Development of a Tumor-Responsive Nanopolyplex Targeting Pancreatic Cancer Cells and Stroma

Enhancing immunotherapy with tumour-responsive nanomaterials

The targeted delivery of immunotherapies to tumours using tumour-responsive nanomaterials is a promising area of cancer research with the potential to address the limitations of systemic administration such as on-target off-tumour toxicities and a lack of activity owing to the immunosuppressive tumour microenvironment (TME). Attempts to address these challenges include the design and functionalization of nanomaterials capable of releasing their cargoes in response to specific TME characteristics, thus facilitating the targeted delivery of immune-checkpoint inhibitors, cytokines, mRNAs, vaccines and, potentially, chimaeric antigen receptors as well as of agents that modulate the extracellular matrix and induce immunogenic cell death. In this Review, we describe these various research efforts in the context of the dynamic properties of the TME, such as pH, reductive conditions, reactive oxygen species, hypoxia, specific enzymes, high levels of ATP and locoregional aspects, which can be leveraged to enhance the specificity and efficacy of nanomaterial-based immunotherapies. Highlighting preclinical successes and ongoing clinical trials, we evaluate the current landscape and potential of these innovative approaches. We also consider future research directions as well as the most important barriers to successful clinical translation, emphasizing the transformative potential of tumour-responsive nanomaterials in overcoming the barriers that limit the activity of traditional immunotherapies, thus improving patient outcomes.

A biomimetic dual-targeting nanomedicine for pancreatic cancer therapy

The physiological characteristics of pancreatic cancer (PC) involve the interplay between tumor cells, cancer-associated fibroblasts (CAF) and the extracellular matrix (ECM). This intricate microenvironment contributes to the cancer's resistance to conventional chemoradiotherapy and its poor prognosis. Carbon monoxide (CO), a promising molecule in gas therapy, can effectively penetrate solid tumors and induce tumor cell apoptosis at high concentrations. However, precise dosing control remains a significant challenge in the administration of exogenous CO, and its inherent toxicity at elevated concentrations presents substantial barriers to clinical translation. In this study, we developed a novel biomimetic nanomedical drug delivery system capable of simultaneously targeting CAF and PC tumor cells, degrading the ECM, and inhibiting tumor growth. The strategy integrates iron carbonyl (FeCO), an anti-cancer agent, and losartan (Lo), a drug that degrades tumor matrix, into a biodegradable nanomaterial-mesoporous polydopamine (MPDA). The resulting nanoparticles are then coated with CAF cell membranes (CAFM) and functionalized with plectin-1 targeted peptide (PTP), a molecule that targets PC cells, to construct the (Lo + FeCO)@MPDA@CAFM-PTP nanomedicine. This system utilizes the homologous adhesion properties of CAF membranes to target CAFs, delivering Lo to degrade the ECM. Following ECM degradation, the nanomedicine penetrates further to bind to PC tumor cells via PTP. Then anti-cancer drug FeCO is released to react with the excessive reactive oxygen species (ROS) in PC tumor cells to produce high concentrations of CO, effectively inducing tumor cell apoptosis. The (Lo + FeCO)@MPDA@CAFM-PTP nanomedicine demonstrated significant cytotoxicity against Panc-1 cells in vitro and effectively inhibited PC tumor growth in vivo. This innovative approach holds great promise for advancing pancreatic cancer treatment.

Development of a peptide-based tumor-activated checkpoint inhibitor for cancer immunotherapy

Antibody-based checkpoint inhibitors have achieved great success in cancer immunotherapy, but their uncontrollable immune-related adverse events remain a major challenge. In this study, we developed a tumor-activated nanoparticle that is specifically active in tumors but not in normal tissues. We discovered a short anti-PD-L1 peptide that blocks the PD-1/PD-L1 interaction. The peptide was modified with a PEG chain through a novel matrix metalloproteinase-2 (MMP-2)-specific cleavage linker. The modified TR3 peptide self-assembles into a micelle-like nanoparticle (TR3-M-NP), which remains inactive and unable to block the PD-1/PD-L1 interaction in its native form. However, upon cleavage by MMP-2 in tumors, it releases the active peptide. The TR3-M-NP5k nanoparticle was specifically activated in tumors through enzyme-mediated cleavage, leading to the inhibition of tumor growth and extended survival compared to control groups. In summary, TR3-M-NP shows great potential as a tumor-responsive immunotherapy agent with reduced toxicities. STATEMENT OF SIGNIFICANCE: In this study, we developed a bioactive peptide-based checkpoint inhibitor that is active only in tumors and not in normal tissues, thereby potentially avoiding immune-related adverse effects. We discovered a short anti-PD-L1 peptide, TR3, that blocks the PD-1/PD-L1 interaction. We chemically modified the TR3 peptide to self-assemble into a micelle-like nanoparticle (TR3-M-NP), which itself cannot block the PD-1/PD-L1 interaction but releases the active TR3 peptide in tumors upon cleavage by MMP-2. In contrast, the nanoparticle is randomly degraded in normal tissues into peptides fragments that cannot block the PD-1/PD-L1 interaction. Upon intraperitoneal injection, TR3-M-NP5k was activated specifically in tumors through enzyme cleavage, leading to the inhibition of tumor growth and extended survival compared to the control groups. In summary, TR3-M-NP holds significant promise as a tumor-responsive immunotherapy agent with reduced toxicities. The bioactive platform has the potential to be used for other types of checkpoint inhibitor.

Plectin-1-targeted recognition for enhancing comprehensive therapy in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) poses a formidable challenge due to its aggressive nature and poor prognosis. Gemcitabine (Gem), a primary therapeutic option, functions by inhibiting DNA synthesis and promoting apoptosis, thereby impeding the progression of PDAC. However, Gem is hindered by suboptimal pharmacokinetics and efficacy. In response to these challenges, we have developed a nanoparticle (NP) designed for specific recognition of plectin-1 in PDAC cell membranes. The NPs encapsulate Gem while demonstrating pH-responsive drug release characteristics in the acidic tumor microenvironment. This targeted approach enhances local drug delivery while alleviating concerns about systemic toxicity. Furthermore, the NPs are enriched with indocyanine green (ICG), renowned for its strong photothermal effects, thereby further enhancing therapeutic outcomes. This study presents an innovative therapeutic strategy for PDAC based on a plectin-1-targeted recognition delivery approach. The approach is applied to enhance chemotherapy, combined with photothermal therapy (PTT), inducing apoptosis in PDAC cell lines and improving the pharmacokinetics of Gem. In conclusion, the delivery strategy based on plectin-1-targeted recognition shows promising preclinical prospects for enhancing therapeutic efficacy in PDAC, offering valuable insights for future clinical applications.

Gelatin-coated glutathione depletion and oxygen generators in potentiated chemotherapy for pancreatic cancer

Chemotherapy is generally acknowledged as an effective method for pancreatic cancer (PC). However, its treatment efficacy is often compromised due to inefficient drug delivery and drug resistance propensity of tumor tissues. The purpose of this study is to design and develop a novel drug delivery system (Manganese-doped mesoporous silica nanoparticles, Mn-MSN) in which paclitaxel (PTX), a conventional chemotherapeutic agent used to effectively treat pancreatic cancer clinically. Through cross-linking with glutaraldehyde, gelatin (Ge) was encapsulated on the carrier surface, endowing the nanoparticles (Ge-Mn-MSN@PTX) with excellent biocompatibility, low hemolytic activity, and enzyme-responsive degradation. Mn was added for the following purposes: (1) catalyzing hydrogen peroxide (H2O2) to generate oxygen (O2), thereby alleviating tumor hypoxia and drug resistance; (2) depleting glutathione (GSH), inducing intracellular lipid peroxidation and ferroptosis; (3) enabling real-time monitoring of the therapeutic efficacy of the nanoparticles via magnetic resonance imaging (MRI). The experimental results demonstrated that Ge-Mn-MSN@PTX has satisfactory biosafety, antitumor activity, controlled drug release as well as imaging tracking capabilities. In the SW1990 nude mice model, the Ge-Mn-MSN@PTX effectively inhibited tumor growth by suppressing the expression of the resistance protein P-glycoprotein (P-gp) and inducing ferroptosis. In conclusion, the designed gelatin-coated Mn-MSN shows potential for application in future pancreatic cancer therapy.

Delivery of a STING Agonist Using Lipid Nanoparticles Inhibits Pancreatic Cancer Growth

Introduction

The tumor microenvironment (TME) of pancreatic cancer is highly immunosuppressive and characterized by a large number of cancer-associated fibroblasts, myeloid-derived suppressor cells, and regulatory T cells. Stimulator of interferon genes (STING) is an endoplasmic reticulum receptor that plays a critical role in immunity. STING agonists have demonstrated the ability to inflame the TME, reduce tumor burden, and confer anti-tumor activity in mouse models. 2'3' cyclic guanosine monophosphate adenosine monophosphate (2'3'-cGAMP) is a high-affinity endogenous ligand of STING. However, delivering cGAMP to antigen-presenting cells and tumor cells within the cytosol remains challenging due to membrane impermeability and poor stability.

Methods

In this study, we encapsulated 2'3'-cGAMP in a lipid nanoparticle (cGAMP-LNP) designed for efficient cellular delivery. We assessed the properties of the nanoparticles using a series of in-vitro studies designed to evaluate their cellular uptake, cytosolic release, and minimal cytotoxicity. Furthermore, we examined the nanoparticle's anti-tumor effect in a syngeneic mouse model of pancreatic cancer.

Results

The lipid platform significantly increased the cellular uptake of 2'3'-cGAMP. cGAMP-LNP exhibited promising antitumor activity in the syngeneic mouse model of pancreatic cancer.

Discussion

The LNP platform shows promise for delivering exogenous 2'3'-cGAMP or its derivatives in cancer therapy.

Dual Starvations Induce Pyroptosis for Orthotopic Pancreatic Cancer Therapy through Simultaneous Deprivation of Glucose and Glutamine

Pancreatic cancer is a highly fatal disease, and existing treatment methods are ineffective, so it is urgent to develop new effective treatment strategies. The high dependence of pancreatic cancer cells on glucose and glutamine suggests that disrupting this dependency could serve as an alternative strategy for pancreatic cancer therapy. We identified the vital genes glucose transporter 1 (GLUT1) and alanine-serine-cysteine transporter 2 (ASCT2) through bioinformatics analysis, which regulate glucose and glutamine metabolism in pancreatic cancer, respectively. Human serum albumin nanoparticles (HSA NPs) for delivery of GLUT1 and ASCT2 inhibitors, BAY-876/V-9302@HSA NPs, were prepared by a self-assembly process. This nanodrug inhibits glucose and glutamine uptake of pancreatic cancer cells through the released BAY-876 and V-9302, leading to nutrition deprivation and oxidative stress. The inhibition of glutamine leads to the inhibition of the synthesis of the glutathione, which further aggravates oxidative stress. Both of them lead to a significant increase in reactive oxygen species, activating caspase 1 and GSDMD and finally inducing pyroptosis. This study provides a new effective strategy for orthotopic pancreatic cancer treatment by dual starvation-induced pyroptosis. The study for screening metabolic targets using bioinformatics analysis followed by constructing nanodrugs loaded with inhibitors will inspire future targeted metabolic therapy for pancreatic cancer.

Direct cytoplasmic delivery of RNAi therapeutics through a non-lysosomal pathway for enhanced gene therapy

The first approved RNAi therapeutics, ONPATTRO, in 2017 moves the concept of RNA interference (RNAi) therapy from research to clinical reality, raising the hopes for the treatment of currently incurable diseases. However, RNAi therapeutics are still facing two main challenges-susceptibility to enzymatic degradation and low ability to escape from endo/lysosome into the cytoplasm. Therefore, we developed disulfide-based nanospheres (DBNPs) as universal vehicles to achieve efficient RNA delivery to address these problems. Notably, the DBNPs possess unique and desirable features, including improved resistance to nuclease degradation, direct cytoplasmic delivery through thiol-mediated cellular uptake, and cytosolic environment-responsive release, greatly enhancing the bioavailability of RNA therapeutics. Additionally, DBNPs are superior in terms of overcoming formidable physiological barriers, including vascular barriers and impermeable tumor tissues. Owning to these advantages, the DBNPs exhibit efficient gene silencing effect when delivering either small interfering RNA (siRNA) or microRNA in various cell lines and generate remarkable growth inhibition in the zebrafish and mouse model of pancreatic tumors as compared to traditional delivery vectors, such as PEI. Therefore, DBNPs have potential application prospect in RNAi therapy both in vitro and in vivo. STATEMENT OF SIGNIFICANCE: RNA interference (RNAi) therapeutics could target and alter any disease-related mRNA translation, thus have great potential in clinical application. Delivery efficiency of RNA modalities into cell cytoplasm is the main problem that currently limit RNAi therapeutics to release their full potential. Most of the known delivery materials suffer from the endo/lysosomal entrapment and enzymatic degradation during endocytosis-dependent uptake, resulting unsatisfied efficiency of the cytoplasmic release. Here, we developed disulfide-based nanospheres could directly transfer RNA modalities into the cytoplasm and significantly enhance the delivery efficiency, thus holding great potential in RNAi therapy.

Evaluation of cell membrane-derived nanoparticles as therapeutic carriers for pancreatic ductal adenocarcinoma using an in vitro tumour stroma model

Here, we fabricated nanoparticles made solely from the membrane of cells found in the pancreatic tumour's microenvironment (TME), like the human MiaPaCa-2 cells and M2-polarized macrophages. The cell membrane-derived nanoparticles (CMNPs) deriving from the MiaPaCa-2 cells (MPC2-CMNPs) were loaded with the chemotherapeutic drug paclitaxel (PTX), and the CMNPs deriving from M2-polarized macrophages (M2-CMNPs) were loaded with the colony-stimulating factor 1 receptor inhibitor, pexidartinib (PXDB). The CMNPs' thorough morphological and physicochemical characterisation was followed by an in-depth study of their targeting ability and the endocytosis pathway involved during their internalisation. An in vitro model of the desmoplastic stroma comprising cancer-associated fibroblast-mimicking cells and M2-polarized macrophages was also developed. The model was characterised by collagen and α-smooth muscle actin (α-SMA) expression (overexpressed in desmoplasia) and was used to assess the CMNPs' ability to cross the stroma and target the tumour cells. Moreover, we assessed the effect of PXDB-loaded M2-CMNPs on the expression of M1 (CD80/CD86) and M2 (CD206/CD209) polarisation markers on activated macrophages. Finally, we evaluated the PTX and PXDB-loaded CMNPs' effect on the viability of all the used TME cell lines alone or in combination. Overall, this pilot study showed the potential of the CMNPs to cross an in vitro stroma model and act synergistically to treat PDAC.

Role of plectin and its interacting molecules in cancer

Plectin, as the cytolinker and scaffolding protein, are widely expressed and abundant in many tissues, and has involved in various cellular activities contributing to tumorigenesis, such as cell adhesion, migration, and signal transduction. Due to the specific expression and differential localization of plectin in cancer, most researchers focus on the role of plectin in cancer, and it has emerged as a potent driver of malignant hallmarks in many human cancers, which provides the possibility for plectin to be widely used as a biomarker and therapeutic target in the early diagnosis and targeted drug delivery of the disease. However, there is still a lack of systematic review on the interaction molecules and mechanism of plectin. Herein, we summarized the structure, expression and function of plectin, and mainly focused on recent studies on the functional and physical interactions between plectin and its interacting molecules, shedding light on the potential of targeting plectin for cancer therapy.

Biomimetic Gold Nanorods Modified with Erythrocyte Membranes for Imaging-Guided Photothermal/Gene Synergistic Therapy

Pancreatic cancer (PC) is one of the most malignant cancers that develops rapidly and carries a poor prognosis. Synergistic cancer therapy strategy could enhance the clinical efficacy compared to either treatment alone. In this study, gold nanorods (AuNRs) were used as siRNA delivery vehicles to interfere with the oncogenes of KRAS. In addition, AuNRs were one of anisotropic nanomaterials that can absorb near-infrared (NIR) laser and achieve rapid photothermal therapy for malignant cancer cells. Modification of the erythrocyte membrane and antibody Plectin-1 occurred on the surface of the AuNRs, making them a promising target nanocarrier for enhancing antitumor effects. As a result, biomimetic nanoprobes presented advantages in biocompatibility, targeting capability, and drug-loading efficiency. Moreover, excellent antitumor effects have been achieved by synergistic photothermal/gene treatment. Therefore, our study would provide a general strategy to construct a multifunctional biomimetic theranostic multifunctional nanoplatform for preclinical studies of PC.

Drug Delivery Strategies for the Treatment of Pancreatic Cancer

Pancreatic cancer is fast becoming a global menace and it is projected to be the second leading cause of cancer-related death by 2030. Pancreatic adenocarcinomas, which develop in the pancreas' exocrine region, are the predominant type of pancreatic cancer, representing about 95% of total pancreatic tumors. The malignancy progresses asymptomatically, making early diagnosis difficult. It is characterized by excessive production of fibrotic stroma known as desmoplasia, which aids tumor growth and metastatic spread by remodeling the extracellular matrix and releasing tumor growth factors. For decades, immense efforts have been harnessed toward developing more effective drug delivery systems for pancreatic cancer treatment leveraging nanotechnology, immunotherapy, drug conjugates, and combinations of these approaches. However, despite the reported preclinical success of these approaches, no substantial progress has been made clinically and the prognosis for pancreatic cancer is worsening. This review provides insights into challenges associated with the delivery of therapeutics for pancreatic cancer treatment and discusses drug delivery strategies to minimize adverse effects associated with current chemotherapy options and to improve the efficiency of drug treatment.

Regulation of metabolism in pancreatic ductal adenocarcinoma via nanotechnology-enabled strategies

Pancreatic ductal adenocarcinoma (PDAC) is a highly fatal malignancy with insidious onset and early distal metastasis. Metabolic reprogramming, the autonomous changes in cellular bioenergetics driven by aberrant genetic events and crosstalk between cancer and non-cancer cells in the desmoplastic microenvironment, is pivotal for the rapid progression of PDAC. As an attractive therapeutic target, nucleoside metabolism is regulated by various anti-metabolic drugs for the clinical treatment of PDAC. Despite various challenges, such as poor drug delivery efficiency and off-target side effects, metabolic modification and intervention are emerging as promising strategies for PDAC therapy, enabled by the rapid development of nanotechnology-based drug delivery strategies. In this review, we discuss the metabolic characteristics of PDAC and highlight how the development of nanomedicine has boosted the development of new therapeutics for PDAC by modulating critical targets in metabolic reprogramming.

Recent Advances in Well-Designed Therapeutic Nanosystems for the Pancreatic Ductal Adenocarcinoma Treatment Dilemma

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant tumor with an extremely poor prognosis and low survival rate. Due to its inconspicuous symptoms, PDAC is difficult to diagnose early. Most patients are diagnosed in the middle and late stages, losing the opportunity for surgery. Chemotherapy is the main treatment in clinical practice and improves the survival of patients to some extent. However, the improved prognosis is associated with higher side effects, and the overall prognosis is far from satisfactory. In addition to resistance to chemotherapy, PDAC is significantly resistant to targeted therapy and immunotherapy. The failure of multiple treatment modalities indicates great dilemmas in treating PDAC, including high molecular heterogeneity, high drug resistance, an immunosuppressive microenvironment, and a dense matrix. Nanomedicine shows great potential to overcome the therapeutic barriers of PDAC. Through the careful design and rational modification of nanomaterials, multifunctional intelligent nanosystems can be obtained. These nanosystems can adapt to the environment's needs and compensate for conventional treatments' shortcomings. This review is focused on recent advances in the use of well-designed nanosystems in different therapeutic modalities to overcome the PDAC treatment dilemma, including a variety of novel therapeutic modalities. Finally, these nanosystems' bottlenecks in treating PDAC and the prospect of future clinical translation are briefly discussed.

Therapeutic Strategies to Overcome Fibrotic Barriers to Nanomedicine in the Pancreatic Tumor Microenvironment

Pancreatic cancer is notorious for its dismal prognosis. The enhanced permeability and retention (EPR) effect theory posits that nanomedicines (therapeutics in the size range of approximately 10-200 nm) selectively accumulate in tumors. Nanomedicine has thus been suggested to be the "magic bullet"-both effective and safe-to treat pancreatic cancer. However, the densely fibrotic tumor microenvironment of pancreatic cancer impedes nanomedicine delivery. The EPR effect is thus insufficient to achieve a significant therapeutic effect. Intratumoral fibrosis is chiefly driven by aberrantly activated fibroblasts and the extracellular matrix (ECM) components secreted. Fibroblast and ECM abnormalities offer various potential targets for therapeutic intervention. In this review, we detail the diverse strategies being tested to overcome the fibrotic barriers to nanomedicine in pancreatic cancer. Strategies that target the fibrotic tissue/process are discussed first, which are followed by strategies to optimize nanomedicine design. We provide an overview of how a deeper understanding, increasingly at single-cell resolution, of fibroblast biology is revealing the complex role of the fibrotic stroma in pancreatic cancer pathogenesis and consider the therapeutic implications. Finally, we discuss critical gaps in our understanding and how we might better formulate strategies to successfully overcome the fibrotic barriers in pancreatic cancer.

New advances in pharmaceutical strategies for sensitizing anti-PD-1 immunotherapy and clinical research

Attempts have been made continuously to use nano-drug delivery system (NDDS) to improve the effect of antitumor therapy. In recent years, especially in the application of immunotherapy represented by antiprogrammed death receptor 1 (anti-PD-1), it has been vigorously developed. Nanodelivery systems are significantly superior in a number of aspects including increasing the solubility of insoluble drugs, enhancing their targeting ability, prolonging their half-life, and reducing side effects. It can not only directly improve the efficacy of anti-PD-1 immunotherapy, but also indirectly enhance the antineoplastic efficacy of immunotherapy by boosting the effectiveness of therapeutic modalities such as chemotherapy, radiotherapy, photothermal, and photodynamic therapy (PTT/PDT). Here, we summarize the studies published in recent years on the use of nanotechnology in pharmaceutics to improve the efficacy of anti-PD-1 antibodies, analyze their characteristics and shortcomings, and combine with the current clinical research on anti-PD-1 antibodies to provide a reference for the design of future nanocarriers, so as to further expand the clinical application prospects of NDDSs. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Discovery of Cyclic Peptide Inhibitors Targeting PD-L1 for Cancer Immunotherapy

Blockade of the interaction between programmed cell death ligand-1 (PD-L1) and its receptor PD-1 has shown great success in cancer immunotherapy. Peptides possess unique characteristics that give them significant advantages as immune checkpoint inhibitors. However, unfavorable physicochemical properties and proteolytic stability profiles limit the translation of bioactive peptides as therapeutic agents. Studies have revealed that cyclization improves the biological activity and stability of linear peptides. In this study, we report the use of macrocyclization scanning for the discovery of cyclic anti-PD-L1 peptides with improved bioactivity. The cyclic peptides demonstrated up to a 34-fold improvement in the PD-1/PD-L1 blocking activity and significant in vivo anti-tumor activity. Our results demonstrate that macrocyclization scanning is an effective way to improve the serum stability and bioactivity of the anti-PD-L1 linear peptide. This strategy can be employed in the optimization of other bioactive peptides, particularly those for protein-protein interaction modulation.

Cancer-Associated Fibroblast-Targeted Delivery of Captopril to Overcome Penetration Obstacles for Enhanced Pancreatic Cancer Therapy

Pancreatic cancer is one of the most stroma-abundant solid cancers. Its desmoplastic nature restricts the penetration of drugs in tumor tissues and is considered as a major challenge for efficient chemotherapy. In the present study, we repurposed the use of captopril to deplete the overexpressed extracellular matrix (ECM) in stroma of pancreatic tumor. Precise delivery of captopril to cancer-associated fibroblasts (CAFs) was achieved using CAFs targeting peptide modified liposomes. The targeted delivery of captopril significantly downregulated the deposition of ECM by blocking the TGF-β1-Smad2 related signaling pathway, which improved the penetration of subsequently administrated liposome-encapsulated chemotherapeutic agent gemcitabine. It proved as a promising solution to break the aforementioned stromal barrier in pancreatic cancer therapy.

[99mTc]Tc-Labeled Plectin-Targeting Peptide as a Novel SPECT Probe for Tumor Imaging

Certain receptors are often overexpressed during tumor occurrence and development and closely correlate with carcinogenesis. Owing to its overexpression on the cell membrane and cytoplasm of various tumors, plectin, which is involved in tumor proliferation, migration, and invasion, has been viewed as a promising target for cancer imaging. Hence, plectin-targeting agents have great potential as imaging probes for tumor diagnosis. In this study, we developed a [99mTc]Tc-labeled plectin-targeted peptide (PTP) as a novel single-photon emission computed tomography (SPECT) probe for tumor imaging and investigated its pharmacokinetics, biodistribution, and targeting ability in several types of tumor-bearing mouse models. The PTP had good biocompatibility and targeting ability to tumor cells in vitro and could be readily labeled with [99mTc]Tc after modification with the bifunctional chelator 6-hydrazino nicotinamide (HYNIC). Furthermore, the prepared [99mTc]Tc-labeled PTP ([99mTc]Tc-HYNIC-PTP) showed high radiochemical purity and excellent stability in vitro. In addition, favorable biodistribution, fast blood clearance, and clear accumulation of [99mTc]Tc-HYNIC-PTP in several types of tumors were observed, with a good correlation between tumor uptake and plectin expression levels. These results indicate the potential of [99mTc]Tc-HYNIC-PTP as a novel SPECT probe for tumor imaging.

Dual-responsive nanosystem based on TGF-β blockade and immunogenic chemotherapy for effective chemoimmunotherapy

The antitumor immune response induced by chemotherapy has attracted considerable attention. However, the immunosuppressive tumor microenvironment hinders the immune activation effect of cancer chemotherapy. TGF-β plays a key role in driving tumor immunosuppression and can prevent effective antitumor immune response through multiple roles. In this study, a dual-responsive prodrug micelle (PAOL) is designed to co-deliver LY2109761 (a TGF-β receptor I/II inhibitor) and oxaliplatin (OXA, a conventional chemotherapy) to remodel tumor microenvironment and trigger immunogenic cell death (ICD) to induce antitumor immunity response. Under hypoxia tumor environment, the polyethylene glycol shell of the micelle cleavages, along with the release of LY2109761 and OXA prodrug. Cytotoxic effect of OXA is then activated by glutathione-mediated reduction in tumor cells and the activated OXA significantly enhances tumor immunogenicity and promotes intratumoral accumulation of cytotoxic T lymphocytes. Meanwhile, TGF-β blockade through LY2109761 reprograms tumor microenvironment by correcting the immunosuppressive state and regulating tumor extracellular matrix, which further maintaining OXA induced immune response. Therefore, due to the capability of boosting tumor-specific antitumor immunity, the bifunctional micelle presents markedly synergistic antitumor efficacies and provides a potent therapeutic strategy for chemoimmunotherapy of solid tumors.

Discovery of Anti-PD-L1 Human Domain Antibodies for Cancer Immunotherapy

Immunotherapy using monoclonal antibodies targeting the PD-1/PD-L1 interaction has shown enormous success for various cancers. Despite their encouraging results in clinics, antibody-based checkpoint inhibitors have several limitations, such as poor tumor penetration. To address these limitations of monoclonal antibodies, there is a growing interest in developing low-molecular-weight checkpoint inhibitors, such as antibody fragments. Several antibody fragments targeting PD-1/PD-L1 were recently discovered using phage libraries from camel or alpaca. However, animal-derived antibody fragments may elicit unwanted immune responses, which limit their therapeutic applications. For the first time, we used a human domain antibody phage library and discovered anti-human PD-L1 human single-domain antibodies (dAbs) that block the PD-1/PD-L1 interaction. Among them, the CLV3 dAb shows the highest affinity to PD-L1. The CLV3 dAb also exhibits the highest blocking efficacy of the PD-1/PD-L1 interaction. Moreover, the CLV3 dAb significantly inhibits tumor growth in mice implanted with CT26 colon carcinoma cells. These results suggest that CLV3 dAb can be potentially used as an anti-PD-L1 inhibitor for cancer immunotherapy.

Nanomedicine in Pancreatic Cancer: Current Status and Future Opportunities for Overcoming Therapy Resistance

Simple Summary

Despite access to a vast arsenal of anticancer agents, many fail to realise their full therapeutic potential in clinical practice. One key determinant of this is the evolution of multifaceted resistance mechanisms within the tumour that may either pre-exist or develop during the course of therapy. This is particularly evident in pancreatic cancer, where limited responses to treatment underlie dismal survival rates, highlighting the urgent need for new therapeutic approaches. Here, we discuss the major features of pancreatic tumours that contribute to therapy resistance, and how they may be alleviated through exploitation of the mounting and exciting promise of nanomedicines; a unique collection of nanoscale platforms with tunable and multifunctional capabilities that have already elicited a widespread impact on cancer management.

Abstract

The development of drug resistance remains one of the greatest clinical oncology challenges that can radically dampen the prospect of achieving complete and durable tumour control. Efforts to mitigate drug resistance are therefore of utmost importance, and nanotechnology is rapidly emerging for its potential to overcome such issues. Studies have showcased the ability of nanomedicines to bypass drug efflux pumps, counteract immune suppression, serve as radioenhancers, correct metabolic disturbances and elicit numerous other effects that collectively alleviate various mechanisms of tumour resistance. Much of this progress can be attributed to the remarkable benefits that nanoparticles offer as drug delivery vehicles, such as improvements in pharmacokinetics, protection against degradation and spatiotemporally controlled release kinetics. These attributes provide scope for precision targeting of drugs to tumours that can enhance sensitivity to treatment and have formed the basis for the successful clinical translation of multiple nanoformulations to date. In this review, we focus on the longstanding reputation of pancreatic cancer as one of the most difficult-to-treat malignancies where resistance plays a dominant role in therapy failure. We outline the mechanisms that contribute to the treatment-refractory nature of these tumours, and how they may be effectively addressed by harnessing the unique capabilities of nanomedicines. Moreover, we include a brief perspective on the likely future direction of nanotechnology in pancreatic cancer, discussing how efforts to develop multidrug formulations will guide the field further towards a therapeutic solution for these highly intractable tumours.

Smart Design of Mitochondria-Targeted and ROS-Responsive CPI-613 Delivery Nanoplatform for Bioenergetic Pancreatic Cancer Therapy

Mitochondria, as the powerhouse of most cells, are not only responsible for the generation of adenosine triphosphate (ATP) but also play a decisive role in the regulation of apoptotic cell death, especially of cancer cells. Safe potential delivery systems which can achieve organelle-targeted therapy are urgently required. In this study, for effective pancreatic cancer therapy, a novel mitochondria-targeted and ROS-triggered drug delivery nanoplatform was developed from the TPP-TK-CPI-613 (TTCI) prodrug, in which the ROS-cleave thioketal functions as a linker connecting mitochondrial targeting ligand TPP and anti-mitochondrial metabolism agent CPI-613. DSPE-PEG2000 was added as an assistant component to increase accumulation in the tumor via the EPR effect. This new nanoplatform showed effective mitochondrial targeting, ROS-cleaving capability, and robust therapeutic performances. With active mitochondrial targeting, the formulated nanoparticles (TTCI NPs) demonstrate much higher accumulation in mitochondria, facilitating the targeted delivery of CPI-613 to its acting site. The results of in vitro antitumor activity and cell apoptosis revealed that the IC₅₀ values of TTCI NPs in three types of pancreatic cancer cells were around 20~30 µM, which was far lower than those of CPI-613 (200 µM); 50 µM TTCI NPs showed an increase in apoptosis of up to 97.3% in BxPC3 cells. Therefore, this mitochondria-targeted prodrug nanoparticle platform provides a potential strategy for developing safe, targeting and efficient drug delivery systems for pancreatic cancer therapy.

Plectin in Cancer: From Biomarker to Therapeutic Target

The cytolinker and scaffolding protein, plectin, has emerged as a potent driver of malignant hallmarks in many human cancers due to its involvement in various cellular activities contributing to tumorigenesis, including cancer cell proliferation, adhesion, migration, invasion, and signal transduction. Evidence shows that beyond plectin's diverse protein interactome, its cancer-specific mislocalization to the cell surface enables its function as a potent oncoprotein. As such, therapeutic targeting of plectin, its protein interactors, and, in particular, cancer-specific plectin (CSP) presents an attractive opportunity to impede carcinogenesis directly. Here, we report on plectin's differential gene and protein expression in cancer, explore its mutational profile, and discuss the current understanding of plectin's and CSP's biological function in cancer. Moreover, we review the landscape of plectin as a prognostic marker, diagnostic biomarker, and target for imaging and therapeutic modalities. We highlight how, beyond their respective biological importance, plectin's common overexpression in cancer and CSP's cancer-specific bioavailability underscore their potential as high-value druggable targets. We discuss how recent evidence of the potent anti-cancer effects of CSP therapeutic targeting opens the door for cell-surface mislocalized proteins as novel therapeutic targets.

Co-inhibition of the TGF-β pathway and the PD-L1 checkpoint by pH-responsive clustered nanoparticles for pancreatic cancer microenvironment regulation and anti-tumor immunotherapy

Pancreatic ductal adenocarcinoma (PDAC) has a dense extracellular matrix (ECM) surrounding tumor cells to sequester CD8+ T cell infiltration and prevent drug penetration. Concomitant inhibition of both the TGF-β pathway and the PD-1/PD-L1 checkpoint is a viable strategy to increase T cell infiltration and cytotoxicity. Here, we used an acidic tumor extracellular pH (pHe) responsive clustered nanoparticle (LYiClustersiPD-L1) to deliver TGF-β receptor inhibitors (LY2157299) and siRNA targeting PD-L1 (siPD-L1) for PDAC stroma microenvironment regulation and antitumor immunotherapy. LY2157299 encapsulated in the hydrophobic core of the nanoparticle can effectively inhibit the activation of pancreatic stellate cells (PSCs) and result in a reduction in type I collagen. siPD-L1 adsorbed on the surface of the nanoparticle was released with small size poly(amidoamine) (PAMAM) at the surface of LYiClustersiPD-L1 under pHe and penetrated into the tumors to silence PD-L1 gene expression in tumor cells. Compared to monotherapy, LYiClustersiPD-L1 significantly increased tumor infiltrating CD8+ T cells and provoked antitumor immunity to synergistically suppress tumor growth in both a subcutaneous Panc02 xenograft model and an orthotopic tumor model.

Tumor microenvironment remodeling-based penetration strategies to amplify nanodrug accessibility to tumor parenchyma

Remarkable advances in nano delivery systems have provided new hope for tumor prevention, diagnosis and treatment. However, only limited clinical therapeutic effects against solid tumors were achieved. One of the main reasons is the presence of abundant physiological and pathological barriers in vivo that impair tumoral penetration and distribution of the nanodrugs. These barriers are related to the components of tumor microenvironment (TME) including abnormal tumor vasculature, rich composition of the extracellular matrix (ECM), and abundant stroma cells. Herein, we review the advanced strategies of TME remodeling to overcome these biological obstacles against nanodrug delivery. This review aims to offer a perspective guideline for the implementation of promising approaches to facilitate intratumoral permeation of nanodrugs through alleviation of biological barriers. At the same time, we analyze the advantages and disadvantages of the corresponding methods and put forward possible directions for the future researches.

Biocompatible Nanoparticles as a Platform for Enhancing Antitumor Efficacy of Cisplatin-Tetradrine Combination

Combination therapy has been a standard strategy in the clinical tumor treatment. We have demonstrated that combination of Tetradrine (Tet) and Cisplatin (CDDP) presented a marked synergistic anticancer activity, but inevitable side effects limit their therapeutic concentration. Considering the different physicochemical and pharmacokinetic properties of the two drugs, we loaded them into a nanovehicle together by the improved double emulsion method. The nanoparticles (NPs) were prepared from the mixture of poly(ethyleneglycol)-polycaprolactone (PEG-PCL) and polycarprolactone (HO-PCL), so CDDP and Tet can be located into the NPs simultaneously, resulting in low interfering effect and high stability. Images from fluorescence microscope revealed the cellular uptake of both hydrophilic and hydrophobic agents delivered by the NPs. In vitro studies on different tumor cell lines and tumor tissue revealed increased tumor inhibition and apoptosis rates. As to the in vivo studies, superior antitumor efficacy and reduced side effects were observed in the NPs group. Furthermore, ¹⁸FDG-PET/CT imaging demonstrated that NPs reduced metabolic activities of tumors more prominently. Our results suggest that PEG-PCL block copolymeric NPs could be a promising carrier for combined chemotherapy with solid efficacy and minor side effects.

Ligand decorated biodegradable nanomedicine in the treatment of cancer

Cancer is one of the major global health problems, responsible for the second-highest number of deaths. The genetic and epigenetic changes in the oncogenes or tumor suppressor genes alter the regulatory pathways leading to its onset and progression. Conventional methods are used in appropriate combinations for the treatment. Surgery effectively treats localized tumors; however, it fails to treat metastatic tumors, leading to a spread in other organs, causing a high recurrence rate and death. Among the different strategies, the nanocarriers-based approach is highly sought for, but its nonspecific delivery can cause a profound side effect on healthy cells. Targeted nanomedicine has the advantage of targeting cancer cells specifically by interacting with the receptors overexpressed on their surface, overcoming its non-specificity to target healthy cells. Nanocarriers prepared from biodegradable and biocompatible materials are decorated with different ligands by encapsulating therapeutic or diagnostic agents or both to target cancer cells overexpressing the receptors. Scientists are now utilizing a theranostic approach to simultaneously evaluate nanocarrier bio-distribution and its effect on the treatment regime. Herein, we have summarized the recent 5-year efforts in the development of the ligands decorated biodegradable nanocarriers, as a targeted nanomedicine approach, which has been highly promising in the treatment of cancer.

Emerging nanotechnological strategies to reshape tumor microenvironment for enhanced therapeutic outcomes of cancer immunotherapy

Immunotherapy has emerged as a novel cancer treatment over the last decade, however, efficacious responses to mono-immunotherapy have only been achieved in a relatively small portion of patients whereas combinational immunotherapies often lead to concurrent side effects. It has been proved that the tumor microenvironment (TME) is responsible for tumor immune escape and the ultimate treatment failure. Recently, there has been remarkable progress in both the understanding of the TME and the applications of nanotechnological strategies, and reviewing the emerging immune-regulatory nanosystems may provide valuable information for specifically modulating the TME at different immune stages. In this review, we focus on comprehending the recently-proposed T-cell-based tumor classification and identifying the most promising targets for different tumor phenotypes, and then summarizing the nanotechnological strategies to best target corresponding immune-related factors. For future precise personalized immunotherapy, tailor-made TME modulation strategies conducted by well-designed nanosystems to alleviate the suppressive TME and then promote anti-tumor immune responses will significantly benefit the clinical outcomes of cancer patients.

Aptamer-SH2 superbinder-based targeted therapy for pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) exhibits the poorest prognosis of all solid tumors with a 5-year survival rate of less than 10% and a median survival of 6 months after diagnosis. Numerous targeted agents have been developed and evaluated to improve the survival benefit in patients with PDAC. Unfortunately, most agents have been proven futile mainly owing to the dense stroma and the sophisticated signaling pathways of PDAC. Here, we show the potent effectiveness of Aptamer-SH2 superbinder-(Arg)9 conjugate on the treatment of PDAC. In this conjugate, DNA aptamer selected against PDAC cell line confers the function of specifically recognizing and binding to the PDAC cells and activated pancreatic stellate cells (PSCs) in stroma; cell penetrating peptide (Arg)9 facilitates the intracellular delivery of fused proteins; SH2 superbinder conducts the drastic blockade of multiple phosphotyrosines (pY)-based signaling pathways in tumor cells.

METHODS

PDAC-associated pY were reanalyzed by bioinformatics screen. XQ-2d and SH2 superbinder-(Arg)9 were crosslinked with BMH to form XQ-2d-SH2 CM-(Arg)9 conjugate. Immunofluorescence was utilized to assess the potency of the conjugate entering cells. MTT and wound healing assays were performed to evaluate the proliferation or migration of PANC-1 and BxPC-3 cells, respectively. Western blot and Pulldown assays revealed that conjugate influenced several pY-based signaling pathways. Tumor-bearing mice were used to validate XQ-2d-SH2 CM-(Arg)9, which restrained the growth and metastasis of cancer cells.

RESULTS

XQ-2d-His-SH2 CM-(Arg)9 conjugate restrained proliferation, invasion, and metastasis of PDAC cells with potent efficacy via blocking the activity of several pY-related signaling cascades. XQ-2d-His-SH2 CM-(Arg)9 could eliminate the dense stroma of PDAC and then arrive at tumor tissues.

CONCLUSIONS

XQ-2d-SH2 CM-(Arg)9 conjugate may efficiently destroy the pancreatic stroma and show potent antitumor efficacy with minimal toxic effect by regulating tumor cell proliferation and metastasis in vitro and in vivo, which makes it to be a promising targeted therapy of PDAC.

Silencing PCBP2 normalizes desmoplastic stroma and improves the antitumor activity of chemotherapy in pancreatic cancer

Rationale: Dense desmoplastic stroma is a fundamental characteristic of pancreatic ductal adenocarcinoma (PDAC) and comprises up to 80% of the tumor mass. Type I collagen is the major component of the extracellular matrix (ECM), which acts as a barrier to impede the delivery of drugs into the tumor microenvironment. While the strategy to deplete PDAC stroma has failed in clinical trials, normalization of the stroma to allow chemotherapy to kill the tumor cells in the “nest” could be a promising strategy for PDAC therapy. We hypothesize that silencing the poly(rC)-binding protein 2 (αCP2, encoded by the PCBP2 gene) leads to the destabilization and normalization of type I collagen in the PDAC stroma.

Methods: We develop a micro-flow mixing method to fabricate a peptide-based core-stabilized PCBP2 siRNA nanocomplex to reverse the accumulation of type I collagen in PDAC tumor stroma. Various in vitro studies were performed to evaluate the silencing activity, cellular uptake, serum stability, and tumor penetration of the PCBP2 siRNA nanocomplex. We also investigated the penetration of small molecules in stroma-rich pancreatic cancer spheroids after the treatment with the PCBP2 siRNA nanocomplex. The anti-tumor activity of the PCBP2 siRNA nanocomplex and its combination with gemcitabine was evaluated in an orthotopic stroma-rich pancreatic cancer mouse model.

Results: Silencing the PCBP2 gene using siRNA reverses the accumulation of type I collagen in human pancreatic stellate cells (PSCs) and mouse NIH 3T3 fibroblast cells. The siRNA nanocomplex significantly reduces ECM production and enhances drug penetration through desmoplastic tumor stroma. The combination of gemcitabine with the PCBP2 siRNA nanocomplex markedly suppresses the tumor progression in a desmoplastic PDAC orthotopic mouse model.

Conclusion: This approach provides a new therapeutic avenue to improve the antitumor efficacy of PDAC therapies by normalizing tumor stroma using the PCBP2 siRNA nanocomplex.

Enzyme-responsive polymeric micelles of cabazitaxel for prostate cancer targeted therapy

Cabazitaxel, a novel tubulin inhibitor with poor affinity for P-glycoprotein, is a second-generation taxane holding great promise for the treatment of metastatic castration-resistant prostate cancer. However, its poor solubility and lack of target-ability limit its therapeutic applications. Herein, we develop a biodegradable, enzyme-responsive, and targeted polymeric micelle for cabazitaxel. The micelle is formed from two amphiphilic block copolymers. The first block copolymer consists of PEG, an enzyme-responsive peptide, and cholesterol; whereas the second block copolymer consists of a targeting ligand, PEG and cholesterol. The enzyme-responsive peptide is cleavable in the presence of matrixmetaloproteinase-2 (MMP-2), which is overexpressed in the tumor microenvironment of prostate cancer. The micelle showed a very low critical micelle concentration (CMC), high drug loading, and high entrapment efficiency. Release of cabazitaxel from the micelle is dependent on the cleavage of the enzyme-responsive peptide. Moreover, the micelle showed dramatically higher cellular uptake in prostate cancer cells compared to free cabazitaxel. Importantly, the ligand-coupled polymeric micelle demonstrated better inhibition of tumor growth in mice bearing prostate cancer xenografts compared to unmodified micelle and free cabazitaxel. Taken together, these findings suggest that the enzyme-responsive cabazitaxel micelle is a potent and promising drug delivery system for advanced prostate cancer therapy. STATEMENT OF SIGNIFICANCE: Herein, we develop a biodegradable, enzyme-responsive, and actively targeted polymer micelle for cabazitaxel, which is a novel tubulin inhibitor with poor affinity for P-glycoprotein. Despite cabazitaxel's great promise for metastatic castration-resistant prostate cancer, its poor solubility, lack of target-ability, and high systemic toxicity limit its therapeutic applications, and therefore a targeted delivery system is highly needed for cabazitaxel. Our results demonstrate the importance of active targeting in targeted prostate cancer therapy. Encapsulating cabazitaxel in the micelle increases its activity and is expected to reduce its systemic toxicity, which is a major hurdle in its clinical applications. Moreover, the polymeric micelle may servers as a promising nanoscale platform for the targeted delivery of other chemotherapeutic agents to prostate cancer.

Co-delivery of IKBKE siRNA and cabazitaxel by hybrid nanocomplex inhibits invasiveness and growth of triple-negative breast cancer

IKBKE is an oncogene in triple-negative breast cancer (TNBC), and we demonstrate that IKBKE small interfering RNA (siRNA) inhibits the proliferation, migration, and invasion of TNBC cells. Despite the recent success of siRNA therapeutics targeting to the liver, there still remains a great challenge to deliver siRNAs to solid tumors. Here, we report a hybrid nanocomplex to co-deliver the IKBKE siRNA and cabazitaxel to TNBC to achieve an optimal antitumor effect. The nanocomplex is modified with hyaluronic acid to target CD44 on TNBC cells. The nanocomplex shows higher cellular uptake and better tumor penetration of the encapsulated cargos. The nanocomplex also exhibits high tumor accumulation and antitumor activity in an orthotopic TNBC mouse model. Encapsulation of cabazitaxel in the nanocomplex enhances the activity of the IKBKE siRNA. The hybrid nanocomplex provides a novel and versatile platform for combination therapies using siRNAs and chemotherapy.

Targeting Altered Energy Metabolism in Colorectal Cancer: Oncogenic Reprogramming, the Central Role of the TCA Cycle and Therapeutic Opportunities

Colorectal cancer (CRC) is among the most frequent cancer entities worldwide. Multiple factors are causally associated with CRC development, such as genetic and epigenetic alterations, inflammatory bowel disease, lifestyle and dietary factors. During malignant transformation, the cellular energy metabolism is reprogrammed in order to promote cancer cell growth and proliferation. In this review, we first describe the main alterations of the energy metabolism found in CRC, revealing the critical impact of oncogenic signaling and driver mutations in key metabolic enzymes. Then, the central role of mitochondria and the tricarboxylic acid (TCA) cycle in this process is highlighted, also considering the metabolic crosstalk between tumor and stromal cells in the tumor microenvironment. The identified cancer-specific metabolic transformations provided new therapeutic targets for the development of small molecule inhibitors. Promising agents are in clinical trials and are directed against enzymes of the TCA cycle, including isocitrate dehydrogenase, pyruvate dehydrogenase kinase, pyruvate dehydrogenase complex (PDC) and α-ketoglutarate dehydrogenase (KGDH). Finally, we focus on the α-lipoic acid derivative CPI-613, an inhibitor of both PDC and KGDH, and delineate its anti-tumor effects for targeted therapy.

Redox Homeostasis and Metabolism in Cancer: A Complex Mechanism and Potential Targeted Therapeutics

Reactive Oxygen Species or "ROS" encompass several molecules derived from oxygen that can oxidize other molecules and subsequently transition rapidly between species. The key roles of ROS in biological processes are cell signaling, biosynthetic processes, and host defense. In cancer cells, increased ROS production and oxidative stress are instigated by carcinogens, oncogenic mutations, and importantly, metabolic reprograming of the rapidly proliferating cancer cells. Increased ROS production activates myriad downstream survival pathways that further cancer progression and metastasis. In this review, we highlight the relation between ROS, the metabolic programing of cancer, and stromal and immune cells with emphasis on and the transcription machinery involved in redox homeostasis, metabolic programing and malignant phenotype. We also shed light on the therapeutic targeting of metabolic pathways generating ROS as we investigate: Orlistat, Biguandes, AICAR, 2 Deoxyglucose, CPI-613, and Etomoxir.

Potential drug delivery nanosystems for improving tumor penetration

Nanosystems, as one of the most important drug delivery systems, play a crucial rule in tumor therapy. However, the deep tumor penetration is retarded by the tumor physiological factors and nanomedicine properties. In this review, we firstly elaborate the factors which impact tumor penetration, including the tumor physiological factors and nanomedicine properties. Then, the latest and potential drug delivery nanosystems for improving tumor penetration are summarized and analyzed in detail. Moreover, recent combination therapies for improving penetration are described to enhance penetration. Finally, we summarize the typical clinical therapies of potential drug delivery nanosystems.