The primary reason for this amendment was to extend the contraception requirement from 30 days after the last dose of study treatment through the Final Safety Follow-Up Visit 12 weeks after the last dose of study treatment.

The primary reasons for this amendment were to: - Open the study in the Czech Republic and Poland in addition to Japan, South Korea, and Taiwan. Although China was originally included, the study was withdrawn from China prior to study approval in that country. The title of the study was updated to reflect these changes. - Recommend that visits for female subjects be scheduled when the subject was not menstruating as a precaution against contamination of urine samples. - Anti-APQ4 antibody testing was to occur at the first Relapse Assessment Visit but was not required at any subsequent Relapse Assessment Visit. - Weight was added as an assessment at the End of Study/Premature Withdrawal/Final Safety Follow-Up Visit. - Clarify that MRI was not to be performed within 28 days after completing a course of steroids. - Clarify that if a subject had positive urinalysis test at Screening and the etiology was known (e.g., due to menses or urinary tract infection in the case of hematuria, or due to recent steroid use or elevated serum glucose in the case of glycosuria), a repeat test was not required.

The primary reasons for this amendment were to: - Enable the early identification of subjects in Parts I or II who are at risk for developing severe, prolonged lymphopenia, and to provide additional guidance on the management of such subjects. In addition, lymphocyte and subset counts have been supplemented as an exploratory endpoint with the objective to study the impact of BG00012 treatment on lymphocytes and the recovery of lymphocyte count in patients with lymphopenia. - Extend the duration of study participation from 28 or 40 weeks to 28 to 52 weeks to reflect the additional safety follow-up for subjects with abnormally low lymphocyte counts. Subjects who completed Part I and did not enroll in Part II of the study or subjects who permanently discontinued study treatment for any reason and had a lymphocyte count <LLN were to be followed until the lymphocyte count was ≥LLN or until 24 weeks after the last dose (whichever was sooner). - Clarify that the use of alternative MS therapies was allowed only after the Investigators had contacted Biogen or its designee to determine their necessity in subjects who completed Part I and did not enroll in Part II of the study or subjects who permanently discontinued study treatment. - Country was added as a covariate for the statistical modelling of additional endpoints to be consistent with the analysis of the primary and secondary endpoints. - If lymphocyte count remains <500/mm3 for ≥24 weeks consecutively, study treatment will be permanently discontinued, and recovery of lymphocytes will be followed.