The purpose of this study is to evaluate the pharmacokinetic and pharmacodynamic effect after a single dose or at steady state after multiple doses of AMX0035 in adults with sporadic ALS.

AMX0035 is a proprietary combination of two small molecules, phenylbutyrate (PB) and taurursodiol. The combination of PB and taurursodiol in AMX0035 is intended to block neuronal death and neurotoxic inflammation through simultaneous reduction of endoplasmic reticulum (ER) stress and mitochondrial stress. The pharmacokinetic of AMX0035 has been evaluated in healthy volunteers. This Phase IIa trial is intended to evaluate pharmacokinetic of PB and taurursodiol upon single dose multiple dose administration of AMX0035 in patients with ALS.

Inclusion Criteria:

1. Male or female, >=18years of age;

2. Diagnosis of sporadic ALS (definite, probable, laboratory probable, possible) made by physician experienced with management of ALS as defined by the World Federation of Neurology revised El Escorial criteria;

3. If taking riluzole, must be on a stable dose for >30 days prior to Day 1 and anticipated to remain at that dose until the final study visit.

4. If taking edaravone, must be on a stable regimen for > 30 days prior to Day 1 and infusion(s) can be scheduled to be performed at no less than 48 hours prior or after the planned pharmacokinetic and pharmacodynamic (PK/PD) sampling.

5. Capable of providing informed consent and following trial procedures;

6. Geographically accessible to the site;

7. Able to undergo the study procedures (including planned sampling on 3 occasions) and to adhere to the visit schedule, as determined by Investigator;

8. Women of child bearing potential (e.g. not post-menopausal for at least one year or surgically sterile) must agree to use adequate birth control for the duration of the study and 3 months after last dose of study drug;

   a. Women must not be planning to become pregnant for the duration of the study and 3 months after last dose of study drug

9. Men must agree to practice contraception for the duration of the study and for at least 3 months after last dose of study drug;

   1. Men must not plan to father a child or provide sperm for donation for the duration of the study and 3 months after last dose of study drug

   2. Acceptable birth control methods for use in this study are:

      • Hormonal methods, such as birth control pills, patches, injections, vaginal ring, or implants
      • Barrier methods (such as a condom or diaphragm) used with a spermicide (a foam, cream, or gel that kills sperm)
      • Intrauterine device (IUD)
      • Abstinence (no heterosexual sex)
      • Unique partner who is surgically sterile (men) or not of child bearing potential (female)

Exclusion Criteria:

1. Familial ALS

2. Forced vital capacity < 50% (or alternatively SVC) or presence of tracheostomy or under PAV (PAV is defined as more than 22 hours daily of non-invasive mechanical ventilation for more than 7 days);

3. Planned elective surgery (such as feeding tube or edaravone access port placement) during the duration of the study;

4. History of known allergy to PB or bile salts;

5. Abnormal liver function defined as aspartate aminotransferase and/or alanine aminotransferase (AST and/or ALT) > 3 times the upper limit of the normal;

6. Renal insufficiency as defined by eGFR < 60 mL/min/1.73m2;

7. Ongoing Anemia with Hg concentration < 10.0 g/dL

8. Pregnant women or women currently breastfeeding;

9. Current biliary disease which may lead to biliary obstruction or impedes biliary flow including active cholecystitis, primary biliary cirrhosis, sclerosing cholangitis, gallbladder cancer, gallbladder polyps, gangrene of the gallbladder, abscess of the gallbladder;

10. History of Class III/IV heart failure (per New York Heart Association - NYHA);

11. Patient under severe salt restriction where the added salt intake due to treatment would put the patient at risk, in the Site Investigator clinical judgement;

12. Presence of unstable psychiatric disease, cognitive impairment, dementia or substance abuse that would impair ability of the subject to provide informed consent, according to Site Investigator judgment;

13. Presence of an active infection requiring systemic antiviral or antimicrobial therapy at any time during the screening period.

14. Clinically significant unstable medical condition (other than ALS) that would pose a risk to the subject if they were to participate in the study, according to Site Investigator judgment.

15. Clinically significant, as determined by the Investigator, 12-lead ECG abnormalities at screening.

16. Treatment, current or within 90 days from start of study treatment, with any cell therapies or gene therapies;

17. Treatment, current or within 90 days from start of study treatment, with experimental medication (for ALS or other indications)

18. Current or anticipated need for a Diaphragm Pacing System (DPS);

19. Anything that, in the opinion of the Site Investigator preclude the subject's full compliance with or completion of the study;

20. Exposure to any disallowed medications listed below:

    1. HDAC Inhibitors including:

       • Valproate
       • Vorinostat (Zolinza)
       • Romidepsin
       • Chidamide
       • Panobinostat
       • Lithium
       • Butyrate
       • Suramin

    2. Probenecid

    3. Bile Acid Sequestrants including:

       • Cholestyramine and Cholestyramine Light
       • Questran and Questran Light
       • Welchol
       • Colestid and Colestid Flavored
       • Prevalite

    4. Product that may interact with sterol absorption or excretion

       • Ezetimibe

    5. Note on Antacids within Two Hours of AMX0035 Administration: Antacids containing aluminum hydroxide or smectite (aluminum oxide) may not be taken within two hours of administration of MX0035 as they inhibit absorption of taurursodiol. These include:

       • Alamag
       • Alumina and Magnesia
       • Antacid, Antacid M and Antacid Suspension
       • Gen-Alox
       • Kudrox
       • M.A.H.
       • Maalox HRF and Maalox TC
       • Magnalox
       • Maldroxal
       • Mylanta and Mylanta Ultimate
       • Ri-Mox
       • Rulox

21. Clinically significant, in the opinion of the Investigator, infection or inflammation at time of screening or admission.

22. Acute gastrointestinal symptoms (eg, nausea, vomiting, diarrhea) at time of screening or admission or a or clinical diagnosis of irritable bowel syndrome (IBS) per ROME criteria (Appendix 7).

23. Any current or previous illicit use of Class A drugs such as opiates, cocaine, ecstasy, LSD, and amphetamines (Class B).

24. An alcoholic intake greater than 14 units per week or unwillingness to stop alcohol consumption for the duration of the study. Note: 1 unit = 8 g ethanol (250 mL of beer or approximately 10 oz, 1 glass wine [100 mL or approximately 3 oz], 1 measure spirits [30 mL or approximately 1 oz]).

25. Use of drugs with enzyme inducing properties such as St John's Wort within 3 weeks prior to the first administration of investigational product.

26. History of plasma/blood donation in the last 2 months.

27. Any condition, which compromises ability to give informed consent or to communicate with the Investigator as required for the completion of this study.

28. Unwilling to conform to all lifestyle considerations and restrictions mandated by the protocol.