So, here we are, with our final discussion of cancer vaccines, which was the 3rd approach in immunotherapy after checkpoint blockade and CAR T cell.
Last post we talked about how a certain type of cancer vaccine wasn’t really a “vaccine” in the true definition of providing protection AGAINST a certain disease. Rather, it was helping to prevent further spread of disease, and in some cases, even treating or fighting the disease.
In this post, we’ll discuss how a cancer vaccine does function to help our own immune system fight against acquisition of disease: in this case, we’ll look at the HPV vaccine, which protects us from cancers caused by the Human Papilloma virus.
The technological approach uses the same theory we have been employing for decades. We modify the actual virus in some way as to make it unable to replicate and spread throughout our body. But we don’t modify that virus to the point that it doesn’t look like itself anymore. In the graphic above, it is the lighter green version of the virus labeled “HPV vaccine,” that has had its gene altered in a way that prevents it from replicating (dark green portion of pink gene).
This modified version of the HPV is then introduced into our system (1) . As it is a foreign substance, an antigen presenting cell (APC) scaven ging the blood encounters this modified virus and processes a piece of it to then present it to a helper T cell (2). The helper T cell then signals the B cell (3) to then turn into activated killer T cells that will take care of the foreign HPV particles (4, 5). Regardless of whether or not the vaccine viruses cause disease is actually irrelevant to the killer T cell.
Now, that process takes care of the modified HPV particles that have been introduced to our bodies in the form of the vaccine. But later, if HPV once again gets into our bodies, what do you think will happen at step 6? Answer, next post!