A Cooperative Clinical Study of Abatacept in Multiple Sclerosis

MS is a chronic autoimmune disease in which blood cells that are supposed to protect the body
from infection mistakenly attack the body's own tissue. In MS, the target of this attack is a
protein called myelin that coats nerves throughout the body. Damage to this protective layer
can lead to loss of neurologic function.

There are a number of treatments available to MS patients. Interferon beta, Copaxone, and
other drugs can delay the worsening of the disease in some patients. For other patients, more
aggressive treatment with chemotherapy drugs such as cyclophosphamide or azathioprine are
needed. These drugs attempt to slow the disease by limiting the activity of the entire immune
system. Because of this, they can often have serious side effects.

This study evaluates the efficacy of abatacept in the treatment of relapsing-remitting MS. In
the first phase of the study, all participants will receive 8 intravenous treatments over a
period of 24 weeks. Then, if a participant remains eligible, they will enter the second phase
of the study and will receive another 8 treatments over the following 24 weeks. Two-thirds (2
out of 3) of participants will receive the study drug abatacept in the first phase, and then
an inactive form (placebo) of the drug in the second phase. The remaining one-third (1 in 3)
will get the placebo first, then the study drug in the second phase if they remain eligible.
Therefore, all participants in the ACCLAIM trial will have the opportunity to receive the
study drug abatacept if they remain healthy during the study. Participants will be asked to
return for a follow-up visit 12 weeks after all treatments have been completed.

Regular appointments scheduled during the trial will be used to monitor participants' health
and progress in the study. These appointments will include: physical and neurological exams,
blood tests and motor function assessments. A total of 11 magnetic resonance imaging (MRI)
procedures are scheduled during the study. The study medication and procedures related to the
study will be provided at no expense to the participant.

Inclusion Criteria:

- Clinically definite Relapsing-remitting Multiple Sclerosis (RRMS) meeting McDonald's
criteria

- Expanded Disability Status Scale (EDSS) scores between 0 and 5

- Active disease as defined by at least one of the following criteria:

1. One or more documented clinical exacerbations in the past year prior to visit -2

2. One or more gadolinium (Gd)-enhanced MRI lesions in the past year

- Willingness to forego available MS therapies

- Ability and willingness to provide informed consent and comply with study requirements
and procedures

Exclusion Criteria:

- Normal brain MRI at week -5 scan

- Females who are pregnant, intending pregnancy, or lactating, and unwilling to undergo
pregnancy testing

- Females who are unwilling to use approved methods of contraception for the duration of
the study

- Any chronic medical disease, other than MS, that compromises organ function

- Active infection

- Diagnosis of secondary or primary progressive MS

- Previous treatment with cyclophosphamide, mitoxantrone, cladribine, or rituximab at
any time

- Previous treatment with abatacept within the last 52 weeks prior to visit -2

- Previous treatment with systemic steroids, interferon, Copaxone, mycophenolate, or
other immunosuppressive medications within the last 4 weeks prior to visit -2

- Previous treatment with Natalizumab within the last 26 weeks prior to visit -2

- Previous vaccination with live vaccine, or previous treatment with fingolimod, within
the last 8 weeks prior to visit-2

- Diagnosis of malignancy other than basal cell carcinoma or cervical carcinoma in situ

- Claustrophobia or other contraindications to Gd-enhanced MRI

- Positive for human immunodeficiency virus (HIV) serology

- Positive for hepatitis B surface antigen (HBsAg)

- Positive for hepatitis C virus (HCV) serology

- Purified protein derivative (PPD)-tuberculin skin test result greater than 5 mm
induration

- Hemoglobin less than 10.5 gm/dL

- Platelets less than 100K/µL

- Absolute lymphocyte count less than 700 cells/μL

- Serum creatinine greater than 1.20 mg/dL

- eGFR (estimated glomerular filtration rate) less than 60 mL/min/1.73 m^2

- IgG anti-cardiolipin antibody greater than 15 GPL U/mL

- Previous participation in another interventional clinical trial within the past 4
weeks prior to visit -2

- Allergy or sensitivity to any component of abatacept

- The presence of any medical condition that the investigator deems incompatible with
participation in the trial