An Open-Label Extension Trial of UT-15C SR in Subjects With Pulmonary Arterial Hypertension (FREEDOM-EXT)

Primary Outcome Measures:

• Continued therapy effect on exercise capacity as assessed by a 6-Minute Walk Test [ Time Frame: Once, after one year of therapy with UT-15C SR. ]
  
• Long-term safety as assessed by clinical laboratories [ Time Frame: Performed at each study scheduled visit ]
  After one year exposure to UT-15C clinical laboratorial assessments will occur 1 time/year through study completion until either drug receives regulatory approval in a particular region or the sponsor discontinues the study.
  
  
• Long-term safety as assessed by adverse events [ Time Frame: Performed monthly during monthly telephone calls ]
  Telephone calls will occur at a minimum 1 time/month through study completion until either drug receives regulatory approval in a particular region or the sponsor discontinues the study.
  
  

This is an open-label study. Each subject's visit schedule will allow assessments after defined periods of exposure to UT-15C SR (3, 6, 12, 24 and 36 months total exposure). The study will continue with yearly visits beyond 36 months until either UT-15C SR is approved by the appropriate regulatory authorities or the study is discontinued by the sponsor. Therefore, the actual date of each visit will be determined by the date on which the subject first received UT-15C SR (e.g., the date of study drug initiation in TDE-PH- 301, TDE-PH-302, or TDE-PH-308 for subjects who were randomized to active therapy in those trials,and the date of UT-15C SR initiation in this study for subjects who were randomized to placebo in the previous controlled trial). Note that the TDE-PH-202, TDE-PH-203, TDE-PH-205 studies are open-label design and therefore will follow the regimen for subjects receiving UT-15C SR.