Oral Cladribine in Early Multiple Sclerosis (MS)

Inclusion Criteria

• Male or female between 18 and 55 years old, inclusive
• Weighed between 40 to 120 kilogram (kg), inclusive
• Participant has experienced a single, first clinical event suggestive of MS within 75 days prior to the Screening visit, (clock starts 24 hours after onset). The event must be a new neurological abnormality present for at least 24 hours, either mono- or polysymptomatic
• Participant has at least two clinically silent lesions on the T2-weighted MRI scan, at screening, with a size of at least 3 millimeter (mm), at least one of which is ovoid or periventricular or infratentorial on screening MRI
• Participant has EDSS 0 - 5.0 at Screening
• Participant has no medical history or evidence of latent tuberculosis infection (LTBI) or active tubercular disease, as evidenced by the Mantoux tuberculosis (TB) skin test or a comparable sensitive test according to local regulations/guidelines (if the Mantoux test is not available), and/or a chest X-ray
• Participant has normal hematological parameters at Screening, as defined by the central laboratory that performed all the assessments
• If female, she must:
• be neither pregnant nor breast-feeding, nor attempting to conceive and
• use a highly effective method of contraception throughout the entire duration of the study and for 90 days following completion of the last dose of study medication. A highly effective method of contraception is defined as those which result in a low failure rate (that is less than 1 percent per year) when used consistently and correctly such as implants, injectables, combined oral contraceptives, some intrauterine devices, sexual abstinence or vasectomized partner, or
• be post-menopausal or surgically sterilized (Note: for Danish sites only, participants should use a hormonal contraceptive or intrauterine device for the duration of the trial)
• Male participants must be willing to use contraception to avoid impregnating partners throughout the study, and for 90 days following the last dose of study medication
• Be willing and able to comply with study procedures for the duration of the study
• Participant has to provide written informed consent voluntarily, including, for United states of America (USA), participant authorization under Health Insurance Portability and Accountability Act (HIPAA), prior to any study-related procedure that is not part of normal medical care
• Participant has refused any treatment already available for clinically isolated syndrome (CIS) such as interferons or glatiramer acetate, at the time of entry into the Initial Treatment Period of this study

Exclusion Criteria

• Participant has a diagnosis of MS (per McDonald criteria, 2005)
• Participant has any other disease that could better explain the participant's signs and symptoms
• Participant has complete transverse myelitis or bilateral optic neuritis
• Participant using or has used any other approved MS disease modifying drug (DMD)
• Participant has used any investigational drug or undergone an experimental procedure within 12 weeks prior to Study day 1
• Participant received oral or systemic corticosteroids or adrenocorticotropic hormone (ACTH) within 30 days prior to screening MRI. The MRI had to be performed 30 days after the oral or systemic corticosteroids or ACTH treatment. In case this interfered with MRI timing the screening period could be extended accordingly.
• Participant has abnormal total bilirubin, or aspartate aminotransferase (AST) or alanine aminotransferase (ALT) or alkaline phosphatase greater than 2.5 times the upper limit of normal
• Participant suffered from current autoimmune disease other than MS
• Participant suffered from psychiatric illness (including history of, or concurrent, severe depressive disorders and/or suicidal ideation) that in the opinion of the investigator creates undue risk to the participant or could affect compliance with the study protocol
• Participant suffered from major medical illness such as cardiac