Efficacy and Safety of CT‐P43, a Candidate Ustekinumab Biosimilar, in Moderate‐to‐Severe Plaque Psoriasis: 52‐Week Results From a Randomised, Active‐Controlled, Double‐Blind, Phase III Study

Equivalent efficacy—mean per cent improvement from baseline in Psoriasis Area and Severity Index (PASI) score at Week (W) 12 (primary endpoint)—was demonstrated between CT‐P43, a candidate ustekinumab biosimilar, and reference ustekinumab. This study further evaluated the efficacy, pharmacokinetics, safety and immunogenicity of CT‐P43 vs. reference ustekinumab, including after switching to CT‐P43 from reference ustekinumab, in patients with moderate‐to‐severe plaque psoriasis. In this double‐blind Phase III trial, patients were randomised (1:1) to treatment with subcutaneous CT‐P43 or reference ustekinumab (45/90 mg [baseline body weight ≤ 100/> 100 kg]). At W16, patients receiving reference ustekinumab were re‐randomised (1:1) to either continue this treatment or switch to CT‐P43; CT‐P43‐treated patients continued CT‐P43. Study medication was administered at W16 (after re‐randomisation), W28 and W40. Secondary efficacy endpoints, pharmacokinetics, safety and immunogenicity were evaluated until W52. At W16, 502 patients were re‐randomised ( n = 253 continued receiving CT‐P43; n = 125 continued receiving reference ustekinumab; n = 124 switched to CT‐P43). Mean (standard deviation) PASI scores at W52 were similar across groups (continuing CT‐P43: 1.44 [2.921]; continuing reference ustekinumab: 1.33 [3.070]; switched: 1.93 [2.966]). At W52, similar proportions of patients continuing CT‐P43, continuing reference ustekinumab and switching achieved ≥ 75% improvement in PASI score ( n = 226 [89.3%], 116 [92.8%] and 111 [89.5%]), static Physician’s Global Assessment score of 0/1 ( n = 215 [85.0%], 110 [88.0%] and 96 [77.4%]) and Dermatology Life Quality Index score of 0/1 ( n = 150 [59.3%], 67 [53.6%] and 78 [62.9%]). Serum ustekinumab concentrations were comparable across groups. Proportions of patients experiencing treatment‐emergent adverse events (TEAEs) were similar across groups; study medication–related TEAEs occurred in 14 (5.5%), 8 (6.4%) and 12 (9.7%) patients continuing CT‐P43, continuing reference ustekinumab and switching, respectively. Switching did not increase antidrug antibody positivity. Results support the comparability of CT‐P43 to reference ustekinumab. Efficacy was maintained after switching to CT‐P43 from reference ustekinumab, without notable safety or immunogenicity findings. Trial Registration: ClinicalTrials.gov identifier: NCT04673786