Impacts of genetic polymorphisms and cancer cachexia on naldemedine pharmacokinetics and bowel movements in patients receiving opioid analgesics.

BACKGROUND/OBJECTIVES: Clinical responses to naldemedine vary between individuals with advanced cancer. This is a prospective, single-center, observational study aimed to evaluate the influence of genetic polymorphisms and cachexia status on plasma naldemedine and clinical responses. METHODS: Forty-eight patients being treated with naldemedine for opioid-induced constipation under treatment of cancer pain were enrolled. Plasma naldemedine concentrations were determined on the fourth day or later after administration of naldemedine, and the associations with genotypes, cachexia status, and clinical responses were assessed. RESULTS: Cancer patients exhibited a large variation in the plasma naldemedine concentrations, and it was correlated with serum total protein level. Patients who were homozygous CYP3A5*3 had a higher plasma concentration of naldemedine than those with the *1 allele. ABCB1 genotypes tested in this study were not associated with plasma naldemedine. A negative correlation was observed between the plasma naldemedine concentration and 4ß-hydroxycholesterol level. The plasma naldemedine concentration was lower in patients with refractory cachexia than in those with precachexia and cachexia. While serum levels of interleukin-6 (IL-6) and acute-phase proteins were higher in patients with refractory cachexia, they were not associated with plasma naldemedine. A higher plasma concentration of naldemedine, CYP3A5*3/*3, and an earlier naldemedine administration after starting opioid analgesics were related to improvement of bowel movements. CONCLUSION: Plasma naldemedine increased under deficient activity of CYP3A5 in cancer patients. Cachectic patients with a higher serum IL-6 had a lower plasma naldemedine. Plasma naldemedine, related to CYP3A5 genotype, and the initiation timing of naldemedine were associated with improved bowel movements.

Associations of plasma aprepitant and its N-dealkylated metabolite with cachexia status and clinical responses in head and neck cancer patients.

PURPOSE: Oral aprepitant has a large interindividual variation in clinical responses in advanced cancer. This study aimed to characterize plasma aprepitant and its N-dealkylated metabolite (ND-AP) based on the cachexia status and clinical responses in head and neck cancer patients. METHODS: Fifty-three head and neck cancer patients receiving cisplatin-based chemotherapy with oral aprepitant were enrolled. Plasma concentrations of total and free aprepitant and ND-AP were determined at 24 h after a 3-day aprepitant treatment. The clinical responses to aprepitant and degrees of cachexia status were assessed using a questionnaire and Glasgow Prognostic Score (GPS). RESULTS: Serum albumin level was negatively correlated with the plasma concentrations of total and free aprepitant but not ND-AP. The serum albumin level had a negative correlation with the metabolic ratio of aprepitant. The patients with GPS 1 or 2 had higher plasma concentrations of total and free aprepitant than those with GPS 0. No difference was observed in the plasma concentration of ND-AP between the GPS classifications. The plasma interleukin-6 level was higher in patients with GPS 1 or 2 than 0. The absolute plasma concentration of free ND-AP was higher in patients without the delayed nausea, and its concentration to determine the occurrence was 18.9 ng/mL. The occurrence of delayed nausea had no relation with absolute plasma aprepitant. CONCLUSION: Cancer patients with a lower serum albumin and progressive cachectic condition had a higher plasma aprepitant level. In contrast, plasma free ND-AP but not aprepitant was related to the antiemetic efficacy of oral aprepitant.

Characterization of endogenous markers of hepatic function in patients receiving itraconazole treatment for prophylaxis of deep mycosis.

BACKGROUND: Long-term use of itraconazole (ITZ) is associated with a risk of inducing hepatotoxicity. This study aimed to evaluate the associations of plasma concentrations of ITZ and its hydroxylated metabolite (OH-ITZ) with endogenous markers of hepatic function. METHODS: Thirty six patients treated with oral ITZ solution for prophylaxis of deep mycosis were enrolled. Plasma concentrations of ITZ and OH-ITZ were determined on the 14th day or later after administration of ITZ. Their associations with endogenous marker levels of hepatic function including plasma coproporphyrin (CP)-I and OATP1B1 genotypes were assessed. RESULTS: The serum level of total bilirubin (T-Bil) was moderately correlated with the plasma concentration of total ITZ (tITZ) and OH-ITZ (tOH-ITZ). T-Bil elevation above 0.3 mg/dL was observed in 19% of patients, although statistically significant difference was not identified. The plasma concentration of tITZ had no correlation with other endogenous markers levels including AST, ALT, albumin, and plasma CP-I. The serum AST and plasma CP-I levels were correlated with the plasma concentration of free OH-ITZ (fOH-ITZ). T-Bil and plasma CP-I, a marker of OATP1B1 activity, were not correlated with each other, and neither was associated with the OATP1B1 genotypes. CONCLUSIONS: Plasma ITZ and OH-ITZ had a positive association with T-Bil. The patients with a higher fOH-ITZ level had lower OATP1B1 activity on the basis of plasma CP-I level. ITZ and OH-ITZ have the potential to slightly increase endogenous marker levels of hepatic function, although most likely by different mechanisms.

LC-MS/MS method for the quantitation of serum tocilizumab in rheumatoid arthritis patients using rapid tryptic digestion without IgG purification.

The quantitation of serum tocilizumab using liquid chromatography tandem-mass spectrometry (LC-MS/MS) method has not been widely applied in clinical settings because of its time-consuming and costly sample pretreatments. The present study aimed to develop a validated LC-MS/MS method for detecting serum tocilizumab by utilizing immobilized trypsin without an immunoglobulin G purification step and evaluate its applicability in the treatment of rheumatoid arthritis (RA) patients administered intravenously or subcutaneously with tocilizumab. The tocilizumab-derived signature peptide was deciphered using a nano-LC system coupled to a hybrid quadrupole-orbitrap mass spectrometer. The serum tocilizumab was rapidly digested by immobilized trypsin for 30 min. The chromatographic peak of the signature peptide and that of the internal standard were separated from the serum digests for a total run time of 15 min. The calibration curve of serum tocilizumab concentration was linear with a range of 2-200 µg/mL. The intra- and inter-day accuracy and relative standard deviation (RSD) were 90.7%-109.4% and <10%, respectively. The serum tocilizumab concentrations in the RA patients receiving intravenous and subcutaneous injections were 5.8-28.9 and 2.4-63.5 µg/mL, respectively. The serum tocilizumab concentrations using the current method positively correlated with those using the enzyme-linked immunosorbent assay, although a systematic error was observed between these methods. In conclusion, a validated LC-MS/MS method with minimal sample pretreatments for monitoring serum tocilizumab concentrations in RA patients was developed.

Impacts of cachexia progression in addition to serum IgG and blood lymphocytes on serum nivolumab in advanced cancer patients.

PURPOSE: Serum nivolumab concentrations exhibit a large variation in cancer patients. Cancer cachexia inducing systemic inflammation promotes the elimination of endogenous proteins, while its association with serum nivolumab remains unclear. The present study aimed to evaluate the impacts of cachexia progression in addition to blood components on serum nivolumab in cancer patients. METHODS: Thirty-eight non-small-cell lung cancer or renal cell cancer patients receiving biweekly intravenous nivolumab were enrolled. Blood samples were collected just before dosing at the 7th administration of nivolumab or later. Serum nivolumab together with serum proteins, inflammatory markers, and peripheral blood leukocytes were determined. Cancer cachexia was classified using the Glasgow Prognostic Score (GPS). Immune-related adverse events (irAEs) were monitored during the study period. RESULTS: Cancer patients had a large variation in serum nivolumab concentrations (interquartile range, 12-21 µg/mL per mg/kg). The serum nivolumab concentration was positively correlated with serum albumin, while negatively associated with serum globulin and immunoglobulin G (IgG). A negative correlation was observed between serum nivolumab and blood lymphocytes. Regarding cachexia progression, the patients with GPS 2 had a higher serum interleukin-6 concentration and a lower serum nivolumab concentration than those with GPS 0 or 1. The GPS, serum IgG, and blood lymphocytes were identified as independent variables for serum nivolumab. The incidence of irAEs was not associated with the nivolumab dose or serum nivolumab. CONCLUSION: Cachexia progression had a negative impact on serum nivolumab in cancer patients. The interindividual variation in serum nivolumab was characterized by cachexia progression in addition to blood components.

Correlations between serum cetuximab and EGFR-related markers, and skin disorders in head and neck cancer patients.

PURPOSE: Cetuximab inhibits epidermal growth factor receptor (EGFR) signaling in cancer and skin cells, thereby inducing anti-cancer effects and skin disorders. The present study aimed to evaluate the relationships between serum cetuximab and EGFR-related markers, and adverse effects in head and neck cancer patients. METHODS: Thirty-four head and neck cancer patients receiving weekly intravenous cetuximab were enrolled. Serum cetuximab levels were determined just before dosing. Blood samples for determination of serum EGFR-related markers including soluble epidermal growth factor receptor (sEGFR) and interleukin-6 (IL-6) were obtained. The severities of skin disorders, their medications, and hypomagnesemia treatment were also assessed. RESULTS: Serum levels of cetuximab and sEGFR were negatively and positively correlated with that of IL-6, respectively. The serum cetuximab level was twofold higher in the patients with a grade 2-3 skin rash than with a grade 0-1 rash. The serum cetuximab cutoff value related to severe skin rash was 71 µg/mL (sensitivity, 59%; and specificity, 94%). The use of a strong topical corticosteroid for skin rash was also associated with a higher serum cetuximab level. Serum levels of sEGFR and IL-6 had no correlations with the skin disorder severities or their medications. Hypomagnesemia treatment using intravenous magnesium sulfate was not related to serum cetuximab and EGFR-related markers. CONCLUSIONS: Head and neck cancer patients with a higher serum IL-6 level tended to have a lower serum cetuximab level. Serum cetuximab had positive correlations to skin rash severity and its medication in the study population.

Simple Liquid Chromatography-Tandem Mass Spectrometry Method for Quantitation of Total and Free Aprepitant and Its Active N-Dealkylated Metabolites in Human Plasma.

BACKGROUND: Aprepitant, an antiemetic selective neurokinin-1 receptor antagonist, is primarily metabolized to the active N-dealkylated form (ND-AP) and then converted to its carbonyl form (ND-CAP) in humans. This study developed a simple liquid chromatography-tandem mass spectrometry method using electrospray ionization for the quantitation of plasma total and free aprepitant and its N-dealkylated metabolites and used them to analyze patient plasma. METHODS: Free aprepitant and ND-AP in plasma were fractionated using centrifugal ultrafiltration. The analytes in plasma or their ultrafiltered specimens treated with triethylamine/acetonitrile were isocratically separated using a 3-µm octadecylsilyl column with a total run time of 10 minutes and scanned using positive ion electrospray ionization. RESULTS: The calibration curves of total aprepitant, ND-AP, and ND-CAP were prepared at concentration ranges of 50-2500, 20-1000, and 5-250 ng/mL, respectively, whereas that of free aprepitant and ND-AP were at a concentration range of 2-150 ng/mL. The intraassay and interassay accuracy and imprecision values were 93.5%-107.7% and 94.6%-103.3%, and 2.1%-7.5% and 1.0%-8.9%, respectively. Aprepitant and its metabolites did not exhibit any matrix effects or instabilities in the plasma specimens. In cancer patients receiving oral aprepitant, the plasma concentration ranges of total aprepitant, ND-AP, and ND-CAP, and free aprepitant and ND-AP were 137-2170, 104-928, 22.4-97.6, 8.11-60.0, and 3.53-56.0 ng/mL, respectively. The median plasma free fraction proportion of aprepitant and ND-AP was 4.14% and 4.90%, respectively. CONCLUSIONS: The present developed method showed an acceptable analytical performance and can be used to evaluate total and free aprepitant and its N-dealkylated metabolites in patient plasma.

Impact of CYP2D6 activity and cachexia progression on enantiomeric alteration of plasma tramadol and its demethylated metabolites and their relationships with central nervous system symptoms in head and neck cancer patients.

This study aimed to evaluate the influence of CYP2D6 activity and cachexia progression on the enantiomeric alteration of plasma tramadol and its demethylated metabolites in head and neck cancer patients. Fifty-three head and neck cancer patients receiving oral tramadol were enrolled. The plasma concentrations of tramadol, O-desmethyltramadol (ODT) and N-desmethyltramadol (NDT) enantiomers were determined. The CYP2D6 activity score (AS) and degree of cachexia progression were assessed according to genotype and the Glasgow Prognostic Score (GPS), respectively. The enantiomeric ratio of NDT was (+)-form dominant in all patients. CYP2D6 AS had negative correlations with the plasma concentrations of (+)-NDT and (-)-NDT. The plasma concentrations of (+)-tramadol and (+)-ODT were higher in patients with GPS 1 or 2 than in those with GPS 0. Lower metabolic ratios to NDT enantiomers were observed in patients with GPS 1 or 2. In patients with GPS 1 or 2, the plasma (-)-tramadol was associated with the incidence of central nervous system symptoms. In conclusion, CYP2D6 AS partially explained the contribution of CYP2D6 activity to plasma tramadol and its demethylated metabolite enantiomers. Additionally, cachexia progression elevated the plasma (+)-tramadol and (+)-ODT levels through the reduction of N-demethylation of (+)-tramadol.

LC-MS/MS method for denosumab quantitation in human serum with rapid protein digestion using immobilized trypsin.

BACKGROUND: Proteomics-based LC-MS/MS methods using trypsin solution have some problems including ion suppression and long protein digestion times. Few practical methods to quantify denosumab in human serum have been published. METHODOLOGY: Immunoglobulins in serum were extracted using immobilized protein G. Denatured, reduced and alkylated serum samples were digested with immobilized trypsin for 14 min. A denosumab-unique peptide was identified using a Fourier transform mass spectrometer as a signature peptide. The signature peptide was quantitated with a hybrid triple-quadrupole/linear ion-trap mass spectrometer. CONCLUSION: A rapid and practical proteomics-based LC-MS/MS method using immobilized trypsin for denosumab quantitation in human serum was developed. The present method has an acceptable analytical performance and can be helpful for the determination of serum denosumab in clinical settings.

Simple and rapid LC-MS/MS method for the absolute determination of cetuximab in human serum using an immobilized trypsin.

Proteomic approaches using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) without an immunopurification technique have not been applied to the determination of serum cetuximab. This study developed a simple and rapid LC-MS/MS method for the absolute determination of cetuximab in human serum and applied it to clinical settings. Surrogate peptides derived from cetuximab digests were selected using a Fourier transform mass spectrometer. Reduced-alkylated serum cetuximab without immunopurification was digested for 20minutes using immobilized trypsin, and the digestion products were purified by solid-phase extraction. The LC-MS/MS was run in positive ion multiple reaction monitoring mode. This method was applied to the determination of serum samples in head and neck cancer patients treated with cetuximab. The chromatographic run time was 10minutes and no peaks interfering with surrogate peptides in serum digestion products were observed. The calibration curve of absolute cetuximab in serum was linear over the concentration range of 4-200µg/mL. The lower limit of quantification of cetuximab in human serum was 4µg/mL. The intra-assay and inter-assay precision and accuracy were less than 13.2% and 88.0-100.7%, respectively. The serum concentration range of cetuximab was 19-140µg/mL in patients. The serum cetuximab concentrations in LC-MS/MS were correlated with those in ELISA (r=0.899, P <0.01) and the mean bias was 1.5% in cancer patients. In conclusion, the present simple and rapid method with acceptable analytical performance can be helpful for evaluating the absolute concentration of serum cetuximab in clinical settings.

Membrane transport mechanisms of choline in human intestinal epithelial LS180 cells.

The aim of the present study was to investigate the membrane transport mechanisms of choline using human intestinal epithelial LS180 cells. The mRNA of choline transporter-like proteins (CTLs) was expressed significantly in LS180 cells, and the rank order was CTL1 > CTL4 > CTL3 > CTL2 > CTL5. In contrast, the mRNA expression of other choline transporters, organic cation transporter (OCT) 1, OCT2 and high-affinity choline transporter 1 (CHT1), was considerably lower in LS180 cells. Five mm unlabelled choline, hemicolinium-3 and guanidine, but not tetraethylammonium, inhibited the cellular uptake of 100 µm choline in LS180 cells. The uptake of choline into LS180 cells was virtually Na(+)-independent. The uptake of choline was significantly decreased by acidification of the extracellular pH; however, it was not increased by alkalization of the extracellular pH. In addition, both acidification and alkalization of intracellular pH decreased the uptake of choline, indicating that the choline uptake in LS180 cells is not stimulated by the outward H(+) gradient. On the other hand, the uptake of choline was decreased by membrane depolarization along with increasing extracellular K(+) concentration. In addition, the Na(+)-independent uptake of choline was saturable, and the Km value was estimated to be 108 µm. These findings suggest that the uptake of choline into LS180 cells is membrane potential-dependent, but not outward H(+) gradient-dependent.

Pharmacokinetic variability of flecainide in younger Japanese patients and mechanisms for renal excretion and intestinal absorption.

The aims of the present study were to evaluate the variability of pharmacokinetics of flecainide in young Japanese patients and to investigate the mechanisms of renal excretion and intestinal absorption of the drug using cultured epithelial cells. First the plasma concentration data of flecainide was analysed in 16 Japanese patients aged between 0.07 and 18.30 years using a one-compartment model. Considerable interindividual variability was observed in the oral clearance (CL/F) and the apparent volume of distribution (V/F) of flecainide in the young patients. Flecainide was transported selectively in the basolateral-to-apical direction in P-glycoprotein-expressing renal epithelial LLC-GA5-COL150 cell monolayers. The uptake of flecainide into intestinal epithelial LS180 cells was decreased significantly by acidification of the extracellular medium, and was inhibited by tertiary amines, such as diphenhydramine and quinidine. These findings in the present study suggest that flecainide is excreted by P-glycoprotein in the renal tubule and is taken up by the postulated H(+)/tertiary amine antiporter in the intestine, and that functional variability of not only the hepatic drug-metabolizing enzymes, but also the transporters in the kidney and intestine, may be responsible for the interindividual variability of systemic clearance (CL) and/or the bioavailability (F) of flecainide.