Drug Development

Area of Science:

• Neuroscience
• Proteomics
• Biomarker Discovery

Background:

• Alzheimer's disease (AD) presents significant molecular heterogeneity, complicating treatment development.
• Understanding AD subtypes is crucial for developing effective therapies and improving patient outcomes.
• Previous research identified five distinct AD molecular subtypes based on protein alterations.

Purpose of the Study:

• To validate the identified AD molecular subtypes in an independent cohort of early AD patients from a clinical trial.
• To assess the replicability of previously defined AD subtypes using cerebrospinal fluid (CSF) proteomic data.
• To investigate the amyloid specificity of these molecular subtypes.

Main Methods:

• Cerebrospinal fluid (CSF) samples from 202 individuals (101 amyloid-positive, 101 amyloid-negative) in a Phase 3 elenbecestat trial were analyzed.
• 16-plex tandem mass tag (TMT) mass spectrometry was employed for protein analysis.
• A random forest classifier, trained on a discovery cohort, was used to classify individuals into one of the five AD subtypes.

Main Results:

• All five AD molecular subtypes were identified in the amyloid-positive group.
• The distribution of subtypes included hyperplasticity (s1, 44%), innate immune activation (s2, 20%), RNA dysregulation (s3, 1%), choroid plexus dysfunction (s4, 18%), and blood-brain barrier dysfunction (s5, 17%).
• Protein level comparisons largely replicated previous findings, with SMOC1 levels significantly higher in amyloid-positive individuals.

Conclusions:

• The successful replication of the five AD molecular subtypes in an independent clinical cohort validates their robustness.
• These findings support the potential for developing personalized medicine approaches for Alzheimer's disease.
• The identified subtypes pave the way for novel combination therapy strategies in AD treatment.