A maytansinoid is a chemical derivative of maytansine. A maytansinoid is a chemical derivative of maytansine. Some are being investigated as the cytotoxic component of antibody-drug conjugates. Anticancer properties of maytansinoids have been attributed to their ability to disrupt microtubule function. The maytansinoid emtansine (DM1), for example, binds at the ends of microtubules and thereby suppresses their dynamic instability