This clinical trial is being conducted to learn about safety and tolerability of digoxin in ALS individuals. Additionally, this trial aims to better understand if digoxin has an effect on slowing neurodegeneration in ALS.

This is a single-arm, Phase 2a, open label, 24-week treatment trial evaluating standard clinical dosages of commercially available, FDA approved oral digoxin in up to 40 eligible ALS participants with early disease (<24 months from symptom onset). The trial will include two cohorts of eligible participants; Cohort 1 of approximately 30 sporadic/non-C9 ALS and Cohort 2 of approximately 10 C9orf72(+) ALS individuals.

Inclusion Criteria:

1. Ability to provide written informed consent.

2. Adults >18 years of age with a diagnosis of symptomatic ALS as determined by an ALS neurologist, and meets either the revised El Escorial Criteria (clinically possible, probable, probable lab-supported, or definite) or the Gold Coast Criteria.

3. Available or pending CLIA certified ALS genetic panel report.

4. Less than or equal to 24-months since onset of weakness attributed to ALS.

5. Vital capacity (VC) of > 65% predicted value for gender, height and age at screening.

6. Clinically unremarkable Complete Blood Counts, including but not limited to Hemoglobin ≥ 9 g/dL, Platelets ≥ 150 x 109 cells/L.

7. No clinically significant abnormalities in the Comprehensive Metabolic Panel per site/sub-investigator's judgment, including but not limited to:

   1. Serum alanine aminotransferase or aspartate aminotransferase < 3× upper limit of normal, or serum total bilirubin <1.5× upper limit of normal
   2. Estimated GFR (eGFR) of > 30 mL/min/1.73m2
   3. Other clinically significant electrolyte and metabolic abnormalities

8. Ability and willingness to complete all study procedures per the Site Investigator's clinical assessment.

9. Negative pregnancy test within 7 days prior to first dose for women of child-bearing potential (WOCB), defined as a sexually mature woman who has not undergone a hysterectomy or who has not been naturally postmenopausal for at least 24 consecutive months (i.e., who has had menses any time in the preceding 24 consecutive months).

10. Individuals enrolling in the C9orf72 cohort of the trial must have CLIA certified ALS gene panel demonstrating >31 repeats of C9orf72 hexanucleotide repeat expansion, deemed pathologic.

Exclusion Criteria:

• 1. Clinically significant unstable medical or surgical condition that would pose a risk to the participant's trial procedural participation or interfere with data collection, according to the Site Investigator's judgment (e.g., active infection requiring antibiotics).

  2. Presence of cognitive or mental health disorders impairing ability to provide informed consent for the study per Site investigator assessment.

  3. Active cancer or history of cancer, unless it was successfully treated for durable remission or cure more than 3 years ago. (Note that basal cell carcinoma, squamous cell carcinoma in situ, cervical carcinoma in situ, prostatic carcinoma in situ, or other malignancies that have been curatively excised at any time previously and with no evidence of disease recurrence for at least 3 years are not exclusionary.) 4. Prior solid organ transplantation. 5. Concomitant use of investigational treatments for ALS within 5 half-lives or 30 days, whichever longer.

  6. Screening 12-lead ECG showing QT interval corrected for rate (QTcF) > 470 msec for women and > 450 msec for men, absence of second degree or higher AV block or other clinically significant cardiac arrythmias.

  7. If female, breastfeeding, pregnant, or of child-bearing potential and unwilling to use effective contraception for duration of the trial and after discontinuing treatment.

  8. Serious cardiac condition within the last 6 months, such as uncontrolled arrhythmia, myocardial infarction, unstable angina, or heart disease defined by the New York Heart Association (NYHA) Class III or Class IV or hereditary long QT syndrome.

  9. Exclusion criteria for Lumbar Punctures: active bleeding tendencies OR inability to withhold antiplatelets or anticoagulants safely as per institutional guidelines around LPs OR anatomical spine considerations making it unsafe or challenging for serial LPs OR allergy to local anesthesia used for procedure.

  10. Clinically active cardiac disorders including sinus bradycardia (HR <40 bpm) or sinus tachycardia (HR>140 bpm), cardiac arrythmias [first-degree, second-degree (Wenckebach), or third-degree heart block; atrial tachycardia with block; AV dissociation; accelerated junctional (nodal) rhythm; unifocal or multiform ventricular premature contractions (especially bigeminy or trigeminy); ventricular tachycardia; and ventricular arrythmias]; Persistent or chronic atrial fibrillation that is not controlled using standard medications 11. Concomitant treatment with amiodarone at any dose or quinidine at a dose greater than 20 mg/day