Multi-responsive nanotheranostics with enhanced tumor penetration and oxygen self-producing capacities for multimodal synergistic cancer therapy

Nano-sensitizer with self-amplified drug release and hypoxia normalization properties potentiates efficient chemoradiotherapy of pancreatic cancer

The hypoxic nature of pancreatic cancer, one of the most lethal malignancies worldwide, significantly impedes the effectiveness of chemoradiotherapy. Although the development of oxygen carriers and hypoxic sensitizers has shown promise in overcoming tumor hypoxia. The heterogeneity of hypoxia-primarily caused by limited oxygen penetration-has posed challenges. In this study, we designed a hypoxia-responsive nano-sensitizer by co-loading tirapazamine (TPZ), KP372-1, and MK-2206 in a metronidazole-modified polymeric vesicle. This nano-sensitizer relies on efficient endogenous NAD(P)H quinone oxidoreductase 1-mediated redox cycling induced by KP372-1, continuously consuming periphery oxygen and achieving evenly distributed hypoxia. Consequently, the normalized tumor microenvironment facilitates the self-amplified release and activation of TPZ without requiring deep penetration. The activated TPZ and metronidazole further sensitize radiotherapy, significantly reducing the radiation dose needed for extensive cell damage. Additionally, the coloaded MK-2206 complements inhibition of therapeutic resistance caused by Akt activation, synergistically enhancing the hypoxic chemoradiotherapy. This successful hypoxia normalization strategy not only overcomes hypoxia resistance in pancreatic cancer but also provides a potential universal approach to sensitize hypoxic tumor chemoradiotherapy by reshaping the hypoxic distribution.

Mitochondrial metabolism blockade nanoadjuvant reversed immune-resistance microenvironment to sensitize albumin-bound paclitaxel-based chemo-immunotherapy

Currently, the efficacy of albumin-bound paclitaxel (PTX@Alb) is still limited due to the impaired PTX@Alb accumulation in tumors partly mediated by the dense collagen distribution. Meanwhile, acquired immune resistance always occurs due to the enhanced programmed cell death-ligand 1 (PD-L1) expression after PTX@Alb treatment, which then leads to immune tolerance. To fill these gaps, we newly revealed that tamoxifen (TAM), a clinically widely used adjuvant therapy for breast cancer with mitochondrial metabolism blockade capacity, could also be used as a novel effective PD-L1 and TGF-β dual-inhibitor via inducing the phosphorylation of adenosine 5'-monophosphate-activated protein kinase (AMPK) protein. Following this, to obtain a more significant effect, TPP-TAM was prepared by conjugating mitochondria-targeted triphenylphosphine (TPP) with TAM, which then further self-assembled with albumin (Alb) to form TPP-TAM@Alb nanoparticles. By doing this, TPP-TAM@Alb nanoparticles effectively decreased the expression of collagen in vitro, which then led to the enhanced accumulation of PTX@Alb in 4T1 tumors. Besides, TPP-TAM@Alb also effectively decreased the expression of PD-L1 and TGF-β in tumors to better sensitize PTX@Alb-mediated chemo-immunotherapy by enhancing T cell infiltration. All in all, we newly put forward a novel mitochondrial metabolism blockade strategy to inhibit PTX@Alb-resistant tumors, further supporting its better clinical application.

Dual-driven nanomotors enable tumor penetration and hypoxia alleviation for calcium overload-photo-immunotherapy against colorectal cancer

The treatment efficacies of conventional medications against colorectal cancer (CRC) are restricted by a low penetrative, hypoxic, and immunosuppressive tumor microenvironment. To address these restrictions, we developed an innovative antitumor platform that employs calcium overload-phototherapy using mitochondrial N770-conjugated mesoporous silica nanoparticles loaded with CaO2 (CaO2-N770@MSNs). A loading level of 14.0 wt% for CaO2-N770@MSNs was measured, constituting an adequate therapeutic dosage. With the combination of oxygen generated from CaO2 and hyperthermia under near-infrared irradiation, CaO2-N770@MSNs penetrated through the dense mucus, accumulated in the colorectal tumor tissues, and inhibited tumor cell growth through endoplasmic reticulum stress and mitochondrial damage. The combination of calcium overload and phototherapy revealed high therapeutic efficacy against orthotopic colorectal tumors, alleviated the immunosuppressive microenvironment, elevated the abundance of beneficial microorganisms (e.g., Lactobacillaceae and Lachnospiraceae), and decreased harmful microorganisms (e.g., Bacteroidaceae and Muribaculaceae). Moreover, together with immune checkpoint blocker (αPD-L1), these nanoparticles showed an ability to eradicate both orthotopic and distant tumors, while potentiating systemic antitumor immunity. This treatment platform (CaO2-N770@MSNs plus αPD-L1) open a new horizon of synergistic treatment against hypoxic CRC with high killing power and safety.

Stimuli-activatable nanomedicine meets cancer theranostics

Stimuli-activatable strategies prevail in the design of nanomedicine for cancer theranostics. Upon exposure to endogenous/exogenous stimuli, the stimuli-activatable nanomedicine could be self-assembled, disassembled, or functionally activated to improve its biosafety and diagnostic/therapeutic potency. A myriad of tumor-specific features, including a low pH, a high redox level, and overexpressed enzymes, along with exogenous physical stimulation sources (light, ultrasound, magnet, and radiation) have been considered for the design of stimuli-activatable nano-medicinal products. Recently, novel stimuli sources have been explored and elegant designs emerged for stimuli-activatable nanomedicine. In addition, multi-functional theranostic nanomedicine has been employed for imaging-guided or image-assisted antitumor therapy. In this review, we rationalize the development of theranostic nanomedicine for clinical pressing needs. Stimuli-activatable self-assembly, disassembly or functional activation approaches for developing theranostic nanomedicine to realize a better diagnostic/therapeutic efficacy are elaborated and state-of-the-art advances in their structural designs are detailed. A reflection, clinical status, and future perspectives in the stimuli-activatable nanomedicine are provided.

Recent advances in mucus-penetrating nanomedicines for oral treatment of colonic diseases

INTRODUCTION

Oral administration is the most common route for treating colonic diseases that present increased incidences in recent years. Colonic mucus is a critical rate-limiting barrier for the accumulation of oral therapeutics in the colonic tissues. To overcome this obstacle, mucus-penetrating nanotherapeutics have been exploited to increase the accumulated amounts of drugs in the diseased sites and improve their treatment outcomes against colonic diseases.

AREAS COVERED

In this review, we introduce the structure and composition of colonic mucus as well as its impact on the bioavailability of oral drugs. We also introduce various technologies used in the construction of mucus-penetrating nanomedicines (e.g. surface modification of polymers, physical means and biological strategies) and discuss their mechanisms and potential techniques for improving mucus penetration of nanotherapeutics.

EXPERT OPINION

The mucus barrier is often overlooked in oral drug delivery. The weak mucus permeability of conventional medications greatly lowers drug bioavailability. This challenge can be addressed through physical, chemical and biological technologies. In addition to the reported methods, promising approaches may be discovered through interdisciplinary research that further helps enhance the mucus penetration of nanomedicines.

A new chitosan-based thermosensitive nanoplatform for combined photothermal and chemotherapy

Targeting the delivery of anti-cancer drugs to a tumor site is essential for effective treatment and to ensure minimal damage to healthy cells and tissues. In this work, a chitosan-based nanoplatform was constructed for combined photothermal therapy and chemotherapy of breast cancer. The pH-sensitive and biocompatible biopolymer chitosan (CS) was grafted with N-vinylcaprolactam (NVCL) and modified with biotin (Bio), imparting it with temperature sensitive property and also the ability for active targeting. The polymer self-assembled to give nanoparticles (NPs) loaded with indocyanine green (ICG) and doxorubicin (DOX). When the NPs are exposed to near-infrared (NIR) laser irradiation, ICG converts the light to heat, inducing a significant phase transition in the NPs and facilitating the release of the drug cargo. In addition, the solubility of chitosan is increased in the slightly acidic microenvironment of the tumor site, which also promotes drug release. A detailed analysis of the NPs both in vitro and in vivo showed that the carrier system is biocompatible, while the drug-loaded NPs are selectively taken up by cancer cells. Particularly when augmented with NIR irradiation, this leads to potent cell death in vitro and also in an in vivo murine xenograft model of breast cancer.

Highly Biocompatible Apigenin-Loaded Silk Fibroin Nanospheres: Preparation, Characterization, and Anti-Breast-Cancer Activity

Breast cancer is among the most common fatal diseases among women. Low-toxicity apigenin (AGN) is of interest due to its good antitumor activity, but its clinical application is severely limited due to its poor water solubility and low bioavailability. An effective strategy to enhance the anti-breast-cancer activity of AGN is to develop it as a nanodelivery system. Silk fibroin (SF) is an ideal drug carrier with good biocompatibility, biodegradability, and a simple extraction process. This paper develops a novel and efficient apigenin-loaded silk fibroin nanodelivery system (SF-AGN) by nanoprecipitation with SF as a carrier. The system was characterized in terms of morphology, zeta potential, particle size, ultraviolet (UV), infrared (IR), and synchronous thermal analyses (TG-DSC), and the in vitro cytotoxicity and in vivo pharmacokinetics were examined. Finally, the chronic toxicity of SF-AGN in mice was studied. The SF-AGN nanodelivery system has good dispersibility, a hydrated particle size of 163.35 nm, a zeta potential of -18.5 mV, an average drug loading of 6.20%, and good thermal stability. MTT studies showed that SF-AGN significantly enhanced the inhibitory effect of AGN on 4T1 and MDA-MB-231 cells. Pharmacokinetic studies have demonstrated that SF-AGN can dramatically improve the bioavailability of AGN. The results of toxicity experiments showed that SF-AGN is biocompatible and does not alter normal tissues or organs. In sum, the SF-AGN nanodelivery system is a promising drug-delivery system for the clinical treatment of breast cancer.

Cascade two-stage tumor re-oxygenation and immune re-sensitization mediated by self-assembled albumin-sorafenib nanoparticles for enhanced photodynamic immunotherapy

As a promising modality for cancer therapy, photodynamic therapy (PDT) still acquired limited success in clinical nowadays due to the extremely serious hypoxia and immunosuppression tumor microenvironment. To ameliorate such a situation, we rationally designed and prepared cascade two-stage re-oxygenation and immune re-sensitization BSA-MHI148@SRF nanoparticles via hydrophilic and hydrophobic self-assembly strategy by using near-infrared photodynamic dye MHI148 chemically modified bovine serum albumin (BSA-MHI148) and multi-kinase inhibitor Sorafenib (SRF) as a novel tumor oxygen and immune microenvironment regulation drug. Benefiting from the accumulation of SRF in tumors, BSA-MHI148@SRF nanoparticles dramatically enhanced the PDT efficacy by promoting cascade two-stage tumor re-oxygenation mechanisms: (i) SRF decreased tumor oxygen consumption via inhibiting mitochondria respiratory. (ii) SRF increased the oxygen supply via inducing tumor vessel normalization. Meanwhile, the immunosuppression micro-environment was also obviously reversed by two-stage immune re-sensitization as follows: (i) Enhanced immunogenic cell death (ICD) production amplified by BSA-MHI148@SRF induced reactive oxygen species (ROS) generation enhanced T cell infiltration and improve its tumor cell killing ability. (ii) BSA-MHI148@SRF amplified tumor vessel normalization by VEGF inhibition also obviously reversed the tumor immune-suppression microenvironment. Finally, the growth of solid tumors was significantly depressed by such well-designed BSA-MHI148@SRF nanoparticles, which could be potential for clinical cancer therapy.

Oral Nanomotor-Enabled Mucus Traverse and Tumor Penetration for Targeted Chemo-Sono-Immunotherapy against Colon Cancer

The therapeutic outcomes of oral nanomedicines against colon cancer are heavily compromised by their lack of specific penetration into the internal tumor, favorable anti-tumor activity, and activation of anti-tumor immunity. Herein, hydrogen peroxide (H₂ O₂ )/ultrasound (US)-driven mesoporous manganese oxide (MnO_x )-based nanomotors are constructed by loading mitochondrial sonosensitizers into their mesoporous channels and orderly dual-functionalizing their surface with silk fibroin and chondroitin sulfate. The locomotory activities and tumor-targeting capacities of the resultant nanomotors (CS-ID@NMs) are greatly improved in the presence of H₂ O₂ and US irradiation, inducing efficient mucus-traversing and deep tumor penetration. The excess H₂ O₂ in the tumor microenvironment (TME) is decomposed into hydroxyl radicals and oxygen by an Mn²⁺ -mediated Fenton-like reaction, and the produced oxygen participates in sonodynamic therapy (SDT), yielding abundant singlet oxygen. The combined Mn²⁺ -mediated chemodynamic therapy and SDT cause effective ferropotosis of tumor cells and accelerate the release of tumor antigens. Importantly, animal experiments reveal that the treatment of combining oral hydrogel (chitosan/alginate)-embedding CS-ID@NMs and immune checkpoint inhibitors can simultaneously suppress the growth of primary and distal tumors through direct killing, reversion of immunosuppressive TME, and potentiation of systemic anti-tumor immunity, demonstrating that the CS-ID@NM-based platform is a robust oral system for synergistic treatment of colon cancer.

Mucus-Penetrating Silk Fibroin-Based Nanotherapeutics for Efficient Treatment of Ulcerative Colitis

Oral nanoparticles have been considered a prospective drug delivery carrier against ulcerative colitis (UC). To enhance the mucus-penetrating capacity and aqueous solubility, and strengthen the anti-inflammatory effect of resveratrol (RSV), we fabricated RSV-loaded silk fibroin-based nanoparticles with the functionalization of Pluronic F127 (PF-127). The obtained PF-127-functionalized RSV-loaded NPs had an average particle size around 170 nm, a narrow size distribution (polydispersity index < 0.2), and negative zeta potential (−20.5 mV). Our results indicated that the introduction of PF-127 strengthened the mucus-penetrating property of NPs. In vitro studies suggested that NPs with PF-127 enhanced the suppression of the secretion of proinflammatory cytokine TNF-α and reactive oxygen species (ROS) from RAW 264.7 macrophages under lipopolysaccharide stimulation in comparison with other counterparts. According to the evaluation of macro symptoms and main inflammatory cytokines, we further report preferable therapeutic outcomes achieved by PF-127 functionalized-NP-treated dextran sulphate sodium (DSS) groups in the colitis model compared with blank silk fibroin NPs and RSV-loaded NPs without the functionalization of PF-127. Taken together, this work suggests that the fabricated PF-127 NPs via the oral route are promising and useful RSV-loaded nanocarriers for UC treatment.