Tumor dependent growth kinetics of human tumor xenografts using the subrenal capsule assay

Using the subrenal capsule assay modified by us in order to decrease the ingrowth of host cells, evaluation of the growth kinetics of three human ovarian tumors and one human lung tumor were made by multiple measurements of the tumor implantation site over the 6-day growth period. For all tumors, a lag period of 2-3 days was noticed before growth occurred in the subrenal location. In general, estimation of the composition of the fragments growing under the renal capsule did not change greatly in terms of percentage tumor of which they consisted but by day 6 most had shown a significant degree of host cell infiltration despite the effects of pre-implantation immunosuppression. We would suggest that only certain human tumors are suitable for implantation using this technique. Further, it appears that within even this group of selected tumors only some are suitable for drug studies, those having established exponential growth early enough so that a measurable endpoint can be reached within the 6-day time limit of the assay.