Reprogramming the T cell response to cancer by simultaneous, nanoparticle-mediated PD-L1 inhibition and immunogenic cell death

Enhancing cancer immunotherapy: Exploring strategies to target the PD-1/PD-L1 axis and analyzing the associated patent, regulatory, and clinical trial landscape

Cancer treatment modalities and their progression is guided by the specifics of cancer, including its type and site of localization. Surgery, radiation, and chemotherapy are the most often used conventional treatments. Conversely, emerging treatment techniques include immunotherapy, hormone therapy, anti-angiogenic therapy, dendritic cell-based immunotherapy, and stem cell therapy. Immune checkpoint inhibitors' anticancer properties have drawn considerable attention in recent studies in the cancer research domain. Programmed Cell Death Protein-1 (PD-1) and its ligand (PD-L1) checkpoint pathway are key regulators of the interactions between activated T-cells and cancer cells, protecting the latter from immune destruction. When the ligand PD-L1 attaches to the receptor PD-1, T-cells are prevented from destroying cells that contain PD-L1, including cancer cells. The PD-1/PD-L1 checkpoint inhibitors block them, boosting the immune response and strengthening the body's defenses against tumors. Recent years have seen incredible progress and tremendous advancement in developing anticancer therapies using PD-1/PD-L1 targeting antibodies. While immune-related adverse effects and low response rates significantly limit these therapies, there is a need for research on methods that raise their efficacy and lower their toxicity. This review discusses various recent innovative nanomedicine strategies such as PLGA nanoparticles, carbon nanotubes and drug loaded liposomes to treat cancer targeting PD-1/PD-L1 axis. The biological implications of PD-1/PD-L1 in cancer treatment and the fundamentals of nanotechnology, focusing on the novel strategies used in nanomedicine, are widely discussed along with the corresponding guidelines, clinical trial status, and the patent landscape of such formulations.

Nano-Delivery of Immunogenic Cell Death Inducers and Immune Checkpoint Blockade Agents: Single-Nanostructure Strategies for Enhancing Immunotherapy

Cancer immunotherapy has revolutionized oncology by harnessing the patient's immune system to target and eliminate cancer cells. However, immune checkpoint blockades (ICBs) face limitations such as low response rates, particularly in immunologically 'cold' tumors. Enhancing tumor immunogenicity through immunogenic cell death (ICD) inducers and advanced drug delivery systems represents a promising solution. This review discusses the development and application of various nanocarriers, including polymeric nanoparticles, liposomes, peptide-based nanoparticles, and inorganic nanoparticles, designed to deliver ICD inducers and ICBs effectively. These nanocarriers improve therapeutic outcomes by converting cold tumors into hot tumors, thus enhancing immune responses and reducing systemic toxicity. By focusing on single-nanoparticle systems that co-deliver both ICD inducers and ICBs, this review highlights their potential in achieving higher drug concentrations at tumor sites, improving pharmacokinetics and pharmacodynamics, and facilitating clinical translation. Future research should aim to optimize these nanocarrier systems for better in vivo performance and clinical applications, ultimately advancing cancer immunotherapy.

Engineering nanomedicines for immunogenic eradication of cancer cells: Recent trends and synergistic approaches

Resistance to cancer immunotherapy is mainly attributed to poor tumor immunogenicity as well as the immunosuppressive tumor microenvironment (TME) leading to failure of immune response. Numerous therapeutic strategies including chemotherapy, radiotherapy, photodynamic, photothermal, magnetic, chemodynamic, sonodynamic and oncolytic therapy, have been developed to induce immunogenic cell death (ICD) of cancer cells and thereby elicit immunogenicity and boost the antitumor immune response. However, many challenges hamper the clinical application of ICD inducers resulting in modest immunogenic response. Here, we outline the current state of using nanomedicines for boosting ICD of cancer cells. Moreover, synergistic approaches used in combination with ICD inducing nanomedicines for remodeling the TME via targeting immune checkpoints, phagocytosis, macrophage polarization, tumor hypoxia, autophagy and stromal modulation to enhance immunogenicity of dying cancer cells were analyzed. We further highlight the emerging trends of using nanomaterials for triggering amplified ICD-mediated antitumor immune responses. Endoplasmic reticulum localized ICD, focused ultrasound hyperthermia, cell membrane camouflaged nanomedicines, amplified reactive oxygen species (ROS) generation, metallo-immunotherapy, ion modulators and engineered bacteria are among the most innovative approaches. Various challenges, merits and demerits of ICD inducer nanomedicines were also discussed with shedding light on the future role of this technology in improving the outcomes of cancer immunotherapy.

Optimizing long-term stability of siRNA using thermoassemble ionizable reverse pluronic-Bcl2 micelleplexes

Thermosassemble Ionizable Reverse Pluronic (TIRP) platform stands out for its distinctive combination of thermoassemble and ionizable features, effectively overcoming challenges in previous siRNA delivery systems. This study opens up a formation for long-term stabilization, and high loading of siRNA, specifically crafted for targeting oncogenic pathways. TIRP-Bcl2 self-assembles into a unique micelle structure with a nanodiameter of 75.8 ± 5.7 nm, efficiently encapsulating Bcl2 siRNA while maintaining exceptional colloidal stability at 4 °C for 8 months, along with controlled release profiles lasting 180 h. The dual ionizable headgroup enhance the siRNA loading and the revers pluronic unique structural orientation enhance the stability of the siRNA. The thermoassemble of TIRP-Bcl2 facilitates flexi-rigid response to mild hyperthermia, enhancing deep tissue penetration and siRNA release in the tumor microenvironment. This responsive behavior improves intracellular uptake and gene silencing efficacy in cancer cells. TIRP, with its smaller particle size and reverse pluronic nature, efficiently transports siRNA across the blood-brain barrier, holding promise for revolutionizing glioblastoma (GBM) treatment. TIRP-Bcl2 shows significant potential for precise, personalized therapies, promising prolonged siRNA delivery and in vitro/in vivo stability. This research opens avenues for further exploration and clinical translation of this innovative nanocarrier system across different cancers.

A Nucleic Acid-Based LYTAC Plus Platform to Simultaneously Mediate Disease-Driven Protein Downregulation

Protein degradation techniques, such as proteolysis-targeting chimeras (PROTACs) and lysosome-targeting chimeras (LYTACs), have emerged as promising therapeutic strategies for the treatment of diseases. However, the efficacy of current protein degradation methods still needs to be improved to address the complex mechanisms underlying diseases. Herein, a LYTAC Plus hydrogel engineered is proposed by nucleic acid self-assembly, which integrates a gene silencing motif into a LYTAC construct to enhance its therapeutic potential. As a proof-of-concept study, vascular endothelial growth factor receptor (VEGFR)-binding peptides and mannose-6 phosphate (M6P) moieties into a self-assembled nucleic acid hydrogel are introduced, enabling its LYTAC capability. Small interference RNAs (siRNAs) is then employed that target the angiopoietin-2 (ANG-2) gene as cross-linkers for hydrogel formation, giving the final LYTAC Plus hydrogel gene silencing ability. With dual functionalities, the LYTAC Plus hydrogel demonstrated effectiveness in simultaneously reducing the levels of VEGFR-2 and ANG-2 both in vitro and in vivo, as well as in improving therapeutic outcomes in treating neovascular age-related macular degeneration in a mouse model. As a general material platform, the LYTAC Plus hydrogel may possess great potential for the treatment of various diseases and warrant further investigation.

Effects of immunogenic cell death-inducing chemotherapeutics on the immune cell activation and tertiary lymphoid structure formation in melanoma

Background

The infiltration and activation of immune cells in the tumor microenvironment (TIME) affect the prognosis of patients with cancer. Tertiary lymphoid structure (TLS) formation favors tumour- infiltrating-lymphocyte (TIL) recruitment and is regarded as an important indicator of good prognosis associated with immunotherapy in patients with tumors. Chemotherapy is currently one of the most commonly used clinical treatment methods. However, there have been no clear report to explore the effects of different types of chemotherapy on TLS formation in the TIME. This study examined the effects of immunogenic cell death (ICD)-inducing chemotherapeutics on immune cells, high-endothelial venules (HEV), and TLSs in mouse melanomas.

Methods

Doxorubicin (an ICD inducer), gemcitabine (non-ICD inducer), and a combination of the two drugs was delivered intra-peritoneally to B16F1-loaded C57BL/6 mice. The infiltration of immune cells into tumor tissues was evaluated using flow cytometry. HEV and TLS formation was assessed using immunohistochemistry and multiple fluorescent immunohistochemical staining.

Results

Doxorubicin alone, gemcitabine alone, and the two-drug combination all slowed tumor growth, with the combined treatment demonstrating a more pronounced effect. Compared with the control group, the doxorubicin group showed a higher infiltration of CD8+ T cells and tissue-resident memory T cells (TRM) and an increase in the secretion of interferon-γ, granzyme B, and perforin in CD8+ T subsets and activation of B cells and dendritic cells. Doxorubicin alone and in combination with gemcitabine decreased regulatory T cells in the TIME. Moreover, doxorubicin treatment promoted the formation of HEV and TLS. Doxorubicin treatment also upregulated the expression of programmed cell death protein (PD)-1 in CD8+ T cells and programmed cell death protein ligand (PD-L)1 in tumor cells.

Conclusions

These results indicate that doxorubicin with an ICD reaction promotes TLS formation and increases PD-1/PD-L1 expression in tumor tissues. The results demonstrate the development of a therapeutic avenue using combined immune checkpoint therapy.

Recent progress, perspectives, and issues of engineered PD-L1 regulation nano-system to better cure tumor: A review

Currently, immune checkpoint blockade (ICB) therapies that target the programmed cell death ligand-1 (PD-L1) have been used as revolutionary cancer treatments in the clinic. Apart from restoring the antitumor response of cytotoxic T cells by blocking the interaction between PD-L1 on tumor cells and programmed cell death-1 (PD-1) on T cells, PD-L1 proteins were also newly revealed to possess the capacity to accelerate DNA damage repair (DDR) and enhance tumor growth through multiple mechanisms, leading to the impaired efficacy of tumor therapies. Nevertheless, current free anti-PD-1/PD-L1 therapy still suffered from poor therapeutic outcomes in most solid tumors due to the non-selective tumor accumulation, ineludible severe cytotoxic effects, as well as the common occurrence of immune resistance. Recently, nanoparticles with efficient tumor-targeting capacity, tumor-responsive prosperity, and versatility for combination therapy were identified as new avenues for PD-L1 targeting cancer immunotherapies. In this review, we first summarized the multiple functions of PD-L1 protein in promoting tumor growth, accelerating DDR, as well as depressing immunotherapy efficacy. Following this, the effects and mechanisms of current clinically widespread tumor therapies on tumor PD-L1 expression were discussed. Then, we reviewed the recent advances in nanoparticles for anti-PD-L1 therapy via using PD-L1 antibodies, small interfering RNA (siRNA), microRNA (miRNA), clustered, regularly interspaced, short palindromic repeats (CRISPR), peptide, and small molecular drugs. At last, we discussed the challenges and perspectives to promote the clinical application of nanoparticles-based PD-L1-targeting therapy.

PEI-Based Nanoparticles for Tumor Immunotherapy via In Situ Antigen-Capture Triggered by Photothermal Therapy

Activating a tumor antigen-specific immune response is key to the success of tumor immunotherapy and the development of personalized antitumor therapy. Nanocarriers can capture, enrich, and protect in situ produced tumor antigens due to immunogenic cell death (ICD), thus enhancing the tumor-specific immune response. Developing multifunctional nanocarriers that combine multiple antigen capturing mechanisms is crucial to the activation of tumor-specific immune responses. In this study, polyethylenimine (PEI) was employed as a main building block to construct a series of multifunctional indocyanine green (ICG)-loaded nanoparticles to capture antigens via multiple mechanisms: electrostatic interactions with PEI, hydrophobic interactions with the thermosensitive segment (POEGMA300), and covalent bonding with the pyridyl disulfide (PDS) groups, respectively. Their capacity of ICD induction, tumor antigen-capture, and antitumor immune responses were evaluated. Both the intrinsic toxicity of PEI and the ICG-mediated photothermal effect were responsible for inducing ICD. The positively charged PEI segment exhibited the best antigen-capturing ability via electrostatic interactions, promoted bone marrow-derived dendritic cell maturation and CD8+ T cell proliferation, and elicited antitumor immune responses in vivo. PDS groups bonded antigens covalently and significantly contributed to the suppression of distant tumor growth. Although the thermosensitive hydrophobic polymer segment did not contribute positively to antigen capture or tumor growth inhibition, NPs containing all of the functional modules prolonged the survival of tumor-bearing mice more than other treatments. This study provides more chemical insights into the design of polymer-based in situ nanovaccines against cancer.

Nanoassembly of doxorubicin-conjugated polyphosphoester and siRNA simultaneously elicited macrophage- and T cell- mediated anticancer immune response for cancer therapy

Efficiently reawakening immune cells, including T cells and macrophages, to eliminate tumor cells is a promising strategy for cancer treatment, but remains a huge challenge nowadays. Herein, a nanoassembly formed by doxorubicin (DOX)-conjugated polyphosphoester (PP-(hDOX)) and CD47-targeting siRNA (siCD47) via electrostatic and π-π stacking interactions, termed as PP-(hDOX&siCD47), was developed to reawaken the T cell and macrophage-mediated anticancer activity. The PP-(hDOX&siCD47) could efficiently blockade antiphagocytic signal by downregulation of CD47 expression to reactive macrophage-mediated anticancer immunotherapy. Moreover, the conjugated DOX of PP-(hDOX&siCD47) can perform the chemotherapy towards tumor cells and also elicit the T cell-mediated anticancer immune response via immunogenic cell death (ICD) effect. Therefore, the PP-(hDOX&siCD47) treatment could significantly increase M1-like macrophages proportion and tumor infiltration of CD8+ T cells, while the proportions of regulatory T cells (Treg) and myeloid-derived suppressor cells (MDSC) were considerably reduced in tumor tissue, eventually achieving significantly tumor growth inhibition. Overall, this study provides a simple siRNA and DOX codelivery approach to simultaneously elicit the macrophage- and T cell-mediated anticancer immune response for cancer therapy.

Promotion of ICD via Nanotechnology

Immunotherapy represents the most promising treatment strategy for cancer, but suffers from compromised therapeutic efficiency due to low immune activity of tumor cells and an immunosuppressive microenvironment, which significantly hampers the clinical translations of this treatment strategy. To promote immunotherapy with desired therapeutic efficiency, immunogenic cell death (ICD), a particular type of death capable of reshaping body's antitumor immune activity, has drawn considerable attention due to the potential to stimulate a potent immune response. Still, the potential of ICD effect remains unsatisfactory because of the intricate tumor microenvironment and multiple drawbacks of the used inducing agents. ICD has been thoroughly reviewed so far with a general classification of ICD as a kind of immunotherapy strategy and repeated discussion of the related mechanism. However, there are no published reviews, to the authors' knowledge, providing a systematic summarization on the enhancement of ICD via nanotechnology. For this purpose, this review first discusses the four stages of ICD according to the development mechanisms, followed by a comprehensive description on the use of nanotechnology to enhance ICD in the corresponding four stages. The challenges of ICD inducers and possible solutions are finally summarized for future ICD-based enhanced immunotherapy.

Liposomal co-delivery of toll-like receptors 3 and 7 agonists induce a hot triple-negative breast cancer immune environment

Triple-negative breast cancer (TNBC) is highly aggressive and has no standard treatment. Although being considered as an alternative to conventional treatments for TNBC, immunotherapy has to deal with many challenges that hinder its efficacy, particularly the poor immunogenic condition of the tumor microenvironment (TME). Herein, we designed a liposomal nanoparticle (LN) platform that delivers simultaneously toll-like receptor 7 (imiquimod, IQ) and toll-like receptor 3 (poly(I:C), IC) agonists to take advantage of the different toll-like receptor (TLR) signaling pathways, which enhances the condition of TME from a "cold" to a "hot" immunogenic state. The optimized IQ/IC-loaded LN (IQ/IC-LN) was effectively internalized by cancer cells, macrophages, and dendritic cells, followed by the release of the delivered drugs and subsequent stimulation of the TLR3 and TLR7 signaling pathways. This stimulation encouraged the secretion of type I interferon (IFN-α, IFN-β) and CXCLl0, a T-cell and antigen-presenting cells (APCs) recruitment chemokine, from both cancer cells and macrophages and polarized macrophages to the M1 subtype in in vitro studies. Notably, systemic administration of IQ/IC-LN allowed for the high accumulation of drug content in the tumor, followed by the effective uptake by immune cells in the TME. IQ/IC-LN treatment comprehensively enhanced the immunogenic condition in the TME, which robustly inhibited tumor growth in tumor-bearing mice. Furthermore, synergistic antitumor efficacy was obtained when the IQ/IC-LN-induced immunogenic state in TME was combined with anti-PD1 antibody therapy. Thus, our results suggest the potential of combining 2 TLR agonists to reform the TME from a "cold" to a "hot" state, supporting the therapeutic efficacy of immune checkpoint inhibitors.

Shaping the "hot" immunogenic tumor microenvironment by nanoparticles co-delivering oncolytic peptide and TGF-β1 siRNA for boosting checkpoint blockade therapy

Induction of potent immune responses toward tumors remains challenging in cancer immunotherapy, in which it only showed benefits in a minority of patients with "hot" tumors, which possess pre-existing effector immune cells within the tumor. In this study, we proposed a nanoparticle-based strategy to fire up the "cold" tumor by upregulating the components associated with T and NK cell recruitment and activation and suppressing TGF-β1 secretion by tumor cells. Specifically, LTX-315, a first-in-class oncolytic cationic peptide, and TGF-β1 siRNA were co-entrapped in a polymer-lipid hybrid nanoparticle comprising PLGA, DSPE-mPEG, and DSPE-PEG-conjugated with cRGD peptide (LTX/siR-NPs). The LTX/siR-NPs showed significant inhibition of TGF-β1 expression, induction of type I interferon release, and triggering immunogenic cell death (ICD) in treated tumor cells, indicated via the increased levels of danger molecules, an in vitro setting. The in vivo data showed that the LTX/siR-NPs could effectively protect the LTX-315 peptide from degradation in serum, which highly accumulated in tumor tissue. Consequently, the LTX/siR-NPs robustly suppressed TGF-β1 production by tumor cells and created an immunologically active tumor with high infiltration of antitumor effector immune cells. As a result, the combination of LTX/siR-NP treatment with NKG2A checkpoint inhibitor therapy remarkably increased numbers of CD8+NKG2D+ and NK1.1+NKG2D+ within tumor masses, and importantly, inhibited the tumor growth and prolonged survival rate of treated mice. Taken together, this study suggests the potential of the LTX/siR-NPs for inflaming the "cold" tumor for potentiating the efficacy of cancer immunotherapy.

Recent advances in targeting myeloid-derived suppressor cells and their applications to radiotherapy

Myeloid-derived suppressor cells (MDSCs) are a group of heterogenous immature myeloid cells with potent immune suppressive properties that not only constrain anti-tumor immune activation and functions, promote tumor progression, but also contribute to treatment resistance and tumor relapse. Targeting MDSCs may be a promising new cancer treatment method, but there is still a problem of low treatment efficiency. Combined application with radiotherapy may be a potential method to solve this problem. Drug delivery systems (DDSs) provide more efficient targeted drug delivery capability and can reduce the toxicity and side effects of drugs. Recent advance in DDSs targeting development, recruitment, differentiation, and elimination of MDSCs have shown promising effect in reversing immune inhibition and in overcoming radiotherapy resistance. In this review, we systematically summarized DDSs applied to target MDSCs for the first time, and classified and discussed it according to its different mechanisms of action. In addition, this paper also reviewed the biological characteristics of MDSCs and their role in the initiation, progression, and metastasis of cancer. Moreover, this review also summarizes the role of DDSs targeting MDSCs in radiosensitization. Finally, the future development of DDSs targeting MDSCs is also prospected.

A scoping review on the significance of programmed death-ligand 1-inhibiting microRNAs in non-small cell lung treatment: A single-cell RNA sequencing-based study

BACKGROUND

The programmed death-ligand 1 (PD-L1)/PD-1 axis is one of the well-established inhibitory axes in regulating immune responses. Besides the significance of tumor-intrinsic PD-L1 expression in immune evasion, its oncogenic role has been implicated in various malignancies, like non-small cell lung cancer (NSCLC). As small non-coding RNAs, microRNAs (miRs) have pivotal roles in cancer biology. The current study aimed to systematically review the current knowledge about the significance of PD-L1-inhibiting miRs in NSCLC inhibition and their underlying mechanisms.

MATERIALS AND METHODS

We conducted the current scoping review based on the PRISMA-ScR statement. We systematically searched Embase, Scopus, Web of Science, PubMed, Ovid, EBSCO, ProQuest, Cochrane Library, African Index Medicus, and Pascal-Francis up to 4 April 2021. We also performed in silico tumor bulk RNA sequencing and single-cell RNA sequencing to further the current knowledge of the non-coding RNA-mediated tumor-intrinsic PD-L1 regulation and the PD-L1/PD-1 axis in NSCLC.

RESULTS

The ectopic expression of hsa-miR-194-5p, hsa-miR-326, hsa-miR-526b-3p, hsa-miR-34a-5p, hsa-miR-34c-5p, hsa-miR-138-5p, hsa-miR-377-3p, hsa-let-7c-5p, hsa-miR-200a-3p, hsa-miR-200b-3p, hsa-miR-200c-3p, and hsa-miR-197-3p, as PD-L1-inhibiting miR, inhibits NSCLC development. These PD-L1-inhibiting miRs can substantially regulate the cell cycle, migration, clonogenicity, invasion, apoptosis, tumor chemosensitivity, and host anti-tumoral immune responses. Based on single-cell RNA sequencing results, PD-L1 inhibition might liberate the tumor-infiltrated CD8+ T-cells and dendritic cells (DCs)-mediated anti-tumoral immune responses via disrupting the PD-L1/PD-1 axis.

CONCLUSION

Given the promising preclinical results of these PD-L1-inhibiting miRs in inhibiting NSCLC development, their ectopic expression might improve NSCLC patients' prognosis; however, further studies are needed to translate this approach into clinical practice.

The role of T-cells in head and neck squamous cell carcinoma: From immunity to immunotherapy

Head and neck squamous cell carcinoma (HNSCC) encompass a group of complex entities of tumours affecting the aerodigestive upper tract. The main risk factors are strongly related to tobacco and alcohol consumption, but also HPV infection is often associated. Surgery, radiotherapy and/or chemotherapy are the standard treatments, though the 5-year overall survival is less than 50%. The advances in genomics, molecular medicine, immunology, and nanotechnology have shed a light on tumour biology which helps clinical researchers to obtain more efficacious and less toxic therapies. Head and neck tumours possess different immune escape mechanisms including diminishing the immune response through modulating immune checkpoints, in addition to the recruitment and differentiation of suppressive immune cells. The insights into the HNSCC biology and its strong interaction with the tumour microenvironment highlights the role of immunomodulating agents. Recently, the knowledge of the immunological features of these tumours has paved the way for the discovery of effective biomarkers that allow a better selection of patients with odds of improving overall survival through immunotherapy. Specially biomarkers regarding immune checkpoint inhibitors antibodies, such as anti-PD-1/PD-L1 and anti-CTLA-4 in combination with standard therapy or as monotherapy. New immunotherapies to treat head and neck cancer carcinomas, such as CAR T cells and nanoparticles have been the center of attention and in this review, we discuss the necessity of finding targets for the T cell in the cancer cells to generate CAR T cells, but also the relevance of evaluating specificity and safety of those therapies.

Opportunities for Nitric Oxide in Potentiating Cancer Immunotherapy

Despite nearly 30 years of development and recent highlights of nitric oxide (NO) donors and NO delivery systems in anticancer therapy, the limited understanding of exogenous NO's effects on the immune system has prevented their advancement into clinical use. In particular, the effects of exogenously delivered NO differing from that of endogenous NO has obscured how the potential and functions of NO in anticancer therapy may be estimated and exploited despite the accumulating evidence of NO's cancer therapy-potentiating effects on the immune system. After introducing their fundamentals and characteristics, this review discusses the current mechanistic understanding of NO donors and delivery systems in modulating the immunogenicity of cancer cells as well as the differentiation and functions of innate and adaptive immune cells. Lastly, the potential for the complex modulatory effects of NO with the immune system to be leveraged for therapeutic applications is discussed in the context of recent advancements in the implementation of NO delivery systems for anticancer immunotherapy applications. SIGNIFICANCE STATEMENT: Despite a 30-year history and recent highlights of nitric oxide (NO) donors and delivery systems as anticancer therapeutics, their clinical translation has been limited. Increasing evidence of the complex interactions between NO and the immune system has revealed both the potential and hurdles in their clinical translation. This review summarizes the effects of exogenous NO on cancer and immune cells in vitro and elaborates these effects in the context of recent reports exploiting NO delivery systems in vivo in cancer therapy applications.

Co-Delivery of Doxorubicin and Anti-PD-L1 Peptide in Lipid/PLGA Nanocomplexes for the Chemo-Immunotherapy of Cancer

The combined delivery of chemotherapeutics with checkpoint inhibitors of the PD-1/PD-L1 pathway provides a new approach for cancer treatment. Small-molecule peptide inhibitors possess short production cycle, low immunogenicity, and fewer side effects; however, their potential in cancer therapy is hampered by the rapid biodegradation and a nanocarrier is needed for efficient drug delivery. Herein, anticancer drug doxorubicin (DOX) and PD-L1 inhibitor peptide P-12 are co-loaded by a lipid polymer nanocomplex based on poly(lactic-co-glycolic acid) (PLGA) and DSPE-PEG. Octaarginine (R8)-conjugated DSPE-PEG renders the LPN efficient internalization by cancer cells. The optimal nanomedicine LPN-30-R8^2K@DP shows a diameter of 125 nm and a DOX and P-12 loading content of 5.0 and 6.2%, respectively. LPN-30-R8^2K@DP exhibits good physiological stability and enhanced cellular uptake by cancer cells. It successfully induces immunogenic cell death and PD-L1 blockade in CT26 cancer cells. The in vivo antitumor study further suggests that co-loaded nanomedicine efficiently suppresses CT26 tumor growth and elicits antitumor immune response. This study manifests that lipid polymer nanocomplexes are promising drug carriers for the efficient chemo-immunotherapy of cancer.

Integration of miRNA:mRNA Co-Expression Revealed Crucial Mechanisms Modulated in Immunogenic Cancer Cell Death

Immunogenic cell death (ICD) in cancer represents a functionally unique therapeutic response that can induce tumor-targeting immune responses. ICD is characterized by the exposure and release of numerous damage-associated molecular patterns (DAMPs), which confer adjuvanticity to dying cancer cells. The spatiotemporally defined emission of DAMPs during ICD has been well described, whereas the epigenetic mechanisms that regulate ICD hallmarks have not yet been deeply elucidated. Here, we aimed to examine the involvement of miRNAs and their putative targets using well-established in vitro models of ICD. To this end, B cell lymphoma (Mino) and breast cancer (MDA-MB-231) cell lines were exposed to two different ICD inducers, the combination of retinoic acid (RA) and interferon-alpha (IFN-α) and doxorubicin, and to non ICD inducers such as gamma irradiation. Then, miRNA and mRNA profiles were studied by next generation sequencing. Co-expression analysis identified 16 miRNAs differentially modulated in cells undergoing ICD. Integrated miRNA-mRNA functional analysis revealed candidate miRNAs, mRNAs, and modulated pathways associated with Immune System Process (GO Term). Specifically, ICD induced a distinctive transcriptional signature hallmarked by regulation of antigen presentation, a crucial step for proper activation of immune system antitumor response. Interestingly, the major histocompatibility complex class I (MHC-I) pathway was upregulated whereas class II (MHC-II) was downregulated. Analysis of MHC-II associated transcripts and HLA-DR surface expression confirmed inhibition of this pathway by ICD on lymphoma cells. miR-4284 and miR-212-3p were the strongest miRNAs upregulated by ICD associated with this event and miR-212-3p overexpression was able to downregulate surface expression of HLA-DR. It is well known that MHC-II expression on tumor cells facilitates the recruitment of CD4+ T cells. However, the interaction between tumor MHC-II and inhibitory coreceptors on tumor-associated lymphocytes could provide an immunosuppressive signal that directly represses effector cytotoxic activity. In this context, MHC-II downregulation by ICD could enhance antitumor immunity. Overall, we found that the miRNA profile was significantly altered during ICD. Several miRNAs are predicted to be involved in the regulation of MHC-I and II pathways, whose implication in ICD is demonstrated herein for the first time, which could eventually modulate tumor recognition and attack by the immune system.

Walking Dead Tumor Cells for Targeted Drug Delivery Against Lung Metastasis of Triple-Negative Breast Cancer

Lung metastasis is challenging in patients with triple-negative breast cancer (TNBC). Surgery is always not available due to the dissemination of metastatic foci and most drugs are powerless because of poor retention at metastatic sites. TNBC cells generate an inflamed microenvironment and overexpress adhesive molecules to promote invasion and colonization. Herein, "walking dead" TNBC cells are developed through conjugating anti-PD-1 (programmed death protein 1 inhibitor) and doxorubicin (DOX)-loaded liposomes onto cell corpses for temporal chemo-immunotherapy against lung metastasis. The walking dead TNBC cells maintain plenary tumor antigens to conduct vaccination effects. Anti-PD-1 antibodies are conjugated to cell corpses via reduction-activated linker, and DOX-loaded liposomes are attached by maleimide-thiol coupling. This anchor strategy enables rapid release of anti-PD-1 upon reduction conditions while long-lasting release of DOX at inflamed metastatic sites. The walking dead TNBC cells improve pulmonary accumulation and local retention of drugs, reprogram the lung microenvironment through damage-associated molecular patterns (DAMPs) and PD-1 blockade, and prolong overall survival of lung metastatic 4T1 and EMT6-bearing mice. Taking advantage of the walking dead TNBC cells for pulmonary preferred delivery of chemotherapeutics and checkpoint inhibitors, this study suggests an alternative treatment option of chemo-immunotherapy to augment the efficacy against lung metastasis.

Recent Advances in Nanoparticles-Based Platforms Targeting the PD-1/PD-L1 Pathway for Cancer Treatment

Immune checkpoint inhibitors (ICIs) targeting the PD-1/PD-L1 axis showed remarkable improvements in overall response and patient survival, which changed the treatment landscape for multiple cancer types. However, the majority of patients receiving ICIs are either non-responders or eventually develop secondary resistance. Meanwhile, immunological homeostasis would be destroyed as T cell functions are activated excessively, leading to immune-related adverse events (irAEs). Clinically, a large number of irAEs caused by ICIs occurred and affected almost every organ system, resulting in the discontinuation or even the termination of the ongoing therapy. Therefore, researchers are exploring methods to overcome the situations of insufficient accumulation of these drugs in tumor sites and severe side effects. PD-1/PD-L1-targeted agents encapsulated in nanoparticles have emerged as novel drug delivery systems for improving the delivery efficacy, enhancing immune response and minimizing side effects in cancer treatment. Nanocarriers targeting the PD-1/PD-L1 axis showed enhanced functionalities and improved the technical weaknesses based on their reduced off-target effects, biocompatible properties, multifunctional potential and biomimetic modifications. Here, we summarize nanoparticles which are designed to directly target the PD-1/PD-L1 axis. We also discuss the combination of anti-PD-1/PD-L1 agents and other therapies using nanomedicine-based treatments and their anticancer effects, safety issues, and future prospects.

Mannosylated poly(acrylic acid)-coated mesoporous silica nanoparticles for anticancer therapy

Although mesoporous silica nanoparticles (MSNs) are widely used as anticancer drug carriers, unmodified MSNs induce off-target effects and at high doses, there are adverse effects of hemolysis because of the interaction with the silanol group on the surface and cells. In this study, we developed doxorubicin (DOX)-loaded MSNs coated with mannose grafted poly (acrylic acid) copolymer (DOX@MSNs-man-g-PAA) to enhance the hemocompatibility and target efficacy to cancer cells. This uniform nanosized DOX@MSNs-man-g-PAA showed sustained and pH-dependent drug release with improved hemocompatibility over the bare MSNs. The uptake of the DOX@MSN-man-g-PAA in breast cancer cells was significantly improved by mannose receptor-mediated endocytosis, which showed significant increasing intracellular ROS and changes in mitochondrial membrane potential. This formulation exhibited superior tumor-suppressing activity in the MDA-MB-231 cells inoculated mice. Overall, the present study suggested the possibility of the copolymer-coated MSNs as drug carriers for cancer therapy.

Huaier Induces Immunogenic Cell Death Via CircCLASP1/PKR/eIF2α Signaling Pathway in Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most lethal breast cancer subtype owing to the lack of targeted therapeutic strategies. Immunogenic cell death (ICD), a modality of regulated cancer cell death, offered a novel option for TNBC via augmenting tumor immunogenic microenvironment. However, few ICD-inducing agents are currently available. Here, we showed that Trametes robiniophila Murr (Huaier) triggered ICD in TNBC cells by promoting cell surface calreticulin (CRT) exposure, and increasing release of adenosine triphosphate (ATP) and high-mobility group protein B1 (HMGB1). Co-culturing with Huaier-treated TNBC cells efficiently enhanced the maturation of dendritic cells (DCs), which was further validated via cell-based vaccination assay. In the xenograft mouse model, oral administration of Huaier led to tumor-infiltrating lymphocytes (TILs) accumulation and significantly delayed tumor growth. Besides, depletion of endogenous T cells obviously abrogated the effect. Mechanically, Huaier could elicit endoplasmic reticulum (ER) stress-associated ICD through eIF2α signaling pathway. Further studies revealed that circCLASP1 was involved in the Huaier-induced immunogenicity by binding with PKR in the cytoplasm and thus blocking its degradation. Taken together, we highlighted an essential role of circCLASP1/PKR/eIF2α axis in Huaier-induced ICD. The findings of our study carried significant translational potential that Huaier might serve as a promising option to achieve long-term tumor remission in patients with TNBC.

Immunogenic Cell Death Activates the Tumor Immune Microenvironment to Boost the Immunotherapy Efficiency

Tumor immunotherapy is only effective in a fraction of patients due to a low response rate and severe side effects, and these challenges of immunotherapy in clinics can be addressed through induction of immunogenic cell death (ICD). ICD is elicited from many antitumor therapies to release danger associated molecular patterns (DAMPs) and tumor‐associated antigens to facilitate maturation of dendritic cells (DCs) and infiltration of cytotoxic T lymphocytes (CTLs). The process can reverse the tumor immunosuppressive microenvironment to improve the sensitivity of immunotherapy. Nanostructure‐based drug delivery systems (NDDSs) are explored to induce ICD by incorporating therapeutic molecules for chemotherapy, photosensitizers (PSs) for photodynamic therapy (PDT), photothermal conversion agents for photothermal therapy (PTT), and radiosensitizers for radiotherapy (RT). These NDDSs can release loaded agents at a right dose in the right place at the right time, resulting in greater effectiveness and lower toxicity. Immunotherapeutic agents can also be combined with these NDDSs to achieve the synergic antitumor effect in a multi‐modality therapeutic approach. In this review, NDDSs are harnessed to load multiple agents to induce ICD by chemotherapy, PDT, PTT, and RT in combination of immunotherapy to promote the therapeutic effect and reduce side effects associated with cancer treatment.

Stimuli-responsive nano vehicle enhances cancer immunotherapy by coordinating mitochondria-targeted immunogenic cell death and PD-L1 blockade

Induction of immunogenic cell death promotes antitumor immunity against cancer. However, majority of clinically-approved drugs are unable to elicit sufficient ICD. Here, our study revealed that mitochondria-targeted delivery of doxorubicin (DOX) massively amplified ICD via substantial generation of reactive oxygen species (ROS) after mitochondrial damage. The underlying mechanism behind increased ICD was further demonstrated to be ascribed to two pathways: (1) ROS elevated endoplasmic reticulum (ER) stress, leading to surface exposure of calreticulin; (2) ROS promoted release of various mitochondria-associated damage molecules including mitochondrial transcription factor A. Nevertheless, adaptive upregulation of PD-L1 was found after such ICD-inducing treatment. To overcome such immunosuppressive feedback, we developed a tumor stimuli-responsive nano vehicle to simultaneously exert mitochondrial targeted ICD induction and PD-L1 blockade. The nano vehicle was self-assembled from ICD-inducing copolymer and PD-L1 blocking copolymer, and possessed long-circulating property which contributed to better tumor accumulation and mitochondrial targeting. As a result, the nano vehicle remarkably activated antitumor immune responses and exhibited robust antitumor efficacy in both immunogenic and non-immunogenic tumor mouse models.

Bacteria as Nanoparticle Carriers for Immunotherapy in Oncology

The use of nanocarriers to deliver antitumor agents to solid tumors must overcome biological barriers in order to provide effective clinical responses. Once within the tumor, a nanocarrier should navigate into a dense extracellular matrix, overcoming intratumoral pressure to push it out of the diseased tissue. In recent years, a paradigm change has been proposed, shifting the target of nanomedicine from the tumoral cells to the immune system, in order to exploit the natural ability of this system to capture and interact with nanometric moieties. Thus, nanocarriers have been engineered to interact with immune cells, with the aim of triggering specific antitumor responses. The use of bacteria as nanoparticle carriers has been proposed as a valuable strategy to improve both the accumulation of nanomedicines in solid tumors and their penetration into the malignancy. These microorganisms are capable of propelling themselves into biological environments and navigating through the tumor, guided by the presence of specific molecules secreted by the diseased tissue. These capacities, in addition to the natural immunogenic nature of bacteria, can be exploited to design more effective immunotherapies that yield potent synergistic effects to induce efficient and selective immune responses that lead to the complete eradication of the tumor.

Targeting the PD-1/PD-L1 axis for cancer treatment: a review on nanotechnology

Although nanomedicines have been in the oncology field for almost three decades with the introduction of doxil, only a few nanomedicine products have reached approval. Can nanotechnology be a realistic tool to reduce the number of hospital beds? At present, several clinically approved anti-PD-1/PD-L1 antibodies or CAR T cell-based therapies are available; however, the immunotherapy field is far from mature. Will immunotherapy be the fourth pillar of cancer treatment? In this review, we summarized the current status of immunotherapy using PD-1/PD-L1-targeting nanocarriers. The knowledge on material science, therapeutic agents and formulation designs could pave the way for high-efficacy treatment outcomes.

Nanovaccines silencing IL-10 production at priming phase for boosting immune responses to melanoma

Despite the significant efforts in developing cancer vaccines, there are still numerous challenges that need to be addressed to ensure their clinical efficacy. Herein, a lymphatic dendritic cell (DC)-targeted artificial nanovaccine mimicking tumor cell membrane (ATM-NV) is developed to boost effector immune response and control immunosuppression simultaneously. The NVs are formulated with lipids, tumor cell membrane proteins, imiquimod (IMQ), and IL-10 siRNA. IL-10 siRNA is incorporated to inhibit the secretion of IL-10, an immunosuppressive cytokine, of maturated DCs upon IMQ. To enhance the DC targeting ability, the nanovaccine surface was non-covalently conjugated with the anti-CD205 antibody. The IMQ and IL-10 siRNA co-loaded, CD205 receptor-targeted artificial tumor membrane NVs (IMQ/siR@ATM-NVs) efficiently migrate to the tumor-draining lymph node and target DCs. Furthermore, immunization with IMQ/siR@ATM-NVs reduces the production of IL-10 and increases T_h1-driven antitumor immunity resulted in a great tumor inhibition efficacy. Our results suggest a potential strategy to promote the vaccination's antitumor efficacy by blocking the intrinsic negative regulators in DCs.

A scoping review on the potentiality of PD-L1-inhibiting microRNAs in treating colorectal cancer: Toward single-cell sequencing-guided biocompatible-based delivery

Tumoral programmed cell death ligand 1 (PD-L1) has been implicated in the immune evasion and development of colorectal cancer. Although monoclonal immune checkpoint inhibitors can exclusively improve the prognosis of patients with microsatellite instability-high (MSI-H) and tumor mutational burden-high (TMB-H) colorectal cancer, specific tumor-suppressive microRNAs (miRs) can regulate multiple oncogenic pathways and inhibit the de novo expression of oncoproteins, like PD-L1, both in microsatellite stable (MSS) and MSI-H colorectal cancer cells. This scoping review aimed to discuss the currently available evidence regarding the therapeutic potentiality of PD-L1-inhibiting miRs for colorectal cancer. For this purpose, the Web of Science, Scopus, and PubMed databases were systematically searched to obtain peer-reviewed studies published before 17 March 2021. We have found that miR-191-5p, miR-382-3p, miR-148a-3p, miR-93-5p, miR-200a-3p, miR-200c-3p, miR-138-5p, miR-140-3p, and miR-15b-5p can inhibit tumoral PD-L1 in colorectal cancer cells. Besides inhibiting PD-L1, miR-140-3p, miR-382-3p, miR-148a-3p, miR-93-5p, miR-200a-3p, miR-200c-3p, miR-138-5p, and miR-15b-5p can substantially reduce tumor migration, inhibit tumor development, stimulate anti-tumoral immune responses, decrease tumor viability, and enhance the chemosensitivity of colorectal cancer cells regardless of the microsatellite state. Concerning the specific, effective, and safe delivery of these miRs, the single-cell sequencing-guided biocompatible-based delivery of these miRs can increase the specificity of miR delivery, decrease the toxicity of traditional nanoparticles, transform the immunosuppressive tumor microenvironment into the proinflammatory one, suppress tumor development, decrease tumor migration, and enhance the chemosensitivity of tumoral cells regardless of the microsatellite state.

Innovations in Biomaterial Design toward Successful RNA Interference Therapy for Cancer Treatment

Gene regulation using RNA interference (RNAi) therapy has been developed as one of the frontiers in cancer treatment. The ability to tailor the expression of genes by delivering synthetic oligonucleotides to tumor cells has transformed the way scientists think about treating cancer. However, its clinical application has been limited due to the need to deliver synthetic RNAi oligonucleotides efficiently and effectively to target cells. Advances in nanotechnology and biomaterials have begun to address the limitations to RNAi therapeutic delivery, increasing the likelihood of RNAi therapeutics for cancer treatment in clinical settings. Herein, innovations in the design of nanocarriers for the delivery of oligonucleotides for successful RNAi therapy are discussed.

Combination chemotherapeutic and immune-therapeutic anticancer approach via anti-PD-L1 antibody conjugated albumin nanoparticles

Anticancer regimens have been substantially enriched through monoclonal antibodies targeting immune checkpoints, programmed cell death-1/programmed cell death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte antigen-4. Inconsistent clinical efficacy after solo immunotherapy may be compensated by nanotechnology-driven combination therapy. We loaded human serum albumin (HSA) nanoparticles with paclitaxel (PTX) via nanoparticle albumin-bound technology and pooled them with anti-PD-L1 monoclonal antibody through a pH-sensitive linker for targeting and immune response activation. Our tests demonstrated satisfactory preparation of paclitaxel-loaded, PD-L1-targeted albumin nanoparticles (PD-L1/PTX@HSA). They had small particle size (~200 nm) and polydispersity index (~0.12) and successfully incorporated each constituent. Relative to normal physiological pH, the formulation exhibited higher drug-release profiles favoring cancer cell-targeted release at low pH. Modifying nanoparticles with programmed cell death-ligand 1 increased cancer cell internalization in vitro and tumor accumulation in vivo in comparison with non-PD-L1-modified nanoparticles. PD-L1/PTX@HSA constructed by nanoparticle albumin-bound technology displayed successful tumor inhibition efficacy both in vitro and in vivo. There was successful effector T-cell infiltration, immunosuppressive programmed cell death-ligand 1, and regulatory T-cell suppression because of cytotoxic T-lymphocyte antigen-4 synergy. Moreover, PD-L1/PTX@HSA had low organ toxicity. Hence, the anti-tumor immune responses of PD-L1/PTX@HSA combined with chemotherapy and cytotoxic T-lymphocyte antigen-4 is a potential anti-tumor strategy for improving quantitative and qualitative clinical efficacy.

miR-506-loaded gelatin nanospheres target PENK and inactivate the ERK/Fos signaling pathway to suppress triple-negative breast cancer aggressiveness

Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer. Some microRNAs (miRNAs) were abnormally expressed in TNBC, and they are closely related to the occurrence and progression of TNBC. Here, we found that miR-506 was significantly downregulated in TNBC and relatively lower miR-506 expression predicted a poorer prognosis. Moreover, we found that miR-506 could inhibit MDA-MB-231 cell viability, colony formation, migration, and invasion, and suppress the ERK/Fos oncogenic signaling pathway through upregulating its direct target protein proenkephalin (PENK). Therefore, miR-506 was proposed as a nucleic acid drug for TNBC therapy. However, miRNA is unstable in vivo, which limiting its application as a therapeutic drug via conventional oral or injected therapies. Here, a gelatin nanosphere (GN) delivery system was applied for the first time to load exogenous miRNA. Exogenous miR-506 mimic was loaded on GNs and injected into the in situ TNBC animal model, and the miR-506 could achieve sustained and controlled release. The results confirmed that overexpression of miR-506 and PENK in vivo through loading on GNs inhibited in situ triple-negative breast tumor growth and metastasis significantly in the xenograft model. Moreover, we indicated that the ERK/Fos signaling pathway was intensively inactivated after overexpression of miR-506 and PENK both in vitro and in vivo, which was further validated by the ERK1/2-specific inhibitor SCH772984. In conclusion, this study demonstrates that miR-506-loaded GNs have great potential in anti-TNBC aggressiveness therapy.

Charge-switchable nanoparticles enhance Cancer immunotherapy based on mitochondrial dynamic regulation and immunogenic cell death induction

Cancer immunotherapy has emerged as a promising option for various malignant tumors therapy. Unfortunately, the existence of an immunosuppressive tumor microenvironment (ITM) and the absence of an effective delivery strategy limit its further application. To reverse the ITM and exploit a favorable delivery system for cancer immunotherapy, twin-like charge-switchable nanoparticles (shMFN1-NPs + DOX-NPs, termed as MIX-NPs) were developed to selectively target tumor-associated macrophages (TAMs) and cancer cells, respectively. The shMFN1-NPs (150 nm) and DOX-NPs (160 nm) both had uniform spherical-shaped structures and showed favorable tumor tissue accumulation. Based on the pH-responsive core-shell separation, the nanoparticles obtained an excellent balance between the circulation time and cellular uptake. Mitochondrial dynamics are involved in macrophage polarization by regulating a novel signaling network, involving the modulation from fusion (M2-TAMs) to mitochondrial fission (M1-TAMs). M2-TAMs targeting nanoparticles shMFN1-NPs were fabricated to deliver shMFN1 for repolarization of TAMs from the M2 to M1 phenotype by inhibiting mitochondrial fusion. Moreover, DOX-NPs effectively triggered the immunogenic cell death (ICD) of cancer cells, and the succeeding maturation of dendritic cells (DCs) promoted the infiltration and activation of CD8⁺ T cells. MIX-NPs displayed the strongest antitumor efficacy (TIR = 83%) in the subcutaneous 4T1 tumor model. MIX-NPs suppressed the myeloid-derived suppressor cells (MDSCs) and regulatory T lymphocytes (Tregs) to further remodel the ITM. Taken together, our developed drug delivery strategy reversed the ITM and activated the antitumor immune response, providing a profound prospective treatment strategy in cancer immunotherapy.

Damage-Associated Molecular Patterns Modulation by microRNA: Relevance on Immunogenic Cell Death and Cancer Treatment Outcome

Simple Summary

Inside the cell, damage-associated molecular pattern molecules (DAMPs) play several physiological functions, but when they are released or translocated to the extracellular space, they gain additional immunogenic roles. Thus, DAMPs are considered key hallmarks of immunogenic cell death (ICD) in cancer, a functionally unique regulated form of stress-mediated cell death that activates the immune system response against tumor cells. Several epigenetic modulators of DAMPs have been reported. In this review, we aimed to provide an overview of the effects of microRNAs (miRNAs) on the expression of DAMPs and the putative link between miRNA, DAMPs, and cell death, focused on ICD. Overall, we propose that miRNAs, by targeting DAMPs, play critical roles in the regulation of both cell death and immune-associated mechanisms in cancer, while evidence of their potential involvement in ICD is limited. Finally, we discuss emerging data regarding the impact of miRNAs’ modulation on cancer treatment outcome.

Abstract

Immunogenic cell death (ICD) in cancer is a functionally unique regulated form of stress-mediated cell death that activates both the innate and adaptive immune response against tumor cells. ICD makes dying cancer cells immunogenic by improving both antigenicity and adjuvanticity. The latter relies on the spatiotemporally coordinated release or exposure of danger signals (DAMPs) that drive robust antigen-presenting cell activation. The expression of DAMPs is often constitutive in tumor cells, but it is the initiating stressor, called ICD-inducer, which finally triggers the intracellular response that determines the kinetics and intensity of their release. However, the contribution of cell-autonomous features, such as the epigenetic background, to the development of ICD has not been addressed in sufficient depth. In this context, it has been revealed that several microRNAs (miRNAs), besides acting as tumor promoters or suppressors, can control the ICD-associated exposure of some DAMPs and their basal expression in cancer. Here, we provide a general overview of the dysregulation of cancer-associated miRNAs whose targets are DAMPs, through which new molecular mediators that underlie the immunogenicity of ICD were identified. The current status of miRNA-targeted therapeutics combined with ICD inducers is discussed. A solid comprehension of these processes will provide a framework to evaluate miRNA targets for cancer immunotherapy.

Hybrid micelles codelivering shikonin and IDO-1 siRNA enhance immunotherapy by remodeling immunosuppressive tumor microenvironment

Cancer immunotherapy is becoming an important option for malignant tumors treatment. Unfortunately, lacking intratumoral infiltration of cytotoxic T lymphocytes (CTLs) and immunosuppressive tumor microenvironment (ITM) remian primary barriers that immensely hamper its further clinical application. For boosting immune response and rebuilding the ITM, valid hybrid micelles (SK/siIDO1-HMs) delivering shikonin (SK) and IDO-1 knockdown siRNA (siIDO1) were conducted. SK/siIDO1-HMs had sufficient circulation time, favorable intratumoral accumulation and rapidly release in the cytoplasm. Importantly, SK was demonstrated to significantly elicit intratumoral accumulation of CTLs through inducing immunogenic cell death (ICD) of tumor cells. Moreover, siIDO1 downregulated the IDO-1-caused immunosuppression and restrained regulatory T lymphocytes (Tregs). In summary, SK/siIDO1-HMs displayed a remarkable potential for tumor therapy via triggering the ICD and moderating the IDO-1-triggered immunosuppression.

Natural Melanin-Based Nanoparticles With Combined Chemo/Photothermal/Photodynamic Effect Induce Immunogenic Cell Death (ICD) on Tumor

Melanin, as a natural product, has been used as an extraordinary ingredient for nanomedicine due to its great biocompatibility and light responsive property. In this study, polydopamine (PDA), an analog of melanin, was extracted from dopamine and encapsulated with doxorubicin (DOX). The as-prepared nanoparticles (NPs) with good stability, great biosafety and high near infrared (NIR) responsive property ameliorated the cell uptake of DOX in OS-RC-2/ADR cells, exhibited synergistic chemo/photothermal (PTT)/photodynamic (PDT) effects, induced the release of damage associated molecular patterns (DAMPs), and finally, led to immunogenic cell death (ICD). In general, it was suggested that PDA-DOX NPs with NIR irradiation could serve as a promising agent for tumor therapy.

Pre- and Post-Transcriptional Regulation of cFLIP for Effective Cancer Therapy Using pH-Ultrasensitive Nanoparticles

Cellular FLIP (cFLIP) is a crucial player of apoptosis-regulated pathways that is frequently overexpressed in solid cancers. To inhibit c-FLIP, pre- and post-transcriptionally, a multifunctional nanoparticle (NP) was created to deliver cFLIP-specific small interfering RNA (siRNA) into cancer cells. Specifically, Vorinostat (Vor)-loaded mesoporous silica nanoparticles (MSN) were conjugated with polyethylenimine-biotin (PB), followed by electrostatically binding with cFLIP siRNA (Vor/siR@MSN-PB). To stabilize and prolong the circulation time of nanoparticles, a bialdehyde-modified poly(ethylene glycol) (PEG) was cross-linked onto the polyethylenimine (PEI) backbone via the formation of the imine linkage (Schiff base) (Vor/siR@MSN-PB-PEG). The Schiff base is highly stable at physiological pH 7.4 but labile under slightly acidic pH conditions. In the acidic tumor microenvironment (TME), the PEG outer layer could be rapidly cleaved, resulting in the switching of the nanoparticle surface charge to positive, which specifically enhances internalization of the NPs to the biotin-positive tumor cells. Our results demonstrated the successful preparation of Vor/siR@MSN-PB-PEG NPs, in which the siRNA was effectively protected in serum and regulated the expression of cFlip, post-transcriptionally. The presence of the PEG layer resulted in high tumor accumulation and high efficacy in tumor inhibition, which was a result of the efficient cFLIP suppression. Furthermore, in the low-dose regimen of Vorinostat-the pre-transcriptional cFLIP suppressor, treatment with Vor/siR@MSN-PB-PEG NPs was found to be safe with the treated mice, indicating a promising combination regimen for cancer therapy.

A gene-coated microneedle patch based on industrialized ultrasonic spraying technology with a polycation vector to improve antitumor efficacy

A coated microneedle patch is a reliable way to load gene on a surface as a transdermal gene delivery platform. But there are many limitations to the traditional methods to fabricate a coated microneedle patch, such as the fact that they are time consuming or the difficulty in controlling the loading content. In this research, ultrasonic spraying technology, as an industrialized production method, was first used to fabricate a gene-coated microneedle patch. First, the p53 expression plasmid (p53 DNA) was ultrasonically sprayed on a polycaprolactone (PCL) microneedle patch (D@MNP). To promote the transfection efficiency, polycation polyethylenimine (PEI), as a vector, was then ultrasonically sprayed on D@MNP (P@D@MNP). From the experimental results, although two layers were sprayed step by step, no obvious stratification could be observed. The vector PEI interweaved with genes and inhibited the gene release profile, but it changed the released naked genes to positively charged complexes, which would promote gene transfection efficiency. In subsequent in vivo experiments, the anti-tumor efficacy of the "P@D@MNP treated group" could reach 84.7%, although it had the lowest gene release profile. In contrast, the anti-tumor efficacy of the "intravenous injection group" and "D@MNP treated group" was only 24.3% and 59.3%, respectively. Overall, P@D@MNP was a safe and efficient device to treat the subdermal tumor. Ultrasonic spraying technology provided an industrialized method to fabricate the coated microneedle patch as a transdermal gene/drug delivery platform.

CCR2-targeted micelles for anti-cancer peptide delivery and immune stimulation

Signaling between the CC chemokine receptor 2 (CCR2) with its ligand, monocyte chemoattractant protein-1 (MCP-1) promotes cancer progression by directly stimulating tumor cell proliferation and downregulating the expression of apoptotic proteins. Additionally, the MCP-1/CCR2 signaling axis drives the migration of circulating monocytes into the tumor microenvironment, where they mature into tumor-associated macrophages (TAMs) that promote disease progression through induction of angiogenesis, tissue remodeling, and suppression of the cytotoxic T lymphocyte (CTL) response. In order to simultaneously disrupt MCP-1/CCR2 signaling and target CCR2-expressing cancer cells for drug delivery, KLAK-MCP-1 micelles consisting of a CCR2-targeting peptide sequence (MCP-1 peptide) and the apoptotic KLAKLAK peptide were synthesized. In vitro, KLAK-MCP-1 micelles were observed to bind and induce cytotoxicity to cancer cells through interaction with CCR2. In vivo, KLAK-MCP-1 micelles inhibited tumor growth (34 ± 11%) in a subcutaneous B16F10 murine melanoma model despite minimal tumor accumulation upon intravenous injection. Tumors treated with KLAK-MCP1 demonstrated reduced intratumor CCR2 expression and altered infiltration of TAMs and CTLs as evidenced by immunohistochemical and flow cytometric analysis. These studies highlight the potential application of CCR2-targeted nanotherapeutic micelles in cancer treatment.

Anti-CTLA-4 antibody-functionalized dendritic cell-derived exosomes targeting tumor-draining lymph nodes for effective induction of antitumor T-cell responses

The therapeutic efficacy of current cancer vaccines is far from optimal, mainly because of insufficient induction of antigen-specific T cells and because tumor cells can hijack immunosuppressive mechanisms to evade the immune responses. Generating specific, robust, and long-term immune responses against cancer cells and the attenuating of immunosuppressive factors are critical for effective cancer vaccination. Recently, the engineering of exosomes specifically bind to T cells, and then stimulating tumor-specific T-cell immune responses has emerged as a potential alternative strategy for cancer vaccination. In this study, we generated a bifunctional exosome combining the strategy of vaccination and checkpoint blockade. Exosomes prepared from Ovalbumin (OVA)-pulsed, activated dendritic cells were modified with anti-CTLA-4 antibody (EXO-OVA-mAb) to block this inhibitory molecule and to enhance the specificity of the exosomes toward T cells. Our study provides a unique strategy for functionalizing exosome membrane with anti-CTLA-4 antibody via lipid-anchoring method to synergize efficacy of cancer vaccination and immune checkpoint blockade against the tumor. STATEMENT OF SIGNIFICANCE: We designed T-cell-targeting exosomes (EXO-OVA-mAb) decorated with costimulatory molecules, MHCs, antigenic OVA peptide, and anti-CTLA-4 antibody, combining the strategies of vaccines and checkpoint blockade. The exosomes showed enhanced binding to T cells in tumor-draining lymph nodes, effectively induced T-cell activation, and improved the tumor homing of effector T cells, ultimately significantly restraining tumor growth. Thus, EXO-OVA-mAb greatly facilitates T-cell targeting, induces a strong tumor-specific T-cell response, and increased the ratio of effector T cells/regulatory T cells within tumors, resulting in appreciable tumor growth inhibition.

Manipulating immune system using nanoparticles for an effective cancer treatment: Combination of targeted therapy and checkpoint blockage miRNA

Accumulating clinical data shows that less than half of patients are beneficial from PD-1/PD-L1 blockage therapy owing to the limited infiltration of effector immune cells into the tumor and abundant of the immunosuppressive factors in the tumor microenvironment. In this study, PD-L1 inhibition therapy and BRAF-targeted therapy, which showed clinical benefit, were combined in a CXCR4-targeted nanoparticle co-delivering dabrafenib (Dab), a BRAF inhibitor, and miR-200c which can down-regulate PD-L1 expression. The cationic PCL-PEI core containing Dab- and miR-200c- were coated with poly-L-glutamic acid conjugated with LY2510924, a CXCR-4 antagonist peptide, (PGA-pep) to obtain miR@PCL-PEI/Dab@PGA-pep nanoformulation. The stimulus pH- and redox- reactive of PGA-pep was ascribed to exhibit an enhanced release of drug in the tumor microenvironment as well as improve the stability of miR-200c during the blood circulation. In addition, the presence of LY2510924 peptide would enhance the binding affinity of miR@PCL-PEI/Dab@PGA-pep NPs to cancer cells, leading to improved cellular uptake, cytotoxicity, and in vivo accumulation into tumor area. The in vivo results indicated that both, the immunogenic cell death (ICD) and the inhibition of PD-L1 expression, induced by treatment with CXCR-4 targeted nanoparticles, enables to improve the DC maturation in lymph node and CD8⁺ T cell activation in the spleen. More importantly, effector T cells were increasingly infiltrated into the tumor, whereas the immunosuppressive factors like PD-L1 expression and regulatory T cells were significantly reduced. They, all together, promote the immune responses against the tumor, indicating the therapeutic efficiency of the current strategy in cancer treatment.

A pH-responsive Pickering Nanoemulsion for specified spatial delivery of Immune Checkpoint Inhibitor and Chemotherapy agent to Tumors

Rationale: Immune checkpoint (ICP) blockade therapy combined with chemotherapy is a promising treatment strategy for tumors. Chemotherapeutic agents usually function inside the tumor cells, while ICP inhibitors are efficacious out of the tumor cells. It is desirable to effectively co-deliver an ICP inhibitor and a chemotherapy agent to different sites of a tumor. We have designed an effective drug delivery system to accomplish both objectives. Methods: We designed a Pickering nanoemulsion (PNE) using multi-sensitive nanogels with pH-responsive, hydrophilicity-hydrophobicity switch, and redox-responding properties as an oil/water interfacial stabilizer. The D/HY@PNE was employed for specified spatial delivery of the chemotherapy agent doxorubicin (DOX) and ICP inhibitor HY19991 (HY). We systematically investigated the pH-responsive disassembly of PNE, the release of DOX and HY from D/HY@PNE in the tumor microenvironment, enhanced tumor penetration of DOX, immunogenic cell death (ICD), antitumor efficacy, and the immune response induced by D/HY@PNE in vitro and in vivo. Results: D/HY@PNE disassembled to release the ICP inhibitor HY and DOX-loaded nanogels due to the hydrophilicity-hydrophobicity reversal of nanogels in the acidic tumor microenvironment. Quantitative analysis indicates that D/HY@PNE presents enhanced tumor penetration behavior and effectively induces ICD. The strong immune response induced by D/HY@PNE was due to the efficient synergetic combination of chemotherapy and immunotherapy and resulted in enhanced antitumor efficacy in 4T1 tumor-bearing mice. Conclusion: This novel strategy highlights the promising potential of a universal platform to co-deliver different therapeutic or diagnostic reagents with spatial regulation to improve the anti-tumor effect.

Current developments in nanotechnology for improved cancer treatment, focusing on tumor hypoxia

Hypoxia is a common feature of the tumor microenvironment, which is characterized by tissue oxygen deficiency due to an aggressive proliferation of cancer cells. Hypoxia activates hypoxia-inducible factor-dependent signaling, which in turn regulates metabolic reprogramming, immune suppression, resistance to apoptosis, angiogenesis, metastasis, and invasion to secondary sites. In this review, we provide an overview of the use of nanotechnology to harmonize intra-tumoral oxygen or suppress hypoxia-related signaling for an improved efficacy of cancer treatment. The biological background was followed by conducting a literature review on the (1) nanoparticles responsible for enhancing oxygen levels within the tumor, (2) nanoparticles sensitizing hypoxia, (3) nanoparticles suppressing hypoxia-inducing factor, (4) nanoparticles that relieve tumor hypoxia for enhancement of chemotherapy, photodynamic therapy, and immunotherapy, either individually or in combination. Lastly, the heterogeneity of cancer and limitations of nanotechnology are discussed to facilitate translational therapeutic treatment.

Tumor Targeted Nanocarriers for Immunotherapy

The paramount discovery of passive accumulation of nanoparticles in tumoral tissues triggered the development of a wide number of different nanoparticles capable of transporting therapeutic agents to tumoral tissues in a controlled and selective way. These nanocarriers have been endowed with important capacities such as stimuli-responsive properties, targeting abilities, or the capacity to be monitored by imaging techniques. However, after decades of intense research efforts, only a few nanomedicines have reached the market. The reasons for this disappointing outcome are varied, from the high tumor-type dependence of enhanced permeation and retention (EPR) effect to the poor penetration capacity of nanocarriers within the cancerous tissue, among others. The rapid nanoparticle clearance by immune cells, considered another important barrier, which compromises the efficacy of nanomedicines, would become an important ally in the fight against cancer. In the last years, the fine-tuned ability of immune cells to recognize and engulf nanoparticles have been exploited to deliver immunoregulating agents to specific immune cell populations selectively. In this work, the recent advances carried out in the development of nanocarriers capable of operating with immune and tumoral cells in order to orchestrate an efficient antitumoral response will be presented. The combination of nanoparticles and immunotherapy would deliver powerful weapons to the clinicians that offer safer and more efficient antitumoral treatments for the patients.