Clonogenic cell survival curves for human melanoma xenografts using agar diffusion chamber and lung colony assays.

Studies using 2 different cloning assays to grow colonies and measure cell survival after treatment of human melanoma xenografts are reported and reviewed. Clonogenic cell survival curves were constructed for 5 melanoma xenografts with a clinically relevant range of drugs, using a soft agar diffusion chamber assay. Cells in colonies were similar to human melanoma cells in morphology, histochemistry, ultrastructure and antigenicity and xenograft tumours could be grown from the colonies. The survival curves were compatible with the known clinical patterns of response of malignant melanoma. The sensitivities of the xenografts correlated with the response of the same tumour in the patient when assessable. In 2 xenograft lines, it proved possible to grow colonies in the lungs of immune deprived mice. Studies of drug sensitivity using this lung colony assay agreed closely with the soft agar assay. It is concluded that the measurement of clonogenic cell survival can be a valuable endpoint in the assessment of the response of some xenograft tumours to therapy. The agreement between the 2 assays in which colonies were grown under widely different conditions decreases the likelihood that cells cloned represent an atypical subpopulation.