Preferential inhibition of tumors by drug depressing DNA polymerases.

Abstract

To the Editor.— In chemical sensitivity tests on hundreds of human cancers and in radioactive tracer studies on more than 80 human cancers, one or more sulfhydryl (SH) inhibitors have shown greater activity against tumors than against normal tissues. 1,2 The clinically useful SH inhibitors have now been found to depress DNA polymerases in vitro, with greater effect against RNA-dependent DNA-polymerase activity than against DNA-dependent DNA-polymerase activity. Clinically, SH inhibitors, selected according to individual patient sensitivity tests, have led to regression of a wide range of human tumors, without apparent interference with wound healing or injury to hematologic status. In two series totaling over 120 patients, the majority of patients whose cancers could be tested obtained objective regression from the SH inhibitors alone, or combined with other selected drugs. Randomized experiments in Japan with the Kondo sensitivity test 3 similarly have shown promising clinical results for patients receiving antitumor agents