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June 27, 2024

VenoStent: The Promise of Safer Treatment for Dialysis Patients

Over 800,000 people in the U.S. suffer from end-stage renal disease (ESRD) or kidney failure, a medical condition where the kidneys permanently stop functioning and can no longer filter waste from the blood. Patients with ESRD must receive dialysis or a kidney transplant to survive more than a few weeks. Because of the limited availability of kidney transplants, the vast majority of these patients rely on hemodialysis to survive. In order to perform dialysis, patients must have an access point into their vascular system capable of handling the high blood flows necessary to perform hemodialysis.

The preferred vascular access point for dialysis is an arteriovenous fistula (AVF). A vascular surgeon creates an AVF by forming a connection between an artery and vein in a patient’s arm. After an AVF is created, physicians must wait between one to four months for the AVF to dilate and thicken before it can be used for dialysis, a process called “maturation.” However, because of the poor cardiovascular health of ESRD patients, the maturation process is very challenging, and a significant proportion of ESRD patients are unable to use their AVFs for dialysis. In fact, only 40 percent of AVFs remain operational within one year after their creation.

VenoStent, an innovative medical device company based in Houston, Texas, is aiming to dramatically improve outcomes for AVF patients with its bioabsorbable perivascular wrap, SelfWrap. In early human studies, SelfWrap has demonstrated the potential to significantly improve the AVF maturation process and allow AVFs to remain functional longer. Once approved by the FDA, VenoStent’s SelfWrap has the potential to significantly improve access to life-saving dialysis for ESRD patients. Norwest is proud to join in VenoStent’s Series A funding to help bring its ground-breaking technology to patients.

The Complications of Dialysis Access Methods

Each year, over 500,000 ESRD patients receive dialysis in the U.S. Dialysis is a medical procedure where a patient’s blood is run through a machine that filters and cleans the blood of waste material. The “cleaned” blood is then returned to the patient. As mentioned earlier, in order to undergo dialysis, patients must have an access procedure to create or reach blood vessels with sufficient blood flow to support a dialysis machine.

Most patients begin dialysis with a temporary catheter implanted in the chest, called a central venous catheter (CVC). However, because a CVC leaves an indwelling catheter with direct connection to the outside world, they suffer from significant infection complications. Roughly 50 percent of patients with a CVC will have a serious infection within only three months of placement. If a patient has to use a CVC for a year, it is almost certain they will have a life-threatening bloodstream infection (i.e., sepsis) at some point.

Typically, CVCs are the stepping stone to a longer-term solution, such as arteriovenous fistula (AVF), a surgically created connection between an artery and vein — the preferred access method mentioned above. Over 500,000 AVF surgeries are performed every year in the U.S. After an AVF is created, doctors have to wait weeks to months for the AVF to dilate and thicken to a point where it is capable of performing dialysis (i.e., “become functional”), a process known as “fistula maturation.” However, because of the poor cardiovascular health of ESRD patients, the maturation process is very challenging, and a significant proportion of ESRD patients are unable to use their AVFs for dialysis. Vascular surgeons have long clamored to find a better way to create AVFs.

The most common complication during the AVF maturation process is something called intimal hyperplasia, which is a thickening and narrowing (i.e., stenosis) of the blood vessel wall on the inside of the fistula. Intimal hyperplasia is the result of injury to the vessel wall due to the increased turbulence and shear force from high pressure arterial blood flowing into the thin walled vein in a fistula. Approximately 65 to 85 percent of AVFs develop intimal hyperplasia and the resulting stenosis and subsequent blood clot formation (i.e., thrombosis) are the leading causes for AVF failure.

The VenoStent Solution

To provide a better solution for dialysis patients, VenoStent has developed SelfWrap, a bioabsorbable perivascular wrap that vascular surgeons place around the juncture where they connect the artery to the vein. SelfWrap provides both structural support and optimized blood flow to limit the formation of intimal hyperplasia. The bioabsorbable polymer used in the SelfWrap provides an artery-like structural support to stabilize the vein wall and limit the turbulence created by fistula, and the geometrical shape of the SelfWrap maintains an optimal 30-degree angle between the artery and vein to limit shear stress. Placing the SelfWrap adds a mere 5-10 minutes to the AVF procedure, and, over time, the wrap dissolves, leaving only a native blood vessel.

Promising Early Results

Early indications are that SelfWrap achieves impressive results. The first-in-human trial produced 90 percent unassisted maturation and 95 percent functional maturation at six months – compared to 33 percent and 58 percent, respectively, with the current standard care. In addition, 90 percent of patients with the SelfWrap were able to remove their CVC within 9 months of placement compared to 27 percent of patients with the current standard of care. The SelfWrap procedure was very safe with no adverse events reported in the first-in-human study. These data suggest that the use of SelfWrap — which helps reduce frequent complications of AVF procedures and dialysis access — may save the healthcare system well over $10,000 per patient annually in caring for people living with ESRD.

As a result of the encouraging first-in-human trial results, the FDA granted SelfWrap “Breakthrough Device” status in May 2022. VenoStent is currently conducting a 200-person pivotal trial for FDA approval. Pending positive results from the pivotal trial, the company expects to receive FDA approval for SelfWrap in late 2026.

Why We’re Excited

Norwest’s healthcare team examines scores of young companies in search of those with the ability to deliver on our two primary goals: better patient outcomes at lower cost.

Our recent investment in VenoStent meets our criteria and gives us several reasons to be excited about its future. Among them are:

  • The company is addressing a serious unmet need in a large patient population that currently has no other options.
  • The SelfWrap procedure is safe, fast, and easy to perform, and it fits nicely within the existing workflow of AVF surgeries.
  • The first-in-human trial demonstrated compelling, never before seen results.

VenoStent has compiled a top-tier management team that is supported by a strong board of directors and an experienced team of advisors with extensive experience in medical-device development and approval

Most exciting of all is the very real prospect that thousands of patients with ESRD will see a marked improvement in their quality of life.

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