Representativeness of Participants Eligible to Be Enrolled in Clinical Trials of Aducanumab for Alzheimer Disease Compared With Medicare Beneficiaries With Alzheimer Disease and Mild Cognitive Impairment

Perceptions about dementia clinical trials among underrepresented populations: a nationally representative survey of U.S. dementia caregivers

BACKGROUND

The research community has historically failed to enroll diverse groups of participants in dementia clinical trials. A unique aspect of dementia care research is the requirement of a study partner, who can attest to the care recipient's clinical and functional capacity. The aim of this study is to assess racial and ethnic differences and the importance of various trial considerations among dementia caregivers, in their decision to participate in clinical research as study partners.

METHOD

We embedded a vignette about a hypothetical dementia clinical trial in a nationally representative survey of U.S. dementia caregivers, oversampling non-Hispanic Black and Hispanic caregivers. Dementia caregivers were asked about their willingness to participate in the trial with their care recipient and rated the importance of nine considerations in hypothetical decisions to participate. Caregiver demographic characteristics were analyzed as predictors of trial participation in a base demographic model. In a second reasons model caregiver demographic characteristics and the rated importance of the nine considerations were separately analyzed as predictors; both models used survey-weighted logistic regression.

RESULT

The sample consisted of 610 dementia caregivers, including 156 non-Hispanic Black and 122 Hispanic caregiver participants. In the base demographic model, hypothetical trial participation was negatively associated with older caregiver age (OR (odds ratio) = 0.72, p = < 0.001). In the reasons model, the rated importance of a social responsibility to help others by participating in research was significantly associated with participation (OR = 1.56, p = 0.049), while the importance of the possibility of the care recipient experiencing serious side effects was negatively associated with participation (OR = 0.51, p = 0.003). In both models there was no significant difference in hypothetical participation between non-Hispanic Black and non-Hispanic White caregivers, or between Hispanic and non-Hispanic White caregivers.

CONCLUSION

Hispanic and non-Hispanic Black dementia caregivers were not less likely than non-Hispanic White dementia caregivers to participate in a hypothetical dementia clinical trial. Our study suggests that failures to recruit diverse populations in dementia clinical research are not attributable to less willingness among members of underrepresented groups but may instead reflect structural barriers and historic exclusion from trial participation.

Investigating patient eligibility for anti-amyloid monoclonal antibody treatment of Alzheimer's disease: real-world data from an Austrian psychiatric memory clinic population

BACKGROUND

Pharmacological treatment options for patients with dementia owing to Alzheimer's disease are limited to symptomatic therapy. Recently, the US Food and Drug Administration approved the monoclonal antibody lecanemab for the treatment of amyloid-positive patients with mild cognitive impairment (MCI) and early Alzheimer´s dementia. European approval is expected in 2024. Data on the applicability and eligibility for treatment with anti-amyloid monoclonal antibodies outside of a study population are lacking.

AIMS

This study examined eligibility criteria for lecanemab in a real-world memory clinic population between 1 January 2022 and 31 July 2023.

METHOD

We conducted a retrospective, single-centre study applying the clinical trial eligibility criteria for lecanemab to out-patients of a specialised psychiatric memory clinic. Eligibility for anti-amyloid treatment was assessed following the phase 3 inclusion and exclusion criteria and the published recommendations for lecanemab.

RESULTS

The study population consisted of 587 out-patients. Two-thirds were diagnosed with Alzheimer's disease (probable or possible Alzheimer's disease dementia in 43.6% of cases, n = 256) or MCI (23%, n = 135), and 33.4% (n = 196) were diagnosed with dementia or neurocognitive disorder owing to another aetiology. Applying all lecanemab eligibility criteria, 11 (4.3%) patients with dementia and two (1.5%) patients with MCI would have been eligible for treatment with this compound, whereas 13 dementia (5.1%) and 14 (10.4%) MCI patients met clinical inclusion criteria, but had no available amyloid status.

CONCLUSIONS

Even in a memory clinic with a good infrastructure and sufficient facilities for dementia diagnostics, most patients do not meet the eligibility criteria for treatment with lecanemab.

Monoclonal antibodies and aptamers: The future therapeutics for Alzheimer's disease

Alzheimer's disease (AD) is considered the most common and prevalent form of dementia of adult-onset with characteristic progressive impairment in cognition and memory. The cure for AD has not been found yet and the treatments available until recently were only symptomatic. Regardless of multidisciplinary approaches and efforts made by pharmaceutical companies, it was only in the past two years that new drugs were approved for the treatment of the disease. Amyloid beta (Aβ) immunotherapy is at the core of this therapy, which is one of the most innovative approaches looking to change the course of AD. This technology is based on synthetic peptides or monoclonal antibodies (mAb) to reduce Aβ levels in the brain and slow down the advance of neurodegeneration. Hence, this article reviews the state of the art about AD neuropathogenesis, the traditional pharmacologic treatment, as well as the modern active and passive immunization describing approved drugs, and drug prototypes currently under investigation in different clinical trials. In addition, future perspectives on immunotherapeutic strategies for AD and the rise of the aptamer technology as a non-immunogenic alternative to curb the disease progression are discussed.

Perceptions about dementia clinical trials among underrepresented populations: A nationally representative survey of U.S. dementia caregivers

Background

The research community has historically failed to enroll diverse groups of participants in dementia clinical trials. A unique aspect of dementia care research is the requirement of a study partner, who can attest to the care recipient's clinical and functional capacity. The aim of this study is to assess racial and ethnic differences and the importance of various trial considerations among dementia caregivers, in their decision to participate in clinical research as study partners.

Method

We embedded a vignette about a hypothetical dementia clinical trial in a nationally representative survey of U.S. dementia caregivers, oversampling non-Hispanic Black and Hispanic caregivers. Dementia caregivers were asked about their willingness to participate in the trial with their care recipient and rated the importance of nine considerations in hypothetical decisions to participate. Caregiver demographic characteristics were analyzed as predictors of trial participation in a base demographic model. In a second reasons model caregiver demographic characteristics and the rated importance of the nine considerations were separately analyzed as predictors; both models used survey-weighted logistic regression.

Result

The sample consisted of 610 dementia caregivers, including 156 non-Hispanic Black and 122 Hispanic caregiver participants. In the base demographic model, hypothetical trial participation was negatively associated with older caregiver age (OR (odds ratio) = 0.72, p = < 0.001). In the reasons model, the rated importance of a social responsibility to help others by participating in research was significantly associated with participation (OR = 1.56, p = 0.049), while the importance of the possibility of the care recipient experiencing serious side effects was negatively associated with participation (OR = 0.51, p = 0.003). In both models there was no significant difference in hypothetical participation between non-Hispanic Black and non-Hispanic White caregivers, or between Hispanic and non-Hispanic White caregivers.

Conclusion

Hispanic and non-Hispanic Black dementia caregivers were not less likely than non-Hispanic White dementia caregivers to participate in a hypothetical dementia clinical trial. Our study suggests that failures to recruit diverse populations in dementia clinical research are not attributable to less willingness among members of underrepresented groups but may instead reflect structural barriers and historic exclusion from trial participation.

What Are the Reliable Plasma Biomarkers for Mild Cognitive Impairment? A Clinical 4D Proteomics Study and Validation

Objective

At present, Alzheimer's disease (AD) lacks effective treatment means, and early diagnosis and intervention are the keys to treatment. Therefore, for mild cognitive impairment (MCI) and AD patients, blood sample analysis using the 4D nonstandard (label-free) proteomic in-depth quantitative analysis, looking for specific protein marker expression differences, is important. These marker levels change as AD progresses, and the analysis of these biomarkers changes with this method, which has the potential to show the degree of disease progression and can be used for the diagnosis and preventive treatment of MCI and AD.

Materials and Methods

Patients were recruited according to the inclusion and exclusion criteria and divided into three groups according to scale scores. Elderly patients diagnosed with AD were selected as the AD group (n = 9). Patients diagnosed with MCI were classified into the MCI group (n = 10). Cognitively healthy elderly patients were included in the normal cognition control group (n = 10). Patients' blood samples were used for 4D label-free proteomic in-depth quantitative analysis to identify potential blood biomarkers. The sample size of each group was expanded (n = 30), and the selected biomarkers were verified by enzyme-linked immunosorbent assay (ELISA) to verify the accuracy of the proteomic prediction.

Results

Six specific blood markers, namely, APOE, MMP9, UBR5, PLA2G7, STAT5B, and S100A8, were detected by 4D label-free proteomic quantitative analysis. These markers showed a statistically significant upregulation trend in the MCI and AD groups compared with the normal cognition control group (P < 0.05). ELISA results showed that the levels of these six proteins in the MCI group were significantly higher than those in the normal cognition control group, and the levels of these six proteins in the AD group were significantly higher than those in the MCI group (P < 0.05).

Conclusion

The plasma levels of APOE, MMP9, UBR5, PLA2G7, STAT5B, and S100A8 in cognitively healthy elderly patients and patients with MCI and AD were significantly different and, more importantly, showed a trend of increasing expression. These results indicate that these six human plasma markers have important diagnostic and therapeutic potential in the identification of cognitive impairment and have value for in-depth research and clinical application.

Incidence and Prevalence of Dementia: A 2015-2020 Population-Based Study in the Campania Region of Italy

OBJECTIVE

The aims of this study were to provide population-based estimates of prevalence and incidence of any dementia and Alzheimer's dementia (AD) in the Campania region (South Italy) and to validate towards a clinical registry.

METHODS

This was a population-based study, using routinely collected healthcare data of individuals living in the Campania region (South Italy) from 2015 to 2020. We included individuals aged ≥65 years alive at the prevalence day (January 1, 2021) who had at least one administrative record for dementia and/or AD from 2015 to 2020. Age-and sex-standardised prevalence rates were calculated using direct standardisation method (European population in 2020 as the reference population). To estimate the incidence, we tested three possible algorithms, which differed for the duration of the time interval between study baseline (January 1, 2015) and index date (first record for dementia and/or AD in administrative databases). We employed a clinical database for the validation of our algorithms towards neuropsychological test results.

RESULTS

Among individuals aged over 65 years, 80,392 had dementia, of which 35,748 had AD. The age- and sex-standardised prevalence rates per 1,000 individuals for any dementia and AD were 77.64 (95% confidence interval [CI] = 77.57; 77.68) and 34.05 (95% CI = 34.01; 34.09), respectively. There were 82.10 incident cases of any dementia per 100,000 per year (0.79 sensitivity and 0.62 specificity) and 59.89 incident cases of AD per 100,000 per year (0.80 sensitivity and 0.59 specificity). The capture-recapture method showed a very low number of undetected cases (1.7% for any dementia and 3.0% for AD). Our algorithms showed acceptable performance with the area under the curve ranging from 0.59 to 0.72 and a double likelihood ratio of correctly identifying individuals above and below mini-mental status examination (MMSE) standard cut-offs (24 and 26).

CONCLUSIONS

Prevalence and incidence of any dementia and AD in the Campania region (South Italy) from 2015 to 2020 are in line with previous estimates from other countries. Our algorithm, integrating administrative and clinical data, holds potential for assessing dementia's epidemiological burden, identifying risk factors, planning healthcare access, and developing prevention strategies.

New directions for Alzheimer's disease research from the Jackson Laboratory Center for Alzheimer's and Dementia Research 2022 workshop

INTRODUCTION

In September 2022, The Jackson Laboratory Center for Alzheimer's and Dementia Research (JAX CADR) hosted a workshop with leading researchers in the Alzheimer's disease and related dementias (ADRD) field.

METHODS

During the workshop, the participants brainstormed new directions to overcome current barriers to providing patients with effective ADRD therapeutics. The participants outlined specific areas of focus. Following the workshop, each group used standard literature search methods to provide background for each topic.

RESULTS

The team of invited experts identified four key areas that can be collectively addressed to make a significant impact in the field: (1) Prioritize the diversification of disease targets, (2) enhance factors promoting resilience, (3) de-risk clinical pipeline, and (4) centralize data management.

DISCUSSION

In this report, we review these four objectives and propose innovations to expedite ADRD therapeutic pipelines.

Cross-Regional Data Initiative for the Assessment and Development of Treatment for Neurological and Mental Disorders

Purpose

To describe and categorize detailed components of databases in the Neurological and Mental Health Global Epidemiology Network (NeuroGEN).

Methods

An online 132-item questionnaire was sent to key researchers and data custodians of NeuroGEN in North America, Europe, Asia and Oceania. From the responses, we assessed data characteristics including population coverage, data follow-up, clinical information, validity of diagnoses, medication use and data latency. We also evaluated the possibility of conversion into a common data model (CDM) to implement a federated network approach. Moreover, we used radar charts to visualize the data capacity assessments, based on different perspectives.

Results

The results indicated that the 15 databases covered approximately 320 million individuals, included in 7 nationwide claims databases from Australia, Finland, South Korea, Taiwan and the US, 6 population-based electronic health record databases from Hong Kong, Scotland, Taiwan, the Netherlands and the UK, and 2 biomedical databases from Taiwan and the UK.

Conclusion

The 15 databases showed good potential for a federated network approach using a common data model. Our study provided publicly accessible information on these databases for those seeking to employ real-world data to facilitate current assessment and future development of treatments for neurological and mental disorders.

Eligibility for Anti-Amyloid Treatment in a Population-Based Study of Cognitive Aging

BACKGROUND AND OBJECTIVES

Treatment options for Alzheimer disease (AD) are limited and have focused mainly on symptomatic therapy and improving quality of life. Recently, lecanemab, an anti-β-amyloid monoclonal antibody (mAb), received accelerated approval by the US Food and Drug Administration for treatment in the early stages of biomarker-confirmed symptomatic AD. An additional anti-β-amyloid mAb, aducanumab, was approved in 2021, and more will potentially become available in the near future. Research on the applicability and generalizability of the anti-β-amyloid mAb eligibility criteria on adults with biomarkers available in the general population has been lacking. The study's primary aim was to apply the clinical trial eligibility criteria for lecanemab treatment to participants with early AD of the population-based Mayo Clinic Study of Aging (MCSA) and assess the generalizability of anti-amyloid treatment. The secondary aim of this study was to apply the clinical trial eligibility criteria for aducanumab treatment in MCSA participants.

METHODS

This cross-sectional study aimed to apply the clinical trial eligibility criteria for lecanemab and aducanumab treatment to participants with early AD of the population-based MCSA and assess the generalizability of anti-amyloid treatment.

RESULTS

Two hundred thirty-seven MCSA participants (mean age [SD] 80.9 [6.3] years, 54.9% male, and 97.5% White) with mild cognitive impairment (MCI) or mild dementia and increased brain amyloid burden by PiB PET comprised the study sample. Lecanemab trial's inclusion criteria reduced the study sample to 112 (47.3% of 237) participants. The trial's exclusion criteria further narrowed the number of potentially eligible participants to 19 (overall 8% of 237). Modifying the eligibility criteria to include all participants with MCI (instead of applying additional cognitive criteria) resulted in 17.4% of participants with MCI being eligible for lecanemab treatment. One hundred four participants (43.9% of 237) fulfilled the aducanumab clinical trial's inclusion criteria. The aducanumab trial's exclusion criteria further reduced the number of available participants, narrowing those eligible to 12 (5.1% of 237). Common exclusions were related to other chronic conditions and neuroimaging findings.

DISCUSSION

Findings estimate the limited eligibility in typical older adults with cognitive impairment for anti-β-amyloid mAbs.

Implications of the Approval of Lecanemab for Alzheimer Disease Patient Care: Incremental Step or Paradigm Shift?

The amyloid cascade model of the pathogenesis of Alzheimer disease (AD) is well supported in observational studies. Its therapeutic corollary asserts that removal of amyloid-β peptide ("amyloid") would provide clinical benefits. After 2 decades of pursuing the strategy of amyloid removal without success, clinical trials of the antiamyloid monoclonal antibody (AAMA) donanemab and a phase 3 clinical trial of lecanemab have reported clinical benefits linked to amyloid removal. Lecanemab (trade name, Leqembi) is the first with published phase 3 trial results. When administered through IV every 2 weeks to patients with elevated brain amyloid and mild cognitive impairment or mild dementia, lecanemab delayed cognitive and functional worsening by approximately 5 months in an 18-month double-blind, placebo-controlled trial. The trial was well conducted, and the results favoring lecanemab were internally consistent. The demonstration that lecanemab treatment delayed clinical progression in persons with mild symptoms due to AD is a major conceptual achievement, but a better appreciation of the magnitude and durability of benefits for individual patients will require extended observations from clinical practice settings. Amyloid-related imaging abnormalities (ARIA) that were largely asymptomatic occurred in approximately 20%, slightly more than half of which were attributable to treatment and the rest to underlying AD-related amyloid angiopathy. Persons who were homozygous for the APOE ε4 allele had greater ARIA risks. Hemorrhagic complications with longer-term lecanemab use need to be better understood. Administration of lecanemab will place unprecedented pressures on dementia care personnel and infrastructure, both of which need to grow exponentially to meet the challenge.

Lipid metabolism transcriptomics of murine microglia in Alzheimer's disease and neuroinflammation

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ) plaques followed by intracellular neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau. An unrestrained immune response by microglia, the resident cells of the central nervous system (CNS), leads to neuroinflammation which can amplify AD pathology. AD pathology is also driven by metabolic dysfunction with strong correlations between dementia and metabolic disorders such as diabetes, hypercholesterolemia, and hypertriglyceridemia. Since elevated cholesterol and triglyceride levels appear to be a major risk factor for developing AD, we investigated the lipid metabolism transcriptome in an AD versus non-AD state using RNA-sequencing (RNA-seq) and microarray datasets from N9 cells and murine microglia. We identified 52 differentially expressed genes (DEG) linked to lipid metabolism in LPS-stimulated N9 microglia versus unstimulated control cells using RNA-seq, 86 lipid metabolism DEG in 5XFAD versus wild-type mice by microarray, with 16 DEG common between both datasets. Functional enrichment and network analyses identified several biological processes and molecular functions, such as cholesterol homeostasis, insulin signaling, and triglyceride metabolism. Furthermore, therapeutic drugs targeting lipid metabolism DEG found in our study were identified. Focusing on drugs that target genes associated with lipid metabolism and neuroinflammation could provide new targets for AD drug development.

Physician Perspectives on the Food and Drug Administration's Decision to Grant Accelerated Approval to Aducanumab for Alzheimer's Disease

In June 2021, the US Food and Drug Administration (FDA) granted accelerated approval to aducanumab, a monoclonal antibody indicated for the treatment of Alzheimer's disease. The accelerated approval decision was controversial due to concerns about the use of an unvalidated surrogate measure, beta-amyloid, as the basis for approval and a lack of clinical outcome benefit. Between October 2021 and September 2022, we conducted a survey of a nationally representative group of internists, medical oncologists, and cardiologists to understand perspectives around aducanumab's approval and how this FDA decision may influence trust in other drugs approved through the accelerated approval program. Among 214 physician respondents familiar with the accelerated approval of aducanumab, 184 (86%) would not prescribe or recommend aducanumab. Further, 143 (67%) physicians reported losing trust in other drugs approved through the accelerated approval program due to the FDA's decision with aducanumab. As a growing number of similar novel Alzheimer's disease treatments are on the horizon, the first of which, lecanemab, already has received accelerated approval in January 2023, our survey findings provide insight into the impact of the FDA's regulatory decisions on the perspectives and prescribing behavior of physicians concerning these novel drug treatments.

Advances in amyloid-targeting monoclonal antibodies for Alzheimer's disease: clinical and public health issues

INTRODUCTION

Alzheimer's disease (AD) is a major global public health challenge. To date, no treatments have been shown to stop the underlying pathological processes. The cerebral accumulation of amyloid-beta (Ab) is still considered as the primum movens of AD and disease-modifying treatments targeting Ab are reaching - or have already reached - clinical practice.

AREAS COVERED

The authors explore the main advancements from Aβ-targeting monoclonal antibodies (mAbs) for the treatment of AD. From a public health perspective, they address ethically relevant issues such as the benevolence and non-maleficence principles. They report on the potential biological and clinical benefits of these drugs, discussing minimal clinically important differences (MCID) and other relevant outcomes. They examine the short- and long-term effects of amyloid-related imaging abnormalities (ARIA), and explore the differences between eligibility criteria in clinical trials, appropriate use recommendations, and prescribing information content. In doing so, they contextualize the discussion on the disagreements among different regulatory authorities.

EXPERT OPINION

Although anti-β-amyloid monoclonal antibodies may be effective in selected scenarios, non-negligible knowledge gaps and implementation limits persist. Overcoming these gaps can no longer be postponed if we are to ensure the principles of Quality of Care for patients with cognitive impairment who would be eligible for this class of drugs.

FDA's dilemma with the aducanumab approval: public pressure and hope, surrogate markers and efficacy, and possible next steps

Accelerating Food and Drug Administration (FDA) product approval to market based on surrogate markers in the absence of proven efficacy creates a risk of adverse outcomes for affected patients, even in response to a life-threatening condition, such as in this case, Alzheimer's disease. FDA's recent unexpected approval of aducanumab, despite the unified opposition of its own highly respected advisory committee after the early termination of two efficacy trials, creates the potential risk of adverse effects and lack of clinical efficacy at very high costs. In view of these concerns, a thorough review of the issues and pressures that led to this decision is worth the careful consideration of the clinical and scientific communities with regard to whether this approval represents a calculated and balanced compassionate decision versus a disturbing precedent.

Improving generalizability and study design of Alzheimer's disease cohort studies in the United States by including under-represented populations

The poor generalizability of clinical research data due to the enrollment of highly educated, non-Latinx White participants hampers the development of therapies for Alzheimer's disease (AD). Black and Latinx older adults have a greater risk for dementia, yet it is unclear how health-care disparities and sociocultural factors influence potential AD therapies and prognosis. Low enrollment of under-represented populations may be attributable to several factors including greater exclusion due to higher rates of comorbidities, lower access to AD clinics, and the legacy of unethical treatment in medical research. This perspective outlines solutions tested in the Brain Health Registry (BHR) and the Alzheimer's Disease Neuroimaging Initiative (ADNI), including culturally-informed digital research methods, community-engaged research strategies, leadership from under-represented communities, and the reduction of exclusion criteria based on comorbidities. Our successes demonstrate that it is possible to increase the inclusion and engagement of under-represented populations into US-based clinical studies, thereby increasing the generalizability of their results.

Recruitment across two decades of NIH-funded Alzheimer's disease clinical trials

BACKGROUND

Timely accrual of a representative sample is a key factor in whether Alzheimer's disease (AD) clinical trials successfully answer the scientific questions under study. Studies in other fields have observed that, over time, recruitment to trials has become increasingly reliant on larger numbers of sites, with declines in the average per-site recruitment rate. Here, we examined the trends in recruitment over a 20-year period of NIH-funded AD clinical trials conducted by the Alzheimer's Disease Cooperative Study (ADCS), a temporally consistent network of sites devoted to interventional research.

METHODS

We performed retrospective analyses of eleven ADCS randomized clinical trials. To examine the recruitment planning, we calculated the expected number of participants to be enrolled per site for each trial. To examine the actual trial recruitment rates, we quantified the number of participants enrolled per site per month.

RESULTS

No effects of time were observed on recruitment planning or overall recruitment rates across trials. No trial achieved an overall recruitment rate greater than one subject per site per month. We observed the fastest recruitment rates in trials with no competition and the slowest in trials that overlapped in time. The highest recruitment rates were consistently seen early within trials and declined over the course of studies.

CONCLUSIONS

Trial recruitment projections should plan for fewer than one participant randomized per site per month and consider the number of other AD trials being conducted concurrently.

Global estimates on the number of persons across the Alzheimer's disease continuum

INTRODUCTION

Global estimates on numbers of persons in early stages of Alzheimer's disease (AD), including prodromal and preclinical, are lacking, yet are needed to inform policy decisions on preventive measures and planning for future therapies targeting AD pathology.

METHODS

We synthesized the literature on prevalence across the AD continuum and derived a model estimating the number of persons, stratified by 5-year age groups, sex, and disease stage (AD dementia, prodromal AD, and preclinical AD).

RESULTS

The global number of persons with AD dementia, prodromal AD, and preclinical AD were estimated at 32, 69, and 315 million, respectively. Together they constituted 416 million across the AD continuum, or 22% of all persons aged 50 and above.

DISCUSSION

Considering predementia stages, the number of persons with AD is much larger than conveyed in available literature. Our estimates are uncertain, especially for predementia stages in low- and middle-income regions where biomarker studies are missing.

Observational studies in Alzheimer disease: bridging preclinical studies and clinical trials

Recent high-profile failures of Alzheimer disease treatments at the clinical trial stage have led to renewed efforts to identify and test novel interventions for Alzheimer disease and related dementias (ADRD). In this Perspective, we highlight the importance of including well-designed observational studies as part of these efforts. Observational research is an important cornerstone for gathering evidence on risk factors and causes of ADRD; this evidence can then be combined with data from preclinical studies and randomized controlled trials to inform the development of effective interventions. Observational study designs can be particularly beneficial for hypothesis generation, posing questions that are unethical or impractical for a trial setting, studying life-course associations, research in populations typically not included in trials, and public health surveillance. Here, we discuss each of these situations in the specific context of ADRD research. We also highlight novel approaches to enhance causal inference and provide a timely discussion on how observational epidemiological studies help provide a bridge between preclinical studies and successful interventions for ADRD.

High-clearance anti-amyloid immunotherapies in Alzheimer's disease. Part 2: putative scenarios and timeline in case of approval, recommendations for use, implementation, and ethical considerations in France

In 2021, aducanumab, an immunotherapy targeting amyloid-β, was approved for Alzheimer's disease (AD) by the US Food and Drug Administration thanks to positive results on a putative biological surrogate marker. This approval has raised an unprecedented controversy. It was followed by a refusal of the European Medicine Agency, which does not allow the marketing of drugs solely on biological arguments and raised safety issues, and important US coverage limitations by the Centers for Medicare & Medicaid Services. Two other anti-amyloid immunotherapies showed significant results regarding a clinical outcome in phase II trials, and five drugs are being studied in phase III trials. Lecanemab is currently under examination for an 'Accelerated Approval' in the US, with an expected decision in January 2023. The common feature and novelty of these anti-amyloid immunotherapies, compared to those tested in previous trials of the 2010s, is their ability to induce a high clearance of amyloid load, as measured with positron emission tomography, in the brain of early-stage biomarker-proven AD patients. In the first part of this review, we underlined through a meta-analysis that the pooled data from high-clearance anti-amyloid immunotherapies trials demonstrated a significant but slight clinical effect after 18 months. Still, safety remains an issue with serious and symptomatic amyloid-related imaging abnormalities, which are seldom (∼1 per 200 treated patients) but occur beyond chance. In the second part of this review, we hypothesized that there is a high probability that some phase III trials of high-clearance anti-amyloid immunotherapies in early AD will finally be unarguably positive on clinical outcomes in the next five years with acceptable safety data. This may, in turn, lead to approval by the European Medicine Agency if the risk-benefit profile is deemed favorable. Such approval would be a game-changer in managing AD patients and for the organization of memory clinics in France. We review the possible timeline and scenarios for putative approval in France and make propositions regarding putative use in clinical practice, putative implementation in a real-life setting, and ethical considerations.

mRNA Vaccines Against SARS-CoV-2 Variants Delivered by Lipid Nanoparticles Based on Novel Ionizable Lipids

SARS-CoV-2 variants are now still challenging all the approved vaccines, including mRNA vaccines. There is an urgent need to develop new generation mRNA vaccines with more powerful efficacy and better safety against SARS-CoV-2 variants. In this study, a new set of ionizable lipids named 4N4T are constructed and applied to form novel lipid nanoparticles called 4N4T-LNPs. Leading 4N4T-LNPs exhibit much higher mRNA translation efficiency than the approved SM-102-LNPs. To test the effectiveness of the novel delivery system, the DS mRNA encoding the full-length S protein of the SARS-CoV-2 variant is synthesized and loaded in 4N4T-LNPs. The obtained 4N4T-DS mRNA vaccines successfully trigger robust and durable humoral immune responses against SARS-CoV-2 and its variants including Delta and Omicron. Importantly, the novel vaccines have higher RBD-specific IgG titers and neutralizing antibody titers than SM-102-based DS mRNA vaccine. Besides, for the first time, the types of mRNA vaccine-induced neutralizing antibodies are found to be influenced by the chemical structure of ionizable lipids. 4N4T-DS mRNA vaccines also induce strong Th1-skewed T cell responses and have good safety. This work provides a novel vehicle for mRNA delivery that is more effective than the approved LNPs and shows its application in vaccines against SARS-CoV-2 variants.

Aduhelm, the Newly Approved Medication for Alzheimer Disease: What Epidemiologists Can Learn and What Epidemiology Can Offer

Alzheimer disease (AD) is a progressive disorder common among older adults and culminating in profound cognitive impairments and high mortality risk. The US Food and Drug Administration (FDA) recently provided accelerated approval for Aduhelm, a medication for AD treatment. Aduhelm (Biogen Inc., Cambridge, Massachusetts) has been described as the first disease-modifying treatment for AD but has not been demonstrated to improve patients' cognitive or functional outcomes. In this commentary, we describe why Aduhelm approval was controversial and aspects of the current evidence of special pertinence to epidemiologists. The FDA decision was based primarily on 2 randomized controlled trials (RCTs), both terminated early, with conflicting findings about the cognitive benefits of Aduhelm. Both RCTs showed important adverse effects of the medication. The FDA cited the documented reduction in brain amyloid, an AD biomarker hypothesized as a surrogate outcome, to justify accelerated approval. Despite lack of racial/ethnic diversity in the RCT participants, concerns about health disparities have been invoked to argue for public funding of this expensive medication. The Centers for Medicare and Medicaid Services recently made a "Coverage with Evidence Development" determination for Aduhelm and similar medications. We end by describing how innovative study designs could accelerate postapproval research and evaluate the proposed surrogate outcomes.

Addressing Challenges to Alternative Payment Models for New Alzheimer's Disease Therapies for US Commercial Payers

Commercial payers that ultimately decide to cover aducanumab or other Alzheimer's disease therapies may require innovative payment tools to minimize their financial risk given the uncertain benefits and high cost of such treatments. Drawing on the published evidence, we propose two different types of payment models applicable to disease-modifying therapies in Alzheimer's disease, and suggest four strategies to overcome challenges in their implementation. Such strategies range from developing best practices for outcome measurement in Alzheimer's disease, investing in infrastructure to collect real-world data, increasing representativeness of registry data in Alzheimer's disease, and integrating the diagnostic, treatment, and payment landscape. These important steps could make access to emerging therapies in Alzheimer's disease more sustainable in the long term, and could serve as a blueprint for better access to novel therapies in other indications in the future.

Blood-brain barrier leakage in Alzheimer's disease: From discovery to clinical relevance

Alzheimer's disease (AD) is the most common form of dementia. AD brain pathology starts decades before the onset of clinical symptoms. One early pathological hallmark is blood-brain barrier dysfunction characterized by barrier leakage and associated with cognitive decline. In this review, we summarize the existing literature on the extent and clinical relevance of barrier leakage in AD. First, we focus on AD animal models and their susceptibility to barrier leakage based on age and genetic background. Second, we re-examine barrier dysfunction in clinical and postmortem studies, summarize changes that lead to barrier leakage in patients and highlight the clinical relevance of barrier leakage in AD. Third, we summarize signaling mechanisms that link barrier leakage to neurodegeneration and cognitive decline in AD. Finally, we discuss clinical relevance and potential therapeutic strategies and provide future perspectives on investigating barrier leakage in AD. Identifying mechanistic steps underlying barrier leakage has the potential to unravel new targets that can be used to develop novel therapeutic strategies to repair barrier leakage and slow cognitive decline in AD and AD-related dementias.

Management of Dementia

PURPOSE OF REVIEW

This article describes an approach to managing patients following a diagnosis of dementia, including medical management, nonpharmacologic strategies, safety interventions, caregiver support, mobilization of community resources, and advanced care planning.

RECENT FINDINGS

Dementia clinical syndromes are frequently caused by mixed pathologies, leading to varied clinical presentations that include memory loss, behavioral changes, communication challenges, safety concerns, and loss of independent function. Medications for treating dementia currently target cognitive and behavioral symptoms, although disease-modifying therapies for Alzheimer disease may be making their way into widespread clinical practice soon. Identification and treatment of co-occurring medical problems, such as obstructive sleep apnea, adverse medication effects, mood disorders, hearing loss, pain, alcohol misuse, and vascular risk factors, may mitigate the impact of these conditions on cognitive decline. Mobilization of clinical and community-based interprofessional teams will ensure that people with dementia and their care partners have the expertise, support, and access to resources they need. Addressing goals of care early in the disease course will allow people with dementia to contribute to their care plan by expressing their wishes.

SUMMARY

Developing a structured approach to treating common causes of dementia and related comorbid medical conditions, identifying a local network of interprofessional clinical and community-based referrals, and providing readily available educational resources will help clinicians provide quality dementia care management that extends beyond the clinic visit. Encouraging patients and families to engage in clinical research will advance the identification of effective therapies, preventive strategies, and quality care models for the future.

Are we ready to use anti-amyloid therapy in Alzheimer's disease?

Alzheimer's disease (AD) is the most common neurodegenerative disease. Biomarkers have demonstrated that AD pathology exists over the disease continuum from a stage preceding symptoms over 15-25 years to the progressively more impaired symptomatic states, mild cognitive impairment (MCI), and dementia. Biomarkers include: amyloid (Aß), phosphorylated tau, and neurodegeneration. The plasma assays for Aß and tau show great promise for clinical and research use. This review has aimed not only to present the ATN diagnostic classification and the preclinical AD concepts in addressing some possibilities of cognitive assessment instruments, but also to briefly summarize the main anti-amyloid monoclonal antibodies studied in clinical trials. In addition, this paper presents a critical analysis by experts in cognitive neurology while addressing the question as to whether we are prepared for the anti-amyloid therapy era or not.

Aducanumab Use in Symptomatic Alzheimer Disease Evidence in Focus: A Report of the AAN Guidelines Subcommittee

OBJECTIVE

To identify the class of evidence for aducanumab use for the treatment of Alzheimer disease and present clinical considerations regarding use.

METHODS

The author panel systematically reviewed available clinical trial data detailing aducanumab use in individuals with early symptomatic Alzheimer disease. Level of evidence statements were assigned in accordance with the American Academy of Neurology's 2017 therapeutic classification of evidence scheme. Safety information, regulatory decisions, and clinical context were also reviewed.

RESULTS

Data were identified from 4 clinical trials, 1 rated Class I and 3 rated Class II. The Class I study showed that single doses of aducanumab up to 30 mg/kg were safe and well tolerated. All 3 Class II studies provided evidence that aducanumab (3-10 mg/kg) decreased amyloid deposition on brain PET at 1 year vs placebo. Efficacy data in the Class II studies varied by dose and outcome, but aducanumab either had no effect on mean change on the Clinical Dementia Rating Sum of Boxes scores or resulted in less worsening (vs placebo) that was of uncertain clinical importance. Adverse amyloid-related imaging abnormalities occurred in approximately 40% of individuals treated with aducanumab vs 10% receiving placebo.

CLINICAL CONTEXT

Administration of aducanumab will require expanded clinical infrastructure. Evidence-based guidance is needed to address key questions (e.g., safety in populations not enrolled in phase 3 studies, expected benefits on daily function, treatment duration) and critical issues relating to access to aducanumab (e.g., coverage, costs, burden of monthly infusions) that will inform shared decision making between patients and providers.

Use of Extrapolation in New Drug Approvals by the US Food and Drug Administration

IMPORTANCE

The US Food and Drug Administration (FDA)-approved indications can be factors in prescribing practices and insurance coverage, yet the frequency with which the extrapolation of clinical characteristics from pivotal trial data to the final approved indication occurs is not well understood.

OBJECTIVES

To evaluate the frequency of extrapolation beyond pivotal trial data into approved indications in relation to disease severity, disease subtype, and concomitant medication use.

DESIGN, SETTING, AND PARTICIPANTS

In a cross-sectional study, the characteristics of patients in pivotal trials of 105 novel drug approvals from 2015 to 2017 were identified and compared with the FDA-approved indications for the drugs. Main sources analyzed included FDA reviews, published material describing the pivotal trials, and the original drug labeling. The study was conducted from July 4, 2019, to June 1, 2021.

EXPOSURES

Clinical characteristics of pivotal trials used in FDA approval.

MAIN OUTCOMES AND MEASURES

Main outcomes included the nature and frequency of extrapolation from study populations to the final indications. Extrapolation was defined as the granting of an indication for use in a broader population than was included in the pivotal trials on the basis of disease severity, disease subtype, or concomitant medication use.

RESULTS

Among the 105 novel FDA drug approvals studied, 23 extrapolations of trial population characteristics to the approved indication were identified in 21 drugs (20%): 12 times (29%) in 2015, 3 times (15%) in 2016, and 6 times (14%) in 2017. Extrapolation of trial findings to patients with greater disease severity was most common (n = 14 drugs), followed by differences in disease subtype (n = 6) and concomitant medication use (n = 3).

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that extrapolation from pivotal trial data to FDA-approved indications is common. Although extrapolations may be grounded in reasonable clinical predictions, they can limit the generalizability of such indications to specific prescribing decisions; these findings suggest a greater need for close postapproval monitoring to determine whether new safety issues arise, or effectiveness differs from expectations when these medications are used in broader real-world populations.

[Causal treatment of Alzheimer's disease: amyloid antibodies]

BACKGROUND

Alzheimer's disease (AD) is the most common cause of dementia. The number of people affected will increase dramatically in the coming decades due to the demographic change. Causal pharmacological approaches have not been available to date. The monoclonal anti-amyloid beta antibody aducanumab was recently approved for the treatment of AD in the USA but was rejected in Europe in December 2021 by the European Medicines Agency (EMA).

OBJECTIVE

This review presents the background and rationale for amyloid beta-directed treatment approaches in AD. The focus is on passive immunization with monoclonal anti-amyloid beta antibodies.

DATA SITUATION

There are four monoclonal anti-amyloid beta antibodies in an advanced stage of clinical development. Evidence of a clear and significant reduction of the cerebral amyloid load was found for all of them. In the case of aducanumab this has already led to approval by the U.S. Food and Drug Administration (FDA). In the USA donanemab, gantenerumab and lecanemab have received the status of a so-called breakthrough therapy and are expected to go through an accelerated approval process by the FDA in the next 1-2 years.

CONCLUSION

Anti-amyloid antibodies represent the first cause-based, disease-modifying therapy for AD approved in the USA. Compared to the near-complete removal of cerebral amyloid plaques, the magnitude of the clinical effect is smaller and the benefit for patients is currently subject to controversial discussions. Nonetheless, the new treatment option represents an important step in the development of effective treatment. Future strategies for the treatment of AD will likely aim at a multimodal concept with different molecular targets. A prerequisite for all effective disease-modifying therapies will be an early biomarker-based diagnosis prior to the onset of a dementia-type syndrome.

Aducanumab Therapy to Treat Alzheimer's Disease: A Narrative Review

Background

Aducanumab, a new monoclonal antibody that targets β-amyloid aggregates, has been granted conditional approval by the U.S. FDA for treatment of mild Alzheimer's disease (AD). The approval of this drug without a confirmed significant clinical impact has resulted in several debates.

Objective

In this narrative review, aducanumab approval-related controversy, the drug's pharmacokinetics and pharmacodynamic characteristics, evidence from the efficacy and safety trials of aducanumab, implications of the drug approval, and the future directions in the management of patients with AD are summarized.

Methods

Using relevant keywords, Google Scholar, Web of Science, and MEDLINE databases and manufacturer's website were searched.

Results

Infusion of aducanumab at a higher dose resulted in a modest slowing of cognitive decline among patients with mild cognitive impairment or early-onset AD dementia. The drug however can cause amyloid-related imaging abnormalities. Due to modest impact on cognition, the use of this drug by patients with AD will most likely be limited. The manufacturer is required to run an extended phase IIIb trial to verify the benefit of this drug. Access to therapy requires a careful selection of patients and periodic monitoring to ensure the optimal use of the drug.

Conclusion

Despite the limitations, aducanumab is the first disease-modifying therapy approved for the treatment of AD. Aducanumab addresses a part of the pathogenesis of AD; therefore, drugs that can act on multiple targets are needed. In addition, the search for preventive strategies, validated plasma-based assays, and newer drugs for AD, which are effective, safe, convenient, and affordable, is vital.

Exosomes in Age-Related Cognitive Decline: Mechanistic Insights and Improving Outcomes

Aging is the most prominent risk factor for cognitive decline, yet behavioral symptomology and underlying neurobiology can vary between individuals. Certain individuals exhibit significant age-related cognitive impairments, while others maintain intact cognitive functioning with only minimal decline. Recent developments in genomic, proteomic, and functional imaging approaches have provided insights into the molecular and cellular substrates of cognitive decline in age-related neuropathologies. Despite the emergence of novel tools, accurately and reliably predicting longitudinal cognitive trajectories and improving functional outcomes for the elderly remains a major challenge. One promising approach has been the use of exosomes, a subgroup of extracellular vesicles that regulate intercellular communication and are easily accessible compared to other approaches. In the current review, we highlight recent findings which illustrate how the analysis of exosomes can improve our understanding of the underlying neurobiological mechanisms that contribute to cognitive variation in aging. Specifically, we focus on exosome-mediated regulation of miRNAs, neuroinflammation, and aggregate-prone proteins. In addition, we discuss how exosomes might be used to enhance individual patient outcomes by serving as reliable biomarkers of cognitive decline and as nanocarriers to deliver therapeutic agents to the brain in neurodegenerative conditions.

Key Recommendations from the 2021 “Inclusion of Older Adults in Clinical Research” Workshop

Older adults are often underrepresented in clinical research, even though older adults are major consumers of novel therapies. We present major themes and recommendations from the 2021 "Inclusion of Older Adults in Clinical Research" Workshop, convened by the Clinical and Translational Science Award (CTSA) Inclusion of Older Adults as a Model for Special Populations Workgroup and the Research Centers Collaborative Network (RCCN). The goal of this workshop was to develop strategies to assist the research community in increasing the inclusion of older adults in clinical research. Major identified barriers include historical lack of federal guidelines, ageist biases and stereotypes, and lack of recruitment and retention techniques or infrastructure focused on older adults. Three key recommendations emerged: 1) engaging with the policymaking process to further promote inclusion; 2) using the CTSA Workgroup Presentation Materials Library and other resources to overcome ageism, and 3) building institutional capacity to support age inclusion.

Heterogeneity in Alzheimer's Disease Diagnosis and Progression Rates: Implications for Therapeutic Trials

The clinical presentation and the pathological processes underlying Alzheimer's disease (AD) can be very heterogeneous in severity, location, and composition including the amount and distribution of AB deposition and spread of neurofibrillary tangles in different brain regions resulting in atypical clinical patterns and the existence of distinct AD variants. Heterogeneity in AD may be related to demographic factors (such as age, sex, educational and socioeconomic level) and genetic factors, which influence underlying pathology, the cognitive and behavioral phenotype, rate of progression, the occurrence of neuropsychiatric features, and the presence of comorbidities (e.g., vascular disease, neuroinflammation). Heterogeneity is also manifest in the individual resilience to the development of neuropathology (brain reserve) and the ability to compensate for its cognitive and functional impact (cognitive and functional reserve). The variability in specific cognitive profiles and types of functional impairment may be associated with different progression rates, and standard measures assessing progression may not be equivalent for individual cognitive and functional profiles. Other factors, which may govern the presence, rate, and type of progression of AD, include the individuals' general medical health, the presence of specific systemic conditions, and lifestyle factors, including physical exercise, cognitive and social stimulation, amount of leisure activities, environmental stressors, such as toxins and pollution, and the effects of medications used to treat medical and behavioral conditions. These factors that affect progression are important to consider while designing a clinical trial to ensure, as far as possible, well-balanced treatment and control groups.

The Current Landscape of Prevention Trials in Dementia

As the prevalence of dementia and Alzheimer's disease (AD) increases worldwide, it is imperative to reflect on the major clinical trials in the prevention of dementia and the challenges that surround them. The pharmaceutical industry has focused on developing drugs that primarily affect the Aβ cascade and tau proteinopathy, while academics have focused on repurposed therapeutics and multi-domain interventions for prevention studies. This paper highlights significant primary, secondary, and tertiary prevention trials for dementia and AD, overall design, methods, and systematic issues to better understand the current landscape of prevention trials. We included 32 pharmacologic intervention trials and 9 multi-domain trials. Fourteen could be considered primary prevention, and 18 secondary or tertiary prevention trials. Major categories were Aβ vaccines, Aβ antibodies, tau antibodies, anti-inflammatories, sex hormones, and Ginkgo biloba extract. The 9 multi-domain studies mainly focused on lifestyle modifications such as blood pressure management, socialization, and physical activity. The lack of validated drug targets, and the complexity of the diagnostic frameworks, eligibility criteria, and outcome measurements for trials, make it difficult to show efficacy for both pharmacological and multi-domain interventions. We hope that this summative analysis of trials will stimulate discussion for scientists and clinicians interested in reviewing and developing preventative interventions for AD.