Inclusion Criteria:

- Adult participants ≥ 18 years of age

- Symptomatic World Health Organization (WHO) Group 1 Pulmonary Hypertension (PH)(PAH)
classified by one of the following subgroups:

- Idiopathic pulmonary arterial hypertension (IPAH);

- Heritable pulmonary arterial hypertension (HPAH);

- Associated with drugs and toxins;

- PAH associated with:

- Connective tissue disease

- Congenital systemic-pulmonary intracardiac shunt

- Has the following hemodynamic parameters that are consistent with the diagnosis of
PAH:

- Mean pulmonary arterial pressure (mPAP) > 20 mmHg at rest, AND

- Pulmonary artery wedge pressure (PAWP) ≤ 15 mmHg, AND

- PVR ≥ 5 Wood Units (400 dyn·sec·cm-5)

- Has WHO/New York Heart Association (NYHA) Functional Class (FC) II or III symptoms as
assessed by the Investigator

- Must be on a stable PAH background therapy with either an endothelin-receptor
antagonist (ERA) and/or a phosphodiesterase-5 inhibitor (PDE5-I) or soluble guanylate
cyclase (sGC) stimulator and/or prostacyclin analogue or receptor agonist
(oral/inhaled/SC/intravenous)

- 6MWD ≥ 150 and ≤ 500 meters at screening

- Provide written (signed and dated) informed consent form before the initiation of any
Screening tests or procedures

Exclusion Criteria:

- Evidence or history of left ventricular dysfunction and/or clinically significant
cardiac disease

- Has pulmonary function tests (PFTs) with evidence of significant obstructive or
parenchymal lung disease

- Evidence of thromboembolic disease assessed by ventilation perfusion (V/Q) lung scan
or other local standard of care diagnostic evaluation at the time of PAH diagnosis or
after

- Has uncontrolled systemic hypertension

- Hemoglobin < 9 g/dL at Screening

- Prior heart or heart-lung transplants, active on the lung transplant list, or life
expectancy of < 12 months per Investigator assessment

- Diagnosis of pulmonary veno-occlusive disease or pulmonary capillary hemangiomatosis

- Initiation or discontinuation of an exercise program for cardiopulmonary
rehabilitation within 90 days prior to Baseline or planned initiation during the study

- Prior participation in a KER-012 study or prior treatment with a therapy targeting
TGF-? superfamily (e.g. sotatercept)

- Prior participation in another interventional clinical study with medicinal products
within 30 days or 5 half-lives prior to Screening, whichever is longer

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 8/28/23. Questions regarding updates should be directed to the study team contact.