Bleeding control improves after switching to emicizumab: Real-world experience of 177 children in the PedNet registry

INTRODUCTION

Despite the rapid uptake of emicizumab in the paediatric haemophilia A (HA) population, real-world data on the safety and efficacy is limited.

AIM

To report on bleeding and safety in paediatric patients receiving emicizumab prophylaxis.

METHODS

Data were extracted from the multicentre prospective observational PedNet Registry (NCT02979119). Children with haemophilia A, and ≥50 FVIII exposures or inhibitors present receiving emicizumab maintenance therapy were analysed. Data were summarized as medians with interquartile range (IQR, P25-P75). Mean (95% confidence interval (CI)), annualized (joint) bleeding rate (A(J)BR) during emicizumab and ≤2 years before emicizumab prophylaxis were modelled and compared using negative binomial regression.

RESULTS

Total of 177 patients started emicizumab at median 8.6 years (IQR 4.8-13.1), most had no FVIII inhibitors (64%). Follow up before emicizumab was median: 1.68 years (IQR: 1.24-1.90) and during emicizumab: 1.32 years (IQR: .94-2.11). In patients without inhibitors, mean ABR reduced after starting emicizumab from 2.41 (CI 1.98-2.95) to 1.11 (CI .90-1.36, p < .001), while AJBR reduced from.74 (CI .56-.98) to.31 (CI .21-.46, p < .001). Concordantly, in patients with inhibitors, mean ABR reduced from 5.08 (CI 4.08-6.38) to .75 (CI .56-1.01, p < .001), while AJBR reduced from 1.90 (CI 1.42-2.58) to .34 (CI .21-.56, p < .001). Five emicizumab-related adverse events were reported (3% of the cohort), including one patient with antidrug antibodies.

CONCLUSION

This study showed improved bleeding control compared to previous treatment and a favourable safety profile during emicizumab therapy in paediatric haemophilia A patients.

TRIAL REGISTRATION

Clin.gov.trial-NCT02979119.

Haemostatic Effects of Recombinant Human Erythropoietin in Chronic Haemodialysis Patients

Recombinant human erythropoietin was administered for up to 40 weeks to nine patients on chronic haemodialysis. From the third week of administration onwards, not only haemoglobin and haematocrit but also the platelet count rose, the latter, however, transiently. Subnormal platelet aggregation before therapy also improved transiently and in parallel with the erythropoietin dosage. The bleeding time normalized in almost all patients. There were no major side-effects. We conclude that recombinant erythropoietin improves haemostasis in chronic haemodialysis patients by increasing the haematocrit and in addition transiently enhances platelet number and function.

Pituitary adenylate cyclase-activating polypeptide (PACAP) in zebrafish models of nephrotic syndrome

Pituitary adenylate cyclase-activating polypeptide (PACAP) is an inhibitor of megakaryopoiesis and platelet function. Recently, PACAP deficiency was observed in children with nephrotic syndrome (NS), associated with increased platelet count and aggregability and increased risk of thrombosis. To further study PACAP deficiency in NS, we used transgenic Tg(cd41:EGFP) zebrafish with GFP-labeled thrombocytes. We generated two models for congenital NS, a morpholino injected model targeting nphs1 (nephrin), which is mutated in the Finnish-type congenital NS. The second model was induced by exposure to the nephrotoxic compound adriamycin. Nephrin RNA expression was quantified and zebrafish embryos were live-screened for proteinuria and pericardial edema as evidence of renal impairment. Protein levels of PACAP and its binding-protein ceruloplasmin were measured and GFP-labeled thrombocytes were quantified. We also evaluated the effects of PACAP morpholino injection and the rescue effects of PACAP-38 peptide in both congenital NS models. Nephrin downregulation and pericardial edema were observed in both nephrin morpholino injected and adriamycin exposed congenital NS models. However, PACAP deficiency was demonstrated only in the adriamycin exposed condition. Ceruloplasmin levels and the number of GFP-labeled thrombocytes remained unchanged in both models. PACAP morpholino injections worsened survival rates and the edema phenotype in both congenital NS models while injection with human PACAP-38 could only rescue the adriamycin exposed model. We hereby report, for the first time, PACAP deficiency in a NS zebrafish model as a consequence of adriamycin exposure. However, distinct from the human congenital NS, both zebrafish models retained normal levels of ceruloplasmin and thrombocytes. We further extend the renoprotective effects of the PACAP-38 peptide against adriamycin toxicity in zebrafish.

Human phenotype ontology annotation and cluster analysis to unravel genetic defects in 707 cases with unexplained bleeding and platelet disorders

BACKGROUND

Heritable bleeding and platelet disorders (BPD) are heterogeneous and frequently have an unknown genetic basis. The BRIDGE-BPD study aims to discover new causal genes for BPD by high throughput sequencing using cluster analyses based on improved and standardised deep, multi-system phenotyping of cases.

METHODS

We report a new approach in which the clinical and laboratory characteristics of BPD cases are annotated with adapted Human Phenotype Ontology (HPO) terms. Cluster analyses are then used to characterise groups of cases with similar HPO terms and variants in the same genes.

RESULTS

We show that 60% of index cases with heritable BPD enrolled at 10 European or US centres were annotated with HPO terms indicating abnormalities in organ systems other than blood or blood-forming tissues, particularly the nervous system. Cases within pedigrees clustered closely together on the bases of their HPO-coded phenotypes, as did cases sharing several clinically suspected syndromic disorders. Cases subsequently found to harbour variants in ACTN1 also clustered closely, even though diagnosis of this recently described disorder was not possible using only the clinical and laboratory data available to the enrolling clinician.

CONCLUSIONS

These findings validate our novel HPO-based phenotype clustering methodology for known BPD, thus providing a new discovery tool for BPD of unknown genetic basis. This approach will also be relevant for other rare diseases with significant genetic heterogeneity.

Transcriptional diversity during lineage commitment of human blood progenitors

Blood cells derive from hematopoietic stem cells through stepwise fating events. To characterize gene expression programs driving lineage choice, we sequenced RNA from eight primary human hematopoietic progenitor populations representing the major myeloid commitment stages and the main lymphoid stage. We identified extensive cell type-specific expression changes: 6711 genes and 10,724 transcripts, enriched in non-protein-coding elements at early stages of differentiation. In addition, we found 7881 novel splice junctions and 2301 differentially used alternative splicing events, enriched in genes involved in regulatory processes. We demonstrated experimentally cell-specific isoform usage, identifying nuclear factor I/B (NFIB) as a regulator of megakaryocyte maturation-the platelet precursor. Our data highlight the complexity of fating events in closely related progenitor populations, the understanding of which is essential for the advancement of transplantation and regenerative medicine.

Severe gastrointestinal bleeding and thrombocytopenia in a child with an anti-GATA1 autoantibody

We describe a patient, who developed during the first week of life petechiae and hematomas caused by severe thrombocytopenia and gastrointestinal bleeding due to multiple small gastric hemangiomata. Bone marrow examination showed hypermegakaryocytosis and dysmegakaryopoiesis. Alloimmune thrombocytopenia was excluded. Only 3 y later, platelet counts normalized and bleedings disappeared but small skin hemangiomata remained. Electron microscopy showed enlarged round platelets with a paucity of alpha granules similar as in GATA1-deficient patients but no GATA1 mutation was found. Immunoblot analysis showed a strong interaction between patient Igs and recombinant GATA1, GATA2, and the N finger (Nf) of GATA1. The lymphocyte transformation test with recombinant GATA1Nf was positive. In vitro culturing of normal CD34 cells with purified patient Igs showed a decreased number of megakaryocyte colonies but an increased overall size of the colonies compared with control Igs. Mice injected with patient Igs showed a reduced platelet count compared with mice injected with control Igs. Thrombopoiesis was also reduced after injection of patient Igs in transgenic zebrafish compared with control Igs. In conclusion, this study is the first report of an anti-GATA1 autoantibody leading to severe thrombocytopenia and gastrointestinal bleeding from multiple pinpoint hemangiomata.