bioTARGET · Bioorthogonal Cascade-Targeting: Directing Drugs into Cells with Molecular Precision

Bioorthogonal chemistries cross the boundaries between static chemical connectivity and the dynamic physiologic regulation of molecular state, enabling powerful tools for molecular control in complex biological environments. In combination with ligand-directed drug delivery, safe and selective chemical reactions that perform efficiently in vivo can fuel the design of new therapeutic strategies. Despite significant progress in the field of drug targeting, it remains challenging to shuttle therapeutic agents to the desired tissue, reaching the necessary cellular and even sub-cellular level, all while avoiding collateral damage. To engage this challenge, I aim to develop the concept of bioorthogonal cascade-targeting to direct the recognition, activation, and intracellular delivery of therapeutic constructs with molecular precision. We will develop next-level chemical tools for bioorthogonal bond-cleavage with exceptional reaction performance and the unique capability of tunable sequential release events (‘tandem release’). These innovations will enable us to design bioorthogonally activatable ligands for multiple therapeutic approaches that open new ground, most notably in escalating the complexity of (bio)chemical choreography. In particular, I propose cascade-processes, triggered by a single biocompatible click event, that can achieve: (i) the ‘bridging’ of non-internalizing cell-surface receptors to forward therapeutics into cells; (ii) the ‘hopping’ of drug conjugates from one target to another, or from one cell to another; and (iii) kinetically preprogrammed ‘escape’ of drugs from the endosomal compartment of cells entered via cascade-targeting. This will allow us to spatially and temporally control the movement and release of therapeutics in a (sub)cellular environment, and ultimately to establish bioorthogonal cascades as unique strategies that shift the paradigm of biologically controlled drug delivery.