Site‐Specific Construction of Long‐Term Drug Depot for Suppression of Tumor Recurrence

Abstract Local tumor recurrence after surgical resection is a critical concern in cancer therapy, and the current treatments, such as postsurgical chemotherapy, still show undesired side effects. Here a nonimplant strategy (transformation induced localization, TIL) is presented to in situ construct long‐term retentive drug depots, wherein the sustained drug release from fibrous drug depots results in highly efficient suppression of postsurgical local tumor relapse. The peptide‐based prodrug nanoparticles show favorable tumor targeting and instantly reorganize into fibrous nanostructures under overexpressed enzyme, realizing the construction of long‐term drug depot in the tumor site. After the resection surgery, the remnant cancer cells are still inhibited by the sustained drug release from the fibrous prodrug depot, effectively preventing postsurgical local recurrences. This TIL strategy shows great potential in cancer recurrence therapy and offers a novel perspective for constructing functional biomaterials in vivo.