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

Immune modulation of the liver metastatic colorectal cancer microenvironment via the oral CAPOX-mediated cGAS-STING pathway

We evaluated modulation of the immunosuppressive tumor microenvironment in both local and liver metastatic colorectal cancer (LMCC), focusing on tumor-associated macrophages, which are the predominant immunosuppressive cells in LMCC. We developed an orally administered metronomic chemotherapy regimen, oral CAPOX. This regimen combines capecitabine and a nano-micelle encapsulated, lysine-linked deoxycholate and oxaliplatin complex (OPt/LDC-NM). The treatment effectively modulated immune cells within the tumor microenvironment by activating the cGAS-STING pathway and inducing immunogenic cell death. This therapy modulated immune cells more effectively than did capecitabine monotherapy, the current standard maintenance chemotherapy for colorectal cancer. The macrophage-modifying effect of oral CAPOX was mediated via the cGAS-STING pathway. This is a newly identified mode of immune cell activation induced by metronomic chemotherapy. Moreover, oral CAPOX synergized with anti-PD-1 antibody (αPD-1) to enhance the T-cell-mediated antitumor immune response. In the CT26. CL25 subcutaneous model, combination therapy achieved a 91 % complete response rate with a confirmed memory effect against the tumor. This combination also altered the immunosuppressive tumor microenvironment in LMCC, which αPD-1 monotherapy could not achieve. Oral CAPOX and αPD-1 combination therapy outperformed the maximum tolerated dose for treating LMCC, suggesting metronomic therapy as a promising strategy.

Development and Validation of a Spectrofluorimetric Method for the Quantification of Capecitabine in Bulk and Tablets

Objectives

A new, simple, and affordable spectrofluorimetric method was established for quantification of capecitabine in bulk and in marketed formulations.

Materials and Methods

Native fluorescence of capecitabine in 0.1% (w/v) cetrimide was measured at 386 nm after excitation at 313 nm.

Results

A linear relationship between fluorescence intensity and capecitabine concentration was noticed in 0.2-1.0 μg/mL range. The method was supported by checking several validation parameters as stated using International Conference on Harmonization (ICH) guidelines. The limit of detection (LOD) and quantification (LOQ) values (0.032 and 0.096 μg/mL, respectively) and results of validation parameters demonstrated that the method procedure were sensitive, accurate, precise, and reproducible (% relative standard deviation <2.0). The percentage assay in commercial formulation was found to be 99.2, which agrees with ICH guidelines.

Conclusion

Due to the above findings, developed method can be successfully adopted for routine analysis of capecitabine in pharmaceutical dosage forms.

Randomized double-blind, placebo-controlled study of topical diclofenac in the prevention of hand-foot syndrome in patients receiving capecitabine (the D-TORCH study)

Introduction

Hand-foot syndrome (HFS) is a common cutaneous side effect of capecitabine therapy. Apart from oral cyclooxygenase-2 (COX-2) inhibitor (celecoxib), there are no proven strategies for the prevention of HFS. However, celecoxib is associated with significant cardiotoxicity. To date, no study has evaluated the role of topical COX inhibitor, diclofenac. In this study, we aim to compare topical 1% diclofenac gel with placebo in the prevention of capecitabine-induced HFS.

Methods

This is a randomized, placebo-controlled, double-blind, parallel-group superiority trial: the Diclofenac Topical in Reducing Capecitabine induced HFS (D-TORCH) study. A total of 264 patients with breast and gastrointestinal malignancies will be randomly allocated (stratified by sex and type of therapy [monotherapy or combination regimen with capecitabine]) to receive either 1% topical diclofenac or placebo that will be applied over the palmar and dorsal surface of the hands twice daily whilst taking capecitabine for 12 weeks. The patients will be followed up until the end of four cycles. The primary objective of this study is to compare the effect of topical diclofenac with placebo in preventing HFS (incidence of NCI CTCAEv5.0 grade 2 or higher HFS). The secondary objective is to compare the effect of topical diclofenac with placebo on preventing all grades of HFS (incidence of NCI CTCv5.0 all grade HFS), time to develop HFS (from the start of capecitabine), patient-reported outcomes (PROs) (HF-HRQoL questionnaire), adherence with the application (self-reported), capecitabine dose changes (number of patients with dose modifications due to HFS) and safety profile (NCICTCv5.0 all grade HFS)

Discussion

The D-TORCH study aims to determine if 1% topical diclofenac reduces the incidence of grade 2 or higher HFS in patients receiving capecitabine. To date, there have been a lot of trials for hand-foot syndrome prevention using agents like pyridoxine, vitamin E, carvedilol, and various polyherbal formulations, but none has been found successful. If the trial meets the primary end point, 1% topical diclofenac will be the new standard of care for HFS prevention.

Trial registration

Clinical Trials Registry of India CTRI/2021/01/030592. Prospectively registered on January 19, 2021

Cerebral microdialysis in glioma studies, from theory to application

Despite recent advances in the treatment of solid tumors, there are few effective treatments for malignant gliomas due to the infiltrative nature, and the protective shield of blood-brain barrier or blood-tumor barriers that restrict the passage of chemotherapy drugs into the brain. Imaging techniques, such as PET and MRI, have allowed the assessment of tumor function in vivo, but they are indirect measures of activity and do not easily allow continuous repeated evaluations. Because the biology of glioma on a cellular and molecular level is fairly unknown, especially in relation to various treatments, the development of novel therapeutic approaches to this devastating condition requires a strong need for a deeper understanding of the tumor's pathophysiology and biochemistry. Cerebral microdialysis, a probe-based sampling technique, allows a discrete volume of the brain to be sampled for neurochemical analysis of neurotransmitters, metabolites, biomarkers, and chemotherapy drugs, which has been employed in studying brain tumors, and is significant for improving the treatment of glioma. In this review, the current concepts of cerebral microdialysis for glioma are elucidated, with a special emphasis on its application to neurochemistry and pharmacokinetic studies.

Anticancer therapy for breast cancer patients with skin metastases refractory to conventional treatments

Skin metastases of breast cancer are usually late events in the course of tumor progression and signify a poor prognosis. They may remain as a therapeutic challenge especially after failure of standard treatments. Topical interventions, together with or without radiotherapy, may only palliate the symptoms temporarily. However, there may be alternative treatment modalities for unresectable breast cancer skin metastases resistant to chemotherapy and radiotherapy. There are various genetic alterations in tumors and therapeutic potential of expression patterns for factors like epidermal growth factor receptor may have important clinical implications in case of disease refractory to the conventional treatments. Here, we clarified the therapeutic options and genetic alterations in skin metastatic breast cancer patients refractory to standard chemotherapeutics.

Analysis of anticancer drugs: a review

In the last decades, the number of patients receiving chemotherapy has considerably increased. Given the toxicity of cytotoxic agents to humans (not only for patients but also for healthcare professionals), the development of reliable analytical methods to analyse these compounds became necessary. From the discovery of new substances to patient administration, all pharmaceutical fields are concerned with the analysis of cytotoxic drugs. In this review, the use of methods to analyse cytotoxic agents in various matrices, such as pharmaceutical formulations and biological and environmental samples, is discussed. Thus, an overview of reported analytical methods for the determination of the most commonly used anticancer drugs is given.

Microdialysis for assessing intratumoral drug disposition in brain cancers: a tool for rational drug development

IMPORTANCE OF THE FIELD

many promising targeted agents and combination therapies are being investigated for brain cancer. However, the results from recent clinical trials have been disappointing. A better understanding of the disposition of drug in the brain early in drug development would facilitate appropriate channeling of new drugs into brain cancer clinical trials.

AREAS COVERED IN THIS REVIEW

barriers to successful drug activity against brain cancer and issues affecting intratumoral drug concentrations are reviewed. The use of the microdialysis technique for extracellular fluid (ECF) sampling and its application to drug distribution studies in brain are reviewed using published literature from 1995 to the present. The benefits and limitations of microdialysis for performing neuorpharmacokinetic (nPK) and neuropharmacodynamic (nPD) studies are discussed.

WHAT THE READER WILL GAIN

the reader will gain an appreciation of the challenges involved in identifying agents likely to have efficacy in brain cancer, an understanding of the general principles of microdialysis, and the power and limitations of using this technique in early drug development for brain cancer therapies.

TAKE HOME MESSAGE

a major factor preventing efficacy of anti-brain cancer drugs is limited access to tumor. Intracerebral microdialysis allows sampling of drug in the brain ECF. The resulting nPK/nPD data can aid in the rational selection of drugs for investigation in brain tumor clinical trials.

Increasing tumoral 5-fluorouracil concentrations during a 5-day continuous infusion: a microdialysis study

Purpose

Response to anticancer therapy is believed to be directly related to the concentration of the anticancer drug in the tumor itself. Assessment of intra-tumor drug pharmacokinetics can be helpful to gain more insight into mechanisms involved in the (in)sensitivity of tumors to anticancer therapy. We explored the pharmacokinetics of 5-fluorouracil in both plasma and tumor tissue during a 5-day continuous infusion of 5-fluorouracil in patients with cancer. Sampling for measurement of 5-fluorouracil in tumor tissue was performed using microdialysis.

Experimental design

In seven patients with an accessible (sub)cutaneous tumor treated with a continuous 5-fluorouracil infusion, plasma and microdialysate samples from tumor and normal adipose tissue were collected over a period of 5 days.

Results

For six patients, drug concentrations in both tumor tissue and plasma were available. Concentration–time curves of unbound 5-fluorouracil were lower in tumor tissue compared to the curves in plasma, but exposure ratios of tumor tissue versus plasma increased during the 5-day infusion period. The presence of circadian rhythmicity of 5-fluorouracil pharmacokinetics in the tumor itself was demonstrated as 5-fluorouracil concentrations in tumor extracellular fluid were higher during the night than during daytime.

Conclusion

Microdialysis was successfully employed in patients with cancer during a continuous 5-day 5-fluorouracil infusion. Plasma and tumor pharmacokinetics of 5-fluorouracil differed substantially with increasing 5-fluorouracil concentrations in tumor over time, possibly resulting from a lowered interstitial fluid pressure by 5-fluorouracil itself. This microdialysis 5-fluorouracil model might be useful to monitor the effect of drug delivery modulating strategies in future studies.

EUS-guided in vivo microdialysis of the pancreas: a novel technique with potential diagnostic and therapeutic application

BACKGROUND

Microdialysis has been used in vivo to measure dynamic temporal variations in extracellular or interstitial concentrations of non-protein-bound substances that are unstable in the systemic circulation.

OBJECTIVE

To evaluate the technical feasibility and possible complications of EUS-guided in vivo microdialysis of the pancreas.

DESIGN AND INTERVENTION

Under the guidance of an echoendoscope inserted into the stomach of each dog, the pancreatic parenchyma was punctured by using a 19-gauge needle. A specially developed microdialysis probe threaded through the lumen of the 19-gauge needle was positioned in the pancreas. The probe was constantly perfused with saline solution at a flow rate of 1.0 microL/minute.

SETTING

Experiments on 8 beagle dogs.

MAIN OUTCOME MEASUREMENTS

The concentration of 5-fluorouracil (5-FU) in the microdialysate was measured at 10-minute intervals, once before and for 8 times after a single (20 mg/kg) bolus intravenous infusion of 5-FU.

RESULTS

Following the administration of 5-FU, the concentration of 5-FU in all macrodialysate samples exceeded the cut-off value by more than 100-fold. The 5-FU levels in the microdialysate increased rapidly, peaked by 10 minutes (13.9 microg/mL), and gradually declined thereafter. No local bleeding or accumulation of fluid around the pancreas was observed.

LIMITATION

Sampling was unsuccessful in 2 of the 8 dogs because the probe broke while being inserted into the pancreatic parenchyma.

CONCLUSION

EUS-guided pancreatic microdialysis is feasible and has multiple potential clinical/therapeutic applications, including monitoring pharmacokinetics focally and detecting novel biomarkers that are unstable or undetectable in the plasma.

Application of prolonged microdialysis sampling in carboplatin-treated cancer patients

Purpose

To better understand the mechanisms underlying (in)sensitivity of tumors to anticancer drugs, assessing intra-tumor drug pharmacokinetics (PKs) could be important. We explored the feasibility of microdialysis in tumor tissue for multiple days in a clinical setting, using carboplatin as model drug.

Methods

Plasma and microdialysate samples from tumor and adipose normal tissues were collected up to 47 h after dosing in eight carboplatin-treated patients with an accessible (sub)cutaneous tumor.

Results

Pharmacokinetics were evaluable in tumor tissue in 6/8 patients and in adipose normal tissue in 3/8 patients. Concentration–time curves of unbound platinum in both the tissues followed the pattern of the curves in plasma, with exposure ratios of tissue versus plasma ranging from 0.64 to 1.46.

Conclusions

Microdialysis can be successfully employed in ambulant patients for multiple days, which enables one to study tissue PK of anticancer drugs in normal and malignant tissues in more detail.

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

Background

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

Methods

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

Results

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

Conclusion

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

Gender specific tumour pharmacology--from kinetics to genetics

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

Microdialysis versus other techniques for the clinical assessment of in vivo tissue drug distribution

Quantification of target site pharmacokinetics (PK) is crucial for drug discovery and development. Clinical microdialysis (MD) has increasingly been employed for the description of drug distribution and receptor phase PK of the unbound fraction of various analytes. Costs for MD experiments are comparably low and given suitable analytics, target tissue PK of virtually any drug molecule can be quantified. The major limitation of MD stems from the fact that organs such as brain, lung or liver are not readily accessible without surgery. Recently, non-invasive imaging techniques, i.e. positron emission tomography (PET) or magnetic resonance spectroscopy (MRS), have become available for in vivo drug distribution assessment and allow for drug concentration measurements in practically every human organ. Spatial resolution of MRS imaging, however, is low and although PET enables monitoring of regional drug concentration differences with a spatial resolution of a few millimetres, discrimination between bound and unbound drug or parent compound and metabolite is difficult. Radiotracer development is furthermore time and labour intensive and requires special expertise and radiation exposure and costs originating from running a PET facility cannot be neglected. The recent complementary use of MD and imaging has permitted to exploit individual strengths of these diverse techniques. In conclusion, MD and imaging techniques have provided drug distribution data that have so far not been available. Used alone or in combination, these methods may potentially play an important role in future drug research and development with the potential to serve as translational tools for clinical decision making.

In vivo microdialysis for PK and PD studies of anticancer drugs

In vivo microdialysis technique has become one of the major tools to sample endogenous and exogenous substances in extracellular spaces. As a well-validated sampling technique, microdialysis has been frequently employed for quantifying drug disposition at the desired target in both preclinical and clinical settings. This review addresses general methodological considerations critical to performing microdialysis in tumors, highlights selected preclinical and clinical studies that characterized drug disposition in tumors by the use of microdialysis, and illustrates the potential application of microdialysis in the assessment of tumor response to cancer treatment.

Microdialysis

Microdialysis is a probe-based sampling method, which, if linked to analytical devices, allows for the measurement of drug concentration profiles in selected tissues. During the last two decades, microdialysis has become increasingly popular for preclinical and clinical pharmacokinetic studies. The advantage of in vivo microdialysis over traditional methods relates to its ability to continuously sample the unbound drug fraction in the interstitial space fluid (ISF). This is of particular importance because the ISF may be regarded as the actual target compartment for many drugs, e.g. antimicrobial agents or other drugs mediating their action through surface receptors. In contrast, plasma concentrations are increasingly recognised as inadequately predicting tissue drug concentrations and therapeutic success in many patient populations. Thus, the minimally invasive microdialysis technique has evolved into an important tool for the direct assessment of drug concentrations at the site of drug delivery in virtually all tissues. In particular, concentrations of transdermally applied drugs, neurotransmitters, antibacterials, cytotoxic agents, hormones, large molecules such as cytokines and proteins, and many other compounds were described by means of microdialysis. The combined use of microdialysis with non-invasive imaging methods such as positron emission tomography and single photon emission tomography opened the window to exactly explore and describe the fate and pharmacokinetics of a drug in the body. Linking pharmacokinetic data from the ISF to pharmacodynamic information appears to be a straightforward approach to predicting drug action and therapeutic success, and may be used for decision making for adequate drug administration and dosing regimens. Hence, microdialysis is nowadays used in clinical studies to test new drug candidates that are in the pharmaceutical industry drug development pipeline.

Comparative pharmacology of oral fluoropyrimidines: a focus on pharmacokinetics, pharmacodynamics and pharmacomodulation

The main purpose of the present review article was to shed light on the different 5-fluorouracil (5-FU) prodrugs by underlining their respective pharmacological features in terms of metabolic activation, dihydropyrimidine dehydrogenase inhibition, pharmacokinetic profile and biomodulation ability. Oral fluoropyrimidines differ particularly as concerns their pharmacokinetic profile and especially in the delivery of circulating 5-FU. More clinical studies need to be performed incorporating tumour predictive markers during oral fluoropyrimidine-based treatment. The new possibilities are to achieve pharmacomodulation of oral fluoropyrimidines, notably for UFT and capecitabine, that open up the prospect of establishing significant novel treatment protocols based on drug combinations.

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

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