Light-Triggered Nanozymes Remodel the Tumor Hypoxic and Immunosuppressive Microenvironment for Ferroptosis-Enhanced Antitumor Immunity

Cancer immunotherapy holds significant promise for addressing diverse malignancies. Nevertheless, its efficacy remains constrained by the intricate tumor immunosuppressive microenvironment. Herein, a light-triggered nanozyme Fe-TCPP-R848-PEG (Fe-MOF-RP) was designed for remodeling the immunosuppressive microenvironment. The Fe-TCPP-MOFs were utilized not only as a core catalysis component against tumor destruction but also as a biocompatible delivery vector of an immunologic agonist, improving its long circulation and tumor enrichment. Concurrently, it catalyzes the decomposition of H2O2 within the tumor, yielding oxygen to augment photodynamic therapy. The induced ferroptosis, in synergy with photodynamic therapy, prompts the liberation of tumor-associated antigens from tumor cells inducing immunogenic cell death. Phototriggered on-demand release of R848 agonists stimulated the maturation of dendritic cells and reverted the tumor-promoting M2 phenotypes into adoptive M1 macrophages, which further reshaped the tumor immunosuppressive microenvironment. Notably, the nanozyme effectively restrains well-established tumors, such as B16F10 melanoma. Moreover, it demonstrates a distal tumor-inhibiting effect upon in situ light treatment. What is more, in a lung metastasis model, it elicits robust immune memory, conferring enduring protection against tumor rechallenge. Our study presents a straightforward and broadly applicable strategy for crafting nanozymes with the potential to effectively thwart cancer recurrence and metastasis.

Chimeric Antigen Receptor T Cell and Chimeric Antigen Receptor NK Cell Therapy in Pediatric and Adult High-Grade Glioma-Recent Advances

High-grade gliomas (HGG) account for approximately 10% of central nervous system (CNS) tumors in children and 25% of CNS tumors in adults. Despite their rare occurrence, HGG are a significant clinical problem. The standard therapeutic procedure in both pediatric and adult patients with HGG is the surgical resection of the tumor combined with chemotherapy and radiotherapy. Despite intensive treatment, the 5-year overall survival in pediatric patients is below 20-30%. This rate is even lower for the most common HGG in adults (glioblastoma), at less than 5%. It is, therefore, essential to search for new therapeutic methods that can extend the survival rate. One of the therapeutic options is the use of immune cells (T lymphocytes/natural killer (NK) cells) expressing a chimeric antigen receptor (CAR). The objective of the following review is to present the latest results of preclinical and clinical studies evaluating the efficacy of CAR-T and CAR-NK cells in HGG therapy.

Cancer-derived non-coding RNAs endow tumor microenvironment with immunosuppressive properties

Non-coding RNAs (ncRNAs) have attracted extensive attention due to their vital roles in tumorigenesis and progression, especially in the immunotherapy resistance. Tumor immunotherapy resistance is a crucial factor hindering the efficacy of tumor treatments, which can be largely attributed to the immunosuppressive properties of tumor microenvironment. Current studies have revealed that cancer-derived ncRNAs are involved in the formation of tumor immunosuppressive microenvironment (TIME) through multiple ways. They not only promote the expression of immune checkpoint ligands (e.g., PD-L1, CD47, Gal-9, and CD276) on cancer cell surfaces, but also enhance the secretion of immunosuppressive cytokines (e.g., TGF-β, IL-6, IL-10, VEGF, and chemokines). Cancer-derived ncRNAs could also be transferred into surrounding immune-related cells through extracellular vesicles, thereby inhibiting the cytotoxicity of CD8+ T cells and NK cells, restraining the DC-mediated antigen presentation, inducing the immunosuppressive phenotype transformation of TAMs and CAFs, and enhancing the immunosuppressive functions of Tregs and MDSCs. Herein, we summarize the roles of cancer-derived ncRNAs in regulating TIME formation and further explore their potential applications as prognostic biomarkers and immunotherapeutic targets, which will help us to address the TIME-mediated immunotherapy resistance in the future. This article is categorized under: RNA in Disease and Development > RNA in Disease Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs.

Lactate Efflux Inhibition by Syrosingopine/LOD Co-Loaded Nanozyme for Synergetic Self-Replenishing Catalytic Cancer Therapy and Immune Microenvironment Remodeling

An effective systemic mechanism regulates tumor development and progression; thus, a rational design in a one-stone-two-birds strategy is meant for cancer treatment. Herein, a hollow Fe3 O4 catalytic nanozyme carrier co-loading lactate oxidase (LOD) and a clinically-used hypotensor syrosingopine (Syr) are developed and delivered for synergetic cancer treatment by augmented self-replenishing nanocatalytic reaction, integrated starvation therapy, and reactivating anti-tumor immune microenvironment. The synergetic bio-effects of this nanoplatform stemmed from the effective inhibition of lactate efflux through blocking the monocarboxylate transporters MCT1/MCT4 functions by the loaded Syr as a trigger. Sustainable production of hydrogen peroxide by catalyzation of the increasingly residual intracellular lactic acid by the co-delivered LOD and intracellular acidification enabled the augmented self-replenishing nanocatalytic reaction. Large amounts of produced reactive oxygen species (ROS) damaged mitochondria to inhibit oxidative phosphorylation as the substituted energy supply upon the hampered glycolysis pathway of tumor cells. Meanwhile, remodeling anti-tumor immune microenvironment is implemented by pH gradient reversal, promoting the release of proinflammatory cytokines, restored effector T and NK cells, increased M1-polarize tumor-associated macrophages, and restriction of regulatory T cells. Thus, the biocompatible nanozyme platform achieved the synergy of chemodynamic/immuno/starvation therapies. This proof-of-concept study represents a promising candidate nanoplatform for synergetic cancer treatment.

Natural Products for the Immunotherapy of Glioma

Glioma immunotherapy has attracted increasing attention since the immune system plays a vital role in suppressing tumor growth. Immunotherapy strategies are already being tested in clinical trials, such as immune checkpoint inhibitors (ICIs), vaccines, chimeric antigen receptor T-cell (CAR-T cell) therapy, and virus therapy. However, the clinical application of these immunotherapies is limited due to their tremendous side effects and slight efficacy caused by glioma heterogeneity, antigen escape, and the presence of glioma immunosuppressive microenvironment (GIME). Natural products have emerged as a promising and safe strategy for glioma therapy since most of them possess excellent antitumor effects and immunoregulatory properties by reversing GIME. This review summarizes the status of current immunotherapy strategies for glioma, including their obstacles. Then we discuss the recent advancement of natural products for glioma immunotherapy. Additionally, perspectives on the challenges and opportunities of natural compounds for modulating the glioma microenvironment are also illustrated.

A Near-Infrared-II Fluorescent Nanocatalyst for Enhanced CAR T Cell Therapy against Solid Tumor by Immune Reprogramming

Chimeric antigen receptor (CAR) T cell therapy holds great promise in the treatment of hematological malignancies but performs poorly in solid tumors due to the tumor immunosuppressive microenvironment. Herein, a multifunctional nanocatalyst (APHA@CM) was prepared by encapsulating horseradish peroxidase (HRP)-loaded Au/polydopamine nanoparticles (Au/PDA NPs) and Ag₂S quantum dots with CAR T cell membranes to improve the CAR T cell therapy in solid tumors. The APHA@CM has excellent multimodal imaging capability to precisely guide the scope and time window for nanocatalyst-induced tumor microenvironment regulation and CAR T cell therapy. The oxidase-like activity of Au NPs inhibited the glycolytic metabolism of tumor cells, reducing lactate efflux, reprogramming tumor immunosuppression, and ultimately increasing CAR T cell activation within the tumors. Additionally, the hypoxia environment of tumors could be relieved by HRP to enhance the Au/PDA NPs-induced synergistic sonodynamic/photothermal therapy (SDT/PTT), thereby promoting the immunogenic cell death of NALM 6 cells and enhancing CAR T cell-mediated immune microenvironment reprogramming. When this strategy was utilized to treat NALM 6 solid tumors, it not only completely eliminated tumors but also formed a long-term immune memory effect to inhibit tumor metastasis and recurrence. This work offers a strategy for CAR T cell therapy in solid tumor.

Polarization of Tumor-Associated Macrophages Promoted by Vitamin C-Loaded Liposomes for Cancer Immunotherapy

While checkpoint blockade immunotherapy as a promising clinical modality has revolutionized cancer treatment, it is of benefit to only a subset of patients because of the tumor immunosuppressive microenvironment. Herein, we report that the specified delivery of vitamin C at the tumor site by responsive lipid nanoparticles can efficiently induce oxidative toxicity and the polarization of M1 macrophages, promoting the infiltration of activating cytotoxic T lymphocytes in the tumor microenvironment for intensive immune checkpoint blocking therapy. Both in vitro and in vivo assays demonstrate successful vitamin C-induced polarization of M2 macrophages to M1 macrophages. In vivo transcriptome analysis also reveals the activation mechanism of vitamin C immunity. More importantly, the combination approach displays much better immune response and immune process within the tumor microenvironment than clinical programmed cell death ligand 1 (Anti-PD-L1) alone. This work provides a powerful therapeutic application of vitamin C to amplify Anti-PD-L1 immunotherapy in cancer treatment, which brings hope to patients with clinically insensitive immunity.

A Self-amplifying ROS-sensitive prodrug-based nanodecoy for circumventing immune resistance in chemotherapy-sensitized immunotherapy

Circumventing immune resistance and boosting immune response is the ultimate goal of cancer immunotherapy. Herein, we reported a tumor-associated macrophage (TAM) membrane-camouflaged nanodecoy containing a self-amplifying reactive oxygen species (ROS)-sensitive prodrug nanoparticle for specifically inducing immunogenic cell death (ICD) in combination with TAM depletion. A versatile ROS-cleavable camptothecin (CPT) prodrug (DCC) was synthesized through a thioacetal linker between CPT and the ROS generator cinnamaldehyde (CA), which could self-assemble into a uniform prodrug nanoparticle to realize a positive feedback loop of "ROS-triggered CA/CPT release and CA/CPT-mediated ROS generation." This DCC was further modified with the TAM membrane (abbreviated as DCC@M2), which could not only target both primary tumors and lung metastasis nodules through VCAM-1/α₄β₁ integrin interaction but also absorb CSF-1 secreted by tumor cells to disturb the interaction between TAMs and cancer cells. Our nanodecoy could effectively induce ICD cascade and deplete TAMs for priming tumor-specific effector T cell infiltration for antitumor immune response activation, which represents a versatile approach for cancer immunotherapy. STATEMENT OF SIGNIFICANCE: A tumor-associated macrophage (TAM) membrane-camouflaged nanodecoy containing a self-amplifying reactive oxygen species (ROS)-sensitive prodrug nanoparticle was fabricated for the first time. This ROS-cleavable camptothecin (CPT)/cinnamaldehyde (CA) prodrug (DCC) could self-assemble into a uniform nanoparticle to realize the positive feedback loop of "ROS-triggered CA/CPT release and CA/CPT-mediated ROS generation." After TAM membrane coating, this system (DCC@M2) could not only target both primary tumors and lung metastatic nodules but also scavenge CSF-1 secreted by tumor cells for TAM depletion for sufficient chemotherapy-sensitized immunotherapy.

Anticancer nanomedicines harnessing tumor microenvironmental components

INTRODUCTION

Small-molecular drugs are extensively used in cancer therapy, while they have issues of nonspecific distribution and consequent side effects. Nanomedicines that incorporate chemotherapeutic drugs have been developed to enhance the therapeutic efficacy of these drugs and reduce their side effects. One of the promising strategies is to prepare nanomedicines by harnessing the unique tumor microenvironment (TME).

AREAS COVERED

The TME contains numerous cell types that specifically express specific antibodies on the surface including tumor vascular endothelial cells, tumor-associated adipocytes, tumor-associated fibroblasts, tumor-associated immune cells and cancer stem cells. The physicochemical environment is characterized with a low pH, hypoxia, and a high redox potential resulting from tumor-specific metabolism. The intelligent nanomedicines can be categorized into two groups: the first group which is rapidly responsive to extracellular chemical/biological factors in the TME and the second one which actively and/or specifically targets cellular components in the TME.

EXPERT OPINION

In this paper, we review recent progress of nanomedicines by harnessing the TME and illustrate the principles and advantages of different strategies for designing nanomedicines, which are of great significance for exploring novel nanomedicines or translating current nanomedicines into clinical practice. We will discuss the challenges and prospects of preparing nanomedicines to utilize or alter the TME for achieving effective, safe anticancer treatment.

In situ Injection of pH- and Temperature-Sensitive Nanomaterials Increases Chemo-Photothermal Efficacy by Alleviating the Tumor Immunosuppressive Microenvironment

Purpose

Triple-negative breast cancer (TNBC) is challenging to treat with traditional "standard of care" therapy due to the lack of targetable biomarkers and rapid progression to distant metastasis.

Methods

We synthesized a novel combination regimen that included chemotherapy and photothermal therapy (PTT) to address this problem. Here, we tested a magnetic nanosystem (MNs-PEG/IR780-DOX micelles) loaded with the near-infrared (NIR) photothermal agent IR780 and doxorubicin (DOX) to achieve chemo-photothermal and boost antitumor immunity. Intraductal (i.duc) administration of MNs-PEG/IR780-DOX could increase the concentration of the drug in the tumor while reducing systemic side effects.

Results

We showed more uptake of MNs-PEG/IR780-DOX by 4T1-luc cells and higher penetration in the tumor. MNs-PEG/IR780-DOX exhibited excellent photothermal conversion in vivo and in vitro. The release of DOX from MNs-PEG/IR780-DOX is pH- and temperature-sensitive. Facilitated by i.duc administration, MNs-PEG/IR780-DOX displayed antitumor effects and prevented distant organs metastasis under NIR laser (L) irradiation and magnetic field (MF)while avoiding DOX-induced toxicity. More importantly, MNs-PEG/IR780-DOX alleviated tumor immunosuppressive microenvironment by increasing tumor CD8⁺ T cells infiltration and reducing the proportion of myeloid-derived suppressor cells (MDSCs) and Tregs.

Conclusion

Intraductal administration of pH- and temperature-sensitive MNs-PEG/IR780-DOX with L and MF had the potential for achieving minimally invasive, targeted, and accurate treatment of TNBC.

Engineering Endogenous Tumor-Associated Macrophage-Targeted Biomimetic Nano-RBC to Reprogram Tumor Immunosuppressive Microenvironment for Enhanced Chemo-Immunotherapy

Immunotherapy has shown encouraging results in various cancers, but the response rates are relatively low due to the complex tumor immunosuppressive microenvironment (TIME). The presence of tumor-associated macrophages (TAMs) and tumor hypoxia correlates significantly with potent immunosuppressive activity. Here, a hemoglobin-poly(ε-caprolactone) (Hb-PCL) conjugate self-assembled biomimetic nano red blood cell (nano-RBC) system (V(Hb)) is engineered to deliver chemotherapeutic doxorubicin (DOX) and oxygen for reprogramming TIME. The Hb moiety of V(Hb)@DOX can bind to endogenous plasma haptoglobin (Hp) and specifically target the M2-type TAMs via the CD163 surface receptor, and effectively kill the cells. In addition, the O₂ released by the Hb alleviates tumor hypoxia, which further augments the antitumor immune response by recruiting fewer M2-type macrophages. TAM-targeting depletion and hypoxia alleviation synergistically reprogram the TIME, which concurrently downregulate PD-L1 expression of tumor cells, decrease the levels of immunosuppressive cytokines such as IL-10 and TGF-β, elevate the immunostimulatory IFN-γ, enhance cytotoxic T lymphocyte (CTL) response, and boost a strong memory response. The ensuing TAM-targeted chemo-immunotherapeutic effects markedly inhibit tumor metastasis and recurrence. Taken together, the engineered endogenous TAM-targeted biomimetic nano-RBC system is a highly promising tool to reprogram TIME for cancer chemo-immunotherapy.

Zoledronic Acid-Gadolinium Coordination Polymer Nanorods for Improved Tumor Radioimmunotherapy by Synergetically Inducing Immunogenic Cell Death and Reprogramming the Immunosuppressive Microenvironment

Radiation therapy can potentially elicit a systemic immune response and cause the regression of nonirradiated tumors, and the checkpoint blockade immunotherapies have been introduced to improve their clinical response rate. However, the therapeutic benefits of radioimmunotherapy are still far from satisfactory. Herein, the self-assembled "carrier-free" coordination polymer nanorods are constructed based on gadolinium and zoledronic acid, which can deposit X-ray for improved reactive oxygen species production to induce potent immunogenic cell death (ICD), simultaneously deplete tumor-associated macrophages with regulatory cytokines inhibition, respectively. With the potent ICD induction and reprogrammed immunosuppressive microenvironment, this synergetic strategy can promote antigen presentation, immune priming and T-cell infiltration, and potentiate checkpoint blockade immunotherapies against primary, distant, and metastatic tumors.

CAR T-Cell Therapy Is Effective but Not Long-Lasting in B-Cell Lymphoma of the Brain

Advanced central nervous system (CNS) lymphoma is an exclusion criterion for most chimeric antigen receptor (CAR) T-cell studies due to the associated levels of neurotoxicity. In this study, we described five patients with chemorefractory B-cell CNS lymphoma who received CAR19 and CAR22 T-cell “Cocktail” therapy and follow-up for 6–16 months. All patients experienced cytokine release syndrome (CRS). Two patients experienced CAR T-cell-related encephalopathy syndrome (CRES), which was controllable. The best response was observed in two patients, who successfully achieved complete remissions (CR), and the other three patients achieved partial remissions (PR). Four patients had progressive disease (PD) after remission. In addition, one CR patient and one PD patient accepted CAR T-cell infusion following hematopoietic stem cell transplantation therapy in the 3rd month and were in ongoing remission for 14 and 6 months of follow-up, respectively. The targeted antigens in two patients were still positive, and CAR T-cells were reboosted in the cerebrospinal fluid (CSF) after PD, but a small number of CD3-positive T-cells were observed to infiltrate into the tumor. Our study indicates the efficacy of CAR T-cell therapy for CNS lymphoma with an acceptable safety profile; however, the remission did not last long, perhaps due to the tumor immunosuppressive microenvironment (TME) of the CNS. CAR T-cell therapy should be combined with other treatments to help improve the TME of cerebral lymphoma.