GB002 in Adult Subjects With Pulmonary Arterial Hypertension

This is a double-blind, placebo-controlled, randomized Phase 2 study. This study will evaluate the oral inhalation of GB002 in adult subjects with WHO Group 1 PAH who are WHO FC II and III and have a PVR of ≥ 400 dyne•s/cm5. After signing an informed consent form (ICF), subjects will be screened for study eligibility for up to a 5-week screening period. Subjects must continue on stable doses of background PAH medications from 4 weeks before consent and throughout the treatment period. Dose modification of background PAH medications will not be allowed during the screening period. On Day 1 (Baseline visit), eligible subjects will be randomized 1:1 to 1 of 2 treatment groups to receive GB002 twice per day (BID) or placebo. Initially subjects will receive 60 mg BID (4 inhalations BID) for 1 week, after which, subjects will increase the dose to 90 mg BID (6 inhalations BID). Investigational product (IP) dose may be reduced due to tolerability or AEs. Randomization will be stratified by PVR. Subjects will receive IP, BID, over 24 weeks inhaled orally with a dry powder inhaler (DPI). Following initiation of IP in the clinic on Day 1, subjects will return to the clinic every 4 weeks through Week 28 (24 weeks of treatment + 4 weeks of follow-up). Subjects will also be contacted by phone at Week 1 and attend a Week 28 Follow-up visit at the clinic.

Inclusion Criteria

• 6MWD ≥ 150 meters and ≤ 550 meters at screening. The lower of 2 consecutive distances should be within 15% of the higher distance.
• WHO FC II or III symptomatology.
• Treatment with standard of care PAH background therapies. Medications should remain stable for the past 4 weeks prior to consent and throughout the screening period.

Exclusion Criteria

• Systolic blood pressure < 90 mm Hg during screening and baseline visits.
• WHO Pulmonary Hypertension Group 2–5.
• HIV- associated PAH.

Study Requirements

Subjects will be in the trial for 28 weeks and have 7 clinic visits. Subjects will initially receive GB002 60 mg BID or placebo (4 inhalations BID) for 1 week, after which, subjects will increase the dose to 90 mg BID (6 inhalations BID). IP dose may be reduced due to tolerability or AEs. Following initiation of IP in the clinic on Day 1, subjects will return to the clinic every 4 weeks through Week 28 (24 weeks of treatment + 4 weeks of follow-up). Subjects will also be contacted by phone at Week 1 and attend a Week 28 Follow-up visit at the clinic. Except for Week 3, blood will be collected at each visit for clinical laboratory testing. A Right heart catheterization will be performed at screening and End of Treatment and an echocardiogram will be performed at screening, Visit 6 and End of Treatment. A V/Q lung scan or CT-angiogram will be performed only at screening.