NIR light triggered intracellular polymerization via nanoparticles containing acrylates prodrugs and azo-polymers for inhibiting cisplatin efflux for combined chemotherapy and immunotherapy

Despite the high clinical success of cisplatin, this compound is associated with insufficient intracellular uptake and quick excretion from cancer cells, resulting in poor drug efficacy. To overcome these limitations, herein, a nanoparticle formulation for efficient drug delivery and high therapeutic effect towards challenging cancer tumors by multimodal chemotherapy and immunotherapy is reported. The nanoparticles are generated upon self-assembly of a polymerizable Pt(IV) prodrug with axial acrylates, a near-infrared II polymer that can generate heat, and a thermosensitive polymer with azo bonds that can generate radicals upon exposure to heat. The nanoparticles are found with a higher cellular uptake than the molecular drug cisplatin. Upon exposure to irradiation at 1064 nm, the azo bonds are broken, and therapeutically active radicals as well as the Pt(IV) complex simultaneously released. Due to the presence of reactive acrylate moieties, the metal complex is able to undergo in-situ polymerization inside the cancer cells, resulting in the formation of a cross-linked polymeric network and therefore the retention of the cisplatin and reduction of the cisplatin efflux in the cancer cells, triggering cell death by a combination of apoptosis and immunogenic cell death. Based on these promising effects, the therapeutic efficiency is evaluated in a clinically highly challenging ovarian cancer patient-derived xenograft mouse model as well as an ID8 subcutaneous tumor-bearing C57BL/6 mouse model. This study reports on the first example of a nanoparticle delivery system with Pt(IV) prodrugs that can polymerize within cancer cells, thereby resulting in a decrease in cisplatin efflux, efficient DNA damage, and effective immunogenic response.