for people ages 18 years and up (full criteria)
at San Francisco, California and other locations
study started
estimated completion
Bruce Cree



To compare the efficacy of MEDI-551 versus placebo in reducing the risk of an NMO/NMOSD attack in subjects with NMO/NMOSD.

Official Title

A Double-masked, Placebo-controlled Study With Open-label Period to Evaluate the Efficacy and Safety of MEDI-551 in Adult Subjects With Neuromyelitis Optica and Neuromyelitis Optica Spectrum Disorders


MEDI-551 is a genetically engineered humanized monoclonal antibody that binds to the B cell specific surface antigen CD19 resulting in the depletion of B cells. CD19 positive (CD19+) B-lineage plasmablasts are responsible for the production of autoantibodies against the AQP4 channel protein.

The main objective of this study is to determine whether MEDI-551 compare to placebo decreases the risk of an attack in subjects with NMO/NMOSD.

This is a multicenter, multinational, randomized, double-masked, placebo controlled study with an open-label extension period to evaluate the efficacy and safety of intravenous (IV) MEDI-551 in adult subjects with NMO/NMOSD.

After a screening period, eligible subjects will enter a randomized-controlled period (RCP) of maximum 197 days where they will be randomized in a 3:1 ratio to receive either IV MEDI-551 or placebo. NMO/NMOSD attacks will be evaluated by the investigator and confirmed against the attack criteria by an independent Adjudication Committee (AC). Subjects for whom the attack was confirmed by the AC will be given the option to enroll into an open label period (OLP) with MEDI-551 treatment. Subjects who complete the RCP without experiencing an attack will be given the option to enroll into an OLP with MEDI-551 treatment. The OLP will continue for a minimum of 1 year and a maximum of 3 years after the last subject enter the OLP.

All subjects who discontinue from the RCP or the OLP will continue in a Safety Follow-up for a total of 12 months from last dose to evaluate the long-term safety of the investigational product.


Neuromyelitis Optica and Neuromyelitis Optica Spectrum Disorders NMO, NMOSD, Neuromyelitis Optica, Neuromyelitis Optica Spectrum Disorders, autoimmune, demyelination, MEDI-551, monoclonal antibody, Devic's syndrome, B-cell Neuromyelitis Optica Disease MEDI-551 MEDI551


You can join if…

Open to people ages 18 years and up

  1. Men and women 18 years or older with diagnosis of NMO/NMOSD
  2. Confirmation of NMO/NMOSD status:
  3. AQP4-IgG sero-positive NMO/NMOSD with at least one attack requiring rescue therapy in the last year or two attacks requiring rescue therapy in the last 2 years
  4. AQP4-IgG sero-negative NMO with at least one attack requiring rescue therapy in the last year or two attacks requiring rescue therapy in the last 2 years
  5. Able and willing to give written informed consent and comply with the requirements of the study protocol.
  6. EDSS <= 7.5 (8 in special circumstances)
  7. Men and women of reproductive potential must agree to use a highly effective method of birth control from screening to 6 months after final dose of the investigational product.

You CAN'T join if...

  1. Lactating and pregnant females
  2. Treatment with any investigational agent within 4 weeks of screening
  3. Known history of a severe allergy or reaction to any component of the investigational product formulation or history of anaphylaxis following any biologic therapy.
  4. Known active severe bacterial, viral, or other infection or any major episode of infection requiring hospitalization.
  5. History of alcohol, drug, or chemical abuse, or a recent history of such abuse < 1 year prior to randomization
  6. Receipt of the following at any time prior to randomization:
  7. Alemtuzumab
  8. Total lymphoid irradiation
  9. Bone marrow transplant
  10. T-cell vaccination therapy
  11. Receipt of rituximab or any experimental B-cell depleting agent within 6 months prior screening and B-cells below the lower limit of normal.
  12. Receipt of IVIG within 1 month prior to randomization.
  13. Receipt of any of the following within 3 months prior to randomization:
  14. Natalizumab (Tysabri®)b.
  15. Cyclosporin
  16. Methotrexate
  17. Mitoxantrone
  18. Cyclophosphamide
  19. Tocilizumab
  20. Eculizumab
  21. . History of Hepatitis B and/or Hepatitis C (Hep B/C at screening)
  22. . Known history of a primary immunodeficiency (congenital or acquired) or an underlying condition such as human immunodeficiency virus (HIV) infection
  23. . History of malignancies, apart from squamous cell or basal cell carcinoma of the skin treated with documented success of curative therapy > 3 months prior to randomization
  24. . Any concomitant disease other than NMO/NMOSD that required treatment with oral or intravenous steroids at doses over 20 mg a day for over 21 days


  • Research Site
    San Francisco California 94158 United States
  • Research Site
    Sacramento California 95817 United States

Lead Scientist

  • Bruce Cree
    Bruce Cree, MD, PhD, MAS is a Professor of Clinical Neurology and is the George A. Zimmermann Endowed Professor in Multiple Sclerosis in the Department of Neurology at the University of California San Francisco. Dr. Cree completed his MD and PhD in Biochemistry at UCSF. His neurology residency training was at Columbia University.


in progress, not accepting new patients
Start Date
Completion Date
MedImmune LLC
Phase 2/3
Study Type
Last Updated