Phase 3 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 determine
whether dexpramipexole (150 mg twice daily) is safe and effective in the treatment of ALS.

Inclusion Criteria:

- Aged 18 to 80 years old, inclusive, on Day 1.

- Diagnosis of sporadic or familial ALS.

- Onset of first ALS symptoms within 24 months prior to Day 1.

- World Federation of Neurology El Escorial criteria are met for a possible,
laboratory-supported probable, probable, or definite ALS diagnosis.

- Upright slow vital capacity (SVC) of 65% or more at screening.

- Patients taking or not taking Riluzole are eligible for this study: if a patient has
never taken Riluzole, he or she is eligible; if a patient is currently taking
Riluzole, he or she must have been on a stable dose for at least 60 days; if a patient
has discontinued Riluzole, he or she must have stopped taking it for at least 30 days.

- Must be able to swallow tablets at the time of study entry.

Exclusion Criteria:

- Other medically significant illness.

- Clinically significant abnormal laboratory values.

- Pregnant women or women breastfeeding.

- Prior exposure to dexpramipexole.

- Currently taking pramipexole or other dopamine agonists.

Other protocol-defined inclusion/exclusion criteria may apply.