TSUBASA Study: Evaluating Association of Physical Activity and Bleeding Events in People With Haemophilia A Without Factor VIII Inhibitors Receiving Emicizumab.

Background: Emicizumab is approved for routine prophylaxis, but limited data exist investigating the relationship between bleeds and exercise in people with haemophilia A (PwHA) receiving emicizumab.

Aim: To evaluate the relationship between physical activity and bleeding outcomes in Japanese PwHA receiving emicizumab prophylaxis.

Methods: This prospective, multicentre, observational study was conducted in Japanese PwHA initiating emicizumab between November 2019 and October 2021. Physical activity and bleeding events were reported using an electronic patient-reported outcomes application, while activity intensity was collected by a wearable activity tracker worn over five 8-day monitoring periods. Data on safety were recorded by investigators using electronic case report forms. Quality of life data were also collected and will be reported in a separate publication.

Results: Overall, 129 participants enrolled. Median age was 32 years (range 0-73), and 83.7% of participants had severe HA. Overall, 73 participants performed 968 exercise events, with 18.8% and 6.0% of events classified as moderate and high risk, respectively. Two (0.2%) exercise events were associated with bleeding: one basketball (moderate risk) and one fishing (low risk). In total, 137 adverse events (AEs) were reported in 62 participants. No serious AEs were emicizumab-related. The mean annualised treated bleed rate was 1.9 and 51 (39.5%) participants experienced zero bleeds during the study period (97 weeks).

Conclusion: This study suggests that PwHA receiving emicizumab prophylaxis can participate in a wide range of physical activities with minimal bleeding risk, which supports their access to the health benefits of exercise. Emicizumab remains well tolerated.