Browsing by Author "Dean, Robert A."

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    The Alzheimer's Disease Neuroimaging Initiative 2 Biomarker Core: A review of progress and plans
    (Elsevier, 2015-07) Kang, Ju-Hee; Korecka, Magdalena; Figurski, Michal J.; Toledo, Jon B.; Blennow, Kaj; Zetterberg, Henrik; Waligorska, Teresa; Brylska, Magdalena; Fields, Leona; Shah, Nirali; Soares, Holly; Dean, Robert A.; Vanderstichele, Hugo; Petersen, Ronald C.; Aisen, Paul S.; Saykin, Andrew J.; Weiner, Michael W.; Trojanowski, John Q.; Shaw, Leslie M.; Alzheimer's Disease Neuroimaging Initiative; Department of Radiology and Imaging Sciences, School of Medicine
    INTRODUCTION: We describe Alzheimer's Disease Neuroimaging Initiative (ADNI) Biomarker Core progress including: the Biobank; cerebrospinal fluid (CSF) amyloid beta (Aβ1-42), t-tau, and p-tau181 analytical performance, definition of Alzheimer's disease (AD) profile for plaque, and tangle burden detection and increased risk for progression to AD; AD disease heterogeneity; progress in standardization; and new studies using ADNI biofluids. METHODS: Review publications authored or coauthored by ADNI Biomarker core faculty and selected non-ADNI studies to deepen the understanding and interpretation of CSF Aβ1-42, t-tau, and p-tau181 data. RESULTS: CSF AD biomarker measurements with the qualified AlzBio3 immunoassay detects neuropathologic AD hallmarks in preclinical and prodromal disease stages, based on CSF studies in non-ADNI living subjects followed by the autopsy confirmation of AD. Collaboration across ADNI cores generated the temporal ordering model of AD biomarkers varying across individuals because of genetic/environmental factors that increase/decrease resilience to AD pathologies. DISCUSSION: Further studies will refine this model and enable the use of biomarkers studied in ADNI clinically and in disease-modifying therapeutic trials.
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    Florbetapir positron emission tomography and cerebrospinal fluid biomarkers
    (Elsevier, 2015-08) Hake, Ann Marie; Trzepacz, Paula T.; Wang, Shufang; Yu, Peng; Case, Michael; Hochstetler, Helen; Witte, Michael M.; Degenhardt, Elisabeth K.; Dean, Robert A.; Department of Neurology, IU School of Medicine
    BACKGROUND: We evaluated the relationship between florbetapir-F18 positron emission tomography (FBP PET) and cerebrospinal fluid (CSF) biomarkers. METHODS: Alzheimer's Disease Neuroimaging Initiative-Grand Opportunity and Alzheimer's Disease Neuroimaging Initiative 2 (GO/2) healthy control (HC), mild cognitive impairment (MCI), and Alzheimer's disease (AD) dementia subjects with clinical measures and CSF collected ±90 days of FBP PET data were analyzed using correlation and logistic regression. RESULTS: In HC and MCI subjects, FBP PET anterior and posterior cingulate and composite standard uptake value ratios correlated with CSF amyloid beta (Aβ1-42) and tau/Aβ1-42 ratios. Using logistic regression, Aβ1-42, total tau (t-tau), phosphorylated tau181P (p-tau), and FBP PET composite each differentiated HC versus AD. Aβ1-42 and t-tau distinguished MCI versus AD, without additional contribution by FBP PET. Total tau and p-tau added discriminative power to FBP PET when classifying HC versus AD. CONCLUSION: Based on cross-sectional diagnostic groups, both amyloid and tau measures distinguish healthy from demented subjects. Longitudinal analyses are needed.
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    The impact of preanalytical variables on measuring cerebrospinal fluid biomarkers for Alzheimer's disease diagnosis: A review
    (Elsevier, 2018) Hansson, Oskar; Mikulskis, Alvydas; Fagan, Anne M.; Teunissen, Charlotte; Zetterberg, Henrik; Vanderstichele, Hugo; Molinuevo, Jose Luis; Shaw, Leslie M.; Vandijck, Manu; Verbeek, Marcel M.; Savage, Mary; Mattsson, Niklas; Lewczuk, Piotr; Batrla, Richard; Rutz, Sandra; Dean, Robert A.; Blennow, Kaj; Pathology and Laboratory Medicine, School of Medicine
    Introduction Cerebrospinal fluid (CSF) biomarkers have the potential to improve the diagnostic accuracy of Alzheimer's disease, yet there is a lack of harmonized preanalytical CSF handling protocols. Methods This systematic review summarizes the current literature on the influence of preanalytical variables on CSF biomarker concentration. We evaluated the evidence for three core CSF biomarkers: β-amyloid 42, total tau, and phosphorylated tau. Results The clinically important variables with the largest amount of conflicting data included the temperature at which samples are stored, the time nonfrozen samples can be stored, and possible effects of additives such as detergents, blood contamination, and centrifugation. Conversely, we discovered that there is consensus that tube material has a significant effect. Discussion A unified CSF handling protocol is recommended to reduce preanalytical variability and facilitate comparison of CSF biomarkers across studies and laboratories. In future, experiments should use a gold standard with fresh CSF collected in low binding tubes.
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    An integrated multi-study analysis of intra-subject variability in cerebrospinal fluid amyloid-β concentrations collected by lumbar puncture and indwelling lumbar catheter
    (BioMed Central, 2015-07-29) Lucey, Brendan P.; Gonzales, Celedon; Das, Ujjwas; Li, Jinhe; Siemers, Eric R.; Slemmon, J. Randall; Bateman, Randall J.; Huang, Yafei; Fox, Gerard B.; Claassen, Jurgen A.H.R.; Slats, Diane; Verbeek, Marcel M.; Tong, Gary; Soares, Holly; Savage, Mary J.; Kennedy, Matthew; Forman, Mark; Sjögren, Magnus; Margolin, Richard; Chen, Xia; Farlow, Martin R.; Dean, Robert A.; Waring, Jeffrey F.; Department of Neurology, IU School of Medicine
    INTRODUCTION: Amyloid-β (Aβ) has been investigated as a diagnostic biomarker and therapeutic drug target. Recent studies found that cerebrospinal fluid (CSF) Aβ fluctuates over time, including as a diurnal pattern, and increases in absolute concentration with serial collection. It is currently unknown what effect differences in CSF collection methodology have on Aβ variability. In this study, we sought to determine the effect of different collection methodologies on the stability of CSF Aβ concentrations over time. METHODS: Grouped analysis of CSF Aβ levels from multiple industry and academic groups collected by either lumbar puncture (n=83) or indwelling lumbar catheter (n=178). Participants were either placebo or untreated subjects from clinical drug trials or observational studies. Participants had CSF collected by lumbar puncture or lumbar catheter for quantitation of Aβ concentration by enzyme linked immunosorbent assay. Data from all sponsors was converted to percent of the mean for Aβ40 and Aβ42 for comparison. Repeated measures analysis of variance was performed to assess for factors affecting the linear rise of Aβ concentrations over time. RESULTS: Analysis of studies collecting CSF via lumbar catheter revealed tremendous inter-subject variability of Aβ40 and Aβ42 as well as an Aβ diurnal pattern in all of the sponsors' studies. In contrast, Aβ concentrations from CSF samples collected at two time points by lumbar puncture showed no significant differences. Repeated measures analysis of variance found that only time and draw frequency were significantly associated with the slope of linear rise in Aβ40 and Aβ42 concentrations during the first 6 hours of collection. CONCLUSIONS: Based on our findings, we recommend minimizing the frequency of CSF draws in studies measuring Aβ levels and keeping the frequency standardized between experimental groups. The Aβ diurnal pattern was noted in all sponsors' studies and was not an artifact of study design. Averaging Aβ concentrations at each time point is recommended to minimize the effect of individual variability. Indwelling lumbar catheters are an invaluable research tool for following changes in CSF Aβ over 24-48 hours, but factors affecting Aβ concentration such as linear rise and diurnal variation need to be accounted for in planning study designs.
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    Sabirnetug (ACU193) Lowers CSF Levels of Synaptic Biomarkers in INTERCEPT‐AD Phase 1 Study in Early AD
    (Wiley, 2025-01-09) Cline, Erika N.; Johnson, Elizabeth; Sundell, Karen; Antwi-Berko, Daniel; Koel-Simmerlink, Marleen J. A.; Teunissen, Charlotte; Siemers, Eric; Zhang, Hao; Hyland, Maddelyn; Sethuraman, Gopalan; Vanderstichele, Hugo; Kaplow, June; Dean, Robert A.; Jerecic, Jasna; Pathology and Laboratory Medicine, School of Medicine
    Background: Sabirnetug (ACU193) is a humanized IgG2 antibody targeting soluble, synaptotoxic amyloid β oligomers (AβOs). AβOs accumulate in Alzheimer’s disease (AD) and induce pre‐ and post‐synaptic changes, resulting in dendritic spine loss, neuronal degeneration, and release of synaptic proteins into the CSF. Recently, we reported that three administrations of sabirnetug in an early AD population (INTERCEPT‐AD Phase 1 study, NCT04931459) significantly lowered CSF levels of the post‐synaptic protein neurogranin as well as pTau181. Here, we present data on additional CSF synaptic biomarkers and AD plasma biomarkers measured in INTERCEPT‐AD. Method: INTERCEPT‐AD was a randomized, placebo‐controlled study with two parts: single ascending dose (SAD) randomized in a 6:2 ratio to sabirnetug (2, 10, 25, 60 mg/kg) or placebo and multiple ascending dose (MAD) randomized 8:2 to sabirnetug (three administrations at 10 or 60 mg/kg every 4 weeks [Q4W] or 25 mg/kg Q2W) or placebo. Biomarkers were measured blinded in CSF and EDTA‐plasma, before and after drug administration, by Amsterdam UMC. Result: CSF levels of vesicle‐associated membrane protein 2 (VAMP2), a protein involved in pre‐ and post‐synaptic vesicle trafficking, were significantly normalized (lowered) in sabirnetug treated participants relative to placebo in all three MAD cohorts. Levels of the pre‐synaptic protein neuronal pentraxin 2 (NPTX2), which acts on post‐synaptic excitatory synapses, regulates complement activity, and lowers with cognitive decline, trended lower with sabirnetug than placebo. Plasma levels of GFAP, pTau181, and pTau217 trended towards normalization (lowering) of AD‐dependent changes in the 60 mg/kg Q4W cohort. Conclusion: In INTERCEPT‐AD, three administrations of sabirnetug lowered CSF levels of both pre‐ and post‐synaptic proteins, consistent with sabirnetug’s proposed mechanism of action to inhibit AβO synaptic binding. VAMP2 appeared most sensitive to sabirnetug in this study, lowering significantly in all three MAD cohorts; other markers previously reported to have a statistically significant response to sabirnetug ‐ neurogranin and pTau181 ‐ did so at the highest dose. No statistically significant changes in plasma biomarkers were observed in this short study. Long‐term changes in biomarker levels and their relationship to clinical efficacy will be evaluated in the 18‐month ALTITUDE‐AD phase 2 study of sabirnetug beginning in the first half of 2024.
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    Trial of Solanezumab for Mild Dementia Due to Alzheimer’s Disease
    (2018-01) Honig, Lawrence S.; Vellas, Bruno; Woodward, Michael; Boada, Mercè; Bullock, Roger; Borrie, Michael; Hager, Klaus; Andreasen, Niels; Scarpini, Elio; Liu‑Seifert, Hong; Case, Michael; Dean, Robert A.; Hake, Ann; Sundell, Karen; Hoffmann, Vicki Poole; Carlson, Christopher; Khanna, Rashna; Mintun, Mark; DeMattos, Ronald; Selzler, Katherine J.; Siemers, Eric; Pathology and Laboratory Medicine, School of Medicine
    BACKGROUND Alzheimer’s disease is characterized by amyloid-beta (Aβ) plaques and neurofibrillary tangles. The humanized monoclonal antibody solanezumab was designed to increase the clearance from the brain of soluble Aβ, peptides that may lead to toxic effects in the synapses and precede the deposition of fibrillary amyloid. METHODS We conducted a double-blind, placebo-controlled, phase 3 trial involving patients with mild dementia due to Alzheimer’s disease, defined as a Mini–Mental State Examination (MMSE) score of 20 to 26 (on a scale from 0 to 30, with higher scores indicating better cognition) and with amyloid deposition shown by means of florbetapir positron-emission tomography or Aβ1-42 measurements in cerebrospinal fluid. Patients were randomly assigned to receive solanezumab at a dose of 400 mg or placebo intravenously every 4 weeks for 76 weeks. The primary outcome was the change from baseline to week 80 in the score on the 14-item cognitive subscale of the Alzheimer’s Disease Assessment Scale (ADAS-cog14; scores range from 0 to 90, with higher scores indicating greater cognitive impairment). RESULTS A total of 2129 patients were enrolled, of whom 1057 were assigned to receive solanezumab and 1072 to receive placebo. The mean change from baseline in the ADAS-cog14 score was 6.65 in the solanezumab group and 7.44 in the placebo group, with no significant between-group difference at week 80 (difference, −0.80; 95% confidence interval, −1.73 to 0.14; P=0.10). As a result of the failure to reach significance with regard to the primary outcome in the prespecified hierarchical analysis, the secondary outcomes were considered to be descriptive and are reported without significance testing. The change from baseline in the MMSE score was −3.17 in the solanezumab group and −3.66 in the placebo group. Adverse cerebral edema or effusion lesions that were observed on magnetic resonance imaging after randomization occurred in 1 patient in the solanezumab group and in 2 in the placebo group. CONCLUSIONS Solanezumab at a dose of 400 mg administered every 4 weeks in patients with mild Alzheimer’s disease did not significantly affect cognitive decline.