Phase I and pharmacokinetic study of the oral fluoropyrimidine capecitabine in combination with paclitaxel in patients with advanced solid malignancies

Utility of Physiologically Based Pharmacokinetic Modeling to Investigate the Impact of Physiological Changes of Pregnancy and Cancer on Oncology Drug Pharmacokinetics

BACKGROUND

The treatment of cancer during pregnancy remains challenging with knowledge gaps in drug dosage, safety, and efficacy due to the under-representation of this population in clinical trials. Our aim was to investigate physiological changes reported in both pregnancy and cancer populations into a PBPK modeling framework that allows for a more accurate estimation of PK changes in pregnant patients with cancer.

METHODS

Paclitaxel and docetaxel were selected to validate a population model using clinical data from pregnant patients with cancer. The validated population model was subsequently used to predict the PK of acalabrutinib in pregnant patients with cancer.

RESULTS

The Simcyp pregnancy population model reasonably predicted the PK of docetaxel in pregnant patients with cancer, while a modified model that included a 2.5-fold increase in CYP2C8 abundance, consistent with the increased expression during pregnancy, was needed to reasonably predict the PK of paclitaxel in pregnant patients with cancer. Changes in protein binding levels of patients with cancer had a minimal impact on the predicted clearance of paclitaxel and docetaxel. PBPK modeling predicted approximately 60% lower AUC and Cmax for acalabrutinib in pregnant versus non-pregnant patients with cancer.

CONCLUSIONS

Our results suggest that PBPK modeling is a promising approach to investigate the effects of pregnancy and cancer on the PK of oncology drugs and potentially inform dosing for pregnant patients with cancer. Further evaluation and refinement of the population model are needed for pregnant patients with cancer with additional compounds and clinical PK data.

A physiologically based pharmacokinetic - pharmacodynamic modelling approach to predict incidence of neutropenia as a result of drug-drug interactions of paclitaxel in cancer patients

Paclitaxel is the backbone of standard chemotherapeutic regimens used in a number of malignancies and is frequently given with concomitant medications. Newly developed oncolytic agents, including tyrosine kinase inhibitors are often shown to be CYP3A4 and P-gp inhibitors. The aim of this study was to develop a PBPK model for intravenously administered paclitaxel in order to predict the incidence of neutropenia and to estimate the DDI potential as a victim drug. The dose-dependent effects on paclitaxel plasma protein binding, volume of distribution and drug clearance were considered for dose levels of 80 mg/m², 135 mg/m² and 175 mg/m². A pharmacodynamics model that incorporate the impact of paclitaxel on the neutrophil was developed. The relative metabolic clearance via CYP3A4 and CYP2C8, the renal clearance as well as P-gp mediated biliary clearance were incorporated in the model in order to assess the neutropenia in the presence of DDI. The developed PBPK-PD model was able to recover the drop in neutrophils observed after the administration of 175mg/m2 of paclitaxel over a 3-h duration. The mean nadir observed was 1.9 × 10⁹ neutrophils/L and was attained after 10 days of treatment, and a fraction of 47% of the population was predicted to have at some point a neutropenia including 12% with severe neutropenia. In the case of concomitant administration of ketoconazole, 39% of the population was predicted to suffer from severe neutropenia. In summary, PBPK-PD modeling allows a priori prediction of DDIs and safety events involving complex combination therapies which are often utilized in an oncology setting.

Acute Cardiotoxicity during Capecitabine Treatment: A Case Report

Capecitabine (Xeloda®, Roche, Monza), a fluoropyrimidine carbamate, is an orally administered drug that delivers fluorouracil (5-FU) selectively to the tumor. The drug has demonstrated activity in metastatic breast cancer, pancreatic cancer and colorectal cancer.

In this case report the authors describe an unusually and reversible cardiac side effect which occurs to 39-year-old patient treated with capecitabine 2000 mg/m2/day for advanced gastric cancer.

It is important to note that the safety data from clinical trials indicate that capecitabine has a toxicity profile typical of infused fluoropyrimidines. However, none of the studies described cardiac side effects.

Capecitabine: Indications and Future Perspectives in the Treatment of Metastatic Colorectal and Breast Cancer

Fluoropyrimidines remain the most important drugs in the treatment of breast and colorectal carcinoma, but response rates and survival time have been disappointing. Optimal administration is by continuous intravenous infusion, which makes it cumbersome to use and compromises patient independence. Recently, a number of new agents, including fluorouracil prodrugs and selective dihydropyrimidine dehydrogenase inhibitors, have been studied, with promising results. Capecitabine is the first in a new class of fluoropyrimidines. It is an oral, tumor-activated anticancer drug whose activity mimics that of continuously infused 5-fluorouracil. Capecitabine circumvents dihydropyrimidine dehydrogenase catabolism and appears to be at least as active against metastatic colorectal and breast cancer as conventionally administered intravenous 5-fluorouracil, with significantly less toxicity, an improved quality of life, and lesser cost. Capecitabine may ultimately provide enhanced antitumor activity to fluorouracil-containing regimes for advanced colorectal and breast cancer.

Physiologically Based Pharmacokinetic Modeling to Predict Drug-Drug Interactions with Efavirenz Involving Simultaneous Inducing and Inhibitory Effects on Cytochromes

BACKGROUND

Antiretroviral drugs are among the therapeutic agents with the highest potential for drug-drug interactions (DDIs). In the absence of clinical data, DDIs are mainly predicted based on preclinical data and knowledge of the disposition of individual drugs. Predictions can be challenging, especially when antiretroviral drugs induce and inhibit multiple cytochrome P450 (CYP) isoenzymes simultaneously.

METHODS

This study predicted the magnitude of the DDI between efavirenz, an inducer of CYP3A4 and inhibitor of CYP2C8, and dual CYP3A4/CYP2C8 substrates (repaglinide, montelukast, pioglitazone, paclitaxel) using a physiologically based pharmacokinetic (PBPK) modeling approach integrating concurrent effects on CYPs. In vitro data describing the physicochemical properties, absorption, distribution, metabolism, and elimination of efavirenz and CYP3A4/CYP2C8 substrates as well as the CYP-inducing and -inhibitory potential of efavirenz were obtained from published literature. The data were integrated in a PBPK model developed using mathematical descriptions of molecular, physiological, and anatomical processes defining pharmacokinetics. Plasma drug-concentration profiles were simulated at steady state in virtual individuals for each drug given alone or in combination with efavirenz. The simulated pharmacokinetic parameters of drugs given alone were compared against existing clinical data. The effect of efavirenz on CYP was compared with published DDI data.

RESULTS

The predictions indicate that the overall effect of efavirenz on dual CYP3A4/CYP2C8 substrates is induction of metabolism. The magnitude of induction tends to be less pronounced for dual CYP3A4/CYP2C8 substrates with predominant CYP2C8 metabolism.

CONCLUSION

PBPK modeling constitutes a useful mechanistic approach for the quantitative prediction of DDI involving simultaneous inducing or inhibitory effects on multiple CYPs as often encountered with antiretroviral drugs.

Erythrocyte membrane nanoparticles improve the intestinal absorption of paclitaxel

Paclitaxel (PTX) is a cytotoxic chemotherapy drug with encouraging activity in human malignancies. However, free PTX has a very low oral bioavailability due to its low aqueous solubility and the gastrointestinal drug barrier. In order to overcome this obstacle, we have designed erythrocyte membrane nanoparticles (EMNP) using sonication method. The permeability of PTX by EMNP was 3.5-fold (P_app = 0.425 nm/s) and 16.2-fold (P_app = 394.1 nm/s) higher than free PTX in MDCK-MDR1 cell monolayers and intestinal mucosal tissue, respectively. The in vivo pharmacokinetics indicated that the AUC_0-t (μg/mL·h) and C_max (μg/mL) of EMNP were 14.2-fold and 6.0-fold higher than that of free PTX, respectively. In summary, the EMNP appears to be a promising nanoformulation to enhance the oral bioavailability of insoluble and poorly permeable drugs.

Capecitabine: a novel, orally administered, tumour-activated treatment for colorectal cancer

Objective. To provide a comprehensive review of the preclinical and clinical pharmacology and toxicology of the fluoropyrimidine, capecitabine, with particular reference to its use in its new indication, advanced colorectal cancer.

Data sources. A MEDLINE search was conducted using the term ‘‘capecitabine’’ for the period 1995 -2001. The reference lists from retrieved articles were reviewed and other relevant papers identified. The abstract books from the annual meetings of the American Society of Clinical and Oncology and the European Society of Medical Oncology were also reviewed.

Data extraction. The aim of the review was to be comprehensive and descriptive. All studies containing information deemed to be of interest were reviewed by the author, none were excluded on grounds of quality.

Data synthesis. Capecitabine is a prodrug of the widely used cytotoxic agent 5-fluorouracil (5-FU). Unlike 5-FU it is extensively and reliably absorbed after oral administration and does not require folinate (FA) potentiation. Activation of capecitabine is a three-step enzymatic process. The final activating enzyme, thymidine phosphorylase, is found in unusually high concentrations in many solid tumours, resulting in preferential delivery of 5-FU to tumour tissues, including that of colorectal cancers, suggesting therapeutic potential in this malignancy. Large, randomized trials have demonstrated that capecitabine fulfils this potential—compared with the widely used ‘‘Mayo’’ regimen of intravenous 5-FU and folinic acid, oral capecitabine (1250 mg/m2 twice daily) produced a superior response rate and a similar time to disease progression and duration of survival. It was also better tolerated than 5-FU/FA—of seven common fluoropyrimidine-induced toxicities, four were significantly less common with capecitabine. Capecitabine also produced significantly less grade 4 toxicity or toxicity requiring hospitalization, though the hand -foot syndrome that characterizes prolonged, continuous exposure to 5-FU was more common after capecitabine.

Capecitabine for treating head and neck cancer

INTRODUCTION

With an increasing incidence, over half a million cases of head and neck cancer (HNC) are diagnosed annually worldwide. Various chemotherapeutic agents are utilized to achieve adequate locoregional control. Cisplatin, fluorouracil (FU), and taxanes are often used to treat HNC but these regimens have shown high toxicity and poor patient compliance. Capecitabine is an orally administered prodrug that is preferentially converted to FU in tumor cells in comparison to normal cells.

AREA COVERED

In this review, the authors evaluate the role of capecitabine in radical and palliative settings either alone or in combination with other chemotherapeutic drugs in the management of HNC. In addition, metabolic conversion, pharmacokinetics, pharmacodynamics, and toxicity profile of capecitabine are discussed.

EXPERT OPINION

Various phase II trials conducted on capecitabine in the management of recurrent HNC have shown comparable results and tolerable toxic effects especially in pre-treated fragile patients. Capecitabine, used in induction or concurrent settings in the radical management of locoregionally advanced HNC, have also shown promising results. Randomized trials are needed to validate the role of capecitabine in the management of HNC.

Biomodulation of capecitabine by paclitaxel and carboplatin in advanced solid tumors and adenocarcinoma of unknown primary

Paclitaxel and carboplatin upregulate thymidine phosphorylase and thus may provide synergistic antitumor activity in combination with capecitabine (CTX). We, therefore, performed a phase I/II study of CTX. In the phase I study, patients with advanced solid tumors received carboplatin on day 1, paclitaxel on days 1, 8, 15 and capecitabine orally twice a day on days 8-21, every 4 weeks. Phase II patients with advanced adenocarcinoma of unknown primary (ACUP) were treated at the maximal tolerable dose. The phase I study enrolled 29 patients evaluable for dose limiting toxicity. The recommended phase II dose was capecitabine 750 mg/m(2) bid, paclitaxel 60 mg/m(2)/week and carboplatin AUC of 6. There were 9 confirmed responses, 5 partial responses and disease stabilization >3 months in 14 patients. The phase II study was prematurely terminated at 25 patients due to cessation of funding. The objective response rate was 32 % (95 % CI 0.15-0.54), the median progression-free survival 5.5 months (95 % CI 2.8-10.8 months) and the median overall survival 10.8 months (95 % CI 6.0-32.0 months). CTX demonstrated acceptable tolerability and antitumor activity. At the recommended dose level in patients with ACUP, this regimen showed encouraging preliminary activity.

Liver injury possibly related to drug interaction after liver transplant: a case report

WHAT IS KNOWN AND OBJECTIVE

Drug-induced hepatotoxicity is potentially lethal. Liver transplant patients receive a large number of medications and adverse drug reactions, and drug-drug interactions must be closely monitored.

CASE SUMMARY

We report a case of a 29-year-old liver transplant patient who suffered liver injury most likely induced by drug interaction between capecitabine and warfarin. Vitamin K1 caused skin rash possibly because of the distribution and metabolism characteristic of the drug in this patient.

WHAT IS NEW AND CONCLUSION

Close monitoring and prompt discontinuation of the drugs with high volume of distribution and metabolized through the liver are necessary to avoid drug-drug interaction in liver transplant patients.

Pharmacokinetic evaluation of capecitabine in breast cancer

INTRODUCTION

Capecitabine , an oral prodrug of 5-fluorouracil (5-FU), is adsorbed in its intact form through the intestine and metabolized to 5-FU in tumour cells. In metastatic breast cancer (MBC), capecitabine is an effective and well-tolerated therapeutic option both in monotherapy and in combination with chemotherapeutic or molecular-targeted agents.

AREAS COVERED

We summarized data on pharmacokinetics and pharmacodynamics of capecitabine. We also produced a general review of the most relevant clinical studies of capecitabine in MBC. A literature search was performed using PubMed database including selected articles published in English language up to October 2012.

EXPERT OPINION

The unique pharmacodynamic/pharmacokinetic features represent the bases of the reduced toxicity and the activity of capecitabine in several tumours. Although during the past 10 years there has been an increasing use of this drug in MBC both as single agent and in combination, encouraging results of well tolerated and active combinations with novel agents will lead to a more extensive and protracted use of capecitabine. In view of this, some aspects should be further clarified such as the optimal starting dose and the introduction of alternative schedules of treatment.

Pharmacokinetic analysis of capecitabine and cisplatin in combination with trastuzumab in Japanese patients with advanced HER2-positive gastric cancer

PURPOSE

To evaluate the pharmacokinetics (PK) of capecitabine and cisplatin, administered in combination with or without trastuzumab, in Japanese patients with HER2-positive advanced gastric cancer (AGC).

METHODS

Patients eligible for this PK study (study JP19959), which was carried out during treatment Cycle 1 of the ToGA study, received either capecitabine and cisplatin (XP arm) or trastuzumab plus capecitabine and cisplatin (HXP arm). All patients received capecitabine (1,000 mg/m(2) orally, twice daily for 14 days) and cisplatin (80 mg/m(2) intravenous infusion on Day 1). Patients in the HXP arm also received trastuzumab (8 mg/kg intravenous infusion on Day 1), concurrently with capecitabine. No further study medication was administered during study JP19959. Serial plasma samples for PK analysis were obtained at intervals before and after the administration of capecitabine and cisplatin on Day 1.

RESULTS

Twenty-two patients were enrolled in this PK study: eight in the HXP arm and 14 in the XP arm. All blood samples were available for PK analysis. Co-administration of trastuzumab resulted in no statistically or clinically significant changes in the PK profiles of capecitabine or its metabolites, or of cisplatin (total or unbound platinum).

CONCLUSIONS

Variability in the AUC(last) and C (max) values for the capecitabine was consistent with the known PK profile of capecitabine and fell within established limits. Concurrent trastuzumab therapy is unlikely to alter the PK or safety profile of capecitabine or cisplatin in Japanese patients with HER2-positive AGC.

Cytotoxicity and genotoxicity of capecitabine in head and neck cancer and normal cells

The interaction between a chemical and a cell may strongly depend on whether this cell is normal or pathological. Side effects of anticancer drugs may sometimes overcome their benefit action, so it is important to investigate their effect in both the target and normal cells. Capecitabine (Xeloda, CAP), a prodrug of 5-fluorouracil, is mainly used in colon cancer, but little is known about its action in head and neck cancer. We compared the cyto- and genotoxicity of CAP in head and neck HTB-43 cells and normal human lymphocytes by comet assay and flow cytometry. CAP at concentration up to 50 μM significantly decreased the viability of the cancer cells, whereas it did not affect normal lymphocytes. The drug did not interact with isolated plasmid DNA, but it damaged DNA in both cancer and normal cells. However, the extent of the damage in the former was much higher than in the latter. CAP induced apoptosis in the cancer cells, but not in normal lymphocytes. Pre-treatment of the cells with the nitrone spin traps α-(4-pyridil-1-oxide)-N-tert-butylnitrone and N-tert-butyl-α-phenylnitrone decreased the extent of CAP induced DNA damage, suggesting that free radicals may be involved in the formation of DNA lesions induced by CAP. The drug evoked an increase in the G0/G1 cell population accompanied by a decrease in the S cell population. CAP may evoke a pronounced cyto- and genotoxic effects in head and neck cancer cells, whereas it may or may not induce such effects in normal cells to far lesser extent.

The frequency and severity of capecitabine-induced hypertriglyceridaemia in routine clinical practice: a prospective study

Background:

Capecitabine is known to rarely cause raised serum triglycerides (TG). In our centre, several patients receiving capecitabine developed raised TG levels corresponding to the ‘very high risk’ category for potentially serious acute pancreatitis.

Methods:

A fasting blood lipid screening protocol was introduced into clinical practice for patients receiving capecitabine. Patients with TGs >5 mmol l⁻¹ were treated and followed up. An 18-month prospective audit was performed to establish the incidence and severity of capecitabine-induced hypertriglyceridaemia (CIHT).

Results:

A total of 304 patients received capecitabine for colorectal cancer between January 2008 and June 2009. Of these, 212 patients (70%) were screened and 8 (3.7%) developed clinically significant hypertriglyceridaemia requiring lipid-lowering therapy. Two of the eight patients had diabetes and one had pre-existing dyslipidaemia. One suffered cerebral infarction during chemotherapy. There were no cases of acute pancreatitis. Follow-up showed that serum TGs safely and rapidly returned to normal with appropriate treatment without discontinuation of capecitabine.

Conclusions:

This is the first prospective study evaluating CIHT. These results suggest that it should be classed as a ‘common’ undesired effect of capecitabine. Despite this, the incidence does not justify routine screening in all patients. Targeted screening in those with diabetes or pre-existing hyperlipidaemia is recommended, together with adoption of a clear management policy.

Phase I and pharmacokinetic study of sequential paclitaxel and trabectedin every 2 weeks in patients with advanced solid tumors

PURPOSE

This phase I study evaluated the feasibility, safety, pharmacokinetics (PK), and preliminary evidence of anticancer activity of the sequential administration of paclitaxel and trabectedin on an every-2-week schedule in patients with refractory solid malignancies. The study also sought to determine the maximum tolerated dose (MTD) level on this schedule, as well as to recommend doses for disease-directed studies.

EXPERIMENTAL DESIGN

Twenty-seven patients were treated with paclitaxel (80-120 mg/m(2); 1-hour i.v. infusion, day 1) and trabectedin (0.525-0.775 mg/m(2); 3-hour i.v. infusion, day 2) with doses increased in successive cohorts. Blood sampling for PK and drug-drug interaction studies was done.

RESULTS

Neutropenia, which resulted in treatment delay exceeding 1 week, was the principal dose-limiting toxicity for this paclitaxel-trabectedin regimen and precluded dose escalation above 120 mg/m(2) paclitaxel and 0.650 mg/m(2) trabectedin. At the MTD (120 mg/m(2) paclitaxel and 0.650 mg/m(2) trabectedin), the safety profile was favorable in patients receiving cumulative treatment. Relevant drug-drug PK interactions between paclitaxel and trabectedin were not identified. A patient with soft tissue sarcoma had a complete response and several patients with various refractory solid malignancies showed protracted stable disease as their best response.

CONCLUSIONS

The MTD level of sequential paclitaxel 1-hour infusion (day 1) and trabectedin 3-hour infusion (day 2) administered every 2 weeks is 120 and 0.650 mg/m(2), respectively. The manageable toxicities at the MTD, preliminary evidence of antitumor activity, and lack of notable PK drug-drug interactions warrant further disease-directed studies of this regimen in relevant tumor types and settings.

Improvement of purine and pyrimidine antimetabolite-based anticancer treatment by selective suppression of mycoplasma-encoded catabolic enzymes

Most mycoplasmas are present as commensals, colonising the mucosa of our respiratory and gastrointestinal tract. Experimental data suggest that the long-term association of certain mycoplasma species with mammalian cells might favour host-cell transformation and malignancy. Moreover, increased mycoplasma infection has been noted in several cancers. Despite efforts to develop target-specific anticancer drugs, current cancer treatment still relies on the use of nucleobase or nucleoside-based analogues. Here, we provide experimental evidence that nucleoside-metabolising catabolic enzymes expressed by mycoplasmas substantially compromise the efficacy of nucleoside antimetabolites used in the treatment of cancer. We also suggest potential methods for improving future chemotherapy by suppressing mycoplasma-mediated catabolism of the anticancer nucleoside analogues.

Capecitabine: an overview of the side effects and their management

Xeloda (capecitabine), a thymidine phosphorylase activated fluoropyrimidine carbamate, is currently the only universally approved orally administered 5-fluorouracil (5-FU) prodrug. It belongs to a newer generation of orally administered fluoropyrimidines. It has been developed because of the clinical need for efficient, tolerable and convenient agents, which do not require continuous infusion. Capecitabine is not a cytotoxic drug in itself, but via a three-step enzymatic cascade, it is converted to 5-FU mainly within human cancer cells. While the drug compares favorably with 5-FU in patients with advanced or metastatic colorectal cancer and pretreated breast cancer, it also has an improved toxicity profile, mainly of gastrointestinal and dermatologic effects with a significantly lower incidence of grade 3/4 myelotoxicity compared with infusional 5-FU-based chemotherapy. Capecitabine's selective activation within the tumor allows for less systemic toxicity events. A gradient of fluoropyrimidine toxicity is observed: high in the US and low in East Asia. In addition, there is a discrepancy in tolerance of dose among patients treated in the US vs. Europe. Although patients can take the drug orally in the convenience of their own home, the key to successful management of capecitabine is the clinician's awareness of its severe, but low in incidence, adverse effects, and the patients' education, emphasizing compliance with the treatment plan, prevention and timely recognition of its toxicities.

Dose-finding phase I and pharmacokinetic study of capecitabine (Xeloda) in combination with epirubicin and cyclophosphamide (CEX) in patients with inoperable or metastatic breast cancer

OBJECTIVE

The present study aimed to identify the recommended dose (RD) of capecitabine, epirubicin and cyclophosphamide (CEX) combination treatment for inoperable or metastatic breast cancer and to assess response rate, tolerability and pharmacokinetics in Japanese patients.

METHODS

Patients received 3-week cycles of fixed-dose intravenous cyclophosphamide (600 mg/m(2), day 1), intravenous epirubicin (75-100 mg/m(2), day 1) and oral capecitabine (628-900 mg/m(2) twice daily, days 1-14). Dose escalation/deescalation decisions for consecutive cohorts were made using the continual reassessment method (CRM). RD was defined as dose level closest to that causing dose-limiting toxicity (DLT) in 33% of patients.

RESULTS

Among the 17 patients enrolled, 3 experienced DLT (hand-foot syndrome, anorexia, mucositis; all grade 3) and 3 (18%) febrile neutropenia. Based on CRM calculation, mean DLT occurrence probabilities (90% confidence intervals in parentheses) for levels 2, 3 and 4 were 21% (8-42%), 35% (17-56%) and 56% (38-71%), respectively. Level 3 was thus chosen as the RD. Combination treatment did not affect pharmacokinetic parameters of capecitabine, epirubicin or their metabolites. Objective responses were achieved by 7 patients (41%), including partial responses in 4 of 6 patients (67%) receiving the RD.

CONCLUSION

CEX represents a well-tolerated regimen, and RD for Japanese patients was determined to be capecitabine 900 mg/m(2) twice daily in combination with epirubicin 90 mg/m(2) and cyclophosphamide 600 mg/m(2) using the CRM.

Expression of thymidine phosphorylase in peripheral blood cells of breast cancer patients is not increased by paclitaxel

Background

A synergistic cytotoxic effect has been hypothesized for taxanes and capecitabine, a prodrug of 5-fluorouracil. Based on preclinical studies, this synergism has been attributed to an up-regulation of the enzyme thymidine phosphorylase (TP). Beside tumour tissue, TP is highly expressed in white blood cells, possibly causing increased hematotoxicity, when taxanes are combined with capecitabine. So far, this hypothesis has not been investigated in humans.

Methods

A total of 128 consecutive blood samples were collected from eight patients with advanced breast cancer receiving paclitaxel weekly at a dose of 80 mg/m². To assess the expression of TP in blood cells, samples were collected prior to first therapy, at the end of infusion, and up to 15 days thereafter. This procedure was repeated during the sixth application of paclitaxel. After isolation of the peripheral mononuclear blood cells, the expression of TP was assessed by ELISA. In parallel, paclitaxel level in plasma was evaluated at three selected time points as pharmacokinetic control parameter.

Results

Paclitaxel concentrations at the end of infusion did not change significantly from week 1 to week 6. The expression of TP in peripheral mononuclear blood cells decreased significantly after infusion below pretherapeutic values (p = 0.023; n = 8). After the nadir on day 3, the expression of TP increased moderately returning to baseline levels within one week. The overall picture in week 6 was similar to week 1. Using a trend analysis, neither a short-term nor a long-term induction of TP was observed.

Conclusion

TP in peripheral mononuclear blood cells was hardly regulated under therapy with paclitaxel. Therefore, no increased haematotoxicity due to TP upregulation is expected from the combination of taxanes and capecitabine.

Expression of the High-Affinity Fluoropyrimidine-Preferring Nucleoside Transporter hCNT1 Correlates with Decreased Disease-Free Survival in Breast Cancer

PURPOSE

Nucleoside and nucleobase derivatives are currently used in the treatment of a variety of solid tumors; however, the role of plasma membrane transporters as biomarkers of drug metabolism has not been fully addressed. Thus, the purpose of this study was to determine whether the concentrative nucleoside transporter hCNT1 is a predictive marker of therapeutic response.

METHODS

We studied a cohort of 90 breast cancer patients who were treated with cyclophosphamide-methotrexate-5-fluorouracil after surgery and then monitored for up to 108 months. hCNT1 and enzymes associated with nucleotide metabolism (thymidine phosphorylase, dihydropyrimidine dehydrogenase and thymidylate synthase) were assessed immunohistochemically in tissue samples.

RESULTS

Human CNT1 presence was mostly cytoplasmic, with some nuclear staining. The percentage of hCNT1-positive cells correlated positively with the expression of thymidine phosphorylase and dihydropyrimidine dehydrogenase. Nuclear staining correlated negatively with decreased disease-free survival, whereas the percentage of hCNT1-positive cells correlated positively with reduced long-term survival, with the hCNT1-positive index (>80%) being indicative of poor prognosis. A relative risk of relapse was associated with high hCNT1-positive indexes, whereas when this parameter was combined with the nodal status (positive), a high risk of relapse was found, suggesting that both parameters may reflect a poor prognosis.

CONCLUSIONS

These results indicate that the expression of the high-affinity concentrative nucleoside transporter hCNT1 has a prognostic value in determining disease-free survival and risk of relapse in breast cancer patients undergoing surgery followed by cyclophosphamide-methotrexate-5-fluorouracil chemotherapy.

Gene expression analysis using human cancer xenografts to identify novel predictive marker genes for the efficacy of 5-fluorouracil-based drugs

The development of a diagnostic method for predicting the therapeutic efficacy or toxicity of anticancer drugs is a critical issue. We carried out a gene expression analysis to identify genes whose expression profiles were correlated with the sensitivity of 30 human tumor xenografts to 5-fluorouracil (5-FU)-based drugs (tegafur + uracil [UFT], tegafur + gimeracil + oteracil [S-1], 5'-deoxy-5-fluorouridine [5'-DFUR], and N4-pentyloxycarbonyl-5'-deoxy-5-fluorocytidine [capecitabine]), as well as three other drugs (cisplatin [CDDP], irinotecan hydrochloride [CPT-11], and paclitaxel) that have different modes of action. In the present study, we focused especially on the fluoropyrimidines. The efficacy of all anticancer drugs was assayed using human tumor xenografts in nude mice. The mRNA expression profile of each of these xenografts was analyzed using a Human Focus array. Correlation analysis between the gene expression profiles and the chemosensitivities of seven drugs identified 39 genes whose expression levels were correlated significantly with multidrug sensitivity, and we suggest that the angiogenic pathway plays a pivotal role in resistance to fluoropyrimidines. Furthermore, many genes showing specific correlations with each drug were also identified. Among the candidate genes associated with 5-FU resistance, the dihydropyrimidine dehydrogenase mRNA expression profiles of the tumors showed a significant negative correlation with chemosensitivity to all of the 5-FU based drugs except for S-1. Therefore, the administration of S-1 might be an effective strategy for the treatment of high dihydropyrimidine dehydrogenase-expressing tumors. The results of the present study may enhance the prediction of tumor response to anticancer drugs and contribute to the development of tailor-made chemotherapy.

Weekly paclitaxel plus capecitabine in advanced breast cancer patients: dose-finding trial of GOIRC and GOL

BACKGROUND

Paclitaxel and capecitabine have demonstrated a synergic effect and significant antitumor activity in patients with advanced breast cancer. A weekly schedule of paclitaxel obtained a response rate of 50-68% in advanced breast cancer and less serious side-effects.

PATIENTS AND METHODS

Thirty-two patients with advanced breast cancer pretreated with chemotherapy were enrolled in a dose-finding trial to determine the maximum tolerated dose (MTD) and the dose-limiting toxicity (DLT) of paclitaxel given on days 1, 8 and 15 of each cycle combined with capecitabine given twice daily from day 1 through day 14, every 21 days. Three patients were recruited at one of six dose levels (paclitaxel 70-100 mg/m2, capecitabine 1650-2500 mg/m2).

RESULTS

Thirty-two patients were accrued and 31 were evaluated for toxicity. One DLT has been experienced at level VI as diarrhea grade 3. We determined dose level V as the MTD, but we recommend dose level IV for phase II studies (capecitabine 1250 mg/m2 orally twice daily plus paclitaxel 80 mg/m2 intravenously weekly), owing to cumulative toxicity at level V. The objective response rate was 43%.

CONCLUSIONS

Weekly paclitaxel plus capecitabine is a safety and active chemotherapy in previously treated metastatic breast cancer.

Capecitabine: a review

BACKGROUND

Fluorouracil (FU) is an antimetabolite with activity against numerous types of neoplasms, including those of the breast, esophagus, larynx, and gastrointestinal and genitourinary tracts. Systemic toxicity, including neutropenia, stomatitis, and diarrhea, often occur due to cytotoxic nonselectivity. Capecitabine was developed as a prodrug of FU, with the goal of improving tolerability and intratumor drug concentrations through tumor-specific conversion to the active drug.

OBJECTIVES

The purpose of this article is to review the available information on capecitabine with respect to clinical pharmacology, mechanism of action, pharmacokinetic and pharmacodynamic properties, clinical efficacy for breast and colorectal cancer adverse-effect profile, documented drug interactions, dosage and administration, and future directions of ongoing research.

METHODS

Relevant English-language literature was identified through searches of PubMed (1966 to August 2004), International Pharmaceutical Abstracts (1977 to August 2004), and the Proceedings of the American Society of Clinical Oncology (January 1995 to August 2004). Search terms included capecitabine, Xeloda, breast cancer, and colorectal cancer. The references of the identified articles were reviewed for additional sources. In addition, product information was obtained from Roche Pharmaceuticals. Studies from the identified literature that addressed this article's objectives were selected for review, with preference given to Phase II/III trials.

RESULTS

Capecitabine is an oral prodrug that is converted to its only active metabolite, FU, by thymidine phosphorylase. Higher levels of this enzyme are found in several tumors and the liver, compared with normal healthy tissue. In adults, capecitabine has a bioavailability of approximately 100% with a Cmax of 3.9 mg/L, Tmax of 1.5 to 2 hr, and AUC of 5.96 mg.h/L. The predominant route of elimination is renal, and dosage reduction of 75% is recommended in patients with creatinine clearance (CrCl) of 30 to 50 mL/min. The drug is contraindicated if CrCl is < 30 mL/min. Capecitabine has shown varying degrees of efficacy with acceptable tolerability in numerous cancers including prostate, renal cell, ovarian, and pancreatic, with the largest amount of evidence in metastatic breast and colorectal cancer. Single-agent capecitabine was compared with IV FU/leucovorin (LV) using the bolus Mayo Clinic regimen in 2 Phase III trials as first-line treatment for patients with metastatic colorectal cancer. Overall response rate (RR) favored the capecitabine arm (26% vs 17%, P < 0.001); however, this did not translate into a difference in time to progression (TTP) (4.6 months vs 4.7 months) or overall survival (OS) (12.9 months vs 12.8 months). In Phase II noncomparative trials, combinations of capecitabine with oxaliplatin or irinotecan have produced results similar to regimens combining FU/LV with the same agents in patients with colorectal cancer. In metastatic breast cancer patients who had received prior treatment with an anthracycline-based regimen, a Phase III trial comparing the combination of capecitabine with docetaxel versus docetaxel alone demonstrated superior objective tumor RR (42% vs 30%, P = 0.006), median TTP (6.1 months vs 4.2 months, P < 0.001), and median OS (14.5 months vs 11.5 months, P = 0.013) with the combination treatment. Noncomparative Phase II studies have also supported efficacy in patients with metastatic breast cancer pretreated with both anthracyclines and taxanes, yielding an overall RR of 15% to 29% and median OS of 9.4 to 15.2 months. The most common dose-limiting adverse effects associated with capecitabine monotherapy are hyperbilirubinemia, diarrhea, and hand-foot syndrome. Myelosuppression, fatigue and weakness, abdominal pain, and nausea have also been reported. Compared with bolus FU/LV, capecitabine was associated with more hand-foot syndrome but less stomatitis, alopecia, neutropenia requiring medical management, diarrhea, and nausea. Capecitabine has been reported to increase serum phenytoin levels and the international normalized ratio in patients receiving concomitant phenytoin and warfarin, respectively. The dose of capecitabine approved by the US Food and Drug Administration (FDA) for both metastatic colorectal and breast cancer is 1250 Mg/M2 given orally twice per day, usually separated by 12 hours for the first 2 weeks of every 3-week cycle.

CONCLUSIONS

Capecitabine is currently approved by the FDA for use as first-line therapy in patients with metastatic colorectal cancer when single-agent fluoropyrimidine therapy is preferred. The drug is also approved for use as (1) a single agent in metastatic breast cancer patients who are resistant to both anthracycline- and paclitaxel-based regimens or in whom further anthracycline treatment is contra indicated and (2) in combination with docetaxel after failure of prior anthracycline-based chemotherapy. Single-agent and combination regimens have also shown benefits in patients with prostate, pancreatic, renal cell, and ovarian cancers. Improved tolerability and comparable efficacy compared with IV FU/LV in addition to oral administration make capecitabine an attractive option for the treatment of several types of cancers as well as the focus of future trials.

Capecitabine with weekly paclitaxel for advanced breast cancer: a phase I dose-finding trial

OBJECTIVE

To determine the maximum tolerated dose (MTD), toxicity and activity of combined weekly paclitaxel and capecitabine in patients with metastatic breast cancer.

METHODS

Sixteen patients with metastatic breast cancer, of whom 15 were evaluable for toxicity and response, were enrolled in 7 Swiss centers. Paclitaxel 80 mg/m2 was given intravenously on days 1, 8 and 15. Capecitabine was administered orally on days 1 through 14 using five different dose levels. Both drugs were given in a 21-day schedule.

RESULTS

Capecitabine could be administered at doses commonly used for the drug as a single agent, i.e. 1,250 mg/m2 twice daily in combination with weekly paclitaxel. Hematological and other toxicities did not appear to be dose-limiting; however, significant skin and nail toxicities were observed. A response or stable disease was observed in 87% of patients [13/15; exact 95% confidence interval (CI) 60-98%], with 2 complete responses, 4 partial responses (overall response rate 40%, exact 95% CI 16-68%) and 7 patients with stable disease for at least 9 weeks.

CONCLUSION

The phase I evaluation of capecitabine in combination with fixed-dose weekly paclitaxel did not allow the definition of an MTD of capecitabine based on the predefined criteria. Instead, the dose for the phase II evaluation was determined based on the occurrence of toxicity in later courses and on experience with other regimens containing capecitabine. Capecitabine (1,000 mg/m2 twice daily, days 1-14, every 3 weeks) with paclitaxel (80 mg/m2 weekly) is a promising combination for advanced breast cancer now being investigated in a phase II trial.

Capecitabine Plus Paclitaxel As Front-Line Combination Therapy for Metastatic Breast Cancer: A Multicenter Phase II Study

Purpose

The goal of this multicenter, open-label phase II study was the clinical evaluation of combination therapy with the oral fluoropyrimidine capecitabine and the taxane paclitaxel in patients with metastatic breast cancer (MBC).

Patients and Methods

Forty-seven patients with MBC received oral capecitabine at 1,650 mg/m2/d (825 mg/m2 twice daily) on days 1 through 14, and intravenous infusion of paclitaxel at 175 mg/m2 on day 1 of each 21-day treatment cycle. Treatment continued until disease progression, intolerable toxicity, or patient's decision to discontinue. Patients (35 to 76 years old) had a median Karnofsky performance status of 90%. Forty-four patients (94%) received study treatment as first-line therapy for metastatic disease.

Results

Objective responses occurred in 24 (51%) patients; seven (15%) complete responses and 17 (36%) partial responses. Stable disease lasting 180 days or more was observed in nine (19%); the clinical response rate was 70%. Median duration of response was 12.6 months, median time to disease progression was 10.6 months, and median overall survival time was 29.9 months. The most common treatment-related adverse events, regardless of severity, were alopecia, hand-foot syndrome, nausea, and fatigue. Neutropenia (15%), alopecia (13%), and hand-foot syndrome (11%) were the only grade 3 or 4 treatment-related adverse events that occurred in more than 10% of patients.

Conclusion

The combination of capecitabine plus paclitaxel is a highly active and generally well-tolerated regimen for first-line treatment of MBC.

Interferon-alpha 2a up-regulated thymidine phosphorylase and enhanced antitumor effect of capecitabine on hepatocellular carcinoma in nude mice

PURPOSE

To investigate the antitumor effect of interferon-alpha 2a (IFN-alpha2a) combined with capecitabine on hepatocellular carcinoma (HCC) in nude mice in relation to thymidine phosphorylase (TP) expression.

METHODS

Thirty nude mice bearing orthotopic xenografts of a human HCC tumor (LCI-D20) were divided into control, capecitabine, IFN-alpha2a, and combination (capecitabine plus IFN-alpha2a) groups. Tumor growth was determined by measuring the tumor volume. An enzyme-linked immunosorbent assay (ELISA) was used to study the TP expression in the cancer tissues of the liver.

RESULTS

IFN-alpha2a enhanced the sensitivity of the LCI-D20 tumor response to capecitabine treatment. The tumor volume was significantly reduced in the capecitabine (455+/-236 mm(3)), IFN-alpha2a (248 +/- 114 mm(3)) or combination (46 +/- 29 mm(3)) treatment groups as compared to the control (1,033 +/- 146 mm(3)) (P < 0.01). A significant difference was also found between the single treatment (capecitabine or interferon) and combination treatment group (P < 0.01 and P < 0.05, respectively). IFN-alpha2a up-regulated TP expression in LCI-D20 tumor. An approximate 1.5-fold increase in TP expression was observed in the mice which received IFN-alpha2a treatment compared to the control mice.

CONCLUSION

IFN-alpha2a enhanced the antitumor effect of capecitabine on HCC in nude mice, which might be ascribed to the up-regulation of TP expression in liver cancer tissues by IFN-alpha2a.

Phase I and pharmacokinetic study of the association of capecitabine-cisplatin in head and neck cancer patients

The combination of cisplatin and 5-fluorouracil (5-FU) is considered to be the standard treatment in induction chemotherapy for patients with squamous cell carcinoma of the head and neck. Capecitabine (Xeloda) is an oral fluoropyrimidine that is preferentially activated at the tumoral level, exploiting the higher thymidine phosphorylase activity in tumoral tissue. This phase I trial was conducted in patients with locally recurrent or metastatic head and neck carcinoma. The treatment plan included cisplatin on day 1 every 21 days, followed by capecitabine twice daily from day 2 to day 15, with a 1-week rest period. Pharmacokinetic investigations concerned plasma measurement of unchanged capecitabine, 5'-deoxy-5-fluorocytidine, 5'-doxifluridine and 5-FU using an optimized high performance liquid chromatography method, and cisplatin measurement in plasma using a limited sampling procedure. Twenty-one patients were included (mean age 61 years, range 46-76 years). Dose (mg/m(2)) increments for cisplatin and capecitabine (b.i.d.), respectively, were as follows: level 1, 80 and 1000 (three patients); level 2, 100 and 1000 (12 patients); and level 3, 100 and 1125 (five patients). Dose-limiting toxicities occurring during the first cycle (grade >/= 3) were observed on level 2 (one patient with diarrhea, nausea, vomiting, hand-foot syndrome, one toxic death due to renal failure and neutropenia, one patient with neutropenia) and on level 3 (one patient with diarrhea, one patient with hand-foot syndrome and one patient with neutrothrombocytopenia). Due to delayed side-effects, 14 patients (67%) had repeated cycles every 28 days instead of 21 days as initially planned. Objective response was obtained in seven patients (three complete responses and four partial responses). There was no evidence of pharmacokinetic-pharmacodynamic relationships with the drugs and metabolites investigated. Combination of capecitabine and cisplatin is feasible, with a very promising response rate. The recommended doses for further phase II studies are those of level 2 with cisplatin 100 mg/m(2) on day 1 and capecitabine 1000 mg/m(2) b.i.d. on days 1-14, every 28 days.

Development of and clinical experience with capecitabine (Xeloda®) in the treatment of solid tumours

The oral fluoropyrimidine capecitabine (Xeloda) delivers 5-FU to the tumour site, thereby limiting the side effects and other complications associated with intravenous (i.v.) 5-FU. As an oral drug, capecitabine is preferred to 5-FU by many patients as it can be conveniently taken at home. In first-line metastatic colorectal cancer (MCRC), capecitabine results in superior response rates and equivalent progression-free and overall survival compared with i.v. 5-FU/LV. There is also increasing evidence for replacing i.v. 5-FU with capecitabine in combination with other anticancer agents (e.g. oxaliplatin and irinotecan) in MCRC and in the adjuvant treatment of early stage colon cancer. In anthracycline-pretreated metastatic breast cancer (MBC), adding capecitabine to docetaxel improves survival, time to progression (TTP) and response rates beyond docetaxel. Single-agent capecitabine is also effective in pretreated MBC and is a promising first-line therapy. Capecitabine has a favourable safety profile, the most frequent adverse events being hand-foot syndrome, stomatitis and diarrhoea. Because capecitabine is orally administered, it is possible to intervene promptly with dose interruption/reduction to resolve adverse events without impacting on efficacy. The increasing availability of capecitabine in the home-based setting requires careful consideration of the role of the oncology nurse, who is the key link between the patient and clinician for effective and efficient management.

A phase II study of weekly docetaxel plus capecitabine for patients with advanced nonsmall cell lung carcinoma

BACKGROUND

Docetaxel is an active agent in advanced nonsmall-cell lung carcinoma (NSCLC) and demonstrates preclinical and clinical synergism with capecitabine. We conducted the current Phase II study to evaluate the efficacy and safety of the docetaxel/capecitabine combination in chemotherapy-naive patients with advanced NSCLC.

METHODS

Eligibility required Stage IIIB or IV NSCLC, bidimensionally measurable disease, and an Eastern Cooperative Oncology Group performance score of 2 or lower. Treatment consisted of docetaxel 36 mg/m(2) intravenously on Days 1 and 8 plus capecitabine 1000 mg/m(2) orally twice per day on Days 1-14 of a 21-day cycle, for a maximum of 6 cycles.

RESULTS

Of 39 patients enrolled, 39 and 36 patients were evaluated for toxicity and response, respectively. The overall response rate was 53% (95% confidence interval [CI], 37-69%) with 19 partial responses (no complete response). The median duration of response was 6.2 months (range, 2.1-15.7 months). At a median follow-up of 14.2 months, 19 patients died. The median overall survival time was 17.8 months, with a 1-year survival rate of 56.4% (95% CI, 40.9-72.0%). There were two treatment-related deaths (one death due to pneumonia and one due to sepsis). Hematologic toxicity was mild to moderate. Thirteen percent of the patients had Grade 3 or 4 neutropenia. However, Grade 2 or 3 nonhematologic toxicities were frequent, which included asthenia (51%), stomatitis (33%), hand-foot syndrome (33%), and diarrhea (29%).

CONCLUSIONS

The docetaxel/capecitabine combination showed promising antitumor activity for chemotherapy-naive patients with advanced NSCLC, However, it was frequently associated with moderate-to-severe nonhematologic toxicities, suggesting clinical synergism in both efficacy and toxicity. Further adjustment of the dose schedule is recommended to maximize the therapeutic index.

Clinical pharmacokinetic/pharmacodynamic and physiologically based pharmacokinetic modeling in new drug development: the capecitabine experience

Preclinical studies, along with Phase I, II, and III clinical trials demonstrate the pharmacokinetics, pharmacodynamics, safety and efficacy of a new drug under well controlled circumstances in relatively homogeneous populations. However, these types of studies generally do not answer important questions about variability in specific factors that predict pharmacokinetic and pharmacodynamic (PKPD) activity, in turn affecting safety and efficacy. Semi-physiological and clinical PKPD modeling and simulation offer the possibility of utilizing data obtained in the laboratory and the clinic to make accurate characterizations and predictions of PKPD activity in the target population, based on variability in predictive factors. Capecitabine is an orally administered pro-drug of 5-fluorouracil (5-FU), designed to exploit tissue-specific differences in metabolic enzyme activities in order to enhance efficacy and safety. It undergoes extensive metabolism in multiple physiologic compartments, and presents particular challenges for predicting pharmacokinetic and pharmacodynamic activity in humans. Clinical and physiologically based pharmacokinetic (PBPK) and pharmacodynamic models were developed to characterize the activity of capecitabine and its metabolites, and the clinical consequences under varying physiological conditions such as creatinine clearance or activity of key metabolic enzymes. The results of the modeling investigations were consistent with capecitabine's rational design as a triple pro-drug of 5-FU. This paper reviews and discusses the PKPD and PBPK modeling approaches used in capecitabine development to provide a more thorough understanding of what the key predictors of its PBPK activity are, and how variability in these predictors may affect its PKPD, and ultimately, clinical outcomes.

Capecitabine: a review of its pharmacology and therapeutic efficacy in the management of advanced breast cancer

Capecitabine is an orally administered prodrug of fluorouracil which is indicated in the US and Europe, in combination with docetaxel, for the treatment of patients with metastatic breast cancer failing anthracycline therapy, and as monotherapy for metastatic breast cancer resistant to paclitaxel and anthracycline therapy (US) or failing intensive chemotherapy (Europe). Capecitabine is also approved for use in metastatic colorectal cancer. Capecitabine is metabolically activated preferentially at the tumour site, and shows antineoplastic activity and synergy with other cytotoxic agents including cyclophosphamide or docetaxel in animal models. Bioavailability after oral administration is close to 100%. In patients with pretreated advanced breast cancer, capecitabine is effective as monotherapy and also in combination with other agents. Combination therapy with capecitabine 1,250 mg/m(2) twice daily for 2 weeks of every 3-week cycle plus intravenous docetaxel 75 mg/m(2) on day one of each cycle was superior to intravenous monotherapy with docetaxel 100 mg/m(2) on day one of each cycle. Capecitabine plus docetaxel significantly reduced the risks of disease progression and death by 35% (p = 0.0001) and 23% (p < 0.05), respectively, and significantly increased median survival (p < 0.05) and objective response rates (p < 0.01). Efficacy has also been demonstrated with capecitabine monotherapy and combination therapy in previously untreated patients in preliminary trials. The most common adverse effects occurring in patients receiving capecitabine monotherapy include lymphopenia, anaemia, diarrhoea, hand-and-foot syndrome, nausea, fatigue, hyperbilirubinaemia, dermatitis and vomiting (all >25% incidence). While gastrointestinal events and hand-and-foot syndrome occurred more often with capecitabine than with paclitaxel or a regimen of cyclophosphamide, methotrexate and fluorouracil (CMF), neutropenic fever, arthralgia, pyrexia and myalgia were more common with paclitaxel, and nausea, stomatitis, alopecia and asthenia were more common with CMF. The incidence of adverse effects and hospitalisation was similar in patients receiving capecitabine plus docetaxel and those receiving docetaxel monotherapy. In conclusion, capecitabine, an oral prodrug of fluorouracil which is activated preferentially at the tumour site, is an effective and convenient addition to the intravenous polychemotherapeutic treatment of advanced breast cancer in pretreated patients, and also has potential as a component of first-line combination regimens. Combined capecitabine plus docetaxel therapy resulted in similar rates of treatment-related adverse effects and hospitalisation to those seen with docetaxel monotherapy. Capecitabine is also effective as monotherapy in pretreated patients and phase II data for capecitabine as first-line monotherapy are also promising. While gastrointestinal effects and hand-and-foot syndrome occur often with capecitabine, the tolerability profile was comparatively favourable for other adverse effects (notably, neutropenia and alopecia).

Treatment for anthracycline-pretreated metastatic breast cancer

As a result of increasing anthracycline use earlier in the course of breast cancer, oncologists are frequently faced with the challenge of treating patients whose disease has progressed during or following anthracycline therapy or who are ineligible for further anthracycline therapy. Many of these women remain candidates for cytotoxic chemotherapy, and several treatment options exist. Until recently, the taxanes, docetaxel in particular, were widely regarded as the most effective therapy for these patients, based on a survival advantage observed with docetaxel. However, a recent phase III study demonstrated that the addition of capecitabine to docetaxel results in superior overall survival (with a 3-month improvement in median survival), superior time to disease progression, and a superior response rate, with a manageable safety profile. Capecitabine/docetaxel is the first cytotoxic combination to improve survival over standard monotherapy in patients with anthracycline-pretreated metastatic breast cancer. Moreover, the survival benefit can be attributed to the addition of capecitabine, as it was achieved despite the lower dose of docetaxel administered in the combination arm. Quality of life was maintained with capecitabine/docetaxel combination therapy, which further supports the use of this regimen in patients with anthracycline-pretreated metastatic breast cancer. Pharmacoeconomic modeling using the data from the phase III trial has shown that the capecitabine/docetaxel combination therapy is highly cost effective when compared with other cancer treatments that improve survival. This review describes several treatment options for patients with anthracycline-pretreated breast cancer, including the phase III data (efficacy, tolerability, quality of life, and pharmacoeconomics) for capecitabine plus docetaxel in this setting.

Penetration of capecitabine and its metabolites into malignant and healthy tissues of patients with advanced breast cancer

Capecitabine is an oral prodrug of 5-fluorouracil (FU). Since FU concentrations achieved in malignant lesions are an important determinant of efficacy, we investigated the intratumoral transcapillary transfer of capecitabine and its metabolites in vivo. A total of 10 patients with skin metastases from breast cancer received a daily dose of 2500 mg m(-2) capecitabine administered orally in two divided doses for 2 weeks. Microdialysis probes were inserted into a cutaneous metastasis and subcutaneous connective tissue to evaluate the interstitial tissue pharmacokinetics of capecitabine and its metabolites 5'-deoxy-5-fluorocytidine (DFCR), 5'-deoxy-5-fluorouridine (DFUR), and FU by capillary electrophoresis. As intended with the prodrug design of capecitabine, FU was present in low concentrations in tumour interstitium (median c(max): 0.26 microg ml(-1)) when compared with capecitabine, DFCR, and DFUR (median c(max): 2.66, 4.22, and 2.13 microg ml(-1), respectively). Capecitabine and its metabolites easily penetrated malignant and healthy tissue and equilibrated within 45 min between plasma and tissue interstitium. Considering tissue exposure at the extracellular level, no significant differences between healthy and malignant tissues were observed. Our data show that absorption and metabolism determined the tissue pharmacokinetics of capecitabine. There was no evidence of drug tolerance, which may be attributed to impaired transcapillary transfer into tissue, even after repeated administration as shown for three patients.

Clinical studies of three oral prodrugs of 5-fluorouracil (capecitabine, UFT, S-1): a review

Although 5-fluorouracil (5-FU) was first introduced in 1957, it remains an essential part of the treatment of a wide range of solid tumors. 5-FU has antitumor activity against epithelial malignancies arising in the gastrointestinal tract and breast as well as the head and neck, with single-agent response rates of only 10%-30%. Although 5-FU is still the most widely prescribed agent for the treatment of colorectal cancer, less than one-third of patients achieve objective responses. Recent research has focused on the biomodulation of 5-FU to improve the cytotoxicity and therapeutic effectiveness of this drug in the treatment of advanced disease. As all the anticancer agents, 5-FU leads to several toxicities. The toxicity profile of 5-FU is schedule dependent. Myelotoxicity is the major toxic effect in patients receiving bolus doses. Hand-foot syndrome (palmar-plantar erythrodysesthesia), stomatitis, and neuro- and cardiotoxicities are associated with continuous infusions. Other adverse effects associated with both bolus-dose and continuous-infusion regimens include nausea and vomiting, diarrhea, alopecia, and dermatitis. All these reasons explain the need for more effective and less toxic fluoropyrimidines. In the first part of this review, we briefly present the metabolic pathways of 5-FU responsible for the efficacy and toxicity of this drug. This knowledge is also necessary to understand the target(s) of biomodulation. The second part is devoted to a review of the literature on three recent prodrugs of 5-FU, i.e., capecitabine, UFT (ftorafur [FTO] plus uracil), and S-1 (FTO plus 5-chloro-2,4-dihydroxypyridine plus potassium oxonate). The pharmacological principles that have influenced the development of these new drugs and our current knowledge of the clinical pharmacology of these new agents, focusing on antitumor activity and toxicity, are presented. The literature was analyzed until March 2002. This review is intended to be as exhaustive as possible since it was conceived as a work tool for readers wanting to go further.

Nucleoside analogues and nucleobases in cancer treatment

Cytotoxic nucleoside analogues and nucleobases were among the first chemotherapeutic agents to be introduced for the medical treatment of cancer. This family of compounds has grown to include a variety of purine and pyrimidine nucleoside derivatives with activity in both solid tumours and malignant disorders of the blood. These agents behave as antimetabolites, compete with physiological nucleosides, and interact with a large number of intracellular targets to induce cytotoxicity. Progress has recently been made in the identification and characterisation of nucleoside transporters and the enzymes of nucleoside metabolism. In addition, there is now greater understanding of the molecular mechanisms of anticancer nucleoside activity, which provides opportunities for potentiating their antitumour effects. Strategies to optimise intracellular analogue accumulation and to enhance cancer-cell selectivity are proving beneficial in clinical trials.

Superior survival with capecitabine plus docetaxel combination therapy in anthracycline-pretreated patients with advanced breast cancer: phase III trial results

PURPOSE

Docetaxel and capecitabine, a tumor-activated oral fluoropyrimidine, show high single-agent efficacy in metastatic breast cancer (MBC) and synergy in preclinical studies. This international phase III trial compared efficacy and tolerability of capecitabine/docetaxel therapy with single-agent docetaxel in anthracycline-pretreated patients with MBC.

PATIENTS AND METHODS

Patients were randomized to 21-day cycles of oral capecitabine 1,250 mg/m(2) twice daily on days 1 to 14 plus docetaxel 75 mg/m(2) on day 1 (n = 255) or to docetaxel 100 mg/m(2) on day 1 (n = 256).

RESULTS

Capecitabine/docetaxel resulted in significantly superior efficacy in time to disease progression (TTP) (hazard ratio, 0.652; 95% confidence interval [CI], 0.545 to 0.780; P =.0001; median, 6.1 v 4.2 months), overall survival (hazard ratio, 0.775; 95% CI, 0.634 to 0.947; P =.0126; median, 14.5 v 11.5 months), and objective tumor response rate (42% v 30%, P =.006) compared with docetaxel. Gastrointestinal side effects and hand-foot syndrome were more common with combination therapy, whereas myalgia, arthralgia, and neutropenic fever/sepsis were more common with single-agent docetaxel. More grade 3 adverse events occurred with combination therapy (71% v 49%, respectively), whereas grade 4 events were slightly more common with docetaxel (31% v 25% with combination).

CONCLUSION

The significantly superior TTP and survival achieved with the addition of capecitabine to docetaxel 75 mg/m(2), with the manageable toxicity profile, indicate that this combination provides clear benefits over single-agent docetaxel 100 mg/m(2). Docetaxel/capecitabine therapy is an important treatment option for women with anthracycline-pretreated MBC.

Capecitabine: fulfilling the promise of oral chemotherapy

Capecitabine is a synthetic oral fluoropyrimidine carbamate that is sequentially activated in a three-step process, which results in the preferential production of 5-fluorouracil in tumours, rather than in the normal surrounding tissue. Capecitabine is proven to be as effective as the combination of 5-fluorouracil and leucovorin administered on the Mayo clinic schedule in patients with metastatic colorectal cancer. It has also been proven to be effective in patients with metastatic breast cancer that has progressed despite prior anthracyclines and taxoids. More recently, it has also been shown to increase survival in combination with docetaxel in patients with metastatic breast cancer in comparison to docetaxel alone. This article reviews the pharmacology and clinical activity of capecitabine, as well as combinations of capecitabine with other chemotherapeutic agents and future directions of investigation with this convenient and widely active antitumour therapy.

Pharmacobiologically based scheduling of capecitabine and docetaxel results in antitumor activity in resistant human malignancies

PURPOSE

Capecitabine and docetaxel have demonstrated preclinical antitumor synergy. This synergy is thought to occur from docetaxel-mediated upregulation of thymidine phosphorylase (dThdPase), an enzyme responsible for the relative tumor selectivity of capecitabine. On the basis of the time-dependency and transiency for this upregulation, we performed a phase I study of capecitabine in combination with weekly docetaxel. We hypothesized that weekly docetaxel would result in sustained dThdPase expression and that capecitabine administration at times of maximum dThdPase upregulation would increase the therapeutic index for this combination.

PATIENTS AND METHODS

Patients with advanced solid malignancies received docetaxel on days 1, 8, and 15, and capecitabine bid on days 5 to 18, every 4 weeks. Docetaxel was fixed at 36 mg/m(2)/wk, whereas capecitabine was escalated in successive patients cohorts.

RESULTS

Sixteen patients received 77 courses at capecitabine doses from 950 to 1,500 mg/m(2)/d. The most common toxicities were hand-foot syndrome, diarrhea, nausea/vomiting, and asthenia. Grades 3 to 4 hematologic toxicities were infrequent and no treatment-related hospitalizations occurred. Three of three patients treated at 1,500/36 mg/m(2) capecitabine/docetaxel developed grade 3 hand-foot syndrome or diarrhea during either their first or second course, whereas only two of 13 patients at 1,250/36 mg/m(2) doses developed significant toxicity. Antitumor responses (n = 7) occurred in patients with hepatocellular, non-small-cell lung, and chemotherapy-refractory breast, bladder, and colorectal carcinomas. Prolonged stabilizations occurred in patients with metastatic mesothelioma (n = 2), chemorefractory non-small-cell lung carcinoma, and bronchioloalveolar carcinoma.

CONCLUSION

Capecitabine in combination with weekly docetaxel is well tolerated. Recommended doses are capecitabine 1,250 mg/m(2)/d (625 mg/m(2) bid) with docetaxel 36 mg/m(2)/wk. The acceptable toxicity profile in this dose schedule, and the antitumor activity observed, warrant further evaluation of this regimen.

A phase I study of oral uracil-ftorafur plus folinic acid in combination with weekly paclitaxel in patients with solid tumors

INTRODUCTION

Ftorafur is an orally available prodrug of 5-fluorouracil (5-FU). Its combination with uracil in a molar ratio of 1:4 (UFT) increases the 5-FU concentration in tumor cells compared with ftorafur alone. Paclitaxel has a broad spectrum of activity against solid tumors and synergic effects with UFT have been demonstrated in vitro. A phase I study was performed to determine the maximum tolerated dose of the combination of UFT and paclitaxel in patients with advanced solid tumors.

STUDY DESIGN

UFT and folinic acid were applied at 300 mg/m2/day and 90 mg/day, respectively, on days 1-28, repeated on day 36. Paclitaxel was applied on days 1, 8, 15 and 22 of each cycle. The starting dose of paclitaxel was 50 mg/m2 and escalation in 10 mg/m2 steps was performed up to 100 mg/m2 weekly.

RESULTS

Forty-seven consecutive patients with various solid tumors have been included in six different dose levels. One hundred and thirty cycles have been applied. The treatment was well tolerated overall. Most frequently encountered adverse effects were gastrointestinal and hematological toxicity (diarrhea CTC 3/4 in 6% of patients, anemia in 11%, leukocytopenia in 9%, polyneuropathy in 9%, fatigue in 11%, other in 6%). Partial remissions were observed in 28% of patients.

CONCLUSION

Owing to the lack of overlapping toxicities, UFT/folinic acid plus paclitaxel can be combined at doses of proven single agent activity. Side effects are mainly attributable to the gastrointestinal toxicity of UFT and to the neuro- and hematotoxicity of paclitaxel. The recommended doses for phase II studies are 300 mg/m2 of UFT plus 90 mg of folinic acid on days 1-28, and 90 mg/m2 of paclitaxel weekly.

Capecitabine (Xeloda): from the laboratory to the patient's home

Attempts at improving the efficacy of 5-fluorouracil (5-FU) by protracted continuous infusion and/or biochemical modulation have been hindered by the need for indwelling central venous catheters and their associated toxicity. Capecitabine, an oral fluoropyrimidine carbamate, has been rationally synthesized as an inactive precursor that is absorbed intact through the intestinal mucosa and is sequentially converted by an enzymatic cascade involving 3 distinct enzymes to 5'-deoxy-5-fluorocytidine, to 5'-deoxy-5-fluorouridine (5'-DFUR), and finally to 5-FU. Preclinical studies provided evidence of preferential intratumoral conversion of inactive 5'-DFUR to active 5-FU due to the relative overexpression of the final anabolizing enzyme, thymidine phosphorylase, in tumor tissues, with a resultant decrease of 5-FU exposure in normal tissues. The safety of capecitabine and optimal dosing schedules have been explored in phase I/II studies, resulting in the evaluation of the intermittent schedule (1250 mg/m2 twice daily for 14 days, every 3 weeks) in most subsequent clinical trials. Two large randomized phase III studies in patients with metastatic colon cancer established at least equivalent efficacy and improved tolerability with capecitabine compared to the Mayo Clinic bolus 5-FU/leucovorin regimen. The most common treatment-related adverse events are palmar-plantar erythrodysesthesia, diarrhea, and stomatitis, with grade 3/4 events occurring in 17%, 15%, and 2%-8% of patients, respectively. Myelosuppression was minimal. Overall toxicity was easily managed, with a significant reduction in the frequency of hospitalizations and medical resource use. The spectrum of clinical efficacy of capecitabine is expected to encompass other tumor types and administration in the adjuvant setting. As a home-based outpatient regimen, capecitabine represents a safe and effective advance in modern drug development.

Taxanes and capecitabine in combination: rationale and clinical results

The clinical utility of capecitabine as a single agent in metastatic breast cancer has been demonstrated with significant responses seen in women already treated with anthracyclines and taxanes. A phase II study in older women with metastatic breast cancer demonstrated capecitabine to be an effective front-line therapeutic agent. Clinical trials of capecitabine in combination with the taxanes, paclitaxel and docetaxel, have been based on the observed upregulation of thymidine phosphorylase (TP) in preclinical studies. This taxane-mediated upregulation is synergistic, time dependent, and persists for up to 10 days. Studies of taxanes administered every 3 weeks with capecitabine have shown favorable antitumor responses and the combination of a taxane with capecitabine was favored over a taxane alone. The day-to-day administration of taxanes and capecitabine led to toxicity concerns, which have hindered their daily use. The administration of taxanes on a weekly schedule has demonstrated a more favorable toxicity profile (i.e., less myelosuppression), and initial studies in combination with capecitabine have demonstrated their utility in various solid tumors. Schedule optimization based on the upregulation of TP may result in a greater therapeutic index, thus allowing for the determination of the most advantageous way of combining these agents.

Combination chemotherapy of the taxanes and antimetabolites: its use and limitations

In an effort to improve response rates of chemotherapy, taxanes have been combined with other cytotoxic agents such as antimetabolites. However, the use of some of these combinations in patients has been restricted by severe toxicity. The significance of the sequence of drug administration in combining methotrexate (MTX) and taxanes was recognised in in vitro studies, showing synergistic effects for the sequence of MTX followed by paclitaxel, and antagonism for exposure in the reverse order. A possible explanation might be an MTX-induced synchronisation of cells in the S phase of the cell cycle, after which cells are more susceptible for the cytotoxic action of taxanes. Clinical studies using this sequence were hampered by severe neutropenia and mucositis at relatively low doses of both drugs. As no pharmacokinetic interactions were observed, the excess of toxicity may have been due to sequence-dependent synergistic actions on bone marrow and mucosa. In contrast, and confusingly, in vitro studies on 5-fluorouracil (5-FU) and taxanes indicate that 5-FU preceeding or simultaneously given to paclitaxel impairs cytotoxicity as compared with paclitaxel monotherapy, while the reverse sequence results in additive or synergistic cytotoxicity. While almost all clinical studies have used the sequence of a taxane followed by 5-FU, various schedules appeared feasible and effective. The combination of a 5-FU analogue, capecitabine and taxanes was supported by in vitro data. A large phase III trial confirmed the feasibility and superior efficacy of this combination in breast cancer patients relapsing after an anthracycline. Conflicting results exist on the benefit of combining gemcitabine and taxanes in tumour cell lines. Although the accumulation of gemcitabine triphosphate (dFdCTP) in mononuclear cells was significantly higher with an increasing dose of paclitaxel, no pharmacokinetic interactions for both agents were noticed. A pharmacokinetic analysis of the gemcitabine-docetaxel combination therapy has not been published in detail. Despite numerous trials, so far no optimum schedule has been established. Regarding data on actually delivered dose intensities, a 2- or 3-weekly cycle seems favourable and feasible. However, possible severe pulmonary toxicity warrants cautious monitoring of patients treated with this combination. Different outcomes of preclinical and clinical studies reveal that combining two chemotherapeutic agents is not simply a matter of putting antitumour activities together. Drug interaction may result in synergism, not only of efficacy but also of toxic side-effects. Adding two drugs may also implicate antagonism in drug efficacy due to unwanted interference in cytotoxicity or pharmacokinetics. For agents acting at a specific phase of the cell cycle, the sequence of administration may determine the efficacy and toxicity of a combination therapy. Because of an observed discrepancy between in vitro data and clinical studies, we would like to emphasise the need for adequate dose-finding clinical trials together with pharmacokinetic data analysis before examining any new combination chemotherapy in more detail in phase II studies.

Clinical pharmacokinetics of capecitabine

Capecitabine is a novel oral fluoropyrimidine carbamate that is preferentially converted to the cytotoxic moiety fluorouracil (5-fluorouracil; 5-FU) in target tumour tissue through a series of 3 metabolic steps. After oral administration of 1250 mg/m2, capecitabine is rapidly and extensively absorbed from the gastrointestinal tract [with a time to reach peak concentration (tmax) of 2 hours and peak plasma drug concentration (Cmax) of 3 to 4 mg/L] and has a relatively short elimination half-life (t(1/2)) [0.55 to 0.89 h]. Recovery of drug-related material in urine and faeces is nearly 100%. Plasma concentrations of the cytotoxic moiety fluorouracil are very low [with a Cmax of 0.22 to 0.31 mg/L and area under the concentration-time curve (AUC) of 0.461 to 0.698 mg x h/L]. The apparent t(1/2) of fluorouracil after capecitabine administration is similar to that of the parent compound. Comparison of fluorouracil concentrations in primary colorectal tumour and adjacent healthy tissues after capecitabine administration demonstrates that capecitabine is preferentially activated to fluorouracil in colorectal tumour, with the average concentration of fluorouracil being 3.2-fold higher than in adjacent healthy tissue (p = 0.002). This tissue concentration differential does not hold for liver metastasis, although concentrations of fluorouracil in liver metastases are sufficient for antitumour activity to occur. The tumour-preferential activation of capecitabine to fluorouracil is explained by tissue differences in the activity of cytidine deaminase and thymidine phosphorylase, key enzymes in the conversion process. As with other cytotoxic drugs, the interpatient variability of the pharmacokinetic parameters of capecitabine and its metabolites, 5'-deoxy-5-fluorocytidine and fluorouracil, is high (27 to 89%) and is likely to be primarily due to variability in the activity of the enzymes involved in capecitabine metabolism. Capecitabine and the fluorouracil precursors 5'-deoxy-5-fluorocytidine and 5'-deoxy-5-fluorouridine do not accumulate significantly in plasma after repeated administration. Plasma concentrations of fluorouracil increase by 10 to 60% during long term administration, but this time-dependency is assumed to be not clinically relevant. A potential drug interaction of capecitabine with warfarin has been observed. There is no evidence of pharmacokinetic interactions between capecitabine and leucovorin, docetaxel or paclitaxel.

Multicenter, Phase II study of capecitabine in taxane-pretreated metastatic breast carcinoma patients

BACKGROUND

Capecitabine is an oral, tumor-targeted fluoropyrimidine carbamate with high activity in metastatic breast carcinoma and in paclitaxel-pretreated metastatic breast carcinoma.

METHODS

The current multicenter, Phase II trial assessed the efficacy and safety of intermittent oral capecitabine, 1255 mg/m(2) twice daily (2 weeks of treatment followed by a 1-week rest period), in patients with metastatic breast carcinoma in whom prior taxane therapy had failed. All patients had failed treatment or had disease that was refractory to two or three previous chemotherapy regimens, one of which contained a taxane. Nearly all patients (96%) also had received prior anthracycline chemotherapy. Seventy-five patients were recruited at 5 centers, 74 of whom received treatment.

RESULTS

The overall response rate was 26%, with response rates of 27% and 20%, respectively, in the subgroups of patients previously pretreated with paclitaxel (n = 47) or docetaxel (n = 27). The median survival was 12.2 months, the median duration of response was 8.3 months, and the median time to disease progression was 3.2 months. The most common treatment-related adverse events (all grades) were hand-foot syndrome (62%), diarrhea (58%), nausea (55%), emesis (37%), and stomatitis (34%). However, the majority were mild to moderate in intensity and only three patients experienced Grade 4 (according to the National Cancer Institute of Canada Common Toxicity criteria) adverse events. The only Grade 3 treatment-related adverse events reported in > or = 10% of the patients were hand-foot syndrome (22%), diarrhea (16%), and stomatitis (12%). Myelosuppression and alopecia were rare, and there were no reported treatment-related deaths.

CONCLUSIONS

The results of the current study demonstrate that capecitabine is an effective and well tolerated treatment in patients with taxane-refractory or taxane-failing metastatic breast carcinoma. In addition, it is a convenient, orally administered drug, which makes it an attractive agent for use in outpatient treatment.

Capecitabine: a novel agent for the treatment of solid tumors

Although 5-fluorouracil (5-FU) has been used to treat breast and colorectal cancers for several decades, bolus 5-FU has disappointing efficacy. Prolonged infusion schedules and biomodulation with leucovorin have resulted in improved response rates, but these have not translated into significant improvements in survival in patients with metastatic disease. Furthermore, prolonged infusion is inconvenient for patients and can result in medical complications. New oral fluoropyrimidines, including capecitabine, are promising alternatives to i.v. 5-FU. Capecitabine generates 5-FU preferentially within tumors through exploitation of the high intratumoral activity of thymidine phosphorylase. The tumor selectivity of capecitabine has been confirmed in a clinical study of colorectal cancer patients. Clinical trials have shown that capecitabine is an effective, well-tolerated treatment for breast and colorectal cancer, with response rates of 20-26% in anthracycline- and taxane-pretreated metastatic breast cancer. As first-line monotherapy, capecitabine produces response rates of 25-27% in metastatic colorectal cancer and 30% in metastatic breast cancer. In all studies to date, capecitabine has been well tolerated, with adverse events typical of infusional 5-FU and manageable with treatment interruption/dose modification. Myelosuppression and alopecia are rare. Capecitabine is also being investigated in other solid tumors (including ovarian, pancreatic and gastric cancers) as adjuvant monotherapy in breast and colorectal cancer, and in combination with other cytotoxic agents. Results of ongoing trials are eagerly awaited.

New options for outpatient chemotherapy--the role of oral fluoropyrimidines

For several decades fluoropyrimidines, especially 5-fluorouracil (5-FU), have played a role in standard chemotherapy regimens for a range of solid tumours, including breast and colorectal cancers. In recent years, schedule modification and biomodulation have achieved improved efficacy and tolerability. However, the complications arising from infused intravenous administration are well-recognized and there is an unmet medical need for oral agents with improved efficacy and tolerability, offering more convenient outpatient therapy. Several oral fluoropyrimidines are in development, including capecitabine, UFT (uracil plus tegafur), S-1 and eniluracil. As yet, only UFT/leucovorin and capecitabine have been evaluated in randomized phase III clinical trials in metastatic colorectal cancer. Both have demonstrated safety benefits and equivalent survival compared with the Mayo Clinic regimen, and capecitabine has demonstrated a significantly superior response rate. Time to disease progression was equivalent to the Mayo Clinic regimen with capecitabine, but inferior with UFT/leucovorin. Capecitabine is also effective in patients with taxoid-pretreated metastatic breast cancer, a population which previously had no established treatment options. Both capecitabine and UFT/leucovorin are being evaluated in combination with irinotecan and oxaliplatin in colorectal cancer, and vinorelbine and docetaxel/paclitaxel in breast cancer. In the future, these more convenient, oral fluoropyrimidines may replace intravenous 5-FU in the treatment of breast and colorectal cancer.