The objective of this study is to investigate the long term safety of ALS patients taking ONO-2506PO.

This is an extension study which consists of two phases:

Double-blind phase; Patients will continue to take blinded study medication, as allocated in study ONO-2506POE014 by the central randomization system, in the presence of stable standard Riluzole therapy, until un-blinding of the study results.

Open label phase; Patients who were allocated to ONO-2506PO in the ONO-2506POE014 study will be offered entry into the open label phase of ONO-2506POE015 study and will continue to take 1200 mg of ONO-2506PO for the duration of their participation in the study, in the presence of stable standard Riluzole therapy. Patients who were allocated to placebo in ONO-2506POE014 study will be withdrawn from ONO-2506POE015 study, but will continue to be followed up by their site with standard care.

Inclusion Criteria:

• Adult male and female patients with diagnosis of ALS over the age of 18 years.
• Previous randomization and completion of the last visits in ONO-2506POE014 study.
• Patients whom the investigator has no concern and judges tolerable for the continued treatment with ONO-2506PO and Riluzole from a risk and benefit point of view.

Exclusion Criteria:

• A clinically relevant medical history or presence of cardiovascular, gastrointestinal, renal, hepatic, endocrine/metabolic, neurologic, lymphatic, haematologic, immunologic, musculoskeletal, connective tissue, dermatologic, genito/urinary, psychiatric diseases or disorders that, in the opinion of the investigator may pose an unwarranted risk to the patient