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Obexelimab

Phase 3

IgG4 Related Disease | Small molecule | Rare Disease |Zenas BioPharma, Inc.|Last Updated: Aug 18, 2026

Target and mechanism

Molecular targetCD19, FCGR2B
Target classInhibitor
ModalitySmall molecule

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLEDDMC
Total Trials1
Total Enrollment194

FDA Designations

No designations recorded

Clinical trial landscape

Obexelimab · 4 trials · 4 indications

Phase 3 2Phase 2 2
NCT05786573A Study of Obexelimab in Patients With Warm Autoimmune Hemolytic Anemia (SApHiAre)Warm Autoimmune Hemolytic Anemia
ACTIVE NOT_RECRUITING134 Analytics
NCT05662241A Phase 3 Study of Obexelimab in Patients With IgG4-Related DiseaseIgG4 Related Disease
ACTIVE NOT_RECRUITING194 Analytics
PHASE3ACTIVE NOT_RECRUITING
A Study of Obexelimab in Patients With Warm Autoimmune Hemolytic Anemia (SApHiAre)
Warm Autoimmune Hemolytic AnemiaUnlock trial analytics
PHASE3ACTIVE NOT_RECRUITING
A Phase 3 Study of Obexelimab in Patients With IgG4-Related Disease
IgG4 Related DiseaseUnlock trial analytics

Study Endpoints

Primary Endpoints

Safety and Dose Confirmation Run-in Period (SRP)
24 weeks

Proportion of participants with hemoglobin (Hgb) ≥ 10 g/dL and ≥ 2 g/dL increase from Baseline with no use of blood transfusion or glucocorticoid (GC) rescue therapy.

Randomized Control Period (RCP)
24 weeks

Proportion of participants who achieve a durable Hgb response (defined as Hgb ≥ 10 g/dL and ≥ 2 g/dL increase from Baseline on at least 3 of 4 consecutive available visits), at the earliest on or after Week 12, with no use of blood transfusion or GC rescue therapy prior to attaining durable response through Week 24.

Primary outcome measure
Randomization to Week 52

Time to first IgG4-RD flare, defined as the reappearance of previous signs/symptoms or appearance of new signs/symptoms of IgG4-RD that requires initiation of rescue therapy in the opinion of the investigator and the Adjudication Committee (AC), from randomization to Week 52.

Cumulative number of new GdE T1 hyperintense lesions
Week 8 and Week 12

Cumulative number of new GdE T1 hyperintense lesions as measured by brain MRI

Secondary Endpoints

Secondary Outcome Measures
24 weeks
Number of T2 Lesions
Week 8 and Week 12
Number of GdE T1 lesions
Week 4, Week 8, and Week 12
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Study Design & Arms

AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Safety and Dose Confirmation Run-in Period (SRP): ObexelimabEXPERIMENTALObexelimab will be administered as an SC injection for 24 weeks.
Randomized Control Period (RCP): ObexelimabEXPERIMENTALObexelimab will be administered as an SC injection for 24 weeks.
Randomized Control Period (RCP): PlaceboPLACEBO_COMPARATORPlacebo will be administered as an SC injection for 24 weeks
ZB012EXPERIMENTALObexelimab administered as an SC injection.
PlaceboPLACEBO_COMPARATORPlacebo administered as an SC injection.
ObexelimabEXPERIMENTALObexelimab will be administered as a subcutaneous injection for 24 weeks.

Interventions

NameTypeDescription
ObexelimabDRUGObexelimab is a monoclonal antibody that simultaneously binds CD19 and FcγRIIb, resulting in down regulation of B cell activity.
PlaceboOTHERPlacebo
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites7

Inclusion Criteria: 1. Males and females, ≥ 18 years of age 2. Clinically diagnosed with wAIHA for at least 3 months and currently receiving treatment for wAIHA or have previously received treatment for wAIHA. 3. Diagnosis of primary or secondary wAIHA documented by a positive direct antiglobulin t...

Countries:ItalyPolandSpainTaiwanUnited KingdomUnited StatesArgentinaCanadaChinaFranceGermanyJapanMexicoSouth KoreaTurkey (Türkiye)BelgiumBulgariaDenmarkGreecePortugalPuerto RicoRomaniaSouth AfricaAustriaCroatiaCzechia
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Recent Changes (Last 90 Days)

MEDIUMAug 18, 2026NCT06559163Status: RECRUITING → ACTIVE_NOT_RECRUITING
MEDIUMAug 18, 2026NCT06559163Status: RECRUITING → ACTIVE_NOT_RECRUITING

Frequently asked questions about Obexelimab

What is Obexelimab used for?

Obexelimab is an investigational drug being developed for IgG4-related disease, warm autoimmune hemolytic anemia, systemic lupus erythematosus, and relapsing multiple sclerosis. It is currently in clinical trials for these conditions and is not yet approved by regulatory authorities.

What does Obexelimab target?

Obexelimab targets CD19 and FCGR2B, functioning as an inhibitor of these molecular targets. By engaging these proteins, the drug is designed to modulate B-cell activity, which is relevant to the autoimmune and inflammatory conditions it is being studied for.

Who makes Obexelimab?

Obexelimab is being developed by Zenas BioPharma, Inc., a biopharmaceutical company. The company's stock is traded under the ticker symbol ZBIO on the public markets.

What phase is Obexelimab in?

Obexelimab is in Phase 3 clinical trials for IgG4-related disease and warm autoimmune hemolytic anemia, and in Phase 2 trials for systemic lupus erythematosus and relapsing multiple sclerosis. It is an investigational drug still in clinical development and has not been approved.

What clinical trials is Obexelimab in?

Obexelimab is being studied in multiple trials, including NCT05662241 for IgG4-related disease, NCT05786573 for warm autoimmune hemolytic anemia, NCT06559163 for systemic lupus erythematosus, and NCT06564311 for relapsing multiple sclerosis. All trials are active but not recruiting participants.

Is Obexelimab the same as any other drug?

Obexelimab is the primary name for this investigational drug, and no alternative names have been reported. It is being studied under this name across all its clinical trials for various autoimmune conditions.