Extension Study of BIIB092 in Participants With Progressive Supranuclear Palsy (PSP) Who Participated in CN002003

This study, previously posted by Bristol-Myers Squibb, has transitioned to Biogen under a
licensing agreement.

Key Inclusion Criteria:

1. Completed treatment in Study CN002003.

2. A diagnosis of probable or possible PSP consistent with Study CN002003 criteria with
no new medical information or diagnoses since enrollment into Study CN002003 that
might confer doubt on the PSP diagnosis.

3. Able to tolerate Magnetic Resonance Imaging (MRI).

4. Able to perform all protocol-specified assessments and comply with the study visit
schedule.

5. Have reliable caregiver to accompany patient to all study visits. Caregiver must be
able to read, understand, and speak local language fluently to ensure comprehension of
informed consent and informant-based assessments of patient. Caregiver must also have
frequent contact with patient (at least 3 hours per week at one time or at different
times) and be willing to monitor the patient's health and concomitant medications
throughout the study.

6. Patient must reside outside a skilled nursing facility or dementia care facility at
the time of enrollment

7. Women of childbearing potential (WOCBP) and sexually active fertile men with partners
who are WOCBP must use highly effective birth control.

Key Exclusion Criteria:

1. Presence of an unstable, clinically significant medical condition other than PSP
including, but not limited to: hematological, endocrine, cardiovascular, renal,
hepatic, gastrointestinal, immunological, psychological or neurological disease or
malignancy.

2. Contraindication to undergoing a lumbar puncture (LP).

3. Recent drug or alcohol abuse as defined in Diagnostic and Statistical Manual of Mental
Disorders (4th Edition).

4. Treatment with any investigational drugs (including placebo) other than BIIB092 or
placebo given in Study CN002003 or devices within 90 days prior to enrollment

5. Any vaccination within 30 days prior to study drug administration.

6. Contraindication to the MRI examination for any reason

7. Any other sound medical, psychiatric, and/or social reason as determined by the
investigator

8. Known history of human immunodeficiency virus.

9. Evidence of organ dysfunction or significant deterioration from prior values in
CN002003 beyond what is consistent with the target population or that would place the
patient at increased risk or risk of early study discontinuation.

10. Inability to be venipunctured and/or tolerate venous access.

11. History of allergy, hypersensitivity, or serious adverse reaction to monoclonal
antibodies or related compounds or allergy to any of the components of the study drug

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply