Bioinspired Lipoproteins of Furoxans-Oxaliplatin Remodel Physical Barriers in Tumor to Potentiate T-Cell Infiltration

A Lactate-Depleting metal organic framework-based nanocatalyst reinforces intratumoral T cell response to boost anti-PD1 immunotherapy

Infiltration and activation of intratumoral T lymphocytes are critical for immune checkpoint blockade (ICB) therapy. Unfortunately, the low tumor immunogenicity and immunosuppressive tumor microenvironment (TME) induced by tumor metabolic reprogramming cooperatively hinder the ICB efficacy. Herein, we engineered a lactate-depleting MOF-based catalytic nanoplatform (LOX@ZIF-8@MPN), encapsulating lactate oxidase (LOX) within zeolitic imidazolate framework-8 (ZIF-8) coupled with a coating of metal polyphenol network (MPN) to reinforce T cell response based on a "two birds with one stone" strategy. LOX could catalyze the degradation of the immunosuppressive lactate to promote vascular normalization, facilitating T cell infiltration. On the other hand, hydrogen peroxide (H2O2) produced during lactate depletion can be transformed into anti-tumor hydroxyl radical (•OH) by the autocatalytic MPN-based Fenton nanosystem to trigger immunogenic cell death (ICD), which largely improved the tumor immunogenicity. The combination of ICD and vascular normalization presents a better synergistic immunopotentiation with anti-PD1, inducing robust anti-tumor immunity in primary tumors and recurrent malignancies. Collectively, our results demonstrate that the concurrent depletion of lactate to reverse the immunosuppressive TME and utilization of the by-product from lactate degradation via cascade catalysis promotes T cell response and thus improves the effectiveness of ICB therapy.

Bioinspired Lipoproteins of Furoxans-Gemcitabine Preferentially Targets Glioblastoma and Overcomes Radiotherapy Resistance

Radiotherapy (RT) resistance is an enormous challenge in glioblastoma multiforme (GBM) treatment, which is largely associated with DNA repair, poor distribution of reactive radicals in tumors, and limited delivery of radiosensitizers to the tumor sites. Inspired by the aberrant upregulation of RAD51 (a critical protein of DNA repair), scavenger receptor B type 1 (SR-B1), and C-C motif chemokine ligand 5 (CCL5) in GBM patients, a reduction-sensitive nitric oxide (NO) donor conjugate of gemcitabine (RAD51 inhibitor) (NG) is synthesized as radio-sensitizer and a CCL5 peptide-modified bioinspired lipoprotein system of NG (C-LNG) is rationally designed, aiming to preferentially target the tumor sites and overcome the RT resistance. C-LNG can preferentially accumulate at the orthotopic GBM tumor sites with considerable intratumor permeation, responsively release the gemcitabine and NO, and then generate abundant peroxynitrite (ONOO- ) upon X-ray radiation, thereby producing a 99.64% inhibition of tumor growth and a 71.44% survival rate at 120 days in GL261-induced orthotopic GBM tumor model. Therefore, the rationally designed bioinspired lipoprotein of NG provides an essential strategy to target GBM and overcome RT resistance.

Remodeling tumor immunosuppression with molecularly imprinted nanoparticles to enhance immunogenic cell death for cancer immunotherapy

Insufficient tumor accumulation and distribution of immunogenic cell death (ICD) inducer as well as low antitumor immunity severely restrict the therapeutic efficacy of tumor immunotherapy. Tumor associated fibroblasts (TAFs) are important in tumor extracellular matrix (ECM) remodeling and immune evasion. Reprogramming tumor immunosuppressive microenvironment via TAFs regulation might present a promising way for enhanced ICD effect and complete tumor elimination. In this study, TAFs derived tryptase imprinted nanoparticles (DMSN@MIPs) are developed to modulate TAFs and improve tumor immunotherapy effect of doxorubicin liposomes (DOX/LIP). Tryptase (TPS), secreted by mast cells, are found to support tumor growth via transcriptionally activating TAFs to an activated state with increased expression of fibroblast activation marker α-smooth muscle actin (α-SMA). DMSN@MIPs canbe used as artificial antibodies, which effectively neutralize TPS, reduce TAFs activation, promote intra-tumor penetration of DOX/LIP and enhance ICD effect induced by DOX/LIP. In addition, the combined administration system remodels immunosuppressive microenvironment, which not only significantly up-regulates immune cells (DC cells, CD8+T cells, NK cells), but also significantly down-regulates immunosuppressive cells (Treg cells, MDSCs cells). Our results support the DMSN@MIPs canbe a promising approach to improve ICD efficacy in cancer immunotherapy.

Emerging platinum(IV) prodrug nanotherapeutics: A new epoch for platinum-based cancer therapy

Owing to the unique DNA damaging cytotoxicity, platinum (Pt)-based chemotherapy has long been the first-line choice for clinical oncology. Unfortunately, Pt drugs are restricted by the severe dose-dependent toxicity and drug resistance. Correspondingly, Pt(IV) prodrugs are developed with the aim to improve the antitumor performance of Pt drugs. However, as "free" molecules, Pt(IV) prodrugs are still subject to unsatisfactory in vivo destiny and antitumor efficacy. Recently, Pt(IV) prodrug nanotherapeutics, inheriting both the merits of Pt(IV) prodrugs and nanotherapeutics, have emerged and demonstrated the promise to address the underexploited dilemma of Pt-based cancer therapy. Herein, we summarize the latest fronts of emerging Pt(IV) prodrug nanotherapeutics. First, the basic outlines of Pt(IV) prodrug nanotherapeutics are overviewed. Afterwards, how versatile Pt(IV) prodrug nanotherapeutics overcome the multiple biological barriers of antitumor drug delivery is introduced in detail. Moreover, advanced combination therapies based on multimodal Pt(IV) prodrug nanotherapeutics are discussed with special emphasis on the synergistic mechanisms. Finally, prospects and challenges of Pt(IV) prodrug nanotherapeutics for future clinical translation are spotlighted.

Targeted Reprogramming of Vitamin B3 Metabolism as a Nanotherapeutic Strategy towards Chemoresistant Cancers

Cancer-associated fibroblasts (CAFs) promote cancer stem cell (CSC)-mediated chemoresistance and immunosuppressive tumor microenvironment. However, direct depletion of CAFs may increase cancer invasiveness and metastasis. As a generalized strategy against chemoresistant cancers, Gemini-like homotypic targeting nanoparticles (NPs) are designed for two-pronged CAF transformation and cancer cell elimination. The CAF-targeted NPs couple vitamin B3 metabolic reprogramming to epigenetic modulation of secreted pro-stemness and immunosuppressive factors, thereby diminishing CSC and suppressive immune cell populations to enhance cancer cell drug susceptibility and cytotoxic T cell infiltration. In mouse models of breast, liver, pancreatic and colorectal cancers that are resistant to their respective first-line chemotherapeutics, a single dose of hydrogel co-delivering the Gemini-like NPs can rehabilitate chemosensitivity, induce immune activation, and achieve tumor regression. Moreover, it stimulates robust T cell memory for long-term protection against tumor rechallenge. This study thus represents an innovative approach with broad applicability for overcoming cancer chemoresistance.

Research progress in leveraging biomaterials for enhancing NK cell immunotherapy

NK cell immunotherapy is a promising antitumor therapeutic modality after the development of T cell immunotherapy. Structural modification of NK cells with biomaterials may provide a precise, efficient, and low-cost strategy to enhance NK cell immunotherapy. The biomaterial modification of NK cells can be divided into two strategies: surface engineering with biomaterials and intracellular modification. The surface engineering strategies include hydrophobic interaction of lipids, receptor-ligand interaction between membrane proteins, covalent binding to amino acid residues, click reaction and electrostatic interaction. The intracellular modification strategies are based on manipulation by nanotechnology using membranous materials from various sources of NK cells (such as exosome, vesicle and cytomembranes). Finally, the biomaterials-based strategies regulate the recruitment, recognition and cytotoxicity of NK cells in the solid tumor site in situ to boost the activity of NK cells in the tumor. This article reviews the recent research progress in enhancing NK cell therapy based on biomaterial modification, to provide a reference for further researches on engineering NK cell therapy with biomaterials.

Lipid-based nanoparticles for cancer immunotherapy

As the fourth most important cancer management strategy except surgery, chemotherapy and radiotherapy, cancer immunotherapy has been confirmed to elicit durable antitumor effects in the clinic by leveraging the patient's own immune system to eradicate the cancer cells. However, the limited population of patients who benefit from the current immunotherapies and the immune related adverse events hinder its development. The immunosuppressive microenvironment is the main cause of the failure, which leads to cancer immune evasion and immunity cycle blockade. Encouragingly, nanotechnology has been engineered to enhance the efficacy and reduce off-target toxicity of their therapeutic cargos by spatiotemporally controlling the biodistribution and release kinetics. Among them, lipid-based nanoparticles are the first nanomedicines to make clinical translation, which are now established platforms for diverse areas. In this perspective, we discuss the available lipid-based nanoparticles in research and market here, then describe their application in cancer immunotherapy, with special emphasis on the T cells-activated and macrophages-targeted delivery system. Through perpetuating each step of cancer immunity cycle, lipid-based nanoparticles can reduce immunosuppression and promote drug delivery to trigger robust antitumor response.

Bioactive inorganic nanomaterials for cancer theranostics

Bioactive materials are a special class of biomaterials that can react in vivo to induce a biological response or regulate biological functions, thus achieving a better curative effect than traditional inert biomaterials. For cancer theranostics, compared with organic or polymer nanomaterials, inorganic nanomaterials possess unique physical and chemical properties, have stronger mechanical stability on the basis of maintaining certain bioactivity, and are easy to be compounded with various carriers (polymer carriers, biological carriers, etc.), so as to achieve specific antitumor efficacy. After entering the nanoscale, due to the nano-size effect, high specific surface area and special nanostructures, inorganic nanomaterials exhibit unique biological effects, which significantly influence the interaction with biological organisms. Therefore, the research and applications of bioactive inorganic nanomaterials in cancer theranostics have attracted wide attention. In this review, we mainly summarize the recent progress of bioactive inorganic nanomaterials in cancer theranostics, and also introduce the definition, synthesis and modification strategies of bioactive inorganic nanomaterials. Thereafter, the applications of bioactive inorganic nanomaterials in tumor imaging and antitumor therapy, including tumor microenvironment (TME) regulation, catalytic therapy, gas therapy, regulatory cell death and immunotherapy, are discussed. Finally, the biosafety and challenges of bioactive inorganic nanomaterials are also mentioned, and their future development opportunities are prospected. This review highlights the bioapplication of bioactive inorganic nanomaterials.

Targeted Degradation of PD-L1 and Activation of the STING Pathway by Carbon-Dot-Based PROTACs for Cancer Immunotherapy

Proteolysis targeting chimeras (PROTACs) technology is an emerging approach to degrade disease-associated proteins. Here, we report carbon-dot (CD)-based PROTACs (CDTACs) that degrade membrane proteins via the ubiquitin-proteasome system. CDTACs can bind to programmed cell death ligand 1 (PD-L1), recruit cereblon (CRBN) to induce PD-L1 ubiquitination, and degrade them with proteasomes. Fasting-mimicking diet (FMD) is also used to enhance the cellular uptake and proteasome activity. More than 99 % or 90 % of PD-L1 in CT26 or B16-F10 tumor cells can be degraded by CDTACs, respectively. Furthermore, CDTACs can activate the stimulator of interferon genes (STING) pathway to trigger immune responses. Thus, CDTACs with FMD treatment effectively inhibit the growth of CT26 and B16-F10 tumors. Compared with small-molecule-based PROTACs, CDTACs offer several advantages, such as efficient membrane protein degradation, targeted tumor accumulation, immune system activation, and in vivo detection.

Nitric Oxide-Loaded Bioinspired Lipoprotein Normalizes Tumor Vessels To Improve Intratumor Delivery and Chemotherapy of Albumin-Bound Paclitaxel Nanoparticles

The disorganized vasculatures in tumors represent a substantial challenge of intratumor nanomedicine delivery to exert the anticancer effects. Herein, we rationally designed a glutathione (GSH)-activated nitric oxide (NO) donor loaded bioinspired lipoprotein system (NO-BLP) to normalize tumor vessels and then promote the delivery efficiency of sequential albumin-bound paclitaxel nanoparticles (PAN) in tumors. NO-BLP exhibited higher tumor accumulation and deeper penetration versus the counterpart liposomal formulation (NO-Lipo) in 4T1 breast cancer tumors, thus producing notable vascular normalization efficacy and causing a 2.33-fold increase of PAN accumulation. The sequential strategy of NO-BLP plus PAN resulted in an 81.03% inhibition of tumor growth in 4T1 tumors, which was better than the NO-BLP monotherapy, PAN monotherapy, and the counterpart NO-Lipo plus PAN treatment. Therefore, the bioinspired lipoprotein of NO-BLP provides an encouraging platform to normalize tumor vessels and promote intratumor delivery of nanomedicines for effective cancer treatment.

Macrophage Membrane-Coated Nano-Gemcitabine Promotes Lymphocyte Infiltration and Synergizes AntiPD-L1 to Restore the Tumoricidal Function

The limited lymphocyte infiltration and exhaustion of tumoricidal functions in solid tumors remain a formidable obstacle to cancer immunotherapy. Herein, we designed a macrophage membrane-coated nano-gemcitabine system (MNGs) to promote lymphocyte infiltration and then synergized anti-programmed death ligand 1 (antiPD-L1) to reinvigorate the exhausted lymphocytes. MNGs exhibited effective intratumor-permeating and responsive drug-releasing capacity, produced notable elimination of versatile immunosuppressive cells, and promoted lymphocyte infiltration into cancer cell regions in tumors, but over 50% of these infiltrated lymphocytes were in the exhausted state. Compared with MNG monotherapy, the MNGs+antiPD-L1 combination produced 31.77% and 30.63% reduction of exhausted CD3⁺CD8⁺ T cells and natural killer (NK) cells and 2.83- and 3.17-fold increases of interferon-γ (IFN-γ)-positive subtypes, respectively, thereby resulting in considerable therapeutic benefits in several tumor models. Thus, MNGs provide an encouraging strategy to promote lymphocyte infiltration and synergize antiPD-L1 to restore their tumoricidal function for cancer immunotherapy.

Hypoxia-responsive Immunostimulatory Nanomedicines Synergize with Checkpoint Blockade Immunotherapy for Potentiating Cancer Immunotherapy

Inducing cell death while simultaneously enhancing antitumor immune responses is a promising therapeutic approach for multiple cancers. Celastrol (Cel) and 7-ethyl-10-hydroxycamptothecin (SN38) have contrasting physicochemical properties, but strong synergy in immunogenic cell death induction and anticancer activity. Herein, a hypoxia-sensitive nanosystem (CS@TAP) was designed to demonstrate effective immunotherapy for colorectal cancer by systemic delivery of an immunostimulatory chemotherapy combination. Furthermore, the combination of CS@TAP with anti-PD-L1 mAb (αPD-L1) exhibited a significant therapeutic benefit of delaying tumor growth and increased local doses of immunogenic signaling and T-cell infiltration, ultimately extending survival. We conclude that CS@TAP is an effective inducer of immunogenic cell death (ICD) in cancer immunotherapy. Therefore, this study provides an encouraging strategy to synergistically induce immunogenic cell death to enhance tumor cytotoxic T lymphocytes (CTLs) infiltration for anticancer immunotherapy.

Hypoxia-responsive Immunostimulatory Nanomedicines Synergize with Checkpoint Blockade Immunotherapy for Potentiating Cancer Immunotherapy

Inducing cell death while simultaneously enhancing antitumor immune responses is a promising therapeutic approach for multiple cancers. Celastrol (Cel) and 7-ethyl-10-hydroxycamptothecin (SN38) have contrasting physicochemical properties, but strong synergy in immunogenic cell death induction and anticancer activity. Herein, a hypoxia-sensitive nanosystem (CS@TAP) was designed to demonstrate effective immunotherapy for colorectal cancer by systemic delivery of an immunostimulatory chemotherapy combination. Furthermore, the combination of CS@TAP with anti-PD-L1 mAb (αPD-L1) exhibited a significant therapeutic benefit of delaying tumor growth and increased local doses of immunogenic signaling and T-cell infiltration, ultimately extending survival. We conclude that CS@TAP is an effective inducer of immunogenic cell death (ICD) in cancer immunotherapy. Therefore, this study provides an encouraging strategy to synergistically induce immunogenic cell death to enhance tumor cytotoxic T lymphocytes (CTLs) infiltration for anticancer immunotherapy.

Strategies of engineering nanomedicines for tumor retention

The retention of therapeutic agents in solid tumors at sufficient concentration and duration is crucial for their antitumor effects. Given the important contribution of nanomedicines to oncology, we herein summarized two major strategies of nanomedicines for tumor retention, such as transformation- and interactions-mediated strategies. The transformation-mediated retention strategy was achieved by enlarging particle size of nanomedicines or modulating the morphology into fibrous structures, while the interactions-mediated retention strategy was accomplished by modulating nanomedicines to promote their interactions with versatile cells or components in tumors. Moreover, we provide some considerations and perspectives of tumor-retaining nanomedicines for effective cancer therapy.