Briciclib, also known as ON 013105 or ON 014185, is a benzyl styryl sulfone analog, and a disodium phosphate ester prodrug of ON 013100, with potential antineoplastic activity. Upon hydrolysis, cyclin D modulator ON 013105 is converted to ON 013100, which blocks cyclin D mRNA translation and decreases protein expression of cyclin D. This may induce cell cycle arrest and apoptosis in cancer cells overexpressing cyclin D and eventually decrease tumor cell proliferation. This agent may exhibit synergistic antitumor activity in combination with other chemotherapeutic agents.