Concordance of combination and single agent chemosensitivity prediction in ovarian carcinoma using the subrenal capsule xenograft assay (SRCA)

The tumors from 62 patients with advanced ovarian adenocarcinoma were assayed by the subrenal capsule xenograft assay (SRCA) for sensitivity to doxorubicin (A), cis-platinum (P), and cyclophosphamide (C), individually and in combination. In some instances only one or two of the individual drugs were assayed; however, the combination, CAP, was always tested. All patients received an optimal surgical debulking (absence of any residual tumor masses greater than or equal to 2 cm) followed by chemotherapy with CAP. Forty-two tumors were predicted to be sensitive to CAP by the SRCA; 51 of 71 (72%) individually tested drugs agreed with this determination. Twenty-one tumors were predicted to be resistant to CAP and 32 of 36 (89%) individually tested drugs agreed with this determination. In this preliminary study, 11 patients had surgically documented partial responses to CAP chemotherapy. All of these patients had tumors which prospectively tested as sensitive to CAP in the SRCA: 13 of 18 (72%) of separately tested drugs were in concordance with this sensitivity. Fourteen patients failed CAP therapy and three of these failures were predicted prospectively by the SRCA: 9 of 9 (100%) of separately tested drugs were in concordance. Thus, there is an overall concordance of 82% (22/27) between the individual components of a combination chemotherapy and the combination therapy itself. It would seem that extrapolations of sensitivity or resistance can be made from the individual components.