In vivo-in vitro clonogenic assays in a human tumour xenograft with a high plating efficiency.

The HT29R human colonic adenocarcinoma cell line grows as locally invasive, mucin-secreting tumours in immunosuppressed mice with a doubling time of 6 days. These tumours may be disaggregated to give single-cell suspensions with plating efficiencies of 25-45% in technically simple in vivo-in vitro cell-survival assays. The effect of maximum tolerated doses of 5-fluorouracil, melphalan and cyclo-phosphamide on in situ growth is only slight. In vivo-in vitro cell-survival assays phosphamide on in situ growth is only slight. In vivo-in vitro cell-survival assays are consistent with these in situ results. The relative ease of experimental manipulation and the high clonogenic efficiency of this tumour make it a useful addition to human tumour xenograft models.