Pulmonary microbiome and transcriptome signatures reveal distinct pathobiologic states associated with mortality in two cohorts of pediatric stem cell transplant patients

Lung injury is a major determinant of survival after pediatric hematopoietic cell transplantation (HCT). A deeper understanding of the relationship between pulmonary microbes, immunity, and the lung epithelium is needed to improve outcomes. In this multicenter study, we collected 278 bronchoalveolar lavage (BAL) samples from 229 patients treated at 32 children's hospitals between 2014-2022. Using paired metatranscriptomes and human gene expression data, we identified 4 patient clusters with varying BAL composition. Among those requiring respiratory support prior to sampling, in-hospital mortality varied from 22-60% depending on the cluster (p=0.007). The most common patient subtype, Cluster 1, showed a moderate quantity and high diversity of commensal microbes with robust metabolic activity, low rates of infection, gene expression indicating alveolar macrophage predominance, and low mortality. The second most common cluster showed a very high burden of airway microbes, gene expression enriched for neutrophil signaling, frequent bacterial infections, and moderate mortality. Cluster 3 showed significant depletion of commensal microbes, a loss of biodiversity, gene expression indicative of fibroproliferative pathways, increased viral and fungal pathogens, and high mortality. Finally, Cluster 4 showed profound microbiome depletion with enrichment of Staphylococci and viruses, gene expression driven by lymphocyte activation and cellular injury, and the highest mortality. BAL clusters were modeled with a random forest classifier and reproduced in a geographically distinct validation cohort of 57 patients from The Netherlands, recapitulating similar cluster-based mortality differences (p=0.022). Degree of antibiotic exposure was strongly associated with depletion of BAL microbes and enrichment of fungi. Potential pathogens were parsed from all detected microbes by analyzing each BAL microbe relative to the overall microbiome composition, which yielded increased sensitivity for numerous previously occult pathogens. These findings support personalized interpretation of the pulmonary microenvironment in pediatric HCT, which may facilitate biology-targeted interventions to improve outcomes.

Decreased Opioid Consumption in Bone Marrow Harvest Patients Using Quadratus Lumborum Blocks in a Standardized Protocol

Purpose

Bone marrow harvesting is associated with significant postoperative pain that may have potential negative consequences for the patient and health care system. In the current absence of uniform guidelines, there exists considerable variability amongst providers with respect to perioperative analgesia, especially opioid administration. In this initiative, we explored the potential for preoperative bilateral quadratus lumborum blocks in combination with a standardized perioperative analgesic protocol to manage pain with the goal of reducing perioperative narcotic usage and thereby improving opioid stewardship.

Methods

Adults who underwent bone marrow donation from 2018 to 2020 were included in this analysis (n = 32). The pre-implementation group (n = 19) was reviewed retrospectively while the implementation group (n = 13) was evaluated prospectively. Patient demographics, pain scores, and opioid consumption were evaluated.

Results

Patient characteristics were equivalent except for anesthesia type with an increased number of patients in the implementation group undergoing spinal anesthesia. The implementation group showed significantly reduced median intraoperative (20.0 mg vs. 0.0 mg; p < 0.001) and total opioid consumption (20.5 mg vs. 0.0 mg; p < 0.001). The number of patients who received any opioids decreased from 84.2% (16/19) before implementation to 23.1% (3/13) after implementation.

Conclusion

This change in practice suggests that implementation of a standardized perioperative protocol, including bilateral quadratus lumborum blocks, for bone marrow harvest patients leads to reduced perioperative opioid administration without compromising immediate perioperative pain control.

Teriparatide Therapy in a 4-Month-Old With Severe Hypoparathyroidism

Teriparatide is a human parathyroid hormone analog approved for the treatment of osteoporosis in adult patients. Its use for hypocalcemia and hypoparathyroidism in the pediatric population is described through case reports and small case series; however, larger studies that demonstrate long-term efficacy and safety are limited. At our institution, a 4-month-old premature (gestational age: 32 weeks) infant with multiple congenital anomalies, functional athymia, and severe hypoparathyroidism and receiving calcitriol, vitamin D, and calcium carbonate supplementation was initiated on subcutaneous injection of teriparatide. During the course of treatment, her calcium carbonate, vitamin D, and calcitriol supplementation requirements substantially decreased. Teriparatide effectively increased serum ionized calcium concentrations and decreased serum phosphorus concentrations in the present case-study over a 6-month period. Teriparatide was well tolerated, and no evidence of hypercalcemia was observed throughout treatment.

Outcomes of pediatric patients with therapy-related myeloid neoplasms

Long-term outcomes after allogeneic hematopoietic cell transplantation (HCT) for therapy-related myeloid neoplasms (tMNs) are dismal. There are few multicenter studies defining prognostic factors in pediatric patients with tMNs. We have accumulated the largest cohort of pediatric patients who have undergone HCT for a tMN to perform a multivariate analysis defining factors predictive of long-term survival. Sixty-eight percent of the 401 patients underwent HCT using a myeloablative conditioning (MAC) regimen, but there were no statistically significant differences in the overall survival (OS), event-free survival (EFS), or cumulative incidence of relapse and non-relapse mortality based on the conditioning intensity. Among the recipients of MAC regimens, 38.4% of deaths were from treatment-related causes, especially acute graft versus host disease (GVHD) and end-organ failure, as compared to only 20.9% of deaths in the reduced-intensity conditioning (RIC) cohort. Exposure to total body irradiation (TBI) during conditioning and experiencing grade III/IV acute GVHD was associated with worse OS. In addition, a diagnosis of therapy-related myelodysplastic syndrome and having a structurally complex karyotype at tMN diagnosis were associated with worse EFS. Reduced-toxicity (but not reduced-intensity) regimens might help to decrease relapse while limiting mortality associated with TBI-based HCT conditioning in pediatric patients with tMNs.

Delirium in Children Undergoing Hematopoietic Cell Transplantation: A Multi-Institutional Point Prevalence Study

Introduction: Delirium occurs frequently in adults undergoing hematopoietic cell transplantation, with significant associated morbidity. Little is known about the burden of delirium in children in the peri-transplant period. This study was designed to determine delirium rates, define risk factors (demographic and treatment related), and establish feasibility of multi-institutional bedside screening for delirium in children undergoing hematopoietic cell transplant. Methods: This is a multi-institutional point prevalence study. All subjects were prospectively screened for delirium twice daily using the Cornell Assessment of Pediatric Delirium over a 10-day period. De-identified data, including basic demographics and daily characteristics, were extracted from the electronic medical record. Results: Eleven North American institutions were included, 106 children were enrolled, and 883 hospital days were captured. Delirium screening was successfully completed on more than 98% of the study days. Forty-eight children (45%) developed delirium over the course of the 10-day study. Children were diagnosed with delirium on 161/883 study days, for an overall delirium rate of 18% per day. Higher delirium rates were noted in children <5 years old (aOR 0.41 for children over 5 years), and in association with specific medications (melatonin, steroids, and tacrolimus). Conclusion: Delirium was a frequent occurrence in our study cohort, with identifiable risk factors. Delirium screening is highly feasible in the pediatric hematopoietic cell transplant patient population. A large-scale prospective longitudinal study following children throughout their transplant course is urgently needed to fully describe the epidemiology of pediatric delirium, explore the effects of delirium on patient outcomes, and establish guidelines to prevent and treat delirium in the peri-transplant period.

Outcomes of Measurable Residual Disease in Pediatric Acute Myeloid Leukemia before and after Hematopoietic Stem Cell Transplant: Validation of Difference from Normal Flow Cytometry with Chimerism Studies and Wilms Tumor 1 Gene Expression

We enrolled 150 patients in a prospective multicenter study of children with acute myeloid leukemia undergoing hematopoietic stem cell transplantation (HSCT) to compare the detection of measurable residual disease (MRD) by a "difference from normal" flow cytometry (ΔN) approach with assessment of Wilms tumor 1 (WT1) gene expression without access to the diagnostic specimen. Prospective analysis of the specimens using this approach showed that 23% of patients screened for HSCT had detectable residual disease by ΔN (.04% to 53%). Of those patients who proceeded to transplant as being in morphologic remission, 10 had detectable disease (.04% to 14%) by ΔN. The disease-free survival of this group was 10% (0 to 35%) compared with 55% (46% to 64%, P < .001) for those without disease. The ΔN assay was validated using the post-HSCT specimen by sorting abnormal or suspicious cells to confirm recipient or donor origin by chimerism studies. All 15 patients who had confirmation of tumor detection relapsed, whereas the 2 patients with suspicious phenotype cells lacking this confirmation did not. The phenotype of the relapse specimen was then used retrospectively to assess the pre-HSCT specimen, allowing identification of additional samples with low levels of MRD involvement that were previously undetected. Quantitative assessment of WT1 gene expression was not predictive of relapse or other outcomes in either pre- or post-transplant specimens. MRD detected by ΔN was highly specific, but did not identify most relapsing patients. The application of the assay was limited by poor quality among one-third of the specimens and lack of a diagnostic phenotype for comparison.

Analysis of factors affecting immune recovery and initial response to tetanus after DTaP vaccination in pediatric allogeneic HSCT patients

Transfer of donor immunity after allo-HSCT is limited, requiring re-vaccination after HSCT. The CDC 2009 guidelines introduced earlier vaccination post-HSCT with a uniform vaccination strategy. This study objective was to describe predictors of immune recovery and initial response to tetanus after DTaP vaccination post-HSCT. We conducted a retrospective chart review of pediatric allo-HSCT patients transplanted between July 1, 2007-June 30, 2012 who survived >1 yr without relapse (N = 27). Response to tetanus one month after the initial dose of DTaP was defined as a ≥4 fold increase in tetanus titers ≥1 month after vaccination. Wilcoxon rank-sum exact test and Kruskall-Wallis tests were used to analyze CD4, CD8, and CD19 counts. Exact conditional logistic regression was utilized to analyze initial tetanus vaccination response. A statistically significant increase in median CD4, CD8, and CD19 counts occurred from six to 12 months post-HSCT (p ≤ 0.0001, 0.005, 0.004). Only 36% of patients had initial tetanus vaccination response at first attempt post-HSCT. None of the variables tested were statistically significant in predicting initial tetanus response to vaccination. There was no association between predictors of immune recovery or transplant variables and initial tetanus response. A uniform vaccination strategy is unlikely to provide protective antibodies for many post-HSCT patients and should be evaluated in larger studies.

Post-hematopoietic stem cell transplant immunization practices in the Pediatric Blood and Marrow Transplant Consortium

BACKGROUND

A survey of National Marrow Donor Program transplant centers in 1995 demonstrated a wide range of immunization practices in post-hematopoietic stem cell transplant (HSCT) recipients, which led to the 2000 Centers for Disease Control and Prevention (CDC) recommendations for vaccination after HSCT. We surveyed the principal investigators of the Pediatric Blood and Marrow Transplant Consortium (PBMTC) to identify immunization practice patterns after HSCT and assess compliance with the 2000 CDC guidelines.

PROCEDURE

Approval was obtained from the Medical University of South Carolina Institutional Review Board. A 33 question survey using surveymonkey.com was distributed by email to principal investigators in the PBMTC.

RESULTS

Forty-one (40%) of the 102 pediatric HSCT centers participating in the PBMTC responded. Thirty of the responding centers completed the entire survey. For individual vaccines, compliance with the CDC guidelines ranged from 22% to 93%. Less than 20% of the centers reported schedules consistent with the 2000 CDC recommendations for both allogeneic and autologous HSCT recipients.

CONCLUSION

Despite the 2000 CDC guidelines, wide variation in post-HSCT immunization practices still exists. Updated guidelines have been needed, particularly to address the use of the pneumococcal conjugate vaccine. In conjunction with multiple other groups, the CDC recently released new immunization guidelines in October 2009. Additional data are still needed to adequately address the utility of incorporating immunologic parameters with the timing of vaccination after HSCT.

A novel mutation in type II methemoglobinemia

Type II methemoglobinemia is a somatic deficiency of cytochrome b5 reductase with severe global neurologic impairment. We report a novel mutation in exon 3 of the CYB5R3 gene on chromosome 22 consisting of homozygous 1-base pair (bp) deletion noted as c.215delG; p.Gly72AlafsX100. The patient had improvement of gross motor skills, chewing, and swallowing that may be due to the initiation of daily ascorbic acid therapy. We hypothesize that a possible response to ascorbic acid may be related to the effect of making additional ferrous iron available for its role as a cofactor in carnitine synthesis.

Pancytopenia with myelodysplasia due to copper deficiency

We present a case of pancytopenia in a 9-month-old infant with total parenteral nutrition (TPN) dependence due to short bowel syndrome. Bone marrow examination revealed left-shifted myeloid maturation, erythroid and myeloid dysplasia with normal iron stores. Serum copper level was 2 microm/dl (normal range 90-190 mcg/dl). After supplementation, copper levels normalized at 143 mcg/dl, and the macrocytic anemia, neutropenia, and thrombocytopenia resolved. Copper deficiency should be considered in the differential diagnosis of cytopenias and myelodsyplasia, particularly in the growing number of pediatric patients with TPN dependency or malabsorption.

Immunopathogenesis of adrenoleukodystrophy: current understanding

Adrenoleukodystrophy is a neurometabolic disease with a decreased ability to degrade very long chain fatty acids (VLCFA) and significant phenotypic variation. Unlike most neurometabolic diseases, the success of hematopoietic stem cell transplantation (HSCT) is based on acquiring a new immune system rather than enzyme replacement. VLCFA accumulation appears necessary but not sufficient for pathogenesis. Evidence for the involvement of different components of the immune system in the pathogenesis of the cerebral lesions (cellular, cytokines, humoral, and complement) is reviewed, along with both HSCT and non-HSCT immunologic approaches to treatment and future directions.

The "slurp" test: bedside evaluation of bulbar muscle fatigue

Patients with myasthenia gravis or other neuromuscular disorders are subject to increasing weakness of bulbar-innervated muscles, with resulting aspiration or catastrophic airway compromise. The available practical assessments of bulbar function in children are inadequate. We report our experience with the "slurp" test, a new bedside measure of bulbar function, in children with myasthenia gravis. Our experience suggests that the test is valuable for identifying patients with probable serious compromise of bulbar function, for monitoring such children during times of intercurrent illness, and for guiding therapy.