cGVHD at Cincinnati Children's Hospital Medical Center. All patients received a dose of 250 mg/m2 orally, once daily. Responses were measured at 6 months after drug initiation using the 2014 NIH consensus panel response criteria. Twenty-two patients of median age 13.5 years received ibrutinib. cGVHD grades were severe (n = 15), moderate (n = 6), and mild (n = 1). Eight patients stopped ibrutinib prior to 3 months due to adverse events or death and could not be evaluated for 6-month response. Of the 14 evaluable patients, 12 achieved a partial response at 6 months and two patients had progressive disease. Seven evaluable patients with lung involvement had stable lung function at 6 months. One patient had EBV reactivation, and one patient developed pneumococcal sepsis despite appropriate prophylaxis while on ibrutinib therapy. No fungal infections occurred while on ibrutinib. Adverse events leading to discontinuation included recurrent fevers without a source, extensive bruising, oral bleeding, gastrointestinal distress, lower GI bleeding, dizziness, elevated transaminases, and pneumococcal sepsis. Ibrutinib administration of 250 mg/m2 oral daily shows promising responses in pediatric cGVHD. Pediatric-focused pharmacokinetic-directed studies are needed to establish optimal dosing and define efficacy in children.

Pediatric and Young Adult Vulvovaginal Graft-versus-Host Disease.

Vulvovaginal graft-versus-host disease (GVHD) is an underdiagnosed and poorly recognized complication of hematopoietic stem cell transplantation (HSCT). Previous studies have reported findings restricted to predominantly adult populations. We report a case series of pediatric and young adult vulvovaginal GVHD, which was identified in 19 patients (median age, 11.8 years; range, 2.4 to 21.9 years) out of a total 302 female patients who underwent transplantation over an 8-year period at a pediatric HSCT center. The majority of patients had concomitant nongenital GVHD; only 1 patient had isolated vulvovaginal GVHD. The median time from bone marrow transplantation to diagnosis of vulvovaginal GVHD was 30 months (range, 2.3 to 97.5 months). A high percentage of the patients in our series were without vulvar or vaginal symptoms (n = 8; 42%), even though 17 patients (89%) presented with grade 3 disease based on current adult grading scales. Vulvar examination findings most frequently included interlabial and clitoral hood adhesions (89%), loss of architecture of the labia minora or clitoral hood (42%), and skin erosions or fissures (37%). Only 5 patients underwent a speculum exam, none of whom had vaginal GVHD. Examination findings of primary ovarian insufficiency (POI) can overlap with those of GVHD, and 6 patients (32%) in our cohort were diagnosed with POI. Only 1 patient was on systemic hormone replacement therapy at the time of vulvovaginal GVHD diagnosis. The majority of patients (n = 16) were treated with topical steroid therapy, with a median time to response of 43 days. Five patients (26%) had a complete response to therapy, and 10 patients (53%) had a partial response. This case series provides valuable insight into pediatric and young adult vulvovaginal GVHD and highlights the need for increased screening for vulvar disease in this population.

Impact of T Cell Dose on Outcome of T Cell-Replete HLA-Matched Allogeneic Peripheral Blood Stem Cell Transplantation.

Data on whether the T cell dose of allogeneic peripheral blood stem cell (PBSC) products influences transplantation outcomes are conflicting. Using the Center for International Blood and Marrow Transplant Research database, we identified 2736 adult patients who underwent first allogeneic PBSC transplantation for acute leukemia or myelodysplastic syndrome between 2008 and 2014 using an HLA-matched sibling donor (MSD) or an 8/8-matched unrelated donor (MUD). We excluded ex vivo and in vivo T cell-depleted transplantations. Correlative analysis was performed between CD3+ T cell dose and the risk of graft-versus-host-disease (GVHD), relapse, nonrelapse mortality (NRM), disease-free survival (DFS), and overall survival (OS). Using maximum likelihood estimation, we identified CD3+ T cell dose cutoff that separated the risk of acute GVHD (aGVHD) grade II-IV in both the MSD and MUD groups. A CD3+ T cell dose cutoff of 14 × 107 cells/kg identified MSD/low CD3+ (n = 223) and MSD/high CD3+ (n = 1214), and a dose of 15 × 107 cells/kg identified MUD/low CD3+ (n = 197) and MUD/high CD3+ (n = 1102). On univariate analysis, the MSD/high CD3+ group had a higher cumulative incidence of day +100 aGVHD grade II-IV compared with the MSD/low CD3+ group (33% versus 25%; P = .009). There were no differences between the 2 groups in engraftment rate, risk of aGVHD grade III-IV or chronic GVHD (cGVHD), NRM, relapse, DFS, or OS. The MUD/high CD3+ group had a higher cumulative incidence of day +100 aGVHD grade II-IV compared with the MUD/low CD3+ group (49% versus 41%; P = .04). There were no differences between the 2 groups in engraftment rate, risk of severe aGVHD or cGVHD, NRM, relapse, DFS, or OS. Multivariate analysis of the MSD and MUD groups failed to show an association between CD3+ T cell dose and the risk of either aGVHD grade II-IV (P = .10 and .07, respectively) or cGVHD (P = .80 and .30, respectively). Subanalysis of CD4+ T cells, CD8+ T cells, and CD4+/CD8+ ratio failed to identify cutoff values predictive of transplantation outcomes; however, using the log-rank test, the sample size was suboptimal for identifying a difference at this cutoff cell dose. In this registry study, the CD3+ T cell dose of PBSC products did not influence the risk of aGVHD or cGVHD or other transplantation outcomes when using an MSD or an 8/8-matched MUD. Subset analyses of CD4+ and CD8+ T cell doses were not possible given our small sample size.

Circulating dsDNA, endothelial injury, and complement activation in thrombotic microangiopathy and GVHD.

Transplant-associated thrombotic microangiopathy (TA-TMA) is a common and poorly recognized complication of hematopoietic stem cell transplantation (HSCT) associated with excessive complement activation, likely triggered by endothelial injury. An important missing piece is the link between endothelial injury and complement activation. We hypothesized that neutrophil extracellular traps (NETs) mechanistically link endothelial damage with complement activation and subsequent TA-TMA. Neutrophil activation releases granule proteins together with double-stranded DNA (dsDNA) to form extracellular fibers known as NETs. NETs have been shown to activate complement and can be assessed in humans by quantification of dsDNA in serum. We measured levels of dsDNA, as a surrogate for NETs in 103 consecutive pediatric allogeneic transplant recipients at day 0, +14, +30, +60, and +100. A spike in dsDNA production around day +14 during engraftment was associated with subsequent TA-TMA development. Peak dsDNA production around day +14 was associated with interleukin-8-driven neutrophil recovery. Increased dsDNA levels at days +30, +60, and +100 were also associated with increased mortality and gastrointestinal graft-versus-host disease (GVHD). NETs may serve as a mechanistic link between endothelial injury and complement activation. NET formation may be one mechanism contributing to the clinical overlap between GVHD and TA-TMA.

Lower levels of vitamin A are associated with increased gastrointestinal graft-versus-host disease in children.

Vitamin A promotes development of mucosal tolerance and enhances differentiation of regulatory T cells. Vitamin A deficiency impairs epithelial integrity, increasing intestinal permeability. We hypothesized that higher vitamin A levels would reduce the risk of graft-versus-host disease (GVHD) through reduced gastrointestinal (GI) permeability, reduced mucosal injury, and reduced lymphocyte homing to the gut. We tested this hypothesis in a cohort study of 114 consecutive patients undergoing allogeneic stem cell transplant. Free vitamin A levels were measured in plasma at day 30 posttransplant. GI GVHD was increased in patients with vitamin A levels below the median (38% vs 12.4% at 100 days, P = .0008), as was treatment-related mortality (17.7% vs 7.4% at 1 year, P = .03). Bloodstream infections were increased in patients with vitamin A levels below the median (24% vs 8% at 1 year, P = .03), supporting our hypothesis of increased intestinal permeability. The GI mucosal intestinal fatty acid-binding protein was decreased after transplant, confirming mucosal injury, but was not correlated with vitamin A levels, indicating that vitamin A did not protect against mucosal injury. Expression of the gut homing receptor CCR9 on T-effector memory cells 30 days after transplant was increased in children with vitamin A levels below the median (r = -0.34, P = .03). Taken together, these data support our hypothesis that low levels of vitamin A actively promote GI GVHD and are not simply a marker of poor nutritional status or a sicker patient. Vitamin A supplementation might improve transplant outcomes.

Post-Transplant CD34+ Selected Stem Cell "Boost" for Mixed Chimerism after Reduced-Intensity Conditioning Hematopoietic Stem Cell Transplantation in Children and Young Adults with Primary Immune Deficiencies.

Mixed chimerism and eventual graft loss occurs in a proportion of children with primary immune deficiencies receiving alemtuzumab, fludarabine, and melphalan reduced-intensity conditioning (RIC) regimens before allogeneic hematopoietic stem cell transplantation (HSCT). We investigated the usefulness of a CD34+ selected stem cell "boost" without conditioning to treat mixed chimerism in children and young adults who received predominantly an alemtuzumab, fludarabine, and melphalan RIC regimen for primary immune deficiencies and reported the outcomes. Patients with a primary immune deficiency disorder who were either enrolled on a prospective CD34+ boost study for treatment of mixed chimerism from 2011 to 2014 (n = 9) or treated with a CD34+ boost on a clinical basis from 2014 to 2016 (n = 3) were included in this analysis. Response to a CD34+ boost was defined as a rise in donor chimerism by ≥15% with donor chimerism of at least 20%, stabilization was defined as a rise in chimerism by <15% with donor chimerism ≥ 20%, and no response was defined as any decline in donor chimerism or need for a second HSCT after a CD34+ boost. Twelve patients received alemtuzumab, fludarabine, and melphalan. Median age was 4.5 years (range, .9 to 20.6), and median whole blood donor chimerism before the boost was 25% (range, 3% to 61%). Three patients (25%) met criteria for response, 1 patient (8%) was considered to have stabilization, and 8 patients (67%) had no response 12 months after the boost. None of the patients developed any complications from a CD34+ boost, including no acute graft-versus-host disease (GVHD). All patients are alive with a median follow-up of 32 months (range, 8 to 79). We conclude that a CD34+ selected stem cell boost can be considered for treatment of mixed chimerism after alemtuzumab, fludarabine, and melphalan RIC HSCT in children and young adults with primary immune deficiencies. Approximately one-third of patients can be expected to benefit from a CD34+ selected stem cell boost and may avoid the need for a second HSCT. Lack of any GVHD or toxicity makes a stem cell boost an attractive option compared with donor lymphocyte infusions for treatment of mixed chimerism.

Single Ultra-High-Dose Cholecalciferol to Prevent Vitamin D Deficiency in Pediatric Hematopoietic Stem Cell Transplantation.

Vitamin D deficiency is prevalent among childhood hematopoietic stem cell transplantation (HSCT) recipients and associated with inferior survival at 100 days after transplantation. Achieving and maintaining therapeutic vitamin D levels in HSCT recipients is extremely challenging in the first 3 to 6 months after transplantation due to poor compliance in the setting of mucositis and the concomitant use of critical transplantation drugs that interfere with vitamin D absorption. We sought to evaluate the safety and efficacy of a single, ultra-high-dose of vitamin D given before childhood HSCT to maintain levels in a therapeutic range during the peritransplantation period. Ten HSCT recipients with pretransplantation 25-OH vitamin D (25OHD) level <50 ng/mL and with no history of hypercalcemia, nephrolithiasis, or pathological fractures were enrolled on this pilot study. A single enteral vitamin D dose (maximum 600,000 IU) was administered to each patient based on weight and pretransplantation vitamin D level before the day of HSCT. Vitamin D levels between 30 and 150 ng/mL were considered therapeutic. All patients received close clinical observation and monitoring of 25OHD levels, calcium, phosphate, parathyroid hormone, urine calcium/creatinine ratio, and n-telopeptide for safety and efficacy assessment. The mean age of the study subjects was 5.8 ± 4.9 years, and the mean pretransplantation 25OHD level was 28.9 ± 13.1 ng/mL. All patients tolerated single, ultra-high-oral dose of vitamin D under direct medical supervision. No other oral vitamin D supplements were administered during the observation window of 8 weeks. Three of 10 patients received 400 IU/day of vitamin D in parenteral nutrition only for 5 days during the study window. A mean peak serum vitamin D level of 80.4 ± 28.6 ng/mL was reached at a median of 9 days after the vitamin D dose. All patients achieved a therapeutic vitamin D level of >30 ng/mL. Mean vitamin D levels were sustained at or above 30 ng/mL during the 8-week observation window. There were no electrolyte abnormalities attributed to the ultra-high-dose of vitamin D. Most patients had mildly elevated urine calcium/creatinine ratios during treatment, but none showed clinical or radiologic signs of nephrocalcinosis or nephrolithiasis. Our findings indicate that single ultra-high-oral dose vitamin D treatment given just before HSCT is safe and well tolerated in the immediate peritransplant period in children. Patients in our study were able to achieve and sustain therapeutic vitamin D levels throughout the critical period during which vitamin D insufficiency is associated with decreased overall survival. Larger prospective studies are needed to address the impact of single ultra-high-dose vitamin D treatment on HSCT outcomes.

Pretransplant Absolute Lymphocyte Counts Impact the Pharmacokinetics of Alemtuzumab.

Alemtuzumab is frequently used as part of reduced-intensity conditioning (RIC) regimens for allogeneic hematopoietic cell transplantation (HCT) in pediatric patients with nonmalignant diseases. We previously suggested an optimal day 0 targeted range of alemtuzumab, but there are no pediatric data regarding the pharmacokinetics (PK) of subcutaneous alemtuzumab to guide precision dosing trials. The goal of this study was to prospectively characterize alemtuzumab PK and to explore absolute lymphocyte count (ALC) as a predictor of interindividual variability. We prospectively enrolled 23 patients who received an alemtuzumab, fludarabine, and melphalan RIC regimen. Seventeen patients completed study and received 1 mg/kg alemtuzumab divided over 5 days subcutaneously, starting on day -14. The median age was 7 years (range, .5 to 18). Blood sampling for PK measurements and descriptive PK analyses were performed. The median maximum alemtuzumab concentration was 2.39 µg/mL (interquartile range, 1.98 to 2.92). The median terminal half-life was 5.2 days (interquartile range, 2.7 to 7.8). The median concentration at day 0 was 1.27 µg/mL (interquartile range, .35 to 1.51). Importantly, day 0 alemtuzumab levels and area under the curve negatively correlated with predose ALC and ALC area-time, respectively. In conclusion, we reported the PK of subcutaneous alemtuzumab given to pediatric allogeneic HCT patients and observed that almost all patients have persistence of lytic levels of alemtuzumab beyond day 0, at levels in excess of that needed to reduce the risk of acute graft-versus-host disease. Additionally, levels correlate with pretransplant ALC. These results will allow the development of population PK models for precision dosing trials.

Incidence and Outcomes of Central Nervous System Hemophagocytic Lymphohistiocytosis Relapse after Reduced-Intensity Conditioning Hematopoietic Stem Cell Transplantation.

Hemophagocytic lymphohistiocytosis (HLH) is an immune regulatory disorder that commonly presents with central nervous system (CNS) involvement. The only cure for genetic HLH is hematopoietic stem cell transplantation (HSCT), typically treated with reduced-intensity conditioning (RIC) regimens. We sought to estimate the incidence of CNS relapse after RIC HSCT, determine risk factors, and evaluate outcomes. We performed a retrospective chart review of 94 consecutive children and young adults with primary HLH who received RIC HSCT. CNS relapse within 1 year after transplantation was diagnosed by review of clinical symptoms, cerebral spinal fluid (CSF), and radiologic findings. Four (4.25%) patients developed symptoms of possible CNS HLH after HSCT and 3 patients were diagnosed. Eight patients underwent screening lumbar puncture because of history of active CNS disease at the onset of the conditioning regimen and 4 had evidence of continued disease. The overall incidence of CNS relapse and continued CNS disease after RIC HSCT was 8%. All patients with CNS disease after HSCT responded to CNS-directed therapy. Whole blood donor chimerism at the time of CNS relapse was low at 1% to 34%, but it remained high at 88% to 100% for patients with continued CNS disease. Overall survival for patients with CNS relapse was 50%, compared with 75% for patients without CNS disease (P = .079). Our data suggest that a low level of donor chimerism or active CNS disease at the time of transplantation increase the risk of CNS HLH after HSCT. Surveillance CSF evaluation after allogeneic RIC HSCT should be considered in patients with risk factors and CNS-directed treatment should be initiated if appropriate.

Ruxolitinib as Salvage Therapy in Steroid-Refractory Acute Graft-versus-Host Disease in Pediatric Hematopoietic Stem Cell Transplant Patients.

We describe our retrospective clinical experience with ruxolitinib for steroid-refractory acute graft-versus-host disease (GVHD) in pediatric allogeneic hematopoietic stem cell transplant (HSCT) patients. Ruxolitinib was administered orally at 5 mg twice daily for children ≥ 25 kg or 2.5 mg twice daily if <25 kg. We excluded patients who received new immune suppressive agents within 2 weeks before initiation of ruxolitinib from response analysis. Patients were called a treatment failure if ruxolitinib was stopped before completion of 4 weeks of therapy because of adverse effects and not because of progression of acute GVHD. Thirteen patients received ruxolitinib, and 11 patients were assessable for response. One patient achieved a complete response, 4 had a partial response, and 2 had no response at 4 weeks after the first ruxolitinib dose. Four patients were treatment failures. Overall response rate was 45%. Adverse effects (n = 13) included grades 3 to 4 elevated alanine transaminase (n = 7), grades 3 to 4 neutropenia (n = 5), and grade 4 thrombocytopenia (n = 3). Infectious complications in patients included for response analysis (n = 11) were Epstein-Barr viremia (n = 2), adenovirus (n = 2), BK (n = 3), bacterial infections (n = 6), and fungal infections (n = 1). Seven of 13 patients were alive at a median follow-up of 401 days (range, 219 to 969) after HSCT. We observed a high rate of reversible adverse effects in children with steroid-refractory acute GVHD and a fair overall response of ruxolitinib as a salvage therapeutic agent. Further pharmacokinetic studies are needed to determine the best-tolerated dose of ruxolitinib that will achieve efficacy without significant adverse effects.

Hematopoietic Stem Cell Transplantation Activity in Pediatric Cancer between 2008 and 2014 in the United States: A Center for International Blood and Marrow Transplant Research Report.

This Center for International Blood and Marrow Transplant Research report describes the use of hematopoietic stem cell transplantation (HSCT) in pediatric patients with cancer, 4408 undergoing allogeneic (allo) and3076 undergoing autologous (auto) HSCT in the United States between 2008 and 2014. In both settings, there was a greater proportion of boys (n = 4327; 57%), children < 10 years of age (n = 4412; 59%), whites (n = 5787; 77%), and children with a performance score ≥ 90% at HSCT (n = 6187; 83%). Leukemia was the most common indication for an allo-transplant (n = 4170; 94%), and among these, acute lymphoblastic leukemia in second complete remission (n = 829; 20%) and acute myeloid leukemia in first complete remission (n = 800; 19%) werethe most common. The most frequently used donor relation, stem cell sources, and HLA match were unrelated donor (n = 2933; 67%), bone marrow (n = 2378; 54%), and matched at 8/8 HLA antigens (n = 1098; 37%) respectively. Most allo-transplants used myeloablative conditioning (n = 4070; 92%) and calcineurin inhibitors and methotrexate (n = 2245; 51%) for acute graft-versus-host disease prophylaxis. Neuroblastoma was the most common primary neoplasm for an auto-transplant (n = 1338; 44%). Tandem auto-transplants for neuroblastoma declined after 2012 (40% in 2011, 25% in 2012, and 8% in 2014), whereas tandem auto-transplants increased for brain tumors (57% in 2008 and 77% in 2014). Allo-transplants from relatives other than HLA-identical siblings doubled between 2008 and 2014 (3% in 2008 and 6% in 2014). These trends will be monitored in future reports of transplant practices in the United States.

Defects of B-cell terminal differentiation in patients with type-1 Kabuki syndrome.

BACKGROUND: Kabuki syndrome (KS) is a complex multisystem developmental disorder associated with mutation of genes encoding histone-modifying proteins. In addition to craniofacial, intellectual, and cardiac defects, KS is also characterized by humoral immune deficiency and autoimmune disease, yet no detailed molecular characterization of the KS-associated immune phenotype has been reported. OBJECTIVE: We sought to characterize the humoral immune defects found in patients with KS with lysine methyltransferase 2D (KMT2D) mutations. METHODS: We comprehensively characterized B-cell function in a cohort (n = 13) of patients with KS (age, 4 months to 27 years). RESULTS: Three quarters (77%) of the cohort had a detectable heterozygous KMT2D mutation (50% nonsense, 20% splice site, and 30% missense mutations), and 70% of the reported mutations are novel. Among the patients with KMT2D mutations (KMT2D(Mut/+)), hypogammaglobulinemia was detected in all but 1 patient, with IgA deficiency affecting 90% of patients and a deficiency in at least 1 other isoform seen in 40% of patients. Numbers of total memory (CD27(+)) and class-switched memory B cells (IgM(-)) were significantly reduced in patients with KMT2D(Mut/+) mutations compared with numbers in control subjects (P < .001). Patients with KMT2D(Mut/+) mutations also had significantly reduced rates of somatic hypermutation in IgG (P = .003) but not IgA or IgM heavy chain sequences. Impaired terminal differentiation was noted in primary B cells from patients with KMT2D(Mut/+) mutations. Autoimmune pathology was observed in patients with missense mutations affecting the SET domain and its adjacent domains. CONCLUSIONS: In patients with KS, autosomal dominant KMT2D mutations are associated with dysregulation of terminal B-cell differentiation, leading to humoral immune deficiency and, in some cases, autoimmunity. All patients with KS should undergo serial clinical immune evaluations.