Therapeutic drug monitoring of oral targeted antineoplastic drugs

Evaluation of in vivo pharmacokinetic study of the anti-cancer drug imatinib using silkworms as an animal model

Imatinib is an oral molecular targeted therapy that acts as a tyrosine kinase inhibitor. Silkworms present a promising experimental model for elucidating the pharmacokinetic and toxicity profiles of various compounds. This study aimed to establish an experimental paradigm for investigating the pharmacokinetics of imatinib in silkworms. A comparative analysis of imatinib pharmacokinetic parameters across silkworms, humans, mice, and rats revealed similarities in time to maximum concentration (Tmax) and apparent clearance values between silkworms and humans. However, differences in elimination half-life (t1/2) and apparent volume of distribution between silkworms and humans remained within 5- and 4-fold ranges, respectively. Importantly, mice demonstrated pharmacokinetic parameters closer to those of humans than rats during imatinib studies. Additionally, silkworms and mice exhibit similar Tmax and t1/2 values. This study highlights the potential of silkworms as valuable tools for investigating imatinib metabolism in pharmacokinetic studies. Furthermore, it underscores the applicability of silkworms in elucidating the pharmacokinetic parameters of various molecular-targeted drugs, thus facilitating advancements in drug development and evaluation.

A Score to Predict the Clinical Usefulness of Therapeutic Drug Monitoring: Application to Oral Molecular Targeted Therapies in Cancer

Therapeutic drug monitoring (TDM) involves measuring and interpreting drug concentrations in biological fluids to adjust drug dosages. In onco-hematology, TDM guidelines for oral molecular targeted therapies (oMTTs) are varied. This study evaluates a quantitative approach with a score to predict the clinical usefulness of TDM for oMTTs. We identified key parameters for an oMTT's suitability for TDM from standard TDM recommendations. We gathered oMTT pharmacological data, which covered exposure variability (considering pharmacokinetic (PK) impact of food and proton pump inhibitors), technical intricacy (PK linearity and active metabolites), efficacy (exposure-response relationship), and safety (maximum tolerated dose, and exposure-safety relationship). To assess the validity and the relevance of the score and define relevant thresholds, we evaluated molecules with prospective validation or strong recommendations for TDM, both in oncology and in other fields. By September 1, 2021, the US Food and Drug Administration (FDA) approved 67 oMTTs for onco-hematological indications. Scores ranged from 15 (acalabrutinib) to 80 (sunitinib) with an average of 48.3 and a standard deviation of 15.6. Top scorers included sunitinib, sorafenib, cabozantinib, nilotinib, and abemaciclib. Based on scores, drugs were categorized into low (< 40), intermediate (≥ 40 and < 60), and high (≥ 60) relevance for TDM. Notably, negative controls generally scored around or under 40, whereas positive controls had a high score across different indications. In this work, we propose a quantitative and reproducible score to compare the potential usefulness of TDM for oMTTs. Future guidelines should prioritize the TDM for molecules with the highest score.

Machine Learning Methods for Precision Dosing in Anticancer Drug Therapy: A Scoping Review

INTRODUCTION

In the last decade, various Machine Learning techniques have been proposed aiming to individualise the dose of anticancer drugs mostly based on a presumed drug effect or measured effect biomarkers. The aim of this scoping review was to comprehensively summarise the research status on the use of Machine Learning for precision dosing in anticancer drug therapy.

METHODS

This scoping review was conducted in accordance with the interim guidance by Cochrane and the Joanna Briggs Institute. We systematically searched the databases Medline (via PubMed), Embase and the Cochrane Library for research articles and reviews including results published after 2016. Results were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) checklist.

RESULTS

A total of 17 relevant studies was identified. In 12 of the included studies, Reinforcement Learning methods were used, including Classical, Deep, Double Deep and Conservative Q-Learning and Fuzzy Reinforcement Learning. Furthermore, classical Machine Learning methods were compared in terms of their performance and an artificial intelligence platform based on parabolic equations was used to guide dosing prospectively and retrospectively, albeit only in a limited number of patients. Due to the significantly different algorithm structures, a meaningful comparison between the various Machine Learning approaches was not possible.

CONCLUSION

Overall, this review emphasises the clinical relevance of Machine Learning methods for anticancer drug dose optimisation, as many algorithms have shown promising results enabling model-free predictions with the potential to maximise efficacy and minimise toxicity when compared to standard protocols.

Analytical Validation of a Volumetric Absorptive Microsampling Method for Therapeutic Drug Monitoring of the Oral Targeted Anticancer Agents, Abiraterone, Alectinib, Cabozantinib, Imatinib, Olaparib, and Sunitinib, and Metabolites

BACKGROUND

Volumetric Absorptive Microsampling (VAMS) is a useful tool for therapeutic drug monitoring (TDM) of oral targeted anticancer agents. VAMS aims to improve safety and efficacy by enabling at-home blood sample collection by patients. This study aimed to develop and validate an ultra-high performance liquid chromatography-tandem mass spectrometry method for the quantitative determination of abiraterone, alectinib, cabozantinib, imatinib, olaparib, sunitinib, and the metabolites, Δ(4)-abiraterone (D4A), alectinib-M4, imatinib-M1, and N -desethyl sunitinib, in dried whole blood samples using VAMS to support TDM.

METHODS

After the collection of 10 μL of whole blood sample using the VAMS device, the analytes were extracted from the tip using methanol with shaking, evaporated, and reconstituted in acetonitrile:0.1 mol/L ammonium hydroxide in water (1:1, vol/vol). The extracts were then analyzed using ultra-high performance liquid chromatography-tandem mass spectrometry. Validation experiments based on the ICH M10 guideline were carried out, and stability was evaluated under shipping and storage conditions. VAMS specimens were collected in the outpatient clinic to demonstrate the applicability of the assay.

RESULTS

The validated range of the method was considered accurate and precise for all analytes. Accordingly, the validation experiments met the relevant requirements, except for cross-analyte interference. Based on the stability data, shipment can be performed at room temperature within 14 days after sample collection and the VAMS specimen can be stored up to 9 months at -20 and -70°C. Samples from 59 patients were collected at the hospital.

CONCLUSIONS

The developed method could be used to successfully quantify the concentrations of abiraterone, D4A, alectinib, alectinib-M4, cabozantinib, imatinib, imatinib-M1, olaparib, sunitinib, and N -desethyl sunitinib within the validated range using VAMS. Therefore, the method can be used to estimate the dried whole blood-to-plasma ratios for TDM in the clinic.

Docetaxel, cyclophosphamide, and epirubicin: application of PBPK modeling to gain new insights for drug-drug interactions

The new adjuvant chemotherapy of docetaxel, epirubicin, and cyclophosphamide has been recommended for treating breast cancer. It is necessary to investigate the potential drug-drug Interactions (DDIs) since they have a narrow therapeutic window in which slight differences in exposure might result in significant differences in treatment efficacy and tolerability. To guide clinical rational drug use, this study aimed to evaluate the DDI potentials of docetaxel, cyclophosphamide, and epirubicin in cancer patients using physiologically based pharmacokinetic (PBPK) models. The GastroPlus™ was used to develop the PBPK models, which were refined and validated with observed data. The established PBPK models accurately described the pharmacokinetics (PKs) of three drugs in cancer patients, and the predicted-to-observed ratios of all the PK parameters met the acceptance criterion. The PBPK model predicted no significant changes in plasma concentrations of these drugs during co-administration, which was consistent with the observed clinical phenomenon. Besides, the verified PBPK models were then used to predict the effect of other Cytochrome P450 3A4 (CYP3A4) inhibitors/inducers on these drug exposures. In the DDI simulation, strong CYP3A4 modulators changed the exposure of three drugs by 0.71-1.61 fold. Therefore, patients receiving these drugs in combination with strong CYP3A4 inhibitors should be monitored regularly to prevent adverse reactions. Furthermore, co-administration of docetaxel, cyclophosphamide, or epirubicin with strong CYP3A4 inducers should be avoided. In conclusion, the PBPK models can be used to further investigate the DDI potential of each drug and to develop dosage recommendations for concurrent usage by additional perpetrators or victims.

Therapeutic Monitoring of Palbociclib, Ribociclib, Abemaciclib, M2, M20, and Letrozole in Human Plasma: A Novel LC-MS/MS Method

BACKGROUND

Therapeutic drug monitoring (TDM) using cyclin-dependent kinase inhibitors (CDK4/6is) is a novel approach for optimizing treatment outcomes. Currently, palbociclib, ribociclib, and abemaciclib are the available CDK4/6is and are primarily coadministered with letrozole. This study aimed to develop and validate an LC-MS/MS method for the simultaneous analysis of CDK4/6is, 2 active metabolites of abemaciclib (M2 and M20), and letrozole in human plasma for use in TDM studies.

METHODS

Sample pretreatment comprised protein precipitation with methanol and dilution of the supernatant with an aqueous mobile phase. Chromatographic separation was achieved using a reversed-phase XBridge BEH C18 column (2.5 μm, 3.0 × 75 mm XP), with methanol serving as the organic mobile phase and pyrrolidine-pyrrolidinium formate (0.005:0.005 mol/L) buffer (pH 11.3) as the aqueous mobile phase. A triple quadrupole mass spectrometer was used for the detection, with the ESI source switched from negative to positive ionization mode and the acquisition performed in multiple reaction monitoring mode.

RESULTS

The complete validation procedure was successfully performed in accordance with the latest regulatory guidelines. The following analytical ranges (ng/mL) were established for the tested compounds: 6-300, palbociclib and letrozole; 120-6000, ribociclib; 40-800, abemaciclib; and 20-400, M2 and M20. All results met the acceptance criteria for linearity, accuracy, precision, selectivity, sensitivity, matrix effects, and carryover. A total of 85 patient samples were analyzed, and all measured concentrations were within the validated ranges. The percent difference for the reanalyzed samples ranged from -11.2% to 7.0%.

CONCLUSIONS

A simple and robust LC-MS/MS method was successfully validated for the simultaneous quantification of CDK4/6is, M2, M20, and letrozole in human plasma. The assay was found to be suitable for measuring steady-state trough concentrations of the analytes in patient samples.

Incidence of hand-foot syndrome with protein kinase inhibitors in advanced hepatocellular carcinoma patients who received atezolizumab-bevacizumab combination

INTRODUCTION

Treatment of advanced HepatoCellular Carcinoma (HCC) is based on first-line (L1) combination of atezolizumab and high-dose (HD) bevacizumab while second-line (L2) refers one antiangiogenic protein kinase inhibitors (aaPKI). This prolonged antiangiogenic pressure let us to observe an increasing occurrence of Hand-Foot Syndromes (HFS) in patients receiving aaPKI after HD bevacizumab combination. This study reports observations and discussions about the evidence and hypothesis that could be made.

METHODS

Patients who received the L1 combination from September 1st 2020 to December 31st 2022 to identify L2 aaPKI. Demographic, biological, oncological data and occurrence of HFS were collected. In addition were collected the number of L1 combination cycles, type of aaPKI, and delay between last L1 cycle and L2 initiation. This study had a purely exploratory purpose, so no statistical analysis was planned.

RESULTS

17 patients received an aaPKI after the L1 HD bevacizumab combination with a median time of 26 days from last L1 cycle to L2 start. Five patients experienced HFS including grade 3 (n = 2) with sorafenib and cabozantinib. The HFS occurred with a median delay of 23 days (IQR: 21-28) from aaPKI start. Three patients experienced aaPKI-related dose-limiting toxicity.

CONCLUSIONS

Proportion of patients experienced HFS in our cohort did not differ from pivotal trials data and the sample size do not allow to conclude. Hypotheses include timing of aaPKI start in HCC treatment, vascular toxicity at aaPKI start after HD bevacizumab discontinuation instead combination, patient-related outcome for a better understanding of these aaPKI-related HFS post HD bevacizumab.

Tyrosine kinase inhibitors in cancers: Treatment optimization - Part II

Real-life populations are more heterogeneous than those included in prospective clinical studies. In cancer patients, comorbidities and co-medications favor the appearance of severe adverse effects which can significantly impact quality of life and treatment effectiveness. Most of tyrosine kinase inhibitors (TKI) have been developed with flat oral dosing exposing patients to the risk of poor adherence due to side effects. Additionally, genetic or physiological factors, differences in diet, and drug-drug interactions can lead to inter-individual variability affecting treatment outcomes and increasing the risk of adverse events. Knowledge of the different factors of variability allows individualized patient management. This review examines the effects of adherence, food intake, and pharmaceutical form on the pharmacokinetics of oral TKI, as well as evaluating pharmacokinetics considerations improving TKI management. Concentration-effectiveness and concentration-toxicity data are presented for the selected TKI, and a simple therapeutic drug monitoring schema is outlined to help individualize dosing of oral TKI.

Pharmacology of Tyrosine Kinase Inhibitors: Implications for Patients with Kidney Diseases

Tyrosine kinase inhibitors (TKI) have introduced a significant advancement in cancer management. These compounds are administered orally, and their absorption holds a pivotal role in determining their variable efficacy. They exhibit extensive distribution within the body, binding strongly to both plasma and tissue proteins. Often reliant on efflux and influx transporters, TKI undergo primary metabolism by intestinal and hepatic cytochrome P450 enzymes, with nonkidney clearance being predominant. Owing to their limited therapeutic window, many TKI display considerable intraindividual and interindividual variability. This review offers a comprehensive analysis of the clinical pharmacokinetics of TKI, detailing their interactions with drug transporters and metabolic enzymes, while discussing potential clinical implications. The prevalence of kidney conditions, such as AKI and CKD, among patients with cancer is explored in their effect on TKI pharmacokinetics. Finally, the potential nephrotoxicity associated with TKI is also examined.

Population Pharmacokinetics of Trametinib and Impact of Nonadherence on Drug Exposure in Oncology Patients as Part of the Optimizing Oral Targeted Anticancer Therapies Study

Trametinib is a targeted therapy used for the treatment of solid tumours, with significant variability reported in real-life studies. This variability increases the risk of suboptimal exposure, which can lead to treatment failure or increased toxicity. Using model-based simulation, this study aims to characterize and investigate the pharmacokinetics and the adequacy of the currently recommended doses of trametinib. Additionally, the simulation of various suboptimal adherence scenarios allowed for an assessment of the impact of patients' drug adherence on the treatment outcome. The population data collected in 33 adult patients, providing 113 plasmatic trametinib concentrations, were best described by a two-compartment model with linear absorption and elimination. The study also identified a significant positive effect of fat-free mass and a negative effect of age on clearance, explaining 66% and 21% of the initial associated variability, respectively. Simulations showed that a maximum dose of 2 mg daily achieved the therapeutic target in 36% of male patients compared to 72% of female patients. A dose of 1.5 mg per day in patients over 65 years of age achieved similar rates, with 44% and 79% for male and female patients, respectively, reaching the therapeutic target. Poor adherence leads to a significant drop in concentrations and a high risk of subtherapeutic drug levels. These results underline the importance of interprofessional collaboration and patient partnership along the patient's journey to address patients' needs regarding trametinib and support medication adherence.

Triazole antifungal drug interactions-practical considerations for excellent prescribing

Systemic antifungal therapy is critical for reducing the mortality from many invasive and chronic fungal infections. Triazole antifungals are the most frequently prescribed antifungals but require attention to dosing and drug interactions. Nearly 600 severe drug-drug interactions and over 1100 moderate interactions requiring dose modifications are described or anticipated with systemic antifungal agents (see https://www.aspergillus.org.uk/antifungal-drug-interactions/). In this article, we address the common and less common, but serious, drug interactions observed in clinical practice with triazole antifungals, including a group of drugs that cannot be prescribed with all or most triazole antifungals (ivabradine, ranolazine, eplerenone, fentanyl, apomorphine, quetiapine, bedaquiline, rifampicin, rifabutin, sirolimus, phenytoin and carbamazepine). We highlight interactions with drugs used in children and new agents introduced for the treatment of haematological malignancies or graft versus host disease (midostaurin, ibrutinib, ruxolitinib and venetoclax). We also summarize the multiple interactions between oral and inhaled corticosteroids and triazole antifungals, and the strategies needed to optimize the therapeutic benefits of triazole antifungal therapy while minimizing potential harm to patients.

Clinical Guidance for Dosing and Monitoring Oral Antihormonal Drugs in Patients with Breast Cancer After Roux-en-Y Gastric Bypass

ABSTRACT

Obesity is associated with an increased risk of cancers, such as breast cancer. Roux-en-Y gastric bypass (RYGB) is a common surgical intervention used to induce weight loss, reduce comorbidities, and improve overall survival. Due to alterations in the gastrointestinal tract, RYGB is associated with changes in oral drug disposition, which can affect treatment outcomes. Oral antihormonal agents were monitored in 9 patients who previously underwent RYGB. The results of therapeutic drug monitoring and estradiol concentrations were analyzed, and a review of the relevant literature was performed. As only 1 of the 6 patients prescribed tamoxifen achieved a therapeutic endoxifen concentration with the standard dose of 20 mg/d, a higher starting dose of 40 mg/d was recommended to increase the probability of attaining a therapeutic plasma concentration. All patients with decreased CYP2D6 metabolic activity could not achieve therapeutic plasma concentrations; therefore, CYP2D6 genotyping was recommended before the initiation of tamoxifen therapy to identify patients who should be switched to aromatase inhibitors. Anastrozole and letrozole exposure in patients who underwent RYGB patients appeared sufficient, with no dose adjustment required. However, until more data become available, monitoring aromatase inhibitor efficacy is recommended. Monitoring the drug concentrations is a viable option; however, only indicative data on therapeutic drug monitoring are available. Therefore, estradiol concentrations should be measured.

New-generation androgen receptor signaling inhibitors (ARSIs) in metastatic hormone-sensitive prostate cancer (mHSPC): pharmacokinetics, drug-drug interactions (DDIs), and clinical impact

INTRODUCTION

The therapeutic scenario of metastatic hormone-sensitive prostate cancer (mHSPC) has dramatically changed in recent years, with the approval of new-generation Androgen Receptor Signaling Inhibitors (ARSIs), in combination with the androgen deprivation therapy (ADT), which was the previous standard of care. Despite showing a similar clinical efficacy, ARSIs, all of which are administered orally, are different in terms of pharmacokinetic and drug-drug interactions (DDIs).

AREAS COVERED

This review covers the main pharmacokinetic characteristics of ARSIs that have been approved for the first-line therapy of mHSPC patients, underlying the differences among these molecules and focusing on the known or possible interactions with other drugs. Full-text articles and abstracts were searched in PubMed.

EXPERT OPINION

Since prostate cancer occurs mainly in older age, comorbidities and the consequent polypharmacy increase the DDI risk in mHSPC patients who are candidates for ARSI. Waiting for new therapeutic options, in the absence of direct comparisons, pharmacokinetic knowledge is essential to guide clinicians in prescribing ARSI in this setting.

Therapeutic Drug Monitoring of Pazopanib in Renal Cell Carcinoma and Soft Tissue Sarcoma: A Systematic Review

BACKGROUND

Pazopanib, an anti-angiogenic multitarget tyrosine kinase inhibitor, has been approved for the treatment of metastatic renal cell carcinoma and soft tissue sarcoma. However, its recommended dose does not always produce consistent outcomes, with some patients experiencing adverse effects or toxicity. This variability is due to differences in the systemic exposure to pazopanib. This review aimed to establish whether sufficient evidence exists for the routine or selective therapeutic drug monitoring of pazopanib in adult patients with approved indications.

METHODS

A systematic search of the PubMed and Web of Science databases using search terms related to pazopanib and therapeutic drug monitoring yielded 186 and 275 articles, respectively. Ten articles associated with treatment outcomes or toxicity due to drug exposure were selected for review.

RESULTS

The included studies were evaluated to determine the significance of the relationship between drug exposure/Ctrough and treatment outcomes and between drug exposure and toxicity. A relationship between exposure and treatment outcomes was observed in 5 studies, whereas the trend was nonsignificant in 4 studies. A relationship between exposure and toxicity was observed in 6 studies, whereas 2 studies did not find a significant relationship; significance was not reported in 3 studies.

CONCLUSIONS

Sufficient evidence supports the therapeutic drug monitoring of pazopanib in adult patients to improve its efficacy and/or safety in the approved indications.

Therapeutic drug monitoring guidelines in oncology: what do we know and how to move forward? Insights from a systematic review

Background

Compared with anti-infective drugs, immunosuppressants and other fields, the application of therapeutic drug monitoring (TDM) in oncology is somewhat limited.

Objective

We aimed to provide a comprehensive understanding of TDM guidelines for antineoplastic drugs and to promote the development of individualized drug therapy in oncology.

Design

This study type is a systematic review.

Data sources and methods

This study was performed and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 statement. Databases including PubMed, Embase, the official websites of TDM-related associations and Chinese databases were comprehensively searched up to March 2023. Two investigators independently screened the literature and extracted data. The methodological and reporting quality was evaluated using the Appraisal of Guidelines for Research and Evaluation II (AGREE II) and the Reporting Items for Practice Guidelines in Healthcare (RIGHT), respectively. Recommendations and quality evaluation results were presented by visual plots. This study was registered in PROSPERO (No. CRD42022325661).

Results

A total of eight studies were included, with publication years ranging from 2014 to 2022. From the perspective of guideline development, two guidelines were developed using evidence-based methods. Among the included guidelines, four guidelines were for cytotoxic antineoplastic drugs, three for small molecule kinase inhibitors, and one for antineoplastic biosimilars. Currently available guidelines and clinical practice provided recommendations of individualized medication in oncology based on TDM, as well as influencing factors. With regard to methodological quality based on AGREE II, the average overall quality score was 55.21%. As for the reporting quality by RIGHT evaluation, the average reporting rate was 53.57%.

Conclusion

From the perspective of current guidelines, TDM in oncology is now being expanded from cytotoxic antineoplastic drugs to newer targeted treatments. Whereas, the types of antineoplastic drugs involved are still small, and there is still room for quality improvement. Furthermore, the reflected gaps warrant future studies into the exposure-response relationships and population pharmacokinetics models.

Improving olaparib exposure to optimize adverse effects management

Background

Olaparib is an inhibitor of the human poly-(ADP-ribose)-polymerase enzymes (PARP1/2) needed to repair single-strand DNA breaks. It is used in breast, ovarian, prostate and pancreatic cancer.

Objectives

This work aimed to describe the pharmacokinetics/pharmacodynamics (PK/PD) relationship between olaparib plasma concentrations and common adverse effects (i.e. anaemia and hypercreatininaemia), in a real-life setting, to propose a target concentration for therapeutic drug monitoring.

Methods

Two PK/PD models describing the evolution of haemoglobinaemia and creatininaemia as a function of time were developed, based on data from, respectively, 38 and 37 patients receiving olaparib. The final model estimates were used to calculate the incidence of anaemia and creatinine increase according to plasma trough concentrations for 1000 virtual subjects to define target exposure.

Results

The final models correctly described the temporal evolution of haemoglobinaemia and creatininaemia for all patients. The haemoglobinaemia PK/PD model is inspired by Friberg's model, and the creatininaemia PK/PD model is an indirect response model. Model parameters were in agreement with physiological values and close to literature values for similar models. The mean (population) plasma haemoglobin concentration at treatment initiation, as estimated by the model, was 11.62 g/dL, while creatinine concentration was 71.91 µmol/L. Using simulations, we have identified a target trough concentration of 3500-4000 ng/mL, above which more than 20% of patients would report grade ≥3 anaemia.

Conclusion

Based on real-world data, we were able to properly describe the time course of haemoglobinaemia and plasma creatininaemia during olaparib treatment.

Preliminary Investigation of a Rapid and Feasible Therapeutic Drug Monitoring Method for the Real-Time Estimation of Blood Pazopanib Concentrations

Pazopanib is a multi-kinase inhibitor used to treat advanced/metastatic renal cell carcinoma and advanced soft tissue tumors; however, side effects such as diarrhea and hypertension have been reported, and dosage adjustment based on drug concentration in the blood is necessary. However, measuring pazopanib concentrations in blood using the existing methods is time-consuming; and current dosage adjustments are made using the results of blood samples taken at the patient's previous hospital visit (approximately a month prior). If the concentration of pazopanib could be measured during the waiting period for a doctor's examination at the hospital (in approximately 30 min), the dosage could be adjusted according to the patient's condition on that day. Therefore, we aimed to develop a method for rapidly measuring blood pazopanib concentrations (in approximately 25 min) using common analytical devices (a tabletop centrifuge and a spectrometer). This method allowed for pazopanib quantification in the therapeutic concentration range (25-50 μg/mL). Additionally, eight popular concomitant medications taken simultaneously with pazopanib did not interfere with the measurements. We used the developed method to measure blood concentration in two patients and obtained similar results to those measured using the previously reported HPLC method. By integrating it with the point of care and sample collection by finger pick, this method can be used for measurements in pharmacies and patients' homes. This method can maximize the therapeutic effects of pazopanib by dose adjustment to control adverse events.

Simultaneous determination of 11 oral targeted antineoplastic drugs and 2 active metabolites by LC-MS/MS in human plasma and its application to therapeutic drug monitoring in cancer patients

Interindividual exposure differences have been identified in oral targeted antineoplastic drugs (OADs) owing to the pharmacogenetic background of the patients and their susceptibility to multiple factors, resulting in insufficient efficacy or adverse effects. Therapeutic drug monitoring (TDM) can prevent sub-optimal concentrations of OADs and improve their clinical treatment. This study aimed to develop and validate an LC-MS/MS method for the simultaneous quantification of 11 OADs (gefitinib, imatinib, lenvatinib, regorafenib, everolimus, osimertinib, sunitinib, tamoxifen, lapatinib, fruquintinib and sorafenib) and 2 active metabolites (N-desethyl sunitinib and Z-endoxifen) in human plasma. Protein precipitation was used to extract OADs from the plasma samples. Chromatographic separation was performed using an Eclipse XDB-C18 (4.6 × 150 mm, 5 μm) column with a gradient elution of the mobile phase composed of 2 mM ammonium acetate with 0.1 % formic acid in water (solvent A) and methanol (solvent B) at a flow rate of 0.8 mL/min. Mass analysis was performed using positive ion mode electrospray ionization in multiple-reaction monitoring mode. The developed method was validated following FDA bioanalytical guidelines. The calibration curves were linear over the range of 2-400 ng/mL for gefitinib, imatinib, lenvatinib, regorafenib, and everolimus; 1-200 ng/mL for osimertinib, sunitinib, N-desethyl sunitinib, tamoxifen, and Z-endoxifen; and 5-1000 ng/mL for lapatinib, fruquintinib, and sorafenib, with all coefficients of correlation above 0.99. The intra- and inter-day imprecision was below 12.81 %. This method was successfully applied to the routine TDM of gefitinib, lenvatinib, regorafenib, osimertinib, fruquintinib, and sorafenib to optimize the dosage regimens.

Exposure-response relationship of cabozantinib in patients with metastatic renal cell carcinoma treated in routine care

BACKGROUND

Interindividual pharmacokinetic variability may influence the clinical benefit or toxicity of cabozantinib in metastatic renal cell carcinoma (mRCC). We aimed to investigate the exposure-toxicity and exposure-response relationship of cabozantinib in unselected mRCC patients treated in routine care.

METHODS

This ambispective multicenter study enrolled consecutive patients receiving cabozantinib in monotherapy. Steady-state trough concentration (Cmin,ss) within the first 3 months after treatment initiation was used for the PK/PD analysis with dose-limiting toxicity (DLT) and survival outcomes. Logistic regression and Cox proportional-hazards models were used to identify the risk factors of DLT and inefficacy in patients, respectively.

RESULTS

Seventy-eight mRCC patients were eligible for the statistical analysis. Fifty-two patients (67%) experienced DLT with a median onset of 2.1 months (95%CI 0.7-8.2). In multivariate analysis, Cmin,ss was identified as an independent risk factor of DLT (OR 1.46, 95%CI [1.04-2.04]; p = 0.029). PFS and OS were not statistically associated with the starting dose (p = 0.81 and p = 0.98, respectively). In the multivariate analysis of PFS, Cmin, ss > 336 ng/mL resulted in a hazard ratio of 0.28 (95%CI, 0.10-0.77, p = 0.014). By contrast, Cmin, ss > 336 ng/mL was not statistically associated with longer OS.

CONCLUSION

Early plasma drug monitoring may be useful to optimise cabozantinib treatment in mRCC patients treated in monotherapy, especially in frail patients starting at a lower than standard dose.

Dispersive liquid-liquid microextraction followed by sweeping micellar electrokinetic chromatography-tandem mass spectrometry for determination of six breast cancer drugs in human plasma

Herein, we have developed a novel method of aqueous-sample dispersive liquid-liquid microextraction (AqS-DLLME) followed by sweeping micellar electrokinetic chromatography-tandem mass spectrometry (MEKC-MS/MS) for simultaneous determination of breast cancer drugs letrozole, anastrozole, palbociclib, ribociclib, abemaciclib, and fulvestrant in human plasma. Coupling of MEKC to MS was possible due to the use of ammonium perfluorooctanoate (APFO) as a volatile surfactant. The MEKC and MS conditions were optimized to achieve a fast, sensitive, selective, and green analysis enabling full separation of the analytes within 16 min. Electrophoretic buffer was 125 mM APFO at apparent pH 10.5 in 32 % MeOH, while sheath liquid was 70 % MeOH with 0.2 % formic acid, delivered at 10 µL/min. Excellent extraction recoveries from plasma ranging from 89.4 to 104.9 % were obtained with a combination of protein precipitation and DLLME. The developed method was validated according to the ICH guidelines. Remarkable selectivity, accuracy (bias < 6.7 %), precision (RSD < 15.8 %), and stability (bias < 10.4 %) with insignificant matrix effect (RSD < 14.0 %) and no carry-over were obtained over a wide range of concentrations. Linearity with inter-day slope RSD lower than 8.7 % was demonstrated. With this method, very low concentrations could be detected after the injection of only 68.7 nL of the sample. The method was applied to plasma samples from six women currently receiving breast cancer treatment. Determined concentrations of the drugs of interest agreed with concentrations found in clinical studies, thus proving the suitability of the developed method for therapeutic drug monitoring as a superior alternative to published LC-MS methods.

Therapeutic Drug Monitoring for Tyrosine Kinase Inhibitors in Metastatic Renal Cell Carcinoma

Inter-individual variability in drug response pose significant challenges to treatment with tyrosine kinase inhibitors (TKIs) in patients with metastatic renal cell carcinoma (mRCC). TKIs meet traditional criteria for using therapeutic drug monitoring (TDM), but research is still limited. Understanding the role of TDM in individualizing treatment strategies could help optimize treatment. Here we review the state of knowledge of TDM for TKIs in mRCC treatment. A comprehensive literature review of original research studies focusing on TDM of TKIs in mRCC treatment, clinical in vivo studies reporting on pharmacokinetics-pharmacodynamics, therapeutic ranges, drug concentrations, dose adjustments, clinical outcomes, or other relevant aspects related to TDM. We reviewed studies involving human subjects published in peer-reviewed journals. A narrative synthesis approach was employed to summarize the findings. Key themes and trends related to TDM of TKIs in mRCC treatment were identified and synthesized to provide a comprehensive overview of the current state of knowledge. Our search yielded 25 articles. Most were observational. The most consistently reported association between plasma concentration and effect was pazopanib Ctrough >20 µg/mL, but this concentration was not significant across all studies. We found inconsistent evidence for sunitinib and cabozantinib. For axitinib, we found a clear exposure-response relationship, but research was too diverse to conclude on a therapeutic window to use for TDM. We found much heterogeneity between recommended time of measurement (minimum plasma concentration [Cmin], maximal plasma concentration [Cmax], area under the curve [AUC]) and large variation in plasma concentration associated with clinical outcomes, which makes it difficult to recommend specific concentration intervals based on 1 or more of these measurements. Results were more consistent with TKIs continuously administered. Further research is needed to elucidate the long-term impact of TDM to possibly establish standardized therapeutic intervals. Prospective studies are suggested. The application of TDM in TKI-combination therapy is warranted in future research.

Pharmacokinetic Consideration of Venetoclax in Acute Myeloid Leukemia Patients: A Potential Candidate for TDM? A Short Communication

BACKGROUND

Venetoclax (VNX)-based regimens have demonstrated significantly favorable outcomes in patients with acute myeloid leukemia (AML) and are now becoming the standard treatment. Tyrosine kinase inhibitors are administered at a fixed dose, irrespective of body surface area or weight. For such orally targeted therapies, real-world data have highlighted a larger pharmacokinetic (PK) interindividual variability (IIV) than expected. Even if VNX PKs have been well characterized and described in the literature, only 1 clinical trial-based PK study has been conducted in patients with AML. This study aimed to evaluate the PK of VNX in AML patients.

MATERIAL AND METHODS

We retrospectively analyzed all patients treated with a combination of VNX-azacitidine between January and July 2022 at our center, using at least 1 available VNX blood sample. Based on a previously published population PK model, individual PK parameters were estimated to evaluate the exposure and IIV.

RESULTS

and Discussion. Twenty patients received VNX in combination with azacitidine, according to the PK data. A total of 93 plasma concentrations were collected. The dose of VNX was 400 mg, except in 7 patients who received concomitant posaconazole (VNX 70 mg). The patients' weight ranged from 49 kg to 108 kg (mean = 78 kg). Mean individual clearance was 13.5 ± 9.4 L/h with mean individual daily area under the concentration-time curves of 35.8 mg.h/L with significant IIV (coefficient of variation = 41.1%). Ten patients were still alive (8 in complete response), but all experienced at least 1 hematological toxicity of grade ≥ 3.

CONCLUSIONS

Based on the observed large PK variability in the data from our real-world AML patients, the risk of drug interactions and the recommended fixed-dosage regimen of VNX therapeutic drug monitoring may be useful.

A supervised machine-learning approach for the efficient development of a multi method (LC-MS) for a large number of drugs and subsets thereof: focus on oral antitumor agents

OBJECTIVES

Accumulating evidence argues for a more widespread use of therapeutic drug monitoring (TDM) to support individualized medicine, especially for therapies where toxicity and efficacy are critical issues, such as in oncology. However, development of TDM assays struggles to keep pace with the rapid introduction of new drugs. Therefore, novel approaches for faster assay development are needed that also allow effortless inclusion of newly approved drugs as well as customization to smaller subsets if scientific or clinical situations require.

METHODS

We applied and evaluated two machine-learning approaches i.e., a regression-based approach and an artificial neural network (ANN) to retention time (RT) prediction for efficient development of a liquid chromatography mass spectrometry (LC-MS) method quantifying 73 oral antitumor drugs (OADs) and five active metabolites. Individual steps included training, evaluation, comparison, and application of the superior approach to RT prediction, followed by stipulation of the optimal gradient.

RESULTS

Both approaches showed excellent results for RT prediction (mean difference ± standard deviation: 2.08 % ± 9.44 % ANN; 1.78 % ± 1.93 % regression-based approach). Using the regression-based approach, the optimum gradient (4.91 % MeOH/min) was predicted with a total run time of 17.92 min. The associated method was fully validated following FDA and EMA guidelines. Exemplary modification and application of the regression-based approach to a subset of 14 uro-oncological agents resulted in a considerably shortened run time of 9.29 min.

CONCLUSIONS

Using a regression-based approach, a multi drug LC-MS assay for RT prediction was efficiently developed, which can be easily expanded to newly approved OADs and customized to smaller subsets if required.

Plasma Venetoclax Concentrations in Patients with Acute Myeloid Leukemia Treated with CYP3A4 Inhibitors

Venetoclax (VEN) is used in patients with acute myeloid leukemia (AML) and is primarily metabolized by CYP3A4, a major drug-metabolizing enzyme. Patients with AML simultaneously administered VEN and CYP3A4 inhibitors require a more appropriate management of drug-drug interactions (DDIs). Here, we report two cases of patients with AML (54-year-old man and 22-year-old woman) administrated VEN and CYP3A4 inhibitors, such as posaconazole, cyclosporine, or danazol. In the first case, we evaluated the appropriateness of timing for adjusting VEN dosage subsequent to the cessation of posaconazole. Consequently, modifying the VEN dosage in conjunction with the cessation of Posaconazole simultaneously may result in elevated plasma VEN levels. In the second case, plasma VEN concentrations were markedly elevated when co-administered with several CYP3A4 inhibitors. Additionally, in vitro assays were conducted for reverse translational studies to analyze CYP3A4 inhibition. CYP3A4 inhibition by combinatorial administration of cyclosporine A and danazol was demonstrated in vitro, which potentially explains the increasing plasma VEN concentrations observed in clinical settings. Although the acquisition of therapeutic effects is a major priority for patients, frequent therapeutic drug monitoring and dosage adjustments considering DDIs would be important factors in chemotherapy.

Determination of Pralsetinib in Human Plasma and Cerebrospinal Fluid for Therapeutic Drug Monitoring by Ultra-performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS)

BACKGROUND

Ultra-performance Liquid Chromatography-tandem Mass Spectrometry (UPLC-MS/MS) is widely used for concentration detection of many Tyrosine Kinase Inhibitors (TKIs), including afatinib, crizotinib, and osimertinib. In order to analyze whether pralsetinib takes effect in Rearranged during Transfection (RET)-positive patients with central nervous system metastasis, we aimed to develop a method for the detection of pralsetinib concentrations in human plasma and Cerebrospinal Fluid (CSF) by UPLC-MS/MS.

METHODS

The method was developed using the external standard method, and method validation included precision, accuracy, stability, extraction recovery, and matrix effect. Working solutions were all obtained based on stock solutions of pralsetinib of 1mg/mL. The plasma/CSF samples were precipitated by acetonitrile for protein precipitation and then separated on an ACQUITY UPLC HSS T3 column (2.1×100 mm, 1.8 μm) with a gradient elution using 0.1% formic acid (solution A) and acetonitrile (solution B) as mobile phases at a flow rate of 0.4 mL/min. The tandem mass spectrometry was performed by a triple quadrupole linear ion trap mass spectrometry system (QTRAPTM 6500+) with an electrospray ion (ESI) source and Analyst 1.7.2 data acquisition system. Data were collected in Multiple Reaction Monitoring (MRM) and positive ionization mode.

RESULTS

A good linear relationship of pralsetinib in both plasma and CSF was successfully established, and the calibration ranges were found to be 1.0-64.0 μg/mL and 50.0ng/mL-12.8 μg/mL for pralsetinib in the plasma and CSF, respectively. Validation was performed, including calibration assessment, selectivity, precision, accuracy, matrix effect, extraction recovery, and stability, and all results have been found to be acceptable. The method has been successfully applied to pralsetinib concentration detection in a clinical sample, and the concentrations have been found to be 475 ng/mL and 61.55 μg/mL in the CSF and plasma, respectively.

CONCLUSION

We have developed a quick and effective method for concentration detection in both plasma and CSF, and it can be applied for drug monitoring in clinical practice. The method can also provide a reference for further optimization.

An Optimized LC-MS/MS Method for Quantification of Sunitinib and N -Desethyl Sunitinib in Human Plasma and Its Application for Therapeutic Drug Monitoring

BACKGROUND

Sunitinib (SUN) malate is an oral, multitargeted, tyrosine kinase inhibitor approved for the treatment of metastatic renal cell carcinoma, imatinib-resistant or imatinib-intolerant gastrointestinal stromal tumors, and pancreatic neuroendocrine tumors. SUN has a narrow therapeutic window and high variability in interpatient pharmacokinetic parameters. Clinical detection methods for SUN and N -desethyl SUN limit the application of SUN to therapeutic drug monitoring. All published methods for quantifying SUN in human plasma require strict light protection to avoid light-induced isomerism or the use of additional quantitative software. To avoid these difficult processes in clinical routines, the authors propose a novel method that merges the peaks of the E -isomer and Z -isomer of SUN or N -desethyl SUN into a single peak.

METHODS

The E -isomer and Z -isomer peaks of SUN or N -desethyl SUN were merged into a single peak by optimizing the mobile phases to decrease the resolution of the isomers. A suitable chromatographic column was selected to obtain a good peak shape. Thereafter, the conventional and single-peak methods (SPM) were simultaneously validated and compared according to the guidelines published by the Food and Drug Administration in 2018 and the Chinese Pharmacopoeia in 2020.

RESULTS

The verification results showed that the SPM was superior to the conventional method in the matrix effect and met the requirements for biological sample analysis. SPM was then applied to detect the total steady-state concentration of SUN and N -desethyl SUN in tumor patients who received SUN malate.

CONCLUSIONS

The established SPM makes the detection of SUN and N -desethyl SUN easier and faster without light protection or extra quantitative software, making it more appropriate for routine clinical use. The clinical application results showed that 12 patients took 37.5 mg per day, with a median total trough steady-state concentration of 75.0 ng/mL.

Therapeutic drug monitoring and pharmacogenetics to tune imatinib exposure in gastrointestinal stromal tumor patients: hurdles and perspectives for clinical implementation

Tweetable abstract Present evidence supports the use of intensified pharmacologic monitoring of #imatinib including #TherapeuticDrugMonitoring and #PGx to improve outcomes in patients with GI stromal tumor. Future studies need to address emerging questions to facilitate implementation in clinics.

Trends and prescribing patterns of oral anti-neoplastic drugs: a retrospective longitudinal study

Background

Cancer as a global public health problem, imposes a heavy disease burden. With the rapid development of oral anti-neoplastic drugs, there has been a paradigm shift in the treatment of cancer from intravenous to oral administration.

Objective

This study was conducted to investigate the trends and prescribing patterns of oral anti-neoplastic drugs in an academic tertiary hospital in China.

Methods

A single-center and retrospective analysis was performed based on the prescriptions of outpatients treated with oral anti-neoplastic drugs from 2017 to 2022. Yearly prescriptions and expenditure were calculated according to their pharmacological classes, and trends were further analyzed. Defined daily doses (DDDs) and defined daily cost (DDC) of oral targeted anti-neoplastic drugs were also determined.

Results

Both the number of prescriptions and expenditure of oral anti-neoplastic drugs increased progressively. There was a significant upward trend in the number and proportion of prescriptions for the older adult group, male group, and patients with gynecologic/genitourinary and respiratory cancer. Hormonal therapy agents accounted for the highest proportion of prescriptions, and letrozole was initially the most frequently prescribed drug. The number of DDDs of total oral targeted anti-neoplastic drugs showed a continuously ascending trend, primarily driven by the usage of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) and BCR-ABL TKIs.

Conclusion

The prescriptions and expenditure of oral anti-neoplastic drugs, and the number of DDDs of oral targeted anti-neoplastic drugs all showed a progressively ascending trend. Further studies are needed to evaluate the long-term health and financial outcomes, and the factors influencing these prescribing patterns.

Optimisation of Solid-Phase Extraction and LC-MS/MS Analysis of Six Breast Cancer Drugs in Patient Plasma Samples

In the development of bioanalytical LC-MS methods for the determination of drugs in plasma samples in a clinical setting, adequate sample preparation is of utmost importance. The main goals are to achieve the selective extraction of the analytes of interest and attain thorough matrix removal while retaining acceptable ecological properties, cost-effectiveness, and high throughput. Solid-phase extraction (SPE) offers a versatile range of options, from the selection of an appropriate sorbent to the optimisation of the washing and elution conditions. In this work, the first SPE method for the simultaneous extraction of six anticancer drugs used in novel therapeutic combinations for advanced breast cancer treatment-palbociclib, ribociclib, abemaciclib, anastrozole, letrozole, and fulvestrant-was developed. The following sorbent chemistries were tested: octylsilyl (C8), octadecylsilyl (C18), hydrophilic-lipophilic balance (HLB), mixed-mode cation-exchange (MCX and X-C), and mixed-mode weak cation-exchange (WCX), with different corresponding elution solvents. The samples were analysed using LC-MS/MS, with a phenyl column (150 × 4.6 mm, 2.5 μm). The best extraction recoveries (≥92.3%) of all analytes were obtained with the C8 phase, using methanol as the elution solvent. The optimised method was validated in the clinically relevant ranges, showing adequate precision (inter-day RSD ≤ 14.3%) and accuracy (inter-day bias -12.7-13.5%). Finally, its applicability was successfully proven by the analysis of samples from breast cancer patients.

Therapeutic Drug Monitoring of Kinase Inhibitors in Oncology

Although kinase inhibitors (KI) frequently portray large interpatient variability, a 'one size fits all' regimen is still often used. In the meantime, relationships between exposure-response and exposure-toxicity have been established for several KIs, so this regimen could lead to unnecessary toxicity and suboptimal efficacy. Dose adjustments based on measured systemic pharmacokinetic levels-i.e., therapeutic drug monitoring (TDM)-could therefore improve treatment efficacy and reduce the incidence of toxicities. Therefore, the aim of this comprehensive review is to give an overview of the available evidence for TDM for the 77 FDA/EMA kinase inhibitors currently approved (as of July 1st, 2023) used in hematology and oncology. We elaborate on exposure-response and exposure-toxicity relationships for these kinase inhibitors and provide practical recommendations for TDM and discuss corresponding pharmacokinetic targets when possible.

Development and validation of an LC-MS/MS method to measure the BRAF inhibitors dabrafenib and encorafenib quantitatively and four major metabolites semi-quantitatively in human plasma

This article describes the development and validation of a liquid-chromatography coupled with tandem mass spectrometry (LC-MS/MS) assay for the simultaneous quantitation of the BRAF inhibitors dabrafenib and encorafenib, and semi-quantitation of their major metabolites (i.e., carboxy-dabrafenib, desmethyl-dabrafenib, hydroxy-dabrafenib, M42.5A) in human plasma. Analytes were extracted from human plasma by protein precipitation, followed by reversed phase high-performance liquid chromatography. Analyte detection was performed using tandem mass spectrometry with heated electrospray ionization operating in positive ion mode. The assay was validated in accordance with the current U.S. Food and Drug Administration Guidance on Bioanalytical Method Validation. Results showed that measurements were both accurate (94.6-112.0 %) and precise (within-run: 1.9-3.4 %; between-run: 1.7-12.0 %) spanning a concentration range of 5 to 2000 ng/mL for dabrafenib and 10 to 4000 ng/mL for encorafenib. Recoveries for these analytes were consistent with mean values ranging from 85.6 % to 90.9 %. The mean internal standard-normalized matrix factors for each drug ranged between 0.87 and 0.98 and were found to be precise (% RSD <6.4 %). Dabrafenib and encorafenib were stable in the final extract and in human plasma held under various storage conditions. The metabolites also passed the validation criteria for precision and selectivity. Finally, the clinical applicability of the assay was confirmed by (semi-)quantitation of all six analytes in plasma samples from cancer patients receiving standard-of-care treatment with dabrafenib and encorafenib. Reproducibility of the measured analyte concentrations in study samples was confirmed successfully by incurred sample reanalysis. In conclusion, this sensitive LC-MS/MS assay has been validated successfully and is suitable for therapeutic drug monitoring of dabrafenib and encorafenib and clinical pharmacokinetic studies with these BRAF inhibitors.

Unraveling Complexities in the Absorption and Disposition Kinetics of Abiraterone via Iterative PBPK Model Development and Refinement

BACKGROUND AND OBJECTIVE

Abiraterone is a first-in-class inhibitor of cytochrome P450 17A1 (CYP17A1), and its pharmacokinetic (PK) profile is susceptible to intrinsic and extrinsic variabilities. Potential associations between abiraterone concentrations and pharmacodynamic consequences in prostate cancer may demand further dosage optimization to balance therapeutic outcomes. Consequently, we aim to develop a physiologically based pharmacokinetic (PBPK) model for abiraterone via a middle-out approach to prospectively interrogate the untested, albeit clinically relevant, scenarios.

METHODS

To characterize in vivo hydrolysis of prodrug abiraterone acetate (AA) and supersaturation of abiraterone, in vitro aqueous solubility data, biorelevant measurements, and supersaturation and precipitation parameters were utilized for mechanistic absorption simulation. CYP3A4-mediated N-oxidation and sulfotransferase 2A1-catalyzed sulfation of abiraterone were subsequently quantified in human liver subcellular systems. Iterative PBPK model refinement involved evaluation of potential organic anion transporting polypeptide (OATP)-mediated abiraterone uptake in transfected cells in the absence and presence of albumin.

RESULTS

The developed PBPK model recapitulated the duodenal concentration-time profile of both AA and abiraterone after simulated AA administration. Our findings established abiraterone as a substrate of hepatic OATP1B3 to recapitulate its unbound metabolic intrinsic clearance. Further consideration of a transporter-induced protein-binding shift established accurate translational scaling factors and extrapolated the sinusoidal uptake process. Subsequent simulations effectively predicted the PK of abiraterone upon single and multiple dosing.

CONCLUSION

Our systematic development of the abiraterone PBPK model has demonstrated its application for the prospective interrogation of the individual or combined influences of potential interindividual variabilities influencing the systemic exposure of abiraterone.

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.

Status and Quality of Guidelines for Therapeutic Drug Monitoring Based on AGREE II Instrument

BACKGROUND

With the progress of therapeutic drug monitoring (TDM) technology and the development of evidence-based medicine, many guidelines were developed and implemented in recent decades.

OBJECTIVE

The aim was to evaluate the current status of TDM guidelines and provide suggestions for their development and updates based on Appraisal of Guidelines for Research and Evaluation (AGREE) II.

METHODS

The TDM guidelines were systematically searched for among databases including PubMed, Embase, China National Knowledge Infrastructure, Wanfang Data, and the Chinese biomedical literature service system and the official websites of TDM-related associations. The search period was from inception to 6 April 2023. Four researchers independently screened the literature and extracted data. Any disagreement was discussed and reconciled by another researcher. The quality of guidelines was assessed using the AGREE II instrument.

RESULTS

A total of 92 guidelines were included, including 57 technical guidelines, three management guidelines, and 32 comprehensive guidelines. The number of TDM guidelines has gradually increased since 1979. The United States published the most guidelines (20 guidelines), followed by China (15 guidelines) and the United Kingdom (ten guidelines), and 23 guidelines were developed by international organizations. Most guidelines are aimed at adult patients only, while 28 guidelines include special populations. With respect to formulation methods, there are 23 evidence-based guidelines. As for quality evaluation results based on AGREE II, comprehensive guidelines scored higher (58.16%) than technical guidelines (51.36%) and administrative guidelines (50.00%).

CONCLUSION

The number of TDM guidelines, especially technical and comprehensive ones, has significantly increased in recent years. Most guidelines are confronted with the problems of unclear methodology and low quality of evidence according to AGREE II. More evidence-based research on TDM and high-quality guideline development is recommended to promote individualized therapy.

Therapeutic Drug Monitoring (TDM) Implementation in Public Hospitals in Greece in 2003 and 2021: A Comparative Analysis of TDM Evolution over the Years

Therapeutic drug monitoring (TDM) is the clinical practice of measuring drug concentrations. TDM can be used to determine treatment efficacy and to prevent the occurrence or reduce the risk of drug-induced side effects, being, thus, a tool of personalized medicine. Drugs for which TDM is applied should have a narrow therapeutic range and exhibit both significant pharmacokinetic variability and a predefined target concentration range. The aim of our study was to assess the current status of TDM in Greek public hospitals and estimate its progress over the last 20 years. All Greek public hospitals were contacted to provide data and details on the clinical uptake of TDM in Greece for the years 2003 and 2021 through a structured questionnaire. Data from 113 out of 132 Greek hospitals were collected in 2003, whereas for 2021, we have collected data from 98 out of 122 hospitals. Among these, in 2003 and 2021, 64 and 51 hospitals, respectively, performed TDM. Antiepileptics and antibiotics were the most common drug categories monitored in both years. The total number of drug measurement assays decreased from 2003 to 2021 (153,313 ± 7794 vs. 90,065 ± 5698; p = 0.043). In direct comparisons between hospitals where TDM was performed both in 2003 and 2021 (n = 35), the mean number of measurements was found to decrease for most drugs, including carbamazepine (198.8 ± 46.6 vs. 46.6 ± 10.1, p < 0.001), phenytoin (253.6 ± 59 vs. 120 ± 34.3; p = 0.001), amikacin (147.3 ± 65.2 vs. 91.1 ± 71.4; p = 0.033), digoxin (783.2 ± 226.70 vs. 165.9 ± 28.9; p < 0.001), and theophylline (71.5 ± 28.7 vs. 11.9 ± 6.4; p = 0.004). Only for vancomycin, a significant increase in measurements was recorded (206.1 ± 96.1 vs. 789.1 ± 282.8; p = 0.012). In conclusion, our findings show that TDM clinical implementation is losing ground in Greek hospitals. Efforts and initiatives to reverse this trend are urgently needed.

CYP3A4*22 Genotype-Guided Dosing of Kinase Inhibitors in Cancer Patients

INTRODUCTION

A genetic variant explaining a part of the exposure of many kinase inhibitors (KIs) is the single nucleotide polymorphism (SNP) CYP3A4*22, resulting in less CYP3A4 enzyme activity. The primary aim of this study was to investigate if the systemic exposure is non-inferior after a dose reduction of KIs metabolized by CYP3A4 in CYP3A4*22 carriers compared to patients without this SNP (i.e., wildtype patients) receiving the standard dose.

METHODS

In this multicenter, prospective, non-inferiority study, patients were screened for the presence of CYP3A4*22. Patients with the CYP3A4*22 SNP received a 20-33% dose reduction. At steady state, a pharmacokinetic (PK) analysis was performed and compared to the PK results from wildtype patients treated with the registered dose using a two-stage individual patient data meta-analysis approach.

RESULTS

In total, 207 patients were included in the final analysis. The CYP3A4*22 SNP was found in 16% of the patients in the final analysis (n = 34). Most of the included patients received imatinib (37%) or pazopanib (22%) treatment. The overall geometric mean ratio (GMR) comparing the exposure of the CYP3A4*22 carriers to the exposure of the wildtype CYP3A4 patients was 0.89 (90% confidence interval: 0.77-1.03).

CONCLUSION

Non-inferiority could not be proven for dose reduction of KIs metabolized by CYP3A4 in CYP3A4*22 carriers compared to the registered dose in wildtype patients. Therefore, an up-front dose reduction based upon the CYP3A4*22 SNP for all KIs does not seem an eligible new way of personalized therapy.

TRIAL REGISTRATION

International Clinical Trials Registry Platform Search Portal; number NL7514; registered 11/02/2019.

Model-Informed Precision Dosing Software Tools for Dosage Regimen Individualization: A Scoping Review

BACKGROUND

Pharmacokinetic nomograms, equations, and software are considered the main tools available for Therapeutic Drug Monitoring (TDM). Model-informed precision dosing (MIPD) is an advanced discipline of TDM that allows dose individualization, and requires a software for knowledge integration and statistical calculations. Due to its precision and extensive applicability, the use of these software is widespread in clinical practice. However, the currently available evidence on these tools remains scarce.

OBJECTIVES

To review and summarize the available evidence on MIPD software tools to facilitate its identification, evaluation, and selection by users.

METHODS

An electronic literature search was conducted in MEDLINE, EMBASE, OpenAIRE, and BASE before July 2022. The PRISMA-ScR was applied. The main inclusion criteria were studies focused on developing software for use in clinical practice, research, or modelling.

RESULTS

Twenty-eight software were classified as MIPD software. Ten are currently unavailable. The remaining 18 software were described in depth. It is noteworthy that all MIPD software used Bayesian statistical methods to estimate drug exposure and all provided a population model by default, except NONMEN.

CONCLUSIONS

Pharmacokinetic software have become relevant tools for TDM. MIPD software have been compared, facilitating its selection for use in clinical practice. However, it would be interesting to standardize the quality and validate the software tools.

Framework for Implementing Individualised Dosing of Anti-Cancer Drugs in Routine Care: Overcoming the Logistical Challenges

Precision medicine in oncology involves identifying the 'right drug', at the 'right dose', for the right person. Currently, many orally administered anti-cancer drugs, particularly kinase inhibitors (KIs), are prescribed at a standard fixed dose. Identifying the right dose remains one of the biggest challenges to optimal patient care. Recently the Precision Dosing Group established the Accurate Dosing of Anti-cancer Patient-centred Therapies (ADAPT) Program to address individualised dosing; thus, use existing anti-cancer drugs more safely and efficiently. In this paper, we outline our framework, based on the Medical Research Council (MRC) framework, with a simple 6-step process and strategies which have led to the successful implementation of the ADAPT program in South Australia. Implementation strategies in our 6-step process involve: (1) Evaluate the evidence and identify the cancer drugs: Literature review, shadowing other experts, establishing academic partnerships, adaptability/flexibility; (2) Establishment of analytical equipment for drug assays for clinical purposes: assessment for readiness, accreditation, feasibility, obtaining formal commitments, quality assurance to all stakeholders; (3) Clinical preparation and education: educational material, conducted educational meetings, involve opinion leaders, use of mass media, promote network weaving, conduct ongoing training; (4) Blood collection, sample preparation and analyses: goods received procedures, critical control points (transport time); (5) Interpret and release results with recommendations: facilitate the relay of clinical data to providers; (6) Clinical application: providing ongoing consultation, identify early adopters, identify, and prepare champions. These strategies were selected from the 73 implementation strategies outlined in the Expert Recommendations for Implementing Change (ERIC) study. The ADAPT program currently provides routine plasma concentrations for patients on several orally administered drugs in South Australia and is currently in its evaluation phase soon to be published. Our newly established framework could provide great potential and opportunities to advance individualised dosing of oral anti-cancer drugs in routine clinical care.

Sensitivity enhancement of a Cu (II) metal organic framework-acetylene black-based electrochemical sensor for ultrasensitive detection of imatinib in clinical samples

Imatinib (IMB), an anticancer drug, is extensively used for chemotherapy to improve the quality of life of cancer patients. The aim of therapeutic drug monitoring (TDM) is to guide and evaluate the medicinal therapy, and then optimize the clinical effect of individual dosing regimens. In this work, a highly sensitive and selective electrochemical sensor based on glassy carbon electrode (GCE) modified with acetylene black (AB) and a Cu (II) metal organic framework (CuMOF) was developed to measure the concentration of IMB. CuMOF with preferable adsorbability and AB with excellent electrical conductivity functioned cooperatively to enhance the analytical determination of IMB. The modified electrodes were characterized using X-rays diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier transform infrared (FT-IR), ultraviolet and visible spectrophotometry (UV-vis), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), brunauer‒emmett‒teller (BET) and barrett‒joyner‒halenda (BJH) techniques. Analytical parameters such as the ratio of CuMOF to AB, dropping volumes, pH, scanning rate and accumulation time were investigated through cyclic voltammetry (CV). Under optimal conditions, the sensor exhibited an excellent electrocatalytic response for IMB detection, and two linear detection ranges were obatined of 2.5 nM-1.0 μM and 1.0-6.0 μM with a detection limit (DL) of 1.7 nM (S/N = 3). Finally, the good electroanalytical ability of CuMOF-AB/GCE sensor facilitated the successful determination of IMB in human serum samples. Due to its acceptable selectivity, repeatability and long-term stability, this sensor shows promising application prospects in the detection of IMB in clinical samples.

LC-MS/MS Method for the Quantification of PARP Inhibitors Olaparib, Rucaparib and Niraparib in Human Plasma and Dried Blood Spot: Development, Validation and Clinical Validation for Therapeutic Drug Monitoring

Poly (ADP-ribose) polymerase inhibitors (PARPis) are becoming increasingly meaningful in oncology, and their therapeutic drug monitoring (TDM) might be beneficial for patients. Several bioanalytical methods have been reported for PARPis quantification in human plasma, but advantages might be obtained using dried blood spot (DBS) as a sampling technique. Our aim was to develop and validate a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for olaparib, rucaparib, and niraparib quantification in both human plasma and DBS matrices. Additionally, we aimed to assess the correlation between the drug concentrations measured in these two matrices. DBS from patients was obtained using Hemaxis DB10 for volumetric sampling. Analytes were separated on a Cortecs-T3 column and detected with electrospray ionization (ESI)-MS in positive ionization mode. Validation was performed according to the latest regulatory guidelines, in the range (ng/mL) 140-7000 for olaparib, 100-5000 for rucaparib, and 60-3000 for niraparib, within the hematocrit (Hct) range 29-45%. The Passing-Bablok and Bland-Altman statistical analyses revealed a strong correlation between plasma and DBS for olaparib and niraparib. However, due to the limited amount of data, it was challenging to establish a robust regression analysis for rucaparib. To ensure a more reliable assessment, additional samples are required. The DBS-to-plasma ratio was used as a conversion factor (CF) without considering any patient-related hematological parameters. These results provide a solid basis for the feasibility of PARPis TDM using both plasma and DBS matrices.

Plasma Cabozantinib Level Measurement in Patients with Renal Cell and Hepatocellular Carcinomas Using a Simple HPLC-UV Method Suitable for Clinical Application

Cabozantinib, which is used to treat renal cell and hepatocellular carcinomas, is often associated with dose-dependent adverse events. Monitoring the levels of cabozantinib in the blood may maximize the therapeutic effect and prevent serious adverse events. In this study, we developed a high-performance liquid chromatography-ultraviolet (HPLC-UV) method of measuring plasma cabozantinib concentration. Human plasma samples (50 µL) were processed by simple deproteinization with acetonitrile, followed by chromatographic separation on a reversed-phase column with an isocratic mobile phase of 0.5% KH₂PO₄ (pH 4.5) and acetonitrile (43:57, v/v) at a flow rate of 1.0 mL/min, with a 250 nm ultraviolet detector. The calibration curve was linear over the concentration range (0.05-5 µg/mL) with a coefficient of determination of 0.99999. The accuracy of the assay ranged from -4.35% to 0.98%, and recovery was >96.04%. The measurement time was 9 min. These findings confirm the effectiveness of this HPLC-UV method for cabozantinib quantification in human plasma, which is sufficiently simple for use for monitoring patients in clinical settings.

A strategy for low-cost portable monitoring of plasma drug concentrations using a sustainable boron-doped-diamond chip

On-site monitoring of plasma drug concentrations is required for effective therapies. Recently developed handy biosensors are not yet popular owing to insufficient evaluation of accuracy on clinical samples and the necessity of complicated costly fabrication processes. Here, we approached these bottlenecks via a strategy involving engineeringly unmodified boron-doped diamond (BDD), a sustainable electrochemical material. A sensing system based on a ∼1 cm² BDD chip, when analysing rat plasma spiked with a molecular-targeting anticancer drug, pazopanib, detected clinically relevant concentrations. The response was stable in 60 sequential measurements on the same chip. In a clinical study, data obtained with a BDD chip were consistent with liquid chromatography-mass spectrometry results. Finally, the portable system with a palm-sized sensor containing the chip analysed ∼40 μL of whole blood from dosed rats within ∼10 min. This approach with the 'reusable' sensor may improve point-of-monitoring systems and personalised medicine while reducing medical costs.

A Physiologically Based Pharmacokinetic Model to Predict Determinants of Variability in Epirubicin Exposure and Tissue Distribution

BACKGROUND

Epirubicin is an anthracycline antineoplastic drug that is primarily used in combination therapies for the treatment of breast, gastric, lung and ovarian cancers and lymphomas. Epirubicin is administered intravenously (IV) over 3 to 5 min once every 21 days with dosing based on body surface area (BSA; mg/m²). Despite accounting for BSA, marked inter-subject variability in circulating epirubicin plasma concentration has been reported.

METHODS

In vitro experiments were conducted to determine the kinetics of epirubicin glucuronidation by human liver microsomes in the presence and absence of validated UGT2B7 inhibitors. A full physiologically based pharmacokinetic model was built and validated using Simcyp^® (version 19.1, Certara, Princeton, NJ, USA). The model was used to simulate epirubicin exposure in 2000 Sim-Cancer subjects over 158 h following a single intravenous dose of epirubicin. A multivariable linear regression model was built using simulated demographic and enzyme abundance data to determine the key drivers of variability in systemic epirubicin exposure.

RESULTS

Multivariable linear regression modelling demonstrated that variability in simulated systemic epirubicin exposure following intravenous injection was primarily driven by differences in hepatic and renal UGT2B7 expression, plasma albumin concentration, age, BSA, GFR, haematocrit and sex. By accounting for these factors, it was possible to explain 87% of the variability in epirubicin in a simulated cohort of 2000 oncology patients.

CONCLUSIONS

The present study describes the development and evaluation of a full-body PBPK model to assess systemic and individual organ exposure to epirubicin. Variability in epirubicin exposure was primarily driven by hepatic and renal UGT2B7 expression, plasma albumin concentration, age, BSA, GFR, haematocrit and sex.

Pharmacokinetic Boosting of Kinase Inhibitors

(1) Introduction: Pharmacokinetic boosting of kinase inhibitors can be a strategy to enhance drug exposure and to reduce dose and associated treatment costs. Most kinase inhibitors are predominantly metabolized by CYP3A4, enabling boosting using CYP3A4 inhibition. Kinase inhibitors with food enhanced absorption can be boosted using food optimized intake schedules. The aim of this narrative review is to provide answers to the following questions: Which different boosting strategies can be useful in boosting kinase inhibitors? Which kinase inhibitors are potential candidates for either CYP3A4 or food boosting? Which clinical studies on CYP3A4 or food boosting have been published or are ongoing? (2) Methods: PubMed was searched for boosting studies of kinase inhibitors. (3) Results/Discussion: This review describes 13 studies on exposure boosting of kinase inhibitors. Boosting strategies included cobicistat, ritonavir, itraconazole, ketoconazole, posaconazole, grapefruit juice and food. Clinical trial design for conducting pharmacokinetic boosting trials and risk management is discussed. (4) Conclusion: Pharmacokinetic boosting of kinase inhibitors is a promising, rapidly evolving and already partly proven strategy to increase drug exposure and to potentially reduce treatment costs. Therapeutic drug monitoring can be of added value in guiding boosted regimens.

Dose optimization strategy of the tyrosine kinase inhibitors imatinib, dasatinib, and nilotinib for chronic myeloid leukemia: From clinical trials to real-life settings

With the advent of tyrosine kinase inhibitors (TKIs), the treatment prospects of chronic myeloid leukemia (CML) have changed markedly. This innovation can lengthen the long-term survival of patients suffering from CML. However, long-term exposure to TKIs is accompanied by various adverse events (AEs). The latter affect the quality of life and compliance of patients with CML, and may lead to serious disease progression (and even death). Recently, increasing numbers of patients with CML have begun to pursue a dose optimization strategy. Dose optimization may be considered at all stages of the entire treatment, which includes dose reduction and discontinuation of TKIs therapy. In general, reduction of the TKI dose is considered to be an important measure to reduce AEs and improve quality of life on the premise of maintaining molecular responses. Furthermore, discontinuation of TKIs therapy has been demonstrated to be feasible and safe for about half of patients with a stable optimal response and a longer duration of TKI treatment. This review focuses mainly on the latest research of dose optimization of imatinib, dasatinib, and nilotinib in CML clinical trials and real-life settings. We consider dose reduction in newly diagnosed patients, or in optimal response, or for improving AEs, either as a prelude to treatment-free remission (TFR) or as maintenance therapy in those patients unable to discontinue TKIs therapy. In addition, we also focus on discontinuation of TKIs therapy and second attempts to achieve TFR.

New Targeted Drugs for Acute Myeloid Leukemia and Antifungals: Pharmacokinetic Challenges and Opportunities

BACKGROUND

Acute myeloid leukemia (AML) is a life-threatening disease whose treatment is made difficult by a number of mutations or receptor overexpression in the proliferating cellular clones. Life expectancy of patients diagnosed with new, relapsed-refractory, or secondary AML has been improved by drugs targeted at such moieties. Regrettably, however, clinical use of new AML drugs is complicated by pharmacokinetic interactions with other drugs the patient is exposed to.

SUMMARY

The most relevant drug-drug interactions (DDI) with clinical implications build on competition for or induction/inhibition of CYP3A4, which is a versatile metabolizer of a plethora of pharmacological agents. Here, we review DDI between AML drugs and the agents used to prevent or treat invasive fungal infections (IFI). The pathophysiology of AML, characterized by functionally defective white blood cells and neutropenic/immunosuppressive effects of concomitant induction chemotherapy, can in fact increase the risk of infectious complications, with IFI causing high rates of morbidity and mortality. Triazole antifungals, such as posaconazole, are strong inhibitors of CYP3A4 and may thus cause patient's overexposure to AML drugs that are metabolized by CYP3A4. We describe potential strategies to minimize the consequences of DDI between triazole antifungals and targeted therapies for AML and the role that collaboration between clinical pharmacologists, hematologists, and clinical or laboratory microbiologists may have in these settings.

KEY MESSAGES

Therapeutic drug monitoring and clinical pharmacology stewardship could represent two strategies that best express multidisciplinary collaboration for improving patient management.

Lonafarnib and everolimus reduce pathology in iPSC-derived tissue engineered blood vessel model of Hutchinson-Gilford Progeria Syndrome

Hutchinson-Gilford Progeria Syndrome (HGPS) is a rare, fatal genetic disease that accelerates atherosclerosis. With a limited pool of HGPS patients, clinical trials face unique challenges and require reliable preclinical testing. We previously reported a 3D tissue engineered blood vessel (TEBV) microphysiological system fabricated with iPSC-derived vascular cells from HGPS patients. HGPS TEBVs exhibit features of HGPS atherosclerosis including loss of smooth muscle cells, reduced vasoactivity, excess extracellular matrix (ECM) deposition, inflammatory marker expression, and calcification. We tested the effects of HGPS therapeutics Lonafarnib and Everolimus separately and together, currently in Phase I/II clinical trial, on HGPS TEBVs. Everolimus decreased reactive oxygen species levels, increased proliferation, reduced DNA damage in HGPS vascular cells, and improved vasoconstriction in HGPS TEBVs. Lonafarnib improved shear stress response of HGPS iPSC-derived endothelial cells (viECs) and reduced ECM deposition, inflammation, and calcification in HGPS TEBVs. Combination treatment with Lonafarnib and Everolimus produced additional benefits such as improved endothelial and smooth muscle marker expression and reduced apoptosis, as well as increased TEBV vasoconstriction and vasodilation. These results suggest that a combined trial of both drugs may provide cardiovascular benefits beyond Lonafarnib, if the Everolimus dose can be tolerated.

[Unusual association of BRAF and MEK inhibitors: Clinical response of metastatic melanoma treated with dabrafenib-cobimetinib]

Despite the efficacy of targeted therapies in melanoma, the management of adverse events with BRAFi and MEKi (inhibitors) is one of the limits of these treatments. Close monitoring is required to ensure efficacy and patient safety. In this case study, we report a patient treated for metastatic melanoma with an unusual and innovative combination of dabrafenib (BRAFi) and cobimetinib (MEKi), to manage pyrexia, and lead to complete remission for 19 months. This is the first case ever reported of metastatic melanoma treated with this off-label combination and characterized by the use of therapeutic drug monitoring.

A fast and validated LC-MS/MS method to quantify lenvatinib in dried blood spot

A new LC-MS/MS method for the quantification of lenvatinib (LENVA) in venous Dried Blood Spot (DBS) samples has been presented. This method is characterized by a short run time (4 min), requires a volumetric sampling of 10 µL and extraction of the entire spot to avoid hematocrit (Hct) and spot volume effects. The quantification method was successfully validated in the range of 5.00-2000 ng/mL on two different DBS filter papers (Whatman 31 ET CHR and Whatman 903) according to European Medicines Agency (EMA) and Food and Drug Administration (FDA) guidelines, European Bioanalysis Forum (EBF), and International Association of Therapeutic Drug Monitoring and Clinical Toxicology (IATDMCT) recommendations. During the validation process, the following parameters were evaluated: recovery (≥ 77% for both filter papers), absence of matrix effect, process efficiency (close to 72% for Whatman 31 ET CHR and close to 77% for Whatman 903), Hct effect (CV ≤ 6.3% and accuracy within 96-112%), linearity (r ≥ 0.998 for Whatman 31 ET CHR and r ≥ 0.999 for Whatman 903), intra- and inter-day precision (CV ≤ 8.8%) and accuracy (92.8-108%), selectivity and sensitivity, reproducibility with incurred samples reanalysis (ISR), and stability. This method was applied to quantify venous DBS samples from patients with hepatocellular carcinoma treated with LENVA enrolled in a cross-validation study (CRO-2018-83). A good correlation between LENVA plasma concentration determined by standard procedure and the new developed DBS LENVA method (R² ≥ 0.996) has been observed.

LC-MS/MS Application in Pharmacotoxicological Field: Current State and New Applications

Nowadays, it is vital to have new, complete, and rapid methods to screen and follow pharmacotoxicological and forensic cases. In this context, an important role is undoubtedly played by liquid chromatography-tandem mass spectrometry (LC-MS/MS) thanks to its advanced features. This instrument configuration can offer comprehensive and complete analysis and is a very potent analytical tool in the hands of analysts for the correct identification and quantification of analytes. The present review paper discusses the applications of LC-MS/MS in pharmacotoxicological cases because it is impossible to ignore the importance of this powerful instrument for the rapid development of pharmacological and forensic advanced research in recent years. On one hand, pharmacology is fundamental for drug monitoring and helping people to find the so-called "personal therapy" or "personalized therapy". On the other hand, toxicological and forensic LC-MS/MS represents the most critical instrument configuration applied to the screening and research of drugs and illicit drugs, giving critical support to law enforcement. Often the two areas are stackable, and for this reason, many methods include analytes attributable to both fields of application. In this manuscript, drugs and illicit drugs were divided in separate sections, with particular attention paid in the first section to therapeutic drug monitoring (TDM) and clinical approaches with a focus on central nervous system (CNS). The second section is focused on the methods developed in recent years for the determination of illicit drugs, often in combination with CNS drugs. All references considered herein cover the last 3 years, except for some specific and peculiar applications for which some more dated but still recent articles have been considered.