REFINE-ALS is a prospective, observational, longitudinal, multicenter study designed to identify biomarkers to serve as quantifiable biological non-clinical measures of Edaravone effects in ALS. Epigenetic and protein biomarkers will also be investigated.

Treatment will be prescribed by HCPs in accordance with their clinical judgement and the prescribing information for Edaravone. The decision to prescribe Edaravone to the participants should be made separately from the decision to enroll then in the study. There will be no randomized assignments to treatment and no restrictions on the use of commercially available medications (but those participating in an experimental study, even if taking Edaravone, will be excluded). No experimental treatment is evaluated in this study. The intervention is limited to the collection of blood and urine samples for biomarker testing.

During the estimated study period, eligible patients who are prescribed Edaravone within the approved indication will be invited to participate in the study. An initial screening/baseline visit will be scheduled for participants who are considered for study participation.

Participants in this study will be followed from enrollment up to 24 weeks after treatment initiation (6 treatment cycles [each cycle consisting of 28 days], corresponding to a treatment period of approximately 24 weeks) or premature study discontinuation. Throughout the study period, the investigators will record participant baseline and follow-up information and perform clinical and biomarker assessments.

Inclusion Criteria:

• Male and female aged 18 years or older at enrollment
• Sporadic or familial ALS diagnosed as possible, probable, probable-laboratory supported or definite as defined by the World Federation of Neurology revised El Escorial criteria
• Decision made to prescribe Edaravone prior to screening
• Participant will likely be able to obtain commercial Edaravone and likely to complete 6 cycles of treatment, per site investigator estimation
• Participant either naïve to Edaravone or who did not receive any Edaravone does within 1 month prior to screening
• Signed informed consent by the subject, or a witness if a subject cannot read or write or is physically unable to talk or write, obtained before any study-related activities are undertaken

Exclusion Criteria:

• Participant with a contraindication to Edaravone
• Participant is participating in an interventional clinical trial

This study will be conducted in participants who have sporadic or familial amyotrophic lateral sclerosis (ALS) as defined by revised El Escorial criteria. Participants must provide written informed consent prior to screening. At screening, eligible patient must be at least 18 years old with a decision made to prescribe Edaravone prior to consenting. Participants who are either Edaravone naïve or who did not receive any Edaravone dose within one month of consenting are eligible for inclusion given they meet all other protocol requirements.