A Phase 1 Study of MEDI7734 in Type I Interferon-Mediated Autoimmune Diseases

MEDI7734 is a human monoclonal antibody that binds to and causes temporary depletion of
plasmacytoid dendritic cells (pDCs), a type of white blood cell. The objectives of this study
are to evaluate the safety, drug levels, and pDC levels in subjects who are given a single
injection of MEDI7734 or a placebo.

The study will be conducted in subjects with at least one of the five following autoimmune
diseases: dermatomyositis, polymyositis, Sjogren's syndrome, systemic lupus erythematosus, or
systemic sclerosis.

After a screening period, subjects will be randomized in a 3:1 ratio to receive a single dose
of MEDI7734 or matching placebo, administered as a subcutaneous (under the skin) injection.
After that, subjects will be evaluated periodically at the study site over at least the next
85 days.

Key Inclusion Criteria:

1. Age 18-65 years old

2. Diagnoses of dematomyositis, polymyositis, Sjogren's syndrome, systemic lupus
erythematosus and/or systemic sclerosis based on standard criteria.

3. Weight 40-120kg

4. Stable disease such that in the opinion of the investigator it is unlikely that a
change in subject's therapeutic regimen would be required during the subsequent 3
months.

Key Exclusion Criteria:

1. History of a hypersensitivity reaction or anaphylaxis to a previous mAb or human
immunoglobulin therapy.

2. Chronic hepatitis B, chronic hepatitis C, or HIV infection.

3. History of latent or active tuberculosis (TB), or a positive QuantiFERON®-TB Gold test
at screening.

4. Herpes zoster infection within 3 months before randomization

5. Any of the following medications within 6 months of Day 1: cyclophosphamide,
leflunomide > 20 mg/day, abatacept.

6. Receipt of a mAb within 5 published half-lives prior to Day 1.

7. Receipt of rituximab or an experimental B-cell depleting mAb within 6 months of Day 1.

8. Receipt of rituximab or an experimental B-cell depleting mAb without return of CD19 or
CD20 count to above the lower limit of normal.

9. Receipt of alemtuzumab, bone marrow transplantation, stem cell transplantation, total
lymphoid irradiation, or T-cell vaccination therapy -