Lith-O-Asp is a sialytransferase (ST) inhibitor,(IC50s:12-37 μM).

The results indicate that Lith-O-Asp reduces the activity of both a-2,3- and a-2,6-sialyltransferases, consequently inhibiting the transfer of sialic acids to target glycoproteins[1]. Despite showing no significant growth inhibition effect on various cancer cell lines at doses of 10, 30, and 60 μM, in vitro assays reveal Lith-O-Asp's capability to suppress the activities of ST3Gal I, ST3Gal III, and ST6GalI, with IC50 values ranging from 12 to 37 μM. Furthermore, flow cytometry analysis demonstrates a marked decrease in the expression of cell surface a-2,3- and a-2,6-sialylated antigens.

In lung tissues of mice treated with DMSO and observed using the IVIS in vivo imaging system, a significant presence of secondary metastatic cancer cells was noted 26 days post-fat pad inoculation. Conversely, mice treated with Lith-O-Asp exhibited a reduction in lung metastases, with only 3 of 8 mice showing any metastasis compared to all DMSO-treated mice. The average number of tumor nodules per mouse in the DMSO group was 11±9, while in the Lith-O-Asp group, it was significantly lower at 2±4 nodules. Additionally, 4T1-Luc illumination signals, indicating tumor presence, were markedly stronger in the DMSO control group than in the Lith-O-Asp-treated group on days 7 and 9[1].