Bayer Starts Phase 2 Trial of BAY 3670549 for Atrial Fibrillation

Bayer has started a global Phase 2 clinical trial to evaluate BAY 3670549, an investigational treatment being developed for atrial fibrillation (AFib).

The study, registered as NCT07625215, will test whether BAY 3670549 can help restore the heart to a normal rhythm in adults with AFib.

BAY 3670549 is designed to target a protein called G-protein-coupled inwardly rectifying potassium channel 4, or GIRK4. By blocking this channel, Bayer is investigating whether the drug can change the electrical activity of heart cells and help control an irregular heartbeat.

The Phase 2 trial will evaluate the drug's effectiveness, safety, tolerability, pharmacodynamics, and pharmacokinetics.

What Is Atrial Fibrillation?

Atrial fibrillation is the most common type of sustained irregular heart rhythm.

In a healthy heart, electrical signals help the heart beat in a coordinated way. With AFib, the electrical signals in the upper chambers of the heart, called the atria, become rapid and disorganized.

As a result, the atria quiver instead of contracting normally.

This can cause symptoms such as a fast or irregular heartbeat, shortness of breath, tiredness, and reduced ability to perform normal activities.

AFib can also increase the risk of blood clots. Because the atria do not empty blood efficiently, blood can collect and form clots. A clot can then travel to the brain and cause a stroke.

AFib is also associated with an increased risk of heart failure.

AFib Affects Millions of People Worldwide

The condition has become a growing health concern worldwide.

More than 60 million people are estimated to live with AFib globally.

The number of people affected is also expected to increase as populations age. Projection studies estimate that the number of people with AFib could reach 15.9 million in America by 2050 and 17.9 million in Europe by 2060.

People with AFib are around five times more likely to experience a stroke than people without the condition.

AFib-related strokes can also be particularly serious, with reported one-year mortality of around 50%.

What Is BAY 3670549?

BAY 3670549 is an investigational, highly selective GIRK4 inhibitor.

The drug is being developed as a potential new approach for controlling the electrical activity of heart cells.

In simple terms, Bayer is trying to influence one of the electrical systems that helps control how the heart beats.

The company is studying BAY 3670549 as a possible treatment for rapidly converting AFib back to normal sinus rhythm.

Normal sinus rhythm is the regular heartbeat controlled by the heart's natural electrical pacemaker.

How Does GIRK4 Work?

GIRK4 channels are specialized proteins found in heart cells.

They help control electrical activity by allowing potassium ions to move through the cells in response to signals involving the neurotransmitter acetylcholine.

These channels have an important role in the later part of the heart's electrical signalling process.

One important measurement is the atrial effective refractory period, or AERP. This refers to the period during which the atria are temporarily unable to respond to another electrical signal after a heartbeat.

Increased GIRK4 channel activity can shorten this recovery period.

This shorter recovery time can make it easier for abnormal electrical signals to continue circulating through the atria, which can contribute to AFib.

BAY 3670549 is designed to inhibit GIRK4. Bayer is investigating whether this can help change the electrical environment in the atria and support restoration of a normal heart rhythm.

Phase 2 Trial Will Compare BAY 3670549 With Placebo

The Phase 2 study is randomized, double-blind, placebo-controlled, parallel-group, and multi-cohort.

In simple terms, participants will be assigned to different treatment groups, and some will receive BAY 3670549 while others will receive a placebo.

Neither the participants nor the researchers directly assessing the treatment will know which treatment each participant receives during the blinded part of the study.

The trial will include adults with AFib who require electrical cardioversion.

Researchers will examine whether BAY 3670549 can help restore normal heart rhythm and will also closely monitor safety and tolerability.

What Is Electrical Cardioversion?

Electrical cardioversion is a medical procedure used to restore the heart to a normal rhythm.

During the procedure, a controlled electrical shock is delivered to the heart.

It can be effective, but it generally requires a hospital-based setting. Patients usually need sedation or, in some cases, anaesthesia before the electrical shock is delivered.

This makes the procedure more resource-intensive and can make it difficult to use as a simple, rapid treatment option.

Bayer is investigating whether BAY 3670549 could eventually provide another way to restore normal rhythm without relying on electrical cardioversion in every situation.

Current Drug Options Also Have Limitations

Anti-arrhythmic drugs are already used to manage symptomatic AFib.

However, these medicines are not suitable for every patient.

Some drugs have important contraindications, including limitations for people with certain types of structural heart disease.

There are also safety concerns with some anti-arrhythmic medicines because they can cause abnormal heart rhythms and, in serious cases, sudden death.

Their effectiveness can also be limited in the short term, and some treatments require close medical monitoring.

These limitations are part of the reason Bayer is investigating a different approach through GIRK4 inhibition.

Phase 1 Study Supported Further Development

Before moving into Phase 2, BAY 3670549 was evaluated in a first-in-human Phase 1 study.

The Phase 1 single-ascending-dose study was conducted in healthy male and female participants.

According to Bayer, BAY 3670549 showed a favourable safety and tolerability profile in the study.

These findings supported the company's decision to continue development and move the drug into testing in patients with AFib.

The Phase 2 study will now provide information about how the treatment performs in people who actually have the condition.

Bayer Looks at a Potential Rapid Cardioversion Approach

Bayer is developing BAY 3670549 with the goal of potentially achieving rapid cardioversion.

If the approach is successful, the treatment could provide a fast-acting option for patients experiencing AFib.

The company is also studying whether the treatment can offer a well-tolerated alternative to some of the challenges associated with electrical cardioversion.

However, BAY 3670549 is still an investigational treatment. The Phase 2 study will be important for understanding whether the biological approach translates into meaningful clinical benefits.

Bayer Developed the Program With the Broad Institute

BAY 3670549 originated from a strategic research alliance between Bayer and the Broad Institute.

The collaboration helped identify and develop the GIRK4-targeting approach.

The program is now part of Bayer's cardiovascular drug development activities as the company works to explore new ways of treating heart rhythm disorders.

Bayer Highlights the Need for New AFib Treatments

Dominik Ruettinger, M.D., Ph.D., head of research and early development at Bayer's Pharmaceuticals Division, said the start of the Phase 2 trial is an important step for the BAY 3670549 program.

He said GIRK4 inhibition could potentially provide a new approach to treating AFib and that patients and physicians need fast-acting and well-tolerated treatment options.

The company will now use the Phase 2 study to generate additional clinical data on the treatment.

What Will Researchers Study in Phase 2?

The Phase 2 trial will look at several aspects of BAY 3670549.

The main areas of investigation include its effectiveness in patients with AFib, safety, and tolerability.

Researchers will also study pharmacodynamics and pharmacokinetics.

Pharmacodynamics looks at what the drug does in the body, including its biological effects.

Pharmacokinetics looks at how the body absorbs, distributes, processes, and removes the drug.

Together, these measurements will help researchers understand how BAY 3670549 behaves in patients and how it affects the heart.

What Comes Next for BAY 3670549?

The global Phase 2 trial will now evaluate BAY 3670549 in adults with AFib who require electrical cardioversion.

The results will help Bayer understand whether targeting GIRK4 can provide a useful way to control abnormal electrical activity in the heart and restore normal sinus rhythm.

If the Phase 2 results support continued development, Bayer will have additional information to determine the next clinical steps for BAY 3670549 and its potential role in the treatment of atrial fibrillation.