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A6312 - Transition to Oral Treprostinil from Parenteral or Inhaled Treprostinil or as Add-On Therapy in Pediatric Subjects with Pulmonary Arterial Hypertension
Author Block: D. Ivy1, J. Feinstein2, D. Yung3, M. Mullen4, E. Kirkpatrick5, R. Hirsch6, E. D. Austin7, J. Fineman8, A. Doran9, D. Solum10, C. Deng11, R. K. Hopper12; 1Pediatric Cardiology, Univ of Colorado, Aurora, CO, United States, 2Ped Cardiology, Stanford Univ, Palo Alto, CA, United States, 3Pediatric Cardiology, Seattle Childrens Hospital, Seattle, WA, United States, 4Pediatric Cardiology, Boston Childrens Hospital, Boston, MA, United States, 5Pediatric Cardiology, Childrens Hospital Wisconsin, Milwaukee, WI, United States, 6Pediatric Cardiology, Cincinnati Childrens Hospital, Cincinnati, OH, United States, 7Vanderbilt Univ, Nashville, TN, United States, 8University of California, San Francisco, CA, United States, 9United Therapeutics, Santa Barbara, CA, United States, 10United Therapeutics, Chapel Hill, NC, United States, 11United Therapeutics, Durham, NC, United States, 12Childrens Hospital of Philadelphia, Philadelphia, PA, United States.
Rationale: Transition from parenteral to oral treprostinil has been successfully accomplished in adults with pulmonary artery hypertension (PAH) but data in pediatric patients are lacking. Methods: In Study TDE-PH-206, pediatric subjects treated with parenteral (Cohort 1) or inhaled (Cohort 2) treprostinil were transitioned to oral treprostinil. Prostacyclin-naive subjects on background oral PAH therapy were given oral treprostinil as add-on therapy (Cohort 3). Successful transition was defined as cessation of parenteral or inhaled prostacyclin at Week 4 (Cohorts 1 and 2) and oral treprostinil dose maintenance through Week 24 (Cohorts 1, 2, and 3). Subjects were monitored for adverse events (AEs), 6-Minute Walk Distance (6MWD), PAH symptoms, WHO Functional Class (FC), cardiac magnetic resonance imaging (cMRI), and cardiopulmonary exercise testing (CPET) through 24 weeks. Results: A total of 32 subjects (10 subjects each, Cohorts 1 and 2; 12 subjects Cohort 3) were enrolled. The mean age was 12.2 years (7 to 17 years) and 23 subjects (72%) were female. Most subjects had idiopathic PAH (75.0%) or PAH due to congenital heart disease (15.6%). All subjects were on background oral PAH therapy and 19%, 75%, and 6% were classified as WHO FC 1, 2, and 3, respectively. Cohort 1 subjects were receiving parenteral treprostinil at a median dose of 57.0 ng/kg/min (25.0‑72.0 ng/kg/min) for 5.4 years (2.0-6.1 years). Cohort 2 subjects were receiving 4 inhaled treprostinil treatments per day (average 9 breaths per session) for 3.9 years (0.5-5.3 years). In total, 31 subjects (96.9%) successfully transitioned to oral treprostinil; 1 subject (Cohort 1) transitioned to oral treprostinil, then back to parenteral after experiencing syncope and WHO FC change from 2 to 3. Cohorts 1, 2, and 3 received a final mean oral treprostinil dose of 5.6, 3.3, and 4.5 mg TID, respectively, which is substantially higher by weight compared with doses achieved in adult studies. 1 subject (Cohort 3) was uptitrated from TID to QID dosing based upon clinical impression. All cohorts had variable changes in 6MWD, cMRI, and CPET. 1 subject (Cohort 3) required background therapy adjustment. Overall, 12 serious AEs were reported. Common drug-related AEs included headache (81%), diarrhea (69%), nausea (66%), vomiting (66%), and flushing (56%). Conclusions: Most pediatric subjects successfully transitioned to oral treprostinil with preservation of exercise capacity and WHO FC. Prostanoid-related AEs were most common, and were similar to those reported in adults. Funded by United Therapeutics Corporation