A Phase II, Randomized, Open-Label, Three-Arm Study Comparing Low- and High Dose Alemtuzumab and High-Dose Subcutaneous Interferon Beta-1a (Rebif®) in Patients With Early, Active Relapsing-Remitting Multiple Sclerosis

Inclusion Criteria:

- Signed informed consent form.

- Male or non-pregnant, non-lactating female patients, 18 to 50 years of age
(inclusive).

- Diagnosis of MS per McDonald's update of the Poser criteria, including cranial MRI
consistent with those criteria.

- Onset of first MS symptoms within 3 years prior to screening.

- EDSS score 0.0 to 3.0 (inclusive) at the screening and baseline visits.

- At least 2 completed clinical episodes of MS in the 2 years prior to study entry (ie,
the initial event if within 2 years of study entry plus ≥1 relapse, or ≥2 relapses if
the initial event was between 2 and 3 years prior to study entry).

- In addition to the clinical criteria (3 to 6 above), ≥1 enhancing lesion on any 1 of
the up to 4 screening gadolinium-enhanced MRI scans during a maximum 3-month run-in
period (inclusive of the Month 0 baseline scan).

Exclusion Criteria:

- Previous immunotherapy for MS other than steroids, including treatment with
interferons, intravenous immunoglobulin, glatiramer acetate, and mitoxantrone.

- Personal history of thyroid autoimmune disease.

- Personal history of clinically significant autoimmune disease (eg, inflammatory bowel
disease, diabetes, lupus, severe asthma).

- History of thyroid carcinoma (previous thyroid adenoma is acceptable and is not to be
considered an exclusion criterion).

- History of malignancy (except for basal cell skin carcinoma in which situation the
patient is eligible only if disease-free for more or equal to 5 years).

- Any disability acquired from trauma or another illness that, in the opinion of the
investigator, could interfere with evaluation of disability due to MS.

- Previous treatment with CAMPATH.

- History of anaphylaxis following exposure to humanized monoclonal antibodies.

- Inability to undergo MRI with gadolinium administration.

- Female patients with childbearing potential with a positive serum pregnancy test at
screening or baseline. (NB: Serum pregnancy testing will be performed on each
occasion.).

- Male and female patients who do not agree to use effective contraceptive method(s)
during the study.

- Impaired renal function (ie, serum creatinine larger or equal to 2 times the
Institutional upper limit of normal [ULN]).

- Untreated, major depressive disorder (MDD).

- Epileptic seizures that are not adequately controlled by treatment.

- Suicidal ideation.

- Major systemic disease or other illness that would, in the opinion of the
investigator, compromise patient safety or interfere with the interpretation of study
results.

- Abnormal CD4 count or significantly abnormal thyroid function; presence of anti-TSH
receptor antibodies; known seropositivity for HIV.

- Intolerance of pulsed corticosteroids, especially a history of steroid psychosis.

- Presence of a monoclonal paraprotein.

- Patients who, in the opinion of the investigator, have any form of MS other than
relapsing-remitting

- Patients currently participating in a clinical trial of an experimental or
unapproved/unlicensed therapy