[Image from UCLA]
The drug sponge is made from an absorbent polymer coating and is 3D printed to precisely fit veins that carry the blood flowing out of a targeted organ. The sponge could then absorb any leftover cancer drugs that weren’t absorbed by the tumor, reducing the chance of the medication pinioning otherwise healthy organs.
“Surgeons snake a wire into the bloodstream and place the sponge like a stent, and just leave it in for the amount of time you give chemotherapy, perhaps a few hours,” Nitash Balsara, a professor of chemical and bimolecular engineering at UC Berkeley, said in a press release.
UC Berkeley engineers tested the sponge in pigs and found that it took up 64% of a liver cancer drug injected upstream.
“Because it is a temporary device, there is a lower bar in terms of approval by the FDA,” Steven Hetts, an interventional radiologist at UC San Francisco, said. “I think this type of chemofilter is one of the shortest pathways to patients.”
According to the researchers, most cancer drugs are poisonous, which means there is a delicate line when it comes to administering cancer drugs in chemotherapy. The dosage must be enough to stop the growth of cancer cells, but must also not be high enough that it could damage other organs.
“We are developing this around liver cancer because it is a big public health treat – there are tens of thousands of new cases every year – and we already treat liver cancer using intra-arterial chemotherapy,” said Hetts. “But if you think about it, you could use this sort of approach for any tumor or any disease that is confined to an organ, and you want to absorb the drug on the venous side before it can distribute and cause side effects elsewhere in the body. Ultimately, we would like to use this technology in other organs to treat kidney tumors and brain tumors.”
Hetts treats eye and brain tumors using catheters through the bloodstream to deliver chemotherapy drugs directly to the site of a tumor. The catheter method allows for the maximum dose of the medication to be sent to the tumor and the least dose to the rest of the body to minimize the side effects of chemotherapy drugs. While the method is more targeted, the researchers say that more than half of the dose injected into the body can escape through the target organ.
As a solution, Hetts suggested filtering the blood coming out of the targeted organ to remove excess chemotherapy drugs so that less of the drug reaches the whole body.
“An absorber is a standard chemical engineering concept,” Balsara said. “Absorbers are used in petroleum refining to remove unwanted chemicals such as sulfur. Literally, we’ve taken the concept out of petroleum refining and applied it to chemotherapy.”
The researchers found an absorbent polymer that could be easily 3D printed onto a cylinder to fit inside a person’s veins.
“Fitting the cylinder in the vein is important; if the fit is poor, then the blood with the dissolved drug will flow past the cylinder without interacting with the absorbent,” Balsara said.
The researchers are currently testing how much drug is absorbed when the device is implemented at the exit of a healthy pig liver.
“This is a first level in vivo validation that yes, this device will bind up the drug in the bloodstream,” Hetts said. “But extensive animal testing is not the next path; the next path is getting conditional approval from FDA to do first-in-human studies because it is much more realistic to test these in people who have cancer as opposed to continuing to test in young pigs who have otherwise healthy livers.”
The researchers suggest that drug sponges can be applied to different types of tumors and chemotherapy drugs and could be used to absorb other dangerous drugs like high-powered antibiotics.
“We think this is a generally applicable concept,” Hett said.
The research was published in the journal ACS Central Science and was supported by a grant from the National Institutes of Health.
