Vanda Pharmaceuticals Announces Orphan Drug Designation in Japan for Imsidolimab in Generalized Pustular Psoriasis

WASHINGTON, May 27, 2026 /PRNewswire/ -- Vanda Pharmaceuticals Inc. (Vanda) (Nasdaq: VNDA) today announced that Japan's Ministry of Health, Labour and Welfare (MHLW) has granted orphan drug designation to imsidolimab, a high‑affinity humanized immunoglobulin G4 (IgG4) monoclonal antibody, for the treatment of generalized pustular psoriasis (GPP). Imsidolimab inhibits interleukin‑36 (IL‑36) receptor signaling, addressing the deficiency in the endogenous IL‑36 receptor antagonist regulator that is commonly observed in patients with GPP.1 The MHLW grants orphan drug designation to medicines intended to treat rare diseases with significant unmet medical need.