S 3304 is a novel matrix metalloproteinases (MMP) inhibitor specific for MMP-2 and MMP-9. IC50 & Target: MMP-2, MMP-9^[1] In Vitro: S 3304 is a novel D-tryptophan derivative and a potent, orally active, noncytotoxic Matrix metalloproteinases inhibitor (MMPI). Biochemical studies show that S 3304 most potently inhibits the activities of MMP-2 and MMP-9 but does not inhibit MMP-1, MMP-3, or MMP-7 and may, therefore, lack the musculoskeletal side effects seen with nonspecific inhibitors^[1]. In Vivo: In vivo pharmacologic studies have shown that the oral administration of S 3304, at a dose range of 20 to 200 mg/kg, inhibits angiogenesis, artificially induced in mice by the dorsal air-sac method. Similar oral doses of S 3304 result in potent inhibition of metastatic lung colonization of Lewis murine lung carcinoma injected via tail vein and liver metastasis of C-1H human colon cancer implanted into the spleen^[1].