Quantification of eight hematological tyrosine kinase inhibitors in both plasma and whole blood by a validated LC-MS/MS method

Simultaneous Determination of Ibrutinib, Dihydroxydiol Ibrutinib, and Zanubrutinib in Human Plasma by Liquid Chromatography-Mass Spectrometry/Mass Spectrometry

BACKGROUND

Ibrutinib and zanubrutinib are Bruton tyrosine kinase inhibitors used to treat mantle cell lymphoma, chronic lymphocytic leukemia, and small lymphocytic lymphoma. Dihydroxydiol ibrutinib (DHI) is an active metabolite of the drug. A liquid chromatography-tandem mass spectrometry method was developed to detect ibrutinib, DHI, and zanubrutinib in human plasma.

METHODS

The method involved a protein precipitation step, followed by chromatographic separation using a gradient of 10 mM ammonium acetate (containing 0.1% formic acid)-acetonitrile. Ibrutinib-d5 was used as an internal standard. Analytes were separated within 6.5 minutes. The optimized multiple reaction monitoring transitions of m/z 441.1 → 304.2, 475.2 → 304.2, 472.2 → 455.2, and 446.2 → 309.2 were selected to inspect ibrutinib, DHI, zanubrutinib, and the internal standards in positive ion mode.

RESULTS

The validated curve ranges included 0.200-800, 0.500-500, and 1.00-1000 ng/mL for ibrutinib, DHI, and zanubrutinib, respectively. The precisions of the lower limit of quantification of samples were below 15.5%, the precisions of the other level samples were below 11.4%, and the accuracies were between -8.6% and 8.4%. The matrix effect and extraction recovery of all compounds ranged between 97.6%-109.0% and 93.9%-105.2%, respectively. The selectivity, accuracy, precision, matrix effect, and extraction recovery results were acceptable according to international method validation guidelines.

CONCLUSIONS

A simple and rapid method was developed and validated in this study. This method was used to analyze plasma concentrations of ibrutinib and zanubrutinib in patients with mantle cell lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma, or diffuse large B-cell lymphoma. The selected patients were aged between 44 and 74 years.

A Validated Assay to Quantify Osimertinib and Its Metabolites, AZ5104 and AZ7550, from Microsampled Dried Blood Spots and Plasma

BACKGROUND

Osimertinib is an oral small-molecule tyrosine kinase receptor inhibitor used to treat non-small cell lung cancer (NSCLC) with a sensitizing epidermal growth factor receptor mutation. Patients may experience drug toxicity and require dose deescalation. The study aimed to quantitate osimertinib and its 2 active metabolites, AZ5104 and AZ7550, in microsampled dried blood spots (DBS) collected from patients with NSCLC using a hemaPEN device and compare them with plasma drug levels.

METHODS

A 6-min ultrahigh-performance liquid chromatography-tandem mass spectrometry method was developed and validated using plasma and DBS. The accuracy, selectivity, matrix effect, recovery, and stability were assessed using bioanalytical validation criteria. The hematocrit effect was investigated in DBS. Drug levels were measured in 15 patients with NSCLC, and the Bland-Altman method was used to compare measurements between plasma and DBS.

RESULTS

The validated assay determined accurate and precise quantities, respectively, for osimertinib in both plasma (93.2%-99.3%; 0.2%-2.3%) and DBS (96.7%-99.6%; 0.5%-10.3%) over a concentration of 1-729 ng/mL. The osimertinib metabolites, AZ5104 and AZ7550, were similarly validated in accordance with bioanalytical guidelines. For 30%-60% patient hematocrit, no hematocrit bias was observed with DBS for all analytes. The Bland-Altman method showed high concordance between plasma and DBS analyte levels. Stability experiments revealed that osimertinib and its metabolites were poorly stable in plasma at room temperature, whereas all analytes were stable in DBS for 10 days at room temperature.

CONCLUSIONS

The measurement of osimertinib, AZ5104, and AZ7550 from hemaPEN microsampled DBS is a convenient and reliable approach for therapeutic drug monitoring that produces measurements consistent with plasma drug levels.

Pretreatment and analysis techniques development of TKIs in biological samples for pharmacokinetic studies and therapeutic drug monitoring

Tyrosine kinase inhibitors (TKIs) have emerged as the first-line small molecule drugs in many cancer therapies, exerting their effects by impeding aberrant cell growth and proliferation through the modulation of tyrosine kinase-mediated signaling pathways. However, there exists a substantial inter-individual variability in the concentrations of certain TKIs and their metabolites, which may render patients with compromised immune function susceptible to diverse infections despite receiving theoretically efficacious anticancer treatments, alongside other potential side effects or adverse reactions. Therefore, an urgent need exists for an up-to-date review concerning the biological matrices relevant to bioanalysis and the sampling methods, clinical pharmacokinetics, and therapeutic drug monitoring of different TKIs. This paper provides a comprehensive overview of the advancements in pretreatment methods, such as protein precipitation (PPT), liquid-liquid extraction (LLE), solid-phase extraction (SPE), micro-SPE (μ-SPE), magnetic SPE (MSPE), and vortex-assisted dispersive SPE (VA-DSPE) achieved since 2017. It also highlights the latest analysis techniques such as newly developed high performance liquid chromatography (HPLC) and high-resolution mass spectrometry (HRMS) methods, capillary electrophoresis (CE), gas chromatography (GC), supercritical fluid chromatography (SFC) procedures, surface plasmon resonance (SPR) assays as well as novel nanoprobes-based biosensing techniques. In addition, a comparison is made between the advantages and disadvantages of different approaches while presenting critical challenges and prospects in pharmacokinetic studies and therapeutic drug monitoring.

Quantification of midostaurin in plasma and serum by stable isotope dilution liquid chromatography-tandem mass spectrometry: Application to a cohort of patients with acute myeloid leukemia

OBJECTIVES

Midostaurin is an oral multitargeted tyrosine kinase inhibitor for the treatment of acute myeloid leukemia (AML). Therapeutic drug monitoring of midostaurin may support its safe use when suspecting toxicity or combined with strong CYP3A4 inhibitors.

METHODS

A stable isotope dilution liquid chromatography-tandem mass spectrometry method was developed and validated for the determination and quantification of midostaurin in human plasma and serum. Midostaurin serum concentrations were analyzed in 12 patients with FMS-like tyrosine kinase 3 (FLT3)-mutated AML during induction chemotherapy with cytarabine, daunorubicin, and midostaurin. Posaconazole was used as prophylaxis of invasive fungal infections.

RESULTS

Linear quantification of midostaurin was demonstrated across a concentration range of 0.01-8.00 mg/L. Inter- and intraday imprecisions of the proposed method were well within ±10%. Venous blood samples were taken in nine and three patients in the first and second cycle of induction chemotherapy. Median (range) midostaurin serum concentration was 7.9 mg/L (1.5-26.1 mg/L) as determined in 37 independent serum specimens.

CONCLUSION

In a real-life cohort of AML patients, interindividual variability in midostaurin serum concentrations was high, highlighting issues concerning optimal drug dosing in AML patients. A personalized dosage approach may maximize the safety of midostaurin. Prospective studies and standardization of analytical methods to support such an approach are needed.

Validation of an LC-MS/MS assay for rapid and simultaneous quantification of 21 kinase inhibitors in human plasma and serum for therapeutic drug monitoring

Kinase inhibitors have revolutionized cancer treatment in the past 25 years and currently form the cornerstone of many treatments. Due to the increasing evidence for therapeutic drug monitoring (TDM) of kinase inhibitors, the need is growing for new assays to rapidly evaluate kinase inhibitor plasma concentrations. In this study, we developed an LC-MS/MS assay for the rapid and simultaneous quantification of 21 kinase inhibitors. First, a literature search was conducted to ensure that the linear ranges of the analytes were in line with the reported therapeutic windows and/or TDM reference values. Subsequently, the assay was validated according to FDA and EMA guidelines for linearity, selectivity, carry-over, accuracy, precision, dilution integrity, matrix effect, recovery, and stability. The assay was fast, with a short run-time of 2 min per sample. Sample pre-treatment consisted of protein precipitation with methanol enriched with stable isotope-labeled internal standards (SIL-IS), and the mixture was vortexed and centrifuged before sample injection. Separation was achieved using a C18 column (3 μm,50 × 2.1 mm) with a gradient of two mobile phases (ammonium formate buffer pH 3.5 and acetonitrile). Analyte detection was conducted in positive ionization mode using selected reaction monitoring. The assay was accurate and precise in plasma as well as in serum. Extraction recovery ranged between 95.0% and 106.0%, and the matrix effect was 95.7%-105.2%. The stability of the analytes varied at room temperature and in refrigerated conditions. However, all drugs were found to be stable for 7 days in the autosampler. The clinical applicability of the analytical method (486 analyzed samples between 1 July 2022-1 July 2023) as well as external quality control testing results were evaluated. Taken together, the results demonstrate that the analytical method was validated and applicable for routine analyses in clinical practice.

A liquid chromatography-tandem mass spectrometry method for simultaneous quantification of thirty-nine tyrosine kinase inhibitors in human plasma

Currently, the use of targeted drugs such as tyrosine kinase inhibitors (TKIs) plays an important role in clinical therapy. As the number of approved TKIs continues to increase, existing analysis methods will not be able to meet the growing needs, and will hamper the development of therapeutic drug monitoring (TDM) of TKIs. Based on LC-MS/MS technology, this study tends to develop and validate a multi-component analysis method for simultaneous determination of the concentrations of 39 TKIs in plasma. Spiked plasma was blended with isotope labelled internal standards, and injected into the LC-MS/MS system after protein precipitation by acetonitrile. Chromatographic separation was achieved using an ODS-4 column with gradient elution of formic acid/water (1:1000; v/v) and acetonitrile. Analytes detection was conducted in positive ionisation mode using MRM. The total run time was 8 min. The method validation was conducted by assessing the following parameters: selectivity, linearity and the lower limit of qualification, accuracy and precision, stability, matrix effect and recovery. The concentrations of 39 TKIs showed good linearity within the range of their respective standard curves in plasma, the accuracy of all quality control samples ranged from 85.9% to 114.1%, and the precision was lower than 13.3%. The extraction recovery ranged from 92.6% to 114.7%, and the matrix effect of plasma was lower than 11.3%. This new method was successfully developed, can be used for the determination of drug concentrations in multiple patients with different kinds of TKIs, and will therefore be suitable for TDM of 39 TKIs.

Simultaneous Determination of Orelabrutinib, Zanubrutinib, Ibrutinib and Its Active Metabolite in Human Plasma Using LC-MS/MS

Ibrutinib, orelabrutinib, and zanubrutinib are all Bruton's tyrosine kinase inhibitors, which have greatly improved the treatment of B-cell malignancies. In this study, an LC-MS/MS method was developed and validated for the determination of orelabrutinib, zanubrutinib, ibrutinib, and its active metabolite dihydrodiol ibrutinib in human plasma. The Ibrutinib-d5 was used as the internal standard. Pretreatment was performed using a simple protein precipitation step using acetonitrile. The ACQUITY UPLC HSS T3 column (2.1×50 mm, 1.8 μm) was used to separate the analytes, and the run time was 6.5 min. The mobile phase consisted of acetonitrile and 10 mM of ammonium formate, which contained 0.1% formic acid. The multiple reactions' monitoring transitions were selected at m/z 428.1→411.2, 472.2→455.2, 441.1→304.2, 475.2→304.2 and 446.2→309.2 respectively for orelabrutinib, zanubrutinib, ibrutinib, dihydrodiol ibrutinib and ibrutinib-d5 using positive ion electrospray ionization. The standard curves were linear, from 0.400 to 200 ng/mL for ibrutinib and dihydrodiol ibrutinib, 1.00-500 ng/mL for orelabrutinib, and 2.00-1000 ng/mL for zanubrutinib. Selectivity, the lower limit of quantitation, precision, accuracy, matrix effect, recovery, stability, and dilution integrity all met the acceptance criteria of FDA guidance. This method was used to quantify the plasma levels of orelabrutinib, zanubrutinib, ibrutinib, and dihydrodiol ibrutinib in clinical patients.

Development and Validation of a Simple Method for Simultaneously Measuring the Concentrations of BCR-ABL and Bruton Tyrosine Kinase Inhibitors in Dried Blood Spot (DBS): A Pilot Study to Obtain Candidate Conversion Equations for Predicting Plasma Concentration Based on DBS Concentration

BACKGROUND

Dried blood spots (DBSs) are promising candidates for therapeutic drug monitoring. In this study, a simple method for the simultaneous measurement of tyrosine kinase inhibitors (TKIs), including bosutinib, dasatinib, ibrutinib, imatinib, nilotinib, and ponatinib, using DBS was developed and validated. The prediction of the plasma concentration of TKIs based on the TKI concentrations in the DBS was assessed using the developed measurement method.

METHODS

DBS was prepared using venous blood on Whatman 903 cards. One whole DBS sample containing the equivalent of 40 μL of blood was used for the analysis. The analytical method was validated according to the relevant guidelines. For clinical validation, 96 clinical samples were analyzed. The regression equation was derived from a weighted Deming regression analysis, and correction factors for calculating the estimated plasma concentrations (EPCs) of the analytes from their concentrations in the DBS and the predictive performance of EPC were evaluated using 2 conversion equations.

RESULTS

This method was successfully validated. Hematocrit had no significant effect on the method's accuracy or precision. Ibrutinib was stable in the DBS for up to 8 weeks at room temperature, whereas all BCR-ABL TKIs were stable for 12 weeks. All BCR-ABL TKIs exhibited similar predictive performance for EPCs using both calculation methods. Good agreement between EPCs and the measured plasma concentrations of bosutinib, imatinib, and ponatinib was observed with both conversion equations. However, Bland-Altman analysis showed that blood sampling time affected the EPC accuracy for dasatinib and nilotinib.

CONCLUSIONS

A simple method for the simultaneous determination of BCR-ABL and Bruton TKI concentrations in DBS was developed and validated. Owing to the small clinical sample size, further clinical validation is needed to determine the predictive performance of EPCs for the 6 TKIs.

Development and Validation of an LC-MS/MS Method to Quantify Gilteritinib and Its Clinical Application in Patients With FLT3 Mutation-Positive Acute Myelogenous Leukemia

BACKGROUND

Gilteritinib, a novel oral tyrosine kinase inhibitor, is used to treat acute myeloid leukemia (AML) with FMS-like tyrosine kinase-3 (FLT3) mutations. Therapeutic drug monitoring (TDM) of gilteritinib is important for improving clinical outcomes and ensuring safety. Therefore, this study aimed to develop a simplified method for quantifying gilteritinib in human plasma using liquid chromatography-tandem mass spectrometry.

METHODS

Liquid chromatography was performed by using an Acquity BEH C18 column (50 mm × 2.1 mm, 1.7 μm) and a gradient elution with 0.1% formic acid in water (A) and acetonitrile (B). Detection was performed by using a Shimadzu tandem mass spectrometer through multiple reaction monitoring in the positive-ion mode.

RESULTS

The developed method enabled quantification of gilteritinib in 4 minutes and was validated by evaluating selectivity, calibration curve (10-1000 ng/mL, r 2 > 0.99), a lower limit of quantification (LLOQ), accuracy (overall bias -4.2% to 1.9%), precision (intraday CV ≤ 7.9%; interday CV ≤ 13.6%), carryover, recovery, matrix effect, dilution integrity, and stability according to the US Food and Drug Administration (FDA) guidelines. This method was successfully applied to the TDM of gilteritinib trough concentrations in 3 patients with AML.

CONCLUSIONS

The developed method fulfilled the FDA guideline criteria and can easily be implemented to facilitate TDM in patients receiving gilteritinib in a clinical setting.

Rapid Determination of 9 Tyrosine Kinase Inhibitors for the Treatment of Hepatocellular Carcinoma in Human Plasma by QuEChERS-UPLC-MS/MS

A reliable and rapid method employing QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) pretreatment coupled with ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) was successfully developed and validated for the analysis of nine tyrosine kinase inhibitors (TKIs) in human plasma. Biological samples were extracted with acetonitrile and salted out with 350 mg of anhydrous magnesium sulfate (MgSO₄), followed by purification with 40 mg of ethyl enediamine-N-propylsilane (PSA) adsorbents. All analytes and internal standards (IS) were separated on the Hypersil GOLD VANQUISH C18 (2.1 mm × 100 mm, 1.9 μM) column using the mobile phases composed of acetonitrile (phase A) and 0.1% formic acid in water (phase B) for 8.0 min. Detection was performed by selection reaction monitoring (SRM) in the positive ion electrospray mode. Lenvatinib, sorafenib, cabozantinib, apatinib, gefitinib, regorafenib, and anlotinib rendered good linearity over the range of 0.1–10 ng/ml, and 1–100 ng/ml for tivantinib and galunisertib. All linear correlation coefficients for all standard curves were ≥ 0.9966. The limits of detection (LOD) and the limits of quantitation (LOQ) ranged from 0.003 to 0.11 ng/ml and 0.01–0.37 ng/ml, respectively. The method was deemed satisfactory with an accuracy of -7.34–6.64%, selectivity, matrix effect (ME) of 90.48–107.77%, recovery, and stability. The proposed method is simple, efficient, reliable, and applicable for the detection of TKIs in human plasma samples as well as for providing a reference for the clinical adjustment of drug administration regimen by monitoring the drug concentrations in the plasma of patients.

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.

Pharmacokinetics, bioavailability and tissue distribution of chitobiose and chitotriose in rats

Chitooligosaccharides (COSs) have various physiological activities and broad application prospects; however, their pharmacokinetics and tissue distribution remain unclear. In this study, a sensitive and selective ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) method for determining chitobiose (COS 2) and chitotriose (COS 3) in rat serum and tissues was developed. This method was successfully validated based on FDA guidelines in terms of selectivity, calibration curves (lower limit of quantification was 0.002 µg/mL for COS 2 and 0.02 µg/mL for COS 3), precision (intra-day relative standard deviation of 0.04%-3.55% and inter-day relative standard deviation of 1.94%-11.63%), accuracy (intra-day relative error of - 1.81%-11.06% and inter-day relative error of - 9.41%-8.63%), matrix effects, recovery (97.10%-101.29%), stability, dilution integrity, and carry-over effects. Then, the method was successfully applied to the pharmacokinetics and tissue distribution study of COS 2 and COS 3 after intragastric and intravenous administration. After intragastric administration, COS 2 and COS 3 were rapidly absorbed, reached peak concentrations in the serum after approximately 0.45 h, and showed rapid elimination with clearances greater than 18.82 L/h/kg and half-lives lower than 6 h. The absolute oral bioavailability of COS 2 and COS 3 was 0.32%-0.52%. COS 2 and COS 3 were widely distributed in Wistar rat tissues and could penetrated the blood-brain barrier without tissue accumulation.

Volumetric absorptive microsampling as a suitable tool to monitor tyrosine kinase inhibitors

Therapeutic drug monitoring (TDM) of tyrosine kinase inhibitors (TKIs) shows significant potential in guiding personalized anticancer treatment. Dried blood microsampling could be a valuable alternative for traditional plasma sampling to provide TDM results faster and to reach a wider audience. Sample collection is easy and patient friendly as only a small volume of blood is collected via a fingerprick. This enables the possibility of home sampling by the patients themselves. Therefore, an LC-MS/MS method was developed and validated for the quantification of bosutinib, dasatinib, gilteritinib, ibrutinib, imatinib, midostaurin, nilotinib and ponatinib in dried blood samples collected via volumetric absorptive microsampling (VAMS). A VAMS device collects a fixed volume of blood (± 10 µL), irrespective of the sample's hematocrit (Hct). During method validation, special attention was paid to the possible impact of Hct (range 0.18-0.55) on matrix effect (ME), robustness of the extraction, and accuracy of the method. The method was successfully validated based on international guidelines in terms of calibration curves, precision (within-run CV 2.20-14.8%; between-run CV 2.40-12.3%), accuracy (within-run bias 0.34-12.5%; between-run bias -0.15 to 16.2%), carry-over and selectivity. IS-compensated ME and recovery were Hct independent and no significant impact of Hct on the accuracy of the TKI quantifications was observed. All TKIs were stable in VAMS samples stored at -20 °C, 4 °C and room temperature for at least 4 weeks and for 2 days at 60 °C (except ibrutinib). Lastly, we demonstrated a good agreement between liquid blood obtained from patients on TKI treatment and VAMS samples prepared from that venous blood. As this implies that there is no methodological impact of liquid versus dried blood analysis, the presented method can be applied in clinical follow-up studies for determining TKIs in (capillary) VAMS samples with varying Hct levels.

Novel Treatments for Pediatric Relapsed or Refractory Acute B-Cell Lineage Lymphoblastic Leukemia: Precision Medicine Era

With the markedly increased cure rate for children with newly diagnosed pediatric B-cell acute lymphoblastic leukemia (B-ALL), relapse and refractory B-ALL (R/R B-ALL) remain the primary cause of death worldwide due to the limitations of multidrug chemotherapy. As we now have a more profound understanding of R/R ALL, including the mechanism of recurrence and drug resistance, prognostic indicators, genotypic changes and so on, we can use newly emerging technologies to identify operational molecular targets and find sensitive drugs for individualized treatment. In addition, more promising and innovative immunotherapies and molecular targeted drugs that are expected to kill leukemic cells more effectively while maintaining low toxicity to achieve minimal residual disease (MRD) negativity and better bridge hematopoietic stem cell transplantation (HSCT) have also been widely developed. To date, the prognosis of pediatric patients with R/R B-ALL has been enhanced markedly thanks to the development of novel drugs. This article reviews the new advancements of several promising strategies for pediatric R/R B-ALL.

Handling unstable analytes: literature review and expert panel survey by Japan Bioanalysis Forum Discussion Group

Analyzing unstable small molecule drugs and metabolites in blood continues to be challenging for bioanalysis. Although scientific countermeasures such as immediate cooling, immediate freezing, addition of enzyme inhibitors, pH adjustment, dried blood spot or derivatization have been developed, selecting the best practices has become an issue in the pharmaceutical industry as the number of drugs with such problems is increasing, even for generic drugs. In this study, we conducted a comprehensive literature review and a questionnaire survey to determine a suitable practice for evaluating instability and implementing countermeasures. Three areas of focus, matrix selection, effect of hemolysis and selection of esterase inhibitors, are discussed.

Therapeutic Drug Monitoring and Individualized Medicine of Dasatinib: Focus on Clinical Pharmacokinetics and Pharmacodynamics

Dasatinib is an oral second-generation tyrosine kinase inhibitor known to be used widely in Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia (CML) and Ph+ acute lymphoblastic leukemia (ALL). Notably, although a high pharmacokinetic variability in patients and an increased risk of pleural effusion are attendant, fixed dosing remains standard practice. Retrospective studies have suggested that dasatinib exposure may be associated with treatment response (efficacy/safety). Therapeutic drug monitoring (TDM) is gradually becoming a practical tool to achieve the goal of individualized medicine for patients receiving targeted drugs. With the help of TDM, these patients who maintain response while have minimum adverse events may achieve long-term survival. This review summaries current knowledge of the clinical pharmacokinetics variation, exposure-response relationships and analytical method for individualized dosing of dasatinib, in particular with respect to therapeutic drug monitoring. In addition, it highlights the emerging insights into several controversial issues in TDM of dasatinib, with the aim of presenting up-to-date evidence for clinical decision-making and insights for future studies.

Simultaneous determination of nine tyrosine kinase inhibitors in three complex biological matrices by using high-performance liquid chromatography-diode array detection combined with a second-order calibration method

An intelligent chemometric second-order calibration method called alternating trilinear decomposition- assisted multivariate curve resolution combined with high-performance liquid chromatography-diode array detection was used for the simultaneous quantification of nine tyrosine kinase inhibitors in three complex biological systems. The method allows simultaneous quantification of the components in different biological matrices without the need for cumbersome pre-treatment steps, complex elution conditions, and complete peak separation. Even with the varying time shift, severe peak overlap, and various unknown interferences, the proposed method can extract pure chromatographic and spectroscopic information for each analyte, while providing accurate qualitative and quantitative results of nine common tyrosine kinase inhibitors in three different biological matrices. All the drugs were eluted in 7 min. The results showed that the nine drugs in each matrix showed good linearity (r > 0.984) in the calibration range with a root mean square error of calibration less than 0.9 μg/mL. The average spiked recoveries of the target analytes were all in the range of 83.4-110.0%, with standard deviations less than 9.0%. Finally, the classical method was used to validate the proposed method. In comparison to the traditional method, the proposed strategy is accuracy, simultaneous, and interference-free.