A phase II study of continuous infusion 5-fluorouracil and leucovorin with weekly cisplatin in metastatic colorectal carcinoma

Strategies to reduce the risk of platinum containing antineoplastic drug-induced ototoxicity

INTRODUCTION

Cisplatin is a highly effective chemotherapeutic agent against a variety of solid tumors in adults and in children. Unfortunately, a large percentage of patients suffer permanent sensorineural hearing loss. Up to 60% of children and at least 50% of adults suffer this complication that seriously compromises their quality of life. Hearing loss is due to damage to the sensory cells in the inner ear. The mechanisms of cochlear damage are still being investigated. However, it appears that inner ear damage is triggered by reactive oxygen species (ROS) formation and inflammation 34.

AREAS COVERED

We discuss a number of potential therapeutic targets that can be addressed to provide hearing protection. These strategies include enhancing the endogenous antioxidant pathways, heat shock proteins, G protein coupled receptors and counteracting ROS and reactive nitrogen species, and blocking pathways that produce inflammation, including TRPV1 and STAT1 36.

EXPERT OPINION

Numerous potential protective agents show promise in animal models by systemic or local administration. However, clinical trials have not shown much efficacy to date with the exception of sodium thiosulfate. There is an urgent need to discover safe and effective protective agents that do not interfere with the efficacy of cisplatin against tumors yet preserve hearing 151.

Synthesis, characterization and cytotoxic activity of binuclear copper(II)-complexes with some S-isoalkyl derivatives of thiosalicylic acid. Crystal structure of the binuclear copper(II)-complex with S-isopropyl derivative of thiosalicylic acid

Isoalkyl (isoalkyl = isopropyl-(L1), isobutyl-(L2) and isoamyl-(L3)) derivatives of thiosalicylic acid (TSA) were prepared by alkylation of TSA with corresponding isoalkyl-chlorides in the alkaline water-ethanol solution. The new free copper(II)-complexes with corresponding S-isoalkyl derivatives of TSA (C1-copper(II)-complex with S-isopropyl derivative of thiosalicylic acid, C2-copper(II)-complex with S-isobutyl derivative of thiosalicylic acid and C3-copper(II)-complex with S-isoamyl derivative of thiosalicylic acid) have been synthesized by direct reaction of copper(II)-nitrate with ligand precursor and then characterized by microanalysis, infrared spectra (IR) and EPR (electron paramagnetic resonance) spectra. The spectroscopically predicted structure of the obtained binuclear copper(II)-complex with S-isopropyl derivative of thiosalicylic acid was confirmed by X-ray analysis. Single crystals suitable for X-ray measurements were obtained by slow crystallization from a water solution. Newly synthesized precursors S-isoalkyl derivatives of thiosalicylic acid and corresponding copper(II)-complexes moderately reduced viability of human and murine lung cancer cells, they showed similar cytotoxic effect on human colorectal cancer cells as cisplatin and lower cytotoxic effect than cisplatin toward normal fibroblasts, evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) colorimetric technique. All new complexes exhibited apoptotic effect toward lung cancer cells, stronger than cisplatin, whereas only C3 induced significant apoptosis of colorectal cancer cells. Complex C1 showed significant antiproliferative effect against murine lung cancer cells, LLC1, while C2 reduced expression of Ki67 in human colorectal cancer cells. All tested complexes induced cell cycle arrest of HCT116 cells in G2/M phase.

Prediction of exposure-driven myelotoxicity of continuous infusion 5-fluorouracil by a semi-physiological pharmacokinetic-pharmacodynamic model in gastrointestinal cancer patients

Purpose

To describe 5-fluorouracil (5FU) pharmacokinetics, myelotoxicity and respective covariates using a simultaneous nonlinear mixed effect modelling approach.

Methods

Thirty patients with gastrointestinal cancer received 5FU 650 or 1000 mg/m²/day as 5-day continuous venous infusion (14 of whom also received cisplatin 20 mg/m²/day). 5FU and 5-fluoro-5,6-dihydrouracil (5FUH2) plasma concentrations were described by a pharmacokinetic model using NONMEM. Absolute leukocyte counts were described by a semi-mechanistic myelosuppression model. Covariate relationships were evaluated to explain the possible sources of variability in 5FU pharmacokinetics and pharmacodynamics.

Results

Total clearance of 5FU correlated with body surface area (BSA). Population estimate for total clearance was 249 L/h. Clearances of 5FU and 5FUH2 fractionally changed by 77%/m² difference from the median BSA. 5FU central and peripheral volumes of distribution were 5.56 L and 28.5 L, respectively. Estimated 5FUH2 clearance and volume of distribution were 121 L/h and 96.7 L, respectively. Baseline leukocyte count of 6.86 × 10⁹/L, as well as mean leukocyte transit time of 281 h accounting for time delay between proliferating and circulating cells, was estimated. The relationship between 5FU plasma concentrations and absolute leukocyte count was found to be linear. A higher degree of myelosuppression was attributed to combination therapy (slope = 2.82 L/mg) with cisplatin as compared to 5FU monotherapy (slope = 1.17 L/mg).

Conclusions

BSA should be taken into account for predicting 5FU exposure. Myelosuppression was influenced by 5FU exposure and concomitant administration of cisplatin.

Electronic supplementary material

The online version of this article (10.1007/s00280-019-04028-5) contains supplementary material, which is available to authorized users.

Palmar-plantar erythrodysesthesia

Objective. To provide a comprehensive review of the chemotherapy induced dermatological toxi-city, palmar-plantar erythrodysesthesia (PPE), including clinical presentation, drugs implication in causing the reaction, and approaches for management.

Data sources. A search of MEDLINE (1966-2002), IDIS (1985- 2002) and CANCERLIT (1993-2002) databases was conducted using the terms (and variations of the terms) palmar-plantar erythrodysesthesia, hand-foot syndrome, and acral erythema. Bibliographies from selected articles were also reviewed for appropriate references.

Data extraction. The retrieved literature was reviewed to include all articles pertaining to the incidence, clinical presentation, mechanism, pathology, diagnosis, treatment and prevention of PPE.

Data synthesis. PPE is a distinctive, localized cutaneous reaction to certain antineoplastic agents. A number of drugs have been implicated, including most commonly cytarabine, fluorouracil, doxorubicin, and capecitabine. There appears to be an association with administration schedules that lead to elevated peak plasma concentrations, such as in high-dose therapy, or after prolonged periods of constant exposure, as with continuous infusions, regular oral dosing, or liposomal formulations. The extent and severity of the reaction, time of onset, and duration are variable. Symptoms can occur to both hands and feet, and include dysesthesia, paresthesia, erythema, swelling, pain, blistering, ulceration, and desquamination. Cessation of the offending agent appears to be the most important step in the management of PPE. Dose modification may be necessary for subsequent cycles. As the course of PPE is self-limiting, treatment is commonly supportive and based on the type and severity of symptoms encountered. This can include analgesia, emollient or soothing creams, wound care, and cold compresses. Administration of corticosteroids has produced mixed results. Pyridoxine shows promise as both a treatment and preventative strategy, although confirmation in prospective clinical trials is needed. Advice should be provided to patients to ensure prompt recognition of toxicity and plans for prevention and amelioration of symptoms provided.

Significance of organic cation transporter 3 (SLC22A3) expression for the cytotoxic effect of oxaliplatin in colorectal cancer

The effect of oxaliplatin against colorectal cancer is superior to that of cisplatin, but the molecular mechanism(s) involved is not clear. We found previously that oxaliplatin, but not cisplatin, was transported by human (h) and rat organic cation transporter 3 (OCT3)/SLC22A3. In the present study, we examined whether hOCT3 was significantly involved in the oxaliplatin-induced cytotoxicity and accumulation of platinum in colorectal cancer. The level of hOCT3 mRNA in the colon was 9.7-fold higher in cancerous than in normal tissues in six Japanese patients (P = 0.0247). In human colorectal cancer-derived cell lines, the mRNA of hOCT3 was highly expressed compared with that of other organic cation transporters. The release of lactate dehydrogenase (LDH) and accumulation of platinum with oxaliplatin treatment were increased in SW480 cells transfected with hOCT3 cDNA compared with empty vector-transfected cells. T84 and SW837 cells, with high levels of hOCT3, released more LDH and accumulated more platinum after oxaliplatin treatment than low hOCT3-expressing cells such as SW480, HCT116, HT29, and Lovo. However, the amount of platinum accumulated after cisplatin treatment did not differ among these six cell lines. The levels of hOCT3 expression in colon and rectum were also higher in cancerous than in normal tissues in Caucasian patients as determined by dot blotting. In conclusion, the hOCT3-mediated uptake of oxaliplatin into the cancers was suggested to be important for its cytotoxicity, and hOCT3 expression may be a marker for cancer chemotherapy including oxaliplatin.

Role of p21waf1/cip1 in effects of oxaliplatin in colorectal cancer cells

Clinical studies have shown that oxaliplatin, a novel platinum derivative, is a potent chemotherapeutic agent for colorectal cancer when combined with 5-fluorouracil and leucovorin. Although the toxic activity is based on covalent adducts between platinum and DNA, its actual biological behavior is mostly unknown. In an effort to explore the mechanism of tumor susceptibility to oxaliplatin, we examined the cytotoxic effects of oxaliplatin in colorectal cancer cell lines in reference to p53 gene status. Although p53 gene status did not clearly predict sensitivity to oxaliplatin, p53 wild-type cells including HCT116 were sensitive but HCT116 p53-/- were found to be resistant to oxaliplatin. Oxaliplatin caused strong p21waf1/cip1 induction and G0-G1 arrest in p53 wild-type cells, whereas cisplatin did not induce G0-G1 arrest. Assays using p53 wild but p21waf1/cip1 null HCT116 cells revealed that oxaliplatin did not show G0-G1 arrest and reduced growth-inhibitory effects, suggesting that p21waf1/cip1 may be a key element in oxaliplatin-treated p53 wild-type cells. Although HCT116 is DNA mismatch repair-deficient, a mismatch repair-proficient HCT116+ch3 cell line displayed similar responses with regard to p21waf1/cip1-mediated growth inhibition and G0-G1 arrest. In p53 mutant cells, on the other hand, oxaliplatin caused an abrupt transition from G1 to S phase and eventually resulted in G2-M arrest. This abrupt entry into S phase was associated with loss of the p21waf1/cip1 protein via proteasome-mediated degradation. These findings suggest that p21waf1/cip1 plays a role in oxaliplatin-mediated cell cycle and growth control in p53-dependent and -independent pathways.

Genome-wide screen identifies genes whose inactivation confer resistance to cisplatin in Saccharomyces cerevisiae

To identify novel genes that mediate cellular resistance to cisplatin, we have screened the collection of Saccharomyces cerevisiae deletion strains. We have found reproducibly 22 genes/open reading frames (ORF), which when deleted, confer resistance to cisplatin at a concentration that is lethal to wild-type cells. Complementation of individual deletion strains with the corresponding wild-type gene abolished cisplatin resistance, confirming that specific gene deletions caused the resistance. Twenty of the genes/ORFs identified have not been previously linked to cisplatin resistance and belong to several distinct functional groups. Major functional groups encode proteins involved in nucleotide metabolism, mRNA catabolism, RNA-polymerase-II-dependent gene regulation and vacuolar transport systems. In addition, proteins that function in ubiquitination, sphingolipid biogenesis, cyclic AMP-dependent signaling, DNA repair, and genome stability are also associated with cisplatin resistance. More than half of the identified genes are known to have sequences or functional homology to mammalian counterparts. Some deletion strains are cross-resistant to selected cytotoxic agents whereas hypersensitive to others. The sensitivity of certain resistant strains to other cytotoxic agents suggests that our findings may point to particular drug combinations that can overcome resistance caused by inactivation of specific genes.

Oxaliplatin, a Potent Inhibitor of Survivin, Enhances Paclitaxel-induced Apoptosis and Mitotic Catastrophe in Colon Cancer Cells

BACKGROUND

Clinical studies have demonstrated that oxaliplatin, a novel platinum derivative, is a potent chemotherapeutic agent, especially when combined with other reagents. The aim of the present study was to explore the mechanism of such action.

METHODS

Using colon cancer cell lines, we examined changes in cell cycle, apoptosis and mitotic catastrophe induced by oxaliplatin and/or paclitaxel.

RESULTS

Oxaliplatin at its IC(50) induced apoptosis and cell cycle arrest at G(2)-M phase. Western blot analyses indicated that oxaliplatin decreased mitosis-commencing protein cdc2 and anti-apoptotic proteins, phospho-Bcl(2) and Bcl-xl in the three colon cancer cells tested. Since cdc2 stabilizes survivin, a putative IAP (inhibitor of apoptosis) family member, through phosphorylation of Thr34, we examined the level of survivin and found a marked decrease due to oxaliplatin. This finding is of particular interest because survivin is a promising molecular target against various human cancers and a key molecule involved in both apoptosis and mitotic catastrophe. When used in combination with paclitaxel (taxol), a putative apoptosis-inducing reagent, the isobologram indicated that the taxol-oxaliplatin sequence or taxol plus oxaliplatin had synergic or additive effects, while the oxaliplatin-taxol sequence resulted in a prominent antagonism. The taxol-oxaliplatin sequence caused marked growth inhibition of DLD1 and SW480 cells, possibly due to upregulation of apoptotic and non-apoptotic pathways, respectively. Morphological surveys indicated that the non-apoptotic process could be mitotic catastrophe.

CONCLUSION

Our results suggest that oxaliplatin that potently inhibited survivin may exert outstanding cytotoxic effects when combined with certain chemoreagents through enhancement of apoptosis and mitotic catastrophe.

Phase II trial of cisplatin, tegafur plus uracil and leucovorin as neoadjuvant chemotherapy in patients with squamous cell carcinoma of the oropharynx and hypopharynx

We evaluated the efficacy and toxicity of cisplatin, tegafur plus uracil and leucovorin as neoadjuvant chemotherapy for locally advanced squamous cell carcinoma (SCC) of the oropharynx and hypopharynx. Forty-six patients (stage IV, 83%; N2/3, 52%) were treated with PUL (50 mg/m2 cisplatin on day 1, 300 mg/m2 tegafur plus uracil orally and 60 mg leucovorin orally on days 1-14) over a 14-day cycle. Evaluation after 3 cycles led to chemotherapy termination if primary tumor responses were less than partial responses. Otherwise, PUL was continued up to 6 cycles before locoregional therapy. Patients achieving at least good partial responses at the primary site after neoadjuvant chemotherapy received radiotherapy for organ preservation. Chemotherapy responses were analyzed by intent-to-treat. Response rates of primary sites were 71.7% (33 of 46) with 34.8% (16 of 46) showing a complete response. Thirty patients (65.2%) achieved good partial responses at the primary site. Overall response and complete response rates of neck lymph nodes were 68.6% (24 of 35) and 25.7% (nine of 35). The combined response rate of primary site and neck lymph nodes was 63% (95% confidence interval 48.5-77.5%) with a complete response rate of 15.2%. Toxicities of WHO grade 3-4 included anemia (19.6%), diarrhea (17.4%) and neutropenia (8.7%). With a median follow-up of 36 months, overall survival and disease-free survival rates were 45.7% (21 of 46) and 41.3% (19 of 46); organ preservation rate was 90% (19 of 21). We concluded that the outpatient PUL regimen was a moderately effective, less-toxic neoadjuvant chemotherapy for SCC of the oropharynx and hypopharynx. PUL should be studied further with other active agents or radiotherapy.

Effect of capecitabine on mean corpuscular volume in patients with metastatic breast cancer

Capecitabine is a novel oral chemotherapy agent designed to generate 5-fluorouracil (5-FU) preferentially in tumor tissue, and is the most effective therapy for anthracycline and taxane-resistant breast cancer. Macrocytosis has not been previously reported in association with capecitabine therapy. We performed a retrospective review of consecutive metastatic breast cancer (MBC) patients receiving standard 21-day cycles of oral capecitabine therapy at a single center during the year 2000. Patients were assessed prior to each cycle with clinical examinations and complete blood counts. Seventy-six women (median age 52 years, median follow-up 273 days) met inclusion criteria for the study. Prior to treatment, the average mean corpuscular volume (MCV) was 91.6 fl (normal range 80-100 fl). During chemotherapy, MCV increased in a dose-dependent and time-dependent manner. Fifty-seven percent of study patients developed macrocytosis (MCV > 100 fl) while on capecitabine therapy; 85% of women who received at least nine cycles of therapy exhibited macrocytosis. Development of macrocytosis was independent of anemia, thrombocytopenia, neutropenia, liver metastasis, and hepatic dysfunction; however, increases in MCV were more pronounced in 5-FU-naive patients. Alternative causes of macrocytosis were not identified in patients without coexisting anemia. We conclude that capecitabine therapy produces time-dependent and dose-dependent macrocytosis in MBC patients. However, macrocytosis was not associated with anemia or overt myelosuppression. When capecitabine-treated breast cancer patients develop macrocytosis in the absence of anemia, investigations of other causes of macrocytosis are not warranted.

Cisplatin, tegafur, and leucovorin: a moderately effective and minimally toxic outpatient neoadjuvant chemotherapy for locally advanced squamous cell carcinoma of the head and neck

BACKGROUND

To evaluate the efficacy and toxicity of cisplatin, tegafur, and leucovorin as neoadjuvant chemotherapy (CT) for patients with advanced, nonmetastatic squamous cell carcinoma of the head and neck (SCCHN).

METHODS

Patients with SCCHN according to World Health Organization (WHO) performance status of 2 or less and adequate organ function were enrolled. The CT regimen (PTL) was 50 mg/m(2) cisplatin (P) on Day 1, 800 mg per day oral tegafur (T), and 60 mg per day oral leucovorin (L) for 14 days. The CT was administered at outpatient clinics for 14-day cycles. PTL was initiated with the intent of organ preservation and it was continued for a maximum of six cycles before locoregional therapy. Reevaluation after three cycles led to the termination of CT when the response was less than a partial response. CT was discontinued immediately upon evidence of tumor progression or excessive toxicity.

RESULTS

From March 1996 through July 1999, 97 patients were enrolled consecutively. All participants were men with a median age of 56 years (range, 37-70 years). The primary tumor sites were the tongue base, 14, and the hypopharynx, 83. Sixteen percent of the tumors were Stage III, 84% were Stage IV, 62% were Stage T4, and 44% were Stage N2-3. The median number of CT cycles was six. On an intent-to-treat basis, 26 patients (27%) achieved complete responses and 32 patients (33%) achieved partial responses. The overall response rate was 60% (95% confidence interval, 50-70%). The most common toxicities of WHO Grade 3 or higher included (percent of patients): anemia, 8.3%; stomatitis, 6.3%; thrombocytopenia, 3.1%; and vomiting, 3.1%. With a median follow-up period of 3 years, the overall survival and disease-free survival rates were 40% and 38%, respectively. Organ preservation was achieved in 70% (29 of 37) of the surviving patients.

CONCLUSION

The outpatient PTL regimen was a moderately effective and minimally toxic CT for SCCHN. PTL should be studied further in combination with other active agents or radiotherapy for patients with SCCHN.

High-Dose Fluorouracil and Leucovorin: Weekly Continuous Infusions for Metastatic Colorectal Cancer

The increasing complexity of cancer chemotherapy makes it mandatory that pharmacists be familiar with these highly toxic agents. This column reviews various issues related to the preparation, dispensing, and administration of cancer chemotherapy, both commercially available and investigational.

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.

Pharmacology of fluorinated pyrimidines: eniluracil

The pharmacological inactivation of dihydropyrimidine dehydrogenase (DPD) represents one strategy to improve 5-FU therapy, which historically has been associated with unpredictable pharmacological behavior and toxicity. This is principally due to high interpatient differences in the activity of DPD, the enzyme that mediates the initial and rate-limiting step in 5-FU catabolism. By inactivating DPD and suppressing the catabolism of 5-FU, eniluracil has dramatically altered the pharmacological profile of 5-FU. The maximum tolerated dose of oral 5-FU given with oral eniluracil (1.0 to 25 mg/m2) is substantially lower than conventional 5-FU doses. In the presence of eniluracil, bioavailability of 5-FU has increased to approximately 100%, the half-life is prolonged to 4 to 6 hours, and systemic clearance is reduced > 20-fold to values comparable the glomerular filtration rate (46 to 58 mL/min/m2). Renal excretion (approximately 45% to 75%), instead of DPD-related catabolism, is the principal route of elimination of oral 5-FU given with eniluracil. Chronic daily administration of oral 5-FU 1.0 mg/m2 twice daily with eniluracil 20 mg twice daily produces 5-FU steady-state concentrations (8-38 ng/mL) similar to those achieved with protracted intravenous administration on clinically relevant dose-schedules. On a daily x 5 regimen, higher 5-FU AUC values are related to neutropenia, whereas elevated 5-FU AUC and steady-state concentrations are related to diarrhea when oral 5-FU is given daily with eniluracil on a chronic schedule. The pharmacokinetic behavior of oral eniluracil is similar to that for oral 5-FU. Administration of eniluracil 10 to 20 mg twice daily completely inactivates DPD activity both in peripheral blood mononuclear cells and in colorectal tumor tissue, and prolonged inhibition of DPD after discontinuation of eniluracil treatment has been noted. In the presence of eniluracil, oral administration of 5-FU is feasible and variation in 5-FU exposure is reduced, with the anticipation of further reduction in variation as dosing guidelines based on renal function are formulated.

Phase I and pharmacologic study of oral fluorouracil on a chronic daily schedule in combination with the dihydropyrimidine dehydrogenase inactivator eniluracil

PURPOSE

To determine the maximum-tolerated dose (MTD), toxicities, and pharmacokinetics of oral fluorouracil (5-FU) administered twice daily in combination with oral eniluracil, an inactivator of dihydropyrimidine dehydrogenase, administered for 28 days every 35 days.

PATIENTS AND METHODS

Oral 5-FU 1.35 mg/m(2) twice daily was administered with oral eniluracil 10 mg daily for 14 to 28 days, followed by a 1-week rest period. Eniluracil was started 1 day before 5-FU. Patients then received escalated doses of oral 5-FU 1. 35 to 1.8 mg/m(2) twice daily with an increased dose of eniluracil 10 mg twice daily for 28 days. A reduced dose of 5-FU 1.0 mg/m(2) with eniluracil 20 mg twice daily was evaluated.

RESULTS

Thirty-six patients with solid malignancies were enrolled onto the study. Diarrhea was the principal dose-limiting toxicity of oral 5-FU and eniluracil given on this chronic schedule. The recommended phase II dose is 5-FU 1.0 mg/m(2) twice daily with eniluracil 20 mg twice daily. Mean (SD) values for terminal half-life, apparent volume of distribution, and systemic clearance of 4.5 hours (0.83 hours), 19 L/m(2) (3.0 L/m(2)), and 51 mL/min/m(2) (13 mL/min/m(2)), respectively. An average of 77% of 5-FU was excreted unchanged in urine after 28 days of treatment. The mean (range) 5-FU C(SS,min) values achieved at the 1.0 mg/m(2) dose level were 22 ng/mL (8 to 38 ng/mL).

CONCLUSION

Chronic oral administration of 5-FU with oral eniluracil is tolerable and produces 5-FU steady-state concentrations similar to those achieved with protracted intravenous administration of 5-FU on clinically relevant dose schedules. Eniluracil provides an attractive means of administering 5-FU on protracted schedules.

Continuous infusion of chemotherapy: focus on 5-fluorouracil and fluorodeoxyuridine

Continuous infusion of chemotherapy is one of the developments to try to improve the treatment of metastatic cancer. There is a sound theoretical rationale to deliver cytotoxic drugs as a continuous infusion. Furthermore, the development of reliable venous access devices and portable infusion pumps enables patients to be treated in an ambulatory setting. This review focuses on the continuous infusion of the most frequently used drugs: 5-fluorouracil (5-FU) and fluorodeoxyuridine (FUDR). An overview is given of both preclinical studies and studies in humans. Continuous infusion of 5-FU and FUDR has proven to be feasible in all studies. However, the results (response rate and especially survival) are rather disappointing. So far, continuous infusion of cytostatic drugs can still be considered as an experimental procedure. Whether protracted, intermittent of circadian modulated continuous infusion is the optimal treatment schedule has still to be proven in future studies. Furthermore, studies are needed to demonstrate whether dose intensity for most tumours is important for treatment outcome. Also, studies are needed to investigate quality of life and economic issues.

Effect of cisplatin in advanced colorectal cancer resistant to 5-fluorouracil plus (S)-leucovorin

Modulation of 5-fluorouracil (5-FU) is currently being investigated in advanced colorectal cancer. In an attempt to improve the results obtainable for the association of 5-FU and leucovorin, we decided to add cisplatin to 5-FU and (6S)-leucovorin (S-LV) after disease progression. The hypothesis was that a pharmacological enhancement of the efficacy of 5-FU would result in responses in 5-FU-unresponsive patients or in a second response in previously responding patients. A group of 28 5-FU+S-LV-pretreated patients, with advanced measurable colorectal cancer, were treated with 80 mg/m2 cisplatin on day 1, 80 mg/m2 S-LV and 370 mg/m2 5-FU as an i. v. bolus for 5 consecutive days every 4 weeks. We obtained 3 partial responses (response rate: 11 +/- 11%), while 11 patients had stable disease (39 +/- 18%). Among the 3 responders, 1 patient had earlier achieved a partial response, a second stable disease and 1 had disease progression after the previous 5-FU+S-LV treatment. The median survival time for all 28 patients was 11 months. Toxicity was minimal and consisted of mild and reversible gastrointestinal symptoms and myelosuppression. We believe that further studies must be carried out to establish the real impact of the synergism between cisplatin, 5-FU and S-LV in untreated patients.