Tumor-specific delivery of gemcitabine with activatable liposomes

Potent cancer therapy by liposome microstructure tailoring with active-to-passive targeting and shell-to-core thermosensitive features

Liposomes have been widely studied as drug carriers for clinical application, and the key issue is how to achieve effective delivery through targeting strategies. Even though certain cell-level targeting or EPR effect designs have been developed, reaching sufficient drug concentration in intracellular regions remains a challenge due to the singularity of functionality. Herein, benefiting from the unique features of tumor from tissue to cell, a dual-thermosensitive and dual-targeting liposome (DTSL) was creatively fabricated through fine microstructure tailoring, which holds intelligent both tissue-regulated active-to-passive binding and membrane-derived homologous-fusion (HF) properties. At the micro level, DTSL can actively capture tumor cells and accompany the enhanced HF effect stimulated by self-constriction, which achieves a synergistic promotion effect targeting tissues to cells. As a result, this first active-then passive targeting process makes drug delivery more accurate and effective, and after dynamic targeting into cells, the nucleus of DTSL undergoes further thermally responsive contraction, fully releasing internal drugs. In vivo experiments showed that liposomes with dual targeting and dual thermosensitive features almost completely inhibited tumor growth. Summarized, these results provide a reference for a rational design and microstructural tailoring of the liposomal co-delivery system of drugs, suggesting that active-to-passive dual-targeting DTSL can function as a new strategy for cancer treatment.

Biomaterial-Based CRISPR/Cas9 Delivery Systems for Tumor Treatment

CRISPR/Cas9 gene editing technology is characterized by high specificity and efficiency, and has been applied to the treatment of human diseases, especially tumors involving multiple genetic modifications. However, the clinical application of CRISPR/Cas9 still faces some major challenges, the most urgent of which is the development of optimized delivery vectors. Biomaterials are currently the best choice for use in CRISPR/Cas9 delivery vectors owing to their tunability, biocompatibility, and efficiency. As research on biomaterial vectors continues to progress, hope for the application of the CRISPR/Cas9 system for clinical oncology therapy builds. In this review, we first detail the CRISPR/Cas9 system and its potential applications in tumor therapy. Then, we introduce the different delivery forms and compare the physical, viral, and non-viral vectors. In addition, we analyze the characteristics of different types of biomaterial vectors. We further review recent research progress in the use of biomaterials as vectors for CRISPR/Cas9 delivery to treat specific tumors. Finally, we summarize the shortcomings and prospects of biomaterial-based CRISPR/Cas9 delivery systems.

Lipid-like gemcitabine diester-loaded liposomes for improved chemotherapy of pancreatic cancer

Gemcitabine (GEM) is a non-selective chemotherapeutic agent used in the treatment of pancreatic cancer. Its antitumor efficacy is limited by a short plasma half-life and severe adverse reactions. To overcome these shortcomings, four novel lipid-like GEM diesters were synthesized and encapsulated into liposomes. Through optimization, dimyristoyl GEM (dmGEM)-loaded liposomes (LipodmGEM) were successfully obtained with an almost complete encapsulation efficiency. Compared to free GEM, LipodmGEM showed enhanced cellular uptake and cell apoptosis, improved inhibition of cell migration on AsPC-1 cells and a greatly extended half-life (7.22 vs. 1.78 h). LipodmGEM succeeded in enriching the drug in the tumor (5.28 vs. 0.03 μmol/g at 8 h), overcoming a major shortcoming of GEM, showed excellent anticancer efficacy in vivo and negligible systemic toxicity, superior to GEM. Attractive as well, suspensions of LipodmGEM remained stable at 2-10 °C away from light for no <2 years. Our results suggest that LipodmGEM might become of high interest for treating pancreatic cancer while the simple strategy we reported might be explored as well for converting other antitumor drugs with high water-solubility and short plasma half-life into attractive nanomedicines.

Innovative Experimental Ultrasound and US-Related Techniques Using the Murine Model in Pancreatic Ductal Adenocarcinoma: A Systematic Review

Pancreatic ductal adenocarcinoma (PDAC) is a cancer with one of the highest mortality rates in the world. Several studies have been conductedusing preclinical experiments in mice to find new therapeutic strategies. Experimental ultrasound, in expert hands, is a safe, multifaceted, and relatively not-expensive device that helps researchers in several ways. In this systematic review, we propose a summary of the applications of ultrasonography in a preclinical mouse model of PDAC. Eighty-eight studies met our inclusion criteria. The included studies could be divided into seven main topics: ultrasound in pancreatic cancer diagnosis and progression (n: 21); dynamic contrast-enhanced ultrasound (DCE-US) (n: 5); microbubble ultra-sound-mediated drug delivery; focused ultrasound (n: 23); sonodynamic therapy (SDT) (n: 7); harmonic motion elastography (HME) and shear wave elastography (SWE) (n: 6); ultrasound-guided procedures (n: 9). In six cases, the articles fit into two or more sections. In conclusion, ultrasound can be a really useful, eclectic, and ductile tool in different diagnostic areas, not only regarding diagnosis but also in therapy, pharmacological and interventional treatment, and follow-up. All these multiple possibilities of use certainly represent a good starting point for the effective and wide use of murine ultrasonography in the study and comprehensive evaluation of pancreatic cancer.

Liposomal nanostructures for Gemcitabine and Paclitaxel delivery in pancreatic cancer

Pancreatic cancer (PC) is an incurable disease with a high death rate in the world nowadays. Gemcitabine (GEM) and Paclitaxel (PTX) are considered as references of chemotherapeutic treatments and are commonly used in clinical applications. Factors related to the tumor microenvironment such as insufficient tumor penetration, toxicity, and drug resistance can limit the effectiveness of these therapeutic anticancer drugs. The use of different liposomal nanostructures is a way that can optimize the drug's effectiveness and reduce toxicity. Given the development of PC therapy, this review focuses on advances in Nano-formulation, characterization, and delivery systems of loaded GEM and PTX liposomes using chemotherapy, nucleic acid delivery, and stroma remodeling therapy. As a result, the review covers the literature dealing with the applications of liposomes in PC therapy.

A new approach to the development and assessment of doxorubicin-loaded nanoliposomes for the treatment of osteosarcoma in 2D and 3D cell culture systems

Doxorubicin (DOX) is an effective anticancer drug used for the treatment of osteosarcoma. Liposomal nanocarriers for doxorubicin administration are now regarded as one of the most promising approaches to overcome multiple drug resistance and adverse side effects. The use of hydrogel as a 3D scaffold to mimic the cellular environment and provide comparable biological conditions for deeper investigations of cellular processes has attracted considerable attention. This study aimed to evaluate the impact of liposomal doxorubicin on the osteosarcoma cell line in the presence of alginate hydrogel as a three-dimensional scaffold. Different liposomal formulations based on cholesterol, phospholipids, and surfactants containing doxorubicin were developed using the thin-layer hydration approach to improve therapeutic efficacy. The final selected formulation was superficially modified using DSPE-mPEG2000. A three-dimensional hydrogel culture model with appropriate structure and porosity was synthesized using sodium alginate and calcium chloride as crosslinks for hydrogel. Then, the physical properties of liposomal formulations, such as mechanical and porosity, were characterized. The toxicity of the synthesized hydrogel was also assessed. Afterward, the cytotoxicity of nanoliposomes was analyzed on the Saos-2 and HFF cell lines in the presence of a three-dimensional alginate scaffold using the MTT assay. The results indicated that the encapsulation efficiency, the amount of doxorubicin released within 8 h, the mean size of vesicles, and the surface charge were 82.2%, 33.0%, 86.8 nm, and -4.2 mv, respectively. As a result, the hydrogel scaffolds showed sufficient mechanical resistance and suitable porosity. The MTT assay demonstrated that the synthesized scaffold had no cytotoxicity against cells, while nanoliposomal DOX exhibited marked toxicity against the Saos-2 cell line in the 3D culture medium of alginate hydrogel compared to the free drug in the 2D culture medium. Our research showed that the 3D culture model physically resembles the cellular matrix, and nanoliposomal DOX with proper size could easily penetrate into cells and cause higher cytotoxicity compared to the 2D cell culture.

Thermosensitive nanocomposite components for combined photothermal-photodynamic therapy in liver cancer treatment

Phototherapies, in the form of photodynamic therapy (PDT) and photothermal therapy (PTT), have great application prospects in the field of biomedical science due to high precision and non-invasiveness. Because of the limited therapeutic efficacy of single phototherapy, researchers start to focus on combined PTT-PDT. Here, we designed a composite nanomaterial for PTT-PDT. H-TiO₂ mesoporous spheres were prepared by sol-gel method and hydrogenation treatment. After modification with polydopamine (PDA), they were combined with indocyanine green (ICG) and NPe6 photosensitizers and coated by thermosensitive liposomes to prepare H-TiO₂ @PDA@ICG@NPe6 @Lipo nanocomposite component. The results indicated a substantial improvement of the component in the aspects of spectral response range, photothermal conversion efficiency and light absorption performance by modification and photosensitizers, in the absence of any toxicities on cells. Thermal induction and sequential irradiation with 808 nm and 664 nm lasers induced the aggregation of H-TiO₂ @PDA@ICG@NPe6 @Lipo at the tumor site to generate hyperthermia and massive reactive oxygen species (ROS), resulting in decreased cell activity or even cell apoptosis and restrained growth of allograft tumors. These findings underscore the favorable effects of H-TiO₂ @PDA@ICG@NPe6 @Lipo on the combined phototherapies and provide approaches for the development of nano-drugs in the context of liver cancer.

Liposome-based diagnostic and therapeutic applications for pancreatic cancer

Pancreatic cancer is one of the harshest and most challenging cancers to treat, often labeled as incurable. Chemotherapy continues to be the most popular treatment yet yields a very poor prognosis. The main barriers such as inefficient drug penetration and drug resistance, have led to the development of drug carrier systems. The benefits, ease of fabrication and modification of liposomes render them as ideal future drug delivery systems. This review delves into the versatility of liposomes to achieve various mechanisms of treatment for pancreatic cancer. Not only are there benefits of loading chemotherapy drugs and targeting agents onto liposomes, as well as mRNA combined therapy, but liposomes have also been exploited for immunotherapy and can be programmed to respond to photothermal therapy. Multifunctional liposomal formulations have demonstrated significant pre-clinical success. Functionalising drug-encapsulated liposomes has resulted in triggered drug release, specific targeting, and remodeling of the tumor environment. Suppressing tumor progression has been achieved, due to their ability to more efficiently and precisely deliver chemotherapy. Currently, no multifunctional surface-modified liposomes are clinically approved for pancreatic cancer thus we aim to shed light on the trials and tribulations and progress so far, with the hope for liposomal therapy in the future and improved patient outcomes. STATEMENT OF SIGNIFICANCE: Considering that conventional treatments for pancreatic cancer are highly associated with sub-optimal performance and systemic toxicity, the development of novel therapeutic strategies holds outmost relevance for pancreatic cancer management. Liposomes are being increasingly considered as promising nanocarriers for providing not only an early diagnosis but also effective, highly specific, and safer treatment, improving overall patient outcome. This manuscript is the first in the last 10 years that revises the advances in the application of liposome-based formulations in bioimaging, chemotherapy, phototherapy, immunotherapy, combination therapies, and emergent therapies for pancreatic cancer management. Prospective insights are provided regarding several advantages resulting from the use of liposome technology in precision strategies, fostering new ideas for next-generation diagnosis and targeted therapies of pancreatic cancer.

In Vitro Measurement and Mathematical Modeling of Thermally-Induced Injury in Pancreatic Cancer Cells

Thermal therapies are under investigation as part of multi-modality strategies for the treatment of pancreatic cancer. In the present study, we determined the kinetics of thermal injury to pancreatic cancer cells in vitro and evaluated predictive models for thermal injury. Cell viability was measured in two murine pancreatic cancer cell lines (KPC, Pan02) and a normal fibroblast (STO) cell line following in vitro heating in the range 42.5-50 °C for 3-60 min. Based on measured viability data, the kinetic parameters of thermal injury were used to predict the extent of heat-induced damage. Of the three thermal injury models considered in this study, the Arrhenius model with time delay provided the most accurate prediction (root mean square error = 8.48%) for all cell lines. Pan02 and STO cells were the most resistant and susceptible to hyperthermia treatments, respectively. The presented data may contribute to studies investigating the use of thermal therapies as part of pancreatic cancer treatment strategies and inform the design of treatment planning strategies.

Review of the Delivery Kinetics of Thermosensitive Liposomes

Thermosensitive liposomes (TSL) are triggered nanoparticles that release the encapsulated drug in response to hyperthermia. Combined with localized hyperthermia, TSL enabled loco-regional drug delivery to tumors with reduced systemic toxicities. More recent TSL formulations are based on intravascular triggered release, where drug release occurs within the microvasculature. Thus, this delivery strategy does not require enhanced permeability and retention (EPR). Compared to traditional nanoparticle drug delivery systems based on EPR with passive or active tumor targeting (typically <5%ID/g tumor), TSL can achieve superior tumor drug uptake (>10%ID/g tumor). Numerous TSL formulations have been combined with various drugs and hyperthermia devices in preclinical and clinical studies over the last four decades. Here, we review how the properties of TSL dictate delivery and discuss the advantages of rapid drug release from TSL. We show the benefits of selecting a drug with rapid extraction by tissue, and with quick cellular uptake. Furthermore, the optimal characteristics of hyperthermia devices are reviewed, and impact of tumor biology and cancer cell characteristics are discussed. Thus, this review provides guidelines on how to improve drug delivery with TSL by optimizing the combination of TSL, drug, and hyperthermia method. Many of the concepts discussed are applicable to a variety of other triggered drug delivery systems.

Anticancer Drugs: Recent Strategies to Improve Stability Profile, Pharmacokinetic and Pharmacodynamic Properties

In past decades, anticancer research has led to remarkable results despite many of the approved drugs still being characterized by high systemic toxicity mainly due to the lack of tumor selectivity and present pharmacokinetic drawbacks, including low water solubility, that negatively affect the drug circulation time and bioavailability. The stability studies, performed in mild conditions during their development or under stressing exposure to high temperature, hydrolytic medium or light source, have demonstrated the sensitivity of anticancer drugs to many parameters. For this reason, the formation of degradation products is assessed both in pharmaceutical formulations and in the environment as hospital waste. To date, numerous formulations have been developed for achieving tissue-specific drug targeting and reducing toxic side effects, as well as for improving drug stability. The development of prodrugs represents a promising strategy in targeted cancer therapy for improving the selectivity, efficacy and stability of active compounds. Recent studies show that the incorporation of anticancer drugs into vesicular systems, such as polymeric micelles or cyclodextrins, or the use of nanocarriers containing chemotherapeutics that conjugate to monoclonal antibodies can improve solubility, pharmacokinetics, cellular absorption and stability. In this study, we summarize the latest advances in knowledge regarding the development of effective highly stable anticancer drugs formulated as stable prodrugs or entrapped in nanosystems.

Metal complex-based liposomes: Applications and prospects in cancer diagnostics and therapeutics

Metal complexes are of increasing interest as pharmaceutical agents in cancer diagnostics and therapeutics, while some of them suffer from issues such as limited water solubility and severe systemic toxicity. These drawbacks severely hampered their efficacy and clinical applications. Liposomes hold promise as delivery vehicles for constructing metal complex-based liposomes to maximize the therapeutic efficacy and minimize the side effects of metal complexes. This review provides an overview on the latest advances of metal complex-based liposomal delivery systems. First, the development of metal complex-mediated liposomal encapsulation is briefly introduced. Next, applications of metal complex-based liposomes in a variety of fields are overviewed, where drug delivery, cancer imaging (single photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI)), and cancer therapy (chemotherapy, phototherapy, and radiotherapy) were involved. Moreover, the potential toxicity, action of toxic mechanisms, immunological effects of metal complexes as well as the advantages of metal complex-liposomes in this content are also discussed. In the end, the future expectations and challenges of metal complex-based liposomes in clinical cancer therapy are tentatively proposed.

Nanocarriers targeting the diseases of the pancreas

Diseases of the pancreas include acute and chronic pancreatitis, exocrine pancreatic insufficiency, diabetes and pancreatic cancer. These pathologies can be difficult to treat due to the innate properties of the pancreas, its structure and localization. The need for effective targeting of the pancreatic tissue by means of nanoparticles delivering therapeutics is a major focus area covered and discussed in this review. Most common diseases of the pancreas do not have specific and direct medical treatment option, and existing treatment options are generally aimed at relieving symptoms. Diabetes has different treatment options for different subtypes based on insulin having stability problems and requiring injections reducing patient compliance. Pancreatic cancer progresses silently and can only be diagnosed in advanced stages. Therefore, survival rate of patients is very low. Gemcitabine and FOLFIRINOX treatment regimens, the most commonly used clinical standard treatments, are generally insufficient due to the chemoresistance that develops in cancer cells and also various side effects. Therefore new treatment options for pancreatic cancer are also under focus. Overcoming drug resistance and pancreatic targeting can be achieved with active and passive targeting methods, and a more effective and safer treatment regimen can be provided at lower drug doses. This review covers the current literature and clinical trials concerning pancreatic drug delivery systems in the nanoscale focusing on the challenges and opportunities provided by these smart delivery systems.

Gemcitabine Direct Electrochemical Detection from Pharmaceutical Formulations Using a Boron-Doped Diamond Electrode

The development of fast and easy-to-use methods for gemcitabine detection is of great interest for pharmaceutical formulation control in both research laboratories and hospitals. In this study, we report a simple, fast and direct electrochemical method for gemcitabine detection using a boron-doped diamond electrode. The electrochemical oxidation of gemcitabine on a boron-doped diamond electrode was found to be irreversible in differential pulse voltammetry, and scan rate influence studies demonstrated that the process is diffusion-controlled. The influence of the pH and supporting electrolytes were also tested, and the optimized differential pulse voltammetry method was linear in the range of 2.5–50 μg/mL, with a detection limit of 0.85 μg/mL in phosphate-buffered saline (pH 7.4; 0.1 M). An amperometric method was also optimized for gemcitabine detection. The linear range of the method was 0.5–65 μg/mL in phosphate-buffered saline of pH 7.4 as well as pH 5.5, the limit of detection being 0.15 μg/mL. The optimized differential pulse voltammetry and amperometric detection strategies were successfully applied to pharmaceutical formulations, and the results were compared to those obtained by high-performance liquid chromatography and UV-Vis spectrophotometry with good correlations.

Emerging pro-drug and nano-drug strategies for gemcitabine-based cancer therapy

Gemcitabine has been extensively applied in treating various solid tumors. Nonetheless, the clinical performance of gemcitabine is severely restricted by its unsatisfactory pharmacokinetic parameters and easy deactivation mainly because of its rapid deamination, deficiencies in deoxycytidine kinase (DCK), and alterations in nucleoside transporter. On this account, repeated injections with a high concentration of gemcitabine are adopted, leading to severe systemic toxicity to healthy cells. Accordingly, it is highly crucial to fabricate efficient gemcitabine delivery systems to obtain improved therapeutic efficacy of gemcitabine. A large number of gemcitabine pro-drugs were synthesized by chemical modification of gemcitabine to improve its biostability and bioavailability. Besides, gemcitabine-loaded nano-drugs were prepared to improve the delivery efficiency. In this review article, we introduced different strategies for improving the therapeutic performance of gemcitabine by the fabrication of pro-drugs and nano-drugs. We hope this review will provide new insight into the rational design of gemcitabine-based delivery strategies for enhanced cancer therapy.

Heat-activated nanomedicine formulation improves the anticancer potential of the HSP90 inhibitor luminespib in vitro

The heat shock protein 90 inhibitor, luminespib, has demonstrated potent preclinical activity against numerous cancers. However, clinical translation has been impeded by dose-limiting toxicities that have necessitated dosing schedules which have reduced therapeutic efficacy. As such, luminespib is a prime candidate for reformulation using advanced drug delivery strategies that improve tumor delivery efficiency and limit off-target side effects. Specifically, thermosensitive liposomes are proposed as a drug delivery strategy capable of delivering high concentrations of drug to the tumor in combination with other chemotherapeutic molecules. Indeed, this work establishes that luminespib exhibits synergistic activity in lung cancer in combination with standard of care drugs such as cisplatin and vinorelbine. While our research team has previously developed thermosensitive liposomes containing cisplatin or vinorelbine, this work presents the first liposomal formulation of luminespib. The physico-chemical properties and heat-triggered release of the formulation were characterized. Cytotoxicity assays were used to determine the optimal drug ratios for treatment of luminespib in combination with cisplatin or vinorelbine in non-small cell lung cancer cells. The formulation and drug combination work presented in this paper offer the potential for resuscitation of the clinical prospects of a promising anticancer agent.

A Liposomal Gemcitabine, FF-10832, Improves Plasma Stability, Tumor Targeting, and Antitumor Efficacy of Gemcitabine in Pancreatic Cancer Xenograft Models

Purpose

The clinical application of gemcitabine (GEM) is limited by its pharmacokinetic properties. The aim of this study was to characterize the stability in circulating plasma, tumor targeting, and payload release of liposome-encapsulated GEM, FF-10832.

Methods

Antitumor activity was assessed in xenograft mouse models of human pancreatic cancer. The pharmacokinetics of GEM and its active metabolite dFdCTP were also evaluated.

Results

In mice with Capan-1 tumors, the dose-normalized areas under the curve (AUCs) after FF-10832 administration in plasma and tumor were 672 and 1047 times higher, respectively, than after using unencapsulated GEM. The tumor-to-bone marrow AUC ratio of dFdCTP was approximately eight times higher after FF-10832 administration than after GEM administration. These results indicated that liposomal encapsulation produced long-term stability in circulating plasma and tumor-selective targeting of GEM. In mice with Capan-1, SUIT-2, and BxPC-3 tumors, FF-10832 had better antitumor activity and tolerability than GEM. Internalization of FF-10832 in tumor-associated macrophages (TAMs) was revealed by flow cytometry and confocal laser scanning microscopy, and GEM was efficiently released from isolated macrophages of mice treated with FF-10832. These results suggest that TAMs are one of the potential reservoirs of GEM in tumors.

Conclusion

This study found that FF-10832 had favorable pharmacokinetic properties. The liposomal formulation was more effective and tolerable than unencapsulated GEM in mouse xenograft tumor models. Hence, FF-10832 is a promising candidate for the treatment of pancreatic cancer.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11095-021-03045-5.

Recent Advances in Lipid-Based Nanosystems for Gemcitabine and Gemcitabine-Combination Therapy

The anti-metabolite drug gemcitabine is widely used for the treatment of a variety of cancers. At present, gemcitabine is administered as a hydrochloride salt that is delivered by slow intravenous injection in cycles of three or four weeks. Although regarded as a 'front-line' chemotherapeutic agent, its efficacy is hampered by poor target cell specificity, sub-optimal cellular uptake, rapid clearance from circulation, the development of chemoresistance, and undesirable side-effects. The use of organic, inorganic, and metal-based nanoparticles as delivery agents presents an opportunity to overcome these limitations and safely harness optimal drug efficacy and enhance their therapeutic indices. Among the many and varied nano delivery agents explored, the greatest body of knowledge has been generated in the field of lipid-mediated delivery. We review here the liposomes, niosomes, solid lipid nanoparticles, nanostructured lipid carriers, exosomes, lipid-polymer hybrids, and other novel lipid-based agents that have been developed within the past six years for the delivery of gemcitabine and its co-drugs.

Nanoparticle delivery improves the pharmacokinetic properties of cyclic dinucleotide STING agonists to open a therapeutic window for intravenous administration

The stimulator of interferon genes (STING) pathway plays an important role in the immune surveillance of cancer and, accordingly, agonists of STING signaling have recently emerged as promising therapeutics for remodeling of the immunosuppressive tumor microenvironment (TME) and enhancing response rates to immune checkpoint inhibitors. 2'3'-cyclic guanosine monophosphate-adenosine monophosphate (2'3'-cGAMP) is the endogenous ligand for STING, but is rapidly metabolized and poorly membrane permeable, restricting its use to intratumoral administration. Nanoencapsulation has been shown to allow for systemic administration of cGAMP and other cyclic dinucleotides (CDN), but little is known about how nanocarriers affect important pharmacological properties that impact the efficacy and safety of CDNs. Using STING-activating nanoparticles (STING-NPs) - a polymersome platform designed to enhance cGAMP delivery - we investigate the pharmacokinetic (PK)-pharmacodynamic (PD) relationships that underlie the ability of intravenously (i.v.) administered STING-NPs to induce STING activation and inhibit tumor growth. First, we demonstrate that nanoencapsulation improves the half-life of encapsulated cGAMP by 40-fold, allowing for sufficient accumulation of cGAMP in tumors and activation of the STING pathway in the TME as assessed by western blot analysis and gene expression profiling. Nanoparticle delivery also changes the biodistribution profile, resulting in increased cGAMP accumulation and STING activation in the liver and spleen, which we identify as dose limiting organs. As a consequence of STING activation in tumors, i.v. administered STING-NPs reprogram the TME towards a more immunogenic antitumor milieu, characterized by an influx of >20-fold more CD4+ and CD8+ T-cells. Consequently, STING-NPs increased response rates to αPD-L1 antibodies, resulting in significant improvements in median survival time in a B16-F10 melanoma model. Additionally, we confirmed STING-NP monotherapy in an additional melanoma (YUMM1.7) and breast adenocarcinoma (E0771) models leading to >50% and 80% reduction in tumor burden, respectively, and significant increases in median survival time. Collectively, this work provides an examination of the PK-PD relationship governing STING activation upon systemic delivery using STING-NPs, providing insight for future optimization for nanoparticle-based STING agonists and other immunomodulating nanomedicines.

Anti-Cancer Nanomedicines: A Revolution of Tumor Immunotherapy

Immunotherapies have been accelerating the development of anti-cancer clinical treatment, but its low objective responses and severe off-target immune-related adverse events (irAEs) limit the range of application. Strategies to remove these obstacles primarily focus on the combination of different therapies and the exploitation of new immunotherapeutic agents. Nanomedicine potentiates the effects of activating immune cells selectively and reversing tumor induced immune deficiency microenvironment through multiple mechanisms. In the last decade, a variety of nano-enabled tumor immunotherapies was under clinical investigation. As time goes by, the advantages of nanomedicine are increasingly prominent. With the continuous development of nanotechnology, nanomedicine will offer more distinctive perspectives in imaging diagnosis and treatment of tumors. In this Review, we wish to provide an overview of tumor immunotherapy and the mechanisms of nanomaterials that aim to enhance the efficacy of tumor immunotherapy under development or in clinic treatment.

Nano drug delivery systems in upper gastrointestinal cancer therapy

Upper gastrointestinal (GI) carcinomas are characterized as one of the deadliest cancer types with the highest recurrence rates. Their treatment is challenging due to late diagnosis, early metastasis formation, resistance to systemic therapy and complicated surgeries performed in poorly accessible locations. Current cancer medication face deficiencies such as high toxicity and systemic side-effects due to the non-specific distribution of the drug agent. Nanomedicine has the potential to offer sophisticated therapeutic possibilities through adjusted delivery systems. This review aims to provide an overview of novel approaches and perspectives on nanoparticle (NP) drug delivery systems for gastrointestinal carcinomas. Present regimen for the treatment of upper GI carcinomas are described prior to detailing various NP drug delivery formulations and their current and potential role in GI cancer theranostics with a specific emphasis on targeted nanodelivery systems. To date, only a handful of NP systems have met the standard of care requirements for GI carcinoma patients. However, an increasing number of studies provide evidence supporting NP-based diagnostic and therapeutic tools. Future development and strategic use of NP-based drug formulations will be a hallmark in the treatment of various cancers. This article seeks to highlight the exciting potential of novel NPs for targeted cancer therapy in GI carcinomas and thus provide motivation for further research in this field.

Gemcitabine-retinoid prodrug loaded nanoparticles display in vitro antitumor efficacy towards drug-resilient human PANC-1 pancreatic cancer cells

The treatment of pancreatic cancer with gemcitabine is hampered by its rapid metabolism in vivo, the dense stroma around the tumor site which prevents the drug from reaching the cancerous cells and drug resistance. To address these challenges, this study describes the preparation of a retinoid prodrug of gemcitabine, GemRA (gemcitabine conjugated to retinoic acid), and its formulation into a nanoparticulate system applicable for pancreatic cancer treatment. Retinoic acid targets stellate cells which are part of the stroma and can thus augment the delivery of gemcitabine. GemRA dissolved in dimethylsulfoxide presented efficacy towards PANC-1 (human) and mT4 (mouse) pancreatic cancer cell lines but its poor solubility in aqueous solution affects its applicability. Thus, the preparation of the nanoparticles was initially attempted through self-assembly of GemRA, which resulted in the formation of unstable aggregates that precipitated during preparation. As a result, encapsulation of the drug into micelles of polyethylene glycol-retinoic acid (PGRA) amphiphilic conjugates was accomplished and resulted in successful incorporation of GemRA into nanoparticles of ca. 33 nm by dynamic light scattering and 25 nm by transmission electron microscopy. The nanoparticles had good stability in aqueous media and protected gemcitabine from the enzymatic action of cytidine deaminase, which converts gemcitabine to its inactive metabolite upon circulation. Cellular uptake of the nanoparticles by PANC-1 cells was confirmed by fluorescence spectroscopy and flow cytometry. Treatment of PANC-1 cells in vitro with the prodrug-loaded nanoparticles resulted in a significant reduction in cell viability (IC50 ca. 5 μM) compared to treatment with gemcitabine (IC50 > 1000 μM). The ability of the GemRA-loaded nanoparticles to induce cellular apoptosis of treated PANC-1 cells was ascertained via a TUNEL assay suggesting these nanoparticles are effective in pancreatic cancer treatment.

Recent Progress in Bioconjugation Strategies for Liposome-Mediated Drug Delivery

In nanoparticle (NP)-mediated drug delivery, liposomes are the most widely used drug carrier, and the only NP system currently approved by the FDA for clinical use, owing to their advantageous physicochemical properties and excellent biocompatibility. Recent advances in liposome technology have been focused on bioconjugation strategies to improve drug loading, targeting, and overall efficacy. In this review, we highlight recent literature reports (covering the last five years) focused on bioconjugation strategies for the enhancement of liposome-mediated drug delivery. These advances encompass the improvement of drug loading/incorporation and the specific targeting of liposomes to the site of interest/drug action. We conclude with a section highlighting the role of bioconjugation strategies in liposome systems currently being evaluated for clinical use and a forward-looking discussion of the field of liposomal drug delivery.

Development of thermosensitive resiquimod-loaded liposomes for enhanced cancer immunotherapy

Resiquimod (R848) is a toll-like receptor 7 and 8 (TLR7/8) agonist with potent antitumor and immunostimulatory activity. However, systemic delivery of R848 is poorly tolerated because of its poor solubility in water and systemic immune activation. In order to address these limitations, we developed an intravenously-injectable formulation with R848 using thermosensitive liposomes (TSLs) as a delivery vehicle. R848 was remotely loaded into TSLs composed of DPPC: DSPC: DSPE-PEG2K (85:10:5, mol%) with 100 mM FeSO₄ as the trapping agent inside. The final R848 to lipid ratio of the optimized R848-loaded TSLs (R848-TSLs) was 0.09 (w/w), 10-fold higher than the previously-reported values. R848-TSLs released 80% of R848 within 5 min at 42 °C. These TSLs were then combined with αPD-1, an immune checkpoint inhibitor, and ultrasound-mediated hyperthermia in a neu deletion (NDL) mouse mammary carcinoma model (Her2⁺, ER/PR negative). Combined with αPD-1, local injection of R848-TSLs showed superior efficacy with complete NDL tumor regression in both treated and abscopal sites achieved in 8 of 11 tumor bearing mice over 100 days. Immunohistochemistry confirmed enhanced CD8⁺ T cell infiltration and accumulation by R848-TSLs. Systemic delivery of R848-TSLs, combined with local hyperthermia and αPD-1, inhibited tumor growth and extended median survival from 28 days (non-treatment control) to 94 days. Upon re-challenge with reinjection of tumor cells, none of the previously cured mice developed tumors, as compared with 100% of age-matched control mice. The dose of R848 (10 μg for intra-tumoral injection or 6 mg/kg for intravenous injection delivered up to 4 times) was well-tolerated without weight loss or organ hypertrophy. In summary, we developed R848-TSLs that can be administered locally or systematically, resulting in tumor regression and enhanced survival when combined with αPD-1 in mouse models of breast cancer.

Improved efficacy of doxorubicin delivery by a novel dual-ligand-modified liposome in hepatocellular carcinoma

Liposomes have been widely used as drug carriers in both biomedical research and for clinical applications, allowing the stabilisation of therapeutic compounds and overcoming obstacles to cellular and tissue uptake. However, liposomes still have low targeting efficiency, resulting in insufficient killing of tumour cells and unnecessary damage to normal cells. In this study, glycyrrhetinic acid (GA) and peanut agglutinin (PNA) were used as ligands to prepare dual-ligand-modified doxorubicin-loaded liposomes (DOX-GA/PNA-Lips) to enhance the targeting accuracy and efficacy of drug delivery against malignant liver cancer. PNA and GA modification enhanced the binding ability of liposomes to liver cancer cells, leading to excellent tissue and cell targeting of DOX-GA/PNA-Lips. DOX-GA/PNA-Lips showed an effective anti-tumour effect in vivo and in vitro, with its targeted delivery facilitating attenuation of the toxic side effects of DOX. These results demonstrated that dual-ligand-modified liposomes may provide an effective strategy for the treatment of hepatocellular carcinoma.

Physical triggering strategies for drug delivery

Physically triggered systems hold promise for improving drug delivery by enhancing the controllability of drug accumulation and release, lowering non-specific toxicity, and facilitating clinical translation. Several external physical stimuli including ultrasound, light, electric fields and magnetic fields have been used to control drug delivery and they share some common features such as spatial targeting, spatiotemporal control, and minimal invasiveness. At the same time, they possess several distinctive features in terms of interactions with biological entities and/or the extent of stimulus response. Here, we review the key advances of such systems with a focus on discussing their physical mechanisms, the design rationales, and translational challenges.

Nanomaterials: Applications in the diagnosis and treatment of pancreatic cancer

Pancreatic cancer (PC) remains one of the leading causes of cancer-related death in human sowing to missed early and effective diagnosis. The inability to translate research into clinical trials and to target chemotherapy drugs to tumors is a major obstacle in PC treatment. Compared with traditional cancer detection methods, the method combining existing clinical diagnosis and detection systems with nanoscale components using novel nanomaterials shows higher sensitivity and specificity. Nanomaterials can interact with biological systems to efficiently and accurately detect and monitor biological events during diagnosis and treatment. With the advance of experimental and engineering technology, more nanomaterials will begin the transition to clinical trials for their validation. This paper describes a number of nanomaterials used in the diagnosis and treatment of PC.