Dual-Enzyme Responsive Polymeric Micelles with Cascade Targeting and Caspase-3 Activated Drug Release for Tumor-Specific Chemotherapy.

Cancer, as a global health crisis, continues to threaten human life and health. Chemotherapy occupies a central position in cancer treatment, but conventional chemotherapeutic agents have some limitations, such as low solubility, lack of specific targeting, insufficient bioavailability and high toxicity to normal tissues. However, the use of DOX is associated with serious adverse effects, including cardiotoxicity and myelosuppression, which limit its effectiveness in antitumor therapy. To overcome these challenges, drug delivery systems (DDSs) have been developed, with polymeric micelles emerging as a highly promising option. In this study, we designed and synthesized a multistage enzyme-responsive amphiphilic molecule, mPEG-GFLGRGDEVD-DOX, for targeted cancer therapy through self-assembly into micelles. Upon cleavage of the GFLG by Cathepsin B, the micelles shed the mPEG crown, thereby exposing the active targeting peptide sequence RGD, which enhances micelle uptake by tumor cells. Concurrently, the DOX loaded in the micelles partially leaks out, inducing apoptosis and activating the apoptotic protease Caspase-3. Caspase-3 then cleaves the DEVD tail, facilitating the rapid intracellular release of the drug. This approach specifically highlights the innovative use of a dual-enzyme cascade (Cathepsin B and Caspase-3) to sequentially trigger tumor-specific drug release, overcoming the limitations of current clinical applications. The synergistic action of these enzymes enhances both drug release and selectivity, offering a promising strategy for improved cancer therapy.