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From Mechanisms to Medicines: realizing the DREAM of an Alzheimer’s cure

Madhav Thambisetty, MD, PhD

Clinical and Translational Neuroscience Section

Laboratory of Behavioral Neuroscience

National Institute on Aging (NIA)

National Institutes of Health (NIH)

thambisettym@mail.nih.gov

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Outline

1. Why have we failed to find cures for Alzheimer’s disease (AD)?

2. Establishing a pipeline for identifying drug targets in AD through systems biology

Unbiased proteomics identifies an APOE ε4 associated signature of incipient AD and implicates cytokine signaling as a drug target

Phenotypic screening and efficacy studies of candidate AD drugs: PREVENT-AD study

Translating disease mechanisms to medicines: the DREAM study

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"A characteristic disease of the cerebral cortex” �(Über eine eigenartige Erkrankung der Hirnrinde, 1907

37th meeting of SouthWest German psychiatrists, Tübingen, Germany; 1906

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Alzheimer’s Disease: a lot learned but…

Rate of publication: >1000/month

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Little gained…

Drug Name	Brand Name	Approved for	FDA Approved
Donepezil	Aricept	All stages	1996
Rivastigmine	Exelon	All stages	2000
Galantamine	Razadyne	Mild-Moderate	2001
Memantine	Namenda	All stages	2003

“Researchers have already cast much darkness on the subject,

and if they continue their investigations, we shall soon know

nothing at all about it.”

**Aducanumab accelerated approval June 2021

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Clinical and Translational Neuroscience Section: Translating Biological mechanisms in AD to Drug Targets

Goal: Establish a flexible, scalable pipeline to identify targets for disease modification in ADRD.

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A flexible and scalable pipeline for drug discovery in ADRD

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A flexible and scalable pipeline for drug discovery in ADRD

Ongoing initiatives for target validation and drug discovery in AD in the NIA IRP

Supported by the Scientific Director’s ‘Special-AD’ mechanism from Congressional monies dedicated to ADRD

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Drug Repurposing for Effective Alzheimer’s Medicines (DREAM)

Two-year multi-center study for identifying novel repurposing candidates for AD leveraging both deep molecular phenotyping of human brain and blood and big-data analyses of real-world clinical outcomes

Centers of excellence in Pharmacoepidemiology at Harvard Medical School, Johns Hopkins University and Rutgers University

Two large real-world clinical datasets with over 20 million older individuals with clinical diagnoses and prescription data

Converging results from independent analyses will ensure reliability of findings and support their confirmation in RCTs of candidate AD treatments

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Drug Repurposing for Effective Alzheimer’s Medicines (DREAM)

Testing JAK/STAT signaling modulation in AD

R.Desai et al. Targeting Abnormal Metabolism in Alzheimer’s Disease: the Drug Repurposing for

Effective Alzheimer’s Medicines (DREAM) study. Alzheimer's & Dementia: Translational Research

& Clinical Interventions, 2020

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R.Desai et al. Targeting Abnormal Metabolism in Alzheimer’s Disease: the Drug Repurposing for

Effective Alzheimer’s Medicines (DREAM) study. Alzheimer's & Dementia: Translational Research

& Clinical Interventions, 2020

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Overcoming “uncertainties” in Pharmacoepidemiologic analyses

R.Desai et al. Targeting Abnormal Metabolism in Alzheimer’s Disease: the Drug Repurposing for

Effective Alzheimer’s Medicines (DREAM) study. Alzheimer's & Dementia: Translational Research

& Clinical Interventions, 2020

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��Specific Aim-1

Phenotypic drug screening

Preclinical Validation of Emerging Novel Treatments for Alzheimer’s Disease �(PREVENT-AD) STUDY

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��Specific Aim-2

Drug efficacy in transgenic mouse model

48 mice (5xFAD: n=32; WT: n=16)
27-week duration
Tx: intraperitoneal application 1/week
In-vivo blood sampling
Histologic processing

Cognitive performance

Amyloid plaques

Tau

tangles

Neuro-inflammation

Axonal damage

Preclinical Validation of Emerging Novel Treatments for Alzheimer’s Disease �(PREVENT-AD) STUDY

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A flexible and scalable pipeline for drug discovery in ADRD

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A Brain proteomic signature of incipient AD implicates �STAT3 as a drug target�

The ε4 allele of the apolipoprotein E gene (APOE) is the most robust risk factor for sporadic AD

APOE ε4 carriers have a dose-dependent increase in risk for AD and a lower age of onset (Genin 2011 & Sando 2008)

APOE ε4 likely confers risk prior to middle age and decades before age of AD onset: However, the mechanisms by which APOE ε4 confers risk decades prior to AD onset remains unknown

The promise of APOE-directed AD therapies remains unrealized

Jackson Roberts et al. A Brain Proteomic Signature of Incipient Alzheimer’s Disease in Young APOE ε4 Carriers identifies novel drug targets 2021 SCIENCE Advances

Jackson Roberts

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Understanding APOE ε4-associated AD risk to �identify plausible drug targets

Establish a proteomic signature of APOE ε4 carrier status in a young non-demented cohort (YAPS).

Determine which of these protein alterations are shared in AD in two older cohorts (ROS & BLSA) with neuropathologically confirmed cases of AD.

Explore this proteomic signature in association with ante-mortem cognitive trajectories, AD pathology, and biological functional categorization.

Test whether FDA-approved and experimental drugs that target abnormal signaling pathway(s) implicated in the APOE4-AD signature are AD treatments.

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STAT3 is an AD drug target: establishing a brain proteomic �signature of incipient AD

Jackson Roberts et al. A Brain Proteomic Signature of Incipient Alzheimer’s Disease in Young APOE ε4 Carriers identifies novel drug targets 2021 SCIENCE Advances

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Dr. Junmin Peng, St. Jude Children’s Research

Hospital, Memphis

Dr. Li-Huei Tsai, MIT, Boston

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Cytokine signaling through STAT3 is a druggable target

Drug	Indication	Status
Crizotinib	Lung cancer	FDA-approved
Napabucasin	Colorectal cancer	FDA-orphan status
TTI-101	Hepatocellular cancer	In ongoing phase-1 trials

Jackson Roberts et al. A Brain Proteomic Signature of Incipient Alzheimer’s Disease in Young APOE ε4 Carriers identifies novel drug targets 2021 SCIENCE Advances

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Does TTI-101 alter molecular outcomes relevant to AD?

Jackson Roberts et al. A Brain Proteomic Signature of Incipient Alzheimer’s Disease in Young APOE ε4 Carriers identifies novel drug targets 2021 SCIENCE Advances

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TTI-101 rescues multiple AD phenotypes

Lowers IL-6, IL-1β release

in BV-2 microglia

Lowers Aβ₄₂ secretion in hAPP

over-expressing H4 cells

Lowers p-Tau levels in hTau441

over-expressing Neuroblastoma

cells

Jackson Roberts et al. A Brain Proteomic Signature of Incipient Alzheimer’s Disease in Young APOE ε4 Carriers identifies novel drug targets 2021 SCIENCE Advances

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RAX 50 µM

MTX 50 nM

RAX 50 µM

MTX 50 nM

RAX 50 µM

MTX 50 nM

HMC3 (Microglia)

1321N1 (Astrocytes)

BE(2)-M17 (Neuroblasts)

p-STAT3 (Tyr705)

p-STAT3 (Ser727)

ACTB

STAT3

A commonly used RA drug (RAX) inactivates STAT3 in Microglia and Astrocytes

Interpretation: RAX inactivates STAT3 in microglia and astrocytes.

Dr. Carlos Anerillas, LGG

Dr. Myriam Gorospe, LGG

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Does RAX alter molecular outcomes relevant to AD?

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RAX rescues multiple AD phenotypes

Lowers TNF-α, IL-6, IL-1β release

in BV-2 microglia

Increases Aβ₄₂ clearance

in BV-2 microglia

Lowers p-Tau levels in hTau441

over-expressing Neuroblastoma

cells

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Does RAX rescue impaired hippocampal synaptic plasticity in �a transgenic AD model?��

Long-term potentiation (LTP) is a process involving persistent strengthening of synapses that leads to a long-lasting increase in signal transmission between neurons. It is an important process in the context of synaptic plasticity. LTP recording is widely recognized as a cellular model for the study of memory.

LTP is impaired in the APP/PS1 transgenic mouse model of AD

Rescue of impaired LTP is a relevant neurophysiological read-out of disease-modifying AD treatments

Dr. Sajikumar Sreedharan, NUS

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APP/PS1

Dr. Sheeja Navakkode (Electrophysiology), Dr. Wong Lik Wei (Western blots) Dr. Sajikumar Sreedharan, National University, Singapore

RAX rescues impaired LTP in the hippocampus of APP/PS1 mice

STAT3-I 50 μM

A. Scheme representing hippocampal slice with the location of two independent stimulating electrode and one recording electrode to stimulate and record late-LTP from CA1 pyramidal neurons. B. Typical late-LTP from APP/PS1 mice ( taken from Li et a.l, 2017, PMID: 28484012 ). C. Rescue of late-LTP by RAX (50 µM), applied 30 min before and 30 min after the induction of LTP by strong tetanization protocol (STET: 100 Hz, 100 pulses , 0.2 ms at 0’, 10’ and 20’ min) in synaptic input S1. S2 served as a control. X axis represents percentage of field excitatory post synaptic potentials (fEPSP) recorded from hippocampal CA1 pyramidal neurons from 4-5 months old male APP/PS1 mice. Y axis represents time in minutes. D. Late-LTP + 25 µM RAX. E. Typical late-LTP from Wild type (WT)mice F. Effects of RAX (50 µM) on late-LTP from WT mice. G. Effects of Mtx on late- LTP from APP/PS1 mice. ‘n’ represents number of slices.

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Drug Repurposing for Effective Alzheimer’s Medicines (DREAM)

Does RAX lower AD risk in real world clinical practice?

R.Desai et al. Targeting Abnormal Metabolism in Alzheimer’s Disease: the Drug Repurposing for

Effective Alzheimer’s Medicines (DREAM) study. Alzheimer's & Dementia: Translational Research

& Clinical Interventions, 2020

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RAX lowers cumulative incidence of AD by 8-16% in the DREAM study

RAX vs MTx

RAX; N=71,029 MTx; N=54,562

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RAX lowers cumulative incidence of AD by 8-16% in the DREAM study

RAX

MTx

RAX; N=71,029 MTx; N=54,562

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Conclusions

Elevated STAT3 signaling is a plausible AD drug target

An experimental STAT3 inhibitor (TTI-101) and the commonly used, FDA-approved RA-drug (RAX) rescue molecular phenotypes relevant to AD including neuroinflammation, Aβ clearance/secretion and tau phosphorylation.

RAX restores impaired synaptic plasticity in APP/PS1 mice and lowers AD risk in older individuals

These results suggest that STAT3 inhibition is a promising therapeutic target in AD and merits confirmation in RCTs.

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��Specific Aim-2

Drug efficacy in transgenic mouse model

48 mice (5xFAD: n=32; WT: n=16)
27-week duration
Tx: intraperitoneal application 1/week
In-vivo blood sampling
Histologic processing

Cognitive performance

Amyloid plaques

Tau

tangles

Neuro-inflammation

Axonal damage

Preclinical Validation of Emerging Novel Treatments for Alzheimer’s Disease �(PREVENT-AD) STUDY

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CARD Dementia Clinical Trials Unit, NIH Clinical Center

AV-1451

Proof-of-concept studies of promising ADRD drugs emerging from preclinical pipeline

Neuroimaging and fluid biomarkers as surrogate indicators of target engagement and efficacy

Experimental treatments moving imaging/fluid biomarkers therapeutic directions will be prioritized

for further confirmation in larger multi-center trials

Goal is to test at least 1 FDA-approved drug per year in the first 5 years.

Advance at least two experimental drugs in the first 5 years

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Continue to develop resources, capabilities and partnerships to advance data-driven drug repositioning and combination therapy

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Colleagues and collaborators

Unit of Clinical & Translational Neuroscience

Madhav Thambisetty

Vijay Varma

Sayantani Roy

Jackson Roberts

Jong Shin

Andrew Williamson

Laboratory of Behavioral Neuroscience

Susan Resnick (Chief)

Yang An

Lori Beason-Held

Melissa Kitner-Triolo

Longitudinal Studies Section

Luigi Ferrucci

Toshiko Tanaka

HiThru Analytics

Sudhir Varma

DREAM Study

Rishi Desai

Sebastian Schneeweiss

Tobias Gerhard

Jodi Segal

NIDDK

Priyanka Narayan

U Miss Medical Center

Michael Griswold

Chad Blackshear

Johns Hopkins University SOM

Marilyn Albert

Juan Troncoso

Olga Pletnikova

MIT

Li-Huei Tsai

Hansruedi Mathys

Manolis Kellis

Jose Davila Valderrain

St. Jude

Junmin Peng

Emory University

Allan Levey

Nicholas Seyfried

ROSMAP

David Bennett

Gregory Klein

NCI

Shahinaz Gadalla

Youjin Wang

Gebze Technical University, Kocaeli Turkey

Tunahan Çakır

H. Büşra Lüleci

KCL, London

Cristina Legido-Quigley

National University of Ireland

Anup Oommen

AMP-AD Consortium

Andrew & Lillian A. Posey Foundation

We are grateful to BLSA participants for their invaluable contributions

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