Pet-labeled cathepsin activity-based probes for studying lysosomal storage disorder therapies
Novel small-molecule probes that covalently bind lysosomal cathepsin proteases for PET imaging of lysosomes in lysosomal storage disorder (LSD) models. Built on a potent dipeptide electrophile core (IC50 < 1µM), these probes enable in vivo detection and monitoring of LSD therapies, with applications in Pompe and Gaucher disease research.
Overview
This research offers a library of small-molecule activity-based probes designed to bind lysosomal cysteine cathepsin proteases and enable PET imaging of lysosomes in the context of lysosomal storage disorder (LSD) therapies. Cathepsins B and L are ubiquitously active lysosomal enzymes, and compounds that covalently bind them accumulate and mark lysosomes in an activity-dependent manner. The probes are designed to retain their binding behavior even in LSD environments, where modest pH changes do not significantly alter cathepsin activity. By labeling these probes with PET radionuclide chelators, researchers and clinicians can non-invasively visualize and monitor lysosomal function, supporting the development and evaluation of LSD treatments such as those for Pompe and Gaucher disease.
Technical specifications
Core chemistry:
- Capped dipeptide scaffold linked to an electrophile, with molecular weight of approximately 573 Dalton
- Potency toward recombinant cathepsins with IC50 values below 1µM
- Compatible with multiple electrophile classes: covalent irreversible, covalent reversible, and non-covalent binding modes
Reporter tag options:
- Radionuclide attachment moieties including DOTA and DTPA chelators, free amine handles, and desferrioxamine (DFO) analogs for PET labeling
- Prior validated use with fluorescent and electron microscopy tags for cellular and in vivo detection
Validation capabilities:
- Tested for potency against recombinant cathepsins
- Assessed for cell permeability and lysosomal accumulation in primary cells
- Evaluated in normal, Pompe, and Gaucher mouse models to replace existing fluorescent lysosome labeling
Technology readiness level
The probe chemistry is supported by multiple high-impact publications and patents, including a patent on PET-labeled cathepsin probes. The team has demonstrated probe accumulation and retention in lysosomes using electron and fluorescent microscopy, and has recent unpublished data on potent reversible cathepsin probes. The next phase involves biochemical evaluation of a expanded probe library incorporating covalent reversible, covalent irreversible, and non-covalent variants with PET-compatible chelators, followed by testing in LSD mouse models. This positions the technology at an advanced preclinical stage with strong translational potential for imaging applications in LSD drug development.
About Hebrew University of Jerusalem
The Hebrew University of Jerusalem is a comprehensive public research university with multiple campuses in Jerusalem and an agricultural campus in Rehovot. Its integration with Hadassah’s university hospitals enables clinical studies, access to varied patient populations, and co‑located research that accelerates translation. Industry engagement runs through Yissum, the university’s tech‑transfer company, managing IP, licensing, startup creation, and sponsored research agreements. Research is supported by competitive national funding and international programs, including European Union frameworks.
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