Safety and Efficacy Of amber Peripheral liquid embolic system: a First-in-Human & Pivotal Study. Stage I. OPAL Study

Inside the human body, blood vessels are the essential highways that deliver oxygen and nutrients to every organ. Sometimes, these roads need to be closed off. Whether to stop a dangerous bleed, to shrink a tumor by cutting off its fuel supply, or to seal a weak spot in a vessel, doctors use a technique called embolization. This involves threading a tiny tube through the blood vessels to a specific spot and releasing a substance that blocks the flow. For decades, doctors have used various materials for this job, from tiny metal coils to liquid glues. While effective, some of these older liquids have drawbacks: they can be difficult to see clearly on scans, they require complex mixing before use, or they can stick to the delivery tube, making it hard for the doctor to pull back.

A new liquid material called Amber 20 has been developed to address these issues. It is designed to be easy to see on imaging, ready to use straight from the vial, and it does not stick to the catheter. To see if this new tool is safe and works as intended, a team of doctors across Spain conducted a first-of-its-kind study. They tested the system in fifteen patients who needed urgent or planned vascular blockages for various reasons, ranging from active bleeding to treating tumors. The goal was simple: to see if the device could safely stop blood flow without causing harm to the patient or getting stuck in the body.

The study, known as the OPAL trial, brought together specialists from eleven different hospitals to treat fifteen patients between March and November 2024. The patients ranged in age from young adults to seniors, with a median age of 56. Their conditions were diverse. Some were suffering from active arterial bleeding or aneurysms, which are bulging weak spots in vessel walls. Others had hypervascular tumors, which are growths that feed heavily on blood, or type II endoleaks, a complication where blood leaks back into a repaired aortic aneurysm. A few patients needed the procedure to prepare for liver surgery or to treat a non-functioning organ. In every case, the doctors needed to permanently block specific blood vessels to solve the problem.

The procedure involved guiding a microcatheter, a tube thinner than a human hair, through the blood vessels until it reached the target area. The doctors then injected the Amber 20 liquid. Unlike some older agents that require shaking or mixing with other chemicals, Amber 20 was ready to use immediately. Once it touched the blood inside the body, a chemical exchange occurred. The liquid solvent in the vial moved out, and the liquid began to solidify into a soft plug within about four minutes. Because the material does not stick to the tube, the doctors could move the catheter around or inject more liquid if needed without the risk of the tube getting trapped inside the vessel.

The results were striking. In all fifteen cases, the doctors achieved complete blockage of the targeted vessels. The liquid successfully stopped the blood flow exactly where it was needed, a result known as technical success. This happened in every single patient, meaning the device worked perfectly in terms of its primary function. The doctors also observed that the material was easy to see on X-ray images during the procedure, allowing them to guide it precisely without needing to mix in extra contrast agents.

Safety was the other major focus of the study. The researchers looked closely for any serious problems caused by the device itself within the first 24 hours after the procedure. They found none. No patient suffered a device-related serious adverse event. One patient did experience a mild fever and discomfort after the procedure, a condition known as post-embolization syndrome, which is a common reaction to the body healing from the blockage. However, this was attributed to the procedure itself rather than the new liquid, and the patient recovered fully. Across the entire group, all side effects were mild or moderate and resolved without any lasting damage. No issues with the device, such as it breaking or failing to work, were reported.

The study also highlighted a specific advantage of the Amber 20 material regarding future care. Because the liquid contains iodine bonded directly into its structure, it shows up clearly on computerized tomography (CT) scans without creating the cloudy, starburst-like shadows that other materials often produce. This clarity is crucial for doctors who need to take follow-up images to ensure the blockage remains effective, particularly in cases like endoleaks where precise monitoring is vital. The absence of these visual artifacts means doctors can see the anatomy more clearly in the days and weeks after the treatment.

While the results are promising, the researchers are careful to note the limits of this initial work. The study included only fifteen patients, which is a small number for medical research, and it did not include a long-term follow-up period to see how the material behaves over months or years. The study was designed as a first step to prove the concept and safety of the device. The authors conclude that Amber 20 appears to be a safe and effective tool for blocking peripheral blood vessels, with a high success rate and a clean safety profile in this early group. These findings suggest that the material is ready for the next phase of testing, which will involve a larger group of patients and a longer observation period to confirm these early successes.