Multicenter, Double-Blind, Placebo-Controlled, Randomized, Parallel-Group, Dose-Ranging Study to Evaluate the Safety and Efficacy of Intravenous Natalizumab (BG00002) in Acute Ischemic Stroke
Phase: PHASE2
Conditions: Acute Ischemic Stroke
Sponsor: Biogen

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Biogen MA Inc.
1
Biogen MA Inc.
250 Binney Street
Cambridge, MA 02142
United States
PROTOCOL NUMBER: 
101SK202/NCT02730455
Biogen Idec Research Limited
Innovation House
70 Norden Road
Maidenhead Berkshire
SL6 4AY
United Kingdom
PHASE OF DEVELOPMENT:
2
PROTOCOL TITLE: A Multicenter, Double-Blind, Placebo-Controlled, Randomized, 
Parallel-Group, Dose-Ranging Study to Evaluate the Safety and Efficacy of Intravenous 
Natalizumab (BG00002) in Acute Ischemic Stroke
EUDRA CT NO:
2015-004783-11
DATE:
03 May 2017
Version 3.0
FINAL
Supersedes previous Version 2.0 dated 15 December 2016.

Protocol 101SK202
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TABLE OF CONTENTS
SPONSOR SIGNATURE PAGE ....................................................................................................2
1.
SPONSOR INFORMATION .......................................................................................8
2.
LIST OF ABBREVIATIONS.......................................................................................9
3.
SYNOPSIS .................................................................................................................11
4.
STUDY SCHEMATIC AND SCHEDULE OF ACTIVITIES FOR STUDY 
101SK202 ...................................................................................................................15
4.1.
Study Schematic .........................................................................................................15
4.2.
Schedule of Activities.................................................................................................16
5.
INTRODUCTION......................................................................................................18
5.1.
Overview of Acute Ischemic Stroke...........................................................................18
5.2.
Current Therapies for Acute Ischemic Stroke ............................................................19
5.3.
Profile of Previous Experience With Natalizumab.....................................................19
5.3.1.
Nonclinical Experience...............................................................................................19
5.3.2.
Clinical Experience.....................................................................................................19
5.4.
Study Rationale...........................................................................................................20
5.4.1.
Role of Inflammation in Stroke..................................................................................20
5.4.2.
Preclinical Rationale...................................................................................................20
5.4.3.
Clinical Rationale .......................................................................................................21
5.5.
Rationale for the Treatment Window of ≤24 Hours From LKN................................21
5.6.
Rationale for Dosing Regimen ...................................................................................22
5.6.1.
Rationale for Comparator/Reference Product or Placebo ..........................................22
6.
STUDY OBJECTIVES AND ENDPOINTS..............................................................23
6.1.
Primary Objective and Endpoint ................................................................................23
6.2.
Secondary Objectives and Endpoints .........................................................................23
6.3.
Exploratory Objectives and Endpoints.......................................................................23
7.
STUDY DESIGN .......................................................................................................25
7.1.
Study Overview ..........................................................................................................25
7.2.
Overall Study Duration and Follow-Up .....................................................................25
7.2.1.
Screening ....................................................................................................................25
7.2.2.
Treatment....................................................................................................................25

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7.2.3.
Follow-Up...................................................................................................................25
7.3.
Study Stopping Rules .................................................................................................26
7.4.
End of Study ...............................................................................................................26
8.
SELECTION OF SUBJECTS ....................................................................................27
8.1.
Inclusion Criteria ........................................................................................................27
8.2.
Exclusion Criteria.......................................................................................................28
9.
ENROLLMENT, REGISTRATION, AND RANDOMIZATION ............................30
9.1.
Screening and Enrollment...........................................................................................30
9.2.
Randomization and Registration of Subjects..............................................................30
9.3.
Blinding Procedures....................................................................................................30
10.
DISCONTINUATION OF STUDY TREATMENT AND/OR 
WITHDRAWAL OF SUBJECTS FROM THE STUDY...........................................31
10.1.
Discontinuation of Study Treatment...........................................................................31
10.2.
Withdrawal of Subjects From Study...........................................................................31
11.
STUDY TREATMENT USE .....................................................................................33
11.1.
Regimen......................................................................................................................33
11.2.
Modification of Dose and/or Treatment Schedule......................................................33
11.3.
Precautions..................................................................................................................33
11.4.
Compliance.................................................................................................................33
11.5.
Concomitant Therapy and Procedures........................................................................33
11.5.1.
Concomitant Therapy .................................................................................................33
11.5.1.1.
Allowed Concomitant Therapy...................................................................................33
11.5.1.2.
Disallowed Concomitant Therapy..............................................................................34
11.5.2.
Concomitant Procedures.............................................................................................34
11.6.
Continuation of Treatment..........................................................................................34
12.
STUDY TREATMENT MANAGEMENT................................................................35
12.1.
Natalizumab................................................................................................................35
12.1.1.
Natalizumab Preparation ............................................................................................35
12.1.2.
Natalizumab Storage...................................................................................................35
12.1.3.
Natalizumab Handling and Disposal ..........................................................................36
12.1.4.
Natalizumab Accountability.......................................................................................36
12.2.
Placebo........................................................................................................................36

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13.
EFFICACY, PHARMACOKINETIC, AND PHARMACODYNAMIC 
ASSESSMENTS.........................................................................................................37
13.1.
Clinical Efficacy Assessments....................................................................................37
13.2.
Pharmacokinetic Assessments....................................................................................39
13.3.
Pharmacodynamic Assessments.................................................................................39
14.
SAFETY ASSESSMENTS ........................................................................................40
14.1.
Clinical Safety Assessments.......................................................................................40
14.2.
Laboratory Safety Assessments..................................................................................40
15.
SAFETY DEFINITIONS, RECORDING, REPORTING, AND 
RESPONSIBILITIES .................................................................................................41
15.1.
Definitions ..................................................................................................................41
15.1.1.
Serious Pretreatment Event.........................................................................................41
15.1.2.
Adverse Event.............................................................................................................41
15.1.3.
Serious Adverse Event................................................................................................41
15.1.4.
Prescheduled or Elective Procedures or Routinely Scheduled Treatments................42
15.2.
Safety Classifications..................................................................................................42
15.2.1.
Investigator Assessment of Events.............................................................................42
15.2.2.
Relationship of Events to Study Treatment................................................................43
15.2.3.
Severity of Events.......................................................................................................43
15.2.4.
Expectedness of Events ..............................................................................................43
15.3.
Monitoring and Recording Events..............................................................................44
15.3.1.
Adverse Events ...........................................................................................................44
15.3.2.
Serious Adverse Events..............................................................................................44
15.3.3.
Immediate Reporting of Serious Adverse Events.......................................................44
15.3.3.1.
Deaths .........................................................................................................................45
15.3.4.
Suspected Unexpected Serious Adverse Reactions....................................................45
15.4.
Procedures for Handling Special Situations ...............................................................45
15.4.1.
Pregnancy ...................................................................................................................45
15.4.2.
Overdose.....................................................................................................................45
15.4.3.
Medical Emergency....................................................................................................46
15.4.3.1.
Unblinding for Medical Emergency...........................................................................46
15.5.
Contraception Requirements ......................................................................................46
15.6.
Safety Responsibilities................................................................................................47

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15.6.1.
The Investigator..........................................................................................................47
15.6.2.
Biogen.........................................................................................................................48
16.
STATISTICAL METHODS AND DETERMINATION OF SAMPLE SIZE...........49
16.1.
Efficacy.......................................................................................................................49
16.1.1.
Analysis Population....................................................................................................49
16.1.2.
Methods of Analysis...................................................................................................49
16.1.2.1.
Analysis of the Primary Endpoint...............................................................................49
16.1.2.2.
Analysis of the Secondary Endpoints.........................................................................49
16.1.2.3.
Additional/Exploratory Endpoints Analysis...............................................................51
16.2.
Pharmacokinetics........................................................................................................51
16.2.1.
Analysis Population....................................................................................................51
16.2.2.
Methods of Analysis...................................................................................................51
16.3.
Pharmacodynamics.....................................................................................................52
16.3.1.
Analysis Population....................................................................................................52
16.3.2.
Methods of Analysis...................................................................................................52
16.4.
Safety..........................................................................................................................52
16.4.1.
Analysis Population....................................................................................................52
16.4.2.
Methods of Analysis...................................................................................................52
16.4.2.1.
Adverse Events ...........................................................................................................53
16.4.2.2.
Clinical Laboratory Results........................................................................................53
16.4.2.3.
Vital Signs ..................................................................................................................53
16.5.
Interim Analyses.........................................................................................................53
16.6.
Sample Size Considerations .......................................................................................53
17.
ETHICAL REQUIREMENTS ...................................................................................54
17.1.
Declaration of Helsinki...............................................................................................54
17.2.
Ethics Committee........................................................................................................54
17.3.
Subject Information and Consent ...............................................................................54
17.4.
Subject Data Protection ..............................................................................................55
17.5.
Compensation for Injury.............................................................................................55
17.6.
Conflict of Interest......................................................................................................55
17.7.
Registration of Study and Disclosure of Study Results..............................................55
18.
ADMINISTRATIVE PROCEDURES.......................................................................56

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18.1.
Study Site Initiation....................................................................................................56
18.2.
Quality Assurance.......................................................................................................56
18.3.
Monitoring of the Study..............................................................................................56
18.4.
Study Funding.............................................................................................................56
18.5.
Publications.................................................................................................................56
19.
FURTHER REQUIREMENTS AND GENERAL INFORMATION........................57
19.1.
External Contract Organizations.................................................................................57
19.1.1.
Contract Research Organization.................................................................................57
19.1.2.
Interactive Response Technology...............................................................................57
19.1.3.
Remote Data Capture..................................................................................................57
19.1.4.
Central Laboratories for Laboratory Assessments .....................................................57
19.1.5.
Central Facility for Other Assessments ......................................................................57
19.2.
Study Committees.......................................................................................................57
19.2.1.
Advisory Committee...................................................................................................57
19.2.2.
Independent Data Safety Monitoring Committee.......................................................58
19.3.
Changes to Final Study Protocol ................................................................................58
19.4.
Ethics Committee Notification of Study Completion or Termination........................58
19.5.
Retention of Study Data..............................................................................................58
19.6.
Study Report Signatory...............................................................................................59
20.
REFERENCES ...........................................................................................................60
21.
SIGNED AGREEMENT OF THE STUDY PROTOCOL.........................................62
LIST OF TABLES
Table 1:
Schedule of Activities for Study 101SK202...............................................................16
LIST OF FIGURES
Figure 1:
Study Design...............................................................................................................15

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1.
SPONSOR INFORMATION
Biogen MA Inc.
250 Binney Street
Cambridge, MA 02142
United States
Biogen Idec Research Limited
Innovation House
70 Norden Road
Maidenhead, Berkshire 
SL6 4AY
United Kingdom
For urgent medical issues in which the study’s Medical Monitor should be contacted, please refer 
to the Study Reference Manual’s Official Study Contact List for complete contact information.
Biogen may transfer any or all of its study-related responsibilities to a contract research 
organization (CRO) and other third parties; however, Biogen retains overall accountability for 
these activities.

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2.
LIST OF ABBREVIATIONS
AE
adverse event
AUC
area under the serum concentration versus time curve
AUC0-120
area under the serum concentration versus time curve from dosing (time=0) 
to 120 hours after dosing
AUC0-2160
area under the serum concentration versus time curve from dosing (time=0) 
to 2160 hours after dosing
AUC0-672
area under the serum concentration versus time curve from dosing (time=0) 
to 672 hours after dosing
AUC0-last
area under the serum concentration versus time curve, from dosing (time=0) 
to last measurable concentration
BDI-2
Beck Depression Inventory 2
BI
Barthel Index
CD
Crohn’s disease
CI
confidence interval
Cmax
maximum serum concentration
CRO
contract research organization
CT
computed tomography
DAMPs
damage associated molecular patterns
DHA
Directions for Handling and Administration
DSMC
Data Safety Monitoring Committee
EC
ethics committee
eCRF
electronic case report form
FIM
Functional Independence Measure
FSS
Fatigue Severity Scale
GCP
Good Clinical Practice
HRU
health resource utilization
ICF
Informed Consent Form
ICH
International Council on Harmonisation
IRB
institutional review board
IRT
interactive response technology
IV
intravenous
IXRS
Interactive Voice/Web Response System
JCV
John Cunningham virus
LKN
last known normal
MoCA
Montreal Cognitive Assessment
MRI
magnetic resonance imaging
mRS
modified Rankin Scale
MS
multiple sclerosis
NIHSS
National Institute of Health Stroke Scale

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OR
odds ratio
PD
pharmacodynamic(s)
PK
pharmacokinetic(s)
PML
progressive multifocal leukoencephalopathy
RDC
remote data capture
rtPA
recombinant tissue plasminogen activator
SAE
serious adverse event
SAP
statistical analysis plan
SDMT
Symbol-Digits Modalities Test
SE
standard error
SIS-16
Stroke Impact Scale-16
SUSAR
suspected unexpected serious adverse reaction
t½
half-life
tlast
time of last measurable concentration
tmax
time to Cmax
tPA
tissue plasminogen activator
US
United States
VCAM-1
vascular cell adhesion molecule-1
VLA-4
α4β1 integrin, also known as very late antigen-4

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3.
SYNOPSIS
Protocol Number:
101SK202
Protocol Title:
A Multicenter, Double-Blind, Placebo-Controlled, 
Randomized, Parallel-Group, Dose-Ranging Study to 
Evaluate the Safety and Efficacy of Intravenous 
Natalizumab (BG00002) in Acute Ischemic Stroke
Version Number
3.0
Name of Study Treatment:
BG00002 (natalizumab; Tysabri)
Study Indication:
Acute Ischemic Stroke
Study Rationale
Stroke is a leading cause of mortality and serious long-term 
disability.  There is a substantial unmet medical need for 
new therapies that can improve outcomes in acute stroke.
Experimental and pathologic data suggest that peri-infarct 
inflammation contributes to secondary injury after brain 
ischemia and that blocking inflammation reduces neuronal 
injury and improves clinical outcomes.
Natalizumab is a humanized monoclonal antibody approved 
for the treatment of both relapsing multiple sclerosis and 
Crohn’s disease that blocks α4β1- or α4β7-integrin-
mediated adhesion of leukocytes to vascular endothelial 
cells and inhibits the transmigration of leukocytes into 
inflamed parenchymal tissue.
In Study 101SK201 (ACTION), while treatment with 
natalizumab did not reduce magnetic resonance 
imaging-defined infarct volume, there was evidence that it 
resulted in clinical benefit in patients with acute ischemic 
stroke, and no safety concerns were identified. 
This study (101SK202) will assess dose response and 
overall safety and efficacy of natalizumab in subjects with 
acute ischemic stroke.  Time dependency of treatment 
effects will also be assessed through a treatment window of 
up to 24 hours from last known normal (LKN).
Phase of Development:
2

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Study Objectives and 
Endpoints:
The primary objective of the study is to assess the effects of 
natalizumab versus placebo in acute ischemic stroke on 
clinical measures of independence and activities of daily 
life.
The primary efficacy endpoint is a composite global 
measure of functional disability based on a score of 0 or 1 
on the modified Rankin scale (mRS) and a score of ≥95 on 
the Barthel Index (BI) at Day 90 [Tilley 1996]. 
The secondary objective of the study is to explore dose and 
exposure response, time dependency of the treatment effect,
and the clinical treatment effects of natalizumab versus 
placebo in acute ischemic stroke on the following measures 
of independence, activities of daily living, neurologic 
function, quality of life, and cognition and safety and 
tolerability.
The secondary endpoints are:

mRS score at Day 90

BI score at Day 90

Stroke Impact Scale-16 score at Day 90

Montreal Cognitive Assessment score at Day 90

Safety (incidence and proportion of adverse 
events and serious adverse events)

National Institutes of Health Stroke Scale 
(NIHSS) score at Day 90
The exploratory objective of this study is to evaluate the 
effect of natalizumab on measures of function, cognition, 
fatigue, depression, quality of life, and 
pharmacokinetic/pharmacodynamic relationships over time.
The exploratory endpoints are:

Functional Independence Measure score at 
Day 90

Symbol-Digits Modalities Test score at Day 90

Fatigue Severity Scale score at Day 90

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
Beck Depression Inventory 2 score

Serum concentrations of natalizumab at selected 
times after dosing

Blood biomarkers of natalizumab

Subject direct resource use (assessed using a 
health resource utilization questionnaire)

EuroQoL EQ-5D-3L (questionnaire)
Study Design:
This is a Phase 2 multicenter, double-blind, 
placebo-controlled, randomized, 3-arm, dose-ranging study. 
Study Location:
Approximately 67 sites in the United States and Europe are 
planned.
Number of Planned Subjects:
Approximately 270 subjects are expected to be enrolled.  Of 
these, no more than 90 subjects will be treated between >9 
and ≤24 hours from LKN.
Study Population:
This study will be conducted in subjects aged 18 to 80 years 
with acute ischemic stroke defined by LKN at ≤24 hours
prior to study treatment initiation.
Detailed criteria are described in Section 8.
Treatment Groups:
All subjects will receive 1 dose of study treatment at 
Screening according to their randomization in a 1:1:1 ratio 
to 1 of the following 3 treatment groups:

Natalizumab 600 mg intravenous (IV) in 
approximately 90 subjects

Natalizumab 300 mg IV in approximately 
90 subjects

Placebo IV in approximately 90 subjects
Randomization will occur separately within each treatment 
window.  For subjects in the ≤9 hour treatment window, 
randomization will be stratified by baseline NIHSS category 
(NIHSS scores from 5 to 15 or 16 to 23), tissue plasminogen 
activator (tPA) use (yes or no), and region; for subjects in 
the >9 to ≤24 hour window, randomization will be stratified 

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by tPA use (yes or no) and region.
Duration of Treatment and 
Follow-up:
Subjects will participate in this study for approximately 
90 days.

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4.
STUDY SCHEMATIC AND SCHEDULE OF ACTIVITIES FOR 
STUDY 101SK202
4.1.
Study Schematic
The study design is displayed in Figure 1.
Figure 1:
Study Design
LKN = last known normal; NA = natalizumab; R = randomization.
Note: PK/PD/biomarkers are performed within 1 hour after the end of the infusion.

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4.2.
Schedule of Activities
Table 1:
Schedule of Activities for Study 101SK202
Tests and Assessments
Screening1
0 Hours2
(Day 1)
Within 1 Hour 
After End of 
Infusion
12 Hours
±3 Hours
24 Hours
±6 Hours
Day 53
Day 304
±5 Days
Day 90 Follow-up4/
Early Termination4
±5 Days
Informed consent
X
Confirm eligibility
X
Demographics and medical 
history5
X
Physical and neurological 
examination
X
X
X
X
X
Vital signs6
X
X
X
X
X
X
X
Height (if available) and weight
X (anytime from Screening to Day 5 Visit)
Urine pregnancy test7
X
Hematology and blood 
chemistry
X
X
X
X
X
X
Serum biomarkers
X
X
X
X
X
X
PD sampling
X
X
X
X
X
X
X
PK sampling
X
X
X
X
X
X
X
Blood sample for 
anti-natalizumab antibodies
X
X
X
NIHSS
X
X2
X
X
X
X
mRS
X8
X
X
BI
X
X
X
SIS-16
X9
X
X
MoCA
X
X
X
Functional Independence 
Measure
X
X
SDMT
X
X
X
Fatigue Severity Scale
X9
X
X
Beck Depression Inventory 2
X9
X
X
HRU questionnaire
X
X
X
EQ-5D-3L
X
X
X
Study treatment administration10
X
Stroke subtype classification11
X
SAE reporting
Record as per Section 15.3.2 of the protocol

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Tests and Assessments
Screening1
0 Hours2
(Day 1)
Within 1 Hour 
After End of 
Infusion
12 Hours
±3 Hours
24 Hours
±6 Hours
Day 53
Day 304
±5 Days
Day 90 Follow-up4/
Early Termination4
±5 Days
AE reporting
Record as per Section 15.3.1 of the protocol
Concomitant medications
Record as per Section 11.5 of the protocol
Concomitant procedures
Record as per Section 11.5 of the protocol
AE = adverse event; BI = Barthel Index; BDI-2 = Beck Depression Inventory 2; CT= computed tomography; ECG = electrocardiogram; FIM = Functional Independence Measure; 
FSS = Fatigue Severity Scale; HRU = health resource utilization; LKN = last known normal; MoCA = Montreal Cognitive Assessment; MRI = magnetic resonance imaging; 
mRS = modified Rankin Scale; NIHSS = National Institute of Health Stroke Scale; PD = pharmacodynamic; PK = pharmacokinetic; SAE = serious adverse event; SDMT = 
Symbol-Digits Modalities Test; SIS-16 = Stroke Impact Scale-16.
Note:  All timepoints, except “within 1 hour after the end of the infusion”, are relative to start of study treatment administration.
1
All Screening assessments must be performed prior to infusion.  Screening assessments that are performed as standard of care do not need to be repeated for the study, provided 
that Biogen has access to the information and data are recorded in subject’s case report form.  Data collected for the Screening assessments will be used for patient baseline 
analysis in this study.  The ECG and CT or MRI assessments results should already be available at Screening (as they are performed as part of the standard of care), and a copy 
of the images and report should be filed with the subject’s study records.
2
The 0 Hours vital signs assessments are to be performed within 15 minutes prior to study treatment administration.  If the Screening NIHSS is performed more than 1 hour 
prior to study treatment administration, it must be repeated during the visit at 0 Hours before study treatment administration.
3
Day 5 assessments are to occur on Day 5 or earlier if discharged, but must occur prior to discharge.
4
The subject will be asked to complete the Day 30 and Day 90 Follow-Up or Early Termination assessments in person (see Section 7.2.3 and Section 10.2).  If the subject is 
unable to return to the study center to complete the Day 30 or Day 90 (Follow-up or Early Termination) assessments in person, safety information will be collected by 
telephone or remotely, as local regulations allow and pending medical monitor approval, and will include the collection of AEs, SAEs, FIM, mRS, BI, BDI-2, SIS-16, EQ-5D-
3L, physical/neurological examination, vital signs, hematology/blood chemistry, serum biomarkers, PD sampling, PK sampling, anti-natalizumab antibodies, NIHSS, MoCA, 
SDMT, FSS, HRU, and concomitant medications.
5
Medical history should include an assessment of prior substance abuse.
6
Vital signs collected at each of the specified timepoints include temperature, blood pressure, pulse or heart rate, and respiratory rate.  Vital signs collected as part of the 
subject’s standard of care and that fall within 30 minutes of a study visit do not need to be repeated for the study, provided that Biogen has access to the information and data 
are recorded in the subject’s case report form.
7
Required only for women of childbearing potential.  If a serum beta human chorionic gonadotropin test was performed as part of the subject’s standard of care, the results will 
be accepted in lieu of the urine pregnancy test.
8
An mRS assessment will be done on Day 5, or earlier if discharged.
9
Per instructions on the SIS-16, BDI-2, and FSS forms, the subject or proxy should provide responses as it applies to the prior 2 week period.  When completing the SIS-16 
BDI-2, and FSS assessments during the Day 5 Visit, the subject or proxy should consider only the time period starting between the initial stroke (LKN) and the Day 5 Visit.
10
The subject must be observed for 1 hour after completion of infusion.
11
The stroke etiology will be assessed based on the subject’s standard of care and diagnostic testing.  This should be completed at Day 5 or earlier if discharged, but if results are 
incomplete, it may be completed at Day 30.

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5.
INTRODUCTION
Natalizumab is a recombinant humanized monoclonal antibody approved in the United States 
(US), European Union, and multiple other countries for the treatment of relapsing multiple 
sclerosis (MS).  It is also approved for the treatment of Crohn’s disease (CD) in the US.  
Natalizumab is produced in a murine myeloma cell line (NS/0) and binds to the α4 subunit of 
human integrin, which is expressed at high levels on all circulating human leukocytes except 
polymorphonuclear leukocytes.
Natalizumab binding blocks the interaction of α4β1 integrin (also known as very late antigen-4 
[VLA-4]) on leukocytes with its counter receptor, vascular cell adhesion molecule-1 (VCAM-1) 
and fibronectin, located on endothelial cells.  Likewise, natalizumab blocks the interaction of 
α4β7 integrin expressed on leukocytes with mucosal addressin cell adhesion molecule-1.  
Disruption of these cell adhesion molecule interactions prevents trafficking of mononuclear 
leukocytes across the endothelium and into parenchymal tissue.  This is believed to be the basis 
of its efficacy in MS and CD, and in clinical studies, natalizumab has demonstrated reduction in 
MS relapse rates by approximately 70%.  
Experimental and pathologic data suggest that peri-infarct inflammation in patients with 
ischemic stroke contributes to secondary injury after brain ischemia, and blocking inflammation 
reduces the volume of brain infarction and improves clinical outcomes.  The Phase 2a 
Study 101SK201 demonstrated that although natalizumab did not reduce infarct volume, it was 
associated with improved clinical outcomes, and no safety risks were observed.  The observed 
clinical benefits warranted further investigation. 
5.1.
Overview of Acute Ischemic Stroke
Stroke occurs when there is an interruption of blood flow to the brain, causing death of neural 
tissue and focal neurological deficits.  The signs and symptoms vary with the location and extent 
of the stroke.  There are nearly 800,000 strokes of all types per year in the US, of which ischemic 
stroke accounts for approximately 80% [Roger 2011].  In Europe, the estimated annual incidence 
of stroke is over 1.1 million, with a similar percentage of these (approximately 80%) being 
ischemic strokes [Heuschmann 2009; Truelsen 2006].
Guidelines for the evaluation and treatment of acute stroke patients focus on reperfusion 
therapies and controlling factors that may exacerbate stroke or complicate the clinical course.  
The diagnosis of acute ischemic stroke is made through a combination of a history and physical 
examination that is consistent with focal ischemia and a resulting neurologic deficit.  Brain 
imaging, obtained through either computed tomography (CT) or magnetic resonance imaging 
(MRI), is used to exclude hemorrhage and other focal pathologies and document early signs of 
ischemia. 
Regardless of the mechanism of ischemia, inflammation is thought to contribute to the 
progression of brain injury.  Inflammation was long considered to be merely a reaction to 

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damaged brain tissue, but recent evidence suggests that inflammation is a key part of ischemic 
injury that stems from both responses in the vasculature and the release of damage associated 
molecular patterns (DAMPs) from ischemic brain tissue [Shichita 2012].  
5.2.
Current Therapies for Acute Ischemic Stroke 
Recombinant tissue plasminogen activator (rtPA) is the only approved pharmacological therapy 
for acute ischemic stroke. It is approved for use within 3 hours of stroke onset in the US and 
within 4.5 hours in many European countries. Current American Heart Association guidelines 
also suggest use up to 4.5 hours after stroke onset, although treatment effects diminish over time 
and risk of hemorrhage increases [Jauch 2013]. Because of the narrow time window, it is 
estimated that only 3% of patients with stroke received rtPA within the treatment window, and 
there is a clear need for therapies that may be more widely used. In addition to rtPA, 
intra-arterial thrombectomy has also been shown to improve clinical outcomes in stroke patients
[Berkhemer 2015; Goyal 2015; Jovin 2015].  Participation in this study will not impact the 
ability of subjects to receive current standards of care for acute stroke treatment.
5.3.
Profile of Previous Experience With Natalizumab
5.3.1.
Nonclinical Experience
See the Investigator’s Brochure for detailed information on nonclinical studies.
5.3.2.
Clinical Experience
Natalizumab has been used extensively in the setting of relapsing remitting MS and CD, both in 
clinical studies involving over 5500 subjects, as well as in the postmarketing setting, with more 
than 9 years of experience and a cumulative exposure of over 200,000 person-years.  As of 
31 December 2012, approximately 112,200 patients have been treated with natalizumab 
worldwide.  Therefore, the safety of natalizumab, when given as a 300 mg intravenous (IV) dose 
every 4 weeks, has been well characterized in these specific patient populations.  
The efficacy of natalizumab in relapsing MS patients has been established in 3 controlled 
studies:  a Phase 2 dose-comparison study as well as 2 Phase 3 efficacy and safety studies.  In 
both Phase 3 studies, treatment with natalizumab delayed the time to sustained progression in 
disability, substantially reduced the frequency of relapses, and markedly attenuated brain MRI 
measures of inflammation and tissue destruction in subjects with relapsing MS.  Natalizumab as 
monotherapy significantly reduced the risk of disability progression by 42% relative to placebo.
The most notable complication of treatment is the risk of progressive multifocal 
leukoencephalopathy (PML). PML is an opportunistic viral infection of the central nervous 
system caused by the John Cunningham virus (JCV). Among the patients who developed PML,
natalizumab exposure ranged from 8 to 90 months, with the majority having received >24 
months of treatment. Three established risk factors for the development of PML have been 
identified: presence of anti-JCV antibodies, longer treatment duration of natalizumab (especially 
≥2 years), and prior use of immunosuppressant therapy before initiation of natalizumab. 

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Other risks of natalizumab treatment include a risk for hypersensitivity reactions, infections, and 
hepatic injury.  Serious hypersensitivity reactions (e.g., anaphylaxis) have occurred at an 
incidence of <1%.
For Phase 2a experience, see Section 5.4.3.
5.4.
Study Rationale
Stroke is a leading cause of mortality and serious long-term disability.  There is a substantial 
unmet medical need for new therapies that can improve the outcome of acute ischemic stroke.  
5.4.1.
Role of Inflammation in Stroke
The inflammatory response is closely coupled to the initial ischemia and activates both the innate 
and adaptive immune systems.  It begins in the intravascular compartment within the first 
6 hours (hyperacute period).  The production of reactive oxygen species activates platelets and 
endothelial cells.  Oxidative stress reduces the vasodilatory effects of nitric oxide, which is a 
potent inhibitor of platelet aggregation and leukocyte adhesion to the vascular wall.  
Intravascular leukocytes loosely adhere to P-selectin, which is upregulated minutes after the 
onset of ischemia, and subsequently firmly binds to adhesion molecules, such as intercellular 
adhesion molecule-1 and VCAM-1.  The activation of matrix metalloproteinase and expression 
of proteases promote blood-brain barrier breakdown, allowing for further influx of leukocytes.  
After the hyperacute period, DAMPs released from injured neural tissue, including nuclear and 
cytoplasmic neural proteins, trigger cells of the innate and adaptive immune systems.  These 
endogenous danger signals are sensed through pattern recognition receptors, such as toll-like 
receptors.  This post-ischemic inflammatory reaction has been shown to increase infarct volume 
and worsen functional outcomes in preclinical stroke models [Gelderblom 2009].  
5.4.2.
Preclinical Rationale
The key role of mononuclear leukocyte-mediated damage in acute stroke is supported by the fact 
that depletion of these cells or blocking α4 with the rodent-homologue antibody in experimental 
models reduces brain infiltration of leukocytes, attenuates expression of cytokines such as 
interferon-γ and interleukin-6 in brain tissue, reduces stroke size, and improves behavior in the 
rodent model [Liesz 2011].  In 1 study, the reduction in stroke volume due to blocking α4β1 was 
greater at Day 7 than Day 1, which is consistent with the delayed damage induced by peri-infarct 
inflammation [Liesz 2011].  In animal models of experimental brain ischemia, monoclonal 
antibodies targeting α4 integrin have reduced infarct volume and improved functional outcomes 
by approximately 30% compared to placebo.  This effect has been observed in models of 
transient ischemia with treatment administered around the time of reperfusion [Becker 2001; 
Relton 2001].  In a preclinical randomized controlled study involving 6 centers, treatment with 
anti-CD49 (targeting α4 integrin) reduced leukocyte invasion and infarct volume in a permanent 
distal middle cerebral artery occlusion model [Llovera 2015].  

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5.4.3.
Clinical Rationale
Natalizumab has been evaluated in a Phase 2a study assessing patients with acute ischemic 
stroke.  Study 101SK201 explored the efficacy and safety of a single dose of 300 mg 
natalizumab IV administered at ≤6 hours or at >6 to ≤9 hours from when the subjects were last 
known normal (LKN).  In this study, 161 subjects (79 subjects in the natalizumab group and 
82 subjects in the placebo group) were randomized in the study.  The primary efficacy analysis 
demonstrated that natalizumab did not decrease acute infarct volume growth defined by MRI.  
However, on prespecified secondary and tertiary clinical endpoints, natalizumab treatment was 
associated with improved clinical outcomes.  More patients had an “excellent” outcome on the 
modified Rankin Scale (mRS) (defined as a score of 0 or 1) with natalizumab than with placebo 
at Days 30 (odds ratio [OR] 2.88; 90% confidence interval [CI] 1.20 to 6.93) and 90 (OR 1.48; 
90% CI 0.74 to 2.98).  More patients had an “excellent” outcome on the Barthel Index (BI; 
defined as a score of ≥95) at Day 90 with natalizumab (OR 1.91; 90% CI 1.07 to 3.41) than 
placebo.  There was no evidence of benefit on the National Institute of Health Stroke Scale
(NIHSS).  Tertiary clinical endpoints (Stroke Impact Scale-16 [SIS-16], Montreal Cognitive 
Assessment [MoCA]) also supported improved outcomes in the natalizumab group.  In both 
treatment groups, the incidences of death (18% natalizumab versus 16% placebo) and serious 
adverse events (SAEs; 46% natalizumab versus 46% placebo) were similar, and no increase in 
infections or infusion-related reactions were observed in the natalizumab group.  Overall, the 
safety profile was consistent with its use in in the postmarketing setting.
5.5.
Rationale for the Treatment Window of ≤24 Hours From LKN
In experimental rodent models, immune cell infiltration in the brain parenchyma following an 
ischemic stroke occurs predominantly after 24 hours of lesion onset, reaching its peak at 
approximately 3 days after the index event [Gelderblom 2009].  Congruently, blockage of 
maladaptive immune responses through immune modulatory treatments as far as 5 days after 
ischemia onset has been demonstrated to yield significant beneficial effects in rodent models, 
suggesting that therapies targeting lymphocyte infiltration after ischemia may have a prolonged 
therapeutic window [Doyle 2015; Shichita 2009].
A stratified randomization process was adopted in Study 101SK201 to evaluate the potential 
time dependency of treatment effect when administering 300 mg of natalizumab in a 9-hour 
window as compared to placebo.  In this study, half of the subjects in the intent-to-treat 
population were assigned to receive study treatment at ≤6 hours from LKN, while the other half 
had study treatment administered within the >6 to ≤9 hour window.  Results from 
Study 101SK201 indicated that estimates of treatment effect favored natalizumab against 
placebo at both treatment windows, with no evidence of time dependency for the treatment 
benefit.  Likewise, the safety profile of natalizumab treatment was comparable in the ≤6 hour 
and the >6 to ≤9 hour treatment windows, with a small decrease in the proportion of deaths (21% 
and 15%, respectively) and SAEs (47% and 45%, respectively) being reported among subjects 
treated in the later treatment window.
Based on these observations, the therapeutic window for natalizumab therapy appears to be 
greater than 9 hours.  Therefore, in addition to evaluating a ≤9 hour treatment window, 

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Study 101SK202 will further explore the time dependency of the treatment effect of natalizumab 
in patients with acute ischemic stroke by enrolling a limited number of subjects within the 
treatment window of >9 to ≤24 hours from LKN.
5.6.
Rationale for Dosing Regimen
Study 101SK201 indicated that a dose of 300 mg natalizumab was associated with improved 
clinical outcomes after stroke. Post hoc analyses demonstrated that those subjects with greater 
area under the serum concentration versus time curve (AUC; but not maximum serum 
concentration [Cmax]) following administration of 300 mg) were more likely to have better 
clinical and MRI defined outcomes compared to placebo treated subjects and subjects with lower 
AUC following 300 mg. For example, higher natalizumab AUC after the 300 mg IV infusion 
was associated with lower MRI-defined infarct volume growth at Day 30 (p =0.033), and 
subjects in the top tertile of natalizumab AUC had the highest OR for excellent outcome on the 
mRS at Day 90 (OR: 3.02; 95% CI: 0.89 to 10.75) and BI at Day 90 (OR: 3.00; 95% CI: 0.97 to 
9.99).  Exposure–response modeling predicted that doses in the range of 450 to 600 mg may be 
associated with improved outcomes relative to the 300-mg dose.
Therefore, Study 101SK202 will explore this relationship by evaluating 300-mg and 600-mg
doses administered at 0 Hours in comparison with placebo administered at 0 Hours.  Dosing 
instructions and details regarding administration will be provided in the Directions for Handling 
and Administration (DHA).  
Doses as high as 6 mg/kg of natalizumab have been studied previously in subjects with MS with 
the highest dose of 697 mg given monthly. The Phase 2b Study AN100226-231 evaluated the 
safety, tolerability, and efficacy of multiple administrations of natalizumab (3 mg/kg versus 
6 mg/kg) given every 28 days for 6 months in subjects with MS. Monthly infusions of 
natalizumab at doses of 3 and 6 mg/kg were well tolerated and were associated with a safety 
profile similar to that of placebo. There was no significant difference in the incidence of adverse 
events (AEs) between treatment groups. The majority of AEs in each treatment group were 
reported by the Investigator as mild or moderate in severity and not related to study drug.
5.6.1.
Rationale for Comparator/Reference Product or Placebo 
The use of placebo is justified because subjects will be receiving the standard of care in addition 
to study treatment.

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6.
STUDY OBJECTIVES AND ENDPOINTS
6.1.
Primary Objective and Endpoint
The primary objective of the study is to assess the clinical effects of natalizumab versus placebo 
in acute ischemic stroke on clinical measures of functional independence and activities of daily 
living.
The primary efficacy endpoint that relates to this objective is a composite global measure of 
functional disability based on a score of 0 or 1 on the mRS and a score of ≥95 on the BI at Day 
90 [Tilley 1996]. 
6.2.
Secondary Objectives and Endpoints
The secondary objective of the study is to explore dose and exposure response, time dependency
of the treatment effect, and the clinical treatment effects of natalizumab versus placebo in acute 
ischemic stroke on the following measures of independence, activities of daily living, neurologic 
function, quality of life, cognition, and safety and tolerability.
The secondary endpoints that relate to this objective are:

mRS score at Day 90

BI score at Day 90

SIS-16 score at Day 90

MoCA score at Day 90

Safety (incidence and proportion of AEs and SAEs)

NIHSS score at Day 90
6.3.
Exploratory Objectives and Endpoints
The exploratory objective of this study is to evaluate the effect of natalizumab on measures of 
function, cognition, fatigue, depression, quality of life, and pharmacokinetic
(PK)/pharmacodynamic (PD) relationships over time.
The exploratory endpoints that relate to this objective are:

Functional Independence Measure (FIM) score at Day 90

Symbol-Digits Modalities Test (SDMT) score at Day 90

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
Fatigue Severity Scale (FSS) score at Day 90

Beck Depression Inventory 2 (BDI-2) score

Serum concentrations of natalizumab at selected times after dosing

Blood biomarkers of natalizumab

Subject direct resource use (assessed using a health resource utilization [HRU] 
questionnaire)

EuroQoL EQ-5D-3L (questionnaire)

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7.
STUDY DESIGN
7.1.
Study Overview
See Figure 1 for a schematic of the study design.
This is a Phase 2, multicenter, double-blind, placebo-controlled, randomized, dose-ranging, 
3-arm study of natalizumab administered ≤24 hours from when the subject was LKN in subjects 
with acute ischemic stroke.  This study will evaluate the efficacy and safety of natalizumab over 
a 90-day period.  The study will be conducted at approximately 67 sites in the United States and 
Europe.
After completing screening assessments and fulfilling the criteria for study entry, eligible 
subjects in each of 2 treatment windows (≤9 hours and >9 to ≤24 hours from LKN) will be 
randomized in a 1:1:1 ratio to 1 of 3 treatment groups, each of which will receive a single dose at 
0 Hours (Day 1) according to one of the following 3 regimens: 600 mg IV natalizumab, 
300 mg IV natalizumab, or placebo IV.  Post-treatment assessments will be performed at the 
following timepoints:  within 1 hour after the end of the infusion, 12 ± 3 hours after the start of 
the infusion, 24 ± 6 hours after the start of the infusion, Day 5, Day 30 (±5 days), and the Day 90 
Follow-Up visit (±5 days).
Participation in this study will not influence the subject’s ability to receive standard of care 
treatment for stroke, as deemed necessary by the Investigator.
7.2.
Overall Study Duration and Follow-Up
The study period will consist of Screening, Randomization, Treatment, and Safety Follow-up 
periods.  Subjects will participate in this study for approximately 90 days. 
7.2.1.
Screening
Subject eligibility for the study will be determined at the time of acute ischemic stroke diagnosis.
7.2.2.
Treatment
Eligible subjects will report to the study site to receive study treatment ≤24 hours from their 
LKN, as described in Section 7.1.  Approximately one-third of the subjects will be treated in 
each treatment group.
7.2.3.
Follow-Up
Subjects are to return to the study site for a follow-up visit on Day 30 and Day 90 (Follow-Up 
Visit; the final study visit).  If the subject is unable to return to the study center to complete a
visit in person, the Day 30 or the Day 90 Follow-Up visits can be completed over the telephone 
or remotely, as local regulations allow and pending medical monitor approval.  

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The final study visit will be the Day 90 Follow-Up and will consist of the collection of AEs, 
SAEs, FIM, mRS, BI, BDI-2, SIS-16, EQ-5D-3L, physical/neurological examination, vital signs, 
hematology/blood chemistry, serum biomarkers, PD sampling, PK sampling, anti-natalizumab 
antibodies, NIHSS, MoCA, SDMT, FSS, HRU, and concomitant medication information.
7.3.
Study Stopping Rules
Biogen may terminate this study at any time after informing Investigators.  Investigators will be 
notified by Biogen or designee if the study is placed on hold, completed, or closed.  There are no 
prespecified stopping rules.  An independent Data Safety Monitoring Committee (DSMC) will 
be formed and will review safety data regularly.  Details of the DSMC responsibilities will be 
provided in the DSMC charter.
7.4.
End of Study
The end of study is last subject, last visit for final collection of data.

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8.
SELECTION OF SUBJECTS
8.1.
Inclusion Criteria
To be eligible to participate in this study, candidates must meet the following eligibility criteria 
at Screening or at the timepoint specified in the individual eligibility criterion listed.  All 
eligibility assessments must be completed in time for dosing within ≤9 hours or >9 to ≤24 hours
of the subject’s LKN:
1. Ability to understand the purpose and risks of the study and provide signed and dated 
informed consent and authorization to use protected health information in accordance 
with national and local subject privacy regulations OR consent provided by an 
independent physician where local regulation allows, and/or provision of informed 
consent by the subject’s representative in accordance with all local and national 
regulations OR according to the local institutional review board’s (IRB’s)/ethics 
committee’s (EC’s) guidelines OR by another process compliant with applicable national 
laws and regulations and IRB/EC requirements
2. Aged 18 to 80 years, inclusive, at the time of informed consent
3. Clinical diagnosis of supratentorial acute ischemic stroke defined by LKN ≤24 hours 
prior to study treatment initiation.  Note:  An acute brain CT or MRI scan must be 
available from the patient’s history to assess eligibility for the study and be consistent 
with the diagnosis of acute ischemic stroke
Note:  The number of subjects enrolling in the treatment window of >9 to ≤24 hours from 
LKN will be limited to no more than 90.
4. Score of 5 to 23 points, inclusive, on the NIHSS at Screening for subjects initiating 
treatment ≤9 hours from LKN.  Note:  NIHSS eligibility must be confirmed within 
60 minutes prior to randomization.
5. Score of 5 to 15 points, inclusive, on the NIHSS at Screening for subjects initiating 
treatment >9 to ≤24 hours from LKN.  Note:  NIHSS eligibility must be confirmed within 
60 minutes prior to randomization.
6. Prior to index stroke, patient was able to perform the following basic activities of daily 
living without assistance:  dressing, eating, walking, bathing, and using the toilet
7. For those subjects who underwent a cranial MRI, there is at least 1 acute infarct with a
diameter of ≥2 cm on baseline brain diffusion-weighted imaging
8. Subjects of childbearing potential must be willing and able to practice effective 
contraception during the study

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9. All women of childbearing potential and all men must practice effective contraception 
during the study and for at least 3 months after their last dose of study treatment.  For 
further details of contraceptive requirements for this study, please refer to Section 15.5.
8.2.
Exclusion Criteria
Candidates will be excluded from study entry if any of the following exclusion criteria exist at 
Screening, or at the timepoint specified in the individual criterion listed:
1. Lacunar or isolated brainstem or cerebellar stroke based on clinical assessment and 
available acute imaging studies performed under the standard of care.
2. Presence of acute intracranial hemorrhage on acute brain CT or MRI.  However, 
petechial hemorrhages of ≤1 cm are not exclusionary.
3. Severe stroke defined by imaging criteria based on either one of the following
a.
ASPECTS score of 0 to 4 based on head CT OR
b. Acute infarct volume on MRI diffusion weighted imaging ≥70 mL (cc)
4. Seizure at the onset of stroke
5. Hypotension requiring the use of IV vasopressor support or systolic blood pressure 
<90 mmHg at the time of randomization
6. Known history of prior treatment with natalizumab
7. Immunocompromised subjects as determined by the Investigator, based on medical 
history, physical examination, or laboratory testing, or due to prior or current 
immunosuppressive or immunomodulating treatment
8. Known history of positive test result for human immunodeficiency virus (HIV)
9. Known history of active viral hepatitis B or C.
10. Signs of active herpes simplex type 1 and 2 or varicella within 4 weeks prior to 
randomization
11. Known history of chronic, recurrent, or recent serious infection (e.g., pneumonia, 
septicemia) as determined by the Investigator within 6 months of randomization
12. Signs and symptoms of active or acute infection
13. Abnormal laboratory values indicative of or known history of significant medical, 
neurologic (other than stroke), or psychiatric disorders or known history of substance 
abuse that might preclude safe participation in the study in the opinion of the Investigator

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14. Known history of malignant disease within the last 5 years, including solid tumors and 
hematological malignancies (with the exception of basal cell and squamous cell 
carcinomas of the skin that have been completely excised and are considered cured)
15. Inability to comply with study requirements
16. Previous registration in this study
17. Other unspecified reasons that, in the opinion of the Investigator and/or Biogen, make the 
subject unsuitable for enrollment
18. Nursing or pregnant females or females planning to become pregnant during study 
participation
19. Known history of participation in any other investigational study that involved treatment 
with an investigational drug within 6 months prior to enrollment
20. Hypersensitivity reaction to present tissue plasminogen activator treatment

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9.
ENROLLMENT, REGISTRATION, AND RANDOMIZATION
9.1.
Screening and Enrollment
Subjects (or their legally authorized representative [e.g., parent or legal guardian], where 
applicable) must provide informed consent before any screening tests are performed (see 
Section 17.3).  When a subject signs the Informed Consent Form (ICF), that subject is considered
to be enrolled in the study.  Subjects will not be eligible for rescreening.
Participating study sites are required to document all screened candidates initially considered for 
inclusion in this study.  If a subject is excluded from the study, the reasons for exclusion will be 
documented in the subject’s source documents and on the screening log.
9.2.
Randomization and Registration of Subjects
Two separate randomization schemes will be used for subjects in the 2 treatment windows 
(i.e., ≤9 hours from LKN and >9 to ≤24 hours from LKN).  Within each treatment window, 
subjects will be randomized and registered by an Interactive Voice/Web Response System 
(IXRS) at Screening, after all Screening assessments have been completed and after the 
Investigator has verified that the subjects are eligible per criteria in Sections 8.1 and 8.2.  No 
subject may begin treatment prior to randomization and assignment of a unique subject 
identification number.  Any subject identification numbers that are assigned will not be reused 
even if the subject does not receive treatment.
Subjects in each treatment window will be randomized to receive natalizumab 300 mg, 600 mg,
or placebo in a 1:1:1 ratio (see Figure 1).  For subjects in the ≤9 hour treatment window, 
randomization will be stratified by baseline NIHSS category (NIHSS score 5 to 15 or 16 to 23),
tPA use (yes or no), and region; for subjects in the >9 to ≤24 hour treatment window, 
randomization will be stratified by tPA use (yes or no) and region.
Refer to the Study Reference Manual for details on registration and randomization.
As confirmation, IXRS will provide the Investigator with written verification of the subject’s 
registration by e-mail or fax.  Study treatment preparation and administration should commence 
as soon as confirmation of randomization and assignment of a drug kit number is received.
9.3.
Blinding Procedures
This is a randomized, double-blinded, placebo-controlled study.
All study staff will be blinded to the subject treatment assignments.  To maintain the study blind, 
it is imperative that subject treatment assignments are not shared with the subjects, their families, 
or any member of the study team, either at the study site or at Biogen.  
Matching placebo vials will be provided.

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10.
DISCONTINUATION OF STUDY TREATMENT AND/OR 
WITHDRAWAL OF SUBJECTS FROM THE STUDY
10.1.
Discontinuation of Study Treatment
Infusion of study treatment must be stopped immediately and permanently discontinued for any 
of the following reasons:

The subject is found to be pregnant.  Study treatment must be discontinued 
immediately.  Report the pregnancy according to the instructions in Section 15.4.1.

The subject experiences a hypersensitivity or suspected allergic reaction to study 
treatment

Subject consent for participation is withdrawn

The subject experiences a medical emergency that necessitates discontinuation of 
study treatment

The subject experiences a medical emergency that necessitates unblinding of the 
subject’s treatment assignment

At the discretion of the Investigator or the Sponsor (Biogen) for medical reasons
The reason for discontinuation of study treatment must be recorded in the subject’s electronic 
case report form (eCRF).  For all subjects who discontinue study treatment, safety data will be 
collected at the Day 90 Follow-Up visit.
10.2.
Withdrawal of Subjects From Study
Subjects must be withdrawn from the study for any of the following reasons:

Subject consent for participation is withdrawn.  

The subject enrolls into another interventional clinical study in which an 
investigational treatment or approved therapy for investigational use is administered.

The subject is unwilling or unable to comply with the protocol.
The reason for the subject’s withdrawal from the study must be recorded in the subject’s eCRF.  
The subject will be asked to complete early termination assessments in person.  If the subject 
cannot complete early termination assessments in person, a follow-up phone call or remote visit 
will be made to all subjects who withdraw from the study for purposes of collecting information 
on AEs/SAEs, FIM, mRS, BI, BDI-2, SIS-16, EQ-5D-3L, physical/neurological examination, 

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vital signs, hematology/blood chemistry, serum biomarkers, PD sampling, PK sampling, anti-
natalizumab antibodies, NIHSS, MoCA, SDMT, FSS, HRU, and concomitant therapy.
For all subjects who withdrew from the study, safety data will be collected at the Day 90 
Follow-Up or Early Termination visit.
Subjects who withdraw from the study will not be replaced.

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11.
STUDY TREATMENT USE
11.1.
Regimen
Refer to and follow the DHA.
11.2.
Modification of Dose and/or Treatment Schedule
The dose should be followed as described in Section 7.1.  No modifications of dose are allowed.
11.3.
Precautions
Subjects will be observed for 1 hour after the study treatment infusion is complete to allow 
monitoring for hypersensitivity reactions.
11.4.
Compliance
Compliance with treatment dosing is to be monitored and recorded by site staff.
11.5.
Concomitant Therapy and Procedures
11.5.1.
Concomitant Therapy
A concomitant therapy is any drug or substance administered between time of informed consent 
or authorization to enroll and completion of assessments at the Day 90 Follow-Up visit (as 
required by the protocol).  All thrombolytic treatments (i.e., IV and intra-arterial rtPA) and
mechanical thrombectomy that a subject receives are to be recorded as concomitant therapy 
regardless of whether they are given before or after the time of informed consent.
11.5.1.1.
Allowed Concomitant Therapy
Concomitant therapy with any of the following is allowed as long as the exclusion criteria 
described in Section 8.2 are observed:

Medications necessary for treatment of AEs according to the discretion of the 
Investigator.

Medications used in standard of care to treat stroke, cardiovascular risk factors, or 
other comorbid conditions, except for disallowed concomitant therapy.

Corticosteroids that are administered by non-systemic routes (e.g., topical or inhaled).  
Acute use of systemic corticosteroids is allowed in this study.

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11.5.1.2.
Disallowed Concomitant Therapy
Concomitant therapy with any investigational product is not allowed.
11.5.2.
Concomitant Procedures
A concomitant procedure is any therapeutic intervention (e.g., surgery/biopsy, physical therapy) 
or diagnostic assessment (e.g., blood gas measurement, bacterial cultures) performed between 
the time the subject is enrolled in the study and Safety Follow-Up.  All thrombolytic treatments 
and mechanical thrombectomy that a subject receives are to be recorded as concomitant 
procedures regardless of whether they are given before or after the time of informed consent.
The use of concomitant therapies or procedures defined above must be recorded on the subject’s 
eCRF, according to instructions for eCRF completion.  All AEs following the administration of 
these therapies or procedures must be documented on the appropriate eCRF, regardless of 
relatedness.
11.6.
Continuation of Treatment 
No further provisions are made for access to the study treatment.  If natalizumab is proven to be 
beneficial, all regulatory requirements regarding post-study access will be met.

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12.
STUDY TREATMENT MANAGEMENT
Study site staff should follow the DHA for specific instructions on the handling, preparation, 
administration, and disposal of the study treatment.  The DHA supersedes all other references 
(e.g., protocol).
Study treatment must be dispensed only by a pharmacist or appropriately qualified staff.  Study 
treatment is to be dispensed only to subjects enrolled in this study.  Once study treatment is 
prepared for a subject, it can be administered only to that subject.  Study treatment vials are for 
one-time use only; do not use any study treatment remaining in the vial for another subject.
12.1.
Natalizumab
Natalizumab is supplied as a liquid in 15-mL vials containing 300 mg of natalizumab per vial.  
Natalizumab drug product contains recombinant humanized anti-α4 integrin antibody and 
excipient materials (sodium phosphate monobasic monohydrate, sodium phosphate dibasic 
heptahydrate, sodium chloride, and polysorbate 80).
Natalizumab is manufactured by Biogen.  
The contents of the natalizumab label will be in accordance with all applicable regulatory 
requirements.  At a minimum, the label will include a study reference code, study treatment 
identifier, quantity of dosage units, lot number, and other pertinent information in accordance 
with local law.  The expiry or use-by date is stored in the interactive response technology (IRT) 
system, and printable assignment reports are available to site personnel.  Study treatment should 
not be used after the expiration, expiry, or use-by date.  
12.1.1.
Natalizumab Preparation
The individual preparing natalizumab should carefully review the instructions provided in the 
DHA.
If the packaging is damaged, or if there is anything unusual about the appearance or attributes of 
the vials or study treatment, do not use the study treatment.  The vials in question should be 
saved at the study site and the problem immediately reported to Biogen.
12.1.2.
Natalizumab Storage
Study treatment must be stored in a secure location.  
Natalizumab is to be stored at 2°C to 8°C (36°F to 46°F), protected from light in a monitored and 
locked refrigerator with limited access.  Study treatment is not to be frozen.  For the most up-to-
date storage requirements, follow the instructions provided in the DHA.

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12.1.3.
Natalizumab Handling and Disposal
The Investigator must return all used and unused vials of natalizumab as instructed by Biogen,
unless approved for onsite destruction.
If any study treatment supplies are to be destroyed at the study site, the institution or appropriate 
site personnel must obtain prior approval from Biogen by providing, in writing, the destruction 
policy or details of the method of destruction.  After such destruction, Biogen must be notified, 
in writing, of the details of the study treatment destroyed (e.g., lot or kit numbers, quantities), the 
date of destruction, and proof of destruction.
12.1.4.
Natalizumab Accountability
Accountability for study treatment is the responsibility of the Investigator.  The study site must 
maintain accurate records demonstrating dates and amount of study treatment received, to whom
study treatment was dispensed (subject-by-subject accounting), and accounts of any study 
treatment accidentally or deliberately destroyed or lost.  
Unless otherwise notified, all vials both used and unused must be saved for study treatment 
accountability.  At the end of the study, reconciliation must be made between the amount of 
study treatment supplied, dispensed, and subsequently destroyed, lost, or returned to Biogen.  A 
written explanation must be provided for any discrepancies.
12.2.
Placebo
Placebo is supplied as a liquid in 15-mL vials containing sodium phosphate monobasic 
monohydrate, sodium phosphate dibasic heptahydrate, sodium chloride, and polysorbate 80.
Placebo is manufactured by Biogen.
The label will include conditions for storage and other pertinent information required by local 
law, such as the lot/kit number and caution statement.  Placebo should not be used after the 
expiration date.

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13.
EFFICACY, PHARMACOKINETIC, AND 
PHARMACODYNAMIC ASSESSMENTS
See Section 4 for the timing of all assessments.
13.1.
Clinical Efficacy Assessments
The following clinical tests/assessments will be performed to assess the efficacy of natalizumab.  
Designation of eligibility criteria for performing the assessments will be provided in the Study 
Reference Manual.
mRS:  The mRS measures independence, rather than neurological function, with specific tasks 
pre- and poststroke [Bonita and Beaglehole 1988; Rankin 1957; Rankin 2003; van Swieten 
1988].  The scale consists of 7 grades, from 0 to 6, with 0 corresponding to no symptoms and 6 
corresponding to death.  Raters will be required to be certified in the use of the mRS.  The mRS
will be completed by a telephone interview for any subjects who fail to attend their Day 90 
Follow-Up or Early Termination visit.  The mRS takes less than 5 minutes to administer.
BI:  The BI consists of 10 items that measure a person’s daily functioning, specifically the 
activities of daily living and mobility [Collin 1988; Mahoney and Barthel 1965; Wade and Collin 
1988].  The items include feeding, moving from wheelchair to bed and returning, grooming, 
transferring to and from a toilet, bathing, walking on a level surface, going up and down stairs, 
dressing, and maintaining continence of bowels and bladder.  The assessment can be used to 
determine a baseline level of functioning and can be used to monitor change in activities of daily 
living over time.  The items are weighted according to a scheme developed by the authors.  The 
person receives a score based on whether they have received help while doing the task.  The 
scores for each of the items are summed to create a total score up to a maximum of 100.  The 
higher the score, the more “independent” the person is.  The BI takes less than 5 minutes to 
administer.
NIHSS: The NIHSS is a reliable tool for rapidly evaluating the effects of acute cerebral 
infarction [Lyden 1999].  Raters will be required to be certified in the use of the NIHSS.  A 
trained observer rates the subject’s ability to answer questions and perform activities relating to 
level of consciousness, language, visual-field loss, extraocular movement, motor strength, ataxia, 
dysarthria, sensory loss, and extinction and inattention (formerly neglect).  There are 15 items.  
Ratings for each item are scored with 3 to 5 grades, with 0 as normal and a maximum possible 
total severity score of 42 for all items.  There is an allowance for untestable items.  The test takes 
approximately 10 minutes to complete.   
SIS-16:  The SIS-16 is a 16-item physical dimension instrument that was developed as a brief, 
stand-alone tool for measuring the physical aspects of stroke recovery [Duncan 2003].  The 
16 physical aspects are rated on a 1 to 5 scale as follows:  not difficult at all (5), a little 
difficult (4), somewhat difficult (3), very difficult (2), and could not do at all (1).  The SIS-16 

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takes 5 to 10 minutes to complete and is also available in a proxy version that can be used when 
patients are unable to answer themselves. 
MoCA:  The MoCA is a global cognitive screening test with favorable psychometric properties 
[Cumming 2013; Pasi 2013]; it has been shown to be more sensitive to executive impairment 
than the Mini-Mental State Examination.  It screens 8 domains:  visuospatial/executive, naming, 
memory, attention, language, abstraction, delayed recall, and orientation.  The assessment takes 
approximately 10 minutes.  The highest possible total score is 30 points, and the assessment is 
available in 31 languages.
FIM:  The FIM instrument is a widely used functional performance measure developed 
specifically for the inpatient acute rehabilitation population.  It has been recommended by the 
Agency for Health Care Policy and Research Post-Stroke Rehabilitation panel as a measure of 
activities of daily living after stroke.  It is an 18-item instrument graded on a 7-point ordinal 
scale, with a maximum total score of 126.  The 7-point ordinal scale indicates the burden of care 
associated with each aspect of function.  The assessment is verbally administered by a certified 
rater to the patient or proxy and takes approximately 30 to 60 minutes to complete.  
SDMT:  The SDMT measures Informational Processing Speed in the visual modality.  This is a 
90-second timed test, patient respondent only.  Patients are presented with a key that includes 9
numbers, each paired with a different symbol.  Patients must then provide the correct numbers 
that accompany the symbols.  Both written and oral response versions are used and the SDMT 
takes only a few minutes to administer (including task instructions).  When used with the MoCA, 
SDMT has been found to improve accuracy in detecting post-stroke vascular cognitive 
impairment [Dong 2014].  Rater certification is required.  
FSS:  The FSS is a 9-item scale which measures the severity of fatigue and its effect on a 
person’s activities and lifestyle in patients with a variety of disorders.  The scale is self-reported 
or verbally administered and takes approximately 3 to 5 minutes to complete.  The items are 
scored on a 7 point scale with 1 = strongly disagree and 7= strongly agree.  The minimum total 
score is 9, and the maximum score possible is 63, with the higher the score indicating greater 
fatigue severity.
BDI-2:  The BDI-2 quantifies the severity of depression that has been evaluated in the setting of 
stroke.  It is a self-report inventory and can be self-administered or verbally administered.  This 
instrument rates items on a 4 point scale that ranges from 0 to 3.  Ratings are summed to provide 
a total score ranging from 0 to 63.
Subject direct resource use (HRU questionnaire):  The HRU questionnaire quantifies the 
amount of time patients spent in various settings of care (e.g., intensive care unit, general 
medical ward, skilled nursing facility, long-term care, Home with Support, Home without 
Support, etc), the 30-day readmission rate, and rehabilitation utilization.
EQ-5D-3L:  EQ-5D-3L is an instrument that evaluates the generic quality of life; it was 
developed in Europe and is widely used.  The EQ-5D-3L descriptive system is a preference-
based health-related quality of life measure with 1 question for each of the following 5 

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dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression.  This 
scale can be self-reported, proxy-respondent, or verbally administered and takes approximately 
10 minutes to complete.
13.2.
Pharmacokinetic Assessments
The following tests will be performed to assess the PK of natalizumab:

Serum concentrations of natalizumab at selected times after dosing
13.3.
Pharmacodynamic Assessments
The following tests may be performed to assess the PD properties of natalizumab:

Blood biomarkers of natalizumab target engagement

Serum cytokines and other inflammatory markers of stroke
Serum samples collected during the study may be used for other potential or exploratory 
biomarkers related to efficacy or safety related outcomes and/or natalizumab-VLA-4 
pharmacology. 
The purpose of serum sample collection is to develop potential predictive biomarkers throughout 
the study that may predict response to treatment or understand disease course and to develop 
potential PD markers through characterization of changes in blood cell transcription induced by 
the study treatment or disease course. A combination of linear modeling and machine learning 
approaches may be used to analyze the data.
Blood samples may be stored for up to 15 years after study completion for analyses.

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14.
SAFETY ASSESSMENTS
Refer to Section 4 for the timing of all safety assessments.
14.1.
Clinical Safety Assessments
The following clinical assessments will be performed to evaluate the safety profile of 
natalizumab: 

Medical history

Physical examinations and neurological assessments

Vital sign measurements:  temperature, pulse rate, systolic and diastolic blood 
pressure, and respiratory rate

Height and weight measurements

Concomitant therapy and procedure recording

Monitoring of AEs and SAEs
14.2.
Laboratory Safety Assessments
The following laboratory tests will be performed to evaluate the safety profile of natalizumab:

Hematology:  Complete blood count with differential and platelet count and absolute 
neutrophil count 

Blood chemistry:  total protein, albumin, creatinine, blood urea nitrogen, uric acid, 
bilirubin (total and direct), alkaline phosphatase, alanine aminotransferase, aspartate 
aminotransferase, gamma-glutamyl-transferase, glucose, calcium, phosphorus, 
bicarbonate, chloride, sodium, and potassium

Anti-natalizumab antibodies
Duplicate samples for laboratory assessments will be collected as a backup in case the original 
sample is lost or not evaluable.  All samples listed above will be sent to central laboratories.  
Standard of Care samples will be analyzed locally.

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15.
SAFETY DEFINITIONS, RECORDING, REPORTING, AND
RESPONSIBILITIES
Throughout the course of the study, every effort must be made to remain alert to possible AEs.  
If an AE occurs, the first concern should be for the safety of the subject.  If necessary, 
appropriate medical intervention should be provided.
At the signing of the ICF, each subject or his/her legally authorized representative and/or main 
caregiver must be given the names and telephone numbers of study site staff for reporting AEs 
and medical emergencies.
15.1.
Definitions
15.1.1.
Serious Pretreatment Event
A serious pretreatment event is any event that meets the criteria for SAE reporting (as defined in 
Section 15.1.3) and occurs after the subject or the subject’s representative signs the ICF or after 
enrollment is authorized by the site or by another process compliant with applicable national 
laws and regulations and IRB/EC requirements, but before administration of study treatment.
15.1.2.
Adverse Event
An AE is any untoward medical occurrence in a patient or clinical investigation subject 
administered a pharmaceutical product and that does not necessarily have a causal relationship 
with this treatment.  An AE can therefore be any unfavorable and unintended sign (including an 
abnormal laboratory finding), symptom, or disease temporally associated with the use of a 
medicinal (investigational) product, whether or not related to the medicinal (investigational) 
product.
Determination of whether an abnormal laboratory value meets the definition of an AE will be 
made by the Investigator.  Although abnormal laboratory values are typically not considered 
AEs, the following considerations may result in an abnormal laboratory value being considered 
an AE:

A laboratory test result that meets the criteria for an SAE

A laboratory test result that requires the subject to receive specific corrective therapy

A laboratory abnormality that the Investigator considers to be clinically significant
15.1.3.
Serious Adverse Event
An SAE is any untoward medical occurrence that at any dose:

Results in death

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
In the view of the Investigator, places the subject at immediate risk of death (a 
life-threatening event); however, this does not include an event that, had it occurred 
in a more severe form, might have caused death

Requires inpatient hospitalization or prolongation of existing hospitalization

Results in persistent or significant disability/incapacity

Results in a congenital anomaly/birth defect
An SAE may also be any other medically important event that, in the opinion of the Investigator, 
may jeopardize the subject or may require intervention to prevent one of the other outcomes 
listed in the definition above.  (Examples of such medical events include allergic bronchospasm 
requiring intensive treatment in an emergency room or convulsions occurring at home that do not 
require an inpatient hospitalization.)
15.1.4.
Prescheduled or Elective Procedures or Routinely Scheduled Treatments
A prescheduled or elective procedure or a routinely scheduled treatment will not be considered 
an SAE, even if the subject is hospitalized.  The study site must document all of the following:

The prescheduled or elective procedure or routinely scheduled treatment was 
scheduled (or was on a waiting list to be scheduled) prior to obtaining the subject’s 
consent to participate in the study.

The condition requiring the prescheduled or elective procedure or routinely scheduled 
treatment was present before and did not worsen or progress in the opinion of the 
Investigator between the subject’s consent to participate in the study and the time of 
the procedure or treatment.

The prescheduled or elective procedure or routinely scheduled treatment is the sole 
reason for the intervention or hospital admission.
o
If a subject is hospitalized due to local requirements for administration of the 
study treatment, the hospitalization should not be considered an SAE unless 
one of the requirements in Section 15.1.3 is met.
15.2.
Safety Classifications
15.2.1.
Investigator Assessment of Events
All events must be assessed to determine the following:

If the event meets the criteria for an SAE as defined in Section 15.1.3.

The relationship of the event to study treatment as defined in Section 15.2.2.

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
The severity of the event as defined in Section 15.2.3.
15.2.2.
Relationship of Events to Study Treatment
The following definitions should be considered when evaluating the relationship of AEs and 
SAEs to the study treatment.
Relationship of Event to Study Treatment
Not related
An AE will be considered “not related” to the use of the investigational drug if there is 
not a reasonable possibility that the event has been caused by the product under 
investigation.  Factors pointing toward this assessment include but are not limited to:  the 
lack of reasonable temporal relationship between administration of the drug and the 
event, the presence of a biologically implausible relationship between the product and the 
AE, or the presence of a more likely alternative explanation for the AE.
Related
An AE will be considered “related” to the use of the investigational drug if there is a 
reasonable possibility that the event may have been caused by the product under 
investigation.  Factors that point toward this assessment include but are not limited to:  a 
positive rechallenge, a reasonable temporal sequence between administration of the drug 
and the event, a known response pattern of the suspected drug, improvement following 
discontinuation or dose reduction, a biologically plausible relationship between the drug 
and the AE, or a lack of an alternative explanation for the AE.
15.2.3.
Severity of Events
The following definitions should be considered when evaluating the severity of AEs and SAEs:
Severity of Event
Mild
Symptoms barely noticeable to subject or does not make subject uncomfortable; does not 
influence performance or functioning; prescription drug not ordinarily needed for relief of 
symptoms but may be given because of personality of subject.
Moderate
Symptoms of a sufficient severity to make subject uncomfortable; performance of daily 
activity is influenced; subject is able to continue in study; treatment for symptoms may be 
needed.
Severe
Symptoms cause severe discomfort; symptoms cause incapacitation or significant impact 
on subject’s daily life; severity may cause cessation of treatment with study treatment; 
treatment for symptoms may be given and/or subject hospitalized.
15.2.4.
Expectedness of Events
Expectedness of all AEs will be determined by Biogen according to the Investigator’s Brochure. 

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15.3.
Monitoring and Recording Events
15.3.1.
Adverse Events
Any AE experienced by the subject between the time of first dose of study treatment (initiation 
of infusion [0 hour]) and the subject’s last study visit is to be recorded on the eCRF, regardless 
of the severity of the event or its relationship to study treatment.
15.3.2.
Serious Adverse Events
Any SAE experienced by the subject between the time of first dose of study treatment (initiation 
of infusion [0 hour]) and the subject’s last study visit is to be recorded on an SAE form, 
regardless of the severity of the event or its relationship to study treatment.  SAEs must be 
reported to 
 within 24 hours as described in Section 15.3.3.  Follow-up information 
regarding an SAE also must be reported with 24 hours. 
Subjects will be followed for all SAEs until the last study visit.  Thereafter, the event should be 
reported to 
 only if the Investigator considers the SAE to be related to study treatment.  
Any SAE that is ongoing when the subject completes or discontinues the study will be followed 
by the Investigator until the event has resolved, stabilized, or returned to baseline status.  If, after 
the subject’s last study visit, an SAE occurs in a subject, then the Investigator should report this 
event to the Sponsor as the Investigator becomes aware of each event.
15.3.3.
Immediate Reporting of Serious Adverse Events
In order to adhere to all applicable laws and regulations for reporting an SAE, the study site must 
formally notify 
 within 24 hours of the study site staff becoming aware of the SAE.  It is 
the Investigator’s responsibility to ensure that the SAE reporting information and procedures are 
used and followed appropriately.
Reporting Information for SAEs
Any SAE that occurs between the time that the subject has signed the ICF and the subject’s last 
visit must be reported to 
 within 24 hours of the study site staff becoming aware of the 
event.  Thereafter, the event should be reported only if the Investigator considers it related to 
study treatment.
A report must be submitted to 
 regardless of the following:

Whether or not the subject has undergone study-related procedures

Whether or not the subject has received study treatment

The severity of the event

The relationship of the event to study treatment

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To report initial or follow-up information on an SAE, fax a completed SAE form; refer to the 
Study Reference Manual for complete contact information.
15.3.3.1.
Deaths
Death is an outcome of an event.  The event that resulted in death should be recorded on the 
appropriate eCRF.  All causes of death must be reported as SAEs within 24 hours of the site 
becoming aware of the event.  The Investigator should make every effort to obtain and send 
death certificates and autopsy reports to 
.  The term death should be reported as an SAE 
only if the cause of death is not known and cannot be determined.
15.3.4.
Suspected Unexpected Serious Adverse Reactions
Suspected unexpected serious adverse reactions (SUSARs) are SAEs that are unexpected and 
judged by the Investigator or Biogen to be related to the study treatment administered.
Appropriate personnel at Biogen will unblind SUSARs for the purpose of regulatory reporting.  
Biogen will submit SUSARs (in blinded or unblinded fashion) to regulatory agencies according 
to local law.  Biogen will submit SUSARs to Investigators in a blinded fashion.
15.4.
Procedures for Handling Special Situations
15.4.1.
Pregnancy
Subjects should not become pregnant during the study and up to 3 months after their last 
dose of study treatment.  If a female subject becomes pregnant, study treatment must be 
discontinued immediately.
The Investigator must report a pregnancy by faxing the appropriate form to 
 within 
24 hours of the study site staff becoming aware of the pregnancy at the fax number found in the 
Study Reference Manual.  The Investigator or study site staff must report the outcome of the 
pregnancy to 
. 
Congenital abnormalities and birth defects in the offspring of male or female subjects should be 
reported as an SAE if conception occurred during the study treatment period.
15.4.2.
Overdose
An overdose is any dose of study treatment administered to a subject or taken by a subject that 
exceeds the dose assigned to the subject according to the protocol.  Overdoses are not considered 
AEs and should not be recorded as an AE on the eCRF; however, all overdoses must be recorded 
on an Overdose form and faxed to 
 within 24 hours of the site becoming aware of the 
overdose (see Study Reference Manual for fax number).  An overdose must be reported to 
 even if the overdose does not result in an AE.  If an overdose results in an AE, the AE 
must be recorded on the eCRF.  If an overdose results in an SAE, both the SAE and Overdose 

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forms must be completed and faxed to 
.  All study treatment-related dosing information 
must be recorded on the dosing eCRF.
15.4.3.
Medical Emergency
In a medical emergency requiring immediate attention, study site staff will apply appropriate 
medical intervention, according to current standards of care.  The Investigator (or designee) 
should contact the study’s Medical Monitor.  Refer to the Study Reference Manual’s Official 
Study Contact List for complete contact information.
15.4.3.1.
Unblinding for Medical Emergency
In a medical emergency when knowledge of the subject’s treatment assignment may influence 
the subject’s clinical care, the Investigator and, if applicable, designated personnel at Biogen 
may access the subject’s treatment assignment by IRT.  The Investigator must document the 
reasons for unblinding in the subject’s source documents.  The Investigator is strongly advised 
not to divulge the subject’s treatment assignment to any individual not directly involved in 
managing the medical emergency, nor to personnel involved with the analysis and conduct of the 
study.  The Investigator can contact Biogen or designee to discuss such situations.
15.5.
Contraception Requirements
All women of childbearing potential must practice effective contraception during the study and 
for at least 3 months after their last dose of study treatment.  
For the purposes of this study, women who do not meet one of the following criteria listed below 
are considered to be physiologically capable of becoming pregnant and are, therefore, defined as 
women of childbearing potential:

Postmenopausal
o
12 months of natural (spontaneous) amenorrhea without an alternative 
medical cause
o
6 weeks after surgical bilateral oophorectomy with or without hysterectomy

Posthysterectomy

Female surgical sterilization (e.g., bilateral tubal ligation)

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For the purposes of the study, highly effective contraception is defined as contraception that 
achieves a failure rate of less than 1% when used consistently and correctly, and includes the 
following:
For females:

Established use of oral, intravaginal, or transdermal combined (estrogen and 
progestogen containing) hormonal methods of contraception associated with the 
inhibition of ovulation.

Established use of oral, injected, or implanted progestogen-only hormonal methods of 
contraception associated with the inhibition of ovulation. 

Placement of an intrauterine device or intrauterine hormone-releasing system.

Bilateral tubal occlusion.

For female subjects participating in the study, male sexual partners must have 
undergone surgical sterilization with the appropriate postvasectomy documentation of 
the absence of sperm in the ejaculate.
For males:

Effective male contraception includes a vasectomy with negative semen analysis at 
follow-up. 
True abstinence, when this is consistent with the preferred and usual lifestyle of the subject, can 
be considered a highly effective method of contraception based on the evaluation of the 
Investigator who should also take into consideration the duration of the clinical study.  Periodic 
abstinence (e.g., calendar, ovulation, symptothermal, postovulation methods) and withdrawal are 
not considered acceptable methods of contraception.
Pregnancy reporting is described in Section 15.4.1.
15.6.
Safety Responsibilities
15.6.1.
The Investigator
The Investigator’s responsibilities include the following:

Monitor and record all AEs, including SAEs, regardless of the severity or relationship 
to study treatment.

Determine the seriousness, relationship, and severity of each event.

Determine the onset and resolution dates of each event.

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
Monitor and record all pregnancies and follow up on the outcome of the pregnancy in 
female subjects.

Complete an SAE form for each SAE and fax it to 
 within 24 hours of the 
study site staff becoming aware of the event.

Pursue SAE follow-up information actively and persistently.  Follow-up information 
must be reported to 
 within 24 hours of the study site staff becoming aware 
of new information.

Ensure all AE and SAE reports are supported by documentation in the subjects’ 
medical records.

Pursue AE follow-up information, if possible, until the event has resolved or become 
stable.

Report SAEs to local IRB/ECs, as required by local law.
15.6.2.
Biogen 
Biogen’s responsibilities include the following:

Before study site activation and subject enrollment, the Clinical Monitor is 
responsible for reviewing with study site staff the definitions of AE and SAE, as well 
as the instructions for monitoring, recording, and reporting AEs and SAEs.

Biogen is to notify all appropriate regulatory authorities, IRBs, central ECs, and 
Investigators of SAEs, as required by local law, within required time frames.

Safety data will be provided to the DSMC for review of all AEs and key laboratory 
tests for all subjects prior to completion of Study 101SK202. 

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16.
STATISTICAL METHODS AND DETERMINATION OF
SAMPLE SIZE
The objectives of the study and the endpoints to be analyzed are listed in Section 6.
16.1.
Efficacy
16.1.1.
Analysis Population
The efficacy analysis will include subjects who are randomized and have received the entire 
infusion of study treatment.
16.1.2.
Methods of Analysis
Unless otherwise specified, continuous variables will be summarized using summary statistics 
(mean, standard deviation, median, minimum, and maximum) by treatment group, and 
categorical variables will be presented using frequency distributions by timepoint and treatment 
group.  Point estimates and 95% CIs will be provided where applicable. 
Subgroup analysis by key factors (including baseline NIHSS category and tPA use) will be
performed for selected efficacy endpoints.
16.1.2.1.
Analysis of the Primary Endpoint
The primary endpoint is a global composite of an excellent outcome on the mRS (score of 0 or 1) 
and an excellent outcome on the BI (score of at least 95) at Day 90.  The primary analysis will be 
based on a Generalized Estimating Equation model and logit link function assuming a common 
OR of natalizumab versus placebo across 2 components of the endpoint: the proportion of 
subjects with an excellent outcome on the mRS and the proportion of subjects with an excellent 
outcome on the BI.  The model will include covariates of treatment window (≤9 hours from LKN 
vs. >9 to ≤24 hours from LKN), baseline NIHSS category, and tPA use.  The interaction between
treatment and treatment window will be assessed to determine whether the data of the 
2 treatment windows can be pooled.  If not, then data from the >9 to ≤24 hour window will be 
excluded from the analysis population of the primary endpoint and will be analyzed separately.  
The global OR of natalizumab (2 doses combined) and CIs will be provided. 
Sensitivity analyses will be performed to evaluate the impact of missing data, and the missing 
data handling will be specified in the statistical analysis plan (SAP).
Similar analyses for other timepoints, key subgroups, and each dose versus placebo will be 
performed.  The details will be provided in the SAP.
16.1.2.2.
Analysis of the Secondary Endpoints
The same analysis population for the primary endpoint as described in Section 16.1.2.1 will 
apply to the secondary endpoints. The same covariates used in the final modeling of the primary 

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endpoint will be adopted in all statistical models for the secondary endpoints described in this 
section.
16.1.2.2.1. mRS and BI at Day 90
The distribution of mRS at Day 90 will be analyzed by Van Elteren’s test.  The proportion of 
subjects who have excellent outcome in mRS (score of 0 or 1) at Day 90 will be analyzed by 
logistic regression.
The proportion of subjects with excellent outcome on mRS at other timepoints (Day 30, Day 5) 
will be analyzed similarly.  The mRS at each visit will also be analyzed using a mixed-effects 
model for repeated measures with treatment and treatment by visit interaction as explanatory 
variables.
The proportion of subjects who have an excellent outcome on the BI (score of at least 95) at Day 
90 will be analyzed by logistic regression.
The proportion of subjects with an excellent outcome on the BI at other timepoints (Day 30, Day 
5) will be analyzed similarly.  The BI at each visit will also be analyzed using a mixed-effects 
model for repeated measures with treatment and treatment–by-visit interaction as explanatory 
variables.
16.1.2.2.2. SIS-16 and MoCA at Day 90
Summary statistics of SIS-16 and MoCA at each visit will be presented by treatment group using 
observed data.
SIS-16 and MoCA at each visit will be analyzed by a mixed-effects model for repeated measures 
with treatment and treatment by visit interaction as explanatory variables. Treatment contrasts at 
Day 90 will be derived. 
In addition, MoCA assessments will be presented using summary statistics for the following 
categories: <10 (severe cognitive impairment), 10 to 17 (moderate cognitive impairment), and 
≥18 (mild cognitive impairment).
16.1.2.2.3. NIHSS at Day 90
The change in NIHSS score from baseline at each visit will be analyzed by a repeated-measures 
mixed model with treatment and treatment by visit interaction as explanatory variables.  
Treatment contrasts at Day 90 and other timepoints will be derived. 
The proportion of subjects who have an NIHSS score of 0 or 1 or who have demonstrated at least 
an 8-point improvement from baseline at Day 90 will be analyzed by logistic regression, 
adjusting for baseline NIHSS category and tPA use. 
NIHSS at other timepoints will be analyzed similarly.

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16.1.2.2.4. Dose-Response and Exposure-Response
In addition to the estimation of treatment effect of each dose versus placebo, trend testing 
[Armitage 1955; Cochran 1954] of a monotonically increasing dose response in proportion of 
excellent outcome on mRS and BI will be performed. Exposure-response models, including Emax
model of natalizumab, will be explored. The details will be provided in the SAP.
16.1.2.3.
Additional/Exploratory Endpoints Analysis
Analyses for exploratory efficacy endpoints will be provided in the SAP.
16.2.
Pharmacokinetics
16.2.1.
Analysis Population
Subjects who have received natalizumab at the 0 Hours Visit and had at least 1 measurable 
sample collected for the determination of natalizumab concentrations will be included in the 
analysis.
16.2.2.
Methods of Analysis
Serial natalizumab concentrations will be measured during the study.  Summary statistics for the 
concentration values will be calculated at each collection timepoint, and the mean concentrations 
(±standard error [SE]) will be plotted over time on both linear and logarithmic scales.  Plots for 
individual investigational sites will also be produced.
PK parameters will be calculated using noncompartmental methods 
.
Noncompartmental estimations of the various parameters will be calculated using Model 202 
(noncompartmental IV infusion) in the 
. Calculations will be 
performed using a “linear up/log down” algorithm, with a 1-hour infusion assumed. Points for 
the determination of terminal rate constants will be selected manually. Summary statistics for 
each PK parameter will be calculated. The following PK parameters will be determined for this 
study:

Cmax

Time to Cmax (tmax)

Area under the serum concentration versus time curve from dosing (time=0) to 
120 hours after dosing (AUC0-120)

Area under the serum concentration versus time curve from dosing (time=0) to 
672 hours after dosing (AUC0-672)

Area under the serum concentration versus time curve from dosing (time=0) to 
2160 hours after dosing (AUC0-2160) 

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
Area under the serum concentration versus time curve, from dosing (time=0) to last 
measurable concentration (AUC0-last)

Half-life (t½)

Time of last measurable concentration (tlast)

Volume of distribution (V)

Clearance (CL)
Concentrations reported as below the limit of quantification at any time after dosing will be 
treated as missing. The actual times of sample collection (and not the protocol-specified times) 
will be used in the calculation of all parameters.
16.3.
Pharmacodynamics
16.3.1.
Analysis Population
Subjects who have received the entire infusion of study treatment and have at least 
1 postbaseline assessment of the parameter being analyzed will be included in the PD analysis.
16.3.2.
Methods of Analysis
Summary statistics for α4-integrin saturation include the following:

Maximum % saturation [Rmax], time to Rmax [TRmax]

Percent saturation pre-dose [Rpre-dose] and percent saturation at the end of the dosing 
interval [R672] were calculated. 
The mean % saturation values (±SE) were plotted over time for both the entire study population 
and the individual dosing groups.
16.4.
Safety
16.4.1.
Analysis Population
The safety analysis will include subjects who are randomized and have received any portion of 
the infusion of study treatment.
16.4.2.
Methods of Analysis
No formal statistical testing will be performed on the safety data.

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16.4.2.1.
Adverse Events
The incidence of treatment-emergent AEs will be tabulated by treatment group, severity, and 
relationship to study treatment.  The tabular summaries will include incidence by system organ 
class and by preferred term.  SAEs and AEs resulting in study withdrawal will be summarized by 
treatment group.
Treatment-emergent AEs are those defined as having onset after the start of study treatment, or a 
sign, symptom, or diagnosis that worsens since the event was previously reported.  For the 
analysis of incidence by severity, the occurrence of the AE with the greatest severity will be 
used, and a subject will be counted only once and only in the category of the greatest severity for 
each event.  For the analysis of incidence by relationship to study treatment, the occurrence of 
the AE with the strongest relationship to study treatment will be used, and a subject is counted 
only once and only in the category of the strongest relationship to study treatment for each event.
16.4.2.2.
Clinical Laboratory Results
Clinically relevant abnormalities for laboratory parameters will be identified by treatment group 
using shift tables and evaluated for their clinical relevance.
16.4.2.3.
Vital Signs
The analysis of vital signs will focus on the incidence of clinically relevant abnormalities by 
treatment group.  
16.5.
Interim Analyses
An interim futility analysis may be performed after 50% of the study population has completed 
the Day 30 assessment. No interim stopping rules for superiority will be applied.
16.6.
Sample Size Considerations
A sample size of 270 (90 per treatment group) will provide at least 88% probability for the point 
estimate of the OR for the primary comparison of natalizumab (dose groups combined) versus 
placebo on the global composite measure at Day 90 to exceed 1.3 in both treatment windows 
(i.e., same efficacy for subjects being treated ≤9 hours and >9 to ≤24 hours from LKN),
assuming a true OR of 1.8 as observed in Study 101SK201.  Adopting a conservative assumption 
of a 50% reduction in treatment efficacy in the >9 to ≤24 hour treatment window when compared 
to the ≤9 hour treatment window, this probability will be at least 80%.  An OR of ≥1.3 on the 
global outcome measure is considered to be clinically meaningful based on the effect of tPA in 
the 3- to 4.5-hour time window.  At this sample size, the probability of observing a point 
estimate exceeding 1.3, if the true OR is ≤1 (i.e., the false positive rate), is less than 0.2.  In 
addition, if the true OR of the higher dose versus placebo is 3.0, as observed in the subgroup 
with exposure above the median in Study 101SK201, the probability of observing an OR of ≥1.3 
when comparing the 600- to 300-mg dose is at least 74%.

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17.
ETHICAL REQUIREMENTS
Biogen and 
 and the Investigator must comply with all instructions, regulations, and 
agreements in this protocol and applicable International Council on Harmonisation (ICH) and 
Good Clinical Practice (GCP) guidelines and conduct the study according to local regulations.
The Investigator may delegate responsibilities for study-related tasks where appropriate to 
individuals sufficiently qualified by education, training, and experience, in accordance with 
applicable ICH and GCP guidelines.  The Investigator should maintain a list of the appropriately 
qualified persons to whom significant study-related duties have been delegated.
17.1.
Declaration of Helsinki
This study will be performed in alignment with the ethical principles outlined in the Declaration 
of Helsinki.
17.2.
Ethics Committee
The Investigator must obtain EC approval of the protocol, ICF, and other required study 
documents prior to starting the study.  The Sponsor or designee will submit documents on behalf 
of the investigational sites in countries other than the US.
If the Investigator makes any changes to the ICF, Biogen must approve the changes before the 
ICF is submitted to the EC.  A copy of the approved ICF must be provided to Biogen.  After 
approval, the ICF must not be altered without the agreement of the relevant EC and Biogen.
It is the responsibility of the Investigators to ensure that all aspects of institutional review are 
conducted in accordance with current applicable regulations.
Biogen must receive a letter documenting EC approval, which specifically identifies the 
protocol, protocol number, and ICF, prior to the initiation of the study.  Protocol amendments 
will be subject to the same requirements as the original protocol.
A progress report must be submitted to the EC at required intervals and not less than annually.
At the completion or termination of the study, the investigational site must submit a close-out 
letter to the EC and Biogen.
17.3.
Subject Information and Consent
Prior to performing any study-related activities under this protocol, including screening tests and 
assessments, written informed consent with the approved ICF must be obtained from the subject 
or subject’s legally authorized representative (e.g., parent or legal guardian), as applicable, in 
accordance with local practice and regulations.  

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The background of the proposed study, the procedures, the benefits and risks of the study, and 
that study participation is voluntary for the subject must be explained to the subject (or the 
subject’s legally authorized representative).  The subject must be given sufficient time to 
consider whether to participate in the study.
A copy of the signed and dated ICF must be given to the subject or the subject’s legally 
authorized representative.  The signed and dated ICF will be retained with the study records.  
Local regulations must be complied with in respect to the final disposition of the original (wet 
signature) and copies of the signed and dated ICFs.
Confirmation of informed consent must also be documented in the subject’s medical record.
17.4.
Subject Data Protection
Prior to any testing under this protocol, including screening tests and assessments, candidates 
must also provide all authorizations required by local law (e.g., Protected Health Information 
authorization in North America).
The subject will not be identified by name in the eCRF or in any study reports, and these reports 
will be used for research purposes only.  Biogen, its partners and designees, ECs, and various 
government health agencies may inspect the records of this study.  Every effort will be made to 
keep the subject’s personal medical data confidential.
17.5.
Compensation for Injury
Biogen maintains appropriate insurance coverage for clinical studies and will follow applicable 
local compensation laws.
17.6.
Conflict of Interest
The Investigators should address any potential conflicts of interest (e.g., financial interest in 
Biogen or 
) with the subject before the subject makes a decision to participate in the 
study.
17.7.
Registration of Study and Disclosure of Study Results
Biogen will register the study and poststudy results regardless of outcome on a publicly 
accessible website in accordance with the applicable laws and regulations.

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18.
ADMINISTRATIVE PROCEDURES
18.1.
Study Site Initiation
The Investigator must not screen any subjects prior to completion of a study initiation visit, 
conducted by Biogen.  This initiation visit will include a detailed review of the protocol and 
study procedures.
18.2.
Quality Assurance
During and/or after completion of the study, quality assurance officers named by Biogen or the 
regulatory authorities may wish to perform onsite audits or inspections.  The Investigator will be 
expected to cooperate with any audit or inspection and to provide assistance and documentation 
(including source data) as requested.
18.3.
Monitoring of the Study
The Investigator must permit study-related monitoring by providing direct access to source data 
and to the subjects’ medical histories.
The Clinical Monitor will visit the Investigator at regular intervals during the study and after the 
study has completed, as appropriate.
During these visits, eCRFs and supporting documentation related to the study will be reviewed 
and any discrepancies or omissions will be resolved.  
Monitoring visits must be conducted according to the applicable ICH and GCP guidelines to 
ensure protocol adherence, quality of data, study treatment accountability, compliance with 
regulatory requirements, and continued adequacy of the investigational site and its facilities.
18.4.
Study Funding
Biogen is the Sponsor of the study and is funding the study.  All financial details are provided in 
the separate contracts between the institution, Investigator, and Biogen.  
18.5.
Publications
Details are included in the clinical study agreement for this study.

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19.
FURTHER REQUIREMENTS AND GENERAL INFORMATION
19.1.
External Contract Organizations
A CRO will be responsible for all administrative aspects of this study including but not limited to 
study initiation, monitoring, management of AEs, and data management.
19.1.1.
Contract Research Organization 
A CRO will be responsible for administrative aspects of the study including but not limited to 
study initiation, monitoring, and management of SAE reports and data management.  Before 
subjects are screened at each study site, the CRO will review study responsibilities with the 
Investigators and other study site staff, as appropriate.
19.1.2.
Interactive Response Technology
IRT will be used in this study.  Before subjects are screened or enrolled, the IRT vendor will 
provide each study site with the necessary training, a user manual, and access rights to the 
system.
19.1.3.
Remote Data Capture
Subject information will be captured and managed by study sites on eCRFs by a remote data 
capture (RDC) tool developed and supported by the RDC vendor and configured by Biogen.
19.1.4.
Central Laboratories for Laboratory Assessments
A central laboratory has been selected by Biogen to analyze all hematology and blood chemistry, 
PK sampling, and immunogenicity samples collected for this study.  Standard of Care samples 
will be analyzed locally.
Duplicate samples for laboratory assessments will be collected as a backup in case the original 
sample is lost or not evaluable.
19.1.5.
Central Facility for Other Assessments
A central facility has been selected by Biogen to perform imaging assessments for this study.  
19.2.
Study Committees
19.2.1.
Advisory Committee
An advisory committee will be formed to provide scientific and medical direction for the study 
and to oversee the administrative progress of the study.  The advisory committee will meet at 
regular intervals to monitor subject accrual and to monitor compliance with the protocol at 

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individual study sites.  The advisory committee will be blinded to subject treatment assignments.  
The advisory committee will determine whether the study should be stopped or amended for 
reasons other than safety.
Members of the advisory committee will include the Medical Director, the Clinical Operations 
Lead, and the Project Statistician from Biogen (and/or their designees), as well as participating 
Investigators who will be appointed by Biogen based on relevant expertise.  Biogen will 
designate one of the participating Investigators to be the chairperson of the advisory committee.
The Ongoing Data Review Committee will have an Ongoing Data Review Plan that is separate 
from the DSMC.
19.2.2.
Independent Data Safety Monitoring Committee 
An independent DSMC will be formed to review data regularly to assess safety and risk-benefit 
and recommend appropriate modification to the study or termination of the study.  The DSMC 
receives reports of all SUSARs, AEs, and key laboratory tests and meets throughout the study at 
regular timepoints described in the DSMC charter.
19.3.
Changes to Final Study Protocol
All protocol amendments must be submitted to the EC and regulatory authorities if required by 
local law.  Protocol modifications that affect subject safety, the scope of the investigation, or the 
scientific quality of the study must be approved by the EC before implementation of such 
modifications to the conduct of the study.  If required by local law, such modifications must also 
be approved by the appropriate regulatory agency prior to implementation.
However, Biogen may, at any time, amend this protocol to eliminate an apparent immediate 
hazard to a subject.  In this case, the appropriate regulatory authorities will be notified 
subsequent to the modification.
In the event of a protocol modification, the ICF may require similar modifications (see 
Section 17).
19.4.
Ethics Committee Notification of Study Completion or Termination
Where required, the regulatory authorities and ECs must be notified of completion or termination 
of this study, and sent a copy of the study synopsis in accordance with necessary timelines.
19.5.
Retention of Study Data
The minimum retention time for study records will meet the strictest standard applicable to that 
site, as dictated by any institutional requirements or local laws or regulations.  Prior to 
proceeding with destruction of records, the Investigator must notify Biogen in writing and 
receive written authorization from Biogen to destroy study records.  In addition, the Investigator 

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must notify Biogen of any changes in the archival arrangements including but not limited to 
archival at an offsite facility or transfer of ownership if the Investigator leaves the site.
19.6.
Study Report Signatory
Biogen will designate one of the participating Study Investigators as a signatory for the study 
report.  This determination will be made by several factors, including but not limited to, the 
Investigator’s experience and reputation in the studied indication; the Investigator’s contribution 
to the study in terms of design, management, and/or subject enrollment; or by other factors 
determined to be relevant by Biogen.

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20.
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Ischemic Stroke. The New England journal of medicine. 2015;372:2296-306.

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Disabil Stud. 1988;10(2):64-7.

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21.
SIGNED AGREEMENT OF THE STUDY PROTOCOL
I have read the foregoing protocol, “A Multicenter, Double-Blind, Placebo-Controlled, 
Randomized, Parallel-Group, Dose-Ranging Study to Evaluate the Safety and Efficacy of 
Intravenous Natalizumab (BG00002) in Acute Ischemic Stroke,” and agree to conduct the study 
according to the protocol and the applicable ICH guidelines and GCP regulations, and to inform 
all who assist me in the conduct of this study of their responsibilities and obligations.
____________________________________________________
Investigator’s Signature
Date
____________________________________________________
Investigator’s Name (Print)
____________________________________________________
Study Site (Print)

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The information contained herein may not be used, disclosed, or published without the written consent of 
Biogen MA Inc.
1
Biogen MA Inc.
250 Binney Street
Cambridge, MA  02142
United States
Biogen Idec Research Limited
Innovation House
70 Norden Road
Maidenhead Berkshire
SL6 4AY
United Kingdom
______________________________________________________________________
AMENDMENT SUMMARY
Biogen Protocol 101SK202/NCT02730455
A Multicenter, Double-Blind, Placebo-Controlled, Randomized, Parallel-Group, Dose-Ranging 
Study to Evaluate the Safety and Efficacy of Intravenous Natalizumab (BG00002) in Acute 
Ischemic Stroke
Version 3.0
Date:  03 May 2017
EUDRA CT Number:  2015-004783-11
Version 3.0 of the protocol has been prepared for this amendment, which supersedes Version 2.0 
(dated 15 December 2016).

Protocol 101SK202, Version 3.0
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Biogen MA Inc.
2
PRIMARY REASON FOR AMENDMENT
The primary reason for this amendment to Protocol 101SK202 is to correct an error in the 
pharmacokinetic (PK)/pharmacodynamic (PD) sampling times.  New text is shown in bold type; 
deleted text is shown with a strikethrough.

Protocol 101SK202, Version 3.0
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3
Section 4.2, Schedule of Activities
Now reads:
Table 1:
Schedule of Activities for Study 101SK202
Tests and Assessments
Screening1,2
0 Hours2
(Day 1)
Within 1 Hour 
After Start End of 
Infusion
12 Hours
±3 Hours
24 Hours
±6 Hours
Day 53
Day 304
±5 Days
Day 90 Follow-up4/
Early Termination4
±5 Days
Informed consent
X
Confirm eligibility
X
Demographics and medical 
history5
X
Physical and neurological 
examination
X
X
X
X
X
Vital signs6
X
X
X
X
X
X
X
Height (if available) and weight
X (anytime from Screening to Day 5 Visit)
Urine pregnancy test7
X
Hematology and blood 
chemistry
X
X
X
X
X
X
Serum biomarkers
X
X
X
X
X
X
PD sampling
X
X
X
X
X
X
X
PK sampling
X
X
X
X
X
X
X
Blood sample for 
anti-natalizumab antibodies
X
X
X
NIHSS
X
X2
X
X
X
X
mRS
X8
X
X
BI
X
X
X
SIS-16
X9
X
X
MoCA
X
X
X
Functional Independence 
Measure
X
X
SDMT
X
X
X
Fatigue Severity Scale
X9
X
X
Beck Depression Inventory 2
X9
X
X
HRU questionnaire
X
X
X
EQ-5D-3L
X
X
X
Study treatment administration10
X

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Tests and Assessments
Screening1,2
0 Hours2
(Day 1)
Within 1 Hour 
After Start End of 
Infusion
12 Hours
±3 Hours
24 Hours
±6 Hours
Day 53
Day 304
±5 Days
Day 90 Follow-up4/
Early Termination4
±5 Days
Stroke subtype classification11
X
SAE reporting
Record as per Section 15.3.2 of the protocol
AE reporting
Record as per Section 15.23.1 of the protocol
Concomitant medications
Record as per Section 11.5 of the protocol
Concomitant procedures
Record as per Section 11.5 of the protocol
AE = adverse event; BI = Barthel Index; BDI-2 = Beck Depression Inventory 2; CT= computed tomography; ECG = electrocardiogram; FIM = Functional Independence Measure; 
FSS = Fatigue Severity Scale; HRU = health resource utilization; LKN = last known normal; MoCA = Montreal Cognitive Assessment; MRI = magnetic resonance imaging; 
mRS = modified Rankin Scale; NIHSS = National Institute of Health Stroke Scale; PD = pharmacodynamic; PK = pharmacokinetic; SAE = serious adverse event; SDMT = 
Symbol-Digits Modalities Test; SIS-16 = Stroke Impact Scale-16.
Note:  All timepoints, except “within 1 hour after the end of the infusion”, are relative to start of study treatment administration.
1
All Screening assessments must be performed prior to infusion.  Screening assessments that are performed as standard of care do not need to be repeated for the study, 
provided that Biogen has access to the information and data are recorded in subject’s case report form.  Data collected for the Screening assessments will be used for patient 
baseline analysis in this study.  The ECG and CT or MRI assessments results should already be available at Screening (as they are performed as part of the standard of care), 
and a copy of the images and report should be filed with the subject’s study records.
2
All Screening assessments must be performed prior to infusion.  The 0 Hours vital signs assessments are to be performed within 15 minutes prior to study treatment 
administration.  If the Screening NIHSS is performed more than 1 hour prior to study treatment administration, it must be repeated during the visit at 0 Hours before study 
treatment administration.
3
Day 5 assessments are to occur on Day 5 or earlier if discharged, but must occur prior to discharge.
4
The subject will be asked to complete the Day 30 and Day 90 Follow-Up or Early Termination assessments in person (see Section 7.2.3 and Section 10.2).  If the subject is 
unable to return to the study center to complete the Day 30 or Day 90 (Follow-up or Early Termination) assessments in person, safety information will be collected by 
telephone or remotely, as local regulations allow and pending medical monitor approval, and will include the collection of AEs, SAEs, FIM, mRS, BI, BDI-2, SIS-16, EQ-5D-
3L, physical/neurological examination, vital signs, hematology/blood chemistry, serum biomarkers, PD sampling, PK sampling, anti-natalizumab antibodies, NIHSS, MoCA, 
SDMT, FSS, HRU, and concomitant medications.
5
Medical history should include an assessment of prior substance abuse.
6
Vital signs collected at each of the specified timepoints include temperature, blood pressure, pulse or heart rate, and respiratory rate.  Vital signs collected as part of the 
subject’s standard of care and that fall within 30 minutes of a study visit do not need to be repeated for the study, provided that Biogen has access to the information and data 
are recorded in the subject’s case report form.
7
Required only for women of childbearing potential.  If a serum beta human chorionic gonadotropin test was performed as part of the subject’s standard of care, the results will 
be accepted in lieu of the urine pregnancy test.
8
An mRS assessment will be done on Day 5, or earlier if discharged.
9
Per instructions on the SIS-16, BDI-2, and FSS forms, the subject or proxy should provide responses as it applies to the prior 2 week period.  When completing the SIS-16 
BDI-2, and FSS assessments during the Day 5 Visit, the subject or proxy should consider only the time period starting between the initial stroke (LKN) and the Day 5 Visit.
10
The subject must be observed for 1 hour after completion of infusion.11
The stroke etiology will be assessed based on the subject’s standard of care and diagnostic testing.  
This should be completed at Day 5 or earlier if discharged, but if results are incomplete, it may be completed at Day 30.

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Rationale:  As natalizumab (both 300 mg and 600 mg) and placebo are given as infusions over 2
hours, the original wording for the collection of PK/PD samples would not be appropriate as the 
infusion would still be ongoing.  Thus, a column heading in Table 1 was revised to ensure that 
the blood samples for PK/PD assessments, as well as vital sign measurements, are taken within 
1 hour after the infusion has stopped.
In order to get appropriate PK/PD results, the blood samples need to be taken within 1 hour after 
the infusion has stopped.
This change also affects Section 7.1, Study Overview.

Protocol 101SK202, Version 3.0
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SUMMARY OF MAJOR CHANGES TO THE PROTOCOL
Changes to the protocol are presented chronologically.  New text is shown in bold type; deleted 
text is shown with a strikethrough.
No other major changes were made to the protocol.

Protocol 101SK202, Version 3.0
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SUMMARY OF MINOR CHANGES TO THE PROTOCOL
The following minor changes were made to the protocol, as appropriate:

The version number and date were updated throughout the protocol.

The version number and date of the superseded version of the protocol were updated.

In Table 1, the Schedule of Activities, the Section numbers cited for serious adverse 
event and adverse event reporting were changed to the correct sections.

Changed the Note to include “within 1 hour after the end of the infusion”

The first sentence of footnote 2 was moved to the beginning of footnote 1

In Figure 1, Study Schema, a footnote was added to state PK/PD/biomarker sample 
times are conducted within 1 hour after the end of the infusion.

Minor format changes to Section 7.1 were made to ensure proper cross-referencing.

Spelled out examination throughout text (previously ‘exam’)

CONFIDENTIAL
The information contained herein may not be used, disclosed, or published without the written consent of 
Biogen MA Inc.
1
Biogen MA Inc.
250 Binney Street
Cambridge, MA  02142
United States
Biogen Idec Research Limited
Innovation House
70 Norden Road
Maidenhead Berkshire
SL6 4AY
United Kingdom
______________________________________________________________________
AMENDMENT SUMMARY
Biogen Protocol 101SK202/NCT02730455
A Multicenter, Double-Blind, Placebo-Controlled, Randomized, Parallel-Group, Dose-Ranging 
Study to Evaluate the Safety and Efficacy of Intravenous Natalizumab (BG00002) in Acute 
Ischemic Stroke
Version 2.0
Date:  15 December 2016
EUDRA CT Number:  2015-004783-11
Version 2.0 of the protocol has been prepared for this amendment, which supersedes Version 1.0.

Protocol 101SK202, Version 2.0
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The information contained herein may not be used, disclosed, or published without the written consent of 
Biogen MA Inc.
2
PRIMARY REASON FOR AMENDMENT
The primary reason for this amendment to Protocol 101SK202 is to remove unnecessary study 
procedures (i.e., 0 hour blood draw and the Functional Independence Measure at Day 5) and to 
add an expanded treatment window (>9 to ≤24 hours) in which subjects would be eligible for 
inclusion in the trial.
New text is shown in bold type; deleted text is shown with a strikethrough.
Section 4.2, Schedule of Activities
Now reads:
See pages 4 and 5 for updated schedule of activities.
Rationale:  To relieve the burden of too many procedures on the subjects and the study centers.
Section 7.1, Study Overview
Now reads:
This is a Phase 2, multicenter, double-blind, placebo-controlled, randomized, dose-ranging, 
3-arm study of natalizumab administered ≤924 hours from when the subject was LKN in subjects 
with acute ischemic stroke.  This study will evaluate the efficacy and safety of natalizumab over 
a 90-day period.  This study will be conducted at approximately 67 sites in the Unites States and 
Europe.
After completing screening assessments and fulfilling the criteria for study entry, eligible 
subjects in each of 2 treatment windows (≤9 hours and >9 to ≤24 hours from LKN) will be 
randomized in a 1:1:1 ratio to 1 of 3 treatment groups, each of which will receive a single dose at 
0 Hours (Day 1) according to one of the following 3 regimens:  600 mg IV natalizumab, 
300 mg IV natalizumab, or placebo IV.
Rationale:  In experimental rodent models, immune cell infiltration in the brain parenchyma 
following an ischemic stroke occurs predominantly after 24 hours of lesion onset, reaching its 
peak at approximately 3 days after the index event.  Congruently, blockage of maladaptive 
immune responses through immune modulatory treatments as far as 5 days after ischemia onset 
has been demonstrated to yield significant beneficial effects in rodent models, suggesting that 
therapies targeting lymphocyte infiltration after ischemia may have a prolonged therapeutic 
window.
A stratified randomization process was adopted in Study 101SK201 to evaluate the potential 
time dependency of treatment effect when administering 300 mg of natalizumab in a 9-hour 

Protocol 101SK202, Version 2.0
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window as compared to placebo.  In this study, half of the subjects in the intent-to-treat 
population were assigned to receive study treatment at ≤6 hours from last known normal (LKN), 
while the other half had study treatment administered within the >6 to ≤9 hour window.  Results 
from Study 101SK201 indicated that estimates of treatment effect favored natalizumab against 
placebo at both treatment windows, with no evidence of time dependency for the treatment 
benefit.  Likewise, the safety profile of natalizumab treatment was comparable in the ≤6 hour 
and the >6 to ≤9 hour treatment windows, with a small decrease in the proportion of deaths (21% 
and 15%, respectively) and serious adverse events (47% and 45%, respectively) being reported
among subjects treated in the later treatment window.
Based on these observations, the therapeutic window for natalizumab therapy appears to be 
greater than 9 hours.  Therefore, Study 101SK202 will further explore the time dependency of 
the treatment effect of natalizumab in patients with acute ischemic stroke by enrolling a limited 
number of subjects within the treatment window of >9 to ≤24 hours from LKN.
This change also affects Section 4.1, Study Schematic; Section 5.5, Rationale for the Treatment 
Window of ≤24 Hours from LKN; Section 6.2, Secondary Objectives and Endpoints; Section 
7.2.2, Treatment; Section 8.1, Inclusion Criteria; Section 9.2, Randomization and Registration of 
Subjects; Section 16.1.2.1, Analysis of the Primary Endpoint; Section 16.1.2.2, Analysis of the 
Secondary Endpoints; Section 16.1.2.2.1, mRS and BI at Day 90; Section 16.1.2.2.2, SIS-16 and 
MoCA at Day 90; Section 16.1.2.2.3, NIHSS at Day 90; Section 16.6, Sample Size 
Considerations; and Section 20, References.

Protocol 101SK202, Version 2.0
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Table 1:
Schedule of Activities for Study 101SK202
Tests and Assessments
Screening1,2
0 Hours
(Day 1)
Within 1 Hour 
After EndStart of 
Infusion
12 Hours
±3 Hours
24 Hours
±6 Hours
Day 53
Day 304
±5 Days
Day 90 Follow-up4/
Early Termination54
±5 Days
Informed consent
X
Confirm eligibility
X
Demographics and medical 
history65
X
Physical and neurological 
examination
X
X
X
X
X
Vital signs76
X
X
X
X
X
X
X
Height (if available) and weight
X (anytime from Screening to Day 5 Visit)
Urine pregnancy test87
X
Hematology and blood 
chemistry
X
X
X
X
X
X
X
Serum biomarkers
X
X
X
X
X
X
PD sampling
X
X
X
X
X
X
X
PK sampling
X
X
X
X
X
X
X
Blood sample for 
anti-natalizumab antibodies
X
X
X
NIHSS
X
X2
X
X
X
X
mRS
X98
X
X
BI
X
X
X
SIS-16
X109
X
X
MoCA
X
X
X
Functional Independence 
Measure
X
X
X
SDMT
X
X
X
Fatigue Severity Scale
X109
X
X
Beck Depression Inventory 2
X109
X
X
HRU questionnaire
X
X
X
EQ-5D-3L
X
X
X
Study treatment 
administration1110
X
Stroke subtype classification1211
X
SAE reporting
Record as per Section 15.2 of the protocol

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Tests and Assessments
Screening1,2
0 Hours
(Day 1)
Within 1 Hour 
After EndStart of 
Infusion
12 Hours
±3 Hours
24 Hours
±6 Hours
Day 53
Day 304
±5 Days
Day 90 Follow-up4/
Early Termination54
±5 Days
AE reporting
Record as per Section 15.2 of the protocol
Concomitant medications
Record as per Section 11.5 of the protocol
Concomitant procedures
Record as per Section 11.5 of the protocol
AE = adverse event; BI = Barthel Index; BDI-2 = Beck Depression Inventory 2; CT= computed tomography; ECG = electrocardiogram; FIM = Functional Independence Measure; 
FSS = Fatigue Severity Scale; HRU = health resource utilization; LKN = last known normal; MoCA = Montreal Cognitive Assessment; MRI = magnetic resonance imaging;
mRS = modified Rankin Scale; NIHSS = National Institute of Health Stroke Scale; PD = pharmacodynamic; PK = pharmacokinetic; SAE = serious adverse event; SDMT = 
Symbol-Digits Modalities Test; SIS-16 = Stroke Impact Scale-16.
Note:  All timepoints are relative to start of study treatment administration.
1
Screening assessments that are performed as standard of care do not need to be repeated for the study, provided that Biogen has access to the information and data are recorded 
in subject’s case report form.  Data collected for the Screening assessments will be used for patient baseline analysis in this study.  The ECG and CT or MRI assessments 
results should already be available at Screening (as they are performed as part of the standard of care), and a copy of the images and report should be filed with the subject’s 
study records.
2
All Screening assessments must be performed prior to infusion.  The 0 Hours vital signs assessments are to be performed within 15 minutes prior to study treatment 
administration.  If the Screening NIHSS is performed more than 1 hour prior to study treatment administration, it must be repeated during the visit at 0 Hours before study 
treatment administration.
3
Day 5 assessments are to occur on Day 5 or earlier if discharged, but must occur prior to discharge.
4
If the patient is unable to return to the study center to complete a visit in person, the Day 90 Follow-Up can be completed over the telephone or remotely, as local regulations 
allow and pending medical monitor approval.  The Day 90 Follow-Up consists of the collection of AEs, SAEs, FIM, mRS, BI, BDI-2, SIS-16, EQ-5D-3L, 
physical/neurological exam, vital signs, hematology/blood chemistry, serum biomarkers, PD sampling, PK sampling, anti-natalizumab antibodies, NIHSS, MoCA, SDMT, 
FSS, HRU, and concomitant medications.
54
The subject will be asked to complete the Day 30 and Day 90 Follow-Up or Early Termination assessments in person (see Section 7.2.3 and Section 10.2).  If the subject does 
notis unable to return to the study center to complete the Day 30 or Day 90 (Follow-up or Early Termination) assessments in person, safety information will be collected by 
telephone or remotely, as local regulations allow and pending medical monitor approval, and will include the collection of AEs, SAEs, FIM, mRS, BI, BDI-2, SIS-16, EQ-5D-
3L, physical/neurological exam, vital signs, hematology/blood chemistry, serum biomarkers, PD sampling, PK sampling, anti-natalizumab antibodies, NIHSS, MoCA, SDMT, 
FSS, HRU, and concomitant medications.
65
Medical history should include an assessment of prior substance abuse.
76
Vital signs collected at each of the specified timepoints include temperature, blood pressure, pulse or heart rate, and respiratory rate.  Vital signs collected as part of the 
subject’s standard of care and that fall within 30 minutes of a study visit do not need to be repeated for the study, provided that Biogen has access to the information and data 
are recorded in the subject’s case report form.
87
Required only for women of childbearing potential.  If a serum beta human chorionic gonadotropin test was performed as part of the subject’s standard of care, the results will 
be accepted in lieu of the urine pregnancy test.
98
An mRS assessment will be done on Day 5, or earlier if discharged.
109 Per instructions on the SIS-16, BDI-2, and FSS forms, the subject or proxy should provide responses as it applies to the prior 2 week period.  When completing the SIS-16 
BDI-2, and FSS assessments during the Day 5 Visit, the subject or proxy should consider only the time period starting between the initial stroke (LKN) and the Day 5 Visit.
1110 The subject must be observed for 1 hour after completion of infusion.
1211 The stroke etiology will be assessed based on the subject’s standard of care and diagnostic testing.  This should be completed at Day 5 or earlier if discharged, but if results are 
incomplete, it may be completed at Day 30.

Protocol 101SK202, Version 2.0
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SUMMARY OF MAJOR CHANGES TO THE PROTOCOL
Changes to the protocol are presented chronologically.  New text is shown in bold type; deleted 
text is shown with a strikethrough.
Section 3, Synopsis
The Synopsis was revised to reflect changes made throughout the protocol.
Section 8.1, Inclusion Criteria
Change:  A National Institute of Health Stroke Scale (NIHSS) Screening score for eligibility 
was added for the >9 to ≤24 hour treatment window, and NIHSS eligibility is to be confirmed 
within 60 minutes prior to randomization.
Now reads:
4.  Score of 5 to 23 points, inclusive, on the NIHSS at Screening for subjects initiating 
treatment ≤9 hours from LKN.  Note:  NIHSS eligibility must be confirmed within 
60 minutes prior to randomization.
5.  Score of 5 to 15 points, inclusive, on the NIHSS at Screening for subjects initiating 
treatment >9 to ≤24 hours from LKN.  Note:  NIHSS eligibility must be confirmed within 
60 minutes prior to randomization.
Rationale: The maximum NIHSS Screening score for subjects initiating treatment in the >9 to 
≤24 hour window was set at 15 points because prognosis associated with higher NIHSS scores is 
worsened when present at later time points.  The timeframe for confirming NIHSS eligibility was 
clarified to occur 60 minutes prior to randomization.
This change also affects Section 4.2, Schedule of Activities.
Section 8.2, Exclusion Criteria
Changes: (1) Patients with rapidly improving or minor stroke symptoms or (2) with petechial 
hemorrhages ≤1 cm are no longer excluded from the study.  (3) The statement regarding 
performing brain magnetic resonance imaging (MRI) to assess subject eligibility was removed.
The types of exclusionary strokes were clarified.  (4) The exclusion criteria regarding hepatitis 
infections and bacterial, fungal, or viral infections were simplified.

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Now reads:  
1.  Rapidly improving or minor stroke symptoms
2.1. Lacunar or isolated brainstem or cerebellar stroke based on clinical assessment and 
available acute imaging studies performed under the standard of care.  If it is unclear whether 
the subject has had a lacunar stroke based on clinical findings and head CT results, a brain MRI 
should be performed to assess eligibility, provided that all other inclusion criteria are met
3.2. Presence of acute intracranial hemorrhage on acute brain CT or MRI.  However, petechial 
hemorrhages of ≤1 cm are not exclusionary.
[…]
10.9. Known history of active viral hepatitis B or C positive test result for hepatitis C virus 
antibody or current hepatitis B infection (defined as positive for hepatitis B surface antigen 
[HBsAg] and hepatitis B core antibody [HBcAb]).  Subjects with immunity to hepatitis B from 
active vaccination or previous natural infection (defined as negative HBsAg, positive hepatitis B 
surface antibody immunoglobulin G, and negative HBcAb) are eligible to participate in the study 
(per the US Centers for Disease Control and Prevention’s interpretation of the hepatitis B 
serology panel)
13.12. Signs and Ssymptoms of bacterial, fungal, or viral infection (including upper respiratory 
tract infection) within 14 days prior to randomizationactive or acute infection
Rationale:  (1) Subjects who experience rapid improvement in stroke symptoms may still be 
eligible to participate in the study based on their NIHSS score at the time of eligibility. Subjects 
with an NIHSS score of 5 or more, as specified in the inclusion criteria, would not have minor 
stroke symptoms.  (2) A brain MRI is not a study procedure and should be performed according 
to standard of care.  Cerebellar strokes are considered exclusionary.  (3) Petechial hemorrhage is 
associated with baseline NIHSS and is commonly observed in moderate to severe ischemic 
strokes.  Petechial hemorrhage is not associated with poor clinical outcome and is easily 
distinguishable from parenchymal hemorrhage in imaging studies.  Results from Study 
101SK201 supported that treatment with natalizumab had no impact on the rate of hemorrhagic 
transformation.  Therefore, small petechial hemorrhages should not be considered exclusionary 
in this study.  In addition, petechial hemorrhages are likely to be randomly well balanced among 
the treatment arms because the randomization process stratifies for stroke severity. (4)
Laboratory testing for infections is not required as a study procedure, and the level of detail 
specified in the original exclusion criteria may be difficult to obtain from a patient’s medical 
history.  Furthermore, only active or acute infection events that are ongoing at the time of 
eligibility assessment should be considered exclusionary.
Section 11.5.1, Concomitant Therapy, and Section 11.5.2, Concomitant Procedures
Change:  Thrombolytic treatments/procedures will be recorded as concomitant regardless of 
whether they are given before or after informed consent.

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Section 11.5.1 now reads:
A concomitant therapy is any drug or substance administered between time of informed consent 
or authorization to enroll and completion of assessments at the Day 90 Follow-Up visit (as 
required by the protocol).  All thrombolytic treatments (i.e., IV and intra-arterial rtPA) and 
mechanical thrombectomy that a subject receives are to be recorded as concomitant 
therapy regardless of whether they are given before or after the time of informed consent.
Section 11.5.2 now reads:
A concomitant procedure is any therapeutic intervention (e.g., surgery/biopsy, physical therapy) 
or diagnostic assessment (e.g., blood gas measurement, bacterial cultures) performed between 
the time the subject is enrolled in the study and Safety Follow-Up.  All thrombolytic treatments 
and mechanical thrombectomy that a subject receives are to be recorded as concomitant 
procedures regardless of whether they are given before or after the time of informed 
consent.
Rationale:  All thrombolytic treatments need to be recorded.
Section 15.5, Contraception Requirements
Change:  Contraception requirements were updated.
Now reads:  
For the purposes of the study, highly effective contraception is defined as use of 1 or more of
contraception that achieves a failure rate of less than 1% when used consistently and 
correctly, and includes the following:
For females:

Established use of oral, intravaginal, or transdermal combined (estrogen and 
progestogen containing) hormonal methods of contraception associated with the 
inhibition of ovulation.

Established use of oral, injected, or implanted progestogen-only hormonal methods 
of contraception associated with the inhibition of ovulation. 

Placement of an intrauterine device or intrauterine hormone-releasing system.

Bilateral tubal occlusion

Barrier methods of contraception with use of a spermicide:  condom or occlusive cap 
(diaphragm or cervical/vault caps) with spermicidal foam/gel/film/cream suppository.  
The use of barrier contraceptives should always be supplemented with the use of a 
spermicide.

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
Male surgical sterilization (For female subjects participating in the study, male 
sexual partners must have undergone surgical sterilization with the appropriate 
postvasectomy documentation of the absence of sperm in the ejaculate).  (For female 
subjects participating in the study, male sexual partners must have undergone surgical 
sterilization.)
For males:

Effective male contraception includes a vasectomy with negative semen analysis at 
follow-up, or the use of condoms with spermicide.
True abstinence, when this is consistent with the preferred and usual lifestyle of the subject, can 
be considered an acceptablea highly effective method of contraception based on the evaluation 
of the Investigator who should also take into consideration the duration of the clinical study.
Rationale:  Contraception language was updated so that all subjects are instructed to use highly 
effective methods of contraception and so that the methods of highly effective contraception are 
defined consistently with the Clinical Trial Facilitation Group’s recommendations.
Section 16.6, Sample Size Considerations
Change:  The sample size was increased.
Now reads:  A sample size of 225270 (7590 per treatment group) will provide at least 8688% 
probability for the point estimate of the OR for the primary comparison of natalizumab (dose 
groups combined) versus placebo on the global composite measure at Day 90 to exceed 1.3, in 
both treatment windows (i.e., same efficacy for subjects being treated ≤9 hours and >9 to 
≤24 hours from LKN), assuming a true OR of 1.8 as observed in Study 101SK201.  Adopting a 
conservative assumption of a 50% reduction in treatment efficacy in the >9 to ≤24 hour
treatment window when compared to the ≤9 hour treatment window, this probability will 
be at least 80%.  An OR of ≥1.3 on the global outcome measure is considered to be clinically 
meaningful based on the effect of tPA in the 3- to 4.5-hour time window.  At this sample size, 
the probability of observing a point estimate exceeding 1.3, if the true OR is ≤1 (i.e., the false 
positive rate), is less than 0.2.  In addition, if the true OR of the higher dose versus placebo is 
3.0, as observed in the subgroup with exposure above the median in Study 101SK201, the 
probability of observing an OR of ≥1.3 when comparing the 600- to 300-mg dose is at least
7674%.  To allow for approximately 6% discontinuation before Day 90 (as observed in Study 
101SK201), 240 subjects will be randomized.
Rationale:  The sample size was increased to account for the addition of a new treatment 
window (>9 to ≤24 hours from LKN).

Protocol 101SK202, Version 2.0
CONFIDENTIAL
The information contained herein may not be used, disclosed, or published without the written consent of 
Biogen MA Inc.
10
SUMMARY OF MINOR CHANGES TO THE PROTOCOL
The following minor changes were made to the protocol, as appropriate:

The version number and date were updated throughout the protocol.

A Sponsor signature page was added.

The list of abbreviations was updated.

In Section 1, Sponsor Information, the information on how to contact the study’s 
Medical Monitor for urgent medical issues was updated.  This change also affects 
Section 15.3.3, Immediate Reporting of Serious Adverse Events, and Section 15.4.3, 
Medical Emergency.

In Section 7.1, Study Overview, clarification was made: the timing of post-treatment 
assessments are from the start of infusion and now reads as follows:  Post-treatment 
assessments will be performed at the following timepoints after the start of study 
treatment administration:  within 1 hour after the end start of the infusion, 
12 ± 3 hours after the end start of the infusion, 24 ± 6 hours after the end start of the 
infusion, Day 5, Day 30 (±5 days), and the Day 90 Follow-Up visit (±5 days).  This 
change also affects Section 4.2, Schedule of Activities.

In Section 7.1, Study Overview, the following statement from the Synopsis was 
added:  The study will be conducted at approximately 67 sites in the United 
States and Europe.

In Section 7.2.3, Follow-Up, clarification was made that subjects are to return to the 
site only for the Day 30 and 90 assessments and if subjects are unable to return to the 
site, these assessments can be done over the phone.  This section now reads:  Subjects 
are to return to the study site for a follow-up visit on Day 5, Day 30, and Day 90 
(Follow-Up Visit; the final study visit).  If the patientsubject is unable to return to the 
study center to complete a visit in person, the Day 5, Day 30, or the Day 90 
Follow-Up visits can be completed over the telephone or remotely, as local 
regulations allow and pending medical monitor approval.  This change also affects 
Section 4.2, Footnote 4 of the Schedule of Activities.

In Section 8.1, Inclusion Criteria, inclusion criteria were updated to identify the types 
of daily activities the patient was able to perform and now reads as follows:  56.  Prior 
to index stroke, patient was able to perform the following basic activities of daily 
living without assistance: dressing, eating, walking, bathing, and using the toilet.

In Section 10.2, Withdrawal of Subjects From Study, a statement was added to 
indicate that subjects who withdraw from the study will not be replaced.  It was 
clarified that information collected for early termination assessments can also be 
collected by a remote visit.

In Section 13.1, Clinical Efficacy Assessments, the reference to premorbid mRS was 
removed since it is not being collected.

Protocol 101SK202, Version 2.0
CONFIDENTIAL
The information contained herein may not be used, disclosed, or published without the written consent of 
Biogen MA Inc.
11

In Section 14.2, Laboratory Safety Assessments, the reference to anti-JCV serology 
testing was removed.  This also affects Section 19.1.4, Central Laboratories for 
Laboratory Assessments.

In Section 16.5, Interim Analyses, it was clarified that an interim analysis may be 
performed after 50% of the study population has completed the Day 30 assessment.

Typographical errors and formatting were corrected.