Effects of 5-(2-chlorobenzyl)-4,5,6,7-tetrahydrothieno[3,2-c]pyridine hydrochloride (Ticlopidine), a platelet aggregation inhibitor, on blood-borne metastasis.

A new platelet aggregation inhibitor compound, 5-(2-chlorobenzyl-4,5,6,7-tetrahydrothieno[3,2-C]pyridine hydrochloride (ticlopidine), was examined for its inhibitory effects on blood-borne metastasis using three different rodent tumors (B16 melanoma, Lewis lung carcinoma, and rat ascites hepatoma, AH130). Ticlopidine was administered p.o. to the rodents. It inhibited the aggregation of platelets induced by adenosine diphosphate, thrombin, crude extract of AH130, and viable AH130 and B16 melanoma cells and also resulted in a significant decrease of pulmonary metastasis induced by i.v. injection of B16 melanoma and AH130. Spontaneous pulmonary metastasis of Lewis lung carcinoma was also inhibited by p.o. administration of ticlopidine. This new compound may be a useful agent for inhibiting platelet aggregation caused by various agents and for suppressing hematogenous pulmonary metastasis.