Honn et al. [Science (Wash. DC), 212: 1270, 1981] have recently reported a 93% reduction in the development of
metastases of B16 amelanotic
tumor cells given i.v. following a single dose of
prostacyclin (PGI2) (100 micrograms) and
theophylline (100 micrograms) 30 min prior to the injection of
tumor cells. We have been unable to reduce pulmonary
metastases induced by the i.v. injection of CT26
colon adenocarcinoma,
Lewis lung carcinoma, or B16
amelanotic melanoma cells with a similar regimen. Thus, PGI2 and
theophylline given prior to injection of
tumor cells and 2 hr postinjection had no effect on the number or volume of pulmonary
tumor nodules for CT26 cells, using 15 experimental and 14 control animals; Lewis lung cells, using 14 experimental and 13 control animals; or B16 amelanotic cells, using 26 experimental and 12 control animals. The PGI2 used was shown to be active in vitro, inhibiting
tumor-induced platelet aggregation by all three
tumors at 10(-9)M; and in vivo by inhibition of Lewis lung-induced
thrombocytopenia at 1 hr, using 100 micrograms PGI2 prior to the injection of
tumor cells.