PB1046-PT-CL-0005 is an open-label, dose-titration study to assess the safety, tolerability, and hemodynamic effects of individually dose-titrated PB1046 administered by weekly subcutaneous injection for 8 weeks in adult subjects with PAH who have a permanently implanted hemodynamic monitor in the distal pulmonary artery. The primary objectives of the study are to assess the overall safety, tolerability, and hemodynamic profile of a PB1046 across an individually titrated dose range.