Study to Evaluate the Safety & Efficacy of FLX-787-ODT to Treat Fasciculations in Tongue and Upper or Lower Extremity Muscles Most Affected in Subjects With ALS

Inclusion Criteria:

- Documented diagnosis of ALS diagnosis of less than 3 years.

- Expected survival > 6 months

- Frequent fasciculations noted during clinical examination of any single muscle (>6
visible fasciculations per minute) observed in Part I

- Normal oral cavity exam at screening

- Proficient in English

- Male subjects will either be surgically sterile or agree to use a medically acceptable
method of contraception during sexual contact with females of childbearing potential,
and will refrain from sperm donation for 45 days following the study

- Male subjects will either be surgically sterile or agree to use a medically acceptable
method of contraception during sexual contact with females of childbearing potential,
and will refrain from sperm donation for 45 days following the study

Exclusion Criteria:

- Presence of clinically significant or unstable condition that would result in an
increased risk of study participation or difficulty in interpretation of the study
results

- Tremor or other movement disorder that would interfere with recording

- Inability to lie flat

- Presence of major gastrointestinal disorders, such as inflammatory bowel disease,
diverticulitis, active peptic ulcer disease, or significant gastroesophageal reflux
disease (i.e., not well-controlled on antacids or proton pump inhibitors), or oral or
esophageal lesions/ulcers

- Presence of laryngospasm or significant swallowing problems

- Presence of percutaneous endoscopic gastrostomy, esophagogastroduodenoscopy, or G-tube

- Inability to tolerate a spicy sensation in the mouth or stomach

- Actively using illicit drugs or history of chronic substance abuse within the past
year prior to screening, including abuse of alcohol

- Participated in a clinical study (except natural history studies without
administration of an investigational product) within 30 days prior to screening

- Pregnant, breastfeeding, or planning to become pregnant

- Blood pressure of ≥160 mmHg systolic and/or ≥100 mmHg diastolic

- Clinically significant abnormalities in laboratory findings (including screening
complete electrolyte panel, complete blood count, liver function tests).