Individual fluorouracil dose adjustment in FOLFOX based on pharmacokinetic follow-up compared with conventional body-area-surface dosing: a phase II, proof-of-concept study. Clin Colorectal Cancer. 2012;11:263-267. [PMID: 22683364 DOI: 10.1016/j.clcc.2012.05.004]

Closed-loop automated drug infusion regulator: A clinically translatable, closed-loop drug delivery system for personalized drug dosing

BACKGROUND

Dosing of chemotherapies is often calculated according to the weight and/or height of the patient or equations derived from these, such as body surface area (BSA). Such calculations fail to capture intra- and interindividual pharmacokinetic variation, which can lead to order of magnitude variations in systemic chemotherapy levels and thus under- or overdosing of patients.

METHODS

We designed and developed a closed-loop drug delivery system that can dynamically adjust its infusion rate to the patient to reach and maintain the drug's target concentration, regardless of a patient's pharmacokinetics (PK).

FINDINGS

We demonstrate that closed-loop automated drug infusion regulator (CLAUDIA) can control the concentration of 5-fluorouracil (5-FU) in rabbits according to a range of concentration-time profiles (which could be useful in chronomodulated chemotherapy) and over a range of PK conditions that mimic the PK variability observed clinically. In one set of experiments, BSA-based dosing resulted in a concentration 7 times above the target range, while CLAUDIA keeps the concentration of 5-FU in or near the targeted range. Further, we demonstrate that CLAUDIA is cost effective compared to BSA-based dosing.

CONCLUSIONS

We anticipate that CLAUDIA could be rapidly translated to the clinic to enable physicians to control the plasma concentration of chemotherapy in their patients.

FUNDING

This work was supported by MIT's Karl van Tassel (1925) Career Development Professorship and Department of Mechanical Engineering and the Bridge Project, a partnership between the Koch Institute for Integrative Cancer Research at MIT and the Dana-Farber/Harvard Cancer Center.

Evaluation of dried blood spots as an alternative sampling strategy for 5-fluorouracil monitoring: From method development to clinical application

Therapeutic drug monitoring (TDM) of 5-Fluorouracil (5-FU) is strongly recommended because of its large inter-individual pharmacokinetic variability, narrow therapeutic window, and incidence of toxicity. However, there are several factors that limit the application of TDM in clinical settings. Considering the intrinsic advantages of dried microsamples, such as minimally invasive sampling, analyte stability, and cost-effective logistics, this study aimed to develop a method for the determination of 5-FU in dried blood spots (DBS) using ultra-high liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and to evaluate its clinical application. Sample preparation was based on an aqueous extraction followed by protein precipitation. Separation was performed in an Acquity UPLC® HSS C18 (150 ×2.1 mm, 1.8 µm), and the mobile phases were water and acetonitrile with 0.5% acetic acid. The total run time was 5.5 min. The method was linear from 100 to 2000 ng/mL, precise (maximum CV% of 7.5%), and accurate (98.3-115.4%). The average recovery was 70%. Blood hematocrit had a minimal impact on the assay. DBS samples were stable for 21 days at 4, 25, and 45 °C. A total of 40 paired samples of plasma, capillary DBS, and venous DBS were analyzed. Median 5-FU concentrations were 444.7, 637.0, and 499.7 ng/mL for plasma, capillary DBS, and venous DBS, respectively. Capillary and plasma concentrations were significantly correlated (r > 0.90), but there was a lack of agreement between the methods, as capillary DBS levels were on average 146% of plasma. Venous DBS corresponded to 110% of the measured plasma concentrations, with a strong correlation (r > 0.97) and agreement between the methods. Our study is the first to report the use of DBS samples to quantify 5-FU. Further studies are needed to establish whether capillary samples can replace plasma.

The past, present, and future of chemotherapy with a focus on individualization of drug dosing

While there have been rapid advances in developing new and more targeted drugs to treat cancer, much less progress has been made in individualizing dosing. Even though the introduction of immunotherapies such as CAR T-cells and checkpoint inhibitors, as well as personalized therapies that target specific mutations, have transformed clinical treatment of cancers, chemotherapy remains a mainstay in oncology. Chemotherapies are typically dosed on either a body surface area (BSA) or weight basis, which fails to account for pharmacokinetic differences between patients. Drug absorption, distribution, metabolism, and excretion rates can vary between patients, resulting in considerable differences in exposure to the active drugs. These differences result in suboptimal dosing, which can reduce efficacy and increase side-effects. Therapeutic drug monitoring (TDM), genotype guided dosing, and chronomodulation have been developed to address this challenge; however, despite improving clinical outcomes, they are rarely implemented in clinical practice for chemotherapies. Thus, there is a need to develop interventions that allow for individualized drug dosing of chemotherapies, which can help maximize the number of patients that reach the most efficacious level of drug in the blood while mitigating the risks of underdosing or overdosing. In this review, we discuss the history of the development of chemotherapies, their mechanisms of action and how they are dosed. We discuss substantial intraindividual and interindividual variability in chemotherapy pharmacokinetics. We then propose potential engineering solutions that could enable individualized dosing of chemotherapies, such as closed-loop drug delivery systems and bioresponsive biomaterials.

Testing for Dihydropyrimidine Dehydrogenase Deficiency to Individualize 5-Fluorouracil Therapy

Simple Summary

5-Fluorouracil (5-FU) is a chemotherapy drug that is commonly used to treat multiple cancers. Many people who are treated with 5-FU experience severe toxicity to the drug, and in severe cases, patients can die. This review discusses current methods for identifying people who are at high risk for severe side effects to 5-FU therapy.

Abstract

Severe adverse events (toxicity) related to the use of the commonly used chemotherapeutic drug 5-fluorouracil (5-FU) affect one in three patients and are the primary reason cited for premature discontinuation of therapy. Deficiency of the 5-FU catabolic enzyme dihydropyrimidine dehydrogenase (DPD, encoded by DPYD) has been recognized for the past 3 decades as a pharmacogenetic syndrome associated with high risk of 5-FU toxicity. An appreciable fraction of patients with DPD deficiency that receive 5-FU-based chemotherapy die as a result of toxicity. In this manuscript, we review recent progress in identifying actionable markers of DPD deficiency and the current status of integrating those markers into the clinical decision-making process. The limitations of currently available tests, as well as the regulatory status of pre-therapeutic DPYD testing, are also discussed.

The effect and therapeutic compliance of adjuvant therapy in patients with cholangiocarcinoma after R0 resection: a retrospective study

BACKGRUOUND

This study aimed to compare clinical outcomes between surveillance and adjuvant therapy (AT) groups after R0 resection for cholangiocarcinoma (CCA).

METHODS

A total of 154 patients who underwent R0 resection for CCA at the Daegu Catholic University Medical Center between January 2010 and December 2019 were included. Overall survival (OS) and progression-free survival (PFS) were analyzed.

RESULTS

The median follow-up duration was 899 days. There were 109 patients in the AT group and 45 patients in the surveillance group. The patients in the AT group were younger (67 years vs. 74 years, p<0.001) and included more males (64.2% vs. 46.7%, p=0.044). The proportion of patients with stage III CCA was larger in the AT group than in the surveillance group (13.8% vs. 2.2%, p=0.005). In addition, AT did not improve OS (5-year OS rate, 69.3% in the AT group vs. 64.2% in the surveillance group, p=0.806) or PFS (5-year PFS rate, 42.6% in the AT group vs. 48.9% in the surveillance group, p=0.113). In multivariate analysis using the Cox proportional hazards model, stage III CCA (hazard ratio [HR], 10.81; 95% confidence interval [CI], 2.92-40.00; p<0.001) was a significant predictor of OS. American Society of Anesthesiologists classification II (HR, 0.50; 95% CI, 0.31-0.81; p=0.005), and American Joint Committee on Cancer stages II (HR, 3.14; 95% CI, 1.25-7.89; p=0.015) and III (HR, 8.08; 95% CI, 2.80-23.32; p<0.001) were independent predictors of PFS.

CONCLUSION

AT after R0 resection for CCA did not improve OS or PFS.

Clinical Benefit of Therapeutic Drug Monitoring in Colorectal Cancer Patients Who Received Fluorouracil-Based Chemotherapy

Background

The impact of therapeutic drug management (TDM) on reducing toxicity and improving efficacy in colorectal cancer (CRC) patients receiving fluorouracil-based chemotherapy is still unclear.

Material/Methods

A total of 207 patients (Study Group n=54, Historical Group n=153) with metastatic colorectal cancer were enrolled. All of them received 6 administrations of the 5-FU based regimens. Initial 5-FU dosing of all patients was calculated using body surface area (BSA). In the Study Group, individual exposure during each cycle was measured using a nanoparticle immunoassay, and the 5-FU blood concentration was calculated using the area under the curve (AUC). We adjusted the 5-FU infusion dose of the next cycle based on the AUC data of the previous cycle to achieve the target of 20–30 mg×h/L.

Results

In the fourth cycle, patients in the target concentration range (AUC mean, 26.3 mg×h/L; Median, 28 mg×h/L; Range, 14–38 mg×h/L; CV, 22.4%) accounted for 46.8% of all patients, which were more than the ones in the first cycle (P<0.001). 5-FU TDM significantly reduced the toxicity of chemotherapy and improved its efficacy. The Study Group (30/289) showed a lower percentage of severe adverse events than that in the Historical Group (185/447) (P<0.001). The incidences of complete response and partial response in the Study Group were higher than those in the Historical Group (P=0.032).

Conclusions

TDM in colorectal cancer can reduce toxicity, improve efficacy and clinical outcome, and can be routinely used in 5-FU-based chemotherapy.

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.

Successful management of hyperammonemia with hemodialysis on day 2 during 5-fluorouracil treatment in a patient with gastric cancer: a case report with 5-fluorouracil metabolite analyses

Purpose

Hyperammonemia is an important adverse event associated with 5-fluorouracil (5FU) from 5FU metabolite accumulation. We present a case of an advanced gastric cancer patient with chronic renal failure, who was treated with 5FU/leucovorin (LV) infusion chemotherapy (2-h infusion of LV and 5FU bolus followed by 46-h 5FU continuous infusion on day 1; repeated every 2 weeks) and developed hyperammonemia, with the aim of exploring an appropriate hemodialysis (HD) schedule to resolve its symptoms.

Methods

The blood concentrations of 5FU and its metabolites, α-fluoro-β-alanine (FBAL), and monofluoroacetate (FA) of a patient who had hyperammonemia from seven courses of palliative 5FU/LV therapy for gastric cancer were measured by liquid chromatography–mass spectrometry.

Results

On the third day of the first cycle, the patient presented with symptomatic hyperammonemia relieved by emergency HD. Thereafter, the 5FU dose was reduced; however, in cycles 2–4, the patient developed symptomatic hyperammonemia and underwent HD on day 3 for hyperammonemia management. In cycles 5–7, the timing of scheduled HD administration was changed from day 3 to day 2, preventing symptomatic hyperammonemia. The maximum ammonia and 5FU metabolite levels were significantly lower in cycles 5–7 than in cycles 2–4 (NH3 75 ± 38 vs 303 ± 119 μg/dL, FBAL 13.7 ± 2.5 vs 19.7 ± 2.0 μg/mL, FA 204.0 ± 91.6 vs 395.9 ± 12.6 ng/mL, mean ± standard deviation, all p < 0.05). After seven cycles, partial response was confirmed.

Conclusion

HD on day 2 instead of 3 may prevent hyperammonemia in 5FU/LV therapy.

Electronic supplementary material

The online version of this article (10.1007/s00280-020-04158-1) contains supplementary material, which is available to authorized users.

A comprehensive review of economic evaluations of therapeutic drug monitoring interventions for cancer treatments

Therapeutic drug monitoring (TDM) of cancer drugs has been shown to improve treatment effectiveness and safety. The aim of this paper was to comprehensively review economic evaluations of TDM interventions for cancer drugs. Searches were conducted in 4 electronic databases, Medline, EMBASE, and Centre for Reviews and Dissemination databases (Database of Abstracts of Reviews of Effects and the NHS Economic Evaluation Database), from their inception to June 2019. Studies were included if they were economic evaluations of TDM interventions for an active cancer treatment. The quality of reporting of economic evaluations was assessed using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS checklist). Of the 11 publications identified, imatinib with TDM and 5-fluorouracil with TDM were the most commonly assessed interventions (4 publications each). Overall study quality was good, with publications meeting 61 to 91% (median 80%) of CHEERS checklist criteria. A variety of studies were used to estimate the clinical effectiveness inputs for the cost effectiveness models. All publications considered TDM to be cost-effective based on an incremental cost-effectiveness ratio below the willingness to pay threshold (64%) or being cost-saving (36%). TDM interventions were considered cost-effective across the economic evaluations. Further clinical research assessing the impact of TDM on overall survival or other long-term health outcomes may enhance the evidence base for TDM in oncology. Future economic evaluations of TDM should explicitly consider uncertainty in the underlying clinical evidence and incorporate changes in the use of newer targeted drugs that form the current standard of care.

Systemic exposure to 5-fluorouracil and its metabolite, 5,6-dihydrofluorouracil, and development of a limited sampling strategy for therapeutic drug management of 5-fluorouracil in patients with gastrointestinal malignancy

AIMS

5-Fluorouracil (5-FU) is widely used in combination chemotherapy, and literature suggests pharmacokinetic-guided dosing to improve clinical efficacy and reduce toxicity. This study aimed to determine the pharmacokinetic exposure of both 5-FU and its metabolite, 5,6-dihydrofluorouracil (DHFU), in patients with gastrointestinal malignancy and to establish a simplified strategy to assist in therapeutic drug management for dose optimization.

METHODS

This was a prospective, observational study, performed in 27 patients diagnosed with gastrointestinal malignancy who were prescribed 5-FU. Multiple samples were collected per patient over the slow bolus (15-20 min) and continuous infusion period (over 44 h) in doses 1 and 3, and the concentrations of 5-FU and DHFU were measured.

RESULTS

A higher proportion of patients had exposures within the therapeutic range in dose 3 (50%) as compared to dose 1 (37.5%) with 5-FU. There was an association between delayed time to maximum concentration of DHFU and a high maximum concentration of 5-FU. A limited sampling strategy was developed with 4 samples, 2 during the bolus period and 2 during the continuous period (at 18 h and the end of infusion), which accurately predicted the total area under the curve of 5-FU.

CONCLUSION

Using body surface area-based dosing with 5-FU, 50-60% of patients were outside of the therapeutic range. In the absence of genotype testing, measurement of the metabolite DHFU could be a phenotypical measure of dihydropyrimidine dehydrogenase enzyme activity. A limited sampling strategy was developed in patients who were prescribed a combination regimen of slow bolus, followed by a 44-hour continuous infusion of 5-FU to assist in the therapeutic drug management of patients.

5-Fluorouracil Response Prediction and Blood Level-Guided Therapy in Oncology: Existing Evidence Fundamentally Supports Instigation

5-Fluorouracil (5-FU) response prediction and therapeutic drug monitoring (TDM) are required to minimize toxicity while preserving efficacy. Conventional 5-FU dose normalization uses body surface area. It is characterized by up to 100-fold interindividual variability of pharmacokinetic (PK) parameters, and typically >50% of patients have plasma 5-FU concentrations outside the optimal range. This underscores the need for a different dose rationalization paradigm, hence there is a case for 5-FU TDM. An association between 5-FU PK parameters and efficacy/toxicity has been established. It is believed that 5-FU response is enhanced and toxicity is reduced by PK management of its dosing. The area under the concentration-time curve is the most relevant PK parameter associated with 5-FU efficacy/toxicity, and optimal therapeutic windows have been proposed. Currently, there is no universally applied a priori test for predicting 5-FU response and identifying individuals with an elevated risk of toxicity. The following two-step strategy: prediction of response/toxicity and TDM for subsequent doses seems plausible. Approximately 80% of 5-FU is degraded in a three-step sequential metabolic pathway. Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme. Its deficiency can cause toxicity with standard 5-FU doses. DPD also metabolizes uracil (U) into 5,6-dihydrouracil (UH2). The UH2/U ratio is an index of DPD activity and a credible biomarker of response and toxicity. This article outlines the UH2/U ratio as a parameter for 5-FU response/toxicity prediction and highlights key studies emphasizing the value of 5-FU TDM. Broad application of 5-FU response/toxicity prediction and blood level-guided therapy remains unmet, despite ever-increasing clinical interest. Considered collectively, existing evidence is compelling and fundamentally supports universal instigation of response/toxicity prediction and TDM.

Therapeutic drug monitoring (TDM) of 5-fluorouracil (5-FU): new preanalytic aspects

Background 5-Fluorouracil (5-FU) is frequently used for the treatment of gastrointestinal tumors. The pharmacological effect of 5-FU is influenced by genetic polymorphisms as well as differently dosed regimens. Currently, 5-FU is generally administered as a continuous infusion via an implanted port system using a body surface area (BSA)-based dose calculation. In order to optimize treatment, the area under the curve (AUC) can be estimated to allow for individual dose adjustment. A 5-FU AUC range between 20 and 30 [mg×h×L] is recommended. The aim of the current study was to assess if blood for AUC analysis could also be drawn at the side where the port system had been placed. Methods We collected EDTA blood samples of patients receiving infusional 5-FU simultaneously from different sampling points (right/left cubital vein). 5-FU concentrations were measured in a steady-state equilibrium based on nanoparticle immunoassay (My5-FU; Saladax). Results A total of 39 patients took part in this study. About half of the patients did not reach the target 5-FU concentration window (37% were under- and 16% of the patients were overdosed). Calculated median AUC was 23.3 for the right arm (range 5.8-59.4) and a median of 23.4 for the left arm (range 5.3-61.0). AUC values showed no difference between right compared to left arms (p=0.99). Conclusions In all, these results confirm that a high percentage of patients are not treated with 5-FU doses reaching suggested AUC levels of 20-30. The location of venepuncture, however, had no impact on the results of plasma 5-FU concentration.

5-Nitrouracil stabilizes the plasma concentration values of 5-FU in colorectal cancer patients receiving capecitabine

Capecitabine is selectively converted from 5′-DFUR to 5-fluorouracil (5-FU) in tumours by thymidine phosphorylase (TP). We investigated the addition of 5-nitrouracil (5-NU), a TP inhibitor, into blood samples for precise measurements of plasma 5-FU concentrations. The plasma concentration of 5-FU was measured after capecitabine administration. Two samples were obtained at 1 or 2 h after capecitabine administration and 5-NU was added to one of each pair. Samples were stored at room temperature or 4 °C and 5-FU concentrations were measured immediately or 1.5 or 3 h later. The mean plasma 5-FU concentration was significantly higher at room temperature than at 4 °C (p < 0.001). The 5-FU concentration was significantly increased in the absence of 5-NU than in the presence of 5-NU (p < 0.001). The 5-FU change in concentration was greater in the absence of 5-NU, and reached 190% of the maximum compared with baseline. A significant interaction was found between temperature and 5-NU conditions (p < 0.001). Differences between the presence or absence of 5-NU were greater at room temperature than under refrigerated conditions. 5-FU plasma concentrations after capecitabine administration varied with time, temperature, and the presence or absence of 5-NU. This indicates that plasma concentrations of 5-FU change dependent on storage conditions after blood collection.

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

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

Therapeutic Drug Monitoring in Oncology: International Association of Therapeutic Drug Monitoring and Clinical Toxicology Recommendations for 5-Fluorouracil Therapy

5-Fluorouracil (5-FU) is dosed by body surface area, a practice unable to reduce the interindividual variability in exposure. Endorsed by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology (IATDMCT), we evaluated clinical evidence and strongly recommend TDM for the management of 5-FU therapy in patients with colorectal or head-and-neck cancer receiving common 5-FU regimens. Our systematic methodology provides a framework to evaluate published evidence in support of TDM recommendations in oncology.

Association between circadian and chemotherapeutic cycle effects on plasma concentration of 5-fluorouracil and the clinical outcome following definitive 5-fluorouracil/cisplatin-based chemoradiotherapy in patients with esophageal squamous cell carcinoma

Therapeutic drug monitoring (TDM) of 5-fluorouracil (5-FU) is believed to be a clinical option for improving clinical responses. Evaluating the potential factors contributing to plasma 5-FU concentration is important to develop TDM of 5-FU. Our aim was to evaluate the association of the circadian and treatment cycle effects on plasma 5-FU concentration with the clinical response. A post hoc population analysis was performed using the plasma concentration of 5-FU and clinical response data, including prognosis from 49 patients with esophageal squamous cell carcinoma after treatment with definitive 5-FU/cisplatin-based chemoradiotherapy, consisting of prolonged infusion of 5-FU at 400 mg/(m²·day) for 5 days. The circadian rhythm and treatment cycle were applied as covariates to the model equation. The plasma 5-FU concentration in the evening was 1.3-fold higher compared with the morning, and in the second cycle, it was 1.5-fold increased compared with the first cycle, with relatively small inter-individual variations (23.3 and 16.8%). Clinical efficacy depended on the plasma 5-FU concentration, excluding the covariate effects (P=0.025), which correlated with age and height but not body surface area. Circadian variation did not contribute to the clinical response, and the increase in 5-FU plasma concentration in the second cycle significantly correlated with leucocyte counts obtained before chemoradiotherapy. The higher plasma concentration of 5-FU in the early phase of treatment may be the key determinant of clinical efficacy, whereas the variations in the plasma concentration of 5-FU owing to the time of day and treatment cycle are small contributors.

How can we best monitor 5-FU administration to maximize benefit to risk ratio?

INTRODUCTION

5-Fluorouracil (5-FU) is currently used as a chemotherapy in several cancers such as head-and-neck (H&N) and colorectal cancers. 5-FU dosing is traditionally based on body surface area (BSA), but this strategy is usually associated with severe toxicities. 5-FU is mainly catabolized by dihydropyrimidine dehydrogenase (DPD), and 5-FU dosage adaptation according to DPD status at the first cycle of treatment is now recommended. To further optimize 5-FU-based chemotherapy, a body of evidences justifies therapeutic drug monitoring (TDM). Areas covered: 5-FU pharmacokinetics, relationships between pharmacokinetics and efficacy or toxicity of 5-FU, proofs of interest of 5-FU TDM and its practical considerations are discussed. Expert opinion: BSA-adjusted 5-FU administration is associated with a large inter-individual variability, and according to this strategy, many patients experience under- or overexposure. Moreover, relationships between 5-FU area under the curve (AUC) and its toxicity or efficacy have been demonstrated, at least in patients with colorectal or H&N cancers. 5-FU therapeutic index has been validated and algorithms of 5-FU dosage adaptation according to its AUC are now available. Advances in pre-analytical and analytical steps of 5-FU TDM make its use feasible in clinical practice. Thus, there are consistent evidences to recommend 5-FU TDM in patients with advanced colorectal or H&N cancers.

[5-fluorouracil therapeutic drug monitoring: Update and recommendations of the STP-PT group of the SFPT and the GPCO-Unicancer]

Despite being 60-years old now, 5-FU remains the backbone of numerous regimen to treat a variety of solid tumors such as breast, head-and-neck and digestive cancers either in neo-adjuvant, adjuvant or metastatic settings. Standard 5-FU usually claims 15-40% of severe toxicities and up to 1% of toxic-death. Numerous studies show a stiff relationship between 5-FU exposure and toxicity or efficacy. In addition, 5-FU pharmacokinetics is highly variable between patients. Indeed, 80% of the 5-FU dose is catabolized in the liver by dihydropyrimidine dehydrogenase (DPD) into inactive compounds. It is now well established that DPD deficiency could lead to severe toxicities and, thus, require dose reduction in deficient patients. However, despite dosage adaptation based on DPD status, some patients may still experience under- or over-exposure, leading to inefficacy or major toxicity. The "Suivi thérapeutique pharmacologique et personnalisation des traitements" (STP-PT) group of the "Société française de pharmacologie et de thérapeutique" (SFPT) and the "Groupe de pharmacologie clinique oncologique" (GPCO)-Unicancer, based on the latest and most up-to-date literature data, recommend the implementation of 5-FU Therapeutic Drug Monitoring in order to ensure an adequate 5-FU exposure.

Population Pharmacokinetic-Pharmacodynamic Modeling of 5-Fluorouracil for Toxicities in Rats

BACKGROUND AND OBJECTIVES

Myelosuppression is a dose-limiting toxicity of 5-fluorouracil (5-FU). Predicting the inter- and intra-patient variability in pharmacokinetics and toxicities of 5-FU may contribute to the individualized medicine. This study aimed to establish a population pharmacokinetic-pharmacodynamic model that could evaluate the inter- and intra-individual variability in the plasma 5-FU concentration, 5-FU-induced body weight loss and myelosuppression in rats.

METHOD

Plasma 5-FU concentrations, body weight loss, and blood cell counts in rats following the intravenous administration of various doses of 5-FU for 4 days were used to develop the population pharmacokinetic-pharmacodynamic model.

RESULTS

The population pharmacokinetic model consisting of a two-compartment model with Michaelis-Menten elimination kinetics successfully characterized the individual and population predictions of the plasma concentration of 5-FU and provided credible parameter estimates. The estimates of inter-individual variability in maximal rate of saturable metabolism and residual variability were 8.1 and 22.0%, respectively. The population pharmacokinetic-pharmacodynamic model adequately described the individual complete time-course of alterations in body weight loss, erythrocyte, leukocyte, and lymphocyte counts in rats treated with various doses of 5-FU. The inter-individual variability of the drug effects in the pharmacodynamic model for body weight loss was 82.6%, which was relatively high. The results of the present study suggest that not only individual fluctuations in the 5-FU concentration but also the cell sensitivity would affect the onset and degree of 5-FU-induced toxicity.

CONCLUSION

This population pharmacokinetic-pharmacodynamic model could evaluate the inter- and intra-individual variability in drug-induced toxicity and guide the assessments of novel anticancer agents in drug development.

A correlation study of fluorouracil pharmacodynamics with clinical efficacy and toxicity

Purpose:

Plasma 5-fluorouracil (5-FU) concentrations vary greatly between individuals who have received standard dosage. Pharmacokinetic adjusted doses have been hypothesized to overcome the possibility of potential toxicity and ineffectiveness related to inappropriate plasma levels of 5-FU. In this study, we prospectively investigated the clinical benefit and toxicity of 5-FU in relation to its pharmacokinetic properties.

Methods:

Pharmacokinetics, effectiveness, and toxicity of 5-FU were investigated in 101 patients. The 5-FU pharmacokinetics were measured on day 2 of chemotherapy infusions. Clinicodemographic characteristics are outlined.

Results:

All 101 patients who received adjuvant chemotherapy were alive at the end of a median 45 months of the follow-up period. At least one grade 1 adverse event (AE) was observed in 69.3% of the patients and grade two AEs were observed in 10.1% of the patients. The 5-FU levels ranged between 103 and 4311 µg/L and area under the curve (AUC) measurements ranged between 4.5 and 189.7 mg min/L. Pharmacokinetic measurements were not significantly correlated with clinical efficacy (log-rank p = 0.21). However, higher AUC levels were positively correlated with toxicity (p = 0.02) and with the severity of adverse events. The risks of mucositis (odds ratio [OR] 1.45; p = 0.042) and neurotoxicity (OR 2.01; p = 0.009) were significantly increased in a logistic regression model.

Conclusions:

There is no clear evidence that increased plasma levels or pharmacokinetic adjusted doses of 5-FU were related to better efficacy. However, toxicity might be closely associated with increased plasma levels of 5-FU. Toxicities can be deferred via dose adjustments without any expense in efficacy.

5-FU therapeutic drug monitoring as a valuable option to reduce toxicity in patients with gastrointestinal cancer

Aims

5-FU is used as the main backbone of chemotherapy regimens for patients with colorectal and other gastrointestinal cancers. Despite development of new strategies that allowed enhancing clinical effectiveness and tolerability of 5-FU, 10-30% of patients treated with 5-FU-based regimens experience severe treatment-related toxicity. In our study, we evaluated the 5-FU exposure-toxicity relationship and investigated the efficacy of PK-guided dosing in increasing tolerability of 5-FU-based chemotherapy.

Results

50.7% of patients required dose adjustments after cycle 1. Percentage of patients within 5-FU AUC range was 49.3%, 66.9%, 61.0% at cycle 1, 2 and 3 respectively (p = 0.002 cycle 1 vs cycle 2). At all 3 cycles, lower incidences of grade I/II toxicities were observed for patients below or within range compared with those above range (19.4% vs 41.3%, p < 0.001 respectively).

Conclusions

Our analysis confirms that the use of BSA-guided dosing results in highly variable 5-FU exposure and strongly suggests that PK-guided dosing can improve tolerability of 5-FU based chemotherapy in patients with gastrointestinal cancers, thus supporting 5-FU therapeutic drug monitoring.

Methods

155 patients with gastrointestinal cancers, who were to receive 5-FU-based regimens were included in our study. At cycle 1, the 5-FU dose was calculated using patient's Body Surface Area (BSA) method. A blood sample was drawn on Day 2 to measure 5-FU concentration. At cycle 2, the 5-FU dose was adjusted using a PK-guided dosing strategy targeting a plasma AUC range of 18-28 mg·h/L, based on cycle 1 concentration. Assessments of toxicity was performed at the beginning of every cycle.

Constraint-based perturbation analysis with cluster Newton method: a case study of personalized parameter estimations with irinotecan whole-body physiologically based pharmacokinetic model

Background

Drug development considering individual varieties among patients becomes crucial to improve clinical development success rates and save healthcare costs. As a useful tool to predict individual phenomena and correlations among drug characteristics and individual varieties, recently, whole-body physiologically based pharmacokinetic (WB- PBPK) models are getting more attention. WB-PBPK models generally have a lot of drug-related parameters that need to be estimated, and the estimations are difficult because the observed data are limited. Furthermore, parameter estimation in WB-PBPK models may cause overfitting when applying to individual clinical data such as urine/feces drug excretion for each patient in which Cluster Newton Method (CNM) is applicable for parameter estimation. In order to solve this issue, we came up with the idea of constraint-based perturbation analysis of the CNM. The effectiveness of our approach is demonstrated in the case of irinotecan WB-PBPK model using common organ-specific tissue-plasma partition coefficients (Kp) among the patients as constraints in WB-PBPK parameter estimation.

Results

We find strong correlations between age, renal clearance and liver functions in irinotecan WB-PBPK model with personalized physiological parameters by observing the distributions of optimized values of strong convergence drug-related parameters using constraint-based perturbation analysis on CNM. The constraint-based perturbation analysis consists of the following three steps: (1) Estimation of all drug-related parameters for each patient; the parameters include organ-specific Kp. (2) Fixing suitable values of Kp for each organ among all patients identically. (3) Re-estimation of all drug-related parameters other than Kp by using the fixed values of Kp as constraints of CNM.

Conclusions

Constraint-based perturbation analysis could yield new findings when using CNM with appropriate constraints. This method is a new technique to find suitable values and important insights that are masked by CNM without constraints.

Electronic supplementary material

The online version of this article (10.1186/s12918-017-0513-2) contains supplementary material, which is available to authorized users.

Chemotherapy-induced neutropenia and the prognosis of colorectal cancer: a meta-analysis of cohort studies

INTRODUCTION

Recently, there has been a controversial discussion about the prognostic value of chemotherapy-induced neutropenia (CIN) in colorectal cancer patients. Thus, a meta-analysis was conducted to determine the relationship between CIN and the prognosis of colorectal cancer patients.

METHODS

We searched the PubMed, EMBASE, and Cochrane library databases to identify studies evaluating the association between CIN and colorectal cancer prognosis. Pooled random/fixed effect models were used to calculate pooled hazard ratios (HRs) and 95% confidence intervals (CIs) to assess the association.

RESULTS

Eight studies were selected for the meta-analysis, for a total of 2,745 patients. There was significant improved survival among colorectal cancer patients with CIN (HR = 0.62, 95% CI = 0.47-0.76). However, significant heterogeneity was found (p = 0.000, Ι² = 75.0%). Through subgroup analysis, we could greatly eliminate the heterogeneity and found that neutropenia was associated with better survival in stage IV colorectal cancer patients, no matter the HR calculated by overall survival (OS) or progression-free survival (PFS). Meanwhile, the prognostic value of neutropenia in stage II/III colorectal cancer can be found when the HR is calculated by disease-free survival (DFS). Additionally, we observed significant differences after stratification according to various tumor stages, endpoints, and the use of G-CSF.

CONCLUSIONS

Our results which, based on a cohort study, indicate that CIN is associated with improved survival in patients with colorectal cancer. However, further randomized controlled trials are warranted.

Timing of chemotherapy-induced neutropenia predicts prognosis in metastatic colon cancer patients: a retrospective study in mFOLFOX6 -treated patients

Background

The occurrence of Chemotherapy-induced neutropenia (CIN) was reported to be a predictor of better survival in several cancers. The objective of our study is to evaluate the relationship between the timing of CIN and prognosis.

Methods

Between June 2012 and August 2014, 290 patients with confirmed metastatic colon cancer received at least one cycle of mFOLFOX6 as first-line chemotherapy were eligible for assessment as all patients group. Of the 232 received at least six cycles of mFOLFOX6 and survived 150 days after treatment were considered as landmark group. Timing of CIN was categorized into absence, early-onset and late-onset CIN groups. The end of cycle 3 was the cutoff to differentiate early-onset or late-onset. The correlation between timing of CIN with survival was analyzed by Kaplan-Meier method and Cox proportional hazards model.

Results

In all patients group, the median survival of patients without neutropenia, early-onset and late-onset neutropenia were 6.7, 20.7 and 12.8 months (P < 0.001). The patients with early-onset and late-onset CIN had better prognosis than CIN absence by multivariate analysis. Findings were much the same for landmark group.

Conclusions

In conclusion, timing of CIN is an independent predictor of prognosis in metastatic colon cancer patients received mFOLFOX6, whereas an early-onset of CIN predicts longer survival.

Neutropenia predicts better prognosis in patients with metastatic gastric cancer on a combined epirubicin, oxaliplatin and 5-fluorouracil regimen

Chemotherapy-induced neutropenia (CIN) reportedly indicated better prognosis for some cancers. We retrospectively analyzed 150 evaluable metastatic gastric cancer (MGC) patients who had received first-line EOF5 (combination regimen of epirubicin, oxaliplatin and 5-day continuous infusion of 5-fluorouracil) treatment. We divided patients into three groups according to the worst grade of CIN: absent group (grade 0), moderate group (grade 1–2) and severe group (grade 3–4). Multivariate analyses of overall survival (OS) proved moderate and severe CIN were important prognostic factors whether regarding CIN as a time-varying covariate (TVC) or not. Compared with absent CIN, hazard ratio (HR) for moderate and severe CIN were 0.31 (95% confidential interval (CI): 0.17–0.55; P < 0.001) and 0.36 (95% CI: 0.20–0.64; P = 0.001) respectively with TVC; and were 0.31 (95% CI: 0.17–0.56; P < 0.001) and 0.34 (95% CI: 0.19–0.61; P < 0.001) respectively without TVC. In progression-free survival (PFS) analyses, moderate and severe CIN showed similar results. In the landmark group (n = 122 patients) analyses with TVC, moderate and severe CIN remained prognostic factors for PFS, while only moderate CIN was prognostic factor for OS. CIN predicted longer OS and PFS in MGC patients treated with first-line EOF5 chemotherapy.

Pharmacokinetic dose adjustment of 5-FU in modified FOLFOX7 plus bevacizumab for metastatic colorectal cancer in Japanese patients: a-JUST phase II clinical trial

PURPOSE

Dose adjustment of 5-fluorouracil (FU) based on pharmacokinetic monitoring has been shown to reduce toxicities and increase efficacy compared with dosing based on body surface area in patients with metastatic colorectal cancer (mCRC). We evaluated the efficacy and safety of pharmacokinetic dose adjustment of FU in a modified FOLFOX7 (mFOLFOX7) plus bevacizumab regimen in Japanese patients with previously untreated mCRC.

METHODS

This single-arm, multicenter phase II trial enrolled 48 patients with mCRC. Treatment consisted of 5 mg/kg intravenous bevacizumab followed by mFOLFOX7 (oxaliplatin 85 mg/m² on day 1, infused leucovorin 200 mg/m², followed by a 2400 mg/m² infusion of FU for 46 h starting on day 1), repeated every 2 weeks. FU concentrations were measured by immunoassay between 18 and 36 h after the start of continuous FU infusion, and the FU dose was then adjusted if required in subsequent cycles. The primary endpoint was response rate.

RESULTS

The median initial area under the concentration-time curve for FU was 23 mg h/L. Twenty-nine patients (60%) achieved the target concentration at the first cycle, and all 48 achieved it within the fourth cycle. The overall frequency of grade 3/4 adverse effects was 38%, with no significant difference between patients who did and not require dose adjustments. The overall response rate was 48% (95% confidence intervals = 34-62%). The median progression-free and overall survival rates were 11.3 and 24.1 months, respectively.

CONCLUSIONS

Pharmacokinetic dose adjustment of FU in mFOLFOX7 plus bevacizumab can optimize FU concentrations promptly and is safe in Japanese patients with mCRC.

Is monitoring of plasma 5-fluorouracil levels in metastatic / advanced colorectal cancer clinically effective? A systematic review

Background

Pharmacokinetic guided dosing of 5-fluorouracil chemotherapies to bring plasma 5-fluorouracil into a desired therapeutic range may lead to fewer side effects and better patient outcomes. High performance liquid chromatography and a high throughput nanoparticle immunoassay (My5-FU) have been used in conjunction with treatment algorithms to guide dosing. The objective of this study was to assess accuracy, clinical effectiveness and safety of plasma 5-fluorouracil guided dose regimen(s) versus standard regimens based on body surface area in colorectal cancer.

Methods

We undertook a systematic review. MEDLINE; MEDLINE In-Process & Other Non-Indexed Citations; EMBASE; Cochrane Library; Science Citation Index and Conference Proceedings (Web of Science); and NIHR Health Technology Assessment Programme were searched from inception to January 2014. We reviewed evidence on accuracy of My5-FU for estimating plasma 5-fluorouracil and on the clinical effectiveness of pharmacokinetic dosing compared to body surface area dosing. Estimates of individual patient data for overall survival and progression-free survival were reconstructed from published studies. Survival and adverse events data were synthesised and examined for consistency across studies.

Results

My5-FU assays were found to be consistent with reference liquid chromatography tandem mass spectrometry. Comparative studies pointed to gains in overall survival and in progression-free survival with pharmacokinetic dosing, and were consistent across multiple studies.

Conclusions

Although our analyses are encouraging, uncertainties remain because evidence is mainly from outmoded 5-fluorouracil regimens; a randomised controlled trial is urgently needed to investigate new dose adjustment methods in modern treatment regimens.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2581-x) contains supplementary material, which is available to authorized users.

Endogenous plasma and salivary uracil to dihydrouracil ratios and DPYD genotyping as predictors of severe fluoropyrimidine toxicity in patients with gastrointestinal malignancies

OBJECTIVE

The aim of this study was to evaluate the use of plasma and saliva uracil (U) to dihydrouracil (UH₂) metabolic ratio and DPYD genotyping, as a means to identify patients with dihydropyrimidine dehydrogenase (DPD) deficiency and fluoropyrimidine toxicity.

METHODS

Paired plasma and saliva samples were obtained from 60 patients with gastrointestinal cancer, before fluoropyrimidine treatment. U and UH₂ concentrations were measured by LC-MS/MS. DPYD was genotyped for alleles *7, *2A, *13 and Y186C. Data on toxicity included grade 1 to 4 neutropenia, mucositis, diarrhea, nausea/vomiting and cutaneous rash.

RESULTS

35% of the patients had severe toxicity. There was no variant allele carrier for DPYD. The [UH₂]/[U] metabolic ratios were 0.09-26.73 in plasma and 0.08-24.0 in saliva, with higher correlation with toxicity grade in saliva compared to plasma (r_s=-0.515 vs r_s=-0.282). Median metabolic ratios were lower in patients with severe toxicity as compared to those with absence of toxicity (0.59 vs 2.83 saliva; 1.62 vs 6.75 plasma, P<0.01). A cut-off of 1.16 for salivary ratio was set (AUC 0.842), with 86% sensitivity and 77% specificity for the identification of patients with severe toxicity. Similarly, a plasma cut-off of 4.0 (AUC 0.746), revealed a 71% sensitivity and 76% specificity.

CONCLUSIONS

DPYD genotyping for alleles 7, *2A, *13 and Y186C was not helpful in the identification of patients with severe DPD deficiency in this series of patients. The [UH₂]/[U] metabolic ratios, however, proved to be a promising functional test to identify the majority of cases of severe DPD activity, with saliva performing better than plasma.

Fluorouracil plasma monitoring: systematic review and economic evaluation of the My5-FU assay for guiding dose adjustment in patients receiving fluorouracil chemotherapy by continuous infusion

BACKGROUND

5-Fluorouracil (5-FU) is a chemotherapy used in colorectal, head and neck (H&N) and other cancers. Dose adjustment is based on body surface area (BSA) but wide variations occur. Pharmacokinetic (PK) dosing is suggested to bring plasma levels into the therapeutic range to promote fewer side effects and better patient outcomes. We investigated the clinical effectiveness and cost-effectiveness of the My5-FU assay for PK dose adjustment to 5-FU therapy.

OBJECTIVES

To systematically review the evidence on the accuracy of the My5-FU assay compared with gold standard methods [high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS)]; the effectiveness of My5-FU PK dosing compared with BSA; the effectiveness of HPLC and/or LC-MS compared with BSA; the generalisability of published My5-FU and PK studies; costs of using My5-FU; to develop a cost-effectiveness model.

DATA SOURCES

We searched MEDLINE, EMBASE, Science Citation Index and other databases between January and April 2014.

METHODS

Two reviewers independently screened titles and abstracts with arbitration and consensus agreement. We undertook quality assessment. We reconstructed Kaplan-Meier plots for progression-free survival (PFS) and overall survival (OS) for comparison of BSA and PK dosing. We developed a Markov model to compare My5-FU with BSA dosing which modelled PFS, OS and adverse events, using a 2-week cycle over a 20 year time horizon with a 3.5% discount rate. Health impacts were evaluated from the patient perspective, while costs were evaluated from the NHS and Personal Social Services perspective.

RESULTS

A total of 8341 records were identified through electronic searches and 35 and 54 studies were included in the clinical effectiveness and cost-effectiveness reviews respectively. There was a high apparent correlation between My5-FU, HPLC and LC-MS/mass spectrometer but upper and lower limits of agreement were -18% to 30%. Median OS were estimated as 19.6 [95% confidence interval (CI) 17.0 to 21.0] months for PK versus 14.6 (95% CI 14.1 to 15.3) months for BSA for 5-FU+folinic acid (FA); and 27.4 (95% CI 23.2 to 38.8) months for PK versus 20.6 (95% CI 18.4 to 22.9) months for BSA for FOLFOX6 in metastatic colorectal cancer (mCRC). PK versus BSA studies were generalisable to the relevant populations. We developed cost-effectiveness models for mCRC and H&N cancer. The base case assumed a cost per My5-FU assay of £ 61.03. For mCRC for 12 cycles of a oxaliplatin in combination with 5-fluorouracil and FA (FOLFOX) regimen, there was a quality-adjusted life-year (QALY) gain of 0.599 with an incremental cost-effectiveness ratio of £ 4148 per QALY. Probabilistic and scenario analyses gave similar results. The cost-effectiveness acceptability curve showed My5-FU to be 100% cost-effective at a threshold of £ 20,000 per QALY. For H&N cancer, again, given caveats about the poor evidence base, we also estimated that My5-FU is likely to be cost-effective at a threshold of £ 20,000 per QALY.

LIMITATIONS

Quality and quantity of evidence were very weak for PK versus BSA dosing for all cancers with no randomised controlled trials (RCTs) using current regimens. For H&N cancer, two studies of regimens no longer in use were identified.

CONCLUSIONS

Using a linked evidence approach, My5-FU appears to be cost-effective at a willingness to pay of £ 20,000 per QALY for both mCRC and H&N cancer. Considerable uncertainties remain about evidence quality and practical implementation. RCTs are needed of PK versus BSA dosing in relevant cancers.

Pharmacokinetically guided algorithm of 5-fluorouracil dosing, a reliable strategy of precision chemotherapy for solid tumors: a meta-analysis

Precision medicine characterizes a new era of cancer care and provides each patient with the right drug at the right dose and time. However, the practice of precision dosing is hampered by a lack of smart dosing algorithms. A pharmacokinetically guided (PKG) dosing algorithm is considered to be the leading strategy for precision chemotherapy, although the effects of PKG dosing are not completely confirmed. Hence, we conducted a meta-analysis to evaluate the effects of the PKG algorithm of 5-fluorouracil (5-FU) dosing on patients with solid tumors. A comprehensive retrieval was performed to identify all of the prospective controlled studies that compared the body surface area (BSA)-based algorithm with the PKG algorithm of 5-FU in patients with solid tumors. Overall, four studies with 504 patients were included. The PKG algorithm significantly improved the objective response rate of 5-FU-based chemotherapy compared with the BSA-based algorithm. Furthermore, PKG dosing markedly decreased the risk of total grade 3/4 adverse drug reactions, especially those related to hematological toxicity. Overall, the PKG algorithm may serve as a reliable strategy for individualized dosing of 5-FU.

Therapeutic drug monitoring of 5-fluorouracil

PURPOSE

For over 50 years, 5-FU has played a critical role in the systemic chemotherapy of cancer patients. 5-FU serves as the main backbone of combination chemotherapy for patients with colorectal cancer in both the adjuvant and metastatic disease settings. Herein, we review the current status of 5-FU therapeutic drug monitoring (TDM) and discuss its potential role in the clinical practice setting.

METHOD

PubMed and abstracts from the American Society of Clinical Oncology were searched up through September 2015 for clinical data relating to 5-FU TDM.

RESULTS

5-FU dosing has been typically determined by using body surface area (BSA). However, it is now well established that BSA-based 5-FU dosing is correlated with a wide variation of 5-FU systemic exposure. Pharmacokinetic (PK) studies of 5-FU systemic exposure have shown a wide range of interpatient variation of 5-FU plasma drug levels. Over the past 30 years, increasing efforts have been placed on optimizing 5-FU dosing with the main goals of increasing antitumor efficacy while reducing drug-associated toxicity. There is growing evidence to show that 5-FU dosing based on plasma 5-FU drug level is feasible and that 5-FU TDM can improve clinical outcomes by improving efficacy of 5-FU-based combination regimens and reducing toxicities.

CONCLUSION

Dose adjustment of 5-FU is feasible, and PK-based dosing can significantly improve clinical outcomes by reducing toxicities and improving efficacy.

Species differences in tumour responses to cancer chemotherapy

Despite advances in chemotherapy, radiotherapy and targeted drug development, cancer remains a disease of high morbidity and mortality. The treatment of human cancer patients with chemotherapy has become commonplace and accepted over the past 100 years. In recent years, and with a similar incidence of cancer to people, the use of cancer chemotherapy drugs in veterinary patients such as the dog has also become accepted clinical practice. The poor predictability of tumour responses to cancer chemotherapy drugs in rodent models means that the standard drug development pathway is costly, both in terms of money and time, leading to many drugs failing in Phase I and II clinical trials. This has led to the suggestion that naturally occurring cancers in pet dogs may offer an alternative model system to inform rational drug development in human oncology. In this review, we will explore the species variation in tumour responses to conventional chemotherapy and highlight our understanding of the differences in pharmacodynamics, pharmacokinetics and pharmacogenomics between humans and dogs. Finally, we explore the potential hurdles that need to be overcome to gain the greatest value from comparative oncology studies.

Drug Eluting Stents for Malignant Airway Obstruction: A Critical Review of the Literature

Lung cancer being the most prevalent malignancy in men and the 3(rd) most frequent in women is still associated with dismal prognosis due to advanced disease at the time of diagnosis. Novel targeted therapies are already on the market and several others are under investigation. However non-specific cytotoxic agents still remain the cornerstone of treatment for many patients. Central airways stenosis or obstruction may often complicate and decrease quality of life and survival of these patients. Interventional pulmonology modalities (mainly debulking and stent placement) can alleviate symptoms related to airways stenosis and improve the quality of life of patients. Mitomycin C and sirolimus have been observed to assist a successful stent placement by reducing granuloma tissue formation. Additionally, these drugs enhance the normal tissue ability against cancer cell infiltration. In this mini review we will concentrate on mitomycin C and sirolimus and their use in stent placement.

Metastatic Colorectal Cancer: A Systematic Review of the Value of Current Therapies

To evaluate, from a US payer perspective, the cost-effectiveness of treatment strategies for metastatic colorectal cancer (mCRC), we performed a systematic review of published cost-effectiveness analyses. We identified 14 papers that fulfilled our search criteria and revealed varying levels of value among current treatment strategies. Older agents such as 5-fluorouracil, irinotecan, and oxaliplatin provide high-value treatments. More modern agents targeting the EGFR or VEGF pathways, such as bevacizumab, cetuximab, and panitumumab, do not appear to be cost-effective treatments at their current costs. The analytical methods used within the papers varied widely, and this variation likely plays a significant role in the heterogeneity in incremental cost-effectiveness ratios. The cost-effectiveness of current treatment strategies for mCRC is highly variable. Drugs recently approved by the US Food and Drug Administration for mCRC are not cost-effective, and this is primarily driven by high drug costs.

Personalizing chemotherapy dosing using pharmacological methods

PURPOSE

Given the toxic nature and narrow therapeutic index of traditional chemotherapeutics, better methods of dose and therapy selection are critical. Pharmacological methods, including pharmacogenomics and pharmacokinetics, offer a practical method to enrich drug exposure, reduce toxicity, and improve quality of life for patients.

METHODS

PubMed and key abstracts from the American Society of Clinical Oncology (ASCO) and American Association for Cancer Research (AACR) were searched until July 2015 for clinical data relating to pharmacogenomic- and/or pharmacokinetic-guided dosing of anticancer drugs.

RESULTS

Based on the results returned from a thorough search of the literature and the plausibility of utilizing pharmacogenomic and/or pharmacokinetic methods to personalize chemotherapy dosing, we identified several chemotherapeutic agents with the potential for therapy individualization. We highlight the available data, clinical validity, and utility of using pharmacogenomics to personalize therapy for tamoxifen, 5-fluorouracil, mercaptopurine, and irinotecan, in addition to using pharmacokinetics to personalize dosing for 5-fluorouracil, busulfan, methotrexate, taxanes, and topotecan.

CONCLUSION

A concerted effort should be made by researchers to further elucidate the role of pharmacological methods in personalizing chemotherapy dosing to optimize the risk-benefit profile. Clinicians should be aware of the clinical validity, utility, and availability of pharmacogenomic- and pharmacokinetic-guided therapies in clinical practice, to ultimately allow optimal dosing for each and every cancer patient.

Relationship between chemotherapy induced hematological toxicity and prognosis in advanced colorectal cancer patients undergoing first-line FOLFOX chemotherapy

AIM: To assess whether chemotherapy induced hematological toxicity is a marker of increased progression-free survival (PFS) in patients with advanced colorectal cancer receiving first-line FOLFOX chemotherapy.

METHODS: A retrospective analysis was performed of clinical data for 158 advanced colorectal cancer patients treated at Chinese PLA General Hospital. Patient and tumor characteristics and hematological toxicity (neutropenia, anemia, and thrombocytopenia) were recorded. The relationship between hematological toxicity and prognosis was analyzed.

RESULTS: Univariate analysis showed that compared with G0 neutropenia, G1/G2/G3-4 neutropenia reduced the risk of disease progression by 27%, 36%, and 29% (HR = 0.73, 95%CI: 0.286-0.891, (P = 0.018; HR = 0.64, 95%CI: 0.56-0.88, (P = 0.03; HR = 0.71, 95%CI: 0.44-0.85, P < 0.003), respectively. Thrombocytopenia reduced the risk of progression by 26% (HR = 0.74, 95%CI: 0.68-0.753, (P = 0.015). In contrast, anemia during chemotherapy was significantly associated with poorer PFS (HR = 0.823, 95%CI: 0.609-0.921, (P = 0.03).

CONCLUSION: These data suggest that occurrence of neutropenia or thrombocytopenia is associated with a better prognosis. Monitoring of neutropenia during chemotherapy and corresponding drug adjustment may contribute to favorable PFS.

Cost effectiveness analysis of pharmacokinetically-guided 5-fluorouracil in FOLFOX chemotherapy for metastatic colorectal cancer

BACKGROUND

Dosing chemotherapy based on BSA results in marked interindividual variability in drug exposure. A randomized trial showed increased OS and decreased toxicity with PK-guided compared with BSA-based 5-FU dosing in patients with mCRC. The objective of this study was to compare the cost effectiveness of PK-based 5-FU dosing with BSA-based 5-FU dosing in patients with mCRC receiving FOLFOX (5-FU, leucovorin, and oxaliplatin).

MATERIALS AND METHODS

We developed a Markov model to evaluate the cost effectiveness of PK FOLFOX compared with BSA FOLFOX. Progression risks and cause-specific mortality were extrapolated from the fitted survival models. Costs for administration and management of adverse events were estimated based on 2013 Medicare reimbursement rates and average sale prices.

RESULTS

PK FOLFOX provided 2.03 QALYs at a cost of $50,205 compared with BSA FOLFOX, which provided 1.46 QALYs at a cost of $37,173. The incremental cost-effectiveness ratio (ICER) was $22,695 per QALY. The ICER remained < $50,000 per QALY in all univariate and multivariate sensitivity analyses.

CONCLUSION

At a $50,000 per QALY threshold, PK FOLFOX is cost effective for mCRC. Because of the cost effectiveness profile and OS advantage with PK FOLFOX, it should be evaluated further in comparative effectiveness studies.

A community-based multicenter trial of pharmacokinetically guided 5-fluorouracil dosing for personalized colorectal cancer therapy

BACKGROUND

Pharmacokinetically guided (PK-guided) versus body surface area-based 5-fluorouracil (5-FU) dosing results in higher response rates and better tolerability. A paucity of data exists on PK-guided 5-FU dosing in the community setting.

PATIENTS AND METHODS

Seventy colorectal cancer patients, from one academic and five community cancer centers, received the mFOLFOX6 regimen (5-FU 2,400 mg/m(2) over 46 hours every 2 weeks) with or without bevacizumab at cycle 1. The 5-FU continuous-infusion dose was adjusted for cycles 2-4 using a PK-guided algorithm to achieve a literature-based target area under the concentration-time curve (AUC). The primary objective was to demonstrate that PK-guided 5-FU dosing improves the ability to achieve a target AUC within four cycles of therapy. The secondary objective was to demonstrate reduced incidence of 5-FU-related toxicities.

RESULTS

At cycles 1 and 4, 27.7% and 46.8% of patients achieved the target AUC (20-25 mg × hour/L), respectively (odds ratio [OR]: 2.20; p = .046). Significantly more patients were within range at cycle 4 compared with a literature rate of 20% (p < .0001). Patients had significantly higher odds of not being underdosed at cycle 4 versus cycle 1 (OR: 2.29; p = .037). The odds of a patient being within range increased by 30% at each subsequent cycle (OR: 1.30; p = .03). Less grade 3/4 mucositis and diarrhea were observed compared with historical data (1.9% vs 16% and 5.6% vs 12%, respectively); however, rates of grade 3/4 neutropenia were similar (33% vs 25%-50%).

CONCLUSION

PK-guided 5-FU dosing resulted in significantly fewer underdosed patients and less gastrointestinal toxicity and allows for the application of personalized colorectal cancer therapy in the community setting.

Advances and directions in chemotherapy using implantable port systems for colorectal cancer: a historical review

With the recent advances in chemotherapy for colorectal cancer, the prognosis for patients with metastatic colorectal cancer has been significantly improved. The development of the implantable port system has also enabled patients to receive multiagent chemotherapy with a more satisfactory quality of life. Historically, chemotherapy using implantable port systems was begun to obtain an oncological benefit in the treatment of locoregional cancer. In the 1950s, there was an increasing interest in perfusion techniques for the application of chemotherapeutic agents, such as nitrogen mustard, in the locoregional treatment of metastatic cancer. Among them, the treatment of liver metastasis has interested oncologists for many years. On the other hand, implantable devices were developed during the intervening decades that have enabled patients with colorectal cancer with liver metastases to be treated effectively using hepatic arterial infusion; which became more common in the 1980s. The treatment of metastatic colorectal cancer increasingly requires a multimodal approach and multiple treatment options based not on convenience, but in terms of personalization and efficacy. Therefore, it is important to optimize the pharmacokinetics of chemotherapeutic agents. Implantable port systems for colorectal cancer patients have been essential for oncological practice, and the importance of these systems will remain unchanged in the near future.