Kevin P. Henseler, MD, FACR, Midwest Radiology, Roseville, Minnesota, discusses real-world experience with a unique shear-thinning hydrogel embolic material. In this analysis, the unique material demonstrated technical success across a range of applications and in combination with other embolization agents to produce successful embolization.

These results were first shared at the Society of Interventional Radiology 2024 Annual Meeting in Salt Lake City, Utah. The cases included in this analysis were performed under a limited market evaluation.

Transcript:

IO Learning: What is the OBSIDIO Conformable Embolic, and how does it differ from existing embolization agents?

Kevin Henseler, MD, FACR: Obsidio is a novel embolization material that is basically a hydrogel, which is something that we're generally fairly familiar with, and in that hydrogel is tantalum, which allows you to see it under x-ray guidance, and a nano-silicate particle that allows it to perform the embolization in the unique manner.

That manner requires shear stress to allow what is generally a viscous material, such as peanut butter, to go through a microcatheter when put under pressure, and as soon as it leaves the tip of the microcatheter, it reverts to its natural state of this highly viscous material. Where the material interacts with the wall of the blood vessel, there's some binding that goes on.

It creates a very rapid and complete embolization that allows this material to fill the blood vessel, form a cast of the vessels that are being embolized, and allows a secure, quick, and permanent embolization.

IO Learning: What are the important practical or clinical notes for interventional radiologists to be aware of, if using this agent?

Dr Henseler: One of the things that is important when using this product is to understand what it is and what it isn't. It is a novel product, so it is not, for instance, a liquid embolization. The point of this product is not to flow with the blood flow into the distalmost vasculature. It tends to create the embolic material clot closer to the end of the catheter tip than very, very distally. It is also not a coil, so it is not something that will embolize immediately at the end of your catheter.

It has characteristics that are unique and have to be understood in order to use the product appropriately and in order to figure out the appropriate cases to use the product.

IO Learning: What are factors that would make a patient more appropriate for this technology?

Dr Henseler: OBSIDIO is FDA-cleared for embolization of hypervascular tumors and arterial hemorrhage in vessels 3 mm or less. Early on in utilizing this product, it's often best to consider those factors in choosing patients.

What are some great early cases? It might be an upper GI bleed with a GDA [gastroduodenal artery] embolization. That's a great early case. Other cases are traumatic bleeding or spontaneous bleeding, for instance, retroperitoneal hematoma, pelvic bleeding, or rectus sheath hematoma, those would be great cases that would be very low risk, in order to build some understanding of how the product works and be able to understand the unique properties that you need to understand to use the product in a more advanced way. Those properties being: how big the vessel is, how much blood flow there is in the vessel, what the distal territory looks like.

All those are factors that, with a fairly small number of embolizations, people will rapidly come to understanding as to the much greater and broader breadth of cases that can be utilized with OBSIDIO.

IO Learning: What is the background and rationale for the analysis presented at the SIR Meeting?

Dr Henseler: OBSIDIO was FDA-cleared in July of 2022 and the company immediately began trying to understand exactly how this product is going to be utilized in clinical practice. And the first attempt at that was to set up the [limited market evaluation] LME where 27 sites that were pre-selected were given special training and support in order to see how this material would be utilized in a broad range of indications in clinical practice in real-life in humans.

There were 131 patients studied in this LME and and the goal of that was to understand where OBSIDIO was utilized safely. Were there any cautions that we learned about as well? As to understand, in physicians' hands, how would they use this product and in which cases?

IO Learning: What were the results and outcomes from this analysis?

Dr Henseler: One of the things that was a hypothesis for this product is that it is relatively intuitive for a seasoned interventional radiologist to be able to use. In order to test that hypothesis, we gave it to a bunch of seasoned interventional radiologists who were able to choose which patients and which procedures they wanted to use this in. What we found in the study is that there was a 100% technical success rate. We learned that what we thought was a product that was easy to teach and easy to learn, we found that that is in fact the case.

In the breadth of procedures that were performed, we did find 4 adverse events and they all were limited to the lower GI tract, either rectal arteries or ileocolic arteries and people who were using the material in what we call the aliquot or sandwich technique. That's a technique where a small volume of OBSIDIO is introduced into the catheter and then advanced through the catheter with saline in order to expel it from the catheter. The advantage of that is that it leaves the lumen of the catheter open to be utilized to subselect other vessels or to check on the embolization.

These adverse events triggered some investigation as to what might be some of the limitations of utilizing this product in this aliquot technique. The engineers and scientists at Boston Scientific have taken that data and been able to evaluate some of the limitations with this technique. What we found is that very small volumes of OBSIDIO are more likely to have some difficulty in keeping the embolic plug together, and the saline can interact, and also the more quickly it is advanced through the catheter. There's some understanding now about utilizing larger volumes on the order of 0.1 or 0.2 cc, at the very minimum and not tiny little aliquots.

There is also an understanding of how little of the product needs to be used. One of the things we learned is also that the amount of OBSIDIO initially one thinks they need for embolization is often much more than you actually need, that the OBSIDIO embolization is even more effective than you think and you need a small amount of product.

IO Learning: What is the significance of these results?

Dr Henseler: The results are teaching us that OBSIDIO is a product that offers a broad spectrum of uses that we can consider. The indications are relatively broad in and of themselves, but in the interventional radiology and interventional oncology practice, there are lots of other areas where we use embolics. And many of these were used within the LME.

There are a number of vascular territories, vessel sizes, catheter sizes, all of these were successfully utilized outside of the small limitations of the indications. One of the things that's telling us is that we can safely use this product in a broader array of patients procedures and indications, and it will require us to continue to closely monitor, to ensure that we are able to safely care for patients, for instance, with portal venous embolizations, with other possible venous embolizations, with larger blood vessels.

We also learned that this product can be, and again in these trained hands, often was used as an adjuvant with other products. It could be used with coils to hasten the embolization. This product is agnostic to anticoagulation, that's an advantage. In anticoagulated patients in larger vessels, using this along with a coil can allow a much safer and more confident occlusion versus coils alone. We’re seeing the utility of this as an adjuvant and as a partner with other embolization products in order to enhance both products. The advantages of some of the other embolic products and the advantages of OBSIDIO are synergistically coming together to actually give better outcomes.

IO Learning: What are the future steps for this research?

Dr Henseler: The next step is the OCCLUDE study, for which sites are currently being enrolled, and this study is going to be prospective, versus the retrospective study, on the use of OBSIDIO, following patients so that we are able to more definitively assess the success of embolization, evaluate for any adverse events, and once again be able to understand the use of the product in a broader range when physicians are given the opportunity to use this product in their normal daily practice.

IO Learning: Is there anything else you would like to add?

Dr Henseler: I would summarize by saying that OBSIDIO is a new class of embolic material. It is different than all of the other embolic that we are currently familiar with and so it does take some understanding of what the engineering and characteristics of the product uniquely deliver. Once you have that understanding, the initial LME study tells us that it is a very successful with 100% success, it let us understand that there is a broad array of procedures for which it is likely to be helpful.

Moving forward, we are excited to be able to more closely understand which patients are going to have significant benefit and further demonstrate safety, efficacy, and ease of use of this product.

Source:

Oklu R. Real-World experience with Obsidio Conformable Embolic: Data from 131 US cases. Presented at Society of Interventional Radiology Annual Meeting. March 23-28, 2024; Salt Lake City, UT