The primary objective for this trial is to determine the effect of GB002 (seralutinib) on improving pulmonary hemodynamics in subjects with World Health Organization (WHO) Group 1 PAH who are Functional Class (FC) II and III. The secondary objective for this trial is to determine the effect of GB002 (seralutinib) on improving exercise capacity in this population.



Eligible Ages
Between 18 Years and 75 Years
Eligible Genders
Accepts Healthy Volunteers

Inclusion Criteria

  1. A current diagnosis of symptomatic PAH classified by one of the following: 1. Idiopathic PAH (IPAH) or heritable pulmonary arterial hypertension (HPAH). 2. PAH associated with connective tissue diseases. 3. PAH associated with anorexigen or methamphetamine use. 4. Congenital heart disease with simple systemic to pulmonary shunt at least 1 year after surgical repair. 2. 6MWD ≥ 150 meters and ≤ 550 meters at screening. 3. WHO FC II or III symptomatology. 4. Treatment with standard of care PAH background therapies. 5. Documentation of cardiac catheterization within the screening period that is consistent with the diagnosis of PAH and meeting all the following criteria, to be confirmed by a central hemodynamic core laboratory: 1. Mean pulmonary arterial pressure (mPAP) ≥ 25 mmHg (at rest), AND 2. PVR ≥ 400 dyne•sec/cm5, AND 3. Pulmonary capillary wedge pressure (PCWP) or left ventricular-end diastolic pressure (LVEDP) ≤12 mm Hg if PVR ≥400 to <500 dyne∙sec/cm5 OR 4. PCWP or LVEDP ≤15 mmHg if PVR ≥500 dyne∙sec/cm5 6. Pulmonary function tests (PFTs) and diffusing capacity of the lungs for carbon monoxide (DLCO) at screening with the following criteria met: 1. Forced expiratory volume in 1 second (FEV1) ≥60% (predicted); 2. DLCO ≥40% predicted except for subject with PAH associated with systemic sclerosis (SSc-APAH) where DLCO ≥30% is required.

Exclusion Criteria

  1. Evidence of chronic thromboembolic disease or acute pulmonary embolism as assessed by ventilation-perfusion (V/Q) scan, computed tomography (CT)-angiogram, or pulmonary angiogram prior to screening. 2. Uncontrolled systemic hypertension as evidenced by sitting systolic blood pressure > 160 mm Hg or sitting diastolic blood pressure > 100 mm Hg during screening visit after a period of rest. 3. Systolic blood pressure < 90 mm Hg during screening and baseline visits. 4. WHO Pulmonary Hypertension Group 2-5. 5. Human immunodeficiency virus (HIV)-associated PAH. 6. History of left-sided heart disease and/or clinically significant cardiac disease. 7. Untreated severe obstructive sleep apnea. 8. History of atrial septostomy within 180 days prior to screening. 9. Pulmonary venous occlusive disease (PVOD). 10. Subjects with a history of portopulmonary hypertension or portal hypertension classified as Child-Pugh Class A or higher; or baseline ALT or AST > 2 x ULN or Total Bilirubin ≥ 2 x ULN. 11. History of malignancy within 5 years prior to screening. 12. History of a potentially life-threatening cardiac arrhythmia with an ongoing risk. 13. Severe acute or chronic medical or laboratory abnormality that may increase the risk associated with study participation or IP administration (eg; history intracranial hemorrhage). 14. Chronic renal insufficiency as defined by an estimated glomerular filtration rate (eGFR) < 45 mL/min/1.73m2 via Chronic Kidney Disease Epidemiology Collaboration (CKD-epi) at screening or requires dialytic therapy or hemofiltration. 15. Hemoglobin (Hgb) concentration < 8.5 g/dL at screening. 16. Evidence of active HIV, Hepatitis B or Hepatitis C, or tuberculosis (TB) infections. 17. Inhaled prostanoids; these drugs may be withdrawn ≥ 4 weeks prior to or at screening, if clinically indicated. 18. Use of oral anticoagulants (ie, coumadin or NOAC) at randomization. 19. Requirement of intravenous (IV) inotropes (ie, levosimendan, dopamine, dobutamine, milrinone, norepinephrine) other than an IV prostanoid within 4 weeks of screening. 20. Prior participation in GB002 studies and/or prior treatment with GB002. 21. Currently participating in or has participated in a study of an investigational agent or has used an investigational device for the treatment of PAH within 4 weeks prior to screening. 22. Current use of inhaled tobacco and/or inhaled marijuana. 23. Documented history of alcohol abuse and/or positive test for drugs of abuse (amphetamines, methamphetamines, cocaine, phencyclidine [PCP]). 24. Subjects with a history of severe milk protein allergy. In addition, subjects with known intolerance or hypersensitivity to lactose who, in the opinion of the investigator, may experience severe symptoms following the ingestion of lactose. 25. QTcF of > 480 msec recorded on a screening or baseline ECG or receiving concurrent treatment with medications that prolong QT interval. 26. Have any other condition or reason that, in the opinion of the Investigator or Medical Monitor, would prohibit the subject from participating in the study. NOTE: Additional inclusion/exclusion criteria may apply, per protocol.

Study Design

Phase 2
Study Type
Intervention Model
Parallel Assignment
Primary Purpose
Double (Participant, Investigator)
Masking Description
Subjects, investigators, other site personnel, and Sponsor (and/or designee) personnel who are directly involved in the conduct of the study, collection of the data, and analysis of the final safety and efficacy results will remain blinded to treatment assignments until after the completion of the study and the database has been locked.

Arm Groups

ArmDescriptionAssigned Intervention
GB002 (seralutinib)
GB002 (seralutinib) inhaled orally twice per day (BID) over 24 weeks
  • Drug: GB002 (seralutinib)
    Capsule containing GB002 (seralutinib)
  • Device: Generic Dry Powder Inhaler
    Generic dry powder inhaler for GB002 (seralutinib) or placebo delivery
Placebo Comparator
Placebo inhaled orally BID over 24 weeks
  • Drug: Placebo
    Matching capsule containing placebo
  • Device: Generic Dry Powder Inhaler
    Generic dry powder inhaler for GB002 (seralutinib) or placebo delivery

Recruiting Locations

University of Kansas Medical Center
Kansas City, Kansas 66160

More Details

GB002, Inc., a wholly owned subsidiary of Gossamer Bio, Inc.

Study Contact

GB002, Inc.


Study information shown on this site is derived from ClinicalTrials.gov (a public registry operated by the National Institutes of Health). The listing of studies provided is not certain to be all studies for which you might be eligible. Furthermore, study eligibility requirements can be difficult to understand and may change over time, so it is wise to speak with your medical care provider and individual research study teams when making decisions related to participation.