Pharmacokinetics of 5-fluorouracil in colorectal cancer patients receiving interferon

Angelica sinensis polysaccharides alleviate the oxidative burden on hematopoietic cells by restoring 5-fluorouracil-induced oxidative damage in perivascular mesenchymal progenitor cells

CONTEXT

5-Fluorouracil (5-FU)-injured stromal cells may cause chronic bone marrow suppression; however, the underlying mechanism remains unclear. Angelica sinensis polysaccharide (ASP), the main biologically active ingredient of the Chinese herb, Angelica sinensis (Oliv.) Diels (Apiaceae), may enrich the blood and promote antioxidation.

OBJECTIVE

This study investigated the protective antioxidative effects of ASP on perivascular mesenchymal progenitors (PMPs) and their interactions with hematopoietic cells.

MATERIALS AND METHODS

PMPs were dissociated from C57BL/6 mouse femur and tibia and were subsequently divided into the control, ASP (0.1 g/L), 5-FU (0.025 g/L), and 5-FU + ASP (pre-treatment with 0.1 g/L ASP for 6 h, together with 0.025 g/L 5-FU) then cultured for 48 h. Hematopoietic cells were co-cultured on these feeder layers for 24 h. Cell proliferation, senescence, apoptosis, and oxidative indices were detected, along with stromal osteogenic and adipogenic differentiation potentials. Intercellular and intracellular signaling was analyzed by real-time quantitative reverse transcription polymerase chain reaction and Western blotting.

RESULTS

ASP ameliorated the reactive oxygen species production/scavenge balance in PMPs; improved osteogenic differentiation; increased SCF, CXCL12, VLA-4/VCAM-1, ICAM-1/LFA1, and TPO/MPL, Ang-1/Tie-2 gene expression. Further, the ASP-treated feeder layer alleviated hematopoietic cells senescence (from 21.9 ± 1.47 to 12.1 ± 1.13); decreased P53, P21, p-GSK-3β, β-catenin and cyclin-D1 protein expression, and increased glycogen synthase kinase (GSK)-3β protein expression in co-cultured hematopoietic cells.

DISCUSSION AND CONCLUSIONS

ASP delayed oxidative stress-induced premature senescence of 5-FU-treated feeder co-cultured hematopoietic cells via down-regulation of overactivated Wnt/β-catenin signaling. These findings provide a new strategy for alleviating myelosuppressive stress.

A pharmacokinetic study of 5-FU/leucovorin and alpha-interferon in advanced cancer

The present study was designed to study 5-FU pharmacokinetics after interferon. Weekly bolus 5-FU (500 mg/m2), immediately followed by leucovorin (60 mg/m2) was given in 14 weekly cycles to 55 gastrointestinal and breast cancer patients. Interferon-alpha was given on days 2, 4 and 6, starting from cycle 2 at a dose of 0.5 million units (MU) and stepwise increased to 12 MU in cycles 12 and 13. Five patients could not tolerate the treatment even at the lowest dose of interferon and 22 patients were unavailable for the pharmacokinetic analysis because of dose reductions of 5-FU. Five patients were able to follow the protocol to 12 MU, whereas most patients were unable to continue owing to toxicity. 5-FU pharmacokinetics was analysed every second cycle. Peak concentration and AUC were increased after 12 MU of interferon, but no other significant influence of interferon on pharmacokinetic parameters of 5-FU was observed.

Immunomodulation therapy in colorectal carcinoma

There has been much progress in the understanding of the relationship between the immune system and colorectal cancer. This has led to the use of immunomodulatory therapy in the adjuvant and palliative treatment of the condition. Although attempts at the use of non-specific immunomodulation with agents such as levamisole, cimetidine, alpha interferon and Bacillus Calmette-Guerin (BCG) have not produced significant clinical benefits when tested in randomized trials in both the adjuvant setting and for metastatic disease, promising results are being obtained with more specific therapy. Edrecolomab [corrected], a murine monoclonal antibody targeting the 17-1A antigen on malignant colorectal cells has produced a reduction in relapse and mortality rates when used as adjuvant treatment following surgery for Dukes' C colon cancer. Active specific therapy with autologous tumour vaccine administered with BCG has produced similar benefits in Dukes' B cancer. Both 3H1 anti-idiotypic antibody against carcinoembryonic antigen and 105AD7 antibody to gp72 glycoprotein have demonstrated in-vitro and in-vivo immune activation against tumour. Non-randomized studies postulate prolongation of survival using these antibodies in advanced disease. These agents are all currently being tested in randomized studies powered to detect meaningful survival differences and clinical benefit. Immune therapy offers the potential of low toxicity therapy in colorectal cancer and may have a role as an adjunct to conventional chemotherapy.

A phase II study of recombinant interferon-beta (r-hIFN-beta 1a) in combination with 5-fluorouracil (5-FU) in the treatment of patients with advanced colorectal carcinoma

The combination of 5-fluorouracil (5-FU) and interferon-alpha (IFN-alpha) has reported activity in the treatment of advanced colorectal carcinoma. Laboratory studies of IFN-beta suggest that this agent may offer theoretical advantages over IFN-alpha in combination with 5-FU. A total of 27 patients with advanced or recurrent colorectal carcinoma were treated in a non-randomized open phase II study with a combination of 5-fluorouracil (750 mg m(-1) daily for 5 days as a continuous intravenous (i.v.) infusion followed, from day 15, by i.v. bolus 750 mg m(-2) every 7 days) and recombinant interferon-beta [r-hIFN-beta-1a; 9 MIU (total dose) by subcutaneous injection from day 1 on every Monday, Wednesday and Friday throughout the treatment period]. Toxicity was less than that seen with this schedule of 5-FU in combination with IFN-alpha. Among 21 evaluable patients, four objective responses were seen. Recombinant human interferon-beta-1a in combination with 5-FU is an acceptable regimen in terms of toxicity. However, the study did not demonstrate a superior response rate when compared with previous reports of treatment with 5-FU alone or in combination with IFN-alpha.

Measurement of plasma 5-fluorouracil by high-performance liquid chromatography with comparison of results to tissue drug levels observed using in vivo 19F magnetic resonance spectroscopy in patients on a protracted venous infusion with or without interferon-alpha

PURPOSE

To measure plasma 5-fluorouracil (5-FU) levels using high-performance liquid chromatography (HPLC) and compare the findings to the tissue metabolism of 5-FU evaluated using 19F magnetic resonance spectroscopy (MRS), during a protracted venous infusion (PVI) with or without interferon-alpha.

METHODS

Patients receiving PVI 5-FU (300 mg/m2/day) with or without interferon-alpha (5 x 10(6) units 3 times per week), had 2 weekly plasma 5-FU levels evaluated using reverse-phase ion-pairing HPLC. These samples were drawn just prior to the patient undergoing MRS using a 1.5T Siemens Magnetom whole body magnetic resonance system with a 16 cm surface coil placed over normal liver or metastatic tumour. Semi-quantitated MRS values were compared with the plasma 5-FU levels using linear regression analysis. Data were available from patients given interferon-alpha with PVI 5-FU from day 1 or at the point of 5-FU refractory disease.

RESULTS

A total of 30 patients were studied. Plasma 5-FU concentrations while on a protracted venous infusion varied from <25 ng/ml (0.192 mu M) to 25,000 ng/ml (192 mu M). A high plasma 5-FU concentration was associated with an increase in patient toxicity. Patients given interferon-alpha with 5-FU had higher median plasma 5-FU levels higher than patients on 5-FU alone (6138 vs. 218 ng/ml; p = 0.03). There was no correlation between the plasma 5-FU concentration and tumour response. A comparison of the plasma 5-FU data to the MRS studies in normal liver revealed a positive correlation between plasma 5-FU and liver catabolite signal (r = 0.68; p = 0.016) but a negative correlation with the log plasma 5-FU concentration and 5-FU liver signal (r = -0.63; p = 0.022). The patients experiencing toxicity, in addition to having a higher plasma 5-FU concentration did not exhibit a liver 5-FU signal, while the reverse was true for those having no toxicity.

CONCLUSIONS

Plasma 5-FU levels may show greater interpatient variation when given as a protracted venous infusion. Levels of 5-FU correlated with treatment toxicity but not with anti-tumour activity. The addition of interferon-alpha to 5-FU increases plasma 5-FU levels. MRS findings suggest patients with low plasma 5-FU levels have higher 5-FU levels in normal liver tissue than in those with higher plasma levels.

The role of interferon-alpha as a modulator of fluorouracil and leucovorin

Several preclinical studies have demonstrated that interferon-alpha (IFN-alpha) may enhance the cytotoxicity of fluoropyrimidines in a greater-than-additive manner in a variety of human cancer cell lines. The underlying mechanism(s) have varied in different cancer cell lines, and include increased fluorouracil anabolism to fluorodeoxyuridine monophosphate, further inhibition of thymidylate synthase, stimulation of thymidine and uridine phosphorylase activities, greater DNA damage, and enhanced natural killer cell-mediated lysis of tumour targets. These preclinical studies stimulated clinical evaluation of IFN-alpha in combination with 5-fluorouracil (5-FU) with and without leucovorin (LV), and the initial clinical results appeared promising. We summarise preclinical research concerning the interaction of 5-FU and IFN-alpha. The rationale for combining 5-FU with IFN-alpha and LV is discussed, and we describe our clinical experience with the combination of 5-FU, LV and IFN-alpha-2a. The insights and unresolved questions concerning the clinical application of this combination are also discussed.

A clinical and pharmacological study of 5-fluorouracil, leucovorin and interferon alfa in advanced colorectal cancer

Modulation of 5-fluorouracil (FUra) using leucovorin (LV) is a standard treatment approach in patients with metastatic colorectal cancer. Modulation of FUra with interferon alfa has also shown some promise. Laboratory data have demonstrated increased cytotoxicity when FUra is combined with both LV and interferon. The current study examined the effects of double modulation of FUra using LV and interferon. Patients with measurable advanced colorectal cancer received bolus FUra 375 mg/m2 plus LV 20 mg/m2 daily for 5 days, repeated every 28 days. Recombinant human interferon alfa-2a, 3 million IU/m2 subcutaneously, was given daily on the days of chemotherapy then three times weekly. There was one complete response and nine partial responses (10/41) seen for an overall response rate of 24% (95% CI 12.0-40.0%). Overall, 70% of patients experienced one or more episodes of nonhematologic toxicity of grade 3 or more. Weight loss was common, with a mean decrease of 2.9 kg over the first two months (P < 0.0001). Improvements in tumor-related symptoms were balanced by increased fatigue and a deterioration in body weight and performance status. There was no evidence of progressive changes in FUra metabolism from interferon usage.

The effect of 5-fluorouracil and alpha interferon and 5-fluorouracil and leucovorin on cellular anti-tumour immune responses in patients with advanced colorectal cancer

Interferon alpha (IFN-alpha) enhances the activity of 5-fluorouracil (5-FU) in the treatment of advanced colorectal cancer although the mechanism is not understood. We have investigated the effect of this combination on cellular immunity and compared this with standard therapy of 5-FU/L-leucovorin, in 24 patients with advanced colorectal cancer. This study has demonstrated an enhancement of the cellular immune response in patients given 5-FU/IFN-alpha with augmentation of natural killer (NK) cell function and abrogation of 5-FU-induced suppression of lymphokine-activated killer (LAK) cell activity.

Lack of effect of interferon alpha 2a upon fluorouracil pharmacokinetics

The disposition of 5-fluorouracil (FUra) was studied in 19 colorectal cancer patients during treatment with FUra and high-dose leucovorin (LV) with or without interferon alpha 2a (IFN-alpha). All received LV 200 mg m-2 over 2 h, then FUra 400 mg m-2 over 5 min then FUra 400 mg m-2 over 22 h, repeated on day 2, on a 14 day cycle. Nine patients also received IFN-alpha 6 MU every 48 h, starting at least 2 weeks before the study. Series of 14 blood samples were assayed for FUra by reversed-phase high-performance liquid chromatography (HPLC). Minimum Akaike information criterion estimation was used to determine the simplest effective pharmacokinetic model. This consisted of a single compartment with first-order (linear) and Michaelis-Menten (non-linear) components to drug elimination. This model gave r2 > 0.98 in 19/20 data sets. With the Michaelis constant (KM) set at 15 microM, values were derived for the volume of distribution (Vd), the maximum rate of non-linear elimination (Vmax) and the first-order elimination rate constant (K1.e). Mean (+/- s.d.) values in control (no IFN-alpha) patients were: Vd 10.4 (+/- 1.9) l m-2, Vmax 182 (+/- 59) mumol l-1 h-1 and k1.e 4.35 (+/- 0.58) h-1. No significant differences were detected in patients receiving IFN-alpha, in whom the equivalent mean values were Vd 10.0 (+/- 0.9) l m-2, Vmax 141 (+/- 27) mumol l-1 h-1 and k1.e 3.96 (+/- 0.5) h-1. Mean trapezoidal AUC0-22 h was similar in the two groups (control patients 116 microM h, IFN-alpha patients 125 microM h). No significant correlations with renal or hepatic function were detected. These results, while not inconsistent with previous reports of a reduced rate of FUra elimination at higher IFN-alpha doses, suggest that any clinical effect of this moderate dose of IFN-alpha on FUra toxicity or activity is due to modulation at target cells, not to pharmacokinetic interaction.

Protracted venous infusion 5-fluorouracil and interferon-alpha in advanced and refractory colorectal cancer

BACKGROUND

The management of patients with advanced colorectal cancer remains dependent on the optimal use of 5-Fluorouracil (5-FU). Enhanced 5-FU activity can be achieved by either adding a modulator or by altering the administration schedule, in particular using a protracted venous infusion. Based on encouraging phase II data using bolus 5-FU and interferon-alpha, we designed a study to investigate the activity of this modulator in patients with colorectal cancer refractory to protracted venous infusion 5-FU.

PATIENTS AND METHODS

Patients with advanced colorectal cancer were treated with 5-FU (300 mg/m2/day) given as a protracted venous infusion via an indwelling central venous catheter and portable battery driven pump. At the time the tumour became refractory to 5-FU, interferon-alpha was added and further outcome evaluated.

RESULTS

One hundred twenty-four patients were entered on the study, 118 of whom had measurable disease. Fifty-two patients had previously received chemotherapy. The overall tumour response rate with infusional 5-FU was 33% (38/118), however in previously untreated patients was 42% (29/69) and 18% in those given prior chemotherapy (9/49). At the point of refractory disease 64 patients had interferon-alpha added to the 5-FU. Five patients (8%) showed an objective partial response following interferon-alpha addition. Patient toxicities on infusional 5-FU included hand-foot erythroderma, stomatitis and diarrhoea. There were only 15 episodes of grade 3 or 4 toxicity. The addition of interferon-alpha gave fever, lethargy, myelosuppression and depression, but did not increase the incidence or severity of 5-FU related toxicities. Of 67 patients with tumour related pain, 53 (79%) had an improvement in their symptoms. Median survival of the whole group was 7.5 months.

CONCLUSIONS

Protracted venous infusion 5-FU is an active and well tolerated palliative treatment for advanced colorectal cancer. The addition of interferon-alpha at the point of 5-FU refractory disease resulted in further significant response in a small number of patients. Further randomised studies, including quality-of-life end-points, are needed before the use of interferon-alpha can be recommended as a modulator of 5-FU in the clinical setting.

Inhibition of dihydropyrimidine dehydrogenase by alpha-interferon: experimental data on human tumor cell lines

Interferons (IFNs) are very promising fluorouracil (FU) biochemical modulators. The pharmacological origin sustaining the FU-IFN synergistic interaction is not clearly understood. It was recently shown that alpha-IFN was associated with a dose-dependent decrease in FU clearance in treated patients. Dihydropyrimidine dehydrogenase (DPD) is the key regulating enzyme for FU catabolism. The effects on DPD exerted by both the IFN dose and the duration of exposure were evaluated in a panel of five human cancer cell lines. All cell lines investigated exhibited quantifiable DPD activity with inter-cell-line variability (0.118-0.318 nmol min-1 mg protein-1). A prolonged exposure to IFN (up to 5 days) was necessary to obtain a significant inhibition of DPD activity. A concentration-dependent significant decrease in DPD activity, reaching 50% of the initial activity determined for the highest IFN concentration (10(5) IU/ml), was demonstrated in all cell lines tested (5-day IFN exposure). For three cell lines, IFN potentiated the FU-induced growth inhibition in a concentration-dependent manner. Considering all cell lines and all IFN concentrations, it appears that globally, the greater the inhibition of DPD activity, the greater the FU potentiation (Spearman rank correlation on all cell lines, P = 0.011).