-Author name in bold denotes the presenting author
-Asterisk * with author name denotes a Non-ASH member
Clinically Relevant Abstract denotes an abstract that is clinically relevant.

PhD Trainee denotes that this is a recommended PHD Trainee Session.

Ticketed Session denotes that this is a ticketed session.

3184 Immunogenicity, Efficacy and Safety of Rurioctocog Alfa Pegol in Previously Untreated Patients with Severe Hemophilia a: Interim Results from an Open-Label Multicenter Clinical TrialClinically Relevant Abstract

Program: Oral and Poster Abstracts
Session: 322. Disorders of Coagulation or Fibrinolysis: Clinical and Epidemiological: Poster III
Hematology Disease Topics & Pathways:
Bleeding and Clotting, Clinical Trials, Hemophilia, Clinical Research, Diseases, Pediatric, Study Population
Monday, December 13, 2021, 6:00 PM-8:00 PM

Robert F. Sidonio Jr., MD, MSc1, Christine Knoll2, Flora Peyvandi3,4*, Oleksandra Stasyshyn, MD, PhD5*, Ali Bulent Antmen6*, Seoh Leng Yeoh7*, Darintr Sosothikul8*, Caterina Maggiore9*, Werner Engl10*, Geoffrey Allen11* and Srilatha Tangada11

1Aflac Cancer and Blood Disorders Center, Emory University, Atlanta, GA
2Phoenix Children's Hospital, Phoenix, AZ
3Angelo Bianchi Bonomi Hemophilia and Thrombosis Centre, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
4Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy
5Academy of Medical Sciences of Ukraine, Lviv, Ukraine
6Acibadem Adana Hospital, Adana, Turkey
7Department of Pediatrics, Hospital Pulau Pinang, Penang, Malaysia
8Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
9IQVIA, Milan, Italy
10Baxalta Innovations GmbH, a Takeda company, Vienna, Austria
11Takeda Development Center Americas, Inc., Cambridge, MA

Background

Management of severe hemophilia A includes on-demand treatment or prophylaxis with replacement factor VIII (FVIII) concentrate. FVIII inhibitors can develop following exposure to exogenous FVIII in approximately 30% of previously untreated patients (PUPs), typically in the first 50 exposure days (EDs), with serious complications. This is the first study evaluating the safety, immunogenicity, and hemostatic efficacy of rurioctocog alfa pegol (Adynovate®; Baxalta US Inc., a Takeda company, Lexington, MA, USA), an extended half-life (EHL) recombinant FVIII, in PUPs with severe hemophilia A.

Methods

This prospective, open-label, multi-center, phase 3 study (NCT02615691) was conducted in patients ˂6 years of age with severe hemophilia A (FVIII <1%). Patients were previously untreated, or had <3 EDs to rurioctocog alfa pegol, octocog alfa, or plasma transfusion at any time prior to screening. Patients with detectable FVIII inhibitory antibodies at screening or a history of FVIII inhibitory antibodies prior to screening (≥0.6 Bethesda units) were not eligible. Patients received intravenous rurioctocog alfa pegol as prophylaxis (25-50 IU/kg, up to 80 IU/kg ≥1 × weekly) and/or on-demand therapy (10-50 IU/kg, up to 80 IU/kg depending on bleed severity). Prophylaxis was started before 3 years of age or after a maximum of 2 joint bleeds, whichever occurred first. The primary endpoint was the incidence of FVIII inhibitor development. Secondary endpoints included safety and efficacy (annualized bleeding rate [ABR] and hemostatic efficacy). This protocol-specified interim analysis was conducted after 50 patients had completed ≥50 EDs without developing an inhibitor to FVIII or had developed a confirmed FVIII inhibitor at any time. The data cut-off was 30 August 2019. Demographic and baseline characteristics were summarized using continuous and categorical data. The incidence of FVIII inhibitor development was calculated using the Clopper Pearson exact 95% CI computed for the proportion of patients who developed FVIII inhibitors during the study. ABR was analyzed by point and interval estimates derived from a negative binomial model with treatment regimen as a covariate. The number and percentage of patients reporting adverse events (AEs) and serious AEs (SAEs) was recorded for all patients receiving rurioctocog alfa pegol. Informed consent and ethics approval were obtained.

Results

As of the data cut-off, 59 (73.8%) of 80 enrolled patients had received ≥1 dose of rurioctocog alfa pegol; 18 patients (screen failures) did not meet the eligibility criteria and 4 discontinued prior to treatment. 54 patients received prophylaxis and 35 received on-demand treatment at any time during the study period. The mean (SD) patient age at baseline was 11.8 (8.2) months. The number of patients with 0 EDs prior to screening was 36 (61.0%), with 9 (15.3%) patients having 1 ED and 14 (23.7%) having 2 EDs. Overall, 32 patients had a family history of hemophilia A. A large deletion, intron 1 or intron 22 inversion, or substitution nonsense hemophilia gene mutation was present in 29 (49.2%) patients and 21 (35.6%) had either a small deletion, small duplication, or substitution missense gene mutation. Of the 52 patients who qualified for this interim analysis, 10 developed an inhibitory antibody to rurioctocog alfa pegol during the study; the incidence of inhibitor development was 0.192 (95% CI, 0.096-0.325) (10/52). Rurioctocog alfa pegol exposure data and ABRs for patients receiving prophylaxis or on-demand treatment are presented in Table 1. At bleed resolution, hemostatic efficacy was rated by patients as “excellent” for 88/269 bleeds (32.7%) and “good” for 73/269 bleeds (27.1%). Overall, 52 (88.1%) patients receiving rurioctocog alfa pegol experienced a total of 283 AEs, and 13 patients experienced 14 rurioctocog alfa pegol-related AEs (including 10 SAEs). SAEs occurred in 24 patients, 10 of whom experienced 10 treatment-related SAEs of FVIII inhibitor development.

Discussion

This is the first prospective study of the EHL recombinant FVIII rurioctocog alfa pegol for the treatment of PUPs with severe hemophilia A. These preliminary results demonstrate a relatively low inhibitor rate compared with other EHL recombinant FVIII products and a safety and efficacy profile consistent with that previously observed for rurioctocog alfa pegol in the treatment of bleeding episodes in patients with hemophilia A.

Disclosures: Sidonio: Takeda: Consultancy, Research Funding; Pfizer: Consultancy; Novo Nordisk: Consultancy; Octapharma: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Catalyst: Consultancy; Biomarin: Consultancy; Bayer: Consultancy; Guardian Therapeutics: Consultancy. Peyvandi: Takeda: Honoraria; Spark: Honoraria; Sobi: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Roche: Honoraria; Bioverativ: Honoraria; Grifols: Honoraria. Stasyshyn: Grifols: Consultancy, Speakers Bureau; Novo Nordisk: Consultancy, Research Funding, Speakers Bureau; Octapharma: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy, Research Funding, Speakers Bureau; Takeda: Consultancy, Research Funding, Speakers Bureau; Shire: Consultancy, Honoraria, Research Funding; Institute of Blood Pathology and Transfusion Medicine of National Academy of Medical Sciences of Ukraine: Current Employment; CSL Behring: Consultancy, Honoraria, Research Funding, Speakers Bureau; Sanofi: Honoraria, Research Funding; Roche: Speakers Bureau; LFB: Honoraria, Research Funding. Antmen: Takeda: Consultancy; Pfizer: Consultancy; Roche: Consultancy; Novo Nordisk: Consultancy. Yeoh: Takeda: Honoraria; Pfizer: Honoraria; Roche: Honoraria; Grifols: Honoraria. Maggiore: IQVIA: Current Employment. Engl: Baxalta Innovations GmbH, a Takeda company: Current Employment; Takeda: Current equity holder in publicly-traded company. Allen: Takeda Development Center Americas, Inc.: Current Employment; Takeda: Current equity holder in publicly-traded company. Tangada: Takeda: Current equity holder in publicly-traded company; Takeda Development Center Americas, Inc: Current Employment.

*signifies non-member of ASH