Every once in a while I see a paper that makes me sit up and say “Wow”. They are rare, but when they happen they let us really see the progress that is being made. This week one of those papers was published in the journal Science Translational Medicine.
The study built on recent work that is focused on the immune system, and the potential that we can make it attack a cancer (something which doesn’t normally happen). There has already been some excellent results in this field in human trials, but this study took the work in a slightly different direction. The work was carried out in mice, so is still at an early stage, but the a small clinical trial is starting this month, and that will tell us how optimistic we should be.
What these scientists have developed is a clever way to activate the immune cells specifically within the tumour by injecting it with a tiny amount of DNA and another compound. When they did this they found that the tumours shrank and disappeared. It gets better though: they tried the same approach in breast cancer, colon cancer, and melanoma, (three very different cancer types) and saw the same effect across the board.
Perhaps the most exciting part of the work was that when they injected one tumour, the immune system attacked all the tumours in that mouse, which means that this is an approach that may work in late stage patients, who are typically very difficult to treat.
The technique itself makes use of a trick that is already used in patients: by injecting a tiny amount of DNA into a patient’s cancer, we can improve responses to chemotherapy. It works by making the immune cells in the vicinity express a marker on their surface, which has the effect of priming them for action. The insight that these scientists had, was that by using a second compound to recognize this marker, they could activate the cells to attack the tumour. Because the injection is directly into the cancer, only the immune cells that recognize the tumour are activated. Some of these then leave the original tumour and attack other ones throughout the body.
This approach proved to be remarkably effective. In total, the scientists treated 90 animals with the therapy. Eighty seven of those were cured. Additionally, in some of the mice the tumours became resistant and began to grow again, which is typically what happens in human patients. However, if they then injected this new tumour with the therapy, they saw the same shrinking as before, which is extremely encouraging.
It was a startlingly successful study, but as I mentioned above, this work was in mice, so we can’t be sure the results will translate to humans. It’s possible that there will be toxicity to humans, or that there will be issues with stimulating the immune system like this, but it is also very possible that we will see some real benefits of this therapy.
It’s an exciting time to be in cancer research!