Tyrosine kinase inhibitor (TKI): a drug which blocks the action of a type of protein called a “tyrosine kinase”, which can otherwise be stuck in the “on” position in certain types of cancers. An overactive tyrosine kinase can lead to uncontrolled cell growth (i.e. cancer); a TKI can be used to reduce this undesired activity.

You may remember reading about EGFR on this site. The EGFR protein is a tyrosine kinase, and drugs like gefitinib, erlotinib, and cetuximab are TKIs which target EGFR.

For a list of major TKIs in use in oncology, take a look at the Cancer Research UK website.

Etymologically, the word “tyrosine”, which designates a particular amino acid (the building blocks of proteins), comes from the Greek tyros which means “cheese”. Indeed, this amino acid was apparently easily obtained from old cheese. A “kinase” is a type of enzyme that activates other enzymes. The name comes from the Greek kinein which means “to move”. This is the same root as in “kinetic”, such as “telekinetic”: to move at a distance. If only it were possible….