Barriers to drug delivery in solid tumors

Niclosamide-loaded polymeric micelles ameliorate hepatocellular carcinoma in vivo through targeting Wnt and Notch pathways

AIM

Niclosamide (NIC) is an anthelmintic agent repurposed as a potent anticancer agent. However, its use is hindered by its poor solubility. We investigated the underlying mechanisms of NIC anticancer activity employing a novel oral NIC pluronic-based nanoformulation and tested its effect in thioacetamide-induced hepatocellular carcinoma (HCC) in rats. We evaluated its antitumor effect through regulating Wnt/β-catenin and Notch signaling pathways and apoptosis.

MAIN METHODS

Niclosamide-loaded pluronic nanoparticles (NIC-NPs) were optimally developed and characterized with sustained release properties up to 7 days. Sixteen weeks after HCC induction, NIC (70 mg/kg) and an equivalent dose of NIC-NPs were administered orally for 3 consecutive weeks. Hepatocyte integrity was assessed by measuring serum levels of aminotransferases, ALP, GGT, bilirubin, albumin and total protein. HCC development was detected by measuring AFP expression. Necroinflammation and fibrosis were scored by histopathological examination. Wnt/β-catenin and Notch signaling were evaluated by measuring hepatic mRNA levels of Wnt3A, Lrp5 and Lrp6 Co-receptors, Dvl-2, Notch1 and Hes1 and β-catenin protein levels. Apoptosis was assessed by measuring mRNA and protein levels of cyclin D1 and caspase-3.

KEY FINDING

The novel NIC-NPs restored liver integrity, reduced AFP levels and showed improved anticancer and proapoptotic activities compared to drug alone. The inhibitory effect of NIC on Wnt/β-catenin and Notch signaling pathways was potentiated by the NIC-NPs formulation.

SIGNIFICANCE

We conclude that NIC acts by inhibiting Wnt/β-catenin and Notch signaling and inducing apoptosis in HCC. Developing pluronic-based nanoformulations may be a promising approach to improve NIC solubility and offer the possibility of controlled release.

Nanomicellar Lenalidomide-Fenretinide Combination Suppresses Tumor Growth in an MYCN Amplified Neuroblastoma Tumor

Purpose

In a previous study, we demonstrated that the combination of fenretinide with lenalidomide, administered by a novel nanomicellar formulation (FLM), provided a strong antitumor effect in a neuroblastoma TrkB-expressing tumor. In this study, we tested the nanomicellar combination in an MYCN amplified neuroblastoma xenograft to assess its efficacy in different tumor genotypes and evaluate the interactions of the nanomicelles with the tumor cells.

Experimental Design

FLM was administered to mice bearing human NLF xenografts to evaluate its efficacy in comparison with the nanomicelles containing fenretinide alone (FM). Confocal laser-scanning fluorescence microscopy images of the NLF cells treated with FLM and FM allowed us to estimate the nanomicelle ability to transport the encapsulated drugs inside the tumor cells. Flow cytometric analysis of the cells from treated tumors was performed to assess the effect of treatment on GD2 expression and NK cell infiltration.

Results

FLM and FM decreased the growth of NLF xenografts at comparable extents during the treatment period. Afterwards, FLM induced a progressive tumor regression without regrowth, while FM treatment was followed by regrowth within 15-20 days after the end of treatment. Both FLM and FM were able to penetrate the tumor cells transporting the encapsulated drugs. FLM transported higher amount of fenretinide inside the cells. Also, FLM treatment strongly increased GD2 expression in treated tumors and slightly decreased the NK infiltration compared to FM.

Conclusion

FLM treatment induced a superior antitumor response than FM in NLF xenografts, presumably due to the combined effects of fenretinide cytotoxicity and lenalidomide antiangiogenic activity. The ability of FLM to penetrate tumor cells, transporting the encapsulated drugs, substantially improved the therapeutic efficiency of this system. Moreover, the enhancement of GD2 expression in FLM treated tumors offers the possibility to further increase the antitumor effect by the use of anti-GD2 CAR-T cells and anti-GD2 antibodies in combination with FLM in multimodal therapies.

Barriers and Strategies of Cationic Liposomes for Cancer Gene Therapy

Cationic liposomes (CLs) have been regarded as the most promising gene delivery vectors for decades with the advantages of excellent biodegradability, biocompatibility, and high nucleic acid encapsulation efficiency. However, the clinical use of CLs in cancer gene therapy is limited because of many uncertain factors in vivo. Extracellular barriers such as opsonization, rapid clearance by the reticuloendothelial system and poor tumor penetration, and intracellular barriers, including endosomal/lysosomal entrapped network and restricted diffusion to the nucleus, make CLs not the ideal vector for transferring extrinsic genes in the body. However, the obstacles in achieving productive therapeutic effects of nucleic acids can be addressed by tailoring the properties of CLs, which are influenced by lipid compositions and surface modification. This review focuses on the physiological barriers of CLs against cancer gene therapy and the effects of lipid compositions on governing transfection efficiency, and it briefly discusses the impacts of particle size, membrane charge density, and surface modification on the fate of CLs in vivo, which may provide guidance for their preclinical studies.

Nanocomposite hydrogel with NIR/magnet/enzyme multiple responsiveness to accurately manipulate local drugs for on-demand tumor therapy

Chemotherapy is one of the most commonly utilized approaches to treat malignant tumor. However, the well-controlled chemotherapy able to accurately manipulate local drugs for on-demand tumor treatment is still a challenge. Herein, a magnet and light dual-responsive hydrogel combining thermosensitive poly(N-acryloyl glycinamide) (PNAGA), doxorubicin (DOX) loaded and polyester (PE) capped mesoporous silica nanocarriers (MSNs) as well as Fe₃O₄ nanoparticles (Fe₃O₄ NPs) grafted graphene oxide (GO) was fabricated to address above issue. The Fe₃O₄ NPs and GO respectively serve as magnetothermal agent and photothermal agent to perform hyperthermia, meanwhile to generate chain motion of PNAGA with varying degrees under different conditions of magnetic field and/or NIR irradiation. This strategy not only allowed the gel-sol transition of the hydrogel by prior heating for tumor injection, but performed controllable release routes of DOX-MSNs-PE (DMP for short) nanocarriers to meet various requirements from different patients and the changing states of tumor. Furthermore, these escaped DMP nanocarriers could be taken by surrounding tumor cells, and then deliver their drug to these cells after rapid hydrolysis of the PE cap triggered by esterase, resulting in accurate chemotherapy. Both in vitro and in vivo results indicated that the PNAGA-DMP-Fe₃O₄@GO hydrogel combining well-controllable chemotherapy and hyperthermia can eliminate more than 90% tumor cells and effectively inhibit the tumor growth in mice model, demonstrating the great candidate of our hydrogel for accurate tumor therapy.

Biocompatibility of Biomaterials for Nanoencapsulation: Current Approaches

Nanoencapsulation is an approach to circumvent shortcomings such as reduced bioavailability, undesirable side effects, frequent dosing and unpleasant organoleptic properties of conventional drug delivery systems. The process of nanoencapsulation involves the use of biomaterials such as surfactants and/or polymers, often in combination with charge inducers and/or ligands for targeting. The biomaterials selected for nanoencapsulation processes must be as biocompatible as possible. The type(s) of biomaterials used for different nanoencapsulation approaches are highlighted and their use and applicability with regard to haemo- and, histocompatibility, cytotoxicity, genotoxicity and carcinogenesis are discussed.

Selective targeting of cancer signaling pathways with nanomedicines: challenges and progress

Cancer is one of the leading causes of death worldwide. Regardless of advances in understanding the molecular mechanics of cancer, its treatment is still lacking and the death rates for many forms of the disease remain the same as six decades ago. Although a variety of therapeutic agents and strategies have been reported, these therapies often failed to provide efficient therapy to patients as a consequence of the inability to deliver right and adequate chemotherapeutic agents to the right place. However, the situation has started to revolutionize substantially with the advent of novel 'targeted' nanocarrier-based cancer therapies. Such therapies hold great potential in cancer management as they are biocompatible, tailored to specific needs, tolerated and deliver enough drugs at the targeted site. Their use also enhances the delivery of chemotherapeutics by improving biodistribution, lowering toxicity, inhibiting degradation and increasing cellular uptake. However, in some instances, nonselective targeting is not enough and the inclusion of a ligand moiety is required to achieve tumor targeting and enhanced drug accumulation at the tumor site. This contemporary review outlines the targeting potential of nanocarriers, highlighting the essentiality of nanoparticles, tumor-associated molecular signaling pathways, and various biological and pathophysiological barriers.

In situ forming implants exposed to ultrasound enhance therapeutic efficacy in subcutaneous murine tumors

In situ forming implants (ISFIs) allow for a high initial intratumoral concentration and sustained release of the chemotherapeutic. However, clinical translation is impeded primarily due to limited drug penetration from the tumor/boundary interface and poor intratumoral drug retention. Therapeutic ultrasound (TUS) has become a popular approach for improving drug penetration of transdermal devices and increasing cellular uptake of nanoparticles. These effects are driven by the mechanical and thermal bioeffects associated with TUS. In this study, we characterize the released drug penetration, retention, and overall therapeutic response when exposing ISFI to the combination of the mechanical and thermal effects of TUS (C-TUS). ISFIs were intratumorally injected into subcutaneous murine tumors then exposed to C-TUS (exposure: 5 min, duty factor: 0.33, frequency: 3 MHz, intensity: 2.2 W/cm2, pulse duration: 2 ms, pulse repetition frequency: 165 Hz, effective radiating area: 5 cm2, energy delivered: 896 J, time average intensity: 0.88 W/cm2). Tumors treated with the combination of ISFI + C-TUS demonstrated a 2.5-fold increase in maximum drug penetration and a 3-fold increase in drug retention at 5- and 8-days post-injection, respectively, compared to ISFIs without TUS exposure. These improvements in drug penetration and retention translated into an enhanced therapeutic response. Mice treated with ISFI + C-TUS showed a 62.6% reduction in tumor progression, a 50.0% increase in median survival time, and a 26.6% increase in necrotic percentage compared to ISFIs without TUS exposure. Combining intratumoral ISFIs with TUS may be beneficial for addressing some long-standing challenges with local drug delivery in cancer treatment and may serve as a viable noninvasive method to improve the poor clinical success of local drug delivery systems.

Proteins from Lignosus tigris with selective apoptotic cytotoxicity towards MCF7 cell line and suppresses MCF7-xenograft tumor growth

Background

Lignosus tigris, a recently discovered species of the unique Lignosus family, has been traditionally used by the indigenous communities in Peninsular Malaysia to treat various ailments and as an alternative medicine for cancer treatment. The L. tigris cultivar sclerotia (Ligno TG-K) was found to contain numerous bioactive compounds with beneficial biomedicinal properties and the sclerotial extract exhibited potent antioxidant activity. However, the anticancer property of the Ligno TG-K including in vitro and in vivo antitumor effects as well as its anticancer active compounds and the mechanisms has yet to be investigated.

Methods

The cytotoxicity of the Ligno TG-K against human breast (MCF7), prostate (PC3) and lung (A549) adenocarcinoma cell lines was evaluated using MTT cytotoxicity assay. The cytotoxic mechanisms of the active high molecular weight proteins (HMWp) fraction were investigated through detection of caspases activity and apoptotic-related proteins expression by Western blotting. The in vivo antitumor activity of the isolated HMWp was examined using MCF7 mouse xenograft model. Shotgun LC-MS/MS analysis was performed to identify the proteins in the HMWp.

Results and Discussion

Cold water extract of the sclerotia inhibited proliferation of MCF7, A549 and PC3 cells with IC₅₀ ranged from 28.9 to 95.0 µg/mL. Bioassay guided fractionation of the extract revealed that HMWp exhibited selective cytotoxicity against MCF7 cells via induction of cellular apoptosis by the activation of extrinsic and intrinsic signaling pathways. HMWp activated expression of caspase-8 and -9 enzymes, and pro-apoptotic Bax protein whilst inhibiting expression of tumor survivor protein, Bcl-2. HMWp induced tumor-cell apoptosis and suppressed growth of tumor in MCF-7 xenograft mice. Lectins, serine proteases, RNase Gf29 and a 230NA deoxyribonuclease are the major cytotoxic proteins that accounted for 55.93% of the HMWp.

Conclusion

The findings from this study provided scientific evidences to support the traditional use of the L. tigris sclerotia for treatment of breast cancer. Several cytotoxic proteins with high abundance have been identified in the HMWp of the sclerotial extract and these proteins have potential to be developed into new anticancer agents or as adjunct cancer therapy.

Potentiality, Limitations, and Consequences of Different Experimental Models to Improve Photodynamic Therapy for Cancer Treatment in Relation to Antiangiogenic Mechanism

The relevance of experimentally gained information represents a long-term debating issue in the field of molecular biology research. The loss of original conditions in the in vitro environment affects various biological mechanisms and cellular interactions. Consequently, some biochemical mechanisms are lost or critically altered. Analyses in these modified conditions could, therefore, distort the relevancy of experimentally gained information. In some cases, the similarities with original conditions are so small that utilization of simpler in vitro models seems impossible, or could occur in a very limited way. To conclude, the study of more complex phenomena places higher demands on the complexity of the experimental model. The latest information highlights the fact that the tumor angiogenesis mechanism has very complex features. This complexity can be associated with a wide range of angiogenic factors expressed by a variety of malignant and non-malignant cells. Our article summarizes the results from various experimental models that were utilized to analyze a photodynamic therapy effect on tumor angiogenic mechanisms. Additionally, based on the latest information, we present the most important attributes and limitations of utilized experimental models. We also evaluate the essential problems associated with angiogenic mechanism induction after photodynamic therapy application.

Human intratumoral therapy: Linking drug properties and tumor transport of drugs in clinical trials

Cancer therapies aim to kill tumor cells directly or engage the immune system to fight malignancy. Checkpoint inhibitors, oncolytic viruses, cell-based immunotherapies, cytokines, and adjuvants have been applied to prompt the immune system to recognize and attack cancer cells. However, systemic exposure of cancer therapies can induce unwanted adverse events. Intratumoral administration of potent therapies utilizes small amounts of drugs, in an effort to minimize systemic exposure and off-target toxicities. Here, we discuss the properties of the tumor microenvironment and transport considerations for intratumoral drug delivery. Specifically, we consider various tumor tissue factors and physicochemical factors that can affect tumor retention after intratumoral injection. We also review approved and clinical-stage intratumoral therapies and consider how the molecular and biophysical properties (e.g. size and charge) of these therapies influences intratumoral transport (e.g. tumor retention and cellular uptake). Finally, we offer a critical review and highlight several emerging approaches to promote tumor retention and limit systemic exposure of potent intratumoral therapies.

Engineering nanomedicines through boosting immunogenic cell death for improved cancer immunotherapy

Current cancer immunotherapy has limited response rates in a large variety of solid tumors partly due to the low immunogenicity of the tumor cells and the immunosuppressive tumor microenvironment (ITM). A number of clinical cancer treatment modalities, including radiotherapy, chemotherapy, photothermal and photodynamic therapy, have been shown to elicit immunogenicity by inducing immunogenic cell death (ICD). However, ICD-based immunotherapy is restricted by the ITM limiting its efficacy in eliciting a long-term antitumor immune response, and by severe systemic toxicity. To address these challenges, nanomedicine-based drug delivery strategies have been exploited for improving cancer immunotherapy by boosting ICD of the tumor cells. Nanosized drug delivery systems are promising for increasing drug accumulation at the tumor site and codelivering ICD inducers and immune inhibitors to simultaneously elicit the immune response and relieve the ITM. This review highlights the recent advances in nanomedicine-based immunotherapy utilizing ICD-based approaches. A perspective on the clinical translation of nanomedicine-based cancer immunotherapy is also provided.

Oncolytic bacteria: past, present and future

More than a century ago, independent groups raised the possibility of using bacteria to selectively infect tumours. Such treatment induces an immune reaction that can cause tumour rejection and protect the patient against further recurrences. One of the first holistic approximations to use bacteria in cancer treatment was performed by William Coley, considered the father of immune-therapy, at the end of XIX century. Since then, many groups have used different bacteria to test their antitumour activity in animal models and patients. The basis for this reactivity implies that innate immune responses activated upon bacteria recognition, also react against the tumour. Different publications have addressed several aspects of oncolytic bacteria. In the present review, we will focus on revisiting the historical aspects using bacteria as oncolytic agents and how they led to the current clinical trials. In addition, we address the molecules present in oncolytic bacteria that induce specific toxic effects against the tumors as well as the activation of host immune responses in order to trigger antitumour immunity. Finally, we discuss future perspectives that could be considered in the different fields implicated in the implementation of this kind of therapy in order to improve the current use of bacteria as oncolytic agents.

Magnetotactic Bacteria and Magnetosomes as Smart Drug Delivery Systems: A New Weapon on the Battlefield with Cancer?

An important direction of research in increasing the effectiveness of cancer therapies is the design of effective drug distribution systems in the body. The development of the new strategies is primarily aimed at improving the stability of the drug after administration and increasing the precision of drug delivery to the destination. Due to the characteristic features of cancer cells, distributing chemotherapeutics exactly to the microenvironment of the tumor while sparing the healthy tissues is an important issue here. One of the promising solutions that would meet the above requirements is the use of Magnetotactic bacteria (MTBs) and their organelles, called magnetosomes (BMs). MTBs are commonly found in water reservoirs, and BMs that contain ferromagnetic crystals condition the magnetotaxis of these microorganisms. The presented work is a review of the current state of knowledge on the potential use of MTBs and BMs as nanocarriers in the therapy of cancer. The growing amount of literature data indicates that MTBs and BMs may be used as natural nanocarriers for chemotherapeutics, such as classic anti-cancer drugs, antibodies, vaccine DNA, and siRNA. Their use as transporters increases the stability of chemotherapeutics and allows the transfer of individual ligands or their combinations precisely to cancerous tumors, which, in turn, enables the drugs to reach molecular targets more effectively.

Cytotoxicity of Novel Redox Sensitive PEG2000-S-S-PTX Micelles against Drug-Resistant Ovarian and Breast Cancer Cells

PURPOSE

Since the last decade, it is established that nonspecific delivery of chemotherapeutics fails to effectively treat cancer due to systemic cytotoxicity, poor biodistribution at tumor site and most importantly the development of drug resistance (MDR). Stimuli-sensitive drug delivery systems gained significant attention in recent years for effective tumor therapy and reversal of MDR. The aim of this study was developing a redox sensitive micellar prodrug system, by taking the advantage of the significant difference in GSH levels between extracellular and intracellular environments, but more importantly in healthy and tumor tissues.

METHODS

Redox sensitive PEG₂₀₀₀-S-S-PTX micelles were developed for intracellular paclitaxel delivery and characterized in vitro. In vitro release studies were carried out and followed by cytotoxicity studies in chemo-resistant ovarian and breast cancer cells in various reducing environments for different time periods to confirm their potential.

RESULTS

PEG₂₀₀₀-S-S-PTX, was synthesized and characterized as a redox sensitive micellar prodrug system. The reduction sensitivity and in vitro PTX release properties were confirmed in reducing environments comparatively with physiological conditions. Cytotoxicity studies suggested that ovarian (SK-OV-3) cells could be better candidates for treatment with redox-sensitive drug delivery systems than breast (MCF-7) cancer cells.

CONCLUSIONS

The results of this study highlights the importance of personalized therapy since no fits-for-all system can be developed for different cancer with significantly different metabolic activities. Graphical Abstract Schematic representation of self-assembly of reduction-sensitive PEG2000-S-S-PTX micelles and GSH dependent release of PTX.

Use of Oppositely Polarized External Magnets To Improve the Accumulation and Penetration of Magnetic Nanocarriers into Solid Tumors

Drug delivery to solid tumors is hindered by hydrostatic and physical barriers that limit the penetration of nanocarriers into tumor tissue. When exploiting the enhanced permeability and retention (EPR) effect for passive targeting of nanocarriers, the increased interstitial fluid pressure and dense extracellular matrix in tumors limits the distribution of the nanocarriers to perivascular regions. Previous strategies have shown that magnetophoresis enhances accumulation and penetration of nanoparticles into solid tumors. However, because magnetic fields fall off rapidly with distance from the magnet, these methods have been limited to use in superficial tumors. To overcome this problem, we have developed a system comprising two oppositely polarized magnets that enables the penetration of magnetic nanocarriers into more deeply seeded tumors. Using this method, we demonstrate a 5-fold increase in the penetration and a 3-fold increase in the accumulation of magnetic nanoparticles within solid tumors compared to EPR.

Predicting Therapeutic Antibody Delivery into Human Head and Neck Cancers

PURPOSE

The efficacy of antibody-based therapeutics depends on successful drug delivery into solid tumors; therefore, there is a clinical need to measure intratumoral antibody distribution. This study aims to develop and validate an imaging and computation platform to directly quantify and predict antibody delivery into human head and neck cancers in a clinical study.

EXPERIMENTAL DESIGN

Twenty-four patients received systemic infusion of a near-infrared fluorescence-labeled therapeutic antibody followed by surgical tumor resection. A computational platform was developed to quantify the extent of heterogeneity of intratumoral antibody distribution. Both univariate and multivariate regression analyses were used to select the most predictive tumor biological factors for antibody delivery. Quantitative image features from the pretreatment MRI were extracted and correlated with fluorescence imaging of antibody delivery.

RESULTS

This study not only confirmed heterogeneous intratumoral antibody distribution in-line with many preclinical reports, but also quantified the extent of interpatient, intertumor, and intratumor heterogeneity of antibody delivery. This study demonstrated the strong predictive value of tumor size for intratumoral antibody accumulation and its significant impact on antibody distribution in both primary tumor and lymph node metastasis. Furthermore, this study established the feasibility of using contrast-enhanced MRI to predict antibody delivery.

CONCLUSIONS

This study provides a clinically translatable platform to measure antibody delivery into solid tumors and yields valuable insight into clinically relevant antibody tumor penetration, with implications in the selection of patients amenable to antibody therapy and the design of more effective dosing strategies.

The assembly and antitumor activity of lycium barbarum polysaccharide-platinum-based conjugates

In this work, the new polysaccharide-platinum conjugates of 5-aminosalicylic acid modified lycium barbarum polysaccharide linking platinum compounds were designed in order to construct an anticancer metal drug delivery system. The multiple analysis methods were used to describe the chemical structure and physical properties of the polysaccharide-metal conjugates. The results showed that 5-aminosalicylic acid successfully acted as linker which was covalently bound between polysaccharide and platinum compound. The morphology and rheological properties of polysaccharide have been changed by the formation of conjugates, which exhibited certain inhibition specificity to A549 (human lung cancer cell line). The agarose gel electrophoresis and fluorescence microscopy results demonstrated that such conjugates promoted the unwinding of DNA and could significantly damage the nucleus of A549 cells. Cell cycle analyzing the Pt complex of conjugates could cause intracellular DNA damage and induced G2 phase arrest. So, polysaccharide-platinum conjugates might find a range of applications, for example in metal anticancer drug delivery.

Tumor microenvironment targeted nanotherapeutics for cancer therapy and diagnosis: A review

Recent findings suggest that the cellular and extracellular materials surrounding the cancerous cells from an atypical tumor microenvironment (TM) play a pivotal role in the process of tumor initiation and progression. TM comprises an intricate system involving diverse cell types including endothelial cells, pericytes, smooth muscle cells, fibroblasts, various inflammatory cells, dendritic cells, and cancer stem cells (CSCs). The TM-forming cells dynamically interact with the cancerous cells through various signaling mechanisms and pathways. The existence of this dynamic cellular communication is responsible for creating an environment suitable for sustaining a reasonably high cellular proliferation. Presently, researchers are showing interest to use these TM conditions to mediate effective targeting measures for cancer therapy. The use of nanotherapeutics-based combination therapy; stimuli-responsive nanotherapeutics targeting acidic pH, hypoxic environment; and nanoparticle-induced hyperthermia are some of the approaches that are under intense investigation for cancer therapy. This review discusses TM and its role in cancer progression and crosstalk understanding, opportunities, and epigenetic modifications involved therein to materialize the capability of nanotherapeutics to target cancer by availing TM. STATEMENT OF SIGNIFICANCE: This article presents various recent reports, proof-of-concept studies, patents, and clinical trials on the concept of tumor microenvironment for mediating the cancer-specific delivery of nanotechnology-based systems bearing anticancer drug and diagnostics. We highlight the potential of tumor microenvironment; its role in disease progression, opportunities, challenges, and allied treatment strategies for effective cancer therapy by conceptual understanding of tumor microenvironment and epigenetic modifications involved. Specifically, nanoparticle-based approaches to target various processes related to tumor microenvironment (pH responsive, hypoxic environment responsive, targeting of specific cells involved in tumor microenvironment, etc.) are dealt in detail.

The Metabolic Remodelling in Lung Cancer and Its Putative Consequence in Therapy Response

Lung cancer is the leading cause of cancer-related deaths worldwide in both men and women. Conventional chemotherapy has failed to provide long-term benefits for many patients and in the past decade, important advances were made to understand the underlying molecular/genetic mechanisms of lung cancer, allowing the unfolding of several other pathological entities. Considering these molecular subtypes, and the appearance of promising targeted therapies, an effective personalized control of the disease has emerged, nonetheless benefiting a small proportion of patients. Although immunotherapy has also appeared as a new hope, it is still not accessible to the majority of patients with lung cancer.The metabolism of energy and biomass is the basis of cellular survival. This is true for normal cells under physiological conditions and it is also true for pathophysiologically altered cells, such as cancer cells. Thus, knowledge of the metabolic remodelling that occurs in cancer cells in the sense of, on one hand, surviving in the microenvironment of the organ in which the tumour develops and, on the other hand, escaping from drugs conditioned microenvironment, is essential to understand the disease and to develop new therapeutic approaches.

A Cell Membrane-Targeting Self-Delivery Chimeric Peptide for Enhanced Photodynamic Therapy and In Situ Therapeutic Feedback

Nowadays, cell membrane-targeted therapy, which owns high antitumor efficacy by avoiding cell barriers, has received great attention. Here, a cell membrane-targeted self-delivery theranostic chimeric peptide CMP-PpIX is designed for simultaneously targeted photodynamic therapy (PDT) of tumor and real-time therapeutic feedback. Self-assembled CMP-PpIX nanoparticles can effectively accumulate in tumor by enhanced permeability and retention effect without additional vector. And this chimeric peptide CMP-PpIX has low background fluorescence, which is due to its relatively high intramolecular Förster resonance energy transfer (FRET) quenching efficiency between 5(6)-carboxyfluorescein (FAM) and 4-(dimethylaminoazo)-benzene-4-carboxylic acid (Dabcyl). More importantly, CMP-PpIX can be anchored on the tumor cell membrane for more than 8 h. Under irradiation, reactive oxygen species produced by CMP-PpIX directly damage cell membrane and rapidly induce apoptosis, which significantly improve the efficacy of PDT in vitro and in vivo. Then, peptide sequence Asp-Glu-Val-Asp (DEVD) is subsequently cleaved by activated caspase-3 and activated caspase-7, which separates the FAM and Dabcyl and terminates the FRET process. Therefore, fluorescence of FAM is recovered to monitor the expression of activated caspase-3 in vitro and in vivo to feedback real-time PDT therapeutic efficacy. In general, a novel cell membrane-targeted self-delivery theranostic chimeric peptide offers new promise for effective imaging-guided PDT.

Stimuli-responsive nanoparticle-assisted immunotherapy: a new weapon against solid tumours

The interplay between photo-thermal therapy and immunotherapy allows the realization of new nanotechnology-based cancer treatments for solid tumors.

Delivery of Nanoparticle-Based Radiosensitizers for Radiotherapy Applications

Nanoparticle-based radiosensitization of cancerous cells is evolving as a favorable modality for enhancing radiotherapeutic ratio, and as an effective tool for increasing the outcome of concomitant chemoradiotherapy. Nevertheless, delivery of sufficient concentrations of nanoparticles (NPs) or nanoparticle-based radiosensitizers (NBRs) to the targeted tumor without or with limited systemic side effects on healthy tissues/organs remains a challenge that many investigators continue to explore. With current systemic intravenous delivery of a drug, even targeted nanoparticles with great prospect of reaching targeted distant tumor sites, only a portion of the administered NPs/drug dosage can reach the tumor, despite the enhanced permeability and retention (EPR) effect. The rest of the targeted NPs/drug remain in systemic circulation, resulting in systemic toxicity, which can decrease the general health of patients. However, the dose from ionizing radiation is generally delivered across normal tissues to the tumor cells (especially external beam radiotherapy), which limits dose escalation, making radiotherapy (RT) somewhat unsafe for some diseased sites despite the emerging development in RT equipment and technologies. Since radiation cannot discriminate healthy tissue from diseased tissue, the radiation doses delivered across healthy tissues (even with nanoparticles delivered via systemic administration) are likely to increase injury to normal tissues by accelerating DNA damage, thereby creating free radicals that can result in secondary tumors. As a result, other delivery routes, such as inhalation of nanoparticles (for lung cancers), localized delivery via intratumoral injection, and implants loaded with nanoparticles for local radiosensitization, have been studied. Herein, we review the current NP delivery techniques; precise systemic delivery (injection/infusion and inhalation), and localized delivery (intratumoral injection and local implants) of NBRs/NPs. The current challenges, opportunities, and future prospects for delivery of nanoparticle-based radiosensitizers are also discussed.

Single-Stranded DNA-Packaged Polyplex Micelle as Adeno-Associated-Virus-Inspired Compact Vector to Systemically Target Stroma-Rich Pancreatic Cancer

Despite the rigidity of double-stranded DNA (dsDNA), its packaging is used to construct nonviral gene carriers due to its availability and the importance of its double-helix to elicit transcription. However, there is an increasing demand for more compact-sized carriers to facilitate tissue penetration, which may be easily fulfilled by using the more flexible single-stranded DNA (ssDNA) as an alternative template. Inspired by the adeno-associated virus (AAV) as a prime example of a transcriptionally active ssDNA system, we considered a methodology that can capture unpaired ssDNA within the polyplex micelle system (PM), an assembly of DNA and poly(ethylene glycol)-b-poly(l-lysine) (PEG-PLys). A micellar assembly retaining unpaired ssDNA was prepared by unpairing linearized pDNA with heat and performing polyion complexation on site with PEG-PLys. The PM thus formed had a compact and spherical shape, which was distinguishable from the rod-shaped PM formed from dsDNA, and still retained its ability to activate gene expression. Furthermore, we demonstrated that its capacity to encapsulate DNA was much higher than AAV, thereby potentially allowing the delivery of a larger variety of protein-encoding DNA. These features permit the ssDNA-loaded PM to easily penetrate the size-restricting stromal barrier after systemic application. Further, they can elicit gene expression in tumor cell nests of an intractable pancreatic cancer mouse model to achieve antitumor effects through suicide gene therapy. Thus, single-stranded DNA-packaged PM is appealing as a potential gene vector to tackle intractable diseases, particularly those with target delivery issues due to size-restriction barriers.

Nano-Enhanced Drug Delivery and Therapeutic Ultrasound for Cancer Treatment and Beyond

While ultrasound is most widely known for its use in diagnostic imaging, the energy carried by ultrasound waves can be utilized to influence cell function and drug delivery. Consequently, our ability to use ultrasound energy at a given intensity unlocks the opportunity to use the ultrasound for therapeutic applications. Indeed, in the last decade ultrasound-based therapies have emerged with promising treatment modalities for several medical conditions. More recently, ultrasound in combination with nanomedicines, i.e., nanoparticles, has been shown to have substantial potential to enhance the efficacy of many treatments including cancer, Alzheimer disease or osteoarthritis. The concept of ultrasound combined with drug delivery is still in its infancy and more research is needed to unfold the mechanisms and interactions of ultrasound with different nanoparticles types and with various cell types. Here we present the state-of-art in ultrasound and ultrasound-assisted drug delivery with a particular focus on cancer treatments. Notably, this review discusses the application of high intensity focus ultrasound for non-invasive tumor ablation and immunomodulatory effects of ultrasound, as well as the efficacy of nanoparticle-enhanced ultrasound therapies for different medical conditions. Furthermore, this review presents safety considerations related to ultrasound technology and gives recommendations in the context of system design and operation.

Liposomal Nanostructures for Drug Delivery in Gastrointestinal Cancers

Gastrointestinal (GI) cancers like liver, pancreatic, colorectal, and gastric cancer remain some of the most difficult and aggressive cancers. Nanoparticles like liposomes had been approved in the clinic for cancer therapy dating as far back as 1995. Over the years, liposomal formulations have come a long way, facing several roadblocks and failures, and advancing by optimizing formulations and incorporating novel design approaches to navigate therapeutic delivery challenges. The first liposomal formulation for a GI cancer drug was approved recently in 2015, setting the stage for further clinical developments of liposome-based delivery systems for therapies against GI malignancies. This article reviews the design considerations and strategies that can be used to deliver drugs to GI tumors, the wide range of therapeutic agents that have been explored in preclinical as well as clinical studies, and the current therapies that are being investigated in the clinic against GI malignancies.

Enhancing Tumor Drug Distribution With Ultrasound-Triggered Nanobubbles

Issues with limited intratumoral drug penetration and heterogeneous drug distribution continue to impede the therapeutic efficacy of nanomedicine-based delivery systems. Ultrasound (US)-enhanced drug delivery has emerged as one effective means of overcoming these challenges. Acoustic cavitation in the presence of nanoparticles has shown to increase the cellular uptake and distribution of chemotherapeutic agents in vivo. In this study, we investigated the potential of a drug-loaded echogenic nanoscale bubbles in combination with low frequency (3 MHz), high energy (2 W/cm2) US for antitumor therapy. The doxorubicin-loaded nanobubbles (Dox-NBs) stabilized with an interpenetrating polymer mesh were 171.5 ± 20.9 nm in diameter. When used in combination with therapeutic US, Dox-NBs combined with free drug showed significantly higher (*p < 0.05) intracellular uptake and therapeutic efficacy compared with free drug. When injected intravenously in vivo, Dox-NBs + therapeutic US showed significantly higher (*p < 0.05) accumulation and better distribution of Dox in tumors when compared with free drug. This strategy provides an effective and simple method to increase the local dose and distribution of otherwise systemically toxic chemotherapeutic agents for cancer therapies.

On-Chip Preparation of Amphiphilic Nanomicelles-in-Sodium Alginate Spheroids as a Novel Platform Against Triple-Negative Human Breast Cancer Cells: Fabrication, Study of Microfluidics Flow Hydrodynamics and Proof of Concept for Anticancer and Drug Delivery Applications

Spheroidal microparticles versatility as a drug carrier makes it a real workhorse in drug delivery applications. Despite of their long history, few research publications emphasize on how to improve their potential targeting ability, production rate, and dissolution characteristics. The current research presents an example of the combined state of the art of nano- and microparticles development technologies. Here in a novel on-chip, microfluidics approach is developed for encapsulating amphiphilic nanomicelles-in-sodium alginate spheroid. The designed nano-in-micro drug delivery system revealed a superior cytotoxicity against triple-negative human breast cancer cell line (MDA-MB-231), besides, a more sustained release of the drug. Hydrodynamics of the designed microchip was also investigated as a function of different flow rates with an insight on the dimensionless numbers; capillary number and Weber number throughout the microchannels. Our study confirmed the efficient encapsulation of nanomicelles within the alginate shell. The current microfluidics approach can be efficiently applied for uniform production of nano-in-microparticles with potential anticancer capability.

Seeing Better and Going Deeper in Cancer Nanotheranostics

Biomedical imaging modalities in clinical practice have revolutionized oncology for several decades. State-of-the-art biomedical techniques allow visualizing both normal physiological and pathological architectures of the human body. The use of nanoparticles (NP) as contrast agents enabled visualization of refined contrast images with superior resolution, which assists clinicians in more accurate diagnoses and in planning appropriate therapy. These desirable features are due to the ability of NPs to carry high payloads (contrast agents or drugs), increased in vivo half-life, and disease-specific accumulation. We review the various NP-based interventions for treatments of deep-seated tumors, involving "seeing better" to precisely visualize early diagnosis and "going deeper" to activate selective therapeutics in situ.

Morphophenotypic classification of tumor organoids as an indicator of drug exposure and penetration potential

The dynamics of tumor progression is driven by multiple factors, which can be exogenous to the tumor (microenvironment) or intrinsic (genetic, epigenetic or due to intercellular interactions). While tumor heterogeneity has been extensively studied on the level of cell genetic profiles or cellular composition, tumor morphological diversity has not been given as much attention. The limited analysis of tumor morphophenotypes may be attributed to the lack of accurate models, both experimental and computational, capable of capturing changes in tumor morphology with fine levels of spatial detail. Using a three-dimensional, agent-based, lattice-free computational model, we generated a library of multicellular tumor organoids, the experimental analogues of in vivo tumors. By varying three biologically relevant parameters-cell radius, cell division age and cell sensitivity to contact inhibition, we showed that tumor organoids with similar growth dynamics can express distinct morphologies and possess diverse cellular compositions. Taking advantage of the high-resolution of computational modeling, we applied the quantitative measures of compactness and accessible surface area, concepts that originated from the structural biology of proteins. Based on these analyses, we demonstrated that tumor organoids with similar sizes may differ in features associated with drug effectiveness, such as potential exposure to the drug or the extent of drug penetration. Both these characteristics might lead to major differences in tumor organoid's response to therapy. This indicates that therapeutic protocols should not be based solely on tumor size, but take into account additional tumor features, such as their morphology or cellular packing density.

Use of magnetic fields and nanoparticles to trigger drug release and improve tumor targeting

Drug delivery strategies aim to maximize a drug's therapeutic index by increasing the concentration of drug at target sites while minimizing delivery to off-target tissues. Because biological tissues are minimally responsive to magnetic fields, there has been a great deal of interest in using magnetic nanoparticles in combination with applied magnetic fields to selectively control the accumulation and release of drug in target tissues while minimizing the impact on surrounding tissue. In particular, spatially variant magnetic fields have been used to encourage accumulation of drug-loaded magnetic nanoparticles at target sites, while time-variant magnetic fields have been used to induce drug release from thermally sensitive nanocarriers. In this review, we discuss nanoparticle formulations and approaches that have been developed for magnetic targeting and/or magnetically induced drug release, as well as ongoing challenges in using magnetism for therapeutic applications. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Strategizing biodegradable polymeric nanoparticles to cross the biological barriers for cancer targeting

The biological barriers in the body have been fabricated by nature to protect the body from foreign molecules. The successful delivery of drugs is limited and being challenged by these biological barriers including the gastrointestinal tract, brain, skin, lungs, nose, mouth mucosa, and immune system. In this review article, we envisage to understand the functionalities of these barriers and revealing various drug-loaded biodegradable polymeric nanoparticles to overcome these barriers and deliver the entrapped drugs to cancer targeted site. Apart from it, tissue-specific multifunctional ligands, linkers and transporters when employed imparts an effective active delivery strategy by receptor-mediated transcytosis. Together, these strategies enable to deliver various drugs across the biological membranes for the treatment of solid tumors and malignant cancer.

Gold nanorods: from anisotropy to opportunity. An evolution update

Gold nanoparticles have drawn attention to nanomedicine for many years due to their physicochemical properties, which include: good stability; biocompatibility; easy surface chemistry and superior magnetic; and last, electronic properties. All of these properties distinguish gold nanoparticles as advantageous carriers to be exploited. The challenge to develop new gold nanostructures has led to anisotropy, a new property to exploit for various medical applications: diagnostic and imaging strategies as well as therapeutic options. Gold nanorods are the most studied anisotropic gold nanoparticles because of the presence of two absorption peaks according to their longitudinal and transversal plasmon resonances. The longitudinal surface plasmonic resonance can provide the absorption in the near-infrared region and this is an important aspect of using gold nanorods for medical purposes.

Fluorescence Guidance in Surgical Oncology: Challenges, Opportunities, and Translation

Surgical resection continues to function as the primary treatment option for most solid tumors. However, the detection of cancerous tissue remains predominantly subjective and reliant on the expertise of the surgeon. Surgery that is guided by fluorescence imaging has shown clinical relevance as a new approach to detecting the primary tumor, tumor margins, and metastatic lymph nodes. It is a technique to reduce recurrence and increase the possibility of a curative resection. While significant progress has been made in developing this emerging technology as a tool to assist the surgeon, further improvements are still necessary. Refining imaging agents and tumor targeting strategies to be a precise and reliable surgical strategy is essential in order to translate this technology into patient care settings. This review seeks to provide a comprehensive update on the most recent progress of fluorescence-guided surgery and its translation into the clinic. By highlighting the current status and recent developments of fluorescence image-guided surgery in the field of surgical oncology, we aim to offer insight into the challenges and opportunities that require further investigation.

MIX2: A Novel Natural Multi-Component Modulator of Multidrug-Resistance and Hallmarks of Cancer Cells

Multidrug resistance is one of the key barriers suppressing the effectiveness of drug therapies of malignant tumors. Here, we report a study on the effect of a mix of natural extracts (MIX2) prepared from fresh fruits of Prunus spinosa, Crataegus monogyna, Sorbus aucuparia, and Euonymus europaeus on the classic hallmarks of cancer cells and the expression of multidrug resistance proteins. In the studies, HeLa and T98G cell lines, and classic methods of molecular biology, including RT-qPCR, Western blot, flow cytometry, and confocal imaging, were used. Additionally, migration, adhesion, and proliferation assays were performed. The obtained results indicate that the MIX2 cocktail presents strong anti-cancer properties. MIX2 is not toxic, but at the same time significantly alters the migration, proliferation, and adhesion of tumor cells. Furthermore, it was found that cells exposed to the mixture presented a significantly reduced expression level of genes associated with MDR, including ABCB1, which encodes for glycoprotein P. In vitro data showed that MIX2 effectively sensitizes tumor cells to doxorubicin. We postulate that modulation of the multidrug resistance phenotype of tumors with the use of MIX2 may be considered as a safe and applicable tool in sustaining drug delivery therapies of malignancies.

Chemoresistance and the Self-Maintaining Tumor Microenvironment

The progression of cancer is associated with alterations in the tumor microenvironment, including changes in extracellular matrix (ECM) composition, matrix rigidity, hypervascularization, hypoxia, and paracrine factors. One key malignant phenotype of cancer cells is their ability to resist chemotherapeutics, and elements of the ECM can promote chemoresistance in cancer cells through a variety of signaling pathways, inducing changes in gene expression and protein activity that allow resistance. Furthermore, the ECM is maintained as an environment that facilitates chemoresistance, since its constitution modulates the phenotype of cancer-associated cells, which themselves affect the microenvironment. In this review, we discuss how the properties of the tumor microenvironment promote chemoresistance in cancer cells, and the interplay between these external stimuli. We focus on both the response of cancer cells to the external environment, as well as the maintenance of the external environment, and how a chemoresistant phenotype emerges from the complex signaling network present.

Microbubble-Mediated Delivery for Cancer Therapy

Despite an overall improvement in survival rates for cancer, certain resistant forms of the disease still impose a significant burden on patients and healthcare systems. Standard chemotherapy in these cases is often ineffective and/or gives rise to severe side effects. Targeted delivery of chemotherapeutics could improve both tumour response and patient experience. Hence, there is an urgent need to develop effective methods for this. Ultrasound is an established technique in both diagnosis and therapy. Its use in conjunction with microbubbles is being actively researched for the targeted delivery of small-molecule drugs. In this review, we cover the methods by which ultrasound and microbubbles can be used to overcome tumour barriers to cancer therapy.

Prior anti-CAFs break down the CAFs barrier and improve accumulation of docetaxel micelles in tumor

BACKGROUND

Abnormal expression of stromal cells and extracellular matrix in tumor stroma creates a tight barrier, leading to insufficient extravasation and penetration of therapeutic agents. Cancer-associated fibroblasts (CAFs) take on pivotal roles encouraging tumor progression.

METHOD

To surmount the refractoriness of stroma, we constructed a multi-targeting combined scenario of anti-CAFs agent tranilast and antitumor agent docetaxel micelles (DTX-Ms). Tranilast cut down crosstalk between tumor cells and stromal cells, ameliorated the tumor microenvironment, and enhanced the antiproliferation efficacy of DTX-Ms on cancer cells.

RESULTS

Diverse experiments demonstrated that tranilast enhanced DTX-Ms' antitumor effect in a two-stage pattern by CAFs ablation, tumor cell migration blocking, and metastasis inhibition. Along with activated CAFs decreasing in vivo, the two-stage therapy succeeded in reducing interstitial fluid pressure, normalizing microvessels, improving micelles penetration and retention, and inhibiting tumor growth and metastasis. Interestingly, tranilast alone failed to inhibit tumor growth in vivo, and it could only be used as an adjuvant medicine together with an antitumor agent.

CONCLUSION

Our proposed two-stage therapy offers a promising strategy to enhance antitumor effects by breaking down CAFs barrier and increasing micellar delivery efficiency.

Deepened cellular/subcellular interface penetration and enhanced antitumor efficacy of cyclic peptidic ligand-decorated accelerating active targeted nanomedicines

Introduction

Acceleration and improvement of penetration across cell-membrane interfaces of active targeted nanotherapeutics into tumor cells would improve tumor-therapy efficacy by overcoming the issue of poor drug penetration. Cell-penetrating peptides, especially synthetic polyarginine, have shown promise in facilitating cargo delivery. However, it is unknown whether polyarginine can work to overcome the membrane interface in an inserted pattern for cyclic peptide ligand-mediated active targeting drug delivery. Here, we conducted a study to test the hypothesis that tandem-insert nona-arginine (tiR₉) can act as an accelerating component for intracellular internalization, enhance cellular penetration, and promote antitumor efficacy of active targeted cyclic asparagine–glycine–arginine (cNGR)-decorated nanoliposomes.

Methods

Polyarginine was coupled with the polyethylene glycol (PEG) chain and the cNGR moiety, yielding a cNGR–tiR₉–PEG_2,000–distearoylphosphatidylethanolamine conjugate.

Results

The accelerating active targeted liposome (Lip) nanocarrier (cNGR-tiR₉-Lip–doxorubicin [Dox]) constructed in this study held suitable physiochemical features, such as appropriate particle size of ~150 nm and sustained-release profiles. Subsequently, tiR₉ was shown to enhance cellular drug delivery of Dox-loaded active targeted systems (cNGR-Lip-Dox) significantly. Layer-by-layer confocal microscopy indicated that the tandem-insert polyarginine accelerated active targeted system entry into deeper intracellular regions based on observations at marginal and center locations. tiR₉ enhanced the penetration depth of cNGR-Lip–coumarin 6 through subcellular membrane barriers and caused its specific accumulation in mitochondria, endoplasmic reticulum, and Golgi apparatus. It was also obvious that cNGR-tiR₉-Lip-Dox induced enhanced apoptosis and activated caspase 3/7. Moreover, compared with cNGR-Lip-Dox, cNGR-tiR₉-Lip-Dox induced a significantly higher antiproliferative effect and markedly suppressed tumor growth in HT1080-bearing nude mice.

Conclusion

This active tumor-targeting nanocarrier incorporating a tandem-insert polyarginine (tiR₉) as an accelerating motif shows promise as an effective drug-delivery system to accelerate translocation of drugs across tumor-cell/subcellular membrane barriers to achieve improved specific tumor therapy.

Investigation on the effect of nanoparticle size on the blood-brain tumour barrier permeability by in situ perfusion via internal carotid artery in mice

The blood-brain barrier (BBB) is a limiting factor in nanoparticle drug delivery to the brain, and various attempts have been made to overcome it for efficient drug delivery. Nowadays, it was considered as further issue for brain-drug delivery that the nanoparticle delivered to brain through the BBB reach cancer cells in tumour tissue. In this study, we investigated the effect of nanoparticle size on blood-brain tumour barrier (BBTB) permeation of fluorescence-labelled gold nanoparticles (AuNPs) in a mouse model of orthotopic glioblastoma multiforme (GBM), established by intracranial implantation of luciferase-expressing human glioblastoma U87MG cells. AuNPs sized 10, 50, and 100 nm were perfused into the GBM mice via internal carotid artery (ICA) for 5 min. Immediately after perfusion, the brains were fixed and prepared for LSCM observation. The AuNPs distribution in the normal and tumorous brain tissues was analysed qualitatively and quantitatively. Higher distribution of AuNPs was observed in the tumorous tissue than in the normal tissue. Furthermore, the smallest nanoparticle, 10 nm AuNPs, was widely distributed in the brain tumour tissue, whereas the 50 and 100 nm AuNPs were located near the blood vessels. Therefore, nanoparticle size affected the permeation of nanoparticles from the blood into brain tumour tissue.

Impact of the hypoxic phenotype on the uptake and efflux of nanoparticles by human breast cancer cells

Breast cancer cells adapt to the hypoxic tumoral environment by undergoing changes in metabolism, cell signalling, endo-lysosomal receptor uptake and recycling. The resulting hypoxic cell phenotype has the potential to undermine the therapeutic efficacy of nanomedicines designed for endocytic uptake and specific intracellular trafficking. The aim of this study was to examine the impact of hypoxia and simulated reperfusion on the in vitro uptake and release of nanomedicines by human breast cancer cells. Cells were exposed to a hypoxic preconditioning treatment in 1% oxygen for 6 and 24 hours to induce temporal changes in the hypoxic circuit (e.g. HIF-1α expression). The preconditioned cells were then dosed with nanoparticles for 45 or 180 minutes emulating nanomedicine access following tumor reperfusion. Hypoxic preconditioning significantly increased nanoparticle retention by up to 10% when compared to normoxic cultures, with the greatest relative difference between normoxic and hypoxic cultures occurring with a 45 minute dosing interval. Exocytosis studies indicated that the preconditioned cells had a significantly increased nanoparticle efflux (up to 9%) when compared to normoxic cells. Overall, we were able to show that hypoxic preconditioning regulates both the endocytosis and exocytosis of nanomedicines in human breast cancer cells.

A novel 3D breast-cancer-on-chip platform for therapeutic evaluation of drug delivery systems

The ability to rapidly screen drugs and drug delivery systems with a more accurate tumor model to better predict their in vivo performance is of great importance in drug development, because there have been some limitations in currently used tumor models. To address this problem, we developed an in vitro breast tumor model on a chip, composed of a microvessel wall, the extracellular matrix (ECM) and uniformly sized multicellular tumor spheroids (MCTS), for the evaluation of nanoparticle-based drug delivery systems. A carbon dots (CDs)-based drug delivery system was synthesized as a model to evaluate the real-time monitoring ability of the system transport through the endothelium and the penetrability into MCTS with a high spatio-temporal resolution on the established platform. Moreover, a modified 96-well plate was used to hold the microfluidic devices for in situ cytotoxicity assays of the MCTS by a microplate reader. Our findings revealed that the synthesized drug delivery system could be transported across an endothelial monolayer within 3 h and was nontoxic to the cells throughout the experiment. In addition, we demonstrated the capabilities of this model by assessing the delivery and efficacy of the drug delivery system in BT549 and T47D spheroids, two cell lines representative of triple negative breast cancer (TNBC) and non-TNBC, respectively. This microfluidic platform enables evaluation of dynamic transport behavior and in situ cytotoxicity evaluation in one system. The established platform provides a more accurate and low-cost in vitro model for rapid drug screening in pre-clinical studies.

Spatially Uniform Tumor Treatment and Drug Penetration by Regulating Ultrasound with Microbubbles

Tumor microenvironment has different morphologies of vessels in the core and rim regions, which influences the efficacy of tumor therapy. Our study proposed to improve the spatial uniformity of the antivascular effect and drug penetration within the tumor core and rim in combination therapies by regulating ultrasound-stimulated microbubble destruction (USMD). Focused ultrasound at 2 MHz and lipid-shell microbubbles (1.12 ± 0.08 μm, mean ± standard deviation) were used to perform USMD. The efficiency of the antivascular effect was evaluated by intravital imaging to determine the optimal USMD parameters. Tumor perfusion and histological alterations in the tumor core and rim were used to analyze the spatial uniformity of the antivascular effect and liposomal-doxorubicin (5 mg/kg) penetration in the combination therapy. Tumor vessels of specific sizes were disrupted by regulating USMD: vessels with sizes of 11 ± 3, 14 ± 5, 19 ± 7, and 23 ± 10 μm were disrupted by stimulation at acoustic pressures of 3, 5, 7, and 9 MPa, respectively (each p < 0.05). The effective treatment time of USMD (at 2 × 10⁷ microbubbles/mouse, 7 MPa, and three cycles) was 60-120 min, which resulted in the disruption of 21-44% of vessels smaller than 50 μm. The reductions in perfusion and vascular density after combination therapy did not differ significantly between the tumor core and rim. This study found that regulating USMD can result in homogeneous antivascular effects and drug penetration within tumors and thereby improve the efficacy of combination therapies.

Synthesis, Positron Emission Tomography Imaging, and Therapy of Diabody Targeted Drug Lipid Nanoparticles in a Prostate Cancer Murine Model

The blood clearance of chemotherapeutic drugs such as doxorubicin (Dox) can be extended by incorporation into lipid nanoparticles (LNPs) and further improved by tumor targeting with antibody fragments. We used positron emission tomography (PET) imaging in a murine prostate cancer model to evaluate tumor targeting of LNPs incorporating Dox and antiprostate-specific membrane antigen (PSMA) diabodies. Dox-LNPs were generated by mixing or covalent attachment to water soluble distearoylphosphatidyl ethanolamine-polyethylene glycol (DSPE-PEG)₂₀₀₀. Cu-64 PET imaging was performed with DOTA-conjugated Dox, PEG-LNP, or an anti-PSMA site-specific cysteine-diabody. Since the mixture Dox+PEG-LNP was unstable in serum, further studies utilized Dox covalently bound to LNP ± covalently bound DOTA-cys-diabody (cys-DB)-LNP. Blood clearance of covalent Dox-PEG-LNP was slower than Dox alone or Dox+PEG-LNP. PET imaging of ⁶⁴Cu-DOTA-Dox-PEG-LNP reached a maximum of 10% ID/g in tumors compared with 3% ID/g of ⁶⁴Cu-DOTA-Dox, due to the prolonged blood clearance. Mixing ⁶⁴Cu-DOTA-cys-DB-PEG-LNP with covalent Dox-PEG-LNP gave LNPs containing both drug and tumor targeting cys-DB. The mixed LNPs exhibited increased tumor uptake (15% ID/g) versus untargeted ⁶⁴Cu-DOTA-Dox-PEG-LNPs (10% ID/g) demonstrating feasibility of the approach. Based on these results, a therapy study with mixed LNPs containing cys-DB-LNP and either Dox-LNP or the antitubulin drug auristatin-LNP showed significant reduction of tumor growth with the auristatin-diabody-LNP mixture, but not the Dox-diabody-LNP mixture.

Strategies to improve tumor penetration of nanomedicines through nanoparticle design

Nanoparticles (NPs) have emerged as an effective means to deliver therapeutic drugs for cancer treatment, as they can preferentially accumulate at tumor site through the enhanced permeability and retention effect. Various forms of NPs including liposomes, polymeric micelles, and inorganic particles have been used for therapeutic applications. However, the therapeutic benefits of nanomedicines are suboptimal. Although many possible reasons may account for the compromised therapeutic efficacy, the inefficient tumor penetration can be a vital obstacle. Tumor develops characteristic pathological environment, such as abnormal vasculature, elevated interstitial fluid pressure, and dense extracellular matrix, which intrinsically hinder the transport of nanomedicines in the tumor parenchyma. The physicochemical properties of the NPs such as size, shape, and surface charge have profound effect on tumor penetration. In this review, we will highlight the factors that affect the transport of NPs in solid tumor, and then elaborate on designing strategies to improve NPs' penetration and uniform distribution inside the tumor interstitium. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.