Comparison of the subrenal capsule assay and succinate dehydrogenase inhibition test.

Fresh surgical explants of solid tumors obtained from 50 patients were tested against the same chemotherapeutic agents in both the in vivo subrenal capsule (SRC) assay and the in vitro succinate dehydrogenase inhibition (SDI) test. Control growth adequate to meet evaluable assay criteria was obtained in 36 of 50 tumors tested in the SRC assay (72.0%). In the SDI test, 46 of 50 tumors were evaluable (92.0%). Correlations between the two test systems were dependent upon the activity criteria established for each system. With activity criteria set at current drug screening levels as a change of less than or equal to -2.0 in modified PAPAN score (S) for the SRC and an inhibition of greater than or equal to 50.0% in succinate dehydrogenase activity (SD) for the SDI, 12.5% of the drugs tested were active in the SRC and 22.3% were active in the SDI. Correlations of tumor response between the two test systems were 31.7% for sensitive (13/41) and 95.1% for resistant (98/103).