A Novel LC-MS/MS Method for Therapeutic Drug Monitoring of Baricitinib in Plasma of Pediatric Patients.

BACKGROUND: Janus kinase inhibitors are antirheumatic immunosuppressive drugs that target intracellular Janus kinases (JAKs). Baricitinib is a selective and reversible orally administered JAK1/JAK2 inhibitor approved for treating rheumatoid arthritis, atopic dermatitis, and alopecia areata in adult patients. Expanded access to baricitinib has been approved for treating pediatric patients affected by rare Mendelian autoinflammatory diseases with type I interferon-mediated damage. Knowledge of the pharmacokinetic properties and target plasma levels of baricitinib in pediatric patients is limited. In this study, a novel LC-MS/MS method for measuring baricitinib in plasma, validated according to the ICH M10 guidelines, is presented. METHODS: Sample preparation was performed by adding 10 µL of IS working solution (150 ng/mL) and 200 µL of MeOH to each plasma sample. Chromatographic separation was conducted using a Thermo Scientific Accucore Polar Premium column (50 mm × 2.1 mm, i.d. 2.6 m). This method was applied to 7 real anonymous plasma samples obtained from pediatric patients treated with baricitinib at IRCCS Istituto Giannina Gaslini (Genoa, Italy). Patients of both sexes had a median age of 14 years (range, 10-17 years). RESULTS: The LC-MS/MS method resulted linear over wide concentration ranges (1.024-100 ng/mL) and was accurate and reproducible in the absence of matrix effects, allowing for robust, specific, and rapid quantification of baricitinib from a low amount of plasma (50 µL). The plasma concentration of baricitinib in the samples of the patients, expressed as mean ± SD, was 11.25 ± 10.86 ng/mL. CONCLUSIONS: This novel LC-MS/MS method is suitable for the therapeutic drug monitoring of baricitinib and can help guide therapy optimization in pediatric patients.

Optimising urinary catecholamine metabolite diagnostics for neuroblastoma.

INTRODUCTION: The analysis of urinary catecholamine metabolites is a cornerstone of neuroblastoma diagnostics. Currently, there is no consensus regarding the sampling method, and variable combinations of catecholamine metabolites are being used. We investigated if spot urine samples can be reliably used for analysis of a panel of catecholamine metabolites for the diagnosis of neuroblastoma. METHODS: Twenty-four-hour urine or spot urine samples were collected from patients with and without neuroblastoma at diagnosis. Homovanillic acid (HVA), vanillylmandelic acid (VMA), dopamine, 3-methoxytyramine, norepinephrine, normetanephrine, epinephrine and metanephrine were measured by high-performance liquid chromatography coupled with fluorescence detection (HPLC-FD) and/or ultra-performance liquid chromatography coupled with electrospray tandem mass spectrometry (UPLC-MS/MS). RESULTS: Catecholamine metabolite levels were measured in urine samples of 400 neuroblastoma patients (24-hour urine, n = 234; spot urine, n = 166) and 571 controls (all spot urine). Excretion levels of catecholamine metabolites and the diagnostic sensitivity for each metabolite were similar in 24-hour urine and spot urine samples (p > .08 and >.27 for all metabolites). The area under the receiver-operating-characteristic curve (AUC) of the panel containing all eight catecholamine metabolites was significantly higher compared to that of only HVA and VMA (AUC = 0.952 vs. 0.920, p = .02). No differences were observed in metabolite levels between the two analysis methods. CONCLUSION: Catecholamine metabolites in spot urine and 24-hour urine resulted in similar diagnostic sensitivities. The Catecholamine Working Group recommends the implementation of spot urine as standard of care. The panel of eight catecholamine metabolites has superior diagnostic accuracy over VMA and HVA.

Development of an Accurate Mass Retention Time Database for Untargeted Metabolomic Analysis and Its Application to Plasma and Urine Pediatric Samples.

Liquid-chromatography coupled to high resolution mass spectrometry (LC-HRMS) is currently the method of choice for untargeted metabolomic analysis. The availability of established protocols to achieve a high confidence identification of metabolites is crucial. The aim of this work is to describe the workflow that we have applied to build an Accurate Mass Retention Time (AMRT) database using a commercial metabolite library of standards. LC-HRMS analysis was carried out using a Vanquish Horizon UHPLC system coupled to a Q-Exactive Plus Hybrid Quadrupole-Orbitrap Mass Spectrometer (Thermo Fisher Scientific, Milan, Italy). The fragmentation spectra, obtained with 12 collision energies, were acquired for each metabolite, in both polarities, through flow injection analysis. Several chromatographic conditions were tested to obtain a protocol that yielded stable retention times. The adopted chromatographic protocol included a gradient separation using a reversed phase (Waters Acquity BEH C18) and a HILIC (Waters Acquity BEH Amide) column. An AMRT database of 518 compounds was obtained and tested on real plasma and urine samples analyzed in data-dependent acquisition mode. Our AMRT library allowed a level 1 identification, according to the Metabolomics Standards Initiative, of 132 and 124 metabolites in human pediatric plasma and urine samples, respectively. This library represents a starting point for future metabolomic studies in pediatric settings.

A Novel LC-MS/MS-Based Method for the Diagnosis of ADA2 Deficiency from Dried Plasma Spot.

Adenosine Deaminase 2 Deficiency (DADA2) (OMIM: 607575) is a monogenic, autoinflammatory disease caused by the loss of functional homozygous or heterozygous mutations in the ADA 2 gene (previously CECR1, Cat Eye Syndrome Chromosome Region 1). A timely diagnosis is crucial to start Anti-TNF therapies that are efficacious in controlling the disease. The confirmation of DADA2 is based on DNA sequencing and enzymatic assay. It is, thus, very important to have robust and reliable assays that can be rapidly utilized in specialized laboratories that can centralize samples from other centers. In this paper, we show a novel enzymatic assay based on liquid chromatography-tandem mass spectrometry that allows the accurate determination of the ADA2 enzyme activity starting from very small amounts of plasma spotted on filter paper (dried plasma spot). The method allows significantly distinguishing healthy controls from affected patients and carriers and could be of help in implementing the diagnostic workflow of DADA2.

High-dose versus low-dose tranexamic acid for paediatric craniosynostosis surgery: a double-blind randomised controlled non-inferiority trial.

BACKGROUND: Tranexamic acid (TXA) reduces blood loss and transfusion in paediatric craniosynostosis surgery. The hypothesis is that low-dose TXA, determined by pharmacokinetic modelling, is non-inferior to high-dose TXA in decreasing blood loss and transfusion in children. METHODS: Children undergoing craniosynostosis surgery were enrolled in a two-centre, prospective, double-blind, randomised, non-inferiority controlled trial to receive high TXA (50 mg kg-1 followed by 5 mg kg-1 h-1) or low TXA (10 mg kg-1 followed by 5 mg kg-1 h-1). Primary outcome was blood loss. Low dose was determined to be non-inferior to high dose if the 95% confidence interval (CI) for the mean difference in blood loss was above the non-inferiority margin of -20 ml kg-1. Secondary outcomes were transfusion, TXA plasma concentrations, and biological markers of fibrinolysis and inflammation. RESULTS: Sixty-eight children were included. Values were non-inferior regarding blood loss (39.4 [4.4] vs 40.3 [6.2] ml kg-1 [difference=0.9; 95% CI: -14.2, 15.9]) and blood transfusion (21.3 [1.6] vs 23.6 [1.5] ml kg-1 [difference=2.3; 95% CI: -2.1, 6.7]) between high-dose (n=32) and low-dose (n=34) groups, respectively. The TXA plasma concentrations during surgery averaged 50.2 (8.0) and 29.6 (7.6) µg ml-1. There was no difference in fibrinolytic and inflammatory biological marker concentrations. No adverse events were observed. CONCLUSIONS: Tranexamic acid 10 mg kg-1 followed by 5 mg kg-1 h-1 is not less effective than a higher dose of 50 mg kg-1 and 5 mg kg-1 h-1 in reducing blood loss and transfusion in paediatric craniosynostosis surgery. CLINICAL TRIAL REGISTRATION: NCT02188576.

Cannabidiol Determination on Peripheral Capillary Blood Using a Microsampling Method and Ultra-High-Performance Liquid Chromatography Tandem Mass Spectrometry with On-Line Sample Preparation.

The aim of this work is to evaluate volumetric absorptive microsampling (VAMS) from capillary blood as an alternative strategy for therapeutic drug monitoring (TDM) in patients treated with the newly available GW-purified form of cannabidiol (Epidiolex®). A fast ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) coupled to an online sample preparation system analysis was carried out on a Thermo Scientific Ultimate 3000 LC system coupled to a TSQ Quantiva triple quadrupole for the quantification of cannabidiol (CBD) and, in addition, delta-9-tetrahydrocannabinol (Δ9-THC). After validation using European Medicine Agency (EMA) guidelines the method was applied to samples obtained by finger prick of five pediatric patients treated with Epidiolex® and the results were compared to those obtained from venous blood and plasma. The method is linear in the range of 1-800 µg/L for both CBD and THC with intra- and inter-day precisions ranging from 5% to 14% and accuracies from -13% to +14% starting from 30 µL of sample. Stability in VAMS is ensured for up to 4 weeks at 25 °C thus allowing simple delivery. There was no difference (p = 0.69) between concentrations of CBD measured from VAMS sampled from capillary or venous blood (range: 52.19-330.14 or 72.15-383.45 µg/L) and those obtained from plasma (range: 64.3-374.09 µg/L) The VAMS-LC-MS/MS method represents a valid alternative strategy for therapeutic drug monitoring of patients treated with Epidiolex®.

Efficacy and Adverse Events During Janus Kinase Inhibitor Treatment of SAVI Syndrome.

OBJECTIVES: Mutations affecting the TMEM173 gene cause STING-associated vasculopathy with onset in infancy (SAVI). No standard immunosuppressive treatment approach is able to control disease progression in patients with SAVI. We studied the efficacy and safety of targeting type I IFN signaling with the Janus kinase inhibitor, ruxolitinib. METHODS: We used DNA sequencing to identify mutations in TMEM173 in patients with peripheral blood type I IFN signature. The JAK1/2 inhibitor ruxolitinib was administered on an off-label basis. RESULTS: We identified three patients with SAVI presenting with skin involvement and progressive severe interstitial lung disease. Indirect echocardiographic signs of pulmonary hypertension were present in one case. Following treatment with ruxolitinib, we observed improvements of respiratory function including increased forced vital capacity in two patients, with discontinuation of oxygen therapy and resolution of echocardiographic abnormalities in one case. Efficacy was persistent in one patient and only transitory in the other two patients. Clinical control of skin complications was obtained, and one patient discontinued steroid treatment. One patient, who presented with kidney involvement, showed resolution of hematuria. One patient experienced increased recurrence of severe viral respiratory infections. Monitoring of peripheral blood type I interferon signature during ruxolitinib treatment did not show a stable decrease. CONCLUSIONS: We conclude that targeting type I IFN receptor signaling may represent a promising therapeutic option for a subset of patients with SAVI syndrome and severe lung involvement. However, the occurrence of viral respiratory infection might represent an important cautionary note for the application of such form of treatment.

LC-MS/MS-Based Quantification of 9 Antiepileptic Drugs From a Dried Sample Spot Device.

BACKGROUND: Therapeutic drug monitoring (TDM) of antiepileptic drugs (AEDs) is commonly performed on plasma or serum. The use of dried plasma spots (DPSs) could represent a useful tool to facilitate sample shipment to reference laboratories. In this article, the authors describe the application of a commercially available UHPLC-MS/MS method for the determination of 9 commonly prescribed AEDs (levetiracetam, lacosamide, topiramate, ethosuximide, lamotrigine, rufinamide, zonisamide, primidone, and oxcarbazepine and its active metabolite 10-OH-monohydroxycarbazepine) to DPS collected on dried sample spot devices (DSSDs). METHOD: Fifty microliters of plasma were spotted on DSSD. After being air-dried at room temperature, they were extracted using an organic extraction solution containing the appropriate deuterated internal standards. The chromatographic separation was performed on a UHPLC reversed-phase C-18 column, and the analytes were quantified using a triple quadrupole mass spectrometer (LC-MS/MS). RESULTS: The assay was linear over the concentration ranges tested with a total runtime of 10.3 minutes. Recovery ranged from 93.7% to 106.8%. Intraday and interday precision for all quality control levels, including lower limit of quantification, ranged from 2.1% to 18.4% and 2.1% to 13.2%. Intraday and interday accuracy biases ranged from -11.7% to 14.3% and -9.2% to 8.0%. The absence of matrix effects was also tested and confirmed. Real samples derived from patients under therapy were also analyzed, and the comparison of results obtained from DSSD with those obtained from plasma showed that the 2 matrices were interchangeable. Stability tests performed on both quality controls, and real samples demonstrated that DSSDs can be easily stored and shipped at room temperature for 15 days. CONCLUSIONS: The application of the LC-MS/MS method allowed the authors to obtain a very specific, sensitive, and rapid (total runtime = 10.3 minutes) quantification of 9 AEDs starting from very low volumes of plasma samples. The main advantage of DPS over wet samples is room temperature storage and shipment, which lowers shipment costs and makes it suitable for routine TDM. Moreover, in comparison with other alternative matrices, DPS allows for the use of the same therapeutic ranges on which routine TDM is based. DPS on DSSD can thus be considered as a useful and cheap tool for the broader application of TDM.

Epidemiology of invasive fungal diseases in children with solid tumours undergoing autologous haematopoietic stem cell transplantation: a 10-year experience in a tertiary Italian centre.

The objective of the study was to determine the incidence of invasive fungal disease (IFD) in children undergoing autologous haematopoietic stem cell transplantation (auHSCT) for solid tumours (ST). Retrospective study on auHSCT was performed in children with ST (January 2006-December 2015). Data on the number of patient-days at risk (pdr) during the first 30 and 90 days after auHSCT and cases of proven/probable IFDs were collected. Infection rate (IR, episodes/1000 pdr) and proportions and cumulative risk (CR) of IFD were evaluated. In 186 patients, 270 auHSCT were performed, for a total of 8327 pdr during the first 30 days and 24 366 up to day 90. Median age was 5 years (interquartile range 2;8), 63% were male. At day 30, seven procedures were complicated by IFD, with an IR of 0.84 (95% CI 0.66-1.02) and aCR of 2.6% (95% CI 1.4-5.4) at 18 days after HSCT. Within day 90, two further IFDs were detected with an IR of 0.37 (95% CI -0.49 to 1.23) and a CR of 3.3% (95% CI 1.7-6.3) at day 69. Children undergoing auHSCT for ST have a low incidence of IFDs in the first 90 days after the procedure.

Performance of 1,3-ß-D-glucan for diagnosing invasive fungal diseases in children.

Plasma 1,3-ß-D-glucan (BDG) is indicated as a tool for early diagnosis of invasive fungal diseases (IFD). However, data on its diagnostic value are scarce in children. Therefore, definition of BDG test performance in paediatrics is needed. BDG was evaluated in children admitted to "Istituto Giannina Gaslini," Genoa, Italy, who developed clinical conditions at risk for IFD. Results were analysed for sensitivity, specificity, predictive values, likelihood ratios, accuracy, informedness and probability of missing one case by a negative test. A total of 1577 BDG determinations were performed on 255 patients (49% males, median age 5.4 years). Overall 46 IFD were diagnosed, 72% proven/probable. The test performance was evaluated for 80 pg/mL, 120 pg/mL, 200 pg/mL, 350 pg/mL, 400 pg/mL cut offs. Sensitivity was always <0.80 and specificity > 0.90 only for cut offs ≥200 pg/mL. Negative predictive value was ≥0.90 for all the cut offs evaluated, while positive predictive value resulted barely 0.50 (8% IFD prevalence). Accuracy was never >0.90, and informedness was at best 0.50. The risk of missing one IFD by a negative result was < 10%. Analyses in haemato-oncological or newborn patients did not show major differences. Detection of serum BDG does not appear a valuable adjunctive diagnostic tool for IFD in paediatrics.

What Is the Best Initial Empirical Treatment of Suspected Sepsis in a Newborn Readmitted Soon after Discharge Home in an Era of Increased Resistance to Antibiotics? A Report of Two Cases.

Background Colonization/infection by antibiotic-resistant bacteria is becoming a major threat to health care systems. Case report Two septic neonates were readmitted in our hospital few days after hospital discharge. In both of them, microbiological workup revealed an infection caused by multiresistant pathogens. Noteworthy, one baby had received intensive care management for 4 weeks, whereas the other had been vaginally delivered and sent home on his second day of life. Conclusion These cases suggest that in countries and/or hospital with high prevalence of colonization/infection by resistant pathogens in nurseries, neonatal intensive care units, and obstetric wards, the choice of initial therapy of suspected sepsis in a neonate readmitted from home soon after discharge should take into account the possibility of an infection due to a multiresistant pathogen.

Primary intestinal mold infection in children with solid tumors: a case report in an adolescent with Ewing sarcoma, and literature review.

We report a case of primary intestinal infection due to filamentous fungi in an adolescent with Ewing sarcoma. The clinical picture was that of peritonitis secondary to intestinal perforation and the diagnosis was established only on histopathological bases. This condition is very rare, and only one case of primary intestinal mold infection in children with solid tumors has been reported in the literature, although more records can be found describing similar conditions in other cancer patient populations (i.e. adults with solid tumors or children with hematological malignancies or patients receiving hemopoietic stem cell transplant). Clinicians must be aware of this possibility since only an aggressive medical and surgical approach can improve patients' prognosis.

Quantification of micafungin in human plasma by liquid chromatography-tandem mass spectrometry.

Micafungin (MCF) is an antifungal agent of the echinocandin class approved in Europe both in adults and in children for the treatment of invasive candidiasis. Few analytical methods for therapeutic drug monitoring (TDM) of this drug have been described so far. In this paper, we describe a rapid and validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for the measurement of MCF in plasma. MCF was analyzed in 100-µL plasma samples over a wide range of concentrations (0.1-20 µg/mL) by LC-MS/MS after protein precipitation. The suitability of the assay for TDM was evaluated by using plasma samples from pediatric patients who received MCF for the treatment of invasive candidiasis. The overall turnaround time for the assay was 20 min. The lower limit of quantification of the method was 0.1 ng/mL. No ion suppression due to matrix effects was found with different pre-analytical conditions, such as hemolysis, lipemia, and hyperuricemia. A simple and rapid LC-MS/MS method which provides high specificity, precision, and accuracy for quantification of MCF in plasma has been developed and validated.

Dose optimization and target attainment of vancomycin in children.

Vancomycin is a glycopeptide antibiotic that has been adopted in clinical practice to treat gram-positive infections for more than 70 years. Despite vancomycin's long history of therapeutic use, optimal dose adjustments and pharmacokinetic/pharmacodynamic (PK/PD) target attainment in children are still under debate. Therapeutic drug monitoring (TDM) has been widely integrated into pediatric clinical practice to maximize efficacy and safety of vancomycin treatment. Area under the curve (AUC)-guided TDM has been recently recommended instead of trough-only TDM to ensure PK/PD target attainment of AUC0-24h/minimal inhibitory concentration (MIC) > 400 to 600 and minimize acute kidney injury risk. Bayesian forecasting in pediatric patients allows estimation of population PK to accurately predict individual vancomycin concentrations over time, and consequently total vancomycin exposure. AUC-guided TDM for vancomycin, preferably with Bayesian forecasting, is therefore suggested for all pediatric age groups and special pediatric populations. In this review we aim to analyze the current literature on the pediatric use of vancomycin and summarize the current knowledge on dosing optimization for target attainment in special patient populations.

Therapeutic drug monitoring of glycopeptide antimicrobials: An overview of liquid chromatography-tandem mass spectrometry methods.

Therapeutic drug monitoring (TDM) is a critical clinical tool used to optimize the safety and effectiveness of drugs by measuring their concentration in biological fluids. These fluids are primarily plasma or blood. TDM, together with real-time dosage adjustment, contributes highly to the successful management of glycopeptide antimicrobial therapies. Understanding pharmacokinetic/pharmacodynamic (PK/PD) properties is vital for optimizing antimicrobial therapies, as the efficacy of these therapies depends on both the exposure of the patient to the drug (PK) and pharmacodynamic (PD) parameters such as the in vitro estimated minimum drug concentration that inhibits bacterial growth (MIC). Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) is widely recognized as the gold standard for measuring small molecules, such as antibiotics. This review provides a comprehensive overview of LC-MS/MS methods available for TDM of glycopeptide antibiotics, including vancomycin, teicoplanin, dalbavancin, oritavancin, and telavancin.

Innovative LC-MS/MS method for therapeutic drug monitoring of fenfluramine and cannabidiol in the plasma of pediatric patients with epilepsy.

We present a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying fenfluramine (FFA), its active metabolite norfenfluramine (norFFA), and Epidyolex®, a pure cannabidiol (CBD) oral solution in plasma. Recently approved by the EMA for the adjunctive treatment of refractory seizures in patients with Dravet and Lennox-Gastaut syndromes aged above 2 years, FFA and CBD still do not have established therapeutic blood ranges, and thus need careful drug monitoring to manage potential pharmacokinetic and pharmacodynamic interactions. Our method, validated by ICH guidelines M10, utilizes a rapid extraction protocol from 100 µL of human plasma and a reversed-phase C-18 HPLC column, with deuterated internal standards. The Thermofisher Quantiva triple-quadrupole MS coupled with an Ultimate 3000 UHPLC allowed multiple reaction monitoring detection, ensuring precise analyte quantification. The assay exhibited linear responses across a broad spectrum of concentrations: ranging from 1.64 to 1000 ng/mL for both FFA and CBD, and from 0.82 to 500 ng/mL for norFFA. The method proves accurate and reproducible, free from matrix effect. Additionally, FFA stability in plasma at 4 °C and -20 °C for up to 7 days bolsters its clinical applicability. Plasma concentrations detected in patients samples, expressed as mean ± standard deviation, were 0.36 ± 0.09 ng/mL for FFA, 19.67 ± 1.22 ng/mL for norFFA. This method stands as a robust tool for therapeutic drug monitoring (TDM) of FFA and CBD, offering significant utility in assessing drug-drug interactions in co-treated patients, thus contributing to optimized patient care in complex therapeutic scenarios.