Examining amyloid reduction as a surrogate endpoint through latent class analysis using clinical trial data for dominantly inherited Alzheimer's disease.

INTRODUCTION: Increasing evidence suggests that amyloid reduction could serve as a plausible surrogate endpoint for clinical and cognitive efficacy. The double-blind phase 3 DIAN-TU-001 trial tested clinical and cognitive declines with increasing doses of solanezumab or gantenerumab. METHODS: We used latent class (LC) analysis on data from the Dominantly Inherited Alzheimer Network Trials Unit 001 trial to test amyloid positron emission tomography (PET) reduction as a potential surrogate biomarker. RESULTS: LC analysis categorized participants into three classes: amyloid no change, amyloid reduction, and amyloid growth, based on longitudinal amyloid Pittsburgh compound B PET standardized uptake value ratio data. The amyloid-no-change class was at an earlier disease stage for amyloid amounts and dementia. Despite similar baseline characteristics, the amyloid-reduction class exhibited reductions in the annual decline rates compared to the amyloid-growth class across multiple biomarker, clinical, and cognitive outcomes. DISCUSSION: LC analysis indicates that amyloid reduction is associated with improved clinical outcomes and supports its use as a surrogate biomarker in clinical trials. HIGHLIGHTS: We used latent class (LC) analysis to test amyloid reduction as a surrogate biomarker. Despite similar baseline characteristics, the amyloid-reduction class exhibited remarkably better outcomes compared to the amyloid-growth class across multiple measures. LC analysis proves valuable in testing amyloid reduction as a surrogate biomarker in clinical trials lacking significant treatment effects.

Targeting amyloid ß in Alzheimer's disease: Meta-analysis of low-dose solanezumab in Alzheimer's disease with mild dementia studies.

INTRODUCTION: Solanezumab is a monoclonal antibody that binds to the mid-domain of soluble amyloid ß peptide. This meta-analysis evaluated the effect of low-dose solanezumab on clinical progression in three phase 3 studies. METHODS: The population comprised patients aged ≥55 years with Alzheimer's disease (AD) with mild dementia, randomized to 400 mg solanezumab or placebo every 4 weeks for 80 weeks. Frequentist mixed-model repeated-measures (MMRM) and Bayesian disease progression model (DPM) longitudinal analyses were conducted. RESULTS: Pooled MMRM analyses showed a statistically significant effect of solanezumab across cognitive and functional outcome measures. DPM results were generally consistent with MMRM results, ranging from 15% to 30% slowing of clinical progression. DISCUSSION: These analyses suggest low-dose solanezumab slows clinical progression of AD with mild dementia. The ongoing A4 solanezumab study in participants with preclinical AD will ascertain the effect of a higher dose of solanezumab in an earlier disease stage. HIGHLIGHTS: Individual EXPEDITION studies were negative but suggest low-dose solanezumab had an effect in slowing the clinical progression of Alzheimer's disease (AD) with mild dementia. At 80 weeks, mixed-model repeated-measures analyses showed numeric reductions in measures of clinical decline in solanezumab-treated arms compared with placebo across almost every outcome measure, and statistical significance in multiple outcome measures in each study. Pooled analyses suggest a high probability that low-dose solanezumab has at least some effect on slowing the clinical progression of AD with mild dementia. Across cognitive and functional outcome measures, estimates from disease progression model analyses range from 15% to 30% slowing of decline with low-dose solanezumab in AD with mild dementia.

Systematic in silico analysis of clinically tested drugs for reducing amyloid-beta plaque accumulation in Alzheimer's disease.

INTRODUCTION: Despite strong evidence linking amyloid beta (Aß) to Alzheimer's disease, most clinical trials have shown no clinical efficacy for reasons that remain unclear. To understand why, we developed a quantitative systems pharmacology (QSP) model for seven therapeutics: aducanumab, crenezumab, solanezumab, bapineuzumab, elenbecestat, verubecestat, and semagacestat. METHODS: Ordinary differential equations were used to model the production, transport, and aggregation of Aß; pharmacology of the drugs; and their impact on plaque. RESULTS: The calibrated model predicts that endogenous plaque turnover is slow, with an estimated half-life of 2.75 years. This is likely why beta-secretase inhibitors have a smaller effect on plaque reduction. Of the mechanisms tested, the model predicts binding to plaque and inducing antibody-dependent cellular phagocytosis is the best approach for plaque reduction. DISCUSSION: A QSP model can provide novel insights to clinical results. Our model explains the results of clinical trials and provides guidance for future therapeutic development.

Anti-amyloid-ß protein agents for the treatment of Alzheimer's disease: an update on emerging drugs.

INTRODUCTION: Currently available Alzheimer's disease (AD) therapeutics are only symptomatic, targeting cholinergic and glutamatergic neurotransmissions. Several putative disease-modifying drugs in late-stage clinical development target amyloid-ß (Aß) peptide and tau protein, the principal neurophatological hallmarks of the disease. AREAS COVERED: Phase III randomized clinical trials of anti-Aß drugs for AD treatment were searched in US and EU clinical trial registries and principal biomedical databases until May 2020. EXPERT OPINION: At present, compounds in Phase III clinical development for AD include four  anti-Ab monoclonal antibodies (solanezumab, gantenerumab, aducanumab, BAN2401), the combination of cromolyn sodium and ibuprofen (ALZT-OP1), and two small molecules (levetiracetam, GV-971). These drugs are mainly being tested in subjects during early AD phases or at preclinical stage of familial AD or even in asymptomatic subjects at high risk of developing AD. The actual results support the hypothesis that elevated Aß represents an early stage in the AD continuum and demonstrate the feasibility of enrolling these high-risk participants in secondary prevention trials to slow cognitive decline during the AD preclinical stages. However, a series of clinical failures may question further development of Aß-targeting drugs and the findings from current ongoing Phase III trials will hopefully give light to this critical issue.

Lessons Learnt from the Second Generation of Anti-Amyloid Monoclonal Antibodies Clinical Trials.

BACKGROUND: Alzheimer disease (AD) is a chronic neurodegenerative disorder with complex pathophysiology that affects over 50 million people worldwide. Most drug therapies, to date, have focused on targeting the amyloid-beta (Aß) pathway, but clinical outcomes of anti-Aß antibodies have been unsuccessful and unable to meet their primary endpoints. Similar trends have also been observed in treatments that target the tau pathway. SUMMARY: This paper reviews recent anti-Aß passive monotherapies, since Bapineuzumab, that have progressed to phase 3 clinical trials. Specifically, we discuss the 4 clinical trial programs of Solanezumab (targets Aß monomers), Aducanumab (targets Aß oligomers and plaques), Crenezumab (targets Aß oligomers), and Gantenerumab (targets Aß fibrils) which are all exogenous monoclonal antibodies. We conclude with potential reasons for why they have not met their primary endpoints and discuss lessons learnt from these trials. Key Message: Future disease-modifying trials (DMTs) for AD should be conducted in asymptomatic, Aß-positive individuals. Moreover, potential additive and/or synergistic benefits focusing on anti-Aß and anti-tau drug combinations merit further investigation.

Late-Stage Failures of Monoclonal Antibody Drugs: A Retrospective Case Study Analysis.

AIM: To analyze the late-stage failures of monoclonal antibody drugs. The later a drug fails in development, the more time and expense is incurred by the sponsor. METHODS: We review the late stage, Phase III, failures of 21 monoclonal antibody drugs between 2014 and 2019 using published and publicly available information to characterize the reasons for these failures. RESULTS: In some cases, the failures are unavoidable due to the lack of adequate science, but in others, we characterize the causes of such failures and recommend how such failures may have been avoided. CONCLUSION: By learning from previous mistakes and adhering to the principles and recommendations provided, it is possible to avoid these common pitfalls, increasing the likelihood of success in phase III clinical trials, and thus securing regulatory approval.

Use of white matter reference regions for detection of change in florbetapir positron emission tomography from completed phase 3 solanezumab trials.

INTRODUCTION: We compared subject-specific white matter (SSWM) and whole cerebellum (CBL) reference regions for power to detect longitudinal change in amyloid positron emission tomography signal. METHODS: Positive florbetapir positron emission tomography scans were analyzed from participants (66 placebo treated and 63 solanezumab treated) with mild dementia caused by Alzheimer's disease from the EXPEDITION and EXPEDITION2 studies. For comparison to CBL, a second normalization was performed on longitudinal data using an SSWM correction factor (SSWM normalization ratio [SSWMnr]). Analysis of covariance assessed baseline to 18-month change between treatment with solanezumab and placebo. Sample and effect size estimations provided magnitude of observed treatment changes. RESULTS: Longitudinal percent change between placebo and solanezumab using CBL was not significant (P = .536) but was significant for SSWMnr (P = .042). Compared with CBL, SSWMnr technique increased the power to detect a treatment difference, more than tripling the effect size and reducing the sample size requirements by 85% to 90%. DISCUSSION: Adjusting longitudinal standardized uptake value ratios with an SSWM reference region in these antiamyloid treatment trials increased mean change detection and decreased variance resulting in the substantial improvement in statistical power to detect change.

Emerging drugs to reduce abnormal ß-amyloid protein in Alzheimer's disease patients.

INTRODUCTION: Currently available drugs against Alzheimer's disease (AD) target cholinergic and glutamatergic neurotransmissions without affecting the underlying disease process. Putative disease-modifying drugs are in development and target ß-amyloid (Aß) peptide and tau protein, the principal neurophatological hallmarks of the disease. Areas covered: Phase III clinical studies of emerging anti-Aß drugs for the treatment of AD were searched in US and EU clinical trial registries and in the medical literature until May 2016. Expert opinion: Drugs in Phase III clinical development for AD include one inhibitor of the ß-secretase cleaving enzyme (BACE) (verubecestat), three anti-Aß monoclonal antibodies (solanezumab, gantenerumab, and aducanumab), an inhibitor of receptor for advanced glycation end products (RAGE) (azeliragon) and the combination of cromolyn sodium and ibuprofen (ALZT-OP1). These drugs are mainly being tested in subjects during early phases of AD or in subjects at preclinical stage of familial AD or even in asymptomatic subjects at high risk of developing AD. The hope is to intervene in the disease process when it is not too late. However, previous clinical failures with anti-Aß drugs and the lack of fully understanding of the pathophysiological role of Aß in the development of AD, put the new drugs at substantial risk of failure.

Phase 3 solanezumab trials: Secondary outcomes in mild Alzheimer's disease patients.

INTRODUCTION: EXPEDITION and EXPEDITION2 were identically designed placebo-controlled phase 3 studies assessing effects of solanezumab, an antiamyloid monoclonal antibody binding soluble amyloid-ß peptide, on cognitive and functional decline over 80 weeks in patients with mild-to-moderate Alzheimer's disease (AD). Primary findings for both studies have been published. METHODS: Secondary analyses of efficacy, biomarker, and safety endpoints in the pooled (EXPEDTION + EXPEDITION2) mild AD population were performed. RESULTS: In the mild AD population, less cognitive and functional decline was observed with solanezumab (n = 659) versus placebo (n = 663), measured by Alzheimer's Disease Assessment Scale Cognitive subscale, Mini-Mental State Examination, and Alzheimer's Disease Cooperative Study-Activities of Daily Living functional scale Instrumental ADLs. Baseline-to-endpoint changes did not differ between treatment groups for Alzheimer's Disease Cooperative Study-Activities of Daily Living functional scale, basic items of the ADCS-ADL, and Clinical Dementia Rating Sum of Boxes. Plasma/cerebrospinal fluid biomarker findings indicated target engagement by solanezumab. Solanezumab demonstrated acceptable safety. Efficacy findings for the moderate AD population are also provided. DISCUSSION: These findings describe solanezumab effects on efficacy/safety measures in a mild AD population. Another phase 3 study, EXPEDITION3, will investigate solanezumab's effects in a mild AD population.

Lessons learned from the failure of solanezumab as a prospective treatment strategy for Alzheimer's disease.

INTRODUCTION: In the last decade, the efforts conducted for discovering Alzheimer's Disease (AD) treatments targeting the best-known pathogenic factors [amyloid-ß (Aß), tau protein, and neuroinflammation] were mostly unsuccessful. Given that a systemic failure of Aß clearance was supposed to primarily contribute to AD development and progression, disease-modifying therapies with anti-Aß monoclonal antibodies (e.g. solanezumab, bapineuzumab, gantenerumab, aducanumab, lecanemab and donanemab) are ongoing in randomized clinical trials (RCTs) with contrasting results. AREAS COVERED: The present Drug Discovery Case History analyzes the failures of RCTs of solanezumab on AD. Furthermore, the authors review the pharmacokinetics, pharmacodynamics, and tolerability effect of solanezumab from preclinical studies with its analogous m266 in mice. Finally, they describe the RCTs with cognitive, cerebrospinal fluid and neuroimaging findings in mild-to-moderate AD (EXPEDITION studies) and in secondary prevention studies (A4 and DIAN-TU). EXPERT OPINION: Solanezumab was one of the first anti-Aß monoclonal antibodies to be tested in preclinical and clinical AD showing to reduce brain Aß level by acting on soluble monomeric form of Aß peptide without significant results on deposits. Unfortunately, this compound showed to accelerate cognitive decline in both asymptomatic and symptomatic trial participants, and this failure of solanezumab further questioned the Aß cascade hypothesis of AD.

Change in Digital Cognitive Test Performance between Solanezumab and Placebo Groups in Preclinical Alzheimer's Disease: Secondary Analyses from the A4 Study.

BACKGROUND: Primary results from the Anti-Amyloid in Asymptomatic Alzheimer's disease Study (A4) suggested no benefit of solanezumab on its primary cognitive outcome, a composite of paper and pencil tests (the Preclinical Alzheimer's Cognitive Composite; PACC). OBJECTIVE: To determine whether change in cognitive performance, assessed using the Computerized Cognitive Composite (C3) summary score and C3 individual tests, differed between treatment groups over 240 weeks, differed based on baseline Aß burden, and tracked with PACC decline. DESIGN: Longitudinal analysis of cognitive change over 240 weeks on the C3 Summary Score and C3 individual tests between participants randomly assigned to solanezumab at a dose of up to 1600 mg intravenously every 4 weeks versus placebo. SETTING: The A4 study took place at 67 sites in Australia, Canada, Japan and the United States. PARTICIPANTS: Cognitively unimpaired older adults (n=1117, Mean Age=71.9, 60.7% female) with elevated brain amyloid levels on 18F-florbetapir positron-emission tomography (PET) at baseline (n=549 in the solanezumab group; n=568 in the placebo group). MEASUREMENTS: Participants completed the C3 battery and PACC every 6 months. The C3 Summary Score combines the Cogstate Brief Battery (CBB)-One Card Learning, the Behavioral Pattern Separation (BPS) Test- Object- Lure Discrimination Index, and the Face Name Associative Memory Exam (FNAME)- Face-Name Matching. RESULTS: Change on the C3 Summary Score was moderately correlated with change on the PACC (Spearman's corr=0.53, 95% CI: 0.49 to 0.57; p<0.001). At 240 weeks, mean change in the C3 Summary Score did not differ between groups; +0.24 in the solanezumab group and +0.27 in the placebo group (mean difference= -0.02; 95% CI: -0.13 to 0.08; p = 0.650). Lack of a treatment effect was similarly observed across most individual C3 tests. Performance on the C3 tests were influenced by level of amyloid burden, where higher levels were associated with worse performance. CONCLUSION: This study provides corroborating evidence that solanezumab does not slow cognitive decline in preclinical AD as exhibited with a computerized cognitive assessment with some evidence that solanezumab may exacerbate cognition on select digital outcomes. This study also provides important information that amyloid related cognitive change manifests differently on individual C3 tests.

More failure with solanezumab - this time in preclinical Alzheimer's disease.

INTRODUCTION: There is no cure for Alzheimer's disease, which is the sixth leading cause of death in the USA. Lecanemab is anti-Aß monoclonal antibody approved for the treatment of early Alzheimer's disease but is only marginally effective. Other antibodies are being developed including solanezumab. AREAS COVERED: A phase 3 clinical trial of solanezumab in preclinical Alzheimer's disease. In the A4 study, solanezumab did not reduce the decline in cognition or function and had no effect on brain amyloid burden. EXPERT OPINION: After the poor results in the EXPEDITION series of trials, the development of solanezumab should have been terminated. The rationale for undertaking the A4 trial was questionable, and the lack of benefit was probable. The controversial approval of two anti-Aß monoclonal antibodies (aducanumab and lecanemab) for the treatment of Alzheimer's disease by the US Food and Drug Administration (FDA), despite a high incidence of amyloid-related imagining abnormalities (ARIA), may be fueling this continuation of clinical development of agents such as solanezumab. The lesson from the A4 trial is that more careful/realistic consideration needs to be given before embarking on further phase 3 trials with anti-Aß monoclonal antibodies.

Magnetic resonance imaging measures of brain volumes across the EXPEDITION trials in mild and moderate Alzheimer's disease dementia.

Introduction: Solanezumab is a monoclonal antibody that preferentially binds soluble amyloid beta and promotes its clearance from the brain. The aim of this post hoc analysis was to assess the effect of low-dose solanezumab (400 mg) on global brain volume measures in patients with mild or moderate Alzheimer's disease (AD) dementia quantified using volumetric magnetic resonance imaging (vMRI) data from the EXPEDITION clinical trial program. Methods: Patients with mild or moderate AD (EXPEDITION and EXPEDITION2) and mild AD (EXPEDITION3), were treated with either placebo or solanezumab (400 mg) every 4 weeks (Q4W) for 76 weeks. vMRI scans were acquired at baseline and at 80 weeks from 427 MRI facilities using a standardized imaging protocol. Whole brain volume (WBV) and ventricle volume (VV) changes were estimated at 80 weeks using either boundary shift integral (EXPEDITION and EXPEDITION2) or tensor-based morphometry (EXPEDITION3). Results: The pooled cohort used for this study consisted of participants with vMRI at baseline and week 80 across the three trials. Analyzed patient subgroups comprised full patient cohort (N = 2933), apolipoprotein E (APOE) ε4+ carriers (N = 1835), and patients with mild (N = 2497) or moderate AD dementia (N = 428). No significant effect (all P-values ≥.05) of treatment was observed in the pooled sample, individual trials, or subgroups of patients with mild or moderate AD or APOE ε4 carriers, in either WBV or VV change. Discussion: Analysis of patients with mild or moderate AD dementia from baseline to 80 weeks using vMRI measures of WBV and VV changes suggested that low-dose solanezumab was not linked to changes in volumes at 80 weeks. Analysis of the pooled cohort did not demonstrate an effect on brain volumes with treatment. Evaluation of a higher dose of solanezumab in the preclinical stage of AD is currently being undertaken.

ALZT-OP1: an experimental combination regimen for the treatment of Alzheimer's disease.

INTRODUCTION: For Alzheimer's disease (AD) treatment, US FDA granted accelerated approval for aducanumab due to its amyloid-ß (Aß)-lowering effects, notwithstanding the reported poor correlation between amyloid plaque reduction and clinical change for this drug. The diversification of drug targets appears to be the future of the AD field and from this perspective, drugs modulating microglia dysfunction and combination treatment regimens offer some promise. AREAS COVERED: The aim of the present article was to provide a comprehensive review of ALZT-OP1 (cromolyn sodium plus ibuprofen), an experimental combination treatment regimen for AD, discussing their mechanisms of action targeting Aß and neuroinflammation, examining the role of microglia in AD and offering our own insights on the role of present and alternative approaches directed toward neuroinflammation. EXPERT OPINION: Enrolling high-risk participants with elevated brain amyloid could help to slow cognitive decline in secondary prevention trials during AD preclinical stages. Long-term follow-up indicated that non-steroidal anti-inflammatory drugs use begun when the brain was still normal may benefit these patients, suggesting that the timing of therapy could be crucial. However, previous clinical failures and the present incomplete understanding of the Aß pathophysiological role in AD put this novel experimental combination regimen at substantial risk of failure.

Evaluation of dose-dependent treatment effects after mid-trial dose escalation in biomarker, clinical, and cognitive outcomes for gantenerumab or solanezumab in dominantly inherited Alzheimer's disease.

Introduction: While the Dominantly Inherited Alzheimer Network Trials Unit (DIAN-TU) was ongoing, external data suggested higher doses were needed to achieve targeted effects; therefore, doses of gantenerumab were increased 5-fold, and solanezumab was increased 4-fold. We evaluated to what extent mid-trial dose increases produced a dose-dependent treatment effect. Methods: Using generalized linear mixed effects (LME) models, we estimated the annual low- and high-dose treatment effects in clinical, cognitive, and biomarker outcomes. Results: Both gantenerumab and solanezumab demonstrated dose-dependent treatment effects (significant for gantenerumab, non-significant for solanezumab) in their respective target amyloid biomarkers (Pittsburgh compound B positron emission tomography standardized uptake value ratio and cerebrospinal fluid amyloid beta 42), with gantenerumab demonstrating additional treatment effects in some downstream biomarkers. No dose-dependent treatment effects were observed in clinical or cognitive outcomes. Conclusions: Mid-trial dose escalation can be implemented as a remedy for an insufficient initial dose and can be more cost effective and less burdensome to participants than starting a new trial with higher doses, especially in rare diseases. Highlights: We evaluated the dose-dependent treatment effect of two different amyloid-specific immunotherapies.Dose-dependent treatment effects were observed in some biomarkers.No dose-dependent treatment effects were observed in clinical/cognitive outcomes, potentially due to the fact that the modified study may not have been powered to detect such treatment effects in symptomatic subjects at a mild stage of disease exposed to high (or maximal) doses of medication for prolonged durations.

Structure and Function of Alzheimer's Amyloid ßeta Proteins from Monomer to Fibrils: A Mini Review.

Alzheimer's disease is the most common form of dementia, that affects millions of people worldwide. According to the widely accepted amyloid cascade hypothesis, misfolding and aggregation of Aß peptides is the principal cause of Alzheimer's disease. In the present mini-review, we have discussed the different structures of Aß protein from monomer to fibrils and their arrangement in different symmetries. We have highlighted the critical amino acid residue that plays a crucial role in the early stage misfolding of Aß monomers, Aß fibrils arrangement in different symmetries, the elongation process and Aß protein interaction with the membrane. We have further discussed the antibodies that are currently in clinical trial phase III for Alzheimer's disease.

Magnetic resonance imaging measures of brain atrophy from the EXPEDITION3 trial in mild Alzheimer's disease.

INTRODUCTION: Solanezumab is a humanized monoclonal antibody that preferentially binds to soluble amyloid ß and promotes its clearance from the brain in preclinical studies. The objective of this study was to assess the effect of solanezumab in slowing global and anatomically localized brain atrophy as measured by volumetric magnetic resonance imaging (MRI). METHODS: In the EXPEDITION3 phase 3 trial, participants with mild Alzheimer's disease were randomized to receive intravenous infusions of either 400 mg of solanezumab or placebo every 4 weeks for 76 weeks. Volumetric MRI scans were acquired at baseline and at 80 weeks from 275 MRI facilities using a standardized imaging protocol. A subset of 1462 patients who completed both MRI and 14-item Alzheimer's Disease Assessment Scale-Cognitive Subscale assessments at both time points were selected for analysis. Longitudinal MRI volume changes were analyzed centrally by tensor-based morphometry with a standard FreeSurfer brain parcellation. Prespecified volumetric measures, including whole brain and ventricles, along with anatomically localized regions in the temporal, parietal, and frontal lobes were evaluated in those participants. RESULTS: Group-mean differences in brain atrophy rates were directionally consistent across a number of brain regions but small in magnitude (1.3-6.9% slowing) and not statistically significant when corrected for multiple comparisons. The annualized rates of change of the volumetric measures and the correlation of these changes with cognitive changes in placebo-treated subjects were similar to those reported previously. DISCUSSION: In the EXPEDITION3 trial, solanezumab did not significantly slow down rates of global or anatomically localized brain atrophy. Brain volume changes and their relationship to cognition were consistent with previous reports.

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.

Molecular Docking and Dynamic Simulation of AZD3293 and Solanezumab Effects Against BACE1 to Treat Alzheimer's Disease.

The design of novel inhibitors to target BACE1 with reduced cytotoxicity effects is a promising approach to treat Alzheimer's disease (AD). Multiple clinical drugs and antibodies such as AZD3293 and Solanezumab are being tested to investigate their therapeutical potential against AD. The current study explores the binding pattern of AZD3293 and Solanezumab against their target proteins such as ß-secretase (BACE1) and mid-region amyloid-beta (Aß) (PDBIDs: 2ZHV & 4XXD), respectively using molecular docking and dynamic simulation (MD) approaches. The molecular docking results show that AZD3293 binds within the active region of BACE1 by forming hydrogen bonds against Asp32 and Lys107 with distances 2.95 and 2.68 Å, respectively. However, the heavy chain of Solanezumab interacts with Lys16 and Asp23 of amyloid beta having bond length 2.82, 2.78, and 3.00 Å, respectively. The dynamic cross correlations and normal mode analyses show that BACE1 depicted good residual correlated motions and fluctuations, as compared to Solanezumab. Using MD, the Root Mean Square Deviation and Fluctuation (RMSD/F) graphs show that AZD3293 residual fluctuations and RMSD value (0.2 nm) was much better compared to Solanezumab (0.7 nm). Moreover, the radius of gyration (Rg) results also depicts the significance of AZD3293 docked complex compared to Solanezumab through residual compactness. Our comparative results show that AZD3293 is a better therapeutic agent for treating AD than Solanezumab.

Grasping at straws: the failure of solanezumab to modify mild Alzheimer's disease.

INTRODUCTION: The amyloid-beta (Aß) cascade hypothesis is that reducing Aß levels in the brain will be beneficial in the treatment of Alzheimer's disease. Solanezumab is a humanized analog of a murine antibody that selectively targets the central domain of the soluble form of Aß. In the EXPEDITION 1 and 2 Phase 3 clinical trials, solanezumab was shown to be ineffective in subjects with mild-to-moderate Alzheimer's disease, and to have no effect on brain Aß burden. Areas covered: This evaluation considers the secondary analysis of (EXPEDITION 1 and 2), which led to the EXPEDITION 3 trial of solanezumab in subjects with mild Alzheimer's disease, and the results of EXPEDITION 3. Expert opinion: The secondary analysis of EXPEDITION 1 and 2 was limited to mild Alzheimer's disease, and showed improvements on some scales, but not others. This analysis did not report data on Aß burden. In my opinion, this was a questionable basis to undertake a further phase trial with solanezumab. The EXPEDITION 3 trial of solanezumab in subjects with mild Alzheimer's disease was terminated early for ineffectiveness. With hindsight, solanezumab should have been discontinued after EXPEDITION 1 and 2, especially as it had not been shown to reduce Aß burden.