Hepatic adeno-associated virus (AAV)-serotype 2 mediatedgene transfer results in transgene product expression that is sustained in experimental animals but not in human subjects. We hypothesize that ...this is caused by rejection of transduced hepatocytes by AAV capsid-specific memory CD8+ T cells reactivated by AAV vectors. Here we show that healthy subjects carry AAV capsid-specific CD8+ T cells and that AAV-mediated gene transfer results in their expansion. No such expansion occurs in mice after AAV-mediated gene transfer. In addition, we show that AAV-2 induced human T cells proliferate upon exposure to alternate AAV serotypes, indicating that other serotypes are unlikely to evade capsid-specific immune responses.
Safety and pharmacokinetics (PK) of recombinant von Willebrand factor (rVWF) combined at a fixed ratio with recombinant factor VIII (rFVIII) were investigated in 32 subjects with type 3 or severe ...type 1 von Willebrand disease (VWD) in a prospective phase 1, multicenter, randomized clinical trial. rVWF was well tolerated and no thrombotic events, inhibitors, or serious adverse events were observed. The PK of rVWF ristocetin cofactor activity, VWF antigen, and collagen-binding activity were similar to those of the comparator plasma-derived (pd) VWF-pdFVIII. In vivo cleavage of ultra-large molecular-weight rVWF multimers by ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13; the endogenous VWF protease) and generation of characteristic satellite bands were demonstrated. In 2 subjects with specific nonneutralizing anti-VWF–binding antibodies already detectable before rVWF infusion, a reduction in VWF multimers and VWF activity was observed. Stabilization of endogenous FVIII was enhanced following post–rVWF-rFVIII infusion as shown by the difference in area under the plasma concentration curve compared with pdVWF-pdFVIII (AUC0-∞) (P < .01). These data support the concept of administering rVWF alone once a therapeutic level of endogenous FVIII is achieved. This trial was registered at www.clinicaltrials.gov as #NCT00816660.
•rVWF is safe, well tolerated, and has a PK profile generally comparable to pdVWF, but promotes enhanced stabilization of endogenous FVIII.
•Bleeding from angiodysplasia and AVM is common in inpatient HHT, more so than heavy menstrual bleeding and postpartum hemorrhage in women.•IDA is common in HHT whether or not they bleed, suggesting ...need for universal iron screening.
Display omitted
Hereditary hemorrhagic telangiectasia (HHT) is a common bleeding disorder, but little is known regarding prevalence and risk factors for bleeding. Adult discharges with HHT and bleeding were identified by International Classification of Disease, 10th edition (ICD-10) codes in the National Inpatient Sample (NIS), 2016-2018. Prevalence estimates were weighted using NIS discharge-level weights to reflect national estimates. Risk factors for bleeding were determined by weighted multivariable logistic regression. Among 18 170 849 discharges, 2528 (0.01%) had HHT, of whom 648 (25.6%) had bleeding. Arteriovenous malformation (AVM) (31.9% vs 1.3%), angiodysplasia (23.5% vs 2.3%), telangiectasia (2.3% vs 0.2%), and epistaxis (17.9% vs 0.6%) were more common in HHT than in non-HHT patients (non-HHT), each P < .001. In contrast, menstrual (HMB) and postpartum bleeding (PPH) were less common in reproductive-age HHT than non-HHT, each P < .001. Anemia associated with iron deficiency (IDA), was equally common in HHT with or without bleeding (15.7% vs 16.0%), but more common than in non-HHT (7.5%), P < .001. Comorbidities, including gastroesophageal reflux (25.9% vs 20.0%) and cirrhosis (10.0% vs 3.6%) were greater in HHT than non-HHT, each P < .001. In multivariable logistic regression, peptic ulcer disease (OR, 8.86; P < .001), portal vein thrombosis (OR, 3.68; P = .006), and hepatitis C, (OR, 2.13; P = .017) were significantly associated with bleeding in HHT. In conclusion, AVM and angiodysplasia are more common and HMB and PPH less common in patients in those with HHT than non-HHT. IDA deficiency is as common in HHT with and without bleeding, suggesting ongoing blood loss and need for universal iron screening.
Among individuals with the rare congenital bleeding disorder hemophilia A, the major challenge is inhibitor formation, which is associated with significant morbidity and cost. Yet, as the optimal ...approach to prevent and eradicate inhibitors is not known, we are at equipoise. Because classic trial design is not practical in a rare disease setting, we designed 2 48-week randomized trials comparing ELOCTATE and emicizumab to prevent and eradicate inhibitors. To achieve statistical efficiency, we incorporated historic data (Bayesian priors) on inhibitor formation to allow preferential randomization to emicizumab, piecewise exponential survival models to determine mean and 95% confidence interval for inhibitor formation in each arm, and simulations to determine the best model design to optimize power. To achieve administrative efficiency, the trials will be performed with the same sites, staff, visit frequency, blood sampling, laboratories, and laboratory assays, with streamlined enrollment so patients developing inhibitors in the first trial may be enrolled on the second trial. The primary end point is the probability of inhibitor formation or inhibitor eradication, respectively. The design indicates early stopping rules for overwhelming evidence of superiority of the emicizumab arms. Simulations indicate that, with 66 subjects, the Prevention Trial will have 84% power to detect noninferiority of emicizumab to ELOCTATE with a margin of 10% if emicizumab is truly 10% superior to ELOCTATE; with 90 subjects, the Eradication Trial will have 80% power to detect 15% superiority of ELOCTATE immune tolerance induction with vs without emicizumab. Thus, a platform design provides statistical and administrative efficiency to conduct INHIBIT trials.
•Because classic randomized trials are impractical in hemophilia, a Bayesian platform design was used to design 2 linked inhibitor trials.•Simulations indicate the platform design provides statistical and administrative efficiency to run prevention and eradication trials.
Display omitted
Background
Persons with hemophilia (PWH) are at risk for chronic hemophilic arthropathy (HA). Joint replacement surgery may be used to relieve intractable pain and/or restore joint function.
...Objectives
This multicenter, prospective, observational cohort study evaluated the rate of bleeding during the postoperative period after total hip (THA) or knee arthroplasty (TKA).
Patients/Methods
We included PWH of any severity ≥18 years of age who were undergoing THA or TKA. Clinical decisions were made at the discretion of the treating physician according to local standards of care. Clinical data were prospectively recorded. Major bleeding was defined as bleeding in a critical site, bleeding that resulted in either a 2 g/dl or greater decrease in hemoglobin during any 24‐h period, or transfusion of two or more units of packed red blood cells.
Results
One hundred thirty‐one procedures (98 TKA and 33 THA) were performed, 39 (29.8%) of which were complicated by major bleeding, including 46% of THA and 25% of TKA. The risk of major bleeding was increased in THA compared to TKA (OR 2.50, p = .05), and by the presence of an inhibitor (OR 4.29, p = .04), increased BMI (OR 4.49 and 6.09 for overweight and obese, respectively, compared to normal BMI, each p < .01), and non‐use of an antifibrinolytic medication (OR 3.00, p = .03). Neither continuous clotting factor infusion (versus bolus infusion) nor pharmacologic thromboprophylaxis were associated with bleeding risk.
Conclusions
The bleeding risk remains substantial after THA and TKA in PWH, despite factor replacement. Use of antifibrinolytic medications is associated with decreased risk.
von Willebrand disease (VWD) is the most common inherited bleeding disorder, and type 1 VWD is the most common VWD variant. Despite its frequency, diagnosis of type 1 VWD remains the subject of ...debate. In order to study the spectrum of type 1 VWD in the United States, the Zimmerman Program enrolled 482 subjects with a previous diagnosis of type 1 VWD without stringent laboratory diagnostic criteria. von Willebrand factor (VWF) laboratory testing and full-length VWF gene sequencing was performed for all index cases and healthy control subjects in a central laboratory. Bleeding phenotype was characterized using the International Society on Thrombosis and Haemostasis bleeding assessment tool. At study entry, 64% of subjects had VWF antigen (VWF:Ag) or VWF ristocetin cofactor activity below the lower limit of normal, whereas 36% had normal VWF levels. VWF sequence variations were most frequent in subjects with VWF:Ag <30 IU/dL (82%), whereas subjects with type 1 VWD and VWF:Ag ≥30 IU/dL had an intermediate frequency of variants (44%). Subjects whose VWF testing was normal at study entry had a similar rate of sequence variations as the healthy controls (14%). All subjects with severe type 1 VWD and VWF:Ag ≤5 IU/dL had an abnormal bleeding score (BS), but otherwise BS did not correlate with VWF:Ag. Subjects with a historical diagnosis of type 1 VWD had similar rates of abnormal BS compared with subjects with low VWF levels at study entry. Type 1 VWD in the United States is highly variable, and bleeding symptoms are frequent in this population.
•Type 1 VWD in the United States is highly variable, including patients with very low VWF levels as well as those with mild or minimal VWF deficiency.•The frequency of sequence variants in the VWF gene increases with decreasing VWF level, but BS does not vary by VWF level.
What is the correct use of established clotting factors, prothrombin complex concentrates (PCCs), and activated factor VII in bleeding complications of trauma, surgery, and old and new oral ...anticoagulants? How will new clotting factors, specifically the long-acting factors, change the hemostatic management of coagulation deficiency disorders? From bench to bedside, comparative coagulation studies and clinical trials of modified clotting factors are providing insights to help guide hemostatic management of congenital and acquired bleeding disorders. Comparative thrombin-generation studies and preclinical and clinical trials suggest that PCCs and fresh-frozen plasma are effective in reversing the anticoagulant effects of warfarin, yet there are few data to guide reversal of the new oral anticoagulants dabigatran and rivaroxaban. Although coagulation studies support the use of PCCs to reverse new oral anticoagulants, correlation with clinical response is variable and clinical trials in bleeding patients are needed. For congenital bleeding disorders, exciting new technologies are emerging from the bench. Data from clinical trials of molecularly modified coagulation factors with extended half-lives suggest the possibility of fewer infusions, reduced bleeds, and better quality of life in persons with hemophilia. Preclinical studies of other novel prohemostatic approaches for hemophilia and other congenital coagulation disorders include RNA interference silencing of antithrombin, monoclonal anti-tissue factor pathway inhibitor (anti-antibody, anti-tissue factor pathway inhibitor) aptamer, bispecific anti-IXa/X antibody, and fucoidans. Understanding the comparative coagulation studies of established prohemostatic agents, the pharmacokinetics of new long-acting clotting factors, and their correlation with bleeding outcomes will provide opportunities to optimize the hemostatic management of both congenital and acquired hemostatic disorders.
von Willebrand disease (VWD) is a congenital bleeding disorder characterized by deficient or defective von Willebrand factor (VWF). Among women with VWD, postpartum hemorrhage (PPH) is common. ...Treatment options at delivery include plasma-derived VWF (pdVWF) and recombinant VWF (rVWF). However, limited data are available regarding their efficacy. We conducted a retrospective observational study comparing PPH in women with VWD treated at the Hemophilia Center of Western Pennsylvania between 1 February 2017 and 31 January 2018 with either rVWF or pdVWF. We compared postpartum outcomes, including PPH frequency and estimated blood loss (EBL) at delivery. There were a total of 12 deliveries, 7 vaginal and 5 cesarean. At delivery and for 3 days postpartum, 6 women received 80 IU/kg of rVWF and 6 received 80 IU/kg of pdVWF, based on prepregnancy weight, insurance, and/or patient choice. Treatment groups had similar demographics, including median age (32.0 vs 27.0 years; P = .075), bleeding scores (3.0 vs 3.5; P = .734), and prepregnancy body mass index (29.0 vs 29.2 kg/m2; P = .691). PPH occurred in 3 (25.0%) of 12 deliveries, with no difference by treatment group (2 of 6 rVWF vs 1 of 6 pdVWF; P = 1.000) and no difference in EBL by treatment group (685 vs 462 mL; P = .384) or delivery type (vaginal, P = .722 vs cesarean, P = .531). In summary, PPH occurred in one-fourth of the deliveries in women with VWD, despite a higher dose (80 IU/kg) of rVWF or pdVWF. Future trials are needed to develop and assess novel strategies to prevent PPH in VWD.
•rVWF contains no factor VIII but has higher VWF multimers and a longer half-life than pdVWF.•PPH occurred in 25% of women with VWD, despite a higher VWF dose (80 IU/kg).
Display omitted
PDF
