The OASIS trial is a multicenter, randomized, double-blind, placebo-controlled, investigator-initiated phase 2 study in Japan investigating the efficacy and safety of subcutaneous efgartigimod PH20 for Sjögren's disease (SjD) dryness[1]. Sjögren's disease is a chronic autoimmune disease with lymphocytic infiltration and destruction of the lacrimal and salivary glands, leading to dryness of the eyes and mouth, which significantly impairs the quality of life, especially in severe dryness[1]. There is no disease-modifying treatment approved for SjD, and the effect of efgartigimod PH20 on dryness remains unknown, although it has shown promising efficacy in systemic SjD[1]. Approximately 45 adult patients with SjD and moderate to severe dryness will be randomized 1:1:1 to subcutaneous efgartigimod PH20 1000 mg weekly (QW), 1000 mg every two weeks (Q2W), or placebo for 24 weeks[1]. The primary endpoint is the change in ESSPRI (EULAR Sjögren's syndrome patient-reported index) dryness score from baseline to week 24[1]. Key secondary endpoints include changes in ESSPRI total, ESSPRI fatigue, DiSSA symptom diary, and ESSPRI and STAR response rate[1]. The blinded period is followed by open-label extended treatment to assess long-term safety and efficacy[1]. The study is registered in the Japanese Clinical Trials Registry (jRCT2071250042) from July 8, 2025[1].