What is "mertansine"

n. A cytotoxic agent and maytansinoid.

Mertansine, also called DM1 (and in some of its forms emtansine), is a thiol-containing maytansinoid that for therapeutic purposes is attached to a monoclonal antibody through reaction of the thiol group with a linker structure to create an antibody-drug conjugate (ADC).

ADCs with this design include trastuzumab emtansine, lorvotuzumab mertansine, and cantuzumab mertansine. Some are still experimental; others are in regular clinical use.