P468 Switching from adalimumab originator to ABP 501 biosimilar: a multicentre North Italian study

Abstract

Introduction: In late 2018, adalimumab (ADA) biosimilars have been approved by the EMA with the same indications of the reference product (RP), that is Humira. However, while their efficacy and safety have been proven in patients with rheumatoid arthritis and psoriasis showing no differences compared to the RP, data on inflammatory bowel disease (IBD) is lacking. The primary aim of this study was to verify the ability of ABP501 to maintain the clinical response induced by the RP after switching to the biosimilar. Aims & Methods: We retrospectively enrolled all consecutive patients who switched to ABP501 by ADA Originator at the IBD Units of Veneto Region (Padua, Santorso) from December 2018 to November 2019. We collected data on partial Mayo (p-Mayo) Score, Harvey-Bradshaw Index (HBI), C Reactive Protein (CRP), fecal calprotectin (FC), concomitant steroid and azathioprine therapy at the time of the switch (T0) and after six months. Continuous and categorical variables were expressed as mean with standard deviation (SD) and frequency with percentages respectively. Comparisons among variables were conducted using one-way ANOVA and Chi-square. Data were analyzed using STATA11 software. Result(s): Fifty-eight IBD patients switched to biosimilar [12 with Ulcerative Colitis (UC) and 46 with Crohn Disease (CD)] were included in the study. All switched patients were in remission or in mild clinical activity at the time of the switch. We observed a clinical worsening and clinical improvement in 12 and 3 patients, respectively (p=0.001) from T0 to T1. FC value increases at T1 compared to T0 (from a mean value of 98.32 to 137.9 ug/g) but without significantly difference. Ten patients needed to add steroids at T1 (p=0.04) and eight (13,7%) needed therapeutic optimization. Finally, 11 (18,9%) patients stopped therapy: 10 for loss of response and 2 for adverse event. Conclusion(s): Our data shows that after switching, 1/3 of the patients may experience a disease relapse, requiring treatment optimization (i.e. addiction of steroids or increasing the dose to once a week) or treatment discontinuation. Thus, patients should be strictly observed in order to prevent or, at least, early manage such clinical relapses. Larger and longer studies are mandatory to understand the clinical implications of these findings.