Introduction Biosimilar IFX (CT-P13; Remsima^TM/Inflectra^TM) became available in the UK in February 2015 offering significant savings to the NHS. Efficacy and safety data in inflammatory bowel disease (IBD) is limited. From May 2015 IBD patients at the Royal Devon and Exeter NHSFT were switched from Remicade^TM to Biosimilar IFX. We reviewed efficacy and safety data during this switch.

Methods Treatment was evaluated in IBD patients who met the following criteria: i) Remicade^TM treatment for greater than 6 months prior to switch ii) minimum follow-up data of 6 months following switch. Disease activity scores (Harvey-Bradshaw Index for Crohn’s disease [CD] and Simple Colitis Score for ulcerative colitis [UC]), CRP, drug levels and total anti-drug antibody levels were collected immediately prior to biosimilar switch and then every 16 weeks. All adverse events were recorded.

Results 104 patients (54 male) met the inclusion criteria with a mean age of 43 years (range 17–71). 73 had CD, 29 had UC and 2 had IBD-unclassified. The median duration of Remicade^TM therapy prior to switch was 1137 days (95% confidence interval = 933–1290). Missing cases were excluded on a variable by variable basis. There was no significant difference in CRP (median pre-switch = 2, post-switch = 2, P = 0.81) or disease activity score (median pre-switch = 1, post-switch = 1, P = 0.44) after switching from Remicade^TM to Biosimilar IFX. 85% were in remission before compared with 81% six months following switch (P = 0.51).

There was no difference in the number of people with detectable total anti-drug antibody levels (pre-switch = 29, post-switch = 27, P = 0.88) but a fall in drug levels was noted after switching (median pre-switch =5.4, post-switch = 2.8, P = 0.01). 41% had significant anti-drug antibodies pre-switch compared to 36% at 6 months post switch (P = 0.50). 11% of patients had positive anti-drug antibodies with undetectable drug levels pre-switch compared to 7% at 6 months (P = 0.35).

4 patients had adverse events within eight months of switching to biosimilar IFX; 2 minor infusion reactions and 2 anti-TNF induced skin disease. 19 patients stopped within six months of switching; 6 electively, 9 due to loss of response and 4 for other reasons.

Conclusion This uncontrolled data suggests biosimilar IFX is safe and effective with no significant change observed in CRP, disease severity index and drug antibody levels six months after switch. The fall in IFX drug level after switch warrants further investigation.

Disclosure of Interest K. Bennett: None Declared, G. Heap Grant/research support from: Hospira, Knapp, Abbvie, MSD, S. Hawkins: None Declared, T. Ahmad Grant/research support from: Hospira, Knapp, Abbvie, MSD