Alzheimer's disease-related biomarkers and cancer-related cognitive decline: the thinking and living with cancer study.

PURPOSE: We evaluated whether plasma Alzheimer's Disease (AD)-related biomarkers were associated with cancer-related cognitive decline (CRCD) among older breast cancer survivors. METHODS: We included survivors 60-90 years with primary stage 0-III breast cancers (n = 236) and frequency-matched non-cancer controls (n = 154) who passed a cognitive screen and had banked plasma specimens. Participants were assessed at baseline (pre-systemic therapy) and annually for up to 60-months. Cognition was measured using tests of attention, processing speed and executive function (APE) and learning and memory (LM); perceived cognition was measured by the FACT-Cog PCI. Baseline plasma neurofilament light (NfL), glial fibrillary acidic protein (GFAP), beta-amyloid 42/40 (Aß42/40) and phosphorylated tau (p-tau181) were assayed using single molecule arrays. Mixed models tested associations between cognition and baseline AD-biomarkers, time, group (survivor vs control) and their two- and three-way interactions, controlling for age, race, WRAT4 Word Reading score, comorbidity and BMI; two-sided 0.05 p-values were considered statistically significant. RESULTS: There were no group differences in baseline AD-related biomarkers except survivors had higher baseline NfL levels than controls (p = .013). Survivors had lower adjusted longitudinal APE than controls starting from baseline and continuing over time (p = <0.002). However, baseline AD-related biomarker levels were not independently associated with adjusted cognition over time, except controls had lower APE scores with higher GFAP levels (p = .008). CONCLUSION: The results do not support a relationship between baseline AD-related biomarkers and CRCD. Further investigation is warranted to confirm the findings, test effects of longitudinal changes in AD-related biomarkers and examine other mechanisms and factors affecting cognition pre-systemic therapy.

Resveratrol differentially affects MMP-9 release from neurons and glia; implications for therapeutic efficacy.

Resveratrol, a naturally occurring polyphenol that activates sirtuin 1 (SIRT1), has been shown to reduce overall levels of matrix metalloprotease-9 (MMP-9) in cerebrospinal fluid (CSF) samples from patients with Alzheimer's dementia (AD). Depending on the site of release, however, MMP-9 has the potential to improve or impair cognition. In particular, its release from microglia or pericytes proximal to the blood brain barrier can damage the basement membrane, while neuronal activity-dependent release of this protease from glutamatergic neurons can instead promote dendritic spine expansion and long-term potentiation of synaptic plasticity. In the present study, we test the hypothesis that resveratrol reduces overall MMP-9 levels in CSF samples from patients with APOE4, an allele associated with increased glial inflammation. We also examine the possibility that resveratrol reduces inflammation-associated MMP release from cultured glia but spares neuronal activity-dependent release from cultured cortical neurons. We observe that resveratrol decreases overall levels of MMP-2 and MMP-9 in CSF samples from AD patients. Resveratrol also reduces CSF levels of tissue inhibitor of metalloproteinases-1 (TIMP-1), glial-derived protein that restricts long-term potentiation of synaptic transmission, in individuals homozygous for APOE4. Consistent with these results, we observe that resveratrol reduces basal and lipopolysaccharide (LPS)-stimulated MMP and TIMP-1 release from cultured microglia and astrocytes. In contrast, however, resveratrol does not inhibit release of MMP-9 from cortical neurons. Overall, these results are consistent with the possibility that while resveratrol reduces potentially maladaptive MMP and TIMP-1 release from activated glia, neuroplasticity-promoting MMP release from neurons is spared. In contrast, resveratrol reduces release of neurocan and brevican, extracellular matrix components that restrict neuroplasticity, from both neurons and glia. These data underscore the diversity of resveratrol's actions with respect to affected cell types and molecular targets and also suggest that further studies may be warranted to determine if its effects on glial MMP release could make it a useful adjunct for AD- and/or anti-amyloid therapy-related damage to the blood brain barrier.

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.