Hemophilia is a rare congenital bleeding disorder that results from complete or partial deficiency of blood coagulation factor (F)VIII (hemophilia A) or FIX (hemophilia B) due to pathogenic variants in their coding genes. Hemophilia requires complex management. To date, there is no evidence-based clinical practice guideline on hemophilia treatment based on the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. This evidence-based clinical practice guideline from the International Society on Thrombosis and Haemostasis aims to provide an overview of evidence and support patients, caregivers, hematologists, pediatricians, other clinicians, researchers, and stakeholders in treatment decisions about congenital hemophilia A and B. The International Society on Thrombosis and Haemostasis formed a multidisciplinary guideline panel of physicians and patients with global representation, balanced to minimize potential bias from conflicts of interest. The panel prioritized a set of clinical questions and outcomes according to their importance for clinicians and patients. A methodological team supported the guideline development process, including searching for evidence and performing systematic reviews. The GRADE approach was used, including GRADE Evidence to Decision frameworks. The recommendations were subject to public comment. The panel selected 13 questions, of which 11 addressed the treatment of hemophilia A and 2 the treatment of hemophilia B. Specifically, the panel addressed questions on prophylactic and episodic treatment with FVIII concentrates, bypassing agents, and nonfactor therapy (emicizumab) for hemophilia A (with and without inhibitors) as well as immune tolerance induction for hemophilia A. For hemophilia B, the panel addressed questions on prophylactic and episodic treatment of bleeding events with FIX concentrates. Agreement was reached for all 13 recommendations, of which 7 (54%) were based on evidence from randomized clinical trials, 3 (23%) on observational studies, and 3 (23%) on indirect comparisons. Strong recommendations were issued for prophylactic over episodic treatment for severe and moderately severe hemophilia A and B. Only conditional recommendations were issued for the remaining questions. Future research should focus on direct treatment comparisons and the treatment of hemophilia B with and without inhibitors. Future updates of this guideline will provide an updated evidence synthesis on the current questions and focus on new FVIII and FIX concentrates, novel nonfactor therapies, and gene therapy for severe and nonsevere hemophilia A and B.

Long-term prophylaxis with a von Willebrand factor (VWF) concentrate is recommended in patients with von Willebrand disease (VWD) who have a history of severe and frequent bleeds. However, data from prospective studies are scarce. WIL-31, a prospective, noncontrolled, international phase 3 trial, investigated the efficacy and safety of Wilate prophylaxis in severe patients with VWD. Male and female patients 6 years or older with VWD types 1, 2 (except 2N), or 3 who had completed a prospective, 6-month, on-demand, run-in study (WIL-29) were eligible to receive Wilate prophylaxis for 12 months. At baseline, patients (n = 33) had a median age of 18 years. Six (18%) patients had severe type 1, 5 (15%) had type 2, and 22 (67%) had type 3 VWD. The primary end point of a >50% reduction in mean total annualized bleeding rate (TABR) with Wilate prophylaxis vs prior on-demand treatment was met; mean TABR during prophylaxis was 5.2, representing an 84.4% reduction. The bleeding reduction was consistent across age, sex, and VWD types. The mean spontaneous ABR was 3.2, representing an 86.9% reduction vs on-demand treatment. During prophylaxis, 10 (30.3%) patients had 0 bleeding events and 15 (45.5%) patients had 0 spontaneous bleeding events. Of 173 BEs, 84.4% were minor and 69.9% treated. No serious adverse events related to study treatment and no thrombotic events were recorded. Overall, WIL-31 showed that Wilate prophylaxis was efficacious and well-tolerated in pediatric and adult patients with VWD of all types. The WIL-29 and WIL-31 trials were registered at www.ClinicalTrials.gov as #NCT04053699 and #NCT04052698, respectively.