TJ Bio's Plonmarlimab Hits 83.3% Response Rate in Phase 2 MAS Trial
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HANGZHOU – November 04, 2026 -- TJ Biopharma's GM-CSF antibody plonmarlimab achieved an 83.3% overall response rate at Week 8 in the Phase 2 PRIME-1 study of macrophage activation syndrome (MAS), according to results now published in the Journal of Hematology & Oncology.
PRIME-1 enrolled 18 patients who had failed high-dose glucocorticoids
The open-label, single-arm, multi-center study treated patients who were refractory to, or had relapsed after, high-dose glucocorticoid therapy. Fifteen of 18 patients achieved a complete or partial response. Median time to response was 2.1 weeks, with the earliest response recorded on Day 5.