We may be headed towards an entirely new era of cancer treatment.
“That means we can use 50 times less of the drug and still get the same results,” says Elena Batrakova, associate professor in the Eshelman School of Pharmacy at the University of North Carolina at Chapel Hill.
“That matters because we may eventually be able to treat patients with smaller and more accurate doses of powerful chemotherapy drugs resulting in more effective treatment with fewer and milder side effects,” Batrakova continued.
It’s particularly exciting that the scientists got these results without testing out any new chemo drugs or experimental medications — they simply figured out a new way to package and deliver chemotherapy medication that’s already been tested and shown to work in humans.
This new delivery system relies on exosomes, which are little spheres harvested from the white blood cells that protect the body against infection. A new chemo delivery system is crucial since the existing method involves pumping toxic medication into large areas of the body, which can end up killing off other healthy tissue as it kills off the cancer cells.
There have been attempts in the past decade to use plastic-based nanoparticles as a way to deliver drugs, but the body recognizes the substance as foreign which creates a tough obstacle for researchers. Exosomes, however, are made of the same material as cell embranes so they don’t pose the same issue.
“Exosomes are engineered by nature to be the perfect delivery vehicles,” says Batrakova. “By using exosomes from white blood cells, we wrap the medicine in an invisibility cloak that hides it from the immune system. We don’t know exactly how they do it, but the exosomes swarm the cancer cells, completely bypassing any drug resistance they may have and delivering their payload.”
In order to test out the new system, the researchers used a chemotherapy drug called paclitaxel. Paclitaxel is already used by doctors to effectively treat breast, lung, and pancreatic cancers, but it comes with a slew of severe side effects like hair loss, diarrhea, and muscle cramping.
The researchers took exosomes from mice and loaded them with paclitaxel before unleashing the medicine-filled exosomes in a petri dish containing drug-resistant cancer cells. Amazingly, the results revealed that 50 times less of the paclitaxel medicine was needed to kill the cancer cells. The researchers called their treatment exoPXT.
Not only did the exosomes kill the drug-resistant cancer cells, but they also proved to be useful in seeking out and marking cancer cells. The researchers came to this finding after testing dye-filled exosomes in mice with drug-resistant lung cancer and believe exosomes could also have potential as highly accurate diagnostic tools.
"Accurately mapping the extent of tumors in the lungs is one of the biggest challenges in treating lung-cancer patients," said Batrakova. "Our results show how powerful exosomes can be as both a therapeutic and a diagnostic."
The research still has a ways to go in the future before it can be trialled in humans, but the potential is thrilling. Hopefully exosomes will help improve both diagnostic methods and cancer treatment.