On-Membrane Supramolecular Assemblies Serving as Bioorthogonal Gating for Melphalan

Covalent drugs have experienced a revival in recent decades due to their advantageous pharmacodynamic profiles and targeting of "undruggable" proteins. However, balancing selectivity, reactivity, and potency is essential for safe and effective drugs. Here, we employ a cell-selective bioorthogonal prodrug design to enhance the selectivity for covalent inhibitors without compromising the reactivity and potency. The upregulation of phosphatase and integrin facilitates the formation of enzyme-instructed supramolecular assemblies (EISA) on the cancer cell membrane. These assemblies localize bioorthogonal reaction handles tetrazine (Tz), which liberate Melphalan from its bioorthogonal prodrug TCO-Mel. The TCO modification disrupts the LAT1-mediated transportation, reducing cellular permeability of TCO-Mel and the corresponding cytotoxicity to normal cells. Although the cell-selective on-membrane assemblies directed prodrug activation restores Melphalan influx to inhibit cancer cell growth. This prodrug activation strategy further demonstrates potent tumor suppression with satisfactory biocompatibility in vivo. Overall, we extend the scope of bioorthogonal prodrug design for covalent drugs via regulating cellular influx of active pharmaceutical ingredients (APIs).