Multicenter Evaluation of a Novel Nanoparticle Immunoassay for 5-Fluorouracil on the Olympus AU400 Analyzer

Comparing Scientific Machine Learning With Population Pharmacokinetic and Classical Machine Learning Approaches for Prediction of Drug Concentrations

A variety of classical machine learning (ML) approaches has been developed over the past decade aiming to individualize drug dosages based on measured plasma concentrations. However, the interpretability of these models is challenging as they do not incorporate information on pharmacokinetic (PK) drug disposition. In this work we compare drug plasma concentraton predictions of well-known population PK (PopPK) modeling with classical machine learning models and a newly proposed scientific machine learning (MMPK-SciML) framework. MMPK-SciML allows to estimate PopPK parameters and their inter-individual variability (IIV) using multimodal covariate data of each patient and does not require assumptions about the underlying covariate relationships. A dataset of 541 fluorouracil (5FU) plasma concentrations as example for an intravenously administered drug and a dataset of 302 sunitinib and its active metabolite concentrations each as example for an orally administered drug were used for analysis. Whereas classical ML models were not able to describe the data sufficiently, MMPK-SciML allowed us to obtain accurate drug plasma concentration predictions for test patients. In case of 5FU, goodness-of-fit shows that the MMPK-SciML approach predicts drug plasma concentrations more accurately than PopPK models. For sunitinib, we observed slightly less accurate drug concentration predictions compared to PopPK. Overall, MMPK-SciML has shown promising results and should therefore be further investigated as a valuable alternative to classical PopPK modeling, provided there is sufficient training data.

Rapid biomonitoring of fluoropyrimidine-based chemotherapy drugs and their biometabolites in colorectal cancer patients' blood samples using an in-syringe-based fast drug extraction technique followed by LC-MS/MS analysis

Patients with dihydropyrimidine dehydrogenase (DPD) deficiency in peripheral mononuclear cells are at higher risk of severe toxicity due to the improper dose of fluorouracil-based chemotherapy drugs, which has become an essential aspect for consideration in clinical studies. 5-fluorouracil (5-FU) is a first-line and second-line chemotherapy drug in adjuvant, neoadjuvant, or palliative therapy settings to treat solid tumors and cancers. In this work, a novel in-syringe-based fast drug extraction (IS-FaDEx) technique followed by UHPLC-MS/MS detection was developed for rapid biomonitoring of 5-FU and its biometabolites in human blood samples. In this process, the 5-FU drug and its metabolites were extracted using 1 mL of extraction solvent, and then, the cleanup was performed with solid sorbents under an semi-automated setup. Under optimized conditions, method validation results showed an excellent linearity range from 1∼1000 ng mL-1 with correlation coefficients >0.99. The detection limits varied between 0.4 and 2.0 ng mL-1, recoveries of 5-FU and its biometabolites ranged from 94.9-107.5%, and relative standard deviation were between 3.1-8.3%. The overall analytical GREEnness (AGREE) score for the proposed method was determined to be 0.83 using the AGREE metric approach, showing an excellent greenness profile. Therefore, the developed method proved efficient, robust, semi-automated, and rapid, which can considerably minimize solvent, salts, and sorbent usage following green and sustainable chemistry principles. The current approach showed effectiveness in drug monitoring investigations and can be beneficial for enhancing the efficacy and safety of 5-FU-based chemotherapy in colorectal cancer patients.

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.

Interrogating colorectal cancer metastasis to liver: a search for clinically viable compounds and mechanistic insights in colorectal cancer Patient Derived Organoids

BACKGROUND

Approximately 20-50% of patients presenting with localized colorectal cancer progress to stage IV metastatic disease (mCRC) following initial treatment and this is a major prognostic determinant. Here, we have interrogated a heterogeneous set of primary colorectal cancer (CRC), liver CRC metastases and adjacent liver tissue to identify molecular determinants of the colon to liver spreading. Screening Food and Drug Administration (FDA) approved drugs for their ability to interfere with an identified colon to liver metastasis signature may help filling an unmet therapeutic need.

METHODS

RNA sequencing of primary colorectal cancer specimens vs adjacent liver tissue vs synchronous and asynchronous liver metastases. Pathways enrichment analyses. The Library of Integrated Network-based Cellular Signatures (LINCS)-based and Connectivity Map (CMAP)-mediated identification of FDA-approved compounds capable to interfere with a 22 gene signature from primary CRC and liver metastases. Testing the identified compounds on CRC-Patient Derived Organoid (PDO) cultures. Microscopy and Fluorescence Activated Cell Sorting (FACS) based analysis of the treated PDOs.

RESULTS

We have found that liver metastases acquire features of the adjacent liver tissue while partially losing those of the primary tumors they derived from. We have identified a 22-gene signature differentially expressed among primary tumors and metastases and validated in public databases. A pharmacogenomic screening for FDA-approved compounds capable of interfering with this signature has been performed. We have validated some of the identified representative compounds in CRC-Patient Derived Organoid cultures (PDOs) and found that pentoxyfilline and, to a minor extent, dexketoprofen and desloratadine, can variably interfere with number, size and viability of the CRC -PDOs in a patient-specific way. We explored the pentoxifylline mechanism of action and found that pentoxifylline treatment attenuated the 5-FU elicited increase of ALDHhigh cells by attenuating the IL-6 mediated STAT3 (tyr705) phosphorylation.

CONCLUSIONS

Pentoxifylline synergizes with 5-Fluorouracil (5-FU) in attenuating organoid formation. It does so by interfering with an IL-6-STAT3 axis leading to the emergence of chemoresistant ALDHhigh cell subpopulations in 5-FU treated PDOs. A larger cohort of CRC-PDOs will be required to validate and expand on the findings of this proof-of-concept study.

Influence of the skeletal muscle index on pharmacokinetics and toxicity of fluorouracil

BACKGROUND

The body composition of patients has been associated with tolerability and effectiveness of anticancer therapy. This study aimed to assess the influence of the skeletal muscle index (SMI) on the pharmacokinetics and toxicity of fluorouracil.

METHODS

Patients treated in an oncological practice with fluorouracil-based chemotherapy and undergoing therapeutic drug monitoring were retrospectively investigated. Computed tomography images were analyzed to measure abdominal skeletal muscle areas in Hounsfield units for the psoas major muscle, back and total skeletal muscle to determine the SMI. For the latter, an automated segmentation method was used additionally. SMI measures were tested as covariates on fluorouracil clearance in a population pharmacokinetic model. Furthermore, regression analyses were performed to analyze the influence of SMI measures on the probability of clinically relevant adverse events (CTCAE grades ≥ 2).

RESULTS

Fluorouracil plasma concentrations of 111 patients were available. Covariate analyses showed significant improvements of the model fit by all SMI measures. However, interindividual variability of fluorouracil clearance was only slightly reduced, whereas the SMI of the back muscle showed the largest reduction (-1.1 percentage points). Lower SMI values of the back muscle increased the probability for polyneuropathy and lower SMI of the psoas increased the probability for fatigue.

CONCLUSIONS

Our results suggest that pharmacokinetics and toxicity of fluorouracil may be associated with specific SMI measures which deserve further investigation.

Therapeutic drug monitoring for cytotoxic anticancer drugs: Principles and evidence-based practices

Cytotoxic drugs are highly efficacious and also have low therapeutic index. A great degree of caution needs to be exercised in their usage. To optimize the efficacy these drugs need to be given at maximum tolerated dose which leads to significant amount of toxicity to the patient. The fine balance between efficacy and safety is the key to the success of cytotoxic chemotherapeutics. However, it is possibly more rewarding to obtain that balance for this class drugs as the frequency of drug related toxicities are higher compared to the other therapeutic class and are potentially life threatening and may cause prolonged morbidity. Significant efforts have been invested in last three to four decades in therapeutic drug monitoring (TDM) research to understand the relationship between the drug concentration and the response achieved for therapeutic efficacy as well as drug toxicity for cytotoxic drugs. TDM evolved over this period and the evidence gathered favored its routine use for certain drugs. Since, TDM is an expensive endeavor both from economic and logistic point of view, to justify its use it is necessary to demonstrate that the implementation leads to perceivable improvement in the patient outcomes. It is indeed challenging to prove the utility of TDM in randomized controlled trials and at times may be nearly impossible to generate such data in view of the obvious findings and concern of compromising patient safety. Therefore, good quality data from well-designed observational study do add immense value to the scientific knowledge base, when they are examined in totality, despite the heterogeneity amongst them. This article compiles the summary of the evidence and the best practices for TDM for the three cytotoxic drug, busulfan, 5-FU and methotrexate. Traditional use of TDM or drug concentration data for dose modification has been witnessing a sea change and model informed precision dosing is the future of cytotoxic drug therapeutic management.

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

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.

Current status and future outlooks on therapeutic drug monitoring of fluorouracil

INTRODUCTION

: Therapeutic drug monitoring (TDM) of the anticancer drug fluorouracil (5FU) as a method to support dose adjustments has been researched and discussed extensively. Despite manifold evidence of the advantages of 5FU-TDM, traditional body surface area (BSA)-guided dosing is still widely applied.

AREAS COVERED

: This review covers the latest evidence on 5FU-TDM based on a literature search in PubMed between June and September 2021. It particularly highlights new approaches of implementing 5FU-TDM into precision medicine by combining TDM with pharmacogenetic testing and/or pharmacometric models. This review further discusses remaining obstacles in order to incorporate 5FU-TDM into clinical routine.

EXPERT OPINION

: New data on 5FU-TDM further strengthen the advantages compared to BSA-guided dosing as it is able to reduce pharmacokinetic variability and thereby improve treatment efficacy and safety. Interprofessional collaboration has the potential to overcome the remaining barriers for its implementation. Pre-emptive pharmacogenetic testing followed by 5FU-TDM can further improve 5FU exposure in a substantial proportion of patients. Developing a model framework integrating pharmacokinetics and pharmacodynamics of 5FU will be crucial to fully advance into the precision medicine era. Model applications can potentially support clinicians in dose finding before starting chemotherapy. Additionally, TDM provides further assistance in continuously improving model predictions.

Effectiveness of a Controlled 5-FU Delivery Based on FZD10 Antibody-Conjugated Liposomes in Colorectal Cancer In vitro Models

The use of controlled delivery therapy in colorectal cancer (CRC) reduces toxicity and side effects. Recently, we have suggested that the Frizzled 10 (FZD10) protein, a cell surface receptor belonging to the FZD protein family that is overexpressed in CRC cells, is a novel candidate for targeting and treatment of CRC. Here, the anticancer effect of novel immuno-liposomes loaded with 5-Fluorouracil (5-FU), decorated with an antibody against FZD10 (anti-FZD10/5-FU/LPs), was evaluated in vitro on two different CRC cell lines, namely metastatic CoLo-205 and nonmetastatic CaCo-2 cells, that were found to overexpress FZD10. The anti-FZD10/5-FU/LPs obtained were extensively characterized and their preclinical therapeutic efficacy was evaluated with the MTS cell proliferation assay based on reduction of tetrazolium compound, scratch test, Field Emission Scanning Electron Microscopes (FE-SEM) investigation and immunofluorescence analysis. The results highlighted that the cytotoxic activity of 5-FU was enhanced when encapsulated in the anti-FZD10 /5-FU/LPs at the lowest tested concentrations, as compared to the free 5-FU counterparts. The immuno-liposomes proposed herein possess a great potential for selective treatment of CRC because, in future clinical applications, they can be encapsulated in gastro-resistant capsules or suppositories for oral or rectal delivery, thereby successfully reaching the intestinal tract in a minimally invasive manner.

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.

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.

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.

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.

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.

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.

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.

Evaluation of 5-fluorouracil pharmacokinetic models and therapeutic drug monitoring in cancer patients

5-fluorouracil (5-FU) remains the cornerstone of all currently applied regimens for the treatment of patients with cancers of the gastrointestinal tract, breast, and head and neck. Unfortunately, a large variation in the clearance of 5-FU has been observed between patients, suggesting that some patients might receive nonoptimal 5-FU doses. However, therapeutic drug monitoring of 5-FU has been shown to result in reduced intra- and inter-individual variability in 5-FU plasma levels and pharmacokinetically guided dose adjustments of 5-FU-containing therapy results in a significantly improved efficacy and tolerability. To date, compartmental Michaelis-Menten elimination-based modeling has proven to be a sensitive and accurate tool for analyzing the pharmacokinetics of 5-FU and to identify patients with a dihydropyrimidine dehydrogenase deficiency. These Michaelis-Menten models also allow the use of a limited sampling strategy and offer the opportunity to predict a priori the 5-FU plasma concentrations in patients receiving adapted doses of 5-FU.

Comparative evaluation of the My5-FU™ immunoassay and LC-MS/MS in monitoring the 5-fluorouracil plasma levels in cancer patients

BACKGROUND

Chemotherapies of solid tumors commonly include 5-fluorouracil (5-FU). With standard doses of 5-FU, substantial inter-patient variability has been observed in exposure levels and treatment response. Recently, improved outcomes in colorectal cancer patients due to pharmacokinetically guided 5-FU dosing were reported. We aimed at establishing a rapid and sensitive method for monitoring 5-FU plasma levels in cancer patients in our routine clinical practice.

METHODS

Performance of the Saladax My5-FU™ immunoassay was evaluated on the Roche Cobas® Integra 800 analyzer. Subsequently, 5-FU concentrations of 247 clinical plasma samples obtained with this assay were compared to the results obtained by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and other commonly used clinical analyzers (Olympus AU400, Roche Cobas c6000, and Thermo Fisher CDx90).

RESULTS

The My-FU assay was successfully validated on the Cobas Integra 800 analyzer in terms of linearity, precision, accuracy, recovery, interference, sample carryover, and dilution integrity. Method comparison between the Cobas Integra 800 and LC-MS/MS revealed a proportional bias of 7% towards higher values measured with the My5-FU assay. However, when the Cobas Integra 800 was compared to three other clinical analyzers in addition to LC-MS/MS including 50 samples representing the typical clinical range of 5-FU plasma concentrations, only a small proportional bias (≤1.6%) and a constant bias below the limit of detection was observed.

CONCLUSIONS

The My5-FU assay demonstrated robust and highly comparable performance on different analyzers. Therefore, the assay is suitable for monitoring 5-FU plasma levels in routine clinical practice and may contribute to improved efficacy and safety of commonly used 5-FU-based chemotherapies.

Personalized dosing via pharmacokinetic monitoring of 5-fluorouracil might reduce toxicity in early- or late-stage colorectal cancer patients treated with infusional 5-fluorouracil-based chemotherapy regimens

INTRODUCTION

Therapeutic plasma 5-fluorouracil (5-FU) levels are achieved in only 20% to 30% of patients with the current practice of administering 5-FU doses based on body surface area (BSA). Alternatively, 5-FU doses can be adjusted based on 5-FU pharmacokinetic (PK) monitoring. Although benefits of PK monitoring of 5-FU in metastatic colorectal cancer (CRC) have been reported, its utility among patients with early stage disease has not been reported.

PATIENTS AND METHODS

We retrospectively examined the effect of 5-FU PK monitoring in 84 CRC patients (49 stage IV and 35 stage II/III) receiving mFOLFOX6 (modifiedFOLFOX6; modified 5-fluorouracil, leucovorin, oxaliplatin protocol) or mFOLFIRI (modified 5-fluorouracil, leucovorin, irinotecan protocol). Forty-six of the 84 patients received 5-FU doses based on BSA and 38 received doses that were adjusted with PK monitoring. 5-FU plasma levels were measured using a nanoparticle immunoassay method.

RESULTS

5-fluorouracil PK monitoring significantly improved disease-free survival in stage II/III patients (P = .0429). There was also a trend towards improved progression-free survival among stage IV patients who had their 5-FU levels PK-monitored (P = .16). Moreover, 5-FU PK monitoring significantly reduced (P = .0437) and delayed (P = .0144) adverse effects in stage II/III patients. Toxicity occurred after the second 5-FU dose in the BSA group and after the sixth to seventh dose in the PK monitoring group. In stage IV patients, the onset of toxicities was also delayed with PK monitoring (P = .0605).

CONCLUSION

We provide evidence that PK monitoring of 5-FU is potentially beneficial for late stage and early stage CRC. These results contribute to the growing body of evidence regarding patient benefit when treatment decisions are based on the individual patient characteristics, in this case, a patients' 5-FU levels.

Evaluation of predictive tests for screening for dihydropyrimidine dehydrogenase deficiency

5-Fluorouracil (5-FU) is rapidly degraded by dihyropyrimidine dehydrogenase (DPD). Therefore, DPD deficiency can lead to severe toxicity or even death following treatment with 5-FU or capecitabine. Different tests based on assessing DPD enzyme activity, genetic variants in DPYD and mRNA variants have been studied for screening for DPD deficiency, but none of these are implemented broadly into clinical practice. We give an overview of the tests that can be used to detect DPD deficiency and discuss the advantages and disadvantages of these tests.

Emerging applications of nanotechnology for the diagnosis and management of vulnerable atherosclerotic plaques

An estimated 16 million people in the United States have coronary artery disease (CAD), and approximately 325,000 people die annually from cardiac arrest. About two-thirds of unexpected cardiac deaths occur without prior recognition of cardiac disease. A vast majority of these deaths are attributable to the rupture of 'vulnerable atherosclerotic plaques'. Clinically, plaque vulnerability is typically assessed through imaging techniques, and ruptured plaques leading to acute myocardial infarction are treated through angioplasty or stenting. Despite significant advances, it is clear that current imaging methods are insufficiently capable for elucidating plaque composition--which is a key determinant of vulnerability. Further, the exciting improvement in the treatment of CAD afforded by stenting procedures has been buffered by significant undesirable host-implant effects, including restenosis and late thrombosis. Nanotechnology has led to some potential solutions to these problems by yielding constructs that interface with plaque cellular components at an unprecedented size scale. By leveraging the innate ability of macrophages to phagocytose nanoparticles, contrast agents can now be targeted to plaque inflammatory activity. Improvements in nano-patterning procedures have now led to increased ability to regenerate tissue isotropy directly on stents, enabling gradual regeneration of normal, physiologic vascular structures. Advancements in immunoassay technologies promise lower costs for biomarker measurements, and in the near future, may enable the addition of routine blood testing to the clinician's toolbox--decreasing the costs of atherosclerosis-related medical care. These are merely three examples among many stories of how nanotechnology continues to promise advances in the diagnosis and treatment of vulnerable atherosclerotic plaques.

Routine dihydropyrimidine dehydrogenase testing for anticipating 5-fluorouracil-related severe toxicities: hype or hope?

5-Fluorouracil (5-FU) is a mainstay for treating colorectal cancer, alone or more frequently as part of combination therapies. However, its efficacy/toxicity balance is often limited by the occurrence of severe toxicities, showing in about 15%-20% of patients. Several clinical reports have shown the deleterious effect of dihydropyrimidine dehydrogenase (DPD) genetic polymorphism, a condition that reduces the liver detoxification step of standard dosages of 5-FU, in patients undergoing fluoropyrimidine-based therapy. Admittedly, DPD deficiency accounts for 50%-75% of the severe and sometimes life-threatening toxicities associated with 5-FU (or oral 5-FU). However, technical consensus on the best way to identify patients with DPD deficiency before administrating 5-FU is far from being achieved. Consequently, no regulatory step has been undertaken yet to recommend DPD testing as part of routine clinical practice for securing the administration of 5-FU. This review covers the limits and achievements of the various strategies proposed so far for determining DPD status in patients scheduled for 5-FU therapy.

A review of analytical methods for the determination of 5-fluorouracil in biological matrices

5-Fluorouracil (5-FU) is a cytostatic agent that has been widely used in the treatment of various solid tumours for more than 20 years, and is still considered to be among the most active antineoplastic agents in advanced colorectal cancer and malignancies of the head and neck. A large number of non-chromatographic and chromatographic methods for the quantitation of 5-FU, related prodrugs and their metabolites in biological matrices have been developed in the last 30 years to support preclinical and clinical studies. However, 5-FU monitoring has not been widely used, at least not in the USA, and certainly not outside the clinical research setting, given the absence of simple, fast and inexpensive testing methods for 5-FU monitoring. Recent developments with testing based on liquid chromatography-tandem mass spectrometry and a nanoparticle antibody-based immunoassay may facilitate routine monitoring of 5-FU in daily clinical practice. In this review the advantages and disadvantages of the bioanalytical methods developed and used for 5-FU, its metabolites and related prodrugs are discussed.