A global comparative field study to evaluate the factor VIII activity of efanesoctocog alfa by one-stage clotting and chromogenic substrate assays at clinical haemostasis laboratories.

INTRODUCTION: Structural and chemical modifications of factor VIII (FVIII) products may influence their behaviour in FVIII activity assays. Hence, it is important to assess the performance of FVIII products in these assays. Efanesoctocog alfa is a new class of FVIII replacement therapy designed to provide both high sustained factor activity levels and prolonged plasma half-life. AIM: Evaluate the accuracy of measuring efanesoctocog alfa FVIII activity in one-stage clotting assays (OSAs) and chromogenic substrate assays (CSAs). METHODS: Human plasma with no detectable FVIII activity was spiked with efanesoctocog alfa or a full-length recombinant FVIII product comparator, octocog alfa, at nominal concentrations of 0.80 IU/mL, 0.20 IU/mL, or 0.05 IU/mL, based on labelled potency. Clinical haemostasis laboratories (N = 35) tested blinded samples using in-house assays. Data from 51 OSAs (14 activated partial thromboplastin time [aPTT] reagents) and 42 CSAs (eight kits) were analyzed. RESULTS: Efanesoctocog alfa activity was reliably (±25% of nominal activity) measured across all concentrations using OSAs with Actin FSL and multiple other aPTT reagents. Under- and overestimation of FVIII activity occurred with some reagents. No specific trend was observed for any class of aPTT activators. A two- to three-fold overestimation was consistently observed using CSAs and the OSA with Actin FS as the aPTT reagent across evaluated concentrations. CONCLUSION: Under- or overestimation occurred with some specific OSAs and most CSAs, which has been previously observed with other modified FVIII replacement products. Efanesoctocog alfa FVIII activity was measured with acceptable accuracy and reliability using several OSA methods and commercial plasma standards.

Pharmacokinetics of recombinant factor VIII in adults with severe hemophilia A: fixed-sequence single-dose study of octocog alfa, rurioctocog alfa pegol, and efanesoctocog alfa.

Background: Efanesoctocog alfa is a new class of factor (F) VIII replacement therapy designed to provide high sustained factor levels for longer by overcoming the von Willebrand factor half-life ceiling. Objectives: To assess the pharmacokinetics and safety of standard half-life (octocog alfa) and extended half-life (rurioctocog alfa pegol) FVIIIs and efanesoctocog alfa. Methods: This phase 1 study (NCT05042440; EudraCT 2021-000228-37) enrolled previously treated adult men with severe hemophilia A. Patients received sequential single 50-IU/kg doses of octocog alfa, rurioctocog alfa pegol, and efanesoctocog alfa after appropriate washout periods between each dose. Results: Thirteen participants were enrolled. Geometric mean elimination half-life of octocog alfa, rurioctocog alfa pegol, and efanesoctocog alfa was 11.0, 15.4, and 43.3 hours, respectively, and area under the FVIII activity-time curve was 1670, 2820, and 10,100 IU × h/dL, respectively. Efanesoctocog alfa maintained mean FVIII activity levels of >40 IU/dL for up to 4 days and at ∼10 IU/dL on day 7. Corresponding times for >40 IU/dL and >10 IU/dL were <1 and <2 days, respectively, for octocog alfa and 1 day and <3 days, respectively, for rurioctocog alfa pegol. No serious treatment-emergent adverse events were reported for efanesoctocog alfa, and no inhibitor development to FVIII was detected. Conclusion: Efanesoctocog alfa had 3- to 4-fold longer elimination half-life and 3- to 6-fold greater exposure (area under the FVIII activity-time curve, 6.03 and 3.57 folds) than octocog alfa and rurioctocog alfa pegol. Efanesoctocog alfa provided high sustained FVIII activity in the normal-to-near-normal range (>40 IU/dL) for up to 4 days after the dose and at ∼10 IU/dL on day 7.

Post hoc longitudinal assessment of the efficacy and safety of recombinant factor IX Fc fusion protein in hemophilia B.

Long-term efficacy and safety of the extended half-life recombinant factor IX Fc fusion protein (rFIXFc) has been established among previously treated patients with severe hemophilia B in 2 phase 3 trials (B-LONG [#NCT01027364] and Kids B-LONG [#NCT01440946]) and a long-term extension study (B-YOND [#NCT01425723]). In this study, we report post hoc analyses of pooled longitudinal data for up to 6.5 years for rFIXFc prophylaxis. In the B-LONG study, subjects ≥12 years received weekly dose-adjusted prophylaxis (WP; starting dose, 50 IU/kg), individualized interval-adjusted prophylaxis (IP; initially, 100 IU/kg every 10 days), or on-demand dosing. In the Kids B-LONG study, subjects <12 years received 50 to 60 IU/kg every 7 days, adjusted as needed. In the B-YOND study, subjects received WP (20-100 IU/kg every 7 days), IP (100 IU/kg every 8-16 days), modified prophylaxis, or on-demand dosing; switching between treatment groups was permitted. A total of 123 subjects from B-LONG and 30 from Kids B-LONG study were included, of whom 93 and 27, respectively, enrolled in the B-YOND study. The median cumulative duration of treatment was 3.63 years (range, 0.003-6.48 years) in B-LONG/B-YOND and 2.88 years (range, 0.30-4.80 years) in Kids B-LONG/B-YOND group. Annualized bleed rates (ABRs) remained low, annualized factor consumption remained stable, and adherence remained high throughout treatment. Low ABRs were also maintained in subjects with dosing intervals ≥14 days or with target joints at baseline. Complete resolution of evaluable target joints and no recurrence in 90.2% of baseline target joints during follow-up were observed. rFIXFc prophylaxis was associated with sustained clinical benefits, including long-term bleed prevention and target joint resolution, for severe hemophilia B.

Efanesoctocog Alfa Prophylaxis for Patients with Severe Hemophilia A.

BACKGROUND: Efanesoctocog alfa provides high sustained factor VIII activity by overcoming the von Willebrand factor-imposed half-life ceiling. The efficacy, safety, and pharmacokinetics of efanesoctocog alfa for prophylaxis and treatment of bleeding episodes in previously treated patients with severe hemophilia A are unclear. METHODS: We conducted a phase 3 study involving patients 12 years of age or older with severe hemophilia A. In group A, patients received once-weekly prophylaxis with efanesoctocog alfa (50 IU per kilogram of body weight) for 52 weeks. In group B, patients received on-demand treatment with efanesoctocog alfa for 26 weeks, followed by once-weekly prophylaxis with efanesoctocog alfa for 26 weeks. The primary end point was the mean annualized bleeding rate in group A; the key secondary end point was an intrapatient comparison of the annualized bleeding rate during prophylaxis in group A with the rate during prestudy factor VIII prophylaxis. Additional end points included treatment of bleeding episodes, safety, pharmacokinetics, and changes in physical health, pain, and joint health. RESULTS: In group A (133 patients), the median annualized bleeding rate was 0 (interquartile range, 0 to 1.04), and the estimated mean annualized bleeding rate was 0.71 (95% confidence interval [CI], 0.52 to 0.97). The mean annualized bleeding rate decreased from 2.96 (95% CI, 2.00 to 4.37) to 0.69 (95% CI, 0.43 to 1.11), a finding that showed superiority over prestudy factor VIII prophylaxis (P<0.001). A total of 26 patients were enrolled in group B. In the overall population, nearly all bleeding episodes (97%) resolved with one injection of efanesoctocog alfa. Weekly prophylaxis with efanesoctocog alfa provided mean factor VIII activity of more than 40 IU per deciliter for the majority of the week and of 15 IU per deciliter at day 7. Prophylaxis with efanesoctocog alfa for 52 weeks (group A) improved physical health (P<0.001), pain intensity (P = 0.03), and joint health (P = 0.01). In the overall study population, efanesoctocog alfa had an acceptable side-effect profile, and the development of inhibitors to factor VIII was not detected. CONCLUSIONS: In patients with severe hemophilia A, once-weekly efanesoctocog alfa provided superior bleeding prevention to prestudy prophylaxis, normal to near-normal factor VIII activity, and improvements in physical health, pain, and joint health. (Funded by Sanofi and Sobi; XTEND-1 ClinicalTrials.gov number, NCT04161495.).

Efanesoctocog alfa for hemophilia A: results from a phase 1 repeat-dose study.

Efanesoctocog alfa (rFVIIIFc-VWF-XTEN; BIVV001) is a new class of factor VIII (FVIII) replacement that breaks the von Willebrand factor-imposed FVIII half-life ceiling. In a phase 1/2a study, single-dose efanesoctocog alfa was well tolerated, and no safety concerns were identified. We evaluated the safety, tolerability, and pharmacokinetics of repeat-dose efanesoctocog alfa in a phase 1 study in previously treated adults (≥150 exposure days) with severe hemophilia A. Participants received 4 once weekly doses of efanesoctocog alfa (cohort 1, 50 IU/kg; cohort 2, 65 IU/kg). All enrolled participants (cohort 1, n = 10; cohort 2, n = 14) completed the study. Inhibitor development to FVIII was not detected. After the last dose of efanesoctocog alfa, geometric mean (range) FVIII activity half-life, area under the activity-time curve, and steady-state maximum concentration for cohort 1 and cohort 2 were 41.3 (34.2-50.1) and 37.3 (28.9-43.8) hours, 8290 (5810-10 300) and 11 200 (7040-15 800) hours × IU/dL, and 131 (96-191) and 171 (118-211) IU/dL, respectively. There was minimal accumulation after 4 doses. Mean FVIII activity for cohort 1 and cohort 2, respectively, was 46% and 69% on day 3 postdose and 10% and 12% on day 7 postdose. Overall, 4 once-weekly doses of efanesoctocog alfa were well tolerated, no safety concerns were identified, and no bleeds were reported during the treatment period. Once-weekly efanesoctocog alfa provided high sustained FVIII activity within the normal to near-normal range for 3 to 4 days postdose and may improve protection against bleeds in patients with hemophilia A. The trial is study 2018-001535-51 in the EU Clinical Trials Register.

Real-world assay variability between laboratories in monitoring of recombinant factor IX Fc fusion protein activity in plasma samples.

INTRODUCTION: Monitoring of factor IX (FIX) replacement therapy in haemophilia B relies on accurate coagulation assays. However, considerable interlaboratory variability has been reported for one-stage clotting (OSC) assays. This study aimed to evaluate the real-world, interlaboratory variability of routine FIX activity assays used in clinical haemostasis laboratories for the measurement of recombinant FIX Fc fusion protein (rFIXFc) activity. METHODS: Human FIX-depleted plasma was spiked with rFIXFc at 0.80, 0.20 or 0.05 IU/mL based on label potency. Participating laboratories tested samples using their own routine OSC or chromogenic substrate (CS) assay protocols, reagents and FIX plasma standards. Laboratories could perform more than one measurement and method, and were not fully blinded to nominal activity values. RESULTS: A total of 142 laboratories contributed OSC results from 175 sample kits using 11 different activated partial thromboplastin time (aPTT) reagents. The median recovered FIX activity for the 0.80, 0.20 and 0.05 IU/mL samples was 0.72 IU/mL, 0.21 IU/mL and 0.060 IU/mL, respectively. Across all OSC reagents, interlaboratory variability (% CV) per aPTT reagent ranged from 9.4% to 32.1%, 8.2% to 32.6% and 12.2% to 42.0% at the 0.80, 0.20 and 0.05 IU/mL levels, respectively. CS results showed excellent median recoveries at all nominal levels (87.5% to 115.0%; n = 11) with low interlaboratory variability (CV 3.6% to 15.4%). CONCLUSION: This large, real-world data set indicates that rFIXFc activity in plasma samples can be accurately measured with the majority of routine OSC and CS assay methods. Given the variation in FIX assay procedures between sites, it is important that individual laboratories qualify their in-house methods for monitoring of rFIXFc activity.

Concurrent manifestation of oligodontia and thrombocytopenia caused by a contiguous gene deletion in 12p13.2: A three-generation clinical report.

BACKGROUND: Wnt and Wnt-associated pathways play an important role in the genetic etiology of oligodontia, a severe form of tooth agenesis. Loss-of-function mutations in LRP6 , encoding a transmembrane cell-surface protein that functions as a coreceptor in the canonical Wnt/b-catenin signaling cascade, also contribute to genetic oligodontia. METHODS AND RESULTS: We describe a three-generation family with hereditary thrombocytopenia and oligodontia. Genome wide array analysis was performed. The array results from the index patient revealed an interstitial loss of 150 kb in 8p23.1 (chr8:6,270,299-6,422,558; hg19) encompassing MCPH1 and ANGPT2 and an interstitial loss of 290 kb in 12p13.2 (chr12:12,005,720-12,295,290; hg19) encompassing ETV6, BCL2L14 and LRP6. CONCLUSION: This case report shows a three-generation family with hereditary thrombocytopenia and oligodontia with a heterozygous 290 kb novel contiguous gene deletion in band p13.2 of chromosome 12, encompassing LRP6 and ETV6. In this report we discuss the clinical relevance of the deletion of both genes and illustrate the importance of thorough examination of oligodontia patients. Comprising not only the oral status but also the medical history of the patients and their relatives.

[Acute illness following chicken pox: spleen infarction as a complication of varicella zoster infection]. / Acuut ziek na waterpokken: miltinfarcten als complicatie van varicella-zosterinfectie.

BACKGROUND: Varicella zoster virus (VZV) infection can cause temporary acquired protein S or C deficiency via cross reacting antibodies and consequently inducing a hypercoagulable state. CASE DESCRIPTION: A 6-year-old girl with a history of congenital cardiac disease was seen at an Emergency Department with acute chest pain, dyspnoea and fever, seven days after developing chicken pox. Diagnostic tests revealed massive infarction of the spleen, and a protein S and C deficiency. In addition, blood cultures revealed a Lancefield group A ß-haemolytic streptococcus (GABHS). The patient recovered fully after treatment with low molecular weight heparin and antibiotics. CONCLUSION: In this patient, septic emboli caused splenic infarction. Thromboembolic complications should be suspected in children with VZV who present with acute symptoms, in particular if bacterial superinfection is found.

Chemokine/chemokine receptor interactions in extramedullary leukaemia of the skin in childhood AML: differential roles for CCR2, CCR5, CXCR4 and CXCR7.

Chemokine receptor/ligand interactions orchestrate the migration of cells to peripheral tissues such as the skin. We analysed chemokine receptor expression by acute myeloid leukaemic (AML) cells present in peripheral blood (n = 7), bone marrow (n = 6), or skin (n = 11) obtained from 15 paediatric AML patients with skin involvement and in 10 AML patients without skin involvement. High percentages of circulating CCR2(pos) AML cells were only detected in patients with extramedullary disease. Skin-residing AML cells displayed a different set of receptors in situ, namely: CCR5, CXCR4, CXCR7 and CX3CR1. These results suggest the involvement of different chemokine/chemokine receptor interactions in homing and retention of AML blasts in the skin.

The effect of graft-versus-host disease on skin endothelial and epithelial cell chimerism in stem-cell transplant recipients.

BACKGROUND: Recent evidence indicates that bone marrow-derived cells contribute to endothelial and epithelial cell renewal in recipients of an allogeneic stem-cell transplantation (SCT). Controversy remains on the biological significance of these donor-derived cells. METHODS: This study investigated the occurrence of endothelial and epithelial cell chimerism in relation to the conditioning regimen, time interval after SCT, and development of acute and chronic graft-versus-host disease (GVHD). Fifty-five skin biopsy samples from 35 female patients transplanted with a male donor were screened for donor-derived endothelial and epithelial cells using in situ hybridization for Y chromosomes in combination with immunohistochemical cell-marking techniques. RESULTS: Endothelial cell chimerism was found in 25% of the biopsies and increased in time after SCT. Its appearance was increased in patients with acute GVHD more than 2 weeks before biopsy. Epithelial cell chimerism was found in 85% of the biopsies. Appearance of epithelial cell chimerism was not correlated with the time interval after SCT or with tissue damage caused by GVHD. CONCLUSION: From these results, we conclude that donor-derived endothelial cell chimerism results from repair of damaged endothelium and maintenance of vascular homeostasis. In contrast, epithelial cell chimerism follows a more uniform pattern of engraftment, not influenced by tissue damage.

Possible link between unique chemokine and homing receptor expression at diagnosis and relapse location in a patient with childhood T-ALL.

Childhood acute lymphoblastic leukemia (ALL) is often associated with extramedullary infiltration by leukemic cells at diagnosis or at relapse. To understand the mechanisms behind the dissemination of T-cell ALL (T-ALL) cells this study investigated the homing receptor expression on the blast cells of 11 pediatric T-ALL patients at diagnosis. One patient revealed a unique profile with high expression of the chemokine receptor CCR9 and the integrin CD103 on the T-ALL cells. Both of these molecules are specifically associated with homing to the gut. This finding was clinically significant as the patient later suffered a relapse that was confined to the gut. Immunohistochemistry revealed that the leukemic cells in the gut still expressed CCR9 and colocalized with a high expression of the CCR9 ligand, CCL25. These findings suggest that the original expression of CCR9 and CD103 on the leukemic cells contributed to the relapse location in the gut of this patient.

Aberrant chemokine receptor expression and chemokine production by Langerhans cells underlies the pathogenesis of Langerhans cell histiocytosis.

Langerhans cell histiocytosis (LCH) is characterized by a clonal proliferation and retention of cells with a Langerhans cell (LC)-like phenotype at various sites within the body. The present study set out to elucidate whether aberrant expression of chemokine receptors or dysregulation of chemokine production in LCH lesions could explain abnormal retention of these cells. Immunohistochemical analysis on 13 LCH biopsies of bone, skin, and lymph node all expressed the immature dendritic cell (DC) marker CCR6 on the lesional LCs and absence of the mature DC marker CCR7. Furthermore, regardless of the tissue site, LCH lesions markedly overexpressed CCL20/MIP-3alpha, the ligand for CCR6. The lesional LCs appeared to be the source of this CCL20/MIP-3alpha production as well as other inflammatory chemokines such as CCL5/RANTES and CXCL11/I-TAC. These may explain the recruitment of eosinophils and CD4+CD45RO+ T cells commonly found in LCH lesions. The findings of this study emphasize that, despite abundant TNF-alpha, lesional LCs remain in an immature state and are induced to produce chemokines, which via autocrine and paracrine mechanisms cause not only the retention of the lesional LCs but also the recruitment and retention of other lesional cells. We postulate that the lesional LCs themselves control the persistence and progression of LCH.