Pediatric Immune Thrombocytopenia 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.

The first national pediatric immune thrombocytopenia registry in Iran: research protocol and preliminary study results

BackgroundDisease registries are comprehensive databases that record detailed information on patients diagnosed with specific conditions, providing valuable insights into their diagnosis, treatment, and outcomes. This study aims to describe the pilot phase of the national pediatric Immune Thrombocytopenia(ITP) registry (NPITP) in Iran, serving as the inaugural interpretive report.MethodsThis patient-centered software system was implemented as a national program across multiple pediatric centers in Iran. Several focus groups were conducted to establish a minimum data set (MDS) comprising six main classes, 14 sub-classes, and 187 data elements. Following expert consensus on the final data set, a web-based software tool was developed by the dedicated IT team, accessible online and offline via https://disreg.sbmu.ac.ir/q/ITP.html. The registry included children aged between two months and 18 years with a platelet count below 100 × 109/L, based on predefined inclusion criteria.ResultsWithin a four-month period, a total of 60 ITP patients were registered, including 41 (68.3%) newly diagnosed cases, 68 (13.6%) persistent cases, and 14 (23.3%) with chronic ITP. The mean age of the registered patients was 55.93 ± 9.72 months. The most frequently observed bleeding symptoms were petechiae (68.3%), purpura (51.6%), and ecchymosis (13.3%). Among the newly diagnosed patients, 20 (33.3%) received intravenous immunoglobulin (IVIG), 17 (28.3%) were treated with prednisolone, and 17 (28.3%) received combined IVIG and steroid therapy. Of all patients, 40 (66.7%) demonstrated a complete response to treatment, while 16 (26.7%) exhibited a partial response. Four patients (6.7%) remained unresponsive to therapy. Treatment-related complications, such as Cushing’s syndrome, edema, weight gain, hirsutism, and mood disorders, were reported in 10 patients (16.6%). However, the majority of patients (81.7%) did not experience therapy-related complications.ConclusionThe pilot phase of the NPITP registry successfully implemented a web-based software tool for data collection, aiming to enhance the quality of care, facilitate clinical research, and support health service planning in the future.

Diagnostic yield of bone marrow aspiration in paediatric primary immune thrombocytopenia: impact of evolution and adherence to medical guidelines over the last 25years.

BMA at presentation did not significantly alter the diagnosis in our cohort of patients with an initial suspicion of ITP, although the procedure was decisive in diagnosing 2 cases of acquired aplastic anaemia during the subsequent course of the disease. Regarding the number of aspirations performed, our findings show that increased physician compliance with current guidelines reduced the rate of unnecessary BMAs. • BMA is a supplementary test for the diagnosis of ITP. • The usefulness of this invasive diagnostic procedure is not clearly stated in current guidelines. • Adjustments to scientific guidelines have led to a reduction in the number of BMAs performed on our patients with suspected ITP in the last 27years. • While the risks and benefits of BMA at the time of diagnosis are unclear in patients with suspected ITP, the procedure does not contribute significant information to support the diagnosis.

FOXO1 Single-Nucleotide Polymorphisms Are Associated with Bleeding Severity and Sensitivity of Glucocorticoid Treatment of Pediatric Immune Thrombocytopenia.

Immune thrombocytopenia (ITP) is an autoimmune-mediated hemorrhagic disease. Emerging evidence indicates that FOXO1 SNPs are related to the immune dysregulation of several autoimmune diseases suggesting that FOXO1 may be involved in inflammation and pathologic activities in patients with ITP. This study aimed to evaluate whether FOXO1 gene single-nucleotide polymorphisms (SNPs) are associated with susceptibility to ITP and clinical priorities of concern include bleeding severity and sensitivity of glucocorticoid treatment. This study recruited 327 newly diagnosed ITP and 220 healthy controls. Four SNPs (rs17446593, rs17446614, rs2721068, and rs2721068) of the FOXO1 gene were detected using the Sequenom MassArray system. Bleeding severity were classified into the mild and severe groups based on the bleeding scores. ITP patients were classified as sensitive and insensitive to glucocorticoid treatment according to the practice guideline for ITP (2019 version). The frequencies of the four SNPs did not show any significant differences between the ITP and healthy control groups. Patients with AA genotype at rs17446593 (p = 0.009) and GG genotype at rs17446614 (p = 0.009) suffered more severe bleeding than patients without them. Carriers of haplotype Grs17446593Ars17446614Crs2721068Trs2755213 were protective to severe bleeding (p = 0.002). The AA genotype at rs17446593 was significantly higher in ITP patients sensitive to glucocorticoid treatment than in those insensitive to glucocorticoid treatment (p = 0.03). Haplotype Grs17446593Grs17446614Trs2721068Trs2755213 increases the risk of glucocorticoid resistance (p = 0.007). Although FOXO1 gene polymorphisms were not associated with susceptibility to ITP, the AA genotype at rs17446593 and GG genotype at rs17446614 were associated with bleeding severity. Haplotype GACT have a protective effect against severe bleeding. Patients with AA genotype at rs17446593 may tend to have good responds to glucocorticoid treatment. However, the FOXO1 gene haplotype GGTT increases the risk of glucocorticoid-resistant. Trial registration: ChiCTR1900022419.

Pediatric refractory chronic immune thrombocytopenia: Identification, patients' characteristics, and outcome.

Refractory chronic immune thrombocytopenia (r-cITP) is one of the most challenging situations in chronic immune thrombocytopenia (cITP). Pediatric r-cITP is inconsistently defined in literature, contributing to the scarcity of data. Moreover, no evidence is available to guide the choice of treatment. We compared seven definitions of r-cITP including five pediatric definitions in 886 patients with cITP (median [min-max] follow-up 5.3 [1.0-29.3] years). The pediatric definitions identified overlapping groups of various sizes (4%-20%) but with similar characteristics (higher proportion of immunopathological manifestations [IM] and systemic lupus erythematosus [SLE]), suggesting that they adequately captured the population of interest. Based on the 79 patients with r-cITP (median follow-up 3.1 [0-18.2] years) according to the CEREVANCE definition (≥3 second-line treatments), we showed that r-cITP occurred at a rate of 1.15% new patients per year and did not plateau over time. In multivariate analysis, older age was associated with r-cITP. One patient (1%) experienced two grade five bleeding events after meeting r-cITP criteria and while not receiving second-line treatment. The cumulative incidence of continuous complete remission (CCR) at 2 years after r-cITP diagnosis was 9%. In this analysis, splenectomy was associated with a higher cumulative incidence of CCR (hazard ratio: 5.43, 95% confidence interval: 1.48-19.84, p = 7.8 × 10-4). In sum, children with cITP may be diagnosed with r-cITP at any time point of the follow-up and are at increased risk of IM and SLE. Second-line treatments seem to be effective for preventing grade 5 bleeding. Splenectomy may be considered to achieve CCR.

Excellent response to treatment with hydroxychloroquine in pediatric patients with SLE-related immune thrombocytopenia.

Pediatric immune thrombocytopenia (ITP) may precede systemic autoimmune disorders. In adolescent patients with ITP, routine screening for systemic lupus erythematosus (SLE) may be performed by testing for antinuclear antibody (ANA) titer. Hydroxychloroquine (HCQ) is a safe and effective immunomodulatory drug in patients with SLE but rarely used in ITP. We analyzed the platelet count response and safety of HCQ in treating pediatric patients with SLE-related ITP. A retrospective study including pediatric patients with ITP and definite or incomplete SLE, who were treated with HCQ during 2010-2021. SLE was defined by ANA titer≥1:160 as measured by immunofluorescence and ≥10 points according to the 2019 EULAR/ACR 2019 classification criteria, while patients with incomplete SLE achieved a score<10. Complete response (CR) of the platelet count was defined as platelet count>100 × 109/L; partial response (PR) as platelet count 30-100 × 109/L and exceeding≥twice baseline counts. Of the 17 patients included (median age 15.5 years; IQR 3.6), 15 (88.2%) were female, 13 had definite SLE, and four had incomplete SLE. HCQ was initiated at a median of 17 months after ITP diagnosis with a median platelet count of 38 × 109/L (IQR 28). At 8weeks, 8 (47.1%) patients responded, including 6 (35.3%) achieving CR. After one year, the overall response was 82.4%, with the remaining patients having stable platelet counts requiring no additional ITP therapy. The response was maintained at a median follow-up of 42 months. No adverse effects to HCQ were noted. Pediatric patients with SLE-related ITP may benefit from treatment with HCQ.

Spotlight on eltrombopag concentration in pediatric immune thrombocytopenia: A single-center observational study in China.

Eltrombopag has been recommended for pediatric immune thrombocytopenia (ITP). Response and adverse drug reactions (ADRs) varied widely between individuals, even at the same dose of eltrombopag. The appropriate eltrombopag concentration in ITP has not been reported. This study aims to explore the appropriate eltrombopag concentration in pediatric ITP. This was a single-center, prospective cohort study. Children diagnosed with refractory persistent/chronic ITP and platelet count < 30×109/L were treated with eltrombopag and followed up for at least 2 months. Concentration was detected by high-performance liquid chromatography-mass spectrometry at least 2 weeks after eltrombopag. The clinical characteristics-concentration, concentration-response, and concentration-ADRs were analyzed. A total of 30 patients were enrolled, comprising 13 males and 17 females, with a median age of 72 (45‒94) months. The median dose and concentration were 1.39 (1.09‒1.56) mg/kg and 2.70 (2.25‒4.13) mg/L, respectively. Of the enrolled patients, 14 responded to treatment, whereas 16 did not. Additionally, five experienced adverse drug reactions. No linear correlation was observed between eltrombopag concentration and clinical characteristics. The concentration was lower in the response group than in the nonresponse group, but there was no significant difference (t = 0.755, P = 0.457). Patients who experienced ADRs had a higher concentration than those without ADRs (t = 2.538, P = 0.017). The area under the receiver operating characteristic curve of ADRs was 0.78 (95% confidence interval: 0.56‒1.00). Youden's index identified the cutoff point as 4.33 mg/L, with a sensitivity of 88% and a specificity of 60%. Logistic regression analysis demonstrated that a higher platelet count before eltrombopag predicted a favorable response. Eltrombopag proves efficacious and well-tolerated for treating pediatric ITP. However, prolonged and high-dose administration may increase the likelihood of ADRs. Thus, examining the appropriate eltrombopag concentration assists in directing individualized management of pediatric ITP.

Dapsone for paediatric chronic immune thrombocytopenia: Shortreport from a tertiary centre in South India.

Immune thrombocytopenia (ITP) resolves in most children within 3-12 months of diagnosis. Chronic ITP affects 10%-20% of patients, some of whom require treatment. Several second-line agents are efficacious in this group of patients. This paper describes our experience of using dapsone as a single second-line agent in children with chronic ITP. One hundred and three children with chronic ITP were seen at our centre from January 2012 to December 2016. Forty-five children met the inclusion criteria and received dapsone; 17 (37.8%) were boys; and 28 (62.2%) were girls. Early response to dapsone was seen in 37.8% of patients. The median duration of long-term follow-up was 50 months, and at least a partial response was seen in 64.4% of the patients. Dapsone offers good initial response rates and sustained remission in paediatric chronic ITP, comparable to other therapeutic agents available.

Machine learning models developed and internally validated for predicting chronicity in pediatric immune thrombocytopenia

BackgroundPrimary immune thrombocytopenia (ITP) in children is typically self-limiting; however, 20% to 30% of patients may experience prolonged thrombocytopenia lasting over a year. The challenge is predicting chronicity to ensure personalized treatment approaches. ObjectivesTo address this issue, we developed and internally validated 4 machine learning (ML) models using demographic and immunologic characteristics to predict the likelihood of chronicity. MethodsThe present study was conducted at Beijing Children’s Hospital from June 2018 to December 2021, aiming to develop predictive models for determining the chronicity of pediatric ITP. Four ML models, based on a logistic regression classifier, random forest classifier, eXtreme Gradient Boosting (XGBoost), and support vector machine, were employed. These models used a set of 16 variables, including 14 immunologic and 2 demographic predictors. The performance evaluation criteria included prediction accuracy, precision, recall, F1 score, and area under the receiver operating characteristic curve (AUROC). ResultsData were collected from 662 patients who were randomly assigned to either a training dataset or a testing dataset using a random number generator. Among them, 26.5% had chronic disease. All models performed well, with AUROC values ranging from 0.81 to 0.84, and XGBoost was selected for its highest AUROC score and interpretability in constructing the predictive model. Age, T helper 17, T helper 17-to-regulatory T cell ratio, T helper 1, and double-negative T cells were identified as significant predictors by the XGBoost algorithm. ConclusionWe developed a precise predictive model for chronicity in pediatric ITP using ML during the initial phase. The XGBoost model achieved high predictive accuracy by using individual patient clinical parameters and demonstrated commendable interpretability.

Predicting the efficacy of glucocorticoids in pediatric primary immune thrombocytopenia using plasma proteomics.

Primary immune thrombocytopenia (ITP) is the most common acquired autoimmune bleeding disorder among children. While glucocorticoids are the primary first-line treatment for ITP treatment, they prove ineffective in certain patients. The challenge of identifying biomarkers capable of early prediction regarding the response to glucocorticoid therapy in ITP persists. This study aimed to identify ideal biomarkers for predicting glucocorticoid efficacy in patients with ITP using plasma proteomics. A four-dimensional data-independent acquisition approach was performed to determine the differentially expressed proteins in plasma samples collected from glucocorticoid-sensitive (GCS) (n=18) and glucocorticoid-resistant (GCR) (n=17) children with ITP treated with prednisone. The significantly differentially expressed proteins were selected for enzyme-linked immunosorbent assay validation in a cohort conprising 65 samples(30 healthy controls, 18 GCS and 17 GCR children with ITP). Receiver operating characteristics curves, calibration curves, and clinical decision curve analysis were used to determine the diagnostic efficacy of this method. 47 differentially expressed proteins (36 up-regulated and 11 down-regulated) were identified in the GCR group compared with the GCS group. The significantly differentially expressed proteins myosin heavy chain 9 (MYH9) and fetuin B (FETUB) were selected for enzyme-linked immunosorbent assay validation. The validation results were consistent with the proteomics analyses. Compared with the GCS group, the GCR group exhibited a significantly reduced the plasma concentration of MYH9 and elevated the plasma concentration of FETUB. Furthermore, the receiver operating characteristics curves, calibration curves, and clinical decision curve analysis demonstrated good diagnostic efficacy of these validated biomarkers. This study contributes to the establishment of objective biological indicators for precision therapy in children with ITP. More importantly, the proteins MYH9 and FETUB hold potential as a foundation for making informed decisions regarding alternative treatments for drugresistant patients, thereby preventing treatment delays.

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 &amp;lt;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&amp;lt;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 &amp;lt; 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 &amp;lt;5 × 10 -8 and suggestive of genome-wide significance, P &amp;lt;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.

Immunoglobulins As a Predictor of Chronicity in Pediatric Immune Thrombocytopenia

Introduction: Immune thrombocytopenia (ITP) is the most common acquired bleeding disorder in children, but predictors of chronicity at the time of diagnosis remain largely unknown. Small studies have previously indicated predictive value of baseline immunoglobulin levels, but without definitive clinically applicable conclusions. We aim to further investigate the utility of immunoglobulin levels obtained at the time of diagnosis in predicting the development of chronic ITP (cITP) in children. Methods: We completed a retrospective review of patients aged 6 months - 21 years diagnosed with ITP at tertiary referral centers from 2015 - 2022 in accordance with IRB-approved protocols. Patients with immunoglobulin levels obtained within 3 months of ITP diagnosis and prior to any treatment were included in the study. cITP was defined as ITP duration &amp;gt;12 months. ITP resolution was defined as achieving a platelet count &amp;gt; 150 x 10 9/L on 2 occasions, or on 1 occasion in the presence of normalized MPV, absent of therapy. Patients who were lost to follow-up or had ongoing disease &amp;lt;1 year duration were excluded. Immunoglobulins were recorded by continuous variable as well as by age-related reference values. The two groups (“spontaneously resolved” and “cITP”) were compared using Pearson's Chi-squared test for nonparametric categorical variables, Fisher's exact test for parametric categorical variables, and Wilcoxon rank sum test for nonparametric categorical variables. A multivariable logistic regression model was built to determine independent associations between immunoglobulin levels and the development of cITP after adjusting for age. R (version 4.2.1) was used for analysis. A p-value &amp;lt;0.05 was considered to be statistically significant. Results: We identified 497 patients for inclusion in the study. Among these, 336 patients (67.6%) had ITP resolution prior to 12 months, while 161 patients (32.4%) developed cITP. Within the full cohort, 257 (51.7%) were male and 218 (43.9%) were Hispanic. Median age of diagnosis was 4.1 years among those with resolution, and 9.4 years among those with cITP. Patients were more likely to have secondary ITP in the cITP group vs the resolved group (37 patients [23.0%] vs 10 patients [6.2%]). Low and high IgG levels were more prevalent in cITP (5% vs 3% and 16% vs 5.7%, respectively). The median IgG level was higher in the cITP group (991 vs 838 mg/dL). Low IgA levels were more prevalent in cITP (7% vs 2.4%) and high IgA levels more prevalent in spontaneously resolving ITP (7.8% vs. 5.7%), although the median IgA level was higher in cITP (116 vs 88 mg/dL), likely attributable to older age in the cITP group. Both low and high IgM levels were more prevalent in cITP (8.9% vs 6.6% and 20% vs 16%, respectively), with the median IgM level being similar in both groups (89 vs 85 mg/dL). The age-adjusted multivariable logistic regression analysis demonstrated independent predictive value of IgG, IgA, and IgM for development of cITP (See Table, Figure). Each 100 mg/dL increase in IgG level was associated with a 17% increase in the odds of developing cITP (p=0.001); while each 100 mg/dL increase in IgA or IgM level was associated with decreased odds of developing cITP (37% [p=0.025] and 56% [p&amp;lt;0.001] decrease, respectively). Additionally, every 1-year increase in age was associated with a 16% increase in the odds of developing cITP (p&amp;lt;0.001). We also found that patients with a known secondary cause of ITP at the time of diagnosis had increased likelihood of developing cITP (p&amp;lt;0.001). Performance scores for the predictive model include a C-index of 0.72 and Nagelkerke R 2 of 0.21. Conclusions: We utilized pre-treatment immunoglobulin values obtained within 3 months of diagnosis from 497 children with ITP to investigate the predictive value of immunoglobulin measurements for the development of cITP. We found that IgG, IgA, and IgM values are predictive of cITP development after accounting for age. Increasing age was also associated with increased risk of cITP. In future work, we plan to evaluate the value of additional variables for predicting the development of cITP and then validate the predictions in an external cohort. Better defining the predictive value of clinical data available at the time of ITP diagnosis will allow hematologists to provide improved prognostication and individualized management much earlier in a patient's disease course, ultimately improving the quality of care for children with ITP.

CD72 gene expression in children suffering from primary immune thrombocytopenia and its correlation with the disease activity

BackgroundImmune thrombocytopenia is a condition in which the immune system attacks platelets, leading to a low platelet count. CD72 is a co-receptor found on B cells during all developmental stages except those of plasma cells. Activation of CD72 promotes B cell growth and differentiation. We aimed to investigate the expression and role of CD72 in pediatric immune thrombocytopenia, as well as its correlation with disease pathogenesis and activity. The study involved 60 children diagnosed with ITP and 40 healthy controls, who were matched accordingly. All participants underwent a thorough medical history assessment and clinical examination. The RT-PCR method was utilized to determine the level of CD72 expression.ResultsCD72 expression level was considerably higher in cases than in controls (P-value < 0.001). Within the cases group, we detected a significant inverse correlation between CD72 expression and platelet count (P-value < 0.03). Also, there was a notable rise in CD72 expression among those experiencing active ITP compared to those in remission. Moreover, autoantibody-positive patients exhibited greater levels of CD72 expression than their autoantibody-negative counterparts did. While there was no discernible association detected between CD72 expression and the duration of the disease.ConclusionCD72 expression is linked to the pathogenesis of ITP. Also, expression elevation is associated with disease activity. In addition, it is not related to disease chronicity. CD72 can be considered a new approach to the diagnosis, treatment, and follow-up of pediatric ITP.

Real World Practices of Thrombopoietin Receptor Agonist Use and Discontinuation in Pediatric Patients with Immune Thrombocytopenia (ITP): A Single Center Retrospective Review

Introduction Thrombopoietin Receptor Agonists (TPO-RAs) are becoming widely used as second-line treatment in patients with immune thrombocytopenia (ITP). These can be weaned/discontinued in adults. There is a paucity of literature on weaning and discontinuation practices in pediatric ITP. Methods We performed a retrospective review of pediatric patients aged 0-18 years with ITP treated with TPO-RAs at our institution over an eight-year period (2015-2022). Weaning and discontinuation practices were compared between patients based on timing of TPO-RA initiation: &amp;lt;3 months from diagnosis (group A), ≥3 to &amp;lt;12 months from diagnosis (group B), &amp;lt;12 months from diagnosis (group AB) or ≥12 months from diagnosis (group C). Results There were 11, 12 and 32 patients in group A, B, and C respectively (table 1). As of last follow up, 10 patients successfully weaned and discontinued their TPO-RA. Eighteen patients were weaning their TPO-RA monotherapy and 15 continued a TPO-RA at maximal dose or required the addition of another agent, such as an immunosuppressant, to permit TPO-RA weaning. Five patients discontinued their TPO-RA due to poor response. Seven patients had stopped the TPO-RA due to an alternate reason (family preference, side effects, etc.). There was no difference in any of these outcomes based on timing of TPO-RA initiation. In patients whose platelet count responded to TPO-RAs, the dose was weaned at the provider's discretion. The dose was generally not weaned for a platelet count &amp;lt;50k. Among only patients in which the TPO-RA monotherapy was weaned, patients in group AB had a shorter duration of TPO-RA treatment than patients in group C (IQR 12.1-48.9 months vs 37.5-88.0 months; p=0.019). While not statistically significant, after the start of the TPO-RA dose weaning, patients in group A weaned their TPO-RA at a faster rate (IQR 4.7-20.5% of maximal dose per month) compared to patients in groups B and C (IQR 1.8-5.1% of maximal dose per month and 1.5-5.5% of maximal dose per month). The 10 patients who fully weaned their TPO-RA had a shorter duration of TPO-RA use compared to the 18 patients who partially weaned their TPO-RA monotherapy (IQR 11.5-38.6 months vs 27.6-82.1 months; p=0.018). Once the wean of TPO-RA dose was started, patients who fully weaned their TPO-RA did so at a faster rate than patients who partially weaned (IQR 5.6-29.6% of maximal dose per month vs 1.0-3.4% of maximal dose per month; p=0.017; figure 1). Seven patients who fully weaned their TPO-RA had follow up CBCs between one and three months after discontinuation. Of these, five patients had platelet counts &amp;gt;100k, while the other two had platelet counts &amp;gt;40k that continued to rise to &amp;gt;80k within a year of discontinuation without further treatment. Of the remaining three patients, two had CBCs more than three months post TPO-RA discontinuation with platelet counts &amp;gt;100k without additional treatment and one had no follow up CBC after TPO-RA discontinuation. Two patients with follow-up had transient ITP exacerbations with platelet counts &amp;lt;10k at 14 and 31 months after TPO-RA discontinuation that were treated with anti-D/steroids and IVIG respectively with subsequent sustained improvement in platelet counts that did not require any further intervention. There was no difference in the number of rescue medications (IVIG, anti-D, steroids) required between patient groups based on timing of TPO-RA initiation or type of agent used. Patients who were treated with both romiplostim and eltrombopag required adjunctive therapies (such as immunosuppressants) more than patients treated with either agent alone (p=0.022). Conclusion TPO-RAs were weaned and successfully discontinued in 10 of 55 (18.2%) pediatric patients with ITP in our small cohort with a low rate of subsequent ITP exacerbation. There was no difference in TPO-RA discontinuation rate in patients with a good platelet response based on timing of TPO-RA initiation. Patients who started a TPO-RA within 12 months of their ITP diagnosis had a shorter duration of TPO-RA use than patients who started a TPO-RA more than 12 months after diagnosis. Patients who started a TPO-RA within three months of diagnosis were able to wean their TPO-RA dose at a faster rate than patients who started a TPO-RA more than three months after diagnosis. TPO-RA dose was weaned at a faster rate in patients who fully weaned their TPO-RA compared to patients who were partially weaned. This data should be validated in a larger study.

A Phase 3 Study of Eltrombopag Vs. Standard First-Line Management for Newly Diagnosed Immune Thrombocytopenia in Children: Trial in Progress Update

Background: Immune thrombocytopenia (ITP) causes low platelet counts, variable bleeding symptoms, and reductions in health-related quality of life (HRQoL). Despite this, novel therapies for newly diagnosed ITP have not been introduced in over 30 years. Eltrombopag, a thrombopoietin receptor agonist (TPO-RA), was FDA approved for children with chronic ITP in 2015. The use of eltrombopag for adults with newly diagnosed ITP has been described in two small single-center trials (Tripathi et al, Int J Hematol, 2014; Gόmez-Almaguer et al, Blood, 2014), and pediatric hematologists do use TPO-RAs off-label in some cases of newly diagnosed ITP (Neunert et al, Pediatr Blood Cancer, 2016). TPO-RAs may be an efficacious and more durable first-line therapy for children with newly diagnosed ITP who require treatment. This abstract provides a 4-year interval update on the Pediatric ITP Newly diagnosed patients Eltrombopag vs Standard therapy (PINES) trial in progress. Study Design and Methods: The PINES trial, NCT03939637, is an investigator-initiated prospective, open label, randomized, multi-center trial sponsored by the ITP Consortium of North America (ICON) and funded by Novartis. The primary objective is to determine if the proportion of patients with a platelet response, defined as ≥3 of 4 platelet counts &amp;gt;50 x10 9/L during weeks 6-12 without rescue treatment, is significantly greater in patients with newly diagnosed ITP treated with eltrombopag compared to those treated with standard first-line therapy. Patients (n=162) from 30 ICON centers (Figure) are randomized 2:1, stratified by age and treatment status, to receive the experimental treatment, eltrombopag, or investigator's choice of 3 standard first-line therapies: prednisone, intravenous immune globulin or anti-D globulin at standardized doses. Eligible patients are ages 1 to &amp;lt;18 with primary ITP, within 3 months of diagnosis, with platelet count &amp;lt;30 x10 9/L who require pharmacologic treatment from the perspective of the treating clinician. Baseline treatment status is 1) upfront treatment, or patients within 10 days of ITP diagnosis with no prior treatment, and 2) treatment failure, or patients previously managed with observation or a first-line standard agent. Patients are ineligible if they can be observed without medication or have severe bleeding. A one-sided z-test, at alpha=0.025, will be used to compare the proportion of patients who have a platelet response between the two treatment arms. All randomized patients will be analyzed in the intention-to-treat analysis. Secondary objectives include treatment arm comparison of bleeding scores (WHO Bleeding Scale and Modified Buchanan Score), changes in HRQoL (measured by the Kids ITP Tool, Hockenberry Fatigue Scale, PROMIS, and Global Change Scale), and changes in percentage of CD4 +25 +Foxp3 + regulatory T (Treg) cells. Due to challenges related to recruitment and the logistics and safety of obtaining frequent assessments during the COVID-19 pandemic, the primary endpoint was re-defined in 2021 to what is considered a clinically equivalent definition of response, from ≥6 of 8 weekly to ≥3 of 4 biweekly platelet counts &amp;gt;50 x10 9/L during weeks 6-12. Baseline Characteristics: Since first site activation in 2019, 100 patients have been enrolled (Table). Subjects include 42 patients aged 1-&amp;lt;6 years, 34 patients aged 6-&amp;lt;12 years, and 24 patients aged 12-&amp;lt;18 years. Thirty-six patients received upfront treatment and 64 patients had treatment failure prior to enrollment. Median baseline platelet count at enrollment was 5 x10 9/L (range 1 - 28 x10 9/L). Median WHO Bleeding Scale at enrollment was 1 (range 0 - 3) and median modified Buchanan Overall Score was 3 (range 0 - 3). Baseline HRQoL surveys have been obtained for &amp;gt;80% of eligible subjects. Treg samples have been obtained for 95% of subjects, and 74% of subjects have consented to optional biology studies. Conclusion: Despite historical difficulty completing interventional trials in pediatric ITP and pandemic-related enrollment challenges, PINES trial enrollment is progressing successfully and will ultimately provide definitive data regarding the efficacy of eltrombopag in children with newly diagnosed ITP. There are no current data supporting the use of TPO-RAs for newly diagnosed ITP in children, or as monotherapy for newly diagnosed ITP in adults. Results from this trial therefore carry the potential to change management practices in ITP.

Childhood Autoimmune Hemolytic Anemia: A Scoping Review

Introduction Autoimmune hemolytic anemia (AIHA) is a disorder characterized by excessive premature red blood cell breakdown due to the presence of autoantibodies. It is rare in children, with an estimated incidence of 0.2 per one million individuals younger than 20 years. There are no guidelines on the investigation and management of pediatric AIHA, and contemporary approaches are derived from adult guidelines. AIHA is an important cause of morbidity in pediatric hematology patients, and a review of pediatric AIHA investigation, diagnosis, and treatment is warranted. This scoping review will summarize the current landscape of diagnosis and management of pediatric AIHA to inform future studies aimed at formulating a pediatric specific approach to the investigation and management of this small but complex patient population. Methods This review searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) from inception to July 27, 2021. All screening and data extraction was done in parallel by two reviewers. Experimental and observational studies reporting on diagnostic criteria, laboratory work up, or treatment/management of AIHA in populations with at least 20% of patients ≤18 years were included. Study characteristics, population characteristics, and study outcomes were extracted and synthesized narratively and descriptively using counts (percentages). Results After removing duplicates, the titles and abstracts of 1742 studies were screened and 109 studies were selected for full-text review. Forty three studies, published between 2003 and 2021, met inclusion criteria and proceeded to data extraction. Forty cohort studies (35 retrospective, 5 prospective) and 3 case-control studies were included. No randomized controlled trials were identified. Diagnostic criteria for AIHA was provided in 29 (67%) studies, with 4 (9%) studies classifying the severity of AIHA. All but one study defined AIHA with at least one of: positive direct antibody test, evidence of anemia, and evidence of hemolysis (including increased lactate dehydrogenase or bilirubin, or decreased haptoglobin). Patients with Evan's syndrome were included in 31 (72%) studies, and 30 (70%) studies included special populations such as transplant recipients or patients with underlying autoimmune conditions. AIHA treatments in pediatric patients were reported in 41 (95%) studies, with 26 (60%) studies dividing the treatments into first- and second-line therapies. Common first-line therapies included steroids (unspecified) in 18 (42%) studies, prednisone in 9 (21%) studies, methylprednisolone in 9 (21%) studies, intravenous immunoglobulin (IVIG) in 17 (40%) studies, and/or combinations of these therapies. Common second-line therapies included rituximab in 16 (37%) studies, cyclosporine in 16 (37%) studies, IVIG in 13 (30%) studies and/or combinations of these therapies. Discussion Compared to pediatric immune thrombocytopenia, there is substantially less information available describing pediatric AIHA. Most studies are retrospective and include both patients with isolated AIHA and Evan's syndrome. Data on diagnosis, investigation, and management are inconsistently reported. Only two studies reported their diagnostic approach for identifying secondary causes of AIHA. Although most studies described diagnostic criteria for AIHA, the specific criteria were variable, and only 4 studies classified AIHA according to severity. Specific treatments were variable. First-line treatments were most commonly a combination of corticosteroids and IVIG in keeping with guidelines for the management of AIHA in adults. Second-line treatments typically consisted of an immunosuppressive or immunomodulatory agent, with the specific medication or combination of medications varying depending on past therapies attempted and the patient's underlying disease. Conclusion Our review identified a deficit of high quality, prospective studies into pediatric AIHA. Prospective studies evaluating the treatment of pediatric AIHA are needed. A standardized definition and classification of pediatric AIHA will help guide much needed future studies of the appropriate investigation and management of pediatric AIHA.

Evaluating the prevalence of inborn errors of immunity in adults with chronic immune thrombocytopenia or Evans syndrome

AbstractInborn errors of immunity (IEIs) are monogenic disorders that predispose patients to immune dysregulation, autoimmunity, and infection. Autoimmune cytopenias, such as immune thrombocytopenia (ITP) and Evans syndrome (a combination of ITP and autoimmune hemolytic anemia), are increasingly recognized phenotypes of IEI. Although recent findings suggest that IEIs may commonly underlie pediatric ITP and Evans syndrome, its prevalence in adult patients with these disorders remains undefined. This study sought to estimate the prevalence of underlying IEIs among adults with persistent or chronic ITP or Evans syndrome using a next-generation sequencing panel encompassing >370 genes implicated in IEIs. Forty-four subjects were enrolled from an outpatient adult hematology clinic at a tertiary referral center in the United States, with a median age of 49 years (range, 20-83). Fourteen subjects (31.8%) had secondary ITP, including 8 (18.2%) with Evans syndrome. No cases of IEI were identified despite a high representation of subjects with a personal history of autoimmunity (45.5%) and early onset of disease (median age at diagnosis of 40 years [range, 2-77]), including 20.5% who were initially diagnosed as children. Eight subjects (18.2%) were found to be carriers of pathogenic IEI variants, which, in their heterozygous state, are not disease-causing. One case of TUBB1-related congenital thrombocytopenia was identified. Although systematic screening for IEI has been proposed for pediatric patients with Evans syndrome, findings from this real-world study suggest that inclusion of genetic testing for IEI in the routine work-up of adults with ITP and Evans syndrome has a low diagnostic yield.

OC 48.1 FOXO1 and FOXO3 Regulate the Proliferation and Suppressive Function of Regulatory T Cells in Pediatric Immune Thrombocytopenia

OC 48.1 FOXO1 and FOXO3 Regulate the Proliferation and Suppressive Function of Regulatory T Cells in Pediatric Immune Thrombocytopenia