Novel somatostatin analogs with tyrosine kinase inhibitory and antitumor activity.

A series of new somatostatin analogs have been developed and tested for antitumor activity. Some analogs strongly inhibited tyrosine kinase activity of human colon tumor cells and this activity correlated well with their antiproliferative effect, but did not correlate with GH release inhibition. The best analogs strongly inhibited the metastasis formation in the Lewis lung metastasis model in mice. On the basis of these in vitro and in vivo data we were able to select one analog with strong tyrosine kinase inhibitory and antitumor activity, without inhibiting growth hormone release.