Monoclonal antibodies are a customized method used to provide targeted therapy against cancer. Ideally, monoclonal antibodies can then attach themselves to specific cell-surface antigen and trigger an immune response selectively against them, without harming any of the surrounding cells.
But how can these artificial antibodies achieve this? And how safe is this?
Antibodies, Acquired Immunity and Targeted Attacks
To better understand how antibodies work, it is necessary to look at the immune system as a whole – and in particular, at the processes behind acquired immunity.
Acquired immunity refers to the body mechanisms meant to defend against a specific infection. They are “acquired” because they usually develop after the initial exposure of the immune system against the infective agent. Acquired antigen-specific responses, which are mediated by the so-called adaptive immune system, tend to be stronger than the antigen non-specific immune responses ofthe innate immune system, which serve as an immediate defense against invading organisms. Conversely, whereas development of specific antibodies by the adaptive immune system only begins after a week or two following the invading infection.
When the body recognizes a foreign virus, bacteria, or other pathogens, it flags it as “non-self”. This initiates a cascade of reactions meant to fight the pathogen by recruiting all defense lines starting with the innate immune system, followed by the adaptive immune system that will also result in development of memory T cells. These can jump start the immediate production of large amounts of antibodies following an additional interaction with the same agent, this time within a few days.
How Are Monoclonal Antibodies Different?
Monoclonal antibodies are artificial antibodies, created to target a specific antigen. They are used to get the body’s immune system to begin actively attacking cancer cells. Monoclonal antibodies will attach themselves to a cancer cell by two arms (Fab2) like a Y-shape with their tail (Fc) sticking out. Activated killer cells with upregulated Fc receptor can attack to the Fc of the monoclonal antibodies, and this will activate an effect known as antibody-dependent cell-mediated cytotoxicity (ADCC) that will induce death to the can cells labeled with the specific monoclonal antibody.
When commercially available monoclonal antibodies exist against antigens expressed on a patient’s cancer cells, such antibodies can result in effective activation of the immune system against the patient’s malignant cells. For example, Rituximab (anti-CD20) is available and very effective for treatment of malignant cells expressing CD20; Herceptin (anti-Her/2 nu) is available for treatment of breast cancer or other cancer cells expressing Her2/neu antigens. Unfortunately, no specific monoclonal antibodies yet exist against the large majority of malignant tumors. As indicated earlier, monoclonal antibodies can also serve to block immune checkpoint inhibitors or to block blood vessels supporting the rapidly growing cancer metastases. Monoclonal antibodies also exist against a large variety of other therapeutic targets.
At Biotherapy International, we often combine the administration of monoclonal antibodies with additional procedures meant to activate the immune system and enhance the effects of ADCC or even for targeting a donor’s immune system cells in an attempt to target killing of patient’s cancer cells by much more effective killer cells reacting against, or rejecting, mismatched cancer cells. This procedure will boost the ability to kill targeted cancer cells, even when a patient’s own lymphocytes fail to eliminate cancer cells.