Dose Titration Study to Test Safety and Effects of CK-2017357 in Patients With Amyotrophic Lateral Sclerosis (ALS)

Patients will be randomized to one of two dosing groups, active CK-2017357 or placebo, in a 3:1 ratio. Prior to study drug dosing, patients will be required to decrease their riluzole dose to 50 mg QD for 7 days; after this 7 day period patients will either receive placebo or start the titration on active CK-2017357 while continuing to take riluzole at 50 mg QD. Potential patients will be screened to assess their eligibility to enter the study within 21 days prior to Day -7, when they will begin taking riluzole at the decreased dose of 50 mg QD. Patients will be randomized in a 3:1 ratio to CK-2017357 (Group 1) or placebo (Group 2). On Day 1, patients will begin taking a total daily dose of 250 mg (125 mg BID) of CK-2017357 or matching placebo tablets BID for 7 days. Then they will take a total daily dose of 375 mg (125 mg morning \[AM\] and 250 mg evening \[PM\]) of CK-2017357 or matching placebo tablets BID for 7 days, and finally, they will take a total daily dose of 500 mg (250 mg BID) of CK-2017357 or matching placebo tablets BID for 7 days. A final dose of 250 mg of CK-2017357 or placebo will be taken in the morning on Day 22 at the study site. Dose-escalation of CK-2017357 or placebo may be stopped, or the dose reduced to a lower level, based on tolerability. All patients who return to a lower dose will stay on that dose for the remainder of the study. Patients will remain on the decreased dose of riluzole until the follow-up visit approximately 7 days after Day 22.