Simultaneous quantification of baloxavir marboxil and its active metabolite in human plasma using UHPLC-MS/MS: Application to a human pharmacokinetic study with different anticoagulants.

Baloxavir marboxil (BXM) is a cap-dependent nucleic acid endonuclease inhibitor, which exerts its antiviral effects after being metabolized to its active form baloxavir acid (BXA). Ethylenediamine tetra-acetic acid (EDTA) and heparin are the two most used anticoagulants in clinical blood sample collection to estimate drug levels in plasma. However, compared to heparin plasma, there is a lack of clinical pharmacokinetic data of BXA using EDTA anticoagulant tubes for blood collection. In the present study, an efficient, rapid, and sensitive ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for simultaneous quantification of BXM and its active metabolite BXA in human plasma with its isotopic baloxavir-d5 (BXA-d5) as internal standard (IS). Plasma samples (50 µL) were undergone using acetonitrile containing 0.1 % formic acid a precipitant. Chromatographic separation was achieved by a Waters XBridge®C8 (2.1 mm × 50 mm, 2.5 µm) column. The gradient mobile phase was 0.1 % formic acid in water (A, pH 2.8) and 0.1 % formic acid in acetonitrile (B) and delivered at a flow rate of 0.6 mL/min for 4.5 min. BXM and BXA were monitored using a positive electrospray triple quadrupole mass spectrometer (TRIPLE QUAD™ 6500+) via multiple reaction monitoring mode. The mass-to-charge ratios (m/z) were 572.2→247.0, 484.2→247.0 and 489.2→252.0 for BXM, BXA, and BXA-d5 (IS). Calibration curves exhibited excellent linearity in the range of 0.1-10 ng/mL for BXM (r2 > 0.996), and 0.3-300 ng/mL for BXA (r2 > 0.998). Within-run and between-run precisions in coefficients of variations were less than 11.62 % for BXM and less than 7.47 % for BXA, and accuracies in relative error were determined to be within -7.78 % to 5.70 % for BXM and -6.67 % to 8.56 % for BXA. Extraction recovery efficiency was 92.76 % for BXM, 95.32 % for BXA, and 99.26 % for BXA-d5, respectively. The matrix effect of BXM and BXA was in line with the requirements, where the relative deviation of the accuracy was less than 6.67 % and the precision was less than 6.69 %. The validated efficient and simple UHPLC-MS/MS method was successfully used in the pharmacokinetic study of BXM and BXA in healthy human volunteers with K2EDTA and heparin tubes for blood collection. EDTA might compete with BXA for chelating metal ions and thereby decrease the plasma ratio in whole blood, leading to approximately 50 % lower measurement of pharmacokinetic parameters as compared with those obtained from heparin plasma anticoagulant tubes.

Development of an extended action fostemsavir lipid nanoparticle.

An extended action fostemsavir (FTR) lipid nanoparticle (LNP) formulation prevents human immunodeficiency virus type one (HIV-1) infection. This FTR formulation establishes a drug depot in monocyte-derived macrophages that extend the drug's plasma residence time. The LNP's physicochemical properties improve FTR's antiretroviral activities, which are linked to the drug's ability to withstand fluid flow forces and levels of drug cellular internalization. Each is, in measure, dependent on PEGylated lipid composition and flow rate ratios affecting the size, polydispersity, shape, zeta potential, stability, biodistribution, and antiretroviral efficacy. The FTR LNP physicochemical properties enable the drug-particle's extended actions.

Discovery of baloxavir sodium as a novel anti-CCHFV inhibitor: Biological evaluation of in vitro and in vivo.

Crimean-Congo hemorrhagic fever virus (CCHFV) is a highly pathogenic bunyavirus with a fatality rate of up to 40%. Currently, there are no licensed antiviral drugs for the treatment of CCHF; thus, the World Health Organization (WHO) listed the disease as a priority. A unique viral transcription initiation mechanism called "cap-snatching" is shared by influenza viruses and bunyaviruses. Thus, we tested whether baloxavir (an FDA-approved anti-influenza drug that targets the "cap-snatching" mechanism) could inhibit CCHFV infection. In cell culture, baloxavir acid effectively inhibited CCHFV infection and targeted CCHFV RNA transcription/replication. However, it has weak oral bioavailability. Baloxavir marboxil (the oral prodrug of baloxavir) failed to protect mice against a lethal dose challenge of CCHFV. To solve this problem, baloxavir sodium was synthesized owing to its enhanced aqueous solubility and pharmacokinetic properties. It consistently and significantly improved survival rates and decreased tissue viral loads. This study identified baloxavir sodium as a novel scaffold structure and mechanism of anti-CCHF compound, providing a promising new strategy for clinical treatment of CCHF after further optimization.

Hepatic Dysfunction Quantified by HepQuant DuO Outperforms Child-Pugh Classification in Predicting the Pharmacokinetics of Ampreloxetine.

HepQuant tests quantify liver function from clearance of deuterium- and 13C-labeled cholates administered either intravenously and orally (SHUNT) or orally (DuO). Hepatic impairment studies have relied on clinical or laboratory criteria like Child-Pugh classification to categorize the degree of hepatic dysfunction. We compared HepQuant tests with Child-Pugh classification in predicting the pharmacokinetics of ampreloxetine. Twenty-one subjects with hepatic impairment (8 Child-Pugh A, 7 Child-Pugh B, and 6 Child-Pugh C), and 10 age- and sex-matched controls were studied. The pharmacokinetics of ampreloxetine were measured after oral administration of a single dose of 10 mg. Disease severity index (DSI), portal-systemic shunting (SHUNT%), hepatic reserve, and hepatic filtration rates (HFRs) were measured from serum samples obtained after intravenous administration of [24-13C]-cholate and oral administration of [2,2,4,4-2H]cholate. Ampreloxetine plasma exposure (AUC0-inf) was similar to controls in Child-Pugh A, increased 1.7-fold in subjects with Child-Pugh B, and 2.5-fold in subjects with Child-Pugh C and correlated with both Child-Pugh score and HepQuant parameters. The variability observed in ampreloxetine exposure (AUC0-inf) in subjects with moderate (Child-Pugh B) and severe hepatic impairment (Child-Pugh C) was explained by HepQuant parameters. Multivariable regression models demonstrated that DSI, SHUNT%, and Hepatic Reserve from SHUNT and DuO were superior predictors of ampreloxetine exposure (AUC0-inf) compared to Child-Pugh score. HepQuant DSI, SHUNT%, and hepatic reserve were more useful predictors of drug exposure than Child-Pugh class for ampreloxetine and thus may better optimize dose recommendations in patients with liver disease. The simple-to-administer, oral-only DuO version of the HepQuant test could enhance clinical utility.

Pharmacology and pharmacokinetics of tazemetostat.

Tazemetostat, a novel oral selective inhibitor of enhancer of zeste homolog 2 (EZH2), was approved by the Food and Drug Administration (FDA) in 2020 for use in patients with advanced epithelioid sarcoma or relapsed/refractory (R/R) EZH2-mutated follicular lymphoma. These indications were approved by the FDA trough accelerated approval based on objective response rate and duration of response that resulted from phase 2 clinical trials. Tazemetostat competes with S-adenosylmethionine (SAM) cofactor to inhibit EZH2, reducing the levels of trimethylated lysine 27 of histone 3 (H3K27me3), considered as pharmacodynamic marker. Tazemetostat is orally bioavailable, characterized by rapid absorption and dose-proportional exposure, which is not influenced by coadministration with food or gastric acid reducing agents. It highly distributes in tissues, but with limited access to central nervous system. Tazemetostat is metabolized by CYP3A in the liver to 3 major inactive metabolites (M1, M3, and M5), has a short half-life and is mainly excreted in feces. Drug-drug interactions were shown with moderate CYP3A inhibitors as fluconazole, leading the FDA to recommend a 50% dose reduction, while studies investigating coadministration of tazemetostat with strong inhibitors/inducers are ongoing. No dosage modifications are recommended based on renal or hepatic dysfunctions. Overall, tazemetostat is the first-in-class EZH2 inhibitor approved by the FDA for cancer treatment. Current clinical studies are evaluating combination therapies in patients with several malignancies.

A Pharmacokinetics-Time to Alleviation of Symptoms Model to Support Extrapolation of Baloxavir Marboxil Clinical Efficacy in Different Ethnic Groups with Influenza A or B.

Baloxavir marboxil, the prodrug of baloxavir acid, is an anti-influenza antiviral. Here, a pharmacokinetics-time to alleviation of symptoms (PK-TTAS) model was developed and used to (I) characterize the PK-TTAS relationship, (II) quantify the impact of covariates, and (III) predict TTAS in different ethnic groups. Data from 1781 otherwise-healthy (OwH) or high-risk (HR) patients included in phase II (JapicCTI-153090) and III studies (NCT02954354 and NCT02949011) were used; patients received either placebo or oral baloxavir marboxil. The natural distribution of TTAS in placebo-treated patients was modeled, then TTAS data from the baloxavir marboxil arms were added to model the impact of baloxavir acid concentration on TTAS. PK parameters estimated by a population PK model and informed by phase I data (NCT03959332 and KCT0003535) were included to simulate TTAS in Chinese and South Korean patients. Composite symptom score at baseline (TSS0), ethnicity, sex, and patient type (OwH or HR) significantly impacted the natural TTAS distribution. TTAS reduced with increasing baloxavir acid concentrations. Compared with placebo, high and low baloxavir acid exposures (AUC0-inf 5.13-16.65 and 0.72-5.13 µg.hr/mL, respectively) significantly reduced TTAS; no covariates affected the drug effect on TTAS. Simulated TTAS was similar between OwH or HR Chinese, South Korean, and other Asian patients, with median reductions from placebo between 18.3-18.8 hours and 21.2-22.0 hours in OwH and HR patients, respectively, assuming TSS0 > 10. Ethnicity (Asian vs. non-Asian) did not significantly impact the drug effect on TTAS; predicted TTAS was similar across different Asian populations. This suggests Chinese and South Korean patients may benefit from similar efficacy as other Asian patients.

Rivaroxaban population pharmacokinetic and pharmacodynamic modeling in Iranian patients.

WHAT IS KNOWN AND OBJECTIVE: Although predictable pharmacokinetic and pharmacodynamic of rivaroxaban allow fixed dosing regimens without routine coagulation monitoring, there is still the necessity to monitor and predict the effects of rivaroxaban in specific conditions and different populations. The current study was designed and conducted to analyze the rivaroxaban population pharmacokinetics in Iranian patients and establish a pharmacokinetic/pharmacodynamic model to predict the relationship between rivaroxaban concentration and its anticoagulant activity. METHODS: A sequential nonlinear mixed effect pharmacokinetic/pharmacodynamic modeling method was used to establish the relation between rivaroxaban concentration and anti-factor Xa activity, prothrombin time, and activated partial thromboplastin time (aPTT) as pharmacodynamic biomarkers in a population of sixty-nine Iranian patients under treatment with oral rivaroxaban. Rivaroxaban plasma concentration was quantified by a validated high-performance liquid chromatography-tandem mass spectrometry. RESULTS AND DISCUSSION: The typical population values (inter-individual variability%) of the oral volume of distribution and clearance for a one-compartment model were 61.2 L (21%) and 3.68 L·h-1 (61%), respectively. Creatinine clearance and Child-Turcotte-Pugh score were found to affect the clearance. A direct link linear structural model best fitted the data for both prothrombin time and aPTT. The baseline estimates of aPTT and prothrombin time in the population were 35.0 (15%) and 12.6 (2%) seconds, respectively. The slope of the relationship between apTT, prothrombin time, and rivaroxaban concentration was 0.033 (28%) and 0.018 (54%) s·ml·ng-1 , respectively. The selected model for anti-factor Xa activity consisted of a direct link inhibitory Emax model with Hill coefficient. The maximum level of inhibition (Emax ) was 4 IU·ml-1 . The concentration of rivaroxaban producing 50% of the maximum inhibitory effect (EC50 ) was 180 (24%) ng·ml-1 , and Hill coefficient (γ) was 1.44 (108%). No covariates showed a statistically significant effect on PT and activated partial thromboplastin time prolonging properties and anti-factor Xa activity. WHAT IS NEW AND CONCLUSION: Our results confirmed that pharmacokinetic/pharmacodynamic models similar to those of the other studies describe the relationship between the rivaroxaban concentration and its anticoagulant effect in Iranian patients. However, considerable differences were observed in the parameters of the pharmacodynamics-pharmacokinetic models with the results of other reports that can explain the unpredictable effects of rivaroxaban in some patients.

Population Pharmacokinetics Analysis of Pemigatinib in Patients With Advanced Malignancies.

Pemigatinib is a fibroblast growth factor receptor 1-3 inhibitor used to treat cholangiocarcinoma. A compartmental population pharmacokinetics model was developed using data from 318 patients with cancer enrolled in a phase 1 dose-escalation/dose-expansion study, a phase 1 Japanese PK bridging study, and a phase 2 cholangiocarcinoma study. The final model for pemigatinib was a 2-compartment disposition model with first-order absorption and linear elimination. All fixed- and random-effect parameters were estimated with good precision, and no apparent biases in the overall model fit were observed. For females, the estimated typical pemigatinib absorption rate constant (ka ) and oral clearance (CL/F) were estimated (1.49 L/h and 10.3 L/h, respectively). For males, the typical apparent clearance and ka are 19.0% higher and 56.5% lower, respectively, compared with females. Typical apparent volume of distribution of the central compartment (Vc /F) and peripheral compartment for a 73.3-kg patient was estimated to be 122.0 L and 80.1 L, respectively; both increased with body weight. Phosphate binder coadministration decreases typical pemigatinib CL/F by 14.1%. Proton pump inhibitor coadministration increases typical pemigatinib apparent Vc/F by 24.4%. Phosphate binders and sex contribute a <20% change to CL/F. The impact of the investigated covariates on pemigatinib pharmacokinetics are not clinically significant.

Inhibiting the Activity of ABCG2 by KU55933 in Colorectal Cancer.

BACKGROUND: Therapeutic resistance is a frequent problem of cancer treatment and a leading cause of mortality in patients with metastatic colorectal cancer (CRC). Recent insight into the mechanisms that confer multidrug resistance has elucidated that the ATP-binding cassette (ABC) superfamily G member 2 (ABCG2) assists cancer cells in escaping therapeutic stress caused by toxic chemotherapy. Therefore, it is necessary to develop ABCG2 inhibitors. OBJECTIVES: In the present study, we investigated the inhibitory effect of KU55933 on ABCG2 in CRC. METHODS: The cytotoxicity assay and drug accumulation assay were used to examine the inhibitory effect of KU55933 on ABCG2. The protein expressions were detected by Western blot assay. The docking assay was performed to predict the binding site and intermolecular interactions between KU55933 and ABCG2. RESULTS: KU55933 was more potent than the known ABCG2 inhibitor fumitremorgin C to enhance the sensitivity of mitoxantrone and doxorubicin and the intracellular accumulation of mitoxantrone, doxorubicin and rhodamine 123 inside CRC cells with ABCG2 overexpression. Moreover, KU55933 did not affect the protein level of ABCG2. Furthermore, the docking data showed that KU55933 was tightly located in the drug-binding pocket of ABCG2. CONCLUSION: In summary, our data presented that KU55933 could effectively inhibit the drug pump activity of ABCG2 in colorectal cancer, which is further supported by the predicted model that showed the hydrophobic interactions of KU55933 within the drug-binding pocket of ABCG2. KU55933 can potently inhibit the activity of ABCG2 in CRC.

Dose-dependent bioavailability and tissue distribution of the ATR inhibitor AZD6738 (ceralasertib) in mice.

PURPOSE: Ataxia telangiectasia and Rad3-related (ATR) initiates and regulates cellular responses to DNA damage, such as those caused by cancer treatments. Several ATR inhibitors (ATRi) are in clinical development including AZD6738. Therapeutic indices among ATRi may differ as a result of varying potencies and concentrations at both tumor and off-target sites. Additionally, AZD6738 contributes to anti-tumor immune responses necessitating evaluation of exposure at immunological sites. METHODS: Using mouse models and a highly sensitive LC-MS/MS assay, the pharmacokinetics of AZD6738 were studied, including dose linearity, bioavailability, metabolism, and tissue distribution in tumor-bearing mice. RESULTS: Initial studies identified dose-dependent bioavailability, with greater than proportional increases in exposure as dose increased resulting in a ~ twofold increase in bioavailability between the lowest and highest investigated doses. These behaviors were successfully captured with a compartmental PK model. Analysis of metabolite PK revealed decreasing metabolic ratios with increasing dose, indicative of saturable first-pass metabolism. Further analysis revealed that intestinal and gut metabolism contribute to metabolism and these saturable mechanisms. Studies of tumor and tissue distribution found rapid and extensive drug distribution to most tissues except brain and spinal cord. CONCLUSION: The complex non-linear behavior of AZD6738 PK in mice was due to pre-systemic saturation and which appears to be recapitulated clinically at low doses. PK reported here will allow future correlation of tissue related toxicities with drug exposure as well as exposure with immunological responses. These results can also be compared with those from similar studies of other ATRi to contrast drug exposure with responses.

Central Nervous System Distribution of an Opioid Agonist Combination with Synergistic Activity.

Novel combinations of specific opioid agonists like loperamide and oxymorphindole targeting the µ- and δ-opioid receptors, respectively, have shown increased potency with minimized opioid-associated risks. However, whether their interaction is pharmacokinetic or pharmacodynamic in nature has not been determined. This study quantitatively determined whether these drugs have a pharmacokinetic interaction that alters systemic disposition or central nervous system (CNS) distribution. We performed intravenous and oral in vivo pharmacokinetic assessments of both drugs after discrete dosing and administration in combination to determine whether the combination had any effect on systemic pharmacokinetic parameters or CNS exposure. Drugs were administered at 5 or 10 mg/kg i.v. or 30 mg/kg orally to institute for cancer research (ICR) mice and 5 mg/kg i.v. to Friend leukemia virus strain B mice of the following genotypes: wild-type, breast cancer resistance protein (Bcrp-/- ) (Bcrp knockout), Mdr1a/b-/- [P-glycoprotein (P-gp) knockout], and Bcrp-/- Mdr1a/b-/- (triple knockout). In the combination, clearance of oxymorphindole (OMI) was reduced by approximately half, and the plasma area under the concentration-time curve (AUC) increased. Consequently, brain and spinal cord AUCs for OMI in the combination also increased proportionately. Both loperamide and OMI are P-gp substrates, but administration of the two drugs in combination does not alter efflux transport at the CNS barriers. Because OMI alone shows appreciable brain penetration but little therapeutic efficacy on its own, and because loperamide's CNS distribution is unchanged in the combination, the mechanism of action for the increased potency of the combination is most likely pharmacodynamic and most likely occurs at receptors in the peripheral nervous system. This combination has favorable characteristics for future development. SIGNIFICANCE STATEMENT: Opioids have yet to be replaced as the most effective treatments for moderate-to-severe pain and chronic pain, but their side effects are dangerous. Combinations of opioids with peripheral activity, such as loperamide and oxymorphindole, would be valuable in that they are effective at much lower doses and have reduced risks for dangerous side effects because the µ-opioid receptor agonist is largely excluded from the CNS.

Evaluation of the clinical cardiac safety of pemigatinib, a fibroblast growth factor receptor inhibitor, in participants with advanced malignancies.

Pemigatinib is a potent inhibitor of the fibroblast growth factor receptor (FGFR) family of receptors that is approved for the treatment of cholangiocarcinoma with FGFR2 fusion or other rearrangements. Data from a first-in-human clinical study were used to assess the potential for pemigatinib to produce clinically significant effects on heart rate (HR) and cardiac repolarization (QTc). A central tendency analysis for electrocardiogram (ECG) outliers and a plasma concentration-QTc analysis were conducted to assess cardiac safety in the first-in-human pemigatinib study (FIGHT-101; NCT02393248). The study included 113 participants who received at least one dose of pemigatinib as monotherapy and had at least one pair of plasma pharmacokinetic (PK) and ECG data points collected. Timed 12-lead ECGs were performed within 15 min of PK blood draws. The ECG parameters for each dose group in the study varied within expectations for patients with advanced malignancies. Categorical analysis of QT interval corrected for HR by Fridericia's method did not reveal dose dependence in the incidence of outliers, and the results of the central tendency and concentration-QTc analyses did not suggest a dose- or concentration-dependent drug effect. Least squares mean change from baseline in HR was small and did not indicate a clinically relevant effect on HR, and no effect was observed on cardiac conduction as assessed by PR and QRS intervals. In conclusion, pemigatinib does not exhibit any clinically significant prolongation of QTc or dose-dependent changes in HR. Clinical trial registration: ClinicalTrials.gov NCT02393248.

Small-molecule polymerase inhibitor protects non-human primates from measles and reduces shedding.

Measles virus (MeV) is a highly contagious pathogen that enters the human host via the respiratory route. Besides acute pathologies including fever, cough and the characteristic measles rash, the infection of lymphocytes leads to substantial immunosuppression that can exacerbate the outcome of infections with additional pathogens. Despite the availability of effective vaccine prophylaxis, measles outbreaks continue to occur worldwide. We demonstrate that prophylactic and post-exposure therapeutic treatment with an orally bioavailable small-molecule polymerase inhibitor, ERDRP-0519, prevents measles disease in squirrel monkeys (Saimiri sciureus). Treatment initiation at the onset of clinical signs reduced virus shedding, which may support outbreak control. Results show that this clinical candidate has the potential to alleviate clinical measles and augment measles virus eradication.

Quantitation of vistusertib by UHPLC-MS/MS in rat plasma and its application to a pharmacokinetic study.

Aim: The present study aimed to develop a UHPLC-MS/MS method for determination of vistusertib in biological matrix, and to describe the pharmacokinetic behavior of vistusertib in SD rats. Methodology & results: After protein precipitation with acetone and acetonitrile (1:1), the chromatographic separation was achieved on an Agilent Poroshell 120 EC-C18 column and detected with a SCIEX QTRAP 4500 mass spectrometer under positive ionization mode. The developed UHPLC-MS/MS method showed an excellent linearity within the range of 1.0-3000 ng/ml with good accuracy and precision. Vistusertib showed a rapid absorption and reached the maximum concentration of 3532.2 ± 678.0 ng/ml 20-30 min after oral administration in Sprague-Dawley rats. Conclusion: The established analytical method was fast, sensitive and robust, and successfully applied to describe the pharmacokinetic behavior of vistusertib following an oral administration in rats.

Evaluation of drug-drug interactions of pemigatinib in healthy participants.

PURPOSE: Pemigatinib (INCB054828), a potent and selective oral fibroblast growth factor receptor 1-3 inhibitor, is a Biopharmaceutical Classification System class II compound with good permeability and pH-dependent solubility that is predominantly metabolized by cytochrome P450 (CYP) 3A. Two drug-drug interaction studies, one with acid-reducing agents, esomeprazole (proton pump inhibitor [PPI]) and ranitidine (histamine-2 [H2] antagonist), and the other with potent CYP3A-modulating agents, itraconazole (CYP3A inhibitor) and rifampin (CYP3A inducer), were performed. METHODS: Both were open-label, fixed-sequence studies conducted in up to 36 healthy participants each, enrolled into two cohorts (n = 18 each). Pemigatinib plasma concentration was measured, and pharmacokinetic parameters were derived by non-compartmental analysis. RESULTS: There was an 88% and 17% increase in pemigatinib area under the plasma drug concentration-time curve (AUC) and maximum plasma drug concentration (Cmax), respectively, with itraconazole, and an 85% and 62% decrease in pemigatinib AUC and Cmax with rifampin coadministration. There was a 35% and 8% decrease in pemigatinib AUC and Cmax, respectively, with esomeprazole, and a 2% decrease in Cmax and 3% increase in AUC with ranitidine coadministration. In both studies, all adverse events reported were grade ≤ 2. CONCLUSION: Coadministration with itraconazole or rifampin resulted in a clinically significant change in pemigatinib exposure. Therefore, coadministration of strong CYP3A inducers with pemigatinib should be avoided, and the dose of pemigatinib should be reduced if coadministration with strong CYP3A inhibitors cannot be avoided. The effect of PPIs/H2 antagonists on pemigatinib exposure was modest, and pemigatinib can be administered without regard to coadministration of PPIs/H2 antagonists.

Fostamatinib: A Review in Chronic Immune Thrombocytopenia.

Fostamatinib (Tavalisse®; Tavlesse®) is the first spleen tyrosine kinase (Syk) inhibitor approved for the treatment of chronic immune thrombocytopenia (ITP) in adult patients who have had an insufficient response to previous treatment. By inhibiting Syk activation in macrophages, fostamatinib blocks autoantibody-mediated platelet phagocytosis. In the placebo-controlled phase III FIT1 and FIT2 trials, 24 weeks of oral fostamatinib therapy increased platelet count in previously treated adults with ITP. A significantly higher proportion of patients achieved stable response with fostamatinib than with placebo in FIT1, but not in FIT2; however, pooled analyses of the two studies showed that fostamatinib produced significantly higher stable and overall response rates than placebo. Interim findings from the ongoing FIT3 open-label extension study suggested that the efficacy of fostamatinib was maintained with long-term treatment (up to 62 months; median duration 6 months), including in patients receiving fostamatinib as second- or later-line treatment. Fostamatinib had a generally manageable tolerability profile in all three FIT studies, with no serious safety risks. Fostamatinib therefore provides an alternative treatment option for chronic ITP in adult patients with an insufficient response to previous treatment.

Surface expression of the immunotherapeutic target GD2 in osteosarcoma depends on cell confluency.

BACKGROUND: Chimeric antigen receptor (CAR) T-cell therapy of pediatric sarcomas is challenged by the paucity of targetable cell surface antigens. A candidate target in osteosarcoma (OS) is the ganglioside GD2 , but heterogeneous expression of GD2 limits its value. AIM: We aimed to identify mechanisms that upregulate GD2 target expression in OS. METHODS AND RESULTS: GD2 surface expression in OS cells, studied by flow cytometry, was found to vary both among and within individual OS cell lines. Pharmacological approaches, including inhibition of the histone methyltransferase Enhancer of Zeste Homolog 2 (EZH2) and modulation of the protein kinase C, failed to increase GD2 expression. Instead, cell confluency was found to be associated with higher GD2 expression levels both in monolayer cultures and in tumor spheroids. The sensitivity of OS cells to targeting by GD2 -specific CAR T cells was compared in an in vitro cytotoxicity assay. Higher cell confluencies enhanced the sensitivity of OS cells to GD2 -antigen specific, CAR T-cell-mediated in vitro cytolysis. Mechanistic studies revealed that confluency-dependent upregulation of GD2 expression in OS cells is mediated by increased de novo biosynthesis, through a yet unknown mechanism. CONCLUSION: Expression of GD2 in OS cell lines is highly variable and associated with increasing cell confluency in vitro. Strategies for selective upregulation of GD2 are needed to enable effective therapeutic targeting of this antigen in OS.

Pharmacokinetics of Dexamethasone when Administered with Fosaprepitant for Chemotherapy-Induced Nausea and Vomiting and Differences in Dose-Dependent Antiemetic Effects.

BACKGROUND: Fosaprepitant, an NK1 receptor antagonist, inhibits and induces cytochrome P450 3A4 (CYP3A4) as its substrate. Contrarily dexamethasone is metabolized by CYP3A4. Therefore, in combination therapy wherein both agents interact with each other, it is recommended that the dexamethasone dose be reduced in the first two days. Thus far, there are only a few studies on the optimum dose of dexamethasone after day 3. Thus, we aimed to determine the pharmacokinetics of dexamethasone on day3 when administered together with fosaprepitant and investigate the dose-dependent differences in its antiemetic effect in patients with cancer. METHODS: Twelve patients with esophageal, stomach, or lung cancer received primary highly emetogenic chemotherapy (HEC). We intravenously administered 9.9 mg and 6.6 mg of dexamethasone on days 1 and 2, respectively, and 6.6 mg or 13.2 mg on day 3 together with the administration of 150 mg fosaprepitant and 0.75 mg palonosetron. We assessed the pharmacokinetics of dexamethasone on day 3 by dose and examined the dose-dependent antiemetic effect. RESULTS: No differences were observed in the time-to-maximum concentration and blood half-life of dexamethasone between patient groups that received dexamethasone at doses of 6.6 mg and 13.2 mg. In contrast, the area under the blood concentration-time curve and the maximum concentration of dexamethasone correlated with its dose. Moreover, the blood dexamethasone concentration on day 3 increased by twofold after the administration of a higher dose than after a lower dose. The severity of nausea in the delayed phase significantly decreased in a dose-dependent manner. CONCLUSION: Administration of a higher dexamethasone dose on day 3 improved the antiemetic effect of the combined regimen in patients with cancer who underwent HEC.
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Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of SPH3127: A Phase I, Randomized, Double-Blind, Placebo-Controlled Trial.

PURPOSE: To evaluate the pharmacokinetics, pharmacodynamics, safety, and tolerability of single- and multiple-dose SPH3127 in healthy individuals. METHODS: This was a randomized, double-blind, placebo-controlled, Phase I dose-escalation study. FINDINGS: SPH3127 exposure, expressed as Cmax, AUC0-t, and AUC0-∞, was proportionally increased with dose for a range of 25-800 mg (single ascending dose [SAD]) and 100-400 mg daily (multiple ascending doses [MADs]). In an SAD, the Cmax values with 25, 50, 100, 200, 400, and 800 mg of SPH3127 were 90.67, 344.50, 523.50, 1239.50, 2445.00, and 5753.33 ng/mL, respectively. The corresponding AUC0-t values were 294.48, 843.62, 1109.33, 2858.56, 6697.50, and 13057.83 h × ng/mL. In MADs, after the first dose of SPH3127, the Cmax values with 100, 200, and 400 mg of SPH3127 were 421.50, 969.00, and 2468.33 ng/mL, respectively. The corresponding AUC0-t values were 1279.28, 2275.77, and 5934.26 h × ng/mL. At steady state, the Cmax values with 100, 200, and 400 mg of SPH3127 were 514.67, 1419.17, and 2513.33 ng/mL, respectively. The corresponding AUC0-24 values were 1638.14, 3096.20, and 7577.70 h × ng/mL. The median Tmax range from 0.33 to 1.0 h and the median t1/2 from 3 to 4 h. In an SAD, when the dose was >100 mg, plasma renin activity inhibition of up to 90% lasted up to 24 h. In MADs, renin activity was continuously inhibited by up to 90% in each group for 24 h after the last administration. Treatment-emergent adverse events (AEs) were reported in 29.2% of individuals receiving the SAD and 33.3% of those receiving MADs. Only mild adverse events occurred. IMPLICATIONS: SPH3127 was well tolerated and had robust and sustained suppression of plasma renin activity. CLINICALTRIALS. GOV IDENTIFIERS: NCT03128138 (SAD study) and NCT03255993 (MAD study).