The EGALITY study: a confirmatory, randomized, double-blind study comparing the efficacy, safety and immunogenicity of GP2015, a proposed etanercept biosimilar, vs. the originator product in patients with moderate-to-severe chronic plaque-type psoriasis

Background: GP2015 is a proposed etanercept biosimilar. Objectives: To demonstrate equivalent efficacy, and comparable safety and immunogenicity of GP2015 and the etanercept originator (ETN, Enbrel^®) in patients with moderate-to-severe chronic plaque-type psoriasis. Methods: In total, 531 eligible patients were randomized 1 : 1 to self-administer GP2015 or ETN twice weekly subcutaneously. Patients with ≥ 50% improvement in Psoriasis Area and Severity Index (PASI 50) at week 12 were rerandomized to continue the same treatment on a once-weekly dosing schedule or to undergo a sequence of three treatment switches between GP2015 and ETN until week 30. Thereafter, patients continued treatment with the product they had been assigned to last, up to week 52. Results: The difference in PASI 75 (75% improvement from baseline PASI score) response rates at week 12 between GP2015 and ETN (primary end point) was −2·3%. The 95% confidence interval (−9·85 to 5·30) was well contained within the prespecified margin range of −18 to 18. The incidence of treatment-emergent adverse events up to week 52 was comparable between continued GP2015 (59·8%) and ETN (57·3%); switching treatments revealed comparable safety profiles. Antidrug antibodies, all non-neutralizing, were limited to five patients on ETN during treatment period 1, and one patient in the switched ETN group, who had been treated with GP2015 for 12 weeks at the time of the finding. Conclusions: The EGALITY study demonstrated equivalent efficacy and comparable safety and immunogenicity of GP2015 and ETN. The study results provide the final clinical confirmation of biosimilarity and contribute to the totality of the evidence proposing that GP2015 is an etanercept biosimilar.