Inhibition of Pulmonary Metastases and Tumor Cell Invasion in Experimental Tumors by Sodium d‐Glucaro‐δ‐lactam (ND2001)

Sodium d‐glucaro‐δ‐lactam (ND2001) inhibited spontaneous pulmonary metastases of the highly metastatic B16 melanoma variant with a maximal inhibition rate of 99.5%, and 6 of 7 animals remained metastasis‐free. Likewise, ND2001 inhibited the spontaneous pulmonary metastases of both Lewis lung carcinoma (3LL) with a rate of 98.0% (3 of 5 animals remaining metastasis‐free) and rat KDH‐8 liver carcinoma with a rate of 82.5% (3 of 7 animals remaining metastasis‐free), although it was unable to inhibit the metastases of mouse BMT‐11 fibrosarcoma and rat SST‐2 breast carcinoma. Pretreatment with ND2001 in vitro inhibited the pulmonary metastases of the B16 variant and 3LL cells, which indicates direct action upon the cancer cells. When the invasive activity of cancer cells was measured by the Boyden chamber method, the number of invading B16 variant or 3LL cells was reduced with maximal inhibition rates of 93.0% or 89.9%, respectively, but pretreatment with ND2001 failed to reduce the invasive activity of BMT‐11 or SST‐2 cells. ND2001 showed neither cytocidal nor antitumor activity. These results suggest that ND2001 inhibited pulmonary metastases at the invasive step into the basement membrane by directly changing some property of the tumor cells.