Rational Design of a Robust Antibody-like Small-Molecule Inhibitor Nanoplatform for Enhanced Photoimmunotherapy

Anti-lung cancer synergy of low-dose doxorubicin and PD-L1 blocker co-delivered via mild photothermia-responsive black phosphorus

We have previously identified a latent interaction mechanism between non-small cell lung cancer cells (NSCLCC) and their associated macrophages (TAM) mediated by mutual paracrine activation of the HMGB1/RAGE/NF-κB signaling. Activation of this mechanism results in TAM stimulation and PD-L1 upregulation in the NSCLCC. In the present work, we found that free DOX at a low concentration that does not cause DNA damage could activate the HMGB1/RAGE/NF-κB/PD-L1 pathway byinducing oxidative stress. It was thus proposed that a combination of low-dose DOX and a PD-L1 blocker delivered in the NSCLC tumor would achieve synergistic TAM stimulation and thereby synergetic anti-tumor potency. To prove this idea, DOX and BMS-202 (a PD-L1 blocker) were loaded to black phosphorus (BP) nanoparticles after dosage titration to yield the BMS-202/DOX@BP composites that rapidly disintegrated and released drug cargo upon mild photothermal heating at 40 °C. In vitro experiments then demonstrated that low-dose DOX and BMS-202 delivered via BMS-202/DOX@BP under mild photothermia displayed enhanced tumor cell toxicity with a potent synergism only in the presence of TAM. This enhanced synergism was due to an anti-tumor M1-like TAM phenotype that was synergistically induced by low dose DOX plus BMS-202 only in the presence of the tumor cells, indicating the damaged tumor cells to be the cardinal contributor to the M1-like TAM stimulation. In vivo, BMS-202/DOX@BP under mild photothermia exhibited targeted delivery to NSCLC graft tumors in mice and synergistic anti-tumor efficacy of delivered DOX and BMS-202. In conclusion, low-dose DOX in combination with a PD-L1 blocker is an effective strategy to turn TAM against their host tumor cells exploiting the HMGB1/RAGE/NF-κB/PD-L1 pathway. The synergetic actions involved highlight the value of TAM and the significance of modulating tumor cell-TAM cross-talk in tumor therapy. Photothermia-responsive BP provides an efficient platform to translate this strategy into targeted, efficacious tumor therapy.

Recent Advances in Reprogramming Strategy of Tumor Microenvironment for Rejuvenating Photosensitizers-Mediated Photodynamic Therapy

Photodynamic therapy (PDT) has recently been considered a potential tumor therapy due to its time-space specificity and non-invasive advantages. PDT can not only directly kill tumor cells by using cytotoxic reactive oxygen species but also induce an anti-tumor immune response by causing immunogenic cell death of tumor cells. Although it exhibits a promising prospect in treating tumors, there are still many problems to be solved in its practical application. Tumor hypoxia and immunosuppressive microenvironment seriously affect the efficacy of PDT. The hypoxic and immunosuppressive microenvironment is mainly due to the abnormal vascular matrix around the tumor, its abnormal metabolism, and the influence of various immunosuppressive-related cells and their expressed molecules. Thus, reprogramming the tumor microenvironment (TME) is of great significance for rejuvenating PDT. This article reviews the latest strategies for rejuvenating PDT, from regulating tumor vascular matrix, interfering with tumor cell metabolism, and reprogramming immunosuppressive related cells and factors to reverse tumor hypoxia and immunosuppressive microenvironment. These strategies provide valuable information for a better understanding of the significance of TME in PDT and also guide the development of the next-generation multifunctional nanoplatforms for PDT.

A lipid/PLGA nanocomplex to reshape tumor immune microenvironment for colon cancer therapy

Immune checkpoint blockade therapy provides a new strategy for tumor treatment; however, the insufficient infiltration of cytotoxic T cells and immunosuppression in tumor microenvironment lead to unsatisfied effects. Herein, we reported a lipid/PLGA nanocomplex (RDCM) co-loaded with the photosensitizer Ce6 and the indoleamine 2,3-dioxygenase (IDO) inhibitor 1MT to improve immunotherapy of colon cancer. Arginine-glycine-aspartic acid (RGD) as the targeting moiety was conjugated on 1,2-distearoyl-snglycero-3-phosphoethanolamine lipid via polyethylene glycol (PEG), and programmed cell death-ligand 1 (PD-L1) peptide inhibitor DPPA (sequence: CPLGVRGK-GGG-d(NYSKPTDRQYHF)) was immobilized on the terminal group of PEG via matrix metalloproteinase 2 sensitive peptide linker. The Ce6 and 1MT were encapsulated in PLGA nanoparticles. The drug loaded nanoparticles were composited with RGD and DPPA modified lipid and lecithin to form lipid/PLGA nanocomplexes. When the nanocomplexes were delivered to tumor, DPPA was released by the cleavage of a matrix metalloproteinase 2-sensitive peptide linker for PD-L1 binding. RGD facilitated the cellular internalization of nanocomplexes via avβ3 integrin. Strong immunogenic cell death was induced by 1O2 generated from Ce6 irradiation under 660 nm laser. 1MT inhibited the activity of IDO and reduced the inhibition of cytotoxic T cells caused by kynurenine accumulation in the tumor microenvironment. The RDCM facilitated the maturation of dendritic cells, inhibited the activity of IDO, and markedly recruited the proportion of tumor-infiltrating cytotoxic T cells in CT26 tumor-bearing mice, triggering a robust immunological memory effect, thus effectively preventing tumor metastasis. The results indicated that the RDCM with dual IDO and PD-L1 inhibition effects is a promising platform for targeted photoimmunotherapy of colon cancer.

Light-Enhanced Hypoxia-Responsive Gene Editing for Hypoxia-Resistant Photodynamic and Immunotherapy

Hypoxia is a key hallmark of solid tumors and can cause resistance to various treatments such as photodynamics and immunotherapy. Microenvironment-responsive gene editing provides a powerful tool to overcome hypoxia resistance and remodel hypoxic microenvironments for enhanced tumor therapy. Here, a light-enhanced hypoxia-responsive multifunctional nanocarrier is developed to perform spatiotemporal specific dual gene editing for enhanced photodynamic and immunotherapy in breast cancer. As a gated molecule of nanocarrier, the degradation of azobenzene moieties under hypoxic conditions triggers controllable release of Cas9 ribonucleoprotein in hypoxic site of the tumor. Hyaluronic acid is conjugated with chloramine e6 to coat mesoporous silica nanoparticles for targeted delivery in tumors and generation of high levels of reactive oxygen species, which can result in increased hypoxia levels for effective cleavage of azobenzene bonds to improve gene editing efficiency and reduce toxic side effects with light irradiation. Moreover, dual targeting HIF-1α and PD-L1 in the anoxic microenvironments can overcome hypoxia resistance and remodel immune microenvironments, which reduces tumor plasticity and resistance to photodynamic and immunotherapy. In summary, a light-enhanced hypoxia responsive nanocomposite is developed for controllable gene editing which holds great promise for synergistic hypoxia-resistant photodynamic and immunotherapy.

Drug delivery nanoparticles for preventing implant bacterial infections based on the bacteria and immunity mechanisms

Implant dysfunction and failure during medical treatment can be attributed to bacterial infection with Staphylococcus aureus and Enterococcus faecalis, which are the prevalent strains responsible for implant infections. Currently, antibiotics are primarily used either locally or systemically to prevent and treat bacterial infections in implants. However, the effectiveness of this approach is unsatisfactory. Therefore, the development of new antimicrobial medications is crucial to address the clinical challenges associated with implant infections. In this study, a nanoparticle (ICG+RSG) composed of indocyanine green (ICG) and rosiglitazone (RSG), and delivered using 1,2-dipalmitoyl-snglycero-3-phosphocholine (DPPC) was prepared. ICG+RSG has photothermal and photodynamic properties to eliminate bacteria at the infection site by releasing reactive oxygen species and increasing the temperature. Additionally, it regulates phagocytosis and macrophage polarization to modulate the immune response in the body. ICG+RSG kills bacteria and reduces tissue inflammation, showing potential for preventing implant infections.

Dynamic immuno-nanomedicines in oncology

Anti-cancer therapeutics have achieved significant advances due to the emergence of immunotherapies that rely on the identification of tumors by the patients' immune system and subsequent tumor eradication. However, tumor cells often escape immunity, leading to poor responsiveness and easy tolerance to immunotherapy. Thus, the potentiated anti-tumor immunity in patients resistant to immunotherapies remains a challenge. Reactive oxygen species-based dynamic nanotherapeutics are not new in the anti-tumor field, but their potential as immunomodulators has only been demonstrated in recent years. Dynamic nanotherapeutics can distinctly enhance anti-tumor immune response, which derives the concept of the dynamic immuno-nanomedicines (DINMs). This review describes the pivotal role of DINMs in cancer immunotherapy and provides an overview of the clinical realities of DINMs. The preclinical development of emerging DINMs is also outlined. Moreover, strategies to synergize the antitumor immunity by DINMs in combination with other immunologic agents are summarized. Last but not least, the challenges and opportunities related to DINMs-mediated immune responses are also discussed.

Advances in Polymeric Micelles: Responsive and Targeting Approaches for Cancer Immunotherapy in the Tumor Microenvironment

In recent years, to treat a diverse array of cancer forms, considerable advancements have been achieved in the field of cancer immunotherapies. However, these therapies encounter multiple challenges in clinical practice, such as high immune-mediated toxicity, insufficient accumulation in cancer tissues, and undesired off-target reactions. To tackle these limitations and enhance bioavailability, polymer micelles present potential solutions by enabling precise drug delivery to the target site, thus amplifying the effectiveness of immunotherapy. This review article offers an extensive survey of recent progress in cancer immunotherapy strategies utilizing micelles. These strategies include responsive and remodeling approaches to the tumor microenvironment (TME), modulation of immunosuppressive cells within the TME, enhancement of immune checkpoint inhibitors, utilization of cancer vaccine platforms, modulation of antigen presentation, manipulation of engineered T cells, and targeting other components of the TME. Subsequently, we delve into the present state and constraints linked to the clinical utilization of polymeric micelles. Collectively, polymer micelles demonstrate excellent prospects in tumor immunotherapy by effectively addressing the challenges associated with conventional cancer immunotherapies.

Polysaccharide-Based Stimulus-Responsive Nanomedicines for Combination Cancer Immunotherapy

Cancer immunotherapy is a promising antitumor approach, whereas nontherapeutic side effects, tumor microenvironment (TME) intricacy, and low tumor immunogenicity limit its therapeutic efficacy. In recent years, combination immunotherapy with other therapies has been proven to considerably increase antitumor efficacy. However, achieving codelivery of the drugs to the tumor site remains a major challenge. Stimulus-responsive nanodelivery systems show controlled drug delivery and precise drug release. Polysaccharides, a family of potential biomaterials, are widely used in the development of stimulus-responsive nanomedicines due to their unique physicochemical properties, biocompatibility, and modifiability. Here, the antitumor activity of polysaccharides and several combined immunotherapy strategies (e.g., immunotherapy combined with chemotherapy, photodynamic therapy, or photothermal therapy) are summarized. More importantly, the recent progress of polysaccharide-based stimulus-responsive nanomedicines for combination cancer immunotherapy is discussed, with the focus on construction of nanomedicine, targeted delivery, drug release, and enhanced antitumor effects. Finally, the limitations and application prospects of this new field are discussed.

Nanotechnology-based photo-immunotherapy: a new hope for inhibition of melanoma growth and metastasis

Melanoma is the most aggressive form of skin cancer and there is a need for the development of effective anti-melanoma therapies as it shows high metastatic ability and low response rate. In addition, it has been identified that traditional phototherapy could trigger immunogenic cell death (ICD) to activate antitumor immune response, which could not only effectively arrest primary tumor growth, but also exhibit superior effects in terms of anti-metastasis, anti-recurrence for metastatic melanoma treatment However, the limited tumor accumulation of photosensitizers/photothermal agents and immunosuppressive tumor microenvironment severely weaken the immune effects. The application of nanotechnology facilitates a higher accumulation of photosensitizers/photothermal agents at the tumor site, which can thus improve the antitumor effects of photo-immunotherapy (PIT). In this review, we summarize the basic principles of nanotechnology-based PIT and highlight novel nanotechnologies that are expected to enhance the antitumor immune response for improved therapeutic efficacy.

Proof of concept nanotechnological approach to in vitro targeting of malignant melanoma for enhanced immune checkpoint inhibition

Immunotherapies, including immune checkpoint inhibitors, have limitations in their effective treatment of malignancies. The immunosuppressive environment associated with the tumor microenvironment may prevent the achievement of optimal outcomes for immune checkpoint inhibitors alone, and nanotechnology-based platforms for delivery of immunotherapeutic agents are increasingly being investigated for their potential to improve the efficacy of immune checkpoint blockade therapy. In this manuscript, nanoparticles were designed with appropriate size and surface characteristics to enhance their retention of payload so that they can transmit their loaded drugs to the tumor. We aimed to enhance immune cell stimulation by a small molecule inhibitor of PD-1/PD-L1 (BMS202) using nanodiamonds (ND). Melanoma cells with different disease stages were exposed to bare NDs, BMS202-NDs or BMS202 alone for 6 h. Following this, melanoma cells were co-cultured with freshly isolated human peripheral blood mononuclear cells (hPBMCs). The effects of this treatment combination on melanoma cells were examined on several biological parameters including cell viability, cell membrane damage, lysosomal mass/pH changes and expression of γHA2X, and caspase 3. Exposing melanoma cells to BMS202-NDs led to a stronger than normal interaction between the hPBMCs and the melanoma cells, with significant anti-proliferative effects. We therefore conclude that melanoma therapy has the potential to be enhanced by non-classical T-cell Immune responses via immune checkpoint inhibitors delivered by nanodiamonds-based nanoparticles.

Chlorin e6: A Promising Photosensitizer in Photo-Based Cancer Nanomedicine

Conventional cancer treatment modalities are often associated with major therapeutic limitations and severe side effects. Photodynamic therapy is a localized noninvasive mode of treatment that has given a different direction to cancer research due to its effectivity against a wide range of cancers and minimal side effects. A photosensitizer is the key component of photodynamic therapy (PDT) that generates cytotoxic reactive oxygen species to eradicate cancer cells. As the therapeutic effectivity of PDT greatly depends upon the photosensitizer, great efforts have been made to search for an ideal photosensitizer. Chlorin e6 is a FDA approved second generation photosensitizer that meets the desired clinical properties for PDT. It is known for its high reactive oxygen species (ROS) generation ability and anticancer potency against many types of cancer. Hydrophobicity is a major drawback of Ce6 that leads to its poor biodistribution and rapid clearance from the circulatory system. To overcome this drawback, researchers have designed and fabricated several types of nanosystems, which can enhance Ce6 solubility and thereby enhance its bioavailability. These nanosystems also improve tumor accumulation of Ce6 by selectively targeting the cancer cells through passive and active targeting. In addition, Ce6 has been employed in many combination therapies like chemo-photodynamic therapy, photoimmunotherapy, and combined photodynamic-photothermal therapy. A combination therapy is more curative than a single therapy due to the synergistic effects of individual therapies. Ce6-based nanosystems for combination therapies have shown excellent results in various studies and provide a promising platform for cancer treatment.

Targeted Nanophotoimmunotherapy Potentiates Cancer Treatment by Enhancing Tumor Immunogenicity and Improving the Immunosuppressive Tumor Microenvironment

Cancer immunotherapy, such as immune checkpoint blockade, chimeric antigen receptor, and cytokine therapy, has emerged as a robust therapeutic strategy activating the host immune system to inhibit primary and metastatic lesions. However, low tumor immunogenicity (LTI) and immunosuppressive tumor microenvironment (ITM) severely compromise the killing effect of immune cells on tumor cells, which fail to evoke a strong and effective immune response. As an exogenous stimulation therapy, phototherapy can induce immunogenic cell death (ICD), enhancing the therapeutic effect of tumor immunotherapy. However, the lack of tumor targeting and the occurrence of immune escape significantly reduce its efficacy in vivo, thus limiting its clinical application. Nanophotoimmunotherapy (nano-PIT) is a precision-targeted tumor treatment that co-loaded phototherapeutic agents and various immunotherapeutic agents by specifically targeted nanoparticles (NPs) to improve the effectiveness of phototherapy, reduce its phototoxicity, enhance tumor immunogenicity, and reverse the ITM. This review will focus on the theme of nano-PIT, introduce the current research status of nano-PIT on converting "cold" tumors to "hot" tumors to improve immune efficacy according to the classification of immunotherapy targets, and discuss the challenges, opportunities, and prospects.

Dual cancer stem cell manipulation to enhance phototherapy against tumor progression and metastasis

Targeting breast cancer stem cells (BCSCs) therapy is a prospective strategy to eliminate tumors owing to the BCSCs-governed drug resistance, tumor progression and metastasis. BCSCs are intrinsically in a disequilibrium state with favorable ability of self-renewal rather than differentiation, resulting in inability of complete tumor eradication. Besides the original BCSCs, epithelial-mesenchymal transition (EMT) process can further facilitate BCSCs regeneration, accompanied by tumor progression and metastasis. Herein, we, for the first time, engineered a photodynamic nanoplatform to manipulate BCSCs against tumor progression and metastasis by not only remolding the disequilibrium state but also blocking the EMT process. The HP@PP was constructed by haloperidol (HP)-incorporated polyethyleneimine-polyhistidine (PP) micelles, which was further integrated with low molecular weight heparin (LMWH)-chlorin e6 (Ce6) conjugate (LC) to form HP@PP/LC nanoparticles (NPs). For HP@PP/LC NPs, the protonation of PP in tumor tissues precisely targeted HP to BCSCs for remolding the disequilibrium state via promoting BCSCs differentiation into tumor cells. Simultaneously, LC conjugate targeted to tumors for exerting EMT blocking ability with LMWH, as well as exerting photodynamic clearance of tumor cells with Ce6 component. Therefore, our nanoplatform provides an emerging strategy for manipulating BCSCs against tumor progression and metastasis, demonstrating a promising photodynamic platform against tumors.

A Nanoplatform to Amplify Apoptosis-to-Pyroptosis Immunotherapy via Immunomodulation of Myeloid-Derived Suppressor Cells

Pyroptosis is a programmed cell death to enhance immunogenicity of tumor cells, but pyroptosis-based immunotherapy is limited due to the immune escape involving myeloid-derived suppressor cells (MDSCs). Therefore, designing a nanoplatform to not only trigger apoptosis-pyroptosis transformation but also combat the MDSC-based immune escape is of great significance. As a proof-of-concept study, here, we designed a metal organic framework (MOF)-based nanoplatform to tailor the pyroptosis immunotherapy through disrupting the MDSC-mediated immunosuppression. By pH-responsive zeolitic imidazolate framework-8 (ZIF-8) modified with hyaluronic acid (HA), the chemotherapeutic drug mitoxantrone (MIT) and DNA demethylating agent hydralazine (HYD) were successfully co-encapsulated into ZIF-8 for achieving (M+H)@ZIF/HA nanoparticles. This nanoplatform demonstrated a powerful apoptosis-to-pyroptosis transformation with a potent disruption of MDSC-mediated T cell paralysis via reducing immunosuppressive methylglyoxal by HYD. Overall, our two-pronged nanoplatform (M+H)@ZIF/HA can switch the cold tumor into an arsenal of antigens that stimulate robust immunological responses, while suppressing immune escape, collectively triggering vigorous cytotoxic T cell responses with remarkable tumor elimination and building a long-term immune memory response against metastasis.

Adoptive CD8+T-cell grafted with liposomal immunotherapy drugs to counteract the immune suppressive tumor microenvironment and enhance therapy for melanoma

The immunosuppressive tumor microenvironment has become a formidable obstacle to the treatment of tumors using adoptive T cell therapy, in particular solid tumors. For the purposes of addressing this issue, effector OT-1 CD8⁺T cells conjugated with liposomal immune regulators (CD8-T-LP-CpG/CD8-T-LP-BMS-202) were developed. An anionic liposome formulation was employed to avoid T cell aggregation and prevent unfavorable side-effects. The inclusion of EGCG in the LP-CpG formulation facilitated the formation of compact complexes with poly lysine (PLL) and is thus expected to increase the stability. CD8-T-LP-CpG administered with a median dose of CpG (20 μg per mouse) markedly reduced the frequency of tumor infiltrating polymorphonuclear leukocyte myeloid-derived suppressor cells (PMN-MDSCs) (20-folds), M2-like macrophages (8-folds), regulatory T-cells (Treg) (2.7-folds), and consequently increased the frequency of cytotoxic CD8⁺T cells in tumor-infiltrating lymphocytes (TILs) (2-folds) and splenic effector memory CD8⁺T cells (3-folds) relative to the phosphate buffered saline (PBS) control group. Furthermore, the absolute number of tumor infiltrating lymphocyte subtypes altered followed a consistent trend. The difference remained significant compared to the OT-1 CD8⁺T cells and the drug-loaded liposome combination group. According to in vivo imaging of CD8-T-LP-DiD, we assumed that the improvement in regulation of the tumor microenvironment of LP-CpG/LP-BMS-202 was attributed to the enhanced drug transportation to the tumor site aided by tumor-specific OT-1 CD8⁺T cells. In addition, CD8-T-LP-BMS-202 administered with a low dose of BMS-202 (1.5 mg per kg body weight) exerted a dramatically improved therapeutic effect by reducing the tumor infiltrating PMN-MDSCs and M2-like macrophages and the corresponding promoted cytotoxic CD8⁺T cell recruitment in the TILs and effector memory CD8⁺T cells mediated anti-tumor immunity. In summary, immune therapy drugs backpacked onto adoptive T cell therapy provides a feasible strategy to improve the therapeutic effect and could result in future clinical translation.

Combination of Chidamide-Mediated Epigenetic Modulation with Immunotherapy: Boosting Tumor Immunogenicity and Response to PD-1/PD-L1 Blockade

Improving tumor immunogenicity is critical for increasing the responsiveness of triple-negative breast cancer (TNBC) to anti-PD-(L)1 treatment. Here, we verified that chidamide (CHI), an epigenetic modulator, could elicit immunogenic cell death within TNBC to enhance cancer immunogenicity and elicit an antitumor immune response. Additionally, CHI increased the expression level of PD-L1, MHC I, and MHC II on cancer cells, which contributed to T-cell recognition and PD-1/PD-L1 blockade therapy response. The synergistic antitumor efficacy of CHI and PD-L1 blockade therapy was further explored through liposomes co-delivering CHI and BMS-202 (a small-molecule PD-L1 inhibitor). The liposomes possessed good biocompatibility, security, and controllable drug release and endowed therapeutics drugs with favorable tumor accumulation. Furthermore, the drug-loaded liposomes could obviously boost the antitumor immunity of TNBC through CHI-enhanced tumor immunogenicity and BMS-202-mediated PD-L1 blockade, thereby effectively inhibiting the growth of primary and metastatic tumors with an inhibitory rate of metastasis of up to 96%. In summary, this work provided a referable and optional approach for clinical antitumor therapy based on the combination of an epigenetic modulator and PD-1/PD-L1 blockade therapy.

Nanoengineering of a newly designed chlorin e6 derivative for amplified photodynamic therapy via regulating lactate metabolism

Chlorin e6 (Ce6) is a widely utilized photosensitizer in photodynamic therapy (PDT) against tumor growth, but its hydrophobic feature and the hypoxia in the tumor microenvironment greatly compromise its therapeutic efficacy. To address the issues, here we designed a new Ce6 derivative (TCe6) by coupling Ce6 with amphiphilic d-α-tocopherol polyethylene glycol 1000 succinate (TPGS), endowing Ce6 with an excellent amphiphilic feature. In particular, the overall reactive oxygen species (ROS) generation by TCe6 was significantly enhanced because TPGS could interact with mitochondrial complex II to induce extra ROS production, amplifying the total ROS production under PDT. Inspired by the unique property of α-cyano-4-hydroxycinnamate (CHC) in regulating lactate metabolism to spare more intracellular oxygen for PDT, TCe6 was further co-assembled with CHC to construct TCe6/CHC nanoparticles (NPs) for addressing the insufficient oxygen issue in PDT. The as-prepared TCe6/CHC NPs not only increased the efficiency of cell internalization but also improved the solubility and stability of Ce6 and CHC. Thanks to the extra ROS production by the TPGS unit, the amphiphilic feature of TCe6 and the CHC-mediated hypoxia microenvironment, the TCe6/CHC NPs demonstrated excellent PDT against tumor growth. This work provided a versatile strategy to solve the current bottleneck in photosensitizer-based PDT, holding great promise for the design of advanced photodynamic nanoplatforms.

Transforming growth factor-β blockade modulates tumor mechanical microenvironments for enhanced antitumor efficacy of photodynamic therapy

Photodynamic therapy (PDT) is frequently used in cancer treatment in clinical settings. However, its applications in stroma-rich solid tumors, e.g., triple negative breast cancer, are limited by abnormal mechanical microenvironments. Solid stress accumulated in stroma-rich solid tumors compresses tumor blood vessels, hampers the delivery of photosensitizers (PSs) in tumor tissues, and poses a major challenge for potent PDT. Here, we report a novel combination strategy to augment PDT based cancer therapy by combining hydroxyethyl starch-chlorin e6 conjugate self-assembled nanoparticles (HES-Ce6 NPs) with the transforming growth factor-β (TGFβ) inhibitor LY2157299 (LY). HES-Ce6 conjugates, as synthesized by one step esterification reaction, could self-assemble into uniform HES-Ce6 NPs, which exhibited enhanced photostability and generated more reactive oxygen species (ROS) under 660 nm laser irradiation than free Ce6. Prior to PDT, intragastric administration of LY decreased collagen deposition, alleviated solid stress, and decompressed tumor blood vessels. As a result, the reconstructed tumor mechanical microenvironment promoted accumulation and penetration of HES-Ce6 NPs into tumor tissues, contributing to augmented antitumor efficacy of HES-Ce6 NP mediated PDT. Modulating tumor mechanical microenvironments using TGFβ blockade to enhance the delivery of PSs in tumors with excessive extracellular matrix represents an efficient strategy for treating stroma-rich solid tumors.

Recent progress in nanomedicine for enhanced cancer chemotherapy

As one of the most important cancer treatment strategies, conventional chemotherapy has substantial side effects and leads easily to cancer treatment failure. Therefore, exploring and developing more efficient methods to enhance cancer chemotherapy is an urgently important problem that must be solved. With the development of nanotechnology, nanomedicine has showed a good application prospect in improving cancer chemotherapy. In this review, we aim to present a discussion on the significant research progress in nanomedicine for enhanced cancer chemotherapy. First, increased enrichment of drugs in tumor tissues relying on different targeting ligands and promoting tissue penetration are summarized. Second, specific subcellular organelle-targeted chemotherapy is discussed. Next, different combinational strategies to reverse multidrug resistance (MDR) and improve the effective intracellular concentration of therapeutics are discussed. Furthermore, the advantages of combination therapy for cancer treatment are emphasized. Finally, we discuss the major problems facing therapeutic nanomedicine for cancer chemotherapy, and propose possible future directions in this field.

An injectable hydrogel using an immunomodulating gelator for amplified tumor immunotherapy by blocking the arginase pathway

Arginase 1 (ARG1) inactivates T cells by degrading L-arginine, severely reducing the immunotherapeutic efficacy. Effectively blocking the ARG1 pathway remains a challenge. L-norvaline is a very cheap and negligible side effects inhibitor of ARG1. However, its blockage efficacy for ARG1 is impeded by its high half-maximal-inhibitory concentration (IC50) requiring high drug loading content of L-norvaline in carriers. Moreover its high water solubility results in bursting and uncontrolled release. Herein we reported an injectable hydrogel strategy via an L-norvaline-based immunomodulating gelator that could effectively block ARG1 pathway. The designed gelator was a diblock copolymer containing L-norvaline-based polypeptide block, which could construct a thermally responsive injectable hydrogel by its self-gelation in tumor microenvironments. The hydrogel not only ensures high drug loading of L-norvaline, but also ensures controlled release of L-norvaline through responsive peptide bond cleavage, thereby solving the problems encountered by L-norvaline. The injectable hydrogel in combination with doxorubicin hydrochloride demonstrated a potent immunotherapy for removal of primary tumors, suppression of abscopal tumors and inhibition of pulmonary metastasis by combining the blockage of ARG1 pathway and the immunogenic cell death. Our immunomodulating gelator strategy provides a robust injectable hydrogel platform to efficiently reverse ARG1 immunosuppressive environments for amplified immunotherapy. STATEMENT OF SIGNIFICANCE: We designed an injectable hydrogel via an L-norvaline-based immunomodulating gelator. The designed gelator, a diblock copolymer containing an L-norvaline-based polypeptide block, enabled a thermally responsive injectable hydrogel by its self-gelation in tumor microenvironments. The injectable hydrogel not only guarantees high drug loading of L-norvaline, but also ensures controlled release of L-norvaline through responsive peptide bonds cleavage, thereby solving the problems encountered by L-norvaline. By further introducing doxorubicin hydrochloride in the hydrogel for inducing immunogenic cell death, the hydrogel showed remarkable immunotherapeutic efficacy towards ablation of primary tumors, suppression of abscopal tumors and inhibition of pulmonary metastasis. Our immunomodulating gelator strategy provides a new concept to efficiently reverse Arginase 1 immunosuppressive environments for amplified immunotherapy.

Sequential receptor-mediated mixed-charge nanomedicine to target pancreatic cancer, inducing immunogenic cell death and reshaping the tumor microenvironment

Pancreatic cancer (PC) is an aggressive form of cancer with dense stroma and immune-suppressive microenvironment, which are the major barriers for treatment. To address such barriers, this study aimed to develop a sequential receptor-mediated mixed-charge targeted delivery system for PC based on 2-(3-((S)-5-amino-1-carboxypentyl)-ureido) pentanedioate (ACUPA^-) and triphenylphosphonium (TPP⁺) modified nanomicelles containing ingenol-3-mebutate (I3A), which was named ACUPA^-/TPP⁺-I3A or ACUPA/TPP-I3A. ACUPA/TPP-I3A induced immunogenic cell death (ICD), which significantly increased the number of tumor-infiltrating T lymphocytes, activated adaptive immunity, and achieved superior survival time. I3A, a novel anticancer drug, could induce PC cell necrosis to release damage-associated molecular patterns, thereby activating adaptive immunity. With certain ratios of negatively (ACUPA^-) and positively (TPP⁺) charged ligands, ACUPA/TPP-I3A acquired a negative charge in plasma (pH 7.4, to inhibit aggregation and uptake in the circulation) and was neutral in the acidic tumor microenvironment (pH 5.0-6.0, to overcome electrostatic hindrances and facilitate transcytosis). Furthermore, neovascular endothelium-specific ACUPA enabled rapid transcytosis of ACUPA/TPP-I3A across tumor vessel walls, entering into endosome/lysosomes (pH 4.5-5.0, its charge became positive and exhibited lysosome escape). Then, ACUPA/TPP-I3A selectively targeted mitochondria, which correlated with TPP-mediated effect. Finally, I3A was released to induce ICD that activated adaptive immunity and achieved superior survival time. Therefore, reshaping of the tumor microenvironment and potentiating antitumor immunity using ACUPA^-/TPP⁺-I3A constituted a novel strategy to prolong the survival time.

In Vitro and In Vivo Demonstration of Ultraefficient and Broad-Spectrum Antibacterial Agents for Photodynamic Antibacterial Chemotherapy

Increasing threats from both pathogenic infections and antibiotic resistance highlight the pressing demand for nonantibiotic agents and alternative therapies. Herein, we report several new phenothiazinium-based derivatives, which could be readily synthesized via fragment-based assembly, which exhibited remarkable bactericidal activities both in vitro and in vivo. Importantly, in contrast to numerous clinically and preclinically used antibacterial photosensitizers, these compounds were able to eliminate various types of microorganisms, including Gram-(+) Staphylococcus aureus (S. aureus), Gram-(-) Escherichia coli, multidrug-resistant S. aureus, and their associated biofilms, at low drug and light dosages (e.g., 0.21 ng/mL in vitro and 1.63 ng/cm² in vivo to eradicate S. aureus at 30 J/cm²). This study thus unveils the potential of these novel phenothiaziniums as potent antimicrobial agents for highly efficient photodynamic antibacterial chemotherapy.

Engineering of a dual-modal phototherapeutic nanoplatform for single NIR laser-triggered tumor therapy

Theranostic nanoplatforms integrating simultaneously photodynamic therapy (PDT) and photothermal therapy (PTT) exhibit intrinsic advantages in tumor therapy due to distinct mechanisms of action. However, it is challenging to achieve PDT and PTT under single near-infrared (NIR) laser irradiation with a nanoplatform utilizing conventional organic photodynamic agent and inorganic photothermal agent owing to the difference in inherent excitation wavelengths. Particularly, the single NIR light (660 nm)-triggered PTT and PDT nanoplatform, constructed from chlorin e6 (Ce6) and copper sulfide (CuS) nanoparticles (NPs), has never been reported. Herein, we, for the first time, designed and established a dual-modal phototherapeutic nanoplatform that achieved both PTT and PDT under single NIR laser (660 nm) irradiation for Ce6 and CuS NPs with the strategy of core-shell structured CuS@Carbon integrated with Ce6. Introducing of carbon shell not only endows small CuS NPs with excellent tumor accumulation, but also significantly strengthens the photothermal performance of CuS NPs, realizing efficient photothermal performance under 660 nm laser irradiation. Moreover, Ce6 in carbon shell endowed the nanoplatform with photodynamic effect under 660 nm laser irradiation. The as-prepared Ce6/CuS@Carbon nanoplatform thus achieved dual-modal phototherapy under single NIR laser irradiation, significantly inhibiting tumor growth with minimal adverse effects and superior biosafety.

Judging Enzyme-Responsive Micelles by Their Covers: Direct Comparison of Dendritic Amphiphiles with Different Hydrophilic Blocks

Enzymatically degradable polymeric micelles have great potential as drug delivery systems, allowing the selective release of their active cargo at the site of disease. Furthermore, enzymatic degradation of the polymeric nanocarriers facilitates clearance of the delivery system after it has completed its task. While extensive research is dedicated toward the design and study of the enzymatically degradable hydrophobic block, there is limited understanding on how the hydrophilic shell of the micelle can affect the properties of such enzymatically degradable micelles. In this work, we report a systematic head-to-head comparison of well-defined polymeric micelles with different polymeric shells and two types of enzymatically degradable hydrophobic cores. To carry out this direct comparison, we developed a highly modular approach for preparing clickable, spectrally active enzyme-responsive dendrons with adjustable degree of hydrophobicity. The dendrons were linked with three different widely used hydrophilic polymers—poly(ethylene glycol), poly(2-ethyl-2-oxazoline), and poly(acrylic acid) using the CuAAC click reaction. The high modularity and molecular precision of the synthetic methodology enabled us to easily prepare well-defined amphiphiles that differ either in their hydrophilic block composition or in their hydrophobic dendron. The micelles of the different amphiphiles were thoroughly characterized and their sizes, critical micelle concentrations, drug loading, stability, and cell internalization were compared. We found that the micelle diameter was almost solely dependent on the hydrophobicity of the dendritic hydrophobic block, whereas the enzymatic degradation rate was strongly dependent on the composition of both blocks. Drug encapsulation capacity was very sensitive to the type of the hydrophilic block, indicating that, in addition to the hydrophobic core, the micellar shell also has a significant role in drug encapsulation. Incubation of the spectrally active micelles in the presence of cells showed that the hydrophilic shell significantly affects the micellar stability, localization, cell internalization kinetics, and the cargo release mechanism. Overall, the high molecular precision and the ability of these amphiphiles to report their disassembly, even in complex biological media, allowed us to directly compare the different types of micelles, providing striking insights into how the composition of the micelle shells and cores can affect their properties and potential to serve as nanocarriers.