Self‐Delivered Transformable Nanosystem Capable of Enhancing Photodynamic Effectiveness and Multi‐Target Ameliorating Immunosuppression for Treatment of Breast Cancer and Lung Metastasis

Abstract Homogeneous distribution and adequate accumulation of photosensitizer in tumor are essential for effective photodynamic therapy (PDT). However, the intricate tumor microenvironment (TME) often poses great challenges to the deep penetration and retention of therapeutic agents in tumor. Moreover, the important effect of PDT to induce specific antitumor immune response is impeded by multiple immunosuppressive mechanisms within TME. Confronting these issues, here a rationally designed nanosystem (SUN‐NPA) with acid‐responsive sphere‐to‐fiber transformation ability by leveraging the characters of drug molecules is proposed to achieve self‐delivery of photosensitizer Chlorin e6 (Ce6) and two small‐molecule immunomodulators, metformin (MET) and sunitinib (SUN). The spatiotemporal controlled transformation enables homogeneous distribution and high accumulation of drugs to achieve enduring PDT and complete tumor elimination. Meanwhile, the co‐delivered MET and SUN alleviate tumor immunosuppression from multiple aspects, effectively synergizing with PDT to ignite potent host immune response and long‐lasting immunological memory against tumor cells. The artful integration of enhanced PDT and activated antitumor immunity realized by SUN‐NPA leads to the significant inhibition of tumor growth and metastasis, exhibiting great potential for oncotherapy.