Dosing Begins in Phase 2b Study of Inhaled Therapy RT234 for PAH

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by Patricia Inácio, PhD |

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Adempas | Pulmonary Hypertension News | Phase 3 Clinical Trial | illustration of medicine bottle labeled clinical trials

A first patient in the U.S. has been dosed in a Phase 2b trial testing Respira Therapeutics‘ inhaled medicine-device combination product, called RT234, as a therapy for pulmonary arterial hypertension (PAH).

The trial (NCT04266197), dubbed VIPAH-PRN, for Vardenafil Inhaled for Pulmonary Arterial Hypertension – PRN, will test RT234 at three clinical sites in the U.S. and two in Serbia.

This is the first study to assess the safety and effectiveness of RT234 on exercise capacity in people with PAH.

It aims to enroll 40 PAH patients, ages 18 to 80, who are on an oral and/or inhaled stable treatment. Participants should have a World Health Organization Group 1 diagnosis. Additional eligibility criteria are available on the trial’s webpage.

Recruitment is open, and details and contacts of trial locations can be found here. In the U.S., the trial will take place at the University of California San Francisco, the University of Kansas Medical Center, and The Ohio State University.

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More information can be obtained by contacting Carol Ann Satler, MD, PhD, president and chief medical officer at Respira, by email at [email protected] or by phone at 646-244-4901.

“The initiation of this clinical trial represents an important milestone for Respira and is a critical next step in potentially offering patients with PAH an acute treatment to manage their shortness of breath, which prevents them from performing normal daily duties,” Satler said in a press release.

PAH is caused by a narrowing of the pulmonary arteries, leading to symptoms such as shortness of breath, fatigue, dizziness, and fainting. People with PAH have limited exercise capacity, as well as severe shortness of breath while doing exercise, despite maintenance therapies.

RT234 is an inhaled therapy specifically designed to provide symptom relief in people with PAH. It is thought to help improve exercise tolerance and ease PAH patients’ breathlessness and fatigue.

The therapeutic combination being tested combines the potent vasodilator vardenafil — available in the United States in an oral form for the treatment of erectile dysfunction — with Respira’s dry-powder inhaler technology AOS-DPI, for Axially Oscillating Sphere dry powder inhaler.

Contrary to other available PAH therapies administrated under a specific treatment regimen, RT234 was designed to be taken when necessary, with on-demand use.

“People suffering from this debilitating and serious condition who are being treated with maintenance therapies still experience episodes of shortness of breath, tiredness and inability to exercise, and there are currently no rapid onset therapies available for ‘as needed’ use to mitigate these episodes,” Satler said.

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The VIPAH-PRN 2b trial is an open-label (no placebo), dose-escalation study in which participants will receive 0.5 mg of RT234. If this dose is found safe and effective, a 1 mg dose — delivered as 0.5 mg twice — will then be assessed.

Participants will be followed for 45 to 76 days. They’ll perform exercise tests before and after their use of the inhaled therapy, including the 6-minute walk test and cardiopulmonary exercise testing.

The study aims to assess the safety and preliminary efficacy of RT234 in easing episodic symptoms and boosting exercise capacity in PAH patients. It will be tested in individuals with PAH who are class 2 — characterized as a slight limitation of physical activity — or class 3, with marked limitation of physical activity, according to the New York Heart Association system.

“Enabling PAH patients to be more active is key to their physical and mental health,” said Raymond L. Benza, MD, the director of the division of Cardiovascular Medicine at The Ohio State University Wexner Medical Center. “Now with the study of RT234, we are examining our ability to boost physical activity when a patient needs it.”

“It’s potentially a great step forward in our battle with this disease,” he added.

RT234 received orphan drug designation from the U.S. Food and Drug Administration for the treatment of PAH. The therapy was deemed safe and well-tolerated in preclinical studies and in a Phase 1 clinical trial (ACTRN12618001077257) in healthy volunteers.

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