What is an antibody?Antibodies are proteins produced by white blood cells that are termed plasma cells. Antibodies are found in blood of vertebrates, and are used by the immune system to identify and neutralize foreign objects. An antibody is constructed from basic structural units called the heavy chain and the light chain. Each antibody is typically composed of two heavy chains and two light chains; however, dimeric and pentameric antibodies also exist in the immune repertoire.
Antibodies function by interacting with specific targets (antigens). These antigens can be proteins, carbohydrates, or even DNA or RNA. The interaction between the antibody and the antigen is governed by the antigen binding region on the antibody and the specific antigen epitope recognized by the antigen binding region.
Although every antibody is constant in its make-up of heavy chains and light chains, the antigen binding region is hypervariable. The variability of the antigen binding region allows for millions of possible antigen binding regions to exist, each with its own unique epitopic specificity. The interaction between the antigen binding region of the antibody and the epitope of the antigen is highly specific. The specificity is such that an antibody will be able to identify and bind only their unique epitope in the midst of millions of different epitopes -- even if this mixture of epitopes are on the same target antigen.
Why antibodies?Antibodies are uniquely suited for use as therapeutic agents for cancer treatment:
In essence, antibodies are pre-existing tools: part of the existing immune repertoire. The use of a species matched antibody therapeutic should cause minimal immune side effects.
An antibody can defeat a cancer cell in multiple ways:
1. An antibody can block a highly specific cancer cell function, leading to cancer cell death.
2. An antibody can interrupt a complex of protein interactions, cutting off the ability of the cancer cell to communicate with other cancer cells and its surroundings, leading to growth arrest and eventual death.
3. An antibody can cause a change to the environment around the tumor, causing the cancer cell to starve to death.
4. An antibody can enhance the innate immune system, aiding the already highly efficient immune killer cells to discover the cancer cell and eradicate the tumor.
5. An antibody is highly stable in the body and in circulation, allowing more of the drug to act on the targeted cancer cells before being expelled or destroyed.