Immunotherapy against cancer – teach the body’s defense system to attack tumor cells is presented as the new revolution in oncology. But it is not easy. The journal Nature Medicine published an article in which the process is not centered directly fight tumor cells, but in other swarming around and somehow make a shield. The work, scientists have made MD Anderson Cancer Center, University of Texas, is basically to identify peptides that have the ability to bind specifically to these coat cells, myeloid suppressor cells (MDSC).
This is the second part of the test: uniting these peptides with some antibodies. The resulting assembly have called peptibodies. The result is similar to adding an explosive to a key: only act against specific lock. This process can lead the attack on the cells one wish to drop, the MDSC. Thus, tumor cells are exposed to properly educated immune system.
Larry Kwak, who has led the work with Hong Qin, explains: “A decade ago we knew that these cells blocked immune response, but had not been able to turn them off because we had identified the target.”
This search for specific ligands has been instrumental in the work. To find them, the investigators, who did not have an idea of what part of the MDSC were best to act, resorted to a system that could be described as unsubtle: try to blind a number of peptide libraries in the world, to find that attached to the surface of these shields tumor cells. Finally found two which they called G3 and H6. These have an added advantage: not only joined the MDSC who wanted to eliminate, but also do not bind to other cells. That’s important because it allows direct therapy, and key to, if you get to test in humans, side effects.
To verify this idea works, the researchers treated mice with two types of cancer of the thymus with various combinations: a few were given the peptibodies new; others were given other substances that made control. The first thing I saw is that the new molecules treated group reduced its number of MDSC, which was a sign that the idea worked. “This is the first demonstration that we can create antibodies to these cells. It is a radically novel target for immunotherapy,”said Kwak.
The researcher believes that, from now on, you can return to the initial idea of eliciting an immune response to stimulate the immune response against cancer cells. This, so far, had failed. “The key to cancer vaccines take it to another level is designed to combine with immunotherapy tumor micro-environment,” explains Kwak.
But this is not enough. The real goal of the researchers are not the cells that make coat, but verify, once removed the tumors decreased. And this proved it: mice treated with Peptibodies daily for two weeks, and finally, cancers had decreased by half.
The news is encouraging, but incomplete. For example, the authors of the study indicate that they do not know exactly how the MDSC act in its role as protector of tumor cells. However, researchers are already working to extend their findings from mice to humans.