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

Chemosensitivity testing with highly purified fresh human tumour cells with the MTT colorimetric assay

A major problem associated with the succinate dehydrogenase inhibition (SDI) test using tetrazolium dye (MTT) as a cancer chemosensitivity testing is the contamination of non-malignant cells in the tumour tissues. Highly purified fresh human tumour cells from 44 solid tumours and 24 malignant ascites were used for the MTT assay. The purity of tumour cells was greater than 90% after separation on Ficoll-Hypaque and Percoll discontinuous gradients. The OD570 obtained from tumour cells alone was higher than that from non-malignant cells. The chemosensitivity of tumour cells was distinct from that of non-malignant cells. Moreover, the chemosensitivity of highly purified tumour cells was also distinct from that of non-purified cells just separated from tumour tissues. 31 of the 68 patients had evaluable lesions, and received cancer chemotherapy according to the results of MTT assay using highly purified tumour cells. A clinical response was obtained in 10 of the 31 patients (response rate = 32.3%, 5 complete responses, 5 partial responses).

Chemosensitivity test for carcinoma of digestive organs

For the chemosensitivity for carcinoma of digestive organs, gastric, colorectal, and hepatic cancer tissues were examined using in vitro succinate dehydrogenase inhibition (SDI) test and in vivo subrenal capsule (SRC) assay. The chemosensitivity varied in the tissue. The origin of an organ tumor, histological differentiation, and difference of primary or metastatic lesions are critical for determining chemosensitivity. Biochemical analysis shows that antitumor drugs have an increased susceptibility in tissues with high activity of pyrimidine nucleotide synthesis.

5-Fluorouracil and UFT-sensitive gastric carcinoma has a high level of thymidylate synthase

The authors examined the relationship between the level of thymidylate synthase (TS) and the sensitivity to 5-fluorouracil (5-FU) and UFT, a combined oral preparation of 1-(2-tetrahydrofuryl)-5-fluorouracil (tegafur) and uracil in a molar ratio of 1:4. For the studies we used the subrenal capsule (SRC) assay and 15 human gastric cancer tissues. The TS levels were assayed by the ligand-binding technique, using [6-3H]FdUMP. The relative variation of tumor size (delta TuS/TuS0) was calculated to be as follows: delta TuS/TuS0 = [(TuS6 - TuS0)/TuS0] x 100 (%), where TuS6 was the tumor size on day 6 and TuS0 on day 0. The chemosensitivity was considered to be positive when delta TuS/TuS0 in the treated group decreased to below -10%. Decrease in tumor size was marked in case of exposure to UFT (-19.8 +/- 13.0%) (mean +/- standard deviation), compared with that to 5-FU (-9.0 +/- 7.2%), with a statistically significant difference (P less than 0.001). The TS level varied from 1.7 to 30.8 pmol/g gastric cancer tissue and the mean was 7.1 +/- 7.2 pmol/g tissue. A correlation was noted between the TS level and decrease in size of the tumor exposed to 5-FU (r = -0.671) or UFT (r = -0.758): gastric cancer tissue with higher level of TS is more sensitive to 5-FU and UFT than is that with a lower TS level. These findings show that the sensitivity to 5-FU and UFT of gastric cancer tissue is related to the TS level and that UFT shows promise for the treatment of patients with gastric cancer.

Combined effects of UFT with other anticancer agents using in vivo chemosensitivity tests

In order to estimate the combined effects of UFT with other anticancer agents, a nude mouse experimental system (NMES), and a subrenal capsule assay (SRCA) were investigated. Three human tumor xenografts were serially transplanted into nude mice and examined. These were; EH-1 established from esophageal cancer, SH-6 from gastric cancer and CH-3 from colon cancer. The antiproliferative effects were estimated in accordance with the NCI therapeutic protocol. Significant antiproliferative effects were obtained only in NMES and a positive relationship was observed between the two assays (p less than 0.05). In the groups which were treated with a single agent, positive tumor responses were observed against mitomycin C in SH-6, against cis-DD platinum in SH-6 and EH-1, and against adriamycin in EH-1, respectively. On this study the synergistic, additive and subadditive effects were defined as the positive combined effects. The combination of MMC and UFT produced positive combined effects for all xenografts in both assays.

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.

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.