Because current treatments aren’t specifically targeted to cancer cells, only 0.01 per cent of chemotherapy drugs actually reach the tumour and its diseased cells.

“I’m working on figuring out how we can deliver more of the chemotherapy drugs to the tumour and less to healthy cells,” said Sofie Snipstad, who recently graduated from the Department of Physics at the Norwegian University of Science and Technology (NTNU). Last year, she won a Norwegian science communication competition for PhD candidates called Researcher Grand Prix. When she made her winning presentation about her research during the competition finals, she was in the middle of testing a new method of cancer treatment on mice.

Now her research has shown that the method can cure cancer in mice.

Her study titled, "Ultrasound Improves the Delivery and Therapeutic Effect of Nanoparticle-Stabilized Microbubbles in Breast Cancer Xenografts," was published in the journal Ultrasound in Medicine and Biology.

Snipstad’s method targets cancerous tumours with chemotherapy so that more of the drug reaches cancer cells while protecting healthy cells. The experiments were conducted in mice with an aggressive breast cancer type.

Researchers undertook many laboratory experiments before conducting their tests with mice - which were the first actual tests using this delivery method for chemotherapy. In addition to causing the tumours to disappear during treatment, the cancer has not returned in the trial animals.

“This is an exciting technology that has shown very promising results. That the first results from our tests in mice are so good, and that the medicine does such a good job right from the start is very promising,” Snipstad said. Instead of being injected straight into the bloodstream and transported randomly to both sick and healthy cells, the chemotherapy medicine is encapsulated in nanoparticles. When nanoparticles containing the cancer drugs are injected into the bloodstream, the nanoparticles are so large that they remain in the blood vessels in most types of healthy tissues. This prevents the chemotherapy from harming healthy cells.

Blood vessels in the tumour, however, have porous walls, so that the nanoparticles containing the chemotherapy can work their way into the cancerous cells.

“My research shows that this method allows us to supply 100 times more chemotherapy to the tumour compared to chemotherapy alone. That’s good,” Snipstad said.

However, the nanoparticles can only reach cells that are closest to the blood vessels that carry the drug-laden particles, she said. That means that cancer cells that are far from the blood vessels that supply the tumour do not get the chemotherapy drugs.

“For the treatment to be effective, it has to reach all parts of the tumour. So our nanoparticles need help to deliver the medicine,” she said.The nanoparticles used by Snipstad and her research team were developed at SINTEF in Trondheim. The particles are unusual because they can form small bubbles. The nanoparticles are in the surface of the bubbles.

The bubbles that contain the chemotherapy-laden nanoparticles are injected into the bloodstream. Ultrasound is then applied to the tumour. The ultrasound causes the bubbles to vibrate and eventually burst, so that the nanoparticles are released. The vibrations also massage the blood vessels and tissues to make them more porous. This helps push the nanoparticles further into the cancerous tumour, instead of only reaching the cancer cells closest to the blood vessels.

“By using ultrasound to transport the chemotherapy-laden nanoparticles into the tumours, our research on mice has shown that we can deliver about 250 times more of the drug to the tumour compared to just injecting chemotherapy into the bloodstream alone,” she said.