Chemoembolization in regional cancer chemotherapy: a rationale

Targeting of different ethiodized oil-doxorubicin mixtures to hypovascular hepatic metastases with intraarterial and intraportal injections

PURPOSE

The distribution of different ethiodized oil-doxorubicin mixtures within and around hypovascular liver metastases in athymic nude mice was compared following either intraarterial or intraportal injections.

MATERIALS AND METHODS

Six different mixtures of doxorubicin and ethiodized oil in water-soluble contrast material, shaken for 5, 10, 15, and 30 minutes, respectively, were prepared and the size of the oil droplets in the mixtures evaluated. Intraarterial and intraportal injections of mixtures shaken for 10 and 15 minutes were performed in mice bearing hypovascular hepatic colorectal metastases. In vivo video microscopy was used to evaluate microvascular flow and the biodistribution and the size of the oil droplets within and around the tumors.

RESULTS

Oil droplets smaller than 20 microns in diameter were taken up by tumor nodules. There was no significant difference in oil droplet accumulation within the tumor between intraarterial and intraportal injections. Oil droplets larger than 20 microns occluded small and medium portal branches. The optimum combination was 0.1 mL of ethiodized oil in 2 mL of diatrizoate sodium meglumine (Renografin-76) shaken for 15 minutes at 800 rpm, which formed droplets smaller than 20 microns (92%).

CONCLUSION

Avascular regions of hepatic metastases may be embolized with ethiodized oil-anticancer drug mixtures containing oil droplets smaller than 20 microns. Since these droplets penetrate to the tumor interstitium with either intraarterial or intraportal injections, chemoembolization via the arterial route seems preferable for treatment of unresectable hypovascular hepatic metastases since it is easier to perform. The conclusions drawn from this study are limited to the animal model for experimental hypovascular hepatic metastases.

Casein as a carrier matrix for 5-fluorouracil: drug release from microspheres, drug-protein conjugates and in-vivo degradation of microspheres in rat muscle

Glutaraldehyde cross-linked casein microspheres were loaded with 5-fluorouracil (5-FU) from concentrated aqueous solutions of the drug after the microspheres were synthesized and cleaned. In-vitro release of the drug was examined in phosphate buffer in the absence and in the presence of protease at 37 degrees C. Drug release data showed that only about 20% of the drug is released in the absence of protease even after 5 days, while digestion of the matrix with protease released the entrapped drug completely in about 24 h. A protein-drug conjugate was synthesized via carbamoyl linkage using 6-(5-FU-1-yl)hexyl isocyanate and the drug release was examined in phosphate buffer at 37 degrees C. Release from the protein-5-FU conjugate was slower compared with the release from microspheres in the presence of protease. Implantation of placebo microspheres of different cross-linking densities in the gluteal muscle of rats showed no adverse tissue reactions over a one-year period. Histopathological examination of the tissues containing injected microspheres suggested that the biological life of casein microspheres in muscle is about 6 months, which is three times that of cross-linked albumin microspheres.

Treatment of hepatocellular carcinoma using doxorubicin/ethiodized oil/gelatin powder chemoembolization

BACKGROUND

Hepatocellular carcinoma (HCC) is a common malignancy worldwide with limited effective therapeutic options available or appropriate for cirrhotic patients.

METHODS

Chemoembolization, using sequential intra-arterial doxorubicin/ethiodized oil and gelatin sponge particle/ethanol embolization, was used to treat patients with unresectable HCC localized to the liver. Fifty-two patients were treated in this manner from 1988 to 1992. The objective response was determined by sequential computed tomography (CT) scans.

RESULTS

Of the 47 patients evaluable for response, 20 (43%) achieved a partial response, and 12 (26%) achieved a minor response. Sixteen patients underwent repeated chemoembolization for locally recurrent disease as many as three times after the initial procedure. All 52 patients were evaluable for survival and toxicity, with a median follow-up of 14 months. Twelve-month survival was 60%, and median survival was 16 months. This compares favorably with values reported in the literature of approximately 20% and 6-14 weeks, respectively. There was a 17% 30-day mortality, with a slightly higher risk for patients with portal vein obstruction. Other toxicities generally were mild and transient, including fever, pain, encephalopathy, and malaise.

CONCLUSIONS

Chemoembolization may enhance survival for patients with unresectable, localized HCC. It appears to be an effective alternative to standard treatment, even in cirrhotic patients.

Chemoembolization for hepatocellular carcinoma: epinephrine followed by a doxorubicin-ethiodized oil emulsion and gelatin sponge powder

PURPOSE

This study evaluates chemoembolization (CE) of the liver with minimal vasoconstriction followed by selective intraarterial delivery of an emulsion of iopamidol, doxorubicin, and ethiodized oil and temporary occlusion of hepatic artery with gelatin sponge powder in patients with hepatocellular carcinoma.

PATIENTS AND METHODS

Since 1988, 30 patients with nonresectable hepatocellular carcinoma underwent CE with the above protocol. Intraarterial epinephrine (0.5-1 microgram diluted in 10 mL of saline) was rapidly injected directly into the proper hepatic artery or selectively into the right or left hepatic arteries and was followed by 40-60 mg of doxorubicin dissolved in 10 mL of iopamidol and emulsified in 20 mL of ethiodized oil. The chemoembolic mixture was injected at the rate of arterial flow. Liver function and clotting parameters were monitored three times a day until there was a downward trend toward preembolic levels. Computed tomography (CT) was performed immediately after embolization and at 1-3-month intervals. Embolization was repeated when CT demonstrated recurrent or progressive disease.

RESULTS

Disease recurred or progressed in 11 patients at 2-17 months after embolization. CE was repeated in four patients; one individual underwent three embolizations. Re-embolization was performed up to 14 months after initial embolization (median, 10 months). Five patients (16.7%) died within 1 month of embolization. Ten patients died at 3-33 months after CE. Two of these patients died of cirrhosis at 6 and 14 months, without evidence of recurrent tumor. Fifteen patients remain alive 5-28 months after CE. Kaplan-Meier estimation of probability of survival curves demonstrates a median survival of 14 months. Sixty-one percent of patients were alive at 1 year and 36% at 2 years after the procedure.

CONCLUSION

CE with use of the above technique is effective for palliating inoperable hepatocellular carcinoma. It causes a significant prolongation of survival over the expected 18-24 weeks in untreated patients; this may occur because high doses of chemotherapeutic agents are delivered and come in contact with the tumor for a longer period, followed by ischemia brought about by temporary arterial occlusion.

Liver and tumor uptake and plasma pharmacokinetic of arterial cisplatin administered with and without starch microspheres in patients with liver metastases

Arterial chemoembolization of liver tumors should improve regional treatment by reducing native blood flow of the whole organ and redistributing residual flow toward hypovascular masses. Plasma cisplatin pharmacokinetics and its tissue uptake and relative tumor and liver vascularity were studied during surgical placement of arterial catheters in four patients and in four patients with colorectal metastases given intraoperative arterial cisplatin (DDP, 25 mg/m2), with an without coadministration of 600 mg degradable starch microspheres (DSM). Mean (+/- standard deviation) filterable plasma platinum levels peaked later (2 minutes) and were significantly lower after DDP with DSM (1.23 +/- 0.69 micrograms/ml) than after DDP alone (2.13 +/- 0.43 micrograms/ml, P less than 0.05), with the area under the curve (AUC0-30 min) values of 15.8 +/- 5.5 and 25.1 +/- 3.8 micrograms x min/ml (P less than 0.05), respectively. No differences in urine excretion, total body clearance, or plasma protein binding of platinum were observed. Tissue biopsies were started 15 minutes after DDP administration and completed in all cases within 5 minutes. Tumor platinum concentrations were significantly higher after DDP with DSM (3.03 +/- 1.60 micrograms/g) than after DDP alone (0.67 +/- 0.49 micrograms/ml, P less than 0.05). Liver concentrations and tumor-liver ratios of platinum also were higher, although not significantly, after DDP with DSM. Preoperative vascularization, studied with arterial perfusion scan, influenced individual tissue drug uptake in cases given DDP alone, with the lowest tumor levels in cold masses. Very high and almost superimposable liver and tumor concentrations were measured in those receiving DDP and DSM. The latter phenomenon was irrespective of native vascularization, indicating that DSM administration induced both an increased whole-liver extraction of the drug and a redistribution of blood flow and flow-dependent tissue uptake of platinum.

Development of radiolabelled albumin microspheres: a comparison of gamma-emitting radioisotopes of iodine (131I) and indium (111In/113mIn)

Biodegradable albumin microspheres have been prepared incorporating either 131I or 111In/111In. Using cDTPAA/albumin molar ratios of 1, 3 and 10, approx. 0.7, 2.1 and 7 molecules of DTPA could be coupled to an albumin molecule, labelling efficiency being constant over this range. Because 131I microspheres were more stable in plasma than the system labelled with radionuclides of indium it was selected for clinical evaluation: potential uses of this radiopharmaceutical are illustrated.

Relationship between reductive drug metabolism in tumour tissue of anthracyclines in microspherical form and anti-tumour activity

Increased activity against a rat solid tumour of doxorubicin incorporated into protein microspheres and administered intratumourally was associated with both increased duration of exposure of tumour tissue to native drug and anaerobic bioreduction of doxorubicin to 7-deoxyaglycones, indicating formation of reactive drug intermediates within tumour tissue. To investigate which of these aspects of drug disposition determined activity we have compared the in vivo fate (clearance from and metabolism by tumour tissue) of doxorubicin in microspherical form with the analogue 4'-deoxydoxorubicin and related this to the tumour growth delay recorded for these drugs. Within the dose range 42 to 55 micrograms, growth delay (14-18 days) of doxorubicin in microspherical form was markedly superior to drug in solution, whereas growth delay of 4'-deoxydoxorubicin in microspherical form (4.3-7.2 days) was not greater than drug in solution. Metabolism to 7-deoxyaglycones by tumour tissue was not a prominent feature of either drug when administered in solution. However, in microspherical form both drugs were extensively metabolized (peak concentrations: 3.6 micrograms/g doxorubicin 7-deoxyaglycone; 2.5 micrograms/g 4'-deoxydoxorubicin 7-deoxyaglycone). Native drug concentrations in tumour tissue were similar after administration in microspherical form at 48 hr (doxorubicin 3.8 micrograms/g; 4'-deoxydoxorubicin 3.7 micrograms/g) and 72 hr (doxorubicin 2.4 micrograms/g; 4'-deoxydoxorubicin 2.7 micrograms/g). At both time points, following administration in microspherical form, tumour tissue concentrations of doxorubicin were significantly greater than when drug was administered in solution, whereas no significant differences were observed for 4'-deoxydoxorubicin. The results are inconsistent with the process of anaerobic bioreduction of doxorubicin to 7-deoxyaglycones being an important component of its anti-tumour activity in microspherical form and point to the importance of increased duration of exposure to native drug.

Biodegradation rate of embolized protein microspheres in lung, liver and kidney of rats

The targeting and sustained release characteristics of cytotoxic drug-loaded protein microspheres may prove useful in the therapeutic chemoembolization of solid tumours. Because biodegradation rate of embolized particles will influence rate of incorporated drug release and duration of exposure, this parameter was studied for microspheres (10-30 microns mean diam.) prepared from the proteins albumin and casein, that we have previously used as carriers for doxorubicin. As a measure of microsphere loss in-vivo the radionuclide 125I was chosen because it can be covalently bound to proteins and also homogeneously distributed throughout the matrix. Radiolabelled microspheres were administered to rats both intravenously (lung as target organ, 1.4-2.2 mg/100 g) and via the hepatic artery (liver as target organ, 0.4-0.8 mg/100 g). In both cases it was observed that the casein system biodegraded more slowly than the albumin in-vivo. Thus, time taken for loss of 50% of embolized microspheres from lung was: albumin 2.0 days; casein 3.5 days and from liver:albumin 3.6 days; casein 6.8 days. Microsphere "debris" did not markedly accumulate in other organs. In-vitro experiments showed that microspheres were stable in serum and that albumin microspheres were not innately more sensitive to enzymic digestion than casein. The results may be useful in estimating duration of exposure of target organs to drug-loaded microsphere systems prepared from these proteins.

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.