Obexelimab - (SunStone)

Nov. 12, 2025: Zenas BioPharma, Inc. (NASDAQ: ZBIO) reported Q3 2025 results and provided pipeline/business updates focused on autoimmune programs.

Obexelimab:

• IgG4-Related Disease (IgG4-RD): Topline results from the Phase 3 INDIGO global, randomized, double-blind, placebo-controlled registration-directed trial are expected around year-end 2025.
• Relapsing MS (RMS): Reported “highly positive” 12-week Phase 2 MoonStone topline data; obexelimab met the primary endpoint with a 95% relative reduction vs placebo in cumulative new gadolinium-enhancing T1 hyperintense lesions over weeks 8 and 12 (p=0.0009). Safety was consistent with prior trials; infections and hypersensitivity were noted, most commonly mild injection-site reactions. 24-week data are expected in Q1 2026.
• Systemic lupus erythematosus (SLE): Phase 2 SunStone continues enrolling; enrollment completion expected around year-end 2025, with topline results expected mid-2026.
• Financing: Entered a Royalty Pharma agreement for up to $300M ($75M upfront plus three $75M payments tied to INDIGO success criteria, FDA approval in IgG4-RD, and FDA approval in SLE), in exchange for a 5.5% royalty on worldwide net sales and other payments in partnered geographies.

Orelabrutinib (BTK inhibitor):

• Zenas licensed global rights (excluding Greater China/Southeast Asia; non-oncology) from InnoCare Pharma, and also obtained rights to ZB021 (oral IL-17AA/AF inhibitor) and ZB022 (oral, brain-penetrant TYK2 inhibitor).
• Initiated a Phase 3 PPMS trial in Q3 2025; a Phase 3 SPMS trial is expected to start in Q1 2026.

Financing/financials: Announced a $120.0M private placement (completed Oct. 2025). Cash/cash equivalents/investments were $301.6M as of Sept. 30, 2025. Net loss was $51.5M for Q3 2025.