Donanemab in Early Alzheimer's Disease.

BACKGROUND: A hallmark of Alzheimer's disease is the accumulation of amyloid-ß (Aß) peptide. Donanemab, an antibody that targets a modified form of deposited Aß, is being investigated for the treatment of early Alzheimer's disease. METHODS: We conducted a phase 2 trial of donanemab in patients with early symptomatic Alzheimer's disease who had tau and amyloid deposition on positron-emission tomography (PET). Patients were randomly assigned in a 1:1 ratio to receive donanemab (700 mg for the first three doses and 1400 mg thereafter) or placebo intravenously every 4 weeks for up to 72 weeks. The primary outcome was the change from baseline in the score on the Integrated Alzheimer's Disease Rating Scale (iADRS; range, 0 to 144, with lower scores indicating greater cognitive and functional impairment) at 76 weeks. Secondary outcomes included the change in scores on the Clinical Dementia Rating Scale-Sum of Boxes (CDR-SB), the 13-item cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-Cog13), the Alzheimer's Disease Cooperative Study-Instrumental Activities of Daily Living Inventory (ADCS-iADL), and the Mini-Mental State Examination (MMSE), as well as the change in the amyloid and tau burden on PET. RESULTS: A total of 257 patients were enrolled; 131 were assigned to receive donanemab and 126 to receive placebo. The baseline iADRS score was 106 in both groups. The change from baseline in the iADRS score at 76 weeks was -6.86 with donanemab and -10.06 with placebo (difference, 3.20; 95% confidence interval, 0.12 to 6.27; P = 0.04). The results for most secondary outcomes showed no substantial difference. At 76 weeks, the reductions in the amyloid plaque level and the global tau load were 85.06 centiloids and 0.01 greater, respectively, with donanemab than with placebo. Amyloid-related cerebral edema or effusions (mostly asymptomatic) occurred with donanemab. CONCLUSIONS: In patients with early Alzheimer's disease, donanemab resulted in a better composite score for cognition and for the ability to perform activities of daily living than placebo at 76 weeks, although results for secondary outcomes were mixed. Longer and larger trials are necessary to study the efficacy and safety of donanemab in Alzheimer's disease. (Funded by Eli Lilly; TRAILBLAZER-ALZ ClinicalTrials.gov number, NCT03367403.).

SARS-CoV-2 Neutralizing Antibody LY-CoV555 in Outpatients with Covid-19.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (Covid-19), which is most frequently mild yet can be severe and life-threatening. Virus-neutralizing monoclonal antibodies are predicted to reduce viral load, ameliorate symptoms, and prevent hospitalization. METHODS: In this ongoing phase 2 trial involving outpatients with recently diagnosed mild or moderate Covid-19, we randomly assigned 452 patients to receive a single intravenous infusion of neutralizing antibody LY-CoV555 in one of three doses (700 mg, 2800 mg, or 7000 mg) or placebo and evaluated the quantitative virologic end points and clinical outcomes. The primary outcome was the change from baseline in the viral load at day 11. The results of a preplanned interim analysis as of September 5, 2020, are reported here. RESULTS: At the time of the interim analysis, the observed mean decrease from baseline in the log viral load for the entire population was -3.81, for an elimination of more than 99.97% of viral RNA. For patients who received the 2800-mg dose of LY-CoV555, the difference from placebo in the decrease from baseline was -0.53 (95% confidence interval [CI], -0.98 to -0.08; P = 0.02), for a viral load that was lower by a factor of 3.4. Smaller differences from placebo in the change from baseline were observed among the patients who received the 700-mg dose (-0.20; 95% CI, -0.66 to 0.25; P = 0.38) or the 7000-mg dose (0.09; 95% CI, -0.37 to 0.55; P = 0.70). On days 2 to 6, the patients who received LY-CoV555 had a slightly lower severity of symptoms than those who received placebo. The percentage of patients who had a Covid-19-related hospitalization or visit to an emergency department was 1.6% in the LY-CoV555 group and 6.3% in the placebo group. CONCLUSIONS: In this interim analysis of a phase 2 trial, one of three doses of neutralizing antibody LY-CoV555 appeared to accelerate the natural decline in viral load over time, whereas the other doses had not by day 11. (Funded by Eli Lilly; BLAZE-1 ClinicalTrials.gov number, NCT04427501.).

Bamlanivimab plus Etesevimab in Mild or Moderate Covid-19.

BACKGROUND: Patients with underlying medical conditions are at increased risk for severe coronavirus disease 2019 (Covid-19). Whereas vaccine-derived immunity develops over time, neutralizing monoclonal-antibody treatment provides immediate, passive immunity and may limit disease progression and complications. METHODS: In this phase 3 trial, we randomly assigned, in a 1:1 ratio, a cohort of ambulatory patients with mild or moderate Covid-19 who were at high risk for progression to severe disease to receive a single intravenous infusion of either a neutralizing monoclonal-antibody combination agent (2800 mg of bamlanivimab and 2800 mg of etesevimab, administered together) or placebo within 3 days after a laboratory diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The primary outcome was the overall clinical status of the patients, defined as Covid-19-related hospitalization or death from any cause by day 29. RESULTS: A total of 1035 patients underwent randomization and received an infusion of bamlanivimab-etesevimab or placebo. The mean (±SD) age of the patients was 53.8±16.8 years, and 52.0% were adolescent girls or women. By day 29, a total of 11 of 518 patients (2.1%) in the bamlanivimab-etesevimab group had a Covid-19-related hospitalization or death from any cause, as compared with 36 of 517 patients (7.0%) in the placebo group (absolute risk difference, -4.8 percentage points; 95% confidence interval [CI], -7.4 to -2.3; relative risk difference, 70%; P<0.001). No deaths occurred in the bamlanivimab-etesevimab group; in the placebo group, 10 deaths occurred, 9 of which were designated by the trial investigators as Covid-19-related. At day 7, a greater reduction from baseline in the log viral load was observed among patients who received bamlanivimab plus etesevimab than among those who received placebo (difference from placebo in the change from baseline, -1.20; 95% CI, -1.46 to -0.94; P<0.001). CONCLUSIONS: Among high-risk ambulatory patients, bamlanivimab plus etesevimab led to a lower incidence of Covid-19-related hospitalization and death than did placebo and accelerated the decline in the SARS-CoV-2 viral load. (Funded by Eli Lilly; BLAZE-1 ClinicalTrials.gov number, NCT04427501.).

Donanemab in Early Symptomatic Alzheimer Disease: The TRAILBLAZER-ALZ 2 Randomized Clinical Trial.

Importance: There are limited efficacious treatments for Alzheimer disease. Objective: To assess efficacy and adverse events of donanemab, an antibody designed to clear brain amyloid plaque. Design, Setting, and Participants: Multicenter (277 medical research centers/hospitals in 8 countries), randomized, double-blind, placebo-controlled, 18-month phase 3 trial that enrolled 1736 participants with early symptomatic Alzheimer disease (mild cognitive impairment/mild dementia) with amyloid and low/medium or high tau pathology based on positron emission tomography imaging from June 2020 to November 2021 (last patient visit for primary outcome in April 2023). Interventions: Participants were randomized in a 1:1 ratio to receive donanemab (n = 860) or placebo (n = 876) intravenously every 4 weeks for 72 weeks. Participants in the donanemab group were switched to receive placebo in a blinded manner if dose completion criteria were met. Main Outcomes and Measures: The primary outcome was change in integrated Alzheimer Disease Rating Scale (iADRS) score from baseline to 76 weeks (range, 0-144; lower scores indicate greater impairment). There were 24 gated outcomes (primary, secondary, and exploratory), including the secondary outcome of change in the sum of boxes of the Clinical Dementia Rating Scale (CDR-SB) score (range, 0-18; higher scores indicate greater impairment). Statistical testing allocated α of .04 to testing low/medium tau population outcomes, with the remainder (.01) for combined population outcomes. Results: Among 1736 randomized participants (mean age, 73.0 years; 996 [57.4%] women; 1182 [68.1%] with low/medium tau pathology and 552 [31.8%] with high tau pathology), 1320 (76%) completed the trial. Of the 24 gated outcomes, 23 were statistically significant. The least-squares mean (LSM) change in iADRS score at 76 weeks was -6.02 (95% CI, -7.01 to -5.03) in the donanemab group and -9.27 (95% CI, -10.23 to -8.31) in the placebo group (difference, 3.25 [95% CI, 1.88-4.62]; P < .001) in the low/medium tau population and -10.2 (95% CI, -11.22 to -9.16) with donanemab and -13.1 (95% CI, -14.10 to -12.13) with placebo (difference, 2.92 [95% CI, 1.51-4.33]; P < .001) in the combined population. LSM change in CDR-SB score at 76 weeks was 1.20 (95% CI, 1.00-1.41) with donanemab and 1.88 (95% CI, 1.68-2.08) with placebo (difference, -0.67 [95% CI, -0.95 to -0.40]; P < .001) in the low/medium tau population and 1.72 (95% CI, 1.53-1.91) with donanemab and 2.42 (95% CI, 2.24-2.60) with placebo (difference, -0.7 [95% CI, -0.95 to -0.45]; P < .001) in the combined population. Amyloid-related imaging abnormalities of edema or effusion occurred in 205 participants (24.0%; 52 symptomatic) in the donanemab group and 18 (2.1%; 0 symptomatic during study) in the placebo group and infusion-related reactions occurred in 74 participants (8.7%) with donanemab and 4 (0.5%) with placebo. Three deaths in the donanemab group and 1 in the placebo group were considered treatment related. Conclusions and Relevance: Among participants with early symptomatic Alzheimer disease and amyloid and tau pathology, donanemab significantly slowed clinical progression at 76 weeks in those with low/medium tau and in the combined low/medium and high tau pathology population. Trial Registration: ClinicalTrials.gov Identifier: NCT04437511.

A Randomized, Placebo-Controlled Clinical Trial of Bamlanivimab and Etesevimab Together in High-Risk Ambulatory Patients With COVID-19 and Validation of the Prognostic Value of Persistently High Viral Load.

BACKGROUND: Based on interim analyses and modeling data, lower doses of bamlanivimab and etesevimab together (700/1400 mg) were investigated to determine optimal dose and expand availability of treatment. METHODS: This Phase 3 portion of the BLAZE-1 trial characterized the effect of bamlanivimab with etesevimab on overall patient clinical status and virologic outcomes in ambulatory patients ≥12 years old, with mild-to-moderate coronavirus disease 2019 (COVID-19), and ≥1 risk factor for progressing to severe COVID-19 and/or hospitalization. Bamlanivimab and etesevimab together (700/1400 mg) or placebo were infused intravenously within 3 days of patients' first positive COVID-19 test. RESULTS: In total, 769 patients were infused (median age [range]; 56.0 years [12, 93], 30.3% of patients ≥65 years of age and median duration of symptoms; 4 days). By day 29, 4/511 patients (0.8%) in the antibody treatment group had a COVID-19-related hospitalization or any-cause death, as compared with 15/258 patients (5.8%) in the placebo group (Δ[95% confidence interval {CI}] = -5.0 [-8.0, -2.1], P < .001). No deaths occurred in the bamlanivimab and etesevimab group compared with 4 deaths (all COVID-19-related) in the placebo group. Patients receiving antibody treatment had a greater mean reduction in viral load from baseline to Day 7 (Δ[95% CI] = -0.99 [-1.33, -.66], P < .0001) compared with those receiving placebo. Persistently high viral load at Day 7 correlated with COVID-19-related hospitalization or any-cause death by Day 29 in all BLAZE-1 cohorts investigated. CONCLUSIONS: These data support the use of bamlanivimab and etesevimab (700/1400 mg) for ambulatory patients at high risk for severe COVID-19. Evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants will require continued monitoring to determine the applicability of this treatment. CLINICAL TRIALS REGISTRATION: NCT04427501.

Effect of Bamlanivimab as Monotherapy or in Combination With Etesevimab on Viral Load in Patients With Mild to Moderate COVID-19: A Randomized Clinical Trial.

Importance: Coronavirus disease 2019 (COVID-19) continues to spread rapidly worldwide. Neutralizing antibodies are a potential treatment for COVID-19. Objective: To determine the effect of bamlanivimab monotherapy and combination therapy with bamlanivimab and etesevimab on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load in mild to moderate COVID-19. Design, Setting, and Participants: The BLAZE-1 study is a randomized phase 2/3 trial at 49 US centers including ambulatory patients (N = 613) who tested positive for SARS-CoV-2 infection and had 1 or more mild to moderate symptoms. Patients who received bamlanivimab monotherapy or placebo were enrolled first (June 17-August 21, 2020) followed by patients who received bamlanivimab and etesevimab or placebo (August 22-September 3). These are the final analyses and represent findings through October 6, 2020. Interventions: Patients were randomized to receive a single infusion of bamlanivimab (700 mg [n = 101], 2800 mg [n = 107], or 7000 mg [n = 101]), the combination treatment (2800 mg of bamlanivimab and 2800 mg of etesevimab [n = 112]), or placebo (n = 156). Main Outcomes and Measures: The primary end point was change in SARS-CoV-2 log viral load at day 11 (±4 days). Nine prespecified secondary outcome measures were evaluated with comparisons between each treatment group and placebo, and included 3 other measures of viral load, 5 on symptoms, and 1 measure of clinical outcome (the proportion of patients with a COVID-19-related hospitalization, an emergency department [ED] visit, or death at day 29). Results: Among the 577 patients who were randomized and received an infusion (mean age, 44.7 [SD, 15.7] years; 315 [54.6%] women), 533 (92.4%) completed the efficacy evaluation period (day 29). The change in log viral load from baseline at day 11 was -3.72 for 700 mg, -4.08 for 2800 mg, -3.49 for 7000 mg, -4.37 for combination treatment, and -3.80 for placebo. Compared with placebo, the differences in the change in log viral load at day 11 were 0.09 (95% CI, -0.35 to 0.52; P = .69) for 700 mg, -0.27 (95% CI, -0.71 to 0.16; P = .21) for 2800 mg, 0.31 (95% CI, -0.13 to 0.76; P = .16) for 7000 mg, and -0.57 (95% CI, -1.00 to -0.14; P = .01) for combination treatment. Among the secondary outcome measures, differences between each treatment group vs the placebo group were statistically significant for 10 of 84 end points. The proportion of patients with COVID-19-related hospitalizations or ED visits was 5.8% (9 events) for placebo, 1.0% (1 event) for 700 mg, 1.9% (2 events) for 2800 mg, 2.0% (2 events) for 7000 mg, and 0.9% (1 event) for combination treatment. Immediate hypersensitivity reactions were reported in 9 patients (6 bamlanivimab, 2 combination treatment, and 1 placebo). No deaths occurred during the study treatment. Conclusions and Relevance: Among nonhospitalized patients with mild to moderate COVID-19 illness, treatment with bamlanivimab and etesevimab, compared with placebo, was associated with a statistically significant reduction in SARS-CoV-2 viral load at day 11; no significant difference in viral load reduction was observed for bamlanivimab monotherapy. Further ongoing clinical trials will focus on assessing the clinical benefit of antispike neutralizing antibodies in patients with COVID-19 as a primary end point. Trial Registration: ClinicalTrials.gov Identifier: NCT04427501.

Effect of Bamlanivimab vs Placebo on Incidence of COVID-19 Among Residents and Staff of Skilled Nursing and Assisted Living Facilities: A Randomized Clinical Trial.

Importance: Preventive interventions are needed to protect residents and staff of skilled nursing and assisted living facilities from COVID-19 during outbreaks in their facilities. Bamlanivimab, a neutralizing monoclonal antibody against SARS-CoV-2, may confer rapid protection from SARS-CoV-2 infection and COVID-19. Objective: To determine the effect of bamlanivimab on the incidence of COVID-19 among residents and staff of skilled nursing and assisted living facilities. Design, Setting, and Participants: Randomized, double-blind, single-dose, phase 3 trial that enrolled residents and staff of 74 skilled nursing and assisted living facilities in the United States with at least 1 confirmed SARS-CoV-2 index case. A total of 1175 participants enrolled in the study from August 2 to November 20, 2020. Database lock was triggered on January 13, 2021, when all participants reached study day 57. Interventions: Participants were randomized to receive a single intravenous infusion of bamlanivimab, 4200 mg (n = 588), or placebo (n = 587). Main Outcomes and Measures: The primary outcome was incidence of COVID-19, defined as the detection of SARS-CoV-2 by reverse transcriptase-polymerase chain reaction and mild or worse disease severity within 21 days of detection, within 8 weeks of randomization. Key secondary outcomes included incidence of moderate or worse COVID-19 severity and incidence of SARS-CoV-2 infection. Results: The prevention population comprised a total of 966 participants (666 staff and 300 residents) who were negative at baseline for SARS-CoV-2 infection and serology (mean age, 53.0 [range, 18-104] years; 722 [74.7%] women). Bamlanivimab significantly reduced the incidence of COVID-19 in the prevention population compared with placebo (8.5% vs 15.2%; odds ratio, 0.43 [95% CI, 0.28-0.68]; P < .001; absolute risk difference, -6.6 [95% CI, -10.7 to -2.6] percentage points). Five deaths attributed to COVID-19 were reported by day 57; all occurred in the placebo group. Among 1175 participants who received study product (safety population), the rate of participants with adverse events was 20.1% in the bamlanivimab group and 18.9% in the placebo group. The most common adverse events were urinary tract infection (reported by 12 participants [2%] who received bamlanivimab and 14 [2.4%] who received placebo) and hypertension (reported by 7 participants [1.2%] who received bamlanivimab and 10 [1.7%] who received placebo). Conclusions and Relevance: Among residents and staff in skilled nursing and assisted living facilities, treatment during August-November 2020 with bamlanivimab monotherapy reduced the incidence of COVID-19 infection. Further research is needed to assess preventive efficacy with current patterns of viral strains with combination monoclonal antibody therapy. Trial Registration: ClinicalTrials.gov Identifier: NCT04497987.

Effect of Amyloid Imaging on the Diagnosis and Management of Patients with Cognitive Decline: Impact of Appropriate Use Criteria.

BACKGROUND: Published appropriate use criteria (AUC) describe patients for whom amyloid positron emission tomography (PET) might be most useful. This study compared the impact of amyloid PET on diagnosis and management in subjects likely to either meet or not meet AUC. METHODS: Physicians provided a provisional diagnosis and management plan for patients presenting with cognitive decline before and after amyloid PET imaging with florbetapir F 18. Participants were classified as AUC-like or not, based on the prescan diagnosis and demographic features. RESULTS: In all, 125 of 229 participants (55%) were classified as AUC-like. Sixty-two percent of the AUC-like subjects had a change in diagnosis after scanning compared with 45% of the non-AUC subjects (p = 0.011). Both groups demonstrated high rates of change in their management plans after scanning (88.0% for AUC-like cases, 85.6% for non-AUC cases). CONCLUSIONS: The impact of amyloid imaging on diagnosis and planned management was maintained and, if anything, amplified in AUC-like patients.

Comparison of imaging biomarkers for Alzheimer's disease: amyloid imaging with [18F]florbetapir positron emission tomography and magnetic resonance imaging voxel-based analysis for entorhinal cortex atrophy.

OBJECTIVE: We compared amyloid positron emission tomography (PET) and magnetic resonance imaging (MRI) in subjects clinically diagnosed with Alzheimer's disease (AD), mild cognitive impairment (MCI), and older healthy controls (OHC) in order to test how these imaging biomarkers represent cognitive decline in AD. METHODS: Fifteen OHC, 19 patients with MCI, and 19 patients with AD were examined by [(18)F]florbetapir PET to quantify the standard uptake value ratio (SUVR) as the degree of amyloid accumulation, by MRI and the voxel-based specific regional analysis system for AD to calculate z-score as the degree of entorhinal cortex atrophy, and by mini-mental state examination (MMSE) and Alzheimer's Disease Assessment Scale-cognitive component--Japanese version (ADAS-Jcog) for cognitive functions. RESULTS: Both cutoff values for measuring AD-like levels of amyloid (1.099 for SUVR) and entorhinal cortex atrophy (1.60 for z-score) were well differentially diagnosed and clinically defined AD from OHC (84.2% for SUVR and 86.7% for z-score). Subgroup analysis based on beta-amyloid positivity revealed that z-score significantly correlated with MMSE (r = -0.626, p < 0.01) and ADAS-Jcog (r = 0.691, p < 0.01) only among subjects with beta-amyloid. CONCLUSIONS: This is the first study to compare [(18)F]florbetapir PET and MRI voxel-based analysis of entorhinal cortex atrophy for AD. Both [(18)F]florbetapir PET and MRI detected changes in AD compared with OHC. Considering that entorhinal cortex atrophy correlated well with cognitive decline only among subjects with beta-amyloid, [18F]florbetapir PET makes it possible to detect AD pathology in the early stage, whereas MRI morphometry for subjects with beta-amyloid provides a good biomarker to assess the severity of AD in the later stage.

The Centiloid Project: standardizing quantitative amyloid plaque estimation by PET.

Although amyloid imaging with PiB-PET ([C-11]Pittsburgh Compound-B positron emission tomography), and now with F-18-labeled tracers, has produced remarkably consistent qualitative findings across a large number of centers, there has been considerable variability in the exact numbers reported as quantitative outcome measures of tracer retention. In some cases this is as trivial as the choice of units, in some cases it is scanner dependent, and of course, different tracers yield different numbers. Our working group was formed to standardize quantitative amyloid imaging measures by scaling the outcome of each particular analysis method or tracer to a 0 to 100 scale, anchored by young controls (≤ 45 years) and typical Alzheimer's disease patients. The units of this scale have been named "Centiloids." Basically, we describe a "standard" method of analyzing PiB PET data and then a method for scaling any "nonstandard" method of PiB PET analysis (or any other tracer) to the Centiloid scale.

PET imaging of amyloid with Florbetapir F 18 and PET imaging of dopamine degeneration with 18F-AV-133 (florbenazine) in patients with Alzheimer's disease and Lewy body disorders.

BACKGROUND: Biomarkers based on the underlying pathology of Alzheimer's disease (AD) and Dementia with Lewy Bodies (DLB) have the potential to improve diagnosis and understanding of the substrate for cognitive impairment in these disorders. The objective of this study was to compare the patterns of amyloid and dopamine PET imaging in patients with AD, DLB and Parkinson's disease (PD) using the amyloid imaging agent florbetapir F 18 and 18F-AV-133 (florbenazine), a marker for vesicular monamine type 2 transporters (VMAT2). METHODS: Patients with DLB and AD, Parkinson's disease (PD) and healthy controls (HC) were recruited for this study. On separate days, subjects received intravenous injections of florbetapir, and florbenazine. Amyloid burden and VMAT2 density were assessed quantitatively and by binary clinical interpretation. Imaging results for both tracers were compared across the four individual diagnostic groups and for combined groups based on underlying pathology (AD/DLB vs. PD/HC for amyloid burden and PD/DLB vs. AD/HC for VMAT binding) and correlated with measures of cognition and parkinsonism. RESULTS: 11 DLB, 10 AD, 5 PD, and 5 controls participated in the study. Amyloid binding was significantly higher in the combined AD/DLB patient group (n = 21) compared to the PD/HC groups (n = 10, mean SUVr: 1.42 vs. 1.07; p = 0.0006). VMAT2 density was significantly lower in the PD/DLB group (n = 16) compared to the AD/ HC group (n = 15; 1.83 vs. 2.97; p < 0.0001). Within the DLB group, there was a significant correlation between cognitive performance and striatal florbenazine binding (r = 0.73; p = 0.011). CONCLUSIONS: The results of this study show significant differences in both florbetapir and florbenazine imaging that are consistent with expected pathology. In addition, VMAT density correlated significantly with cognitive impairment in DLB patients (ClinicalTrials.gov identifier: NCT00857506, registered March 5, 2009).

Potential impact of amyloid imaging on diagnosis and intended management in patients with progressive cognitive decline.

Florbetapir F18 has been approved by the Food and Drug Administration for in vivo assessment of amyloid pathology in patients undergoing evaluation for Alzheimer disease (AD). The aim of this study was to determine the impact of amyloid imaging on the diagnoses and management of patients undergoing evaluation for cognitive decline. Patients were recruited to participate at 19 clinical sites. The site physician provided a provisional diagnosis, an estimate of their diagnostic confidence, and their plan for diagnostic evaluation and management both before and after receiving the results from amyloid imaging with florbetapir F18. Analyses compared the frequency of AD and non-AD diagnoses, plans for ancillary testing, and intended patient management before and after florbetapir imaging. A total of 229 patients participated in the trial (113 amyloid positive, 116 amyloid negative). After receiving the results of the florbetapir scan, diagnosis changed in 125/229, or 54.6% [95% confidence intervals (CI), 48.1%-60.9%], of cases, and diagnostic confidence increased by an average of 21.6% (95% CI, 18.3%-24.8%). A total of 199/229 or 86.9% (95% CI, 81.9%-90.7%) of cases had at least 1 change in their management plan. Intended cholinesterase inhibitor or memantine treatment increased by 17.7% (95% CI, 11.8%-25.8%) of all cases with positive scans and decreased by 23.3% (95% CI, 16.5%-31.8%) of all those with negative scans. Among subjects who had not yet undergone a completed work up, planned brain structural imaging (computed tomographic/magnetic resonance imaging) decreased by 24.4% (95% CI, 17.5%-32.8%) and planned neuropsychological testing decreased by 32.8% (95% CI, 25.0%-41.6%). In summary, amyloid imaging results altered physician's diagnostic thinking, intended testing, and management of patients undergoing evaluation for cognitive decline.

Florbetapir (F18-AV-45) PET to assess amyloid burden in Alzheimer's disease dementia, mild cognitive impairment, and normal aging.

OBJECTIVE: To evaluate the performance characteristics of florbetapir F18 positron emission tomography (PET) in patients with Alzheimer's disease (AD), mild cognitive impairment (MCI), and healthy control subjects (HCs). METHODS: Florbetapir PET was acquired in 184 subjects (45 AD patients, 60 MCI patients, and 79 HCs) within a multicenter phase 2 study. Amyloid burden was assessed visually and quantitatively, and was classified as positive or negative. RESULTS: Florbetapir PET was rated visually amyloid positive in 76% of AD patients, 38% of MCI patients, and 14% of HCs. Eighty-four percent of AD patients, 45% of MCI patients, and 23% of HCs were classified as amyloid positive using a quantitative threshold. Amyloid positivity and mean cortical amyloid burden were associated with age and apolipoprotein E ε4 carrier status. CONCLUSIONS: : The data are consistent with expected rates of amyloid positivity among individuals with clinical diagnoses of AD and MCI, and indicate the potential value of florbetapir F18 PET as an adjunct to clinical diagnosis.

Correlation of amyloid PET ligand florbetapir F 18 binding with Aß aggregation and neuritic plaque deposition in postmortem brain tissue.

BACKGROUND: Florbetapir F 18 (F-AV-45) is a positron emission tomography imaging ligand for the detection of amyloid aggregation associated with Alzheimer disease. Earlier data showed that florbetapir F 18 binds with high affinity to ß-amyloid (Aß) plaques in human brain homogenates (Kd=3.7 nM) and has favorable imaging pharmacokinetic properties, including rapid brain penetration and washout. This study used human autopsy brain tissue to evaluate the correlation between in vitro florbetapir F 18 binding and Aß density measured by established neuropathologic methods. METHODS: The localization and density of florbetapir F 18 binding in frozen and formalin-fixed paraffin-embedded sections of postmortem brain tissue from 40 patients with a varying degree of neurodegenerative pathology was assessed by standard florbetapir F 18 autoradiography and correlated with the localization and density of Aß identified by silver staining, thioflavin S staining, and immunohistochemistry. RESULTS: There were strong quantitative correlations between florbetapir F 18 tissue binding and both Aß plaques identified by light microscopy (Silver staining and thioflavin S fluorescence) and by immunohistochemical measurements of Aß using 3 antibodies recognizing different epitopes of the Aß peptide. Florbetapir F 18 did not bind to neurofibrillary tangles. CONCLUSIONS: Florbetapir F 18 selectively binds Aß in human brain tissue. The binding intensity was quantitatively correlated with the density of Aß plaques identified by standard neuropathologic techniques and correlated with the density of Aß measured by immunohistochemistry. As Aß plaques are a defining neuropathologic feature for Alzheimer disease, these results support the use of florbetapir F 18 as an amyloid positron emission tomography ligand to identify the presence of Alzheimer disease pathology in patients with signs and symptoms of progressive late-life cognitive impairment.

Differential diagnosis in Alzheimer's disease and dementia with Lewy bodies via VMAT2 and amyloid imaging.

BACKGROUND: The noninvasive evaluation of nigrostriatal dopaminergic integrity by PET can provide useful information for the differential diagnosis between dementia with Lewy bodies (DLB) and Alzheimer's disease (AD). OBJECTIVES: To evaluate the diagnostic potential of imaging striatal monoaminergic terminal integrity with the novel vesicular monoamine transporter type 2 (VMAT2) radioligand [(18)F]AV-133 and PET to distinguish DLB from AD. METHODS: Fifty participants [9 DLB, 11 AD, 20 Parkinson's disease (PD) and 10 healthy age-matched control subjects (HC)] underwent [(18)F]AV-133 PET studies. Additionally, 20 participants underwent amyloid imaging PET scans with either [(11)C]PiB or (18)F-florbetaben. VMAT2 density was calculated through normalized tissue uptake value ratios (R(T)) at 120-140 min after injection using the primary visual or the cerebellar cortex as reference region. Comparison of the R(T) for [(18)F]AV-133 was done between the different clinical diagnostic groups. RESULTS: Significantly lower striatal VMAT2 densities were observed in DLB and PD when compared to AD and HC, especially in the posterior putamen. In contrast to PD and DLB, no reductions were observed in AD patients when compared to HC. CONCLUSIONS: [(18)F]AV-133 allows assessment of nigrostriatal degeneration in Lewy body diseases. In contrast to amyloid imaging, VMAT2 imaging with [(18)F]AV-133 can robustly detect reductions of dopaminergic nigrostriatal afferents in DLB patients, assisting in the differential diagnosis from AD.

Use of florbetapir-PET for imaging beta-amyloid pathology.

CONTEXT: The ability to identify and quantify brain ß-amyloid could increase the accuracy of a clinical diagnosis of Alzheimer disease. OBJECTIVE: To determine if florbetapir F 18 positron emission tomographic (PET) imaging performed during life accurately predicts the presence of ß-amyloid in the brain at autopsy. DESIGN, SETTING, AND PARTICIPANTS: Prospective clinical evaluation conducted February 2009 through March 2010 of florbetapir-PET imaging performed on 35 patients from hospice, long-term care, and community health care facilities near the end of their lives (6 patients to establish the protocol and 29 to validate) compared with immunohistochemistry and silver stain measures of brain ß-amyloid after their death used as the reference standard. PET images were also obtained in 74 young individuals (18-50 years) presumed free of brain amyloid to better understand the frequency of a false-positive interpretation of a florbetapir-PET image. MAIN OUTCOME MEASURES: Correlation of florbetapir-PET image interpretation (based on the median of 3 nuclear medicine physicians' ratings) and semiautomated quantification of cortical retention with postmortem ß-amyloid burden, neuritic amyloid plaque density, and neuropathological diagnosis of Alzheimer disease in the first 35 participants autopsied (out of 152 individuals enrolled in the PET pathological correlation study). RESULTS: Florbetapir-PET imaging was performed a mean of 99 days (range, 1-377 days) before death for the 29 individuals in the primary analysis cohort. Fifteen of the 29 individuals (51.7%) met pathological criteria for Alzheimer disease. Both visual interpretation of the florbetapir-PET images and mean quantitative estimates of cortical uptake were correlated with presence and quantity of ß-amyloid pathology at autopsy as measured by immunohistochemistry (Bonferroni ρ, 0.78 [95% confidence interval, 0.58-0.89]; P <.001]) and silver stain neuritic plaque score (Bonferroni ρ, 0.71 [95% confidence interval, 0.47-0.86]; P <.001). Florbetapir-PET images and postmortem results rated as positive or negative for ß-amyloid agreed in 96% of the 29 individuals in the primary analysis cohort. The florbetapir-PET image was rated as amyloid negative in the 74 younger individuals in the nonautopsy cohort. CONCLUSIONS: Florbetapir-PET imaging was correlated with the presence and density of ß-amyloid. These data provide evidence that a molecular imaging procedure can identify ß-amyloid pathology in the brains of individuals during life. Additional studies are required to understand the appropriate use of florbetapir-PET imaging in the clinical diagnosis of Alzheimer disease and for the prediction of progression to dementia.

Synthesis and evaluation of indolinyl- and indolylphenylacetylenes as PET imaging agents for beta-amyloid plaques.

Two new phenylacetylene derivatives, 5-((4-(2-(2-(2-fluoroethoxy)ethoxy)ethoxy)phenyl)ethynyl)indoline 8 and 5-((4-(2-(2-(2-fluoroethoxy)ethoxy)ethoxy)phenyl)ethynyl)-1H-indole 14, targeting beta-amyloid (Abeta) plaques have been prepared. In vitro binding carried out in tissue homogenates prepared from postmortem AD brains with [(125)I]IMPY (6-iodo-2-(4'-dimethylamino-)phenyl-imidazo[1,2-a]pyridine) as the radioligand indicated good binding affinities (K(i)=4.0 and 1.5nM for 8 and 14, respectively). Brain penetration of the corresponding radiofluorinated ligands, evaluated in the normal mice, showed good initial brain penetration (4.50 and 2.43% ID/g (injected dose/gram) for [(18)F]8 and [(18)F]14 at 2min after injection) with moderate to low washout rates from the brain (1.71% ID/g at 2h and 2.10% ID/g at 3h, respectively). Autoradiography and homogenate binding studies demonstrated the high specific binding of [(18)F]14 to the Abeta plaques; however, [(18)F]8 showed low specific binding. These preliminary results identified that indolylphenylacetylene, 14, may be a good lead for further structural modification to develop a useful Abeta plaque imaging agent.

A Semiautomated Method for Quantification of F 18 Florbetapir PET Images.

UNLABELLED: PET amyloid imaging is increasingly used in research trials related to Alzheimer disease and has potential as a quantitative biomarker. This study had 3 objectives: first, to describe a semiautomated quantitative method that does not require subject-specific MR imaging scans for estimating F 18 Florbetapir plaque binding using 10-min PET images; second, to evaluate the method's accuracy for identifying positive and negative scans; and third, to correlate derived standardized uptake value ratios to neuropathologic measures of amyloid. METHODS: The F 18 Florbetapir PET images are initially converted to Montreal Neurologic Institute brain atlas space using an internally developed PET target F 18 Florbetapir template. Subsequently, a single mean cortical standardized uptake value ratio (mcSUVr) is calculated from the mean standardized uptake value of 6 cortical regions normalized to a reference region. Four reference regions were explored: whole cerebellum, cerebellar gray matter, pons, and centrum semiovale. The performance of the resultant mcSUVrs were evaluated in 74 young cognitively normal subjects (age < 50 y) with a negligible likelihood of amyloid ß pathology, and in 59 deceased subjects with autopsy-based amyloid ß neuritic plaque measure who underwent F 18 Florbetapir PET imaging before death. RESULTS: Significant correlations were obtained between mcSUVrs and 3 different pathologic measures of amyloid deposition at autopsy using all 4 reference regions, with the whole-cerebellum mcSUVr correlating most strongly across pathologic measures (r = 0.71-0.75, P < 0.0001). Using the whole-cerebellum mcSUVr and a threshold mcSUVr of less than 1.10, 100% of young cognitively normal subjects were correctly classified as amyloid-negative (mcSUVr range, 0.87-1.08). Similarly, 20 of 20 autopsy-negative subjects showed mcSUVrs of 1.10 or less, whereas 38 of 39 pathology-verified amyloid-positive subjects had mcSUVrs of more than 1.10. CONCLUSION: This semiautomated F 18 Florbetapir PET quantification method yielded mcSUVrs that significantly correlated with measures of amyloid pathology at autopsy. The method also effectively discriminated autopsy-identified amyloid-positive and -negative cases using a whole-cerebellum mcSUVr threshold of 1.10.

Detection of amyloid plaques by radioligands for Abeta40 and Abeta42: potential imaging agents in Alzheimer's patients.

Alzheimer s disease (AD) is linked to increased brain deposition of amyloid-beta (Abeta) peptides in senile plaques (SPs), and recent therapeutic efforts have focused on inhibiting the production or enhancing the clearance of Abeta in brain. However, it has not been possible to measure the burden of SPs or assess the effect of potential therapies on brain Abeta levels in patients. Toward that end, we have developed a novel radioligand, [(125)I]TZDM, which binds Abeta fibrils with high affinity, crosses the blood-brain barrier (BBB), and labels amyloid plaques in vivo. Compared to a styrylbenzene probe, [(125)I]IMSB, [(125)I]TZDM showed a 10-fold greater brain penetration and labeled plaques with higher sensitivity for in vivo imaging. However, this ligand also labels white matter, which contributes to undesirable high background regions of the brain. Interestingly, parallel to their differential binding characteristics onto fibrils composed of 40 (Abeta40)- or 42 (Abeta42)-amino-acid-long forms of Abeta peptides, these radioligands displayed differential labeling of SPs in AD brain sections under our experimental conditions. It was observed that [(125)I]IMSB labeled SPs containing Abeta40, amyloid angiopathy (AA), and neurofibrillary tangles, whereas [(125)I]TZDM detected only SPs and Abeta42-positive AA. Since increased production and deposition of Abeta42 relative to Abeta40 may be crucial for the generation of SPs, [(125)I]TZDM and related derivatives may be more attractive probes for in vivo plaque labeling. Further structural modifications of TZDM to lower the background labeling will be needed to optimize the plaque-labeling property.