# Isoindolinone-Derived PET Tracers for Molecular Imaging of mHTT Aggregates in Huntington’s Disease

## TL;DR

Researchers developed improved PET tracers to detect harmful protein clumps in Huntington’s disease, offering better tools for studying the disease.

## Contribution

A new class of isoindolinone-derived PET tracers with enhanced binding and selectivity for mHTT aggregates was developed.

## Key findings

- Next-generation tracers like [11C]CHDI-009 and [18F]CHDI-385 show improved binding affinity and selectivity.
- These tracers offer better metabolic stability and translational potential compared to earlier versions.
- They provide noninvasive tools to quantify mHTT pathology in Huntington’s disease.

## Abstract

Mutant huntingtin (mHTT) aggregates represent a key pharmacodynamic
biomarker of Huntington’s disease (HD). The development of
positron emission tomography (PET) tracers targeting mHTT addresses
a critical unmet need by enabling the noninvasive quantification of
pathological burden in vivo. The first-generation
tracer, [11C]­CHDI-180R, a benzoxazole derivative, laid
the foundation for this effort. Subsequent analogs such as [11C]­CHDI-626 and [18F]­CHDI-650 were developed to improve in vivo performance; however, key challenges including limited
metabolic stability and suboptimal selectivity persisted. To address
these limitations, a recent study introduced a new class of isoindolinone-derived
candidate tracers, including [11C]­CHDI-009, [18F]­CHDI-385, and [18F]­CHDI-386, identified through systematic
structure–activity relationship (SAR) optimization. These next-generation
tracers exhibit markedly enhanced binding affinity, selectivity, and
translational potential, offering valuable tools to investigate mHTT
pathology and its role in HD progression.