P425 SPOSIB SB2: a Sicilian prospective observational study of patients with inflammatory bowel disease treated with infliximab biosimilar SB2

Abstract Background Few data on Infliximab (IFX) biosimilar SB2 in inflammatory bowel disease (IBD) are available. Methods SPOSIB SB2 is a multicentre, observational, prospective study performed among the cohort of the Sicilian Network for Inflammatory Bowel Disease (SN-IBD). All consecutive patients with Crohn’s disease (CD) or Ulcerative Colitis (UC) starting IFX biosimilar SB2 from the introduction of the drug in Sicily (March 2018) to September 2019 (18 months) were enrolled. Patients were divided into five groups (group A: naive to IFX, naive to anti-TNFs; group B: naive to IFX, previously exposed to other anti-TNFs; group C: switch from IFX originator to SB2; group D: switch from CT-P13 to SB2; group E: multiple switches: from IFX originator to CT-P13 to SB2). The primary end-point was the assessment of safety, in terms of the rate of serious adverse events (SAEs). Secondary end-point was the evaluation of effectiveness, in terms of steroid-free clinical remission and clinical response at 8 weeks and at the end of follow-up, and as treatment persistency. Results 276 patients (median age 39 years; CD 49.3%, UC 50.7%) were included [group A: 127 (46.0%); group B: 65 (23.6%); group C: 17 (6.2%); group D: 43 (15.6%); group E: 24 (8.7%)]. The cumulative number of infusions of SB2 was 1798, the median follow-up was 8 months (IQR: 4–12 months), and the total follow-up time was 182.7 patient-years (PY). Sixty-seven SAEs occurred in 57 patients (20.7%), with an incidence rate of 36.7 per 100 PY, and 26 of them caused the withdrawal of the drug. The incidence rate ratio (IRR) of SAEs was higher among patients in group B compared with group A (57.7 vs. 30.2 per 100 PY; IRr = 1.91; p = 0.026) and group C (57.7 vs. 18.9 per 100 PY; IRr = 2.93; p = 0.045). The effectiveness of IFX biosimilar SB2 after 8 weeks of treatment was evaluated in patients naïve to IFX (group A + B; n = 192): 110 patients (57.3%) had steroid-free remission, 26 patients (13.5%) achieved a partial response, while 56 patients had no response (29.2%). At the end of follow-up, 72 patients (26.1%) interrupted the treatment, without significant differences in treatment persistency estimations between the five groups (log-rank p = 0.15). Conclusion This is the first prospective study on the use of IFX biosimilar SB2 in IBD. Safety and efficacy of SB2 seem to be overall similar to those reported for IFX originator and IFX biosimilar CT-P13. A higher incidence of SAEs was observed among patients naive to IFX and previously exposed to other anti-TNFs.