A series of pyrimido-pyrimidine derivatives were tested for their effe
ct on membrane fluidity-deformability of human red blood cells and on
human platelet aggregation. These agents were also tested for their in
tracellular cAMP increasing activity and proliferation inhibitory acti
vity in neoplastic cells. The order of activity was established and cl
inical implications discussed. Several derivatives are under study as
antineoplastic agents.