The total amount of time of the FUSION study is approximately three years (152 weeks) and is being conducted in two parts. The first part is placebo controlled and consists of 8 clinic visits once every 4 weeks, for a total of 7 months. One month after the last visit, a follow up assessment takes place. After the assessment, participants have the option to enroll in the second part of the FUSION study. Those who do not enroll in Part 2 will be in a follow-up period for a total of 40 weeks. In Part 2 of the FUSION study, all participants receive the investigation antisense drug for an additional 18 months. Participants are assigned to two different groups with one group, dosing every 4 weeks; the second group, dosing every 4 weeks for the first 3 months, then dosing every 8 weeks for the remainder of the treatment period. After the 18-month dosing period is completed, there is a 10 month follow-up period.