Search Results (18)

Anti-amyloid monoclonal antibodies have finally achieved their translational breakthrough after many years of unmet expectations. The FDA granted traditional approval to lecanemab in July 2023, and the European Medicines Agency approved it in late 2024 with specific genetic restrictions; meanwhile, donanemab received FDA approval in July 2024 and EMA marketing authorization just one month ago. These agents consistently clear cerebral amyloid and slow clinical decline modestly in early-stage, biomarker-confirmed Alzheimer’s disease (AD). On the other hand, they also create significant safety risks, including amyloid-related imaging abnormalities (ARIA) and substantial operational requirements for health systems that are already under pressure. Therefore, precise risk management based on APOE genotyping and the presence of cerebral amyloid angiopathy and cerebral microbleeds should be performed before therapy is initiated. The near-term agenda should prioritize the following areas of study: (1) biomarker-driven front-end triage (including emerging plasma assays); (2) ARIA-aware care pathways and shared decision making; (3) outcome-based coverage and rational pricing; (4) clinical trials that layer anti-amyloid therapy into combinatorial strategies targeting tau protein, neuroinflammation, and synaptic resilience. Full article

Alzheimer’s disease (AD) is the most common cause of cognitive decline; currently, anti-amyloid monoclonal antibodies are available for clinical use as disease-modifying treatments, while many other substances are being tested in clinical trials. Molecular biomarkers for AD have been studied for more than two decades, and various guidelines and diagnostic recommendations have been published. However, there are still questions and controversies about the biomarker profile needed to confirm AD and the eligibility for such established treatments and clinical trials. Is amyloid positivity sufficient for eligibility, or is a biomarker for tau biochemistry/pathology also needed? What is the role of hybrid ratios combining amyloid and tau? Should we rely on plasma biomarkers alone? This review aimed to describe and discuss such questions and controversies. Full article

Alzheimer’s disease (AD) is the most common cause of dementia, pathologically defined by extracellular amyloid-β (Aβ) plaques and intracellular tau neurofibrillary tangles. Recent U.S. Food and Drug Administration (FDA) approvals of anti-amyloid monoclonal antibodies (mAbs) aducanumab, lecanemab, and donanemab represent the first disease-modifying therapies for early AD. These therapies have generated both optimism and controversy due to modest efficacy and safety concerns, particularly amyloid-related imaging abnormalities (ARIAs). This review synthesizes current evidence on the efficacy, safety, and biomarker-guided use of anti-Aβ mAbs in AD. Methods: We searched PubMed, Scopus, Web of Science, and Google Scholar to 31 July 2025 for studies on anti-amyloid mAbs in AD. Sources included peer-reviewed articles and regulatory reports. The extracted data covered study design, population, amyloid confirmation, dosing, outcomes, biomarkers, ARIA incidence, and management. Results: Anti-amyloid mAbs consistently demonstrated robust amyloid clearance and modest slowing of clinical decline in early symptomatic AD. Differences emerged across agents in efficacy signals, safety profiles, and regulatory outcomes. Lecanemab and donanemab showed more consistent cognitive benefits, while aducanumab yielded mixed findings, leading to its withdrawal. ARIAs were the most frequent adverse events, occurring more often in APOE ε4 carriers and typically during early treatment. Biomarker analyses also revealed favorable downstream effects, including reductions in phosphorylated tau and markers of astroglial injury, supporting engagement of disease biology. Conclusions: Anti-amyloid mAbs provide proof of concept for AD modification, with the greatest benefit in early disease stages and moderate tau burden. Optimal use requires biomarker confirmation of the amyloid, careful tau staging, and genetic risk assessment. While limitations remain, these therapies represent a pivotal step toward precision neurology and may serve as a foundation for multimodal strategies targeting tau, neuroinflammation, and vascular pathology. Full article

Alzheimer’s disease (AD) impacts more than half a million people worldwide, with no cure available. The regulatory approval of three anti-amyloid monoclonal antibodies (mAbs), including aducanumab, lecanemab, and donanemab, has established immunotherapy as a therapeutic approach to modify disease progression. Its multifactorial pathology, which involves amyloid-β (Aβ) plaques, tau neurofibrillary tangles, neuroinflammation, and cerebrovascular dysfunction, limits the efficacy of single-target therapies. The restricted blood–brain barrier (BBB) penetration and amyloid-related imaging abnormalities (ARIA), together with small treatment effects, demonstrate the necessity for advanced biologic therapies. Protein engineering advancements have created bispecific antibodies that bind to pathological proteins (e.g., Aβ, tau) and BBB shuttle receptors to boost brain delivery and dual therapeutic effects. This review combines existing information about antibody-based therapy in AD by focusing on bispecific antibody formats and their preclinical and clinical development, as well as biomarker-based patient selection and upcoming combination strategies. The combination of rationally designed bispecific antibodies with fluid and imaging biomarkers could show potential for overcoming existing therapeutic challenges and delivering significant clinical advantages. Full article

The present Perspective analyzes the remarkable evolution of the Amyloid Cascade Hypothesis 2.0 (ACH2.0) theory of Alzheimer’s disease (AD) since its inception a few years ago, as reflected in the diminishing role of amyloid-beta (Aβ) in the disease. In the initial iteration of the ACH2.0, Aβ-protein-precursor (AβPP)-derived intraneuronal Aβ (iAβ), accumulated to neuronal integrated stress response (ISR)-eliciting levels, triggers AD. The neuronal ISR, in turn, activates the AβPP-independent production of its C99 fragment that is processed into iAβ, which drives the disease. The second iteration of the ACH2.0 stemmed from the realization that AD is, in fact, a disease of the sustained neuronal ISR. It introduced two categories of AD—conventional and unconventional—differing mainly in the manner of their causation. The former is caused by the neuronal ISR triggered by AβPP-derived iAβ, whereas in the latter, the neuronal ISR is elicited by stressors distinct from AβPP-derived iAβ and arising from brain trauma, viral and bacterial infections, and various types of inflammation. Moreover, conventional AD always contains an unconventional component, and in both forms, the disease is driven by iAβ generated independently of AβPP. In its third, the current, iteration, the ACH2.0 posits that proteolytic production of Aβ is suppressed in AD-affected neurons and that the disease is driven by C99 generated independently of AβPP. Suppression of Aβ production in AD seems an oxymoron: Aβ is equated with AD, and the later is inconceivable without the former in an ingrained Amyloid Cascade Hypothesis (ACH)-based notion. But suppression of Aβ production in AD-affected neurons is where the logic leads, and to follow it we only need to overcome the inertia of the preexisting assumptions. Moreover, not only is the generation of Aβ suppressed, so is the production of all components of the AβPP proteolytic pathway. This assertion is not a quantum leap (unless overcoming the inertia counts as such): the global cellular protein synthesis is severely suppressed under the neuronal ISR conditions, and there is no reason for constituents of the AβPP proteolytic pathway to be exempted, and they, apparently, are not, as indicated by the empirical data. In contrast, tau protein translation persists in AD-affected neurons under ISR conditions because the human tau mRNA contains an internal ribosomal entry site in its 5′UTR. In current mouse models, iAβ derived from AβPP expressed exogenously from human transgenes elicits the neuronal ISR and thus suppresses its own production. Its levels cannot principally reach AD pathology-causing levels regardless of the number of transgenes or the types of FAD mutations that they (or additional transgenes) carry. Since the AβPP-independent C99 production pathway is inoperative in mice, the current transgenic models have no potential for developing the full spectrum of AD pathology. What they display are only effects of the AβPP-derived iAβ-elicited neuronal ISR. The paper describes strategies to construct adequate transgenic AD models. It also details the utilization of human neuronal cells as the only adequate model system currently available for conventional and unconventional AD. The final alteration of the ACH2.0, introduced in the present Perspective, is that AβPP, which supports neuronal functionality and viability, is, after all, potentially produced in AD-affected neurons, albeit not conventionally but in an ISR-driven and -compatible process. Thus, the present narrative begins with the “omnipotent” Aβ capable of both triggering and driving the disease and ends up with this peptide largely dislodged from its pedestal and retaining its central role in triggering the disease in only one, although prevalent (conventional), category of AD (and driving it in none). Among interesting inferences of the present Perspective is the determination that “sporadic AD” is not sporadic at all (“non-familial” would be a much better designation). The term has fatalistic connotations, implying that the disease can strike at random. This is patently not the case: The conventional disease affects a distinct subpopulation, and the basis for unconventional AD is well understood. Another conclusion is that, unless prevented, the occurrence of conventional AD is inevitable given a sufficiently long lifespan. This Perspective also defines therapeutic directions not to be taken as well as auspicious ways forward. The former category includes ACH-based drugs (those interfering with the proteolytic production of Aβ and/or depleting extracellular Aβ). They are legitimate (albeit inefficient) preventive agents for conventional AD. There is, however, a proverbial snowball’s chance in hell of them being effective in symptomatic AD, lecanemab, donanemab, and any other “…mab” or “…stat” notwithstanding. They comprise Aβ-specific antibodies, inhibitors of beta- and gamma-secretase, and modulators of the latter. In the latter category, among ways to go are the following: (1) Depletion of iAβ, which, if sufficiently “deep”, opens up a tantalizing possibility of once-in-a-lifetime preventive transient treatment for conventional AD and aging-associated cognitive decline, AACD. (2) Composite therapy comprising the degradation of C99/iAβ and concurrent inhibition of the neuronal ISR. A single transient treatment could be sufficient to arrest the progression of conventional AD and prevent its recurrence for life. Multiple recurrent treatments would achieve the same outcome in unconventional AD. Alternatively, the sustained reduction/removal of unconventional neuronal ISR-eliciting stressors through the elimination of their source would convert unconventional AD into conventional one, preventable/treatable by a single transient administration of the composite C99/iAβ depletion/ISR suppression therapy. Efficient and suitable ISR inhibitors are available, and it is explicitly clear where to look for C99/iAβ-specific targeted degradation agents—activators of BACE1 and, especially, BACE2. Directly acting C99/iAβ-specific degradation agents such as proteolysis-targeting chimeras (PROTACs) and molecular-glue degraders (MGDs) are also viable options. (3) A circumscribed shift (either upstream or downstream) of the position of transcription start site (TSS) of the human AβPP gene, or, alternatively, a gene editing-mediated excision or replacement of a small, defined segment of its portion encoding 5′-untranslated region of AβPP mRNA; targeting AβPP RNA with anti-antisense oligonucleotides is another possibility. If properly executed, these RNA-based strategies would not interfere with the protein-coding potential of AβPP mRNA, and each would be capable of both preventing and stopping the AβPP-independent generation of C99 and thus of either preventing AD or arresting the progression of the disease in its conventional and unconventional forms. The paper is interspersed with “validation” sections: every conceptually significant notion is either validated by the existing data or an experimental procedure validating it is proposed. Full article

Objective: The purpose of this review is to examine the potential role of donanemab-azbt in the treatment and management of early-stage Alzheimer’s disease (AD), with a focus on its efficacy, safety, and clinical relevance based on data from key clinical trials. Data Sources: A comprehensive literature search of PubMed was conducted using relevant keywords such as “donanemab”, “Alzheimer’s disease”, “Kisunla”, “TRAILBLAZER clinical trials”, and “amyloid-related imaging abnormalities (ARIA)”. Additional data were extracted from clinical trial records (clinicaltrials.gov), conference abstracts, and product monographs. Study Selection and Data Extraction: Only English-language studies conducted in human populations were included. Clinical trials and peer-reviewed studies detailing the efficacy, safety, and mechanistic insights of donanemab-azbt were prioritized. Data Synthesis: Key findings from the TRAILBLAZER series of clinical trials highlighted the potential of donanemab-azbt in slowing cognitive and functional decline in early-stage AD: (1) TRAILBLAZER-ALZ (Phase 2): This trial focused on participants with intermediate levels of tau protein. Results demonstrated a statistically significant slowing of cognitive and functional decline. (2) TRAILBLAZER-ALZ 2 (Phase 3): A large-scale, randomized, double-blind, placebo-controlled study confirmed the efficacy of donanemab-azbt in reducing amyloid plaque accumulation and cognitive decline. Key results included a 35% slowing of decline on the Integrated Alzheimer’s Disease Rating Scale (iADRS) and a 36% slowing on the Clinical Dementia Rating-Sum of Boxes (CDR-SB). Additional secondary outcomes showed improvements in activities of daily living and reduced risk of disease progression. (3) TRAILBLAZER-ALZ 3: This ongoing trial is evaluating donanemab’s potential in delaying or preventing Alois Alzheimer in cognitively normal individuals with amyloid plaques, broadening the scope of early intervention strategies. (4) TRAILBLAZER-ALZ 4: A head-to-head comparison with aducanumab revealed superior amyloid plaque clearance with donanemab. (5) TRAILBLAZER-ALZ 5: Currently recruiting, this trial aims to evaluate safety and efficacy across diverse populations with varying tau levels and comorbidities. (6) TRAILBLAZER-ALZ 6 (Phase 3b): This trial investigates modified dosing regimens to reduce ARIA while maintaining efficacy, particularly in populations with genetic risk factors like ApoE ε4 homozygotes. Relevance to Patient Care and Clinical Practice: Donanemab-azbt represents a promising treatment option for patients with early-stage AD. It specifically targets and reduces amyloid beta plaques, a hallmark of the disease, potentially slowing progression and preserving cognitive function. However, its administration requires careful patient selection, including genetic testing for ApoE ε4 status, to mitigate risks of ARIA. Furthermore, the findings emphasize the importance of close monitoring during treatment. Conclusions: Donanemab-azbt offers a new avenue for managing early-stage AD, showing promise in reducing amyloid burden and slowing cognitive decline. While its efficacy and safety have been demonstrated in clinical trials, further research is essential to validate long-term outcomes, assess effectiveness across diverse populations, and refine dosing strategies to minimize side effects. With continued investigation, donanemab-azbt could significantly impact the clinical landscape of AD treatment. Full article

Background: Monoclonal antibodies approved by the FDA, lecanemab, donanemab, and aducanumab, are failing to meet the expected efficacy to treat early Alzheimer’s disease, and aducanumab has been recalled. Methods: Recently, it was reported that the clinical trials of these antibodies may have violated patient’s rights and subjected them to high, likely lethal risk. The challenge with developing antibodies to treat neurological disorders is their poor blood–brain barrier (BBB) penetration if the antibody must enter the brain, resulting in almost negligible brain bioavailability, requiring high dosing that can be toxic. Results: The reported efficacy of these drugs should also be reviewed, considering the placebo effects, since all antibodies have shown severe side effects that are not prevented by the placebo responses. In this critical and urgent advice to the FDA, I am suggesting a guideline amendment to all clinical trials requiring proof of sufficient brain bioavailability at the site of action, where it is known. Conclusions: For antibodies to cross the blood–brain barrier, there are proven options such as conjugating with transferrin protein, making clinical trials in its absence more questionable. Full article

The clinical spectrum of Alzheimer’s disease (AD) ranges dynamically from asymptomatic and mild cognitive impairment (MCI) to mild, moderate, or severe AD. Although a few disease-modifying treatments, such as lecanemab and donanemab, have been developed, current therapies can only delay disease progression rather than halt it entirely. Therefore, the early detection of MCI and the identification of MCI patients at high risk of progression to AD remain urgent unmet needs in the super-aged era. This study utilized transcriptomics data from cognitively unimpaired (CU) individuals, MCI, and AD patients in the Alzheimer’s Disease Neuroimaging Initiative (ADNI) cohort and leveraged machine learning models to identify biomarkers that differentiate MCI from CU and also distinguish AD from MCI individuals. Furthermore, Cox proportional hazards analysis was conducted to identify biomarkers predictive of the progression from MCI to AD. Our machine learning models identified a unique set of gene expression profiles capable of achieving an area under the curve (AUC) of 0.98 in distinguishing those with MCI from CU individuals. A subset of these biomarkers was also found to be significantly associated with the risk of progression from MCI to AD. A linear mixed model demonstrated that plasma tau phosphorylated at threonine 181 (pTau181) and neurofilament light chain (NFL) exhibit the prognostic value in predicting cognitive decline longitudinally. These findings underscore the potential of integrating machine learning (ML) with transcriptomic profiling in the early detection and prognostication of AD. This integrated approach could facilitate the development of novel diagnostic tools and therapeutic strategies aimed at delaying or preventing the onset of AD in at-risk individuals. Future studies should focus on validating these biomarkers in larger, independent cohorts and further investigating their roles in AD pathogenesis. Full article

Alzheimer’s Disease (AD) is an irreversible, progressive syndrome characterized by neurocognitive impairment. Two neuropathological features seen in AD are extracellular amyloid plaques consisting of amyloid beta1-40 and 1-42, and intracellular neurofibrillary tangles (NFTs). For decades, neuroscience research has heavily focused on seeking to understand the primary mechanism of AD and searching for pharmacological approaches for the treatment of dementia. Three monoclonal antibodies that act against amyloid beta—aducanumab, lecanemab, and donanemab—have been approved by the Food and Drug Administration (FDA) for the treatment of mild cognitive impairment and mild AD, in addition to medications for cognitive symptom management such as acetylcholinesterase inhibitors and the N-methyl-D-aspartate (NMDA) antagonist. Further trials should focus on the combination of therapies targeting amyloid plaques and tau pathology. Full article

Antibodies that can selectively remove rogue proteins in the brain are an obvious choice to treat neurodegenerative disorders (NDs), but after decades of efforts, only two antibodies to treat Alzheimer’s disease are approved, dozens are in the testing phase, and one was withdrawn, and the other halted, likely due to efficacy issues. However, these outcomes should have been evident since these antibodies cannot enter the brain sufficiently due to the blood–brain barrier (BBB) protectant. However, all products can be rejuvenated by binding them with transferrin, preferably as smaller fragments. This model can be tested quickly and at a low cost and should be applied to bapineuzumab, solanezumab, crenezumab, gantenerumab, aducanumab, lecanemab, donanemab, cinpanemab, and gantenerumab, and their fragments. This paper demonstrates that conjugating with transferrin does not alter the binding to brain proteins such as amyloid-β (Aβ) and α-synuclein. We also present a selection of conjugate designs that will allow cleavage upon entering the brain to prevent their exocytosis while keeping the fragments connected to enable optimal binding to proteins. The identified products can be readily tested and returned to patients with the lowest regulatory cost and delays. These engineered antibodies can be manufactured by recombinant engineering, preferably by mRNA technology, as a more affordable solution to meet the dire need to treat neurodegenerative disorders effectively. Full article

The recent setbacks in the withdrawal and approval delays of antibody treatments of neurodegenerative disorders (NDs), attributed to their poor entry across the blood–brain barrier (BBB), emphasize the need to bring novel approaches to enhance the entry across the BBB. One such approach is conjugating the antibodies that bind brain proteins responsible for NDs with the transferrin molecule. This glycoprotein transports iron into cells, connecting with the transferrin receptors (TfRs), piggybacking an antibody–transferrin complex that can subsequently release the antibody in the brain or stay connected while letting the antibody bind. This process increases the concentration of antibodies in the brain, enhancing therapeutic efficacy with targeted delivery and minimum systemic side effects. Currently, this approach is experimented with using drug-transferring conjugates assembled in vitro. Still, a more efficient and safer alternative is to express the conjugate using mRNA technology, as detailed in this paper. This approach will expedite safer discoveries that can be made available at a much lower cost than the recombinant process with in vitro conjugation. Most importantly, the recommendations made in this paper may save the antibodies against the NDs that seem to be failing despite their regulatory approvals. Full article

The amyloid cascade hypothesis for Alzheimer’s disease is still alive, although heavily challenged. Effective anti-amyloid immunotherapy would confirm the hypothesis’ claim that the protein amyloid-beta is the cause of the disease. Two antibodies, aducanumab and lecanemab, have been approved by the U.S. Food and Drug Administration, while a third, donanemab, is under review. The main argument for the FDA approvals is a presumed therapy-induced removal of cerebral amyloid deposits. Lecanemab and donanemab are also thought to cause some statistical delay in the determination of cognitive decline. However, clinical efficacy that is less than with conventional treatment, selection of amyloid-positive trial patients with non-specific amyloid-PET imaging, and uncertain therapy-induced removal of cerebral amyloids in clinical trials cast doubt on this anti-Alzheimer’s antibody therapy and hence on the amyloid hypothesis, calling for a more thorough investigation of the negative impact of this type of therapy on the brain. Full article

New data suggest that the aggregation of misfolded native proteins initiates and drives the pathogenic cascade that leads to Alzheimer’s disease (AD) and other age-related neurodegenerative disorders. We propose a unifying single toxin theory of brain neurodegeneration that identifies new targets and approaches to the development of disease-modifying treatments. An extensive body of genetic evidence suggests soluble aggregates of beta-amyloid (Aβ) as the primary neurotoxin in the pathogenesis of AD. New insights from fluid biomarkers, imaging, and clinical studies provide further evidence for the decisive impact of toxic Aβ species in the initiation and progression of AD. Understanding the distinct roles of soluble and insoluble amyloid aggregates on AD pathogenesis has been the key missing piece of the Alzheimer’s puzzle. Data from clinical trials with anti-amyloid agents and recent advances in the diagnosis of AD demonstrate that the driving insult in biologically defined AD is the neurotoxicity of soluble Aβ aggregates, called oligomers and protofibrils, rather than the relatively inert insoluble mature fibrils and amyloid plaques. Amyloid oligomers appear to be the primary factor causing the synaptic impairment, neuronal stress, spreading of tau pathology, and eventual cell death that lead to the clinical syndrome of AD dementia. All other biochemical effects and neurodegenerative changes in the brain that are observed in AD are a response to or a downstream effect of this initial toxic insult by oligomers. Other neurodegenerative disorders follow a similar pattern of pathogenesis, in which normal brain proteins with important biological functions become trapped in the aging brain due to impaired clearance and then misfold and aggregate into neurotoxic species that exhibit prion-like behavior. These aggregates then spread through the brain and cause disease-specific neurodegeneration. Targeting the inhibition of this initial step in neurodegeneration by blocking the misfolding and aggregation of healthy proteins has the potential to slow or arrest disease progression, and if treatment is administered early in the course of AD and other neurodegenerative disorders, it may delay or prevent the onset of clinical symptoms. Full article

Over the past 30 years, the majority of (pre)clinical efforts to find an effective therapy for Alzheimer’s disease (AD) focused on clearing the β-amyloid peptide (Aβ) from the brain since, according to the amyloid cascade hypothesis, the peptide was (and it is still considered by many) the pathogenic determinant of this neurodegenerative disorder. However, as reviewed in this article, results from the numerous clinical trials that have tested anti-Aβ therapies to date indicate that this peptide plays a minor role in the pathogenesis of AD. Indeed, even Aducanumab and Lecanemab, the two antibodies recently approved by the FDA for AD therapy, as well as Donanemab showed limited efficacy on cognitive parameters in phase III clinical trials, despite their capability of markedly lowering Aβ brain load. Furthermore, preclinical evidence demonstrates that Aβ possesses several physiological functions, including memory formation, suggesting that AD may in part be due to a loss of function of this peptide. Finally, it is generally accepted that AD could be the result of many molecular dysfunctions, and therefore, if we keep chasing only Aβ, it means that we cannot see the forest for the trees. Full article

In June 2021, the US Federal Drug and Food Administration (FDA) granted accelerated approval for the antibody aducanumab and, in January 2023, also for the antibody lecanemab, based on a perceived drug-induced removal of cerebral amyloid-beta as assessed by amyloid-PET and, in the case of lecanemab, also a presumption of limited clinical efficacy. Approval of the antibody donanemab is awaiting further data. However, published trial data indicate few, small and uncertain clinical benefits, below what is considered “clinically meaningful” and similar to the effect of conventional medication. Furthermore, a therapy-related decrease in the amyloid-PET signal may also reflect increased cell damage rather than simply “amyloid removal”. This interpretation is more consistent with increased rates of amyloid-related imaging abnormalities and brain volume loss in treated patients, relative to placebo. We also challenge the current diagnostic criteria for AD based on amyloid-PET imaging biomarkers and recommend that future anti-AD therapy trials apply: (1) diagnosis of AD based on the co-occurrence of cognitive decline and decreased cerebral metabolism assessed by FDA-approved FDG-PET, (2) therapy efficacy determined by favorable effect on cognitive ability, cerebral metabolism by FDG-PET, and brain volumes by MRI, and (3) neuropathologic examination of all deaths occurring in these trials. Full article