Brain-restricted mTOR inhibition with binary pharmacology

Area of Science:

• Pharmacology
• Neuroscience
• Oncology

Background:

• On-target, off-tissue drug effects cause adverse events, limiting therapeutic applications.
• Central nervous system diseases require drugs with brain-specific activity to improve safety and efficacy.

Purpose of the Study:

• To develop a method for achieving brain-restricted inhibition of kinase targets, specifically mammalian target of rapamycin (mTOR).
• To mitigate systemic side effects associated with mTOR inhibitors while maintaining therapeutic efficacy.

Main Methods:

• Utilized a brain-permeable mTOR inhibitor (RapaLink-1) in combination with a brain-impermeable FKBP12 ligand (RapaBlock).
• Designed a generalizable method to create cell-permeable, FKBP12-dependent kinase inhibitors from existing drug scaffolds.
• Demonstrated sensitivity of designed inhibitors to RapaBlock for deactivation.

Main Results:

• The drug combination successfully mitigated systemic effects of mTOR inhibitors.
• RapaLink-1 efficacy was preserved in glioblastoma xenograft models.
• The developed inhibitors allow for brain-restricted kinase inhibition.

Conclusions:

• This strategy enables targeted drug action within the central nervous system, reducing off-target adverse events.
• The approach offers a versatile platform for developing brain-specific kinase inhibitors for various neurological diseases and cancers.