Task Oder 9: RSA D PRIDOPIDINE Home Spirometry and Open-Label Extension (OLE) Period

Task Oder 9: RSA D PRIDOPIDINE Home Spirometry and Open-Label Extension (OLE) Period Regimen-Specific Appendix [D] For pridopidine 45 mg oral capsule administered twice daily (BID) or its matching placebo. Rationale and RSA Design The proposed study is based on cumulative preclinical and clinical studies that demonstrate that pridopidine acts primarily as a Sigma-1 Receptor (S1R) agonist and demonstrates neuroprotective properties mediated by S1R. The purpose of this study is to evaluate the effect of pridopidine 45 mg BID on ALS functional decline, specifically bulbar, upper and lower limb, and respiratory function in participants with ALS. Allocation to Treatment Regimens Participants must first be screened under the Master Protocol before they are randomized to a regimen. As soon as pre-defined criteria for futility for the regimen are met, or the target number of randomized participants has been reached, enrollment will stop in the regimen. Number of Planned Participants and Treatment Groups The number of planned participants for this regimen is 160. There are 2 treatment groups for this regimen, active and placebo. Participants will be randomized in a 3:1 ratio to active treatment or placebo (i.e., 120 active: 40 placebo). Planned Number of Sites Research participants will be enrolled from approximately 60 centers across the US. Treatment Duration The maximum duration of the placebo-controlled treatment period is 24 weeks. Follow-up Duration At the conclusion of the 24-week placebo-controlled treatment period of the study, all participants will either schedule a 28-day follow up phone call and end their participation in the regimen or have the option to receive pridopidine in the Open Label Extension (OLE) period of the study. The duration of the OLE period is planned for 24 weeks. Total Planned Trial Duration For participants completing the placebo-controlled treatment period of the study, the planned amount of time for a participant in the trial is up to 34 weeks, or about 8 months. This duration assumes a 6-week screening window, a 24-week placebo-controlled treatment period, and a 4-week safety follow-up period for those participants who do not enter the OLE period of the study. Participants will complete approximately 10 study visits during the placebo-controlled period of the study.