Population Pharmacokinetic Modeling and Exposure-Efficacy and Body Weight-Response Analyses for Tezepelumab in Patients With Severe, Uncontrolled Asthma.

Tezepelumab is a human monoclonal antibody that blocks the activity of thymic stromal lymphopoietin. This analysis assessed the suitability of a fixed-dose regimen of tezepelumab 210 mg every 4 weeks (Q4W) in adults and adolescents with severe, uncontrolled asthma. A population pharmacokinetic model was developed using data from 1368 patients with asthma or healthy participants enrolled in 8 clinical studies (phases 1-3). Tezepelumab exposure-efficacy relationships were analyzed in the phase 3 NAVIGATOR study (NCT03347279), using asthma exacerbation rates over 52 weeks and changes in pre-bronchodilator forced expiratory volume in 1 s at week 52. Tezepelumab pharmacokinetics were well characterized by a 2-compartment linear disposition model with first-order absorption and elimination following subcutaneous and intravenous administration at 2.1-420 and 210-700 mg, respectively. There were no clinically relevant effects on tezepelumab pharmacokinetics from age (≥12 years), sex, race/ethnicity, renal or hepatic function, disease severity (inhaled corticosteroid dose level), concomitant asthma medication use, smoking history, or anti-drug antibodies. Body weight was the most influential covariate on tezepelumab exposure, but no meaningful differences in efficacy or safety were observed across body weight quartiles in patients with asthma who received tezepelumab 210 mg subcutaneously Q4W. There was no apparent relationship between tezepelumab exposure and efficacy at this dose regimen, suggesting that it is on the plateau of the exposure-response curve of tezepelumab. In conclusion, a fixed-dose regimen of tezepelumab 210 mg subcutaneously Q4W is appropriate for eligible adults and adolescents with severe, uncontrolled asthma.

Population pharmacokinetics of a novel PCSK9 antisense oligonucleotide.

AIMS: The aim of this study was to characterize the population pharmacokinetics of AZD8233, an antisense oligonucleotide (ASO) that targets the PCSK9 transcript to reduce hepatocyte PCSK9 protein production and plasma levels. AZD8233 utilizes generation 2.5 S-constrained ethyl motif (cET) chemistry and is conjugated to a triantennary N-acetylgalactosamine (GalNAc3) ligand for targeted hepatocyte uptake. METHODS: A non-linear mixed-effect modelling approach utilizing NONMEM software was applied to AZD8233 concentration-time data from 3416 samples in 219 participants from four phase 1-2 studies, one in healthy volunteers (NCT03593785) and three in patients with dyslipidaemia (NCT04155645, NCT04641299 and NCT04823611). RESULTS: The final model described the AZD8233 plasma concentration-time profile from four phase 1-2 studies in healthy volunteers or participants with dyslipidaemia, covering a dose range of 4 to 120 mg. The pharmacokinetics of AZD8233 were adequately described by a two-compartment model with first-order absorption. The supra-proportional increase in maximum plasma concentration (Cmax) across the observed dose range was described by non-linear Michaelis-Menten elimination (maximum elimination rate, 9.9 mg/h [12% relative standard error]; concentration yielding half-maximal elimination rate, 4.8 mg/L [18% relative standard error]). Body weight, sex, estimated glomerular filtration rate and disease status (healthy participant vs. patient with dyslipidaemia) were identified as factors affecting exposure to AZD8233. CONCLUSIONS: Covariate analysis showed body weight to be the main factor affecting exposure to AZD8233, which largely explained the higher Cmax observed in the Asian population relative to non-Asians.

Population Pharmacokinetics of Ranibizumab Delivered via the Port Delivery System Implanted in the Eye in Patients with Neovascular Age-Related Macular Degeneration.

The port delivery system with ranibizumab (PDS) is designed to continuously deliver ranibizumab to maintain therapeutic drug concentrations in the vitreous of the eye for an extended duration. The PDS has been evaluated for the treatment of neovascular age-related macular degeneration in the Ladder (PDS 10, 40, and 100 mg/mL, with refill exchanges as needed, versus monthly intravitreal ranibizumab 0.5 mg), Archway (PDS 100 mg/mL with 24-week refill exchanges, versus monthly intravitreal ranibizumab 0.5 mg), and ongoing Portal (PDS 100 mg/mL with 24-week refill exchanges) clinical trials. Data from Ladder, Archway, and Portal were used to develop a population pharmacokinetics (PK) model to estimate the ranibizumab release rate from the PDS implant, describe ranibizumab PK in serum and aqueous humor, and predict the concentration in vitreous humor. A model was developed to adequately describe the serum and aqueous humor PK data, as suggested by goodness-of-fit plots as well as visual predictive checks. In the final model, the first-order implant release rate was estimated to be 0.00654 (1/day), corresponding to a half-life of 106 days, consistent with the implant release rate determined in vitro. The model-predicted vitreous concentrations achieved with PDS 100 mg/mL given every 24 weeks were below the intravitreal peak concentration and above the intravitreal trough concentration of ranibizumab over the entire 24-week refill interval. The results demonstrate a durable release of ranibizumab from the PDS with a half-life of 106 days, providing vitreous exposure to ranibizumab for at least 24 weeks that is within the range of exposure for monthly intravitreal treatment.

Modeling Alzheimer's disease progression utilizing clinical trial and ADNI data to predict longitudinal trajectory of CDR-SB.

There is strong interest in developing predictive models to better understand individual heterogeneity and disease progression in Alzheimer's disease (AD). We have built upon previous longitudinal AD progression models, using a nonlinear, mixed-effect modeling approach to predict Clinical Dementia Rating Scale - Sum of Boxes (CDR-SB) progression. Data from the Alzheimer's Disease Neuroimaging Initiative (observational study) and placebo arms from four interventional trials (N = 1093) were used for model building. The placebo arms from two additional interventional trials (N = 805) were used for external model validation. In this modeling framework, CDR-SB progression over the disease trajectory timescale was obtained for each participant by estimating disease onset time (DOT). Disease progression following DOT was described by both global progression rate (RATE) and individual progression rate (α). Baseline Mini-Mental State Examination and CDR-SB scores described the interindividual variabilities in DOT and α well. This model successfully predicted outcomes in the external validation datasets, supporting its suitability for prospective prediction and use in design of future trials. By predicting individual participants' disease progression trajectories using baseline characteristics and comparing these against the observed responses to new agents, the model can help assess treatment effects and support decision making for future trials.

Lectin-Like Oxidized Low-Density Lipoprotein Receptor 1 Inhibition in Type 2 Diabetes: Phase 1 Results.

Background Blockade of the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a potentially attractive mechanism for lowering inflammatory and lipid risk in patients with atherosclerosis. This study aims to assess the safety, tolerability, and target engagement of MEDI6570, a high-affinity monoclonal blocking antibody to LOX-1. Methods and Results This phase 1, first-in-human, placebo-controlled study (NCT03654313) randomized 88 patients with type 2 diabetes to receive single ascending doses (10, 30, 90, 250, or 500 mg) or multiple ascending doses (90, 150, or 250 mg once monthly for 3 months) of MEDI6570 or placebo. Primary end point was safety; secondary and exploratory end points included pharmacokinetics, immunogenicity, free soluble LOX-1 levels, and change in coronary plaque volume. Mean age was 57.6/58.1 years in the single ascending doses/multiple ascending doses groups, 31.3%/62.5% were female, and mean type 2 diabetes duration was 9.7/8.7 years. Incidence of adverse events was similar among cohorts. MEDI6570 exhibited nonlinear pharmacokinetics, with terminal half-life increasing from 4.6 days (30 mg) to 11.2 days (500 mg), consistent with target-mediated drug disposition. Dose-dependent reductions in mean soluble LOX-1 levels from baseline were observed (>66% at 4 weeks and 71.61-82.96% at 10 weeks in the single ascending doses and multiple ascending doses groups, respectively). After 3 doses, MEDI6570 was associated with nonsignificant regression of noncalcified plaque volume versus placebo (-13.45 mm3 versus -8.25 mm3). Conclusions MEDI6570 was well tolerated and demonstrated dose-dependent soluble LOX-1 suppression and a pharmacokinetic profile consistent with once-monthly dosing. Registration URL: https://clinicaltrials.gov/; Unique identifier: NCT03654313.

Quantitative systems pharmacology model of the amyloid pathway in Alzheimer's disease: Insights into the therapeutic mechanisms of clinical candidates.

Despite considerable investment into potential therapeutic approaches for Alzheimer's disease (AD), currently approved treatment options are limited. Predictive modeling using quantitative systems pharmacology (QSP) can be used to guide the design of clinical trials in AD. This study developed a QSP model representing amyloid beta (Aß) pathophysiology in AD. The model included mechanisms of Aß monomer production and aggregation to form insoluble fibrils and plaques; the transport of soluble species between the compartments of brain, cerebrospinal fluid (CSF), and plasma; and the pharmacokinetics, transport, and binding of monoclonal antibodies to targets in the three compartments. Ordinary differential equations were used to describe these processes quantitatively. The model components were calibrated to data from the literature and internal studies, including quantitative data supporting the underlying AD biology and clinical data from clinical trials for anti-Aß monoclonal antibodies (mAbs) aducanumab, crenezumab, gantenerumab, and solanezumab. The model was developed for an apolipoprotein E (APOE) ɛ4 allele carrier and tested for an APOE ɛ4 noncarrier. Results indicate that the model is consistent with data on clinical Aß accumulation in untreated individuals and those treated with monoclonal antibodies, capturing increases in Aß load accurately. This model may be used to investigate additional AD mechanisms and their impact on biomarkers, as well as predict Aß load at different dose levels for mAbs with known targets and binding affinities. This model may facilitate the design of scientifically enriched and efficient clinical trials by enabling a priori prediction of biomarker dynamics in the brain and CSF.

Evaluating the Safety and Efficacy of Crenezumab vs Placebo in Adults With Early Alzheimer Disease: Two Phase 3 Randomized Placebo-Controlled Trials.

Importance: Alzheimer disease (AD), a neurodegenerative disease characterized by ß-amyloid plaques and τ tangles in the brain, represents an unmet medical need with no fully approved therapeutics to modify disease progression. Objective: To investigate the safety and efficacy of crenezumab, a humanized monoclonal immunoglobulin G4 antibody targeting ß-amyloid oligomers, in participants with prodromal to mild (early) AD. Design, Setting, and Participants: Two phase 3 multicenter randomized double-blind placebo-controlled parallel-group efficacy and safety studies of crenezumab in participants with early AD, CREAD and CREAD2, were initiated in 2016 and 2017, respectively, and were designed to evaluate the efficacy and safety of crenezumab in participants with early AD. CREAD (194 sites in 30 countries) and CREAD2 (209 sites in 27 countries) were global multicenter studies. A total of 3736 and 3664 participants were screened in CREAD and CREAD2, respectively. A total of 3736 and 3664 participants were screened in CREAD and CREAD2, respectively. Both trials enrolled individuals aged 50 to 85 years with early AD. Participants with some comorbidities and evidence of cerebral infarction or more than 4 microbleeds or areas of leptomeningeal hemosiderosis on magnetic resonance imaging were excluded. After 2923 and 2858 were excluded, respectively, 813 participants in CREAD and 806 in CREAD2 were randomly assigned in a 1:1 ratio to either placebo or crenezumab. In the final analysis, there were 409 participants in the placebo group and 404 in the crenezumab group in CREAD and 399 in the placebo group and 407 in the crenezumab group in CREAD2. Data were analyzed up until January 2019 and August 2019, respectively. Interventions: Participants received placebo or 60 mg/kg crenezumab intravenously every 4 weeks for up to 100 weeks. Main Outcomes and Measures: The primary outcome was change from baseline to week 105 in Clinical Dementia Rating-Sum of Boxes (CDR-SB) score. Results: There were 813 participants in CREAD (mean [SD] age, 70.7 [8.2] years; 483 female and 330 male) and 806 in CREAD2 (mean [SD] age, 70.9 [7.7] years; 456 female and 350 male). Baseline characteristics were balanced between both groups. The between-group difference in mean change from baseline in CDR-SB score (placebo minus crenezumab) was -0.17 (95% CI, -0.86 to 0.53; P = .63) at week 105 in the CREAD study (88 placebo; 86 crenezumab). Compared with previous trials, no new safety signals were identified, and amyloid-related imaging abnormalities with edema were rare, mild, and transient. No meaningful changes in AD biomarkers were observed. Both studies were discontinued following a preplanned interim analysis indicating that CREAD was unlikely to meet the primary end point. Conclusions and Relevance: Crenezumab was well tolerated but did not reduce clinical decline in participants with early AD. Trial Registration: ClinicalTrials.gov Identifiers: CREAD, NCT02670083; CREAD2, NCT03114657.

Population Pharmacokinetics and Exposure-Response Relationships of Astegolimab in Patients With Severe Asthma.

Astegolimab is a fully human immunoglobulin G2 monoclonal antibody that binds to the ST2 receptor and blocks the interleukin-33 signaling. It was evaluated in patients with uncontrolled severe asthma in the phase 2b study (Zenyatta) at doses of 70, 210, and 490 mg subcutaneously every 4 weeks for 52 weeks. This work aimed to characterize astegolimab pharmacokinetics, identify influential covariates contributing to its interindividual variability, and make a descriptive assessment of the exposure-response relationships. A population pharmacokinetic model was developed using data from 368 patients in the Zenyatta study. Predicted average steady-state concentration was used in the subsequent exposure-response analyses, which evaluated efficacy (asthma exacerbation rate) and biomarker end points including forced expiratory volume in 1 second, fraction exhaled nitric oxide, blood eosinophils, and soluble ST2. A 2-compartment disposition model with first-order elimination and first-order absorption best described the astegolimab pharmacokinetics. The relative bioavailability for the 70-mg dose was 15.3% lower. Baseline body weight, estimated glomerular filtration rate, and eosinophils were statistically correlated with pharmacokinetic parameters, but only body weight had a clinically meaningful influence on the steady-state exposure (ratios exceeding 0.8-1.25). The exposure-response of efficacy and biomarkers were generally flat with a weak trend in favor of the highest dose/exposure. This study characterized astegolimab pharmacokinetics in patients with asthma and showed typical pharmacokinetic behavior as a monoclonal antibody-based drug. The exposure-response analyses suggested the highest dose tested in the Zenyatta study (490 mg every 4 weeks) performed close to the maximum effect, and no additional response may be expected above it.

A longitudinal model for the Mayo Clinical Score and its sub-components in patients with ulcerative colitis.

Clinical trials in patients with ulcerative colitis (UC) face the challenge of high and variable placebo response rates. The Mayo Clinical Score (MCS) is used widely as the primary endpoint in clinical trials to describe the clinical status of patients with UC. The MCS is comprised of four subscores, each scored 0, 1, 2 and 3: rectal bleeding (RB), stool frequency (SF), physician's global assessment (PGA), and endoscopy (ENDO) subscore. Excluding the PGA subscore gives the modified MCS. Quantitative insight on the placebo response, and its impact on the components of the MCS over time, can better inform clinical trial design and interpretation. Longitudinal modeling of the MCS, and the modified MCS, can be challenging due to complex clinical trial design, population heterogeneity, and limited assessments for the ENDO subscore. The current study pooled patient-level placebo/standard of care (SoC) arm data from five clinical trials in the TransCelerate database to develop a longitudinal placebo response model that describes the MCS over time in patients with UC. MCS subscores were modeled using proportional odds models, and the removal of patients from the placebo/SoC arm, or "dropout", was modeled using logistic regression models. The subscore and dropout models were linked to allow for the prediction of the MCS and the modified MCS. Stepwise covariate modeling identified prior exposure to TNF-α antagonists as a statistically significant predictor on the RB + SF subscore. Patients with prior exposure to TNF-α antagonists had higher post-baseline RB + SF subscores than naive patients.

Pharmacokinetics and exposure-efficacy relationships of omalizumab in patients with nasal polyps.

The anti-immunoglobulin E (IgE) antibody, omalizumab (Xolair), is approved in the United States for the treatment of allergic asthma and chronic spontaneous urticaria, and has recently been studied for the treatment of nasal polyposis following completion of the two replicate phase 3 studies (POLYP 1 and POLYP 2). The dosing of omalizumab used in the phase 3 studies is based on a combination of patients' pre-treatment IgE level and body weight, similar to the approach used in allergic asthma. The objectives of the current analyses were to evaluate whether the pharmacokinetics (PK) of omalizumab and its pharmacodynamic (PD) effect on free and total IgE level in chronic rhinosinusitis with nasal polyps (CRSwNP) are consistent with those in allergic asthma via population PK/PD modeling and simulation, and to graphically explore exposure-response relationships and free IgE-response relationships in CRSwNP. Omalizumab PK and PD effect of total and free IgE in CRSwNP are generally consistent with those in asthma. Observed post-treatment free IgE suppressions were generally within the target range of the baseline IgE- and body weight-based omalizumab dosing table, with 74.2% and 93.0% of patients achieving a serum free IgE level below 25 ng/mL and 50 ng/mL, respectively at Week 24. Exposure-response analyses indicated that there was no clear correlation between omalizumab or free IgE concentration and key efficacy endpoints within the POLYP studies. Overall, these results indicate that the body weight and IgE-based dosing regimen of omalizumab was appropriate for use in CRSwNP patients.

Safety, Tolerability, and Pharmacokinetics of High-Volume Subcutaneous Crenezumab, With and Without Recombinant Human Hyaluronidase in Healthy Volunteers.

Compared with intravenous formulations, subcutaneous (s.c.) formulations of therapeutic monoclonal antibodies may provide increased patient access and more convenient administration options, although historically high-volume s.c. administration (> 10-15 mL) has been challenging. We report results from two phase I studies in healthy participants (GP29523 and GP40201) that evaluated s.c. crenezumab, an anti-Aß monoclonal antibody in development for individuals at risk for autosomal-dominant Alzheimer's disease. GP29523 assessed safety, tolerability, and pharmacokinetics (PK) in 68 participants (aged 50-80 years) who received single ascending doses (600-7,200 mg) of crenezumab or placebo (4-40 mL). GP40201 assessed safety, tolerability, and PK in 72 participants (aged 18-80 years) who received different combinations of dose (1,700-6,800 mg), infusion volume (10-40 mL), and flow rate (2-4 mL/minute), with/without recombinant human hyaluronidase (rHuPH20). There were no serious or dose-limiting adverse events in either study. There were no meaningful differences in pain scores among reference placebo (4 mL), test placebo (4-40 mL), or crenezumab (600-7,200 mg) in GP29523, or across treatments with varying infusion volume, flow rate, dose, or rHuPH20 co-administration or concentration in GP40201. Transient erythema was the most common infusion site reaction in both studies. In GP40201 at volumes of ≥ 20 mL, rHuPH20 co-administration appeared to reduce infusion site swelling incidence, but, in some cases, was associated with larger areas of infusion site erythema. Crenezumab exhibited approximately dose-proportional PK, and s.c. bioavailability was 66% and independent of dose or rHuPH20 co-administration. High-dose, high-concentration, high-volume s.c. crenezumab formulated with/without rHuPH20 was well-tolerated in healthy participants, with an acceptable safety profile.

Population repeated time-to-event analysis of exacerbations in asthma patients: A novel approach for predicting asthma exacerbations based on biomarkers, spirometry, and diaries/questionnaires.

Identification of covariates, including biomarkers, spirometry, and diaries/questionnaires, that predict asthma exacerbations would allow better clinical predictions, shorter phase II trials and inform decisions on phase III design, and/or initiation (go/no-go). The objective of this work was to characterize asthma-exacerbation hazard as a function of baseline and time-varying covariates. A repeated time-to-event (RTTE) model for exacerbations was developed using data from a 52-week phase IIb trial, including 502 patients with asthma randomized to placebo or 70 mg, 210 mg, or 490 mg astegolimab every 4 weeks. Covariate analysis was performed for 20 baseline covariates using the full random effects modeling approach, followed by time-varying covariate analysis of nine covariates using the stepwise covariate model (SCM) building procedure. Following the SCM, an astegolimab treatment effect was explored. Diary-based symptom score (difference in objective function value [dOFV] of -83.7) and rescue medication use (dOFV = -33.5), and forced expiratory volume in 1 s (dOFV = -14.9) were identified as significant time-varying covariates. Of note, time-varying covariates become more useful with more frequent measurements, which should favor the daily diary scores over others. The most influential baseline covariates were exacerbation history and diary-based symptom score (i.e., symptom score was important as both time-varying and baseline covariate). A (nonsignificant) astegolimab treatment effect was included in the final model because the limited data set did not allow concluding the remaining effect size as irrelevant. Without time-varying covariates, the treatment effect was statistically significant (p < 0.01). This work demonstrated the utility of a population RTTE approach to characterize exacerbation hazard in patients with severe asthma.

Population pharmacokinetic and exploratory exposure-response analysis of the fixed-dose combination of pertuzumab and trastuzumab for subcutaneous injection in patients with HER2-positive early breast cancer in the FeDeriCa study.

PURPOSE: To characterize pertuzumab pharmacokinetics (PK) in FeDeriCa (NCT03493854: fixed-dose combination of pertuzumab and trastuzumab for subcutaneous injection [PH FDC SC] versus intravenous pertuzumab plus trastuzumab); derive individual pertuzumab exposures in the PH FDC SC arm for subsequent pertuzumab exposure-response (ER) analyses; compare observed trastuzumab PK with predicted exposures from a previous SC trastuzumab model; assess whether pertuzumab affects trastuzumab PK; evaluate pertuzumab exposure-efficacy and -safety relationships and support the approved SC dosing regimen. METHODS: Population pharmacokinetic modeling and simulations were used to describe the data. Standard goodness-of-fit diagnostics and prediction-corrected visual predictive checks were used for model performance assessment. Covariates were included from previously reported models. ER analysis was conducted using logistic regression. RESULTS: SC pertuzumab PK was described adequately by a two-compartment model with first-order absorption; significant covariates included in the final model were albumin, lean body weight, and Asian region; however, these appeared not to be clinically relevant. Trastuzumab concentrations were described adequately by the previous model; there was no evidence of a pertuzumab effect on trastuzumab PK as part of PH FDC SC and higher model-predicted pertuzumab exposure was not associated with differences in pathologic complete response rate or an increased probability of selected grade ≥ 3 adverse events of interest. CONCLUSION: The approved PH FDC SC dose [loading: 1200/600 mg pertuzumab/trastuzumab (15 mL); maintenance: 600 mg pertuzumab/trastuzumab (10 mL) and 2000 U/mL recombinant human hyaluronidase every 3 weeks] provides a positive benefit-risk profile with comparable efficacy and safety to intravenous pertuzumab plus trastuzumab.

Translational and pharmacokinetic-pharmacodynamic application for the clinical development of GDC-0334, a novel TRPA1 inhibitor.

GDC-0334 is a novel small molecule inhibitor of transient receptor potential cation channel member A1 (TRPA1), a promising therapeutic target for many nervous system and respiratory diseases. The pharmacokinetic (PK) profile and pharmacodynamic (PD) effects of GDC-0334 were evaluated in this first-in-human (FIH) study. A starting single dose of 25 mg was selected based on integrated preclinical PK, PD, and toxicology data following oral administration of GDC-0334 in guinea pigs, rats, dogs, and monkeys. Human PK and PK-PD of GDC-0334 were characterized after single and multiple oral dosing using a population modeling approach. The ability of GDC-0334 to inhibit dermal blood flow (DBF) induced by topical administration of allyl isothiocyanate (AITC) was evaluated as a target-engagement biomarker. Quantitative models were developed iteratively to refine the parameter estimates of the dose-concentration-effect relationships through stepwise estimation and extrapolation. Human PK analyses revealed that bioavailability, absorption rate constant, and lag time increase when GDC-0334 was administered with food. The inhibitory effect of GDC-0334 on the AITC-induced DBF biomarker exhibited a clear sigmoid-Emax relationship with GDC-0334 plasma concentrations in humans. This study leveraged emerging preclinical and clinical data to enable iterative refinement of GDC-0334 mathematical models throughout the FIH study for dose selection in subsequent cohorts throughout the study. Study Highlights WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC? GDC-0334 is a novel, small molecule TRPA1 inhibitor and a pharmacokinetic-pharmacodynamic (PK-PD) modeling strategy could be implemented in a systematic and step-wise manner to build and learn from emerging data for early clinical development. WHAT QUESTION DID THIS STUDY ADDRESS? Can noncompartmental and population-based analyses be used to describe the PK and PD characteristics of GDC-0334 in preclinical and clinical studies? WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE? GDC-0334 exposure generally increased with dose in rats, dogs, and monkeys. The starting dose (25 mg) in the clinical study was determined based on the preclinical data. GDC-0334 exhibited linear PK in humans and the bioavailability was increased with food. The inhibitory effect of GDC-0334 on dermal blood flow induced by the TRPA1 agonist allyl isothiocyanate in humans indicates a clear PK-PD relationship. HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE? The models developed based on TRPA1 agonist-induced dermal blood flow inhibition data can be used to predict PK-PD relationships in future preclinical and clinical studies evaluating new drug entities that target TRPA1.

Tumor growth inhibition modeling of individual lesion dynamics and interorgan variability in HER2-negative breast cancer patients treated with docetaxel.

Information on individual lesion dynamics and organ location are often ignored in pharmacometric modeling analyses of tumor response. Typically, the sum of their longest diameters is utilized. Herein, a tumor growth inhibition model was developed for describing the individual lesion time-course data from 183 patients with metastatic HER2-negative breast cancer receiving docetaxel. The interindividual variability (IIV), interlesion variability (ILV), and interorgan variability of parameters describing the lesion time-courses were evaluated. Additionally, a model describing the probability of new lesion appearance and a time-to-event model for overall survival (OS), were developed. Before treatment initiation, the lesions were largest in the soft tissues and smallest in the lungs, and associated with a significant IIV and ILV. The tumor growth rate was 2.6 times higher in the breasts and liver, compared with other metastatic sites. The docetaxel drug effect in the liver, breasts, and soft tissues was greater than or equal to 1.2 times higher compared with other organs. The time-course of the largest lesion, the presence of at least 3 liver lesions, and the time since study enrollment, increased the probability of new lesion appearance. New lesion appearance, along with the time to growth and time-course of the largest lesion at baseline, were identified as the best predictors of OS. This tumor modeling approach, incorporating individual lesion dynamics, provided a more complete understanding of heterogeneity in tumor growth and drug effect in different organs. Thus, there may be potential to tailor treatments based on lesion location, lesion size, and early lesion response to provide better clinical outcomes.

Safety, Tolerability, and Pharmacokinetics of Crenezumab in Patients with Mild-to-Moderate Alzheimer's Disease Treated with Escalating Doses for up to 133 Weeks.

BACKGROUND: Crenezumab is a fully humanized, monoclonal anti-amyloid-ß immunoglobulin G4 antibody. OBJECTIVE: This Phase Ib study (NCT02353598) evaluated the safety, tolerability, and pharmacokinetics of crenezumabat doses of ≤120 mg/kg administered intravenously every 4 weeks (q4w). Immunogenicity and exploratory biomarkers were also evaluated. METHODS: In this multicenter, double-blind study, participants (aged 50-90 years) with mild-to-moderate Alzheimer's disease (AD) and amyloid-positive positron emission tomography (PET) scan were randomized to receive crenezumab 30 or 45 mg/kg (Cohort 1, n = 21), 60 mg/kg (Cohort 2, n = 21), or 120 mg/kg (Cohort 3, n = 19) or corresponding placebo (n = 14) intravenously q4w for 13 weeks. Seventy-one participants were subsequently enrolled in an optional open-label extension (OLE) and received crenezumab at the originally assigned dose level, except for Cohort 3 (crenezumab 60 mg/kg during OLE). Participants received regular brain MRIs to assess amyloid-related imaging abnormalities (ARIA). Results up to Week 133 are reported. RESULTS: Approximately 94% of participants experienced ≥1 adverse event (AE). Most AEs were mild or moderate; 15.5% experienced a Grade ≥3 AE. No ARIA-edema/effusion (ARIA-E) events were observed. New ARIA-micro hemorrhages and hemosiderosis (ARIA-H) were reported in 4.9% (double-blind treatment period) and 9.9% (combined double-blind treatment and OLE periods) of participants. Steady-state trough concentrations of crenezumab were dose-proportional and maintained for each dose level. CONCLUSION: Crenezumab doses of ≤120 mg/kg intravenously q4w were well tolerated. The observed safety profile for ≤133 weeks of treatment in a mild-to-moderate AD population was similar to that seen in previous trials.

Mechanistic Modeling of Soluble Aß Dynamics and Target Engagement in the Brain by Anti-Aß mAbs in Alzheimer's Disease.

BACKGROUND: Anti-amyloid-ß (Aß) monoclonal antibodies (mAbs) are currently in development for treating Alzheimer's disease. OBJECTIVES: To address the complexity of Aß target engagement profiles, improve the understanding of crenezumab Pharmacokinetics (PK) and Aß Pharmacodynamics (PD) in the brain, and facilitate comparison of anti-Aß therapies with different binding characteristics. METHODS: A mechanistic mathematical model was developed describing the distribution, elimination, and binding kinetics of anti-Aß mAbs and Aß (monomeric and oligomeric forms of Aß1-40 and Aß1-42) in the brain, Cerebrospinal Fluid (CSF), and plasma. Physiologically meaningful values were assigned to the model parameters based on the previous data, with remaining parameters fitted to clinical measurements of Aß concentrations in CSF and plasma, and PK/PD data of patients undergoing anti-Aß therapy. Aß target engagement profiles were simulated using a Monte Carlo approach to explore the impact of biological uncertainty in the model parameters. RESULTS: Model-based estimates of in vivo affinity of the antibody to monomeric Aß were qualitatively consistent with the previous data. Simulations of Aß target engagement profiles captured observed mean and variance of clinical PK/PD data. CONCLUSION: This model is useful for comparing target engagement profiles of different anti-Aß therapies and demonstrates that 60 mg/kg crenezumab yields a significant increase in Aß engagement compared with lower doses of solanezumab, supporting the selection of 60 mg/kg crenezumab for phase 3 studies. The model also provides evidence that the delivery of sufficient quantities of mAb to brain interstitial fluid is a limiting step with respect to the magnitude of soluble Aß oligomer neutralization.

Pharmacokinetics and pharmacodynamic effect of crenezumab on plasma and cerebrospinal fluid beta-amyloid in patients with mild-to-moderate Alzheimer's disease.

BACKGROUND: Crenezumab, a fully humanized anti-beta-amyloid (Aß) immunoglobulin G4 (IgG4) monoclonal antibody, binds to both monomeric and aggregated forms of Aß. We assessed the pharmacokinetics (PK)/pharmacodynamics (PD) of crenezumab and its interaction with monomeric Aß(1-40) and Aß(1-42) peptides in serum/plasma and cerebrospinal fluid (CSF) samples from the phase II ABBY and BLAZE studies and the phase Ib GN29632 study. METHODS: In ABBY, BLAZE, and GN29632 studies, patients with mild-to-moderate AD were treated with either placebo or crenezumab (300 mg subcutaneously every 2 weeks [q2w], or 15 mg/kg, 30 mg/kg, 45 mg/kg, 60 mg/kg, or 120 mg/kg intravenously q4w). Serum/plasma PK/PD analyses included samples from 131 patients who received crenezumab in all three studies. CSF PK/PD analyses included samples from 76 patients who received crenezumab in ABBY or BLAZE. The impact of baseline patient factors on Aß profiles was also evaluated. RESULTS: The serum concentration of crenezumab increased in a dose-proportional manner between 15 and 120 mg/kg q4w. Total monomeric plasma Aß(1-40) and Aß(1-42) levels significantly increased after crenezumab administration. The mean crenezumab CSF to serum ratio was ~ 0.3% and was similar across dosing cohorts/routes of administration. No clear correlation was observed between crenezumab concentration and Aß(1-42) increase in CSF at week 69. The target-mediated drug disposition (TMDD) model described the observed plasma concentration-time profiles of crenezumab and Aß well. Elimination clearance (CLel) and central volume of distribution (Vcent) of crenezumab were estimated at 0.159 L/day and 2.89 L, respectively, corresponding to a half-life of ~ 20 days. Subcutaneous bioavailability was estimated at 66.2%. CONCLUSIONS: Crenezumab PK was dose proportional up to 120 mg/kg, with a half-life consistent with IgG monoclonal antibodies. Our findings provide evidence for peripheral target engagement in patients with mild-to-moderate AD. The study also showed that a model-based approach is useful in making inference on PK/PD relationship with unmeasured species such as free plasma Aß levels. TRIAL REGISTRATIONS: ABBY: ClinicalTrials.gov, NCT01343966. Registered April 28, 2011. BLAZE: ClinicalTrials.gov, NCT01397578. Registered July 19, 2011. GN29632: ClinicalTrials.gov, NCT02353598. Registered February 3, 2015.

Correction to: Population Pharmacokinetics, Efficacy Exposure-response Analysis, and Model-based Meta-analysis of Fenebrutinib in Subjects with Rheumatoid Arthritis.

The article was published with an incomplete title. The complete title is "Population Pharmacokinetics, Efficacy Exposure-response Analysis, and Model-based Meta-analysis of Fenebrutinib in Subjects with Rheumatoid Arthritis" The original article has been corrected.