This phase 2 clinical trial will be conducted over 16 weeks and involves a Screening period (4 weeks) and a Treatment period (12 weeks). The final follow up visit will occur 2 weeks after the end of the Treatment period. Primary and Secondary endpoints will be evaluated according to treatment group, clinic visit period, and the overall Treatment period. Safety analyses will be conducted at each clinic visit, and include: cardiac rhythm monitoring, ECG testing, laboratory evaluation, and symptom and adverse event assessment.