A Study of Obexelimab in Patients With Relapsing Multiple Sclerosis (MoonStone)

November 14, 2025 updated by: Zenas BioPharma (USA), LLC

A Phase 2, Multicenter, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Efficacy and Safety of Obexelimab in Patients With Relapsing Multiple Sclerosis

This study aims to examine the efficacy and safety of obexelimab in participants with relapsing multiple sclerosis

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Detailed Description

The study consists of a Screening Period (Day -28 to Day -1), a 24-week treatment period (Part A and Part B), a 52 week open label extension and an expected 12-week Follow-up Period. Patients with Relapsing Multiple Sclerosis will be randomized in 2:1 ratio to obexelimab or placebo. Randomization will be stratified by Gd lesion status at screening (≥ 1 vs 0).

Part A is the 12-week Randomized Placebo-Controlled Period (RCP), during which obexelimab or placebo will be administered as weekly subcutaneous (SC) injections. Following Part A, all patients will enter the Part B, a 12-week Open-Label Period (OLP), during which all patients will receive obexelimab administered as weekly SC injections. After Part B, patients will enter Part C, a 52-week Open-Label Extension (OLE), after which they will return for an in-clinic Safety Follow-Up Visit 12 weeks after the completion of Part C (i.e. Week 88). If at this time, B cells have not returned to baseline or above the lower limit of normal (LLN), patients will be asked to return every 12 weeks until B cells return to baseline or above the LLN (at minimum). The maximum expected duration of the study is 92 weeks (Screening Period = 4 weeks, Parts A, B and C = 76 weeks, Follow-up Period = 12 weeks).

Study Type

Interventional

Enrollment (Estimated)

93

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Austria
      • Vienna, Austria
        • Neuro-logisch Wien
  • Belgium
      • Overpelt, Belgium
        • Rehabilitation & MS Center, Noorderhart Hospital
      • Roeselare, Belgium
        • AZ Delta-Deltalaan 1
  • China
      • Beijing, China
        • Tiantan Hospital, Capital Medical University
      • Suzhou, China
        • The First Affiliation Hospital of Soochow University
      • Tianjin, China
        • Tianjin Medical University General Hospital
      • Wuhan, China
        • Tongji Hospital, Tongji Medical Center of HUST
      • Ürümqi, China
        • People's Hospital of Xinjiang Uyaur Autonomous Region
  • Croatia
      • Zagreb, Croatia
        • Klinicki bolnicki centar Zagreb
  • Czechia
      • Brno, Czechia
        • Fakultni nemocnice u sv. Anny v Brne
      • Jihlava, Czechia
        • Nemocnice Jihlava
      • Prague, Czechia
        • General University Hospital Praha
  • Denmark
      • Aalborg, Denmark
        • Aalborg Universitetshospital
  • Greece
      • Chaïdári, Greece
        • Attikon University General Hospital
      • Larissa, Greece
        • University General Hospital of Larissa
  • Italy
      • Cefalù, Italy
        • Fondazione Isituto G. Giglio di Cefalu
      • Florence, Italy
        • University of Florence
      • Pozzilli, Italy
        • Istituto Neurologico Mediterraneo Neuromed
      • Roma, Italy
        • Fondazione PTV Policlinico Tor Vergata
  • Poland
      • Bydgoszcz, Poland
        • Neurocentrum Bydgoszcz sp.z o.o.
      • Katowice, Poland
        • M.A. LEK A.M. Maciejowsy Spolka Cywilna
      • Lublin, Poland
        • Zanamed Medical Clinic Sp z o.o.
      • Zabrze, Poland
        • Wielospecjalistyczne Centrum Medyczne Ibismed
  • Spain
      • Madrid, Spain
        • Hospital General Universitario Gregorio Marañón
      • Madrid, Spain
        • Hospital Clinico San Carlos
      • Murcia, Spain
        • Hospital Universitario Virgen de la Arrixaca
      • Málaga, Spain
        • Hospital Regional Universitario de Málaga
      • Málaga, Spain
        • Hospital Regional Universitario de Malaga - Hospital General
      • Seville, Spain
        • Hospital Virgen Macarena
      • Valencia, Spain
        • Hospipal La Fe Valencia
  • United Kingdom
      • Leicester, United Kingdom
        • Leicester General Hospital
      • London, United Kingdom
        • Barts Health NHS Trust
      • Swansea, United Kingdom
        • Morriston Hospital
  • United States
    • Alabama
      • Cullman, Alabama, United States, 35058
        • North Central Neurology
    • Arizona
      • Phoenix, Arizona, United States, 85032
        • Center for Neurology and Spine
      • Scottsdale, Arizona, United States, 85253
        • Perseverance Research Center
    • California
      • West Hollywood, California, United States, 90048
        • Regina Berkovich MD PhD, Inc
    • Florida
      • Naples, Florida, United States, 35105
        • Aqualine Clinical Research
      • Tampa, Florida, United States, 33620
        • University of South Florida
    • Massachusetts
      • Worcester, Massachusetts, United States, 01655
        • University of Massachusetts Medical School
    • Minnesota
      • Plymouth, Minnesota, United States, 55446
        • Infusion Associates Plymouth
    • Missouri
      • St Louis, Missouri, United States, 63131
        • MS Center for Innovations in Care
    • New Jersey
      • Teaneck, New Jersey, United States, 07666
        • Holy Name Medical Center
    • Ohio
      • Columbus, Ohio, United States, 43235
        • Boster Center for MS
    • Texas
      • Plano, Texas, United States, 75024
        • North Texas Institute of Neurology and Headache
    • Wisconsin
      • Greenfield, Wisconsin, United States, 53228
        • Center for Neurological Disorders
      • Milwaukee, Wisconsin, United States, 53226
        • Medical College of Wisconsin

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Diagnosis of RMS (relapsing-remitting or secondary progressive with relapses) according to the 2017 revision of the McDonald diagnostic criteria
  2. An EDSS of ≤ 5.5 at the Screening Visit

  3. Must have documentation of:

    1. . at least 1 relapse within the previous year OR
    2. . ≥ 2 relapses within the past 2 years OR
    3. . ≥ 1 active Gd-enhancing brain lesion on an MRI scan within the past 6 months prior to screening
  4. Not of childbearing potential or willing to follow contraceptive guidance

Exclusion Criteria:

  1. Primary progressive MS or secondary progressive MS without relapses
  2. Meet criteria for neuromyelitis optica spectrum disorder
  3. Relapse in the 30 days prior to randomization
  4. ≥ 10 years disease duration from onset with patient's EDSS ≤ 2.0 (patient reported is adequate in absence of written medical record)
  5. Has > 20 Gd+ lesions on brain MRI at screening

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Placebo Comparator: Placebo
Placebo will be administered as a subcutaneous injection for 12 weeks
Drug: Placebo
Placebo
Experimental: Obexelimab
Obexelimab will be administered as a subcutaneous injection for 76 weeks
Drug: Obexelimab
Obexelimab is a monoclonal antibody that simultaneously binds CD19 and FcyRIIb, resulting in down regulation of B cell activity

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Cumulative number of new GdE T1 hyperintense lesions
Time Frame: Week 8 and Week 12
Cumulative number of new GdE T1 hyperintense lesions as measured by brain MRI
Week 8 and Week 12

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Number of T2 Lesions
Time Frame: Week 8 and Week 12
cumulative number of new and/or enlarging T2 weighted hyperintense lesions
Week 8 and Week 12
Number of GdE T1 lesions
Time Frame: Week 4, Week 8, and Week 12
number of new GdE T1 hyperintense lesions
Week 4, Week 8, and Week 12
Volume of T2 lesions
Time Frame: Week 12
change from baseline in volume of T2 lesions
Week 12
Serum NfL
Time Frame: Week 12
serum NfL
Week 12
Incidence of Adverse Events, injection site reactions and hypersensitivity reactions
Time Frame: 24 weeks
Incidence of Adverse Events, injection site reactions and hypersensitivity reactions, serious adverse events, and adverse events of special interest, as defined by the CTCAE v5.0
24 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Zenas BioPharma (USA), LLC

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

August 26, 2024

Primary Completion (Actual)

August 28, 2025

Study Completion (Estimated)

February 1, 2026

Study Registration Dates

First Submitted

August 19, 2024

First Submitted That Met QC Criteria

August 19, 2024

First Posted (Actual)

August 21, 2024

Study Record Updates

Last Update Posted (Actual)

November 17, 2025

Last Update Submitted That Met QC Criteria

November 14, 2025

Last Verified

June 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • ZB012-02-002

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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