Inhibitor development remains a major challenge in factor VIII (FVIII) replacement therapy. verITI-8 is the first prospective study of a recombinant factor VIII Fc fusion protein (efmoroctocog alfa; rFVIIIFc) for first-time immune tolerance induction (ITI) in males with severe hemophilia A and high-titer inhibitors (historical peak ≥5 Bethesda units [BU]/mL). In this single-arm, open-label, multicenter study, screening was followed by ITI (rFVIIIFc 200 IU/kg/day until tolerization or maximum of 48 weeks). Those who achieved ITI success entered a tapering period, returning to standard prophylaxis, and then entered follow-up. Primary endpoint was time to tolerization with rFVIIIFc defined by inhibitor titer <0.6 BU/mL, incremental recovery (IR) ≥66% of expected IR (IR ≥1.32 IU/dL per IU/kg), and half-life ≥7 hours within 48 weeks. Sixteen subjects received ≥1 rFVIIIFc dose. Twelve (75%), 11 (69%), and 10 subjects (63%), respectively, achieved negative inhibitor titers, an IR ≥66%, and a half-life ≥7 hours (ie, tolerance) within 48 weeks. Median (IQR) times in weeks to achieve these markers of success were 7.4 (2.2-17.8), 6.8 (5.4-22.4), and 11.7 (9.8-26.2), respectively. All subjects experienced ≥1 TEAE (treatment-emergent adverse event [AE]), and 1 reported ≥1 related TEAE (injection site pain). Nine subjects experienced ≥1 treatment-emergent serious AE (TESAE). No thrombotic events, discontinuations due to AEs, or deaths were reported during the study. As the first extended half-life rFVIII with prospective data in ITI, rFVIIIFc offered short time to tolerization with durable responses in almost two-thirds of subjects and was well tolerated. Trial registered at www.clinicaltrials.gov (NCT03093480).

Multisystem Inflammatory Syndrome in Children (MIS-C) is a late systemic inflammatory response to a recent mild or asymptomatic coronavirus disease of 2019 infection. The pathophysiology is incompletely understood but it often features significant coagulopathy along with cardiac and endothelial dysfunction. Endothelial inflammation has been primarily described in acute coronavirus disease of 2019 infection, with less characterization in MIS-C. Here we describe novel findings of nearly universal severe and prolonged factor VIII (FVIII) and von Willebrand factor antigen elevations in an institutional cohort of patients with MIS-C ages younger than or 21 years old (N=31). All patients had elevated acute phase reactants and D-dimer at presentation and met published criteria for MIS-C. FVIII was high at presentation in 97% of patients but continued to rise during the ensuing weeks of treatment to a mean 429%, peaking on median day 17 of illness as an outpatient. FVIII levels were >600% in multiple patients. von Willebrand factor antigen was measured less frequently but showed similar trends. These escalations occurred amidst resolving cardiac dysfunction and acute phase reactant normalization and despite patients receiving multimodal anti-inflammatory treatments and aspirin and enoxaparin thromboprophylaxis. No thrombotic events occurred. Endothelial dysfunction represented by very elevated FVIII levels may persist longer than other acute phase reactants may reflect.

The most serious complication in hemophilia A (HA) treatment is the development of factor (F)VIII inhibitors or anti-drug antibodies (ADA) occurring in 25-35% of patients with severe HA. The immunological mechanisms underlying the development of ADA against FVIII products have not been completely understood yet. Immunological danger signals associated with events such as infection or surgery have been suggested to play a critical role. In previous studies, we have demonstrated that plasma-derived (pd)FVIII but not recombinant (r)FVIII can activate human monocyte-derived dendritic cells (DC) in a danger signaldependent manner, which subsequently mediate the proliferation of autologous CD4+ T cells. In this study, we have investigated the ability of plasma components, naturally present in pdFVIII products, to mediate T cell responses. In fact, we show that addition of plasma to rFVIII plus lipopolysaccharide (LPS)-stimulated DC induces proliferation of autologous CD4+ T cells. Interestingly, although DC pulsed with LPS plus plasma induce T cell proliferation upon co-culture, the addition of FVIII significantly increased the number of proliferating as well as FVIII-specific CD4+ T cells. Total proliferating CD4+ T cells and FVIII-specific subsets were identified mainly as central memory T cells. Experiments using blocking antibodies and receptor antagonists revealed that the complement proteins C3a and, to a lesser extent, C5a are critically involved in these LPS-mediated T cell responses. Collectively, our results indicate that complement proteins are potent drivers of T cell responses towards FVIII. Data presented provide a model how event-related substitution of FVIII in HA patients might contribute to inhibitor development.

Emicizumab prophylaxis significantly reduces bleeding episodes in patients with hemophilia A (PwHA). There is little information on coagulant potentials in emicizumab-treated PwHA with infection, however. We encountered an emicizumab-treated PwHA with inhibitor, complicated with Epstein-Barr virus-associated infectious mononucleosis (IM) in phase 1/2 study (ACE001JP/ACE002JP). Although it was a typical clinical course of IM, activated partial thromboplastin time was mildly prolonged but rotational thromboelastometry revealed severely impaired coagulant potential. The blood concentration of emicizumab decreased moderately in the low concentration range, resulting in an increased risk of bleeding and possibly leading to severe ileocecal bleeds requiring coil embolization. The blood concentrations of factors IX/X little decreased and antiemicizumab antibodies did not develop, however. After the influence by IM resolved, his coagulant potentials gradually recovered with the recovery of emicizumab concentration, and parameters by global coagulation assays improved. An IM case for emicizumab-treated PwHA may need to monitor using global coagulation assays.

Hemophilia is a congenital bleeding disorder with a deficiency of coagulation factor 8 or 9 (hemophilia A or B, respectively) and a tendency for recurrent bleeding, especially into muscles and joints, which may cause orthopedic damage and necessitate joint replacement surgeries at a young age. In recent years, there has been a huge breakthrough in the treatment of hemophilia. Until recently, the only available therapy was based on repeated intravenous injection of factor concentrates (replacement therapy). Nowadays, new therapeutic options are being developed, some already registered and approved and others are still in clinical studies. The new molecules either enhance the coagulation system or inhibit coagulation inhibitors, promoting faster and improved clot formation, and are administered subcutaneously. These developments have had an enormous impact on the patients' quality of life. In the last decade, the option of complete (genetic) cure of the disease has been explored for both hemophilia A and hemophilia B, and multiple clinical gene therapy trials are currently being conducted. In this review, we discuss the novel therapies currently available for hemophilia. We will elaborate on extended half-life long acting factor concentrates, subcutaneous non-replacement therapies and gene therapy.

Milk fat globule-EGF factor VIII (MFG-E8) has been identified as an important source of bioactive peptides, which may exert a pivotal role in regulating biologic redox equilibrium. However, the composition of MFG-E8 polypeptides and their mechanisms on mitigating sarcopenia remain unknown. The aim of this study was to identify the composition of MFG-E8 polypeptides and its effects against oxidative stress in dexamethasone-induced L6 cell injury. Simulated digestion in vitro and liquid chromatography-tandem mass spectrometry were used in this investigation. A total of 95 peptides were identified during complete simulated digestion; among them, the contents of 21 peptides were analyzed, having been determined to exceed 1%. Molecular docking assay found that IDLG, KDPG, YYR, and YYK exhibited high binding affinity with keap1. MTT, dichlorodihydrofluorescein diacetate, mito- and lyso-tracker, and transmission electron microscope assay demonstrated that IDLG and KDPG can alleviate oxidative stress-injured L6 cell vitality, mitochondria activity, vacuolation, and function decrease, and increased autophagy, thereby improving mitochondrial homeostasis. From a molecular perspective, IDLG and KDPG can decrease the expression of keap1 and increase the expression of Nrf2, HO-1, and PGC-1α. Therefore, MFG-E8-derived IDLG and KDPG could be potential polypeptides countering oxidative stress in the treatment of sarcopenia, via the keap1/Nrf2/HO-1 signaling pathway.

Protein S is a vitamin K-dependent protein that acts as a break in secondary hemostasis by inactivating activated factor V and activated factor VIII. We report a case of a 40 years old male who had the first episode of deep vein thrombosis of the left lower limb 10 years back, which despite treatment, reoccurred 3 months later in the bilateral lower limb. Thrombophilic screening showed severe protein S deficiency. The patient then developed deep vein thrombosis of both upper limbs. The patient was advised to place an inferior vena cava filter, which he denied. The patient is now presenting with multiple episodes of post-thrombotic syndrome. Such attacks are treated with elastic compression stockings, rivaroxaban, and morphine. However, despite medication, the pain has not yet subsided. Hence, even though protein S deficiency is the rare cause of deep vein thrombosis when recurrent should be considered despite its rare occurrence.

Hemophilia A (HA) cell therapy approaches in pediatric individuals require suitable factor (F)VIII-producing cells for stable engraftment. Liver sinusoidal endothelial cells (LSEC) and hematopoietic stem cells (HSC) have been demonstrated to be suitable for the treatment of adult HA-mice. However, after transplantation in busulfan (BU)-conditioned newborn mice, adult LSEC/HSC cannot efficiently engraft, while murine fetal liver (FL) hemato/vascular cells from embryonic day 11-13 of gestation (E11-E13), strongly engraft the hematopoietic and endothelial compartments while also secreting FVIII. Our aim was to investigate the engraftment of FL cells in newborn HA mice for obtaining a suitable "proof of concept" for the development of a new HA treatment in neonates. Hence, we transplanted FLE11 or E13 cells and adult bone marrow (BM) cells into newborn HA mice with or without BU preconditioning. The engraftment levels and FVIII activity was assessed starting from 6 weeks after transplantation. FLE11-E13+BU-transplanted newborns reached up to 95% engraftment with stable FVIII activity levels observed for 16 months. FLE13 cells showed engraftment ability even in absence of BU preconditioning, while FLE11 cells did not. BM+BU transplanted newborn HA mice showed high levels of engraftment; nevertheless, in contrast to FL cells, BM cells cannot engraft HA newborns in non-conditioning regimen. Finally, none of the transplanted mice developed anti-FVIII antibodies. Overall, this study sheds some light on the therapeutic potential of healthy FL cells in the cure of HA neonatal/pediatric patients.

Acquired hemophilia A (AHA) is a rare disease caused by autoantibodies inhibiting factor VIII (FVIII) activity. Although the conditionis usually idiopathic, there may be other underlying diseases. Treatment consists of two steps: treatment of acute bleeding and immunosuppression. In this multicenter study, we aimed to demonstrate the clinical characteristics, management details, and survival of AHA patients in Turkey. Data was collected from eleven centers in Turkey. aPTT, FVIII, FVIII inhibitor, and hemoglobin (HB) levels, mixing test results, and demographics at diagnosis, treatment information, adverse events, bleeding episodes during follow-up, relapses, and outcome were analyzed. Twenty-nine patients were analyzed (58.6% female). No underlying disorder could be detected in 14 patients. The most prevalent etiologies were pregnancy, malignancy and infections. The median FVIII activity and FVIII inhibitor titer at diagnosis were 0.7% (0.0-29.4%) and 32.6 BU (0.6-135.6 BU) respectively. Bleeding was severe in 44.8% of patients. The HB value was significantly lower in patients with severe bleeding. Most of the patients (n = 25, 86.2%) had only one bleeding episode without relapse, three patients (10.3%) had two bleeding episodes, and one patient had more than three bleedings. 21 (75%) patients received hemostatic therapy. The use of recombinant FVIIa was slightly higher than activated prothrombin complex concentrate (15 versus 10 patients). Immunosuppressive treatment was initiated in 26 (93%) patients. Regimens containing steroid, cyclophosphamide, and rituximab in different combinations were the most preferred. The median follow-up period was 13 months (2-156 months). Median overall survival was 154.97 months. Four and six-year survival were 90.9 ± 0.8% and 77.9 ± 14.1% respectively. This is a unique study that investigated the demographic characteristics, treatment approaches, and patient survival of AHA in Turkey.

Hemophilia A (factor VIII [FVIII] deficiency) and hemophilia B (factor IX [FIX] deficiency) are the X-linked recessive bleeding disorders that clinically manifest with recurrent bleeding, predominantly into muscles and joints. In its severe presentation, when factor activity is less than 1% of normal, hemophilia presents with spontaneous musculoskeletal bleeds and may progress to debilitating chronic arthropathy. Management of hemophilia has changed profoundly in the past decades. From on-demand to prophylactic factor concentrate replacement, the treatment goal shifted from controlling bleeds to preventing bleeds and improving quality of life. In this new scenario, gene therapy has arisen as a paradigm-changing therapeutic option, a one-time treatment with the potential to achieve sustained coagulation FVIII or FIX expression even within the normal range. This review discusses the critical impact of adeno-associated virus (AAV) gene transfer in hemophilia care, including the recent clinical outcomes, changes in disease perceptions, and its treatment burden. We also discuss the challenging scenario of the AAV-directed immune response in the clinical setting and potential strategies to improve the long-lasting efficacy of hemophilia gene therapy efficacy.