S263

S263 is a potent and selective small molecule inhibitor of the Myeloid Cell Leukemia-1 (Mcl-1) protein, a member of the Bcl-2 family of anti-apoptotic proteins. Developed by Servier, S263 functions by binding to the BH3-binding groove of Mcl-1, thereby preventing its interaction with pro-apoptotic proteins such as Bak and Bax. This inhibition triggers the intrinsic pathway of apoptosis in cancer cells that are dependent on Mcl-1 for survival. S263 has been primarily investigated in preclinical models of hematological malignancies, including multiple myeloma, acute myeloid leukemia (AML), and various lymphomas, where Mcl-1 is frequently overexpressed and serves as a key resistance factor to conventional therapies and other Bcl-2 inhibitors like venetoclax.