Nanosized drug delivery systems modulate the immunosuppressive microenvironment to improve cancer immunotherapy.

Immunotherapy that activates immune systems for combating cancer has yielded considerable clinical benefits recently. However, the immunosuppressive tumor microenvironment (ITME) is a major hurdle to immunotherapy as it supports tumor to evade immune surveillance. Reversing ITME facilitates the recruitment and activation of antitumor immune cells, thereby promoting immunotherapy. Our group has developed various nanosized drug delivery systems (NDDSs) to modulate ITME with enhanced efficacy and safety. In the review we introduce the ITME-remodeling strategies for improving immunotherapy based on NDDSs including triggering tumor cells to undergo immunogenetic cell death (ICD), applying tumor vaccine, and directly regulating intratumoral immune components (immune cells or cytokines). In order to guide the design of NDDSs for amplified effects of antitumor immunotherapy, the contributions and future directions of this field are also discussed.

In Vivo Environment-Adaptive Nanocomplex with Tumor Cell-Specific Cytotoxicity Enhances T Cells Infiltration and Improves Cancer Therapy.

Drug delivery strategies possessing selectivity for cancer cells are eagerly needed in therapy of metastatic breast cancer. In this study, the chemotherapeutic agent, docetaxel (DTX), is conjugated onto heparan sulfate (HS). Aspirin (ASP), which has the activity of anti-metastasis and enhancing T cells infiltration in tumors, is encapsulated into the HS-DTX micelle. Then the cationic polyethyleneimine (PEI)-polyethylene glycol (PEG) copolymer binds to HS via electrostatic force, forming the ASP-loaded HS-DTX micelle (AHD)/PEI-PEG nanocomplex (PAHD). PAHD displays long circulation behavior in blood due to the PEG shell. Under the tumor microenvironment with weakly acidic pH, PEI-PEG separates from AHD, and the free cationic PEI-PEG facilitates the cellular uptake of AHD by increasing permeability of cell membranes. Then the overexpressed heparanase degrades HS, releasing ASP and DTX. PAHD shows specific toxicity toward tumor cells but not normal cells, with advanced activity of inhibiting tumor growth and lung metastasis in 4T1 tumor-bearing mice. The number of CD8+ T cells in tumor tissues is also increased. Therefore, PAHD can become an efficient drug delivery system for breast cancer treatment.

Author Correction: Co-delivery of docetaxel and silibinin using pH-sensitive micelles improves therapy of metastatic breast cancer.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Co-delivery of docetaxel and silibinin using pH-sensitive micelles improves therapy of metastatic breast cancer.

Breast cancer is the most vicious killer for women, and tumor metastasis is one of the leading causes of breast cancer therapy failure. In this study, a new pH-sensitive polymer (polyethylene glycol-block-poly[(1,4-butanediol)-diacrylate-ß-N,N-diisopropylethylenediamine], BDP) was synthesized. Based on BDP, docetaxel/silibinin co-delivery micelles (DSMs) was constructed. DSM had a well-defined spherical shape under the transmission electron microscope with average hydrodynamic diameter of 85.3±0.4 nm, and were stable in the bloodstream but could dissociate to release the chemotherapeutic agents in the low pH environment of the endo/lysosomes in the tumor cells. Compared with free drugs, DSM displayed greatly enhanced cellular uptake, higher cytotoxicity and a stronger anti-metastasis effect against mouse breast cancer cell line 4T1. In 4T1 tumor-bearing mice treated with DSM (twice a week for 3 weeks), the inhibition rate on tumor growth and metastasis reached 71.9% and 80.1%, respectively. These results reveal that DSM might be a promising drug delivery system for metastatic breast cancer therapy.

Combination of miR159 Mimics and Irinotecan Utilizing Lipid Nanoparticles for Enhanced Treatment of Colorectal Cancer.

Colorectal cancer (CRC) ranks as the third most prevalent global malignancy, marked by significant metastasis and post-surgical recurrence, posing formidable challenges to treatment efficacy. The integration of oligonucleotides with chemotherapeutic drugs emerges as a promising strategy for synergistic CRC therapy. The nanoformulation, lipid nanoparticle (LNP), presents the capability to achieve co-delivery of oligonucleotides and chemotherapeutic drugs for cancer therapy. In this study, we constructed lipid nanoparticles, termed as LNP-I-V by microfluidics to co-deliver oligonucleotides miR159 mimics (VDX05001SI) and irinotecan (IRT), demonstrating effective treatment of CRC both in vitro and in vivo. The LNP-I-V exhibited a particle size of 118.67 ± 1.27 nm, ensuring excellent stability and targeting delivery to tumor tissues, where it was internalized and escaped from the endosome with a pH-sensitive profile. Ultimately, LNP-I-V significantly inhibited CRC growth, extended the survival of tumor-bearing mice, and displayed favorable safety profiles. Thus, LNP-I-V held promise as an innovative platform to combine gene therapy and chemotherapy for improving CRC treatment.

"All-in-one" metal polyphenol network nanocapsules integrated microneedle patches for lipophagy fueled ferroptosis-mediated multimodal therapy.

Ferroptosis-mediated multimodal therapy has emerged as a promising strategy for tumor elimination, with lipid peroxide (LPO) playing a pivotal role. However, the therapeutic efficiency is limited due to insufficient intracellular levels of free fatty acids (FFA), which severely hinder the production of LPO. To address this limitation, we proposed a lipophagy strategy aimed at degrading lipid droplets (LDs) to release FFA, serving as the essential "fuel" for LPO production. In this study, the lipophagy inducer epigallocatechin gallate (EGCG) was self-assembled with reactive oxygen species (ROS)-producer phenethyl isothiocyanate (PEITC) mediated by Fe2+ to form EFP nanocapsules, which were further integrated into microneedle patches to form a "all-in-one" EFP@MNs. The metal-polyphenol network structure of EFP endow it with photothermal therapy capacity. Upon insertion into tumors, the released EFP nanocapsules were demonstrated to induce lipophagy through metabolic disturbance, thereby promoting LPO production and facilitating ferroptosis. When combined with photothermal therapy, this approach significantly remolded the tumor immune microenvironment by driving tumor-associated macrophages toward M1 phenotype and enhancing dendritic cell maturation. Encouragingly, in conjunction with αPD-L1 treatment, the proposed EFP@MNs exhibited remarkable efficacy in tumor ablation. Our study presents a versatile framework for utilizing microneedle patches to power ferroptosis-mediated multimodal therapy.

Breaking Tumor Immunosuppressive Network by Regulating Multiple Nodes with Triadic Drug Delivery Nanoparticles.

Inside the tumor microenvironment, a complicated immunosuppressive network is constituted by tumor cells and suppressive immune cells as its nodes, including myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), and regulatory T cells, which have mutual promotion on each other and superimposed inhibition on natural killer (NK) cells and cytotoxic T cells. Breaking the whole balance of this web is critical to tumor immunotherapy since modulation on a single node may be diluted by other factors in the network. To achieve multifaceted regulation on antitumor immunity against triple-negative breast cancer, in this work, a micelle, termed BEM, co-delivering the MDSC inhibitor, entinostat (ENT), and the immune checkpoint inhibitor, BMS-1, was constructed with pH-sensitive amphiphilic poly(ß-amino ester) derivatives. Then, BEM and the scavenger receptor A (SR-A) ligand dextran sulfate (DXS) formed a negatively charged nanoparticle (BEN). DXS detached from BEN in the weakly acidic tumor microenvironment and blocked SR-A on TAMs, reprogramming TAMs toward the M1 type. The positively charged BEM with facilitated intratumoral penetration and cellular uptake dissociated in the lysosomes, accompanied by the release of ENT and BMS-1 to suppress MDSCs and block the programmed cell death protein (PD)-1/PD-ligand 1 pathway, respectively. As a result, NK cells and CD8+ T cells in tumors were increased, as were their effector cytokines. The activated innate and adaptive antitumor immune responses suppressed the growth and metastasis of tumors and prolonged survival of 4T1 tumor-bearing mice. BEN provides a reliable approach for improving cancer immunotherapy by destroying the immunosuppression web in tumors via multinode regulation.

Co-delivering irinotecan and imiquimod by pH-responsive micelle amplifies anti-tumor immunity against colorectal cancer.

Irinotecan (IRT), a classic clinical chemotherapeutic agent for treating colorectal cancer, has been found to induce immunogenic cell death (ICD) while exerting cytotoxicity in tumor cells. This effect is likely to be amplified in combination with immune modulators. Unfortunately, free drugs without targeting capacity would receive poor outcomes and strong side effects. To address these issues, in this work, an acid-sensitive micelle based on an amphiphilic poly(ß-amino ester) derivative was constructed to co-deliver IRT and the immune adjuvant imiquimod (IMQ), termed PII. PII kept stable under normal physiological conditions. After internalization by tumor cells, PII dissociated in acidic lysosomes and released IRT and IMQ rapidly. In the CT26 tumor mouse model, PII increased the intra-tumoral SN38 (the active metabolite of IRT) and IMQ concentrations by up to 9.39 and 3.44 times compared with the free drug solution. The tumor inhibition rate of PII achieved 87.29%. This might profit from that IRT induced ICD, which promoted dendritic cells (DCs) maturation and intra-tumoral infiltration of CD8+ T cells. In addition, IMQ enhanced the antigen presenting ability of DCs and stimulated tumor associated macrophages to secrete tumor-killing cytokines. PII provided an effective strategy to combat colorectal cancer by synergy of chemotherapy and immunoregulation.

Combining gut microbiota modulation and chemotherapy by capecitabine-loaded prebiotic nanoparticle improves colorectal cancer therapy.

Colorectal cancer (CRC) therapy efficiency can be influenced by the microbiota in the gastrointestinal tract. Compared with traditional intervention, prebiotics delivery into the gut is a more controllable method for gut microbiota modulatory therapy. Capecitabine (Cap), the first-line chemotherapeutic agent for CRC, lacks a carrier that can prolong its half-life. Here, we construct a Cap-loaded nanoparticle using the prebiotic xylan-stearic acid conjugate (SCXN). The oral administration of SCXN delays the drug clearance in the blood and increases the intra-tumoral Cap concentration in the CRC mouse model. SCXN also facilitates the probiotic proliferation and short chain fatty acid production. Compared with free Cap, SCXN enhances the anti-tumor immunity and increases the tumor inhibition rate from 5.29 to 71.78%. SCXN exhibits good biocompatibility and prolongs the median survival time of CRC mice from 14 to 33.5 d. This prebiotics-based nanoparticle provides a promising CRC treatment by combining gut microbiota modulation and chemotherapy.

Nano drug delivery systems improve metastatic breast cancer therapy.

Despite continual progress in the technologies and regimens for cancer therapy, the treatment outcome of fatal metastatic breast cancer is far from satisfactory. Encouragingly, nanotechnology has emerged as a valuable tool to optimize drug delivery process in cancer therapy via preventing the cargos from degradation, improving the tumor-targeting efficiency, enhancing therapeutic agents' retention in specific sites, and controlling drug release. In the last decade, several mechanisms of suppressing tumor metastasis by functional nano drug delivery systems (NDDSs) have been revealed and a guidance for the rational design of anti-metastasis NDDSs is summarized, which consist of three aspects: optimization of physiochemical properties, tumor microenvironment remodeling, and biomimetic strategies. A series of medicinal functional biomaterials and anti-metastatic breast cancer NDDSs constructed by our team are introduced in this review. It is hoped that better anti-metastasis strategies can be inspired and applied in clinic.

Gut Microbiota: Influence on Carcinogenesis and Modulation Strategies by Drug Delivery Systems to Improve Cancer Therapy.

Gut microbiota have close interactions with the host. It can affect cancer progression and the outcomes of cancer therapy, including chemotherapy, immunotherapy, and radiotherapy. Therefore, approaches toward the modulation of gut microbiota will enhance cancer prevention and treatment. Modern drug delivery systems (DDS) are emerging as rational and promising tools for microbiota intervention. These delivery systems have compensated for the obstacles associated with traditional treatments. In this review, the essential roles of gut microbiota in carcinogenesis, cancer progression, and various cancer therapies are first introduced. Next, advances in DDS that are aimed at enhancing the efficacy of cancer therapy by modulating or engineering gut microbiota are highlighted. Finally, the challenges and opportunities associated with the application of DDS targeting gut microbiota for cancer prevention and treatment are briefly discussed.

T lymphocyte membrane-decorated epigenetic nanoinducer of interferons for cancer immunotherapy.

Impaired type I interferons (IFNs) may cause immune deficiency in tumours. Current supplementary IFN therapy partially restores anticancer immunity but simultaneously induces immune evasion by upregulating multiple immune checkpoints. Here we create a T lymphocyte membrane-decorated epigenetic nanoinducer that is engineered with programmed cell death protein 1 (PD1), which we call OPEN, for the delivery of the IFN inducer ORY-1001. OPEN increases IFNs and blocks IFN-induced immune checkpoint upregulation. OPEN also targets tumours that express programmed cell death ligand 1 (PDL1) through PDL1/PD1 recognition and subsequently triggers the internalization of OPEN and immune checkpoint proteins. OPEN, which is loaded with ORY-1001, upregulates intratumoural IFNs and downstream major histocompatibility complex I and PDL1. The replenished PDL1 enables further ligation of OPEN, which in turn blocks PDL1. These sequential processes result in an eight- and 29-fold increase of the intratumoural densities of total and active cytotoxic T lymphocytes, respectively, and a strong inhibition of xenograft tumour growth. This T lymphocyte membrane-decorated epigenetic nanoinducer presents a generalizable platform to boost antitumour immunity.

Engineering immunogenic cell death with nanosized drug delivery systems improving cancer immunotherapy.

Many anti-cancer therapies can induce or enhance the immunogenic cell death (ICD), a process that releases damage-associated molecular patterns (DAMPs) to prime antigen processing and presentation necessary for successful cancer immunotherapy. However, the clinical potential of these therapies, especially the chemotherapy, is limited by serious systemic side effects, because of their non-specific accumulation out of the tumors. Nanosized drug delivery systems (NDDSs) can improve the specificity of anti-cancer therapies, which enhance ICD in the tumor while alleviating toxicities. In this review, we summarize recent progress of ICD-inducing NDDSs with a focus on their enhanced safety and efficacy for cancer immunotherapy.

Calcitriol-Loaded Dual-pH-Sensitive Micelle Counteracts Pro-Metastasis Effect of Paclitaxel in Triple-Negative Breast Cancer Therapy.

The therapy of triple-negative breast cancer (TNBC) relies on chemotherapy basing on cytotoxic agents, including paclitaxel (PTX). Unfortunately, PTX will facilitate the invasion of cancer cells and the formation of metastases. To counteract pro-metastasis of PTX in TNBC therapy, in this work, calcitriol (CTL) is delivered along with PTX by a dual-pH-sensitive micelle. The PTX/CTL-co-loaded dual-pH-sensitive micelle (PCDM) can switch its surface charge from negative to positive at the tumor tissue and release PTX and CTL inside the lysosomes because of the structure change of the polymers composing PCDM under the acidic condition. This property makes PCDM able to escape from mononuclear-phagocyte system clearance and easy to enter tumor cells. PCDM efficiently suppresses the 4T1 primary tumor growth in mice and inhibits lung metastasis, due to downregulation of matrix metalloproteinase-9 and BCL-2 levels, upregulation of E-cadherin level, and counteracting the PTX-induced elevation of C-C motif chemokine ligand 2 (CCL2) and Ly6C+ monocytes levels by CTL. PCDM shows good biocompatibility without promoting the serum calcium level. Therefore, the combination of PTX and CTL based on this pH-sensitive micelle is promising for the TNBC treatment.

Erratum: pH-Sensitive Nano-Complexes Overcome Drug Resistance and Inhibit Metastasis of Breast Cancer by Silencing Akt Expression: Erratum.

[This corrects the article DOI: 10.7150/thno.21516.].

Tumor microenvironment-responsive docetaxel-loaded micelle combats metastatic breast cancer.

Efficient tumor-targeting drug delivery systems are urgently needed for treating metastatic breast cancer. In this work, a docetaxel (DTX)-loaded micelle (pDM) as the tumor-microenvironment-responsive delivery platform is developed. The micelle is composed of a pH-sensitive amphiphilic copolymer, poly((1,4-butanediol)-diacrylate-ß-N,N-diisopropylethylenediamine)-polyethyleneimine (BD-PEI), and a matrix metalloproteinase (MMP)-responsive polymer, poly((1,4-butanediol)-diacrylate-ß-N,N-diisopropylethylenediamine)-peptide-polyethylene glycol (PEG) (BD-peptide-PEG). The PEG block of BD-peptide-PEG will be split by MMPs at the tumor microenvironment, which leads to the change of the surface charge and particle size of the micelle to more positive and smaller one. Owing to this transformation and enhanced permeability and retention (EPR) effect, pDM delivers more DTX into tumor tissues and is internalized more efficiently by tumor cells than the non-MMP-sensitive micelles in the 4T1 tumor-bearing mice model. In addition, DTX is released in acidic endo/lysosomes due to the dissociation of the micelle, triggered by the protonation of the hydrophobic block of BD-PEI. As a result, the DTX-loaded micelle inhibits primary tumor growth and pulmonary metastasis effectively. Thus, this pH/MMP-dual-sensitive drug delivery system, which simultaneously attains three keypoints: prolonged circulation time, directional and efficient uptake into tumor cells, and speedy intracellular drug release, is a promising strategy for metastatic breast cancer therapy.

Cocktail Strategy Based on Spatio-Temporally Controlled Nano Device Improves Therapy of Breast Cancer.

Metastatic breast cancer may be resistant to chemo-immunotherapy due to the existence of cancer stem cells (CSC). Also, the control of particle size and drug release of a drug carrier for multidrug combination is a key issue influencing the therapy effect. Here, a cocktail strategy is reported, in which chemotherapy against both bulk tumor cells and CSC and immune checkpoint blockade therapy are intergraded into one drug delivery system. The chemotherapeutic agent paclitaxel (PTX), the anti-CSC agent thioridazine (THZ), and the PD-1/PD-L1 inhibitor HY19991 (HY) are all incorporated into an enzyme/pH dual-sensitive nanoparticle with a micelle-liposome double-layer structure. The particle size shrinks when the nanoparticle transfers from circulation to tumor tissues, favoring both pharmacokinetics and cellular uptake, meanwhile achieving sequential drug release where needed. This nano device, named PM@THL, increases the intratumoral drug concentrations in mice and exhibits significant anticancer efficacy, with tumor inhibiting rate of 93.45% and lung metastasis suppression rate of 97.64%. It also reduces the proportion of CSC and enhances the T cells infiltration in tumor tissues, and thus prolongs the survival of mice. The cocktail therapy based on the spatio-temporally controlled nano device will be a promising strategy for treating breast cancer.

Traceable Bioinspired Nanoparticle for the Treatment of Metastatic Breast Cancer via NIR-Trigged Intracellular Delivery of Methylene Blue and Cisplatin.

Cytotoxic T lymphocyte (CTL) eliminates abnormal cells through target recognition-triggered intracellular toxin delivery. Chimeric antigen receptor T-cell improves cancer cell recognition of CTL, but its effectiveness and safety in solid tumor treatment are still hampered by poor tumor infiltration, suppressive tumor microenvironment, and severe on-target off-tumor toxicity. Given the functionality and challenges of CTL in cancer therapy, herein, a CTL-inspired nanovesicle (MPV) with a cell membrane-derived shell and a methylene blue (MB) and cisplatin (Pt) loaded gelatin nanogel core is created. The MPV generates contrast for tumor photoacoustic imaging, and produces hyperthermia upon laser irradiation, enabling photothermal imaging and deep tumor penetration. Meanwhile, it releases MB and Pt, and then delivers them into the cytosol of cancer cells, which process can be visualized by imaging the recovery of MB-derived fluorescence. The localized hyperthermia, photodynamic therapy, and chemotherapy together kill 4T1 breast cancer cells effectively, resulting in primary tumor regression and 97% inhibition of pulmonary metastasis, without significant toxicity to the animals. Taken together, the MPV shows tumor-specific and stimuli-triggered intracellular toxin delivery with advantages in traceable accumulation and activation, high tumor penetration, and triple combination therapy, and thus can be an effective nanomedicine for combating metastatic breast cancer.

pH-Sensitive Nano-Complexes Overcome Drug Resistance and Inhibit Metastasis of Breast Cancer by Silencing Akt Expression.

The therapy of breast cancer is encumbered by drug resistance and metastasis, which can be due to a defective PI3K/AKT/mTOR signaling pathway. This study was aimed at improving the anti-cancer effect of the chemotherapeutic agent paclitaxel (PTX) on the drug resistant and metastatic breast cancer by co-delivering PTX and a siRNA, siAkt, directed at silencing the Akt expression. Methods: The pH-sensitive amphiphilic polymer, poly [(1,4-butanediol)-diacrylate-ß-N, N-diisopropylethylenediamine]-polyethyleneimine (BDP) was synthesized. The PTX-loaded BDP micelle/siAkt nano-complex (PMA) was prepared and characterized. The cellular uptake, cytotoxicity, RNA interference efficiency, biodistribution, pharmacokinetics, pharmacodynamics, and biocompatibility of PMA in the murine metastatic breast cancer 4T1 cells and the 4T1 tumor-bearing mice were evaluated. Results: PMA was stable at the neutral as well as tumor extracellular pH and released the drugs in the intra-endo/lysosome acidic environment. In 4T1 cells, the RNA interference against the Akt gene down-regulated the expression of Akt and P-glycoprotein and up-regulated the expression of Caspase-3. The down-regulated P-gp inhibits the efflux of PTX thereby increasing its intracellular concentration, improving the cytotoxicity, and inhibiting the migration and invasion of 4T1 cells. In the 4T1 tumor-bearing mice, co-delivery of PTX and siAkt by PMA achieved a tumor inhibiting rate of 94.1% and suppressed 96.8% lung metastases. PMA did not cause pathological lesions in normal organs. Conclusion: PMA, by virtue of overcoming drug resistance and simultaneously restraining lung metastasis, might be an efficient drug delivery system for the therapy of breast cancer.

In-situ synchrotron wide-angle X-ray diffraction as a rapid method for cocrystal/salt screening.

The purpose of this work was to explore in-situ synchrotron wide-angle X-ray diffraction (WAXD) as a rapid and accurate tool to screen and monitor the formation of cocrystal/salts during heating. The active pharmaceutical ingredients (caffeine, carbamazepine and lamotrigine) were respectively mixed with the coformer (saccharin), and then heated by the hot stage. Real-time process monitoring was performed using synchrotron WAXD to assess cocrystal formation and subsequently compared to differential scanning calorimetry (DSC) measurements. The effect of heating rates and cocrystal growth behavior were investigated. Synchrotron WAXD was fast and sensitive to detect cocrystal formation with the appearance of characteristic diffraction rings, even at the heating rate of 30°C/min, while DSC curves showed overlapped peaks. Unlike the indirect characterization of DSC on endo/exothermic peaks, synchrotron WAXD can directly and qualitatively determine cocrystal by diffraction peaks. The diffraction intensity-temperature curves and the corresponding first-derivative curves clearly exhibited the growth behavior of cocrystal upon heating, providing useful information to optimize the process temperature of hot melt extrusion to continuously manufacture cocrystal. The study suggests that in-situ synchrotron WAXD could provide a one-step process to screen cocrystal at high efficiency and reveal the details of cocrystal/salts growth behavior.