Responsiveness of gynecologic tumors to chemotherapeutic agents in the 6-day subrenal capsule assay

An assay to measure adriamycin binding in osteosarcoma cells

Adjuvant chemotherapy is currently employed in the treatment of patients with osteosarcoma, but the drug regimens, although effective in improving disease-free survival, are unsuccessful in 20-40% of patients and very toxic. It would be useful to know whether tumor cells are sensitive to a given drug prior to its use. To this end, we developed a method of assessing Adriamycin (doxorubicin) binding to tumor nuclei as a possible means of detecting sensitivity to the drug. Adriamycin-sensitive murine osteosarcoma cells were used to develop the assay. The in vitro conditions (drug concentration, duration of incubation, and temperature) were optimized with use of the murine osteosarcoma cells in culture. After the cells had been incubated with Adriamycin, cell viability was determined and Adriamycin fluorescence intensity was measured with a cytofluorometer. The optimal parameters for Adriamycin binding were found to be a 30-minute incubation in a 10 micrograms/ml concentration of Adriamycin at 37 degrees C; the frequency of cells that emitted Adriamycin fluorescence from the nucleus compared with the total number of living cells reached 100% under these conditions. In a murine leukemia cell line with known sensitivity to Adriamycin, the cells emitted red fluorescence from the nucleus and cytoplasm, whereas in a resistant line the cells emitted Adriamycin fluorescence from only the cytoplasm. We demonstrated that it is possible to differentiate nuclear from cytoplasmic concentration of Adriamycin in a tumor cell with use of a fluorescent microscope and that resistant cell lines can be distinguished from sensitive cell lines by this method.(ABSTRACT TRUNCATED AT 250 WORDS)

Subrenal capsule assay for fresh human tumors in immunocompetent mice; an inappropriate technique for non-small cell lung cancer

The subrenal capsule assay (SRA) seems to present some difficulties for the evaluation of the chemosensitivity of antineoplastic agents against fresh tumor xenografts. A study was therefore carried out to verify whether two different xenografts would behave in a similar way. Tumors such as melanoma provided adequate homogeneous material for this technique, while non-small cell lung carcinoma (NSCLC) were heterogeneous since the 1 mm3 specimen grafted under the renal capsule usually contained diffuse areas of necrosis and of infection. Furthermore, a large proportion of the grafted specimens, 257 out of 298, did not contain any tumor at all on microscopic examination even when they showed macroscopic growth. Added to these discrepancies, a random microscopic analysis of 180 adjacent fragments of NSCLC and melanomas demonstrated that the variability of heterogeneous tumors precludes any meaningful comparison between homologous tumor tissues designed to be grafted on treated and on control mice. The anti-inflammatory effect of chemotherapeutic drugs on the host's reaction to the graft is probably responsible for the differences between the macroscopic growth results observed in pieces grafted to both treated and control mice: however, it could not be simulated by hydrocortisone (HC) under our experimental conditions. This allows us to conclude that fresh tumors from NSCLC cannot be used in SRA.

Subrenal capsule assay of fresh human tumors: problems and pitfalls

The 6 day subrenal capsule (SRC) assay was performed in normal mice using 20 fresh human non-small cell lung cancers and nine fresh ovarian cancers. Different multi-agent chemotherapy regimens administered intravenously on days 2 + 3 of the assay were evaluated for activity against these two tumor types. Macroscopic results measured via an ocular microscope showed high activity for some combinations as well as for single agents. However, when subjected to microscopic examination, the SRC implants in the untreated control animals did not show viable tumor growth on day 6. Detailed histologic evaluation of over 800 SRC grafts reveals an intense inflammatory and fibrotic reaction in the majority of the grafts. These results indicate that drug sensitivity patterns obtained with this assay using only macroscopic criteria do not correlate with actual tumor regression. Microscopic analysis of the grafts prior to transplant shows absence or only minimal presence of tumor in many cases which also contributes to the poor growth observed in these two tumors.

Chemosensitivity profiles of human cancers assessed by the 6-day SRC assay on serially xenografted tumors

To assess the potential value of the 6-day subrenal capsule (SRC) assay in preclinical evaluation of new drugs using serially xenografted human tumors as source of tumor tissue, we studied the response of 31 human tumor lines (8 malignant melanomas, 12 sarcomas, 9 lung carcinomas and 2 colon carcinomas) to relevant standard drugs and to a new imidazotetrazine, Mitozolomide. Mitozolomide was found to be the most active drug tested in 50% of the lung carcinomas and as active as CCNU in melanomas. The activity of the standard anticancer drugs against subrenal grafts closely resembled the patterns seen with the same tumors in the clinic. In further attempts to validate the procedure, sensitivity profiles of some tumors were concurrently determined in the subcutaneous (s.c.) nude mouse model. In 11 out of the 12 tumors, the two assays selected the same drug as being the most active and in most of these tumors the two procedures gave the same ranking for the different drugs. Also, when the relative sensitivities of a series of melanoma xenografts to each of two drugs (DTIC and CCNU) were tested, the two assays gave the same ranking of the xenografts for each drug. The concordance between the two assays and the fact that the s.c. nude mouse assay reflects the chemosensitivity of the parent tumor in patients, suggest that the application of the 6-day SRC assay to xenografted tumors is a valid and useful procedure permitting rapid preclinical evaluation of new drugs to be carried out at relatively low cost.

Cell structure and function and response to chemotherapy in tumors heterotransplanted into the subrenal capsule of mice and rats

Specimens from 16 freshly biopsied human tumors, two mammary adenocarcinomas, ten ovarian adenocarcinomas, two squamous cell carcinomas, one malignant histiocytoma and one chondrosarcoma of the bone, two human ovarian adenocarcinomas established by transplantation into nude mice and two adenocarcinomas induced in rat mammary gland were transplanted under the renal capsule of 510 normal immunocompetent mice and 180 rats and the effects of chemotherapy were evaluated. The results showed successful transplantation of all types of tumors in both animal species. Morphological analysis revealed preserved glandular structures with surface microvilli, mucin and CEA production and partially preserved basement membranes. Treatment with cyclophosphamide, vinblastine, adriamycin and cisplatin caused cell shrinkage, degradation and partial or total disappearance of the tumor cells. Vascularization was distinct in all specimens. A cellular infiltrate was found frequently but not consistently. A common end stage was a fibrotic scar with no cellular activity, occasionally giving a misleading impression of a growing tumor on gross observation. The results were obtained rapidly and suggest that the subrenal capsule assay would be useful for evaluating the sensitivity of human tumors to therapeutic manipulation, but needs supplementary histological examination.

Predictive testing of vulvar and cervical cancers to chemotherapy by the subrenal capsule assay

The 6-day subrenal capsule assay (SRCA) in normal immunocompetent mice was used to assess response of vulvar and cervical cancers to chemotherapy. Twenty-five out of 31 assays (81%) were evaluable. The previously treated tumors tended to be less sensitive than the untreated tumors (20 vs 33%). Three to five cytotoxic drugs or drug combinations were tested against each individual tumor. In the whole material the combination of cisplatin and etoposide (VP-16) was significantly more effective than bleomycin (P less than 0.01, chi 2 test). The combinations adriamycin + cyclophosphamide + cisplatin and cyclophosphamide + methotrexate were also rather effective. Preliminary clinical correlations were positive. The reliability of the SRCA was discussed, and it was concluded that the assay is a promising predictive method for individualizing chemotherapy.

Subrenal capsule assay in human breast cancer. Response to cytostatic drug combinations and correlation with receptor status

The subrenal capsule assay (SRCA) was used to study the sensitivity of breast cancer to cytostatic drug combinations. The results were compared with steroid receptor status. Forty-five of 46 SRCAs (98%) were macroscopically evaluable. However, a histological study implied that the transplants should also be evaluated histologically, because in only 14/21 (67%) of the control SRCAs examined were histologically viable tumor cells seen. An inflammatory cell reaction was noticed in half of the cases. In the groups treated with cytostatics only 3/21 (14%) had vital tumor cells, whereas inflammation was evident in 4/21 (19%) of the cases. The rate of resistance to A + CTX was 30%. By testing several drug combinations against each tumor the rate of chemoresistance was reduced to 10%. The differences between A + CTX and the best combination were statistically significant (P less than 0.05). Of the tumors 79% were ER-positive and 67% PR-positive. Receptor-negative tumors tended to be more sensitive to cytostatics than receptor-positive tumors (100 vs 85%). The difference was not, however, statistically significant. It can be concluded that the SRCA under standardized conditions is a good method for studying the response of individual breast cancers to chemotherapy.

The subrenal capsule tumor implant assay as a predictor of clinical response to chemotherapy: 3 years of experience

The clinical response to chemotherapy of a series of female patients with advanced pelvic malignancies was compared to the response of their tumors to the same agents in the murine subrenal capsule implant assay. A total of 194 different patients were studied in 242 different assays; 89.3% of the assays were evaluable. There were 83 prospective assays (assays performed before the patient received the chemotherapy) of 66 different patients for which clinical correlations were available. In these assays the sensitivity (frequency of positive test results in responding patients) was 85.0%, the specificity (frequency of negative test results in nonresponding patients) was 57.1%, and the efficiency (percentage correctly classified) was 63.9%. There were 100 retrospective assays (assays performed after the patient had been treated with the chemotherapy) of 69 different patients for which clinical correlations were available. In these assays the sensitivity was 66.7%, the specificity 70.7%, and the efficiency 70.0%. Thirty-one of the patients had both prospective and retrospective assays. There were 59 patients for whom the clinical response to chemotherapy could not be determined. It is believed that the clinical utility of the SRC assay has been validated by the good prospective sensitivity of the assay.