Xencor Reports Early Rheumatoid Arthritis Improvements in Phase 1b Plamotamab Trial

• Xencor is presenting initial Phase 1b plamotamab results in rheumatoid arthritis at ACR Convergence 2026.
• Plamotamab produced deep B-cell depletion and preliminary disease activity improvements; multiple doses showed greater benefits than single doses.
• Treatment was well tolerated, with one mild cytokine release syndrome case; no immune effector cell-associated neurotoxicity syndrome occurred.
• Separately, Phase 1 XmAb657 data showed dose-dependent B-cell reductions in healthy participants, with a safety profile supporting further dose escalation.
• Another XmAb657 healthy-participant cohort is expected to finish by year-end 2026; enrollment of severe autoimmune disease patients is planned for first-quarter 2027.

Disclaimer: This news brief was created by Public Technologies (PUBT) using generative artificial intelligence. While PUBT strives to provide accurate and timely information, this AI-generated content is for informational purposes only and should not be interpreted as financial, investment, or legal advice. Xencor Inc. published the original content used to generate this news brief via Business Wire (Ref. ID: 20261109344749) on November 09, 2026, and is solely responsible for the information contained therein.