- Male/ Female 18-75 years of age
- Clinically definite, laboratory probable, or clinically probable ALS
- ALS symptom onset < 2 years prior to screening visit
- Subjects on riluzole may enter the study if they have been on a stable dose of 50mg BID for >4 weeks prior to screening visit.
- Subject has participated in any previous ALS drug study unless at least 5 half lifes have passed since last dose and screening visit
- Subject has participated in any non-ALS therapeutic (drug or device) trial in the 4 weeks prior to screening visit.