A third-generation artificial kidney has the potential to provide unprecedented wearability and convenience, enable freedom from phosphate binders and excessive dietary restrictions and produce a significant cost savings.
“We saw all these benefits for the patients and reductions in cost as well –for example, imagine if you look at the cost of phosphate binders; it’s about $1,000 a month per patient,” device developer Victor Gura, MD, from the David Geffen School of Medicine at University of Los Angeles, California, told Nephrology News & Issues. “In the U.S., we have about 600,000 patients. Let’s assume that only 400,000 take phosphate binders – that is more than $4 billion a year.”
The third-generation wearable artificial kidney (WAK 3.0) is expected to undergo a new round of human trials in the near future, although enrollment has not yet begun.
“We already have strong preliminary data that the WAK is safe and effective,” Gura said. “We’ve done the maximum of 24 hours. The next clinical trial will extend the time of treatment to about a week.” If successful, the next and last preapproval trial would probably be for about 8 weeks of treatment.
Evolution of the wearable kidney
The original iteration of the WAK, the 1.0, was not wearable, Gura said. The device was on a breadboard and was large.
“That is what we tried in bench and in pigs,” Gura said. “That had all the modular components on the table working together. That worked, and then when we completed the pig study, we went to human studies.”
For these, the researchers developed a second version of the device. This was an 11-pound wearable version that performed well in three human trials around the world, Gura said.
“When we had completed that, our conclusion was that the WAK works,” he said. “It did more than we expected.”
One major finding was that the WAK 2.0 reduced electrolytes to normal levels. Plasma potassium levels remained normal even after the researchers instructed patients to ingest high potassium foods and beverages, such as orange juice and potatoes. Additionally, acid bases remained normal, with no observations of acidosis or alkalosis. Researchers also found the WAK 2.0 was able to move phosphorus in such amounts that phosphate binders would no longer be needed.
“In the studies, we told the patients to eat things with phosphorus – macaroni and cheese, pizza, whatever they wanted,” Gura said. “Phosphorus didn’t go up.”
Gura said researchers then removed enough salt and fluid so that patients would never have fluid overload. He said patients were able to eat all the salt they wanted and drink all the water they wanted.
“There is no swelling of the legs, there is no water going to the lungs and there is no blunt removal of 2 to 3 liters of water every time they go on dialysis, which is a killer.”
Focus on quality of life
After researchers addressed many of these major concerns, they concluded that the WAK may well get better clinical outcomes, liberalize diet and fluid intake and improve quality of life.
“There is also the fact that the patients will no longer be tethered to a machine and to a chair,” Gura said. “They can go and work wherever they want. They can do whatever they want. They will be less fatigued if they can be completely rehabilitated, and that is a big deal.”
These benefits, plus the possibility of decreased mortality and the substantial cost savings, made the WAK an attractive option to pursue. Gura discussed the possibility of reductions in heart disease as well, although future studies would need to be done in this area.
“I suspect that if the blood pressure excess goes away because the volume is controlled, it is possible that there will be less heart failure because they’re never experiencing fluid overload and there is no salt overload,” he said. “We are hoping this will lead to less heart disease, less strokes and less trips to the hospital. We believe that’s going to be a big step forward.”
The challenge, then, was to find a way to scale the device down enough so that it would be something patients would want to wear. At 11 pounds, the 2.0 did not meet that criteria. Gura and his colleagues worked to develop a device that weighed only 2 pounds. The new device also operates without carbon dioxide bubbles occluding a close dialysate circuit, and features creatinine clearance of greater than 30 mL/min. The WAK 3.0 will be small enough to fit under a shirt, skirt, dress or pair of pants, Gura said.
“They can basically go totally unnoticed when they walk around,” he said. “It gives them back their quality of life.”
Researchers accomplished this by reconfiguring the chemicals and absorbents that accounted for most of the weight of the 2.0. The diurnal dialysate circuit is significantly lighter than the nocturnal circuit, thus allowing for a lighter daytime device.
“Patients do not have to connect to the bloodstream with this device – the connection to the bloodstream never changes,” Gura said. “The patients can go about their lives during the day, and then when they’re in bed, they connect the WAK to the night mode. We can even put the night mode in a pillow or a teddy bear.”
In addition to addressing the use of the device for longer durations, the upcoming clinical trials will evaluate “human factors,” such as how the patient interacts with the device and how the device improves quality of life.
“Our hope is that it is going to do a lot of things for the patients in terms of quality of life. We hope it will reduce mortality. We think that patients are going to go to the hospital less often,” Gura said. “We have enough data to assume that it will have a favorable impact on those outcomes, but that is only potential. We still have to prove it and we haven’t yet, because we haven’t done enough studies yet. I can only state that based on the data we have, the potential for improving lives and outcomes is there.” – by Jennifer Byrne
For more information:
Victor Gura, MD, can be reached at 50 N. La Cienega Boulevard #310, Beverly Hills, CA 90211; email: firstname.lastname@example.org
Disclosure: As developer of the Wearable Artificial Kidney, Gura reports having a financial interest in the device.