Background Infliximab is one of the most widely used alternatives in ulcerative colitis (UC). The recent appearance of a biosimilar makes it necessary to assess its use.

Purpose To assess the effectiveness and safety of biosimilar infliximab in patients with UC.

Material and methods Retrospective observational study performed in a tertiary hospital. Patients included were those with UC who were being treated with Remicade and then switched to Remsima (biosimilar infliximab) from March to June 2015.

Effectiveness and safety were assessed 3 months after the switch. The following variables were collected: age, sex, concomitant therapy, disease classification according to the Montreal Scale (severity and extention) in UC, effectiveness and adverse effects. Effectiveness was measured using the True-Love-Witts Scale and C reactive protein (CRP) levels before and 3 months after the switch. Safety was assessed by collecting all adverse events that occurred during treatment.

Results 25 patients were included, 52% were women with an average age of 45 years (21–71). At inclusion, 20% of patients were treated concomitantly with corticosteroids and 36% with azathioprine/mercaptopurine. According to the Montreal Scale, 28% of patients had an extension level of E2, 72% had E3 and none had E1. On the other hand, the severity variable was distributed as follows: 8% of patients S0, 32% S1, 48% S2 and 12% S3. At baseline, 23 patients had stabilised disease and 2 had minor outbreaks. Effectiveness was assessed in 12 patients who were reviewed 3 months after the switch. One patient had a minor outbreak at the beginning and no clinical change occurred after the use of the biosimilar. As for the remaining evaluated patients, 8 maintained the same Tru-Love-Witts score and 4 had a decrease. There was no clinically relevant increase in CRP. No adverse events were detected after the switch.

Conclusion Despite being a preliminary assessment with just a few patients, initial data showed that the switch to an infliximab biosimilar did not represent a decrease in effectivenees and/or safety in patient with UC.

Long term assessment of these patients is required to confirm these results.

No conflict of interest.