AuthorisedHuman Pharmacology (Phase I)- OtherInterventional

Phase Ib Dose-Ranging Study of the Safety, PK, PD & Efficacy of the Activin Signaling Inhibitor HS235 vs placebo added to background therapy in PAH (SEASIDE)

This study is investigating a new medicine, HS235, for people who have pulmonary arterial hypertension (PAH). PAH is a serious condition where blood vessels in the lungs become narrow, making it hard for the heart to pump blood. The main purpose of this study is to find a safe and suitable dose of HS235 when given alongside the treatments people are already using. Researchers will also be checking how the body takes in, uses, and gets rid of the medicine. This is an early-stage study, meaning it's one of the first times this medicine is being tested in people. The goal is to see if HS235 could help improve the health and well-being of people living with PAH.

At a glance

Status

Authorised

Phase

Human Pharmacology (Phase I)- Other

Sponsor

35Pharma Inc.

Enrolment target

Start

23 Dec 2025

Pulmonary arterial hypertension

What is this study about?

Imagine your lungs have tiny blood vessels that carry blood. If these vessels become too narrow, it's like trying to pump air through a pinched hose – it's much harder work. This is what happens in a condition called Pulmonary Arterial Hypertension (PAH). Your heart has to work extra hard to push blood through these narrowed vessels, which can cause symptoms like breathlessness, tiredness, and chest pain.

This study is testing a new medicine called HS235. Researchers believe that HS235 might work by targeting a specific pathway in the body that contributes to the narrowing of these lung blood vessels. By blocking this pathway, the hope is that HS235 could help to relax and widen these vessels, making it easier for blood to flow through your lungs and reducing the strain on your heart.

The study is called 'SEASIDE' and is in an early phase of testing. This means they are carefully looking at how much of the new medicine to give, how safe it is, and how your body reacts to it. They will compare HS235 to a 'placebo', which looks like the real medicine but has no active drug in it. This helps them understand the true effects of HS235, beyond what might happen naturally or through other treatments you are already taking.

Key takeaways

This study is testing a new medicine (HS235) for Pulmonary Arterial Hypertension (PAH).
It aims to find a safe and effective dose.
Participants will receive either HS235 or a placebo alongside their current treatments.
Close medical monitoring will be part of the study.
It is an early-stage study, looking at safety and how the body handles the medicine.

Who may be eligible?

To be considered for this study, you would generally need to be an adult, aged 18 years or older, and have received a diagnosis of Pulmonary Arterial Hypertension (PAH). The study is open to both men and women.

There will be other, more detailed criteria that the doctors and study team will check to make sure the study is right for you and safe for you to participate. These might include specific details about your current health, other medicines you are taking, and certain test results related to your PAH. Your usual doctor and the study team would discuss all of this with you in detail.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Am I 18 years old or older?
Do I have a diagnosis of Pulmonary Arterial Hypertension (PAH)?
Am I currently on treatment for PAH?
Am I able to attend regular appointments at a study clinic?

Answer every question to see your result.

What does participation involve?

If you decide to take part, you would attend regular visits to the study clinic. These visits would involve health checks, blood tests, and other assessments to monitor your condition and how you are responding to the study medicine. You would receive either the new medicine, HS235, or a placebo, in addition to your current PAH treatments. The study team would explain exactly how and when to take the medicine. You would be closely monitored throughout the study, and there would be follow-up appointments after you stop taking the study medicine. The total length of your involvement in the study would be explained in full by the research team.

Potential risks and benefits

Participating in a study means you might receive a new medicine that could potentially help your PAH, though there's no guarantee. Your condition will also be closely monitored by healthcare professionals, which can be reassuring. However, like all medicines, HS235 might have side effects, and some are unknown at this early stage. You might also have to attend extra hospital visits. It's important to remember that you can stop taking part in the study at any time, for any reason, without it affecting your usual medical care.

Locations (5)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

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Unverified
Hungary
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Unverified
Spain
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Unverified
Poland
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Unverified
Germany
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Unverified
Czechia

Common questions

What is Pulmonary Arterial Hypertension (PAH)?

PAH is a serious lung condition where blood vessels in your lungs become narrow, making it hard for your heart to pump blood.

What is HS235?

HS235 is a new medicine being tested. It's designed to help relax and widen the narrowed blood vessels in your lungs.

What is a 'placebo'?

A placebo looks like the study medicine but doesn't have any active drug in it. It helps researchers understand the real effects of the new medicine.

Will I still take my regular PAH medicines if I join?

Yes, HS235 or the placebo would be given in addition to your usual PAH treatments.

Is this a new medicine for humans?

This is an early-stage study, meaning it's one of the first times this specific medicine, HS235, is being tested in people.