Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: Promilla on 23/02/2014 12:01:35
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Hello!
So basically I looked at different cancer therapies, and found the idea of monoclonal antibody therapy for cancer. As far as I understand it is about boosting individual's immune system, so that it can recognize and fight cancer better. The thing I don't understand is that certain drugs (e.g. rituximab, alentuzamab) target B and T lymphocytes. according to Wikipedia, these cells "play a central role in cell-mediated immunity". If these drugs prevent these lymphocytes from working, shouldn't the immune response be suppressed? That's my reasoning, and I don't understand how would they evoke the positive action. Any thoughts?
Cheers,
Promilla
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It is thought that most cancers are kept under control by the immune system and/or anti-cancer genes, so we never notice them.
It is theoretically possible to train the immune system to recognise a new antigen - to effectively vaccinate the body against the cancer.
But the cancers that get big enough for us to notice are those that have managed to to evade the immune system - they are effectively considered "self", and are not attacked by our immune systems.
Monoclonal antibodies (http://en.wikipedia.org/wiki/Monoclonal_antibody_therapy) act like human antibodies, and can be engineered to lock onto almost any chemical visible on the surface of a cell.
Most of these antibody therapies seem to be designed to find cancer cells directly, rather than first training the immune system. When the antibody marks a cancer cell, other parts of the immune system will then attack the marked cell. Some types of antibody therapies can carry a toxic payload (either chemical or radioactive), which they attach to the cancer cell to kill it - and perhaps nearby cells in the cancer.
I see that rituximab is used to treat Non-Hodgkins lymphoma, which is an uncontrolled growth of lymphocytes. In this case, the diseased lymphocytes are part of the problem, rather than part of the cure. This monoclonal antibody targets the CD20 protein which spans the cell wall of lymphocytes.
A single cancer can exhibit a wide variety of mutations, and the uncontrolled growth of cancer cells can be fueled by a wide number of factors. Your oncologist must identify which factor(s) is most important in your particular cancer, and select an available treatment which targets this weakness.
There is always a risk that after eliminating all cells exhibiting a particular antigen, there may be other cancer cells present which do not exhibit this antigen. This is why some combination of surgery, radiation, and chemotherapy are often combined in order to hit as many as possible of the potentially cancerous cells.
There is ongoing research into genetic sequencing of cancers, which has sometimes identified an off-the-shelf medication to which a particular cancer is susceptible. While the cost of gene sequencing is dropping rapidly, unfortunately the cost of interpreting genetic anomalies remains extremely high; this is a skill which is thinly spread in the research community.