TGN1412, also known as CD28, contains a highly unusual property for an antibody medicine: instead of blocking a cell's reaction, it causes a stimulation. For this reason, even a small dose might provoke a cascading, catastrophic calamity. Antibodies stay in the body for months. They can't easily be removed, even through multiple blood transfusions. Experimental drugs are typically tested on laboratory tissue samples or animals before they're considered "safe enough" to be injected into humans. TGN1422, on the other hand, was monoclonal antibody, designed to target a specifically humanoid proteinRead more .