Population pharmacokinetics and exposure-response analyses of safety (ARIA-E and isolated ARIA-H) of lecanemab in subjects with early Alzheimer's disease.

Lecanemab (Leqembi®) was recently approved by health authorities in the United States, Japan, and China to treat early Alzheimer's disease (AD), including patients with mild cognitive impairment (MCI) or mild dementia due to Alzheimer's disease upon confirmation of amyloid beta pathology. Extensively and sparsely sampled PK profiles from 1619 AD subjects and 21,929 serum lecanemab observations from two phase I, one phase II, and one phase III studies were well characterized using a two-compartment model with first-order elimination. The final PK model quantified covariate effects of body weight and sex on clearance and central volume of distribution, ADA-positive status, and albumin on clearance, and of Japanese ethnicity on central and peripheral volumes of distribution. Exposure to lecanemab was comparable between two lecanemab-manufacturing processes. However, none of the identified covariates in the model had a clinically relevant impact on model-predicted lecanemab Cmax or AUC at steady state following 10 mg/kg bi-weekly. Importantly, age, a well-recognized risk factor for AD, was not found to significantly affect lecanemab PK. The incidence of ARIA-E as a function of lecanemab exposure was modeled using a logit function with data pooled from 2641 subjects from the phase II and phase III studies, in which a total of 177 incidences of ARIA-E were observed. The probability of ARIA-E was significantly correlated with model-predicted Cmax and predicted to be higher in subjects homozygous for APOE4. The incidence of isolated ARIA-H was not associated with lecanemab exposure and was similar between placebo and lecanemab-treated subjects.

Safety, Tolerability, and Pharmacokinetics of Zagotenemab in Participants with Symptomatic Alzheimer's Disease: A Phase I Clinical Trial.

Background: Zagotenemab (LY3303560), a monoclonal antibody, preferentially binds to extracellular, misfolded, aggregated tau that has been implicated in Alzheimer's disease (AD). Objective: The goal of this study was to assess the safety and pharmacokinetics of multiple doses of zagotenemab in participants with AD. Methods: This was a Phase Ib, multi-site, participant- and investigator-blind, placebo-controlled, parallel-group study in participants with mild cognitive impairment due to AD or mild to moderate AD. After screening, participants were randomized to zagotenemab 70 mg, 210 mg, or placebo every 4 weeks for up to 49 weeks and were followed up for 16 weeks. Results: A total of 13 males and 9 females, aged 59 to 84 years, were dosed. No deaths occurred during this study. A total of 4 serious adverse events occurred in 2 participants who then discontinued the study. The most commonly reported (3 or more participants) treatment-emergent adverse events were sinus bradycardia, headache, fall, and bronchitis. The pharmacokinetics profile showed generally linear exposures across the dose range studied with a clearance of ~8 mL/h. The half-life of zagotenemab in serum was ~20 days. A dose-dependent increase in plasma tau was observed. No other significant pharmacodynamic differences were observed due to low dose levels and limited treatment duration. Conclusions: No dose-limiting adverse events were observed with zagotenemab treatment. Pharmacokinetics of zagotenemab were typical for a monoclonal antibody. Meaningful pharmacodynamic differences were not observed.Clinicaltrials.gov: NCT03019536.

Donanemab exposure and efficacy relationship using modeling in Alzheimer's disease.

INTRODUCTION: Donanemab is an amyloid-targeting therapy that specifically targets brain amyloid plaques. The objective of these analyses was to characterize the relationship of donanemab exposure with plasma biomarkers and clinical efficacy through modeling. METHODS: Data for the analyses were from participants with Alzheimer's disease from the phase 1 and TRAILBLAZER-ALZ studies. Indirect-response models were used to fit plasma phosphorylated tau 217 (p-tau217) and plasma glial fibrillated acidic protein (GFAP) data over time. Disease-progression models were developed using pharmacokinetic/pharmacodynamic modeling. RESULTS: The plasma p-tau217 and plasma GFAP models adequately predicted the change over time, with donanemab resulting in decreased plasma p-tau217 and plasma GFAP concentrations. The disease-progression models confirmed that donanemab significantly reduced the rate of clinical decline. Simulations revealed that donanemab slowed disease progression irrespective of baseline tau positron emission tomography (PET) level within the evaluated population. DISCUSSION: The disease-progression models show a clear treatment effect of donanemab on clinical efficacy regardless of baseline disease severity.

Donanemab Population Pharmacokinetics, Amyloid Plaque Reduction, and Safety in Participants with Alzheimer's Disease.

Donanemab is an amyloid-targeting therapy that resulted in robust amyloid plaque reduction and slowed Alzheimer's disease (AD) progression compared with placebo in the phase II TRAILBLAZER-ALZ study (NCT03367403). The objectives of the current analyses are to characterize (i) the population pharmacokinetics of donanemab, (ii) the relationship between donanemab exposure and amyloid plaque reduction (response), and (iii) the relationship between donanemab exposure and amyloid-related imaging abnormalities with edema or effusions (ARIA-E). Model development included data from participants with mild cognitive impairment or mild to moderate dementia due to AD from the phase Ib study on donanemab (NCT02624778) and participants with early symptomatic AD from the TRAILBLAZER-ALZ study. The analysis showed donanemab has a terminal elimination half-life of 11.8 days. Body weight and antidrug antibody titer impact donanemab exposure but not the pharmacodynamic response. Maintaining a donanemab serum concentration above 4.43 µg/mL (95% confidence interval: 0.956, 10.4) is associated with amyloid plaque reduction. The time to achieve amyloid plaque clearance (amyloid plaque level < 24.1 Centiloids) varied depending on the baseline amyloid level, where higher baseline levels were associated with fewer participants achieving amyloid clearance. The majority of participants achieved amyloid clearance by 52 weeks on treatment. Apolipoprotein ε4 carriers, irrespective of donanemab serum exposure, were 4 times more likely than noncarriers to have an ARIA-E event by 24 weeks.

Disease progression model using the integrated Alzheimer's Disease Rating Scale.

INTRODUCTION: An Alzheimer's disease (AD) dementia disease progression model was developed based on the integrated Alzheimer's Disease Rating Scale (iADRS). METHODS: Data from 3483 placebo participants in six AD trials were used to develop the disease progression model with NONMEM (version 7.4.2) and examined for mild cognitive impairment, and mild and moderate dementia due to AD. RESULTS: Baseline iADRS score was significantly influenced by AD symptomatic medication use, EXPEDITION2 enrollment (included moderate AD participants), age, and baseline Mini-Mental State Examination (MMSE) score. Rate of disease progression increased across disease stage and was significantly influenced by AD medication use, age, and baseline MMSE score. Apolipoprotein E ε4 carrier status did not influence baseline iADRS score or disease progression. DISCUSSION: These results demonstrate a disease progression model describing the time course of the iADRS across the AD severity spectrum. This model can assist future clinical trials in study design optimization and treatment effect interpretation. HIGHLIGHTS: A disease progression model described the integrated Alzheimer's Disease Rating Scale (iADRS) time course in mild cognitive impairment to moderate Alzheimer's disease. Using the linear regression model, iADRS scores can be calculated for Mini-Mental State Examination scores. Results can help optimize future clinical trial design and aid in understanding treatment effects.

Association of Amyloid Reduction After Donanemab Treatment With Tau Pathology and Clinical Outcomes: The TRAILBLAZER-ALZ Randomized Clinical Trial.

Importance: ß-amyloid plaques and neurofibrillary tau deposits biologically define Alzheimer disease. Objective: To perform post hoc analyses of amyloid reduction after donanemab treatment and assess its association with tau pathology and clinical measures. Design, Setting, and Participants: The Study of LY3002813 in Participants With Early Symptomatic Alzheimer's Disease (TRAILBLAZER-ALZ) was a phase 2, placebo-controlled, randomized clinical trial conducted from December 18, 2017, to December 4, 2020, with a double-blind period of up to 76 weeks and a 48-week follow-up period. The study was conducted at 56 centers in the US and Canada. Enrolled were participants from 60 to 85 years of age with gradual and progressive change in memory function for 6 months or more, early symptomatic Alzheimer disease, elevated amyloid, and intermediate tau levels. Interventions: Donanemab (an antibody specific for the N-terminal pyroglutamate ß-amyloid epitope) dosing was every 4 weeks: 700 mg for the first 3 doses, then 1400 mg for up to 72 weeks. Blinded dose-reduction evaluations occurred at 24 and 52 weeks based on amyloid clearance. Main Outcomes and Measures: Change in amyloid, tau, and clinical decline after donanemab treatment. Results: The primary study randomized 272 participants (mean [SD] age, 75.2 [5.5] years; 145 female participants [53.3%]). The trial excluded 1683 of 1955 individuals screened. The rate of donanemab-induced amyloid reduction at 24 weeks was moderately correlated with the amount of baseline amyloid (Spearman correlation coefficient r, -0.54; 95% CI, -0.66 to -0.39; P < .001). Modeling provides a hypothesis that amyloid would not reaccumulate to the 24.1-centiloid threshold for 3.9 years (95% prediction interval, 1.9-8.3 years) after discontinuing donanemab treatment. Donanemab slowed tau accumulation in a region-dependent manner as measured using neocortical and regional standardized uptake value ratios with cerebellar gray reference region. A disease-progression model found a significant association between percentage amyloid reduction and change on the integrated Alzheimer Disease Rating Scale only in apolipoprotein E (APOE) ε4 carriers (95% CI, 24%-59%; P < .001). Conclusions and Relevance: Results of post hoc analyses for donanemab-treated participants suggest that baseline amyloid levels were directly associated with the magnitude of amyloid reduction and inversely associated with the probability of achieving complete amyloid clearance. The donanemab-induced slowing of tau was more pronounced in those with complete amyloid clearance and in brain regions identified later in the pathologic sequence. Data from other trials will be important to confirm aforementioned observations, particularly treatment response by APOE ε4 status. Trial Registration: ClinicalTrials.gov Identifier: NCT03367403.

Robust Pharmacodynamic Effect of LY3202626, a Central Nervous System Penetrant, Low Dose BACE1 Inhibitor, in Humans and Nonclinical Species.

BACKGROUND: The development of beta-site amyloid-beta precursor protein cleaving enzyme (BACE) 1 inhibitors for the treatment of Alzheimer's disease requires optimization of inhibitor potency, selectivity, and brain penetration. Moreover, there is a need for low-dose compounds since liver toxicity was found with some BACE inhibitors. OBJECTIVE: To determine whether the high in vitro potency and robust pharmacodynamic effect of the BACE inhibitor LY3202626 observed in nonclinical species translated to humans. METHODS: The effect of LY3202626 versus vehicle on amyloid-ß (Aß) levels was evaluated in a series of in vitro assays, as well as in in vivo and multi-part clinical pharmacology studies. Aß levels were measured using analytical biochemistry assays in brain, plasma, and cerebrospinal fluid (CSF) of mice, dogs and humans. Nonclinical data were analyzed using an ANOVA followed by Tukey's post hoc test and clinical data used summary statistics. RESULTS: LY3202626 exhibited significant human BACE1 inhibition, with an IC50 of 0.615±0.101 nM in a fluorescence resonance energy transfer assay and an EC50 of 0.275±0.176 nM for lowering Aß1-40 and 0.228±0.244 nM for Aß1-42 in PDAPP neuronal cultures. In dogs, CSF Aß1hboxx concentrations were significantly reduced by ∼80% at 9 hours following a 1.5 mg/kg dose. In humans, CSF Aß1-42 was reduced by 73.1±7.96 % following administration of 6 mg QD. LY3202626 was found to freely cross the blood-brain barrier in dogs and humans. CONCLUSION: LY3202626 is a potent BACE1 inhibitor with high blood-brain barrier permeability. The favorable safety and pharmacokinetic/pharmacodynamic profile of LY3202626 supports further clinical development.

Phase II (NAVIGATE-AD study) Results of LY3202626 Effects on Patients with Mild Alzheimer's Disease Dementia.

BACKGROUND: LY3202626 is a small molecule inhibitor of ß-site amyloid precursor protein cleaving enzyme (BACE)1 shown to reduce amyloid-ß (Aß)1-40 and Aß1-42 concentrations in plasma and cerebrospinal fluid developed for the treatment of Alzheimer's disease (AD). OBJECTIVE: To assess the change from baseline in flortaucipir positron emission tomography (PET) after treatment with LY3202626 compared with placebo in patients with mild AD dementia. METHODS: Patients received daily 3 mg or 12 mg doses of LY3202626 or placebo for 52 weeks. The primary outcome was assessment of cerebral neurofibrillary tangle load by flortaucipir PET. The study was terminated early following an interim analysis due to a low probability of identifying a statistically significant slowing of cognitive and/or functional decline. RESULTS: A total of 316 patients were randomized and 47 completed the study. There was no statistically significant difference between placebo and either dose of LY3202626 from baseline to 52 weeks, or in annualized change for flortaucipir PET. There was no clinically meaningful difference between placebo and LY3202626 doses on efficacy measures of cognition and function. No deaths or serious adverse events considered related to LY3202626 were reported. A statistically significant increase in treatment-emergent adverse events in the psychiatric disorders system organ class was reported for both LY3202626 doses compared to placebo. CONCLUSION: LY3202626 tested at doses generating 70-90% BACE inhibition was generally well tolerated in this study. LY3202626 treatment did not result in a clinically significant change in cerebral tau burden as measured by flortaucipir nor in change of functional or cognitive decline compared to placebo.

Discovery and Early Clinical Development of LY3202626, a Low-Dose, CNS-Penetrant BACE Inhibitor.

The beta-site APP cleaving enzyme 1, known as BACE1, has been a widely pursued Alzheimer's disease drug target owing to its critical role in the production of amyloid-beta. We have previously reported the clinical development of LY2811376 and LY2886721. LY2811376 advanced to Phase I before development was terminated due to nonclinical retinal toxicity. LY2886721 advanced to Phase II, but development was halted due to abnormally elevated liver enzymes. Herein, we report the discovery and clinical development of LY3202626, a highly potent, CNS-penetrant, and low-dose BACE inhibitor, which successfully addressed these key development challenges.

Donanemab (LY3002813) dose-escalation study in Alzheimer's disease.

INTRODUCTION: This study explored the safety and tolerability features of donanemab (LY3002813) in patients with mild cognitive impairment due to Alzheimer's disease (AD) or mild to moderate AD dementia. METHODS: Patients with AD were enrolled into the single-ascending dose phase and were administered a single, intravenous (IV) dose of donanemab (five dosing cohorts from 0.1 to 10 mg/kg) or placebo followed by a 12-week follow-up period for each dose level. After the follow-up period, the same patients proceeded into the multiple-ascending dose (MAD) phase (five cohorts) and were administered IV doses of donanemab (0.3 to 10 mg/kg) or placebo approximately once per month for up to four doses depending on the initial doses (only cohort 1 went from 0.1 mg/kg to a higher dose of 0.3 mg/kg during the MAD phase). This phase concluded with a 12-week follow-up period. The relative exposure assessment of an unblinded, single, subcutaneous 3-mg/kg dose of donanemab in patients with AD was also performed, followed by a 12-week follow-up period. One cohort of healthy subjects received an unblinded, single, IV 1-mg/kg dose of donanemab. These two cohorts did not continue to the MAD phase. RESULTS: Donanemab was generally well tolerated up to 10 mg/kg. After single-dose administration from 0.1 to 3.0 mg/kg, the mean terminal elimination half-life was ≈4 days, increasing to ≈10 days at 10 mg/kg. Only the 10-mg/kg dose showed changes in amyloid positron emission tomography. Amyloid reduction of 40% to 50% was achieved. Approximately 90% of subjects developed anti-drug antibodies at 3 months after a single intravenous dose. DISCUSSION: Intravenous donanemab 10 mg/kg can reduce amyloid deposits in AD despite having a shorter than expected half-life.

An integrated PK-PD model for cortisol and the 17-hydroxyprogesterone and androstenedione biomarkers in children with congenital adrenal hyperplasia.

AIMS: The aim of this study was to characterize the pharmacokinetic/pharmacodynamic relationships of cortisol and the adrenal biomarkers 17-hydroxyprogesterone and androstenedione in children with congenital adrenal hyperplasia (CAH). METHODS: A nonlinear mixed-effect modelling approach was used to analyse cortisol, 17-hydroxyprogesterone and androstenedione concentrations obtained over 6 hours from children with CAH (n = 50). A circadian rhythm was evident and the model leveraged literature information on circadian rhythm in untreated children with CAH. Indirect response models were applied in which cortisol inhibited the production rate of all three compounds using an Imax model. RESULTS: Cortisol was characterized by a one-compartment model with apparent clearance and volume of distribution estimated at 22.9 L/h/70 kg and 41.1 L/70 kg, respectively. The IC50 values of cortisol concentrations for cortisol, 17-hydroxyprogesterone and androstenedione were estimated to be 1.36, 0.45 and 0.75 µg/dL, respectively. The inhibitory effect was found to be more potent on 17OHP than D4A, and the IC50 values were higher in salt-wasting subjects than simple virilizers. Production rates of cortisol, 17-hydroxyprogesterone and androstenedione were higher in simple-virilizer subjects. Half-lives of cortisol, 17-hydroxyprogesterone and androstenedione were 60, 47 and 77 minutes, respectively. CONCLUSION: Rapidly changing biomarker responses to cortisol concentrations highlight that single measurements provide volatile information about a child's disease control. Our model closely captured observed cortisol, 17-hydroxyprogesterone and androstenedione concentrations. It can be used to predict concentrations over 24 hours and allows many novel exposure metrics to be calculated, e.g., AUC, AUC-above-threshold, time-within-range, etc. Our long-range goal is to uncover dose-exposure-outcome relationships that clinicians can use in adjusting hydrocortisone dose and timing.

Assessment of Transporter Polymorphisms as a Factor in a BCRP Drug Interaction Study With Lanabecestat.

Lanabecestat is a human ß-site amyloid precursor protein-cleaving enzyme 1 inhibitor in development to slow disease progression in patients with early Alzheimer's disease. The study evaluated the breast cancer resistance protein (BCRP) inhibition potential of lanabecestat on the pharmacokinetics (PK) of rosuvastatin, a probe for BCRP activity, in healthy white subjects who were not carriers of SLCO1B1 (c.521T>C), not homozygotes for ABCG2 (c.421C>A or c.34G>A), and not heterozygotes of ABCG2 (c.421C>A and c.34G>A). The safety of lanabecestat + rosuvastatin, the effects of rosuvastatin on the PK of lanabecestat, and the effects of multiple genetic polymorphisms on rosuvastatin exposure were assessed. Geometric mean ratios of the maximum observed rosuvastatin concentration (Cmax ), area under the rosuvastatin concentration-versus-time curve (AUC) from time 0 to infinity, and time of maximum observed drug concentration (tmax ) when rosuvastatin was administered alone and with lanabecestat were contained within 0.8-1.25, as were lanabecestat AUC at steady state and tmax at steady state when lanabecestat was administered alone or with rosuvastatin. Lanabecestat Cmax at steady state increased 8% in the presence of rosuvastatin. Except for an approximately 80% increase of rosuvastatin AUC (P < .05) in the heterozygotes of ABCG2 c.421C>A relative to the CC genotype, there were no statistically significant associations between rosuvastatin exposure and polymorphisms assessed. Lanabecestat + rosuvastatin was associated with few treatment-emergent adverse events, all of which resolved and were mild. Lanabecestat does not meaningfully impact BCRP activity; therefore, restriction of concomitant administration with BCRP substrates, such as rosuvastatin, may be unnecessary.

Clinically Negligible Pharmacokinetic and Pharmacodynamic Interactions Between Lanabecestat and Dabigatran Etexilate, a Prototypical P-gp Substrate.

Lanabecestat, a novel ß-site amyloid precursor protein-cleaving enzyme 1 inhibitor evaluated for Alzheimer treatment, inhibits P-glycoprotein (P-gp) activity in vitro. After oral 50-mg lanabecestat administration, gastric fluid lanabecestat concentrations exceed half-maximal inhibitory concentration (IC50 ), suggesting P-gp inhibition at the intestinal wall. Plasma drug concentrations following 50 mg lanabecestat administered once daily are <10% of IC50 , suggesting minimal systemic P-gp interaction. Dabigatran etexilate (DE) is the prodrug of dabigatran, a thrombin inhibitor and P-gp substrate, making dabigatran exposure an intestinal P-gp activity indicator. This study (NCT02568397) was conducted in 60 healthy subjects receiving a single dose of 150 mg DE alone or during a lanabecestat treatment regimen. On day 16, lanabecestat and DE were coadministered; on day 20, DE was dosed 4 hours after lanabecestat. Safety was assessed using clinical labs, electrocardiogram, vital signs, Columbia Suicide Severity Rating Scale scores, adverse events, and eye and skin examinations. Pharmacokinetic/pharmacodynamic samples were collected up to 36 hours postdose. Geometric mean plasma dabigatran area under the curve from time 0 to infinity (AUC0-∞ ) and the maximum plasma drug concentration (Cmax ) increased by 15% and 17%, respectively, when coadministered with lanabecestat. When DE was dosed 4 hours after lanabecestat, there was no effect on plasma dabigatran AUC0-∞ , Cmax , or thrombin time. DE had no effect on lanabecestat's AUC0-∞ and Cmax at steady state (day 16) versus lanabecestat alone (day 15). No clinically relevant safety concerns were observed. Lanabecestat has no clinically meaningful effect on dabigatran exposure or on P-gp activity at the intestinal wall.

Efficacy and Safety of Lanabecestat for Treatment of Early and Mild Alzheimer Disease: The AMARANTH and DAYBREAK-ALZ Randomized Clinical Trials.

Importance: Alzheimer disease (AD) is a neurodegenerative disorder characterized by cognitive deterioration and impaired activities of daily living. Current treatments provide only minor symptomatic improvements with limited benefit duration. Lanabecestat, a brain-permeable inhibitor of human beta-site amyloid precursor protein-cleaving enzyme 1 (BACE1/ß-secretase), was developed to modify the clinical course of AD by slowing disease progression. Objective: To assess whether lanabecestat slows the progression of AD compared with placebo in patients with early AD (mild cognitive impairment) and mild AD dementia. Design, Setting, and Participants: AMARANTH (first patient visit on September 30, 2014; last patient visit on October 4, 2018) and DAYBREAK-ALZ (first patient visit on July 1, 2016; last patient visit on September 28, 2018) were randomized, placebo-controlled, phase 2/3 and phase 3 clinical trials lasting 104 weeks and 78 weeks, respectively. AMARANTH and DAYBREAK-ALZ were multicenter, global, double-blind studies conducted at 257 and 251 centers, respectively, located in 15 and 18 countries or territories, respectively. A population-based sample of men and women aged 55 to 85 years who met National Institute on Aging-Alzheimer's Association criteria for early AD or mild AD dementia was screened using cognitive assessments, and the presence of amyloid was confirmed. Patients were excluded for unstable medical conditions or medication use, significant cerebrovascular pathologic findings, or a history of vitiligo and/or current evidence of postinflammatory hypopigmentation. AMARANTH screened 6871 patients; 2218 (32.3%) were randomized, and 539 patients completed the study. DAYBREAK-ALZ screened 5706 patients; 1722 (30.2%) were randomized, and 76 patients completed the study. Interventions: Patients were randomized (1:1:1) to once-daily oral doses of lanabecestat (20 mg), lanabecestat (50 mg), or placebo. Main Outcomes and Measures: The primary outcome measure was change from baseline on the 13-item Alzheimer Disease Assessment Scale-cognitive subscale. Secondary outcomes included Alzheimer's Disease Cooperative Study-Instrumental Activities of Daily Living Inventory, Clinical Dementia Rating, Functional Activities Questionnaire, Mini-Mental State Examination, and Neuropsychiatric Inventory. Efficacy analyses were conducted on the intent-to-treat population. Results: Among 2218 AMARANTH patients, the mean (SD) age was 71.3 (7.1) years, and 1177 of 2218 (53.1%) were women. Among 1722 DAYBREAK-ALZ patients, the mean (SD) age was 72.3 (7.0) years, and 1023 of 1722 (59.4%) were women. Both studies were terminated early after futility analysis. There were no consistent, reproducible dose-related findings on primary or secondary efficacy measures. Psychiatric adverse events, weight loss, and hair color changes were reported in a higher percentage of patients receiving lanabecestat than placebo. Conclusions and Relevance: Treatment with lanabecestat was well tolerated and did not slow cognitive or functional decline. Trial Registration: ClinicalTrials.gov identifiers: NCT02245737 and NCT02783573.

Pharmacokinetics and Pharmacodynamics of LY2599666, a PEG-Linked Antigen Binding Fragment that Targets Soluble Monomer Amyloid-ß.

LY2599666 is a humanized, affinity-optimized monoclonal antibody antigen-binding fragment linked to a PEG molecule and targets soluble amyloid-ß (Aß) monomers. This first-in-human dose ascending study assessed pharmacokinetics (PK) (measured as serum free LY2599666 concentration) and pharmacodynamic (PD) effects (measured as plasma total soluble Aß40 and Aß42) after a single subcutaneous (SC) dose of 10, 25, 100, and 200 mg LY2599666 in healthy subjects. As LY2599666 binds to multiple soluble Aß monomers, a two-target mediated drug disposition model (TMDD) was developed to simultaneously fit serum LY2599666 concentration and Aß monomer levels. Four Alzheimer's disease patients completed 25 mg once-weekly dosing of LY2599666 for 12 weeks. In addition, single cerebrospinal fluid samples were collected to assess penetration capability across the blood-brain barrier. PK and PD data collected from the multiple dose cohort aligned with model predictions, suggesting the established TMDD model predicted suppression of soluble Aß40 and Aß42 in plasma after SC dosing of LY2599666.

Central pharmacodynamic activity of solanezumab in mild Alzheimer's disease dementia.

INTRODUCTION: Solanezumab treatment was previously shown to significantly increase total (bound + unbound) cerebrospinal fluid (CSF) levels of amyloid ß (Aß)1-40 and Aß1-42 in patients with mild to moderate Alzheimer's disease dementia yet did not produce meaningful cognitive effects. This analysis assessed solanezumab's central nervous system target engagement by evaluating changes in CSF total and free Aß isoforms and their relationship with solanezumab exposure. METHODS: CSF Aß isoform concentrations were measured in patients with mild Alzheimer's disease dementia from a pooled EXPEDITION + EXPEDITION2 population and from EXPEDITION3. CSF solanezumab concentrations were determined from EXPEDITION3. RESULTS: Solanezumab produced statistically significant increases in CSF total Aß isoforms versus placebo, which correlated with CSF solanezumab concentration. Inconsistent effects on free Aß isoforms were observed. Solanezumab penetration into the central nervous system was low. DISCUSSION: Solanezumab administration engaged the central molecular target, and molar ratio analyses demonstrated that higher exposures may further increase CSF total Aß concentrations.

The potent BACE1 inhibitor LY2886721 elicits robust central Aß pharmacodynamic responses in mice, dogs, and humans.

BACE1 is a key protease controlling the formation of amyloid ß, a peptide hypothesized to play a significant role in the pathogenesis of Alzheimer's disease (AD). Therefore, the development of potent and selective inhibitors of BACE1 has been a focus of many drug discovery efforts in academia and industry. Herein, we report the nonclinical and early clinical development of LY2886721, a BACE1 active site inhibitor that reached phase 2 clinical trials in AD. LY2886721 has high selectivity against key off-target proteases, which efficiently translates in vitro activity into robust in vivo amyloid ß lowering in nonclinical animal models. Similar potent and persistent amyloid ß lowering was observed in plasma and lumbar CSF when single and multiple doses of LY2886721 were administered to healthy human subjects. Collectively, these data add support for BACE1 inhibition as an effective means of amyloid lowering and as an attractive target for potential disease modification therapy in AD.

Interrelationships among cortisol, 17-hydroxyprogesterone, and androstenendione exposures in the management of children with congenital adrenal hyperplasia.

UNLABELLED: Hydrocortisone is the standard replacement therapy for children with congenital adrenal hyperplasia (CAH). Relationships between cortisol exposures and pharmacodynamic responses of 17-hydroxyprogesterone and androstenedione exposures have not been systematically evaluated. OBJECTIVES: (1) Assess individual oral hydrocortisone pharmacokinetics; (2) relate the observed cortisol exposure in each subject to the observed exposures of 17-hydroxyprogesterone and androstenedione; (3) determine potential individualized treatment regimens based on each subject's pharmacokinetic and pharmacodynamic parameters. METHODS: Thirty-four patients (18 boys, 16 girls, aged 1.4 to 18.1 years) with CAH underwent 6-hour pharmacokinetic studies. Results were analyzed by noncompartmental methods to obtain the area under the curve (AUC) for cortisol, 17-hydroxyprogesterone, and androstenedione; maximum concentration and time-to-maximum concentration for cortisol; and minimum and time-to-minimum concentration for 17-hydroxyprogesterone and androstenedione. RESULTS: Mean (SD) cortisol half-life and Cmax were 1.01 (0.20) hours and 24.4 (5.4) µg/dL, respectively. The AUCs for cortisol, 17-hydroxyprogesterone and androstenedione were 40.8 (14.5) µg hour/dL, 29,490 (23,539) ng hour/dL, and 680 (795) ng hour/dL, respectively. No significant relationships existed between cortisol AUCs and the AUCs of either 17-hydroxyprogesterone (P=0.32) or androstenedione (P=0.99); nor were there differences between the change-from-baseline concentrations for cortisol with either 17-hydroxyprogesterone (P=0.80) or androstenedione (P=0.40). Cortisol simulations indicated that although four daily doses decreased 24-hour hypercortisolemia and hypocortisolemia, substantial periods of each remained. CONCLUSIONS: Concentration profiles of cortisol, 17-hydroxyprogesterone, and androstenedione are highly variable in children with CAH, and knowledge of them can assist in personalizing the therapy of CAH patients. Hydrocortisone's rapid half-life and the lack of a sustained-released product make it difficult to closely approximate normal circadian profiles.

Validation and Clinical Utility of ELISA Methods for Quantification of Amyloid-ß of Peptides in Cerebrospinal Fluid Specimens from Alzheimer's Disease Studies.

The aim of this study was to validate assays for measurement of amyloid-ß (Aß) peptides in cerebrospinal fluid (CSF)specimens according to regulatory guidance and demonstrate their utility with measurements in specimens from Alzheimer's disease (AD) studies. Methods based on INNOTEST(®)ß-AMYLOID(1-42) and prototype INNOTEST(®)ß-AMYLOID(1-40) ELISAkits were developed involving pre-analytical sample treatment with Tween-20 for reliable analyte recovery.Validation parameters were evaluated by repeated testing of CSF pools collected and stored in the same manner as clinical specimens. Intra- and interassay coefficients of variation were ≤11% and relative accuracy was within ± 10% for both analytes. Dilutional linearity was demonstrated for both analytes from a spiked CSF pool, but not from a non-spiked native CSF pool. Recovery of standard Aß peptide spikes standard ranged from 77% to 93%. No interference was observed from the investigational drugs LY2811376, LY2886721, LY3002813, or semagacestat. Aß(1-40) and Aß(1-42) were stable in CSF for up to 8 hours at room temperature and during 5 f reeze-thaw cycles from ≤−20◦C and ≤−70◦C. In frozen native CSF specimens, Aß(1-40) was mostly stable up to 3 years at ≤−70◦C, whereas stability of Aß(1-42) was limited to 221 days. Dose-dependent changes in measured CSF Aß were observed in healthy volunteers up to 36 hours after treatment with the-site cleavage enzyme inhibitor LY2886721. In conclusion, rigorous validation tests have successfully demonstrated the strengths and operational limitations of these INNOTEST(®)-based assays.They have proved to be robust and reliable tools for pharmacodynamic evaluations of investigational AD therapeutics in clinical trials.

Modeling and simulations to confirm a controlled hypoglycemic stress test in healthy subjects is not associated with clinically significant QT prolongations.

OBJECTIVES: A modified insulin tolerance test (ITT) can be used to simulate a physiological stress state through the induction of controlled hypoglycemia in healthy volunteers. This allows for evaluation of hypothalamic-pituitary-adrenocortical axis response to stress via a surge in cortical release. However, a consequence of severe, prolonged hypoglycemia is QT interval prolongation. The aim of this analysis was to confirm that blood glucose lowering to 60 mg/dL (previously identified as adequate for inducing stress) has low risk of inducing clinically significant QT prolongation. MATERIALS AND METHODS: Continuous ECG monitoring was conducted as a planned sub study of an open-label, 2-period study involving 18 healthy male subjects. The QTcF response to hypoglycemia was measured over 2 identical periods, ~ 7 days apart. RESULTS: An indirect- response model adequately described the pharmacological relationship between blood glucose and QTcF intervals over the time-course of the ITT. The model correctly identified the steep glucose-QT relationship as an on-off response with a large Hill coefficient of 59 and the threshold glucose, EC50, as ~ 57 mg/dL with narrow between-subject variability of 10%. Simulated QTcF profiles over the course of an ITT did not demonstrate any QTcF interval changes of clinical concern, defined as QTcF observation > 500 ms, if hypoglycemia did not reach below 60 mg/dL. The statistical prediction that the chance of a mean QTcF observation > 500 ms was < 0.0001. CONCLUSIONS: Results support that an ITT maintained at or above 60 mg/dL is unlikely to cause QT prolongation in healthy volunteers and does not warrant continuous ECG monitoring in this group of subjects.