S-methyl DM1 is primarily utilized in the field of targeted cancer therapy, particularly in the development of antibody-drug conjugates (ADCs). It serves as a potent cytotoxic agent that is linked to monoclonal antibodies, which are designed to specifically recognize and bind to antigens on the surface of cancer cells. Once the ADC binds to the target cell, it is internalized, and S-methyl DM1 is released, leading to the inhibition of microtubule assembly. This disruption of microtubule dynamics ultimately induces cell cycle arrest and apoptosis in the cancer cells, thereby providing a targeted approach to minimize damage to healthy tissues. Its high potency and specificity make it a valuable component in the treatment of various cancers, including breast cancer and hematologic malignancies.