Influence of the antacid Maalox on the pharmacokinetics of capecitabine in cancer patients

Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) methods for the therapeutic drug monitoring of cytotoxic anticancer drugs: An update

In the era of precision medicine, there is increasing evidence that conventional cytotoxic agents may be suitable candidates for therapeutic drug monitoring (TDM)- guided drug dosage adjustments and patient's tailored personalization of non-selective chemotherapies. To that end, many liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) assays have been developed for the quantification of conventional cytotoxic anticancer chemotherapies, that have been comprehensively and critically reviewed. The use of stable isotopically labelled internal standards (IS) of cytotoxic drugs was strikingly uncommon, accounting for only 48 % of the methods found, although their use could possible to suitably circumvent patients' samples matrix effects variability. Furthermore, this approach would increase the reliability of cytotoxic drug quantification in highly multi-mediated cancer patients with complex fluctuating pathophysiological and clinical conditions. LC-MS/MS assays can accommodate multiplexed analyses of cytotoxic drugs with optimal selectivity and specificity as well as short analytical times and, when using stable-isotopically labelled IS for quantification, provide concentrations measurements with a high degree of certainty. However, there are still organisational, pharmacological, and medical constraints to tackle before TDM of cytotoxic drugs can be more largely adopted in the clinics for contributing to our ever-lasting quest to improve cancer treatment outcomes.

Re-thinking the possible interaction between proton pump inhibitors and capecitabine

Proton Pump Inhibitors (PPI) rank within the top ten most prescribed medications in Europe and USA. A high frequency of PPI use has been reported amongst patients undergoing chemotherapy, to mitigate treatment-induced gastritis or gastro-oesophageal reflux. Several recent, mostly retrospective, observational studies have reported inferior survival outcomes among patients on capecitabine who concomitantly use PPI. Whilst this association is yet to be definitively established, given the prominence of capecitabine as an anti-cancer treatment with multiple indications, these reports have raised concern within the oncological community and drug regulatory bodies worldwide. Currently, the leading mechanism of interaction postulated in these reports has focussed on the pH altering effects of PPI and how this could diminish capecitabine absorption, leading to a decrease in its bioavailability. In this discourse, we endeavour to summarise plausible pharmacokinetic interactions between PPI and capecitabine. We provide a basis for our argument against the currently proposed mechanism of interaction. We also highlight the long-term effects of PPI on health outcomes, and how PPI use itself could lead to poorer outcomes, independent of capecitabine.

Association between the Co-administration of Histamine H2 Receptor Antagonists and the Effectiveness of Capecitabine in Patients with Colorectal Cancer: Propensity Score Analysis

Background: The association between the effectiveness of capecitabine and the concomitant administration of gastric acid suppressants remains controversial. We aimed to clarify whether the effectiveness of capecitabine is affected by the co-administration of histamine H₂ receptor antagonists (H₂RAs) in early-stage colorectal cancer (CRC) patients using real-world data. Methods: This multicenter, retrospective, observational study included consecutive patients with stage II-III CRC who received either capecitabine monotherapy or the CapeOX regimen (capecitabine and oxaliplatin) as adjuvant therapy between January 2009 and December 2014 in Japan. Relapse-free survival (RFS) and overall survival were estimated using the Kaplan-Meier method. Additionally, multivariable Cox proportional hazards model, propensity score adjustment, and inverse probability of treatment weighting analyses were performed. Results: In total, 552 patients were included in this study, of which 30 were co-administered H₂RAs. RFS at five years was 76.7% (95% confidence interval [CI]: 57.2-88.1%) and 79.8% (95% CI: 76.0-83.0%) in the H₂RA and non-H₂RA groups, respectively. Multivariable Cox proportional hazards model and propensity score-adjusted analyses showed that the co-administration of H₂RAs was associated with a poor RFS among those receiving capecitabine monotherapy (hazard ratio [HR], 2.01; 95% CI: 0.86-4.70 and HR, 1.81; 95% CI: 0.77-4.22, respectively). In contrast, these results were inconsistent with the group receiving the CapeOX regimen. Conclusions: The study findings suggest that the co-administration of H₂RAs may not reduce the effectiveness of capecitabine therapy in patients with early-stage CRC. To confirm this relationship, a prospective study with a pharmacokinetic approach is needed.

Proton pump inhibitors affect capecitabine efficacy in patients with stage II-III colorectal cancer: a multicenter retrospective study

The association between capecitabine efficacy and proton pump inhibitors (PPIs) is controversial. Here, we determined whether co-administration of PPIs affects the real-world effectiveness of capecitabine. This retrospective observational study included consecutive patients with stage II–III colorectal cancer (CRC) who received adjuvant capecitabine monotherapy or CapeOX (capecitabine and oxaliplatin) between January 2009 and December 2014 at nine participating institutions. The primary endpoint was the difference in relapse-free survival (RFS) between patients who received PPIs and those who did not and was estimated using the Kaplan–Meier method. Overall survival (OS) was the secondary endpoint. Multivariable analysis of RFS and OS was performed using a Cox proportional hazards model, propensity score adjustment, and inverse probability of treatment weighting (IPTW) analyses. Data from 606 patients were evaluated, 54 of whom had received a PPI. PPI-treated patients tended to have poorer RFS and OS than patients treated without PPIs. The hazard ratio for RFS with capecitabine monotherapy was 2.48 (95% confidence interval: 1.22–5.07). These results were consistent with sensitivity analyses performed using propensity score adjustment and IPTW methods. Co-administration of PPIs may reduce the effectiveness of capecitabine and negatively impact patients with stage II–III CRC.

Effect of the Proton Pump Inhibitor Esomeprazole on the Systemic Exposure of Capecitabine: Results of A Randomized Crossover Trial

Retrospective data suggest that gastric acid reduction by proton pump inhibitors (PPIs) impairs the dissolution and subsequent absorption of capecitabine, and thus potentially reduces the capecitabine exposure. Therefore, we examined prospectively the effect of esomeprazole on the pharmacokinetics of capecitabine. In this randomized crossover study, patients with cancer were assigned to 2 sequence groups, each consisting of 3 phases: capecitabine with esomeprazole administration 3 hours before (phase A), capecitabine alone (phase B), and capecitabine concomitant with cola and esomeprazole co-administration 3 hours before (phase C). The primary end point was the relative difference (RD) in exposure to capecitabine assessed by the area under the plasma concentration-time curve from zero to infinity (AUC_0-inf ) and analyzed by a linear mixed effect model. Twenty-two evaluable patients were included in the analysis. After esomeprazole, there was a 18.9% increase in AUC_0-inf of capecitabine (95% confidence interval (CI) -10.0% to 57.0%, P = 0.36). In addition, capecitabine half-life was significantly longer after esomeprazole (median 0.63 hours vs. 0.46 hours, P = 0.005). Concomitant cola did not completely reverse the effects observed after esomeprazole (RD 3.3% (95% CI -16.3 to 27.4%, P = 1.00). Capecitabine exposure is not negatively influenced by esomeprazole cotreatment. Therefore, altered capecitabine pharmacokinetics do not explain the assumed worse clinical outcome of PPI-cotreated patients with cancer.

Controversial link between proton pump inhibitors and anticancer agents: review of the literature

Drug-drug interactions represent a topic of great interest, not only due to the risk of unexpected adverse events but also due to the possibility of altering the effectiveness of a specific treatment. Inappropriate or concomitant use of drugs can often lead to changes in the bioavailability of various compounds, resulting in pharmacokinetic alterations. A recent example is the concomitant administration of proton pump inhibitors (PPIs) and anticancer agents. PPIs are overused beyond their classic indications, resulting in a high risk of interactions with other drugs, such as anticancer agents, both PO and intravenous. However, the real clinical impact of concomitant acid suppression therapy and anticancer therapies remains controversial and is not yet fully understood. Certainly, the gut microbiota plays a key role in regulating the response of the immune system, and PPIs can significantly alter the gut microbiome, resulting in gut dysbiosis. Indeed, while the link sometimes appears to lead to negative outcomes, as in the case of immunotherapy, oral capecitabine, or tyrosine kinase inhibitors, in other cases, it seems to enhance the effectiveness of intravenous chemotherapy. In this review, I analyse the possible drug interactions between PPIs and the main classes of anticancer drugs.

Proton Pump Inhibitor Use and the Efficacy of Chemotherapy in Metastatic Colorectal Cancer: A Post Hoc Analysis of a Randomized Phase III Trial (AXEPT)

BACKGROUND

Concomitant use of proton pump inhibitors (PPIs) with capecitabine was suggested to be associated with poor outcomes in gastrointestinal cancers. We analyzed the differential impact of PPI use on capecitabine and fluorouracil using the data set from the AXEPT trial, a phase III randomized trial that demonstrated the noninferiority of mXELIRI (modified XELIRI: capecitabine plus irinotecan) to FOLFIRI (leucovorin, fluorouracil, and irinotecan), either with or without bevacizumab in patients with metastatic colorectal cancer.

PATIENTS AND METHODS

Out of the per-protocol set (n = 620), patients with information on concomitant medications (n = 482) were included in this post hoc analysis. PPI use was defined as concomitant exposure of capecitabine and the use of any PPI for 20% or more of the study period. The treatment-by-PPI-use interaction was examined after adjusting for stratification factors.

RESULTS

Of the 482 patients, 49 (10.1%) used PPI. Among the PPI users, the mXELIRI group tended to have poorer overall survival compared with the FOLFIRI group. In contrast, among the nonusers, the overall survival of the mXELIRI group was significantly better than that of the FOLFIRI group. Similarly, a trend of worse progression-free survival with mXELIRI compared with FOLFIRI was observed in PPI users but not in nonusers. Treatment-by-PPI-use interaction was significant for overall survival and progression-free survival.

CONCLUSION

The significant interaction between PPI use and the type of fluoropyrimidine in terms of overall and progression-free survival suggests that fluorouracil could be a more favorable option than capecitabine for patients with metastatic colorectal cancer using PPIs.

IMPLICATIONS FOR PRACTICE

This study showed a significant interaction between the use of proton pump inhibitors (PPIs) and the type of fluoropyrimidines. This interaction mainly comes from the positive impact of PPIs in the survival outcomes in the fluorouracil arm rather than a negative impact of PPIs in the capecitabine arm. The possible drug-drug interaction shown in this study suggests that fluorouracil, rather than capecitabine, could be a more appropriate choice of fluoropyrimidine for patients who are taking PPIs in the treatment of metastatic colorectal cancer.

Proton Pump Inhibitors and Oncologic Treatment Efficacy: A Practical Review of the Literature for Oncologists

Proton pump inhibitors (PPIs) are the most commonly used anti-acid drugs worldwide, including among cancer patients. However, drug-drug interactions between PPIs and other agents may lead to decreased drug absorption with possible reduced therapeutic benefit, or even increased toxicity. Unfortunately, only scarce data exist regarding the safety of concomitant PPI use with anti-cancer agents. We aim at reviewing current evidence on this possible interaction by dividing anti-cancer agents by class. Until further data is available, we encourage healthcare providers to limit unnecessary PPI overuse.

Population pharmacokinetic and pharmacodynamic modeling of capecitabine and its metabolites in breast cancer patients

PURPOSE

The present study was performed to examine relationships between systemic exposure of capecitabine metabolites (5-FU, 5'-DFCR and 5'-DFUR) and toxicity or clinical response in patients with metastatic breast cancer.

METHODS

A population pharmacokinetic model for capecitabine and its three metabolites was built. Typical parameter values, characteristics of random distributions, associated with parameters, and covariates impact were estimated. Area under the curve (AUC) were computed for 5-FU and compared with grades of toxicity. Pharmacokinetic modeling was based on data collected on the first treatment cycle. Toxicity was assessed on the two first treatment cycles.

RESULTS

The study was conducted in 43 patients. The population pharmacokinetic model (a one-compartment model per compound) was able to capture the very complex absorption process of capecitabine. Statistically significant covariates were cytidine deaminase, alkaline phosphatase and dihydrouracilemia (UH2)/uracilemia (U) ratio. UH2/U ratio was the most significant covariate on 5-FU elimination and CDA on the transformation of 5'-DFCR in 5'-DFUR. A trend was observed between 5-FU AUC and thrombopenia toxicity grades, but not with other toxicities. Best clinical response was not linked to systemic exposure of capecitabine metabolites.

CONCLUSION

In our study, we propose a model able to describe, meanwhile, and its main metabolites, with a complex absorption process and inclusion of enzyme activity covariates such as CDA and UH2/U ratio. Trial registration Eudract 2008-004136-20, 2008/11/26.

Efficacy of capecitabine when used concomitantly with proton pump inhibitors in cancer patients: a systematic review

BACKGROUND

Capectiabine is an oral antineoplastic drug used in multiple malignancies. Proton pump inhibitors (PPI) have been proven to interact with other oral antineoplastic agents. In this systematic review we will summarize the clinical evidence on the efficacy of capecitabine when used concomitantly with PPI.

MATERIALS AND METHODS

We performed a systematic literature search on the main databases up to November 2019.

RESULTS

Nine studies met our inclusion criteria: 8 retrospective studies and 1 phase II clinical trial. Patients with colorectal, breast and gastroesophageal were represented. Four out of the 9 studies reported a shorter efficacy outcome in uni- or multivariate analysis when capecitabine was taken concomitantly with PPI than alone.

CONCLUSIONS

Up to date, the clinical evidence reported on the use of capecitabine concomitantly with PPI is scarce and shows conflicting results. While awaiting further data, avoiding misuse of PPI in cancer patients taking capecitabine is recommended.

Oral Anticancer Therapy: Management of Drug Interactions

Oral anticancer therapy is increasingly integrated into the care of patients with cancer. Recognition and management of drug-drug interactions (DDIs) is critical to providing efficacious and safe anticancer treatment. DDIs with QTc-prolonging agents, anticoagulants, enzyme inducers and inhibitors, antidepressants, and acid suppressants are commonly encountered with anticancer therapies. Here, we review frequently observed DDIs and outline literature-supported suggestions for their management.

Concomitant use of capecitabine and proton pump inhibitors – Is it safe?

Background

Capecitabine is a commonly used oral chemotherapy agent. Recent data suggest that concurrent use of proton pump inhibitors may reduce the efficacy of capecitabine by decreasing its absorption through increased gastric pH. Since proton pump inhibitors are widely used, we evaluated the supportive evidence for the probability of occurrence and potential seriousness of this drug interaction.

Methods

The probability of occurrence was evaluated based on the clinical, pharmacokinetic and in vitro evidence using the Drug Interaction Probability Scale. The possibility of seriousness was assessed based on the potential impact on the therapeutic intent of capecitabine therapy.

Results

The probability of occurrence of the interaction is doubtful. Clinical findings from two retrospective post hoc analyses showed inconsistent trends towards reduced survival. Pharmacokinetics studies found no significant decrease in systemic capecitabine level with concurrent gastric acid suppression with antacid or food intake. In vitro data do not support the proposed mechanism of reduced capecitabine absorption due to increased gastric pH. The possibility of seriousness varies depending on the treatment intent of capecitabine therapy. The most and least serious possible outcome would be reduced possibility of cure or survival and symptom control, respectively.

Conclusion

Although the possible outcome may be serious, the probability of interaction between capecitabine and proton pump inhibitors is doubtful. Therefore, we suggest that intervention should be limited to minimal change to existing therapy plan. This may include routinely ascertaining the need for proton pump inhibitor use. Alternate acid suppressing agents may be considered based on the therapeutic intent of capecitabine therapy.

Capecitabine for the treatment of pancreatic cancer

INTRODUCTION

Capecitabine is an oral prodrug of 5-fluorouracil (5-FU) which is converted to 5FU by a series of reactions catalyzed by different enzymes, the last of the enzymes being thymidine phosphorylase (TP). TP is found to be elevated in tumor cells in comparison to normal cells, which consequently tumor-localizes the production of 5-FU, thereby limiting its systemic toxicity. Today, capecitabine is extensively used for the treatment of many solid malignancies, with a particular focus in breast and gastrointestinal tumors, but also in pancreatic cancer. Areas covered: This review summarizes the pharmacology and the clinical evidence relevant to the use of capecitabine in the treatment of pancreas cancer. The authors provide, furthermore, provide their expert perspectives on its use. Expert opinion: Capecitabine has the advantage over other therapeutics in so much that it has both convenient oral administration and a favorable toxicity profile. Current data has promised the use of capecitabine in all stages of pancreatic cancer. However, predictive markers for outcome and toxicity remain to be validated.

Evaluation of the clinical impact of concomitant acid suppression therapy in colorectal cancer patients treated with capecitabine monotherapy

Background

Capecitabine is an oral chemotherapeutic agent used in colorectal cancer. Two prior studies found a negative impact with the concomitant use of proton pump inhibitor agents during treatment with capecitabine in patients with early colorectal and gastroesophageal cancers.

Objective

To determine if there is a clinical impact of the concomitant use of capecitabine and acid suppression therapy in patients with local and metastatic colorectal cancer.

Methods

This was a single-center retrospective cohort study of adult patients with colorectal cancer on capecitabine monotherapy between 2011 and 2017. Progression-free survival (PFS) and overall survival were compared between patients on acid suppression therapy and those not on acid suppression therapy.

Results

A total of 70 patients were included. Patients on acid suppression therapy at capecitabine initiation (21%) had decreased progression-free survival versus those not on acid suppression therapy (HR 2.24, 95% CI 1.06–4.41, p = 0.035), after adjusting for disease severity and age. Acid suppression therapy use was associated with a numerical decrease in overall survival (HR 1.86, 95% CI 0.81–3.91, p = 0.14). In patients on any concomitant acid suppression therapy (25%), there was a decreased rate of progression-free survival (HR 6.21, 95% CI 2.56–14.32, p = 0.0001) but not overall survival (HR 1.64, 95% CI 0.68–3.54, p = 0.25) versus those without concomitant acid suppression therapy, after adjusting for age and disease severity.

Conclusions

Concurrent use of acid suppression therapy and capecitabine was associated with decreased progression-free survival, and there was a trend towards decreased overall survival. Due to the demonstrated potential of decreased efficacy, concurrent use of proton pump inhibitors or histamine 2 receptor antagonists should be avoided in colorectal cancer patients on treatment with capecitabine monotherapy.

Effects of Proton Pump Inhibitors on FOLFOX and CapeOx Regimens in Colorectal Cancer

BACKGROUND

First-line adjuvant chemotherapy options for early-stage colorectal cancer (CRC) include CapeOx (capecitabine, intravenous oxaliplatin) and FOLFOX (intravenous 5-fluorouracil, leucovorin, oxaliplatin). Capecitabine is an oral prodrug analog of 5-fluorouracil, and recent studies have suggested that proton pump inhibitors (PPIs) may detrimentally affect capecitabine efficacy. Conversely, some literature suggests that PPIs may negatively affect CRC itself. To gain insight into the nature of PPIs' effect on capecitabine and CRC, we investigated their effects on effectiveness of CapeOx versus FOLFOX chemotherapy.

PATIENTS AND METHODS

We conducted a retrospective chart review of 389 patients with stage II-III CRC who received adjuvant CapeOx or FOLFOX from 2004 to 2013. Information regarding PPI receipt, chemotherapy, and patient outcomes from medical records was analyzed.

RESULTS

Three-year recurrence-free survival was significantly lower in CapeOx-treated PPI recipients than non-PPI recipients (69.5 vs. 82.6%; P = .029). Unadjusted analysis showed that CapeOx-treated PPI recipients were twice as likely to experience cancer recurrence or death as CapeOx-treated non-PPI recipients (hazard ratio = 2.03; 95% confidence interval, 1.06-3.88; P = .033). FOLFOX-treated PPI recipients had a non-statistically significant difference in 3-year recurrence-free survival versus non-PPI recipients (82.9 vs. 61.7%; P = .066) and a non-statistically significant difference in recurrence/death (hazard ratio = 0.51; 95% confidence interval, 0.25-1.06; P = .071). No significant differences were seen in overall survival between groups.

CONCLUSION

Our results suggest PPIs negatively affected recurrence-free survival in CapeOx-treated CRC patients and yielded no significant effects among FOLFOX-treated patients, potentially implicating a pharmacokinetic interaction between PPIs and capecitabine. No overall survival effects were seen. Given PPIs' widespread use, further studies are required to corroborate our findings.

A multi-throughput multi-organ-on-a-chip system on a plate formatted pneumatic pressure-driven medium circulation platform

This paper reports a multi-throughput multi-organ-on-a-chip system formed on a pneumatic pressure-driven medium circulation platform with a microplate-sized format as a novel type of microphysiological system. The pneumatic pressure-driven platform enabled parallelized multi-organ experiments (i.e. simultaneous operation of multiple multi-organ culture units) and pipette-friendly liquid handling for various conventional cell culture experiments, including cell seeding, medium change, live/dead staining, cell growth analysis, gene expression analysis of collected cells, and liquid chromatography-mass spectrometry analysis of chemical compounds in the culture medium. An eight-throughput two-organ system and a four-throughput four-organ system were constructed on a common platform, with different microfluidic plates. The two-organ system, composed of liver and cancer models, was used to demonstrate the effect of an anticancer prodrug, capecitabine (CAP), whose metabolite 5-fluorouracil (5-FU) after metabolism by HepaRG hepatic cells inhibited the proliferation of HCT-116 cancer cells. The four-organ system, composed of intestine, liver, cancer, and connective tissue models, was used to demonstrate evaluation of the effects of 5-FU and two prodrugs of 5-FU (CAP and tegafur) on multiple organ models, including cancer and connective tissue.

Association of Proton Pump Inhibitors and Capecitabine Efficacy in Advanced Gastroesophageal Cancer: Secondary Analysis of the TRIO-013/LOGiC Randomized Clinical Trial

Importance

Capecitabine is an oral cytotoxic chemotherapeutic commonly used across cancer subtypes. As with other oral medications though, it may suffer from drug interactions that could impair its absorption.

Objective

To determine if gastric acid suppressants such as proton pump inhibitors (PPIs) may impair capecitabine efficacy.

Design, Setting, and Participants

This secondary analysis of TRIO-013, a phase III randomized trial, compares capecitabine and oxaliplatin (CapeOx) with or without lapatinib in 545 patients with ERBB2/HER2-positive metastatic gastroesophageal cancer (GEC); patients were randomized 1:1 between CapeOx with or without lapatinib. Proton pump inhibitor use was identified by medication records. Progression-free survival (PFS) and overall survival (OS) were compared between patients treated with PPIs vs patients who were not. Specific subgroups were accounted for, such as younger age (<60 years), Asian ethnicity, female sex, and disease stage (metastatic/advanced) in multivariate Cox proportional hazards modeling. The TRIO-013 trial accrued and randomized patients between June 2008 and January 2012; this analysis took place in January 2014.

Interventions

Patients were divided based on PPI exposure.

Main Outcomes and Measures

Primary study outcome was PFS and OS between patients treated with PPIs vs patients who were not. Secondary outcomes included disease response rates and toxicities.

Results

Of the 545 patients with GEC (median age, 60 years; 406 men [74%]) included in the study, 229 received PPIs (42.0%) and were evenly distributed between arms. In the placebo arm, PPI-treated patients had poorer median PFS, 4.2 vs 5.7 months (hazard ratio [HR], 1.55; 95% CI, 1.29-1.81, P < .001); OS, 9.2 vs 11.3 months (HR, 1.34; 95% CI, 1.06-1.62; P = .04); and disease control rate (83% vs 72%; P = .02) vs patients not treated with PPIs. In multivariate analysis considering age, race, disease stage, and sex, PPI-treated patients had poorer PFS (HR, 1.68; 95% CI, 1.42-1.94; P < .001) and OS (HR, 1.41; 95% CI, 1.11-1.71; P = .001). In patients treated with CapeOx and lapatinib, PPIs had less effect on PFS (HR, 1.08; P = .54) and OS (HR, 1.26; P = .10); however, multivariate analysis in this group demonstrated a significant difference in OS (HR, 1.38; 95% CI, 1.06-1.66; P = .03).

Conclusions and Relevance

Proton pump inhibitors negatively effected capecitabine efficacy by possibly raising gastric pH levels, leading to altered dissolution and absorption. These results are consistent with previous erlotinib and sunitinib studies. Whether PPIs affected lapatinib is unclear given concurrent capecitabine. Given capecitabine's prevalence in treatment breast cancer and colon cancer, further studies are under way.

Trial Registration

clinicaltrials.gov Identifier: NCT00680901.

Capecitabine: a novel, orally administered, tumour-activated treatment for breast 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 metastatic breast 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 was excluded on grounds of quality.

Data Summary. 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. The 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 including breast cancers, resulting in preferential delivery of 5-FU to tumour tissues, and suggesting a greater potential for selective cytotoxicity than is seen with 5-FU.

Capecitabine has been examined both alone and in combination with a variety of cytotoxic drugs in the treatment of metastatic breast cancer. To date, clinical evidence supports the use of capecitabine monotherapy in patients relapsing after prior treatment with anthracyclines and taxanes and in combination with docetaxel in patients failing anthracycline treatment.

Data from phase II studies indicate that in the first of these situations, capecitabine elicits a response in about one-fifth of patients and that responses are associated with symptomatic relief and extended survival. In the latter situation, a phase III study has shown that the combination of docetaxel and capecitabine elicits superior response rates, remission durations, and overall survival compared with the taxane alone and with no clinically important increase in toxicity.

Used alone or in combination, the most notable adverse effect associated with capecitabine is palmar-plantar erythrodysasthesia (hand -foot syndrome), a characteristic complex of reddening, dryness, and soreness of the palms of the hands and soles of the feet, which is rarely disabling and readily managed by treatment interruption and dose reduction.

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.

Concomitant Administration of Proton Pump Inhibitors and Capecitabine is Associated With Increased Recurrence Risk in Early Stage Colorectal Cancer Patients

BACKGROUND

Capecitabine is used to treat colorectal (CRC) cancer. TRIO-013, a study examining capecitabine/oxaliplatin ± lapatinib in metastatic gastro-esophageal cancer did not show increases in overall survival (OS) with lapatinib. An analysis showed concurrent proton pump inhibitor (PPI) usage negatively impacted recurrence-free survival (RFS). We retrospectively studied PPI effects on capecitabine efficacy in early stage CRC and how capecitabine adjustments impacted RFS.

METHODS

Early stage CRC patients taking monotherapy capecitabine treated from 2008 to 2012 were reviewed for demographics, medications, toxicities, and patient outcomes.

RESULTS

Of 298 identified patients, 25.8% (n = 77) received concurrent PPIs. Five-year RFS was 74% versus 83% (hazard ratio [HR], 1.89; 95% confidence interval [CI], 1.07-3.35; P = .03) in PPI versus non-PPI patients respectively. OS was 81% versus 78%, respectively (HR, 1.13; 95% CI, 0.60-2.14; P = .7). After accounting for gender, stage, age, and performance status, PPI patients tended toward decreased RFS (HR, 1.65; 95% CI, 0.93-2.94; P = .09). Capecitabine dose modifications affected outcomes. Five-year RFS was 84% in the control group, 100% in the treatment-delay group (P = .99), 67% in the dose reduction group (HR, 2.46; 95% CI, 1.23-4.93; P = .01), and 64% in the discontinuation group (HR, 2.27; 95% CI, 0.93-5.53; P = .07). Five-year OS was significantly less in the discontinuation group than control group (59% vs. 82%; HR, 3.27; 95% CI, 1.44-7.45; P = .005).

CONCLUSIONS

PPIs appear to impact RFS; this may be due to PPIs preventing capecitabine tablet dissolution and absorption. Patients with dose reductions or who stopped treatment had worse outcomes than patients who continued with treatment at starting doses.

Simultaneous determination of capecitabine and its three nucleoside metabolites in human plasma by high performance liquid chromatography-tandem mass spectrometry

Capecitabine (Cape) is a prodrug that is metabolized into 5'-deoxy-5-fluorocytidine (DFCR), 5'-deoxy-5-fluorouridine (DFUR), and 5-fluorouracil (5-FU) after oral administration. A liquid chromatography-tandem mass spectrometry method for the simultaneous determination of capecitabine and its three metabolites in human plasma was developed and validated. The ex vivo conversion of DFCR to DFUR in human blood was investigated and an appropriate blood sample handling condition was recommended. Capecitabine and its metabolites were extracted from 100 μL of plasma by protein precipitation. Adequate chromatographic retention and efficient separation were achieved on an Atlantis dC18 column under gradient elution. Interferences from endogenous matrix and the naturally occurring heavy isotopic species were avoided. Detection was performed in electrospray ionization mode using a polarity-switching strategy. The method was linear in the range of 10.0-5000 ng/mL for Cape, DFCR, and DFUR, and 2.00-200 ng/mL for 5-FU. The LLOQ was established at 10.0 ng/mL for Cape, DFCR, and DFUR, and 2.00 ng/mL for 5-FU. The inter- and intra-day precisions were less than 13.5%, 11.1%, 9.7%, and 11.4%, and the accuracy was in the range of -13.2% to 1.6%, -2.4% to 2.5%, -7.1% to 8.2%, and -2.0% to 3.8% for Cape, DFCR, DFUR, and 5-FU, respectively. The matrix effect was negligible under the current conditions. The mean extraction recoveries were within 105-115%, 92.6-101%, 94.0-100%, and 85.1-99.9% for Cape, DFCR, DFUR, and 5-FU, respectively. Stability testing showed that the four analytes remained stable under all relevant analytical conditions. This method has been applied to a clinical bioequivalence study.

Higher capecitabine AUC in elderly patients with advanced colorectal cancer (SWOGS0030)

Background:

The aging process is accompanied by physiological changes including reduced glomerular filtration and hepatic function, as well as changes in gastric secretions. To investigate what effect would aging have on the disposition of capecitabine and its metabolites, the pharmacokinetics between patients ⩾70 years and <60 years were compared in SWOG0030.

Methods:

Twenty-nine unresectable colorectal cancer patients were stratified to either ⩾70 or <60 years of age, where the disposition of capecitabine and its metabolites were compared.

Results:

Notable increase in capecitabine area under the curve (AUC) was accompanied by reduction in capecitabine clearance in ⩾70 years patients (P<0.05). No difference in 5'-deoxy-5-fluorocytidine, 5'-deoxy-5-fluorouridine (DFUR), and 5-fluorouracil (5FU) AUCs between the two age groups, suggesting that carboxylesterase and cytidine deaminase (CDA) activity was similar between the two age groups. These results suggest that metabolic enzymes involved in converting capecitabine metabolites are not altered by age. An elevation in capecitabine Cmax and reduction in clearance was seen in females, where capecitabine AUC was 40.3% higher in women. Elevation of DFUR Cmax (45%) and AUC (46%) (P<0.05) was also noted, suggesting that CDA activity may be higher in females.

Conclusion:

Increases in capecitabine Cmax and AUC was observed in patients ⩾70 years when compared with younger patients who were >60 years.

Predicting concentrations of the cytostatic drugs cyclophosphamide, carboplatin, 5-fluorouracil, and capecitabine throughout the sewage effluents and surface waters of Europe

The present study evaluated the potential environmental concentrations of 4 cytostatic (also known as cytotoxic) drugs in rivers. The antimetabolite 5-fluorouracil (5FU) and its pro-drug capecitabine were examined based on their very high use rates, cyclophosphamide (CP) for its persistence, and carboplatin for its association with the metal element platinum. The study combined drug consumption information across European countries, excretion, national water use, and sewage removal rates to derive sewage effluent values across the continent. Results showed considerable variation in the popularity of individual cytostatic drugs across Europe, including a 28-fold difference in 5FU use and 15-fold difference in CP use. Such variations could have a major effect on the detection of these compounds in effluent or river water. Overall, capecitabine and CP had higher predicted levels in effluent than 5FU or carboplatin. Predicted effluent values were compared with measurements in the literature, and many non-detects could be explained by insufficient limits of detection. Linking the geographic based water resources model GWAVA with this information allowed water concentrations throughout 1.2 million km of European rivers to be predicted. The 90th percentile (worst case) prediction indicated that, with the exception of capecitabine, more than 99% of Europe's rivers (by length) would have concentrations below 1 ng/L for these cytostatic drugs. For capecitabine, 2.2% of river length could exceed 1 ng/L.

Quantitative determination of capecitabine and its six metabolites in human plasma using liquid chromatography coupled to electrospray tandem mass spectrometry

Capecitabine is the oral prodrug of the anticancer drug 5-fluorouracil (5-FU). The purpose of this study was to quantify capecitabine and its metabolites including 5'-deoxy-5-fluorocytidine (5'-dFCR), 5'-deoxy-5-fluorouridine (5'-dFUR), 5-FU, dihydro-5-fluorouracil (FUH(2)), α-fluoro-ureidopropionic acid (FUPA) and fluoro-β-alanine (FBAL) in human plasma using liquid chromatography coupled to electrospray tandem mass spectrometry. To this end two individual assays were developed: one for the simultaneous quantification of capecitabine, 5'-dFCR and 5'-dFUR using reversed phase chromatography and gradient elution, and one assay for 5-FU, FUH(2), FUPA and FBAL using hydrophilic interaction chromatography and isocratic elution. Both assays were fully validated according to current FDA guidelines. Total run time for the capecitabine assay was 9.0min, and of the 5-FU assay 5.0min. Analyte extraction was performed by protein precipitation. Stable labeled isotopes for each of the analytes were used as internal standards. The linear ranges of the analytes were 50-6000ng/mL for the capecitabine assay and 50-5000ng/mL for the 5-FU assay. Validation results demonstrate that capecitabine and its metabolites can be rapidly, accurately, precisely and robustly quantified in human plasma with the presented methods. Both assays are currently in extensive use in support of pharmacokinetic studies in patients treated with capecitabine or 5-FU.

The use of capecitabine in daily practice: a study on adherence and patients' experiences

BACKGROUND

Adherence to pharmacological therapy is a complex and multifactorial issue that can substantially alter the outcome of treatment. Especially when using long-term medication, cancer patients have adherence rates similar to those of patients with other diseases. The consequences of poor adherence are poor health outcomes and increased health care costs. Only few studies have focused on the use of oral anticancer agents in daily practice. Information about the reasons for nonadherence is essential for the development of interventions that may improve adherence. This report presents the CAPER-capecitabine protocol, which is designed to study the adherence to capecitabine and the influence of patient attitudes towards medication and self-reported side effects. Furthermore, the relationships between patient characteristics, disease characteristics, side effects, quality of life, patient beliefs and attitudes towards disease and medication, dose adjustments, reasons for discontinuation, and plasma concentration of three of the main metabolites, including the active compound 5-fluorouracil, will be explored.

METHODS

In this multicenter, prospective, observational cohort study, 90 patients aged 18 years or older starting treatment with capecitabine will be included and followed for a period up to five cycles. The main study parameters are adherence, patient attitudes towards medication, and the number and grade of patient-reported side effects. At baseline and during week 2 of cycles 1, 3 and 5, patients will be asked to donate blood and fill out a questionnaire. Blood samples will be analyzed for plasma concentration of the metabolites, 5'-deoxy-5-fluorouridine, 5-fluorouracil, and α-fluoro-β-alanine. The CAPER-capecitabine trial is closely related to the CAPER-erlotinib trial.

DISCUSSION

The aim of the present study is to get more insight into patient experiences with the use of capecitabine in daily practice and the various aspects that govern adherence. We hypothesize that patient attitudes towards medication and the side effects experienced play an important role in the way patients use capecitabine. We expect that our findings will be useful for health care professionals in developing interventions to support patients in improving adherence and persistence with the use of capecitabine.

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.

A new, validated HPLC-MS/MS method for the simultaneous determination of the anti-cancer agent capecitabine and its metabolites: 5'-deoxy-5-fluorocytidine, 5'-deoxy-5-fluorouridine, 5-fluorouracil and 5-fluorodihydrouracil, in human plasma

A rapid and selective liquid chromatography/tandem mass spectrometric method was developed for the simultaneous determination of capecitabine and its metabolites 5'-deoxy-5-fluorocytidine (5'-DFCR), 5'-deoxy-5-fluorouracil (5'-DFUR), 5-fluorouracil (5-FU) and dihydro-5-fluorouracil (FUH(2)) in human plasma. A 200 microL human plasma aliquot was spiked with a mixture of internal standards fludarabine and 5-chlorouracil. A single-step protein precipitation method was employed using 10% (v/v) trichloroacetic acid in water to separate analytes from bio-matrices. Volumes of 20 microL of the supernatant were directly injected onto the HPLC system. Separation was achieved on a 30 x 2.1 mm Hypercarb (porous graphitic carbon) column using a gradient by mixing 10 mm ammonium acetate and acetonitrile-2-propanol-tetrahydrofuran (1 : 3 : 2.25, v/v/v). The detection was performed using a Finnigan TSQ Quantum Ultra equipped with the electrospray ion source operated in positive and negative mode. The assay quantifies a range from 10 to 1000 ng/mL for capecitabine, from 10 to 5000 ng/mL for 5'-DFCR and 5'-DFUR, and from 50 to 5000 ng/mL for 5-FU and FUH(2) using a plasma sample of 200 microL. Correlation coefficients (r(2)) of the calibration curves in human plasma were better than 0.99 for all compounds. At all concentration levels, deviations of measured concentrations from nominal concentration were between -4.41 and 3.65% with CV values less than 12.0% for capecitabine, between -7.00 and 6.59% with CV values less than 13.0 for 5'-DFUR, between -3.25 and 4.11% with CV values less than 9.34% for 5'-DFCR, between -5.54 and 5.91% with CV values less than 9.69% for 5-FU and between -4.26 and 6.86% with CV values less than 14.9% for FUH(2). The described method was successfully applied for the evaluation of the pharmacokinetic profile of capecitabine and its metabolites in plasma of treated cancer patients.

Targeting cancers in the gastrointestinal tract: role of capecitabine

Capecitabine is currently the only novel, orally home-administered fluorouracil prodrug. It offers patients more freedom from hospital visits and less inconvenience and complications associated with infusion devices. The drug has been extensively studied in large clinical trials in many solid tumors, including breast cancer, colorectal cancer, gastric cancer, and many others. Furthermore, the drug compares favorably with fluorouracil in patients with such cancers, with a safe toxicity profile, consisting mainly of gastrointestinal and dermatologic adverse effects. Whereas gastrointestinal events and hand-foot syndrome occur often with capecitabine, the tolerability profile is comparatively favorable. Prompt recognition of severe adverse effects is the key to successful management of capecitabine. Ongoing and future clinical trials will continue to examine, and likely expand, the role of capecitabine as a single agent and/or in combination with other anticancer agents for the treatment of gastrointestinal as well as other solid tumors, both in the advanced palliative and adjuvant settings. The author summarizes the current data on the role of capecitabine in the management of gastrointestinal cancers.

Phase I clinical and pharmacokinetic study of oxaliplatin, irinotecan and capecitabine

PURPOSE

To determine the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) of the combination of weekly oxaliplatin x 4, weekly irinotecan x 4 and capecitabine Monday through Friday for 4 weeks of every 6 week cycle in patients with solid tumors; to determine the pharmacokinetic profile of these agents in this combination; to observe patients for clinical anti-tumor response.

METHODS

Twenty-two patients with metastatic solid tumors received oxaliplatin 60 mg/m(2) weekly x 4, irinotecan beginning at a dose of 40 mg/m(2) weekly x 4, and capecitabine Monday through Friday for 4 weeks of every 6 week cycle, initially at 1,000 mg twice daily (bid).

RESULTS

The MTD was oxaliplatin 60 mg/m(2) weekly x 4, irinotecan 50 mg/m(2) weekly x 4 and capecitabine 450 mg bid Monday through Friday for 4 weeks of every 6 week cycle. One of six patients at this dose level developed DLT of nausea, vomiting, and diarrhea. Among patients treated with a constant capecitabine dose of 450 mg bid, there was a higher mean AUC of 5-FU in women than in men (mean +/- SD: 892 +/- 287 nM h vs. 537 +/- 182 nM h; Mann-Whitney two-tailed, P = 0.02). There was one complete response in a patient with gastric cancer.

CONCLUSION

The novel schedule of weekly oxaliplatin, weekly irinotecan, and capecitabine Monday through Friday, all administered for 4 weeks of every 6 week cycle, evaluated in this phase I trial is well-tolerated and demonstrated activity in a patient with gastric cancer.

A dose-escalation study of indisulam in combination with capecitabine (Xeloda) in patients with solid tumours

This dose escalation study was designed to determine the recommended dose of the multi-targeted cell cycle inhibitor indisulam in combination with capecitabine in patients with solid tumours and to evaluate the pharmacokinetics of the combination. Thirty-five patients were treated with indisulam on day 1 of each 21-day cycle. Capecitabine was administered two times daily (BID) on days 1–14. Plasma concentrations of indisulam, capecitabine and its three metabolites were determined for pharmacokinetic analysis. The main dose-limiting toxicity was myelosuppression. Hand/foot syndrome and stomatitis were the major non-haematological toxicities. The recommended dose was initially established at indisulam 700 mg m⁻² and capecitabine 1250 mg m⁻² BID. However, during cycle 2 the recommended dose was poorly tolerated in three patients. A dose of indisulam 500 mg m⁻² and capecitabine 1250 mg m⁻² BID proved to be safe at cycle 1 and 2 in nine additional patients. Indisulam pharmacokinetics during cycle 1 were consistent with pharmacokinetic data from phase I mono-therapy studies. However, exposure to indisulam was remarkably increased at cycle 2 due to a drug–drug interaction between capecitabine and indisulam. Partial response was confirmed in two patients, one with colon carcinoma and the other with pancreatic carcinoma. Seventeen patients had stable disease. Indisulam (700 mg m⁻²) in combination with capecitabine (1250 mg m⁻² BID) was well tolerated during the first cycle. A dose of indisulam 500 mg m⁻² and capecitabine 1250 mg m⁻² BID was considered safe in multiple treatment cycles. The higher incidence of toxicities observed during cycle 2 can be explained by a time-dependent pharmacokinetic drug–drug interaction.

Quality assessment of fluoxetine and fluvoxamine pharmaceutical formulations purchased in different countries or via the Internet by 19F and 2D DOSY 1H NMR

A simple and selective (19)F NMR method has been validated for the quantitation of fluoxetine (FLX) and fluvoxamine (FLV) in methanol solutions and in human plasma and urine. The regression equations for FLX and FLV showed a good linearity in the range of 1.4-620 microg mL(-1) (3.3 x 10(-6)-1.8 x 10(-3) mol L(-1)) with a limit of detection of approximately 0.5 microg mL(-1) (1.3 x 10(-6) mol L(-1)) and a limit of quantification of approximately 2 microg mL(-1) (4.6 x 10(-6) mol L(-1)). The precision of the assay depends on the concentrations and is comprised between 1.5 and 9.5% for a range of concentrations between 1.2 x 10(-3) and 3.2 x 10(-6) mol L(-1). The accuracy evaluated through recovery studies ranged from approximately 96 to 103% in methanol solutions and in urine, and from approximately 93 to 104% in plasma, with standard deviations <7.5%. The low sensitivity of the method precludes its use for the assay of these antidepressants in biofluids at least at therapeutic doses as the ranges of FLX and FLV plasma levels are 0.15-0.5 microg mL(-1) and 0.15-0.25 microg mL(-1), respectively. The method was applied successfully to the determination of FLX and FLV contents in pharmaceutical samples (brand-named and generic) purchased in several countries or via the Internet. All the commercial formulations contain the active ingredient in the range 94-103% of stated concentration. A "signature" of the formulations (solid and liquid) was obtained with 2D Diffusion-Ordered SpectroscopY (DOSY) (1)H NMR which allowed the characterisation of the active ingredient and excipients present in the formulations studied. Finally, the DOSY separation of FLX and FLV whose molecular weights are very close was obtained by using beta-cyclodextrin as host-guest complexing agent.

Rapid and simultaneous determination of capecitabine and its metabolites in mouse plasma, mouse serum, and in rabbit bile by high-performance liquid chromatography

A rapid high-performance liquid chromatography method has been developed for simultaneous determination of capecitabine and its metabolites: 5'-deoxy-5-fluorocytidine (5'-DFCR), 5'-deoxy-5-fluorouridine (5'-DFUR) and 5-fluorouracil (5-FU). 5'-DFCR was synthesized by hydrolyzing capecitabine using commercially available carboxyl esterase (CES) and characterized by NMR, mass spectrometry and elemental analysis. Base-line separations between capecitabine, 5'-DFCR, 5'-DFUR and 5-FU were found with symmetrical peak shapes on a Discovery RP-amide C16 column using 10 mM ammonium acetate at pH 4.0 and methanol as the mobile phase. The retention times of capecitabine, 5'-DFCR, 5'-DFUR and 5-FU were 8.9, 5.0, 5.3 and 3.0 min, respectively. Linear calibration curves were obtained for each compound across a range from 1 to 500 microg ml(-1). The intra- and inter-day relative standard deviations (%RSD) were <5%. A single-step protein precipitation method was employed for separation of the analytes from bio-matrices. Greater than 85% recoveries were obtained for capecitabine, 5'-DFCR, 5'-DFUR and 5-FU from bio-fluids including mouse plasma, mouse serum and rabbit bile.

Capecitabine for the oral treatment of metastatic breast cancer

Women with metastatic breast cancer require tailored chemotherapy that improves outcomes without compromising quality of life. Capecitabine, a pro-drug of 5-fluorouracil, is an oral fluoropyrimidine carbamate that is sequentially activated in a three-step process. This results in the preferential production of 5-fluorouracil in tumors rather than in normal surrounding tissue, improving the tolerability and efficacy of 5-fluorouracil. In combination with docetaxel, capecitabine is the first agent that has shown superior activity to single-agent docetaxel, and it is a particularly appropriate option for younger, fitter patients with rapidly progressing disease and/or visceral metastases. However, for older patients and those with comorbidities and/or after progression to taxanes, single-agent capecitabine may be the best option. Its role in earlier disease stages (adjuvant therapy) is being investigated.

Capecitabine in carcinoma of the pancreas

Capecitabine is an oral prodrug of 5-fluorouracil, which is converted to 5-fluorouracil by three sequential enzymatic reactions. The final requisite enzyme, thymidine phosphorylase, is present at consistently higher levels in tumours compared with normal tissues, thereby suggesting that 5-fluorouracil that is delivered in this way may benefit from an element of tumour targeting and thus enhanced selectivity and better tolerability. Capecitabine has been shown to have single-agent activity in advanced carcinoma of the pancreas and to improve response rates and survival when administered in combination with gemcitabine compared with gemcitabine alone. This paper reviews the pharmacology and clinical data that are relevant to the use of capecitabine in pancreatic cancer.

Fluorine-19 or phosphorus-31 NMR spectroscopy: A suitable analytical technique for quantitative in vitro metabolic studies of fluorinated or phosphorylated drugs

Fluorine-19 or phosphorus-31 NMR (19F NMR or 31P NMR) spectroscopy provides a highly specific tool for identification of fluorine- or phosphorus-containing drugs and their metabolites in biological media as well as a suitable analytical technique for their absolute quantification. This article focuses on the application of in vitro 19F or 31P NMR to the quantitative metabolic studies of some fluoropyrimidine or oxazaphosphorine drugs in clinical use. The first part presents an overview of the advantages (non-destructive and non-selective direct quantitative study of the biological matrices) and limitations (expensive cost of the spectrometers, limited mass or concentration sensitivity) of NMR spectroscopy. The second part deals with the criteria to be considered for successful quantification by NMR (uniform excitation over the entire spectral width of the spectrum, resonance signals properly characterised by taking into account T1 values and avoiding NOE enhancements, optimisation of the data processing, choice of a suitable standard reference). The third and fourth parts report some examples of quantification of 5-fluorouracil, its prodrug capecitabine, 5-fluorocytosine and their metabolites in bulk solutions (biofluids, tissue extracts, perfusates and culture media) and heterogeneous media (excised tissues and packed intact cells) as well as cyclophosphamide and ifosfamide in biofluids. These two parts emphasise the high potential of in vitro 19F or 31P NMR for absolute quantification, in a single run, of all the fluorine- or phosphorus-containing species in the matrices analysed. The limit of quantification in bulk solutions is 1-3 microM for 19F NMR and approximately 10 microM for 31P NMR. In heterogeneous media analysed with 19F NMR, it is 2-5 nmol in excised tissues and cell pellets.

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.

Simple determination of capecitabine and its metabolites by liquid chromatography with ultraviolet detection in a single injection

Capecitabine (N4-pentoxycarbonyl-5'-deoxy-5-fluorocytidine, Xeloda), a prodrug of 5-fluorouracil (5-FU), is an oral tumor-selective fluoropyrimidine carbamate approved in the treatment of colorectal and breast cancer. It has a preferential activation to 5-FU by thymidine phosphorilase (TP) in target tumor tissues through a series of three metabolic steps minimizing the exposure of normal tissues to 5-FU. It offers the potential of less gastrointestinal toxicity and advantages in terms of convenience and quality of life for the patient, in addition to cost-effectiveness as compared with intravenous 5-FU chemotherapy. We developed a high performance liquid chromatography assay for the determination of plasma capecitabine and its nucleoside metabolite concentrations and 5-FU catabolite dihydro-5-fluorouracil in a single step extraction and a single HPLC injection. The retention times of dihydro-5-fluorouracil, 5-FU, 5'-deoxy-5-fluorouridine (5'-DFUR) and capecitabine were 3.6, 4.4, 11.4 and 20.4 min, respectively and the internal standard retention times were 8.7 and 12.2 min for 5-bromouracil (5-BU) and tegafur, respectively. The limit of detection was 0.01 microg/ml for capecitabine and its nucleoside metabolites and the limit of quantification was 0.025 microg/ml. Extraction efficiency was >80% with a single solvent mixture extraction step for all analytes of interest. The assay had good precision, the within-day and between-day standard deviation of the mean (R.S.D.) being <10% in the linear range 0.025-10 microg/ml. The authors conclude that the method described here is ideally suited for the therapeutic monitoring of capecitabine and its metabolites.

Pharmacology of anticancer drugs in the elderly population

Modifications to bodily functions and physiology are known to occur with age. These changes can have a considerable impact on the pharmacokinetic processes of absorption, distribution, metabolism and excretion and the pharmacodynamic properties of administered drugs. For many drugs with a high therapeutic index, this will be clinically unimportant, but for anticancer drugs, which usually have a low therapeutic index, these pharmacological changes can lead to dramatic consequences, such as excessive drug concentrations and unacceptable toxicity, or subtherapeutic drug concentrations and ineffective treatment. Despite the increased susceptibility of the elderly to these changes, doses are rarely adapted on the basis of pharmacokinetics and pharmacodynamics, with the exception of changes secondary to altered renal function. Until recently, only a few large prospective randomised trials have provided evidence-based data for dose adaptations in elderly patients. However, with increasing knowledge of the pharmacokinetics of anticancer drugs, advances in the knowledge of pharmacokinetic behaviour with aging, and documented efficacy and toxicity data in the elderly population, it is possible to highlight aspects of prescribing anticancer drugs in the elderly. In general, and for most drugs, age itself is not a contraindication to full-dose chemotherapy. The main limiting factors are comorbidity and poor functional status, which may be present in a significant number of the elderly population. Elderly patients with cancer are part of the daily practice of oncologists, but currently clinicians can often only estimate whether dose modification is advantageous for the elderly. This review attempts to elucidate the factors that can influence the pharmacokinetics of anticancer drugs frequently used in the elderly, and the clinical or biochemical parameters that form the basis for dose adjustments with age.

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.

Current Canadian experience with capecitabine: partnering with patients to optimize therapy

Capecitabine (Xeloda) is the first oral chemotherapeutic agent to be used in Canada for the treatment of metastatic breast cancer and metastatic colorectal cancer. The home-based administration of this drug, coupled with the importance of prompt side-effect management, presents unique challenges to oncology nurses and gives them an expanded role in optimizing therapeutic outcomes. Fulfillment of this role involves partnering with patients to help them become educated active participants in their own treatment, and to ensure that side effects are prevented, recognized, and managed adeptly. Although well tolerated, capecitabine, as with all chemotherapy, can require interventions and dose modification. Hand-foot syndrome, the most common dose-limiting toxicity, requires particular attention. Drawing from published articles and interviews with Canadian oncology care providers, this article reviews the development and safety profile of capecitabine. Best practices in side-effect management are discussed, with a particular focus on managing hand-foot syndrome and building patient partnerships.

Liquid chromatography-mass spectrometry method for the analysis of the anti-cancer agent capecitabine and its nucleoside metabolites in human plasma

A reversed-phase high-performance liquid chromatography method with electrospray ionization and mass spectral detection is described for the determination of capecitabine, 5'-deoxy-5-fluorocytidine and 5'-deoxy-5-fluorouridine in human plasma with 5-chloro-2'-deoxyuridine as the internal standard. An on-line sample clean-up procedure allows dilution of the plasma sample with the initial mobile phase. The linear dynamic range is 0.0500-10.0 microgram/ml for capecitabine, and 0.0500-25.0 microgram/ml for the metabolites, 5'-deoxy-5-fluorocytidine and 5'-deoxy-5-fluorouridine, respectively. This method has been used to analyze plasma samples from patients receiving capecitabine in combination with oxaliplatin.

Pharmacokinetic considerations of oral chemotherapy in elderly patients with cancer

Persons over the age of 65 years are the fastest growing segment of the US population. In the next 30 years they will comprise over 20% of the population. Fifty per cent of all cancers occur in this age group and therefore there will be an expected rise in the total cancer burden. There has been an increasing trend over the past 20 years toward the use of oral chemotherapy. This change has been encouraged by the need to decrease the costs of chemotherapy administration, patient preferences and quality of life issues. Factors that must be considered with oral chemotherapy administration include limitations of saturability of absorption, patient compliance and pharmacokinetic/pharmacodynamic changes which occur in elderly patients. Interpatient variability and drug metabolism, particularly age-related changes in drug metabolism are being studied. The cytochrome P450 system has been intensively studied because of its importance with regard to chemotherapeutic drugs. This article reviews these issues and provides details regarding specific drugs including temozolomide, thalidomide, topotecan, the fluoropyrimidines, etoposide, hydroxycarbamide (hydroxyurea), tamoxifen, and alkylating drugs. Complementary and alternative therapies are also discussed.

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.

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.

Capecitabine: a review of its use in the treatment of advanced or metastatic colorectal cancer

Capecitabine is an orally administered fluoropyrimidine which is selectively activated in tumour tissue to the active moiety fluorouracil and is cytotoxic through inhibition of DNA synthesis. In patients with advanced or metastatic colorectal cancer, first-line therapy with intermittent capecitabine achieved significantly higher objective tumour response rates than therapy with fluorouracil plus leucovorin in pooled analysis. Response rates were also higher in patients pretreated in the adjuvant setting and whose primary site of metastasis was the lung. However, no significant differences between the two treatment groups were seen in the time to disease progression, time to treatment failure or overall survival. Preliminary data suggest response may be improved by combining capecitabine with other anticancer therapies such as oxaliplatin, irinotecan and radiotherapy. Capecitabine in therapeutic dosage regimens generally has acceptable tolerability. Diarrhoea and hand-and-foot syndrome are the major dose-limiting toxicities associated with capecitabine therapy, with adverse effects generally of a gastrointestinal nature. Overall, diarrhoea, stomatitis, nausea and alopecia were significantly less common with capecitabine than with bolus fluorouracil and leucovorin. In addition, capecitabine recipients experienced significantly less myelosuppression, although more capecitabine recipients discontinued therapy because of adverse events. Importantly, patients spent less time in hospital after capecitabine than after bolus fluorouracil and leucovorin therapy, and the oral route of administration of capecitabine is likely to be preferred. In conclusion, capecitabine has shown superior tumour response and less myelosuppression, although more grade 3 hand-and-foot syndrome, in comparison with the 'Mayo Clinic' regimen of fluorouracil therapy, but is unlikely to improve survival. Significantly, its oral route of administration is likely to be preferred by patients. Future strategies to improve patient response may involve selection of those patients likely to respond best to capecitabine, through determination of relevant enzyme levels and combination of capecitabine with various antineoplastic agents. Data on the effect of the drug on quality of life would help establish its role. In the meantime, capecitabine appears to offer an effective and more convenient alternative to fluorouracil as first-line monotherapy for the treatment of metastatic colorectal cancer.

Rational development of capecitabine

Capecitabine is a fluoropyrimidine carbamate that was rationally designed as an oral drug capable of mimicking continuous infusion 5-fluorouracil (5-FU) and delivering 5-FU preferentially to tumour tissue. Following extensive absorption, capecitabine is rapidly converted to 5-FU via a three-step enzymatic pathway. The final step depends on thymidine phosphorylase, an enzyme present at higher concentrations in malignant compared with normal tissue. This results in the delivery of 5-FU preferentially to the tumour site. Capecitabine has demonstrated high activity in preclinical xenograft models for a wide range of human solid tumours, including those resistant to 5-FU. Phase I studies have determined the maximum tolerated dose (MTD) of capecitabine and identified a number of dosage regimens, which were subsequently evaluated in a randomised, phase II study as first-line treatment for metastatic colorectal cancer. This established an intermittent regimen of capecitabine 1250 mg/m2 twice daily for 14 days followed by a 7-day rest period as the most appropriate regimen for further clinical development.

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.