Study of REGN13335 in Adult Participants With Pulmonary Arterial Hypertension (PAH) (ILLUMINATE)

A Phase 2, Randomized, Double-Blind, Placebo-Controlled Study to Assess the Efficacy, Safety, Pharmacokinetics, and Pharmacodynamic Effects of REGN13335, an Anti-PDGF-B Monoclonal Antibody, in Adults With Pulmonary Arterial Hypertension

This study is researching an experimental drug called REGN13335. The study is focused on participants with Pulmonary Arterial Hypertension (PAH). The aim of the study is to see how safe and effective REGN13335 is in participants with PAH who are taking other PAH medicines.

The study is looking at several other research questions, including:

• What side effects may happen from taking REGN13335
• How much REGN13335 is in the blood at different times
• Whether the body makes antibodies against REGN13335 (which could make REGN13335 less effective or could lead to side effects)

Study Overview

• Status: Recruiting
• Conditions: Pulmonary Arterial Hypertension (PAH)
• Intervention / Treatment: Drug: Placebo; Drug: REGN13335

• Study Type: Interventional
• Enrollment (Estimated): 99
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Clinical Trials Administrator; Phone Number: 844-734-6643; Email: clinicaltrials@regeneron.com

Study Locations

• Latvia
  • Riga, Latvia, LV1002
    • Recruiting
    • P. Stradins Clinical University hospital
• South Korea
  • Seoul, South Korea, 03080
    • Recruiting
    • Seoul National University Hospital
  • Incheon
    • Namdong-gu, Incheon, South Korea, 21565
      • Recruiting
      • Gachon University Gil Medical Center
  • Songpa-gu
    • Seoul, Songpa-gu, South Korea, 05505
      • Recruiting
      • Asan Medical Center
• United Kingdom
  • London, United Kingdom, W12 0HS
    • Recruiting
    • Imperial College Healthcare NHS Trust, Hammersmith Hospital
• United States
  • Colorado
    • Aurora, Colorado, United States, 80045
      • Recruiting
      • University of Colorado Denver

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Key Inclusion Criteria:

1. Documented clinical diagnosis of PAH (Group 1 PH according to the 7th World Symposium on Pulmonary Hypertension (WSPH))
2. WHO functional class II or III (slight to marked limitation of functional status due to PAH)
3. Receiving background Standard Of Care (SOC) therapy for PAH on a stable dose and regimen, as determined by the investigator, as described in the protocol
4. PVR ≥400 dynes∙sec/cm^5 (5 Wood units) based on Right Heart Catheterization (RHC) during the screening period
5. Has 6MWD ≥150 and ≤550 meters repeated twice during screening as described in the protocol

Key Exclusion Criteria:

1. Has Group 2 (PH associated with left heart disease), Group 3 (PH associated with lung diseases and/or hypoxia), Group 4 (PH associated with pulmonary artery obstructions), or Group 5 (PH with unclear and/or multifactorial mechanisms) PH according to the 7th WSPH
2. Pulmonary Arterial Wedge Pressure (PAWP) >15 mm Hg by RHC during the screening period
3. History of left-sided heart disease and/or clinically significant cardiac disease, as described in the protocol
4. Obstructive lung disease defined as Forced Expiratory Volume in 1 second (FEV1)/Forced Vital Capacity <0.7 and FEV1 <70% of the predicted value as described in the protocol
5. Evidence of interstitial lung disease as defined in the protocol
6. Evidence of chronic thromboembolic pulmonary disease or acute pulmonary embolism as described in the protocol
7. Participants requiring anticoagulation and/or antiplatelet therapy for an underlying medical condition as described in the protocol
8. Has any history of intracranial bleeding or any history of elevated intracranial pressure
9. Has any history of bleeding meeting criteria as described in the protocol

Note: Other protocol-defined Inclusion/ Exclusion criteria apply

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

5

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: DBTP-Arm1	Drug: REGN13335; Administered per the protocol
Experimental: DBTP-Arm2	Drug: REGN13335; Administered per the protocol
Placebo Comparator: DBTP-Arm3	Drug: Placebo; Administered per the protocol
Experimental: OLE-Arm1	Drug: REGN13335; Administered per the protocol
Experimental: OLE-Arm2	Drug: REGN13335; Administered per the protocol

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Change from baseline in Pulmonary Vascular Resistance (PVR)	At week 24

Secondary Outcome Measures

Outcome Measure	Time Frame
Occurrence of Treatment-Emergent Adverse Events (TEAEs)	Through end of study, up to approximately 2.5 years
Severity of TEAEs	Through end of study, up to approximately 2.5 years
Change from baseline in circulating N-Terminal pro-B-type Natriuretic Peptide (NT-proBNP) concentrations	At week 24
Change from baseline in mean pulmonary artery pressure	At week 24
Change from baseline in cardiac output	At week 24
Change from baseline in cardiac index	At week 24
Change from baseline in right atrial pressure	At week 24
Change from baseline in 6-Minute Walk Distance (6MWD)	At week 24
Concentrations of functional REGN13335 in plasma	Through end of study, up to approximately 2.5 years
Concentrations of total soluble Platelet-Derived Growth Factor-B (PDGF-B) ligands in plasma	Through end of study, up to approximately 2.5 years

Collaborators and Investigators

• Sponsor: Regeneron Pharmaceuticals
• Investigators: Study Director: Clinical Trial Management, Regeneron Pharmaceuticals

Publications and helpful links

Helpful Links

• Illuminate

Study record dates

Study Major Dates

• Study Start (Actual): May 6, 2026
• Primary Completion (Estimated): February 27, 2028
• Study Completion (Estimated): September 17, 2028

Study Registration Dates

• First Submitted: January 2, 2026
• First Submitted That Met QC Criteria: January 2, 2026
• First Posted (Actual): January 6, 2026

Study Record Updates

• Last Update Posted (Actual): May 29, 2026
• Last Update Submitted That Met QC Criteria: May 26, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Pulmonary Arterial Hypertension (PAH); Pulmonary Hypertension (PH); Elevated Pulmonary Vascular Resistance (PVR); World Health Organization (WHO) functional class II or III; Platelet-Derived Growth Factor-B (PDGF-B); REGN13335
• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Respiratory Tract Diseases; Lung Diseases; Hypertension; Pulmonary Arterial Hypertension; Hypertension, Pulmonary
• Other Study ID Numbers: R13335-PAH-2365; 2024-514754-79-00 (Ctis)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing.

IPD Sharing Time Frame

When Regeneron has:

• received marketing authorization from major health authorities (e.g., FDA, European Medicines Agency (EMA), Pharmaceuticals and Medical Devices Agency (PMDA), etc.) for the product and indication or has globally discontinued development of the product for all indications on or after April 2020 and has no plans for future development
• made the study results publicly available (e.g., scientific publication, scientific conference, clinical trial registry)
• the legal authority to share the data, and
• ensured the ability to protect participant privacy

• IPD Sharing Access Criteria: Qualified researchers can submit a proposal for access to individual patient or aggregate level data from a Regeneron-sponsored clinical trial through Vivli. Regeneron's Independent Research Request Evaluation Criteria can be found at: https://www.regeneron.com/sites/default/files/Regeneron-External-Data-Sharing-Policy-and-Independent-Research-Request-Evaluation-Criteria.pdf
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No