Activity of 4'-0-tetrahydropyranyladriamycin hydrochloride (THP-ADM) in a human tumor cloning system.

4'-0-tetrahydropyranyladriamycin hydrochloride (THP-ADM) is a new anthracycline derivative. The antitumor activity of THP-ADM was tested on 51 human tumor samples representing ten different tumor types in in vitro colony assay method. Tested tumors were: 26 cases of ovarian cancer, 8 cases of breast cancer, 6 cases of colorectal cancer, 3 cases of endometrial cancer, 2 cases each with gastric cancer and sarcoma, and another 4 cases. An in vitro colony assay was done in soft agar as described by Hamburger & Salmon. The criteria for in vitro sensitivity was defined as a 70 percent or greater reduction in the number of colonies after a 1-h exposure to drugs. The selected concentrations of THP-ADM for assay were 0.05, 0.5, and 1.0 micrograms/ml. The sensitivity rates for THP-ADM in each dose were: 0.05 micrograms/ml (7/19, 37%), 0.5 micrograms/ml (10/51, 20%), and 1.0 micrograms/ml (12/19, 63%). In vitro sensitivity of adriamycin (0.04 micrograms/ml) was simultaneously tested in 49 cancer patients. Five out of 25 ovarian cancer patients (20%) showed responses to adriamycin and an overall response rate was 12% (6/49). These data indicate that THP-ADM has an antitumor activity against various cancers and it is comparable to that of adriamycin.