Porphyrin Centered Paclitaxel Tetrameric Prodrug Nanoassemblies as Tumor‐Selective Theranostics for Synergized Breast Cancer Therapy

Abstract Although having undergone decades of development, nanoparticulate drug delivery vehicles for efficient cancer therapy remain a challenge, confined by low drug loading, instability, and poor cancer tissue selectivity. A self‐assembled prodrug, the combination of prodrug strategy and the self‐assembly merits, represents a special chemical entity which spontaneously organizes into supramolecular composites with defined architecture, therefore also providing a strategy to develop new medications. Paclitaxel (PTX) is still among the most generally prescribed chemotherapeutics in oncology but is restricted by poor solubility. Although photodynamic therapy, with its noninvasive features and barely developed drug resistance, signifies an alternative tool to suppress life‐threatening cancer, sole use hardly fulfills its potential. To this end, a reduction‐activatable heterotetrameric prodrug with the photosensitizer is synthesized, then formulated into self‐assembled nanoparticles (NPs) for tumor imaging and combined chemo‐ and photodynamic therapy. Coating the NPs with amphiphilic polymer distearylphosphatidylethanolamine‐polyethylene glycol‐arginine‐glycine‐aspartate (DSPE‐PEG‐RGD) offers high stability and enables cancer tissue targeting. The as‐prepared NPs enlighten disease cells and reveal more potent cytotoxicity comparing to PTX and the photosensitizer alone. Furthermore, the NPs selectively accumulates into tumors and synergistically inhibits tumor proliferation with reduced side effects in mice.