A fully validated LC‑MS/MS method for quantifying bevacizumab in plasma samples from patients with NSCLC and its implications in therapeutic drug monitoring

Given the increasing use of bevacizumab in combinatorial drug therapy for a multitude of different cancer types, there is a need for therapeutic drug monitoring to analyze the possible correlation between drug trough concentration, and therapeutic effect and adverse reactions. An ultra-performance liquid chromatography tandem-mass spectrometry method was then developed and validated to determine bevacizumab levels in human plasma samples. Chromatographic separation was achieved on a Shimadzu InertSustainBio C18 HP column, whereas subsequent mass spectrometric analysis was performed using a Shimadzu 8050CL triple quadrupole mass spectrometer equipped with an electro-spray ionization source in the positive ion mode. In total, three multiple reaction monitoring transitions of each of the surrogate peptides were chosen with 'FTFSLDTSK' applied as the quantification peptide whereas 'VLIYFTSSLHSGVPSR' and 'STAYLQMNSLR' were designated as the verification peptides using the Skyline software. This analytical method was then fully validated, with specificity, linearity, lower limit of quantitation, accuracy, precision, stability, matrix effect and recovery calculated. The linearity of this method was developed to be within the concentration range 5-400 µg/ml for bevacizumab in human plasma. Subsequently, eight patients with non-small cell lung cancer (NSCLC) were recruited and injected with bevacizumab over three periods of treatment to analyze their steady-state trough concentration and differences. To conclude, the results of the present study suggest that bevacizumab can be monitored in a therapeutic setting in patients with NSCLC.

The development and validation of a liquid chromatography tandem mass spectrometry method for the quantification of selinexor and its application in Chinese multiple myeloma patients

Selinexor is a nuclear exportin-1 (XPO1) inhibitor that has been approved for the treatment of multiple myeloma patients. However, sustained use of selinexor may result in some undesirable consequences. Furthermore, selinexor has moderate inter-patient variability. Herein, we developed an ultrahigh-performance liquid chromatography tandem mass spectrometry method for measuring selinexor levels in human plasma ranging from 1 to 1000 ng mL-1. Furthermore, the developed approach was validated in accordance with FDA criteria. The established approach demonstrated inter-day and intra-day precision, expressed as the relative standard deviation, of less than 8%, with accuracies of less than 6%, expressed as relative error. The results showed that the protein depletion was quite complete for selinexor extraction, with recoveries ranging from 85.89 to 108.38%. The validated method facilitates the quantitation of selinexor in multiple myeloma patients. The selinexor plasma concentration exhibits obvious inter-patient' variability after administration. Thus, it is necessary to make a personalized prescription through therapeutic drug monitoring. Furthermore, the change in platelet counts before and after selinexor treatment was shown to be related to the plasma concentration at 3 h after administration, which provides the basis for therapeutic drug monitoring sampling time points and a method for predicting the occurrence of thrombocytopenia. In conclusion, the developed method can be used for the quantification of the plasma concentration of selinexor, and it is of great significance to conduct therapeutic drug monitoring for patients taking selinexor in order to enhance therapeutic effects and prevent the occurrence of adverse reactions.

[Management of high-alert medications by clinical pharmacological approaches]

During the past decade, many high-alert medications have been developed and used in clinical practice. Particularly, in the pharmacotherapy of high-alert medications with large individual differences, more attention is needed. To achieve appropriate and individualized pharmacotherapy, there are many issues to be addressed from a clinical pharmacology perspective, such as enhanced monitoring and prior risk identification. This paper is focusing on the therapeutic drug monitoring of molecularly targeted anticancer drugs, and the provision of real-world evidence based on the clinical implementation of pharmacogenetic testing.

Therapeutic drug monitoring to personalize dosing of imatinib, sunitinib, and pazopanib: A mixed methods study on barriers and facilitators

BACKGROUND

Personalized dosing based on measurement of individual drug levels and adjusting the dose accordingly can improve efficacy and decrease unnecessary toxicity of oncological treatment. For imatinib, sunitinib, and pazopanib, this therapeutic drug monitoring (TDM)-guided dosing is, however, not routinely used, despite accumulating evidence favoring individualized dosing. Therefore, we aimed to identify and quantify (potential) barriers and facilitators in TDM-guided dosing for imatinib, sunitinib, and pazopanib.

METHODS

We performed a mixed methods study among all stakeholders involved: patients, healthcare professionals (HCPs), pharmaceutical companies, and health insurance companies. During the first qualitative part of this study, we performed semi-structured individual interviews and one focus group interview to identify all (potential) barriers and facilitators, and during the second quantitative part of this study, we used a web-based survey to quantify these findings. The interviews addressed the six domains of the implementation of change model of Grol and Wensing: (1) the innovation itself; (2) the HCP; (3) the patient; (4) social context; (5) organizational context; and (6) finances, law, and governance.

RESULTS

In the qualitative study, we interviewed 20 patients, 18 HCPs and 10 representatives of pharmaceutical and health insurance companies and identified 72 barriers and 90 facilitators. In the quantitative study, the survey was responded by 66 HCPs and 58 patients. Important barriers were on the domain of the HCP, such as a lack of experience with TDM (36.4%), on the domain of the patient, such as lack of awareness of TDM (39.7%), and the processing time for measurement and interpretation of the TDM result (40.9%) (organizational domain). Important facilitators were education of HCPs (95.5%), education of patients (87.9%) and facilitating an overview of when and where TDM measurements are being performed (86.4%).

CONCLUSION

We identified and quantified important barriers and facilitators for the implementation of TDM-guided dosing for imatinib, sunitinib, and pazopanib. Based on our results, the implementation strategy should mainly focus on educating both HCPs and patients and on the organizational aspect of TDM.

Rapid extraction of osimertinib and its active metabolite in urine by miniaturized centrifugal spin-column extraction using ionic liquid hybrid hierarchical porous adsorbent

Osimertinib (OSIM) is widely used as a mainstream drug for the treatment of non-small cell lung cancer (NSCLC). However, the lack of a rapid extraction and detection method for OSIM and its metabolite, AZ-5104, has limited clinical drug metabolism and drug resistance research because the drug is unstable. In this study, a new ionic liquid hybrid hierarchical porous material (IL-HHPM) was synthesized with hierarchical porous structures, including micropores (1.6-2.0 nm), mesopores (2.0-50.0 nm), macropores (50.0-148.7 nm), and multiple functional groups via a one-step hydrothermal method using silanized ionic liquids (IL) as functionalized hybrid monomer. The IL-HHPM has the advantages of a high specific surface area (437.4 ± 4.6 m2 g-1), sizable pore volume (0.74 cm3 g-1), and fast mass transfer, additionally, the IL-HHPM adsorbed OSIM and AZ-5104 via π-π interactions and hydrogen bonding. OSIM and AZ-5104 were rapidly extracted and measured in human urine using rapid and miniaturized centrifugal spin-column extraction (MCSCE), which was based on the IL-HHPM. The optimized factors for the extraction recoveries of OSIM and AZ-5104 were adsorbent dosage (8.0 mg), sample volume (0.5 mL), and operation time (9.0 min), and markedly reduced the adsorbent dosage and operation time. The IL-HHPM-MCSCE-HPLC method displayed good linearity (0.02-5.00 μg mL-1, r ≥ 0.9997), satisfying accuracy (spiked recoveries of 87.7%-100.0%), and good precision (RSDs ≤ 7.0%). The developed method is rapid, sensitive, and reproducible for the simultaneous determination of trace level of OSIM and AZ-5104 in human urine.

High throughput LC/ESI-MS/MS method for simultaneous analysis of 20 oral molecular-targeted anticancer drugs and the active metabolite of sunitinib in human plasma

Many types of oral molecular-targeted anticancer drugs are clinically used in cancer genomic medicine. Combinations of multiple molecular-targeted anticancer drugs are also being investigated, expecting to prolong the survival of patients with cancer. Therapeutic drug monitoring of oral molecular-targeted drugs is important to ensure efficacy and safety. A liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) has been used for simultaneous determination of these drugs in human plasma. However, the sensitivity of mass spectrometers and differences in the therapeutic range of drugs have rendered the development of simultaneous LC/ESI-MS/MS methods difficult. In this study, a simultaneous quantitative method for 20 oral molecular-targeted anticancer drugs and the active metabolite of sunitinib was developed based on the results of linear range shifts of the calibration curves using four ion abundance adjustment techniques (collision energy defects, in-source collision-induced dissociation, secondary product ion selected reaction monitoring, and isotopologue selected reaction monitoring). The saturation of the detector for the seven analytes was resolved by incorporating optimal ion abundance adjustment techniques. Furthermore, the reproducibility of this method was confirmed in validation tests, and plasma from patients was measured by this method to demonstrate its usefulness in actual clinical practice. This analytical method is expected to make a substantial contribution to the promotion of personalized medicine in the future.

Honeycomb resin-based spin-column solid-phase extraction for efficient determination of alectinib and its metabolite in human urine

Alectinib and its metabolite, M4, have demonstrated a satisfactory clinical therapeutic effect in the treatment of anaplastic lymphoma kinase-positive advanced non-small-cell lung cancer. Due to individual differences among patients, therapeutic drug monitoring (TDM) is critical for guaranteeing appropriate clinical drug use. To realize TDM for alectinib and its metabolite, M4, a honeycomb phenol-formaldehyde resin (PFR) with excellent hydrophilic properties, abundant adsorption force, and a stable porous structure was synthesized by modifying the porogens F127 and P123. The prepared PFR was employed as an adsorbent in a simple and efficient spin-column solid-phase extraction (SPE) process. A rapid method for detecting alectinib and its metabolite M4 in urine was thereby established. The established method showed a linear range of 0.0200 μg mL^-1-5.00 μg mL^-1 and the recovery range of 98.8-103% for spiked urine samples, with relative standard deviations of ≤ 4.87% (n = 3). Our results proved the practicability of the proposed honeycomb-PFR spin-column SPE method in TDM for alectinib and its metabolite, M4.

The Application of Virtual Therapeutic Drug Monitoring to Assess the Pharmacokinetics of Imatinib in a Chinese Cancer Population Group

PURPOSE

Imatinib is used in gastrointestinal stromal tumours (GIST) and chronic myeloid leukaemia (CML). Oncology patients demonstrate altered physiology compared to healthy adults, e.g. reduced haematocrit, increased α-1 acid glycoprotein, decreased albumin and reduced glomerular filtration rate (GFR), which may influence imatinib pharmacokinetics. Given that Chinese cancer patients often report raised imatinib plasma concentrations and wider inter-individual variability reported in trough concentration when compared to Caucasian cancer patients, therapeutic drug monitoring (TDM) has been advocated.

METHOD

This study utilised a previously validated a Chinese cancer population and assessed the impact of imatinib virtual-TDM in Chinese and Caucasian cancer populations across a dosing range from 200-800 mg daily.

RESULTS

Staged dose titration to 800 mg daily, resulted in recapitulation to within the target therapeutic range for 50 % (Chinese) and 42.1% (Caucasian) subjects possessing plasma concentration < 550 ng/mL when dosed at 400 mg daily. For subjects with plasma concentrations >1500 ng/mL when dosed at 400 mg daily, a dose reduction to 200 mg once daily was able to recover 67 % (Chinese) and 87.4 % (Caucasian) patients to the target therapeutic range.

CONCLUSION

Virtual TDM highlights the benefit of pharmacokinetic modelling to optimising treatments in challenging oncology population groups.

Molecular Recognition and In Vivo Detection of Temozolomide and 5-Aminoimidazole-4-carboxamide for Glioblastoma Using Near-Infrared Fluorescent Carbon Nanotube Sensors

There is a pressing need for sensors and assays to monitor chemotherapeutic activity within the human body in real time to optimize drug dosimetry parameters such as timing, quantity, and frequency in an effort to maximize efficacy while minimizing deleterious cytotoxicity. Herein, we develop near-infrared fluorescent nanosensors based on single walled carbon nanotubes for the chemotherapeutic Temozolomide (TMZ) and its metabolite 5-aminoimidazole-4-carboxamide using Corona Phase Molecular Recognition as a synthetic molecular recognition technique. The resulting nanoparticle sensors are able to monitor drug activity in real-time even under in vivo conditions. Sensors can be engineered to be biocompatible by encapsulation in poly(ethylene glycol) diacrylate hydrogels. Selective detection of TMZ was demonstrated using U-87 MG human glioblastoma cells and SKH-1E mice with detection limits below 30 μM. As sensor implants, we show that such systems can provide spatiotemporal therapeutic information in vivo, as a valuable tool for pharmacokinetic evaluation. Sensor implants are also evaluated using intact porcine brain tissue implanted 2.1 cm below the cranium and monitored using a recently developed Wavelength-Induced Frequency Filtering technique. Additionally, we show that by taking the measurement of spatial and temporal analyte concentrations within each hydrogel implant, the direction of therapeutic flux can be resolved. In all, these types of sensors enable the real time detection of chemotherapeutic concentration, flux, directional transport, and metabolic activity, providing crucial information regarding therapeutic effectiveness.

Dose Individualization of Oral Multi-Kinase Inhibitors for the Implementation of Therapeutic Drug Monitoring

Oral multi-kinase inhibitors have transformed the treatment landscape for various cancer types and provided significant improvements in clinical outcomes. These agents are mainly approved at fixed doses, but the large inter-individual variability in pharmacokinetics and pharmacodynamics (efficacy and safety) has been an unsolved clinical issue. For example, certain patients treated with oral multi-kinase inhibitors at standard doses have severe adverse effects and require dose reduction and discontinuation, yet other patients have a suboptimal response to these drugs. Consequently, optimizing the dosing of oral multi-kinase inhibitors is important to prevent over-dosing or under-dosing. To date, multiple studies on the exposure-efficacy/toxicity relationship of molecular targeted therapy have been attempted for the implementation of therapeutic drug monitoring (TDM) strategies. In this milieu, we recently conducted research on several multi-kinase inhibitors, such as sunitinib, pazopanib, sorafenib, and lenvatinib, with the aim to optimize their treatment efficacy using a pharmacokinetic/pharmacodynamic approach. Among them, sunitinib use is an example of successful TDM implementation. Sunitinib demonstrated a significant correlation between drug exposure and treatment efficacy or toxicities. As a result, TDM services for sunitinib has been covered by the National Health Insurance program in Japan since April 2018. Additionally, other multi-kinase targeted anticancer drugs have promising data regarding the exposure-efficacy/toxicity relationship, suggesting the possibility of personalization of drug dosage. In this review, we provide a comprehensive summary of the clinical evidence for dose individualization of multi-kinase inhibitors and discuss the utility of TDM of multi-kinase inhibitors, especially sunitinib, pazopanib, sorafenib, and lenvatinib.

Relevance of Therapeutic Drug Monitoring of Tyrosine Kinase Inhibitors in Routine Clinical Practice: A Pilot Study

INTRODUCTION

The main goal of treatment in cancer patients is to achieve the highest therapeutic effectiveness with the least iatrogenic toxicity. Tyrosine kinase inhibitors (TKIs) are anticancer oral agents, usually administered at fixed doses, which present high inter- and intra-individual variability due to their pharmacokinetic characteristics. Therapeutic drug monitoring (TDM) can be used to optimize the use of several types of medication.

OBJECTIVE

We evaluated the use of TDM of TKIs in routine clinical practice through studying the variability in exposure to erlotinib, imatinib, lapatinib, and sorafenib and dose adjustment.

MATERIALS AND METHODS

We conducted a retrospective analytical study involving patients who received treatment with TKIs, guided by TDM and with subsequent recommendation of dose adjustment. The quantification of the plasma levels of the different drugs was performed using high-performance liquid chromatography (HPLC). The Clinical Research Ethics Committee of the Hospital Quirónsalud Torrevieja approved this study.

RESULTS

The inter-individual variability in the first cycle and in the last monitored cycle was 46.2% and 44.0% for erlotinib, 48.9 and 50.8% for imatinib, 60.7% and 56.0% for lapatinib and 89.7% and 72.5% for sorafenib. Relationships between exposure and baseline characteristics for erlotinib, imatinib, lapatinib and sorafenib were not statistically significant for any of the variables evaluated (weight, height, body surface area (BSA), age and sex). Relationships between height (p = 0.021) and BSA (p = 0.022) were statistically significant for sorafenib. No significant relationships were observed between C_trough and progression-free survival (PFS) or overall survival (OS) for any drug, except in the case of sunitinib (correlation between C_trough and PFS p = 0.023) in the exposure-efficacy analysis.

CONCLUSIONS

Erlotinib, imatinib, lapatinib and sorafenib show large inter-individual variability in exposure. TDM entails a significant improvement in exposure and enables more effective and safe use of TKIs in routine clinical practice.

Therapeutic Drug Monitoring of Tyrosine Kinase Inhibitors Using Dried Blood Microsamples

Therapeutic drug monitoring (TDM) of tyrosine kinase inhibitors (TKIs) is not yet performed routinely in the standard care of oncology patients, although it offers a high potential to improve treatment outcome and minimize toxicity. TKIs are perfect candidates for TDM as they show a relatively small therapeutic window, a wide inter-patient variability in pharmacokinetics and a correlation between drug concentration and effect. Moreover, most of the available TKIs are susceptible to various drug-drug interactions and medication adherence can be checked by performing TDM. Plasma, obtained via traditional venous blood sampling, is the standard matrix for TDM of TKIs. However, the use of plasma poses some challenges related to sampling and stability. The use of dried blood microsamples can overcome these limitations. Collection of samples via finger-prick is minimally invasive and considered convenient and simple, enabling sampling by the patients themselves in their home-setting. The collection of small sample volumes is especially relevant for use in pediatric populations or in pharmacokinetic studies. Additionally, working with dried matrices improves compound stability, resulting in convenient and cost-effective transport and storage of the samples. In this review we focus on the different dried blood microsample-based methods that were used for the quantification of TKIs. Despite the many advantages associated with dried blood microsampling, quantitative analyses are also associated with some specific difficulties. Different methodological aspects of microsampling-based methods are discussed and applied to TDM of TKIs. We focus on sample preparation, analytics, internal standards, dilution of samples, external quality controls, dried blood spot specific validation parameters, stability and blood-to-plasma conversion methods. The various impacts of deviating hematocrit values on quantitative results are discussed in a separate section as this is a key issue and undoubtedly the most widely discussed issue in the analysis of dried blood microsamples. Lastly, the applicability and feasibility of performing TDM using microsamples in a real-life home-sampling context is discussed.

Systematic review and cost-effectiveness of pharmacokinetically guided sunitinib individualized treatment for patients with metastatic renal cell carcinoma

Background:

Sunitinib has a narrow therapeutic window, with considerable differences between patients. Dosing based on pharmacokinetics (PK) may help overcome some of those issues. This study aims to evaluate and compare the cost-effectiveness of PK-guided individualized treatment of sunitinib with its standard dose in patients with metastatic renal cell carcinoma (mRCC).

Methods:

A comprehensive literature search was performed, and relevant values were used to provide information for the decision analysis model. Utility data were derived from published studies, and costs were obtained from the perspective of payers in China and the United States. A Markov model was established to evaluate the associated costs and health outcomes for patients. The primary outputs of the model included lifetime costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratio (ICER). One-way and probability sensitivity analyses were conducted to evaluate the potential uncertainties of parameters.

Results:

Cost-effective analysis showed that the QALY of the PK-guided group increased by 0.83 compared with that in the standard dose group. From the perspective of both countries’ health systems, the cost of PK-guided dose was lower than that of standard dose. Hence, PK-guided treatment was the dominant strategy. One-way and probability sensitivity analyses confirmed the reliability of these results.

Conclusion:

On the basis of currently available data, PK-guided sunitinib treatment may be a safe, effective, and economical intervention for patients with mRCC.

Research Progress on Quantification Methods of Drug Concentration of Monoclonal Antibodies

Background:

With the development of monoclonal antibodies (mAbs) from the first generation of mice to the fourth generation of human origin, the efficacy and safety in the treatment of many diseases have been continuously improved. MAbs have been widely used in the treatment of cancer, chronic inflammatory diseases, and so on. However, the treatment response of mAbs varies greatly among individuals, and drug exposure may be affected by a variety of physiological and pathological factors, such as combined use of drugs and progression of disease. Therefore, studies tend to recommend therapeutic drug monitoring and individualized treatment strategies.

Objective:

In this paper, the commonly used methods of quantification of monoclonal antibodies were reviewed, especially liquid chromatography- mass spectrometry (LC-MS/MS) and enzyme-linked immunosorbent assay (ELISA), to provide technical support for therapeutic drug detection and individualize dosing for patients.

Conclusion:

For patients achieving mAbs treatment, it is necessary to carry out therapeutic drug monitoring and take it as a routine monitoring index. We recommend that for pharmaceutical laboratories in hospitals, establishing an appropriate assay formats, such as ELISA and LC-MS/MS is critical to determine drug concentration and antidrug antibody (ADA) for mAbs.

UPLC-MS/MS-Based Analysis of Trastuzumab in Plasma Samples: Application in Breast Cancer Patients Sample Monitoring

Trastuzumab is a target-based recombinant humanized IgG1 monoclonal antibody (mAbs), extensively employed for treatment of metastatic breast cancer with human epidermal growth receptor 2 (HER2) overexpression. Studies around the world have reported that mAbs have substantial inter-patient unpredictable absorption, distribution, metabolism, and excretion (ADME-pharmacokinetics) because of multiple elements manipulating the concentration of mAbs in plasma. Herein, we have established a bioanalytical technique using UPLC-MS/MS with an easy sample workup method and in-solution digestion protocol to assay the trastuzumab plasma samples from breast cancer patients in clinical studies. Surrogated proteolytic peptides were used for accurate quantification of trastuzumab (CanMab) with a trastuzumab signature peptide with [13C6, 15N4]-arginine and [13C6, 15N2]-lysine stable isotope-labeled (SIL) peptide. Experiments to validate the method were accurately carried out according to the guidelines mentioned in the bioanalytical method validation protocol. The evaluation established excellent linearity over a wide range of 5–500 µg/mL. The experimental procedure was efficaciously performed in a pilot study of five breast cancer patients and residual concentrations of drugs from responding and non-responding subjects were compared. The receiver operating characteristic (ROC) examination displayed that 52.25 µg/mL was the Cmin threshold predictive response with a satisfactory sensitivity of 88.58% and specificity of 79.25%.

Quantification of Venetoclax for Therapeutic Drug Monitoring in Chinese Acute Myeloid Leukemia Patients by a Validated UPLC-MS/MS Method

Venetoclax has emerged as a breakthrough for treatment of leukemia with a wide interindividual variability in pharmacokinetics. Herein, a rapid, sensitive, and reliable UPLC-MS/MS method for quantification of venetoclax in plasma was developed and validated. The method was operated in the multiple-reaction monitoring (MRM) mode to detect venetoclax at m/z transition 868.5 > 321.0 and IS at 875.5 > 321.0, respectively. Protein precipitation prior to injection into the LC-MS/MS and the analyte was separated on an ACQUITY UPLC BEH C18 column by gradient elution with acetonitrile and 0.1% formic acid in water. Linear calibration curves were obtained in the range of 25−8000 ng/mL. The specificity, recovery, matrix effect, and stability also met the acceptance criteria of FDA guidance. The method was successfully applied to analyze plasma in acute myeloid leukemia (AML) patients. The peak plasma concentration (Cmax) of venetoclax in Chinese AML patient was 2966.0 ± 1595.0 ng/mL while the trough concentration (Cmin) was 1018.0 ± 729.4 ng/mL. Additionally, Cmax and Cmin showed a positive correlation with AST levels. Furthermore, Cmax was significantly higher in the older patients. The present method can be applied for TDM of venetoclax in treatment of hematological cancers.

Oral targeted therapy dose adaptation in older patients with cancer: a real-life French cohort

INTRODUCTION

Oral targeted therapies (OTT) are widely used for cancer management. However, there is no consensus on OTT dose adaptation in older patients with cancer.

METHODS

This non-interventional, retrospective study was a real-life assessment of dose adaptation for six OTT (afatinib, everolimus, palbociclib, pazopanib, sorafenib, and sunitinib), at baseline and during treatment, with the reasons of such changes, in ≥70-year-old patients treated between 02/2016 and 08/2019. Data were compared with univariate models fitted with all variables.

RESULTS

Among the 986 patients treated with OTT, the group of ≥70-year-old patients (n=122) received afatinib (15.6%), everolimus (14.8%), palbociclib (50.8%), pazopanib (9.8%), sorafenib (5.8%), or sunitinib (3.2%). At baseline, the prescribed OTT dose was adapted (reduction) in 29% of ≥70-year-old patients (35/122). These 35 patients were significantly older (mean age: 80 vs 74 years, p <0.001), and had more frequently a performance status score ≥2 (p<0.01) than the other patients (n=87). In the standard dose group, higher toxicity grades (p=0.18) and subsequent dose reduction (41% of patients, 36/87) tended to be more frequent compared with the baseline adapted dose group (26%, 9/35, p=0.1). At the study end, 53% of patients of the whole cohort (65/122) were taking a lower dose than the recommended one.

CONCLUSION

At OTT initiation, dose was adapted in 29% of older adults with cancer, rarely after a formal oncogeriatric evaluation (6.5% of all patients). In the absence of recommendations, clinical studies are needed to evaluate the efficacy and safety of baseline OTT dose reduction in older adults with cancer.

Perspectives and Expertise in Establishing a Therapeutic Drug Monitoring Programme for Challenging Childhood Cancer Patient Populations

The utility of Therapeutic Drug Monitoring (TDM) in the setting of childhood cancer is a largely underused tool, despite the common use of cytotoxic chemotherapeutics. While it is encouraging that modern advances in chemotherapy have transformed outcomes for children diagnosed with cancer, this has come at the cost of an elevated risk of life-changing long-term morbidity and late effects. This concern can limit the intensity at which these drugs are used. Widely used chemotherapeutics exhibit marked inter-patient variability in drug exposures following standard dosing, with fine margins between exposures resulting in toxicity and those resulting in potentially suboptimal efficacy, thereby fulfilling criteria widely accepted as fundamental for TDM approaches. Over the past decade in the UK, the paediatric oncology community has increasingly embraced the potential benefits of utilising TDM for particularly challenging patient groups, including infants, anephric patients and those receiving high dose chemotherapy. This has been driven by a desire from paediatric oncologists to have access to clinical pharmacology information to support dosing decisions being made. This provides the potential to modify doses between treatment cycles based on a comprehensive set of clinical information, with individual patient drug exposures being used alongside clinical response and tolerability data to inform dosing for subsequent cycles. The current article provides an overview of recent experiences of conducting TDM in a childhood cancer setting, from the perspectives of the clinicians, scientists and pharmacists implementing TDM-based dosing recommendations. The ongoing programme of work has facilitated investigations into the validity of current approaches to dosing for some of the most challenging childhood cancer patient groups, with TDM approaches now being expanded from well-established cytotoxic drugs through to newer targeted treatments.

Dendrimer-Based Nanogels for Cancer Nanomedicine Applications

Recent advances in the field of nanotechnology bring an alternative approach to personalized medicine in cancer treatment. Nanogels (NGs) are among the nanosized superconstructs composed of amphiphilic or hydrophilic polymer networks. The design of different types of biodegradable polymer-based NGs in various biomedical applications has received extensive attention, due to their unique physicochemical properties such as highly porous structure, stimuli-responsiveness, and mimicking of some biological properties. In this review, we concisely surveyed the synthesis of dendrimer-based NGs synthesized via different methods including covalent conjugation, inverse nanoprecipitation, physical cross-linking, or self-assembly for various cancer nanomedicine applications, particularly for drug delivery, gene delivery, photothermal therapy, and combination therapy, as well as for biological imaging-guided chemotherapy. Additionally, we provide herein future perspective toward the new design of dendrimer-based NGs for different cancer nanomedicine uses.

Hypofractionated radiotherapy combined with targeted therapy or immunotherapy: Dutch survey on current practice, knowledge and challenges

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Radiotherapy referral during targeted therapy or immunotherapy occurs regularly.

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There is a knowledge gap regarding the implications of combined therapy.

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There is no consensus on expected toxicity of combined therapy.

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Multidisciplinary protocols regarding combined therapy are often not available.

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The application of radiotherapy treatment adaptations varies widely when combined with different systemic treatments.

Introduction

With the introduction of tyrosine kinase inhibitors and systemic antibodies, including immune checkpoint inhibitors, the survival of advanced-stage cancer patients has improved for many tumor types. These patients are increasingly referred for radiotherapy, but it is unclear whether radiotherapy combined with these drugs is safe. No international guidelines exist on whether or how to combine these drugs with radiotherapy. Therefore, we investigated the current clinical practice in the Netherlands regarding hypofractionated radiotherapy in patients using targeted drugs and immunotherapy.

Materials and methods

We sent a survey to all 21 Dutch radiotherapy institutes. Dedicated radiation oncologists, medical oncologists and pulmonologists were asked to fill out the survey. The questions explored their familiarity with the combination of targeted drugs and immunotherapy with radiotherapy, the encountered clinical difficulties and factors influencing treatment decisions.

Results

The survey was filled out by 54 respondents from 19 different institutes. The median annual number of patients per radiation oncologist referred for radiotherapy when using targeted drugs or immunotherapy was 10 and 15, respectively. Despite this high number, only 11% of the radiation oncologists stated that they had sufficient information (resources) for adequate treatment decision making. Among all physicians, 44% stated that there was insufficient knowledge within their institute regarding this topic. Only 17% stated that there was a multidisciplinary protocol available. The application of radiotherapy treatment adaptations (technique, dose, fractionation, field size) varied widely. Generally, there seemed to be no consensus regarding the expected toxicity of combined drug-radiotherapy treatments and the expected risk of tumor flare upon temporary drug discontinuation.

Conclusion

There is no consensus amongst involved medical specialties on expected toxicity. Consequently, it is necessary to perform clinical studies examining the safety of combined drug-radiotherapy treatments, to add radiotherapy to phase I-III clinical trials for new drugs and to incorporate outcomes into multidisciplinary, evidence-based guidelines.

Therapeutic Drug Monitoring of Protein Kinase Inhibitors in Breast Cancer Patients

Protein kinase inhibitors (PKIs) represent up-to-date therapeutic approach in breast cancer treatment. Although cancer is a rapidly progressive disease, many substances, including PKIs, are usually used at fixed doses without regard to each patient's individuality. Therapeutic drug monitoring (TDM) is a tool that allows individualization of therapy based on drug plasma levels. For TDM conduct, exposure-response relationships of drug substances are required. The pharmacokinetic data and exposure-response evidence supporting the use of TDM for 6 PKIs used in breast cancer treatment, one of the most common female tumour diseases, are discussed in this review.

Pharmacogenomics in solid cancers and hematologic malignancies: Improving personalized drug prescription

The discovery of molecular alterations involved in oncogenesis is evolving rapidly and has led to the development of new innovative targeted therapies in oncology. High-throughput sequencing techniques help to identify genomic targets and to provide predictive molecular biomarkers of response to guide alternative therapeutic strategies. Besides the emergence of these theranostic markers for the new targeted treatments, pharmacogenetic markers (corresponding to genetic variants existing in the constitutional DNA, i.e., the host genome) can help to optimize the use of chemotherapy. In this review, we present the current clinical applications of constitutional PG and the recent concepts and advances in pharmacogenomics, a rapidly evolving field that focuses on various molecular alterations identified on constitutional or somatic (tumor) genome.

Utility, promise, and limitations of liquid chromatography-mass spectrometry-based therapeutic drug monitoring in precision medicine

Therapeutic drug monitoring (TDM) is typically referred to as the measurement of the concentration of drugs in patient blood. Although in the past, TDM was restricted to drugs with a narrow therapeutic range in order to avoid drug toxicity, TDM has recently become a major tool for precision medicine being applied to many more drugs. Through compensating for interindividual differences in a drug's pharmacokinetics, improved dosing of individual patients based on TDM ensures maximum drug effectiveness while minimizing side effects. This is especially relevant for individuals that present a particularly high intervariability in pharmacokinetics, such as newborns, or for critically/severely ill patients. In this article, we will review the applications for and limitations of TDM, discuss for which patients TDM is most beneficial and why, examine which techniques are being used for TDM, and demonstrate how mass spectrometry is increasingly becoming a reliable and convenient alternative for the TDM of different classes of drugs. We will also highlight the advances, challenges, and limitations of the existing repertoire of TDM methods and discuss future opportunities for TDM-based precision medicine.

A framework for economic evaluation of therapeutic drug monitoring-guided dosing in oncology

The standard approach for dose individualization of chemotherapy in the oncology setting has long been based on body surface area (BSA) as a measure of body size. However, for many anticancer drugs, administration of dosages based on BSA may result in some patients receiving supratherapeutic or subtherapeutic concentrations due to substantial interindividual pharmacokinetic variability. Therapeutic drug monitoring (TDM)-guided dosing aims to ensure that the patient's serum drug concentration is in a target range which has been shown to produce optimal clinical outcomes. The management of several malignancies is now moving away from using traditional intravenous chemotherapy to longer-term treatment with targeted molecular therapies. These targeted anticancer drugs are currently dosed based on a fixed dose for all patients. The pharmacokinetic characteristics of most of these drugs (e.g., tyrosine-kinase inhibitors) support implementation of individualized dosing via TDM. However, prior to adopting TDM-guided dosing in oncology settings, the economic efficiency and value for money of introducing TDM interventions should be critically and systematically examined along with the impacts on patient care and outcomes. Yet, current evidence in this area is limited, and more generally, there is lack of methodological guidance on how to identify, estimate and value clinical and cost information necessary to conduct economic evaluations of TDM interventions. In this paper, we propose a coherent framework for conducting economic evaluation of TDM interventions in oncology settings and discuss some practical challenges of conducting economic evaluations of TDM.

Assessment of exposure-response relationship for bevacizumab in patients with metastatic colorectal cancer

Limited literature is available for bevacizumab exposure-response relationship and there is not a concentration threshold associated with an optimal disease control. This prospective observational study in patients with metastatic colorectal cancer (mCRC) aims to evaluate, in a real-life setting, the relationship between bevacizumab through concentrations at steady state (C_{trough, SS}) and disease control. C_{trough, SS} were drawn, coinciding with the radiological evaluation of the response (progression or clinical benefit). Generalized estimating equations (GEE) analysis was performed. To test the association between C_{trough, SS} in each patient with overall survival (OS) or progression-free survival (PFS), Cox proportional hazard models were developed. Data included 50 bevacizumab C_{trough, SS} from 27 patients. The GEE model did not suggest any positive association between bevacizumab C_{trough, SS} and clinical benefit (OR 0.99, 95% CI: 0.98-1.02, p = 0.863). The Cox regression showed association between higher median C_{trough, SS} with better OS (HR 0.86, 95% CI: 0.73-1.01, p = 0.060), but not with PFS. We cannot confirm a relationship between bevacizumab C_{trough, SS} and clinical benefit but this is the first real-world study trying to show a relationship between bevacizumab C_{trough, SS} and disease control in mCRC. It was conducted in a small sample size which reduces the level of evidence. Further controlled randomized studies with a sufficient number of patients are required.

Pharmacokinetically guided dosing of oral sorafenib in pediatric hepatocellular carcinoma: A simulation study

Sorafenib improves outcomes in adult hepatocellular carcinoma; however, hand foot skin reaction (HFSR) is a dose limiting toxicity of sorafenib that limits its use. HFSR has been associated with sorafenib systemic exposure. The objective of this study was to use modeling and simulation to determine whether using pharmacokinetically guided dosing to achieve a predefined sorafenib target range could reduce the rate of HFSR. Sorafenib steady‐state exposures (area under the concentration curve from 0 to 12‐h [AUC_0–>12 h]) were simulated using published sorafenib pharmacokinetics at either a fixed dosage (90 mg/m²/dose) or a pharmacokinetically guided dose targeting an AUC_0–>12 h between 20 and 55 h µg/ml. Dosages were either rounded to the nearest quarter of a tablet (50 mg) or capsule (10 mg). A Cox proportional hazard model from a previously published study was used to quantify HFSR toxicity. Simulations showed that in‐target studies increased from 50% using fixed doses with tablets to 74% using pharmacokinetically guided dosing with capsules. The power to observe at least 4 of 6 patients in the target range increased from 33% using fixed dosing with tablets to 80% using pharmacokinetically guided with capsules. The expected HFSR toxicity rate decreased from 22% using fixed doses with tablets to 16% using pharmacokinetically guided dosing with capsules. The power to observe less than 6 of 24 studies with HFSR toxicity increased from 51% using fixed dosing with tablets to 88% using pharmacokinetically guided with capsules. Our simulations provide the rationale to use pharmacokinetically guided sorafenib dosing to maintain effective exposures that potentially improve tolerability in pediatric clinical trials.

Clinical-Based vs. Model-Based Adaptive Dosing Strategy: Retrospective Comparison in Real-World mRCC Patients Treated with Sunitinib

Different target exposures with sunitinib have been proposed in metastatic renal cell carcinoma (mRCC) patients, such as trough concentrations or AUCs. However, most of the time, rather than therapeutic drug monitoring (TDM), clinical evidence is preferred to tailor dosing, i.e., by reducing the dose when treatment-related toxicities show, or increasing dosing if no signs of efficacy are observed. Here, we compared such empirical dose adjustment of sunitinib in mRCC patients, with the parallel dosing proposals of a PK/PD model with TDM support. In 31 evaluable patients treated with sunitinib, 53.8% had an empirical change in dosing after treatment started (i.e., 46.2% decrease in dosing, 7.6% increase in dosing). Clinical benefit was observed in 54.1% patients, including 8.3% with complete response. Overall, 58.1% of patients experienced treatment discontinuation eventually, either because of toxicities or progressive disease. When choosing 50-100 ng/mL trough concentrations as a target exposure (i.e., sunitinib + active metabolite N-desethyl sunitinib), 45% patients were adequately exposed. When considering 1200-2150 ng/mL.h as a target AUC (i.e., sunitinib + active metabolite N-desethyl sunitinib), only 26% patients were in the desired therapeutic window. TDM with retrospective PK/PD modeling would have suggested decreasing sunitinib dosing in a much larger number of patients as compared with empirical dose adjustment. Indeed, when using target trough concentrations, the model proposed reducing dosing for 61% patients, and up to 84% patients based upon target AUC. Conversely, the model proposed increasing dosing in 9.7% of patients when using target trough concentrations and in 6.5% patients when using target AUC. Overall, TDM with adaptive dosing would have led to tailoring sunitinib dosing in a larger number of patients (i.e., 53.8% vs. 71-91%, depending on the chosen metrics for target exposure) than a clinical-based decision. Interestingly, sunitinib dosing was empirically reduced in 41% patients who displayed early-onset severe toxicities, whereas model-based recommendations would have immediately proposed to reduce dosing in more than 80% of those patients. This observation suggests that early treatment-related toxicities could have been partly avoided using prospective PK/PD modeling with adaptive dosing. Conversely, the possible impact of model-based adapted dosing on efficacy could not be fully evaluated because no clear relationship was found between baseline exposure levels and sunitinib efficacy measured at 3 months.

Exploratory analysis of target concentration of lenvatinib in the treatment of hepatocellular carcinoma

PURPOSE

We aimed to evaluate exposure-toxicity/efficacy relationship of lenvatinib by determining its target trough concentration for patients with hepatocellular carcinoma (HCC).

METHODS

In this retrospective, observational study, 28 HCC patients who had been treated with lenvatinib were enrolled between August 2018 and April 2020. We evaluated the association between the trough lenvatinib concentration and occurrence of grade ≥ 3 toxicities. Additionally, we estimated the association of the trough lenvatinib concentration with responder status (disease control; complete response, partial response, or stable disease), and progression-free survival (PFS).

RESULTS

The mean trough lenvatinib concentration was significantly higher in the group with grade ≥ 3 toxicity (n = 15) than in the group with grade ≤ 2 toxicity (n = 13). Based on the receiver operating characteristic curve, the threshold values of the trough lenvatinib concentrations for predicting grade ≥ 3 toxicities and responder status were 71.4 ng/mL [area under the curve (AUC) 0.86, 95% confidence interval (CI) 0.71-1.00; p < 0.05] and 36.8 ng/mL (AUC 0.95, 95% CI 0.85-1.00; p < 0.05), respectively. Lenvatinib concentrations of 36.8-71.4 ng/mL resulted in longer PFS than concentrations < 36.8 ng/mL and ≥ 71.4 ng /mL [median 13.3 months (36.8-71.4 ng/mL) vs. 3.5 months (< 36.8 ng/mL) and 7.8 months (≥ 71.4 ng /mL), respectively].

CONCLUSIONS

Considering these results, we propose that the target trough concentration of lenvatinib could be 36.8-71.4 ng/mL for maintaining disease control status and reducing grade ≥ 3 toxicity in the treatment of HCC.

Therapeutic Drug Monitoring of Sunitinib in Gastrointestinal Stromal Tumors and Metastatic Renal Cell Carcinoma in Adults-A Review

BACKGROUND

Sunitinib is an inhibitor of multiple receptor tyrosine kinases and is a standard-of-care treatment for advanced and metastatic renal cell carcinoma and a second-line treatment in locally advanced inoperable and metastatic gastrointestinal stromal tumors. A fixed dose of the drug, however, does not produce a uniform therapeutic outcome in all patients, and many face adverse effects and/or toxicity. One of the possible causes of the interindividual variability in the efficacy and toxicity response is the highly variable systemic exposure to sunitinib and its active metabolite. This review aims to summarize all available clinical evidence of the treatment of adult patients using sunitinib in approved indications, addressing the necessity to introduce proper and robust therapeutic drug monitoring (TDM) of sunitinib and its major metabolite, N-desethylsunitinib.

METHODS

The authors performed a systematic search of the available scientific literature using the PubMed online database. The search terms were "sunitinib" AND "therapeutic drug monitoring" OR "TDM" OR "plasma levels" OR "concentration" OR "exposure." The search yielded 520 journal articles. In total, 447 publications were excluded because they lacked sufficient relevance to the reviewed topic. The remaining 73 articles were, together with currently valid guidelines, thoroughly reviewed.

RESULTS

There is sufficient evidence confirming the concentration-efficacy and concentration-toxicity relationship in the indications of gastrointestinal stromal tumors and metastatic renal clear-cell carcinoma. For optimal therapeutic response, total (sunitinib + N-desethylsunitinib) trough levels of 50-100 ng/mL serve as a reasonable target therapeutic range. To avoid toxicity, the total trough levels should not exceed 100 ng/mL.

CONCLUSIONS

According to the current evidence presented in this review, a TDM-guided dose modification of sunitinib in selected groups of patients could provide a better treatment outcome while simultaneously preventing sunitinib toxicity.

High-throughput liquid chromatography/electrospray ionization-tandem mass spectrometry method using in-source collision-induced dissociation for simultaneous quantification of imatinib, dasatinib, bosutinib, nilotinib, and ibrutinib in human plasma

Recent studies have shown that therapeutic drug monitoring of tyrosine kinase inhibitors (TKIs) could improve treatment efficacy and safety. A simple analytical method using high-performance LC/electrospray ionization-tandem mass spectrometry has been developed and validated for simultaneous quantification of BCR-ABL and Bruton's TKIs used for chronic leukemia (imatinib, dasatinib, bosutinib, nilotinib, and ibrutinib) in human plasma. Although these structures and physical properties are similar, owing to their different linear ranges, simultaneously determining the plasma levels of these five TKIs by applying optimal MS parameters remains difficult. A quantitative range exceeding 60,000-fold was required, and the linear dynamic ranges of imatinib, bosutinib, and nilotinib were limited because of the presence of a saturated detection signal. In this study, we applied the in-source collision-induced dissociation technique to control the ion amounts in mass spectrometry. This new method allowed rapid determination within 5 min with simple pretreatment. The method was validated according to the US Food and Drug Administration guidelines. Moreover, all samples of patients with chronic leukemia were successfully measured and their values were within the linear range of measurement. Therefore, our high-throughput analytical system is useful to measure the plasma concentrations of imatinib, dasatinib, bosutinib, nilotinib, and ibrutinib in clinical practice.

Dried Blood Spot Technique Applied in Therapeutic Drug Monitoring of Anticancer Drugs: a Review on Conversion Methods to Correlate Plasma and Dried Blood Spot Concentrations

BACKGROUND

Anticancer drugs are notoriously characterized by a low therapeutic index, the introduction of therapeutic drug monitoring (TDM) in oncologic clinical practice could therefore be fundamental to improve treatment efficacy. In this context, an attractive technique to overcome the conventional venous sampling limits and simplify TDM application is represented by dried blood spot (DBS). Despite the significant progress made in bioanalysis exploiting DBS, there is still the need to tackle some challenges that limit the application of this technology: one of the main issues is the comparison of drug concentrations obtained from DBS with those obtained from reference matrix (e.g., plasma). In fact, the use of DBS assays to estimate plasma concentrations is highly dependent on the chemical-physical characteristics of the measured analyte, in particular on how these properties determine the drug partition in whole blood.

METHODS

In the present review, we introduce a critical investigation of the DBS-to-plasma concentration conversion methods proposed in the last ten years and applied to quantitative bioanalysis of anticancer drugs in DBS matrix. To prove the concordance between DBS and plasma concentration, the results of statistical tests applied and the presence or absence of trends or biases were also considered.

Therapeutic drug monitoring of oral targeted antineoplastic drugs

PURPOSE

This review provides an overview of the current challenges in oral targeted antineoplastic drug (OAD) dosing and outlines the unexploited value of therapeutic drug monitoring (TDM). Factors influencing the pharmacokinetic exposure in OAD therapy are depicted together with an overview of different TDM approaches. Finally, current evidence for TDM for all approved OADs is reviewed.

METHODS

A comprehensive literature search (covering literature published until April 2020), including primary and secondary scientific literature on pharmacokinetics and dose individualisation strategies for OADs, together with US FDA Clinical Pharmacology and Biopharmaceutics Reviews and the Committee for Medicinal Products for Human Use European Public Assessment Reports was conducted.

RESULTS

OADs are highly potent drugs, which have substantially changed treatment options for cancer patients. Nevertheless, high pharmacokinetic variability and low treatment adherence are risk factors for treatment failure. TDM is a powerful tool to individualise drug dosing, ensure drug concentrations within the therapeutic window and increase treatment success rates. After reviewing the literature for 71 approved OADs, we show that exposure-response and/or exposure-toxicity relationships have been established for the majority. Moreover, TDM has been proven to be feasible for individualised dosing of abiraterone, everolimus, imatinib, pazopanib, sunitinib and tamoxifen in prospective studies. There is a lack of experience in how to best implement TDM as part of clinical routine in OAD cancer therapy.

CONCLUSION

Sub-therapeutic concentrations and severe adverse events are current challenges in OAD treatment, which can both be addressed by the application of TDM-guided dosing, ensuring concentrations within the therapeutic window.

Individualized Management of Blood Concentration in Patients with Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor, and surgical resection is the first choice for the treatment of the disease, but since the advent of tyrosine kinase inhibitors (TKIs) such as imatinib (IM), the prognosis of the disease has undergone revolutionary changes. According to the current version of the guidelines, most GIST patients receive a fixed dose without taking into account their own individual differences, resulting in a wide difference in blood concentration, adverse reactions and prognosis. With more studies on the relationship between blood drug concentrations and prognosis, the concept of individualized therapy has been paid more attention by researchers. Therapeutic drug monitoring (TDM) has also been made available for the research field of GIST targeted therapy. How to reduce the incidence of drug resistance and adverse reactions in patients with GISTs has become the focus of the current research. This article reviews the common monitoring methods and timing of TKIs blood concentration, the reasonable range of blood drug concentration, the toxic or adverse effects caused by high blood drug concentration, some possible factors affecting blood drug concentration and recent research progress, in order to discuss and summarize the treatment strategy of individual blood drug concentration, improve the prognosis of patients and reduce the adverse effects as much as possible.

Drug dosing in cancer patients with decreased kidney function: A practical approach

Correct drug dosing of anticancer agents is essential to obtain optimal outcomes. Overdosing will result in increased toxicity, treatment interruption and possible cessation of anticancer treatment. Underdosing may result in suboptimal anti-cancer effects and may increase the risk of cancer-related mortality. As it is practical nor feasible to perform therapeutic drug monitoring for all anti-cancer drugs, kidney function is used to guide drug dosing for those drugs whose primary mode of excretion is through the kidney. However, it is not well-established what method should be utilized to measure or estimate kidney function and the choice of method does influence treatment decisions regarding eligibility for anti-cancer drugs and their dose. In this review, we will provide an overview regarding the importance of drug dosing, the preferred method to determine kidney function and a practical approach to drug dosing of anticancer drugs.

Neratinib-Plus-Cetuximab in Quadruple-WT (KRAS, NRAS, BRAF, PIK3CA) Metastatic Colorectal Cancer Resistant to Cetuximab or Panitumumab: NSABP FC-7, A Phase Ib Study

PURPOSE

In metastatic colorectal cancer (mCRC), HER2 (ERBB2) gene amplification is implicated in anti-EGFR therapy resistance. We sought to determine the recommended phase II dose (RP2D) and efficacy of neratinib, a pan-ERBB kinase inhibitor, combined with cetuximab, in patients with progressive disease (PD) on anti-EGFR treatment.

PATIENTS AND METHODS

Twenty-one patients with quadruple-wild-type, refractory mCRC enrolled in this 3+3 phase Ib study. Standard dosage cetuximab was administered with neratinib at 120 mg, 160 mg, 200 mg, and 240 mg/day orally in 28-day cycles. Samples were collected for molecular and pharmacokinetic studies.

RESULTS

Sixteen patients were evaluable for dose-limiting toxicity (DLT). 240 mg was determined to be the RP2D wherein a single DLT occurred (1/7 patients). Treatment-related DLTs were not seen at lower doses. Best response was stable disease (SD) in 7 of 16 (44%) patients. HER2 amplification (chromogenic in situ IHC) was detected in 2 of 21 (9.5%) treatment-naïve tumors and 4 of 16 (25%) biopsies upon trial enrollment (post-anti-EGFR treatment and progression). Compared with matched enrollment biopsies, 6 of 8 (75%) blood samples showed concordance for HER2 CNV in circulating cell-free DNA. Five SD patients had HER2 amplification in either treatment-naïve or enrollment biopsies. Examination of gene-expression, total protein, and protein phosphorylation levels showed relative upregulation of ≥2 members of the HER-family receptors or ligands upon enrollment versus matched treatment-naïve samples.

CONCLUSIONS

The RP2D of neratinib in this combination was 240 mg/day, which was well tolerated with low incidence of G3 AEs. There were no objective responses; SD was seen at all neratinib doses. HER2 amplification, detectable in both tissue and blood, was more frequent post-anti-EGFR therapy.

Cancer Immunotherapy Dosing: A Pharmacokinetic/Pharmacodynamic Perspective

Immune check-point inhibitors are drugs that are markedly different from other anticancer drugs because of their indirect mechanisms of antitumoral action and their apparently random effect in terms of efficacy and toxicity. This marked pharmacodynamics variability in patients calls for reconsidering to what extent approved dosing used in clinical practice are optimal or whether they should require efforts for customization in outlier patients. To better understand whether or not dosing could be an actionable item in oncology, in this review, preclinical and clinical development of immune checkpoint inhibitors are described, particularly from the angle of dose finding studies. Other issues in connection with dosing issues are developed, such as the flat dosing alternative, the putative role therapeutic drug monitoring could play, the rise of combinatorial strategies, and pharmaco-economic aspects.

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.

Pharmacogenomics, Pharmacokinetics and Circulating Proteins as Biomarkers for Bevacizumab Treatment Optimization in Patients with Cancer: A Review

Bevacizumab is a monoclonal antibody that targets VEGF-A and inhibits tumor angiogenesis. Bevacizumab is approved for the treatment of various cancer, including metastatic colorectal cancer (mCRC), ovarian cancer, lung cancer, and others. Thus, it is widely used in oncology, but contrary to other therapeutic classes, there is still a lack of validating predictive factors for treatment outcomes with these agents. In recent years, the research for factors predictive of anti-VEGF treatments and especially bevacizumab response has been one of the most competitive translational research fields. Herein, we review and present the available literature of the clinical use of biomarkers, pharmacogenomics (PG), and therapeutic drug monitoring (TDM) approaches that can be used for the optimization of bevacizumab use in the era of precision medicine.

Relationship between trough level of tyrosine kinase inhibitor (imatinib and nilotinib) and BCR-ABL ratios in an Indonesian chronic-phase chronic myeloid leukemia (CML) population

Objectives Among Chronic Myeloid Leukemia (CML) patients treated with Tyrosine Kinase Inhibitor (TKI-imatinib-nilotinib), some showed a suboptimal response. Based on pharmacokinetic studies, TKI trough level ( C m i n ∞ ${C}_{min}\hat{\infty }$ ) is associated with clinical outcomes, reflected by the BCR-ABL ratio. However, the interindividual pharmacokinetic variability of imatinib and nilotinib is found to be moderate-high. This study aims to analyze the relationship between TKI C m i n ∞   ${C}_{min}\hat{\infty }$ and BCL-ABL ratio in chronic-phase CML patients. Methods Cross-sectional study to CML chronic-phase patients treated with imatinib 400 mg daily or nilotinib 400 or 800 mg daily for ≥12 months. The exclusion criteria were therapy discontinuation within 29 days (imatinib) or 8 days (nilotinib) before the sampling day. Blood samples were drawn 1 h before the next dose. Imatinib-nilotinib C m i n ∞ ${C}_{min}\hat{\infty }$ and BCR-ABL ratio were measured using HPLC and RT-qPCR. The relationship was analyzed using bivariate correlation Spearman's rho test. Results Twenty-three imatinib and 11 nilotinib patients met the inclusion criteria. The mean imatinib and nilotinib C m i n ∞ ${C}_{min}\hat{\infty }$ were 1,065.46 ± 765.71 and 1,445 ± 1,010.35 ng/mL respectively. There were large interindividual variations in both groups (71.87% vs. 69.88%). Half of the patients in each group were found to reach C m i n ∞ ${C}_{min}\hat{\infty }$ target (≥1.000 ng/mL, imatinib; ≥800 ng/mL nilotinib), but only 12 (35,29%) of them result in BCR-ABL ratio ≤0.1%. C m i n ∞   ${C}_{min}\hat{\infty }$ imatinib was found to be significantly associated with BCR-ABL ratio. But, not with the nilotinib group. Conclusions There were high interindividual variations of imatinib and nilotinib correlated with BCR-ABL ratio, but no correlation in nilotinib.

Nuances to precision dosing strategies of targeted cancer medicines

Selecting the dose of a targeted cancer medicine that is most appropriate for a specific individual is a rational approach to maximize therapeutic outcomes and minimize toxicity. There are many different options for optimizing the dose of targeted cancer medicines and the purpose of this review is to provide a comprehensive comparison of the main options explored in prospective studies. Precision initial dose selection of targeted cancer therapies has been minimally explored to date; however, concentration, toxicity, and therapeutic outcome markers are used to guide on-therapy dose adaption of targeted cancer therapies across several medicines and cancers. While a specific concentration, toxicity, or therapeutic outcome marker commonly dominates an investigated precision on-therapy dose adaption strategy, greater attention to simultaneously account for exposure, toxicity, therapeutic outcomes, disease status, time since treatment initiation and patient preferences are required for optimal patient outcomes. To enable successful implementation of precision dosing strategies for targeted cancer medicines into clinical practice, future prospective studies aiming to develop strategies should consider these elements in their design.

Emerging insights on drug delivery by fatty acid mediated synthesis of lipophilic prodrugs as novel nanomedicines

Many drug molecules that are currently in the market suffer from short half-life, poor absorption, low specificity, rapid degradation, and resistance development. The design and development of lipophilic prodrugs can provide numerous benefits to overcome these challenges. Fatty acids (FAs), which are lipophilic biomolecules constituted of essential components of the living cells, carry out many necessary functions required for the development of efficient prodrugs. Chemical conjugation of FAs to drug molecules may change their pharmacodynamics/pharmacokinetics in vivo and even their toxicity profile. Well-designed FA-based prodrugs can also present other benefits, such as improved oral bioavailability, promoted tumor targeting efficiency, controlled drug release, and enhanced cellular penetration, leading to improved therapeutic efficacy. In this review, we discuss diverse drug molecules conjugated to various unsaturated FAs. Furthermore, various drug-FA conjugates loaded into various nanostructure delivery systems, including liposomes, solid lipid nanoparticles, emulsions, nano-assemblies, micelles, and polymeric nanoparticles, are reviewed. The present review aims to inspire readers to explore new avenues in prodrug design based on the various FAs with or without nanostructured delivery systems.

Correlation Between Bevacizumab Exposure and Survival in Patients with Metastatic Colorectal Cancer

BACKGROUND

Bevacizumab treatment is subject to large interpatient variability in efficacy, which may partly be explained by differences in complex bevacizumab pharmacokinetic characteristics that influence bevacizumab exposure. Exposure-response relationships have been identified for other monoclonal antibodies. We aimed to identify possible exposure-survival relationships in bevacizumab-treated patients with metastatic colorectal cancer (mCRC).

MATERIALS AND METHODS

Patients with mCRC who started first-line bevacizumab-based chemotherapy between July 2012 and July 2014, and from whom serial blood samples and survival were prospectively collected, were included. Follow-up was carried out until July 2018. Total bevacizumab trough concentrations were measured from cycle 2 to cycle 30 of treatment. The receiver operating characteristic (ROC) curve analysis and Cox analysis were used to identify the relationship between concentrations and overall survival (OS). In addition, OS was compared between different trough concentration groups.

RESULTS

One hundred fifty-seven blood samples from 46 patients were evaluable for analyses. ROC analysis showed a clear separation in survival based on trough levels (area under the curve = 0.739, p = .009). Cox regression also showed a strong positive correlation between trough levels and survival (p = .0004). Three distinct groups of exposure were identified: low (median trough concentration [C_tm ] ≤41.9 mg/L); medium (C_tm 43-87.2 mg/L) with median OS of 12.8 and 36 months, respectively (p = .0003); and high (C_tm ≥7.9 mg/L), where the majority of patients were still alive 60 months after the initiation of treatment.

CONCLUSION

This study shows that survival was proportional to the magnitude of exposure in patients with mCRC. Further clinical research should focus on clarifying these exposure-outcome relationships in order to optimize dosing.

IMPLICATIONS FOR PRACTICE

Bevacizumab-based chemotherapy is standard first-line treatment in metastatic colorectal cancer. Moreover, bevacizumab presents complicated pharmacokinetics, and in many cases, clinical outcomes can be highly variable, with some patients responding remarkably well and others not. This study's results show that patients who experienced longer overall survival also had significantly higher exposure to bevacizumab. Therefore, bevacizumab trough concentrations could be used both as a predictive biomarker and as a tool for treatment monitoring and optimization. Finally, the development of validated, rapid, and sensitive assays for bevacizumab concentration measurements in combination with these results may lead to a therapeutic drug monitoring-guided approach in bevacizumab treatment with better clinical outcomes.

Higher Systemic Exposure to Unbound Active Metabolites of Regorafenib Is Associated With Short Progression-Free Survival in Colorectal Cancer Patients

Regorafenib treatment improves survival of patients with metastatic colorectal cancer, but it is also characterized by detrimental side effects that may require modified dosing or interval schedules. Regorafenib is metabolized by cytochrome P450 3A4 in the liver to its active metabolites, M-2 and M-5. We examined area under the unbound plasma concentration-time curve (AUCu) to these compounds to establish pharmacokinetic bases for individualized dosing strategies. The plasma protein binding of M-2 and M-5 was approximately 10-fold lower than that of regorafenib, whereas AUCu values for active metabolites on both days 1 and 15 were significantly higher than that of regorafenib. Patients with higher AUCu values of M-2 or M-5 on day 1 showed significantly shorter progression-free survival than others, likely due, at least in part, to treatment discontinuation as a result of adverse events, especially occurred during first cycle.