Anti-amyloid ß Antibody Therapies for Alzheimer's Disease: Association between the Target of Amyloid ß Aggregates and the Clinical Efficacy of Anti-amyloid ß Antibody.

Phase 3 clinical trials have validated the clinical efficacy of some anti-amyloid ß (Aß) antibody therapies, such as lecanemab and donanemab. To date, several clinical trials of anti-Aß drugs have been conducted. However, most of these methods have been unsuccessful. Various Aß aggregates are present during Aß aggregation. The difference in the clinical efficacy of anti-Aß antibody therapy may be attributed to variations in the Aß aggregates targeted. Lecanemab primarily targets protofibrils, and donanemab targets plaques. Solanezumab and bapinezumab target Aß aggregates of monomers alone or from monomers to low molecular weight oligomers. Anti-Aß antibody therapies with clinical cognitive efficacy are thus characterized by targeting large-molecular-weight Aß aggregates, such as protofibrils and plaques. In addition, a positive association was observed between the reduction in amyloid deposition and the inhibition of cognitive decline.

Estimating the Economically Justifiable Price of Limited-Duration Treatment with Donanemab for Early Symptomatic Alzheimer's Disease in the United States.

INTRODUCTION: The goal of this economic model is to estimate an economically justifiable price (EJP) for using donanemab for the treatment of early symptomatic Alzheimer's disease (AD) in the United States based on clinical data from the phase 3 TRAILBLAZER-ALZ 2 trial (NCT04437511). METHODS: We adapted an AD Markov state-transition model developed by the Institute for Clinical and Economic Review to estimate the EJP for donanemab at different willingness-to-pay (WTP) thresholds from the health care system perspective and the societal perspective as co-base cases. RESULTS: Assuming a WTP threshold of $150,000 per quality-adjusted life-year (QALY) gained, the model estimates a 1-year (13-dose) EJP for donanemab of $80,538 from the health care system perspective and $91,126 from the societal perspective; at a WTP threshold of $100,000 per QALY gained, the model estimates a 1-year (13-dose) EJP for donanemab of $44,691 from the health care system perspective and $55,419 from the societal perspective. Mean total treatment costs per patient at the $150,000 per QALY gained EJP derived from the health care system perspective were estimated at $77,812 based on the average number of doses of donanemab patients received in the co-base case analysis. One-way sensitivity analysis (OWSA) indicated that treatment efficacy, disease severity at the time of treatment initiation, and duration of treatment effect were the main drivers of the potential EJP. CONCLUSIONS: Results from this modeling simulation informed by the TRAILBLAZER-ALZ 2 study support an EJP for limited-duration treatment with donanemab that exceeds per-dose list prices for currently available amyloid-targeting therapies, implying potentially lower lifetime costs and better value for money.

What's in It for Me? Contextualizing the Potential Clinical Impacts of Lecanemab, Donanemab, and Other Anti-ß-amyloid Monoclonal Antibodies in Early Alzheimer's Disease.

A new era of disease-modifying therapy for Alzheimer's disease (AD) arrived in 2021 following the Food and Drug Administration's (FDA) decision to grant accelerated approval for aducanumab, an anti-ß-amyloid (Aß) monoclonal antibody designed to target Aß aggregates, a biological component of AD. More recently, trial outcomes for lecanemab and donanemab, two additional antibodies of this drug class, have shown favorable and significant slowing of metrics for cognitive and functional decline. Lecanemab and donanemab have since received similar FDA approval to aducanumab in January 2023 and July 2024, respectively. Given that these therapies are a clearly emerging tool in the repertoire of clinicians treating AD and related dementias, a critical dialogue has been ongoing regarding the potential impacts and place for these therapies. Here, we seek to contextualize this debate by first considering factors involved in theoretically extrapolating current randomized control trial outcomes to estimate meaningful clinical impacts. In the process of this exercise, we outline a generally useful concept termed Summative Treatment-Associated Benefit measuring Long-term Efficacy/Effectiveness Area as a metric of summative benefits of treatment over the life course of an individual. Second, we consider current real-world factors, such as conditions of FDA approval and other points involved in clinical decision-making that will influence and/or temper the actual impacts of this drug class.

Cancer research provides a model for advancing clinical trials in dementia in the era of disease-modifying Alzheimer's-type dementia therapies.

Dementia and cancer are multifactorial, widely-feared, age-associated clinical syndromes that are increasing in prevalence. There have been major breakthroughs in clinical cancer research leading to some effective treatments, whereas the field of dementia has achieved comparatively limited success in clinical research. The lessons of cancer research may help those in the dementia research field in confronting some of the dilemmas faced when the clinical care regimen is not entirely safe or efficacious. Cancer clinical trials have assumed that untreated individuals with cancer are at high risk for morbidity and mortality after primary diagnoses. Thus, patients deserve a choice of clinical interventions, either standard of care or experimental, even if the benefits are not certain and the therapy's side effects are potentially severe. The prognosis for many individuals at risk for dementia carries a correspondingly high level of risk for both mortality and severe morbidity, particularly if one focuses on "health-span" rather than lifespan. Caregivers and patients can be strongly impacted by dementia and the many troubling associated symptoms that often go well beyond amnesia. Polls, surveys, and a literature on "dementia worry" strongly underscore that the public fears dementia. While there are institutional and industry hurdles that complicate enrollment in randomized trials, the gravity of the future morbidity and mortality inherent in a dementia diagnosis may require reconsideration of the current protective stance that limits the freedom of at-risk individuals (either symptomatic or asymptomatic) to participate and potentially benefit from ongoing clinical research. There is also evidence from both cancer and dementia research that individuals enrolled in the placebo arms of clinical trials have unexpectedly good outcomes, indicating that participation in clinical trial can have medical benefits to enrollees. To highlight aspects of cancer clinical research that may inform present and future dementia clinical research, this review highlights three main themes: the risk of side effects should be weighed against the often dire consequences of non-treatment; the desirability of long-term incremental (rather than "magic bullet") clinical advances; and, the eventual importance of combination therapies, reflecting that the dementia clinical syndrome has many underlying biological pathways.

Novel Blood-Based Biomarkers and Disease Modifying Therapies for Alzheimer's Disease. Are We Ready for the New Era?

Recent positive trials for novel disease modifying therapies of anti-amyloid monoclonal antibodies represent a paradigm shift in the prevention and management of Alzheimer's disease, a relentlessly progressive and debilitating disease of old age. The reported efficacy of these new agents when given early in the disease trajectory is dependent on an early and accurate disease diagnosis, which is currently based on cerebrospinal fluid tests or/and neuro-imaging studies such as positron emission tomography. These confirmatory tests provide in vivo evidence of the pathological signature of Alzheimer's disease, of increased cerebral amyloid and tau burden and neurodegeneration. The emergence of blood-based biomarkers represents another breakthrough, offering a less invasive and scalable diagnostic tool that could be applied in both primary and specialist care settings, potentially revolutionizing Alzheimer's disease clinical pathways. However, healthcare systems face challenges in the adoption of these new technologies and therapies due to diagnostic and treatment capacity constraints, as well as financial and infrastructure requirements.

Donanemab, another anti-Alzheimer's drug with risk and uncertain benefit.

Based on "reducing amyloid plaques in the brain", the U.S. Food and Drug Administration has granted accelerated and full approval for two monoclonal anti-Alzheimer's antibodies, aducanumab and lecanemab, respectively. Approval of a third antibody, donanemab, is pending. Moreover, lecanemab and donanemab are claimed to cause delay in the cognitive decline that characterizes the disease. We believe that these findings are subject to misinterpretation and statistical bias. Donanemab is claimed to cause removal of up to 86 % of cerebral amyloid and 36 % delay in cognitive decline compared to placebo. In reality, these are very small changes on an absolute scale and arguably less than what can be achieved with cholinesterase inhibitor/memantine therapy. Moreover, the "removal" of amyloid, based on the reduced accumulation of amyloid-PET tracer, most likely also reflects therapy-related tissue damage. This would also correlate with the minimal clinical effect, the increased frequency of amyloid-related imaging abnormalities, and the accelerated loss of brain volume in treated compared to placebo patients observed with these antibodies. We recommend halting approvals of anti-AD antibodies until these issues are fully understood to ensure that antibody treatment does not cause more harm than benefit to patients.

Pharmacokinetic evaluation of donanemab for the treatment of Alzheimer's.

INTRODUCTION: Donanemab is a humanized monoclonal antibody that significantly reduces cerebral amyloid plaques in Alzheimer's Disease (AD). It can delay disease progression and cognitive decline, making it one of the most promising disease-modifying treatments in the current treatment landscape. AREAS COVERED: This paper covers the current literature available on pharmacokinetics, pharmacodynamics, safety, and tolerability of donanemab. Publications from PubMed and Google were reviewed. A summary of regulatory approvals and current clinical data is also provided. EXPERT OPINION/COMMENTARY: Donanemab as a therapy for AD has more effective disease-modifying effects compared to lecanemab. Donanemab appears generally well-tolerated; however, it may have higher rates of severe side effects, such as amyloid-related imaging abnormalities (ARIA), that could lead to death. Guidelines for frequency of MRI monitoring for ARIA/safety are pending but will be integral to determining its use. Despite some limitations, donanemab is expected to receive FDA approval, giving clinicians access to another disease-modifying drug. Overall, more data is needed about donanemab, especially relating to safety, efficacy, cost, and integration with other treatments, but its development signifies progress in AD treatment.

Alzheimer's Disease (AD) is a brain disorder that severely impacts memory, behavior, and thinking. The most common treatments manage symptoms but do not slow disease progression or improve function. Accumulation of proteins called amyloid-beta plaques in the brain are one of the main causes of the disease. Donanemab is an antibody that helps the body remove these plaques. This review summarizes what is currently known about the safety of donanemab, how it works, and the extent to which it can help people with AD.Results suggest that donanemab significantly decreases the amount of plaques in the brain, delays disease progression, and improves cognition. Treatment can prevent reaccumulation of plaques for an extended period of time. There are some side effects associated with treatment, but they are generally manageable and resolve when the drug is stopped. In rare cases, more serious side effects were reported. These require careful monitoring and an evaluation of potential risk compared to benefit. Overall, current information on donanemab is extensive and shows promise. However, to help caregivers and people with AD make informed decisions on using the drug, further research is needed to fully explore donanemab's safety, cost, and efficacy compared to other therapies in the same class.

Donanemab in Japanese Patients with Early Alzheimer's Disease: Subpopulation Analysis of the TRAILBLAZER-ALZ 2 Randomized Trial.

INTRODUCTION: Donanemab, a monoclonal antibody directed against an insoluble, modified, N-terminal truncated form of amyloid beta, demonstrated efficacy and safety in patients with early, symptomatic Alzheimer's disease (AD) in the phase 3 TRAILBLAZER-ALZ 2 trial. Here, we report clinical outcomes, biomarkers, and safety results for the Japanese subpopulation. METHODS: TRAILBLAZER-ALZ 2 (N = 1736) was conducted in eight countries, including Japan (enrollment June 2020-November 2021; database lock April 2023). Participants (60-85 years) with early, symptomatic AD (mild cognitive impairment/mild dementia), Mini-Mental State Examination score 20-28, and confirmed amyloid and tau pathology were randomized 1:1 (stratified by tau status) to intravenous donanemab (700 mg for three doses, then 1400 mg/dose) or placebo every 4 weeks for 72 weeks. Primary outcome was change from baseline to week 76 in integrated Alzheimer's Disease Rating Scale (iADRS) score. Other outcomes included clinical measures of cognitive and functional impairment, biomarkers, and safety. RESULTS: Of 88 Japanese participants (43 placebo, 45 donanemab), 7 in each group discontinued. Least-squares mean (LSM) change from baseline in iADRS score at week 76 was smaller with donanemab than with placebo in the combined (low-medium tau and high tau) and low-medium tau (N = 76) subpopulations (LSM change difference: 4.43 and 3.99, representing 38.8% and 40.2% slowing of disease progression, respectively). Slowing of AD progression with donanemab was also observed for other clinical outcomes. Marked decreases in amyloid plaque and plasma phosphorylated tau 217 were observed; amyloid clearance (< 24.1 Centiloids) was observed in 83.3% of the combined donanemab and 0% of the combined placebo groups. Amyloid-related imaging abnormalities of edema/effusions occurred in ten (22.2%) donanemab-treated participants (one [2.2%] symptomatic) and one (2.3%) placebo-treated participant. CONCLUSIONS: The overall efficacy and safety of donanemab in Japanese participants were similar to the global TRAILBLAZER-ALZ 2 population. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT04437511.

Transcytosis-Driven Treatment of Neurodegenerative Disorders by mRNA-Expressed Antibody-Transferrin Conjugates.

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.

Profiling lecanemab as a treatment option for Alzheimer's disease.

INTRODUCTION: In July 2023, the U.S. Food and Drug Administration (FDA) granted full approval to lecanemab for the treatment of mild cognitive impairment (MCI) due to Alzheimer's disease (AD) and mild AD dementia. Considering the limited treatment options for AD, the approval of lecanemab offers hope and opens the door for other disease-modifying therapies in the pipeline. AREAS COVERED: In this review, the authors summarize the FDA treatment guidelines, other anti-amyloid agents, and drug information relevant to prescribers, such as pharmacology and pharmacokinetics. Relevant clinical trial outcomes are discussed along with their significance and controversies. EXPERT OPINION: While questions remain about the magnitude of lecanemab's clinical impact, its approval signifies major progress in addressing the underlying pathology of AD. The authors have confidence in lecanemab as a promising treatment option and foresee exciting advancements on the 5-year horizon. Yet, further research is needed regarding trials beyond 18 months, post-marketing surveillance, and lecanameb in combination with existing treatments and lifestyle interventions.

Comparative Efficacy, Tolerability, and Acceptability of Donanemab, Lecanemab, Aducanumab, Melatonin, and Aerobic Exercise for a Short Time on Cognitive Function in Mild Cognitive Impairment and Mild Alzheimer's Disease: A Systematic Review and Network Meta-Analysis.

Background: The Food and Drug Administration (FDA) has approved lecanemab and aducanumab and is reviewing donanemab, but they have questionable efficacy, serious side effects and are costly, whereas melatonin administration and aerobic exercise for a short time may overcome these problems. Objective: We aim to compare the efficacy on cognitive function, tolerability and acceptability of melatonin administration and aerobic exercise for a short time with donanemab, lecanemab, and aducanumab in people with mild AD and MCI. Methods: We systematically reviewed relevant randomized placebo-controlled trials (RCTs) in PubMed, the Cochrane Library, CINHAL, and ClinicalTrials.gov and performed network meta-analyses. Results: The analysis included 10 randomized placebo-controlled trials with 4,599 patients. Although melatonin and aerobic exercise for a short time were significantly more effective than donanemab, lecanemab, aducanumab and placebo in the primary analysis, there was significant heterogeneity. In the sensitivity analysis excluding exercise, melatonin was significantly more effective than donanemab, lecanemab, aducanumab and placebo, with no significant heterogeneity. Aerobic exercise for a short time was significantly less acceptable than donanemab, aducanumab and placebo. Donanemab, lecanemab, and aducanumab were significantly less tolerable than placebo and donanemab and lecanemab were significantly less acceptable than placebo. CONCLUSIONS: Melatonin may be a better potential disease-modifying treatment for cognitive decline in mild AD and MCI. Aerobic exercise for a short time might also be better than donanemab, lecanemab and aducanumab if continued, as it is well tolerated and more effective, although less valid due to heterogeneity. Another limitation is the small number of participants.

The Single Toxin Origin of Alzheimer's Disease and Other Neurodegenerative Disorders Enables Targeted Approach to Treatment and Prevention.

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 (Aß) 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 Aß 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 Aß 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.

How donanemab data address the coverage with evidence development questions.

The Centers for Medicare & Medicaid Services (CMS) established a class-based National Coverage Determination (NCD) for monoclonal antibodies directed against amyloid for Alzheimer's disease (AD) with patient access through Coverage with Evidence Development (CED) based on three questions. This review, focused on donanemab, answers each of these CED questions with quality evidence. TRAILBLAZER-ALZ registration trials are presented with supporting literature and real-world data to answer CED questions for donanemab. TRAILBLAZER-ALZ registration trials demonstrated that donanemab significantly slowed cognitive and functional decline in amyloid-positive early symptomatic AD participants, and lowered their risk of disease progression while key safety risks occurred primarily within the first 6 months and then declined. Donanemab meaningfully improved health outcomes with a manageable safety profile in an early symptomatic AD population, representative of Medicare populations across diverse practice settings. The donanemab data provide the necessary level of evidence for CMS to open a reconsideration of their NCD. HIGHLIGHTS: Donanemab meaningfully improved outcomes in trial participants with early symptomatic Alzheimer's disease. Comorbidities in trial participants were consistent with the Medicare population. Co-medications in trial participants were consistent with the Medicare population. Risks associated with treatment tended to occur in the first 6 months. Risks of amyloid-related imaging abnormalities were managed with careful observation and magnetic resonance imaging monitoring.

Comparative efficacy, tolerability and acceptability of donanemab, lecanemab, aducanumab and lithium on cognitive function in mild cognitive impairment and Alzheimer's disease: A systematic review and network meta-analysis.

BACKGROUND: The comparative clinical utility of the disease-modifying treatments for mild cognitive impairment and Alzheimer's disease that are approved or under review by the Food and Drug Administration (i.e., donanemab, lecanemab and aducanumab), and lithium, which is a potential disease-modifying agent for this condition, remains elusive. OBJECTIVE: We aimed to compare the efficacy on cognitive decline, tolerability and acceptability of these drugs in this condition. METHODS: We systematically searched in MEDLINE, CENTRAL, CINHAL and ClinicalTrials,gov for randomized controlled trials from their inception to 7 November 2023, and then performed a random-effect network meta-analysis. RESULTS: The analysis included 8 randomized placebo-controlled trials with 6547 participants. On the Mini-Mental State Examination, lithium significantly outperformed donanemab, aducanumab and placebo. On the Alzheimer's Disease Assessment Scale-cognitive subscale, the efficacy of all active drugs was significantly higher than placebo. In addition, in the Clinical Dementia Rating sum of boxes, the efficacy of donanemab and lecanemab was significantly higher than placebo. Compared to placebo, donanemab and lecanemab were significantly less acceptable and tolerable. Aducanumab was also less well tolerated compared to placebo. There were no significant differences in the other comparisons. CONCLUSION: Although it is yet to be determined which is more effective between lithium or lecanemab or donanemab, lithium may be more effective than aducanumab. Aducanumab, lecanemab and donanemab do not appear to differ in their effectiveness on cognitive function. Low-dose lithium may be safer than aducanumab, lecanemab and donanemab.

How promising are the latest monoclonal antibodies targeting amyloid-ß for the treatment of early Alzheimer's disease?

INTRODUCTION: Monoclonal antibodies targeting amyloid-ß are the first disease-modifying treatments for Alzheimer disease to have received FDA-approval. There are three different drugs approved or pending FDA-approval: aducanumab, lecanemab, and donanemab. These three drugs are each in different stages of regulatory approval by the FDA. AREAS COVERED: We discuss the development of these drugs, the data regarding their clinical efficacy, their dosing regimens, and side effects. In addition, we examine pragmatic issues with their potential implementation as common treatments to slow the rate of decline in Alzheimer disease, and what unanswered questions remain regarding this new class of drugs. EXPERT OPINION: We conclude that these new monoclonal antibodies that target amyloid-ß represent a genuine advance in the treatment of Alzheimer disease. However, questions remain regarding their clinical significance. Additionally, it is presently unclear which patients would most benefit from these expensive drugs given the risk of side effects and the logistical difficulties concerning administration and the determination of eligibility.

Clinically Important Benefits and Harms of Monoclonal Antibodies Targeting Amyloid for the Treatment of Alzheimer Disease: A Systematic Review and Meta-Analysis.

PURPOSE: We conducted a meta-analysis to evaluate clinically meaningful benefits and harms of monoclonal antibodies targeting amyloid in patients with Alzheimer dementia. METHODS: We searched PubMed, Cochrane CENTRAL, and 5 trial registries, as well as the reference lists of identified studies. We included randomized controlled trials comparing a monoclonal antibody with placebo at a dose consistent with that used in phase 3 trials or for Food and Drug Administration approval. Studies had to report at least 1 clinically relevant benefit or harm. Data were extracted independently by at least 2 researchers for random effects meta-analysis. Changes in cognitive and functional scales were compared between groups, and each difference was assessed to determine if it met the minimal clinically important difference (MCID). RESULTS: We identified 19 publications with 23,202 total participants that evaluated 8 anti-amyloid antibodies. There were small improvements over placebo in the Alzheimer's Disease Assessment Scale (ADAS)-Cog-11 to -14 score (standardized mean difference = -0.07; 95% CI, -0.10 to -0.04), Mini Mental State Examination score (0.32 points; 95% CI, 0.13 to 0.50), and Clinical Dementia Rating-Sum of Boxes scale score (mean difference =-0.18 points; 95% CI, -0.34 to -0.03), and the combined functional scores (standardized mean difference = 0.09; 95% CI, 0.05 to 0.13). None of the changes, including those for lecanemab, aducanumab, and donanemab, exceeded the MCID. Harms included significantly increased risks of amyloid-related imaging abnormalities (ARIA)-edema (relative risk [RR] = 10.29; number needed to harm [NNH] = 9), ARIA-hemorrhage (RR = 1.74; NNH = 13), and symptomatic ARIA-edema (RR = 24.3; NNH = 86). CONCLUSIONS: Although monoclonal antibodies targeting amyloid provide small benefits on cognitive and functional scales in patients with Alzheimer dementia, these improvements are far below the MCID for each outcome and are accompanied by clinically meaningful harms.