Terminating the criminal collaboration in pancreatic cancer: Nanoparticle-based synergistic therapy for overcoming fibroblast-induced drug resistance

Cancer-associated fibroblasts, tumor and radiotherapy: interactions in the tumor micro-environment

Cancer-associated fibroblasts (CAFs) represent a group of genotypically non-malignant stromal cells in the tumor micro-environment (TME) of solid tumors that encompasses up to 80% of the tumor volume. Even though the phenotypic diversity and plasticity of CAFs complicates research, it is well-established that CAFs can affect many aspects of tumor progression, including growth, invasion and therapy resistance. Although anti-tumorigenic properties of CAFs have been reported, the majority of research demonstrates a pro-tumorigenic role for CAFs via (in)direct signaling to cancer cells, immunomodulation and extracellular matrix (ECM) remodeling. Following harsh therapeutic approaches such as radio- and/or chemotherapy, CAFs do not die but rather become senescent. Upon conversion towards senescence, many pro-tumorigenic characteristics of CAFs are preserved or even amplified. Senescent CAFs continue to promote tumor cell therapy resistance, modulate the ECM, stimulate epithelial-to-mesenchymal transition (EMT) and induce immunosuppression. Consequently, CAFs play a significant role in tumor cell survival, relapse and potentially malignant transformation of surviving cancer cells following therapy. Modulating CAF functioning in the TME therefore is a critical area of research. Proposed strategies to enhance therapeutic efficacy include reverting senescent CAFs towards a quiescent phenotype or selectively targeting (non-)senescent CAFs. In this review, we discuss CAF functioning in the TME before and during therapy, with a strong focus on radiotherapy. In the future, CAF functioning in the therapeutic TME should be taken into account when designing treatment plans and new therapeutic approaches.

Engineered PLGA Core-Lipid Shell Hybrid Nanocarriers Improve the Efficacy and Safety of Irinotecan to Combat Colon Cancer

Poly(lactide-co-glycolide) (PLGA) is a biocompatible and biodegradable copolymer that has gained high acceptance in biomedical applications. In the present study, PLGA (Mw = 13,900) was synthesized by ring-opening polymerization in the presence of a biocompatible zinc-proline initiator through a green route. Irinotecan (Ir) loaded with efficient PLGA core-lipid shell hybrid nanocarriers (lipomers, LPs) were formulated with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino (polyethylene glycol)-2000] (DSPE-PEG-2000), using soya lecithin, by a nanoprecipitation method, and the fabricated LPs were designated as P-DSPE-Ir and P-DSPE-PEG-Ir, respectively. The formulated LPs were further validated for their physicochemical properties and biological potential for colon cancer application. The potential delivery of a poorly water-soluble chemotherapeutic drug (Ir) was studied for the treatment of colon cancer. LPs were successfully prepared, providing controlled size (80-120 nm) and surface charge (∼ -35 mV), and the sustained release properties and cytotoxicity against CT-26 colon cancer cells were studied. The in vivo biodistribution and tumor site retention in CT-26 xenograft tumor-bearing Balb/C mice showed promising results for tumor uptake and retention for a prolonged time period. Unlike P-DSPE-Ir, the P-DSPE-PEG-Ir LP exhibited significant tumor growth delay as compared to untreated and blank formulation-treated groups in CT-26 (subcutaneous tumor model) after 4 treatments of 10 mg irinotecan/kg dose. The biocompatibility and safety of the LPs were confirmed by an acute toxicity study of the optimized formulation. Overall, this proof-of-concept study demonstrates that the PLGA-based LPs improve the efficacy and bioavailability and decrease neutropenia of Ir to combat colon cancer.

Nanoparticle-Mediated Drug Delivery Systems for Precision Targeting in Oncology

Nanotechnology has emerged as a transformative force in oncology, facilitating advancements in site-specific cancer therapy and personalized oncomedicine. The development of nanomedicines explicitly targeted to cancer cells represents a pivotal breakthrough, allowing the development of precise interventions. These cancer-cell-targeted nanomedicines operate within the intricate milieu of the tumour microenvironment, further enhancing their therapeutic efficacy. This comprehensive review provides a contemporary perspective on precision cancer medicine and underscores the critical role of nanotechnology in advancing site-specific cancer therapy and personalized oncomedicine. It explores the categorization of nanoparticle types, distinguishing between organic and inorganic variants, and examines their significance in the targeted delivery of anticancer drugs. Current insights into the strategies for developing actively targeted nanomedicines across various cancer types are also provided, thus addressing relevant challenges associated with drug delivery barriers. Promising future directions in personalized cancer nanomedicine approaches are delivered, emphasising the imperative for continued optimization of nanocarriers in precision cancer medicine. The discussion underscores translational research's need to enhance cancer patients' outcomes by refining nanocarrier technologies in nanotechnology-driven, site-specific cancer therapy.

The Application of Nanoparticles Targeting Cancer-Associated Fibroblasts

Cancer-associated fibroblasts (CAF) are the most abundant stromal cells in the tumor microenvironment (TME), especially in solid tumors. It has been confirmed that it can not only interact with tumor cells to promote cancer progression and metastasis, but also affect the infiltration and function of immune cells to induce chemotherapy and immunotherapy resistance. So, targeting CAF has been considered an important method in cancer treatment. The rapid development of nanotechnology provides a good perspective to improve the efficiency of targeting CAF. At present, more and more researches have focused on the application of nanoparticles (NPs) in targeting CAF. These studies explored the effects of different types of NPs on CAF and the multifunctional nanomedicines that can eliminate CAF are able to enhance the EPR effect which facilitate the anti-tumor effect of themselves. There also exist amounts of studies focusing on using NPs to inhibit the activation and function of CAF to improve the therapeutic efficacy. The application of NPs targeting CAF needs to be based on an understanding of CAF biology. Therefore, in this review, we first summarized the latest progress of CAF biology, then discussed the types of CAF-targeting NPs and the main strategies in the current. The aim is to elucidate the application of NPs in targeting CAF and provide new insights for engineering nanomedicine to enhance immune response in cancer treatment.

Nano-Drug Delivery Systems Targeting CAFs: A Promising Treatment for Pancreatic Cancer

Currently, pancreatic cancer (PC) is one of the most lethal malignant tumors. PC is typically diagnosed at a late stage, exhibits a poor response to conventional treatment, and has a bleak prognosis. Unfortunately, PC's survival rate has not significantly improved since the 1960s. Cancer-associated fibroblasts (CAFs) are a key component of the pancreatic tumor microenvironment (TME). They play a vital role in maintaining the extracellular matrix and facilitating the intricate communication between cancer cells and infiltrated immune cells. Exploring therapeutic approaches targeting CAFs may reverse the current landscape of PC therapy. In recent years, nano-drug delivery systems have evolved rapidly and have been able to accurately target and precisely release drugs with little or no toxicity to the whole body. In this review, we will comprehensively discuss the origin, heterogeneity, potential targets, and recent advances in the nano-drug delivery system of CAFs in PC. We will also propose a novel integrated treatment regimen that utilizes a nano-drug delivery system to target CAFs in PC, combined with radiotherapy and immunotherapy. Additionally, we will address the challenges that this regimen currently faces.

Signalling in pancreatic cancer: from pathways to therapy

Pancreatic cancer (PC) is a common malignant tumour in the digestive system. Due to the lack of sensitive diagnostic markers, strong metastasis ability, and resistance to anti-cancer drugs, the prognosis of PC is inferior. In the past decades, increasing evidence has indicated that the development of PC is closely related to various signalling pathways. With the exploration of RAS-driven, epidermal growth factor receptor, Hedgehog, NF-κB, TGF-β, and NOTCH signalling pathways, breakthroughs have been made to explore the mechanism of pancreatic carcinogenesis, as well as the novel therapies. In this review, we discussed the signalling pathways involved in PC and summarised current targeted agents in the treatment of PC. Furthermore, opportunities and challenges in the exploration of potential therapies targeting signalling pathways were also highlighted.

Nano-calcipotriol as a potent anti-hepatic fibrosis agent

Calcipotriol (CAL) has been widely studied as a fibrosis inhibitor and used to treat plaque psoriasis via transdermal administration. The clinical application of CAL to treat liver fibrosis is bottlenecked by its unsatisfactory pharmacokinetics, biodistribution, and side effects, such as hypercalcemia in patients. The exploration of CAL as a safe and effective antifibrotic agent remains a major challenge. Therefore, we rationally designed and synthesized a self-assembled drug nanoparticle encapsulating CAL in its internal hydrophobic core for systematic injection (termed NPs/CAL) and further investigated the beneficial effect of the nanomaterial on liver fibrosis. C57BL/6 mice were used as the animal model, and human hepatic stellate cell line LX-2 was used as the cellular model of hepatic fibrogenesis. Immunofluorescence staining, flow cytometry, western blotting, immunohistochemical staining, and in vitro imaging were used for evaluating the efficacy of NPs/CAL treatment. We found NPs/CAL can be quickly internalized in vitro, thus potently deactivating LX-2 cells. In addition, NPs/CAL improved blood circulation and the accumulation of CAL in liver tissue. Importantly, NPs/CAL strongly contributed to the remission of liver fibrosis without inducing hypercalcemia. Overall, our work identifies a promising paradigm for the development of nanomaterial-based agents for liver fibrosis therapy.

Nanomedicine and epigenetics: New alliances to increase the odds in pancreatic cancer survival

Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest cancers worldwide, primarily due to its robust desmoplastic stroma and immunosuppressive tumor microenvironment (TME), which facilitate tumor progression and metastasis. In addition, fibrous tissue leads to sparse vasculature, high interstitial fluid pressure, and hypoxia, thereby hindering effective systemic drug delivery and immune cell infiltration. Thus, remodeling the TME to enhance tumor perfusion, increase drug retention, and reverse immunosuppression has become a key therapeutic strategy. In recent years, targeting epigenetic pathways has emerged as a promising approach to overcome tumor immunosuppression and cancer progression. Moreover, the progress in nanotechnology has provided new opportunities for enhancing the efficacy of conventional and epigenetic drugs. Nano-based drug delivery systems (NDDSs) offer several advantages, including improved drug pharmacokinetics, enhanced tumor penetration, and reduced systemic toxicity. Smart NDDSs enable precise targeting of stromal components and augment the effectiveness of immunotherapy through multiple drug delivery options. This review offers an overview of the latest nano-based approaches developed to achieve superior therapeutic efficacy and overcome drug resistance. We specifically focus on the TME and epigenetic-targeted therapies in the context of PDAC, discussing the advantages and limitations of current strategies while highlighting promising new developments. By emphasizing the immense potential of NDDSs in improving therapeutic outcomes in PDAC, our review paves the way for future research in this rapidly evolving field.

Nanomedicine Strategies for Targeting Tumor Stroma

The tumor stroma, or the microenvironment surrounding solid tumors, can significantly impact the effectiveness of cancer therapies. The tumor microenvironment is characterized by high interstitial pressure, a consequence of leaky vasculature, and dense stroma created by excessive deposition of various macromolecules such as collagen, fibronectin, and hyaluronic acid (HA). In addition, non-cancerous cells such as cancer-associated fibroblasts (CAFs) and the extracellular matrix (ECM) itself can promote tumor growth. In recent years, there has been increased interest in combining standard cancer treatments with stromal-targeting strategies or stromal modulators to improve therapeutic outcomes. Furthermore, the use of nanomedicine, which can improve the delivery and retention of drugs in the tumor, has been proposed to target the stroma. This review focuses on how different stromal components contribute to tumor progression and impede chemotherapeutic delivery. Additionally, this review highlights recent advancements in nanomedicine-based stromal modulation and discusses potential future directions for developing more effective stroma-targeted cancer therapies.

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.

Integrated manganese (III)-doped nanosystem for optimizing photothermal ablation: Amplifying hyperthermia-induced STING pathway and enhancing antitumor immunity

Despite the great promise initially demonstrated by photothermal ablation (PTA) therapy, its inability to completely ablate large tumors is problematic, because this has been found to result in residual tumors at ablation margins and bring a relative high rate of subsequent recurrences and metastases. To address this issue, we herein report a smart photothermal nanosystem (PBM) based on FDA-approved Prussian blue (PB) nanoparticles, doped with Mn (III) to suppress the tumor debris left by incomplete ablation. Notably, our study demonstrated that PTA-induced hyperthermia plays a crucial role in initiating the cGAS-STING pathway by generating damaged cytosolic DNA. This PBM nanosystem, which consumes glutathione and continuously releases Mn(II), further amplifies the PTA-induced cGAS-STING pathway in CT26 colon and 4T1 breast tumor models. Moreover, treatment with PBM following PTA boosted the robust immune response in situ and extended to the whole body with a remarkable suppression effect on both local residual and distant tumors. This work, which improves the antitumor efficacy of nonablated areas utilizing hyperthermia-enhanced immune therapy, may therefore provide a promising adjuvant antitumor strategy for the issue of incomplete ablation. STATEMENT OF SIGNIFICANCE: This work discovered, for the first time, that photothermal ablation-induced hyperthermia plays a crucial role in initiating the cGAS-STING pathway. Taking advantage of this finding, we developed a smart photothermal material (PBM) tailored for incomplete tumor ablation. This integrated Mn(III)-doped nanosystem (PBM) demonstrated superior therapeutic benefits due to the thermal ablation process and immune enhancement. As the photothermal ablation-induced cGAS-STING pathway was triggered, the released Mn(III) consumes GSH while continuously transferred to Mn(II), which further amplified STING activation and facilitated a more robust antitumor immunity, thereby remarkably inhibiting both local residual and distant tumors in virtue of the biological changes under thermal ablation.

Cancer-associated fibroblasts: Origin, function, imaging, and therapeutic targeting

The tumor microenvironment (TME) is emerging as one of the primary barriers in cancer therapy. Cancer-associated fibroblasts (CAF) are a common inhabitant of the TME in several tumor types and play a critical role in tumor progression and drug resistance via different mechanisms such as desmoplasia, angiogenesis, immune modulation, and cancer metabolism. Due to their abundance and significance in pro-tumorigenic mechanisms, CAF are gaining attention as a diagnostic target as well as to improve the efficacy of cancer therapy by their modulation. In this review, we highlight existing imaging techniques that are used for the visualization of CAF and CAF-induced fibrosis and provide an overview of compounds that are known to modulate CAF activity. Subsequently, we also discuss CAF-targeted and CAF-modulating nanocarriers. Finally, our review addresses ongoing challenges and provides a glimpse into the prospects that can spearhead the transition of CAF-targeted therapies from opportunity to reality.

Recent nanotechnology advancements to treat multidrug-resistance pancreatic cancer: Pre-clinical and clinical overview

Pancreatic cancer (PC) remains one of the most lethal and incurable forms of cancer and has a poor prognosis. One of the significant therapeutic challenges in PC is multidrug resistance (MDR), a phenomenon in which cancer cells develop resistance toward administered therapy. Development of novel therapeutic platforms that could overcome MDR in PC is crucial for improving therapeutic outcomes. Nanotechnology is emerging as a promising tool to enhance drug efficacy and minimize off-target responses via passive and/or active targeting mechanisms. Over the past decade, tremendous efforts have been made to utilize nanocarriers capable of targeting PC cells while minimizing off-target effects. In this review article, we first give an overview of PC and the major molecular mechanisms of MDR, and then we discuss recent advancements in the development of nanocarriers used to overcome PC drug resistance. In doing so, we explore the developmental stages of this research in both pre-clinical and clinical settings. Lastly, we discuss current challenges and gaps in the literature as well as potential future directions in the field.

Targeting hedgehog signaling in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains a leading cause of cancer related death. The urgent need for effective therapies is highlighted by the lack of adequate targeting. In PDAC, hedgehog (Hh) signaling is known to be aberrantly activated, which prompted the pathway as a possible target for effective treatment for PDAC patients. Unfortunately, specific targeting of upstream molecules within the Hh signaling pathway failed to bring clinical benefit. This led to the ongoing debate on Hh targeting as a therapeutic treatment for PDAC patients. Additionally, concurrent non-canonical activation routes also result in translocation of Gli transcription factors into the nucleus. Therefore, different downstream targets of the Hh signaling pathway were identified and evaluated in preclinical and clinical research. In this review we summarize the variety of Hh signaling antagonists in different preclinical models of PDAC. Furthermore, we discuss published and ongoing clinical trials that evaluated Hh antagonists and point out the current hurdles and future perspectives in the light of redesigning Hh-targeting therapies for the treatment of PDAC patients.

Pancreatic tumor eradication via selective Pin1 inhibition in cancer-associated fibroblasts and T lymphocytes engagement

Cancer associated fibroblasts (CAFs) support tumors via multiple mechanisms, including maintaining the immunosuppressive tumor microenvironment and limiting infiltration of immune cells. The prolyl isomerase Pin1, whose overexpression in CAFs has not been fully profiled yet, plays critical roles in tumor initiation and progression. To decipher effects of selective Pin1 inhibition in CAFs on pancreatic cancer, here we formulate a DNA-barcoded micellular system (DMS) encapsulating the Pin1 inhibitor AG17724. DMS functionalized with CAF-targeting anti-FAP-α antibodies (antiCAFs-DMS) can selectively inhibit Pin1 in CAFs, leading to efficacious but transient tumor growth inhibition. We further integrate DNA aptamers (AptT), which can engage CD8+ T lymphocytes, to obtain a bispecific antiCAFs-DMS-AptT system. AntiCAFs-DMS-AptT inhibits tumor growth in subcutaneous and orthotopic pancreatic cancer models.

Pharmacological inhibition of the prolyl isomerase PIN1, highly expressed in cancer cells and cancer associated fibroblasts (CAF), has been proposed for cancer therapy. Here the authors report the design of a DNA-barcoded micellular system functionalized with antibodies targeting CAFs and a T cell recruiting aptamer to deliver the PIN1 inhibitor AG17724, showing antitumor response in preclinical models of pancreatic cancer.

Targeting Tumour-Associated Fibroblasts in Cancers

Tumours develop within complex tissue environments consisting of aberrant oncogenic cancer cells, diverse innate and adaptive immune cells, along with structural stromal cells, extracellular matrix and vascular networks, and many other cellular and non-cellular soluble constituents. Understanding the heterogeneity and the complex interplay between these cells remains a key barrier in treating tumours and cancers. The immune status of the pre-tumour and tumour milieu can dictate if the tumour microenvironment (TME) supports either a pro-malignancy or an anti-malignancy phenotype. Identification of the factors and cell types that regulate the dysfunction of the TME is crucial in order to understand and modulate the immune status of tumours. Among these cell types, tumour-associated fibroblasts are emerging as a major component of the TME that is often correlated with poor prognosis and therapy resistance, including immunotherapies. Thus, a deeper understanding of the complex roles of tumour-associated fibroblasts in regulating tumour immunity and cancer therapy could provide new insight into targeting the TME in various human cancers. In this review, we summarize recent studies investigating the role of immune and key stromal cells in regulating the immune status of the TME and discuss the therapeutic potential of targeting stromal cells, especially tumour-associated fibroblasts, within the TME as an adjuvant therapy to sensitize immunosuppressive tumours and prevent cancer progression, chemo-resistance and metastasis.

Enzymatic drug release cascade from polymeric prodrug nanoassemblies enables targeted chemotherapy

Cancer drug delivery systems often suffer from premature drug leakage during transportation and/or inefficient drug release within cancer cells. We present here a polymeric prodrug nanoassembly that addresses these problems simultaneously. This nanoassembly comprises a polymeric prodrug with novel trivalent phenylboronate moieties for drug conjugation via ether linkages, as well as β-lapachone (Lapa). While the ether linkage enables nearly no drug release under physiological conditions, the Lapa molecules can induce the reactive oxygen species (ROS) burst specifically in cancer cells via NAD(P)H: quinone oxidoreductase-1 catalysis, which triggers the cleavage of the ether bonds and thus cascade amplification drug release in cancer cells. As a result, the nanoassemblies exhibit much higher cytotoxicity against cancer cells than normal cells, and also increased therapeutic efficacy and reduced side effects compared to the clinically used irinotecan. We anticipate that this strategy can be applied to other drug delivery platforms to enable more precise drug release.

Size-tuneable and immunocompatible polymer nanocarriers for drug delivery in pancreatic cancer

Nanocarriers have emerged as one of the most promising approaches for drug delivery. Although several nanomaterials have been approved for clinical use, the translation from lab to clinic remains challenging. However, by implementing rational design strategies and using relevant models for their validation, these challenges are being addressed. This work describes the design of novel immunocompatible polymer nanocarriers made of melanin-mimetic polydopamine and Pluronic F127 units. The nanocarrier preparation was conducted under mild conditions, using a highly reproducible method that was tuned to provide a range of particle sizes (<100 nm) without changing the composition of the carrier. A set of in vitro studies were conducted to provide a comprehensive assessment of the effect of carrier size (40, 60 and 100 nm) on immunocompatibility, viability and uptake into different pancreatic cancer cells varying in morphological and phenotypic characteristics. Pancreatic cancer is characterised by poor treatment efficacy and no improvement in patient survival in the last 40 years due to the complex biology of the solid tumour. High intra- and inter-tumoral heterogeneity and a dense tumour microenvironment limit diffusion and therapeutic response. The Pluronic-polydopamine nanocarriers were employed for the delivery of irinotecan active metabolite SN38, which is used in the treatment of pancreatic cancer. Increased antiproliferative effect was observed in all tested cell lines after administration of the drug encapsulated within the carrier, indicating the system's potential as a therapeutic agent for this hard-to-treat cancer.

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.

Tumor microenvironment and nanotherapeutics: intruding the tumor fort

Over recent years, advancements in nanomedicine have allowed new approaches to diagnose and treat tumors. Nano drug delivery systems exploit the enhanced permeability and retention (EPR) effect and enter the tumor tissue's interstitial space. However, tumor barriers play a crucial role, and cause inefficient EPR or the homing effect. Mounting evidence supports the hypothesis that the components of the tumor microenvironment, such as the extracellular matrix, and cellular and physiological components collectively or cooperatively hinder entry and distribution of drugs, and therefore, limit the theragnostic applications of cancer nanomedicine. This abnormal tumor microenvironment plays a pivotal role in cancer nanomedicine and was recently recognized as a promising target for improving nano-drug delivery and their therapeutic outcomes. Strategies like passive or active targeting, stimuli-triggered nanocarriers, and the modulation of immune components have shown promising results in achieving anticancer efficacy. The present review focuses on the tumor microenvironment and nanoparticle-based strategies (polymeric, inorganic and organic nanoparticles) for intruding the tumor barrier and improving therapeutic effects.

Prodrug polymeric micelles integrating cancer-associated fibroblasts deactivation and synergistic chemotherapy for gastric cancer

Background

The prognosis of patients with advanced gastric cancer (GC) remains unsatisfactory owing to distant metastasis and resistance to concurrent systemic therapy. Cancer-associated fibroblasts (CAFs), as essential participators in the tumor microenvironment (TME), play a vital role in tumor progression. Thus, CAFs-targeting therapy is appealing for remodeling TME and sensitizing GC to conventional systemic therapy.

Methods

Amphiphilic SN38 prodrug polymeric micelles (PSN38) and encapsulated the hydrophobic esterase-responsive prodrug of Triptolide (TPL), triptolide-naphthalene sulfonamide (TPL-nsa), were synthesized to form PSN38@TPL-nsa nanoparticles. Then, CAFs were isolated from fresh GC tissues and immortalized. TPL at low dose concentration was used to investigate its effect on CAFs and CAFs-induced GC cells proliferation and migration. The synergistic mechanism and antitumor efficiency of SN38 and TPL co-delivery nanoparticle were investigated both in vitro and in vivo.

Results

Fibroblast activation protein (FAP), a marker of CAFs, was highly expressed in GC tissues and indicated poorer prognosis. TPL significantly reduced CAFs activity and inhibited CAFs-induced proliferation, migration and chemotherapy resistance of GC cells. In addition, TPL sensitized GC cells to SN38 treatment through attenuated NF-κB activation in both CAFs and GC cells. PSN38@TPL-nsa treatment reduced the expression of collagen, FAP, and α-smooth muscle actin (α-SMA) in tumors. Potent inhibition of primary tumor growth and vigorous anti-metastasis effect were observed after systemic administration of PSN38@TPL-nsa to CAFs-rich peritoneal disseminated tumor and patient-derived xenograft (PDX) model of GC.

Conclusion

TPL suppressed CAFs activity and CAFs-induced cell proliferation, migration and chemotherapy resistance to SN38 of GC. CAFs-targeted TPL and SN38 co-delivery nanoparticles exhibited potent efficacy of antitumor and reshaping TME, which was a promising strategy to treat advanced GC.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01127-5.

Prodrug nanoparticles rationally integrating stroma modification and chemotherapy to treat metastatic pancreatic cancer

Accumulating evidence suggests that stromal modifications improve chemotherapeutic outcomes in pancreatic ductal adenocarcinoma (PDAC). However, combination regimens of stroma-modifying agents and small-molecule cytotoxic drugs have achieved only limited improvements in the clinic, probably due to unsatisfactory pharmacokinetic profiles and restricted drug distribution in tumors. Here, we developed self-assembled prodrug nanoparticles integrating a stromal reprogramming inducer, calcipotriol (CAL), and a potent chemotherapeutic agent, 7-Ethyl-10-hydroxycamptothecin (SN38), to treat PDAC. While SN38 is conjugated to the block polymer backbone, CAL is loaded into the inner hydrophobic space during polymer self-assembly into nanoparticles. To achieve an efficient drug co-package, a planar and hydrophobic cholesterol domain was introduced to stabilize the hydrophobic CAL. Notably, the blood circulation time of CAL significantly improved as CAL|SN38 nanoparticle (CAL|SN38 NP). In addition, CAL|SN38 NP treatment significantly decreased the expression of N-cadherin, collagen, and fibronectin in tumors, which play critical roles in PDAC metastasis. Potent inhibition of primary tumor growth and vigorous anti-metastasis effects were observed after systemic administration of CAL|SN38 NP to stroma-rich PDAC orthotopic tumor-bearing mice. These findings provide a promising paradigm for developing tailor-made nanoparticles with potent stroma-modification capability to combat metastatic cancer.

A tumor microenvironment responsive nanosystem for chemodynamic/chemical synergistic theranostics of colorectal cancer

Rationale: The synergism of new modalities alongside chemodynamic therapy into common chemotherapy has shown promising potential in clinical applications. This paper reports a tumor microenvironment-responsive nanosystem for chemodynamic/chemical synergistic therapy and magnetic resonance imaging (MRI). Methods: The biodegradable nanosystem is synthesized using a surface-modified chain transfer agent for surface-initiated living radical polymerization of the chemotherapeutic drug. Results: In this nanosystem, named CAMNSN@PSN38, the cycling time and solubility of the chemotherapeutic drug are improved. The nanoparticles delivered to tumor tissues gradually release the chemotherapeutic drug and Mn2+ through glutathione (GSH)-triggered biodegradation in the tumor microenvironment. SN38, the released chemotherapeutic drug, not only shows excellent chemical therapy effects but also improves the generation of H2O2. Furthermore, with the Fenton-like agent Mn2+, the generation of reactive oxygen species (ROS) is improved markedly. Finally, CAMNSN@PSN38 shows excellent inhibition of tumor growth in three colorectal cancer tumor models, with an improved accumulation of ROS and controlled release of SN38. Conclusions: The CAMNSN@PSN38-mediated chemodynamic/chemical synergistic therapy provides a promising paradigm for the treatment and MRI-guided therapy of colorectal cancer.

The Role of the Hedgehog Pathway in Chemoresistance of Gastrointestinal Cancers

The hedgehog pathway, which plays a significant role in embryonic development and stem cell regulation, is activated in gastrointestinal cancers. Chemotherapy is widely used in cancer treatment. However, chemoresistance becomes a substantial obstacle in cancer therapy. This review focuses on the recent advances in the hedgehog pathway's roles in drug resistance of gastrointestinal cancers and the novel drugs and strategies targeting hedgehog signaling.

Gene silencing delivery systems for the treatment of pancreatic cancer: Where and what to target next?

Despite intensive research efforts and development of numerous new anticancer drugs and treatment strategies over the past decades, there has been only very limited improvement in overall patient survival and in effective treatment options for pancreatic cancer. Current chemotherapy improves survival in terms of months and death rates in pancreatic cancer patients are almost equivalent to incidence rates. It is imperative to develop new therapeutic approaches. Among them, gene silencing shows promise of effectiveness in both tumor cells and stromal cells by inhibiting tumor-promoting genes. This review summarizes potential targets for gene silencing in both pancreatic cancer cells and abundant stromal cells focusing on non-viral delivery systems for small RNAs and discusses the potential immunological implications. The review concludes with the importance of multifactorial therapy of pancreatic cancer.

Co-delivery Systems of Multiple Drugs Using Nanotechnology for Future Cancer Therapy

Cancer treatments have improved significantly during the last decade but are not yet satisfactory. Combination therapy is often administered to improve efficacy and safety. Drug delivery systems can also improve efficacy and safety. To control the spatiotemporal distribution of drugs, nanotechnology involving liposomes, solid lipid nanoparticles, and polymeric micelles has been developed. Co-delivery systems of multiple drugs are a promising approach to combat cancer. Synergistic effects and reduced side effects are expected from the use of co-delivery systems. In this review, we summarize various co-delivery systems for multiple drugs, including small-molecule drugs, nucleic acids, genes, and proteins. Co-delivery of drugs with different properties is relatively difficult, but some researchers have succeeded in developing such co-delivery systems. Environment-responsive carrier designs can control the release of cargos. Although their preparation is more complicated than that of mono-delivery systems, co-delivery systems can simplify clinical procedures and improve patient QOL.

Regulation of tumor microenvironment for pancreatic cancer therapy

Pancreatic cancer (PC) is one kind of the most lethal malignancies worldwide, owing to its insidious symptoms, early metastases, and negative responses to current therapies. With an increasing understanding of pathology, the tumor microenvironment (TME) plays a significant role in ineffective treatment and poor prognosis of PC. Thus, a growing number of studies have focused on whether components of the TME could be effective targets for PC therapy. Biomaterials have been widely applied in cancer therapy, and numerous organic or inorganic biomaterials for TME regulation have been developed to inhibit the growth and metastasis of PC, as well as reverse therapeutic resistance. In this review, we discuss various biomaterials utilized to treat PC based on different components of the TME, including, but not limited to, extracellular matrix (ECM), abnormal tumor vascularization, and tumor-associated immune cells, as well as other unconventional therapeutic strategies. Besides, the perspectives on the underlying future of theranostic nanomedicines for PC therapy are also presented.

Regulation of Hedgehog Signaling by miRNAs and Nanoformulations: A Possible Therapeutic Solution for Colorectal Cancer

Hedgehog (Hh) signaling aberrations trigger differentiation and proliferation in colorectal cancer (CRC). However, the current approaches which inhibit this vital cellular pathway provoke some side effects. Therefore, it is necessary to look for new therapeutic options. MicroRNAs are small molecules that modulate expression of the target genes and can be utilized as a potential therapeutic option for CRC. On the other hand, nanoformulations have been implemented in the treatment of plethora of diseases. Owing to their excessive bioavailability, limited cytotoxicity and high specificity, nanoparticles may be considered as an alternative drug delivery platform for the Hh signaling mediated CRC. This article reviews the Hh signaling and its involvement in CRC with focus on miRNAs, nanoformulations as potential diagnostic/prognostic and therapeutics for CRC.

Therapeutic resistance of pancreatic cancer: Roadmap to its reversal

Pancreatic cancer is a lethal disease with limited opportunity for resectable surgery as the first choice for cure due to its late diagnosis and early metastasis. The desmoplastic stroma and cellular genetic or epigenetic alterations of pancreatic cancer impose physical and biological barriers to effective therapies, including chemotherapy, radiotherapy, targeted therapy, and immunotherapy. Here, we review the current therapeutic options for pancreatic cancer, and underlying mechanisms and potential reversal of therapeutic resistance, a hallmark of this deadly disease.

Nanoparticle-enhanced chemo-immunotherapy to trigger robust antitumor immunity

Mounting evidence suggests that immunotherapies are a promising new class of anticancer therapies. However, the immunosuppressive tumor microenvironment (TME), poor immunogenicity, and off-target toxicity hinder the broader implementation of immunotherapies. Here, we describe a novel strategy combining chemotherapy and immunotherapy to modulate the TME by systemically and concurrently delivering the chemotherapeutic agent SN38 (7-ethyl-10-hydroxycamptothecin) and the STING agonist DMXAA (5,6-dimethylxanthenone-4-acetic acid) into tumors using triblock copolymer nanoparticles, named PS3D1@DMXAA, which enhances antigen cross-presentation and induces the conversion of the immunosuppressive TME to immunogenic TME through the newly found synergistic function between SN38 and STING activation. PS3D1@DMXAA thus shows potent therapeutic efficacy in three mice tumor models and elicits remarkable therapeutic benefit when combined with anti-PD-1 therapy. Our engineered nanosystem offers a rational design of an effective immunotherapy combination regimen to convert uninflamed "cold" tumors into "hot" tumors, addressing the major challenges immunotherapies faced.

Nanoparticles for Manipulation of the Developmental Wnt, Hedgehog, and Notch Signaling Pathways in Cancer

The Wnt, Hedgehog, and Notch signaling pathways play a crucial role in early development and the maintenance of adult tissues. When dysregulated, these developmental signaling pathways can drive the formation and progression of cancer by facilitating cell survival, proliferation, and stem-like behavior. While this makes these pathways promising targets for therapeutic intervention, their pharmacological inhibition has been challenging due to the substantial complexity that exists within each pathway and the complicated crosstalk that occurs between the pathways. Recently, several small molecule inhibitors, ribonucleic acid (RNA) molecules, and antagonistic antibodies have been developed that can suppress these signaling pathways in vitro, but many of them face systemic delivery challenges. Nanoparticle-based delivery vehicles can overcome these challenges to enhance the performance and anti-cancer effects of these therapeutic molecules. This review summarizes the mechanisms by which the Wnt, Hedgehog, and Notch signaling pathways contribute to cancer growth, and discusses various nanoparticle formulations that have been developed to deliver small molecules, RNAs, and antibodies to cancer cells to inhibit these signaling pathways and halt tumor progression. This review also outlines some of the challenges that these nanocarriers must overcome to achieve therapeutic efficacy and clinical translation.

MiR-199a-modified exosomes from adipose tissue-derived mesenchymal stem cells improve hepatocellular carcinoma chemosensitivity through mTOR pathway

Background

MiR-199a-3p (miR-199a) can enhance the chemosensitivity of hepatocellular carcinoma (HCC). Because of the easy degradation of miRNA by direct infusion, effective vehicle-mediated delivery of miR-199a may represent a new strategy for improving HCC chemotherapy. Considering mesenchymal stem cell (MSC)-derived exosomes as promising natural nanovectors for drug and molecule delivery, we aimed to determine whether exosomes from adipose tissue-derived MSCs (AMSCs) could be used to deliver miR-199a and improve HCC chemosensitivity.

Methods

MiR-199a-modified AMSCs (AMSC-199a) were constructed by miR-199a lentivirus infection and puromycin selection. MiR-199-modified exosomes (AMSC-Exo-199a) were isolated from the supernatant of AMSC-199a and were assessed by transmission electron microscopy, nanoparticle tracking analysis, and flow cytometry analysis. The expression levels of miR-199a in HCC samples, AMSCs, exosomes, and HCC cells were quantified by real-time PCR. The effects of AMSC-Exo-199a on HCC chemosensitivity were determined by cell proliferation and apoptosis assays and by i.v. injection into orthotopic HCC mouse models with doxorubicin treatment. MTOR, p-4EBP1 and p-70S6K levels in HCC cells and tissues were quantified by Western blot.

Results

AMSC-Exo-199a had the classic characteristics of exosomes and could effectively mediate miR-199a delivery to HCC cells. Additionally, AMSC-Exo-199a significantly sensitized HCC cells to doxorubicin by targeting mTOR and subsequently inhibiting the mTOR pathway. Moreover, i.v.-injected AMSC-Exo-199a could distribute to tumor tissue and markedly increased the effect of Dox against HCC in vivo.

Conclusions

AMSC-Exo-199a can be an effective vehicle for miR-199a delivery, and they effectively sensitized HCC to chemotherapeutic agents by targeting mTOR pathway. AMSC-Exo-199a administration may provide a new strategy for improving HCC chemosensitivity.

Epidermal Growth Factor Receptor and Its Role in Pancreatic Cancer Treatment Mediated by Nanoparticles

Pancreatic adenocarcinoma (PDAC) is a disease with a high incidence and a dreary prognosis. Its lack of symptomatology and late diagnosis contribute to the dearth and inefficiency of therapeutic schemes. Studies show that overexpressed epidermal growth factor receptor (EGFR) is a common occurrence, linking this to the progression of pancreatic cancer, although the association between its expression and the survival rate is rather controversial. EGFR-targeted therapy has not shown the results expected, leaving at hand more questions than answers; clearly, there is a need for a better understanding of the molecular pathways involved. Nanoparticles have been used in trying to improve the efficacy of antitumor treatment; thus, using EGFR's ligand, EGF, for nanoconjugation, showed promising results in increasing the cellular uptake mechanisms and apoptosis of the targeted cells.

Reversing activity of cancer associated fibroblast for staged glycolipid micelles against internal breast tumor cells

Rationale: Nano-carrier based combinational therapies for tumor cells hold great potential to improve the outcomes of patients. However, cancer associated fibroblasts (CAFs) in desmoplastic tumors and the derived pathological tumor stroma severely impede the access and sensitibity of tumor cells to antitumor therapies.

Methods: Glycolipid-based polymeric micelles (GLPM) were developed to encapsulate an angiotensin II receptor I inhibitor (telmisartan, Tel) and a cytotoxic drug (doxorubicin, DOX) respectively, which could exert combinational antitumor efficacy by reprogramming tumor microenvironment to expose the vulnerability of internal tumor cells.

Results: As demonstrated, α-SMA positive CAFs significantly decreased after the pre-administration of GLPM/Tel in vitro, which accordingly inhibited the secretion of the CAFs derived stroma. The tumor vessels were further decompressed as a result of the alleviated solid stress inside the tumor masses, which promoted more intratumoral drug delivery and penetration. Ultimately, staged administration of the combined GLPM/Tel and GLPM/DOX at the screened molar ratio not only inhibited the stroma continuously, but also achieved a synergistic antitumor effect through the apoptosis-related peroxisome proliferator-activated receptor-gamma (PPAR-γ) pathway.

Conclusion: In summary, the strategy of suppressing tumor stroma for subsequent combinational therapies against internal breast tumor cells could provide avenues for management of intractable desmoplastic tumors.

Nanoparticle Interactions with the Tumor Microenvironment

Compared to normal tissues, the tumor microenvironment (TME) has a number of aberrant characteristics including hypoxia, acidosis, and vascular abnormalities. Many researchers have sought to exploit these anomalous features of the TME to develop anticancer therapies, and several nanoparticle-based cancer therapeutics have resulted. In this Review, we discuss the composition and pathophysiology of the TME, introduce nanoparticles (NPs) used in cancer therapy, and address the interaction between the TME and NPs. Finally, we outline both the potential problems that affect TME-based nanotherapy and potential strategies to overcome these challenges.

The role of collagen in cancer: from bench to bedside

Collagen is the major component of the tumor microenvironment and participates in cancer fibrosis. Collagen biosynthesis can be regulated by cancer cells through mutated genes, transcription factors, signaling pathways and receptors; furthermore, collagen can influence tumor cell behavior through integrins, discoidin domain receptors, tyrosine kinase receptors, and some signaling pathways. Exosomes and microRNAs are closely associated with collagen in cancer. Hypoxia, which is common in collagen-rich conditions, intensifies cancer progression, and other substances in the extracellular matrix, such as fibronectin, hyaluronic acid, laminin, and matrix metalloproteinases, interact with collagen to influence cancer cell activity. Macrophages, lymphocytes, and fibroblasts play a role with collagen in cancer immunity and progression. Microscopic changes in collagen content within cancer cells and matrix cells and in other molecules ultimately contribute to the mutual feedback loop that influences prognosis, recurrence, and resistance in cancer. Nanoparticles, nanoplatforms, and nanoenzymes exhibit the expected gratifying properties. The pathophysiological functions of collagen in diverse cancers illustrate the dual roles of collagen and provide promising therapeutic options that can be readily translated from bench to bedside. The emerging understanding of the structural properties and functions of collagen in cancer will guide the development of new strategies for anticancer therapy.

Threatening cancer with nanoparticle aided combination oncotherapy

Employing combination therapy has become obligatory in cancer cases exhibiting high tumor load, chemoresistant tumor population, and advanced disease stages. Realization of this fact has now led many of the combination oncotherapies to become an integral part of anticancer regimens. Combination oncotherapy may encompass a combination of anticancer agents belonging to a similar therapeutic category or that of different therapeutic categories (e.g. chemotherapy + gene therapy). Differences in the physicochemical properties, pharmacokinetics and biodistribution pattern of different payloads are the major constraints that are faced by combination chemotherapy. Concordant efforts in the field of nanotechnology and oncology have emerged with several approaches to solve the major issues encountered by combination therapy. Unique colloidal behaviors of various types of nanoparticles and differential targeting strategies have accorded an unprecedented ability to optimize combination oncotherapeutic delivery. Nanocarrier based delivery of the various types of payloads such as chemotherapeutic agents and other anticancer therapeutics such as small interfering ribonucleic acid (siRNA), chemosensitizers, radiosensitizers, and antiangiogenic agents have been addressed in the present review. Various nano-delivery systems like liposomes, polymeric nanoparticles, polymerosomes, dendrimers, micelles, lipid based nanoparticles, prodrug based nanocarriers, polymer-drug conjugates, polymer-lipid hybrid nanoparticles, carbon nanotubes, nanosponges, supramolecular nanocarriers and inorganic nanoparticles (gold nanoparticles, silver nanoparticles, magnetic nanoparticles and mesoporous silica based nanoparticles) that have been extensively explored for the formulation of multidrug delivery is an imperative part of discussion in the review. The present review features the outweighing benefits of combination therapy over mono-oncotherapy and discusses several existent nanoformulation strategies that facilitate a successful combination oncotherapy. Several obstacles that may impede in transforming nanotechnology-based combination oncotherapy from bench to bedside, and challenges associated therein have also been discussed in the present review.

Tumor-stromal crosstalk in pancreatic cancer and tissue fibrosis

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with high morbidity and mortality worldwide. To date, limited therapeutic achievements targeting cell proliferation and related mechanisms has led researchers to focus on the microenvironment where pancreatic cancers develop. The anomalous proliferation of stromal cells, such as pancreatic stellate cells, and an increased deposition of altered matrix proteins create an environment that facilitates tumor growth, metastasis and drug resistance. Here, we summarize our understanding of recent advances in research about the role of fibrosis in pancreatic cancer progression, with particular emphasize on the involvement of fibrotic machineries such as wound healing, extra cellular matrix degradation, and epithelial-to-mesenchymal transition. The precise influence of these mechanisms on the biological behaviors and growth of cancer cells has great impact on clinical therapy and therefore deserves more attention. We also discuss the role of various stromal components in conferring drug resistance to PDAC which further worsening the pessimistic disease prognosis. A more in depth understanding of cancer-stroma crosstalk within the tumor microenvironment and stroma based clinical and translational therapies may provide new therapeutic strategies for the prevention of pancreatic cancer progression.

A drug-repositioning screen for primary pancreatic ductal adenocarcinoma cells identifies 6-thioguanine as an effective therapeutic agent for TPMT-low cancer cells

Pancreatic cancer is one of the most difficult cancers to cure due to the lack of early diagnostic tools and effective therapeutic agents. In this study, we aimed to isolate new bioactive compounds that effectively kill pancreatic ductal adenocarcinoma (PDAC) cells, but not untransformed, human pancreatic ductal epithelial (HPDE) cells. To this end, we established four primary PDAC cell lines and screened 4141 compounds from four bioactive-compound libraries. Initial screening yielded 113 primary hit compounds that caused over a 50% viability reduction in all tested PDAC cells. Subsequent triplicate, dose-dependent analysis revealed three compounds with a tumor cell-specific cytotoxic effect. We found that these three compounds fall into a single category of thiopurine biogenesis. Among them, 6-thioguanine (6-TG) showed an IC₅₀ of 0.39-1.13 μm toward PDAC cells but had no effect on HPDE cells. We propose that this cancer selectivity is due to differences in thiopurine methyltransferase (TPMT) expression between normal and cancer cells. This enzyme is responsible for methylation of thiopurine, which reduces its cytotoxicity. We found that TPMT levels were lower in all four PDAC cell lines than in HPDE or Panc1 cells, and that knockdown of TPMT in HPDE or Panc1 cells sensitized them to 6-TG. Lastly, we used a patient-derived xenograft model to confirm that 6-TG has a significant antitumor effect in combination with gemcitabine. Overall, our study presents 6-TG as a strong candidate for use as a therapeutic agent against PDAC with low levels of TPMT.

New path to treating pancreatic cancer: TRAIL gene delivery targeting the fibroblast-enriched tumor microenvironment

Gene therapy has shown promise in antitumor strategies for advanced cancer. However, efficient and safe delivery of potent therapeutic gene expressing in specific tumor tissues remains elusive, especially when there exist stromal obstacles. Here we report a non-viral gene delivery approach targeting pancreatic stellate cells (PSCs) as the transfection host in the fibroblast-enriched tumor microenvironment of pancreatic cancer. Plasmid DNA (pDNA) encapsulated in branched polyethylenemine (BPEI) was found to selectively transfect PSCs rather than pancreatic cancer cells and other fibroblast cell lines. Mechanism investigations reveal that the highly expressed fibroblast growth factor receptors (FGFRs) in PSCs facilitated the cellular uptake of polyplexes in PSCs. This delivery platform carrying gene encoding of TNF-related apoptosis-inducing ligand (TRAIL) displayed effective by-stander effect and tumor cell-selective cytotoxicity. More importantly, the therapeutic efficacy was proved in a PSC-enriched orthotopic pancreatic tumor model. Thus, this gene delivery strategy smartly converts PSCs as the microenvironment obstacle for drug delivery into the producer and reservoir of selective tumor-killing proteins.

Tri-block polymer with interfacial layer formation ability and its use in maintaining supersaturated drug solution after dissolution of solid dispersions

Background

Maintaining a supersaturated drug solution after the dissolution of the solid dispersions of water insoluble drugs continues to be a great challenge and is important to the oral bioavailability enhancement of hardly soluble drugs.

Methods

Nimodipine solid dispersions were prepared by hot-melt extrusion and a special tri-block polymer was employed as a co-carrier. The solid dispersions were characterized by modulated differential scanning calorimetry, transmission electron microscopy, hydrogen-nuclear magnetic resonance and so on.

Results

The tri-block polymer was able to inhibit the formation of drug crystals after dissolution of the solid dispersions. Due to the unique interfacial layer formation ability of the tri-block polymer, a special drug loading micelle which encapsulated the compound and the hydrophobic fragments of the copolymers appeared in the release media. The tri-block polymer was composed of a hydrophilic part forming the shell of micelles, a hydrophobic part shaping the core of micelles, and a special intermediate hydrophilicity part constructing the interfacial layer of micelles.

Conclusion

The tri-block polymer was not only able to stabilize the supersaturated drug solution of solid dispersions to enhance the oral bioavailability of hardly soluble drugs, but is also a potential candidate to construct micelles for systemic administration, due to the good compatibility and organic solvents free micelle formation procedure.

Macrophages as an active tumour-targeting carrier of SN38-nanoparticles for cancer therapy

Taking advantage of their enhanced permeability and retention (EPR) effect, nanomedicines have been extensively studied for targeted drug delivery to tumour tissues. However, tumour heterogeneity restricts the EPR effect and drug penetration into tumours, and nanoformulations only generate a limited therapeutic improvement in clinical settings. Macrophages have the inherent ability of tumour homing, stealth in blood circulation, and phagocytosis of particles. In this study, we used peritoneal macrophages as carriers for the delivery of SN38 nanoparticles (SN38-NPs) for cancer treatment. SN38-NPs were internalised by macrophages without any obvious effect on viability and migration, and not only induced apoptosis of tumour cells in vitro, but also accumulated in tumour tissues in vivo. In addition, the macrophage-based delivery system for SN38-NPs showed improved therapeutic effect than an equivalent dose of CPT-11 in an A549 subcutaneous tumour model.

Nanotechnologies in Pancreatic Cancer Therapy

Pancreatic cancer has been classified as a cancer of unmet need. After diagnosis the patient prognosis is dismal with few surviving over 5 years. Treatment regimes are highly patient variable and often the patients are too sick to undergo surgical resection or chemotherapy. These chemotherapies are not effective often because patients are diagnosed at late stages and tumour metastasis has occurred. Nanotechnology can be used in order to formulate potent anticancer agents to improve their physicochemical properties such as poor aqueous solubility or prolong circulation times after administration resulting in improved efficacy. Studies have reported the use of nanotechnologies to improve the efficacy of gemcitabine (the current first line treatment) as well as investigating the potential of using other drug molecules which have previously shown promise but were unable to be utilised due to the inability to administer through appropriate routes-often related to solubility. Of the nanotechnologies reported, many can offer site specific targeting to the site of action as well as a plethora of other multifunctional properties such as image guidance and controlled release. This review focuses on the use of the major nanotechnologies both under pre-clinical development and those which have recently been approved for use in pancreatic cancer therapy.