LC-MS/MS method for quick detection of vonoprazan fumarate in human plasma: Development, validation and its application to a bioequivalence study.

A liquid chromatography-tandem mass spectrometry method with vonoprazan fumarate-d4 as a stable isotope-labeled internal standard was developed and validated aiming at quantification of vonoprazan fumarate in human plasma for a bioequivalence study. Chromatographic separation was achieved by acetonitrile one-step protein precipitation using a gradient elution of 0.1% formic acid aqueous solution and acetonitrile with a run time of 3.65 min. Detection was carried out on a tandem mass spectrometer in multiple reaction monitoring mode via a positive electrospray ionization interface. The multiple reaction monitoring mode of precursor-product ion transitions for vonoprazan fumarate and vonoprazan fumarate-d4 were m/z 346.0 → 315.1 and 350.0 → 316.0, respectively. The linear range was 0.150-60.000 ng/ml. This method was fully validated with acceptable results in terms of selectivity, carryover, lower limit of quantification, calibration curve, accuracy, precision, dilution effect, matrix effect, stability, recovery and incurred sample reanalysis. A successful application of this method was realized in the bioequivalence study of vonoprazan fumarate tablet (20 mg) among healthy Chinese volunteers.

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.

Synthesis, Biological, Spectroscopic and Computational Investigations of Novel N-Acylhydrazone Derivatives of Pyrrolo[3,4-d]pyridazinone as Dual COX/LOX Inhibitors.

Secure and efficient treatment of diverse pain and inflammatory disorders is continually challenging. Although NSAIDs and other painkillers are well-known and commonly available, they are sometimes insufficient and can cause dangerous adverse effects. As yet reported, derivatives of pyrrolo[3,4-d]pyridazinone are potent COX-2 inhibitors with a COX-2/COX-1 selectivity index better than meloxicam. Considering that N-acylhydrazone (NAH) moiety is a privileged structure occurring in many promising drug candidates, we decided to introduce this pharmacophore into new series of pyrrolo[3,4-d]pyridazinone derivatives. The current paper presents the synthesis and in vitro, spectroscopic, and in silico studies evaluating the biological and physicochemical properties of NAH derivatives of pyrrolo[3,4-d]pyridazinone. Novel compounds 5a-c-7a-c were received with high purity and good yields and did not show cytotoxicity in the MTT assay. Their COX-1, COX-2, and 15-LOX inhibitory activities were estimated using enzymatic tests and molecular docking studies. The title N-acylhydrazones appeared to be promising dual COX/LOX inhibitors. Moreover, spectroscopic and computational methods revealed that new compounds form stable complexes with the most abundant plasma proteins-AAG and HSA, but do not destabilize their secondary structure. Additionally, predicted pharmacokinetic and drug-likeness properties of investigated molecules suggest their potentially good membrane permeability and satisfactory bioavailability.

A Phase 2 Study of Pimodivir (JNJ-63623872) in Combination With Oseltamivir in Elderly and Nonelderly Adults Hospitalized With Influenza A Infection: OPAL Study.

BACKGROUND: Both the elderly and individuals with comorbidities are at increased risk of developing influenza-related complications. Novel influenza antivirals are required, given limitations of current drugs (eg, resistance emergence and poor efficacy). Pimodivir is a first-in-class antiviral for influenza A under development for these patients. METHODS: Hospitalized patients with influenza A infection were randomized 2:1 to receive pimodivir 600 mg plus oseltamivir 75 mg or placebo plus oseltamivir 75 mg twice daily for 7 days in this phase 2b study. The primary objective was to compare pimodivir pharmacokinetics in elderly (aged 65-85 years) versus nonelderly adults (aged 18-64 years). Secondary end points included time to patient-reported symptom resolution. RESULTS: Pimodivir pharmacokinetic parameters in nonelderly and elderly patients were similar. Time to influenza symptom resolution was numerically shorter with pimodivir (72.45 hours) than placebo (94.15 hours). There was a lower incidence of influenza-related complications in the pimodivir group (7.9%) versus placebo group (15.6%). Treatment was generally well tolerated. CONCLUSIONS: No apparent relationship was observed between pimodivir pharmacokinetics and age. Our data demonstrate the need for a larger study of pimodivir in addition to oseltamivir to test whether it results in a clinically significant decrease in time-to-influenza-symptom alleviation and/or the frequency of influenza complications. CLINICAL TRIALS REGISTRATION: NCT02532283.

Physiologically based pharmacokinetic modelling to predict the clinical effect of CYP3A inhibitors/inducers on esaxerenone pharmacokinetics in healthy subjects and subjects with hepatic impairment.

PURPOSE: Esaxerenone is a novel, oral, nonsteroidal treatment for hypertension. Physiologically based pharmacokinetic (PBPK) modelling was performed to predict the drug-drug interaction (DDI) effect of cytochrome P450 (CYP)3A modulators on esaxerenone pharmacokinetics in healthy subjects and subjects with hepatic impairment. METHODS: In our PBPK model, the fraction of esaxerenone metabolised by CYP3A was estimated from mass-balance data and verified and optimised by clinical DDI study results with strong CYP3A modulators. The model was also verified by the observed pharmacokinetics after multiple oral dosing and by the effect of hepatic impairment on esaxerenone pharmacokinetics. The model was applied to predict the DDI effects on esaxerenone pharmacokinetics with untested CYP3A modulators in healthy subjects and with strong CYP3A modulators in subjects with hepatic impairment. RESULTS: The PBPK model well described esaxerenone pharmacokinetics after multiple oral dosing. The predicted fold changes in esaxerenone plasma exposure after coadministration with strong CYP3A modulators were comparable with the observed data (1.53-fold with itraconazole and 0.31-fold with rifampicin). Predicted DDIs with untested moderate CYP3A modulators were less than the observed DDI with strong CYP3A modulators. The PBPK model also described the effect of hepatic impairment on esaxerenone plasma exposure. The predicted DDI results with strong CYP3A modulators in subjects with hepatic impairment indicate that, for concomitant use of CYP3A modulators, caution is advised for subjects with hepatic impairment, as is for healthy subjects. CONCLUSION: The PBPK model developed predicted esaxerenone pharmacokinetics and DDIs and informed concurrent use of esaxerenone with CYP3A modulators.

Eco-Friendly, Simple, Fast, and Sensitive UPLC-MS/MS Method for Determination of Pexidartinib in Plasma and Its Application to Metabolic Stability.

Pexidartinib is the first drug approved by the U.S. Food and Drug Administration specifically to treat the rare joint tumor tenosynovial giant cell tumor. In the current study, a validated, selective, and sensitive UPLC-MS/MS assay was developed for the quantitative determination of pexidartinib in plasma samples using gifitinib as an internal standard (IS). Pexidartinib and IS were extracted by liquid-liquid extraction using methyl tert-butyl ether and separated on an acquity BEH C18 column kept at 40 °C using a mobile phase of 0.1% formic acid in acetonitrile: 0.1% formic acid in de-ionized water (70:30). The flow rate was 0.25 mL/min. Multiple reaction monitoring (MRM) was operated in electrospray (ESI)-positive mode at the ion transition of 418.06 > 165.0 for the analyte and 447.09 > 128.0 for the IS. FDA guidance for bioanalytical method validation was followed in method validation. The linearity of the established UPLC-MS/MS assay ranged from 0.5 to 1000 ng/mL with r > 0.999 with a limit of quantitation of 0.5 ng/mL. Moreover, the metabolic stability of pexidartinib in liver microsomes was estimated.

Time course of efficacy of ubrogepant for the acute treatment of migraine: Clinical implications.

BACKGROUND: The full utility of an acute treatment requires examination of the entire time course of effect during a migraine attack. Here the time course of effect of ubrogepant is evaluated. METHODS: ACHIEVE-I and -II were double-blind, single-attack, Phase 3 trials. Adults with migraine were randomised 1:1:1 to placebo or ubrogepant (50mg or 100mg, ACHIEVE-I; 25 mg or 50 mg, ACHIEVE-II). Pain freedom, absence of most bothersome symptom, and pain relief were assessed at various timepoints. Samples were collected for pharmacokinetic analysis. Data were pooled for this post-hoc analysis. RESULTS: Participants' (n = 912 placebo, n = 887 ubrogepant 50 mg, pooled analysis population) mean age was 41 years, with a majority female and white. Pain relief separated from placebo by 1 h (43% versus 37% [OR, 95% CI: 1.30, 1.0-1.59]), absence of most bothersome symptom by 1.5 h (28% versus 22% [1.42, 1.14-1.77]), and pain freedom by 2 h (20% vs. 13% [1.72, 1.33-2.22]). Efficacy was sustained from 2-24 h (pain relief: 1.71, 1.1-2.6; pain freedom: 1.71, 1.3-2.3) and remained separated at 48 h (pain relief: 1.7, 1.1-2.6; pain freedom: 1.31, 1.0-1.7). Pharmacokinetic analysis demonstrated maximum plasma concentrations were achieved at 1 h, with pharmacologically active concentrations reached within 11 min and remaining above the EC90 for nearly 12 h. CONCLUSIONS: Evaluation of the time course of effect of ubrogepant showed pain relief as the most sensitive and earliest measure of clinical effect, followed by absence of most bothersome symptom, and pain freedom. Efficacy was demonstrated out to 48 h, providing evidence of the long-lasting effect of ubrogepant. This evaluation supports the role of examining the entire time course of effect to understand fully the utility of an acute treatment for migraine.Trial registration: ACHIEVE I (ClinicalTrials.gov, NCT02828020) and ACHIEVE II (ClinicalTrials.gov, NCT02867709).

Discovery of IDO1 inhibitors containing a decahydroquinoline, decahydro-1,6-naphthyridine, or octahydro-1H-pyrrolo[3,2-c]pyridine scaffold.

A series of IDO1 inhibitors containing a decahydroquinoline, decahydro-1,6-naphthyridine, or octahydro-1H-pyrrolo[3,2-c]pyridine scaffold were identified with good cellular and human whole blood activity against IDO1. These inhibitors contain multiple chiral centers and all diastereomers were separated. The absolute stereochemistry of each isomers were not determined. Compounds 15 and 27 stood out as leads due to their good cellular as well as human whole blood IDO1 inhibition activity, low unbound clearance, and reasonable mean residence time in rat cassette PK studies.

Pharmacokinetics and safety of ubrogepant when coadministered with calcitonin gene-related peptide-targeted monoclonal antibody migraine preventives in participants with migraine: A randomized phase 1b drug-drug interaction study.

OBJECTIVE: To evaluate the impact of two calcitonin gene-related peptide (CGRP)-targeted monoclonal antibodies (mAbs), erenumab and galcanezumab, on the pharmacokinetic (PK) profile, safety, and tolerability of ubrogepant. BACKGROUND: People taking CGRP-targeted mAbs for migraine prevention sometimes take ubrogepant, an oral small-molecule CGRP receptor antagonist, for acute treatment of breakthrough migraine attacks. DESIGN: In this two-arm, multicenter, open-label, phase 1b trial, adults with migraine were randomized to arm 1 (ubrogepant ± erenumab) or arm 2 (ubrogepant ± galcanezumab). The PK profile of ubrogepant was characterized for administration before and 4 days after CGRP-targeted mAb injection. Participants received single-dose ubrogepant 100 mg on day 1, subcutaneous erenumab 140 mg (arm 1) or galcanezumab 240 mg (arm 2) on day 8, and ubrogepant 100 mg once daily on days 12-15. In each study arm, serial blood samples were drawn on days 1 and 12 for measurement of plasma ubrogepant concentrations. The primary outcomes were area under the plasma ubrogepant concentration-time curve (AUC) from time 0 to t post-dose (AUC0- t ) and from time 0 to infinity (AUC0-inf ), and maximum plasma concentration (Cmax ) of ubrogepant when ubrogepant was administered before or after a single dose of erenumab or galcanezumab. Vital signs and laboratory parameters were monitored. RESULTS: Forty participants enrolled (20 per arm; mean [standard deviation] ages, 32.2 [8.9] and 38.4 [8.8] years; 50% [10/20] and 60% [12/20] female in arms 1 and 2, respectively). There were no significant differences in ubrogepant Cmax after versus before erenumab administration (geometric least-squares mean [LSM] ratio, 1.04 [90% CI, 0.93-1.16]), and no significant differences in AUC0- t (1.06 [0.96-1.16]) or AUC0-inf (1.05 [0.96-1.15]). Similarly, ubrogepant Cmax (1.00 [90% CI, 0.82-1.20]), AUC0- t (1.05 [0.90-1.23]), and AUC0-inf (1.05 [0.90-1.22]) geometric LSM ratios were statistically equivalent after galcanezumab versus ubrogepant alone. Treatment-emergent adverse events (TEAEs) were similar to those reported with each treatment alone. No serious TEAEs, TEAEs leading to discontinuation, or clinically relevant changes in laboratory parameters or vital signs were reported. CONCLUSIONS: The PK profile of ubrogepant was not significantly changed and no safety concerns were identified when ubrogepant was coadministered with erenumab or galcanezumab.

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.

Synthesis and preliminary evaluation of novel 11C-labeled GluN2B-selective NMDA receptor negative allosteric modulators.

N-methyl-D-aspartate receptors (NMDARs) play critical roles in the physiological function of the mammalian central nervous system (CNS), including learning, memory, and synaptic plasticity, through modulating excitatory neurotransmission. Attributed to etiopathology of various CNS disorders and neurodegenerative diseases, GluN2B is one of the most well-studied subtypes in preclinical and clinical studies on NMDARs. Herein, we report the synthesis and preclinical evaluation of two 11C-labeled GluN2B-selective negative allosteric modulators (NAMs) containing N,N-dimethyl-2-(1H-pyrrolo[3,2-b]pyridin-1-yl)acetamides for positron emission tomography (PET) imaging. Two PET ligands, namely [11C]31 and [11C]37 (also called N2B-1810 and N2B-1903, respectively) were labeled with [11C]CH3I in good radiochemical yields (decay-corrected 28% and 32% relative to starting [11C]CO2, respectively), high radiochemical purity (>99%) and high molar activity (>74 GBq/µmol). In particular, PET ligand [11C]31 demonstrated moderate specific binding to GluN2B subtype by in vitro autoradiography studies. However, because in vivo PET imaging studies showed limited brain uptake of [11C]31 (up to 0.5 SUV), further medicinal chemistry and ADME optimization are necessary for this chemotype attributed to low binding specificity and rapid metabolism in vivo.

Simulation of Remdesivir Pharmacokinetics and Its Drug Interactions.

PURPOSE: Remdesivir, a drug originally developed against Ebola virus, is currently recommended for patients hospitalized with coronavirus disease of 2019 (COVID-19). In spite of United States Food and Drug Administration's recent assent of remdesivir as the only approved agent for COVID-19, there is limited information available about the physicochemical, metabolism, transport, pharmacokinetic (PK), and drug-drug interaction (DDI) properties of this drug. The objective of this in silico simulation work was to simulate the biopharmaceutical and DDI behavior of remdesivir and characterize remdesivir PK properties in special populations which are highly affected by COVID-19. METHODS: The Spatial Data File format structures of remdesivir prodrug (GS-5734) and nucleoside core (GS-441524) were obtained from the PubChem database to upload into the GastroPlus software 9.8 version (Simulations Plus Inc., USA). The Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) Predictor and PKPlus modules of GastroPlus were used to simulate physicochemical and PK properties, respectively, in healthy and predisposed patients. Physiologically based pharmacokinetic (PBPK) modeling of GastroPlus was used to simulate different patient populations based on age, weight, liver function, and renal function status. Subsequently, these data were used in the Drug-Drug Interaction module to simulate drug interaction potential of remdesivir with other COVID-19 drug regimens and with agents used for comorbidities. RESULTS: Remdesivir nucleoside core (GS-441524) is more hydrophilic than the inactive prodrug (GS-5734) with nucleoside core demonstrating better water solubility. GS-5734, but not GS-441524, is predicted to be metabolized by CYP3A4. Remdesivir is bioavailable and its clearance is achieved through hepatic and renal routes. Differential effects of renal function, liver function, weight, or age were observed on the PK profile of remdesivir. DDI simulation study of remdesivir with perpetrator drugs for comorbidities indicate that carbamazepine, phenytoin, amiodarone, voriconazole, diltiazem, and verapamil have the potential for strong interactions with victim remdesivir, whereas agents used for COVID-19 treatment such as chloroquine and ritonavir can cause weak and strong interactions, respectively, with remdesivir. CONCLUSIONS: GS-5734 (inactive prodrug) appears to be a superior remdesivir derivative due to its hepatic stability, optimum hydrophilic/lipophilic balance, and disposition properties. Remdesivir disposition can potentially be affected by different physiological and pathological conditions, and by drug interactions from COVID-19 drug regimens and agents used for comorbidities.

Tofacitinib as Induction and Maintenance Therapy for Ulcerative Colitis.

BACKGROUND: Tofacitinib, an oral, small-molecule Janus kinase inhibitor, was shown to have potential efficacy as induction therapy for ulcerative colitis in a phase 2 trial. We further evaluated the efficacy of tofacitinib as induction and maintenance therapy. METHODS: We conducted three phase 3, randomized, double-blind, placebo-controlled trials of tofacitinib therapy in adults with ulcerative colitis. In the OCTAVE Induction 1 and 2 trials, 598 and 541 patients, respectively, who had moderately to severely active ulcerative colitis despite previous conventional therapy or therapy with a tumor necrosis factor antagonist were randomly assigned to receive induction therapy with tofacitinib (10 mg twice daily) or placebo for 8 weeks. The primary end point was remission at 8 weeks. In the OCTAVE Sustain trial, 593 patients who had a clinical response to induction therapy were randomly assigned to receive maintenance therapy with tofacitinib (either 5 mg or 10 mg twice daily) or placebo for 52 weeks. The primary end point was remission at 52 weeks. RESULTS: In the OCTAVE Induction 1 trial, remission at 8 weeks occurred in 18.5% of the patients in the tofacitinib group versus 8.2% in the placebo group (P=0.007); in the OCTAVE Induction 2 trial, remission occurred in 16.6% versus 3.6% (P<0.001). In the OCTAVE Sustain trial, remission at 52 weeks occurred in 34.3% of the patients in the 5-mg tofacitinib group and 40.6% in the 10-mg tofacitinib group versus 11.1% in the placebo group (P<0.001 for both comparisons with placebo). In the OCTAVE Induction 1 and 2 trials, the rates of overall infection and serious infection were higher with tofacitinib than with placebo. In the OCTAVE Sustain trial, the rate of serious infection was similar across the three treatment groups, and the rates of overall infection and herpes zoster infection were higher with tofacitinib than with placebo. Across all three trials, adjudicated nonmelanoma skin cancer occurred in five patients who received tofacitinib and in one who received placebo, and adjudicated cardiovascular events occurred in five who received tofacitinib and in none who received placebo; as compared with placebo, tofacitinib was associated with increased lipid levels. CONCLUSIONS: In patients with moderately to severely active ulcerative colitis, tofacitinib was more effective as induction and maintenance therapy than placebo. (Funded by Pfizer; OCTAVE Induction 1, OCTAVE Induction 2, and OCTAVE Sustain ClinicalTrials.gov numbers, NCT01465763 , NCT01458951 , and NCT01458574 , respectively.).

Multifaceted Bioanalytical Methods for the Comprehensive Pharmacokinetic and Catabolic Assessment of MEDI3726, an Anti-Prostate-Specific Membrane Antigen Pyrrolobenzodiazepine Antibody-Drug Conjugate.

Complex biotherapeutic modalities, such as antibody-drug conjugates (ADC), present significant challenges for the comprehensive bioanalytical characterization of their pharmacokinetics (PK) and catabolism in both preclinical and clinical settings. Thus, the bioanalytical strategy for ADCs must be designed to address the specific structural elements of the protein scaffold, linker, and warhead. A typical bioanalytical strategy for ADCs involves quantification of the Total ADC, Total IgG, and Free Warhead concentrations. Herein, we present bioanalytical characterization of the PK and catabolism of a novel ADC. MEDI3726 targets prostate-specific membrane antigen (PMSA) and is comprised of a humanized IgG1 antibody site-specifically conjugated to tesirine (SG3249). The MEDI3726 protein scaffold lacks interchain disulfide bonds and has an average drug to antibody ratio (DAR) of 2. Based on the structural characteristics of MEDI3726, an array of 4 bioanalytical assays detecting 6 different surrogate analyte classes representing at least 14 unique species was developed, validated, and employed in support of a first-in-human clinical trial (NCT02991911). MEDI3726 requires the combination of heavy-light chain structure and conjugated warhead to selectively deliver the warhead to the target cells. Therefore, both heavy-light chain dissociation and the deconjugation of the warhead will affect the activity of MEDI3726. The concentration-time profiles of subjects dosed with MEDI3726 revealed catabolism of the protein scaffold manifested by the more rapid clearance of the Active ADC, while exhibiting minimal deconjugation of the pyrrolobenzodiazepine (PBD) warhead (SG3199).

A phase 1 trial of vadastuximab talirine as monotherapy in patients with CD33-positive acute myeloid leukemia.

Vadastuximab talirine (SGN-CD33A, 33A) is an antibody-drug conjugate consisting of pyrrolobenzodiazepine dimers linked to a monoclonal antibody targeting CD33, which is expressed in the majority of acute myeloid leukemia (AML) patients. This phase 1 study evaluated the safety, pharmacokinetics, and preliminary activity of vadastuximab talirine and determined the recommended monotherapy dose in patients with relapsed or refractory AML. Additional expansion cohorts tested vadastuximab talirine in specific subpopulations of relapsed AML, and in a cohort of older, treatment-naive patients. Patients received vadastuximab talirine IV on day 1 (5-60 µg/kg) or on days 1 and 4 (20 µg/kg) of 21-day cycles. A total of 131 patients (median age, 73 years [range, 26-89 years]) had intermediate I-II (48%) or adverse (34%) risk by European LeukemiaNet classification; 50% of patients had underlying myelodysplasia. Two dose-limiting toxicities (grade 2 pulmonary embolism and grade 4 hypocellular marrow) occurred during dose finding. Most adverse events (AEs) were consistent with myelosuppression; nonhematologic AEs included fatigue, nausea, and diarrhea. The 30-day mortality was 8%. At the recommended monotherapy dose of 40 µg/kg, the complete remission + CRi rate was 28% (5 of 18 patients); 50% of patients who responded achieved minimal residual disease negativity. In patients across dose levels who achieved CR or CRi, the median time to full count recovery was 6.4 weeks for neutrophils (≥1000/µL) and 10.6 weeks for platelets (≥100 × 109/L). Vadastuximab talirine demonstrates activity and a tolerable safety profile as a single agent in patients with AML. The recommended monotherapy dose of vadastuximab talirine is 40 µg/kg. This trial was registered at www.clinicaltrials.gov as # NCT01902329.

A phase 1 trial of vadastuximab talirine combined with hypomethylating agents in patients with CD33-positive AML.

Treatment of acute myeloid leukemia (AML) among the elderly is challenging because of intolerance of intensive therapy and therapy-resistant biology. Hypomethylating agents (HMAs) are commonly used, with suboptimal outcomes. Vadastuximab talirine is a CD33-directed antibody conjugated to pyrrolobenzodiazepine (PBD) dimers. Preclinically, HMAs followed by vadastuximab talirine produced upregulated CD33 expression, increased DNA incorporation by PBD, and enhanced cytotoxicity. A combination cohort in a phase 1 study (NCT01902329) assessed safety, tolerability, and activity of vadastuximab talirine with HMAs. Those eligible had Eastern Cooperative Oncology Group status 0 to 1 and previously untreated CD33-positive AML, and declined intensive therapy. Vadastuximab talirine was administered intravenously at 10 µg/kg on last day of HMA (azacitidine or decitabine) infusion in 4-week cycles. Among 53 patients treated, the median age was 75 years. Patients had adverse (38%) or intermediate (62%) cytogenetic risk. Median treatment duration was 19.3 weeks. No dose-limiting toxicities were reported. The majority of adverse events were a result of myelosuppression, with some causing therapy delays. Thirty- and 60-day mortality rates were 2% and 8%, respectively. The composite remission rate (complete remission [CR] and CR with incomplete blood count recovery) was 70%. Fifty-one percent of remissions were minimal residual disease-negative by flow cytometry. Similarly high remission rates were observed in patients with secondary AML, aged at least 75 years, and with adverse cytogenetic risk. Median relapse-free survival and overall survival were 7.7 and 11.3 months, respectively. Compared with historical data for HMA monotherapy, the combination of vadastuximab talirine with HMAs produced a high remission rate, but was accompanied by increased hematologic toxicity.

NADPH-Independent Inactivation of CYP2B6 and NADPH-Dependent Inactivation of CYP3A4/5 by PBD: Potential Implication for Assessing Covalent Modulators for Time-Dependent Inhibition.

Pyrrolo[2,1-c][1,4]benzodiazepine dimer (PBD) has shown broad antitumor properties and potential as a therapeutic agent for cancers. During a routine drug-drug interaction assessment, it was found that PBD is a reversible inhibitor of CYP2C8 (IC50 = 1.1 µM) but not CYP1A2, 2B6, 2C9, 2C19, 2D6, or 3A4/5. Additionally, PBD is a classic time-dependent inhibition (TDI) of CYP3A4/5, with >30-fold shift in IC50 after a preincubation with NADPH. All other CYPs tested did not show evidence for TDI, but potent inhibition of CYP2B6 (IC50 = 1.5 µM) was observed after a preincubation with or without (w/wo) NADPH, which was an unexpected observation given the fact that no inhibition was observed in the direct inhibition assay. No other CYP isoforms were susceptible to this apparent non-NADPH-dependent inhibition, suggesting that PBD may selectively inactivate CYP2B6 without metabolic activation. The washing of the human liver microsome pellet after incubation with PBD did not fully recover CYP2B6 activity, indicating that PBD is covalently bound to CYP2B6, leading to inactivation of the enzyme. To further investigate the mechanism of NADPH-independent inhibition, the IC50 shift was determined for several PBD analogs, and it was found that the compounds without both reactive imines did not show NADPH-independent inhibition of CYP2B6, implying that NADPH-independent inactivation was likely caused by direct covalent binding of PBD to the enzyme in a highly structure-specific manner. These data clearly highlight the need to assess direct and time-dependent inhibition w/wo NADPH to adequately characterize the in vitro CYP inhibitory properties of drug candidates with reactive moieties. SIGNIFICANCE STATEMENT: We described a very unique in vitro CYP inhibition profile of pyrrolo[2,1-c][1,4]benzodiazepine dimer as a potent reversible CYP2C8 inhibitor, an NADPH-dependent CYP3A4/5 time-dependent inhibition (TDI) inhibitor, and an NADPH-independent CYP2B6 TDI inhibitor, and inhibition of CYPs occurs through three distinct mechanisms: reversible drug-enzyme binding, enzyme inactivation via bioactivation, and enzyme inactivation by covalent binding via chemical reactions. Our results suggest that, for compounds with reactive functional moieties, false positives can be reported when the conventional TDI assay is utilized.

Excretion, Mass Balance, and Metabolism of [14C]LY3202626 in Humans: An Interplay of Microbial Reduction, Reabsorption, and Aldehyde Oxidase Oxidation That Leads to an Extended Excretion Profile.

The mass balance, excretion, and metabolism of LY3202626 were determined in healthy subjects after oral administration of a single dose of 10 mg of (approximately 100 µCi) [14C]LY3202626. Excretion of radioactivity was slow and incomplete, with approximately 75% of the dose recovered after 504 hours of sample collection. The mean total recovery of the radioactive dose was 31% and 44% in the feces and urine, respectively. Because of low plasma total radioactivity, plasma metabolite profiling was conducted by accelerator mass spectrometry. Metabolism of LY3202626 occurred primarily via O-demethylation (M2) and amide hydrolysis (M1, M3, M4, and M5). Overall, parent drug, M1, M2, and M4 were the largest circulating components in plasma, and M2 and M4 were the predominant excretory metabolites. The slow elimination of total radioactivity was proposed to result from an unusual enterohepatic recirculation pathway involving microbial reduction of metabolite M2 to M16 in the gut and reabsorption of M16, followed by hepatic oxidation of M16 back to M2. Supporting in vitro experiments showed that M2 is reduced to M16 anaerobically in fecal homogenate and that M16 is oxidized in the liver by aldehyde oxidase to M2. LY3202626 also showed a potential to form a reactive sulfenic acid intermediate. A portion of plasma radioactivity was unextractable and presumably bound covalently to plasma proteins. In vitro incubation of LY3202626 in human liver microsomes in the presence of NADPH with dimedone as a trapping agent implicated the formation of the proposed sulfenic acid intermediate. SIGNIFICANCE STATEMENT: The excretion of radioactivity in humans after oral administration of a single dose of 10 mg of [14C]LY3202626 was very slow. The results from in vitro experiments suggested that an interplay between microbial reduction, reabsorption, and aldehyde oxidase oxidation (M2 → M16 → M2) could be a reason for extended radioactivity excretion profile. In vitro metabolism also showed that LY3202626 has the potential to form a reactive sulfenic acid intermediate that could potentially covalently bind to plasma protein and result in the observed unextractable radioactivity from plasma.

Drug-Drug Interaction Risk Assessment of Esaxerenone as a Perpetrator by In Vitro Studies and Static and Physiologically Based Pharmacokinetic Models.

Esaxerenone (CS-3150) is a novel, oral, nonsteroidal, selective mineralocorticoid receptor blocker approved for the treatment of hypertension in Japan. Here, the drug-drug interaction (DDI) potential of esaxerenone was evaluated in vitro, and its impact in clinical practice was estimated. Esaxerenone exhibited time-dependent inhibition and induction of CYP3A. When the clinical impacts of esaxerenone on the inhibition and induction of CYP3A were estimated separately by using a mechanistic static model, the predicted area under the curve ratios (AUCRs) of midazolam, a typical CYP3A substrate, were 1.80 and 0.31, respectively, suggesting that the DDI potential of esaxerenone cannot be neglected. Because it was suggested that DDIs mainly occur in the intestine, predictions using concentration-time profiles in each segment of the gastrointestinal tract were performed with GastroPlus, a physiologically based pharmacokinetic (PBPK) modeling software. The predicted AUCR of midazolam was approximately 1.2, which is close to that in a clinical study, despite the difficulty of predicting DDIs for compounds with both inhibition and induction effects. When only inhibition or induction was incorporated into a model, the AUCR of midazolam changed depending on the dosing period and dose level of esaxerenone and the timing of midazolam administration. However, the AUCR calculated by incorporating both effects remained almost constant. This study shows the ability of PBPK models to simulate weak DDIs via intestinal CYP3A and that esaxerenone has low DDI potential as a perpetrator because of the offset of inhibition and induction. SIGNIFICANCE STATEMENT: Weak CYP3A inhibition and/or induction sometimes cause DDIs in the intestine but not the liver. Because strong inhibitors maximally inhibit intestinal CYP3A, the predictability of weak DDIs in the intestine should be evaluated further. Here, we simulate the DDIs of esaxerenone as a perpetrator by using physiologically based pharmacokinetic modeling focusing on the intestine and offset of inhibition and induction.

A phase I study of pexidartinib, a colony-stimulating factor 1 receptor inhibitor, in Asian patients with advanced solid tumors.

Background Pexidartinib, a novel, orally administered small-molecule tyrosine kinase inhibitor, has strong selectivity against colony-stimulating factor 1 receptor. This phase I, nonrandomized, open-label multiple-dose study evaluated pexidartinib safety and efficacy in Asian patients with symptomatic, advanced solid tumors. Materials and Methods Patients received pexidartinib: cohort 1, 600 mg/d; cohort 2, 1000 mg/d for 2 weeks, then 800 mg/d. Primary objectives assessed pexidartinib safety and tolerability, and determined the recommended phase 2 dose; secondary objectives evaluated efficacy and pharmacokinetic profile. Results All 11 patients (6 males, 5 females; median age 64, range 23-82; cohort 1 n = 3; cohort 2 n = 8) experienced at least one treatment-emergent adverse event; 5 experienced at least one grade ≥ 3 adverse event, most commonly (18%) for each of the following: increased aspartate aminotransferase, blood alkaline phosphatase, gamma-glutamyl transferase, and anemia. Recommended phase 2 dose was 1000 mg/d for 2 weeks and 800 mg/d thereafter. Pexidartinib exposure, area under the plasma concentration-time curve from zero to 8 h (AUC0-8h), and maximum observed plasma concentration (Cmax) increased on days 1 and 15 with increasing pexidartinib doses, and time at Cmax (Tmax) was consistent throughout all doses. Pexidartinib exposure and plasma levels of adiponectin and colony-stimulating factor 1 increased following multiple daily pexidartinib administrations. One patient (13%) with tenosynovial giant cell tumor showed objective tumor response. Conclusions This was the first study to evaluate pexidartinib in Asian patients with advanced solid tumors. Pexidartinib was safe and tolerable in this population at the recommended phase 2 dose previously determined for Western patients (funded by Daiichi Sankyo; clinicaltrials.gov number, NCT02734433).