In the Treatment Period, participants received placebo as IV infusion on Days 1 and 15 of Cycle 1 ( 1 Cycle = 168 days ), followed by ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 2. Participants then received ocrelizumab, 600 mg, IV, on Day 1 of Cycles 3 and 4. Participants who completed the TP then entered the TFP which was of variable duration. Participants who completed the TP and the TFP (at least through Week 120) and opted to enroll in the OLE period received ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 5 followed by a single infusion of ocrelizumab, 600 mg, Q24W.

In the Treatment Period, participants received ocrelizumab 300 mg as IV infusion on Days 1 and 15 of Cycle 1 ( 1 Cycle = 168 days ), followed by ocrelizumab, 600 mg, IV, on Day 1 and placebo IV on Day 15 of Cycle 2. Participants then received ocrelizumab, 600 mg, IV, on Day 1 of Cycles 3 and 4. Participants who completed the TP then entered the TFP which was of variable duration. Participants who completed the TP and the TFP (at least through Week 120) and opted to enroll in the OLE period received ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 5 followed by a single infusion of ocrelizumab, 600 mg, Q24W.

In the Treatment Period, participants received ocrelizumab 1000 mg as IV infusion on Days 1 and 15 of Cycle 1 ( 1 Cycle = 168 days ), followed by ocrelizumab, 1000 mg IV, on Day 1 and placebo IV on Day 15 of Cycle 2. Participants then received ocrelizumab, 1000 mg, IV, on Day 1 of Cycle 3 and ocrelizumab, 600 mg, IV, on Day 1 of Cycle 4. Participants who completed the TP then entered the TFP which was of variable duration. Participants who completed the TP and the TFP (at least through Week 120) and opted to enroll in the OLE period received ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 5 followed by a single infusion of ocrelizumab, 600 mg, Q24W.

In the Treatment Period, participants received Avonex 30 mcg as IM injection once every week of Cycle 1 ( 1 Cycle = 168 days ), followed by ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 2. Participants then received ocrelizumab, 600 mg, IV, on Day 1 of Cycles 3 and 4. Participants who completed the TP then entered the TFP which was of variable duration. Participants who completed the TP and the TFP (at least through Week 120) and opted to enroll in the OLE period received ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 5 followed by a single infusion of ocrelizumab, 600 mg, Q24W.

Van Elteren test is stratified by region and presence of baseline gadolinium-enhancing lesions (absent or present).

Van Elteren test is stratified by region and presence of baseline gadolinium-enhancing lesions (absent or present).

In the Treatment Period, participants received placebo as IV infusion on Days 1 and 15 of Cycle 1 ( 1 Cycle = 168 days ), followed by ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 2. Participants then received ocrelizumab, 600 mg, IV, on Day 1 of Cycles 3 and 4. Participants who completed the TP then entered the TFP which was of variable duration. Participants who completed the TP and the TFP (at least through Week 120) and opted to enroll in the OLE period received ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 5 followed by a single infusion of ocrelizumab, 600 mg, Q24W.

In the Treatment Period, participants received ocrelizumab 300 mg as IV infusion on Days 1 and 15 of Cycle 1 ( 1 Cycle = 168 days ), followed by ocrelizumab, 600 mg, IV, on Day 1 and placebo IV on Day 15 of Cycle 2. Participants then received ocrelizumab, 600 mg, IV, on Day 1 of Cycles 3 and 4. Participants who completed the TP then entered the TFP which was of variable duration. Participants who completed the TP and the TFP (at least through Week 120) and opted to enroll in the OLE period received ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 5 followed by a single infusion of ocrelizumab, 600 mg, Q24W.

In the Treatment Period, participants received placebo as IV infusion on Days 1 and 15 of Cycle 1 ( 1 Cycle = 168 days ), followed by ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 2. Participants then received ocrelizumab, 600 mg, IV, on Day 1 of Cycles 3 and 4. Participants who completed the TP then entered the TFP which was of variable duration. Participants who completed the TP and the TFP (at least through Week 120) and opted to enroll in the OLE period received ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 5 followed by a single infusion of ocrelizumab, 600 mg, Q24W.

In the Treatment Period, participants received ocrelizumab 300 mg as IV infusion on Days 1 and 15 of Cycle 1 ( 1 Cycle = 168 days ), followed by ocrelizumab, 600 mg, IV, on Day 1 and placebo IV on Day 15 of Cycle 2. Participants then received ocrelizumab, 600 mg, IV, on Day 1 of Cycles 3 and 4. Participants who completed the TP then entered the TFP which was of variable duration. Participants who completed the TP and the TFP (at least through Week 120) and opted to enroll in the OLE period received ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 5 followed by a single infusion of ocrelizumab, 600 mg, Q24W.

In the Treatment Period, participants received placebo as IV infusion on Days 1 and 15 of Cycle 1 ( 1 Cycle = 168 days ), followed by ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 2. Participants then received ocrelizumab, 600 mg, IV, on Day 1 of Cycles 3 and 4. Participants who completed the TP then entered the TFP which was of variable duration. Participants who completed the TP and the TFP (at least through Week 120) and opted to enroll in the OLE period received ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 5 followed by a single infusion of ocrelizumab, 600 mg, Q24W.

In the Treatment Period, participants received ocrelizumab 300 mg as IV infusion on Days 1 and 15 of Cycle 1 ( 1 Cycle = 168 days ), followed by ocrelizumab, 600 mg, IV, on Day 1 and placebo IV on Day 15 of Cycle 2. Participants then received ocrelizumab, 600 mg, IV, on Day 1 of Cycles 3 and 4. Participants who completed the TP then entered the TFP which was of variable duration. Participants who completed the TP and the TFP (at least through Week 120) and opted to enroll in the OLE period received ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 5 followed by a single infusion of ocrelizumab, 600 mg, Q24W.

In the Treatment Period, participants received placebo as IV infusion on Days 1 and 15 of Cycle 1 ( 1 Cycle = 168 days ), followed by ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 2. Participants then received ocrelizumab, 600 mg, IV, on Day 1 of Cycles 3 and 4. Participants who completed the TP then entered the TFP which was of variable duration. Participants who completed the TP and the TFP (at least through Week 120) and opted to enroll in the OLE period received ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 5 followed by a single infusion of ocrelizumab, 600 mg, Q24W.

In the Treatment Period, participants received ocrelizumab 300 mg as IV infusion on Days 1 and 15 of Cycle 1 ( 1 Cycle = 168 days ), followed by ocrelizumab, 600 mg, IV, on Day 1 and placebo IV on Day 15 of Cycle 2. Participants then received ocrelizumab, 600 mg, IV, on Day 1 of Cycles 3 and 4. Participants who completed the TP then entered the TFP which was of variable duration. Participants who completed the TP and the TFP (at least through Week 120) and opted to enroll in the OLE period received ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 5 followed by a single infusion of ocrelizumab, 600 mg, Q24W.

In the Treatment Period, participants received placebo as IV infusion on Days 1 and 15 of Cycle 1 ( 1 Cycle = 168 days ), followed by ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 2. Participants then received ocrelizumab, 600 mg, IV, on Day 1 of Cycles 3 and 4. Participants who completed the TP then entered the TFP which was of variable duration. Participants who completed the TP and the TFP (at least through Week 120) and opted to enroll in the OLE period received ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 5 followed by a single infusion of ocrelizumab, 600 mg, Q24W.

In the Treatment Period, participants received ocrelizumab 300 mg as IV infusion on Days 1 and 15 of Cycle 1 ( 1 Cycle = 168 days ), followed by ocrelizumab, 600 mg, IV, on Day 1 and placebo IV on Day 15 of Cycle 2. Participants then received ocrelizumab, 600 mg, IV, on Day 1 of Cycles 3 and 4. Participants who completed the TP then entered the TFP which was of variable duration. Participants who completed the TP and the TFP (at least through Week 120) and opted to enroll in the OLE period received ocrelizumab, 300 mg, IV, on Days 1 and 15 of Cycle 5 followed by a single infusion of ocrelizumab, 600 mg, Q24W.