Effects of FUdR on primary-cultured colon carcinomas metastatic to the liver

Novel mouse models of hepatic artery infusion

BACKGROUND

The liver has unique anatomy in that most blood flow to normal hepatocytes is derived from the portal venous system, whereas liver tumors obtain their nutrient blood supply exclusively from the hepatic artery. The focused arterial delivery of anticancer agents to liver tumors has been performed for decades; however, preclinical models to standardize drug regimens and examine novel agents have been lacking. The purpose of this study was to establish preclinical hepatic artery infusion (HAI) models in a mouse and to evaluate the safety and delivery capability of the models.

MATERIAL AND METHODS

C57BL/6 and BALB/c mice were used to develop models of HAI via the hepatic artery (HA), superior pancreaticoduodenal artery (SPDA), or lienogastric artery (LGA). Success rates, distribution of perfusion, and associated morbidity and mortality were analyzed between groups.

RESULTS

All three models were feasible and reproducible in mice, and there was no statistical difference on body weight change between models. The HA model had a 13.3% mortality from acute liver failure, and the SPDA model demonstrated duodenal and pancreatic toxicity. SPDA and LGA routes had the highest success rates (96.7% and 91.4%, respectively) with low mortality, better drug delivery, and preserved physiologic liver function compared with the HA model.

CONCLUSIONS

The optimal route of HAI was mouse breed specific; SPDA access in BALB/c mice, and the LGA access in C57BL/6 mice. The described techniques serve as a reproducible platform for the identification and characterization of therapeutics for diverse metastatic liver tumors.

In vitro concentration response studies and in vitro phase II tests as the experimental basis for regional chemotherapeutic protocols

The theoretical pharmacologic benefit of regional vs. systemic chemotherapy is defined and the concentration response behavior of cytostatic drugs and their optimal exposure times are described with human cancer cell lines (HT29, NMG64/84) and fresh human tumor cell suspensions in the human tumor colony assay (HTCA). The theoretical pharmacological advantages are 5.8 to 6 for adriamycin (ADM), 8 for cisplatinum (CDDP), 6.3 for epidoxorubicin (EPI), 22 to 58 for 5-fluorouracil (5FU), 4.6 for mitomycin C (MMC), and 6.3 for mitoxantrone (NOV). The drugs differed in their cytotoxic potency in vitro and thus also potential efficacy for regional chemotherapy; however, all but 5-fluorodeoxyuridine (5FUDR) exerted cytotoxicity dependent on exposure time and concentration. On average, elevation of the test concentrations by 1 lg doubled responses in fresh human tumor cell suspensions. From these results and clinical considerations, optimal times were defined for the regional chemotherapy strategies of hepatic artery infusion, intraperitoneal instillation, and chemoembolisation as performed at our institution.

In vitro pharmalogic rationale for intraperitoneal regional chemotherapy

We performed basic in vitro studies on cell lines and individual tumor cell suspensions to support the concept of intraperitoneal regional chemotherapy, and to improve the rationale for drug selection in this regional chemotherapeutic method. We defined the concentration-response behavior and the dependence of drug cytotoxicity on time using the two human colorectal carcinoma cell lines HT29 and NMG 64/84. In addition, the drugs concentration-response behavior and cytotoxic potency for IPRC after a single drug exposure at 10 micrograms/ml (5-FU at 100 micrograms/ml) was preclinically defined with in vitro phase II studies using single cell suspensions of human solid tumor biopsies in the human tumor colony assay (HTCA). The drugs doxorubicin (ADM), cisplatin (CDDP), epidoxorubicin (EPI), 5-fluorouracy (5-FU), 5-fluorodeoxyuridine (5-FUDR), melphalan (LPAM), mitomycin C (MMC), and mitroxantrone were incubated at increasing concentrations up to 1000 micrograms/ml at 10, 30, 60, 360, and 1440 minutes with the cell lines. These drugs, as well as vindesine (VDS) and mafosfamide (MAF) were also tested in the HTCA at increasing concentrations. The HTCA response rates at 10 micrograms/ml (5-FU and MAF at 100 micrograms/ml) were used for in vitro phase II comparisons of potential drug clinical activities. All test drugs showed a time- and concentration-dependent cytotoxic activity against the cell lines. Based on the cytotoxicity test results with HT29 and NMG 64/84, specific times were recommended for clinical therapy with each drug. In the HTCA, the drugs showed different cytotoxic concentration responses. The concentration-response behavior of each drug varied in individual tumor biopsies of the same histology. Comparing the response rates at 1 microgram/ml (5-FU and MAF 10 micrograms/ml) and 10 micrograms/ml (5-FU and MAF 100 micrograms/ml), an overall increase of in vitro response by a factor of 2.1 +/- 0.7 (1.1-3.7) was noted. We were able to prove this principle qualification of various test drugs in our in vitro studies and to suggest the optimal exposure times for their use in intraperitoneal chemotherapy. Based on these results, NOV was successfully used in an IPRC clinical study.