Climb Bio, Inc. 8-K

What Happened

• Climb Bio (CLYM) announced initial data (filed 8-K on June 11, 2026) from the Phase 1b portion of its Phase 1b/2a study (NCT07043946) of budoprutug, an anti‑CD19 monoclonal antibody, in adults with primary immune thrombocytopenia (ITP). As of June 1, 2026, 15 patients were enrolled across the 250 mg (n=6) and 500 mg (n=9) intravenous dose cohorts; enrollment in the 1,000 mg cohort is ongoing.

Key Details

• Trial design: three ascending IV dose levels (250 mg, 500 mg, 1,000 mg), two doses given 14 days apart in adults with ITP who had at least one prior therapy.
• Safety: budoprutug was generally well tolerated at 250 mg and 500 mg — no serious adverse events, no treatment discontinuations for adverse events, no infusion‑related reactions; all reported AEs were Grade 1–2.
• Efficacy signals (250 mg cohort): mean B‑cell depletion >90% by Week 4; mean platelet increase of 111,000/µL at Week 24; durable platelet responses in 4 of 6 patients, with 2 of 6 maintaining ≥100 x 10^3/µL for over 24 weeks.
• Prior therapy context: patients were heavily pretreated (median 6–7.5 prior lines; disease duration 0.5–40 years). Of four patients previously treated with rituximab, three responded to budoprutug, including two durable complete responses.
• Timeline: company expects to announce additional data from the study by year‑end 2026.

Why It Matters

• The early data show a favorable safety profile and initial signs of biological activity (B‑cell depletion) and platelet responses in a heavily pretreated ITP population — findings that support continued clinical evaluation and dose selection. For investors, these results reduce early clinical risk for budoprutug but are preliminary; the company is advancing the trial (including a 1,000 mg cohort) and plans additional data updates by year‑end 2026.