Experiments on the toxicity of locoregional liver chemotherapy with 5-fluoro-2'-deoxyuridine and 5-fluorouracil in an animal model

Superiority of combined chemo-embolization and portal infusion with 5-fluorouracil over locoregional infusion concepts in Novikoff hepatoma-bearing rats

The aim of this study was to investigate experimentally whether there is a superior effect of the combination of hepatic artery chemo-embolization with portal vein infusion over either of the two treatment modalities alone. Novikoff hepatoma cells transplanted under the liver capsule of Sprague Dawley rats were used as a model. Tumor growth was assessed at 7 and 21 days after tumor inoculation. The prolamine solution Ethibloc was employed for embolization, and 5-fluorouracil was used as a chemotherapeutic agent for both infusion and chemo-embolization. All arterial treatment modalities were administered in a super-selective manner. There was no intolerable toxicity after dosages of 55 to 125 mg 5-fluorouracil/kg body weight. With regard to therapeutic efficacy the results show that embolization is an effective therapeutic means for inducing tumor necrosis in selected liver areas. As a consequence, the ranking of all treatment modalities was based on the combined evaluation of tumor size and extent of tumor necrosis. According to this evaluation, hepatic artery chemo-embolization was superior to the respective type of infusion (P<0.01). In addition, the combination of both modalities in the form of hepatic artery chemo-embolization and portal vein infusion was effective in destroying more than 97% of vital tumor tissue (P<0.01). These results suggest the need for a comparative clinical study.

Intraportal chemotherapy for colorectal hepatic metastases

One-third of colorectal cancer patients suffer from liver metastases on initial diagnosis. Overt liver metastases appear to be the first site of relapse for 40% to 50% of the patients with operable disease. The fact that tumor cells can be discovered in the mesenteric blood during surgery may indicate that circulating tumor cells give rise to metastases. Experimental investigations have shown that metastatic tumors reaching a diameter of 5 to 7 mm are predominantly perfused by the arterial route, which explains the unsuccessful attempts to treat established liver metastases through the portal vein. However, because metastases in the liver presumably arise via blood flow through the portal vein, adjuvant intraportal chemotherapy might permit ready access of the drug to small liver deposits in a way that systemic chemotherapy might not. The interest in portal adjuvant cytotoxic liver infusion in radically resected colorectal cancer patients is based on an early publication by Taylor, who in 1979 reported on a significant reduction of the incidence of liver metastases in a group of patients randomly assigned to perioperative adjuvant portal infusion with 5-fluorouracil. Based on these results, several groups initiated prospective randomized trials comparing intraportal infusion of various regimens to surgery alone. Results of most of these trials have been published during the last few years. All but one demonstrate improved overall survival and disease-free survival and a reduction of the incidence of liver recurrences in the adjuvant-treated patient group. Ongoing meta-analyses of the randomized trial data may confirm this tendency soon.

Locoregional administration of 5-fluoro-2'-deoxyuridine (FdUrd) in Novikoff hepatoma in the rat: effects of dose and infusion time on tumor growth and on FdUrd metabolite levels in tumor tissue as determined by 19F-NMR spectroscopy

The influence of infusion time and dose on the anticancer efficacy of 5-fluoro-2'-deoxyuridine (FdUrd) was investigated using a locoregional therapy model: Novikoff hepatoma transplanted i.m. into the thigh of Wistar rats and FdUrd infusion via a catheter implanted in the femoral artery. In experiment A the FdUrd dose (five daily doses of 12, 19 and 30 mg/kg) and the duration of administration (bolus, 1 h, 5 h, and 24 h) were varied. The change in tumor volume following treatment and the number of rats showing regression vs progression served as indicators of therapy response. The results showed a clear dose dependence, and for each infusion time the 30 mg/kg dose was the most effective, without any signs of general toxicity. At this dose the longest infusion time (24 h) was less effective (regression in three of six rats) compared with 1-h or 5-h treatments (four of five in regression). In experiment B either one or five daily FdUrd doses (15, 30, 60 mg/kg) were administered i.a. for the same infusion times used in experiment A. After treatment, tumors were explanted ex vivo and approximately 1-g tissues samples were immediately frozen in liquid nitrogen for storage. 19F-NMR spectroscopy at 11.7 T was used to quantify FdUrd metabolites [5-fluorouracil (FUra), alpha-fluoro-beta-alanine (F beta Ala), 5-fluorouracil nucleosides and nucleotides (F-Nuc)] in the solid tumor tissue samples (maintained at 4 degrees C) with a detection threshold of about 5 nmol/g. The metabolite signal pattern indicated that FdUrd is first converted to FUra, followed by anabolism primarily to nucleotides in the oxy form (e.g. FUTP). The total amount of fluorine detected in tumor tissue increased with dose and decreased with infusion time. For all treatments FNuc could be detected, even after 24 h infusion, and their levels showed a good linear correlation with the total F. The major catabolite F beta Ala was present in tumor at low levels that correlated poorly with total F, indicating recirculation from other organs (e.g. liver) as the main source. Thus, the NMR method can provide detailed information regarding the efficiency of locoregional treatment (catheter function, drug uptake and metabolism). Initial results of non-invasive in vivo NMR experiments are also presented.

Extracorporeal hemofiltration: a model for decreasing systemic drug exposure with intra-arterial chemotherapy

Cisplatin (3 mg/kg) was infused through the hepatic artery in nine mongrel dogs. Four of these dogs underwent simultaneous extracorporeal hemofiltration (ECH) of the hepatic venous effluent using a high-flow, dual-lumen catheter placed in the vena cava at the level of the hepatic veins. Platinum levels were measured in the plasma, urine, and ultrafiltrate and in kidney and liver tissue. ECH significantly reduced systemic drug exposure as measured by the AUC for free and total platinum, by urinary excretion, and by 24-h kidney levels. Regional liver levels were minimally affected. Recovery of platinum in the ultrafiltrate was 40% +/- 14%. ECH resulted in efficient extraction of platinum and reduced systemic drug exposure with relative preservation of regional hepatic drug exposure.

Regional chemotherapy of liver metastases from colorectal carcinoma: hepatic artery or portal vein infusion?

Hepatic artery infusion (HAI) chemotherapy has been well developed and is commonly used in the treatment of unresectable hepatic colorectal metastases. However, several important questions are unanswered, such as survival advantage over conventional systemic intravenous chemotherapy, long-term effects on the liver function, and prevention of complications, in particular cholangiosclerosis. Recent investigation into the blood supply of liver tumors challenges the adage that arterial flow is dominant. This review of the merits of regional HAI compared with portal venous infusion (PVI) chemotherapy shows a lack of conclusive data to favor either treatment modality, although a larger experience exists for HAI. Further studies need to be conducted.