Abstract
BACKGROUND: Studies have reported good efficacy outcomes for patients with inflammatory bowel disease (IBD) treated with biosimilars. There are limited long term data. We assessed the long-term efficacy data and safety after switching from adalimumab to adalimumab biosimilar Imraldi in patients with IBD. METHODS: A prospective single-centre observational study involving patients with Crohn’s disease or ulcerative colitis switched from adalimumab originator to adalimumab biosimilar and reviewed up to 24months. Efficacy and loss of response were measured using the Harvey–Bradshaw (HB) index and partial Mayo score for patients with Crohn’s disease and ulcerative colitis respectively. Blood tests including C-reactive protein, adalimumab drug levels and antidrug antibodies were monitored. We have recorded side effects and possible serious adverse effects including COVID 19 infection. RESULTS: 113 patients were switched to Adalimumab biosimilar Imraldi from Adalimumab originator between January 2019 to March 2019. After 12 months of treatment, 25 patients interrupted treatment and 89 (78.8%) continued. These were analysed after 24 months of treatment - 57 (52.3%) continued on Imraldi. Of those who discontinued, 9 were switched back to Adalimumab originator due to side effects, and 34 stopped treatment - 16 patients due to loss of response, 11 patients developed antibodies, 5 underwent a surgery, 4 were in remission and 4 did not tolerate side effects. There was no statistical difference in CRP or Adalimumab levels prior to switch, at 12 months and at 24 months between the patients who continued or discontinued treatment. Overall, 18 of the patients who completed 24 months of treatment reported side effects, most frequently pain after injection (9 patients), followed by skin rash and recurrent infections (in 3 patients each). No patient was diagnosed with COVID 19 during until now. CONCLUSION: After 24 months of follow up, 52.3% patients continued on adalimumab biosimilar and no serious side effects were reported. In particular, none of our patients acquired COVID 19 infection.