Topical application of a novel anti‐interleukin‐17A antibody fragment penetrates psoriatic skin: Results of a randomised, double‐blind, placebo‐controlled Phase Ib study

Interleukin (IL)-17A underlies the pathogenesis of chronic plaque psoriasis (CPP). Well-tolerated, effective IL-17A inhibitors for mild-to-moderate CPP are needed. ZL-1102 is a novel antibody fragment targeting IL-17A. To assess the safety, tolerability, preliminary efficacy and skin penetration of a topical 1% ZL-1102 hydrogel in patients with mild-to-moderate CPP, a two-part, Phase Ib study was conducted. Open-label Part A: six patients received a single topical application of ZL-1102 onto a psoriatic plaque; double-blind Part B: 53 patients were randomised 1:1 to twice-daily ZL-1102 or vehicle for 4 weeks. Key primary endpoints included treatment-emergent adverse events (TEAEs), tolerability and changes in local psoriasis area and severity index (PASI). TEAEs occurred in two (33.3%) patients in Part A and in 16 (59.3%) and 13 (50.0%) patients in the ZL-1102 and vehicle arms, respectively, in Part B. No grade ≥3 TEAEs were seen with ZL-1102. ZL-1102 led to numerically greater changes in local PASI versus vehicle (-28.8% vs. -17.2%), with good local tolerability. The trend towards local PASI improvement was accompanied by biomarker changes based on RNA sequencing, indicative of ZL-1102 penetration into psoriatic plaques. Topical ZL-1102 showed good safety, local tolerability and a trend towards improved local PASI; skin penetration was observed without measurable systemic exposure. ACTRN12620000700932.