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Summary: Chronic refractory primary immune thrombocytopenia (CRITP) is currently defined as refractory to multiple therapeutic of second‐line agents with or without splenectomy, faced with the threat of severe bleeding and challenging to obtain effective treatment. Although stable and effective drug therapy is needed, it is tough to find one. Daratumumab (Dara), an anti‐CD38 monoclonal antibody presented the target cloned plasma cells in multiple myeloma, has also been reported to be effective in refractory autoimmune cytopenia in some case or series reports and ongoing clinical trials for adult patients with CRITP. Here, we report the early and durable response of Dara combination with avatrombopag in three CRITP patients (2 male and 1 female aged 12, 5 and 7 years, respectively) in our centre, with a follow‐up period of more than 25 weeks. Before Dara, the duration of immune thrombocytopenia was 9, 1.4 and 4 years, respectively, a baseline platelet count of 4, 6, 9 × 109/L, the bleeding score was all above level 2 and the number of previous drugs was >3. The time to response (R: Plt ≥30 × 109/L with at least a twofold increase in the baseline count) of Dara was on Day 45, 6 and 4 and achieved complete response (CR: Plt ≥100 × 109/L) on Day 51, 6 and 8, the sustained response (SR: Plt >30 × 109/L following Dara at ≥75% of the platelet count assessment at follow‐up end‐point since the patient achieved response) was 48, 175 and 204 days with the follow‐up time of 39.1, 25.9 and 29.7 weeks. The bleeding score decreased from grade 3 to grade 0 during follow‐up. No significant treatment‐related adverse events were found during follow‐up. Dara combination with avatrombopag may be a safe and efficacious therapy for children with CRITP, but it needs to be further explored. [ABSTRACT FROM AUTHOR]

Summary: Avatrombopag (AVA) is a novel thrombopoietin receptor agonist (TPO‐RA) that has been recently approved as a second‐line therapy for immune thrombocytopenia (ITP) in adults; however, its safety and efficacy data in children are lacking. Here, we demonstrated the efficacy and safety of AVA as second‐line therapy in children with ITP. A multicentre, retrospective, observational study was conducted in children with persistent or chronic ITP who did not respond to or relapsed from previous treatment and were treated with AVA for at least 12 weeks between August 2020 and December 2022. The outcomes were the responses (defined as achieving a platelet count ≥30 × 109/L, twofold increase in platelet count from baseline and absence of bleeding), including rapid response within 4 weeks, sustained response at weeks 12 and 24, bleeding control and adverse events (AEs). Thirty‐four (18 males) patients with a mean age of 6.3 (range: 1.9–15.3) years were enrolled. The median number of previous treatment types was four (range: 1–6), and 41.2% patients switched from other TPO‐RAs. Within 4 weeks, overall response (OR) was achieved in 79.4% patients and complete response (CR, defined as a platelet count ≥100 × 109/L and the absence of bleeding) in 67.7% patients with a median response time of 7 (range: 1–27) days. At 12 weeks, OR was achieved in 88.2%, CR in 76.5% and sustained response in 44% of patients. At 24 weeks, 22/34 (64.7%) patients who achieved a response and were followed up for 24 weeks were evaluated; 12/22 (54.55%) achieved a sustained response. During AVA therapy, median platelet counts increased by week 1 and were maintained throughout the treatment period. The proportion of patients with grade 1–3 bleeding decreased from 52.95% at baseline to 2.94% at 12 weeks, while concomitant ITP medications decreased from 36.47% at baseline to 8.82% at 12 weeks, with only 9 (26.47%) patients receiving rescue therapy 23 times within 12 weeks. There were 61.8% patients with 59 AEs: 29.8% with Common Terminology Criteria for Adverse Events grade 1 and the rest with grade 2. These findings show that AVA could achieve a rapid and sustained response in children with persistent or chronic ITP as a second‐line treatment, with good clinical bleeding control and reduction of concomitant ITP therapy, without significant AEs. [ABSTRACT FROM AUTHOR]

Summary: We have previously confirmed the efficacy and safety of eltrombopag (ELT) in children with chronic immune thrombocytopenia (cITP). However, data on both long‐term exposure and early use of TPO‐RAs are lacking, so further 'field‐practice' evidence on treatment is required. Here, we report the long‐term follow‐up results (between September 2018 and June 2023) of our previous study. The main objective of this study was to retrospectively review our large institutional experience with ITP patients previously enrolled in our paediatric cITP study. We had more than 3 years of follow‐up by June 2023 for treatment patterns and outcomes. A total of 65 patients (28 males) were enrolled, with a median age at ELT initiation of 6.34 (range 1.65, 14.13) years and a follow‐up of 47.07 (36.00, 57.00) months, with 40.36 (10.53, 56.83) months of ELT therapy at the time of analysis. In total, 29.23% (19/65) of patients discontinued ELT due to stable response, and 18.46% (12/65) of patients switched to other ITP therapies due to loss of response (LOR) after 19.13 (14.53, 26.37) months. Of the 19 patients who discontinued ELT due to a stable response, 24.62% (16/65) achieved a 12 m sustained response off‐treatment (SRoT); the last recorded platelet count ranged from 56 to 166 × 109/L (median 107 × 109/L); and 4.62% (3/65) patients relapsed at 5, 6 and 9 months after discontinuation. Of the 12 patients who LOR to ELT after 19.13 (14.53, 26.37) months of therapy, four switched to avatrombopag, three switched to hetrombopag, two switched to traditional Chinese medicine (TCM), one underwent splenectomy and two received additional prednisolone under ELT treatment. Thirty‐four patients who tapered and maintained a durable response. The patients with LOR and the patients with tapering were compared; the platelet count at the start of ELT is lower, and the time to response is longer in the patients with LOR. The platelet count at the start of ELT and the time to response may be the predictive factors for LOR during ELT treatment. We report more than 3 years of long‐term clinical data on children with cITP using ELT. These data do not raise any new safety concerns regarding the long‐term use of ELT in children with cITP. [ABSTRACT FROM AUTHOR]

Objectives: To assess current treatment‐related outcomes for children with severe and moderate haemophilia A (cHA) in China. Methods: This cross‐section Patient Report Outcome (PRO) report collected PRO data of severe and moderate cHAs registered in the 'Hemophilia Home Care Center' database (http://web.bjxueyou.cn) between January 2021 and November 2022. Data included records of bleeding, activities, and concentrates consumption. All patients had a confirmed diagnosis of moderate or severe haemophilia A (FVIII: C ≤ 5%) and were < 18 years old. Results: Among 1038 analysable cases, 9.6% of children with inhibitors had a higher rate of intracranial haemorrhage, dropout school rate, and higher FVIII consumption than children without inhibitors. Among 100 children with inhibitors, 36 patients were treated without immune tolerance induction (ITI), 14 patients with irregular treatment and 50 patients received ITI. Children with ITI had a lower ABR (2.4 (0,6.6) vs. 13.4 (9.5, 26.6), p<.001) and AJBR (0 (0, 3.1) vs. 8.9 (1.6, 19.3), p <.001) compared to those without ITI. Among 938 children without inhibitors, 28.5% received on‐demand treatment and 71.5% received prophylaxis. Of 528 children with 1343.8 (1050.4, 2922.9)IU/kg/year median FVIII consumption, 43.0% received low‐dose, 43.2% received intermediate‐dose, and 13.8% received high‐dose regimen; these children with prophylaxis had a lower ABR (3.1 (0, 10.7) vs. 12.8 (2.4, 45.5), p <.001), AJBR (0.5 (0, 3.9) vs. 3.0 (0, 12.0), p <.001) and disability rate (9.0% vs.18.5%, p =.032) compared to children who received on‐demand treatment. Conclusion: The high rate of drop‐out of school and disability still present a huge gap to meet the needs in China. It is necessary to improve the level of medical accessibility and medicine affordability and strengthen the patient/parent's education in China. [ABSTRACT FROM AUTHOR]

Summary: The thrombopoietin receptor agonists (TPO‐RA) were recommended for primary immune thrombocytopenia (ITP) during the pandemic of COVID‐19. However, the incidence of thrombocytosis and thrombosis was sporadically reported in the chronic immune thrombocytopenia (CITP) patients receiving TPO‐RA during the COVID‐19 infection. With the local prevalence of COVID‐19 in December 2022 in the Beijing area, we got more powerful evidence about the change in platelet (Plt) counts associated with COVID‐19 infection. A single‐centre observational cohort study was performed from the beginning of December 2022 to the end of February 2023 to enrol CITP children treated with TPO‐RA alone as the second‐line treatment and suffering from the COVID‐19 infection in December 2022. The Plt counts before, during and after COVID‐19 infection were collected. In total, 67 (34 males and 33 females) patients with 8.10 (2.15, 15.70) years of age were enrolled. Sixty‐three patients who had responded to the TPO‐RA showed a transient increase in Plt counts after the infection of COVID‐19. The time of starting to increase was on Day 3 (2, 7), and to the peak level on Day 14 (7, 19) of infection with the peak Plt count was 289 (88, 1974) × 109/L. With at least 2 months observation period from COVID‐19 infection, the Plt counts of 100% (63/63) patients declined to the baseline on Day 25 (14, 41). The phenomenon of transient increase in Plt counts has been shown in the CITP children who responded to TPO‐RA when suffering from COVID‐19 infection. [ABSTRACT FROM AUTHOR]

Summary: Eltrombopag (ELT) is effective and safe in adult persistent/chronic immune thrombocytopenia (p/cITP); a proportion could achieve a sustained response off treatment (SRoT); however, data on children are lacking. We attempted to analyse SRoT of ELT in children with p/cITP in this study. A multicentre retrospective observational study was performed in November 2022 for children with p/cITP who used ELT alone for >2 months between January 2017 and November 2021. Clinical data of pre‐, during and post‐ELT were collected. SRoT was defined as maintaining a platelet count of ≥30 × 109/L without rescue therapy for at least 6 months off ELT. There were 143 patients enrolled; 69.2% (99/143) achieved an overall response of 43.3% and 25.9% achieved complete response (CR) and response (R). Among the 35 patients analysed from whom ELT was withdrawn, 71.4% (25/35) showed SRoT after discontinuing ELT without additional ITP therapy, with a median follow‐up of 0.94 (range, 0.53–3.8) years, equal to 17.5% (25/143) in all patients treated with ELT. Compared with the patients with relapse (n = 10), the SRoT patients (n = 25) had a higher rate of CR (80% [20/25] vs. 40% [4/10]), shorter interval time from initiation to taper (6.4 months vs. 9.4 months), longer time from taper to withdrawal (1.1 years vs. 0.3 years) and a longer duration of ELT treatment (1.6 years vs. 0.5 years) with p < 0.05. Patients who achieved CR could attain SRoT more easily (p = 0.02). ELT had a response in 69.2% of children with p/cITP and 17.5% of them attained SRoT with good tolerance. The patients who achieved CR and began ELT treatment as early as possible, with a longer treatment duration and slower tapering, had a higher probability of SRoT. [ABSTRACT FROM AUTHOR]

Background: Drug-induced thrombocytopenia (DITP) is a severe adverse reaction and a significantly under-recognized clinical problem in children. However, for post-marketing pharmacovigilance purposes, detection of DITP signals is crucial. This study aimed to develop a signal detection model for DITP using the pediatric electronic medical records (EMR) data. Methods: This study used the electronic medical records collected at Beijing Children's Hospital between 2009 and 2020. A two-stage modeling method was developed to detect the signal of DITP. In the first stage, we calculated the crude incidence by mining cases of thrombocytopenia to select the potential suspected drugs. In the second stage, we constructed propensity score–matched retrospective cohorts of specific screened drugs from the first stage and estimated the odds ratio (OR) and 95% confidence interval (CI) using conditional logistic regression models. The novelty of the signal was assessed by current evidence. Results: In the study, from a total of 839 drugs, 21 drugs were initially screened as potentially inducing thrombocytopenia. In total, we identified 18 positive DITP associations. Of these, potential DITP risk of nystatin (OR: 1.75, 95% CI: 1.37–2.22) and latamoxef sodium (OR: 1.61, 95% CI: 1.38–1.88) were two new DITP signals in both children and adults. Six associations between thrombocytopenia and drugs including imipenem (OR: 1.69, 95% CI: 1.16–2.45), teicoplanin (OR: 4.75, 95% CI: 3.33–6.78), fusidic acid (OR: 2.81, 95% CI: 2.06–3.86), ceftizoxime sodium (OR: 1.83, 95% CI: 1.36–2.45), ceftazidime (OR: 2.16, 95% CI: 1.58–2.95), and cefepime (OR: 5.06, 95% CI: 3.77–6.78) were considered as new signals in children. Conclusion: This study developed a two-stage algorithm to detect safety signals of DITP and found eighteen positive signals of DITP, including six new signals in a pediatric population. This method is a promising tool for pharmacovigilance based on EMR data. [ABSTRACT FROM AUTHOR]

Primary immune thrombocytopenia (ITP) is an acquired autoimmune bleeding disorder. One of the key mediators of IFN-γ signaling is the signal transducer and activator of transcription 1 protein (STAT1). We evaluated the relationship between STAT1 gene single nucleotide polymorphisms (SNPs) and the associated risk of ITP in a prospective case-control study. A total of 548 children were recruited: 328 children with ITP and 220 healthy children as sex- and age-matched normal controls. The Sequenom MassArray system (Sequenom, San Diego, CA) was used to detect three SNPs genotypes in the STAT1 gene: rs10208033, rs12693591, and rs1467199. There is a statistically significant difference in STAT1 rs1467199 allele frequencies with comparison of each of the four clinical subgroups of ITP patients to the normal controls ( p = 0.0432). Also, newly diagnosed ITP patients and chronic ITP patients demonstrate significant different genotypes ( χ2 = 8.511, p = 0.0142) and allelic frequency ( p = 0.0055). Although a positive STAT1 rs1467199 genotype subgroups to the STAT1 mRNA expression level cannot be established, there is a weak correlation between STAT1 mRNA level and the activity ratio of Type 1 T helper lymphocyte and Type 2 T helper lymphocyte (Th1/Th2 ratio) ( p = 0.0544); correlation with IFN-γ alone did not reach statistical significance ( p = 0.1715). The findings in our study suggest that STAT1 rs1467199 SNP plays a potential role in the IFN-γ dependent development of autoimmunity in children with ITP. The important clinical implication of STAT1 SNPs testing as a predictor of pediatric chronic ITP will be validated in future molecular and protein functional analysis. [ABSTRACT FROM AUTHOR]

Aim To investigate the status of DNA methylation in the Foxp3 promoter in pediatric ITP patients and assess the role of DNA methylation of Treg cells in the pathogenesis of ITP. Methods Quantitative DNA methylation levels of Foxp3 promoter in pediatric ITP patients were detected by MassARRAY EpiTYPER. Methylation levels of Foxp3 promoter were analyzed in ITP patients and normal controls. Results Significantly higher expression of CpG-2, CpG-3 and CpG-11.12 was observed in ITP patients compared to the controls. A subgroup analysis revealed that persistent and chronic ITP patients exhibited significantly higher CpG-6 expression than in the subgroup of newly diagnosed ITP patients. All patients who represented newly diagnosed ITP at admission were reclassified at later follow-up. In this follow-up subgroup analysis, there were significantly higher levels of CpG-6 in the persistent ITP group than that in the newly diagnosed ITP group. Conclusions Our results indicate that defective Treg cell activity identified in ITP might be partially mediated through hypermethylation of CpG sites in the promoter region of Foxp3. [ABSTRACT FROM AUTHOR]

Physical activity is a crucial part of an active lifestyle for haemophiliac children. However, the fear of bleeds has been identified as barriers to participating physical activity for haemophiliac children even with prophylaxis. Lack of evidence and metrics driven by data is key problem. We aim to develop machine learning models based on clinical data with multiple potential factors considered to predict risk of physical activity bleeding for haemophilia children with prophylaxis. From this cohort study, we collected information on 98 haemophiliac children with adequate prophylaxis (trough FVIII:C level > 1 %). The involved potential predictor variables include demographic information, treatment information, physical activity, joint evaluation, and pharmacokinetic parameters, etc. We applied CoxPH, Random Survival Forests (RSF) and DeepSurv to construct prediction models for the risk of bleeding during physical activities. All three survival analysis models were internally and externally validated. A total of 98 patients were enrolled in this study. Their median age was 7.9 (5.5, 10.2) years. The CoxPH, RSF and DeepSurv models' discriminative and calibration abilities were all high, and the RSF model had the best performance (Internal validation: C-index, 0.7648 ± 0.0139; Brier Score, 0.1098 ± 0.0015; External validation: C-index, 0.7260 ± 0.0154; Brier Score, 0.0930 ± 0.0018). The prediction curves demonstrated that the developed RSF model can distinguish the risks well between bleeding and non-bleeding patients, as well as patients with different levels of physical activity. Meanwhile, the feature importance analysis confirmed that physical activity bleeding was deduced by comprehensive effects of various factors, and the importance of different factors on bleeding outcome is discrepant. This study revealed from the mechanism that it is necessary to incorporate multiple factors to accurately predict physical activity related bleeding risk. In clinical practice, the designed machine learning models can provide guidance for children with haemophilia A to positively participate in physical activity. • Predicting the risk of bleeding during physical activity in children withhaemophilia A • Three machine learning methods used to construct prediction models • The RSF model had the best discriminative and calibration • The models can guide children with haemophilia regarding participation in physical activities [ABSTRACT FROM AUTHOR]

Shorter interval-time from inhibitor detection to starting immune tolerance induction (ITI) might predict better ITI outcomes for severe Hemophilia A (SHA) patients with high-risk-inhibitors. However, the prediction-impact of interval-time for these patients on low-dose ITI strategy remained unclear. To explore the relationship between interval-time and low-dose ITI outcomes in Chinese SHA children with high-risk-inhibitors. This was a single-center, retrospective study on SHA children with high-risk-inhibitors (each with immediate pre-ITI inhibitor titer>10 Bethesda Units/mL) undergoing low-dose ITI strategy for ≥24 months. ITI outcomes and their predictive factors were evaluated at the 24th month treatment for each patient. The predictive ability of interval-time on ITI success was determined using receiver operating characteristic (ROC) curve. Among 47 patients investigated, 34 (72.3 %) achieved success. Independent predictor for ITI-outcome on multivariate analysis included the interval-time (p = 0.007) and peak inhibitor-titer (p = 0.011). Shorter interval-time predicted ITI success [cut-off value = 22.3 months, area under ROC-curve (AUC) = 0.701] and early-ITI success within 12 month (cut-off value = 9.4 months AUC = 0.704). Linear regression analysis suggested each month interval-time delay delayed success by 0.1552 month. Unlike the interval-time, peak inhibitor-titer had no success-predictive value in high-peak inhibitor-titer patients on ITI with immunosuppressants. Interval-time represented a strong predictive value for outcomes in our low-dose ITI strategy for SHA patients with high-risk-inhibitors. Shorter interval-time was associated with higher success rate and earlier success achievement. The respective interval-time cut-off values were 22.3 months for ITI success and 9.4 months for early-success. • The interval-time is the time from inhibitor detection to starting ITI. • Interval-time for predicting low-dose ITI outcomes remained unclear, for high-risk-inhibitors patients. • Interval-time had a strong predictive value for outcomes in our low-dose ITI strategy. • Interval-time cut-off values were 22.3 for success and 9.4 months for early-success. [ABSTRACT FROM AUTHOR]

MPIG6B has orthologous physiological effects in human and mice, which regulates platelet production and function. For this reason, germline loss-of-function mutations in this gene cause congenital thrombocytopenia that is associated with bone marrow fibrosis, organomegaly and subsequent anemia. This was described in a consanguineous Arabian family with a novel truncation mutation (p.C108*) in chromosome 6, open reading frame 25 gene, also known as MPIG6B. In our case, we identified a homozygous frameshift variation (c.392delC,p.P134Lfs*10) in a ten-month-old boy presenting with signs of pallor, splenomegaly and resistant hemocytopenia. Interestingly, this is a new form of a MPIG6B variation, which could disrupt the effector protein for the key hematopoiesis regulators. This report adds to the growing number of mutations causing complex clinical manifestations associated with pancytopenia and splenomegaly in children. • A Chinese boy presenting with splenomegaly and hemocytopenia was identified a homozygous frameshift mutation in MPIG6B gene. • It's a new form of MPIG6B variation that has never been reported in public database before. • Due to a germline mutation, stem cell transplantation was recommended first. [ABSTRACT FROM AUTHOR]