Lorvotuzumab mertansine (IMGN901) is an antibody-drug conjugate. It comprises the CD56-binding antibody, lorvotuzumab (huN901), with a maytansinoid cell-killing agent, DM1, attached using a disulfide linker, SPP. (When DM1 is attached to an antibody with the SPP linker, it is mertansine; when it is attached with the thioether linker, SMCC, it is emtansine.) '-mexi-' (melanoma): Ecromeximab§ Lorvotuzumab mertansine (IMGN901) is an antibody-drug conjugate. It comprises the CD56-binding antibody, lorvotuzumab (huN901), with a maytansinoid cell-killing agent, DM1, attached using a disulfide linker, SPP. (When DM1 is attached to an antibody with the SPP linker, it is mertansine; when it is attached with the thioether linker, SMCC, it is emtansine.) Lorvotuzumab mertansine is an experimental agent created for the treatment of CD56 positive cancers (e.g. small-cell lung cancer, ovarian cancer). It has been granted Orphan drug status for Merkel cell carcinoma. It has reported encouraging Phase II results for small-cell lung cancer.