Antineoplastic effect of the pyrimido-pyrimidine derivative: RA 233.

A number of normal and neoplastic human cell lines in culture were studied by cell count and 3H thymidine incorporation for growth inhibitory effect by the pyrimido-pyrimidine derivative RA-233 (mopidamole). There was more inhibition when the drug was added to the culture in the lag phase than in the logarithmic growth phase. There was more inhibition (particularly at low doses) of the neoplastic cell lines than of the non-neoplastic cell lines.