Engineers at Duke University created a promising novel cancer treatment delivery system and demonstrated its efficacy against one of the disease’s most complex forms. The scientists demonstrated how a radioactive implant could completely eliminate tumors in the majority of rodents in newly published research. The study looks at mice with pancreatic cancer, and shows what the researchers claim is the most effective treatment ever studied in these pre-clinical models.

The trouble with pancreatic cancer

Due to the pancreatic cancer tumor cells’ high evasiveness and abundance of mutations (rendering them resistant to many medications), it is notoriously difficult to diagnose and treat. Although it accounts for only 3.2 percent of all cancers, it is the third leading cause of cancer death. One approach is to use chemotherapy to keep the tumor cells in a vulnerable state to radiation and then hit the tumor with a targeted radiation beam.

However, doing so in a way that attacks the tumor while avoiding exposing the patient to high doses of radiation is a fine line to walk. Plus, this method increases the risk of severe side effects. Another approach being researched is the use of implants that can be placed directly inside the tumor to attack it from within with radioactive materials. They have made some progress by encasing radioactive samples in titanium shells, but these can cause damage to the surrounding tissue.

“There’s just no good way to treat pancreatic cancer right now,” study author Jeff Schaal said.

Attacking tumors from the inside out

Schaal and his colleagues investigated a different type of implant, one made of more biocompatible materials that would not pose the same risks to the human body. The researchers used elastin-like polypeptides (ELPs), which are synthetic chains of amino acids that remain liquid at room temperature but form a stable gel-like material in the warmer environment of the body.

This substance was injected into tumors in various pancreatic cancer mouse models, along with a radioactive element called iodine-131, a well-studied and widely used isotope in medical treatment. In this environment, the ELP encapsulates the iodine-131, preventing it from leaking into the body while allowing it to emit beta radiation that penetrates the tumor. When the radiation is exhausted, the ELP bio gel safely degrades into innocuous amino acids.

The treatment was tested in conjunction with paclitaxel, a common chemotherapy drug. The radioactive implants were injected into cancer tumors just beneath the skin, but with mutations known to occur in pancreatic cancer, as well as tumors within the pancreas itself, which historically are more difficult to treat.

The scientists report a 100 percent response rate to the treatment across all models tested. The dual treatment completely eliminated the tumors 80 percent of the time in three-quarters of the models. The researchers used the novel treatment against pancreatic cancer to investigate its potential against one of the disease’s most difficult forms, but they believe the results bode well for its wider application.

“We think the constant radiation allows the drugs to interact with its effects more strongly than external beam therapy allows,” Schaal explained. “That makes us think that this approach might actually work better than external beam therapy for many other cancers, too.”

Next steps

There is a lot to work out before this treatment can be administered to humans, with trials on larger animals being the researchers’ immediate next step. They do claim that these findings are unprecedented in terms of how effectively the treatment disintegrated the tumors, with team member Ashutosh Chilkoti calling them “perhaps the most exciting” results against late-stage pancreatic cancer his lab has produced in nearly 20 years.

Source study: Nature Biomedical Engineering— Brachytherapy via depot of biopsymer-bound 131I synergies with nanoparticle paclitaxel in therapy-resistant pancreatic tumors

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