a method of treatment of a host with a cellular proliferative disease , comprising contacting the host with a cephalotaxine and an antiproliferative agent , each in an amount sufficient to modulate said cellular proliferative disease , is described . in some embodiments , the cephalotaxine comprises homoharringtonine butanediocate ester ). antiproliferative agents of the invention comprise alkylating agents , intercalating agents , metal coordination complexes , pyrimidine nucleosides , purine nucleosides , inhibitors of nucleic acid associated enzymes and proteins , and agents affecting structural proteins and cytoplasmic enzymes .