The IPTA Nashville consensus conference on post-transplant lymphoproliferative disorders after solid organ transplantation in children: IV-consensus guidelines for the management of post-transplant lymphoproliferative disorders in children and adolescents.

The International Pediatric Transplant Association convened an expert consensus conference to assess current evidence and develop recommendations for various aspects of care relating to post-transplant lymphoproliferative disorders (PTLD) after pediatric solid organ transplantation. This report addresses the outcomes of deliberations by the PTLD Management Working Group. A strong recommendation was made for reduction in immunosuppression as the first step in management. Similarly, strong recommendations were made for the use of the anti-CD20 monoclonal antibody (rituximab) as was the case for chemotherapy in selected scenarios. In some scenarios, there is uncoupling of the strength of the recommendations from the available evidence in situations where such evidence is lacking but collective clinical experiences drive decision-making. Of note, there are no large, randomized phase III trials of any treatment for PTLD in the pediatric age group. Current gaps and future research priorities are highlighted.

Approach for defining human adenovirus infection and disease for central review adjudication in clinical studies.

BACKGROUND: Pediatric allogeneic hematopoietic cell transplant (allo-HCT) recipients are at risk for morbidity and mortality from human adenovirus (HAdV). HAdV can be detected in an asymptomatic state, referred to as infection or with signs or symptoms of illness, referred to as disease. Standardized case definitions are needed to distinguish infection from disease and allow for consistent reporting in both observational cohort studies and therapeutic clinical trials. METHODS: A working group of experts in virology, transplant infectious disease, and HCT was assembled to develop HAdV infection and disease definitions with the degree of certainty (i.e., possible, probable, and proven). Definitions were further refined through an iterative process and independently applied by two central review committees (CRCs) to 20 pediatric allo-HCT recipients with at least one HAdV-positive PCR. RESULTS: Initial HAdV infection and disease definitions were developed and updated through an iterative process after reviewing clinical and virological details for 81 subjects with at least one positive HAdV PCR detected in a clinical specimen. Independent application of final definitions to 20 HAdV positive allo-HCT recipients by two CRCs yielded similar number of HAdV infection or disease events but with variation of degree of certainty for some events. CONCLUSIONS: Application of definitions by a CRC for a study of HAdV infection and disease is feasible and can provide consistency in the assignment of outcomes. Definitions need further refinement to improve reproducibility and to provide guidance on determining clinical improvement or worsening after initial diagnosis of HAdV infection or disease.

Presentation, anagement, and outcomes of norovirus in adult and pediatric solid organ and hematopoietic stem cell transplant recipients: A multicenter, retrospective study.

BACKGROUND: Norovirus (NoV) can cause chronic relapsing and remitting diarrhea in immunocompromised patients.  Few multicenter studies have described the clinical course, outcomes, and complications of chronic NoV in transplant recipients. METHODS: A multicenter retrospective study of adult and pediatric SOT and HSCT recipients diagnosed with NoV between November 1, 2017, and February 28, 2021. Data were obtained from electronic medical records (EMR) and entered into a central REDCap database. Descriptive statistics were calculated. RESULTS: A total of 280 NoV+ patients were identified across eight sites. The majority were adults (74.1%) and SOT recipients (91.4%). Initial diagnosis of NoV occurred a median of 36 months post-Tx (IQR [15.0, 90.0]). Most NoV cases had >3 diarrheal episodes daily (66.0%), nausea and vomiting (60.1%). Duration of diarrhea varied greatly (median = 10 days, mean = 85.9 days, range (1, 2100)). 71.3% were hospitalized. Adjustment of immunosuppression, including reduction and discontinuation of mToR inhibitor, CNI, and/or MMF, was the most common management intervention for NoV. Other therapies resulted only in temporary improvement. Four patients died within 30 days and three others died by 180 days postdiagnosis. Clinically significant renal dysfunction was observed in 12.5% by 30 days and 21.4% by 180 days post-NoV diagnosis. CONCLUSION: In HSCT and SOT patients, NoV frequently resulted in severe symptoms, prolonged diarrhea (30% persistent with diarrhea for >30 days), and clinically significant renal dysfunction (up to 21% of patients). Utilized therapies did not reliably result in the resolution of infection demonstrating the need for more effective treatment.

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.

Current and Emerging Antiviral Agents in the Prevention and Treatment of Cytomegalovirus in Pediatric Transplant Recipients.

Despite current prophylaxis regimens, cytomegalovirus (CMV) is common in hematopoietic cell transplantation (HCT) and solid organ transplantation (SOT) and remains a significant cause of morbidity and mortality. Newer antiviral medications are reshaping the landscape for prevention and treatment of CMV DNAemia, infection, and disease. Letermovir is approved for CMV prevention in adult HCT patients and is attractive due to the absence of marrow suppression seen with ganciclovir/valganciclovir. Letermovir should not be routinely used for CMV treatment due to its low threshold for resistance. Maribavir is approved for the treatment of refractory or resistant CMV disease in HCT and SOT recipients ≥12 years of age, though it has no current role in CMV prevention. More research is needed to fully elucidate the roles, efficacy, and safety of these newer agents in prevention and treatment of CMV in pediatric transplant recipients.

Current Landscape and Future Directions of Pediatric Transplant Infectious Diseases.

As the field of pediatric transplant infectious diseases continues to grow, new challenges are constantly arising. Advances in immunosuppressive drugs, antimicrobial development, and novel diagnostic tests add new wrinkles to the care of pediatric transplant recipients. This progress in clinical care serves as a call to direct energy toward pediatric transplant infectious diseases research, to better understand how to use these interventions in pediatric practice.

The IPTA Nashville Consensus Conference on Post-Transplant lymphoproliferative disorders after solid organ transplantation in children: III - Consensus guidelines for Epstein-Barr virus load and other biomarker monitoring.

The International Pediatric Transplant Association convened an expert consensus conference to assess current evidence and develop recommendations for various aspects of care relating to post-transplant lymphoproliferative disorders after solid organ transplantation in children. In this report from the Viral Load and Biomarker Monitoring Working Group, we reviewed the existing literature regarding the role of Epstein-Barr viral load and other biomarkers in peripheral blood for predicting the development of PTLD, for PTLD diagnosis, and for monitoring of response to treatment. Key recommendations from the group highlighted the strong recommendation for use of the term EBV DNAemia instead of "viremia" to describe EBV DNA levels in peripheral blood as well as concerns with comparison of EBV DNAemia measurement results performed at different institutions even when tests are calibrated using the WHO international standard. The working group concluded that either whole blood or plasma could be used as matrices for EBV DNA measurement; optimal specimen type may be clinical context dependent. Whole blood testing has some advantages for surveillance to inform pre-emptive interventions while plasma testing may be preferred in the setting of clinical symptoms and treatment monitoring. However, EBV DNAemia testing alone was not recommended for PTLD diagnosis. Quantitative EBV DNAemia surveillance to identify patients at risk for PTLD and to inform pre-emptive interventions in patients who are EBV seronegative pre-transplant was recommended. In contrast, with the exception of intestinal transplant recipients or those with recent primary EBV infection prior to SOT, surveillance was not recommended in pediatric SOT recipients EBV seropositive pre-transplant. Implications of viral load kinetic parameters including peak load and viral set point on pre-emptive PTLD prevention monitoring algorithms were discussed. Use of additional markers, including measurements of EBV specific cell mediated immunity was discussed but not recommended though the importance of obtaining additional data from prospective multicenter studies was highlighted as a key research priority.

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.

A review of transplant infectious diseases and pediatric transplant infectious diseases curriculum.

PURPOSE OF REVIEW: As the volume and complexity of solid organ and hematopoietic stem cell transplantation continue to see rapid growth, the training of a specialized transplant infectious diseases physician workforce is of increasing interest and importance. This review provides an overview of the evolution of transplant infectious diseases training programs, essential elements of training, as well as future needs. RECENT FINDINGS: Despite the first publication of a transplant infectious diseases curriculum in 2010, more recent surveys of infectious diseases trainees have identified gaps in didactic curriculum, donor and recipient assessment, and safe living practices. SUMMARY: This review of transplant infectious diseases training summarizes growth through the decades, the current landscape of recommend training elements, suggested areas for continued development and expansion in training as well as novel methodologies to reach a modern trainee audience.

Absolute Monocyte Count as Early and Safe Marker for Antibiotic Cessation in Febrile Neutropenia Without Etiology in Pediatric Oncology Patients.

BACKGROUND: There is no practice standard regarding antibiotic duration in children with cancer and unexplained febrile neutropenia (FN). We hypothesized that absolute monocyte count (AMC) and absolute phagocyte count (APC= ANC + AMC + bands) are more sensitive, earlier, and safe markers of antibiotic cessation compared with absolute neutrophil count (ANC). METHODS: A retrospective review of FN episodes (FNEs) in pediatric oncology patients was conducted between 2009 and 2016. Included patients were afebrile for 24 hours and without an identified infectious source at antibiotic cessation. Primary endpoints, including recurrent fever, readmission, bloodstream infection, microbiologically documented infection, and adverse outcomes, were assessed 10 days after antibiotic cessation and compared among different bone marrow recovery parameters (ANC, AMC, APC). Secondary endpoints included length of FN stay, antibiotic-free days, and cost. RESULTS: Three hundred ninety-one FNEs in 235 patients were included. Three groups were compared based on ANC (cells/µL) at the time of antibiotic cessation: < 200 in 102 (26%), 200 to 500 in 111 (28%), and >500 in 178 (46%). No statistically significant differences in primary endpoints were identified among the 3 ANC groups; however, a trend toward unfavorable outcomes in the ANC ≤200 cells/µL group compared with the ANC >200 cells/µL was observed. Primary endpoints based on AMC >100 cells/µL at the time of antibiotic cessation showed statistically significant favorable outcomes compared AMC ≤100 cells/µL (80%, 88%, 90%, 89%, and 93% risk reduction in recurrent fever, readmission, new bloodstream infection, new microbiologically documented infection, and adverse events, respectively). Similar favorable results were seen when APC >300 cells/µL was used as a threshold for antibiotic cessation. The median length of stay for FN if discharged when AMC >100 cells/µL was 3 days shorter and associated with fewer unfavorable outcomes, thus resulting in fewer hospital days, fewer antibiotic days, and decreased cost. CONCLUSION: Our results suggest that AMC >100 cells/µL (regardless of ANC) or APC >300 cells/µL may be safe thresholds for empiric antibiotic cessation and result in reduced unfavorable clinical outcomes within 10 days postdischarge, reduced antibiotic days of therapy and reduced health care costs. Further prospective studies are needed to validate AMC as an accurate surrogate marker for antibiotic cessation in FNEs in children with cancer.

The IPTA Nashville consensus conference on Post-Transplant lymphoproliferative disorders after solid organ transplantation in children: II-consensus guidelines for prevention.

The International Pediatric Transplant Association (IPTA) convened an expert consensus conference to assess current evidence and develop recommendations for various aspects of care relating to post-transplant lymphoproliferative disorder after solid organ transplantation in children. In this report from the Prevention Working Group, we reviewed the existing literature regarding immunoprophylaxis and chemoprophylaxis, and pre-emptive strategies. While the group made a strong recommendation for pre-emptive reduction of immunosuppression at the time of EBV DNAemia (low to moderate evidence), no recommendations for use could be made for any prophylactic strategy or alternate pre-emptive strategy, largely due to insufficient or conflicting evidence. Current gaps and future research priorities are highlighted.

Cytomegalovirus in the transplant setting: Where are we now and what happens next? A report from the International CMV Symposium 2021.

The CMV Symposium in September 2021 was an international conference dedicated to cytomegalovirus (CMV) infection after solid organ or hematopoietic stem cell transplantation. This review provides an overview of the presentations given by the expert faculty, supplemented with educational clinical cases. Topics discussed include CMV epidemiology and diagnosis, the burden of CMV infection and disease, CMV-specific immunity and management of CMV in transplant settings. Major advances in the prevention and treatment of CMV in the past decade and increased understanding of CMV immunity have led to improved patient outcomes. In the future, management algorithms may be individualized based on the transplant recipient's immune profile, which will mark the start of a new era for patients with CMV.

The impact of COVID-19 on the pediatric solid organ transplant population.

The coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has significantly impacted all aspects of healthcare including solid organ transplantation. In this review, we discuss the specific impact of COVID-19 on the pediatric solid organ transplant population including access to grafts for pediatric transplant candidates as well as COVID-19 disease manifestations in pediatric transplant recipients. We address the current knowledge of prevention and management of COVID-19 in pediatric transplant recipients and provide additional information regarding social distancing, infection prevention and return to school.

Long-Term Infectious Complications of Kidney Transplantation.

Infections remain a common complication of solid-organ transplantation. Most infections in the first month after transplant are typically health care-associated infections, whereas late infections, beyond 6-12 months, are community-acquired infections. Opportunistic infections most frequently present in the first 12 months post-transplant and can be modulated on prior exposures and use of prophylaxis. In this review, we summarize the current epidemiology of postkidney transplant infections with a focus on key viral (BK polyomavirus, cytomegalovirus, Epstein-Barr virus, and norovirus), bacterial (urinary tract infections and Clostridioides difficile colitis), and fungal infections. Current guidelines for safe living post-transplant are also summarized. Literature supporting prophylaxis and vaccination is also provided.

Early stool microbiome and metabolome signatures in pediatric patients undergoing allogeneic hematopoietic cell transplantation.

BACKGROUND: The contribution of the gastrointestinal tract microbiome to outcomes after allogeneic hematopoietic cell transplantation (HCT) is increasingly recognized. Investigations of larger pediatric cohorts aimed at defining the microbiome state and associated metabolic patterns pretransplant are needed. METHODS: We sought to describe the pretransplant stool microbiome in pediatric allogenic HCT patients at four centers. We performed shotgun metagenomic sequencing and untargeted metabolic profiling on pretransplant stool samples. Samples were compared with normal age-matched controls and by clinical characteristics. We then explored associations between stool microbiome measurements and metabolite concentrations. RESULTS: We profiled stool samples from 88 pediatric allogeneic HCT patients, a median of 4 days before transplant. Pretransplant stool samples differed from healthy controls based on indices of alpha diversity and in the proportional abundance of specific taxa and bacterial genes. Relative to stool from healthy patients, samples from HCT patients had decreased proportion of Bacteroides, Ruminococcaeae, and genes involved in butyrate production, but were enriched for gammaproteobacterial species. No systematic differences in stool microbiome or metabolomic profiles by age, transplant indication, or hospital were noted. Stool metabolites demonstrated strong correlations with microbiome composition. DISCUSSION: Stool samples from pediatric allogeneic HCT patients demonstrate substantial dysbiosis early in the transplant course. As microbiome disruptions associate with adverse transplant outcomes, pediatric-specific analyses examining longitudinal microbiome and metabolome changes are imperative to identify causal associations and to inform rational design of interventions.

American Society for Transplantation and Cellular Therapy Series: #3-Prevention of Cytomegalovirus Infection and Disease After Hematopoietic Cell Transplantation.

The Practice Guidelines Committee of the American Society for Transplantation and Cellular Therapy partnered with its Transplant Infectious Disease Special Interest Group to update its 2009 compendium-style infectious diseases guidelines for the care of hematopoietic cell transplant (HCT) recipients. A new approach was taken with the goal of better serving clinical providers by publishing each standalone topic in the infectious disease series as a concise format of frequently asked questions (FAQ), tables, and figures. Adult and pediatric infectious disease and HCT content experts developed and answered FAQs. Topics were finalized with harmonized recommendations that were made by assigning an A through E strength of recommendation paired with a level of supporting evidence graded I through III. The third topic in the series focuses on the prevention of cytomegalovirus infection and disease in HCT recipients by reviewing prophylaxis and preemptive therapy approaches; key definitions, relevant risk factors, and diagnostic monitoring considerations are also reviewed.

Cystic fibrosis foundation consensus statements for the care of cystic fibrosis lung transplant recipients.

Cystic fibrosis (CF) is the indication for transplantation in approximately 15% of recipients worldwide, and Cystic Fibrosis Lung Transplant Recipients (CFLTRs) have excellent long-term outcomes. Yet, CFLTRs have unique comorbidities that require specialized care. The objective of this document is to provide recommendations to CF and lung transplant clinicians for the management of perioperative and underlying comorbidities of CFLTRs and the impact of transplantation on these comorbidities. The Cystic Fibrosis Foundation (CFF) organized a multidisciplinary committee to develop CF Lung Transplant Clinical Care Recommendations. Three workgroups were formed to develop focused questions. Following a literature search, consensus recommendations were developed by the committee members based on literature review, committee experience and iterative revisions, and in response to public comment. The committee formulated 32 recommendation statements in the topics related to infectious disease, endocrine, gastroenterology, pharmacology, mental health and family planning. Broadly, the committee recommends close coordination of care between the lung transplant team, the cystic fibrosis care center, and specialists in other disciplines with experience in the care of CF and lung transplant recipients. These consensus statements will help lung transplant providers care for CFLTRs in order to improve post-transplant outcomes in this population.