Our whole immune system works because of a most important feature, and that is the ability to distinguish a self entity from a non-self entity. That means there is a”loophole” with a cancer cell, because a cancer cell was once a normal cell. So, herein lies the basis of WHY cancer cells might have the ability to evade our immune system: the cancer cells are still regarded as “self,” to a certain extent.
An activated T cell can be likened to the Looney Tunes’ Tasmanian devil: when he gets going, he is out of control, voracious and destructive to everything in his path. But clearly that doesn’t happen in a normal scenario with T cells. Otherwise, the cells invaded by bacteria/viruses/other foreign particles would be under attack ALL the time, as once the T cells are triggered, they will keep attacking. Instead, the T cells themselves have internal systems that stop them from attacking everything in sight, that are triggered by other cells through receptors. These can be analogous to the “breaks” on a car, except that the brake system is activated externally.
So, all these built-in programs of the immune system are targeted in Immunotherapy, and are outlined in the graphic as Approaches 1, 2 and 3.
Next post, which will be September 22, we’ll tackle Approach 1: Checkpoint inhibitors.