Climb Bio is a clinical-stage biotech developing two antibody therapies for autoimmune diseases, with no approved products and no product revenue. Its lead candidate, budoprutug, is an anti-CD19 monoclonal antibody designed to deplete B cells — the key drivers of many autoimmune diseases. By targeting CD19, which is expressed across a broader range of B-cell subtypes than the more commonly targeted CD20, budoprutug aims to more completely eliminate the pathogenic B cells responsible for disease. Climb Bio is developing budoprutug in three indications: primary membranous nephropathy (pMN, a rare kidney disease), immune thrombocytopenia (ITP, a rare platelet disorder), and systemic lupus erythematosus (SLE). Budoprutug has received FDA orphan drug designation for pMN and is the more advanced program, with Phase 2 (pMN), Phase 1b/2a (ITP), and Phase 1b (SLE) trials actively enrolling. The second candidate, CLYM116, is an anti-APRIL antibody licensed from Mabworks targeting IgA nephropathy, currently in Phase 1 healthy volunteer trials. Climb Bio outsources all drug manufacturing to CDMOs and operates as a small R&D organization. The company funds itself through capital markets and carries significant licensing obligations tied to both assets, including milestone payments and royalties owed to prior rights holders if either drug reaches commercialization.