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CME Evaluation

Oral Communication Session

Inherited Bleeding Disorders and Inhibitors

Session: Novel hemophilia treatment, clinical trials II

OC 50.2 - Long-term outcomes with efanesoctocog alfa prophylaxis for previously treated children with severe hemophilia A, an interim analysis of the phase 3 XTEND-ed study

Tuesday, June 25, 2024
09:45 – 10:00 ICT
Room: Plenary Hall

    Co-Author(s)

  • Lynn Malec

    Senior Medical Director
    Versiti Blood Research Institute, Milwaukee, WI, USA
    Milwaukee, Wisconsin, United States

  • BN

    Beatrice Nolan

    Clinical Senior Lecturer
    Children's Health Ireland at Crumlin, Dublin, Republic of Ireland
    Dublin, Dublin, Ireland

  • Anthony KC Chan, MBBS

    Professor
    McMaster Children’s Hospital, McMaster University, Hamilton, Canada
    Hamilton, Ontario, Canada

    • Presenting Author(s)

  • MA

    Manuela Albisetti

    Professor
    University Children's Hospital Zurich, Zurich, Switzerland
    Zurich, Zurich, Switzerland

    • Co-Author(s)

  • Sheng-Chieh Chou, MD.

    Hematologist
    Department of Internal Medicine, National Taiwan University Hospital
    Taipei, Taipei, Taiwan (Republic of China)

  • Bulent Zulfikar

    Professor
    Department of Pediatric Hematology, Istanbul University Oncology Institute, Inherited Bleeding Disorders Center, Istanbul, Turkey
    Istanbul, Istanbul, Turkey

  • MS

    Mindy Simpson

    Medical Director
    Rush Hemophilia and Thrombophilia Center, Rush University Medical Center, Chicago, IL, USA
    Chicago, Illinois, United States

  • LF

    Liqi Feng

    Senior Biostatistician
    Sanofi, Shanghai, China
    Shanghai, Shanghai, China (People's Republic)

  • HP

    Helena Palmborg

    Associate Director Scientific Communications
    Sobi, Stockholm, Sweden
    Stockholm, Stockholms Lan, Sweden

  • GN

    Graham Neill

    Global Medical Director
    Sanofi, Reading, United Kingdom
    Reading, England, United Kingdom

  • LA

    Lydia Abad-Franch

    Senior Vice President, Head of Research, Development and Medical Affairs (RDMA)
    Sobi, Basel, Switzerland
    Basel, Basel-Stadt, Switzerland

  • SG

    Sriya Gunawardena

    Senior Clinical Research Director
    Sanofi, Bridgewater, NJ, USA
    Bridgewater, New Jersey, United States

  • KF

    Karin Fijnvandraat

    Professor
    Emma Kinderziekenhuis/AMC, University of Amsterdam, Netherlands
    Amsterdam, Noord-Holland, Netherlands

Background: Efanesoctocog alfa (formerly BIVV001) is a first-in-class high-sustained factor VIII (FVIII) replacement therapy designed to overcome the von Willebrand factor–imposed half-life ceiling. Once-weekly efanesoctocog alfa 50 IU/kg was well tolerated and provided highly effective bleed protection and factor activity within normal to near-normal levels (>40%) for 3 days, and of ~10% at Day 7, in children with severe hemophilia A in the XTEND-Kids study.

Aims: Evaluate long-term data on safety and efficacy of efanesoctocog alfa in previously treated children with severe hemophilia A in the XTEND-ed study (NCT04644575; first interim analysis).

Methods: XTEND-ed is a multicenter, open-label study that enrolled participants from previous Phase 3 studies, including children < 12 years of age who received weekly efanesoctocog alfa prophylaxis for ≤52 weeks in XTEND-Kids, and continue weekly 50 IU/kg prophylaxis in XTEND-ed. The primary endpoint is the occurrence of FVIII inhibitors. Secondary endpoints include annualized bleed rates (ABRs), efficacy for bleed treatment, and safety. Participants provided informed consent and XTEND-ed was approved by applicable ethics committees. Data cut: June 8, 2023.

Results: Seventy-one of 74 males (96%) rolled over from XTEND-Kids to XTEND-ed. The mean (standard deviation [SD]) efficacy period was 35.8 (14.1) weeks. No FVIII inhibitors were detected. The mean (SD) ABR was 0.70 (1.27; 6-monthly data: Table 1), thus maintaining the low mean ABR observed in the parent study (0.88). Most bleeds (86%; 30/35) resolved with a single dose of efanesoctocog alfa 50 IU/kg, with 96% (23/24) of hemostatic responses rated as excellent or good. Overall, 43 (61%) participants experienced ≥1 treatment-emergent adverse event (TEAE) and 2 (3%) experienced ≥1 serious TEAE (Table 2).

Conclusion(s): Long-term results in children with severe hemophilia A in XTEND-ed show that once-weekly efanesoctocog alfa continues to be well tolerated, with no FVIII inhibitors reported, and provides highly effective bleed protection.

Funded by Sanofi and Sobi.