A new antitumor antibiotic FR66973: clonogenic in vitro assessment of activity against human non-small cell lung carcinoma.

We have utilized a human tumor clonogenic assay (HTCA), as a disease-oriented drug screening model of new antitumor drugs, to test the antitumor activity of FR66973 and compared the activity with that of its analogous compound, mitomycin C. The overall in vitro response rate (defined as less than 50% survival of tumor colony forming units) for FR66973 against fresh tumor cells obtained from patients with non-small cell lung carcinoma (NSCLC) was 32%, 50% and 89% at 0.1, 1 and 10 micrograms/ml, respectively, which was superior to that of mitomycin C at the corresponding concentration. Our data suggest that FR66973 is a promising new drug against NSCLC. If phase I toxicities are not prohibitive, FR66973 may also have good activity against NSCLC in clinical phase II trial.