Posted by: Sophie Khatib29 JAN 2013
So, guess what I learned today? That it is becoming more and more possible to treat cancer with a vaccine. Sounds weird, doesn’t it? But it’s true!
Traditional vaccines work by exposing the body to small amounts of inactivated microbes, or small parts of these microbes, and allowing the body to mount an immune response to this particular antigen. Our bodies recognise this antigen, destroy it and then produce a ‘memory’ so that this immune response can be activated quickly if the same antigen were to be recognised again.
Cancer vaccines present the antigen, a section of a protein that the immune system recognises, in order to activate B cells and cytotoxic T cells and in turn, amplify the host’s immune system so that a patient can effectively fight the tumour without the need for a chemotherapeutic agent.
This is an exciting advance in the treatment of cancer because no longer are extremely toxic drugs being developed, but ways to help our own bodies fight cancer cells the way they are developed to. Cancer cells have developed many ways to evade our immune system, such as downregulating the memory T cells and dampening down their response. This has many knock on effects, but by overcoming factors such as this, we can aim to selectively target cancer cells and reduce the havoc that they cause in affected patients.
It has been long since recognised that a tumour is not only made up of tumour cells, but associated cells such as fibroblasts and growth factors to name but a few. There are also many infective agents such as viruses and microbes that are known to be carcinogenic – hence the introduction of the HPV vaccine. With this rapidly increasing knowledge and greater understanding of the factors leading up to tumourigenesis, we are able to develop increasingly specific and safer drugs to treat many cancers.
It may be that cancer vaccines have a place in stopping tumour growth, rather than actually shrinking a tumour, but this may be enough to let a patient lead a normal life and extend their life expectancy. Theoretically, it could have the huge advantage of being able to target cancer cells wherever they occur and so could be used to treat metastasis as well as the primary tumour.
Cancer vaccines rely on the hosts immune system to be functioning well enough before treatment is started which may be a drawback in some circumstances, especially if the patient has just finished a course of chemotherapy and their immune system is temporarily suppressed. Maybe these could be given alongside an agent that stimulates the immune system in a generic fashion to best utilise the pharmacology of the cancer vaccine. Factors such as cytokines or drug molecules could be attached and incorporated into the vaccine to account for a lot of the other pathology caused by a cancer growth. This could then have the ability to increase the levels of useful agents while blocking the undesirable agents such as regulatory T cells.
Could this be a successful leap in the treatment of cancer? I genuinely think so, but until then, we have a lot more to learn about!