Enzyme-sensitive peptide KC26 modifies milk exosomes encapsulating carboplatin for the treatment of retinoblastoma

Milk exosomes have also been widely used as emerging delivery vehicles for various therapeutic cargoes. Retinoblastoma (RB) is the most common primary intraocular malignancy of childhood. However, the therapeutic efficacy is severely hampered by the presence of blood–retinal barrier (BRB) and systemic side effects. Legumain (LGMN) can be used as a target for tumor microenvironment responsive delivery design and therapeutic applications. Here, a LGMN-sensitive peptide KC26-modified milk exosomes loaded with carboplatin (CBP-KC26-MExos). The system enables milk exosomes loaded with carboplatin (CBP) to reach the target cells by binding to LGMN, improves tumor targeting, enhances cellular uptake and apoptosis, inhibits cell proliferation, invasion and migration. Intravenous injection of CBP-KC26-MExos cross the BRB significantly inhibited intraocular tumor progression and reduced CBP toxicity. We have developed a ‘drug-target-carrier’ approach and proposed an enzyme sensitive peptide (KC26) modified milk exosomes loaded with CBP, providing a perspective for exploring targeted therapy of tumor cells and tumor microenvironment, and offering a promising clinical strategy for the treatment of retinoblastoma.