Two-Year Outcomes of Valoctocogene Roxaparvovec Therapy for Hemophilia A.

BACKGROUND: Valoctocogene roxaparvovec delivers a B-domain-deleted factor VIII coding sequence with an adeno-associated virus vector to prevent bleeding in persons with severe hemophilia A. The findings of a phase 3 study of the efficacy and safety of valoctocogene roxaparvovec therapy evaluated after 52 weeks in men with severe hemophilia A have been published previously. METHODS: We conducted an open-label, single-group, multicenter, phase 3 trial in which 134 men with severe hemophilia A who were receiving factor VIII prophylaxis received a single infusion of 6×1013 vector genomes of valoctocogene roxaparvovec per kilogram of body weight. The primary end point was the change from baseline in the annualized rate of treated bleeding events at week 104 after receipt of the infusion. The pharmacokinetics of valoctocogene roxaparvovec were modeled to estimate the bleeding risk relative to the activity of transgene-derived factor VIII. RESULTS: At week 104, a total of 132 participants, including 112 with data that were prospectively collected at baseline, remained in the study. The mean annualized treated bleeding rate decreased by 84.5% from baseline (P<0.001) among the participants. From week 76 onward, the trajectory of the transgene-derived factor VIII activity showed first-order elimination kinetics; the model-estimated typical half-life of the transgene-derived factor VIII production system was 123 weeks (95% confidence interval, 84 to 232). The risk of joint bleeding was estimated among the trial participants; at a transgene-derived factor VIII level of 5 IU per deciliter measured with chromogenic assay, we expected that participants would have 1.0 episode of joint bleeding per year. At 2 years postinfusion, no new safety signals had emerged and no new serious adverse events related to treatment had occurred. CONCLUSIONS: The study data show the durability of factor VIII activity and bleeding reduction and the safety profile of valoctocogene roxaparvovec at least 2 years after the gene transfer. Models of the risk of joint bleeding suggest that the relationship between transgene-derived factor VIII activity and bleeding episodes is similar to that reported with the use of epidemiologic data for persons with mild-to-moderate hemophilia A. (Funded by BioMarin Pharmaceutical; GENEr8-1 ClinicalTrials.gov number, NCT03370913.).

Gene Therapy with Etranacogene Dezaparvovec for Hemophilia B.

BACKGROUND: Moderate-to-severe hemophilia B is treated with lifelong, continuous coagulation factor IX replacement to prevent bleeding. Gene therapy for hemophilia B aims to establish sustained factor IX activity, thereby protecting against bleeding without burdensome factor IX replacement. METHODS: In this open-label, phase 3 study, after a lead-in period (≥6 months) of factor IX prophylaxis, we administered one infusion of adeno-associated virus 5 (AAV5) vector expressing the Padua factor IX variant (etranacogene dezaparvovec; 2×1013 genome copies per kilogram of body weight) to 54 men with hemophilia B (factor IX activity ≤2% of the normal value) regardless of preexisting AAV5 neutralizing antibodies. The primary end point was the annualized bleeding rate, evaluated in a noninferiority analysis comparing the rate during months 7 through 18 after etranacogene dezaparvovec treatment with the rate during the lead-in period. Noninferiority of etranacogene dezaparvovec was defined as an upper limit of the two-sided 95% Wald confidence interval of the annualized bleeding rate ratio that was less than the noninferiority margin of 1.8. Superiority, additional efficacy measures, and safety were also assessed. RESULTS: The annualized bleeding rate decreased from 4.19 (95% confidence interval [CI], 3.22 to 5.45) during the lead-in period to 1.51 (95% CI, 0.81 to 2.82) during months 7 through 18 after treatment, for a rate ratio of 0.36 (95% Wald CI, 0.20 to 0.64; P<0.001), demonstrating noninferiority and superiority of etranacogene dezaparvovec as compared with factor IX prophylaxis. Factor IX activity had increased from baseline by a least-squares mean of 36.2 percentage points (95% CI, 31.4 to 41.0) at 6 months and 34.3 percentage points (95% CI, 29.5 to 39.1) at 18 months after treatment, and usage of factor IX concentrate decreased by a mean of 248,825 IU per year per participant in the post-treatment period (P<0.001 for all three comparisons). Benefits and safety were observed in participants with predose AAV5 neutralizing antibody titers of less than 700. No treatment-related serious adverse events occurred. CONCLUSIONS: Etranacogene dezaparvovec gene therapy was superior to prophylactic factor IX with respect to the annualized bleeding rate, and it had a favorable safety profile. (Funded by uniQure and CSL Behring; HOPE-B ClinicalTrials.gov number, NCT03569891.).

Valoctocogene Roxaparvovec Gene Therapy for Hemophilia A.

BACKGROUND: Valoctocogene roxaparvovec (AAV5-hFVIII-SQ) is an adeno-associated virus 5 (AAV5)-based gene-therapy vector containing a coagulation factor VIII complementary DNA driven by a liver-selective promoter. The efficacy and safety of the therapy were previously evaluated in men with severe hemophilia A in a phase 1-2 dose-escalation study. METHODS: We conducted an open-label, single-group, multicenter, phase 3 study to evaluate the efficacy and safety of valoctocogene roxaparvovec in men with severe hemophilia A, defined as a factor VIII level of 1 IU per deciliter or lower. Participants who were at least 18 years of age and did not have preexisting anti-AAV5 antibodies or a history of development of factor VIII inhibitors and who had been receiving prophylaxis with factor VIII concentrate received a single infusion of 6×1013 vector genomes of valoctocogene roxaparvovec per kilogram of body weight. The primary end point was the change from baseline in factor VIII activity (measured with a chromogenic substrate assay) during weeks 49 through 52 after infusion. Secondary end points included the change in annualized factor VIII concentrate use and bleeding rates. Safety was assessed as adverse events and laboratory test results. RESULTS: Overall, 134 participants received an infusion and completed more than 51 weeks of follow-up. Among the 132 human immunodeficiency virus-negative participants, the mean factor VIII activity level at weeks 49 through 52 had increased by 41.9 IU per deciliter (95% confidence interval [CI], 34.1 to 49.7; P<0.001; median change, 22.9 IU per deciliter; interquartile range, 10.9 to 61.3). Among the 112 participants enrolled from a prospective noninterventional study, the mean annualized rates of factor VIII concentrate use and treated bleeding after week 4 had decreased after infusion by 98.6% and 83.8%, respectively (P<0.001 for both comparisons). All the participants had at least one adverse event; 22 of 134 (16.4%) reported serious adverse events. Elevations in alanine aminotransferase levels occurred in 115 of 134 participants (85.8%) and were managed with immune suppressants. The other most common adverse events were headache (38.1%), nausea (37.3%), and elevations in aspartate aminotransferase levels (35.1%). No development of factor VIII inhibitors or thrombosis occurred in any of the participants. CONCLUSIONS: In patients with severe hemophilia A, valoctocogene roxaparvovec treatment provided endogenous factor VIII production and significantly reduced bleeding and factor VIII concentrate use relative to factor VIII prophylaxis. (Funded by BioMarin Pharmaceutical; GENEr8-1 ClinicalTrials.gov number, NCT03370913.).

BIVV001 Fusion Protein as Factor VIII Replacement Therapy for Hemophilia A.

BACKGROUND: Factor VIII replacement products have improved the care of patients with hemophilia A, but the short half-life of these products affects the patients' quality of life. The half-life of recombinant factor VIII ranges from 15 to 19 hours because of the von Willebrand factor chaperone effect. BIVV001 (rFVIIIFc-VWF-XTEN) is a novel fusion protein designed to overcome this half-life ceiling and maintain high sustained factor VIII activity levels. Data are lacking on the safety and pharmacokinetics of single-dose BIVV001. METHODS: In this phase 1-2a open-label trial, we consecutively assigned 16 previously treated men (18 to 65 years of age) with severe hemophilia A (factor VIII activity, <1%) to receive a single intravenous injection of recombinant factor VIII at a dose of 25 IU per kilogram of body weight (lower-dose group) or 65 IU per kilogram (higher-dose group). This injection was followed by a washout period of at least 3 days. The patients then received a single intravenous injection of BIVV001 at the same corresponding dose of either 25 IU or 65 IU per kilogram. Adverse events and pharmacokinetic measurements were assessed. RESULTS: No inhibitors to factor VIII were detected and no hypersensitivity or anaphylaxis events were reported up to 28 days after the injection of single-dose BIVV001. The geometric mean half-life of BIVV001 was three to four times as long as that of recombinant factor VIII (37.6 hours vs. 9.1 hours in the lower-dose group and 42.5 vs. 13.2 hours in the higher-dose group); the area under the curve (AUC) for product exposure was six to seven times as great in the two dose groups (4470 hours vs. 638 hours × IU per deciliter in the lower-dose group and 12,800 hours vs. 1960 hours × IU per deciliter in the higher-dose group). After the injection of BIVV001 in the higher-dose group, the mean factor VIII level was in the normal range (≥51%) for 4 days and 17% at day 7, which suggested the possibility of a weekly interval between treatments. CONCLUSIONS: In a small, early-phase study involving men with severe hemophilia A, a single intravenous injection of BIVV001 resulted in high sustained factor VIII activity levels, with a half-life that was up to four times the half-life associated with recombinant factor VIII, an increase that could signal a new class of factor VIII replacement therapy with a weekly treatment interval. No safety concerns were reported during the 28-day period after administration. (Funded by Sanofi and Sobi; ClinicalTrials.gov number, NCT03205163.).

Consistency of serial ultrasonographic joint tissue measurements by the Joint tissueActivity and Damage Exam (JADE) protocol in relation to hemophilic joint health parameters.

OBJECTIVES: The Joint tissueActivity and Damage Exam (JADE) is a point-of-care (POC) musculoskeletal ultrasound (MSKUS) protocol for non-radiologists to evaluate hemophilic arthopathy. Our aim was to determine the consistency of cross-sectional analyses of direct tissue measurements (JADE protocol) and clinical Hemophilia Joint Health Score [HJHS] and functional joint assessments (arc) at three clinic visits. METHODS: We prospectively studied adults (n = 44) with hemophilia (A or B) of any severity and arthropathy at 3 North American sites. We assessed HJHS, total arc, and JADE parameters (bilateral elbows, ankles, and knees) at study entry, at ≈12-18 months, and at ≈24-36 months, and used MSKUS to evaluate painful episodes between study visits. JADE measurements included osteochondral alterations, cartilage thickness, and soft tissue expansion at sentinel positions. Associations between joint HJHS and total arc with each JADE variable were examined with random intercept models. RESULTS: At each visit increasing HJHS and decreasing total arc were associated in the expected direction with increasing length of OAs and soft tissue expansion in all joints, and decreasing cartilage thickness in the knee. However, HJHS associations with cartilage thickness were U-shaped for elbow and ankle (i.e. cartilage thinning and thickening). Associations between total arc and cartilage thickness followed a similar curve. (Near) normal levels of both joint parameters (HJHS and total arc) were associated with normal ranges of cartilage thickness. JADE views were also helpful to detect hemarthrosis in association with joint pains. CONCLUSIONS: POC MSKUS applying direct tissue measurements using the JADE protocol provided reproducible cross-sectional associations with joint health outcomes on three visits. These findings advance protocol validation and enable iterative adaptations resulting in JADE protocol version 2.

Diabetes, hepatitis C and human immunodeficiency virus influence hypertension risk differently in cohorts of haemophilia patients, veterans and the general population.

INTRODUCTION: The reasons for the high prevalence of hypertension in persons with haemophilia (PWH) are poorly understood. AIM: To examine the roles of diabetes, Hepatitis C Virus (HCV) and Human Immunodeficiency Virus (HIV) in the etiology of hypertension for PWH. METHODS: Retrospective cross-sectional design. Adult PWH (n = 691) were divided into two groups: (A) free of diabetes, HCV and HIV; (B) with diabetes and/or HCV positivity and/or HIV positivity. Each group was matched by race and age with random samples from the general population of the US (National Health and Nutrition Examination Surveys, NHANES) and outpatients at the Veterans Affairs Medical Center (VAMC) in San Diego. Generalized additive models (GAMs) were fitted for graphical analysis of hypertension risk over the lifespan. RESULTS: In Group A, PWH had the highest prevalence of hypertension compared to NHANES and VAMC, especially in young adults. In Group B, diabetes increased the risk of hypertension for all three cohorts (PWH, NHANES and VAMC), especially for PWH. In PWH, hypertension risk was also increased by HIV, in NHANES by HCV, and in VAMC by HCV and HIV. CONCLUSION: Diabetes conferred the greatest risk of hypertension for all three cohorts. However, curves of hypertension in relation to age revealed that diabetes, HCV and HIV modulated hypertension risk differently in PWH. PWH experienced a disproportionally high risk increase with diabetes. Therefore, haemophilia care should include screening for hypertension and diabetes at a young age.

Blood pressure in persons with haemophilia with a focus on haemophilia-specific risk factors.

INTRODUCTION: Persons with haemophilia (PWH) have a higher prevalence of hypertension compared to the general population, which cannot be explained entirely by the usual cardiovascular risk factors. Neutralizing antibodies (inhibitors) against clotting factors might have some relation to cardiovascular disease in PWH. However, whether inhibitors facilitate hypertension is unknown. AIM: We investigated the relationship between hypertension/blood pressure and inhibitors in PWH. Additional goals were to determine the relationships with haemophilia type, race, and viral status. METHODS: Records were extracted retrospectively for PWH (age ≥18 years) between 2003 and 2014 from four Hemophilia Treatment Centers in North America and included demographics, weight, height, haemophilia type/severity, HCV and HIV infection status, hypertension, use of anti-hypertensive medications, and inhibitor status. We fitted semiparametric generalized additive models (GAMs) to describe adjusted curves of blood pressure (BP) against age. RESULTS: Among 691 PWH, 534 had haemophilia A and 157 had haemophilia B, with a median age of 39 years (range 18 to 79). Forty-four PWH (6.5%) had a history of inhibitors, without evidence for a higher prevalence of hypertension or higher BP. A higher prevalence of hypertension and higher BP were noted for haemophilia A (vs. haemophilia B), coinfection with HCV/HIV (vs. uninfected), or moderate haemophilia (vs. severe haemophilia). CONCLUSION: While there was no signal to suggest that a history of inhibitors is associated with hypertension, differences based on haemophilia type, severity, and viral infection status were identified, encouraging prospective investigations to better delineate haemophilia-specific risk factors for hypertension.

Risk of diabetes in haemophilia patients compared to clinic and non-clinic control cohorts.

INTRODUCTION: Ageing patients with haemophilia (PWH) develop cardiovascular risk factors impacting care. Little is known about the prevalence of diabetes in PWH and its relation to other comorbidities. AIM: To examine the risk of diabetes for adult PWH compared to men from the general United States population (National Health and Nutrition Examination Surveys [NHANES]) and outpatients attending a Veterans Affairs Medical Center (VAMC) clinic. METHODS: Retrospective cross-sectional design. PWH from four haemophilia centres (n = 690) were matched with random samples from NHANES and VAMC. Diabetes (yes/no) was the outcome, while age, body mass index (BMI), race and Hepatitis C (HCV; by serology) and human immunodeficiency virus (HIV) positivity were covariates. We fitted semiparametric generalized additive models (GAMs) in order to compare diabetes risk between cohorts. RESULTS: Younger PWH were at lower risk of diabetes than NHANES or VAMC subjects irrespective of BMI. However, the risk of diabetes rose in older PWH and was closely associated with HCV. For HCV-negative subjects, the risk of diabetes was considerably lower for PWH than NHANES and VAMC subjects. The difference persisted after controlling for BMI and age, indicating that the low risk of diabetes in PWH cannot be explained by lean body mass alone. CONCLUSION: Since many ageing PWH are HCV positive and therefore at heightened risk for diabetes, it is important to incorporate diabetes screening into care algorithms in Haemophilia Treatment Centers, especially since PWH are not always followed in primary care clinics.

Real-world data demonstrate improved bleed control and extended dosing intervals for patients with haemophilia B after switching to recombinant factor IX Fc fusion protein (rFIXFc) for up to 5 years.

INTRODUCTION: In clinical trials, recombinant factor IX fusion protein (rFIXFc) has demonstrated safety, efficacy and prolonged activity with extended dosing intervals for treatment of haemophilia B. AIM: To assess the real-world clinical utility of rFIXFc in a variable patient population and routine clinical practice. METHODS: A multicentre, retrospective chart review was conducted of patients with haemophilia B who had received rFIXFc prophylaxis or on-demand treatment for ≥6 months across six sites in the United States. RESULTS: Sixty-four eligible patients were identified who had a median (range) duration on rFIXFc of 2.7 (0.5-5.0) years. Of 32 patients on rFIXFc prophylaxis who switched from prophylaxis with another factor treatment (ie pre-rFIXFc) and had a known pre-rFIXFc dosing interval, the initial dosing interval was lengthened for 26 (81%) patients and maintained for the remaining 6 (19%) patients. Most (n = 48 [91%]) patients who received rFIXFc prophylaxis from the beginning to the end of the chart review period (n = 53) maintained or lengthened the dosing interval from first through last dose of rFIXFc. For patients receiving rFIXFc prophylaxis, there was an approximate 50% reduction in weekly factor consumption compared with pre-rFIXFc prophylaxis. Overall annualized bleed rates, annualized spontaneous bleed rates and annualized joint bleed rates decreased after switching to rFIXFc prophylaxis (n = 24 with bleed data). Compliance to recommended treatment improved or remained stable in most patients with available data (30/31). CONCLUSION: Recombinant factor IX fusion protein prophylaxis improved bleed control, reduced overall consumption, reduced frequency of infusion and improved compliance for patients with haemophilia B in a real-world setting.

Development and Reliability of the Joint Tissue Activity and Damage Examination for Quantitation of Structural Abnormalities by Musculoskeletal Ultrasound in Hemophilic Joints.

OBJECTIVES: Musculoskeletal ultrasound (US) is used increasingly to examine hemophilic arthropathy. However, quantitative algorithms to document findings are lacking. We developed and sought to validate a protocol quantifying hemophilic joint abnormalities. METHODS: Thirty-one patients with hemophilia were examined serially for 2 years with musculoskeletal US (≈600 joint examinations and ≈6000 images). Based on the spectrum of pathologies, a quantitative algorithm, named Joint Tissue Activity and Damage Examination (JADE), was developed for soft tissue and osteochondral measurements, including power Doppler, using nominal group techniques. To study intra- and inter-rater reliability, 8 musculoskeletal US-experienced hemophilia providers performed anatomic landmark recognition and tissue measurements on 86 images with arthropathic changes, with repetition 1 month later. Twenty-three musculoskeletal US-inexperienced providers performed similar assessments. Inter-operator reliability was established by 6 musculoskeletal US-experienced hemophilia providers, each acquiring images and JADE assessments of 3 hemophilic arthropathic joints. A radiologist and musculoskeletal sonographer functioned as adjudicators. The statistical analysis was performed with the intraclass correlation coefficient (ICC), Fleiss κ, and Cohen κ where appropriate. RESULTS: The musculoskeletal US-experienced providers showed excellent intra-and inter-rater reliability for tissue measurements (ICCs, 0.94-0.96). Agreement was good to excellent for landmark recognition (Fleiss κ, 0.87-0.94). Inter-operator reliability was excellent for measurements and landmark recognition (ICC, 0.90; Fleiss κ, 1.0). Agreement with adjudicators was mostly good to excellent. Musculoskeletal US-inexperienced providers showed excellent inter-rater reliability for measurements (ICC, 0.96) and moderate agreement for landmark recognition (Fleiss κ, 0.58). CONCLUSIONS: The JADE protocol appears feasible for quantifying hemophilic intra-articular abnormalities. Musculoskeletal US-trained hemophilia providers showed high intra-rater, inter-rater, and inter-operator reliability, supporting JADE as a protocol for clinical management and research.