OC 69.5 - Outcomes in Adult and Adolescent Patients With Severe Hemophilia A in the Phase 3 XTEND-1 Study Who Switched to Efanesoctocog Alfa Prophylaxis From an Observational Study With Factor VIII Prophylaxis

Wednesday, June 28, 2023

11:15 – 11:30 ET

Room: 517

Session Available As: Live-Stream and On-Demand

Presenting Author(s)

Sophie Susen, MD, PhD (she/her/hers)

MD, PhD
Univ. Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1011- EGID, F-59000 Lille, France
Lille, Nord-Pas-de-Calais, France

Co-Author(s)

RK

Roshni Kulkarni

Professor, Director Pediatric Hem/Onc, Director MSU center for Bleeding and Clotting Disorder
Department of Pediatrics and Human Development, Michigan State University, East Lansing, MI, USA
East Lansing, Michigan, United States
KN

Keiji Nogami

Professor
Nara Medical University, Nara, Japan
Nara, Nara, Japan
Flora Peyvandi, MD, PhD (she/her/hers)

Director
IRCCS Ca' Granda Maggiore Hospital Foundation, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milano, Italy; Università degli Studi di Milano, Department of Pathophysiology and Transplantation, Milano, Italy
Milano, Lombardia, Italy
Barbara A. Konkle, MD (she/her/hers)

Professor of Medicine
University of Washington
Seattle, Washington, United States
ES

Elena Santagostino

VP Medicine Development Lead for Haemophilia
Sobi, Basel, Switzerland
Basel, Stockholms Lan, Sweden
UK

Umer Khan

Biostatistics Lead
Sanofi, San Diego, CA, USA
San Diego, California, United States
AW

Annemieke Willemze

Global Project Head, Efanesoctocog alfa (BIVV001), Rare Blood Disorders Development
Sanofi, Amsterdam, Netherlands
Amsterdam, Noord-Holland, Netherlands
LB

Linda Bystricka

Director, Global Medical Affairs
Sobi, Stockholm, Sweden
Stockholm, Stockholms Lan, Sweden
JD

Jennifer Dumont

Senior Medical Director, Global Medical Affairs
Sanofi, Cambridge, MA, USA
Cambridge, Massachusetts, United States
PC

Pratima Chowdary, MD

Consultant Haematologist
Katharine Dormandy Haemophilia and Thrombosis Centre, Royal Free London NHS Foundation Trust, London, United Kingdom
London, England, United Kingdom

Background: Efanesoctocog alfa (50 IU/kg), a new class of factor VIII (FVIII) replacement therapy designed to decouple recombinant FVIII (rFVIII) from endogenous von Willebrand factor, provides high sustained FVIII activity in the normal to near-normal range (>40 IU/dL) for the majority of the week with once-weekly dosing.

Aims: To describe a post-hoc intrapatient comparison of outcomes in patients (≥12 years old) with severe hemophilia A on conventional FVIII prophylaxis in a prospective, observational study prior to switching to efanesoctocog alfa prophylaxis while enrolled in XTEND-1 (NCT04161495).

Methods: After providing informed consent, 78 patients (12–69 years old) who had received ≥6 months standard-of-care FVIII prophylaxis (standard half-life FVIII [recombinant or plasma-derived FVIII; n=44] or extended half-life rFVIII [n=34]) in the observational study, and then enrolled in Arm A of XTEND-1 (52 weeks, once-weekly efanesoctocog alfa [50 IU/kg]). Annualized bleed rates (ABR), treatment of bleeds, FVIII consumption, and injection frequency were compared for conventional standard-of-care FVIII prophylaxis (pre-study) versus efanesoctocog alfa (on-study).

Results: Mean (95% confidence interval [CI]) change in overall ABR from pre-study to on-study was −2.27 (−3.44, −1.10); change in joint, spontaneous, and spontaneous joint ABRs were −1.55 (−2.46, −0.64), −1.20 (–1.84, −0.57), and −0.93 (−1.42, −0.43), respectively (Table). Overall, 42.3% of patients were bleed-free pre-study (median observation period: 50.05 weeks) versus 64.1% on-study (median: 50.09 weeks). Mean (standard deviation) number of injections for bleed treatment was 1.8 (5.10) pre-study versus 1.1 (0.30) on-study. Mean (95% CI) change in weekly injection frequency and consumption was −1.37 (−1.59, –1.15) doses and −35.00 (−47.82, –22.18) IU/kg, respectively (Figure). Mean (95% CI) change in annualized consumption was −1828.22 (−2491.88, −1164.57) IU/kg.

Conclusion(s): Switching to once-weekly efanesoctocog alfa 50 IU/kg prophylaxis provided superior bleed protection with reduced injection frequency and lower weekly FVIII consumption versus prior standard-of-care prophylaxis.

Funded by Sanofi and Sobi.

Learning Objectives:

At the conclusion of this presentation participants will be able to describe the study design of the 12-month observational prestudy and the Phase 3 XTEND-1 study
Participants will be able to understand the results of a post hoc analysis of participants with severe hemophilia A who had switched to efanesoctocog alfa prophylaxis after receiving conventional FVIII prophylaxis
Participants will be able to compare consumption of FVIII and outcomes for the treatment of bleeding episodes in those receiving efanesoctocog alfa versus standard or extended half-life FVIII replacements