Dihydropyrimidine dehydrogenase activity and fluorouracil chemotherapy

Treatment efficacy of low-dose 5-fluorouracil with ultrasound in mediating 5-fluorouracil-loaded microbubble cavitation in head and neck cancer

Over the past 50 years, 5-fluorouracil (5-FU) has played a critical role in the systemic chemotherapy of cancer patients. Bolus intravenous (IV) 5-FU infusion has been used due to the limitation of its extremely short half-life (10-15 min). This study used ultrasound (US) mediating 5-FU-loaded microbubbles (MBs) cavitation as a tool to increase local intratumoral 5-FU levels with a reduced dose of 5-FU (a single IV injection of 2.5 mg/kg instead of a single intraperitoneal injection of 25-200 mg/kg as used in previous studies in mice). The 5-FU-MBs were prepared with a 132 mg/mL albumin solution and a 0.30 mg/mL 5-FU solution. The diameters of the MBs and 5-FU-MBs were 1.24 ± 0.85 and 2.00 ± 0.53 µm (mean ± SEM), respectively, and the maximum loading efficiency of 5-FU on MBs was 19.04 ± 0.25%. In the in vitro study, the cell viabilities of 5-FU and 5-FU-MBs did not differ significantly, but compared with the 5-FU-MBs treatment-alone group, cell toxicity increased to 31% in the 5-FU-MBs + US group (p < 0.001). The biodistribution results indicated that the 5-FU levels of the tumors in small animals were significant higher for the 5-FU-MBs + US treatment than for either the 5-FU-MBs or 5-FU treatment with low 5-FU systemic treatment doses (2.5 mg/kg 5-FU IV). In small-animal treatment, 2.5 mg/kg 5-FU therapeutic IV doses injected into mice caused a more-significant reduction in tumor growth in the 5-FU-MBs + US group (65.9%) than in the control group after 34 days of treatment.

Pharmacokinetic variables of medium molecular weight cross linked chitosan nanoparticles to enhance the bioavailability of 5-fluorouracil and reduce the acute oral toxicity

To prepare glutaraldehyde-based cross-linked medium molecular weight chitosan nanoparticles encapsulated with 5-Fluorouracil (5-FU), to overcome dosing frequency as well as reducing acute oral toxicity and poor bioavailability of the drug. Medium molecular weight chitosan nanoparticles (MMWCH-NPs) were prepared by reverse micelles method based on glutaraldehyde (GA) cross-linking and optimized by the process as well as formulation variables like a various drug to polymer ratio, cross-linker volumes, varying stirring speeds (rpm), different time of rotation/stirring, respectively and their effects on the mean particles size distribution and entrapment efficiency %EE and %LC of NPs. Characterization of formulations was done by FTIR studies, TEM, PXRD, TGA, Stability, and dissolution drug release studies were performed by dialysis bag technique at both pH (1.2 & 7.4) and acute oral toxicity studies in albino rabbits. The formulated nanoparticles showed a smooth morphology with smaller particle size distribution (230–550 nm), zeta potential (−15 to −18 mV) required to achieve enhanced permeation and retention effect (EPR), entrapment efficiency (%EE 12–59%). These NPs exhibited a controlled drug release profile with 84.36% of the drug over a period of 24 h. Drug release data were fitted to different kinetic models which predominantly followed Fickian diffusion mechanism (R² = 0.972–0.976, N = 0.326–0.256). The optimized formulation (5-FU6) was observed under DSC/TGA, TEM. PXRD curves, FTIR, which confirmed thermal stability, structural integrity, amorphous state, compatibility between drug and polymer of optimized (5-FU6) as well as reduced acute oral toxicity in albino rabbits. Cross-linked medium molecular weight chitosan nanoparticles are nontoxic, well-tolerated therefore could be the future candidate for therapeutic effects as novel drug delivery carrier for anticancer drug(s).

Oral drugs in the treatment of metastatic colorectal cancer

Colorectal cancer (CRC) is one of the most common forms of cancer, with an estimated 1.36 million new cases and almost 700,000 deaths annually. Approximately 21% of patients with CRC have metastatic disease at diagnosis. The objective of this article is to review the literature on the efficacy and safety of oral drugs available for the treatment of metastatic colorectal cancer (mCRC). Several such drugs have been developed, and fluoropyrimidines are the backbone of chemotherapy in this indication. They exert their antitumour activity by disrupting the synthesis and function of DNA and RNA. Oral fluoropyrimidines include prodrugs capecitabine, tegafur, eniluracil/5-fluorouracil, tegafur/uracil, tegafur/gimeracil/oteracil and trifluridine/tipiracil (FTD/TPI). Oral drugs offer several advantages over injectable formulations, including convenience, flexibility, avoidance of injection-related adverse events (AEs) and, in some circumstances, lower costs. However, oral drugs may not be suitable for patients with gastrointestinal obstruction or malabsorption, they may result in reduced treatment adherence and should not be co-administered with drugs that interfere with absorption or hepatic metabolism. Oral fluoropyrimidines such as capecitabine, as monotherapy or in combination with oxaliplatin, irinotecan or bevacizumab, are as effective as intravenous 5-fluorouracil (5-FU) in first-line treatment of mCRC. Other oral fluoropyrimidines, such as FTD/TPI, are effective in patients with mCRC who are refractory, intolerant or ineligible for 5-FU. In addition, oral fluoropyrimidines are used in adjuvant treatment of mCRC. Regorafenib is an oral multikinase inhibitor used in patients in whom several previous lines of therapy have failed. Frequent AEs associated with oral drugs used in the treatment of CRC include hand-foot syndrome and gastrointestinal and haematological toxicities.

Evaluation of the 5-fluorouracil plasma level in patients with colorectal cancer undergoing continuous infusion chemotherapy

5-Fluorouracil (5-FU) dosing has traditionally been based on the body surface area (BSA) in colorectal cancer treatment. However, there is accumulating evidence that dosing based on BSA may be of limited use. The purpose of the present study was to evaluate the changes in 5-FU plasma levels and tumor response as well as the severity of adverse events in patients with cancer treated with 5-FU combined chemotherapy. The dosing amount of 5-FU was determined based on the BSA. Blood samples were collected, and 5-FU plasma levels in 15 patients with colorectal cancer were measured three times (0, 22 and 40 h before and after the start of infusion) during constant-infusion of 5-FU for 46 h by an immunoassay. 5-FU plasma levels were significantly higher at 22 and 40 h compared with at 0 h (P<0.001), when all 15 patients were analyzed. Notably, the tumor response of the partial response/stable disease group showed significant increases in 5-FU plasma levels at 40 h compared with at 22 h (P<0.01), while the progressive disease group showed no significant increase. In addition, the 5-FU plasma level in the adverse event level of grade ≥2 was higher than that of grade <2 at 40 h after the start of infusion. Collectively, these observations indicated that during continuous infusion of 5-FU, the 5-FU plasma level increased significantly, and the tumor response (such as partial response, stable or progressive disease) may be influenced by the increase of 5-FU plasma level from the start of infusion. Therefore, the 5-FU plasma level may be a predictive factor for maximizing the tumor response and minimizing the risk of severe adverse events.

Reviewing two decades of nanomedicine implementations in targeted treatment and diagnosis of pancreatic cancer: An emphasis on state of art

Pancreatic cancer is nowadays the most life-threatening cancer type worldwide. The problem of poor diagnosis, anti-neoplastics resistance and biopharmaceutical drawbacks of effective anti-cancer drugs lead to worsen disease state. Nanotechnology-based carrier systems used in both imaging and treatment procedures had solved many of these problems. It is critical to develop advanced detection method to save patients from being too late diagnosed. Targeting the pancreatic cancer cells as well helped in decreasing the side effects associated with normal cells destruction. Drug resistance is another challenge in pancreatic cancer management that can be solved by thorough understanding of the microenvironment associated with the disease to design creative nanocarriers. This is the first article to review multifaceted approaches of nanomedicine in pancreatic cancer detection and management. Additionally, mortality rates in selected Arab and European countries were illustrated herein. An emphasis was given on therapeutic and diagnostic challenges and different nanotechnologies adopted to overcome. The four main approaches encompassed nanomedicine for herbal treatment, nanomedicine of synthetic anti-cancer drugs, metal nanoparticles as a distinct treatment policy and nanotechnology for cancer diagnosis. Future research perspectives have been finally proposed.

5-Fluorouracil Loaded Chitosan-PVA/Na+MMT Nanocomposite Films for Drug Release and Antimicrobial Activity

In the present study, chitosan and polyvinyl alcohol (PVA) were blended with different concentrations of sodium montmorillonite (Na+MMT) clay solution by a solvent casting method. X-ray diffraction and transition electron microscope results show that the film properties are related to the co-existence of Na+MMT intercalation/exfoliation in the blend and the interaction between chitosan-PVA and Na+MMT. 5-Fluorouracil (5-FU) was loaded with chitosan-PVA/Na+MMT nanocomposite films for in vitro drug delivery study. The antimicrobial activity of the chitosan-PVA/Na+MMT films showed significant effect against Salmonella (Gram-negative) and Staphylococcus aureus (Gram-positive), whereas 5-FU encapsulated chitosan-PVA/Na+MMT bio-nanocomposite films did not show any inhibition against bacteria. Our results indicate that combination of a flexible and soft polymeric material with high drug loading ability of a hard inorganic porous material can produce improved control over degradation and drug release. It will be an economically viable method for preparation of advanced drug delivery vehicles and biodegradable implants or scaffolds.

Self-Assembling Monomeric Nucleoside Molecular Nanoparticles Loaded with 5-FU Enhancing Therapeutic Efficacy against Oral Cancer

Conventional oligonucleotide based drug delivery systems suffer from lengthy synthetic protocols, high cost, and poor chemical or enzymatic stability under certain circumstances. Canonical free individual nucleosides cannot form stable nanostructures in aqueous solution as drug vehicles. Here, we report the development of a monomeric self-assembled nucleoside nanoparticle (SNNP) into an efficient drug delivery system which has currently no parallel in such field. This was achieved using a l-configurational pyrimido[4,5-d]pyrimidine nucleoside building block that can form robust discrete nanoparticles in just one step with water as the sole solvent. Its high biocompatibility and low toxicity was demonstrated in vitro and in vivo. In mouse xenograft model of oral squamous cell carcinoma (OSCC), SNNP loaded with 5-fluoro-uracile (5-FU-SNNP) remarkably retarded the tumor growth compared with free 5-FU, albeit SNNP alone showed no antitumor effect. The stability in blood circulation and the effective concentration of 5-FU in tumor tissue were increased upon the loading with SNNP. TUNEL and immunohistochemistry analyses further indicated that the superior in vivo antitumor efficacy of 5-FU-SNNP compared to free 5-FU was associated with an enhanced degree of inhibition of cell proliferation and stimulation of cell apoptosis. Furthermore, SNNP alleviated the toxic side effects of 5-FU. These findings suggested that when loaded with SNNP, 5-FU has better antitumor efficacy and lower side effects, indicating that SNNP can efficiently act as a readily accessible, robust, biocompatible and low-toxic nanobiomaterial which may find wide therapeutic applications clinically in the future.

Evaluation of 5-fluorouracil metabolic enzymes as predictors of response to adjuvant chemotherapy outcomes in patients with stage II/III colorectal cancer: a decision-curve analysis

BACKGROUND

The effectiveness of 5-fluorouracil (5-FU)-based adjuvant chemotherapy is reported in patients with colorectal cancer (CRC), but the usefulness of 5-FU metabolic enzymes as predictive biomarkers of the efficacy of this chemotherapy remains unclear.

OBJECTIVE

This study aims to verify whether 5-FU metabolic enzymes are predictive biomarkers in the clinical setting of adjuvant chemotherapy for stage II/III CRC.

METHODS

In total, 179 patients with stage II/III CRC who were treated at our institute between 2000 and 2010 were enrolled. Messenger RNA (mRNA) expression of major 5-FU metabolic enzymes, namely thymidylate synthase, dihydropyrimidine dehydrogenase, thymidine phosphorylase (TP), orotate phosphoribosyl transferase, and β-actin (control) was evaluated using the Danenberg Tumor Profile method. mRNA expression and other clinicopathological data were investigated with regard to CRC relapse.

RESULTS

A total of 78 patients underwent surgery alone, while 101 underwent adjuvant chemotherapy (5-FU plus leucovorin [LV] or tegafur plus uracil /LV) following surgery. Relapse-free survival was longer and risk of recurrence was lower in association with high TP mRNA expression than in association with low TP mRNA expression in the adjuvant chemotherapy group (hazard ratio 0.66; 95 % confidence interval 0.47-0.92; p = 0.016), but not in the surgery alone group. mRNA expression of no other enzymes was associated with relapse in both groups. In decision-curve analyses, the predictive efficiency of TP mRNA expression plus clinicopathological factors was slightly better than that of clinicopathological factors only.

CONCLUSIONS

TP mRNA expression in tumors predicted the effects of adjuvant chemotherapy for stage II/III CRC, although the beneficial effects were marginal.

Supramolecular assemblies constructed from β-cyclodextrin-modified montmorillonite nanosheets as carriers for 5-fluorouracil

5-Fluorouracil-loaded supramolecular assemblies formed from self-assembling β-cyclodextrin modified montmorillonite nanosheets exhibit better antitumor activity and lower cytotoxicity in vitro.

Herbal medicine Guan Chang Fu Fang enhances 5-fluorouracil cytotoxicity and affects drug-associated genes in human colorectal carcinoma cells

Guan Chang Fu Fang (GCFF) is a natural compound, which is extracted from three medicinal plants, Agrimonia pilosa Ledeb., Patrinia scabiosaefolia and Solanum nigrum L. GCFF has demonstrated clinical efficacy in the treatment of colon cancer. At present, 5-fluorouracil (5-FU) is the primary active chemotherapeutic agent used for treating colon cancer. Using median-effect and apoptosis analyses, fluorescence microscopy and western blotting, the present study analyzed the association between GCFF and 5-FU in the human colon adenocarcinoma LoVo cell line. The effect of GCFF on the expression of chemotherapeutic agent-associated genes was also investigated. The results of the synergistic analysis revealed that GCFF exhibited a significant effect upon 5-FU-associated cytotoxicity within the LoVo cell line. This effect was observed over a broad dose-inhibition range (5–95%), but was particularly significant in the lower concentrations. The flow cytometry results revealed that low doses of GCFF or 5-FU induced S-phase arrest, as did a low-dose combination of the two drugs. After 48 h, GCFF significantly suppressed the expression levels of the chemotherapeutic agent resistance-associated genes within the colon cancer cells. The western blot analysis revealed that the combined effects of 5-FU and GCFF were due to a regulation of the B-cell lymphoma-2 family of proteins. The findings of the present study suggested that GCFF, when combined with 5-FU, has the potential to be a novel, chemotherapeutic compound for the treatment of colon cancer.

Successful curative resection of gallbladder cancer following S-1 chemotherapy: A case report and review of the literature

The symptoms of gallbladder cancer (GBC) are vague and non-specific. Therefore, GBC is often detected at an advanced or metastatic stage. The most effective treatment for GBC is surgical resection, however the majority of GBC cases are unresectable at the time of diagnosis. Therefore, numerous GBC patients undergo chemotherapy. This study reports the case of a 60-year-old female with GBC who underwent successful surgical curative resection following a single dose of the chemotherapeutic agent, S-1, twice daily for 4 weeks followed by a 14-day rest period for 36 months. S-1 is a novel orally administered drug composed of a combination of the 5-fluorouracil (5-FU) prodrug, tegafur, 5-chloro-2,4-dihydroxypyridine (CDHP) and oteracil potassium in a 1:0.4:1 molar concentration ratio. The focus of the present study was the candidate factors that affect the therapeutic efficacy of S-1-based chemotherapy. In particular, the gene expression involved in the S-1 metabolic pathway was investigated by assessing the intratumoral dihydropyrimidine dehydrogenase (DPD), thymidylate synthase (TS) and orotate phosphoribosyltransferase gene expression. The surgical specimen exhibited high intratumoral DPD gene expression levels compared with those observed in previously reported non S-1 responsive cases of biliary tract cancer. Due to the results obtained in the current study, we hypothesize that CDHP enhanced the antitumor efficacy of 5-FU by inhibiting the excess DPD protein produced by the tumor.

Fluoropyrimidine toxicity in patients with dihydropyrimidine dehydrogenase splice site variant: the need for further revision of dose and schedule

Dihydropyrimidine dehydrogenase (DPD) is a key enzyme in the metabolic catabolism of 5-fluorouracil (5-FU) and its derivatives (capecitabine and tegafur). Complete or partial deficiency of DPD activity has been demonstrated to induce severe toxicities in cancer patients treated with fluoropyrimidine therapy. We analyzed 180 individuals that were candidates for a treatment with 5-FU class drugs for the most common DPD mutation, IVS14+1G>A, and detected four heterozygous patients. We recorded the toxicities for all 180 individuals after the first two chemotherapy cycles and found that three of the four patients, although they were treated with a dose reduction in 50 % on the basis of the genetic analysis, all showed severe toxicities that resulted in hospitalization of patient and premature discontinuation of treatment. One patient with mutated DPD was not treated with chemotherapy upon the clinician's decision because of his DPD mutated genotype and the presence of microsatellite instability. Our data suggest that greater dose reductions or alternative therapies are needed for patients with DPD IVS14+1G>A mutations.

Pharmacokinetic evaluation of novel oral fluorouracil antitumor drug S-1 in Chinese cancer patients

AIM

S-1 is an oral anticancer fluoropyrimidine formulation consisting of tegafur, 5-chloro-2,4-dihydroxypyridine and potassium oxonate. The aim of this study was to evaluate the pharmacokinetics and bioequivalence of a newly developed generic formulation of S-1 in Chinese cancer patients in comparison with the branded reference formulation of S-1.

METHODS

A single-dose, randomized-sequence, open-label, two-way self-crossover study was conducted in 30 Chinese cancer patients. The subjects alternatively received the two formulations (40 mg/m(2), po) with a 7-d interval. Plasma concentrations of FT, CDHP, Oxo, and 5-Fu were determined using LC-MS/MS. Pharmacokinetic parameters, including Cmax, Tmax, t1/2, AUC0-t, and AUC0-∞ were determined using non-compartmental models with DAS2.0 software. Bioequivalence of the two formulations were to be evaluated according to 90% CIs for the log-transformed ratios of AUC and Cmax of S-1. Adverse events were evaluated through monitoring the symptom, physical and laboratory examinations, ECGs and subject interviews.

RESULTS

The mean values of Cmax, AUC0-t, and AUC0-∞ of FT, 5-Fu, CDHP, and Oxo for the two formulations had no significant differences. The 90% CIs for natural log-transformed ratios of Cmax, AUC0-t, and AUC0-∞ were within the predetermined bioequivalence acceptance limits. A total of 11 mild adverse events, including fatigue, nausea and vomiting, anorexia, diarrhea and myelosuppression, were observed, and no serious and special adverse events were found.

CONCLUSION

The newly developed generic formulation and reference formulation of S-1 have similar pharmacokinetics with one dose (40 mg/m(2)) in Chinese cancer patients. Both the formulations of S-1 are well tolerated.

Pharmacokinetics of the perioperative use of cancer chemotherapy in peritoneal surface malignancy patients

Background. The peritoneal surface is an acknowledged locoregional failure site of abdominal malignancies. Previous treatment attempts with medical therapy alone did not result in long-term survival. During the last two decades, new treatment protocols combining cytoreductive surgery with perioperative intraperitoneal and intravenous cancer chemotherapy have demonstrated very encouraging clinical results. This paper aims to clarify the pharmacologic base underlying these treatment regimens. Materials and Methods. A review of the current pharmacologic data regarding these perioperative chemotherapy protocols was undertaken. Conclusions. There is a clear pharmacokinetic and pharmacodynamic rationale for perioperative intraperitoneal and intravenous cancer chemotherapy in peritoneal surface malignancy patients.

Layered inorganic nanocomposites: a promising carrier for 5-fluorouracil (5-FU)

We report here the intercalation of 5-fluorouracil (5-FU), an anticancer drug in interlayer gallery of Na(+) clay (Montmorillonite, MMT), with the assistance of biopolymer (chitosan, CS). The X-ray diffraction patterns, thermal and spectroscopic analyses indicated the drug intercalation into the clay interlayer space in support of CS and stabilized in the longitudinal monolayer by electrostatic interaction. In vitro drug release showed controlled release pattern. The genotoxic effect of drug was in vitro evaluated in human lymphocyte cell culture by comet assay, and results indicated significant reduction in DNA damage when drug was intercalated with clay and formulated in composites. The results of in vitro cell viability assay in cancer cells pointed at decreased toxicity of drug when encapsulated in Na(+)-clay plates than the pristine drug. In vivo pharmacokinetics, biodistribution, hepatotoxicity markers, e.g., SGPT and SGOT, and liver/testicular histology in rats showed plasma/tissue drug levels were within therapeutic window as compared to pristine drug. Therefore, drug-clay hybrid and composites can be of considerable value in chemotherapy of cancer with reduced side effects.

Development and characterization of hyaluronic acid decorated PLGA nanoparticles for delivery of 5-fluorouracil

The present investigation was aimed to develop and explore the prospective of engineered PLGA nanoparticles as vehicles for targeted delivery of 5-fluorouracil (5-FU). Nanoparticles of 5-FU-loaded hyaluronic acid-poly(ethylene glycol)-poly(lactide-co-glycolide) (HA-PEG-PLGA-FU) copolymer were prepared and characterized by FTIR, NMR, transmission electron microscopy, particle size analysis, DSC, and X-ray diffractometer measurement studies. The nanoparticulate formulation was evaluated for in vitro release, hemolytic toxicity, and hematological toxicity. Cytotoxicity studies were performed on Ehrlich ascites tumor (EAT) cell lines using MTT cell proliferation assay. Biodistribution studies of 99m Tc labeled formulation were conducted on EAT-bearing mice. The in vivo tumor inhibition study was also performed after i.v. administration of HA-PEG-PLGA-FU nanoparticles. The HA conjugated formulation was found to be less hemolytic but more cytotoxic as compared to free drug. The hematological data suggested that HA-PEG-PLGA-FU formulation was less immunogenic compared to plain drug. The tissue distribution studies displayed that HA-PEG-PLGA-FU were able to deliver a higher concentration of 5-FU in the tumor mass. In addition, the HA-PEG-PLGA-FU nanoparticles reduced tumor volume significantly in comparison with 5-FU. Thus, it was concluded that the conjugation of HA imparts targetability to the formulation, and enhanced permeation and retention effect ruled out its access to the non-tumor tissues, at the same time favored selective entry in tumors, thereby reducing the side-effects both in vitro and in vivo.

Associations of various gene polymorphisms with toxicity in colorectal cancer patients receiving oral uracil and tegafur plus leucovorin: a prospective study

BACKGROUND

To assess the predictive value of polymorphism in nine genes, primarily thymidylate synthase (TS) and orotate phosphoribosyltransferase (OPRT), which relates to 5-fluorouracil (5-FU) metabolism, for toxicity in patients treated with oral uracil/tegafur (UFT) plus leucovorin (LV).

PATIENTS AND METHODS

We treated 99 patients with stage II or III colorectal carcinoma with oral UFT + LV. Germline DNA from patients was genotyped for 5-FU and folate metabolism-relating genes. CYP2A6, tegafur-activating enzyme, and uridine diphosphate-glucuronosyltransferase 1A1 genetic variation were also assessed. Toxicity was graded by the National Cancer Institute Common Toxicity Criteria, version 2.0.

RESULTS

The multivariate logistic regression revealed that OPRT 638G>C polymorphism was associated with grade 3 diarrhea [odds ratio (OR) 19.84 for patients with the C/C homozygous type compared with patients with wild type, P = 0.014] and polymorphisms of UGT1A1 were associated with hyperbilirubinemia (OR 38.76 for homozygotes and double heterozygotes of *6 or *28 compared with wild type, P = 0.0008). No relationships were observed between TS polymorphisms and any toxicity.

CONCLUSIONS

OPRT polymorphism predicts toxicity, especially grade 3 or greater diarrhea to oral UFT + LV adjuvant chemotherapy, whereas TS does not, in our study cohort. UGT1A1 polymorphism seems to be a risk factor for hyperbilirubinemia due to UFT+LV.

Abdominal irradiation modulates 5-Fluorouracil pharmacokinetics

Background

Concurrent chemoradiation with 5-fluorouracil (5-FU) is widely accepted for treatment of abdominal malignancy. Nonetheless, the interactions between radiation and 5-FU remain unclear. We evaluated the influence of abdominal irradiation on the pharmacokinetics of 5-FU in rats.

Methods

The radiation dose distributions of cholangiocarcinoma patients were determined for the low dose areas, which are generously deposited around the intrahepatic target volume. Then, corresponding single-fraction radiation was delivered to the whole abdomen of Sprague-Dawley rats from a linear accelerator after computerized tomography-based planning. 5-FU at 100 mg/kg was intravenously infused 24 hours after radiation. A high-performance liquid chromatography system equipped with a UV detector was used to measure 5-FU in the blood. Ultrafiltration was used to measure protein-unbound 5-FU.

Results

Radiation at 2 Gy, simulating the daily human treatment dose, reduced the area under the plasma concentration vs. time curve (AUC) of 5-FU by 31.7% compared to non-irradiated controls. This was accompanied by a reduction in mean residence time and incremental total plasma clearance values, and volume of distribution at steady state. Intriguingly, low dose radiation at 0.5 Gy, representing a dose deposited in the generous, off-target area in clinical practice, resulted in a similar pharmacokinetic profile, with a 21.4% reduction in the AUC. This effect was independent of protein binding capacity.

Conclusions

Abdominal irradiation appears to significantly modulate the systemic pharmacokinetics of 5-FU at both the dose level for target treatment and off-target areas. This unexpected and unwanted influence is worthy of further investigation and might need to be considered in clinical practice.

Pharmacokinetic characteristics and anticancer effects of 5-fluorouracil loaded nanoparticles

Background

It is expected that prolonged circulation of anticancer drugs will increase their anticancer activity while decreasing their toxic side effects. The purpose of this study was to prepare 5-fluorouracil (5-FU) loaded block copolymers, with poly(γ-benzyl-L-glutamate) (PBLG) as the hydrophobic block and poly(ethylene glycol) (PEG) as the hydrophilic block, and then examine the 5-FU release characteristics, pharmacokinetics, and anticancer effects of this novel compound.

Methods

5-FU loaded PEG-PBLG (5-FU/PEG-PBLG) nanoparticles were prepared by dialysis and then scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the shape and size of the nanoparticles, and ultraviolet spectrophotometry was used to evaluate the 5-FU in vitro release characteristics. The pharmacokinetic parameters of 5-FU/PEG-PBLG nanoparticles in rabbit plasma were determined by measuring the 5-FUby high-performance liquid chromatography (HPLC). To study in vivo effects, LoVo cells (human colon cancer cell line) or Tca8113 cells (human oral squamous cell carcinoma cell line) were implanted in BALB/c nude mice that were subsequently treated with 5-FU or 5-FU/PEG-PBLG nanospheres.

Results

5-FU/PEG-PBLG nanoparticles had a core-shell spherical structure with a diameter of 200 nm and a shell thickness of 30 nm. The drug loading capacity was 27.1% and the drug encapsulation was 61.5%. Compared with 5-FU, 5-FU/PEG-PBLG nanoparticles had a longer elimination half-life (t_1/2, 33.3 h vs. 5 min), lower peak concentration (C, 4563.5 μg/L vs. 17047.3 μg/L), and greater distribution volume (V_D, 0.114 L vs. 0.069 L). Compared with a blank control, LoVo cell xenografts and Tca8113 cell xenografts treated with 5-FU or 5-FU/PEG-PBLG nanoparticles grew slower and had prolonged tumor doubling times. 5-FU/PEG-PBLG nanoparticles showed greater inhibition of tumor growth than 5-FU (p < 0.01). In the PEG-PBLG nanoparticle control group, there was no tumor inhibition (p > 0.05).

Conclusion

In our model system, 5-FU/PEG-PBLG nanoparticles changed the pharmacokinetic behavior of 5-FU, thus increasing its anticancer activity. 5-Fluorouracil loaded nanoparticles have potential as a novel anticancer drug that may have useful clinical applications.

Prognostic significance of thymidylate synthase, dihydropyrimidine dehydrogenase and thymidine phosphorylase protein expression in colorectal cancer patients treated with or without 5-fluorouracil-based chemotherapy

BACKGROUND

Low tumour expression levels of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD) and thymidine phosphorylase (TP) have been linked with improved outcome for colorectal cancer (CRC) patients treated with 5-fluorouracil (5-FU). It is unclear whether this occurs because such tumours have better prognosis or they are more sensitive to 5-FU treatment.

PATIENTS AND METHODS

Associations between TS, DPD and TP levels, determined by tissue microarrays and immunohistochemistry, and survival was evaluated in 945 CRC patients according to treatment status.

RESULTS

Low TS and DPD expression associated with worse prognosis in stage II [hazard ratio (HR) = 1.69, 95% confidence interval (CI) (1.09-2.63) and HR = 1.92 (95% CI 1.23-2.94), respectively] and stage III CRC patients treated by surgery alone [HR = 1.39 (95% CI 0.92-2.13) and HR = 1.49 (95% CI 1.02-2.17), respectively]. Low TS, DPD and TP associated with trends for better outcome in stage III patients treated with 5-FU [HR = 0.81 (95% CI 0.49-1.33), HR = 0.70 (95% CI 0.42-1.15) and HR = 0.66 (95% CI 0.39-1.12), respectively].

CONCLUSION

Low TS and DPD expression are prognostic for worse outcome in CRC patients treated by surgery alone, whereas low TS, DPD and TP expression are prognostic for better outcome in patients treated with 5-FU chemotherapy. These results provide indirect evidence that low TS, DPD and TP protein expression are predictive of good response to 5-FU chemotherapy.

The CYP2A6*4 allele is determinant of S-1 pharmacokinetics in Japanese patients with non-small-cell lung cancer

S-1 is an oral fluorouracil anticancer drug that contains the 5-FU prodrug tegafur. Tegafur has been shown to be converted enzymatically to 5-FU to exert its antitumor effect, and this conversion is principally catalyzed by CYP2A6. Forty-six non-small-cell lung cancer patients were enrolled. The frequencies of the CYP2A6*4C, CYP2A6*7, and CYP2A6*9 alleles were 17.4, 19.6, and 15.2%, respectively. In the S-1 pharmacokinetic analysis, the area under the concentration-time curve from 0 to 10 h (AUC(0-10)) ratios of 5-FU/tegafur showed large interindividual variabilities, ranging from 5.14 to 112.6. The AUC(0-10) for tegafur was 1.5-fold higher in patients with the CYP2A6*4C allele than in patients without the CYP2A6*4C allele P < 0.05). Furthermore, patients with the CYP2A6*4C allele had a significantly lower maximum plasma concentration (102.6 +/- 32.9 ng/ml) for 5-FU than patients without the CYP2A6*4C allele (157.0 +/- 65.5 ng/ml, P < 0.05). Genotyping of CYP2A6 polymorphisms may provide vital information for effective cancer therapy using S-1.

Orotate phosphoribosyltransferase gene polymorphism predicts toxicity in patients treated with bolus 5-fluorouracil regimen

PURPOSE

We investigated whether the determination of orotate phosphoribosyltransferase (OPRT) and thymidylate synthase (TYMS) polymorphisms could predict the toxicity of 5-fluorouracil (5-FU) in colorectal cancer patients.

EXPERIMENTAL DESIGN

The determination of OPRT and TYMS genotypes were done in genomic DNA extracted from blood by PCR amplification in 69 patients treated with bolus 5-FU as adjuvant chemotherapy. Associations between these polymorphisms and toxicity were evaluated retrospectively.

RESULTS

The Ala allele in OPRT Gly213Ala polymorphism and the two tandem repeats (2R) in TYMS promoter polymorphism were associated with grade 3 to 4 neutropenia and diarrhea. The multivariate logistic regression models revealed that only TYMS promoter polymorphism had an independent value to predict grade 3 to 4 neutropenia [odds ratio, 19.2 for patients with the 2R allele compared with patients with homozygous with the three repeat (3R) alleles], whereas both OPRT and TYMS promoter polymorphisms were independent predictive factors for grade 3 to 4 diarrhea (odds ratio, 13.3 for patients with the Ala allele compared with patients in the Gly/Gly genotype and 11.1 for patients with the 2R allele compared with patients in the 3R/3R genotype). A significant difference was observed in the time to onset of severe toxicity, defined as grade 4 neutropenia and/or grade 3 to 4 gastrointestinal toxicities according to OPRT and TYMS promoter polymorphisms.

CONCLUSION

OPRT Gly213Ala polymorphism seems to be a useful marker for predicting toxicity to bolus 5-FU chemotherapy. Prospective translational treatment trials including larger number of patients are needed to confirm our results.

Prognostic significance of thymidylate synthase expression in patients with prostate cancer undergoing radical prostatectomy

OBJECTIVES

Thymidylate synthase (TS), a key enzyme in DNA synthesis, is overexpressed in a variety of cancer cells. 5-Fluorouracil (5-FU), an anticancer agent used clinically against various cancers, including prostate cancer, inhibits DNA synthesis by binding TS. In this study, we investigated the expression of TS in prostate cancer and its prognostic significance. Its association with the expression of dihydropyrimidine dehydrogenase (DPD), a principal enzyme in the degradation of 5-FU and pyrimidine nucleotides, was also examined.

METHODS

Fifty-two prostatic tissue specimens were obtained from patients who had undergone radical prostatectomy for prostate cancer without neoadjuvant hormonal therapy. We analyzed the cancerous tissue and normal prostatic tissue specimens for TS expression using immunohistochemistry.

RESULTS

TS was expressed at greater levels in the prostate cancer specimens than in the normal prostatic tissue specimens. The patients with prostate cancer with negative TS expression had a longer postoperative recurrence-free rate than did those with positive expression during the 5 years of follow-up. TS expression was significantly decreased in patients who received neoadjuvant hormonal therapy. No relationship was found between the expression of TS and DPD. Patients with prostate cancer with either negative TS or DPD expression had a significantly longer postoperative disease-free rate than those with positive expression of both during the 5 years of follow-up.

CONCLUSIONS

The results of the present study have shown for the first time that TS expression could be a prognostic marker for patients with prostate cancer undergoing radical prostatectomy. In addition, the combination of TS and DPD expression might also be helpful for the prediction of the prognosis of patients with prostate cancer.

Role of thymidine phosphorylase and orotate phosphoribosyltransferase mRNA expression and its ratio to dihydropyrimidine dehydrogenase in the prognosis and clinicopathological features of patients with pancreatic cancer

BACKGROUND

Thymidine phosphorylase (TP), orotate phosphoribosyltransferase (OPRT), and dihydropyrimidine dehydrogenase (DPD) are important enzymes related to the metabolism of 5-fluorouracil and its derivatives. In this study, we analyzed the expression of these enzymes and evaluated the association between the expression of these enzymes and clinicopathological features and prognosis in patients with pancreatic cancer.

METHODS

TP, OPRT, and DPD mRNA expressions were detected using a real-time reverse transcriptional-polymerase chain reaction method or by immunohistochemistry, using surgical specimens obtained from 25 patients with pancreatic cancer.

RESULTS

TP mRNA expression was lower in cases with an alpha infiltration growth pattern than in cases with other infiltration growth patterns (P < 0.05). OPRT mRNA expression was higher in poorly differentiated-type cases than in differentiated type cases (P < 0.05). TP-, OPRT-, and DPD-positive stainings were found in 15 of 24 cases (63%), 10 of 19 cases (53%), and 14 of 21 cases (67%), respectively. There were significant correlations or trends between the mRNA and protein expressions of TP, OPRT, and DPD. Patients with a low TP/DPD ratio survived significantly longer than those with a high ratio (P < 0.05). Multivariate analysis demonstrated a significantly poorer outcome in patients with a high TP/DPD ratio compared with in patients with a low ratio (P < 0.05).

CONCLUSION

The TP/DPD ratio might be useful as a prognostic factor in patients with pancreatic cancer.

Gender specific tumour pharmacology--from kinetics to genetics

Gender specific tumour pharmacology only started to awake interest in the mid-90s. The most advanced studies include gender specific fluoropyrimidine pharmacokinetics and basic levels of pharmacogenomics, but most pharmacogenetic questions have remained unanswered. Considering polymorphisms of relevant drug converting enzymes such as folate reductase, cytochrome P450 dependent oxidases, and UDP-glucuronyltransferase, we have to rely more on hypotheses than on facts. This very limited knowledge base on gender specific tumour pharmacology urgently needs to be expanded in randomized clinical trials, because only clinical evidence will provide the sound base necessary for its implementation in oncologic therapies.

Use of Capecitabine to Prevent Acute Renal Allograft Rejection in Dog Erythrocyte Antigen-Mismatched Mongrel Dogs

OBJECTIVE

To assess efficacy and toxicity of a capecitabine (CAP)-based regimen for preventing rejection of renal allografts in dog erythrocyte antigen (DEA)-mismatched mongrel dogs.

STUDY DESIGN

Prospective, pilot study.

ANIMALS

Eight healthy, unrelated, DEA mismatched, adult mongrel dogs.

METHODS

All dogs received CAP, starting at 50 mg/m2 PO b.i.d. 4 days preoperatively, increasing to 200 mg/m2 PO b.i.d. by the day of surgery. All dogs received cyclosporine-A (CsA) and prednisolone starting 2 days preoperatively. Standard heterotopic renal transplantation with native nephrectomy was performed. After 90 days, surviving dogs were euthanatized and histopathologic examination was performed.

RESULTS

Two of 8 dogs developed acute neurotoxicity leading to death or euthanasia within 5 days of surgery. For the 6 remaining dogs, there were no statistically significant changes in complete blood count or serum biochemical values. No opportunistic infections developed during the study period. Five of 6 dogs had no to minimal evidence of graft rejection. Two of 6 dogs developed superficial and pigmentary keratitis. Significant histopathologic findings in all dogs included mild lymphoplasmacytic gastroenteritis, steroid hepatopathy, and corneal epithelial thinning. One dog had moderate interstitial nephritis and pyelitis.

CONCLUSIONS

In this experimental model, a CAP-CsA-prednisolone immunosuppressive regimen was effective in preventing rejection of allografts in DEA-mismatched dogs. Severe, unpredictable neurotoxicity and variable ocular toxicity significantly limit clinical applications at this time.

CLINICAL RELEVANCE

A CAP-CsA-prednisolone protocol is an effective, oral immunosuppressive regimen for prevention of allograft rejection in DEA-mismatched mongrel dogs. For clinical application, identification of patients susceptible to toxic side effects would be necessary.

How may anticancer chemotherapy with fluorouracil be individualised?

Fluorouracil is used clinically against various solid tumours. Both fluorouracil toxicity and pharmacokinetics vary highly within and between individuals. The reasons why doses are not individualised routinely are difficulties in defining, predicting and achieving an optimal fluorouracil exposure or dose because of a narrow therapeutic index, nonlinear pharmacokinetics, variabilities in administration rates and metabolism, and in targets like thymidylate synthase. To individualise fluorouracil administration before the first dose, assessment of the individual dihydropyrimidine dehydrogenase (DPD) activity may be useful, because this genetically highly polymorphic enzyme controls approximately 80% of fluorouracil elimination. A complete or partial loss of DPD activity in 0.1 and 3-5% of Caucasians, respectively, leads to increased fluorouracil exposure and toxicity. Several methods to assess DPD activity in patients have been proposed (genotyping, various phenotyping methods), but each of them has limitations, as has the fluorouracil test dose approach. To adapt exposure towards fluorouracil a priori, a combination of genotyping and phenotyping may yield better prediction of toxicity than one method alone. A prerequisite for dose adaptation is the definition of fluorouracil exposure ranges with sufficient therapeutic activity, but without serious toxicity. While an increased risk of leukopenia, diarrhoea, stomatitis, and hand-foot syndrome during continuous 5-day infusions was related to fluorouracil exposures above an area under the plasma concentration-time curve (AUC) threshold of 25-30 mg.h/L, tumour response was higher when an AUC of approximately 30 mg.h/L was achieved, illustrating the extremely narrow therapeutic window of fluorouracil. Pharmacokinetic target values are less clear for other regimens, including chronomodulated regimens, which yielded a superior clinically efficacy and tolerability in several trials. However, the monitoring of fluorouracil plasma concentrations seems principally useful for individual a posteriori dose adjustment. Whether an adaptation of the fluorouracil starting dose to the results of two DPD activity tests before fluorouracil administration a priori, and the adaptation of doses to fluorouracil exposure a posteriori is a reasonable approach to better prevent toxicity and increase efficacy, remains to be evaluated in randomised clinical studies comparing these strategies to routine clinical safety monitoring.

Phase II clinical trial of capecitabine in the treatment of advanced, persistent or recurrent squamous cell carcinoma of the cervix with translational research: a gynecologic oncology group study

PURPOSE

To evaluate the anti-tumor activity and adverse events of capecitabine in advanced, persistent or recurrent squamous cell carcinoma of the cervix, and to explore biomarkers with the potential to predict capecitabine response and toxicity.

EXPERIMENTAL DESIGN

Eligible, consenting patients were treated with a starting dose of 2500 mg/m(2)/day or 1800 mg/m(2)/day (divided into two doses given every 12 h) for 14 days of each 21-day cycle. Prior chemotherapy was allowed only in the context of radiation "sensitization". Genotyping in the 5' and 3' ends of thymidylate synthase (TS) was performed in DNA from pretreatment blood. Relative gene expression of TS, dihydropyrimidine dehydrogenase (DPD) and thymidine phosphorylase (TP) was quantified in RNA extracted from paraffin-embedded tumor.

RESULTS

All patients had prior radiotherapy and 22 received a radiation sensitizer. A partial response was observed in 4 of 26 (15%) evaluable patients. An additional 35% of patients achieved stable disease while 42% experienced increasing disease. The most common serious non-hematological toxicities were gastrointestinal and dermatologic. Exploratory analyses suggested that: a germline polymorphism in the 3' or the 5' end of TS was not associated with TS gene expression, relative tumor expression of TS, DPD and TP were not correlated, and relative tumor expression of TP may predict severe anemia.

CONCLUSIONS

Based on the modest response rate, this trial was closed without a second stage of accrual; single agent capecitabine was not selected for further study in advanced persistent or recurrent squamous cell carcinoma of the cervix previously treated with radiation or chemoradiation.

Thymidine phosphorylase and dihydropyrimidine dehydrogenase expression levels in tumor and normal tissue specimens of T3 human colorectal carcinoma

PURPOSE

Thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) are important enzymes related to the metabolism of 5-fluorouracil and its derivatives. We evaluated the association between the clinicopathological factors and these enzymes in patients with T3 colorectal carcinoma.

METHODS

The TP and DPD expression levels in 15 patients with T3 colorectal carcinomas were measured in tumor and adjacent normal tissue specimens by enzyme-linked immunosorbent assay. Correlations between each enzyme and clinicopathological factors were also statistically evaluated.

RESULTS

The TP levels in tumor and normal tissue specimens were 77.9 +/- 33.6 and 24.7 +/- 10.3, respectively (P < 0.001). The DPD levels in tumor and normal tissue specimens were 44.1 +/- 18.2 and 53.1 +/- 24.1, respectively (P = 0.46). The TP/DPD ratios in tumor and normal tissue specimens were 1.84 +/- 0.52 and 0.53 +/- 0.26, respectively (P < 0.001). The tumor/normal ratios of TP level in patients with and without liver metastasis were 1.79 +/- 0.91 and 4.67 +/- 2.51, respectively (P = 0.024).

CONCLUSION

The measurement of the enzyme expression levels of TP and DPD is considered to be useful for better understanding the conditions of tumor progression. The mechanisms of regulation of these enzymes thus require further evaluation.

Influence of chemotherapeutic agents and cytokines on the expression of 5-fluorouracil-associated enzymes in human colon cancer cell lines

BACKGROUND

Several studies have demonstrated that intratumoral expression of catabolizing and anabolizing enzymes for 5-fluorouracil (5-FU) is important in the response of cancers to 5-FU-based chemotherapy. We investigated the influence of other chemotherapeutic agents or cytokines, which are often administered for enhancing the efficacy of 5-FU, on the tumoral expression of 5-FU-associated enzymes, i.e., dihydropyrimidine dehydrogenase (DPD), thymidylate synthase (TS), orotate phosphoribosyl transferase (OPRT), and thymidine phosphorylase (TP).

METHODS

Human colon cancer cell lines (HT-29, Caco-2, and DLD-1) were incubated with 5-FU and with 5-FU combined with cisplatin, camptothecin, paclitaxel, mitomycin C, interferon, or TNF-related apoptosis-inducing ligand. mRNA expression of 5-FU-associated enzymes was assessed by real-time PCR. Activity of each enzyme and intracellular 5-FU accumulation after incubation with such agents were also evaluated.

RESULTS

Each agent had a synergistic effect on the cytotoxicity of 5-FU. All chemotherapeutic agents other than cytokines induced marked alteration of the mRNA expression profile of 5-FU-associated enzymes; depression of DPD, elevation of TS, and slight suppression of OPRT and TP. In accordance with mRNA expression, enzyme activity of DPD was significantly depressed by such agents. Furthermore, although 5-FU itself increased DPD mRNA expression, a mechanism considered to be related to the acquisition of 5-FU resistance, the addition of cisplatin or camptothecin significantly inhibited the 5-FU-induced elevation of DPD.

CONCLUSIONS

5-FU-associated enzymes in colon cancer cells were greatly influenced by various chemotherapeutic agents; in particular, DPD expression was depressed. These results appear important in planning chemotherapy and also in understanding the development of adverse effects of 5-FU.

Use of Capecitabine After Renal Allograft Transplantation in Dog Erythrocyte Antigen-Matched Dogs

OBJECTIVES

To investigate the use of a capecitabine (CAP)-based regimen after renal transplantation in dogs.

STUDY DESIGN

Prospective, pilot study.

ANIMALS

Healthy, unrelated, dog erythrocyte antigen (DEA)-matched, adult beagles.

METHOD

Standard heterotopic renal transplantation with native nephrectomy was performed in 7 dogs. Dogs received oral, twice daily, CAP (250 mg/m2), cyclosporine-A (CsA) (4 mg/kg), ketoconazole (5 mg/kg), and prednisolone (0.25 mg/kg). After 90 days the surviving dogs were euthanatized and complete necropsy was performed.

RESULTS

Seven transplants were performed. All dogs survived surgery. Six dogs had acute neurotoxicity, which resulted in death or euthanasia of 2 dogs within 2 days of surgery. In the remaining dogs, toxicity resolved rapidly with cessation of drug administration. Thereafter, modification of the regimen minimized toxicity. The 5 remaining dogs survived to study end; 4 dogs had no evidence of graft rejection. Necropsy examination was mostly unremarkable in all dogs. There were no major changes in CBC or biochemical values, except for a significant increase in serum calcium.

CONCLUSIONS

CAP appeared well tolerated in most dogs. Toxicity occurred but abated with modification of the drug regimen. Efficacy for postoperative immunosuppression cannot be determined by this study, although results are promising.

CLINICAL RELEVANCE

CAP-CsA-prednisolone is an effective, oral immunosuppressive regimen for prevention of acute allograft rejection in DEA-matched beagles. Further studies on dose, toxicity, and efficacy compared with current immunosuppressive regimens are needed before use in clinical practice.

Pharmacokinetics of bolus 5-fluorouracil: relationship between dose, plasma concentrations, area-under-the-curve and toxicity

The pharmacokinetics of 5-fluorouracil (5FU) have been related to toxicity and antitumor activity, in particular for continuous infusion schedules, but to a lesser extent for frequently used bolus injections. The use of intensive sampling schedules limits the application of pharmacokinetics to optimize individual dosing or to define the ideal combination with other drugs. We therefore reanalyzed a pharmacokinetic study in order to develop a limited sampling schedule. Patients received escalating doses of 5FU at 500, 600 and 720 mg/m2 as a bolus until toxicity developed. Blood samples were analyzed until 24 h after administration. The area under the concentration time curve from 0-90 min (AUC(0-90)) was strongly correlated with dose and also with toxicity (p = 0.0009). The 5FU concentrations at 30 and 60 min were correlated to the AUC(30-240) and to that of the AUC(0-90) (r2 = 0.970). The use of limited sampling (30, 60, 90 min) in a patient given 353 mg/m2 5FU with severe toxicity at initial dosing at 500 mg/m2 revealed that the AUC(0-90) at 353 mg/m2 was higher than the normal AUC(0-90) for 500 mg/m2. This patient appeared to have an 8-fold lower activity of the 5FU degradation enzyme dihydropyrimidine dehydrogenase. Limited sampling will allow us to define potential aberrant kinetics of pharmacokinetic interaction of 5FU with other drugs being developed for treatment of colorectal cancer.

Predictive factors for response to chemotherapy in colorectal cancer patients

Colorectal cancer represents a major health problem in the western world. A lot of drugs have been employed in treatment of this disease, but only few data are available about predictive factors for response to anticancer treatments in colorectal cancer. Aim of this paper is to review the main data about this investigation field. Using a Medline database search (1966-2003) we reviewed all the relevant papers that investigate clinical and molecular predictors for response to the main drugs used in the treatment of colorectal cancer patients, both in adjuvant and in advanced setting. Moreover we comprehensively reviewed all the data published in abstract form during the most significant international meetings. Our review put in evidence the most important predictive factors for response in colorectal cancer patients treated with anticancer chemotherapy both in adjuvant and in advanced setting. The predictive factors are clustered on the basis of the different anticancer drugs. The results of this review provide the rationale basis for personalizing anticancer treatment in colorectal cancer patients by molecular and clinical features, aiming to improve response rate and reduce toxicities.

Phase II Evaluation of Docetaxel-Modulated Capecitabine in Previously Treated Patients with Non–Small Cell Lung Cancer

PURPOSE

Based on the preclinical observation of upregulation of thymidine phosphorylase, the last enzymatic step in the conversion of capecitabine to 5-fluorouracil, by docetaxel along with good clinical tolerability of the combination of docetaxel and capecitabine using an optimized schedule in a previous phase I trial, we conducted this phase II study of this combination in patients with refractory or relapsed non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

Patients with NSCLC previously treated with at least one platinum- or paclitaxel-based regimen received docetaxel 36 mg/m(2) on days 1, 8, and 15 and capecitabine 625 mg/m(2) twice daily on days 5 to 18, every 4 weeks. The primary objective of the study was evaluation of progression-free survival (PFS) 26 weeks from initiation of treatment.

RESULTS

Thirty-six evaluable patients received 104 cycles of the combination. Severe toxicities were infrequent with only one patient requiring toxicity-related hospitalization. The 26-week PFS rate was 25% (95% confidence interval, 12-42) with an intent to treat median survival and 1-year survival rate of 9.1 months and 37%, respectively. Among 31 patients with measurable disease (Response Evaluation Criteria in Solid Tumors criteria), eight (26%; 95% confidence interval, 12-45) achieved partial responses.

CONCLUSION

The combination of capecitabine and weekly docetaxel is well tolerated in previously treated patients with NSCLC. The relatively high 26-week PFS and 1-year survival, as well as the high response rate observed, encourages further evaluation of this regimen in NSCLC, either in randomized trials for refractory patients or as a potential treatment option for chemotherapy naive patients.

Phase II clinical trial of capecitabine in ovarian carcinoma recurrent 6–12 months after completion of primary chemotherapy, with exploratory TS, DPD, and TP correlates: a Gynecologic Oncology Group study

PURPOSE

A phase II trial was conducted to evaluate the anti-tumor activity and adverse effects of capecitabine in women with measurable platinum-sensitive ovarian cancer or platinum-sensitive primary peritoneal cancer and to explore the ability of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), and thymidine phosphorylase (TP) to predict response and toxicities.

EXPERIMENTAL DESIGN

Patients were treated with a daily starting dose of 2500 mg/m2/day (divided in two doses given every 12 h) for 14 days of each 21-day cycle. Genotyping in the 5' and 3' ends of TS was performed in DNA from 23/23 pre-treatment blood specimens. Relative gene expression of TS, DPD, and TP was quantified in 18/21 paraffin-embedded tumor specimens.

RESULTS

Of the 27 patients enrolled on study, 2 were never treated leaving 25 patients evaluable. Two patients (8.0%) achieved a partial response, 13 (52%) exhibited stable disease, 5 (20%) displayed increasing disease, and response could not be assessed in 5 (20%). The median time to progression and survival was 3.9 and 21.2 months, respectively. The most common serious toxicities were nausea/vomiting, gastrointestinal, and dermatological. There was one treatment-related death. TS expression was associated with severe nausea/vomiting (P = 0.039), but not with other severe toxicities. TS genotype or expression of DPD or TP was not associated with any of the severe toxicities.

CONCLUSIONS

Based on the low response rate, this trial was closed after the first stage of accrual, the drug was not selected for further study in this patient population, and biomarker associations with response could not be assessed.

Tailored Chemotherapy for Colorectal Cancer: A New Approach to Therapy

The treatment of colorectal cancer has advanced over the past several years with the introduction of several active agents. Determining which patients to treat with chemotherapy and choosing optimal treatment would allow practioners to maximize the benefit of chemotherapy. Several prognostic and predictive markers have been identified and include oncogenes, tumor suppressor genes, genes involved in angiogenic and apoptotic pathways and cell proliferation, and those encoding targets of chemotherapy. Specifically, prognostic markers include deletion of 18q (DCC), p27 and microsatellite instability. Predictive markers are those that may determine efficacy of drugs used in colorectal cancer such as fluropyrimidines and oxaliplatin. Alterations in gene expression, protein expression and polymorphic variants in genes encoding thymidylate synthase, dihydropyrimidine dehydrogenase, and thymidine phosphorylase and excision repair cross-complementing genes (ERCC1) may be useful as markers for clinical drug response, survival and host toxicity. The integration of these prognostic and predictive markers would allow individualized treatment for patients, maximizing therapeutic effect and minimizing exposure to toxicity.

Mutations in exon 14 of dihydropyrimidine dehydrogenase and 5-Fluorouracil toxicity in Portuguese colorectal cancer patients

PURPOSE

Dihydropyrimidine dehydrogenase is a critical enzyme in the catabolism of 5-Fluorouracil, a drug frequently used in cancer therapy. Patients with deficient dihydropyrimidine dehydrogenase activity are at risk of developing severe 5-Fluorouracil-associated toxicity. Genetic analysis of the gene coding for dihydropyrimidine dehydrogenase has shown that mutations in exon 14, especially the splice-site mutation IVS14+1G-->A, were associated with dihydropyrimidine dehydrogenase enzymatic deficiency.

METHODS

We evaluated the frequency of mutations in exon 14 of dihydropyrimidine dehydrogenase (DPYD) gene in 73 unselected colorectal cancer patients treated with 5-Fluorouracil after surgery at a Portuguese Cancer Institute.

RESULTS

Sequencing the entire exon 14 allowed the detection of mutations in two of the 73 patients (2.7%), namely two of the eight (25%) patients who presented grade 3-4 toxicity after 5-Fluorouracil chemotherapy. One patient was heterozygous for the splice-site mutation IVS14+1G-->A, whereas the second patient was heterozygous for a novel missense mutation 1845G-->T (E615D) in exon 14 of DPYD gene.

CONCLUSION

We conclude that mutations in exon 14 of DPYD gene are responsible for a significant proportion of life-threatening toxicity to 5-Fluorouracil, and should therefore be excluded before its administration to cancer patients.

Improving patient care through molecular diagnostics

Traditional cancer diagnostic techniques include assessment of histologic appearance, identification of specific tumor subtypes, tumor grading, assessment of lymph node status, and presence of metastasis. These are useful for initial evaluation, but are limited in their ability to predict response to treatment and/or risk of experiencing adverse events to particular treatments. Recently, there has been considerable progress in molecular diagnostics in this area. Using molecular-based technologies, it is now possible to identify some patients with an inherited risk of developing breast cancer, and to more accurately assess the prognosis of those who already have developed the disease. Various techniques are also available or under investigation to help select patients who are most likely to respond to certain types of treatment. At present, this includes diagnostic tests to identify single tumor markers for which specific therapies are available, such as estrogen receptor and HER2. Diagnostic systems that allow simultaneous assessment of multiple markers, such as DNA microarrays and proteomics, are currently being validated. The use of these systems will allow further development of customized therapies directed toward the particular molecular defects in a given cancer.

Prognostic significance of orotate phosphoribosyltransferase activity in bladder carcinoma

BACKGROUND

5-Fluorouracil (5-FU), an antitumor agent, is used clinically against a variety of malignancies, including bladder carcinoma. 5-FU is a prodrug, and orotate phosphoribosyltransferase (OPRT) is the principal enzyme that converts 5-FU directly into an active antitumor metabolite, 5-fluoro-2'-deoxyuridine 5'-monophosphate. In addition, OPRT is the key enzyme in the de novo DNA and RNA synthetic process. To the authors' knowledge, little is known regarding the significance of OPRT in various malignancies, including bladder carcinoma. The authors analyzed the activity levels of OPRT in 60 bladder carcinomas and evaluated the association between the level of OPRT activity and the stage and grade status of bladder carcinoma. They also examined the prognostic significance of OPRT activity in patients with bladder carcinoma and the correlation between OPRT activity levels in bladder carcinoma cells and the sensitivity of those cells to 5-FU.

METHODS

OPRT activity levels in nonfixed, fresh-frozen specimens of bladder carcinoma and normal bladder were determined enzymatically using a 5-FU phosphorylation assay. The sensitivity of bladder cells to 5-FU was assessed using a microculture tetrazolium dye assay.

RESULTS

The activity levels of OPRT were approximately 7.5-fold higher in bladder carcinoma specimens compared with the activity levels in normal bladder specimens. OPRT activity in muscle-invasive bladder carcinoma was 2-fold higher compared with the activity in superficial bladder carcinoma (classified as Ta and T1). In addition, the activity of OPRT in T1 bladder carcinoma was 2-fold higher compared with the activity in Ta bladder carcinoma. The level of OPRT activity in Grade 3 bladder carcinoma was 6-fold and 2-fold higher compared with the activity in Grade 1 and Grade 2 bladder carcinoma, respectively. Patients who had Ta and T1 bladder carcinoma with low OPRT activity had a longer postoperative tumor free period compared with patients who had bladder carcinoma with high OPRT activity in the 3-year follow-up. There was a positive association between the activity levels of OPRT and thymidylate synthase/thymidine kinase, which are the key enzymes in the de novo/salvage DNA synthetic process. OPRT activity in bladder carcinoma cells was correlated positively with their sensitivity to 5-FU.

CONCLUSIONS

to the authors' knowledge, the current study is the first to demonstrate that OPRT activity levels in bladder carcinoma were higher compared with its activity in the normal bladder tissues and that OPRT activity levels were correlated positively with the stage and grade of bladder carcinoma. In addition, high OPRT activity levels in patients with superficial bladder carcinoma predicted early recurrence and high sensitivity to 5-FU. These results suggest that the level of OPRT activity may be used both as a prognostic parameter and as a predictive indicator for 5-FU efficacy in patients with bladder carcinoma and that OPRT may be a molecular therapeutic target in bladder carcinoma.

Significance of Orotate Phosphoribosyltransferase Activity in Renal Cell Carcinoma

PURPOSE

The anticancer agent 5-fluorouracil (5-FU) is clinically used against various cancers, including renal cell carcinoma (RCC). It is a prodrug and orotate phosphoribosyltransferase (OPRT) is the principal enzyme that directly converts 5-FU to the active anticancer metabolite 5-fluoro-2'-deoxyuridine 5'-monophosphate. In addition, OPRT is the key enzyme in the de novo DNA and RNA synthetic process. Little is known about the significance of OPRT in various cancers, including RCC. We investigated the activity of OPRT in 83 RCCs and evaluated the association between the level of OPRT activity and the stage/grade of RCC. The relationship between OPRT activity in RCC cells and their sensitivity to 5-FU was also examined.

MATERIALS AND METHODS

OPRT activity in nonfixed, fresh frozen RCC and normal kidney was determined enzymatically by the 5-FU phosphorylation assay. The sensitivity of RCC cells to 5-FU was assessed by the microculture tetrazolium dye assay.

RESULTS

The activity of OPRT was approximately 8.5-fold higher in RCC than in normal kidney. OPRT activity in stage III/IV RCC was 3-fold higher than in stage I/II RCC. The level of OPRT activity in grade 3 RCC was 3-fold higher than that in grade 1/2 cancer. Patients with RCC with low OPRT activity had longer postoperative disease specific survival than those with high activity at 5-year followup. OPRT activity in RCC cells positively correlated with their sensitivity to 5-FU.

CONCLUSIONS

To our knowledge this is the first study to demonstrate that OPRT activity in RCC was higher than that in normal kidney and OPRT activity positively correlated with RCC stage/grade. In addition, higher OPRT activity in RCC predicted worse prognosis and higher sensitivity to 5-FU. These results suggest that the level of OPRT activity may be used as a prognostic parameter and predictive indicator for 5-FU efficacy in RCC and OPRT may be a molecular therapeutic target in RCC.

Molecular predictors of treatment and outcome in colorectal cancer

Understanding of the metabolism and mechanisms of resistance of tumors to chemotherapeutic agents is essential so that we can administer therapy to maximize response and minimize toxicity. In this review we describe molecular markers associated with fluoropyrimidine and platinum-based chemotherapy that may predict the outcome of therapy when patients are treated with these agents. We discuss the ways in which determination of gene expression levels can enhance the treatment of colorectal cancer through prediction of patient response and tailoring of chemotherapy to the characteristics of an individual tumor.

Quantitation of dihydropyrimidine dehydrogenase (DPD) mRNA expression levels in normal colon and colorectal cancer tumor paraffin-embedded tissue specimens

5-Fluorouracil (5-FU) has been used for more than 40 years in the treatment of neoplastic disease, and remains the standard first-line treatment for colorectal cancer in combination with irinotecan and leucovorin. Previous studies indicated that measurement of dihydropyrimidine dehydrogenase (DPD) gene expression before treatment was valuable in determining the potential benefit of and toxicity to 5-FU treatment. In this study, we investigated the association between intratumoral DPD gene expression and the adjacent normal tissue DPD gene expression and DPD mRNA expression level in non-paired colon tumor and normal colon tissue specimens. In addition, we have compared the difference of DPD gene expression at three different RNA concentrations from the same specimen (180, 100 and 5 ng/reaction, respectively). DPD expression was measured by quantitative RT-PCR using a LightCycler instrument in a total of 31 specimens. Gene expression values were expressed as a ratio of target gene (DPD) to the internal reference gene (G6PDH). Our study revealed no statistically significant difference (p=0.23) between tumor tissues and matched normal tissue in DPD expression. In contrast, the data on DPD mRNA expression in non-paired colon tumor and normal tissue specimens revealed a significant difference (p=0.0004) between the tumor group and the normal group. In the three RNA concentration groups, there was no significant difference (p=0.55) in gene expression at the different RNA concentrations from the same donor. These results demonstrate that intratumoral gene expression levels of DPD do not correlate with tumor cell percentage or with RNA concentration. Thus, DPD mRNA expression appears to be a valid sensitivity test for 5-FU in spite of a varying density of tumor cells and RNA yield in specimens submitted for analysis.

Targeted therapy and pharmacogenomic programs

The goal in administering chemotherapeutics is to develop the ability to predict the outcome of therapy in terms of response and toxicity. Technology has been developed to allow tumor profiling with measurement of protein expression, gene expression levels of markers, and even genetic polymorphisms, which may predict response to particular chemotherapeutics. The chemotherapeutics for which particular markers have been shown to predict outcome include the fluoropyrimidines and platinums. The next step is to develop clinical trials that will assess prospectively the benefits of profiling a patient's particular tumor, which should translate into an improvement in response and toxicity.