Catheters are used today to deliver drugs directly to tumors to avoid broadcasting toxic chemotherapy agents throughout the body. Nevertheless, half of the drug can escape to the rest of the body, causing side effects. Doctors treating liver cancer teamed up with chemical engineers to design a polymer-coated device that can be temporarily placed in the vein coming out of the liver to absorb unused drugs, potentially lowering risk.

With the help of sponges inserted in the bloodstream to absorb excess drugs, doctors are hoping to prevent the dangerous side effects of toxic chemotherapy agents or even deliver higher doses to knock back tumors, like liver cancer, that does not respond to more good treatments.The "drug sponge" is an absorbent polymer coating a cylinder that is 3D printed to fit precisely in a vein that carries the blood flowing out of the target organ the liver in liver cancer, for example. There, it would sop up any drug not absorbed by the tumor, preventing it from reaching and potentially poisoning other organs. 

Polymer-coated drug

In early tests in pigs, the polymer-coated drug absorber took up, on average, 64 % of a liver cancer drug the chemotherapy agent doxorubicin injected upstream."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," said Nitash Balsara, a professor of chemical and biomolecular engineering at the University of California, Berkeley, and a faculty scientist at Lawrence Berkeley National Laboratory.

"Because it is a temporary device, there is a lower bar regarding approval by the FDA," said Steven Hetts, an interventional radiologist at UC San Francisco who first approached Balsara in search of a way to remove drugs from the bloodstream. "I think this type of hemofilter is one of the shortest pathways to patients." Most anticancer drugs are poisonous, so doctors walk a delicate line when administering chemotherapy.

A dose must be sufficient to kill or stop the growth of cancer cells, but not high enough to irreparably damage the patient's other organs. Even so, chemotherapy is typically accompanied by significant side effects, including nausea, vomiting, diarrhea, and suppression of the immune system, not to mention hair loss and ulcers. "They are developing this around liver cancer because it is a big public health threat there are tens of thousands of new cases every year and we already treat liver cancer using intra-arterial chemotherapy," Hetts said.

"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, Balsara and their colleagues at UC Berkeley, UCSF and the University of North Carolina, Chapel Hill, will publish their results online Jan. 9 in the journal ACS Central Science, an open-access publication of the American Chemical Society.