Climb Bio (CLYM) R&D Spotlight: Budoprutug and the CD19 Opportunity summary

Pipeline overview and program updates

• Budoprutug, a differentiated anti-CD19 monoclonal antibody, is advancing in primary membranous nephropathy (pMN/PMN), immune thrombocytopenia (ITP), and systemic lupus erythematosus (SLE), with Fast Track and Orphan Drug Designations for PMN.

• CLYM116, a next-generation anti-APRIL antibody, is in two parallel phase I studies for IgA nephropathy, with data to be presented at the European Renal Association meeting in June and initial Phase 1 data expected mid-2026.

• Budoprutug's subcutaneous formulation completed a healthy volunteer study, showing robust B-cell depletion and similar tolerability to IV, supporting further development.

• Multiple clinical readouts are anticipated in 2026 across both clinical-stage programs.

• The PRISM phase II trial for pMN is enrolling globally, targeting doses up to 1,000 mg to maximize B-cell depletion.

Clinical trial data and development milestones

• Budoprutug achieved complete peripheral B-cell depletion and clinical remission in all five patients in a phase 1b pMN study, with durable responses up to three years.

• The PRISM/PrisMN phase II study in PMN is ongoing, with biomarker-driven dose selection and initial data from the low-dose cohort expected Q4 2026.

• The ITP trial has completed enrollment in the first two cohorts, with initial B-cell and platelet response data from the 250 mg cohort to be presented in June 2026 and additional data by year end.

• Global and China SLE studies are underway, with initial data from low-dose cohorts expected Q4 2026 and first patient in China on track for Q2 2026.

• Subcutaneous budoprutug showed robust B-cell depletion (~80%) and favorable safety in healthy volunteers.

R&D strategy and innovation priorities

• Focused on differentiated monoclonal antibodies against validated B-cell targets in autoimmune diseases with high unmet need, especially kidney health.

• Leveraging clinically validated B-cell targets and proven mAb modalities for scalable, community-based therapies.

• Parallel development across multiple indications to inform optimal dosing and long-term disease control.

• High-sensitivity B-cell assays and translational studies are being used to refine dose selection and biomarker endpoints.

• Ongoing studies are designed to define optimal dosing, depth of B-cell depletion, and potential for long-term disease control.