Phase 3 Extension Study of Dexpramipexole in ALS

Amyotrophic Lateral Sclerosis (ALS) is a rapidly progressive, degenerative disease of motor
neurons in the brain and spinal cord that leads to muscle atrophy and spasticity in limb and
bulbar muscles resulting in weakness and loss of ambulation, oropharyngeal dysfunction,
weight loss, and ultimately respiratory failure. The purpose of this study is to collect
long-term safety data from subjects with Amyotrophic Lateral Sclerosis (ALS) exposed to
dexpramipexole.

Inclusion Criteria:

- Subject has the ability to understand the purpose and risks of the study and provide
signed and dated informed consent (or have the consent confirmed by a witness if
unable to write) and authorization to use protected health information (PHI) in
accordance with national and local subject privacy regulations.

- Subject was enrolled in either CL211 (NCT00931944) or Study 223AS302 (NCTO1281189).

- Subject has completed their last visit in Study CL211 (NCT00931944) or Study 223AS302
(NCTO1281189).

- Subjects of childbearing potential must practice effective contraception during the
study and be willing and able to continue contraception for 1 month (females) or 3
months (males) after their last dose of study treatment.

Exclusion Criteria:

- Subject withdrew prematurely from Study CL211 (NCT00931944) or Study 223AS302
(NCTO1281189).

- Subject permanently discontinued study treatment in Study CL211 (NCT00931944) or Study
223AS302 (NCTO1281189) for any reason other than enrollment into this study.

- Subject from Study CL211 (NCT00931944) or Study 223AS302 (NCTO1281189) has a
significant change in medical history (including laboratory tests or a clinically
significant condition) that in the opinion of the Investigator would impair the
subject's medical fitness for participation and preclude treatment.

- Female subject who is pregnant or breastfeeding.

- Subject is currently enrolled in any investigational drug study other than Study CL211
(NCT00931944) or Study 223AS302 (NCTO1281189).

- Subject is taking pramipexole, other dopamine agonists, any other agent with
dopaminergic activity, or any other disallowed concomitant medication.

- Subject is unwilling or unable to comply with the requirements of the protocol
including the presence of any condition (physical, mental, or social) that is likely
to affect the subject's ability to comply with the protocol. At a minimum, subjects
who are not able to travel to the study site must be willing to agree to remote blood
draws for clinical laboratory evaluations and telephone visits to report Adverse
Events, concomitant medications, and Amyotrophic Lateral Sclerosis Functional Rating
Scale (revised) (ALSFRS-R) scores.