Lower injection‐site reactions and long‐term safety, immunogenicity, and efficacy of etanercept biosimilar YLB113: Results from a post‐hoc analysis of a double‐blind, randomized, phase III comparative study and its open‐label extension in patients with rheumatoid arthritis

AIM: YLB113 biosimilar was evaluated in an open‐label extension single‐arm study to assess long‐term safety, efficacy, and immunogenicity in patients with rheumatoid arthritis (RA). We also report post‐hoc results on the incidence of injection‐site reactions (ISRs) and injection‐site erythema (ISE) from a phase III study. METHOD: Participants from the phase III, double‐blind, randomized, 96 week equivalence study who completed the final visit received 50 mg YLB113 subcutaneously every 2 weeks. Key safety end points were assessed through adverse events (AEs), ISRs, ISE, and anti‐drug antibody (ADA) incidence. The efficacy end point was change from baseline in Disease Activity Score 28‐joint count (DAS28) over time. RESULTS: Of 201 participants, 184 (91.5%) completed the study. Treatment‐emergent AEs were experienced by 93.5% and severe AEs by 10.0% of participants. The discontinuation rate due to AEs was 2.0%. Overall, 20.0% of participants reported an incidence of ISRs throughout the open‐label extension study. Two participants developed ADAs, and none developed neutralizing ADAs at any time after study drug administration. The overall DAS28 (mean ± SD) change was 2.22 ± 0.95 at the study transition, 2.10 ± 0.91 at week 72, and 2.06 ± 0.89 at the end of the study. In the post‐hoc analysis, YLB113 showed a statistically significant lower incidence of ISRs (10 [3.8%], P < 0.0001) and ISE (5 [1.9%], P < 0.0001) compared with the reference product Enbrel®. CONCLUSION: YLB113 demonstrated long‐term safety and sustained efficacy for up to 96 weeks. Patients on YLB113 experienced significantly lower ISRs and ISE in a post‐hoc analysis of the phase III study when compared with reference product.