Respira Therapeutics has announced plans to present results from its recently completed Phase 2b CPET trial of RT234 (vardenafil inhalation powder) in patients with pulmonary arterial hypertension (PAH) at the upcoming American Thoracic Society (ATS) 2025 International Conference in San Francisco.
The clinical trial data will be featured in a late-breaking session on Tuesday, May 20, 2025, with Dr. Raymond L. Benza presenting the findings. The presentation, titled "A Single Dose of RT234, Vardenafil Inhaled via the Axial Oscillating Sphere Dry Powder Inhaler (AOS™ DPI), Acutely Improves Exercise Capacity and Reduces Dyspnea in Pulmonary Arterial Hypertension (PAH) Patients (WHO Group 1 PH)," will highlight results from the open-label Phase 2b CPET (Cardiopulmonary Exercise Testing) study.
Novel Approach to PAH Management
RT234 represents a potentially significant advancement in PAH treatment as it is being developed as the first therapy that patients can use on an as-needed (pro re nata or PRN) basis. This approach differs substantially from current PAH therapies, which typically require continuous administration.
PAH is a progressive, life-threatening condition characterized by high blood pressure in the arteries of the lungs, leading to right heart failure if left untreated. The disease significantly impacts patients' ability to perform physical activities due to symptoms such as shortness of breath, fatigue, and chest pain during exertion.
Current treatment options for PAH include prostacyclin analogs, endothelin receptor antagonists, phosphodiesterase-5 inhibitors, and soluble guanylate cyclase stimulators. However, these medications are generally prescribed for continuous use and may not adequately address acute exertional symptoms that many patients experience.
Innovative Drug Delivery System
A key component of RT234's potential efficacy is Respira's proprietary drug delivery technology. The treatment utilizes the company's Axial Oscillating Sphere Dry Powder Inhaler (AOS™-DPI), which is designed to maximize drug delivery to the distal lung where it can most effectively target the pulmonary vasculature.
Vardenafil, the active pharmaceutical ingredient in RT234, is a phosphodiesterase type 5 (PDE5) inhibitor. While oral PDE5 inhibitors are already used in PAH treatment, the inhaled delivery method may offer advantages in terms of rapid onset of action and targeted delivery to the pulmonary circulation.
Clinical Trial Details
The Phase 2b CPET study (NCT04266197) was designed to evaluate the acute effects of a single dose of RT234 on exercise capacity and dyspnea (shortness of breath) in patients with WHO Group 1 pulmonary arterial hypertension. The open-label trial utilized cardiopulmonary exercise testing to measure changes in exercise parameters following administration of the investigational therapy.
While full results will be presented at the ATS conference, the announcement suggests positive outcomes regarding exercise capacity and symptom reduction. If confirmed, these findings could support further development of RT234 as a novel approach to managing activity-limiting symptoms in PAH patients.
Potential Impact on Patient Quality of Life
"The development of an as-needed therapy for PAH represents an important potential advance in how we manage this challenging condition," said John Kollins, Chief Executive Officer of Respira Therapeutics. "Many PAH patients experience significant limitations in their daily activities due to exertional symptoms. A treatment that could be used specifically when needed for physical activities could substantially improve quality of life."
The ability to acutely improve exercise tolerance on demand could potentially allow PAH patients greater participation in activities of daily living, social engagements, and physical exercise, which are often severely limited by their condition.
The detailed results from the Phase 2b trial will be presented during Session C93: "Advances in Interstitial Lung Disease and Pulmonary Hypertension: Uncovering Novel Mechanisms, Targeted Therapies, and Personalized Approaches" at the Moscone Center in San Francisco.
