Soravtansine (DM4-SULFO-TBA), a maytansinoid derivative, is an antineoplastic agent. Antibody–maytansinoid conjugates (like Mirvetuximab soravtansine) are in clinical trials for the treatment of various cancers. Thus, Mirvetuximab soravtansine (IMGN853) is an antibody-drug conjugate (ADC) that targets FRα (folate receptor alpha) for tumor-directed delivery of the maytansinoid DM4, a potent agent that induces mitotic arrest by suppressing microtubule dynamics.

Maytansine is an ansamycin antibiotic originally isolated from the Ethiopian shrub Maytenus serrata. Maytansine inhibits the assembly of microtubules by binding to tubulin at or near the vinblastine-binding site, decreases microtubule dynamic instability and cause mitotic arrest in cells. It exerts cytotoxicity against a number of tumor cell lines and inhibits tumor growth in vivo. However, in human clinical trials, maytansine showed a small therapeutic window due to its neurotoxicity and harmful effects on the gastrointestinal tract. The potent cell killing ability of maytansine can be used in a targeted delivery approach, such as an antibody-drug conjugate, for the selective delivery of the drug and destruction of cancer cells.

Ansamitocin P3, a structural analogue of maytansine, was isolated from Nocardia. Structurally maytansine and ansamitocin P3 are polyketide macrolactams differing in the acyl groups at the C3 position. Ansamitocin P-3 inhibited the polymerization of tubulin and depolymerized the once polymerized tubulin. Ansamitocin P3 exerts antitumour properties.