In vitro antitumor activity of teniposide against carcinoma of the lung in human tumor clonogenic assay.

The antitumor activity of teniposide (VM26) on carcinoma of the lung was tested by comparing it with its congener, etoposide (VP16) in an in vitro soft agar clonogenic assay system (HTCA). Of 56 tumor biopsies placed in culture, 40 tumors were evaluable for drug sensitivity information (i.e., greater than or equal to 30 colonies in the control plate). The overall in vitro response rate (defined as less than or equal to 50% survival of TCFU) at the standard dose (10% peak plasma concentration) was 35%, which is higher than that of VP16 (28%). In cell lines derived from human carcinoma of the lung, VM26 showed 50% inhibition against colony formation of PC-7 cells at 0.45 microgram/ml which is less than that of VP16. A superior antitumor activity of VM26 on PC-9 cells was also observed. VM26 was observed to act faster than VP16 thus indicating its possible superior antitumor activity in vivo.