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CC BY 4.0 · TH Open 2026; 10: a27818278
DOI: 10.1055/a-2781-8278
Original Article

Paediatric Subanalysis of TSUBASA, Assessing Physical Activity, Bleeding, Quality of Life and Safety in People with Haemophilia A Receiving Emicizumab

Authors

  • Keiji Nogami

    1   Department of Pediatrics, Nara Medical University, Nara, Japan

  • Kagehiro Amano

    2   Department of Laboratory Medicine, Tokyo Medical University, Tokyo, Japan

  • Akihiro Sawada

    3   Department of Respiratory Medicine and Hematology, Hyogo Medical University, Hyogo, Japan

  • Azusa Nagao 

    4   Department of Hematology and Oncology, Kansai Medical University Hospital, Osaka, Japan
    5   Department of Blood Coagulation, Ogikubo Hospital, Tokyo, Japan

  • Chiai Nagae

    6   Department of Pediatrics, St. Marianna University School of Medicine, Kanagawa, Japan

  • Masanori Nojima

    7   Center for Translational Research/Division of Advanced Medicine Promotion, Institute of Medical Science, University of Tokyo, Tokyo, Japan

  • Nobuaki Suzuki

    8   Department of Transfusion Medicine, Nagoya University Hospital, Aichi, Japan

  • Mika Kawano

    9   Medical Science, Chugai Pharmaceutical Co., Ltd., Tokyo, Japan

  • Tomomi Shimura

    9   Medical Science, Chugai Pharmaceutical Co., Ltd., Tokyo, Japan

  • Yoshimasa Sugao

    9   Medical Science, Chugai Pharmaceutical Co., Ltd., Tokyo, Japan

  • Teruhisa Fujii

    10   Division of Transfusion Medicine/Hemophilia Treatment Center, Hiroshima University Hospital, Hiroshima, Japan

Funding Information The study was funded by Chugai Pharmaceutical Co., Ltd.
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Abstract

Introduction

Limited data are available on the relationship between bleeding outcomes and physical activity, and the quality of daily life (QoL), in children with haemophilia A (HA) receiving emicizumab prophylaxis.

Aim

TSUBASA evaluated physical activity, bleeding events, safety, and QoL in Japanese people with HA initiating emicizumab prophylaxis. This paper reports the results from the final analysis, focusing on children and adolescents with HA without factor VIII inhibitors, and their caregivers.

Methods

TSUBASA was a prospective, multicentre, observational study conducted across 50 medical institutions in Japan. Participants received emicizumab for 97 weeks. Bleeding events and physical activity data were obtained using an electronic patient-reported outcomes application; activity intensity was collected by wearable activity trackers worn over five 8-day monitoring periods. Adverse events (AEs) were documented on the electronic case report form and QoL was assessed using questionnaires.

Results

A total of 46 participants aged <18 years were enrolled; most (84.8%) had severe HA. Over a median observation period of 674 days (quartile 1–quartile 3: 665–690), the mean annualized bleed rate was 0.86 (standard deviation: 1.26). In all Twenty-six participants experienced 66 AEs, of which 2 were injection-site reactions deemed related to emicizumab. J-KIDSCREEN-52 questionnaire scores were maintained from baseline onwards. Of the completed caregiver questionnaires (n = 32), 43.8% reported increased activity and 56.3% reported unchanged activity. Additionally, 56.3% reported decreased anxiety about bleeding and 37.5% reported unchanged anxiety about bleeding. A total of 172 events of physical activity were recorded by 19 participants; 44 were high risk, 70 were moderate risk, and 42 were low risk. One activity-related traumatic bleed resulting from the impact of a basketball occurred, and more than 25 different types of physical activity were performed without bleeding.

Conclusion

Children and adolescents with HA who receive prophylaxis with emicizumab may be able to engage in consistent physical activity, with a low risk of experiencing bleeds. Additionally, the questionnaire responses from caregivers on physical activity and caregiver experience provide rare insights into the real-world impact of emicizumab prophylaxis. These findings present a more comprehensive view of the benefits of emicizumab. No new safety signals were observed and QoL was maintained for 2 years after emicizumab initiation.

Keywords

exercise - Japan - children - adolescents - prophylaxis

Data Availability Statement

Data are available upon reasonable request.


Contributors' Statement

K.N.: conceptualization, data curation, formal analysis, investigation, methodology, supervision, writing—review and editing; K.A.: conceptualization, data curation, formal analysis, investigation, methodology, supervision, writing—review and editing; A.S.: conceptualization, data curation, formal analysis, investigation, methodology, supervision, writing—review and editing; A.N.: conceptualization, data curation, formal analysis, investigation, methodology, supervision, writing—review and editing; C.N.: conceptualization, data curation, formal analysis, investigation, methodology, supervision, writing—review and editing; M.N.: conceptualization, data curation, formal analysis, investigation, methodology, supervision, writing—review and editing; N.S.: conceptualization, data curation, formal analysis, investigation, methodology, supervision, writing—review and editing; M.K.: conceptualization, formal analysis, methodology, supervision, writing—review and editing; T.S.: conceptualization, formal analysis, methodology, software, supervision, validation, writing—review and editing; Y.S.: conceptualization, formal analysis, methodology, project administration, supervision, writing—review and editing; T.F.: conceptualization, data curation, formal analysis, investigation, methodology, supervision, writing—review and editing. All authors have reviewed and approved the article prior to submission and agree to be accountable for all aspects of the work.


Ethical Approval

The study was conducted in compliance with the International Conference on Harmonisation Guidelines for Good Clinical Practice, the Act on the Protection of Personal Information (27 May 2016), the Ethical Guidelines for Medical and Health Research Involving Human Subjects, and the Declaration of Helsinki. The study protocol was approved by the research ethics committee at each study site.


Written informed consent was provided before entering the study by all participants or their legally acceptable representatives.


Supplementary Material



Publication History

Received: 21 July 2025

Accepted: 06 January 2026

Article published online:
21 January 2026

© 2026. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)

Georg Thieme Verlag KG
Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany

Bibliographical Record
Keiji Nogami, Kagehiro Amano, Akihiro Sawada, Azusa Nagao, Chiai Nagae, Masanori Nojima, Nobuaki Suzuki, Mika Kawano, Tomomi Shimura, Yoshimasa Sugao, Teruhisa Fujii. Paediatric Subanalysis of TSUBASA, Assessing Physical Activity, Bleeding, Quality of Life and Safety in People with Haemophilia A Receiving Emicizumab. TH Open 2026; 10: a27818278.
DOI: 10.1055/a-2781-8278
 

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