[4,5]-Fused-3,6 disubstituted-pydidazines of Formula I are useful for inducing or promoting apoptosis and for arresting uncontrolled neoplastic cell proliferation, and are specifically useful in the arresting and treatment of neoplasia: wherein Y1 and Y2 are independently selected from the group consisting of (CH2)n,—C(X)—NH—,—(CH2)n—C(X)—O—, and X is O or S; R1 is selected from the group consisting of lower alkyl, lower alkenyl, lower alkynyl, and substituted or unsubstituted phenyl, pyridinyl, and the like; R2 is selected from the group consisting of substituted or unsubstituted phenyl, benzyl, pyridinyl, and the like; “A” is a benzene ring fused with the pyridazine ring; and R3 is independently selected in each instance form the group consisting of halogen, lower alkyl, and the like.