The pharmacokinetics of 5-fluorouracil administered by arterial infusion in advanced colorectal hepatic metastases

Systemic combination therapy of intravenous continuous 5-fluorouracil and subcutaneous pegylated interferon alfa-2a for advanced hepatocellular carcinoma

BACKGROUND

In Japan, sorafenib is now the first-line therapy for individuals with advanced hepatocellular carcinoma (HCC), but no other treatment is available for such patients. The aim of this study was to assess the efficacy and safety of combination therapy with systemic continuous intravenous infusion of 5-fluorouracil (5-FU) and subcutaneous peginterferon alfa-2a, which was used before sorafenib was introduced to Japan.

METHODS

Two hundred and twenty-three HCC patients, who were not amenable to curative surgery, percutaneous ablation, or transarterial chemoembolization (TACE), and for whom intraarterial chemotherapy was not indicated because of the presence of extrahepatic metastasis or stenosis of the common hepatic artery, received peginterferon alfa-2a (90 μg subcutaneously on days 1, 8, 15, and 22) and 5-FU (500 mg/day intravenously given continuously on days 1-5 and 8-12). We assessed their response to treatment and survival, and treatment safety.

RESULTS

The response rate was 9.4 % (including six patients with complete response) and the disease-control rate was 32.7 %. The median time to progression was 2.0 months. The overall median survival time was 6.5 months (Child-Pugh class A: 9.2 months vs. Child-Pugh class B: 2.8 months). In a multivariate analysis, Eastern Cooperative Oncology Group (ECOG) performance status >0, Child-Pugh class B, and the presence of macroscopic vascular invasion were independent predictors of poor prognosis. The major grade 3-4 adverse events were leucopenia (13.9 %) and thrombocytopenia (5.8 %). No treatment-related deaths occurred.

CONCLUSIONS

This combination therapy was well tolerated and showed promising efficacy. Further studies are needed to establish the usefulness of this treatment.

Objective response and time to progression on sequential treatment with sunitinib and sorafenib in metastatic renal cell carcinoma

Patients with metastatic renal cell carcinoma (mRCC) are often treated sequentially with targeted agents, although the optimal strategy is not known. A retrospective, registry-based study has been carried out to assess correlation between clinical response and progression-free survival in patients with mRCC treated sequentially with tyrosine-kinase inhibitors (TKIs) sunitinib and sorafenib. Data on 218 mRCC patients treated with sunitinib and sorafenib who completed therapy with both TKIs were obtained from a database of mRCC patients. Standard nonparametric methods were used to assess correlation between response, PFS and length of treatment on the two agents. A strong correlation between responses to first- versus second TKI was observed (p < 0.001). No significant association was noted between the duration of therapy with the two TKIs (p = 0.056), although there was a weak statistically significant correlation between progression-free survival times in the subgroup patients who discontinued treatment because of disease progression. In conclusion, the duration of response on first TKI is of limited value in selecting mRCC patients for sequential TKI therapy. There is a strong correlation between the types of tumour response on the first- versus the second TKI.

Outcomes of hepatic artery infusion therapy for hepatic metastases from colorectal carcinoma after radiological placement of infusion catheters

AIM

The aim of this study is to evaluate the safety and efficacy of hepatic artery infusion (HAI) of 5-fluorouracil (5FU) for patients with liver metastases from colorectal carcinoma after radiological placement of infusion catheters.

METHODS

Forty-two patients with liver metastases from colorectal carcinoma received radiological placement of infusion catheters using the distal fixation method. They received continuous HAI of 5FU 1,000-1,500mg for 5h weekly or biweekly. Tumor status was assessed by chest-abdominal computed tomography (CT) scan after every 10 infusions. Hepatic perfusion was checked by CT arteriography via the infusion port after every 10 infusions.

RESULTS

Radiological placements of catheters were performed successfully in all cases. Each patient received an average of 36 treatments (range: 10-98). Catheter failure was found in 3 patients (7.1%). Nine incidents of grade 1 toxicity were observed in 8 patients (19.0%). There was a complete response in 6 patients, partial remission in 18, stable disease in 9, and progression of disease in 9 (response rate: 57.1%). Overall median survival time was 29.1 months. Using Cox's proportional hazard model, lymph node metastases in primary colorectal carcinoma and pre-treatment serum CEA affected overall survival (P=0.011, P=0.005).

CONCLUSIONS

HAI after radiological placement of infusion catheters is a safe and effective treatment particularly for patients with no lymph node metastasis in primary carcinoma or with a low pre-treatment serum CEA level.

Relationships between body composition parameters and fluorouracil pharmacokinetics

AIMS

To verify whether fluorouracil (FU) clearance (CL) and volume of distribution (V(ss)) are better correlated with specific body compartments, such as body cell mass (BCM), total body water (TBW) or fat free mass (FFM), rather than with body surface area (BSA) or total body weight (BW).

METHODS

Thirty-four patients (13 females and 21 males) affected by colorectal cancer and receiving FU as adjuvant therapy entered the study. CL and Vss were determined after a 2 min i.v. injection of FU (425 mg m(-2)) and leucovorin (20 mg m(-2)). Body composition, in terms of BCM, TBW and FFM, was evaluated non-invasively by bioelectrical impedance analysis (BIA).

RESULTS

Significant but poor correlations were found between CL or V(ss) and most anthropometric parameters, including BIA-derived measures (r2 range=0.10-0.21). However, when multiple regression analysis was performed with sex, TBW and FFM as independent variables, the correlations improved greatly. The best correlation was obtained between CL and sex (r2=0.44) and between V(ss) and sex (r2=0.36). FFM-normalized CL was significantly higher in women than in men (0.030+/-0.008 vs 0.022+/-0.005 l min(-1) kg)(-1); 95% CI of difference 0.012, 0.003; P=0.003), suggesting that FU metabolism is more rapid in females. Surprisingly, V(ss) was highly correlated with CL (r2=0.67; CL=0.52+V(ss) x 0.040). This finding may either be explained by extensive drug metabolism in extra-hepatic organs or by variable inactivation on first-pass through the lung. Both these hypotheses need experimental validation.

CONCLUSIONS

The pharmacokinetics of FU are better predicted by FFM and TBW than by standard anthropometric parameters and predictions are sex-dependent. The use of BIA may lead to improved dosing with FU.

A phase one study of the hepatic arterial administration of 1,25-dihydroxyvitamin D3 for liver cancers

BACKGROUND AND AIMS

It is well established that exposure to 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) inhibits the proliferation of human colorectal cancer and hepatoma cell lines, both in vitro and in vivo. However, clinical trials of the administration of 1,25(OH)2D3 and analogs for the treatment of malignancy have been limited by the development of hypercalcemia. 1,25-dihydroxyvitamin D3 is principally excreted in bile following hepatic catabolism. This suggested the hypothesis that hepatic regional administration may allow high doses of 1,25(OH)2D3 to be administered for the treatment of liver cancers without producing hypercalcemia, caused by a clinically significant first pass effect. This phase one study investigates the effect of hepatic regional administration of 1,25(OH)2D3 on serum calcium levels, together with other markers of renal and liver function.

METHODS

Six subjects with hepatic colorectal cancer metastases and one with primary hepatocellular cancer were given continuous hepatic arterial infusions of 1,25(OH)2D3, for periods of 1-4 weeks. Blood samples were taken regularly and assayed for calcium levels, liver function tests and urea and electrolyte levels.

RESULTS

Patients remained normocalcemic at dosages of up to 10 mcg/day. No patient experienced any side-effects from the treatment.

CONCLUSIONS

Administration of 1,25(OH)2D3 as a continuous hepatic arterial infusion allows a high dosage to be administered without inducing hypercalcemia. This route of administration may allow the potential of 1,25(OH)2D3 in the treatment of hepatic cancers to be realized.

5-Fluorouracil: forty-plus and still ticking. A review of its preclinical and clinical development

5-Fluorouracil (5-FU) and 5-fluoro-2'-deoxyuridine (FdUrd) are pyrimidine analogs that have been part of the therapeutic armamentarium for a variety of solid tumors for over forty years. 5-FU has customarily required intravenous administration due to poor and erratic oral bioavailability, while FdUrd has generally been employed for regional administration to the liver or the peritoneal cavity. A great deal of knowledge has been gained concerning the cellular pharmacology and mechanism of action of 5-FU since it was first synthesized in the late 1950's. A more thorough understanding of the factors influencing the metabolic activation of 5-FU and its cellular effects has generated considerable interest in combining it with both modulatory agents such as leucovorin and methotrexate that enhance its metabolism or cytotoxic effects. In addition, 5-FU has also been employed to enhance the therapeutic activity of other antineoplastic agents or modalities such as cisplatin and ionizing radiation with which it can synergize. Appreciation of the clinical pharmacology of 5-FU and FdUrd have led to a variety of schedules that are clinically useful. The preclinical and clinical pharmacology of 5-FU is reviewed to provide a basis for exploring the novel approaches to permit oral administration of 5-FU or its prodrugs that will be described in other articles in this issue.

Can pharmacokinetic monitoring improve clinical use of fluorouracil?

Fluorouracil is used clinically against a variety of solid tumors. It is a prodrug that undergoes a series of intracellular conversions to active cytotoxic species. There is wide interindividual variability in fluorouracil metabolism; furthermore, it has nonlinear kinetics that make it relatively more difficult to predict plasma concentrations after brief infusions compared with prolonged infusions. There is an increasing body of evidence that relates plasma fluorouracil concentrations to toxicity and effectiveness, and consequently there may be a definable mathematical relationship that describes a 'therapeutic window'. Dose nomograms and pharmacokinetic models based on limited sampling strategies have been developed, as have empirical dose escalation schedules based on multivariate analysis of the determinants of toxicity, The utility of these approaches should be tested in properly powered, prospective, randomised trials.

Chemo-embolization of experimental liver metastases. Part I: distribution of biodegradable microspheres of different sizes in an animal model for the locoregional therapy

An experimental in vivo rat model was established to simulate the embolization therapy of non-resectable liver metastases with microparticulate systems. The effects of biodegradable microspheres on a transplanted liver-tumor cell line in rat livers were investigated with respect to particle size. The distribution of fluorescence-labelled microspheres was investigated to characterize the effects of long-term embolization with biodegradable microspheres, and the suitability and relevance of this animal model. Novikoff hepatoma cells were implanted into the central liver lobe of Sprague-Dawley rats. After seven days, four batches of fluorescence-marked microspheres (17 microm, 25 microm, 30 microm, and 40 microm) were administered into the proper hepatic artery. Liver(including the tumor), lung and spleen were isolated and frozen sections and tissue cubes of liver-, border-, and tumor tissue were prepared. The sections were examined by fluorescence microscopy. The cubes were extracted and the fluorescence of the marker quantified. During operation, microspheres smaller than 40 microm did not cause complete embolization. The slides showed the spreading of the smaller particles to the spleen and lung. Only 40 microm particles accumulated in the liver and were rarely detectable in other organs. The extraction showed a high concentration of the 40 microm particles in the border tissue. Apparently they were trapped proximal to the tumor capillary system and therefore showed a high ratio of border/tumor concentration. Microparticles smaller than 40 microm had a border/tumor concentration ratio of less than one and were distributed to the spleen and lung. In conclusion, a mean particle diameter of at least 40 microm is required for embolization. Thus, the model shows similarity to clinical situations in the treatment of human liver tumor and metastases.

Intra-hepatic arterial drug delivery

In this review, the pharmacokinetic rationale for hepatic arterial drug therapy is discussed, along with techniques that have been developed in order to try to enhance the regional advantage accrued from this route of administration. Clinical trials of hepatic arterial therapy in patients with primary hepatocellular carcinoma and with liver metastases from colorectal carcinoma are discussed. Although clinical response rates are significantly better with regional as compared with systemic therapy, survival is not prolonged. This is mainly due to the development of extrahepatic metastases. A treatment strategy using high dose hepatic arterial 5-fluorouracil (5-FU) infusion with the deliberate aim of achieving maximum tolerated systemic drug levels has entered phase III clinical trial. Monitoring of in vivo tumour pharmacokinetics using 19F magnetic resonance spectroscopy and 18F-5-FU positron emission tomography (PET) demonstrate elegantly how target drug uptake may be assessed. We plan to use PET to monitor intra-tumoral viral transduction and 5-flucytosine conversion rates to active 5-FU in our hepatic arterial pro-drug gene therapy programme soon to enter clinical trial.

A phase II study of regional 5-fluorouracil infusion with intravenous folinic acid for colorectal liver metastases

Regional chemotherapy, delivered via the hepatic artery, may significantly increase tumour response rates in patients with colorectal liver metastases. However, survival is limited by extrahepatic disease progression. We have developed a novel therapeutic approach for patients with metastases confined to the liver. In order to achieve high local response rates and also inhibit extrahepatic progression, 5-fluorouracil (5-FU) was infused intra-arterially at a dose previously calculated to achieve both high-dose regional therapy and adequate systemic levels. To enhance efficacy further, 5-FU was combined with high-dose systemic folinic acid (FA). Thirty-one patients were evaluated in a phase II study. 5-FU (1.5 g m2) was infused via a surgically implanted hepatic artery catheter over a 24 h period; FA (total 400 mg m-2) was infused intravenously during the initial and final 2 h. Treatments were given weekly for cycles of 6 weeks' duration. To date, median duration of treatment is 6 months and the median follow-up period is 17 months. The overall response rate was 48% with two complete and 13 partial responses. Predicted median time to progression is 8 months. The site of first progression was hepatic in 10 (42%) and extrahepatic in 14 (58%) patients. Seven patients developed local complications; one required emergency surgery. Side-effects were limited to grade 3 toxicity (four patients) or less. Predicted median survival is 19 months. This approach, which is associated with a high response rate and low systemic toxicity, warrants further evaluation. A phase III study is planned.

Clinical pharmacokinetic advantages of new drug delivery methods for the treatment of liver tumours

Response rates following systemic chemotherapy for hepatic tumours are disappointing. The drugs used have a narrow therapeutic ratio, which limit the scope for dose escalation of these potentially toxic agents. Therefore, alternative delivery methods that optimise the efficacy of currently available cytotoxic agents have been explored. Several novel approaches have attempted to 'target' treatment so that it reaches the tumour whilst minimising systemic exposure. There is some evidence to suggest that certain agents, including monoclonal antibodies and liposomes, selectively lodge in tumours following intravenous administration. Alternatively, the route of administration may be modified to enhance targeting of the administered drug. Delivery via the hepatic arterial, portal venous, and peritoneal routes as well as drug delivery via direct implantation may provide certain pharmacokinetic advantages. Infusion rates may be adjusted to optimise the pharmacokinetic profile. Chemoembolisation with microspheres, microcapsules or macromolecules might enhance targeting further. Variations in particle characteristics or by modifying hepatic arterial blood flow with vasoactive substances may be used to further refine this technique. The ultimate 'magic bullet', which allows total delivery of treatment to malignant cells whilst eliminating exposure of healthy tissues to these toxic agents, has not been developed as yet. However, currently available techniques allow considerable dose escalation that, whilst not providing a significant survival advantage, certainly improves response rates.

A phase I study of regional 5-fluorouracil and systemic folinic acid for patients with colorectal liver metastases

A phase I study was undertaken in order to establish the maximum tolerated dose of intra-hepatic arterial 5-fluorouracil (5-FU) when given in combination with systemic folinic acid. Patients with colorectal liver metastases (n = 10) received escalating doses of 5-FU as a 24 h infusion with a fixed dose (400 mg m-2) of intravenous folinic acid once per week. Dose limiting toxicity (WHO grade greater than 2) was encountered at 2 g m-2 5-FU. Principal adverse effects were diarrhoea, vomiting and oral ulceration. The recommended dose for phase II studies is 1.5 g m-2 week-1 24 h 5-FU regional infusion with 400 mg m-2 week-1 intravenous folinic acid.

A pharmacokinetic comparison of intravenous versus intra-arterial folinic acid

Recent clinical trials have suggested that a combination of folinic acid and 5-fluorouracil (5-FU) may improve response rates and survival in patients with advanced colorectal cancer. However, this regimen has been complicated by potentially life threatening toxicity. Regional delivery of folinic acid via a hepatic artery catheter might be expected to reduce systemic exposure and subsequent adverse effects. The present study compared the pharmacokinetic profiles of intravenous and intra-hepatic arterial infusions of folinic acid in patients with colorectal liver metastases (n = 6) who were being treated with weekly regional infusions of 5-FU. The mean area under the plasma concentration--time curve, the peak plasma concentration and the steady state volume of distribution were 163 micrograms ml-1 h-1 (SD 41), 18.5 micrograms ml-1 (SD 1.2) and 7.41 m-2 (SD 0.44) respectively following intravenous administration of folinic acid compared with 142 micrograms ml-1 h-1 (SD 45), 14.8 micrograms ml-1 (SD 2.4) and 11.21 m-2 (SD 1.22) following intra-hepatic arterial administration (P less than 0.05). Regional folinic acid was therefore associated with a statistically significant reduction in systemic exposure compared with the intravenous route.

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.