This study assessed the efficacy and safety of ADS-5102 (at daily doses of 137 mg or 274 mg) compared with placebo in MS patients with walking impairment.

This was a multicenter, 3-arm, randomized, placebo-controlled, double-blind, parallel-group study of ADS-5102 (amantadine) extended release capsules in MS subjects with walking impairment. The study consisted of a screening period (up to 3 weeks), a single-blind placebo run-in period (4 weeks; during which subjects were blinded to treatment), and a double-blind treatment period (12 weeks).

For at least 30 days prior to screening, all subjects were to have received a stable regimen of MS medications, both disease-modifying and symptomatic; these medications were to continue at the same doses and regimens for the duration of the subjects' participation in the study, to the extent compatible with good neurological care. Subjects were not to have used amantadine, dalfampridine, or any 4 aminopyridine or 2,4 diaminopyridine preparation within 30 days prior to screening.

Consented subjects who completed the screening period were to undergo a 4-week single-blind placebo run-in period during which they received placebo as 2 capsules once daily at bedtime.

Subjects who completed the single-blind placebo run-in period and continued to meet study eligibility criteria were randomized with equal probability to 1 of 3 treatment groups: placebo or ADS-5102 at a final dose of 137 mg/day or 274 mg/day. Study drugs were administered as 2 capsules once daily at bedtime.

Subjects were to return to the clinic for safety and efficacy assessments at Week 0 and Week 2 prior to randomization and at Weeks 4 (randomization and baseline visit), 6 (only safety), 8, 12, and 16 after randomization. In addition, telephone visits for safety assessments were conducted at Weeks 5 and 7. Subjects who withdrew from the study before Week 16 were to have an early termination visit that included safety follow-up and efficacy assessments, as appropriate.

Inclusion Criteria:

• Signed a current IRB-approved informed consent form
• Male or female subjects between 18 and 70 years of age, inclusive, at the time of Screening
• Confirmed diagnosis of MS according to the 2017 McDonald criteria
• Current medication regimen must be stable for at least 30 days prior to screening, and subject must be willing to continue the same dosing regimen for the duration of study participation
• Maximum Expanded Disability Status Scale (EDSS) score during screening of 6.5
• Stable physical activity level (inclusive of prescribed physical therapy) for at least 30 days prior to screening and willing to continue without change for the duration of study participation
• A score on each of two completed screening T25FW tests between 8 and 45 seconds, inclusive

Exclusion Criteria:

• Documented inability to tolerate amantadine
• Clinically significant MS relapse with onset less than 30 days prior to screening
• Receipt of dalfampridine (or any 4-aminopyridine or 2,4-diaminopyridine preparation) or amantadine within 30 days prior to screening
• History of seizures within 3 years prior to screening
• History of hallucinations (visual, auditory, or any other type) within 3 years prior to screening
• History of bipolar disorder, schizophrenia, or psychosis, regardless of treatment
• For subjects with a history of major depressive disorder, the presence of active depressive symptoms that, in the opinion of the investigator, would affect the subject's ability to complete study assessments, or which would not be in the subject's best interest to participate in the study
• Presence of orthostatic hypotension at screening: a decrease in systolic blood pressure (at least 20 mm Hg) or diastolic blood pressure (at least 10 mm Hg) within 3 minutes of the subject standing up, compared to pressures obtained while sitting
• If female, is pregnant or lactating
• If a sexually active female, is not surgically sterile or at least 2 years post-menopausal, or does not agree to utilize a highly effective hormonal method of contraception (an IUD, or vasectomized male partner is also acceptable), in combination with a barrier method, from screening through at least 4 weeks after the completion of study treatment. If a sexually active male, does not agree to utilize condoms from screening through at least 4 weeks after the completion of study treatment.
• Treatment with an investigational drug or device within 30 days prior to screening
• Treatment with an investigational biologic within 6 months or 5 half-lives, whichever is longer, prior to screening