In vitro cytotoxic drug sensitivity testing of human tumour xenografts grown as multicellular tumour spheroids.

Tumour cells from 7 patients with ovarian carcinoma and from 22 different human tumour xenografts representing a wide range of histological sub-types have been examined for multicellular spheroid forming ability. Spheroid formation was limited to cells derived from xenografts. Of the 22 lines tested, 5 formed spheroids capable of growth in isolation. There was no clear relationship between histological type and spheroid-forming ability. The plating efficiency of tumour cells obtained from spheroids was always greater than for the cells obtained from the dissociated tumour of origin and was in some cases as much as 6-fold greater. Spheroid growth was nearly exponential for 4 cell lines. Volume growth delay was used to investigate the activity of melphalan, adriamycin, the Vinca alkaloids, CCNU and cisplatin. Differences between lines in drug response broadly reflected patient and in vivo xenograft response.