Wednesday, August 20, 2008

Blinatumomab - BiTE antibodies

Just heard about this particular cancer therapeutic on the Science Magazine Podcast (link to mp3 of episode), called Blinatumomab. It is made by a US company called Micromet, who has a patent on this class of engineered proteins called BiTE antibodies. These proteins are a single polypeptide containing the variable regions from two antibodies with different specificities. BiTE stands for bi-specific T-cell engagers and are named such becuause one of the antibodies specificities is for CD3, a compentent of the T-cell receptor, while the other is specific for a tumour specific antigen. The idea is that these molecules attach to cells expressing the tumour antigen and then recuit Tcells (nonspecifically as they all have CD3) to kill these target cells. The mechanism of exactly how this works eludes me as the T-cells are not being activated in the conventional mechanism that I understand. However it is therefore suggested that the cancer cells would be more suseptable to this mechanism as they have managed so far to escape conventional immune control.
Check out the Micromet company backgrounder on BiTE antibodies. (pdf)
What makes these molecules Science magazine worthy is that Blinatumomab has demonstrated some impressive efficacy against non–Hodgkin's B cell lymphoma (NHL). Check out the publication from Science.