AnaptysBio, Inc. announced positive top-line results from its global Phase 3 GEMINI-1 trial evaluating the safetyAnaptysBio, Inc. and efficacy of imsidolimab (IL-36R mAb) in patients with generalized pustular psoriasis (GPP) flares. Investigational imsidolimab met its primary endpoint in the study population achieving rapid clearance of pustulation, erythema and scaling through Week 4 after a single dose of 750mg IV imsidolimab. Top-line data also demonstrate a favorable safety and tolerability profile.

Imsidolimab is an IgG4 antibody that inhibits the function of the interleukin-36 receptor (IL-36R), a signaling pathway within the immune system shown to be involved in the pathogenesis of inflammatory diseases, including GPP. The registration-enabling GEMINI-1 trial in GPP, which recruited 45 patients, is the first randomized, double-blind, placebo-controlled trial to use the composite endpoint of Generalized Pustular Psoriasis Physician Global Assessment (GPPPGA) at Week 4 as its primary assessment. The GPPPGA assessment, representing a stringent and comprehensive characterization of disease severity, required satisfying an overall clinical response score of 0/1 (clear or almost clear) collectively across each GPP disease attribute, including pustulation, erythema and scaling.

Imsidolimab Met Primary Endpoint Achieving Rapid Clearance of GPP Through Week 4 After a Single Dose: 53.3% of patients who received a single dose of 750mg IV imsidolimab achieved GPPPGA 0/1 (clear or almost clear) at Week 4 (primary endpoint), compared to 13.3% of patients on placebo (p=0.0131); Additionally, 66.7% (10/15) of placebo patients exited GEMINI-1 early, crossed-over to GEMINI-2 and were eligible to receive rescue therapy with a single dose of 750mg IV imsidolimab. Imsidolimab Was Well Tolerated Through End of Study: All AEs reported in imsidolimab-treated patients were mild or moderate and balanced across imsidolimab-treated vs. placebo patients; No SAEs or severe AEs reported in imsidolimab-treated patients; No cases reported of Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) or Guillain-Barre syndrome (GBS); Low incidence and no elevation of infections vs.

placebo; No infusion reactions reported; One of 30 (3.3%) imsidolimab-treated patients had detectable anti-drug antibodies, which were non-neutralizing. Anaptys plans to present comprehensive data from GEMINI-1 and top-line GEMINI-2 results at a medical meeting in H2 2024. Furthermore, the company anticipates filing a biologics license application (BLA) with the U.S. Food and Drug Administration (FDA) by Third Quarter 2024.