Effects of a somatostatin analogue (SMS 201-995) on the growth and development of hepatic tumour derived by intraportal injection of Walker cells in the rat.

Administration of a long active analogue of somatostatin, SMS 201-995 (2 micrograms subcutaneously twice a day) for 3 weeks after intraportal administration of Walker cells significantly inhibited their growth and development in the liver. This was not due to a direct cytotoxic effect of the analogue on Walker cells whose growth was stimulated in vitro. Furthermore, SMS 201-995 had no effect on the growth of Walker cells implanted into the thigh of rats suggesting that the inhibitory action of the analogue could be confined to tumour cells growing in the liver. Further studies suggested that the inhibitory effect of SMS 201-995 on the growth of Walker cells in the liver could be related to a marked stimulation of the hepatic reticuloendothelial system, by a reduction in portal venous flow in the early stages of treatment or by a combination of these effects. Further studies are required to delineate more precisely the mechanism whereby SMS 201-995 inhibits the growth of hepatic tumour derived from intraportal administration of Walker cells.