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Background: Greater subjective cognitive changes on the Cognitive Function Index (CFI) was previously found to be associated with elevated amyloid (Aß) status in participants screening for the A4 Study, reported by study partners and the participants themselves. While the total score on the CFI related to amyloid for both sources respectively, potential differences in the specific types of cognitive changes reported by either participants or their study partners was not investigated., Objectives: To determine the specific types of subjective cognitive changes endorsed by participants and their study partners that are associated with amyloid status in individuals screening for an AD prevention trial., Design, Setting, Participants: Four thousand four hundred and eighty-six cognitively unimpaired (CDR=0; MMSE 25-30) participants (ages 65-85) screening for the A4 Study completed florbetapir (Aß) Positron Emission Tomography (PET) imaging. Participants were classified as elevated amyloid (Aß+; n=1323) or non-elevated amyloid (Aß-; n=3163)., Measurements: Prior to amyloid PET imaging, subjective report of changes in cognitive functioning were measured using the CFI (15 item questionnaire; Yes/Maybe/No response options) and administered separately to both participants and their study partners (i.e., a family member or friend in regular contact with the participant). The impact of demographic factors on CFI report was investigated. For each item of the CFI, the relationship between Aß and CFI response was investigated using an ordinal mixed effects model for participant and study partner report., Results: Independent of Aß status, participants were more likely to report 'Yes' or 'Maybe' compared to the study partners for nearly all CFI items. Older age (r= 0.06, p<0.001) and lower education (r=-0.08, p<0.001) of the participant were associated with higher CFI. Highest coincident odds ratios related to Aß+ for both respondents included items assessing whether 'a substantial decline in memory' had occurred in the last year (ORsp= 1.35 [95% CI 1.11, 1.63]; ORp= 1.55 [95% CI 1.34, 1.79]) and whether the participant had 'seen a doctor about memory' (ORsp= 1.56 [95% CI 1.25, 1.95]; ORp =1.71 [95% CI 1.37, 2.12]). For two items, associations were significant for only study partner report; whether the participant 'Repeats questions' (ORsp = 1.30 [95% CI 1.07, 1.57]) and has 'trouble following the news' (ORsp= 1.46[95% CI 1.12, 1.91]). One question was significant only for participant report; 'trouble driving' (ORp= 1.25 [95% CI 1.04, 1.49])., Conclusions: Elevated Aβ is associated with greater reporting of subjective cognitive changes as measured by the CFI in this cognitively unimpaired population. While participants were more likely than study partners to endorse change on most CFI items, unique CFI items were associated with elevated Aß for participants and their study partners, supporting the value of both sources of information in clinical trials., Competing Interests: R. Amariglio has nothing to disclose. J. Grill has nothing to disclose. D. Rentz has nothing to disclose. G Marshall reports personal fees and institutional support from Eisai Inc., institutional support from Eli Lilly and Company, Janssen Alzheimer Immunotherapy, Novartis, and Genentech, and personal fees from Grifols Shared Services North America, Inc, Pfizer outside the submitted work. R. Buckley has nothing to disclose. R. Yaari reports personal fees from Eli Lilly and Company during the conduct of the study. R. Raman reports grants from NIA, grants from Eli Lilly during the conduct of the study, grants from Janssen and grants from Eisai, outside the submitted work. CK. Sun reports grants from NIA and grants from Eli Lilly and Company during the conduct of the study. J. Sims he is an employee and stock holder of Eli Lilly and Company outside the submitted work. M. Donohue reports grants from NIH, grants and personal fees from Eli Lilly and Company during the conduct of the study, personal fees from Roche, personal fees from Biogen, personal fees from Neurotrack, other from Janssen, personal fees from Vivid Genomics outside the submitted work. P. Aisen reports grants from Janssen, grants from NIA, grants from FNIH, grants from Alzheimer’s Association, grants from Eisai, personal fees from Merck, personal fees from Biogen, personal fees from Roche, personal fees from Lundbeck, personal fees from Proclara, personal fees from Immunobrain Checkpoint outside the submitted work. K. Holdrige reports she is an employee and minor stockholder of Eli Lilly and Company. S Sikkes reports grants from Zon-MW OffRoad, grants from EU-JPND, institutional support from Lundbeck, Boehringer, and Toyama outside the submitted work. Dr. Gatchel reports grants from Alzheimer’s Association, grants from NIH/NIA, personal fees from Huron , grants from Merck , outside the submitted work.

Background: Donanemab (LY3002813) is an IgG1 antibody directed at an N‑terminal pyroglutamate of amyloid beta epitope that is present only in brain amyloid plaques., Objectives: To assess effects of donanemab on brain amyloid plaque load after single and multiple intravenous doses, as well as pharmacokinetics, safety/tolerability, and immunogenicity., Design: Phase 1b, investigator- and patient-blind, randomized, placebo-controlled study., Setting: Patients recruited at clinical research sites in the United States and Japan., Participants: 61 amyloid plaque-positive patients with mild cognitive impairment due to Alzheimer's disease and mild-to-moderate Alzheimer's disease dementia., Intervention: Six cohorts were dosed with donanemab: single dose 10-, 20- or 40- mg/kg (N = 18), multiple doses of 10-mg/kg every 2 weeks for 24 weeks (N = 10), and 10- or 20-mg/kg every 4 weeks for 72 weeks (N=18) or placebo (N = 15)., Measurements: Brain amyloid plaque load, using florbetapir positron emission tomography, was assessed up to 72 weeks. Safety was evaluated by occurrence of adverse events, magnetic resonance imaging, electrocardiogram, vital signs, laboratory testing, neurological monitoring, and immunogenicity., Results: Treatment with donanemab resulted in rapid reduction of amyloid, even after a single dose. By 24 weeks, amyloid positron emission tomography mean changes from baseline for single donanemab doses in Centiloids were: -16.5 (standard error 11.22) 10-mg/kg intravenous; 40.0 (standard error 11.23) 20 mg/kg intravenous; and -49.6 (standard error 15.10) 40-mg/kg intravenous. Mean reduction of amyloid plaque in multiple dose cohorts by 24 weeks in Centiloids were: 55.8 (standard error 9.51) 10-mg/kg every 2 weeks; -50.2 (standard error 10.54) 10-mg/kg every 4 weeks; and -58.4 (standard error 9.66) 20-mg/kg every 4 weeks. Amyloid on average remained below baseline levels up to 72 weeks after a single dose of donanemab. Repeated dosing resulted in continued florbetapir positron emission tomography reductions over time compared to single dosing with 6 out of 28 patients attaining complete amyloid clearance within 24 weeks. Within these, 5 out of 10 patients in the 20 mg/kg every 4 weeks cohort attained complete amyloid clearance within 36 weeks. When dosing with donanemab was stopped after 24 weeks of repeat dosing in the 10 mg every 2 weeks cohort, florbetapir positron emission tomography reductions were sustained up to 72 weeks. For the single dose cohorts on day 1, dose proportional increases in donanemab pharmacokinetics were observed from 10 to 40 mg/kg. Dose proportional increases in pharmacokinetics were also observed at steady state with the multiple dose cohorts. Donanemab clearance was comparable across the dose levels. Mean donanemab elimination-half-life following 20 mg/kg single dose was 9.3 days with range of 5.6 to 16.2 days. Greater than 90% of patients had positive treatment-emergent antidrug antibodies with donanemab. However, overall, the treatment-emergent antidrug antibodies did not have a significant impact on pharmacokinetics. Donanemab was generally well tolerated. Amongst the 46 participants treated with donanemab, the following amyloid-related imaging abnormalities, common to the drug class, were observed: 12 vasogenic cerebral edema events (12 [19.7%] patients), 10 cerebral microhemorrhage events (6 [13.0%] patients), and 2 superficial siderosis events (2 [4.3%] patients)., Conclusions: Single and multiple doses of donanemab demonstrated a rapid, robust, and sustained reduction up to 72 weeks in brain amyloid plaque despite treatment-emergent antidrug antibodies detected in most patients. Amyloid-related imaging abnormalities were the most common treatment-emergent event., Competing Interests: JLD – previous employee and minor stockholder of Eli Lilly and Company; currently at Indiana University School of Medicine. All other authors are employees and minor stockholders of Eli Lilly and Company.