Results of the GPX Embolic Device Clinical Trial: An Interview With Dr. Andrew Holden

VASCULAR DISEASE MANAGEMENT. 2023;20(4):E77-E78

At the 2023 Society of Interventional Radiologists (SIR) Annual Meeting in Phoenix, Arizona, Interventional Radiologist Andrew Holden, ONZM, MBChB, FRANZCR, EBIR, from Auckland City Hospital in New Zealand, presented final results from the GPX Embolic Device (Fluidx) clinical trial. This prospective, single-arm, multicenter, open-label, nonrandomized, first in-human feasibility study examined the use of this novel liquid embolic agent in distal applications within the peripheral vasculature. GPX is designed for use in durable and preoperative transcatheter embolization procedures. Forming an electrostatic gel in response to physiological ionic strength upon exiting the catheter, it follows vascular flow and is designed for deep distal penetration of distally flowing vessels and complex vessel beds. Technical success, freedom from adverse events, and handling/performance characteristics were assessed.

Vascular Disease Management spoke with Dr. Holden to discuss the results of the study and what it means for embolization treatment. 

Dr. Holden, tell us about the presentation you’re giving at SIR 2023 about the results of the Fluidx GPX Embolic device clinical trial. 

We are going to present the results of the Fluidx GPX Embolic device clinical trial that we used in a total of 17 patients with diverse distal embolization needs in New Zealand in a first in-human trial. This was performed at 2 centers: my center in Auckland, and another in Christchurch. The GPX Embolic device is an aqueous-based embolic agent that solidifies inside the vasculature through ionic bonding to form a solid, liquid embolic. It’s very radio-opaque through tantalum, so it's rapidly and easily formed through two 1-mL syringes that are mixed backwards and forwards at least 25 times to suspend the tantalum. Then it can be injected via a standard microcatheter. Compared to many liquid embolics, preparation is extremely easy. The tantalum means that it's very well visualized. It's also a nonadhesive liquid embolic, so you can inject it with great control, minimizing the risk of nontarget embolization.

How long did the study last? What were the results?

We recruited the full cohort of patients over 5 to 6 months. The indication for treatment is an indication for embolization, primarily in the arterial side, but I'll also talk about the venous applications. Essentially, the indication is where you're wanting to treat or embolize tapering distal vasculature. Therefore, it’s not indicated for treating an aneurysm or endoleak where you are treating an uncontrolled space. It's indicated where the vasculature is tapering, such as a vascular tumor or, on the venous side, portal vein embolization prior to resection.

The reason for that is that this liquid embolic is not only very easy and safe to use, but it embolizes very distally in the vasculature, providing a very profound embolic effect. If you were, say, trying to embolize it through an arteriovenous shunt or an aneurysm, you wouldn't be able to control where it goes. It has very specific indications.

In all cases, technical success was achieved, with target regions fully occluded at the first angiogram and excellent distal penetration into vessel beds. At 30-day follow-up, all patients reported good outcomes and sites remained fully occluded. Stable positioning of the embolic device was confirmed where imaging was available.

What’s the main takeaway you want attendees to learn from your presentation?

The cohort of patients that we have treated include benign and malignant vascular tumors and renal cell carcinoma prior to resection or angiomyolipoma, but also, as I mentioned, portal vein embolization. The key messaging I have is we had 100% technical success—that is, acute and complete occlusion.

You get a very profound acute efficacy in terms of embolization because you get distal penetration and profound embolization, so we saw a fantastic tumor response. I think the key messaging here is we've got a new embolic, it has specific indications, it can be administered very easily and safely, and it has a very profound embolic effect. That means that patients may have postembolization syndrome over the following day or two because of the embolization effect, but they'll get a profound clinical result. I think it's very exciting because it's actually filling a gap, an unmet need that no other agent is filling at the moment. n