An adriamycin-resistant subline is more sensitive than the parent human small cell lung cancer cell line to lonidamine.

Lonidamine, a unique new type of anticancer agent, has been shown to exert marginal activity in patients with resistant small cell lung cancer. We have assessed cytotoxic activity using seven human small cell lung cancer cell lines and the drug resistant small cell lung cancer sublines, Adriamycin-resistant SBC-3/ADM100, etoposide-resistant SBC-3/ETP and cisplatin-resistant SBC-3/CDDP. Although lonidamine had only a minimal activity in seven human small cell lung cancer cell lines, SBC-3/ADM100 cells were more sensitive to lonidamine than the parent SBC-3 cells to a 1.6-fold extent in terms of IC50. SBC-3/CDDP and SBC-3/ETP had no cross-resistance to lonidamine at all. These observations may be of potential clinical significance in treating small cell lung cancer.