Assays of drug sensitivity for cells from human tumours: in vitro and in vivo tests on a xenografted tumour.

A human tumour which grows as a xenograft in immune-suppressed mice and forms colonies in vitro has been used to test the correlation between 2 methods of exposure of human tumour cells to chemotherapeutic agents. In vivo exposure to drugs was achieved by injection of tumour-bearing mice with each of 8 cytotoxic agents. For the in vitro exposure, cell suspensions were incubated for 1 h with the same series of drugs. The survival of tumour clonogenic cells was assayed in vitro after either treatment or dose-response curves were obtained. The 8 drugs were ranked according to their in vivo effect at doses equitoxic to mice, and according to their in vitro effect at concentrations designed to approximate to levels of drugs in human plasma. The ranks for in vivo and in vitro exposure correlated well.