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A study to evaluate the effectiveness and safety of REGN13335 in adults with pulmonary arterial hypertension

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study focuses on individuals living with Pulmonary Arterial Hypertension, a condition where the blood pressure in the arteries of the lungs is too high. This high pressure makes it difficult for the heart to pump blood through the lungs. The purpose of the study is to evaluate the effectiveness and safety of a new medication called REGN13335.

REGN13335 is a monoclonal antibody, which is a type of laboratory-made protein designed to target specific parts of the body. In this case, the drug targets Platelet-Derived Growth Factor Subunit B, also known as PDGF-B, a substance that can contribute to the thickening of the blood vessel walls in the lungs. During the study, participants will receive either REGN13335 or a placebo through an injection or infusion.

The study will monitor several health factors, such as pulmonary vascular resistance, which is the amount of force the blood must overcome to flow through the lung vessels. Other areas of focus include cardiac output, which is the amount of blood the heart pumps each minute, and the distance a person can walk in six minutes. The course of the study involves regular assessments to track how the body responds to the treatment and to monitor for any side effects.

The research process

The trial runs in 2 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Study participation and medication administration

    Participation involves receiving either the test medication, known as REGN13335, or a placebo, which is an inactive substance used for comparison.

    The REGN13335 is a monoclonal antibody, which is a type of medicine designed to target a specific protein in the body called platelet-derived growth factor subunit b.

    The medication is administered through injection or infusion, which means it is delivered into the body via the vein, under the skin, or into a muscle.

    The specific dosage and frequency of the administration are determined by the study protocol.

  2. Step 2

    Monitoring and evaluation

    The effectiveness of the treatment is measured by changes in pulmonary vascular resistance, which is the resistance to blood flow in the lungs.

    Various health measurements are recorded, including mean pulmonary artery pressure, cardiac output (the amount of blood the heart pumps), cardiac index, and right atrial pressure.

    Blood tests are performed to check levels of NT-proBNP, a substance in the blood that can indicate how the heart is functioning, as well as the concentration of REGN13335 in the blood.

    Physical performance is assessed through a 6-minute walk distance test to see how far walking can be achieved in six minutes.

    The safety of the medication is monitored by tracking any adverse events, which are unexpected medical occurrences or side effects that happen during the study.

Who can join the trial?

7 criteria

  • You must have a confirmed diagnosis of Pulmonary Arterial Hypertension (PAH), which is a type of high blood pressure that affects the arteries in your lungs.
  • Your condition must be classified as WHO functional class II or III, meaning you experience a mild to significant limitation in your ability to perform daily activities or physical tasks.
  • You must be currently taking Standard of Care (SOC) therapy, which refers to the usual medical treatments used to manage your condition, and this treatment must be at a steady dose.
  • A procedure called Right Heart Catheterization (RHC), which involves placing a thin tube into the heart to measure pressures, must show that your pulmonary vascular resistance (PVR) is 400 dynes∙sec/cm^5 or higher. This measurement shows how much resistance or difficulty there is for blood to flow through the lung vessels.
  • You must be able to walk at least 150 meters but no more than 550 meters during a 6-minute walk test (6MWD), which is a test used to measure how well you can walk over a short period of time. This test must be performed twice.
  • You can be either male or female.
  • You must fall within the specific age range defined by the study protocols.

Who cannot join the trial?

9 criteria

  • You have high blood pressure in the lungs caused by other factors, such as left-sided heart disease (heart problems affecting the left side), lung diseases or low oxygen levels, blockages in the lung arteries, or causes that are unclear or involve multiple factors.
  • Your pulmonary arterial wedge pressure (a measurement of the pressure in the blood vessels of your lungs) is higher than 15 mm Hg when measured through a procedure called a right heart catheterization (a procedure where a thin tube is inserted into the heart to check pressures).
  • You have a history of left-sided heart disease or other significant heart problems.
  • You have obstructive lung disease, which is a condition where it is difficult to exhale air from the lungs, measured by specific lung function tests.
  • There is evidence of interstitial lung disease, which is a type of lung disease that causes scarring or inflammation of the lung tissue.
  • There is evidence of chronic thromboembolic pulmonary disease (long-term blood clots in the lungs) or an acute pulmonary embolism (a sudden blood clot in the lung).
  • You need to take anticoagulation therapy (blood-thinning medicine) or antiplatelet therapy (medicine that prevents blood cells from sticking together) for another medical condition.
  • You have a history of intracranial bleeding (bleeding inside the skull) or elevated intracranial pressure (increased pressure inside the skull).
  • You have a history of bleeding that meets specific medical criteria defined in the study rules.
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Investigated drugs

REGN13335 is an experimental medicine used to study its effects on people with pulmonary arterial hypertension. It is a type of antibody designed to target and block a specific protein in the body called platelet-derived growth factor subunit B, which may help in managing the condition.

What is already known about the treatment

REGN13335 - This medication is an experimental protein-based therapy administered as a powder that is dissolved and then given via injection into a vein, under the skin, or into a muscle. Currently being studied in clinical trials, it is being investigated as a potential treatment for pulmonary arterial hypertension, a condition where blood pressure in the lungs is too high. The drug works by specifically targeting and blocking a protein called platelet-derived growth factor subunit B, which helps prevent the abnormal thickening of blood vessel walls. It is classified as a monoclonal antibody, a type of targeted therapy designed to seek out and neutralize specific molecules in the body.

Investigated diseases

Pulmonary Arterial Hypertension - This condition occurs when the blood vessels in the lungs become narrow, thickened, or blocked. This narrowing makes it harder for blood to flow through the pulmonary arteries. As the disease progresses, the blood pressure within these specific arteries increases. The heart must work harder to pump blood through the lungs. Over time, this extra effort can lead to changes in the structure of the heart and the vessels.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IITrial ID2024-514754-79-00Protocol codeR13335-PAH-2365Estimated enrolment99 patientsSponsorRegeneron Pharmaceuticals Inc.

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