Effects of the active amyloid beta immunotherapy CAD106 on PET measurements of amyloid plaque deposition in cognitively unimpaired APOE ε4 homozygotes.

INTRODUCTION: Alzheimer's Prevention Initiative Generation Study 1 evaluated amyloid beta (Aß) active immunotherapy (vaccine) CAD106 and BACE-1 inhibitor umibecestat in cognitively unimpaired 60- to 75-year-old participants at genetic risk for Alzheimer's disease (AD). The study was reduced in size and terminated early. Results from the CAD106 cohort are presented. METHODS: Sixty-five apolipoprotein E ε4 homozygotes with/without amyloid deposition received intramuscular CAD106 450 µg (n = 42) or placebo (n = 23) at baseline; Weeks 1, 7, 13; and quarterly; 51 of them had follow-up Aß positron emission tomography (PET) scans at 18 to 24 months. RESULTS: CAD106 induced measurable serum Aß immunoglobulin G titers in 41/42 participants, slower rates of Aß plaque accumulation (mean [standard deviation] annualized change from baseline in amyloid PET Centiloid: -0.91[5.65] for CAD106 versus 8.36 [6.68] for placebo; P < 0.001), and three amyloid-related imaging abnormality cases (one symptomatic). DISCUSSION: Despite early termination, these findings support the potential value of conducting larger prevention trials of Aß active immunotherapies in individuals at risk for AD. HIGHLIGHTS: This was the first amyloid-lowering prevention trial in persons at genetic risk of late-onset Alzheimer's disease (AD). Active immunotherapy targeting amyloid (CAD106) was tested in this prevention trial. CAD106 significantly slowed down amyloid plaque deposition in apolipoprotein E homozygotes. CAD106 was generally safe and well tolerated, with only three amyloid-related imaging abnormality cases (one symptomatic). Such an approach deserves further evaluation in larger AD prevention trials.

Reversibility of cognitive worsening observed with BACE inhibitor umibecestat in the Alzheimer's Prevention Initiative (API) Generation Studies.

INTRODUCTION: The Alzheimer's Prevention Initiative (API) Generation Studies evaluated the BACE inhibitor umibecestat for Alzheimer's disease (AD) prevention. The studies were terminated early, and the reversibility of umibecestat's side effects was assessed. METHODS: Cognitively unimpaired 60- to 75-year-old apolipoprotein E (APOE) Îµ4 homozygotes and heterozygotes (the latter with elevated brain amyloid deposition) (n = 1556) received umibecestat (50 or 15 mg daily) or placebo for 7 months on average and were followed for a median (interquartile range) of 4 (3 to 6) months after washout. RESULTS: Compared to placebo, umibecestat-treated participants had small, non-progressive, but statistically significant decline in performance on certain cognitive batteries including Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and API Preclinical Composite Cognitive test, but not Clinical Dementia Rating-Sum of Boxes. RBANS differences were no longer significant at the end of follow-up. DISCUSSION: In people at genetic risk for AD, high-dose beta-site amyloid precursor protein cleaving enzyme (BACE) inhibition was associated with early mild cognitive worsening, which reversed shortly after washout, suggesting a symptomatic side effect not associated with neurodegeneration. Fully anonymized data, images, and samples are available upon request for further research on BACE inhibition. HIGHLIGHTS: This is the first trial with blinded assessment of reversibility of BACE inhibitor side effects. Umibecestat was tested in cognitively unimpaired persons at genetic risk for AD. Umibecestat led to early mild cognitive decline that reversed shortly after washout. This suggests a potentially manageable effect not associated with neurodegeneration. Further research may determine the future of BACE inhibition in AD prevention.

Revised criteria for diagnosis and staging of Alzheimer's disease: Alzheimer's Association Workgroup.

The National Institute on Aging and the Alzheimer's Association convened three separate work groups in 2011 and single work groups in 2012 and 2018 to create recommendations for the diagnosis and characterization of Alzheimer's disease (AD). The present document updates the 2018 research framework in response to several recent developments. Defining diseases biologically, rather than based on syndromic presentation, has long been standard in many areas of medicine (e.g., oncology), and is becoming a unifying concept common to all neurodegenerative diseases, not just AD. The present document is consistent with this principle. Our intent is to present objective criteria for diagnosis and staging AD, incorporating recent advances in biomarkers, to serve as a bridge between research and clinical care. These criteria are not intended to provide step-by-step clinical practice guidelines for clinical workflow or specific treatment protocols, but rather serve as general principles to inform diagnosis and staging of AD that reflect current science. HIGHLIGHTS: We define Alzheimer's disease (AD) to be a biological process that begins with the appearance of AD neuropathologic change (ADNPC) while people are asymptomatic. Progression of the neuropathologic burden leads to the later appearance and progression of clinical symptoms. Early-changing Core 1 biomarkers (amyloid positron emission tomography [PET], approved cerebrospinal fluid biomarkers, and accurate plasma biomarkers [especially phosphorylated tau 217]) map onto either the amyloid beta or AD tauopathy pathway; however, these reflect the presence of ADNPC more generally (i.e., both neuritic plaques and tangles). An abnormal Core 1 biomarker result is sufficient to establish a diagnosis of AD and to inform clinical decision making throughout the disease continuum. Later-changing Core 2 biomarkers (biofluid and tau PET) can provide prognostic information, and when abnormal, will increase confidence that AD is contributing to symptoms. An integrated biological and clinical staging scheme is described that accommodates the fact that common copathologies, cognitive reserve, and resistance may modify relationships between clinical and biological AD stages.

Mavoglurant in Parkinson's patients with l-Dopa-induced dyskinesias: Two randomized phase 2 studies.

BACKGROUND: Two phase 2 randomized, double-blind studies were designed to evaluate efficacy and safety of immediate-release (study 1) and modified-release (study 2) mavoglurant formulations in PD l-dopa-induced dyskinesia. METHODS: Patients were randomized to mavoglurant 100-mg or placebo (4:3) groups (study 1) and mavoglurant 200-mg, mavoglurant 150-mg, or placebo (2:1:1) groups (study 2). Primary outcome was antidyskinetic efficacy, as measured by change from baseline to week 12 in modified Abnormal Involuntary Movement Scale total score. RESULTS: Differences in least-squares mean (standard error) change in modified Abnormal Involuntary Movement Scale total score in week 12 did not reach statistical significance in either study (study 1: mavoglurant 100 mg twice a day versus placebo, 1.7 [1.31]; study 2: mavoglurant 150 mg twice a day (-1.3 [1.16]) and 200 mg twice a day (-0.2 [1.03]) versus placebo). Adverse events incidence was higher with mavoglurant than with placebo. CONCLUSIONS: Both studies failed to meet the primary objective of demonstrating improvement of dyskinesia with mavoglurant treatment. © 2016 International Parkinson and Movement Disorder Society.

Mavoglurant (AFQ056) in combination with increased levodopa dosages in Parkinson's disease patients.

Long-term use of levodopa (L-dopa) in patients with Parkinson's disease is associated with development of dyskinesia. This study explored whether Parkinson's disease patients with L-dopa-induced dyskinesia experience improved OFF-time from higher L-dopa doses without worsening of dyskinesias when receiving adjunctive mavoglurant. Patients with moderate-to-severe L-dopa-induced dyskinesia were randomized to receive mavoglurant or placebo. Mavoglurant (AFQ056) was up-titrated over two weeks from 25 mg twice daily (bid) to 100 mg bid (L-dopa kept stable), followed by three weeks during which the daily L-dopa dosage was increased by up to 300 mg/day. A sample size of 30 was initially planned; however, the study was terminated prematurely due to enrollment challenges. OFF-time showed greater improvements in the mavoglurant group (n = 7) compared with the placebo group (n = 7); difference at week 5 was -2.77 h (90% confidence interval -5.44, -0.09 h; p = 0.09). ON-time without troublesome dyskinesia increased more from baseline to week 5 in the mavoglurant group (4.38 h) versus the placebo group (0.63 h). Clinician-rated measures were conflicting. The Modified Abnormal Involuntary Movement Scale scores showed a slight improvement with mavoglurant compared with placebo, while the Unified Dyskinesia Rating Scale parts III and IV worsened slightly with mavoglurant compared with placebo. Due to the low patient numbers and conflicting clinician-rated outcomes data, our findings are not conclusive. However, our results suggest that mavoglurant combined with higher doses of L-dopa may be effective in treating patients with Parkinson's disease experiencing L-dopa-related motor fluctuations and dyskinesias.

AFQ056 in Parkinson patients with levodopa-induced dyskinesia: 13-week, randomized, dose-finding study.

AFQ056 is a novel, selective metabotropic glutamate receptor 5 antagonist. This was a 13-week, double-blind, placebo-controlled study. Patients with Parkinson's disease and moderate-to-severe levodopa (l-dopa)-induced dyskinesia who were receiving stable l-dopa/anti-parkinsonian treatment and were not currently receiving amantadine were randomized to receive either AFQ056 (at doses of 20, 50, 100, 150, or 200 mg daily) or placebo (1:1:1:1:2:3 ratio) for 12 weeks. The primary outcome was the modified Abnormal Involuntary Movements Scale. Secondary outcomes included the 26-item Parkinson's Disease Dyskinesia Scale, the Patient's/Clinician's Global Impression of Change, and the Unified Parkinson's Disease Rating Scale parts III (motor evaluation) and IV (severity of motor complications). Safety was assessed. In total, 98 of 133 (73.7%) AFQ056-treated patients and 47 of 64 (73.4%) patients in the placebo group completed the study. Baseline characteristics were comparable. Patients randomized to AFQ056 200 mg daily administered in 2 doses demonstrated significant improvements at Week 12 on the modified Abnormal Involuntary Movements Scale compared with placebo (difference, -2.8; 95% confidence interval [CI], -5.2, -0.4; P = 0.007). Based on final actual doses, there was a dose-response relationship on the modified Abnormal Involuntary Movements Scale, with 200 mg daily demonstrating the most robust effect (difference, -3.6; 95% CI, -7.0, -0.3; P = 0.012). Improvements in dyskinesia were supported by change on Unified Parkinson's Disease Rating Scale part IV item 32 (50 mg daily: difference, -0.7; 95% CI, -1.1, -0.2; P = 0.003; 200 mg daily: difference, -0.5; 95% CI, -0.8, -0.1; P = 0.005). No significant changes were observed on the 26-item Parkinson's Disease Dyskinesia Scale, the Unified Parkinson's Disease Rating Scale part IV item 33 or items 32 and 33, or the Patient's/Clinician's Global Impression of Change. Unified Parkinson's Disease Rating Scale part III scores were not significantly changed, indicating no worsening of motor symptoms. The most common adverse events (with incidence greater with AFQ056 than with placebo) were dizziness, hallucination, fatigue, nasopharyngitis, diarrhea, and insomnia. AFQ056 demonstrated anti-dyskinetic efficacy in this population without worsening underlying motor symptoms. These results will guide dose selection for future clinical trials.

Operationalizing selection criteria for clinical trials in Alzheimer's disease: Biomarker and clinical considerations.

Alzheimer's disease (AD) staging criteria lack standardized, empirical description. Well-defined AD staging criteria are an important consideration in protocol design, influencing a more standardized inclusion/exclusion criteria and defining what constitutes meaningful differentiation among the stages. However, many trials are being designed on the basis of biomarker features and the two need to be coordinated. The Alzheimer's Association Research Roundtable (AARR) Spring 2021 meeting discussed the implementation of preclinical AD staging criteria, and provided recommendations for how they may best be incorporated into clinical trials research. Discussion also included what currently available tools for global clinical trials may best define populations in preclinical AD trials, and if are we able to differentiate preclinical from clinical stages of the disease. Well-defined AD staging criteria are key to improving early detection, diagnostics, clinical trial enrollment, and identifying statistically significant clinical changes, and researchers discussed how emerging blood biomarkers may help with more efficient screening in preclinical stages.

Rationale for the selection of dual primary endpoints in prevention studies of cognitively unimpaired individuals at genetic risk for developing symptoms of Alzheimer's disease.

BACKGROUND: There is a critical need for novel primary endpoints designed to detect early and subtle changes in cognition in clinical trials targeting the asymptomatic (preclinical) phase of Alzheimer's disease (AD). The Alzheimer's Prevention Initiative (API) Generation Program, conducted in cognitively unimpaired individuals at risk of developing AD (e.g., enriched by the apolipoprotein E (APOE) genotype), used a novel dual primary endpoints approach, whereby demonstration of treatment effect in one of the two endpoints is sufficient for trial success. The two primary endpoints were (1) time to event (TTE)-with an event defined as a diagnosis of mild cognitive impairment (MCI) due to AD and/or dementia due to AD-and (2) change from baseline to month 60 in the API Preclinical Composite Cognitive (APCC) test score. METHODS: Historical observational data from three sources were used to fit models to describe the TTE and the longitudinal APCC decline, both in people who do and do not progress to MCI or dementia due to AD. Clinical endpoints were simulated based on the TTE and APCC models to assess the performance of the dual endpoints versus each of the two single endpoints, with the selected treatment effect ranging from a hazard ratio (HR) of 0.60 (40% risk reduction) to 1 (no effect). RESULTS: A Weibull model was selected for TTE, and power and linear models were selected to describe the APCC score for progressors and non-progressors, respectively. Derived effect sizes in terms of reduction of the APCC change from baseline to year 5 were low (0.186 for HR = 0.67). The power for the APCC alone was consistently lower compared to the power of TTE alone (58% [APCC] vs 84% [TTE] for HR = 0.67). Also, the overall power was higher for the 80%/20% distribution (82%) of the family-wise type 1 error rate (alpha) between TTE and APCC compared to 20%/80% (74%). CONCLUSIONS: Dual endpoints including TTE and a measure of cognitive decline perform better than the cognitive decline measure as a single primary endpoint in a cognitively unimpaired population at risk of AD (based on the APOE genotype). Clinical trials in this population, however, need to be large, include older age, and have a long follow-up period of at least 5 years to be able to detect treatment effects.

The Alzheimer's Prevention Initiative Composite Cognitive Test: a practical measure for tracking cognitive decline in preclinical Alzheimer's disease.

BACKGROUND: There is growing interest in identifying sensitive composite cognitive tests to serve as primary endpoints in preclinical Alzheimer's disease (AD) treatment trials. We reported previously a composite cognitive test score sensitive to tracking preclinical AD decline up to 5 years prior to clinical diagnosis. Here we expand upon and refine this work, empirically deriving a composite cognitive test score sensitive to tracking preclinical AD decline up to 11 years prior to diagnosis and suitable for use as a primary endpoint in a preclinical AD trial. METHODS: This study used a longitudinal approach to maximize sensitivity to tracking progressive cognitive decline in people who progressed to the clinical stages of AD (n = 868) compared to those who remained cognitively unimpaired during the same time period (n = 989), thereby correcting for normal aging and practice effects. Specifically, we developed the Alzheimer's Prevention Initiative Preclinical Composite Cognitive test (APCC) to measure very early longitudinal cognitive decline in older adults with preclinical AD. Data from three cohorts from Rush University were analyzed using a partial least squares (PLS) regression model to identify optimal composites within different time periods prior to diagnosis, up to 11 years prior to diagnosis. The mean-to-standard deviation ratio (MSDRs) is an indicator of sensitivity to change and was used to inform the final calculation of the composite score. RESULTS: The optimal composite, the APCC, is calculated: 0.26*Symbol Digit Modalities + 2.24*MMSE Orientation to Time + 2.14*MMSE Orientation to Place + 0.53*Logical Memory Delayed Recall + 1.36* Word List-Delayed Recall + 0.68*Judgment of Line Orientation + 1.39*Raven's Progressive Matrices Matrices (subset of 9 items from A and B). The MSDR of the APCC in a population of preclinical AD individuals who eventually progress to cognitive impairment, compared to those who remained cognitively unimpaired during the same time period, was - 1.10 over 1 year. CONCLUSIONS: The APCC is an empirically derived composite cognitive test score with high face validity that is sensitive to preclinical AD decline up to 11 years prior to diagnosis of the clinical stages of AD. The components of the APCC are supported by theoretical understanding of cognitive decline that occurs during preclinical AD. The APCC was used as a primary outcome in the API Generation Program trials.

The Alzheimer's Prevention Initiative Generation Program: Study design of two randomized controlled trials for individuals at risk for clinical onset of Alzheimer's disease.

INTRODUCTION: Alzheimer's disease (AD) pathology, including the accumulation of amyloid beta (Aß) species and tau pathology, begins decades before the onset of cognitive impairment. This long preclinical period provides an opportunity for clinical trials designed to prevent or delay the onset of cognitive impairment due to AD. Under the umbrella of the Alzheimer's Prevention Initiative Generation Program, therapies targeting Aß, including CNP520 (umibecestat), a ß-site-amyloid precursor protein cleaving enzyme-1 (BACE-1) inhibitor, and CAD106, an active Aß immunotherapy, are in clinical development in preclinical AD. METHODS: The Alzheimer's Prevention Initiative Generation Program comprises two pivotal (phase 2/3) studies that assess the efficacy and safety of umibecestat and CAD106 in cognitively unimpaired individuals with high risk for developing symptoms of AD based on their age (60-75 years), APOE4 genotype, and, for heterozygotes (APOE ε2/ε4 or ε3/ε4), elevated brain amyloid. Approximately, 3500 individuals will be enrolled in either Generation Study 1 (randomized to cohort 1 [CAD106 injection or placebo, 5:3] or cohort 2 [oral umibecestat 50 mg or placebo, 3:2]) or Generation Study 2 (randomized to oral umibecestat 50 mg and 15 mg, or placebo [2:1:2]). Participants receive treatment for at least 60 months and up to a maximum of 96 months. Primary outcomes include time to event, with event defined as diagnosis of mild cognitive impairment due to AD and/or dementia due to AD, and the Alzheimer's Prevention Initiative preclinical composite cognitive test battery. Secondary endpoints include the Clinical Dementia Rating Sum of Boxes, Repeatable Battery for the Assessment of Neuropsychological Status total score, Everyday Cognition Scale, biomarkers, and brain imaging. DISCUSSION: The Generation Program is designed to assess the efficacy, safety, and biomarker effects of the two treatments in individuals at high risk for AD. It may also provide a plausible test of the amyloid hypothesis and further accelerate the evaluation of AD prevention therapies.

Measuring cognition and function in the preclinical stage of Alzheimer's disease.

The Alzheimer's Association's Research Roundtable met in November 2016 to explore how best to measure changes in cognition and function in the preclinical stage of Alzheimer's disease. This review will cover the tools and instruments currently available to identify populations for prevention trials, and measure subtle disease progression in the earliest stages of Alzheimer's disease, and will include discussions of suitable cognitive, behavioral, functional, composite, and biological endpoints for prevention trials. Current prevention trials are reviewed including TOMMOROW, Alzheimer's Prevention Initiative Autosomal Dominant Alzheimer's Disease Trial, the Alzheimer's Prevention Initiative Generation Study, and the Anti-Amyloid Treatment in Asymptomatic Alzheimer's to compare current approaches and tools that are being developed.

The BACE-1 inhibitor CNP520 for prevention trials in Alzheimer's disease.

The beta-site amyloid precursor protein cleaving enzyme-1 (BACE-1) initiates the generation of amyloid-ß (Aß), and the amyloid cascade leading to amyloid plaque deposition, neurodegeneration, and dementia in Alzheimer's disease (AD). Clinical failures of anti-Aß therapies in dementia stages suggest that treatment has to start in the early, asymptomatic disease states. The BACE-1 inhibitor CNP520 has a selectivity, pharmacodynamics, and distribution profile suitable for AD prevention studies. CNP520 reduced brain and cerebrospinal fluid (CSF) Aß in rats and dogs, and Aß plaque deposition in APP-transgenic mice. Animal toxicology studies of CNP520 demonstrated sufficient safety margins, with no signs of hair depigmentation, retina degeneration, liver toxicity, or cardiovascular effects. In healthy adults ≥ 60 years old, treatment with CNP520 was safe and well tolerated and resulted in robust and dose-dependent Aß reduction in the cerebrospinal fluid. Thus, long-term, pivotal studies with CNP520 have been initiated in the Generation Program.

Active Aß immunotherapy CAD106 in Alzheimer's disease: A phase 2b study.

INTRODUCTION: This randomized, double-blind, placebo-controlled, 90-week study assessed safety, tolerability, and immunogenicity of CAD106 with/without adjuvant in patients with mild Alzheimer's disease. METHODS: One hundred twenty-one patients received up to seven intramuscular injections of CAD106 (150 µg or 450 µg) or placebo ± adjuvant over 60 weeks. An amyloid positron emission tomography (PET) substudy was also conducted. RESULTS: CAD106 induced strong serological responses (amyloid-beta [Aß]-Immunoglobuline G[IgG]) in 55.1% (150 µg) and 81.1% (450 µg) of patients (strong serological responders [SSRs]). Serious adverse events (SAEs) were reported in 24.5% (95% confidence interval [CI] 16.7-33.8) of the patients in the active treatment group and in 6.7% (95% CI 0.2-31.9) in the placebo group. Three of the SAEs were classified as possibly related to study drug by the investigators. No evidence of central nervous system inflammation was found. Amyloid-related imaging abnormalities (ARIAs) occurred in six cases, all of them were strong serological responders. None of the ARIAs were symptomatic. Serum Aß-IgG titer area under the curves correlated negatively with amyloid PET standardized uptake value ratio percentage change from baseline to week 78 within the CAD106-treated patients (r = -0.84, P = .0004). Decrease in cortical gray-matter volume from baseline to week 78 was larger in SSRs than in controls (P = .0077). DISCUSSION: Repeated CAD106 administration was generally well tolerated. CAD106 450 µg with alum adjuvant demonstrated the best balance between antibody response and tolerability.

The NK1-receptor antagonist TKA731 in painful diabetic neuropathy: a randomised, controlled trial.

Substance P is one of the neurotransmitters released by primary nociceptive neurons in the dorsal horn of the spinal cord and it binds postsynaptically to NK(1)-receptors. This receptor is therefore an obvious target for analgesic drugs. The aim of this multicenter, randomised, double-blind, placebo-controlled and parallel-group study was to test if the non-peptide NK(1)-receptor antagonist TKA731 would relieve painful diabetic polyneuropathy. Eighty-seven patients completed a treatment period of 2 weeks' duration with TKA731 (150 mg daily) or placebo preceded by one week for baseline observations. There was no significant difference between TKA731 and placebo in change in pain rating from baseline to study end neither for rating of total pain (mean -13.4 mm vs. -11.6 mm, p = 0.664) nor for change in ratings of different pain symptoms (touch- or pressure-evoked pain, pain paroxysms, steady burning or deep aching pain) (p = 0.169-0.834).

Long-term treatment with active Aß immunotherapy with CAD106 in mild Alzheimer's disease.

INTRODUCTION: CAD106 is designed to stimulate amyloid-ß (Aß)-specific antibody responses while avoiding T-cell autoimmune responses. The CAD106 first-in-human study demonstrated a favorable safety profile and promising antibody response. We investigated long-term safety, tolerability and antibody response after repeated CAD106 injections. METHODS: Two phase IIa, 52-week, multicenter, randomized, double-blind, placebo-controlled core studies (2201; 2202) and two 66-week open-label extension studies (2201E; 2202E) were conducted in patients with mild Alzheimer's disease (AD) aged 40 to 85 years. Patients were randomized to receive 150µg CAD106 or placebo given as three subcutaneous (2201) or subcutaneous/intramuscular (2202) injections, followed by four injections (150 µg CAD106; subcutaneous, 2201E1; intramuscular, 2202E1). Our primary objective was to evaluate the safety and tolerability of repeated injections, including monitoring cerebral magnetic resonance imaging scans, adverse events (AEs) and serious AEs (SAEs). Further objectives were to assess Aß-specific antibody response in serum and Aß-specific T-cell response (core only). Comparable Aß-immunoglobulin G (IgG) exposure across studies supported pooled immune response assessments. RESULTS: Fifty-eight patients were randomized (CAD106, n = 47; placebo, n = 11). Baseline demographics and characteristics were balanced. Forty-five patients entered extension studies. AEs occurred in 74.5% of CAD106-treated patients versus 63.6% of placebo-treated patients (core), and 82.2% experienced AEs during extension studies. Most AEs were mild to moderate in severity, were not study medication-related and did not require discontinuation. SAEs occurred in 19.1% of CAD106-treated patients and 36.4% of placebo-treated patients (core). One patient (CAD106-treated; 2201) reported a possibly study drug-related SAE of intracerebral hemorrhage. Four patients met criteria for amyloid-related imaging abnormalities (ARIA) corresponding to microhemorrhages: one was CAD106-treated (2201), one placebo-treated (2202) and two open-label CAD106-treated. No ARIA corresponded to vasogenic edema. Two patients discontinued extension studies because of SAEs (rectal neoplasm and rapid AD progression, respectively). Thirty CAD106-treated patients (63.8%) were serological responders. Sustained Aß-IgG titers and prolonged time to decline were observed in extensions versus core studies. Neither Aß1-6 nor Aß1-42 induced specific T-cell responses; however, positive control responses were consistently detected with the CAD106 carrier. CONCLUSIONS: No unexpected safety findings or Aß-specific T-cell responses support the CAD106 favorable tolerability profile. Long-term treatment-induced Aß-specific antibody titers and prolonged time to decline indicate antibody exposure may increase with additional injections. CAD106 may be a valuable therapeutic option in AD. TRIAL REGISTRATION: ClinicalTrials.gov identifiers: NCT00733863, registered 8 August 2008; NCT00795418, registered 10 November 2008; NCT00956410, registered 10 August 2009; NCT01023685, registered 1 December 2009.

Active immunotherapy options for Alzheimer's disease.

Alzheimer's disease (AD) is the most common cause of dementia and a major contributor to disability and dependency among older people. AD pathogenesis is associated with the accumulation of amyloid-beta protein (Aß) and/or hyperphosphorylated tau protein in the brain. At present, current therapies provide temporary symptomatic benefit, but do not treat the underlying disease. Recent research has thus focused on investigating the molecular and cellular pathways and processes involved in AD pathogenesis to support the development of effective disease-modifying agents. In accordance with the existing Aß-cascade hypothesis for AD pathogenesis, immunotherapy has been the most extensively studied approach in Aß-targeted therapy. Both passive and active immunotherapies have been shown to effectively reduce Aß accumulation and prevent downstream pathology in preclinical models. Following AN1792, second-generation active immunotherapies have shown promising results in terms of antibody response and safety. Comparatively, tau immunotherapy is not as advanced, but preclinical data support its development into clinical trials. Results from active amyloid-based immunotherapy studies in preclinical models indicate that intervention appears to be more effective in early stages of amyloid accumulation, highlighting the importance of diagnosing AD as early as possible and undertaking clinical trials at this stage. This strategy, combined with improving our understanding of the complex AD pathogenesis, is imperative to the successful development of these disease-modifying agents. This paper will review the active immunotherapies currently in development, including the benefits and challenges associated with this approach.

Safety, tolerability, and antibody response of active Aß immunotherapy with CAD106 in patients with Alzheimer's disease: randomised, double-blind, placebo-controlled, first-in-human study.

BACKGROUND: Immunotherapy targeting the amyloid ß (Aß) peptide is a potential strategy to slow the progression of Alzheimer's disease. We aimed to assess the safety and tolerability of CAD106, a novel active Aß immunotherapy for patients with Alzheimer's disease, designed to induce N-terminal Aß-specific antibodies without an Aß-specific T-cell response. METHODS: We did a phase 1, double-blind, placebo-controlled, 52-week study in two centres in Sweden. Participants, aged 50-80 years, with mild-to-moderate Alzheimer's disease were entered into one of two cohorts according to time of study entry and then randomly allocated (by use of a computer-generated randomisation sequence) to receive either CAD106 or placebo (4:1; cohort one received CAD106 50 µg or placebo, cohort two received CAD106 150 µg or placebo). Each patient received three subcutaneous injections. All patients, caregivers, and investigators were masked to treatment allocation throughout the study. Primary objectives were to assess the safety and tolerability of CAD106 and to identify the Aß-specific antibody response. Safety assessment was done by recording of all adverse events, assessment of MRI scans, physical and neurological examinations, vital signs, electrocardiography, electroencephalography, and laboratory analysis of blood and CSF. Patients with Aß-IgG serum titres higher than 16 units at least once during the study were classified as responders. This study is registered with ClinicalTrials.gov, number NCT00411580. FINDINGS: Between August, 2005, and March, 2007, we randomly allocated 31 patients into cohort one (24 patients to CAD106 treatment and seven to placebo) and 27 patients into cohort two (22 patients to CAD106 treatment and five to placebo). 56 of 58 patients reported adverse events. In cohort one, nasopharyngitis was the most commonly reported adverse event (10 of 24 CAD106-treated patients). In cohort two, injection site erythema was the most commonly reported adverse event (14 of 22 CAD106-treated patients). Overall, nine patients reported serious adverse events--none was thought to be related to the study drug. We recorded no clinical or subclinical cases of meningoencephalitis. 16 of 24 (67%) CAD106-treated patients in cohort one and 18 of 22 (82%) in cohort two developed Aß antibody response meeting pre-specified responder threshold. One of 12 placebo-treated patients (8%) had Aß-IgG concentrations that qualified them as a responder. INTERPRETATION: Our findings suggest that CAD106 has a favourable safety profile and acceptable antibody response in patients with Alzheimer's disease. Larger trials with additional dose investigations are needed to confirm the safety and establish the efficacy of CAD106. FUNDING: Novartis Pharma AG.