Effect of various drugs on the tumor-necrotizing activity of several chemical agents in mice.

The mechanism of action of some antitumor agents (3-5) has been investigated in recent years by studying their effects in combination with other agents that may be antagonistic or synergistic. Previous work1 in this laboratory showed that the tumor-necrotizing action of the bacterial polysaccharide from Serratia marcescens and of some other tumor-necrotizing agents was reduced by pre-administration of cortisone, of dibenamine, and of several other sympatholytic drugs. These phenomena were further investigated with several tumor-necrotizing agents, together with several modifying drugs of different phar macological nature, in an attempt to throw light on the mechanism of action of the antitumor agents. This paper presents the effects of corti sone, atropine, urethan, two barbiturates, and five sympatholytic drugs on the tumor-necrotizing activity of the following agents: a bacterial poly saccharide, a derivative of podophyllotoxin, histamine, pitressin, serotonin, amphetamine, and i suprel.