Zenas BioPharma (ZBIO) FDA Approvals

Zenas BioPharma's Drug in the FDA Approval Process

This section highlights FDA-related milestones and regulatory updates for drugs developed by Zenas BioPharma (ZBIO). Over the past two years, Zenas BioPharma has reported clinical trial outcomes, regulatory submissions, approvals, and other FDA events for drugs and therapies such as Obexelimab. For definitions of regulatory abbreviations such as NDA, BLA, or PDUFA, see the event status legend.

Obexelimab FDA Regulatory Timeline and Events

Obexelimab is a drug developed by Zenas BioPharma for the following indication: Immunoglobulin G4-Related Disease (IgG4-RD). This drug is under review by the U.S. Food and Drug Administration (FDA). Below is a timeline of key regulatory milestones for this therapy.

Results - February 9,2026

Phase 2

• Drug: Obexelimab
• Announced Date: February 9, 2026
• Indication: Immunoglobulin G4-Related Disease (IgG4-RD)

Zenas BioPharma, Inc. announced that results from the Phase 2 MoonStone trial of obexelimab in Relapsing Multiple Sclerosis (RMS) were presented in a late-breaking oral presentation at the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) Forum 2026, which took place from February 5-7, 2026 in San Diego, California.

Zenas BioPharma, Inc. announced that results from the Phase 2 MoonStone trial of obexelimab in relapsing multiple sclerosis (RMS) were presented as a late‑breaking oral presentation at the ACTRIMS Forum 2026, held February 5–7 in San Diego. The data highlight obexelimab’s clinical activity and profile in RMS.

Obexelimab met the trial’s primary endpoint, producing a 95% relative reduction in new gadolinium‑enhancing T1 lesions versus placebo over weeks 8 and 12 (p = 0.0009). Separately reported 24‑week data support the drug’s robust and durable activity and further validate its unique inhibitory mechanism of action.

Obexelimab was well tolerated in the study, with no new safety signals observed. The Zenas BioPharma word mark, logo mark, and the “lightning bolt” design are trademarks of Zenas BioPharma, Inc. or its affiliated companies.

Positive Results - January 5,2026

Phase 3

• Drug: Obexelimab
• Announced Date: January 5, 2026
• Indication: Immunoglobulin G4-Related Disease (IgG4-RD)

Zenas BioPharma, Inc. announced positive results from the Phase 3 INDIGO trial of obexelimab in Immunoglobulin G4-Related Disease (IgG4-RD). Obexelimab met the primary endpoint, demonstrating a highly statistically significant and clinically meaningful 56% reduction in the risk of IgG4-RD flare compared to placebo (Hazard Ratio 0.44, p=0.0005) during the 52-week randomized placebo-controlled period.

Zenas BioPharma reported positive Phase 3 INDIGO results for obexelimab in Immunoglobulin G4‑Related Disease (IgG4‑RD). In a 194‑patient, 52‑week randomized placebo‑controlled trial, obexelimab met the primary endpoint, cutting the risk of IgG4‑RD flare by 56% versus placebo (hazard ratio 0.44, p=0.0005).

Obexelimab also showed statistically significant benefit on all four key secondary endpoints: investigator‑assessed flares, number of flares requiring rescue therapy, proportion of patients achieving complete remission, and cumulative use of rescue therapy. The drug was well tolerated with no new safety signals; infection rates, including Grade 3 infections, were lower on obexelimab and injection‑site reactions were similar between arms.

Zenas expects to submit a Biologics License Application (BLA) to the FDA in Q2 2026 and a Marketing Authorization Application (MAA) to the EMA in the second half of 2026. The company will discuss the results on a conference call today, January 5, 2026, at 8:00 a.m. ET.Read Announcement

Positive Results - October 27,2025

Phase 2

• Drug: Obexelimab
• Announced Date: October 27, 2025
• Indication: Immunoglobulin G4-Related Disease (IgG4-RD)

Zenas BioPharma, Inc. announced positive results from the Phase 2 MoonStone trial of obexelimab in Relapsing Multiple Sclerosis (RMS).

Zenas BioPharma announced positive Phase 2 MoonStone trial results for obexelimab in relapsing multiple sclerosis (RMS). The trial met its primary endpoint, showing a 95% relative reduction in new gadolinium-enhancing T1 lesions over weeks 8 and 12 compared with placebo (p=0.0009). Patients receiving obexelimab averaged 0.01 new lesions per scan versus 0.23 in the placebo group, indicating near-complete suppression of active inflammation.

The randomized, double-blind trial enrolled 116 RMS patients who received weekly subcutaneous injections of 250 mg obexelimab or placebo over 12 weeks. Obexelimab also significantly lowered the cumulative number of new or enlarging T2 lesions, a measure of chronic disease burden. The safety profile was consistent with prior studies, with mostly mild injection site reactions and some infections.

Obexelimab is a bifunctional antibody targeting CD19 and FcγRIIb on B cells without depleting them. Zenas will report 24-week MoonStone data in Q1 2026, including secondary and exploratory endpoints on disability progression, to guide future development in RMS and other autoimmune diseases.

Clinical Update - February 5,2025

• Drug: Obexelimab
• Announced Date: February 5, 2025
• Indication: Immunoglobulin G4-Related Disease (IgG4-RD)

Zenas BioPharma, Inc announced its 2024 accomplishments, outlined its key business objectives for 2025 and announced preliminary unaudited cash balance as of year-end 2024.

Zenas BioPharma, Inc. announced key milestones from 2024 and shared important goals for 2025. The company highlighted its accomplishments this past year as it advanced multiple clinical trials of its lead product candidate, obexelimab, for treating autoimmune diseases. For 2025, Zenas plans to hit major value-driving targets, including pivotal Phase 2 and Phase 3 trial results. The company is preparing for topline data from its Phase 2 trial in relapsing multiple sclerosis and Phase 3 trial in IgG4-related disease by the end of 2025. Additionally, the enrollment for a Phase 2 trial in systemic lupus erythematosus is expected to complete in 2025. Zenas also announced that its preliminary unaudited cash balance stands at roughly $350 million at the end of 2024, which is expected to fund operations and capital needs through the fourth quarter of 2026.