An Activatable Dual Polymer Nanosystem for Photoimmunotherapy And Metabolic Modulation of Deep-Seated Tumors.

Nanomedicine in combination with immunotherapy has shown great potential in the cancer treatment, but phototherapeutic nanomaterials that specifically activate the immunopharmacological effects in deep tumors have rarely been developed due to limited laser penetration depth and tumor immune microenvironment. Herein we report a newly synthesized semiconducting polymer grafted with imiquimod R837 and indoxmid encapsulated micelle (SPRIN-micelle) with strong absorption in the second near infrared window (NIR-II) that can relieve tumor immunosuppression and enhance the photothermal immunotherapy and catabolic modulation on tumors. Immune agonists (Imiquimod R837) and immunometabolic modulators (Indoxmid) were covalently attached to NIR-II semiconducting polymer (SP) sensors via a glutathione (GSH)-responsive self-immolation linker and then loaded into Pluronic F127 (F127) micelles by a temperature-sensitive critical micelle concentration (CMC)-switching method. Using this method, photothermal effect of SPRIN-micelles in deep-seated tumors could be activated, leading to effective tumor ablation and immunogenic cell death. Meanwhile, imiquimod and indoxmid were tracelessly released in response to the tumor microenvironment, resulting in DC maturation by imiquimod R837 and inhibition of both indoleamine 2,3-dioxygenase (IDO) activity and Treg cell expression by indoxmid. Ultimately, cytotoxic T lymphocyte infiltration and tumor metastasis inhibition in deep solid tumors (9 mm) were achieved. In summary, this work demonstrates a new strategy for the combination of photothermal immunotherapy and metabolic modulation by developing a dual functional polymer system including activable SP and temperature-sensitive F127 for the treatment of deep solid tumors. This article is protected by copyright. All rights reserved.