P548 Efficacy, safety, and pharmacokinetics after switching from infliximab originator to biosimilar SB2 in inflammatory bowel disease patients: A long-term observational, prospective cohort study

Abstract Background SB2 is a biosimilar infliximab approved for the treatment of inflammatory bowel disease (IBD) patients. These are the first prospective data investigating long-term efficacy, safety, and pharmacokinetics after switching from infliximab originator to biosimilar SB2 in IBD patients. Methods This is a prospective, observational cohort study of patients that underwent a switch from infliximab originator to biosimilar SB2 in 2017 as part of routine care at the outpatient Clinic for IBD at the University Hospital of Erlangen, Germany. Long-term safety and clinical effectiveness were recorded over a follow-up period of 18-months. Clinical disease activity was assessed by the Harvey–Bradshaw Index (HBI) in Crohn’s disease (CD) and the partial Mayo Score (pMS) in ulcerative colitis (UC) patients. C-reactive protein (CRP) was analyzed at every patient visit, and IFX trough-level (TL) and anti-IFX antibodies (ADA) were measured prior to every SB2 administration, using the Promonitor® tests. The occurrence of adverse events was registered at every patient visit. Results A total of 148 IBD patients (96 CD, 52 UC) was enrolled. The median duration of previous infliximab treatment before the switch was 29 months (range 1.0–110.0). Median disease activity in CD was an HBI of 3 (0–16) at switch (baseline), 2 (0–13) at month 6, 3 (0–15) at month 12 and 2.5 (0–11) at month 18. Median disease activity in UC was a pMS of 0 (0–6) at baseline, 1 (0–4) at month 6, 1 (0–4) at month 12 and 1 (0–5) at month 18. The median TL for all IBD patients was 6.3 mg/ml (0.1–33.7) at baseline, 5.0 mg/ml (0.1–34.3) at month 6, 6.3 mg/ml (0.1–35.8) at month 12 and 5.1 mg/ml (0.1–35.4) at month 18. CRP for all IBD patients was 2.2 mg/l (0.1–45.6) at baseline, 2.2 mg/l (0.1–90.4) at month 6, 2.3 mg/l (0.1–169.5) at month 12 and 2.7 mg/l (0.1–19.8) at month 18. In the 18-month follow-up period, 12/103 (11.7%) of patients who were ADA-negative at baseline developed ADA post-switch. Altogether, 40 (27%) IBD patients discontinued SB2 treatment during the 18-month follow-up period (4 anaphylaxis, 20 loss of response, 7 non-serious and 9 serious adverse events), 2 paused during pregnancy, 1 discontinued in clinical remission, 10 were lost to follow-up (7 change of physician, 3 unknown). Serious adverse events comprised 3 malignancies (breast and prostate carcinoma, neuroendocrine malignancy), 1 liver abscess and 5 intestinal surgical procedures (1 perforation, 1 ileus, and 3 stenoses). Conclusion Switching from IFX originator to biosimilar SB2 was not associated with an increase in disease activity. No clinically meaningful changes in IFX trough levels or immunogenicity were identified. Altogether, SB2 was well tolerated in a real-life setting.