A selective inhibitor of the anti-apoptotic protein B-cell lymphoma 2 (Bcl-2), with potential pro-apoptotic and antineoplastic activities. Upon administration, Bcl-2 inhibitor BCL201 binds to and inhibits the activity of Bcl-2. This restores apoptotic processes in tumor cells. Bcl-2 protein is overexpressed in many cancers and plays an important role in the negative regulation of apoptosis; its expression is associated with increased drug resistance and tumor cell survival.