Antitumor Activity of Taxol Against Human Lung Cancer Cell Lines

In an attempt to predict the clinical activity of taxol in the treatment of lung cancer, we evaluated antitumor activity of the drug using four human small cell lung cancer (SCLC) cell lines, SBC-2, -3, -4, -7, and two non-small cell lung cancer cell lines, ABC-1, EBC-1. In terms of the 50% tumor growth inhibitory concentration (IC50) determined by MTT assay, taxol was significantly superior to adriamycin (ADM), etoposide (ETP), and cisplatin (CDDP). Cytotoxic activity of taxol against SBC-2, -4, and -7, which had been established from the patients with clinically resistant SCLC, was almost comparable to activity against SBC-3, which had been established from a patient with previously untreated SCLC, indicating the effectiveness of taxol for clinically drug-resistant SCLC. The cross-resistance pattern of taxol to ADM, ETP, and CDDP was investigated using ADM-, ETP-, and CDDP-resistant human SCLC sublines, SBC-3/ADM100, SBC-3/ETP, and SBC-3/CDDP. Taxol was proved to be highly cross-resistant to ADM and ETP showing 1420-fold more resistance to SBC-3/ADM100 and 109-fold more resistance to SBC-3/ETP, however the drug did not show cross-resistance to CDDP at all. These results suggest that taxol is a potent drug in the treatment of lung cancer, and that the drug may play a role in salvage chemotherapy for those with resistant SCLC receiving a CDDP-based combination.