Pediatric Immune Thrombocytopenia Patients Research Articles

The Clinical Significance of the Platelet Membrane Glycoproteins in Children with Primary Immune Thrombocytopenia

Abstract Background Primary immune thrombocytopenia (ITP) is an acquired immune-mediated disorder characterized by isolated thrombocytopenia. Although decreased platelet count is believed to be the main cause of hemorrhage in ITP, it is a poor predictor of bleeding risk by itself. Aim of the Work to measure CD62p and CD42b level in the pediatric ITP patients by using flow cytometer, measurement of platelet parameters in the pediatric ITP patients and to study its correlations to bleeding score. Patients and Methods sixty children with ITP were recruited and assessed for eligibility at the out-patients Hematology clinic – Pediatric Hospital at Ain Shams University, and compared with age and sex matched thirty healthy subjects. Results Pediatric ITP patients had a significant increase in the mean platelet volume, platelet distribution width and a significant decrease in plateletcrit among the ITP patient group in comparison with the control group (P value<0.001). The chronic ITP subgroup had significant increase of platelet count and plateletcrit in comparison with the acute ITP subgroup (P value<0.001). Pediatric ITP patients had significant increase in CD42b and a significant decrease in CD62p among the ITP patient group in comparison with the control group (P value<0.001). No statistically significant difference found between the acute, persistent and chronic ITP subgroups regarding CD42b and CD62p (P value>0.05). Conclusion Platelet function, platelet parameters and platelet glycoprotein CD62p, CD42b expression can be used as a clinical biomarkers in pediatric ITP.

Real-world experience of thrombopoietin receptor agonists in pediatric immune thrombocytopenia: a report from a Chinese tertiary children's hospital.

Primary immune thrombocytopenia (ITP) is the most common bleeding disorder in children. There are approximately 20% pediatric ITP patients respond poor to corticosteroids as first-line treatment. Recently thrombopoietin receptor agonists (TPO-RAs) have been used to treat refractory ITP and have achieved certain therapeutic effects. To investigate the efficacy and safety of TPO-RAs in the treatment of pediatric ITP, we conducted this real-world study. Fifty-three pediatric patients with ITP who did not respond well to corticosteroids were treated with TPO-RAs. Clinical data, including therapeutic response rate, changes in platelet (PLT) count, and adverse events (AEs) were collected. Of the 51 evaluable patients, 37 (72.5%) responded to TPO-RAs. Patients aged >4 years had a higher response rate than those aged ≤4 years (81.1% vs. 50.0%, P=0.04). There was no effect of sex, duration of disease, prior therapy, Mycoplasma pneumoniae (MP) immunoglobulin M (IgM) positivity, antinuclear antibody (ANA) positivity, CD4/CD8 ratio or baseline PLT count on the response rate (P>0.05). Other than 10 patients with PLT counts that exceeded the upper limit of normal, AEs were sporadic, including increased aminotransferase levels, cough, headache, and vomiting. TPO-RAs exhibited good clinical efficacy in pediatric ITP patients who failed to respond to first-line treatment, especially patients aged >4 years, and the side effects were minor.

High Titer ANA at Pediatric ITP Presentation Associated with Progression to Systemic Lupus Erythematosus

Introduction: Immune thrombocytopenia (ITP) is a feature of systemic lupus erythematosus (SLE) in 5-20% of cases. ITP may present at the time of SLE presentation or may precede SLE diagnosis by up to nearly a decade. Even in the absence of an SLE diagnosis, ITP patients may have a positive ANA in ~20% of cases. Some studies suggest that a positive ANA in ITP may herald chronic and more refractory disease, while other studies have not demonstrated a link between ANA+ ITP and progression to SLE. The natural history of ANA+ pediatric ITP patients remains unclear. With the concept that hydroxychloroquine may modulate progression to systemic autoimmunity, European hematologists report using hydroxychloroquine in ANA+ pediatric ITP patients with titers as low as 1:160. However, whether ANA+ ITP patients represent a distinct cohort clinically and should receive different therapies is not well established. The goals of this study were to evaluate the significance and degree of a positive ANA titer at presentation in a cohort of pediatric ITP patients. Methods: Data from a retrospective cohort of 711 ITP patients treated at Texas Children's Hospital from 2012-2022 were reviewed. Patients were defined as SLE if diagnosed as such by rheumatology. To focus on the prognostic value of an ANA upfront, the cohort was refined to include only ITP patients with ANA testing within the newly diagnosed period (0-3 months). Individuals who received IVIG prior to ANA testing were coded as having a missing ANA result given the possibility of false positive results. Being diagnosed concurrently with SLE and ITP was defined as diagnoses within 1 month of each other. Fisher's exact tests were used to compare nonparametric data with a P <0.05 defined as statistically significant. P values were corrected for multiple testing. Results: One hundred sixty-one ITP patients were included for analysis. The cohort was an average of 11.9 years-of-age with a slight female predominance (58.4%). Most of the population self-identified as White and non-Hispanic (84.7%, 45.5%). Nearly 80% had primary ITP and 66.7% were ultimately diagnosed with chronic ITP (cITP). The mean follow-up time for the cohort was 2.2 years (with a range from 0 to 12 years). Forty-seven of 161 (29.2%) individuals had a high titer ANA ³1:1280 at ITP presentation. (Figure 1) There was a statistically significant difference in ANA titer and presence of secondary ITP (P<0.001). Sixty-eight percent (n=23) of secondary ITP patients had a high titer (≥1:1280) ANA versus 20% (n=24) of the primary ITP patients. There was no difference between ANA titer and development of cITP vs. non-cITP. Of this cohort, 20 patients had an ANA tested at ITP presentation and were diagnosed with SLE by rheumatology. Most of these patients had an ANA titer ≥1:1280 (84.2%). The remaining 3 patients had titers of 1:320. Of this cohort, 9 patients had SLE and ITP diagnosed concurrently and 2 had SLE preceding ITP diagnosis by an average of 3.8 years. All 11 patients had an ANA ≥1:1280. Of the 9 who were not diagnosed with SLE at ITP presentation, 6 (66.6%) had an ANA ≥1:1280 and 3 had a titer of 1:320. The lead time to being diagnosed with SLE after presenting with ITP was 1.76 years. Discussion and Conclusions: In this cohort, high titer ANAs in newly diagnosed ITP patients were linked to development of secondary ITP and SLE. Lower titer ANAs were less common, even in those who went on to develop SLE. These findings suggest that specifically high titer ANA results may herald SLE development in pediatric ITP patients. To allow the onset of SLE to be identified earlier, individuals with a high titer ANA at ITP presentation may warrant closer follow-up to monitor for progression to systemic autoimmune disease. This subset of ITP patients could benefit from earlier institution of SLE-directed therapy, such as hydroxychloroquine. Further analysis is underway, including expansion of this analysis to multiple sites within the Pediatric ITP Consortium of North America, as well as surveying pediatric ITP treaters on their practice regarding ANA testing and management in ITP patients.

Genetic Variants in Canonical Wnt Signaling Pathway Associated with Pediatric ITP

Introduction : Pediatric immune thrombocytopenia (ITP) is thought to develop when a triggering event inappropriately activates an autoimmune anti-platelet response in the context of predisposing genetic factors. Inborn errors of immunity are increasingly being identified in cases of chronic, refractory autoimmune cytopenias. We sought to identify genetic variants associated with predisposition to 1) primary or secondary pediatric ITP of any disease duration versus healthy controls and 2) chronic ITP (cITP) versus disease that spontaneously resolves in < 1 year (sr-ITP). Methods : DNA and clinical data were derived from 8 sites from the Pediatric ITP Consortium of North America's (ICON) biorepository. Samples were genotyped using the Illumina Global Screening Array BeadChip. Genotypes were imputed using the Michigan Imputation Server HRC reference panel. Genetic variants that passed standard quality metrics and had a MAF ≥1% were retained. Control samples (n=8,372) were obtained from the National Longitudinal Study of Adolescent to Adult Health (Add Health) cohort. Logistic regression models were used to estimate adjusted odds ratios (aORs) comparing (1) ITP and control cohorts and (2) cITP and sr-ITP cohorts. Models assumed additive allelic effects and accounted for the top 3 principal components. Genome-wide significance was defined as P <5 × 10 -8 and suggestive of genome-wide significance, P <1 x 10 -5. Results : Six-hundred ten unique patient samples were genotyped. Nineteen (3.1%) did not pass quality control, leaving 591 for analysis. This cohort included 307 (52.0%) cITP patients, 209 (35.4%) sr-ITP patients, and 75 (12.7%) individuals without complete follow-up data to allow for classification of cITP or sr-ITP. The ITP cohort was 50.1% male, 50.1% non-Hispanic (NH) white, 29.4% Hispanic, 6.1% NH Black, 3.1% NH Asian, and 11.3% Other/Unknown. Compared with healthy controls, we identified 6 loci associated with ITP at genome-wide significance (Figure 1). Located within the intronic region of SLC24A4 rs75650997 was associated with an increased risk of ITP compared with controls (aOR: 2.38, P=3.9x10 -8). An intronic variant, rs2165798, in NAV2 was inversely associated with ITP (aOR: 0.52, P=3.2x10 -11). A variant in NKD1 rs4785216, was inversely associated with ITP (aOR: 0.43, P=8.86x10 -15).Another intergenic variant, rs4785426, in close proximity to NKD1 was also inversely associated with ITP (aOR: 0.48, P=1.84x10 -16) . An additional 20 variants met suggestive of genome-wide significance. When comparing sr-ITP and cITP patients, no SNVs (single nucleotide variant) reached genome-wide significance, but one variant, rs117609649, in ABCC4 met suggestive of genome-wide significance (aOR: 0.26, P=4.49x10 -7). Discussion : This is the largest, unbiased genetic study of pediatric ITP patients. The analysis comparing ITP versus healthy controls identified 20 suggestive SNVs and 6 which met genome-wide significance. Several of the top SNVs identified in this study affect Wnt/β-catenin signaling. Wnt-signaling impacts the development and regulation of immune cell populations including dendritic cells, macrophages, NK cells, B cells, and T cells. NAV2 activates Wnt/β-catenin signaling. NAV2 variants have been implicated in autoimmune conditions including Celiac disease and rheumatoid arthritis. NKD1 inhibits the canonical Wnt/β-catenin signaling pathway. The cumulative impact of these variants on Wnt activity in ITP should be evaluated in the future. No genetic variants met genome-wide significance in a comparison of sr-ITP and cITP patients. Collectively, these findings suggest there may be genetic variants implicated in ITP risk, but those genetic features are not specific to sr-ITP or cITP. A focused analysis of 632 genes that cause inborn errors of immunity (IEI) is ongoing. This includes gene burden testing and analysis of pathogenic variants within this gene subset. Variants in IEI genes will also be evaluated in a sub-population of patients with Evans syndrome. Conclusion : ITP is highly heterogenous in its presentation, disease course, and response to therapy. Mirroring its clinical behavior, the genetic contribution to ITP development is complex. This study identified potential SNVs associated with ITP, but not specific to sr-ITP or cITP. Variants in genes that affect the canonical Wnt-signaling pathway may play a role in ITP risk.

Pediatric immune thrombocytopenia: a focus on eltrombopag as second-line therapy

ABSTRACTBackgroundImmune thrombocytopenia (ITP) is the most common acquired bleeding disorder. In both children and adults, the primary goal of any therapeutic approach consists of cessation of bleeding and its prevention. Several options are currently available for first-line therapy in Europe, including corticosteroids and intravenous immunoglobulin (IVIg) infusion, which has a similar efficacy and safety profile in both the pediatric and adult populations. When second-line therapy is needed in the pediatric setting, current guidelines recommend eltrombopag as the drug of choice.ProcedureThe aim of this article is to summarize the available evidence and present real-life experience on eltrombopag as second-line therapy in pediatric patients with ITP, with a focus on dosing and response to therapy as well as its tapering and discontinuation.ResultsIn our setting, eltrombopag is associated with good safety profile as well as promising efficacy; dose de-escalation was feasible in 94% of cases and often reached very low pro/kg dosage, with full discontinuation in 15% of cases. In daily practice, a standardized approach for discontinuation of eltrombopag in pediatric patients with ITP is still lacking. Herein, an easy-to-use scheme for tapering and discontinuation in candidate pediatric patients is proposed that proposes 25% dose reduction every four weeks.ConclusionsIn future management of pediatric ITP patients, it will be crucial to assess if thrombopoietin receptor agonists might be more effective in earlier phases of the disease and can modify the course of the disease.

P1640: SINGLE NUCLEOTIDE POLYMORPHISMS OF THE HIF1A GENE ARE ASSOCIATED WITH SENSITIVITY OF GLUCOCORTICOID TREATMENT IN PEDIATRIC ITP PATIENTS

Background: Hypoxia-inducible factor-1α (HIF-1α) plays a crucial role in both innate and adaptive immunity. Emerging evidence indicates that HIF-1α is associated with the inflammation and pathologic activities of autoimmune diseases，suggesting that HIF1α may be involved in immune dysregulation in patients with immune thrombocytopenia (ITP). Aims: The purpose of this study was to evaluate whether single nucleotide polymorphisms (SNPs) of the HIF1A gene are associated with susceptibility to ITP and its clinical prognosis including incidence of chronic immune thrombocytopenia (CITP) and glucocorticoid sensitivity. Methods: This study involved 197 Chinese ITP pediatric patients (discovery cohort) and 220 healthy controls. The Sequenom MassArray system (Sequenom, San Diego, CA) was used to detect three SNPs genotypes in the HIF1A gene: rs11549465, rs1957757 and rs2057482. We also employed another ITP cohort (N = 127) to validate the significant results of SNPs found in the discovery cohort. Results: The frequencies of the three SNPs did not show any significant differences between the ITP and healthy control groups. The CT genotype at rs11549465 was significantly higher in ITP patients sensitive to glucocorticoid-treatment than in those insensitive to glucocorticoid-treatment (P = .025). These results were validated using another ITP cohort (N =127, P = .033). Moreover, the CC genotype was a risk factor for insensitive to GT the OR (95% confidence interval) was 5.96(5.23-6.69) in standard prednisone (PDN) (P=.0069) and 6.35(5.33-7.37) in high-dose dexamethasone (HDD) (P=.04). Summary/Conclusion: Although HIF1A gene polymorphisms were not associated with susceptibility to ITP, the CT genotype at rs11549465 was associated with the sensitivity to glucocorticoid-treatment of ITP patients, suggesting that the rs11549465 SNP may contribute to the sensitivity of glucocorticoid treatment in pediatric ITP patients.

Potential risk factors for the development from immune thrombocytopenia to systemic lupus erythematosus: a case-control study in Chinese children.

Immune thrombocytopenia (ITP) patients are at risk developing to systemic lupus erythematosus (SLE) in the future. Our study attempted to explore the potential risk factors for the development from ITP to SLE in Chinese children by statistical analysis. This study was a retrospective case-control study. Patients diagnosed with ITP and developed to SLE after the diagnosis of ITP were defined as the case group. The control group consisted of children with ITP but without developing to SLE was recruited with a ratio of 1:2. Besides univariable analysis, multivariable logistic regression was built to evaluate the potential risk factors. A total of 150 children was included with 50 in the case group and 100 in the control group. Median developing time from ITP to SLE was 34.5 [IQR 12.5, 58.75] months. ANA was found significantly different between the two groups in our study in the univariable analysis but not in the multivariable analysis (OR = 4.50, 95% CI 0.97 to 21.01). Age diagnosed ITP was positively associated with SLE (OR = 1.07 every 5years, 95% CI 1.01 to 1.15) with alert point at 8years old (sensitivity 0.82, specificity 0.60). A lower level of complement was also positively associated with SLE (OR = 8.33, 95% CI 1.62 to 42.91). A minimum 3-year of close follow-up for pediatric ITP patients was recommended to monitor the risk for developing SLE. Older age and hypocomplementemia were potential risk factors for the development from ITP to SLE.

Single Nucleotide Polymorphisms of the HIF1A Gene are Associated With Sensitivity of Glucocorticoid Treatment in Pediatric ITP Patients.

Hypoxia-inducible factor-1α (HIF-1α) plays a crucial role in both innate and adaptive immunity. Emerging evidence indicates that HIF-1α is associated with the inflammation and pathologic activities of autoimmune diseases, suggesting that HIF1α may be involved in immune dysregulation in patients with immune thrombocytopenia (ITP). The purpose of this study was to evaluate whether single nucleotide polymorphisms (SNPs) of the HIF1A gene are associated with susceptibility to ITP and its clinical prognosis including incidence of chronic ITP and glucocorticoid sensitivity. This study involved 197 Chinese ITP pediatric patients (discovery cohort) and 220 healthy controls. The Sequenom MassArray system (Sequenom, San Diego, CA) was used to detect 3 SNPs genotypes in the HIF1A gene: rs11549465, rs1957757, and rs2057482. We also used another ITP cohort (N=127) to validate the significant results of SNPs found in the discovery cohort. The frequencies of the three SNPs did not show any significant differences between the ITP and healthy control groups. The CT genotype at rs11549465 was significantly higher in ITP patients sensitive to glucocorticoid treatment than in those insensitive to glucocorticoid treatment ( P =0.025). These results were validated using another ITP cohort (N=127, P =0.033). Moreover, the CC genotype was a risk factor for insensitive to GT the odds ratio (95% confidence interval) was 5.96 (5.23-6.69) in standard prednisone ( P =0.0069) and 6.35 (5.33-7.37) in high-dose dexamethasone ( P =0.04). Although HIF1A gene polymorphisms were not associated with susceptibility to ITP, the CT genotype at rs11549465 was associated with the sensitivity to glucocorticoid treatment of ITP patients, suggesting that the rs11549465 SNP may contribute to the sensitivity of glucocorticoid treatment in pediatric ITP patients.

Standardizing the Diagnostic and Therapeutic Approach to Newly Diagnosed Children with ITP: An ITP Consortium of North America (ICON) Quality Improvement Initiative

BACKGROUNDPediatric immune thrombocytopenia (ITP) is an acquired disorder of platelet destruction that is associated with an increased risk of bleeding. Despite published guidelines for the management of ITP, the available evidence is of low grade, leading to practice variation in different settings. The use of validated bleeding scores to guide clinical decision making is inconsistent. In addition, many children are initially treated with medications despite the recommendation for observation in newly diagnosed children with ITP and no or mild bleeding symptoms. This approach leads to over-utilization of healthcare resources including hospitalizations, medication administration, and medical encounters for management-related side effects. In 2020, a quality improvement (QI) project of the Pediatric ITP Consortium of North America (ICON) was initiated to improve consistency in clinical practice at ICON sites using national ITP guidelines.DESIGN/METHODSWithin the ICON QI subcommittee, a standardized clinical care pathway (Figure 1) for newly diagnosed childhood ITP was developed based on the American Society of Hematology (ASH) 2019 guidelines. The goal was to unify approach to management, decrease practice variation, identify and learn from deviations in decision making, and decrease resource utilization by increasing observation rates in low-risk pediatric ITP patients. Site investigators shared the care pathway to update institutional providers on national guidelines. For Aim 1 of this project, sites completed a multi-center, retrospective analysis documenting the pre-QI pathway management of children, ages 1-16 years, diagnosed with ITP from January to December 2019. Statistical analysis was performed using R version 4.0.2. For Aim 2, after local dissemination and education of the clinical care pathway, clinicians at all participating sites will review the pathway at the time of managing newly diagnosed children and then complete a short survey documenting a bleeding score and management decisions.RESULTSCurrent data from the retrospective review is summarized in Figure 1. 98 patients across four ICON institutions are included in this analysis. The median age at diagnosis was 6 years (IQR 2.7, 9.2) with 61% being male. 43 (44%) patients had their first hematology encounter in the inpatient setting, 40 (41%) in the outpatient clinic, and 14 (14%) in the emergency room. Buchanan and Adix bleeding scores were obtained from only one patient (1%) at diagnosis. Treatment strategies varied including observation in 47 (48%) patients, IVIG in 40 (41%), corticosteroids in 9 (9%), and anti-D globulin in 3 (3%). 53 (54%) patients were admitted at the time of diagnosis. The prospective QI pathway is being utilized by six ICON institutions and 20 patients have been followed on the pathway since November 2020. An additional seven sites are in various phases of study activation.DISCUSSIONEvidence-based ITP guidelines and an expert consensus report have been recently published. For children with newly diagnosed ITP and a platelet count <20 x 10 9/L who have no or mild bleeding, ASH guidelines suggest against admission to the hospital and suggest observation rather than treatment with corticosteroids. Retrospective analysis of the management at four ICON centers demonstrates the variation in approach to treatment. However, although guidelines suggest initial management based on objective assessment of bleeding symptoms, only one patient (1%) had a documented bleeding score at presentation, suggesting a lack of a standard approach to management and practice variation. These data support the need for this quality initiative, which involves clinicians reviewing the pathway while managing patients and answering a survey at the time of clinical visits to report on bleeding symptoms and management. This initiative will be expanded to include a total of 13 institutions across the United States. Data will be analyzed every 1-2 years and changes will be made to the pathway with the goal of improving care. Further quality initiatives may help to standardize the management approach of pediatric ITP patients and optimize health outcomes in this patient population. [Display omitted] DisclosuresBadawy: Bluebird Bio Inc: Consultancy; Sanofi Genzyme: Consultancy; Vertex Pharmaceuticals Inc: Consultancy. Grace: Novartis: Research Funding; Dova: Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios: Research Funding; Principia: Membership on an entity's Board of Directors or advisory committees. Nakano: Novartis: Consultancy.

Evaluating Clinical Outcomes and Potential Prognostic Factors Among 308 Children and Adolescents with Immune Thrombocytopenia (ITP): An 11-Year Retrospective Cohort Study

Background:Immune thrombocytopenia (ITP) usually is a mild and self-limited disease; however, 25-30% of children develop chronic ITP. Nordic score is a validated clinical prediction tool, yet its use in children is limited and evidence for other prognostic factors is unclear.Purpose:To evaluate clinical outcomes among pediatric ITP patients, and examine their relationship to patient characteristics, including Nordic score. We hypothesized that Nordic score and patient characteristics will be predictive of ITP resolution or development of chronic ITP.Methods:We conducted a retrospective chart review of all children diagnosed with ITP at our institution between May 2008 to May 2019. Data extraction included patients' age, sex, presenting signs and symptoms, laboratory values, treatment decisions, and clinical outcomes. Nordic score calculated with 6 clinical features from diagnosis: abrupt onset <14 days, age < 10 years, preceding infection <1 month, platelet count < 5x10 9/L, wet purpura, and male sex. High scores (10-14) predict a brief disease course (<3 months), whereas low scores (0-4) predict a more prolonged course.Primary outcomes included complete response (CR) (platelets 100 x10 9/L on 2 occasions >7 days apart), recurrence (platelets < 100 after achieving CR), development of chronic ITP, and resolution (long term normal platelet count). Secondary outcomes included early response (platelets 30 x10 9/L in <1 week), time to CR, duration of CR (months between CR and recurrence), and time to resolution. Data presented as odds ratio (OR) with 95% confidence intervals. OR for Nordic score presented per 5-unit increase correlating with Nordic score categories (low 0-4, moderate 5-9, high 10-14).Results:A total of 308 patients were included (median age 5 years, IQR 2.0-10.8; 54.5% male) (Table 1). About 56% presented with platelets < 10 x10 9/L and 42% had bleeding at diagnosis (bleeding score 3 or higher), only 3% were severe. Median Nordic score was 10 (IQR 6-11). Overall, 64% of patients were treated upfront, majority (98%) receiving intravenous immunoglobulin (IVIG).Treatment at diagnosis was more likely for patients with platelets < 10 x10 9/L (OR 21, 10.4-42.5), bleeding score 3 or higher (OR 2.0, 1-4), and higher Nordic score (OR 6.2, 5.6-6.9) (Table 2). Treatment was predictive only of early response in multivariate analysis, not of CR, recurrence, development of chronic ITP, or disease resolution. Additionally, treatment at diagnosis was not associated with reduction in ITP-related complications, such as major bleeding episodes, need for platelet or red cell transfusions, or iron deficiency anemia.Overall rate of CR was 90% over a median of 1 month (IQR 0.3-4 months), while 13% had recurrence after median 19 months (IQR 8.3-26.0 months) and 32% developed chronic ITP. Overall, 80% of all study patients had resolution of ITP after median 1 month (IQR 0.3-5), with 86% achieving this before 12 months. About 36% of patients with chronic ITP had disease resolution over median 25 months (IQR 16.3-46.5 months).Univariate analysis showed significant variation across subgroups for age, viral symptoms, abrupt onset, Nordic score, hospital admission at diagnosis, platelet count, and treatment. Using multivariate regression analysis adjusted for the above variables, Nordic score was the only independent predictor of all primary outcomes. Higher Nordic score group had increased likelihood of CR (OR 6.2, 5.6-6.8) and disease resolution (OR 6.8, 5.1-8.9). Lower Nordic score group was associated with increased likelihood of recurrence (OR 6.5, 5.3-6.9) and development of chronic ITP (OR 8.6, 6.5-11.4). Additionally, higher Nordic score group was associated with increased time to recurrence and duration of response, decreased time to CR and resolution.Conclusions:In our cohort, low platelet count and bleeding symptoms were drivers of upfront treatment in pediatric ITP. Treatment initiation, associated with Nordic score, was predictive of faster increase in platelet count; however, it had no impact on overall disease trajectory or likelihood of complications. Our analysis demonstrate that Nordic score is an independent predictor of CR, resolution, recurrence, and development chronic ITP. Nordic score is a useful, simple prognostic tool that has the potential to help predict clinical course of pediatric ITP and identifying patients who may benefit from closer monitoring. [Display omitted] DisclosuresBadawy: Bluebird Bio Inc: Consultancy; Sanofi Genzyme: Consultancy; Vertex Pharmaceuticals Inc: Consultancy.

Predicting Chronic Immune Thrombocytopenia in Pediatric Patients at Disease Presentation: Leveraging Clinical and Laboratory Characteristics Via Machine Learning Models

Introduction: Pediatric immune thrombocytopenia (ITP) is the most common acquired bleeding disorder of childhood with 3-4,000 new cases annually. While most children experience self-resolving disease, 25% go on to have chronic ITP (cITP) with thrombocytopenia persisting beyond one year. Given the likelihood of spontaneous resolution and potential side effects of initial treatments, standard management for patients without severe or life-threatening bleeding is often observation. However, if it were possible to predict development of chronic disease, earlier initiation of long-term therapies could minimize bleeding risk, reduce fatigue, ease activity restrictions, and mitigate the poorer health-related quality of life that characterizes cITP.Though associations between variables and cITP have been reported, none are strong enough alone to dictate clinical decisions regarding ITP management. Machine learning (ML) is a set of statistical tools that can be utilized to make predictions or cluster data from large datasets. ML models are well suited to complex patterns within clinical datasets. ML can incorporate greater numbers of variables than could be used with traditional statistical models and can assess the impact of variables contingent upon the state of multiple other variables. In this study, we used a large clinical dataset to test a series of ML models on their ability to predict cITP development.Methods: Our group identified 696 pediatric ITP patients cared for at Texas Children's Hematology Center (TXCH) from 2012 to 2020. Of these, 332 had confirmed acute ITP (self-resolved disease in <1 year), and 253 were diagnosed with cITP. Demographic information, presenting clinical features, and laboratory data drawn within 1 month of diagnosis were tabulated for this cohort. Variables included age, gender, race, ethnicity, presence of primary ITP (defined as ITP that is not caused by another underlying disorder), presenting platelet count, absolute leukocyte count, absolute lymphocyte count, absolute eosinophil count, immature platelet fraction (IPF), mean platelet volume (MPV), direct antiglobulin test (DAT), anti-nuclear antibody (ANA) titer, and immunoglobulin levels.We tested the capabilities of several ML methods in predicting cITP using these presenting clinical and laboratory parameters. We performed a 10-fold cross validation to compare average performance metrics of a 100 tree random forest method against logistic ridge regression, support vector machine (SVM), naïve bayes, and AdaBoost methods. We tested feature importance of clinical variables with relation to cITP using the Gini index. Cross-validated ML method performance was compared using the area under the curve (AUC) receiver operator curve (ROC), as well as F1 statistic, classification accuracy (CA), precision or positive predictive value, and recall or sensitivity. Analyses was performed using Orange v2.7 (https://orangedatamining.com).Results: The top five most informative clinical features by Gini index were primary ITP, MPV, IPF, absolute lymphocyte count, and ANA titer. Comparing our five ML methods after 10-fold cross validation, the 100 tree random forest model was the top performing method on average (AUC = 0.795, CA = 0.737, F1=0.734, Precision = 0.738, Recall = 0.737). With an AUC of approximately 0.8, there is an 80% chance the model will accurately distinguish cITP from aITP. A close second performing method was the naïve bayes (AUC 0.792, CA = 0.698, F1 = 0.671, Precision = 0.737, Recall = 0.698). We present the average cross validated AUC ROC curves and the full ML method test statistics in Figure 1.Conclusions: Clinical and laboratory features present at the time of initial ITP diagnosis can be utilized to predict the development of cITP in pediatric patients using ML models. Ensemble decision tree methods are promising candidates for further ML method refinement, as AUC ROC of predicting cITP with a 100 tree RF model is > 0.7. Our group is expanding this model through incorporation of genotyping data from both acute and cITP patients. Ultimately, these ML models, in the form of an online tool, could be applied to predict cITP, allowing providers to initiate upfront interventions for those ITP patients who are unlikely to experience spontaneous disease resolution. [Display omitted] DisclosuresKirk: Biomarin: Honoraria. Powers: American Regent: Research Funding. Despotovic: Agios: Consultancy; Apellis: Consultancy; UpToDate: Patents & Royalties: Royalties; Novartis: Consultancy, Research Funding.

The Predictive Value of Vanin-1 in Pediatric Immune Thrombocytopenia

Background: Immune thrombocytopenia (ITP) has oxidative stress-related pathway as one of its possible mechanisms. Vanin-1 (VNN1) is an oxidative stress sensitive sensor. Objective: The present study was conducted to assess the clinical significance of VNN1 in pediatric ITP patients. Patients and Methods: A total of 50 kids with ITP have been involved in this work; 25 newly diagnosed, 25 chronic patients with ITP more than 12 months (15 responders and 10 non responders to treatment) and 25 apparently healthy children. All groups had their serum VNN-1 levels checked using a two-antibody sandwich enzyme-linked immunosorbent test. Results: The serum VNN1 level was significantly higher in ITP group than control group (p˂0.001). The level of serum VNN1 was significantly very high in newly diagnosed ITP group (p˂0.001) in comparison to chronic responders and chronic non responders ITP groups. Moreover, there was a significant increase in serum VNN1 level in chronic non responders ITP group (p˂0.001) compared to chronic responders group. In newly diagnosed ITP group, both age (r=-0.62, p=0.006) and the platelet count (r=-0.46, p=0.01) had a significant negative connection with serum VNN1 level. A cut-off value lower than 0.6 ng/ml for serum VNN1 could be used to distinguish the chronic non-responders ITP from chronic responders patients with 100 percent specificity and 90 percent sensitivity. Conclusion: From our current results, it is hypothesized that high VNN1 level plays a role in the pathogenesis and progress of pediatric ITP.

Re-Presentation to Medical Care Due to Adverse Effects of Intravenous Immunoglobulin Therapy in Pediatric Immune Thrombocytopenia Patients

Background : Immune Thrombocytopenia (ITP) is one of the most common acquired bleeding disorders affecting children, with an incidence rate of approximately 5-10 per 100,000 children per year. Intravenous immunoglobulin (IVIG) is an effective and widely employed frontline therapy for ITP; but is associated with substantial adverse effects, most commonly including headaches (~40%) and nausea/vomiting (5-26%). These may occur immediately following infusion or up to 72 hours later, often resulting in re-presentation to medical care. Additional diagnostic testing is often performed, including computed tomography (CT) imaging of the head, given concern for intracranial hemorrhage in these severely thrombocytopenic patients who have not yet responded to IVIG.Objective : To identify rates of re-presentation to medical care due to IVIG-associated adverse effects within a cohort of treated pediatric ITP patients, and to identify the impact of this re-presentation to care on patient safety, health-related quality of life (HRQoL), and healthcare-related costs.Methods : We completed a retrospective chart review, inclusive of all pediatric ITP patients receiving IVIG therapy at a large pediatric referral center within a 6-year timeframe from 2010 - 2016. Included patients were between the ages of 0 and 18 years, receiving IVIG for the primary indication of ITP at a dose of 1 g/kg/dose, and receiving the commercial IVIG product Gamunex-C® 10% (Grifols). All patients not meeting these criteria were excluded in order to maximize homogeneity of evaluated patients. Pre-medication with acetaminophen and diphenhydramine is the standard of practice for IVIG administration within the institution.Results : Among the 473 ITP patients who received Gamunex-C® at Texas Children's Hospital from 2010 - 2016, 133 (28%) experienced documented headache, nausea/vomiting, or both following IVIG infusion, consistent with published incidences. Among these patients, 101 (76%) sought medical care due to these symptoms. Of the 81 patients who had already been discharged, 54 (67%) re-presented for Urgent or Emergency Care services; while 27 (33%) called for medical advice or to obtain supportive prescriptions. Of the 20 patients remaining hospitalized, 100% presented as calls to the on-call physician, resulting in additional medical evaluation, often including laboratory or imaging evaluation. Among all patients re-presenting to medical care, 60 (59%) underwent additional laboratory testing, and 36 (36%) underwent CT imaging to evaluate for life-threatening intracranial bleeding. No CT evaluations revealed evidence of intracranial bleeding, and for all 101 patients re-presenting to medical care, symptoms fully resolved with supportive management.Conclusions : Nearly 1/3 of treated patients in our cohort experienced headache and/or nausea/vomiting, consistent with published incidences for Gamunex-C®. Of these, 76% sought further medical care. Subsequent medical management ranged from supportive care only (41%) to full evaluation with repeat laboratory studies (59%) + CT imaging in many cases (36%). These findings implicate substantially increased healthcare-related costs in the form of laboratory, CT imaging, and emergency service expenses; as well as increased risk to these patients' health and safety, in the form of additional radiation exposure, infection risk, and potential exposure to unnecessary therapies. Formal evaluation of downstream HRQoL and costs is ongoing. Additionally, we believe that a standardized prophylactic post-medication strategy could prevent or significantly reduce re-presentation to medical care due to IVIG-associated headache and/or nausea/vomiting, thereby improving HRQoL and cost impact in this patient population; and a formal prospective trial of this strategy is planned. [Display omitted] DisclosuresLambert:AstraZeneca: Research Funding; Educational Concepts in Medicine: Honoraria; Novartis: Honoraria. Despotovic:Sanofi: Consultancy; Schell Cooley LLP: Other: Expert witness.

Pediatric immune thrombocytopenia: apoptotic markers may help in predicting the disease course.

In all, 15-30% of pediatric immune thrombocytopenia (ITP) patients will remain chronically thrombocytopenic at 1 year post diagnosis. All attempts to classify patients at diagnosis have proven unsuccessful. We hypothesized that a different pathophysiology is responsible for non-chronic versus chronic pediatric ITP. We aimed to examine differences in the apoptotic markers' presentation at diagnosis between non-chronic and chronic patients. Blood samples were collected from 42 pediatric patients with newly diagnosed ITP prior to initiation of treatment. We incubated patients' sera with control platelets and compared the results among three research groups: healthy controls, chronic ITP, and non-chronic ITP patients. We measured apoptotic markers phosphatidylserine (PS) exposure and mitochondrial inner membrane potential (ΔΨm) by flow cytometry and the level of human apoptotic proteins by Human Apoptosis Array. We found increased platelet PS exposure and decreased ΔΨm in response to all ITP patients' sera compared to control subjects. Human Apoptotic Array revealed an increased expression of five apoptotic proteins: BIM, CD40, IGFBP2, P21, and SMAC, following sera incubation of non-chronic pediatric ITP patients, compared to chronic patients' sera, at diagnosis. Our data contribute to knowledge on apoptosis markers that may aid in predicting the prognosis of children with ITP. The key message of our article is that children with chronic ITP have a different apoptotic profile compared to non-chronic ITP. Addition to existing literature: This is the first study comparing apoptotic markers between children with chronic ITP to non-chronic ITP. Our findings indicate that, in the future, apoptotic markers may help to classify ITP patients into non-chronic versus chronic ones, at diagnosis.

Increased levels of IL-10 and IL-1Ra counterbalance the proinflammatory cytokine pattern in acute pediatric immune thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune disease which leads to accelerated platelet clearance. We investigated the plasma cytokine, chemokine and growth factor signatures and their clinical significance in pediatric ITP patients during acute, chronic and follow-up stages as well as the effects of intravenous immunoglobulin (IVIg) treatment, by using the Multiplex technology. In acute ITP before and/or after IVIg treatment we found significantly increased plasma levels of the pro- (tumour necrosis factor–α (TNF-α), interleukin IL-15) and anti- (IL-1 receptor antagonist (Ra), IL-10 and the growth factor interferon γ-induced protein (IP-10)) inflammatory cytokines, compared to healthy controls. Except for IL1-Ra, these cytokines decreased to normal levels in chronic patients. In contrast, growth-regulated α protein (GRO) and soluble CD40 ligand (sCD40L), known as platelet-derived molecules, were found to be significantly decreased in acute and increased in chronic ITP patients compared to healthy controls. GRO levels positively correlated with the platelet counts in the follow-up and chronic cohort. Monocyte counts showed a significant positive correlation only with IP-10 levels in acute ITP after IVIg treatment and follow-up patients. Expression levels of mRNAs for macrophage inflammatory protein MIP1-β, IL-1Ra and GRO determined in peripheral blood mononuclear cells (PBMCs) were significantly reduced in both acute and chronic ITP compared to controls. Our findings suggest that the different clinical presentation of acute and chronic pediatric ITP and to a lesser extent the IVIg treatment effects are characterized overall by a counterbalanced cytokine, chemokine and growth factor pattern response that might exert a pathogenic role in this disease.

Can Anti-Thyroid Antibodies Influence the Outcome of Primary Chronic Immune Thrombocytopenia in Children?

Immune thrombocytopenia (ITP) is an acquired immune mediated disorder characterized by isolated thrombocytopenia. Pediatric ITP patients can develop autoantibodies such as anti-thyroglobulin (TG) and anti-thyroperoxidase (TPO), even in the absence of clinical signs of autoimmune disease. The purpose of this article is to provide a review about: 1) the prevalence of positivity of anti-thyroid antibodies (TPO and TG) in pediatric patients with chronic ITP; 2) the role of autoimmune thyroiditis on the outcome of chronic ITP. The authors individually completed a review of the literature for this article. Retrospective and prospective clinical studies with pediatric cohorts were considered. From the analysis of data, we found 4 papers which included studies only on pediatric population, and which corresponded to selected criteria. Pediatric ITP patients have been shown to have a statistically significant prevalence of anti-thyroid antibodies over healthy controls (11.6-36% versus 1.2-1.3%). No correlation has been found between the platelet count and the prevalence of positive anti-thyroid antibodies at any time of the follow up. The results of our bibliographic research demonstrated that: a) pediatric patients with chronic ITP tend to have a statistically significant prevalence of anti-thyroid antibodies positivity respect to general pediatric population; b) there are no clear data about the role of autoimmune thyroiditis as prognostic factor for chronic course of ITP in pediatric age.

Genetic variants in toll-like receptor 4 are associated with lack of steroid-responsiveness in pediatric ITP patients.

Although the most common front-line therapies for immune thrombocytopenia (ITP) have been in use for decades, it is still not possible to predict an individual patient's clinical course and response to therapy. Patients are managed with a trial-and-error approach and often suffer side effects of therapies which could have been avoided if response prediction were possible. Corticosteroids are the most frequently used upfront therapy for adults and children with ITP. Our group performed whole exome sequencing on a cohort of pediatric ITP patients, and identified two missense single nucleotide variants (SNV) in Toll-like receptor 4 (TLR4). These coding variants in TLR4 had an increased frequency in Caucasian patients with poor response to upfront steroid therapy. Both TLR4 (D299G; rs4986790) and TLR4 (T399I; rs4986791) had a minor allele frequency (MAF) of 20.7% in those patients unresponsive to steroids, but were present at lower allele frequencies of 2.3% and 3.4% in responders respectively (P < .001). These findings were consistent with the trend identified in an independent cohort of pediatric ITP patients treated with corticosteroids who underwent direct genotyping for both SNVs. This study identified two candidate genetic variants in two unique cohorts of ITP patients which may contribute to steroid response and have prognostic implications for treatment response in ITP.

Eltrombopag for the treatment of primary immune thrombocytopenia in 23 pediatric patients

目的评估艾曲泊帕治疗儿童原发免疫性血小板减少症（ITP）的疗效和不良反应。方法回顾性分析2015年5月至2019年3月接受艾曲泊帕治疗的23例儿童ITP患者临床资料。结果23例患者中，男11例，女12例，中位年龄11（2~17）岁。新诊断ITP 4例（17.39%），持续性ITP 8例（34.78%），慢性ITP 11例（47.83%）。艾曲泊帕中位起始剂量为25.0（12.5~50.0）mg/d。基线中位血小板计数为14（2~82）×109/L，治疗后第2周（23例）、第4周（23例）、第3个月（16例）、第6个月（11例）的中位血小板计数分别为40（4~170）×109/L、20（4~130）×109/L、60（4~110）×109/L、70（18~160）×109/L，均高于基线水平（z=-3.440，P=0.001；z=-1.964，P=0.049；z=-4.339，P<0.001；z=-5.794，P<0.001）。7例（30.43%）患者的起效时间≤7 d，10例（43.48%）患者的起效时间≤2周，总有效率为60.87%（14/23）。<6岁（6例）、6~12岁（10例）、13~17岁（7例）组的总有效率分别为33.33%（2/6）、60.00%（6/10）、85.71%（6/7），组间比较差异均无统计学意义（P>0.05）。23例患者基线WHO出血评分0、1、2级分别有4、12、7例，治疗后分别为13、7、3例，出血症状得到明显改善（χ2=7.558，P=0.006）。治疗过程中发生转氨酶、胆红素增高各4例，轻度恶心、呕吐及头晕各1例，对治疗均未造成影响。结论艾曲泊帕作为二线用药治疗儿童ITP疗效及耐受性均较好。

Immunoglobulin Levels As Predictors of the Development of Chronic Disease in Pediatric Immune Thrombocytopenia

Background: Immune thrombocytopenia (ITP) is the most common acquired bleeding disorder in children. Although ~75% of these patients will go on to have spontaneous resolution of disease, up to 25% will develop chronic ITP, with significant and prolonged bleeding symptomatology and impaired quality of life. At this time, there is no definitive method to predict the development of chronic disease at the time of ITP diagnosis. Aims: We aim to identify clinical biomarkers predictive of the development of chronic ITP at the time of diagnosis among pediatric ITP patients. Methods: The clinical records of 280 pediatric ITP patients enrolled in a biological banking study at a large pediatric tertiary care referral center from July 1, 2015 to July 1, 2019 were reviewed in accordance with IRB-approved protocols. ITP diagnosis and chronicity of disease (vs. spontaneous resolution within 1 year of diagnosis) was confirmed by a pediatric hematologist, as defined by current international expert committee standards (Neunert et al, Blood, 2011;117(16):4190-207; Provan et al, Blood, 2010;115(2):168-186). Patients with non-classical ITP were excluded (1 child with drug-induced ITP in the setting of acyclovir therapy, and 1 neonate with passive ITP in the setting of maternal lupus); and patients who were lost to follow-up or had ongoing disease of &amp;lt;1 year duration were subsequently excluded. Patient characteristics including age, gender, ethnicity, presence of concurrent autoimmune disease, and time to resolution were collected. Pertinent biomarkers including immunoglobulin levels (IgG, IgA, and IgM), anti-nuclear antibody (ANA), C-reactive protein (CRP), and immature platelet fraction (IPF) which were obtained at the time of diagnosis were documented, if if obtained prior to the administration of any ITP-directed therapy, and within 2 weeks of diagnosis. Chi-squared test or Fisher's exact test was utilized to compare nonparametric categorical data. Mann-Whitney U test was used to compare nonparametric continuous data. A multivariate backwards logistic regression model was conducted to determine independent associations with the development of chronic ITP. Statistical analyses were performed using SPSS Statistics 26 (IBM, Armonk, New York). A Bonferroni correction was applied to correct for multiple comparisons. A p value &amp;lt; 0.05 was defined as statistically significant. Results: We identified 251 pediatric ITP patients with sufficient length of follow-up to define acute (&amp;lt;1 year) vs. chronic (&amp;gt;1 year) disease within our 4-year study period. This included 132 patients with acute ITP (53%) and 119 patients who went on to develop chronic ITP (47%). Mean age of diagnosis among those with acute ITP was 5.5 years, while mean age of diagnosis among those with chronic ITP was 7.7 years. Within the entire cohort, 126 (50%) were male, and 124 (49%) were of Hispanic ethnicity. Fifty-eight had ITP attributable to systemic autoimmune disease - 17% within the Acute ITP group, and 30% within the Chronic ITP group. Among all patients (n=251), 188 with evaluable biomarkers (immunoglobulin levels, ANA, CRP, or IPF) at the time of diagnosis were identified. These included 174 patients with Ig levels at diagnosis, 43 patients with ANA titers at diagnosis, 25 patients with CRP levels at diagnosis, and 78 patients with IPF at diagnosis. By univariate analysis, we found that abnormalities in immunoglobulin levels at diagnosis were significantly associated with the development of chronic ITP. Low IgG levels (p = 0.015) were more prevalent in chronic (10.3%) vs. acute ITP (1.9%). High IgG levels (p = 0.015) were more prevalent in chronic (6.7%) vs. acute ITP (1.9%). High IgM levels (p = 0.03) were more prevalent in chronic (26.5%) vs. acute ITP (13.3%). Of note, the presence of Evans syndrome (p = 0.0005) and other systemic autoimmune disease (p = 0.011) were also significantly associated with the development of chronic ITP. Subsequent multivariate analysis identified low IgG level at diagnosis to be independently predictive of chronic ITP (p = 0.043, with an odds ratio of 5.7). Conclusion: Although further study is needed within a larger international pediatric ITP cohort, the findings from this institutional study indicate that biomarkers obtained in routine clinical care at the time of ITP diagnosis, specifically immunoglobulin levels, can be utilized to help predict development of chronic disease among pediatric ITP patients. Disclosures Despotovic: Amgen: Research Funding; Dova: Honoraria; Novartis: Research Funding.

Next Generation Sequencing-Based Characterization of T Cell Receptor Repertoire of Patients with Immune Thrombocytopenia

Background: Immune thrombocytopenia (ITP) is an acquired autoimmune disease characterized by increased platelet destruction and impaired platelet production. Abnormal T cell immunity plays a critical role in the pathogenesis of ITP. Analysis of T cell receptor (TCR) repertoire can identify specific T cell population proliferations in response to antigenic stimulation. No systematic next-generation sequencing (NGS)-based TCR repertoire characterization of pediatric ITP patients has been reported to date. We herein report our comprehensive analysis of TCR-β repertoires of peripheral blood samples from a cohort of pediatric patients with ITP. Method: Pediatric patients from Lucile Packard Children's Hospital (Stanford Children's Health) with newly diagnosed ITP (n=11), chronic ITP (n=8), resolved from ITP (n=3), and healthy individuals (n=4) were consented to be included in the study. Total RNA was extracted from peripheral blood samples of the study subjects and reverse transcribed into cDNA. Completely rearranged TRB gene locus was amplified and used for library preparation, which were subsequently sequenced on the Illumina MiSeq platform. The sequencing reads were analyzed with IMGT (ImMunoGeneTics)/HighV-QUEST tools. Further analysis was performed to evaluate TRB repertoire diversity, V-J gene segment usage, clonotype sharing among patient samples, clonality pattern, predominant clonotype frequency changes in different disease state, and sequence similarity among expanded clonotypes. Result: The normalized clonotype counts and the calculated TRB repertoire diversity indices (Shannon and Simpson indices) did not reveal significant difference among newly diagnosed ITP, chronic ITP and healthy control groups. In terms of the V-J gene segment usage among the top 200 clonotypes (as defined by CDR3 amino acid sequences), newly diagnosed ITP group used TRBV12-3 significantly more frequently, and TRBV6-4 significantly less frequently, compared to the healthy control group. The means of overlap coefficient, reflective of TRB clonotype sharing, for newly diagnosed ITP, chronic ITP and healthy control groups are 0.0045 (range 0.005-0.008), 0.0057 (range 0-0.016), 0.0041(range 0.004-0.005), respectively. Chronic ITP patients had significantly more overlap in TRB clonotypes than healthy donors. No common or "public" clonotypes shared within each group were identified. The nucleotide sequence and CDR3 amino acid sequence of dominant TRB clonotypes in ITP patients were compared, and the percent similarity ranged from 30.18% to 88.26% for the former, and from 16.9% to 36.04% for the latter. Conclusion: We performed comprehensive analysis of TCR repertoire of peripheral blood samples from pediatric ITP patients by next-generation sequencing. TCR repertoire diversity at different disease states was analyzed. Differences in V-J gene segment usage and clonotype sharing among patients were observed. These findings provide unique insights into the potential pathophysiology of T cell immunity in patients with ITP. Disclosures No relevant conflicts of interest to declare.