Switching patients with inflammatory arthritis from Etanercept (Enbrel(®)) to the biosimilar drug, SB4 (Benepali(®)): A single-centre retrospective observational study in the UK and a review of the literature

OBJECTIVE/AIM: SB4 (Benepali(®)), the Etanercept biosimilar, is licenced in the UK for the same indications as the reference product, Enbrel(®). In 2016, the Rheumatology Department at Blackpool Teaching Hospitals switched the Etanercept patients, who gave consent, to SB4. A proportion of these patients switched back to Etanercept and therefore we aimed to investigate the reasons of SB4 withdrawal and compare our results with the current evidence. METHODS: We included all the patients switched to SB4 until April 2018, identified from the departmental biologics database. We also searched the published and grey literature through November 2018 for similar articles. RESULTS: 72 Etanercept patients switched to SB4, of which 19 (26.4%) switched back to Etanercept within 6 months on the biosimilar product. All the 19 patients remained on Etanercept until the time of data analysis. The main reason of withdrawal was loss of effect (LOE, 58%). In RA, the duration on Etanercept was associated with SB4 withdrawal (OR 1.43 [95% CI 1.02, 2.00]) and LOE was reflected in the DAS- 28, PGS and CRP increase and in the number of tender joints (all p <0.05). We found ten observational studies reporting 3184 patients, who switched from Etanercept to SB4 and 432 of them (14%) stopped SB4. CONCLUSION: The majority (73.6%) stayed on SB4, which is consistent with the current evidence. Taking also into consideration the results of the other studies, it is unclear if this withdrawal is a true failure on SB4, nocebo effect or spontaneous disease flare.