Overcoming Chemoimmunotherapy-Induced Immunosuppression by Assemblable and Depot Forming Immune Modulating Nanosuspension

Amino acid metabolic reprogramming in the tumor microenvironment and its implication for cancer therapy

Amino acids are essential building blocks for proteins, crucial energy sources for cell survival, and key signaling molecules supporting the resistant growth of tumor cells. In tumor cells, amino acid metabolic reprogramming is characterized by the enhanced uptake of amino acids as well as their aberrant synthesis, breakdown, and transport, leading to immune evasion and malignant progression of tumor cells. This article reviews the altered amino acid metabolism in tumor cells and its impact on tumor microenvironment, and also provides an overview of the current clinical applications of amino acid metabolism. Innovative drugs targeting amino acid metabolism hold great promise for precision and personalized cancer therapy.

Immunological nanomaterials to combat cancer metastasis

Metastasis causes greater than 90% of cancer-associated deaths, presenting huge challenges for detection and efficient treatment of cancer due to its high heterogeneity and widespread dissemination to various organs. Therefore, it is imperative to combat cancer metastasis, which is the key to achieving complete cancer eradication. Immunotherapy as a systemic approach has shown promising potential to combat metastasis. However, current clinical immunotherapies are not effective for all patients or all types of cancer metastases owing to insufficient immune responses. In recent years, immunological nanomaterials with intrinsic immunogenicity or immunomodulatory agents with efficient loading have been shown to enhance immune responses to eliminate metastasis. In this review, we would like to summarize various types of immunological nanomaterials against metastasis. Moreover, this review will summarize a series of immunological nanomaterial-mediated immunotherapy strategies to combat metastasis, including immunogenic cell death, regulation of chemokines and cytokines, improving the immunosuppressive tumour microenvironment, activation of the STING pathway, enhancing cytotoxic natural killer cell activity, enhancing antigen presentation of dendritic cells, and enhancing chimeric antigen receptor T cell therapy. Furthermore, the synergistic anti-metastasis strategies based on the combinational use of immunotherapy and other therapeutic modalities will also be introduced. In addition, the nanomaterial-mediated imaging techniques (e.g., optical imaging, magnetic resonance imaging, computed tomography, photoacoustic imaging, surface-enhanced Raman scattering, radionuclide imaging, etc.) for detecting metastasis and monitoring anti-metastasis efficacy are also summarized. Finally, the current challenges and future prospects of immunological nanomaterial-based anti-metastasis are also elucidated with the intention to accelerate its clinical translation.

Design of a targeted dual drug delivery system for boosting the efficacy of photoimmunotherapy against melanoma proliferation and metastasis

INTRODUCTION

The combination of a photosensitizer and indoleamine-2,3 dioxygenase (IDO) inhibitor provides a promising photoimmunotherapy (PIT) strategy for melanoma treatment. A dual drug delivery system offers a potential approach for optimizing the inhibitory effects of PIT on melanoma proliferation and metastasis.

OBJECTIVE

To develop a dual drug delivery system based on PIT and to study its efficacy in inhibiting melanoma proliferation and metastasis.

METHODS

We constructed a multifunctional nano-porphyrin material (P18-APBA-HA) using the photosensitizer-purpurin 18 (P18), hyaluronic acid (HA), and 4-(aminomethyl) phenylboronic acid (APBA). The resulting P18-APBA-HA was inserted into a phospholipid membrane and the IDO inhibitor epacadostat (EPA) was loaded into the internal phase to prepare a dual drug delivery system (Lip\EPA\P18-APBA-HA). Moreover, we also investigated its physicochemical properties, targeting, anti-tumor immunity, and anti-tumor proliferation and metastasis effects.

RESULTS

The designed system utilized the pH sensitivity of borate ester to realize an enhanced-targeting strategy to facilitate the drug distribution in tumor lesions and efficient receptor-mediated cellular endocytosis. The intracellular release of EPA from Lip\EPA\P18-APBA-HA was triggered by thermal radiation, thereby inhibiting IDO activity in the tumor microenvironment, and promoting activation of the immune response. Intravenous administration of Lip\EPA\P18-APBA-HA effectively induced anti-tumor immunity by promoting dendritic cell maturation, cytotoxic T cell activation, and regulatory T cell suppression, and regulating cytokine secretion, to inhibit the proliferation of melanoma and lung metastasis.

CONCLUSION

The proposed nano-drug delivery system holds promise as offers a promising strategy to enhance the inhibitory effects of the combination of EPA and P18 on melanoma proliferation and metastasis.

Hypoxia-activated cascade nanovaccine for synergistic chemoembolization-immune therapy of hepatocellular carcinoma

In this work, a promising treatment strategy for triggering robust antitumor immune responses in transarterial chemoembolization of hepatocellular carcinoma (HCC) is presented. The zeolitic imidazolate framework nanoparticles loaded with hypoxia-activated prodrug tirapazamine and immune adjuvant resiquimod facilitated in situ generation of nanovaccine via a facile approach. The nanovaccine can strengthen the ability of killing the liver cancer cells under hypoxic environment, while was capable of improving immunogenic tumor microenvironment and triggering strong antitumor immune responses by increasing the primary and distant intratumoral infiltration of immune cells such as cytotoxic T cells. Moreover, a porous microcarrier, approved by FDA as pharmaceutical excipient, was designed to achieve safe and effective delivery of the nanovaccine via transarterial therapy in rabbit orthotopic VX2 liver cancer model. The microcarrier exhibited the characteristics of excellent drug loading and occlusion of peripheral artery. The collaborative delivery of the microcarrier and nanovaccine demonstrated an exciting inhibitory effect on solid tumors and tumor metastases, which provided a great potential as novel combination therapy for HCC interventional therapy.

Nanosuspension-Based Drug Delivery Systems for Topical Applications

Nanosuspensions have garnered recent attention as a promising strategy for mitigating the bioavailability challenges of hydrophobic drugs, particularly those characterized by poor solubility in both aqueous and organic environments. Addressing solubility issues associated with poorly water-soluble drugs has largely resolved the need to enhance drug absorption and bioavailability. As mucosal formulations and topical administration progress in the future, nanosuspension drug delivery, straightforward formulation techniques, and versatile applications will continue to be subjects of interest. Nanosuspensions have undergone extensive scrutiny in preparation for topical applications, encompassing ocular, pulmonary, and dermal usage. Among the numerous methods aimed at improving cutaneous application, nanocrystals represent a relatively recent yet profoundly intriguing approach. Despite the increasing availability of various nanosuspension products, primarily designed for oral administration, only a limited number of studies have explored skin permeability and drug accumulation in the context of nanosuspensions. Nevertheless, the scant published research unequivocally underscores the potential of this approach for enhancing cutaneous bioavailability, particularly for active ingredients with low to medium solubility. Nanocrystals exhibit increased skin adhesiveness in addition to heightened saturation solubility and dissolution rate, thereby augmenting cutaneous distribution. The article provides a comprehensive overview of nanosuspensions for topical application. The methodology employed is robust, with a well-defined experimental design; however, the limited sample size raises concerns about the generalizability of the findings. While the results demonstrate promising outcomes in terms of enhanced drug delivery, the discussion falls short of addressing certain limitations. Additionally, the references largely focus on recent studies, but a more diverse inclusion of historical perspectives could offer a more holistic view of the subject.

A Dual-Targeting Liposome Enhances Triple-Negative Breast Cancer Chemoimmunotherapy through Inducing Immunogenic Cell Death and Inhibiting STAT3 Activation

Immunotherapy gains increasing focus in treating triple-negative breast cancer (TNBC), while its efficacy is greatly restricted owing to low tumor immunogenicity and immunosuppressive tumor microenvironment (ITM). Herein, a LyP-1 and chondroitin sulfate (CS) dual-modified liposome co-loaded with paclitaxel (PTX) and cryptotanshinone (CTS), namely CS/LyP-1-PC Lip, is engineered for TNBC chemoimmunotherapy via induction of immunogenic cell death (ICD) and inhibition of signal transducer and activator of transcript-3 (STAT3) activation. CS/LyP-1-PC Lip enhances cellular uptake through p32 and CD44 dual receptor-mediated endocytosis. Within the tumor, the CS layer is continuously detached by hyaluronidase to release drugs. Subsequently, CTS sensitizes the cytotoxicity of PTX to 4T1 tumor cells. PTX induces ICD of tumor cells and facilitates infiltration of cytotoxic T lymphocyte to provoke immune response. Meanwhile, the concomitant delivery of CTS inhibits STAT3 activation to decrease infiltration of regulatory T cell, M2-type tumor-associated macrophage, and myeloid-derived suppressor cell, thus reversing ITM. Markedly, the dual-targeting liposome shows superior anti-tumor efficacy in subcutaneous TNBC mice and significant lung metastasis suppression in tumor metastasis model. Overall, this work offers a feasible combination regimen and a promising nanoplatform for the development of TNBC chemoimmunotherapy.

Nanoengineered drug delivery in cancer immunotherapy for overcoming immunosuppressive tumor microenvironment

Almost like a living being in and of itself, tumors actively interact with and modify their environment to escape immune responses. Owing to the pre-formation of cancer-favorable microenvironment prior to anti-cancer treatment, the numerous attempts that followed propose limited efficacy in oncology. Immunogenicity by activation of immune cells within the tumor microenvironment or recruitment of immune cells from nearby lymph nodes is quickly offset as the immunosuppressive environment, rapidly converting immunogenic cells into immune suppressive cells, overriding the immune system. Tumor cells, as well as regulatory cells, namely M2 macrophages, Treg cells, and MDSCs, derived by the immunosuppressive environment, also cloak from potential anti-tumoral factors by directly or indirectly secreting cytokines, such as IL-10 and TGF-β, related to immune regulation. Enzymes and other metabolic or angiogenetic constituents - VEGF, IDO1, and iNOS - are also employed directed for anti-cancer immune cell malfunctioning. Therefore, the conversion of "cold" immunosuppressive environment into "hot" immune responsive environment is of paramount importance, bestowing the advances in the field of cancer immunotherapy the opportunity to wholly fulfill its intended purpose. This paper reviews the mechanisms by which tumors wield to exercise immune suppression and the nanoengineered delivery strategies being developed to overcome this suppression.

On-demand integrated nano-engager converting cold tumors to hot via increased DNA damage and dual immune checkpoint inhibition

Cancer immunotherapy has become a promising strategy. However, the effectiveness of immunotherapy is restricted in "cold tumors" characterized with insufficient T cells intratumoral infiltration and failed T cells priming. Herein, an on-demand integrated nano-engager (JOT-Lip) was developed to convert cold tumors to hot via "increased DNA damage and dual immune checkpoint inhibition" strategy. JOT-Lip was engineered by co-loading oxaliplatin (Oxa) and JQ1 into liposomes with T-cell immunoglobulin mucin-3 antibodies (Tim-3 mAb) coupled on the liposomal surface by metalloproteinase-2 (MMP-2)-sensitive linker. JQ1 inhibited DNA repair to increase DNA damage and immunogenic cell death (ICD) of Oxa, thus promoting T cells intratumoral infiltration. In addition, JQ1 inhibited PD-1/PD-L1 pathway, achieving dual immune checkpoint inhibition combining with Tim-3 mAb, thus effectively promoting T cells priming. It is demonstrated that JOT-Lip not only increased DNA damage and promoted the release of damage-associated molecular patterns (DAMPs), but also enhanced T cells intratumoral infiltration and promoted T cell priming, which successfully converted cold tumors to hot and showed significant anti-tumor and anti-metastasis effects. Collectively, our study provides a rational design of an effective combination regimen and an ideal co-delivery system to convert cold tumors to hot, which holds great potential in clinical cancer chemoimmunotherapy.

Reactive oxygen species-powered cancer immunotherapy: Current status and challenges

Reactive oxygen species (ROS) are crucial signaling molecules that can arouse immune system. In recent decades, ROS has emerged as a unique therapeutic strategy for malignant tumors as (i) it can not only directly reduce tumor burden but also trigger immune responses by inducing immunogenic cell death (ICD); and (ii) it can be facilely generated and modulated by radiotherapy, photodynamic therapy, sonodynamic therapy and chemodynamic therapy. The anti-tumor immune responses are, however, mostly downplayed by the immunosuppressive signals and dysfunction of effector immune cells within the tumor microenvironment (TME). The past years have seen fierce developments of various strategies to power ROS-based cancer immunotherapy by e.g. combining with immune checkpoints inhibitors, tumor vaccines, and/or immunoadjuvants, which have shown to potently inhibit primary tumors, metastatic tumors, and tumor relapse with limited immune-related adverse events (irAEs). In this review, we introduce the concept of ROS-powered cancer immunotherapy, highlight the innovative strategies to boost ROS-based cancer immunotherapy, and discuss the challenges in terms of clinical translation and future perspectives.

Efficient tumor synergistic chemoimmunotherapy by self-augmented ROS-responsive immunomodulatory polymeric nanodrug

Immunotherapy has emerged as a promising therapeutic strategy for cancer therapy. However, the therapeutic efficacy has been distracted due to poor immunogenicity and immunosuppressive tumor microenvironment. In this study, a self-augmented reactive oxygen species (ROS) responsive nanocarrier with immunogenic inducer paclitaxel (PTX) and indoleamine 2,3-dixoygenase 1 (IDO1) blocker 1-methyl-D, L-tryptophan (1-MT) co-entrapment was developed for tumor rejection. The carrier was composed of poly (ethylene glycol) (PEG) as hydrophilic segments, enzyme cleavable 1-MT ester and ROS-sensitive peroxalate conjugation as hydrophobic blocks. The copolymer could self-assemble into prodrug-based nanoparticles with PTX, realizing a positive feedback loop of ROS-accelerated PTX release and PTX induced ROS generation. Our nanoparticles presented efficient immunogenic cell death (ICD) which provoked antitumor immune responses with high effector T cells infiltration. Meanwhile immunosuppressive tumor microenvironment was simultaneously modulated with reduced regulatory T cells (Tregs) and M2-tumor associated macrophages (M2-TAMs) infiltration mediated by IDO inhibition. The combination of PTX and 1-MT achieved significant primary tumor regression and reduction of lung metastasis in 4T1 tumor bearing mice. Therefore, the above results demonstrated co-delivery of immunogenic inducer and IDO inhibitor using the ROS amplifying nanoplatform with potent potential for tumor chemoimmunotherapy.

Blockage of the IDO1 pathway by charge-switchable nanoparticles amplifies immunogenic cell death for enhanced cancer immunotherapy

Immunosuppressive tumor microenvironment (ITM), poor immunogenicity and low tumor penetration markedly reduce the tumor immunotherapy capability. To address these hurdles, we successfully engineered acidity-triggered nanoparticles (NPs) with size-reduction and charge-switchable to boost tumor immunotherapy based on indoleamine 2,3-dioxygenase 1 siRNA (IDO1 siRNA) and immunogenic cell death (ICD). The NPs significantly augmented tumor penetrating ability and improved cellular uptake via the detachment of 2,3-dimethylmaleic anhydride grafted poly(ethylene glycol)-poly(L-lysine) copolymer (mPEG-PLL-DMA, PLM) from large-sized NPs with a negative charge. Subsequently, the NPs with a positive charge and small size rapidly escaped from the lysosomes and released mitoxantrone (MIT) and IDO1 siRNA. The antitumor immune response of IDO1 siRNA and MIT provided good antitumor capability through enhancing DCs maturation, improving numbers of CTLs and downregulating the level of Tregs in tumor tissues. In summary, the results demonstrated that charge-switchable NPs based on blockage of the IDO1 pathway and ICD activation induce an efficient antitumor immune response, thus showing high potential for treating primary/distant tumor and reducing metastasis. STATEMENT OF SIGNIFICANCE: Acidity-triggered nanoparticles (NPs) with size-reduction and charge-switchable to boost tumor immunotherapy based on indoleamine 2,3-dioxygenase 1 siRNA (IDO1 siRNA) and immunogenic cell death (ICD) were engineered. NPs augmented tumor penetrating ability and improved cellular uptake via the detachment of mPEG-PLL-DMA (PLM) from large-sized MIT/siR-PLM/PPA NPs with negative charge to expose miniature and positively charged MIT/siR-PPA NPs. The NPs rapidly escaped from the lysosome and sequentially released mitoxantrone (MIT) and IDO1 siRNA. The antitumor immune synergistic effect of inhibiting the IDO1 pathway by IDO1 siRNA and inducting ICD by MIT provided dramatic antitumor capability through enhancing DCs maturation, improving numbers of CTLs and downregulating the level of Tregs in tumor tissues. And the NPs revealed a promising pathway against aggressive and difficult-to-treat cancers.

Targeting the Negative Feedback of Adenosine-A2AR Metabolic Pathway by a Tailored Nanoinhibitor for Photothermal Immunotherapy

The metabolite adenosine plays an important immunosuppressive role in the tumor microenvironment (TME) through its ligation with the metabolic checkpoint adenosine 2A receptor (A2AR). Here, an adenosine-A2AR negative feedback pathway is highlighted during photothermal-induced immunogenic cell death (ICD). Adenosine, hydrolyzed from ATP, is amplified during the photothermal-induced ICD process. It is possible to achieve a robust ICD-based immunotherapy via targeting the adenosine-A2AR metabolic pathway. In this regard, an A2AR inhibitor-loaded polydopamine nanocarrier masked by an acid-sensitive PEG shell is designed to enable tumor-specific delivery and photothermal-induced ICD simultaneously. Upon reaching the acidic TME, the PEG shell selectively detaches and exposes the adhesive polydopamine layer, causing the inhibitors to accumulate at the tumor tissue. The accumulated inhibitors attenuate adenosine's metabolically suppressive effect and strengthen the ICD immune response. It occurs through promoting dendritic cell (DC) activation, increasing CD8+ T lymphocyte infiltration, and reducing the myeloid-derived suppressor cell (MDSC) population. Furthermore, this synergistic therapy significantly regresses the primary tumor, inhibits distal tumor growth, and prevents lung metastasis. The study highlights a strategy to enhance the immunotherapy efficacy of ICD by blocking the metabolic checkpoint A2AR using advanced nanomaterials.