Engineering nanoliposomes to enhance cancer immunotherapy by reversing immunosuppression and synergistically boosting tumour immunogenicity

The clinical success of immune checkpoint inhibitors (ICIs) has initiated a new era in the treatment of metastatic cancer. Unfortunately, the overall response rate of ICIs in pretreated metastatic breast cancer (BC) is generally less than 20% due to many challenges, including low immunogenicity and immunosuppressive tumour microenvironment (ITM). Herein, we synthesized nanoliposomes that codelivered diclofenac (DC) and Mn (5,10,15,20-tetrakis (4-chlorophenyl) porphyrin) Cl (PMnCl) (denoted [email protected]) to overcome these challenges. DC could block lactate transporters (monocarboxylate transporters 1 and 4) on the cancer cell membrane, thus reducing the concentration of lactate, which acts as a critical regulator of the ITM. Meanwhile, PMnCl-induced sonodynamic therapy (SDT) could induce apoptotic and/or necrotic tumour cell death. Importantly, SDT could induce immunogenic cell death (ICD) during the tumour cell debris generation, which changed the state of tumour cells from nonimmunogenic to immunogenic. Thus, [email protected] was verified to activate T cells, inactivate regulatory T cells and regulate the levels of immune cytokines, ultimately inhibiting primary and distant tumours by improving the antitumour effect of anti-PD1-based immunotherapy.