Researchers have been able to effectively vaccinate a mouse against cancer, by using a combination of gold nanoparticles and an FDA-approved immunotherapy drug.
The treatment was achieved through the combination of two separate therapies. The first of these uses a technique that is currently being explored by many different research groups, using gold nanoparticles through something known as “photothermal” therapy.
This involves injecting gold nanoparticles into the cancerous tissue and then hitting them with lasers. The nanoparticles then heat up to such a degree that they begin to kill the tumor in situ. The gold nanoparticles are of particular interest because they preferentially associate with tumors as their blood vessels are particularly leaky.
For this latest study, the researchers have developed a novel new shape for the nanoparticles with multiple spikes called gold nanostars. “The nanostar spikes work like lightning rods, concentrating the electromagnetic energy at their tips,” explained Tuan Vo-Dinh, who co-authored the paper in Scientific Reports.
The second immunotherapy involves a newly developed drug that blocks the action of a particular molecule known as PD-L1. Produced by tumor cells, PDL-1 effectively disables T-cells, which are your body’s main way of fighting cancer, thus allowing the tumor to grow and spread unhindered. The drug itself has already been cleared by the FDA and is in early clinical use.
The researchers carried out a series of experiments in which they injected bladder cancer cells into both hind legs of mice, and waited for the tumors to grow. They were then able to test different therapies but only on one of the legs.
Those with no treatment quickly succumbed to the cancer, as did mice that only received the gold nonstars, because they were not able to kill the cancer in the leg that was left untreated. Some of those that received only the immunotherapy drug did survive for a while, but then died. Yet when it came to the mice that had been given both treatments, the mice managed to survive for much longer.
“When a tumor dies, it releases particles that trigger the immune system to attack the remnants,” said Vo-Dinh. “By destroying the primary tumor [with the nanostars], we activated the immune system against the remaining cancerous cells, and the immunotherapy prevented them from hiding.”
They even found that one of the mice was given some form of immunity to the cancer. A month after it had cleared the tumors, the researchers injected the rodent with more cancerous cells, and the animal's own immune system managed to fight it off by itself.
This study was only small and on mice, which means that its results are limited and very preliminary. Either way, it shows that researchers are trying many new avenues to eliminate cancer.