Outcomes of HLA-mismatched HSCT with TCRαß/CD19 depletion or post-HSCT cyclophosphamide for inborn errors of immunity.

HLA-mismatched transplants with either in vitro depletion of CD3+TCRαß/CD19 (TCRαß) cells or in vivo T-cell depletion using post-transplant cyclophosphamide (PTCY) have been increasingly used for patients with inborn errors of immunity (IEI). We performed a retrospective multicenter study via the EBMT registry on 306 children with IEI undergoing first transplant between 2010-2019 from an HLA-mismatched donor using TCRαß (n=167) or PTCY (n=139). Median age at HSCT was 1.2 years (range, 0.03-19.6 years). The 3-year overall survival (OS) was 78% (95% confidence interval (CI), 71-84%) after TCRαß and 66% (57-74%) after PTCY (p=0.013). Pre-HSCT morbidity score (hazard ratio (HR) 2.27, 1.07-4.80, p=0.032) and non-Busulfan/Treosulfan conditioning (HR 3.12, 1.98-4.92, p<0.001) were the only independent predictors of unfavorable OS. The 3-year event-free survival (EFS) was 58% (50-66%) after TCRαß and 57% (48-66%) after PTCY (p=0.804). Cumulative incidence of severe acute GvHD was higher after PTCY (15%, 9-21%) than TCRαß (6%, 2-9%, p=0.007), with no difference in chronic GvHD (PTCY, 11%, 6-17%; TCRαß, 7%, 3-11%, p=0.173). The 3-year GvHD-free EFS was 53% (44-61%) after TCRαß and 41% (32-50%) after PTCY (p=0.080). PTCY had significantly higher rates of veno-occlusive disease (14.4% versus TCRαß 4.9%, p=0.009), acute kidney injury (12.7% versus 4.6%, p=0.032) and pulmonary complications (38.2% versus 24.1%, p=0.017). Adenoviraemia (18.3% versus PTCY 8.0%, p=0.015), primary graft failure (10%, versus 5%, p=0.048), and second HSCT (17.4% versus 7.9%, p=0.023) were significantly higher in TCRαß. In conclusion, this study demonstrates that both approaches are suitable options in IEI patients, although characterized by different advantages and outcomes.

Posaconazole in paediatric malignancy and haematopoietic stem cell transplant: dosing to achieve therapeutic concentration.

OBJECTIVES: Posaconazole is increasingly used for the treatment and prophylaxis of invasive fungal infections in immunocompromised children. We aimed to review evidence for paediatric posaconazole dosing regimens focusing on attainment of target concentrations and frequency of adverse effects. METHODS: In May 2023, the Cochrane, Embase, MEDLINE and PubMed databases were searched for articles reporting posaconazole dosing in children with malignancy or post-haematopoietic stem cell transplantation. Studies reporting the attainment of target serum concentrations were included. RESULTS: Overall, 24 studies were included. Eighteen studies of the oral suspension consistently reported poor attainment of target concentrations for prophylaxis (≥0.7 µg/mL, 12%-78%) despite high daily doses of 14-23 mg/kg/day (max. 1200 mg/day). Target attainment was significantly affected by gastric pH and food intake. Six studies of the delayed-release tablet (DRT) reported 58%-94% achieved concentrations ≥0.7 µg/mL, with the majority using lower doses of 4-12 mg/kg/day (max. 300 mg/day). Similarly, one study of powder for oral suspension found 67%-100% achieved target concentrations with a dose of 6 mg/kg/day (max. 300 mg/day). As expected, the IV formulation had high attainment of prophylaxis targets (81%-90%) with 6-10 mg/kg/day (max. 400 mg/day). All formulations were well tolerated, and no relationship between adverse effects and posaconazole concentrations was identified. CONCLUSIONS: The required posaconazole dose in immunocompromised children varies depending on the formulation. The IV infusion had the highest attainment of therapeutic concentration followed by the DRT and powder for suspension. By contrast, the oral suspension had low attainment of target concentrations despite higher daily doses.

Wiskott-Aldrich Syndrome: A study on 577 patients defining the genotype as a predictive biomarker for disease severity.

WAS is a multifaceted monogenic disorder with a broad disease spectrum and variable disease severity and a variety of treatment options including allogeneic hematopoietic stem cell transplantation (HSCT) and gene therapy (GT). No reliable biomarker exists to predict disease course and outcome for individual patients. A total of 577 patients with a WAS variant from 26 countries and a median follow-up of 8.9 years (0.3-71.1), totaling 6118 patient-years, were included in this international retrospective study. Overall survival (OS) of the cohort (censored at HSCT or GT) was 82% (95% CI 78-87) at 15 years and 70% (61-80) at 30 years of age. The type of variant was predictive of outcome: patients with a missense variant in exons 1 or 2 or with the intronic hotspot variant c.559+5G>A (class I variants) had a 15-year OS of 93% (89-98) and a 30-year OS of 91% (86-97), compared to 71% (62-81) and 48% (34-68) in patients with any other variant (class II; p<0.0001). The cumulative incidence rates of disease-related complications such as severe bleeding (p=0.007), life-threatening infection (p<0.0001), and autoimmunity (p=0.004) occurred significantly later in patients with a class I variant. The cumulative incidence of malignancy (p=0.6) was not different between classes I and II. This study represents the largest cohort of WAS patients studied so far. It confirms the spectrum of disease severity and quantifies the risk for specific disease-related complications. The class of variant is a biomarker to predict the outcome for WAS patients.

Detection of Bronchiolitis Obliterans Syndrome Using Nitrogen Multiple Breath Washout in Children Posthemopoietic Stem Cell Transplant.

Bronchiolitis obliterans syndrome (BOS) is a severe complication following hemopoietic stem cell transplantation (HSCT) and is often undetected until there is significant deterioration in pulmonary function. Lung clearance index (LCI2.5) derived from the nitrogen multiple breath washout (N2MBW) test may be more feasible and sensitive than spirometry, which is currently used for surveillance and detection of BOS. We aimed to examine the feasibility of performing surveillance N2MBW in children post-HSCT, and in an exploratory analysis, determine if LCI2.5 led to earlier detection of BOS when compared to spirometric indices. Participants aged 5 to 17 years were recruited prior to receiving HSCT into a prospective, single-center, feasibility study at the Royal Children's Hospital, Melbourne. N2MBW and spirometry were performed within the month prior to transplant and repeated at 3, 6, 9, and 12 months post-transplant. Data were also collected on the presence of graft-versus-host (GVHD) disease in any organ, including the lungs. Twenty-one (12 male) children with a mean age of 13.4 (range 9.2 to 17.1) years at recruitment participated in this study. Prior to HSCT, all participants had normal LCI2.5, while 16 (76%) demonstrated normal forced expiratory volume in 1 second (FEV1). Ninety-nine percent of N2MBW tests were technically acceptable, compared with 66% of spirometry tests. Three participants developed BOS, while 2 participants died of other respiratory complications. At 6 and 12 months post-transplant, the BOS group had increases in LCI2.5 ranging from 3 to 5 units and mean reductions in FEV1 % predicted of 40% to 53% relative to pre HSCT values, respectively. In those who developed BOS, post-HSCT LCI2.5 values were significantly worse when compared with the no BOS group (P < .001). Relative changes in LCI2.5 and FEV1 were both predictive of BOS at 6 months post HSCT. This study demonstrates that N2MBW is a more feasible test compared with spirometry in children post HSCT. However, in an exploratory analysis, LCI2.5 did not lead to earlier detection of BOS, when compared to spirometry.

Infections in children following chimeric antigen receptor T-cell therapy for B-cell acute lymphoblastic leukemia.

BACKGROUND: CD19-directed chimeric antigen receptor T-cell (CAR-T) therapy is transforming care for pediatric patients with relapsed or refractory B-cell acute lymphoblastic leukemia (B-ALL). There are limited pediatric-specific data concerning the infection risks associated with CD19 CAR-T therapy and the adequacy of current antimicrobial prophylaxis guidelines for these patients. METHODS: We describe the antimicrobial prophylaxis used and the types of infectious occurring in the first 100 days following CAR-T therapy for relapsed or refractory B-cell ALL in children and adolescents (≤18 years) at our centre. RESULTS: Twenty-seven patients received their first CAR-T infusion (CTI) during the study period. Almost all patients (96%) had a comprehensive Infectious Diseases review prior to CTI, which informed a personalised prophylaxis or fever/sepsis plan in six (22%). Overall, six (22%) patients had one or more infections during the study period including five (19%, 0.9 per 100 days-at-risk) from days 0-30 and three (n = 20, 15%, 0.6 per 100 days-at-risk) from days 31-100. Bacterial blood stream infections were the most common type of infection encountered during both time periods, and one patient had probable pulmonary aspergillosis. There were no infection-related deaths. CONCLUSION: Our study contributes important information on the spectrum of infections encountered in pediatric patients with B-ALL post CAR-T therapy. Overall, the burden of infectious complications post CAR-T therapy in our cohort is lower than previously reported in the literature. Results suggest that our prophylaxis recommendations are effective in this population.

ANZTCT consensus position statement on ruxolitinib in steroid-refractory acute and chronic graft-versus-host disease.

This position paper provides an overview of the assessment and management of both acute and chronic graft-versus-host disease (GvHD). There is a focus on the use of ruxolitinib, a selective inhibitor of Janus kinase (JAK)1 and JAK2, for the treatment of corticosteroid-refractory and corticosteroid-dependent GvHD.

Inborn Errors of Immunity in Children With Invasive Pneumococcal Disease: A Multicenter Prospective Study.

BACKGROUND: In settings with universal conjugate pneumococcal vaccination, invasive pneumococcal disease (IPD) can be a marker of an underlying inborn error of immunity. The aim of this study was to determine the prevalence and characterize the types of immunodeficiencies in children presenting with IPD. METHODS: Multicenter prospective audit following the introduction of routinely recommended immunological screening in children presenting with IPD. The minimum immunological evaluation comprised a full blood examination and film, serum immunoglobulins (IgG, IgA and IgM), complement levels and function. Included participants were children in whom Streptococcus pneumoniae was isolated from a normally sterile site (cerebrospinal fluid, pleura, peritoneum and synovium). If isolated from blood, features of sepsis needed to be present. Children with predisposing factors for IPD (nephrotic syndrome, anatomical defect or malignancy) were excluded. RESULTS: Overall, there were 379 episodes of IPD of which 313 (83%) were eligible for inclusion and 143/313 (46%) had an immunologic evaluation. Of these, 17/143 (12%) were diagnosed with a clinically significant abnormality: hypogammaglobulinemia (n = 4), IgA deficiency (n = 3), common variable immunodeficiency (n = 2), asplenia (n = 2), specific antibody deficiency (n = 2), incontinentia pigmenti with immunologic dysfunction (n = 1), alternative complement deficiency (n = 1), complement factor H deficiency (n = 1) and congenital disorder of glycosylation (n = 1). The number needed to investigate to identify 1 child presenting with IPD with an immunologic abnormality was 7 for children under 2 years and 9 for those 2 years old and over. CONCLUSIONS: This study supports the routine immune evaluation of children presenting with IPD of any age, with consideration of referral to a pediatric immunologist.

Incidence of Sinusoidal Obstruction Syndrome/Veno-Occlusive Disease and Treatment with Defibrotide in Allogeneic Transplantation: A Multicenter Australasian Registry Study.

Sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) is an established complication in patients undergoing allogeneic hemopoietic stem cell transplantation (HSCT). Defibrotide is an effective and safe pharmacologic option for treating diagnosed SOS/VOD. By exploring data provided to the Australasian Bone Marrow Transplant Recipient Registry (ABMTRR) by centers in Australia and New Zealand, this study aimed to describe the incidence of SOS/VOD and patterns of defibrotide use from 2016 to 2020. Patients who underwent allogeneic hemopoietic stem cell transplantation between 2016 and 2020 were identified from the ABMTRR. Data were extracted for a total of 3346 patients, 2692 from adult centers and 654 from pediatric centers, with a median follow-up of 21.5 months and 33.3 months, respectively. Descriptive statistics were used to describe the patient population, including the incidence of SOS/VOD and defibrotide use. Comparisons were made between patients without SOS/VOD and those with SOS/VOD, divided into defibrotide and no defibrotide cohorts. Associations with overall survival (OS) and day 100 survival with such variables as sex, age, disease at transplantation, stem cell source, conditioning agents, SOS/VOD diagnosis, and use of defibrotide, were determined. The reported incidence of SOS/VOD was 4.1% in adult centers and 11.5% in pediatric centers. Defibrotide was administered to 74.8% of adult patients and 97.3% of pediatric patients with SOS/VOD. Significant variability in the use, dosage, and duration of defibrotide was seen across the adult centers. The day 100 survival rate and median OS for patients managed with defibrotide was 51.8% and 103 days, respectively, for adult patients and 90.4% and not reached, respectively, for pediatric patients. In adults, older age at transplantation, an HLA-matched nonsibling relative donor, and a diagnosis of SOS/VOD treated with defibrotide were associated with reduced OS. In pediatric patients, the patient and transplantation characteristics associated with reduced OS were a diagnosis of SOS/VOD and a ≥2 HLA-mismatched related donor. A collaborative approach across Australasia to diagnosing and managing SOS/VOD, particularly with respect to consistent defibrotide use, is recommended.

Density of antibiotic use and infectious complications in pediatric allogeneic hematopoietic cell transplantation.

BACKGROUND: Antibiotics, while an essential component of supportive care in allogeneic hematopoietic cell transplantation (allo-HCT), can have adverse effects and select for antibiotic resistance. Understanding of patterns of use will inform antimicrobial stewardship (AMS) interventions. METHODS: Retrospective, single-center cohort of children undergoing first allo-HCT (n = 125). Antibiotic prescription and infection data were included from the date conditioning was commenced until 30 days post allo-HCT. Antibiotic use was reported as length of therapy (LOT) (number of days a patient received an antibiotic) and days of therapy DOT (aggregating all antibiotics prescribed per day). Infections were classified as microbiologically documented infection (MDI) or clinically documented infections. RESULTS: At least one course of antibiotics was administered to 124 (99%) patients. The LOT was 636 per 1000 patient days and DOT was 959 per 1000 patient days. The median duration of cumulative antibiotic exposure per patient was 24 days (interquartile range [IQR] 20-30 days). There were 131 days of fever per 1000 patient days with patients febrile for a median of 4 days (IQR 1-7 days). Piperacillin-tazobactam was used for 116 (94%) of patients with an LOT of 532 per 1000 patient days. A total of 119 MDI episodes occurred in 74 (59%) patients, including blood stream infection in 30 (24%) and a proven/probable invasive fungal infection in 4 (3%). CONCLUSION: Pediatric HCT patients receive prolonged courses of broad-spectrum antibiotics relative to the frequency of fever and bacterial infections. This study has identified opportunities for AMS intervention to improve outcomes for our HCT patients.

Adverse effects of antibiotics in children with cancer: are short-course antibiotics for febrile neutropenia part of the solution?

INTRODUCTION: Febrile neutropenia is a common complication experienced by children with cancer or those undergoing hematopoietic stem cell transplantation. Repeated episodes of febrile neutropenia result in cumulative exposure to broad-spectrum antibiotics with potential for a range of serious adverse effects. Short-course antibiotics, even in patients with high-risk febrile neutropenia, may offer a solution. AREAS COVERED: This review addresses the known broad effects of antibiotics, highlights developments in understanding the relationship between cancer, antibiotics, and the gut microbiome, and discusses emerging evidence regarding long-term adverse antibiotic effects. The authors consider available evidence to guide the duration of empiric antibiotics in pediatric febrile neutropenia and directions for future research. EXPERT OPINION: Broad-spectrum antibiotics are associated with antimicrobial resistance, Clostridioides difficile infection, invasive candidiasis, significant disturbance of the gut microbiome and may seriously impact outcomes in children with cancer or undergoing allogenic hematopoietic stem cell transplant. Short-course empiric antibiotics are likely safe in most children with febrile neutropenia and present a valuable opportunity to reduce the risks of antibiotic exposure.

Australia and New Zealand Transplant and Cellular Therapies (ANZTCT) position statement: COVID-19 management in patients with haemopoietic stem cell transplant and chimeric antigen receptor T cell.

Patients with post-haemopoietic stem cell transplant or chimeric antigen receptor T -cell (CAR-T) therapy face a significant risk of morbidity and mortality from coronavirus disease 2019 because of their immunosuppressed state. As case numbers in Australia and New Zealand continue to rise, guidance on management in this high-risk population is needed. Whilst we have learned much from international colleagues who faced high infection rates early in the pandemic, guidance relevant to local health system structures, medication availability and emerging therapies is essential to equip physicians to manage our patients optimally.

Use of eculizumab in children with allogeneic haematopoietic stem cell transplantation associated thrombotic microangiopathy - a multicentre retrospective PDWP and IEWP EBMT study.

Terminal complement blockade by humanised monoclonal antibody eculizumab has been used to treat transplantation-associated thrombotic microangiopathy (TA-TMA) in recent years. This retrospective international study conducted by the Paediatric Diseases (PDWP) and Inborn Error Working Party (IEWP) of the European Society for Blood and Marrow Transplantation (EBMT) describes outcome and response of 82 paediatric patients from 29 centres who developed TA-TMA and were treated with eculizumab between January 2014 and May 2019. The median time from hematopoietic stem cell transplantation (HSCT) to TA-TMA manifestation was 92 days (range: 7-606) and from TA-TMA diagnosis to the start of eculizumab treatment 6 days (range: 0-135). Most patients received eculizumab weekly (72%, n = 55) with a standard weight (kg)-based dose (78%, n = 64). Six months from beginning of eculizumab therapy, the cumulative incidence of TA-TMA resolution was 36.6% (95% CI: 26.2-47) and the overall survival (OS) was 47.1% (95% CI: 35.9-57.5). All 43 patients with unresolved TA-TMA died. The cause of death was HSCT-related in 41 patients. This study also documents poor outcome of patients without aGvHD and their frequent concomitant viral infections. Considering recent publications, intensified eculizumab dosing and complement monitoring could potentially improve upon outcomes observed in this study.

Novel approaches to the prediction and diagnosis of pulmonary complications in the paediatric haematopoietic stem cell transplant patient.

PURPOSE OF REVIEW: Haematopoietic stem cell transplant (HSCT) remains the only curative treatment option for many children with relapsed leukaemia, primary immunodeficiencies and haemoglobinopathies. Unfortunately, infectious and noninfectious pulmonary complications following HSCT continue to cause significant morbidity and mortality. This review will focus on recent advances in the field that enhance clinically available diagnostic tools and the role of novel diagnostic techniques. RECENT FINDINGS: Research continues to highlight the role of standard diagnostic modalities, including imaging using computed topography chest and Fluorodeoxyglucose-positron emission tomography (FDG-PET) in the diagnosis of posttransplant pulmonary infections. Similarly, bronchoalveolar lavage using bronchoscopy to obtain samples for microbiological analysis remains an important tool in the clinical and diagnostic algorithm for these children. The application of more novel diagnostic techniques such as metagenomic next-generation sequencing and the use of specific biomarkers remain potential future tools in children in whom the aetiology of posttransplant lung disease is unknown. The impact of the pulmonary microbiome on infectious and noninfectious pulmonary disease post HSCT is a future research direction. SUMMARY: Pulmonary infectious complications post HSCT remain a devastating complication for children and their families. Despite improvements in standard and novel diagnostic modalities, the aetiology of pulmonary disease remains unknown for many patients. There is an urgent need for ongoing collaborative research to bridge this critical knowledge gap and lead to better patient outcomes.

Genomic insights into the secondary aquatic transition of penguins.

Penguins lost the ability to fly more than 60 million years ago, subsequently evolving a hyper-specialized marine body plan. Within the framework of a genome-scale, fossil-inclusive phylogeny, we identify key geological events that shaped penguin diversification and genomic signatures consistent with widespread refugia/recolonization during major climate oscillations. We further identify a suite of genes potentially underpinning adaptations related to thermoregulation, oxygenation, diving, vision, diet, immunity and body size, which might have facilitated their remarkable secondary transition to an aquatic ecology. Our analyses indicate that penguins and their sister group (Procellariiformes) have the lowest evolutionary rates yet detected in birds. Together, these findings help improve our understanding of how penguins have transitioned to the marine environment, successfully colonizing some of the most extreme environments on Earth.

Clinical Utility of Bronchoalveolar Lavage in Pediatric Oncology Patients.

BACKGROUND: Lower airway sampling is important in the assessment of lower respiratory tract infection in children with cancer or posthematopoietic stem cell transplant and can be done via bronchoalveolar lavage (BAL). Clinicians can struggle with balancing the benefits of BAL against the risks. This study aimed to define the diagnostic and clinical utility of BAL in this population. METHODS: A single-center retrospective review of BAL performed in children with cancer or posthematopoietic stem cell transplant. Data extracted included demographics, BAL method and results and antimicrobial treatment. Variables significantly associated with diagnostic yield, diagnostic impact (confirmation or exclusion of infection), and clinical impact (any change in antimicrobial or nonantimicrobial therapy) were assessed in both univariate and multivariate analysis. RESULTS: Seventy-three BAL episodes were included. In 26 (35.6%) episodes, a pathogen was identified on BAL. Forty-nine (67%) BAL episodes had a diagnostic impact and 15 (21%) had a clinical impact. Late BAL (>72 hours) compared with early BAL (odds ratio 3.27; 95% CI: 1.03-10.86), and flexible bronchoscopy compared with nonbronchoscopic lavage (odds ratio 6.10; 95% CI: 1.90-24.0), were more likely to have a diagnostic impact on multivariate analysis. No associations were found for clinical impact. CONCLUSIONS: One-third of BAL episodes identified a pathogen, two-thirds had a diagnostic impact, and almost a quarter of episodes impacted antimicrobial prescribing. The method and timing of BAL may be important, with flexible bronchoscopy 6-fold more likely and late BAL 3-fold more likely to have a diagnostic impact.

Allergic manifestations of inborn errors of immunity and their impact on the diagnosis: A worldwide study.

Background: Allergies have long been observed in Inborn Errors of Immunity (IEI) and might even be the first presentation resulting in delayed diagnosis or misdiagnosis in some cases. However, data on the prevalence of allergic diseases among IEI patients are limited and contradictory. Objective: To provide a worldwide view of allergic diseases, across a broad spectrum of IEI, and their impact on the timely diagnosis of IEI. Methods: This is a worldwide study, conceived by the World Allergy Organization (WAO) Inborn Errors of Immunity Committee. A questionnaire was developed and pilot-tested and was sent via email to collect data from 61 immunology centers known to treat pediatric and/or adult IEI patients in 41 countries. In addition, a query was submitted to The United States Immunodeficiency Network (USIDNET) at its website. Results: Thirty centers in 23 countries caring for a total 8450 IEI patients responded. The USIDNET dataset included 2332 patients. Data from responders showed that a median (IQR) of 16.3% (10-28.8%) of patients experienced allergic diseases during the course of their IEI as follows: 3.6% (1.3-11.3%) had bronchial asthma, 3.6% (1.9-9.1%) atopic dermatitis, 3.0% (1.0-7.8%) allergic rhinitis, and 1.3% (0.5-3.3%) food allergy. As per the USIDNET data, the frequency of allergy among IEI patients was 68.8% (bronchial asthma in 46.9%). The percentage of IEI patients who presented initially with allergic disorders was 8% (5-25%) and diagnosis delay was reported in 7.5% (0.9-20.6%). Predominantly antibody deficiencies had the highest frequency of allergic disease followed by combined immunodeficiency with a frequency of 40.3% (19.2-62.5%) and 20.0% (10-32%) respectively. As per the data of centers, anaphylaxis occurred in 25/8450 patients (0.3%) whereas per USIDNET dataset, it occurred in 249/2332 (10.6%); drugs and food allergy were the main causes in both datasets. Conclusions: This multinational study brings to focus the relation between allergic diseases and IEI. Major allergies do occur in IEI patients but were less frequent than the general population. Initial presentation with allergy could adversely affect the timely diagnosis of IEI. There is a need for policies to raise awareness and educate primary care and other referring specialties on the association of allergic diseases with IEI. This study provides a network among centers for future prospective studies in the field.

Pulmonary surveillance in pediatric hematopoietic stem cell transplant: A multinational multidisciplinary survey.

BACKGROUND: Hematopoietic Stem Cell Transplant (HSCT) is an established treatment for malignant and non-malignant conditions and pulmonary disease is a leading cause of late term morbidity and mortality. Accurate and early detection of pulmonary complications is a critical step in improving long term outcomes. Existing guidelines for surveillance of pulmonary complications post-HSCT contain conflicting recommendations. AIM: To determine the breadth of current practice in monitoring for pulmonary complications of pediatric HSCT. METHODS: An institutional review board approved, online, anonymous multiple-choice survey was distributed to HSCT and pulmonary physicians from the United States of America and Australasia using the REDcap platform. The survey was developed by members of the American Thoracic Society Working Group on Complications of Childhood Cancer, and was designed to assess patient management and service design. RESULTS: A total of 40 (34.8%) responses were received. The majority (62.5%) were pulmonologists, and 82.5% were from the United States of America. In all, 67.5% reported having a protocol for monitoring pulmonary complications and 50.0% reported adhering "well" or "very well" to protocols. Pulmonary function tests (PFTs) most commonly involved spirometry and diffusion capacity for carbon monoxide. The frequency of PFTs varied depending on time post-HSCT and presence of complications. In all, 55.0% reported a set threshold for a clinically significant change in PFT. CONCLUSIONS: These results illustrate current variation in surveillance for pulmonary complications of pediatric HSCT. The results of this survey will inform development of future guidelines for monitoring of pulmonary complications after pediatric HSCT.

Reduced-Intensity/Reduced-Toxicity Conditioning Approaches Are Tolerated in XIAP Deficiency but Patients Fare Poorly with Acute GVHD.

X-linked inhibitor of apoptosis (XIAP) deficiency is an inherited primary immunodeficiency characterized by chronic inflammasome overactivity and associated with hemophagocytic lymphohistiocytosis (HLH) and inflammatory bowel disease (IBD). Allogeneic hematopoietic cell transplantation (HCT) with fully myeloablative conditioning may be curative but has been associated with poor outcomes. Reports of reduced-intensity conditioning (RIC) and reduced-toxicity conditioning (RTC) regimens suggest these approaches are well tolerated, but outcomes are not well established. Retrospective data were collected from an international cohort of 40 patients with XIAP deficiency who underwent HCT with RIC or RTC. Thirty-three (83%) patients had a history of HLH, and thirteen (33%) patients had IBD. Median age at HCT was 6.5 years. Grafts were from HLA-matched (n = 30, 75%) and HLA-mismatched (n = 10, 25%) donors. There were no cases of primary graft failure. Two (5%) patients experienced secondary graft failure, and three (8%) patients ultimately received a second HCT. Nine (23%) patients developed grade II-IV acute GVHD, and 3 (8%) developed extensive chronic GVHD. The estimated 2-year overall and event-free survival rates were 74% (CI 55-86%) and 64% (CI 46-77%), respectively. Recipient and donor HLA mismatch and grade II-IV acute GVHD were negatively associated with survival on multivariate analysis with hazard ratios of 5.8 (CI 1.5-23.3, p = 0.01) and 8.2 (CI 2.1-32.7, p < 0.01), respectively. These data suggest that XIAP patients tolerate RIC and RTC with survival rates similar to HCT of other genetic HLH disorders. Every effort should be made to prevent acute GVHD in XIAP-deficient patients who undergo allogeneic HCT.

Adaptation and Cryptic Pseudogenization in Penguin Toll-Like Receptors.

Penguins (Sphenisciformes) are an iconic order of flightless, diving seabirds distributed across a large latitudinal range in the Southern Hemisphere. The extensive area over which penguins are endemic is likely to have fostered variation in pathogen pressure, which in turn will have imposed differential selective pressures on the penguin immune system. At the front line of pathogen detection and response, the Toll-like receptors (TLRs) provide insight into host evolution in the face of microbial challenge. TLRs respond to conserved pathogen-associated molecular patterns and are frequently found to be under positive selection, despite retaining specificity for defined agonist classes. We undertook a comparative immunogenetics analysis of TLRs for all penguin species and found evidence of adaptive evolution that was largely restricted to the cell surface-expressed TLRs, with evidence of positive selection at, or near, key agonist-binding sites in TLR1B, TLR4, and TLR5. Intriguingly, TLR15, which is activated by fungal products, appeared to have been pseudogenized multiple times in the Eudyptes spp., but a full-length form was present as a rare haplotype at the population level. However, in vitro analysis revealed that even the full-length form of Eudyptes TLR15 was nonfunctional, indicating an ancestral cryptic pseudogenization prior to its eventual disruption multiple times in the Eudyptes lineage. This unusual pseudogenization event could provide an insight into immune adaptation to fungal pathogens such as Aspergillus, which is responsible for significant mortality in wild and captive bird populations.

Independent evolution of intermediate bill widths in a seabird clade.

Interspecific introgression can occur between species that evolve rapidly within an adaptive radiation. Pachyptila petrels differ in bill size and are characterised by incomplete reproductive isolation, leading to interspecific gene flow. Salvin's prion (Pachyptila salvini), whose bill width is intermediate between broad-billed (P. vittata) and Antarctic (P. desolata) prions, evolved through homoploid hybrid speciation. MacGillivray's prion (P. macgillivrayi), known from a single population on St Paul (Indian Ocean), has a bill width intermediate between salvini and vittata and could also be the product of interspecies introgression or hybrid speciation. Recently, another prion population phenotypically similar to macgillivrayi was discovered on Gough (Atlantic Ocean), where it breeds 3 months later than vittata. The similarity in bill width between the medium-billed birds on Gough and macgillivrayi suggest that they could be closely related. In this study, we used genetic and morphological data to infer the phylogenetic position and evolutionary history of P. macgillivrayi and the Gough medium-billed prion relative other Pachyptila taxa, to determine whether species with medium bill widths evolved through common ancestry or convergence. We found that Gough medium-billed prions belong to the same evolutionary lineage as macgillivrayi, representing a new population of MacGillivray's prion that originated through a colonisation event from St Paul. We show that macgillivrayi's medium bill width evolved through divergence (genetic drift) and independently from that of salvini, which evolved through hybridisation (gene flow). This represents the independent convergence towards a similarly medium-billed phenotype. The newly discovered MacGillivray's prion population on Gough is of utmost conservation relevance, as the relict macgillivrayi population in the Indian Ocean is very small.