Q&A: Xeltis implants first restorative hemodialysis graft in humans
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Xeltis, a Swiss-Dutch medical device company, reported that it implanted patients with kidney failure who required dialysis with aXess, the first restorative synthetic hemodialysis access graft.
The aXess graft is designed to restore living blood vessels using patients’ tissue and may be lifechanging for those in need of vessels. The trial launched in June 2021 and researchers expect it to reach primary completion by June 2022. Ultimately, the study should end in December 2026.
Healio interviewed Matteo Tozzi, MD, vascular surgeon and professor of vascular surgery at Università dell’Insubria in Italy, and Frans L. Moll, MD, PhD, professor emeritus of vascular surgery at the University Medical Center Utrecht in The Netherlands, about the progress of the trial.
Healio: Can you describe the aXess graft?
Moll: Currently, polymer is extremely hot in bio research because it is compatible to the human body, and in contrast to what has been implanted in the past, Xeltis polymers are biodegradable, which means that there are no adverse effects from long-term presence in the body.
I use the word biodegradable because the fibers are being replaced by your own endogenous cells and your tissue, but we call it endogenous tissue restoration. The implant forms the frame, and subsequently your body builds a new vessel, while the frame is replaced. That is why we call it endogenous tissue restoration, and that is what makes it a unique novel concept.
There is extensive experience from previous studies with this material, that this polymer fiber structure can be, let's say, overtaken by your own cells. If you make a graft using electrospinning along a mandrel, it makes a loop for the dialysis. Then the graft acts like a kind of "homing" device. It's not too porous, so it doesn't leak extensively, but it allows your own cells to go into the matrix of the graft and ultimately replace it. If you have a blood vessel to replace an artery, you would like it to have a protective layer of endothelial cells to prevent the graft to thrombose. Likewise, at the outer side, where you normally have the adventitia, you would want a similar layer to allow micro blood vessels to go into that new graft.
It is important that the replacement vessel is infection resistant. So, if you have a current artificial graft and, if for example, you give your patient antibiotics, the antibiotics can penetrate the graft and conquer the infection. But also, with new endogenous endothelial from your own cells there, the probability is that you have less chances to get thrombosis.
Xeltis proved this with more than 300 animal studies with 2-year follow-up across all applications, and at least 1 year of follow up for dialysis. Now, Xeltis selected different sites in Europe and at the moment, there are several grafts being implanted in dialysis patients.
Healio: What unmet research needs do you hope to address with this study?
Moll: For years there has been a need to come up with a graft that matches the endogenous AV fistula procedures but does not include the drawbacks of those AV fistula technologies. For example, the time waiting for maturation is sometimes disappointing, and once you have a functioning endogenous AV fistula access, you still must wait a long time. Sometimes, the patients can't wait that long before they go to dialysis. Of course, you can use catheters, but those catheters can also cause infection and complications. So, it would be nice if there was substitute that could match with the endogenous human body structures.
Tozzi: A big problem in the world of dialysis is the high percentage of patients who become infected. Another common problem is when patients are not good candidates for AV fistulas. There is a good chance patients will be candidates for the standard graft, but it needs a lot of long-term maintenance. After approximately 5 years, it becomes necessary to change the graft because the standard Lifespan ePTFE Vascular Graft is not a magical device. So, the cannulation can damage the wall and, over time, the wall can be completely destroyed.
The new endogenous tissue regeneration graft solves both problems. Endogenous tissue restoration graft causes less damage by cannulation and less intragraft stenosis because, as more time passes, the biosynthetic route is transformed into living tissue. So, it is perfect for patients without good vascular access to produce an AV fistula.
Healio: Are there any existing or foreseeable obstacles?
Tozzi: Each patient is different from another and so is each vascular access. This is an obstacle in this type of work.
Moll: Due to COVID-19, we were unable to travel to the different sites, so implantation was delayed. Then, the problem with dialysis is that each patient needs an individualized personal treatment and indication. Each dialysis surgeon must work together with a nephrologist to find creative solutions. Perhaps this patient is obese, the other one is skinny, or one has already had an AV fistula which failed and the other one did not mature. There are different approaches from one site to another site. Or geographically, for example, the West Coast of the United States is doing a lot of straight grafts, while the East Coast is more doing loops.
Healio: Have you been surprised by anything in your findings?
Moll: Personally, I am not surprised. So far, so good. We are optimistic.
Tozzi: I was surprised when I had my first aXess on my hands because of its different texture compared to ePTFE ones. Knowing the pathophysiology of intimal hyperplasia and the complications of the vascular access, for the first time in my life, I saw a product that could potentially reduce these complications. I was surprised that aXess may be the cure to most vascular access problems. I'm impressed and excited to participate in the first trial with the aXess graft.
Healio: Is there anything from your findings that you feel is crucial to make physicians aware of at this time?
Tozzi: aXess is important for surgeons, but it is also important for patients. Those on hemodialysis rely on the functionality of the vascular access. So, when patients have a good vascular access, they will most likely have a life as long as someone without chronic kidney disease. I think it is crucial that patients have a long life on dialysis, and for that to happen, they need a functioning graft.
Moll: We all hope that ultimately the pandemic will slow down and that we can speed up with the program.
For more information:
Matteo Tozzi, MD, is associate professor of vascular surgery at the Research Center for the Study and Application of New Technology in Vascular Surgery, department of medicine and surgery at the University of Insubria, Varese.
Frans L. Moll, MD, PhD, is professor of vascular surgery, in the department of vascular surgery at University Medical Center Utrecht.
They can be reached through their universities. For media, the Xeltis media contact Laura Monti can be reached at laura.monti@xeltis.com.
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Healio Interview
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