Bcl-xL/Bcl-2 binding inhibitors useful in the treatment of unwanted proliferating cells, including cancers and precancers, in subjects in need of such treatment. Also provided are methods of treating a subject having unwanted proliferating cells comprising administering a therapeutically effective amount of a Bcl-xL/Bcl-2 binding inhibitor described herein to a subject in need of such treatment. Also provided are methods of preventing the proliferation of unwanted proliferating cells, such as cancers and precancers, in a subject comprising the step of administering a therapeutically effective amount of a Bcl-xL/Bcl-2 binding inhibitor described herein to a subject at risk of developing a condition characterized by unwanted proliferating cells.