Jade Biosciences announces JADE201 afucosylated monoclonal antibody

Jade Biosciences (JBIO) unveiled JADE201, its investigational half-life extended, afucosylated monoclonal antibody targeting the B-cell activating factor receptor. JADE201 is designed to overcome the limitations of current B cell-directed therapies by combining a dual mechanism of action and half-life extension technology, with the goal of improving on the clinical benefit of existing B-cell depleting therapies across a broad range of autoimmune diseases. Current B-cell depleting therapies may spare important pathogenic B cell populations and risk resistance, and relapse as a result of elevated BAFF signaling that drives B cell repopulation and autoreactivity. JADE201 was engineered with high binding affinity to BAFF-R, supporting robust receptor engagement across multiple B cell subsets. JADE201 incorporates afucosylation to enhance antibody-dependent cellular toxicity and a clinically validated Fc mutation to increase neonatal Fc receptor binding, with the goal of extending systemic exposure while preserving activity. The clinical proof-of-concept for BAFF-R inhibition has been established by ianalumab, which has shown activity across multiple autoimmune indications, including in multiple recent positive Phase 3 trials. JADE201 builds on the desirable pharmacological benefits of ianalumab while addressing its relatively short human half-life by adding half-life extension technology to extend drug exposure, with the potential to enable less frequent subcutaneous dosing and enhance efficacy. In non-human primate studies, JADE201 achieved dose-dependent BAFF receptor occupancy, sustained B cell depletion after a single subcutaneous dose, and demonstrated approximately a two-fold increase in half-life compared with ianalumab. This extended exposure is designed to improve durability and convenience while preserving potency, with the goal of reducing treatment burden and potentially enhancing efficacy. Jade expects to initiate a first-in-human study evaluating JADE201 in patients with rheumatoid arthritis in the first half of 2026. The randomized, placebo-controlled, single ascending dose trial will assess safety, tolerability, pharmacokinetics, and pharmacodynamics, with biomarker-rich endpoints including BAFF-R occupancy, soluble BAFF levels, and B cell subpopulation profiling.