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PATH30003- Frontiers in Human Disease > Lecture 7- Translational applications > Flashcards

Lecture 7- Translational applications Flashcards

1
Q

drug development phases

A

phase 1- healthy volunteers, safety and dosage
phase 2- small no. patients, effectiveness, side effects
phase 3- more patients, effectiveness, adverse reactions
phase 4-additional post-marketing testing

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2
Q

biomarkers

A

can help diagnose pre-symptomatic cases

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3
Q

tau CSF- biomarker

A

CSF tau- increased (dying neurons release extracellularly)

  • higher concentration= greater cognitive impairment in normal-MCI-AD spectrum
  • increased CSF tau not specific for AD
  • similar increase not seen in pure tauopathies, indicate role of Abeta
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4
Q

CSF Abeta- biomarker

A

CSF abeta- decreases over time

  • Abeta42 aggregated, retained within brain, not released in soluble form into CSF
  • low concentrations would match clinical diagnosis of AD
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5
Q

molecular neuroimaging- biomarker

A

study normal brain function, early disease states, longitudinal studies, treatment response

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6
Q

PET (positron emission tomography)

A

inject chemical ligand labelled with radio isotope, detects gamma rays

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7
Q

PiB

A

PET ligand for amyloid; cross BBB, bind to amyloid, detect amyloid

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8
Q

PET signal and braak staging

A

correlation- Abeta deposition/plaque location progressed

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9
Q

Abeta burden in dementia in AD, HC, MCI

A

AD- SUVR above cutoff, PiB positive–>Abeta burden
HC- SUVR below cutoff, PiB positive; pre clinical cases?
MCI- PiB positive (non memory MCI), PiB negative (amnestic MCI)

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10
Q

SUVR

A

standardised uptake value ratio

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11
Q

ApoE4 and PiB signal

A

higher PiB signal

-higher SUVR score, E4 is a risk factor for AD, greater amyloid deposition

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12
Q

neurogenetic testing

A

identify gene mutations, must be done with genetic counselling

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13
Q

genetic stratification

A

very important if you know who to treat, easier during drug trials

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14
Q

Parkinsons disease treating dopaminergic pathway

A

L-dopa
MAO-B inhibitors
dopamine agonists
anti-cholinergic drugs- interfere with production/uptake of ACh–>reduces tremors and muscle stiffness

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15
Q

cholinergic pathway

A

project to thalamus

important role in working memory, conscious awareness and attention

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16
Q

AChesterase inhibitors (Aricept)

A

enhances cholinergic activity (since inhibiting breakdown of ACh)

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17
Q

5 drug targets

A 
alpha secretase activator
anti-oxidant
neuroprotectants
anti inflammatory 
tau aggregation inhibitor
18
Q

tramiprosate (homotaurine)

A

sulfated glycosaminoglycan mimetic

  • oligomerisation inhibitor
  • maintain Abeta in non-fibrillar form
  • reduces Abeta42 induced cell death
  • transgenic mice- reduced amyloid plaque and soluble/insoluble Abeta 40/42 levels
  • clinical trials- failed to improve cognitive performance
19
Q

MPACs

A

metal protein attentuating compounds- targets metals bound to Abeta
- e.g. Clioquinol, PBT2

20
Q

Abeta, metals and async

A

Abeta interacts with metals, drive async toxicity

21
Q

clioquinol

A
  • chelates Zn and Cu, disaggregation of amyloid into smaller pieces of Abeta
  • crosses the BBB
  • small phase 2 human trial -reduction in amyloid load
22
Q

PBT2

A

follow up MPAC to clioquinol

  • oxygen and nitrogen groups provide chelating properties
  • phase 2a trial- positive outcomes
  • global financial crisis- not even funds, trial design wrong
23
Q

semagacestat (eli lilly)

A

gamma secretase inhibitor

24
Q

gamma secretase inhibitor

A

semagacestat (eli lilly)

  • lowered plasma, CSF and brain Abeta in animals
  • lower CSF and plasma Abeta in humans
  • changed both Abeta40/42 levels
  • phase 3 trials- NO slow AD progression, caused worsening of clinical measures of cognition
  • side effects- increased incidence of skin cancers, infections
25
Q

problem with gamma secretase inhibitors

A

non selective

- cleaver other proteins as well e.g. NOTCH0- important protein

26
Q

anti-Abeta vaccines for AD

A
  • only seen as theoretical before someone did it
    Approach
  • immunize AD mouse model with Abeta antigen
    Result
  • reduction in amyloid plaques, and Abeta levels
    -Abs also crossed BBB
27
Q

vaccine in active immunisation against AD

A

AN1792- aggregated Abeta42 peptide antigen
-phase 2a trial- patients immunized
-no significant differences between Ab responder and placebo groups
-trials stopped- meningoencephalitis in 6% patients-T cell activation
- some patients long term followup
-Mean Abeta load 5 years later decreased
-NO evidence for improved survival or improvement in time to severe dementia
Ie- reduced amyloid plaque but no effect on progression of neurodegeneration

28
Q

3 vaccines for passive immunisation for AD

A

preformed purified Abs
1- Bapineuzumab
2- Solanezumab
3- Aducanumab

29
Q

Bapineuzumab

A

binds both soluble and fibrillary Abeta

  • reduced amyloid burden in transgenic mice
  • trials not promising results
  • phase 3 trials- failed in AD patients with or without ApoE4 allele
30
Q

Solanezumab

A

preferentially binds soluble Abeta

  • mouse model- reversed memory deficits without affecting brain Abeta load
  • phase 2 trials- increased plasma and CSF levels of Abeta40/42- GOOD- plaque load decreasing
  • no effect on behavioural outcomes (cognition)
  • phase 3 trials- primary endpoints (congitive, functional) NOT met
  • secondary analysis - modest slowing in cognitive decline
31
Q

Aducanumab

A

binds soluble oligomers and insoluble fibrils

  • included PET imaging of amyloid
  • phase 1b trial- reduced amyloid levels, slowed down cognitive decline
  • but not powered enough to determine effect on cognition
  • did bigger trials- no robust change
32
Q

anti async Ab

A

Antibody- Syn303

  • wire hang test- motor performance
  • did better with Syn303
  • decreases number of async aggregates
  • increases survival of TH positive neurons (dopaminergic)
33
Q

Syn303

A

anti asynuclein Ab

34
Q

Syn506

A

Ab that recognises misfolded async found in LBs

35
Q

anti tau Ab

A

Ab- HJ8.5

  • P301S transgenic mice
  • increases in plasma tau levels, decrease in phospho-tau (hitting its target)
  • improves motor function
36
Q

3 mechanisms of Ab mediated therapeutics

A

1- microglial phagocytosis
2- catalytic disaggregation
3- peripheral sink mechanism

37
Q

microglial phagocytosis

A

microglial recruitment to opsonised Abeta

- Fc receptor mediated phagocytosis `

38
Q

catalytic disaggregation

A

Abs binds to fibrillar Abeta

- solubilisation of Abeta fibrils, neutralise/disaggregate

39
Q

peripheral sink mechanism

A

Ab sequestering to circulating Abeta in periphery

-increased efflux from parenchyma to blood system

40
Q

failure of major clinical trials

A
  • actual mouse models not true representation
  • drug target no longer critical for pathogenic/clinical phenotype
  • treating subjects too advanced in the disease pathway

PATH30003- Frontiers in Human Disease (20 decks)

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