Pharmacokinetics of Efmoroctocog alfa by Two-Compartment Model Highlights Hemophilia A Patients with Biphasic Decay, Long Mean Residence Time, and Beta Half-Life.

Background/Objectives: A compartmental pharmacokinetics (PK) analysis of new extended half-life FVIII concentrates has never been performed in a large cohort of hemophilia patients. An improved PK analysis of individual outcomes may help to tailor hemophilia replacement treatment. Methods: PK outcomes after the infusion of a standard single dose of Efmoroctocog alfa were collected from 173 patients with severe/moderately severe hemophilia A in 11 Italian hemophilia centers. Factor VIII clotting activity (FVIII:C) was measured by one-stage clotting assay (OSA) in all patients, and chromogenic substrate assay (CSA) in a subgroup (n = 52). Fifty patients underwent a comparative PK assessment with standard half-life (SHL) recombinant FVIII (rFVIII) products. Non-compartmental analysis (NCA), one compartment model (OCM), and TCM were used to analyze the decay curves of all patients, and one-way paired ANOVA to compare the PK outcomes. Results: All 173 PKs conformed to the NCA and OCM, but only 106 (61%) conformed to the TCM based on the biphasic features of their decay curves. According to the TCM, the Beta HL and MRT of rFVIIIFc were 20.42 ± 7.73 and 25.64 ± 7.61 h, respectively. ANOVA analysis of the outcomes from the three PK models showed significant differences in clearance, half-life (HL), and mean residence time (MRT) (p < 0.001 for all parameters). As anticipated, the HL and MRT of rFVIIIFc were longer than those of SHL rFVIII. Comparing OSA with CSA outcomes, Cmax resulted higher when measured by CSA (p = 0.05) and, according to TCM, Beta HL resulted longer when measured by OSA (p = 0.03). FVIII:C trough levels obtained with SHL concentrates were significantly lower than those obtained with rFVIIIFc at each post-infusion time point. Conclusions: In a large group of hemophilia A (HA) patients, three different PK models confirmed the improved pharmacokinetic (PK) characteristics of rFVIIIFc, compared with standard half-life rFVIII concentrates. The TCM only fits two-thirds of the PKs, highlighting their biphasic decay and a long Beta half-life. In these patients, the TCM would be preferable to properly evaluate individual PK features.

Invasive procedures and surgery following etranacogene dezaparvovec gene therapy in people with haemophilia B.

BACKGROUND: Little information regarding the management of invasive procedures in people with haemophilia B (HB) after undergoing gene therapy is available. Here, we report the management of invasive procedures in people with severe or moderately severe HB who had previously been treated with etranacogene dezaparvovec in the Phase 2b and Phase 3 HOPE-B clinical trials (NCT03489291, NCT03569891). METHODS: This retrospective analysis included invasive procedures performed within 3 and 2 years following a single infusion of 2x1013 gc/kg of etranacogene dezaparvovec in participants in the Phase 2b and HOPE-B trials, respectively. Data for FIX dosing, duration of postoperative FIX use, FIX activity prior to invasive procedures, and postoperative bleeds were collected and analysed. RESULTS: The analysis included 64 procedures in 29 participants: nine major surgeries, 24 minor surgeries, 11 endoscopies, three endoscopies with biopsy/polypectomy, and 17 dental procedures. Uncontaminated endogenous FIX activity corresponded to mild haemophilia or normal levels prior to 98% of all procedures, with a median endogenous FIX activity of 43.8 IU/dL (range 3.1-113 IU/dL). All major surgeries were managed with exogenous FIX, 67% with ≤4 days of FIX infusion. Most minor surgeries (88%), endoscopies (82%), and dental procedures (94%) were managed with no or a single FIX infusion. Postoperative bleeds occurred after one minor surgery and four dental procedures. There were no symptomatic thrombotic events or FIX inhibitor developments. CONCLUSION: Etranacogene dezaparvovec has the potential to facilitate perioperative management in people with HB by reducing the need for perioperative exogenous FIX and its associated risks.

Liver-related aspects of valoctocogene roxaparvovec gene therapy for hemophilia A: expert guidance for clinical practice.

Adeno-associated virus (AAV)-based gene therapy (valoctocogene roxaparvovec) is an attractive treatment for hemophilia A. Careful clinical management is required to minimize the risk of hepatotoxicity, including assessment of baseline liver condition to determine treatment eligibility and monitoring liver function after gene therapy. This article describes recommendations (developed by a group of hemophilia experts) on hepatic function monitoring before and after gene therapy. To prevent harmful liver-related effects, gene therapy is contraindicated in patients with uncontrolled liver infections, autoimmune hepatitis, liver stiffness ≥8 kPa or cirrhosis. Before using gene therapy in patients with liver steatosis or other liver disorders, the risk of liver damage should be considered using a highly individualized approach. Treatment is not recommended in patients with abnormal liver enzymes, including alanine aminotransferase (ALT) at any level above the upper limit of normal (ULN). Therefore, pre-treatment assessment of liver health should include laboratory tests, abdominal ultrasound and liver stiffness measurements by transient elastography (TE). In the first year after therapy, ALT levels should be monitored 1-2 times/week to detect elevations ≥1.5 × ULN, which may require immunosuppressant therapy. Patients with ALT elevation should receive prednisone 60 mg/day for 2 weeks, followed by stepwise tapering when ALT returns to baseline. ALT monitoring should continue long-term (every 3-6 months), along with abdominal ultrasound (every 6 months) and TE (yearly) evaluations. When patients with good liver health are selected for treatment and closely monitored thereafter, ALT elevations can be promptly treated and are expected to resolve without long-term hepatic sequelae.

Pharmacokinetic model-based assessment of factor IX prophylaxis treatment regimens in severe hemophilia B.

An important aspect of improving care for people with hemophilia B (HB) is developing optimal treatment strategies. Here we aimed to provide in-silico evidence, comparing the estimated optimal posology of factor IX (FIX) products to support the patient-physician decision-making process. A population pharmacokinetic (popPK) model-based assessment comparing the performance of FIX products (rFIX, rIX-FP, rFIXFc, N9-GP) was developed. PopPK analyses were used to determine a product's optimal posology to target predefined steady-state FIX activity trough levels in a hypothetical population of 10,000 people with severe HB. Model-derived optimal posologies were compared across several parameters including trough levels, proportion of patients per regimen and consumption, considering 64 hypothetical patient scenarios of different FIX trough level targets and ages. Results indicated a marked difference between FIX products estimated to achieve target trough levels, consumption and dosing frequencies. rIX-FP was associated with higher trough levels than rFIX and rFIXFc, at a lower weekly dose and administration frequency, across all age groups. N9-GP use in adolescents and adults was associated with lower consumption compared with rIX-FP. Insights from this study may be utilized by clinicians to inform decision-making, by considering the model-generated estimated optimal posologies alongside multiple clinical factors and patient preferences.

Concizumab prophylaxis in persons with hemophilia A or B with inhibitors: patient-reported outcome results from the phase 3 explorer7 study.

Background: Patient-reported outcomes (PROs) reflect patient perceptions of disease and treatment and are important for evaluating new therapies. Objectives: Evaluate the effects of once-daily concizumab prophylaxis on health-related quality of life (HRQoL), treatment burden, and treatment preference in males aged ≥12 years with hemophilia A/B with inhibitors. Methods: Patients enrolled in the multicenter, open-label explorer7 phase 3 study (ClinicalTrials.gov identifier: NCT04083781) were randomized to receive no prophylaxis (arm 1) or concizumab prophylaxis (arm 2) or were nonrandomly allocated to concizumab prophylaxis (arms 3 and 4). The study included questionnaires to assess patients' perception of HRQoL (Haemophilia Quality of Life Questionnaire for Adults), treatment burden (Hemophilia Treatment Experience Measure), and treatment preference (Haemophilia Patient Preference Questionnaire). Results: The estimated treatment difference between patients receiving concizumab prophylaxis vs no prophylaxis at week 24 for Haemophilia Quality of Life Questionnaire for Adults "total score" was -22.6 points (95% CI, -42.5; -2.7), directionally favoring patients receiving concizumab prophylaxis. For Hemophilia Treatment Experience Measure "total score," the estimated treatment difference was -19.9 points (95% CI, -34.3, -5.6) in favor of concizumab vs no prophylaxis. The majority of patients receiving concizumab expressed a preference for concizumab over their previous treatment, the main reasons being "fewer bleeds," "require less time," and "less painful to inject." Across all PROs, there were less responses collected than anticipated, limiting interpretations. Conclusion: PROs collected during the explorer7 study showed improvements in some domains of HRQoL, treatment burden, and patient treatment preference in persons with hemophilia A or B with inhibitors receiving concizumab prophylaxis compared with no prophylaxis.

Gene therapy for people with hemophilia B: a proposed care delivery model in Italy.

BACKGROUND: Gene therapy is designed to provide people with hemophilia B with a steady and elevated factor (F)IX activity, thereby strengthening protection and relieving the burden of frequent replacement therapy infusions. The European Medicines Agency has approved gene therapy for the severe and moderately severe forms of hemophilia B that uses the FIX-Padua variant (etranacogene dezaparvovec). OBJECTIVES: The aim was to provide a document dedicated to hemophilia B gene therapy and give a comprehensive overview of the topic. METHODS: An Italian group of experts in hemophilia carried out a narrative review of the literature and discussed during a virtual meeting several key aspects of the delivery of this treatment in Italy. The discussion covered the organizational model, the role of the multidisciplinary team, the laboratory surveillance, and the patient's journey, from the follow-up to the identification of safety issues and outcome measures. RESULTS: This article highlights the need to follow the Hub and Spoke organizational model and sheds light on the role of each professional figure within the multidisciplinary teams to favor patient engagement, management, and retention. Moreover, this article stresses the need to perform laboratory tests for patient screening and follow-up and proposes a checklist to help patient identification. Finally, the needs of Italian hemophilia centers have been considered to ensure an efficient implementation of the care delivery model. CONCLUSION: It is crucial to ensure that centers are appropriately organized, equipped, and trained to adequately select patients, deliver the gene therapy, and perform follow-up.

Physical Activity, Bleedings and Quality of Life in Subjects with Haemophilia A without Inhibitors-A Multicenter, Observational Italian Study with a Wearable Device.

Background: This study aimed to gather data on physical activity (PA), bleeding, health-related quality of life, and health status, using a wearable device and an electronic patient-reported outcome (ePRO) app, in individuals with moderate or severe hemophilia A (HA) without inhibitors receiving treatment according to the clinical practice. Methods: This is a 12-month multicenter cohort study conducted in Italy. The primary outcomes included the description of PA by type and intensity, adherence to World Health Organization guidelines, bleeding, and health-related quality of life by EQ-5D questionnaire. PA data were collected continuously through a fitness tracker worn by the patient; all the other variables were collected through ePRO questionnaires. Results: Only 54 of the 103 enrolled subjects (52.4%) used their fitness tracker for the defined valid period; adolescents were the least compliant age group. PA was performed at low rates and intensity. Approximately 52% of the subjects had sedentary behavior. The mean EQ-5D values did not change over time. At least one bleeding was reported in 43.7% of the subjects, mostly with sedentary behavior. The PA in the 2 days preceding the bleeding was comparable to the one observed in the overall observational period. Conclusions: The systematic recording of data through a fitness tracker and ePRO app shows that subjects with HA without inhibitors have lower-than-expected PA and that they still experience issues related to bleeding.

Exposure-Response Relationship between VWF/FVIII Activity and Spontaneous Bleeding Events Following Recombinant VWF Prophylaxis in Severe VWD.

Background Recombinant von Willebrand factor (rVWF, vonicog alfa, Takeda Pharmaceuticals USA) is indicated in adults diagnosed with von Willebrand disease (VWD). In this study, the exposure-response (ER) relationship between VWF activity (VWF:RCo) or factor VIII activity (FVIII:C) and spontaneous bleeding events (BEs) was evaluated in adults with severe VWD receiving rVWF prophylaxis for up to 1 year. Methods This secondary analysis included 23 patients receiving rVWF prophylaxis in the open-label, phase 3 prophylaxis trial (NCT02973087). Population pharmacokinetic (PK) and PK/pharmacodynamic (PD) models were used to characterize VWF activity and endogenous FVIII:C, and PK/PD simulations were linked to spontaneous BEs to develop an ER model. Results None of the five patients with VWD types 1 or 2A/B experienced spontaneous BEs. Five of 18 patients with VWD type 3 experienced ≥1 spontaneous BEs. An ER relationship was observed whereby higher VWF:RCo levels were associated with a numerically lower spontaneous BE risk ( p < 0.10). This relationship was independent of patients' pretrial VWF treatment. A statistically significant ER relationship was observed after accounting for relevant data (average ± standard error exposure estimate for VWF:RCo over 24 hours prior to the spontaneous BE: -0.043 ± 0.021, p = 0.041). The model-generated hazard ratio for a 10 IU/dL increment in the average exposure of VWF:RCo 24 hours before a spontaneous BE was 0.651 (95% confidence interval: 0.431-0.982). Conclusions This ER analysis suggests a causal association between VWF:RCo and spontaneous BEs, with an increase of VWF:RCo exposure leading to a decrease in spontaneous BE risk.

Outcome measures in hemophilia: current and future perspectives.

INTRODUCTION: Hemophilia can detrimentally affect patients' quality of life and likelihood of survival. In the evolving landscape of therapies, the therapeutic gain of each treatment must be understood to accurately position it in the therapeutic armamentarium. Accordingly, appropriate outcomes must be measured with appropriate tools. AREAS COVERED: Our narrative review (PubMed search for 'hemophilia AND outcome' until June 2023), provides a compendium of outcome measures used in hemophilia clinical research. To define each outcome measure's relative value and applicability, several characteristics are critically discussed. EXPERT OPINION: Bleeding assessment, first annual/annualized bleeding rate, remains central in evaluating the efficacy and safety of hemophilia treatments. As modern therapies improve clinical outcomes toward zero bleeding events, this endpoint may become less sensitive to detect differences between therapeutic approaches. Technological advancements necessitate the adaptation of outcome measures to address infrequent bleeding events, age-related comorbidities, and laboratory parameters with limited comparability after different treatments. Considerable effort has been dedicated to the development of tools that comprehensively assess coagulation, such as thrombin generation assays. Patient-reported outcome measures are gaining importance although limited by their subjectivity. A definitive set of research outcome measures remains elusive. Outcomes may need to be tailored to different therapeutic interventions.

Gene Therapy for Hemophilia B: Achievements, Open Issues, and Perspectives.

Hemophilia B is the first bleeding disorder for which gene therapy clinical programs began. Presently, adenovirus-associated vectors represent the best means to deliver the transgene, and their administration by intravenous route has been used in recent clinical trials. The natural occurring factor IX (FIX) Padua variant, which allows for a 5- to 8-fold higher activity of FIX, while maintaining a normal protein concentration, was subsequently used to enhance the level of transgene expression. All the recent trials using this variant showed good results, and accumulating data suggest that long-term expression durability could be maintained at a significant hemostatic level. However, the risk of loss of transgene expression associated to immune response with liver enzymes elevation remains a concern, especially as to the efficacy and duration of immunosuppressive treatment. Notwithstanding this limitation, the results of clinical trials suggest that gene therapy in hemophilia B has the potential to provide long-term benefits with sustained factor activity levels predicted to last several years in many patients.

Major Orthopaedic Surgery in Persons with Haemophilia A with and without Inhibitors Treated by Emicizumab: A Mid-Term, Large, and Successful Series at a Single Center.

Introduction: Patients with Haemophilia (PWH) need orthopaedic treatments and often they undergo surgery. Classically, PWH with inhibitors have to face such procedures earlier than other patients. Major orthopaedic surgery is not easy and complications are frequent. Emicizumab is the first monoclonal antibody introduced for haematological prophylaxis for PWH with inhibitors, achieving an efficacious haemostasis also in patients with severe haemophilia A with inhibitors, later demonstrated for PWH without inhibitors. A few years ago, emicizumab was also proposed for PWH undergoing surgery, as it supports excellent bleeding control. The literature on orthopaedic surgery using an emicizumab protocol is scarce: only isolated case reports with short-term follow-ups are available. Aim: The purpose of this study is the assessment of the mid-term outcomes of major orthopaedic surgery performed in a population of patients with and without inhibitors and an emicizumab regimen. Methods: We reviewed the records of 13 PWH (eight with high-titre inhibitors, five without) with a mean age of 54.6 years, undergoing 15 orthopaedic surgical procedures between 2017 and 2022: primary knee and hip arthroplasty, revision, pseudotumor excision, or amputation. Their prophylaxis consisted of the combination of emicizumab and boluses of rFVIIa (PWH with inhibitors) or rFVIII (PWH without inhibitors). The clinical parameters of evaluation were: VAS, Haemophilic Joint Health Score (HJHS), and standard radiologic studies. Follow-up was conducted at 1, 3, 6 months, and then yearly. The survival rate of all implants was also assessed. Results: The mean follow-up was 38.8 months (range: 12-65). All patients were successfully treated without complications during surgery. During the postoperative period, a patient affected by a septic complication two months after his pseudotumor excision underwent an above-the-knee amputation. All patients were regularly discharged to the rehabilitative ward, reporting satisfaction for pain reduction and improved joint and global function at the VAS and HJHS scores. No revisions or implant failures were recorded. Conclusions: A prophylaxis regimen with emicizumab and factor replacement in PWH with or without inhibitors undergoing major orthopaedic surgery ensures effective bleeding control and good postoperative clinical outcomes at mid-term follow-up, and may be routinely adopted in dedicated high-volume hospitals. This series is the most consistent to date reported at a single Haemophilia centre.

Long-term outcomes with emicizumab in hemophilia A without inhibitors: results from the HAVEN 3 and 4 studies.

Background: Emicizumab, a bispecific monoclonal antibody, bridges activated factor (F) IX and FX, mimicking the function of missing or deficient activated FVIII in people with hemophilia A (HA). Objectives: To evaluate the long-term efficacy and safety of emicizumab prophylaxis in people with HA without FVIII inhibitors in the HAVEN 3 and 4 studies. Methods: HAVEN 3 and 4 were phase 3 open-label studies. Participants received emicizumab maintenance doses of 1.5 mg/kg every week or 3 mg/kg every 2 weeks (HAVEN 3), or 6 mg/kg every 4 weeks (HAVEN 4). Long-term efficacy and safety were assessed. Results: A total of 151 and 40 individuals without FVIII inhibitors received emicizumab in HAVEN 3 and 4, respectively. At the last patient, last visit dates (May 12, 2022 [HAVEN 3] and June 29, 2022 [HAVEN 4]), the median (range) duration of emicizumab exposure across the 2 studies was 248.1 (6.1-287.1) weeks. The mean (95% CI) annualized bleed rate for treated bleeds was 2.0 (0.23-7.15) for weeks 1 to 24, decreasing to 0.9 (0.01-5.28) by weeks 217 to 240. Overall, 188 (98.4%) participants experienced ≥1 adverse event (AE), with 185 treatment-related AEs in 71 (37.2%) participants. Forty-four (23.0%) participants reported a serious AE. Two thromboembolic events were reported, which were deemed unrelated to emicizumab by the investigator. No thrombotic microangiopathies were reported. Conclusion: With nearly 5 years of emicizumab exposure across the HAVEN 3 and 4 studies in people with HA without inhibitors, these data indicate continued bleed control with no new safety signals observed during long-term follow-up.

Next-generation strategies to improve safety and efficacy of adeno-associated virus-based gene therapy for hemophilia: lessons from clinical trials in other gene therapies.

Three major directions for the global progress of adeno-associated virus (AAV) vectors for gene therapies (GT) are analyzed: a) engineering vectors to increase transgene expression; b) aligning interests of the health system with costs and challenges for pharmaceutical industry; c) refining patient eligibility criteria, and endpoints definition. Currently employed AAV vectors may cause toxicity and adverse events. Furthermore, studies in animals do not fully predict risks and clinical benefits of AAV-based GT, and animal models reflecting the heterogeneity of certain clinical settings (e.g., congestive heart failure) are poorly available for improving AAV-based GT. Finally, antisense and gene editing approaches will soon complement gene augmentation strategies for the stable solution of unsolved issues of AAV-based GT. While minimizing toxicity, next-generation AAV vectors should decrease the viral load needed to achieve therapeutic efficacy; be functional in a restricted cellular subset; avoid transgene expression in unwanted cells (e.g., hepatocytes), and escape immune oversight in AAV-based GT. The role of stress-induced apoptosis in the loss of transgene expression in GT should be also explored. Aligning interests and obligations of pharmaceutical industry with those of the health system is critical for AAV-based GT success. Costs and challenges for pharmaceutical industry include a) removing impurities from AAV; b) validating tests to measure treatment efficacy, c) promoting training programs to standardize vector genomes delivery, d) collecting long-term follow-up data, and e) maintaining sustainability and cost-effectiveness of AAV-based GT. In rare disorders with small patient numbers (e.g., hemophilia), clearcut outcomes are mandatory as endpoints of unequivocal efficacy data.

Outcomes and outcome measures.

INTRODUCTION: Advances in haemophilia treatment have resulted in a near-normal life expectancy, lower burden of bleeding and treatment, and improved quality of life in high-income countries. Bleeding rate is approaching zero and novel parameters should be evaluated to assess the efficacy of treatment not only from the clinical point of view by using new methodologies (e.g. joint health assessment), but also from the patient's perspective (e.g. pain, quality of life, treatment satisfaction). METHODS AND RESULTS: This approach should be aimed at combining objective clinical methodologies and patient-reported outcomes (PROs). However, some instruments used for assessing PROs are still suboptimal and not properly validated. Recent evidence suggests that these tools can take advantage from a more personalized designed approach and could be effectively improved and serve to facilitate the patient's self-evaluation. For other congenital bleeding disorders (BDs), a set of patient-relevant outcomes has been also defined that overlap substantially those of haemophilia, including bleeding, side effects and complications, and PROs, such as pain, physical functioning, impact on daily life including school and work and mental health. There is a growing focus on addressing women-specific outcomes in BDs, reflecting an increased awareness of the unique challenges faced by women in this context. However, the development of tailored tools is imperative to further advance the progress in managing women with BDs, ensuring more accurate monitoring and personalized care. CONCLUSIONS: How incorporating these outcome measures in the process of approval of novel treatments for these disorders by regulatory authorities remains to be established.

The value-based healthcare approach to haemophilia: Development of outcome measures for the evaluation of care of people with haemophilia.

INTRODUCTION: Considering the advances in haemophilia management and treatment observed in the last decades, a new set of value-based outcome indicators is needed to assess the quality of care and the impact of these medical innovations. AIM: The Value-Based Healthcare in Haemophilia project aimed to define a set of clinical outcome indicators (COIs) and patient-reported outcome indicators (PROIs) to assess quality of care in haemophilia in high-income countries with a value-based approach to inform and guide the decision-making process. METHODS: A Value-based healthcare approach based on the available literature, current guidelines and the involvement of a multidisciplinary group of experts was applied to generate a set of indicators to assess the quality of care of haemophilia. RESULTS: A final list of three COIs and five PROIs was created and validated. The identified COIs focus on two domains: musculoskeletal health and function, and safety. The identified PROIs cover five domains: bleeding frequency, pain, mobility and physical activities, Health-Related Quality of Life and satisfaction. Finally, two composite outcomes, one based on COIs, and one based on PROIs, were proposed as synthetic outcome indicators of quality of care. CONCLUSION: The presented standard set of health outcome indicators provides the basis for harmonised longitudinal and cross-sectional monitoring and comparison. The implementation of this value-based approach would enable a more robust assessment of quality of care in haemophilia, within a framework of continuous treatment improvements with potential added value for patients. Moreover, proposed COIs and PROIs should be reviewed and updated routinely.