Cisplatin-Triggered Bioorthogonal Decaging of Amide Bonds for Targeted-Drug Activation in vivo

Creating ways to control drug activation at specific tissues while sparing healthy tissues remains a major challenge. The administration of exogenous triggers offers the possibility for precise and traceless drug activation. However, ensuring localization of the trigger as well as the prodrug at the diseased tissue is complex while essential for therapeutic efficacy and to avoid side-toxicity. Cisplatin remains a first line option to treat 20% of all cancer patients and while clearing after 30 min from blood it concentrates in tumor tissues. Here, we demonstrate the use of the platinum-mediated bond cleavage of protected tertiary amides, which can occur in a catalytic manner under bioorthogonal conditions. Protected analogues of cytotoxic drugs 5-fluorouracil (5-FU) and monomethyl auristatin E (MMAE) were successfully activated using non-toxic amounts of platinum salts in cells. An otherwise fully stable and non-internalizing ADC built using a bifunctional linker featuring a tertiary amide protected MMAE was also bioorthogonally decaged in the presence of platinum salts for extracellular drug release. Finally, cisplatin-mediated activation of a prodrug 5-FU was shown in a colorectal zebrafish xenograft model leading to a significant tumor reduction. Considering cisplatin’s continued use as a first-choice treatment for many solid cancers and especially in colorectal cancer, we anticipate that our platinum-mediated decaging strategy will enhance cancer therapy by allowing tumor specific prodrug activation.