BEST-10 | CHANGES IN HYPERTROPHIC SYNOVIUM STATUS IN ADULT PATIENTS WITH SEVERE HEMOPHILIA A RECEIVING EMICIZUMAB PROPHYLAXIS: THE RESOLVE STUDY

I.L. Calcaterra¹, M. Di Minno¹, E. Baldacci², G. D’Errico¹, C. Santoro², A. Strangio³, S. Sorella², M. Leotta³, R.C. Santoro³ | ¹Department of Clinical Medicine and Surgery, Federico II University, Napoli, Italy; ²Haematology, University Hospital Policlinico Umberto I, Roma, Italy; ³Hemostasis and Thrombosis Centre, Azienda Ospedaliero Universitaria Renato Dulbecco, Catanzaro, Italy

Background. Evidence on the impact of emicizumab on joint health, particularly hypertrophic synovium, remains limited.
Objectives. To evaluate changes in joint status, with a specific focus on HS, using point-of-care ultrasound and clinical examination in PwH switching from replacement therapy to emicizumab.
Methods. The RESOLVE study is a retrospective observational, multicenter cohort study including adults with severe hemophilia A (FVIII <1%), with and without anti-FVIII inhibitors, who started a treatment with emicizumab and were followed for at least 2 years. Clinical data, annualized bleeding rates (ABR, AjBR), HJHS, and HEAD-US assessments were collected during replacement therapy and after ≥2-year emicizumab. HS was graded according to the HEAD-US protocol. Changes in HS represented the primary outcome.
Results. Fifty-two PwH (mean ± SD age: 37.9±12.1years) were enrolled, with data on 298 joints. Emicizumab prophylaxis resulted in a significant reduction in ABR and AjBR compared with replacement therapy, with an increase in patients achieving ABR zero and AjBR zero. At baseline, HS was present in 22.5% of joints. After ≥2-year-emicizumab, HS was improved/resolved in 53.7% of affected joints, while it persisted in 38.8% and worsened in 7.5% of joints. New-onset HS was developed in 6.1% of previously unaffected joints. Baseline structural joint damage was strongly associated with the presence and persistence of HS.
Conclusions. In this real-world setting, emicizumab provides bleeding protection and is associated with reduction/resolution of HS in more than 50% of affected joints. In case of persistent HS, a tailored approach to joint health management may be needed to fully prevent or reverse HS.