A large number of chemotherapeutic and immunotherapeutic agents have been shown to be less effective when exposed to a hypoxic solid tumor. The tumor hypoxia microenvironment contributes to multidrug resistance and immunosuppression, and current delivery of oxygen or enzyme to alleviate hypoxic microenvironment is often limited by the oxygen supplying capacity of material-based carriers and short window of oxygen production. Herein, macrophage membrane coated chlorella (M-Chl) is constructed for targeted delivery to the solid tumor and sustainable oxygen production via photosynthesis, which provides a new general strategy to overcome tumor hypoxia and improve chemotherapy and immunotherapy. The camouflaged strategy via macrophage membrane coating enhances tumor accumulation and retention of Chl due to the inflammatory homing effects of macrophage membrane, which contributes to long term oxygen production for at least 6 days with one dose of Chl, resulting in efficient downregulation of tumor HIF-1α. In vivo antitumor therapy in mice shows that M-Chl enhances the chemotherapeutic efficacy of doxorubicin via inhibiting hypoxia-mediated overexpression of drug efflux proteins, and also improves the poor immunotherapeutic performance of T cell activation agent, anti-CTLA-4 antibody, via downregulating hypoxia-mediated immunosuppressive proteins. Thus, M-Chl may serve as an important adjuvant for enhancing the therapeutic efficacy of clinical antitumor drugs against solid tumors.
Until now, treatment of refractory tumors and uncontrolled metastasis by cancer immunotherapy has not yet achieved satisfactory therapeutic results due to the insufficient in vivo immune response. Here, we proposed the construction of a therapeutic cancer nanovaccine Fe@OVA-IR820 with ferroptosis-inducing and photothermal properties for boosting cancer immunotherapy. Fe3+ ions were chelated inside the exogenous antigen ovalbumin (OVA) by biomineralization to form the nanovaccine, to which the photosensitizer IR820 was loaded by electrostatic incorporation. After intratumoral injection, in situ immunogenic cell death (ICD) was triggered as a result of Fe3+-dependent ferroptosis. Endogenous neoantigens and damage-associated molecular patterns (DAMPs) were released because of ICD and worked synergically with the exogenous OVA to provoke the immune response, which was further amplified by the photothermal effect after near-infrared irradiation. The enhanced recruitment and infiltration of T cells were observed and resulted in the suppression of the primary tumor. The therapeutic regiment that combined Fe@OVA-IR820 nanovaccine with cytotoxic T lymphocyte-associated protein 4 (CTLA-4) checkpoint blockade significantly boosted anti-cancer immunity and inhibited the growth of distal simulated metastases. Therefore, we proposed Fe@OVA-IR820 nanovaccine combined checkpoint blockade as a potential therapeutic strategy for melanoma treatment.
The combination of immune checkpoint inhibitors and immunogenic cell death (ICD) inducers has become a promising strategy for the treatment of various cancers. However, its efficacy remains unmet because of the dense stroma and defective vasculatures in the tumor microenvironment (TME) that restricts the intratumoral infiltration of cytotoxic T lymphocytes (CTLs). Herein, cancer-associated fibroblasts (CAFs)-targeted nanoemulsions are tailored to combine the ICD induction and the TME reprogramming to sensitize checkpoint blockade immunotherapy. Melittin, as an ICD inducer and an antifibrotic agent, is efficiently encapsulated into the nanoemulsion accompanied by a nitric oxide donor to improve its bioavailability and tumor targeting. The nanoemulsions exhibited dual functionality by directly inducing direct cancer cell death and enhancing the tumoral immunogenicity, while also synergistically reprogramming the TME through reversing the activated CAFs, decreasing collagen deposition and restoring tumor vessels. Consequently, these nanemulsions successfully facilitated the CTLs infiltration and suppressing the recruitment of immunosuppressive cells. A combination of AE-MGNPs and anti-CTLA-4 antibody greatly elicited a striking level of antitumor T-cell response to suppress tumor growth in CAFs-rich colorectal tumor models. Our work emphasized the integration of the ICD induction with simultaneous modulation of the TME to enhance the sensitivity of patients to checkpoint blockade immunotherapy.
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