TRAIL-coated leukocytes that prevent the bloodborne metastasis of prostate cancer

Liquid biopsy in lung cancer: The role of circulating tumor cells in diagnosis, treatment, and prognosis

Despite numerous therapeutic advancements, such as immune checkpoint inhibitors, lung cancer continues to be the leading cause of cancer-related mortality. Therefore, the identification of cancer at an early stage is becoming a significant subject in contemporary oncology. Despite significant advancements in early detection tactics in recent decades, they continue to provide challenges because of the inconspicuous symptoms observed during the early stages of the primary tumor. Presently, tumor biomarkers and imaging techniques are extensively employed across different forms of cancer. Nevertheless, every approach has its own set of constraints. In certain instances, the detriments outweigh the advantages. Hence, there is an urgent need to enhance early detection methods. Currently, liquid biopsy is considered more flexible and not intrusive method in comparison to conventional test for early detection. Circulating tumor cells (CTCs) are crucial components of liquid biopsy and have a pivotal function in the spread and formation of secondary tumors. These indicators show great promise in the early identification of cancer. This study presents a comprehensive examination of the methodologies employed for the isolation and enrichment of circulating tumor cells (CTCs) in lung cancer. Additionally, it explores the formation of clusters of CTCs, which have a pivotal function in facilitating the effective dissemination of cancer to distant organs. In addition, we discuss the importance of CTCs in the detection, treatment, and prognosis of lung cancer.

Cell-mediated nanoparticle delivery systems: towards precision nanomedicine

Cell-mediated nanoparticle delivery systems (CMNDDs) utilize cells as carriers to deliver the drug-loaded nanoparticles. Unlike the traditional nanoparticle drug delivery approaches, CMNDDs take the advantages of cell characteristics, such as the homing capabilities of stem cells, inflammatory chemotaxis of neutrophils, prolonged blood circulation of red blood cells, and internalization of macrophages. Subsequently, CMNDDs can easily prolong the blood circulation, cross biological barriers, such as the blood-brain barrier and the bone marrow-blood barrier, and rapidly arrive at the diseased areas. Such advantageous properties make CMNDDs promising delivery candidates for precision targeting. In this review, we summarize the recent advances in CMNDDs fabrication and biomedical applications. Specifically, ligand-receptor interactions, non-covalent interactions, covalent interactions, and internalization are commonly applied in constructing CMNDDs in vitro. By hitchhiking cells, such as macrophages, red blood cells, monocytes, neutrophils, and platelets, nanoparticles can be internalized or attached to cells to construct CMNDDs in vivo. Then we highlight the recent application of CMNDDs in treating different diseases, such as cancer, central nervous system disorders, lung diseases, and cardiovascular diseases, with a brief discussion about challenges and future perspectives in the end.

Harnessing cells to improve transport of nanomedicines

Efficient tumour treatment is hampered by the poor selectivity of anticancer drugs, resulting in scarce tumour accumulation and undesired off-target effects. Nano-sized drug-delivery systems in the form of nanoparticles (NPs) have been proposed to improve drug distribution to solid tumours, by virtue of their ability of passive and active tumour targeting. Despite these advantages, literature studies indicated that less than 1% of the administered NPs can successfully reach the tumour mass, highlighting the necessity for more efficient drug transporters in cancer treatment. Living cells, such as blood cells, circulating immune cells, platelets, and stem cells, are often found as an infiltrating component in most solid tumours, because of their ability to naturally circumvent immune recognition, bypass biological barriers, and reach inaccessible tissues through innate tropism and active motility. Therefore, the tumour-homing ability of these cells can be harnessed to design living cell carriers able to improve the transport of drugs and NPs to tumours. Albeit promising, this approach is still in its beginnings and suffers from difficult scalability, high cost, and poor reproducibility. In this review, we present an overview of the most common cell transporters of drugs and NPs, and we discuss how different cell types interact with biological barriers to deliver cargoes of various natures to tumours. Finally, we analyse the different techniques used to load drugs or NPs in living cells and discuss their advantages and disadvantages.

Retention of E-selectin functionalized liposome fanny packs on Jurkat cells following invasion through collagen

Circulating immune cells are an appealing candidate to serve as carriers of therapeutic cargo via nanoparticles conjugated to their surface, for several reasons: these cells are highly migratory and can squeeze through small pores of diameter smaller than their resting size; they are easily accessible in the peripheral blood via minimally invasive IV injection of particles, or can be harvested, processed ex vivo, and reintroduced to the body; they are adept at traveling through the circulation with minimal destruction and thus have access to various tissue beds of the body; and immune cells have built-in signal transduction machinery which allows them to actively engage in chemotaxis and home to regions of the tissue containing tumors, invading microorganisms, or injuries in need of wound healing. In this study, we sought to examine and quantify the degree to which nanoscale liposomes, functionalized with E-selectin adhesion receptor, could bind to a model T cell line and remain on the surface of the cells as they migrate through collagen gels of varying density in a transwell cell migration chamber. It is demonstrated that physiological levels of fluid shear stress are necessary to achieve optimal binding of the E-selectin liposomes to the cell surface as expected, and that CD3/CD28 antibody activation of the T cells was not necessary for effective liposome binding. Nanoscale liposomes were successfully conveyed by the migrating cells across a layer of rat tail type 1 collagen gel ranging in composition from 1 to 3 mg/mL. The relative fraction of liposomes carried through the collagen decreased at higher collagen density, likely due to the expected decrease in average pore size, and increased fiber content in the gels. Taken together, these results support the idea that T cells could be an effective cellular carrier of therapeutic molecules either attached to the surface of nanoscale liposomes or encapsulated within their interior.

Harnessing tumor-derived exosomes: A promising approach for the expansion of clinical diagnosis, prognosis, and therapeutic outcome of prostate cancer

Prostate cancer is the second leading cause of men's death worldwide. Although early diagnosis and therapy for localized prostate cancer have improved, the majority of men with metastatic disease die from prostate cancer annually. Therefore, identification of the cellular-molecular mechanisms underlying the progression of prostate cancer is essential for overcoming controlled proliferation, invasion, and metastasis. Exosomes are small extracellular vesicles that mediate most cells' interactions and contain membrane proteins, cytosolic and nuclear proteins, extracellular matrix proteins, lipids, metabolites, and nucleic acids. Exosomes play an essential role in paracrine pathways, potentially influencing Prostate cancer progression through a wide variety of mechanisms. In the present review, we outline and discuss recent progress in our understanding of the role of exosomes in the Prostate cancer microenvironment, like their involvement in prostate cancer occurrence, progression, angiogenesis, epithelial-mesenchymal transition, metastasis, and drug resistance. We also present the latest findings regarding the function of exosomes as biomarkers, direct therapeutic targets in prostate cancer, and the challenges and advantages associated with using exosomes as natural carriers and in exosome-based immunotherapy. These findings are a promising avenue for the expansion of potential clinical approaches.

Spatial distribution of tumor-associated macrophages in an orthotopic prostate cancer mouse model

Mounting evidence suggests that the immune landscape within prostate tumors influences progression, metastasis, treatment response, and patient outcomes. In this study, we investigated the spatial density of innate immune cell populations within NOD.SCID orthotopic prostate cancer xenografts following microinjection of human DU145 prostate cancer cells. Our laboratory has previously developed nanoscale liposomes that attach to leukocytes via conjugated E-selectin (ES) and kill cancer cells via TNF-related apoptosis inducing ligand (TRAIL). Immunohistochemistry (IHC) staining was performed on tumor samples to identify and quantify leukocyte infiltration for different periods of tumor growth and E-selectin/TRAIL (EST) liposome treatments. We examined the spatial-temporal dynamics of three different immune cell types infiltrating tumors using QuPath image analysis software. IHC staining revealed that F4/80+ tumor-associated macrophages (TAMs) were the most abundant immune cells in all groups, irrespective of time or treatment. The density of TAMs decreased over the course of tumor growth and decreased in response to EST liposome treatments. Intratumoral versus marginal analysis showed a greater presence of TAMs in the marginal regions at 3 weeks of tumor growth which became more evenly distributed over time and in tumors treated with EST liposomes. TUNEL staining indicated that EST liposomes significantly increased cell apoptosis in treated tumors. Additionally, confocal microscopy identified liposome-coated TAMs in both the core and periphery of tumors, highlighting the ability of liposomes to infiltrate tumors by "piggybacking" on macrophages. The results of this study indicate that TAMs represent the majority of innate immune cells within NOD.SCID orthotopic prostate tumors, and spatial density varies widely as a function of tumor size, duration of tumor growth, and treatment of EST liposomes.

Tuning of TRAIL clustering on the surface of nanoscale liposomes by phase separation

Phase-separated liposomes were used to formulate tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a protein that selectively kills cancer cells while sparing most healthy ones. By controlling the average number of TRAIL molecules per liposome, we demonstrate the ability to tune the formation of TRAIL clusters and their resulting apoptotic activity.

Cell-Based Micro/Nano-Robots for Biomedical Applications: A Review

Micro/nano-robots are powerful tools for biomedical applications and are applied in disease diagnosis, tumor imaging, drug delivery, and targeted therapy. Among the various types of micro-robots, cell-based micro-robots exhibit unique properties because of their different cell sources. In combination with various actuation methods, particularly externally propelled methods, cell-based microrobots have enormous potential for biomedical applications. This review introduces recent progress and applications of cell-based micro/nano-robots. Different actuation methods for micro/nano-robots are summarized, and cell-based micro-robots with different cell templates are introduced. Furthermore, the review focuses on the combination of cell-based micro/nano-robots with precise control using different external fields. Potential challenges, further prospects, and clinical translations are also discussed.

Activation of Dendritic Cells Isolated from the Blood of Patients with Prostate Cancer by Ex Vivo Fluid Shear Stress Stimulation

Prostate cancer is one of the most common cancers among men in the United States and a leading cause of cancer-related death in men. Treatment options for patients with advanced prostate cancer include hormone therapies, chemotherapies, radioligand therapies, and immunotherapies. Provenge (sipuleucel-T) is an autologous cancer-vaccine-based immunotherapy approved for men with asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC). Administration of sipuleucel-T involves leukapheresis of patient blood to isolate antigen-presenting cells (APCs), including dendritic cells (DCs), and subsequent incubation of isolated APCs with both an antigen, prostatic acid phosphatase (PAP), and granulocyte macrophage-colony stimulating factor (GM-CSF) before their infusion back into the patient. Although sipuleucel-T has been shown to improve overall survival, other meaningful outcomes, such as prostate-specific antigen (PSA) levels and radiographic response, are inconsistent. This lack of robust response may be due to limited ex vivo activation of DCs using current protocols. Earlier studies have shown that many cell types can be activated ex vivo by external forces such as fluid shear stress (FSS). We hypothesize that novel fluid shear stress technologies and methods can be used to improve ex vivo efficacy of prostate cancer DC activation in prostate cancer. Herein, we report a new protocol for activating DCs from patients with prostate cancer using ex vivo fluid shear stress. Ultimately, the goal of these studies is to improve DC activation to expand the efficacy of therapies such as sipuleucel-T. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Sample collection and DC isolation Basic Protocol 2: Determination and application of fluid shear stress Basic Protocol 3: Flow cytometry analysis of DCs after FSS stimulation.

Dual Affinity Nanoparticles for the Transport of Therapeutics from Carrier Cells to Target Cells under Physiological Flow Conditions

In this study, a novel two-stage nanoparticle delivery platform was developed based on the dual functionalization of a liposome with moieties that have fundamentally different strengths of adhesion and binding kinetics. The essential concept of this system is that the nanoparticles are designed to loosely bind to the carrier cell until they come into contact with the target cell, to which they bind with greater strength. This allows the nanoparticle to be transferred from one cell to another, circulating for longer periods of time in the blood and delivering the therapeutic agent to the target circulating tumor cell. Liposomes were prepared using the lipid cake and extrusion technique, then functionalized with E-selectin (ES), anti-cell surface vimentin antibody fragments, and TRAIL via click chemistry. The binding of dual affinity (DA) liposomes was confirmed with the neutrophil-like cell line PLB985, the colorectal cancer cell line HCT116, and healthy granulocytes isolated from peripheral whole blood under physiologically relevant fluid shear stress (FSS) in a cone-and-plate viscometer. Transfer of the DA liposomes from PLB985 to HCT116 cells under FSS was greater compared to all of the control liposome formulations. Additionally, DA liposomes demonstrated enhanced apoptotic effects on HCT116 cells in whole blood under FSS, surpassing the efficacy of the ES/TRAIL liposomes previously developed by the King Lab.

Surface-Engineered Extracellular Vesicles in Cancer Immunotherapy

Extracellular vesicles (EVs) are lipid bilayer-enclosed bodies secreted by all cell types. EVs carry bioactive materials, such as proteins, lipids, metabolites, and nucleic acids, to communicate and elicit functional alterations and phenotypic changes in the counterpart stromal cells. In cancer, cells secrete EVs to shape a tumor-promoting niche. Tumor-secreted EVs mediate communications with immune cells that determine the fate of anti-tumor therapeutic effectiveness. Surface engineering of EVs has emerged as a promising tool for the modulation of tumor microenvironments for cancer immunotherapy. Modification of EVs' surface with various molecules, such as antibodies, peptides, and proteins, can enhance their targeting specificity, immunogenicity, biodistribution, and pharmacokinetics. The diverse approaches sought for engineering EV surfaces can be categorized as physical, chemical, and genetic engineering strategies. The choice of method depends on the specific application and desired outcome. Each has its advantages and disadvantages. This review lends a bird's-eye view of the recent progress in these approaches with respect to their rational implications in the immunomodulation of tumor microenvironments (TME) from pro-tumorigenic to anti-tumorigenic ones. The strategies for modulating TME using targeted EVs, their advantages, current limitations, and future directions are discussed.

Chemical Activation and Mechanical Sensitization of Piezo1 Enhance TRAIL-Mediated Apoptosis in Glioblastoma Cells

Glioblastoma multiforme (GBM), the most common and aggressive type of primary brain tumor, has a mean survival of less than 15 months after standard treatment. Treatment with the current standard of care, temozolomide (TMZ), may be ineffective if damaged tumor cells undergo DNA repair or acquire mutations that inactivate transcription factor p53. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) triggers apoptosis in multiple tumor types, while evading healthy cells, through a transcription-independent mechanism. GBM is particularly resistant to TRAIL, but studies have found that the mechanoreceptor Piezo1 can be activated under static conditions via Yoda1 agonist to induce TRAIL sensitization in other cancer cell lines. This study examines the effects and the mechanism of chemical and mechanical activation of Piezo1, via Yoda1 and fluid shear stress (FSS) stimulation, on TRAIL-mediated apoptosis in GBM cells. Here, we demonstrate that Yoda1 + TRAIL and FSS + TRAIL combination therapies significantly increase apoptosis in two GBM cell lines relative to controls. Further, cells known to be resistant to TMZ were found to have higher levels of Piezo1 expression and were more susceptible to TRAIL sensitization by Piezo1 activation. The combinatory Yoda1 + TRAIL treatment significantly decreased cell viability in TMZ-resistant GBM cells when compared to treatment with both low and high doses of TMZ. The results of this study suggest the potential of a highly specific and minimally invasive approach to overcome TMZ resistance in GBM by sensitizing cancer cells to TRAIL treatment via chemical or mechanical activation of Piezo1.

Recent Advances in the Development of Nanodelivery Systems Targeting the TRAIL Death Receptor Pathway

The TRAIL (TNF-related apoptosis-inducing ligand) apoptotic pathway is extensively exploited in the development of targeted antitumor therapy due to TRAIL specificity towards its cognate receptors, namely death receptors DR4 and DR5. Although therapies targeting the TRAIL pathway have encountered many obstacles in attempts at clinical implementation for cancer treatment, the unique features of the TRAIL signaling pathway continue to attract the attention of researchers. Special attention is paid to the design of novel nanoscaled delivery systems, primarily aimed at increasing the valency of the ligand for improved death receptor clustering that enhances apoptotic signaling. Optionally, complex nanoformulations can allow the encapsulation of several therapeutic molecules for a combined synergistic effect, for example, chemotherapeutic agents or photosensitizers. Scaffolds for the developed nanodelivery systems are fabricated by a wide range of conventional clinically approved materials and innovative ones, including metals, carbon, lipids, polymers, nanogels, protein nanocages, virus-based nanoparticles, dendrimers, DNA origami nanostructures, and their complex combinations. Most nanotherapeutics targeting the TRAIL pathway are aimed at tumor therapy and theranostics. However, given the wide spectrum of action of TRAIL due to its natural role in immune system homeostasis, other therapeutic areas are also involved, such as liver fibrosis, rheumatoid arthritis, Alzheimer's disease, and inflammatory diseases caused by bacterial infections. This review summarizes the recent innovative developments in the design of nanodelivery systems modified with TRAIL pathway-targeting ligands.

TRAIL in the Treatment of Cancer: From Soluble Cytokine to Nanosystems

The death ligand tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a member of the TNF cytokine superfamily, has long been recognized for its potential as a cancer therapeutic due to its low toxicity against normal cells. However, its translation into a therapeutic molecule has not been successful to date, due to its short in vivo half-life associated with insufficient tumor accumulation and resistance of tumor cells to TRAIL-induced killing. Nanotechnology has the capacity to offer solutions to these limitations. This review provides a perspective and a critical assessment of the most promising approaches to realize TRAIL's potential as an anticancer therapeutic, including the development of fusion constructs, encapsulation, nanoparticle functionalization and tumor-targeting, and discusses the current challenges and future perspectives.

Magnetically Actuated Cell-Robot System: Precise Control, Manipulation, and Multimode Conversion

Border-nearing microrobots with self-propelling and navigating capabilities have promising applications in micromanipulation and bioengineering, because they can stimulate the surrounding fluid flow for object transportation. However, ensuring the biosafety of microrobots is a concurrent challenge in bioengineering applications. Here, macrophage template-based microrobots (cell robots) that can be controlled individually or in chain-like swarms are proposed, which can transport various objects. The cell robots are constructed using the phagocytic ability of macrophages to load nanomagnetic particles while maintaining their viability. The robots exhibit high position control accuracy and generate a flow field that can be used to transport microspheres and sperm when exposed to an external magnetic field near a wall. The cell robots can also form chain-like swarms to transport a large object (more than 100 times the volume). This new insight into the manipulation of macrophage-based cell robots provides a new concept by converting other biological cells into microrobots for micromanipulation in biomedical applications.

Monocytes as a convergent nanoparticle therapeutic target for cardiovascular diseases

Due to the increasing population of individuals with cardiovascular diseases and related comorbidities, there is an increasing need for development of synergistic therapeutics. Monocytes are implicated in a broad spectrum of diseases and can serve as a focal point for therapeutic targeting. This review discusses the role of monocytes in cardiovascular diseases and highlights trends in monocyte targets nanoparticles in three cardiovascular-related diseases: Diabetes, Atherosclerosis, and HIV. Finally, the review offers perspectives on how to develop nanoparticle monocyte targeting strategies that can be beneficial for treating co-morbidities.

An albumin scaffold grafted with an alpha-helical motif delivers therapeutic payloads by modular coiled-coil assembly

A short in vivo half-life of protein-based therapeutics often restricts successful clinical translation despite their promising efficacy in vitro. As a biocompatible half-life extender, human serum albumin (HSA) has proven effective in some cases. While genetic fusion is well-established for interlinking HSA and a protein payload, it is limited to structurally simple proteins, necessitating new strategies to expand the utility of HSA for delivery of therapeutic proteins. Here, we report a novel HSA variant (eHSA) as a modular and long-acting carrier compatible with any protein payload of interest. The assembly between eHSA and a payload was driven by a heterodimeric coiled-coil interaction in which a short α-helix grafted onto HSA specifically bound to a complementary α-helix genetically fused to a payload. We showed various proteins including tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), single-chain TRAIL, or green fluorescent protein could piggyback onto eHSA via simple mixing without losing native activity. Additionally, either in presence or absence of a payload, eHSA was found to retain the pH-dependent FcRn-binding behavior - a critical attribute for prolonged survival in the systemic circulation. These results demonstrate eHSA would serve as a modular platform capable of delivering various therapeutic proteins with potentially long in vivo half-lives.

Overcoming biological barriers to improve solid tumor immunotherapy

Cancer immunotherapy has been at the forefront of therapeutic interventions for many different tumor types over the last decade. While the discovery of immunotherapeutics continues to occur at an accelerated rate, their translation is often hindered by a lack of strategies to deliver them specifically into solid tumors. Accordingly, significant scientific efforts have been dedicated to understanding the underlying mechanisms that govern their delivery into tumors and the subsequent immune modulation. In this review, we aim to summarize the efforts focused on overcoming tumor-associated biological barriers and enhancing the potency of immunotherapy. We summarize the current understanding of biological barriers that limit the entry of intravascularly administered immunotherapies into the tumors, in vitro techniques developed to investigate the underlying transport processes, and delivery strategies developed to overcome the barriers. Overall, we aim to provide the reader with a framework that guides the rational development of technologies for improved solid tumor immunotherapy.

Delivery technologies to engineer natural killer cells for cancer immunotherapy

In recent years, immune cell-based cancer therapeutics have been utilized broadly in the clinic. Through advances in cellular engineering, chimeric antigen receptor (CAR) T-cell therapies have demonstrated substantial success in treating hematological tumors and have become the most prominent cell-based therapy with three commercialized products in the market. However, T-cell-based immunotherapies have certain limitations, including a restriction to autologous cell sources to avoid severe side-effects caused by human leukocyte antigen (HLA) mismatch. This necessity for personalized treatment inevitably results in tremendous manufacturing and time costs, reducing accessibility for many patients. As an alternative strategy, natural killer (NK) cells have emerged as potential candidates for improved cell-based immunotherapies. NK cells are capable of killing cancer cells directly without requiring HLA matching. Furthermore, NK cell-based therapies can use various allogeneic cell sources, allowing for the possibility of "off-the-shelf" immunotherapies with reduced side-effects and shortened manufacturing times. Here we provide an overview of the use of NK cells in cancer immunotherapy, their current status in clinical trials, as well as the design and implementation of delivery technologies-including viral, non-viral, and nanoparticle-based approaches-for engineering NK cell-based immunotherapies.

TRAIL-coated leukocytes to kill circulating tumor cells in the flowing blood from prostate cancer patients

Background

Radical surgery is the first line treatment for localized prostate cancer (PC), however, several studies have demonstrated that surgical procedures induce tumor cell mobilization from the primary tumor into the bloodstream.

Methods

The number and temporal fluctuations of circulating tumor cells (CTC), cancer associated fibroblasts (CAF) and CTC cluster present in each blood sample was determined.

Results

The results show that both CTC and CTC cluster levels significantly increased immediately following primary tumor resection, but returned to baseline within 2 weeks post-surgery. In contrast, the CAF level decreased over time. In patients who experienced PC recurrence within months after resection, CTC, CAF, and cluster levels all increased over time. Based on this observation, we tested the efficacy of an experimental TNF-related apoptosis-inducing ligand (TRAIL)-based liposomal therapy ex-vivo to induce apoptosis in CTC in blood. The TRAIL-based therapy killed approximately 75% of single CTCs and CTC in cluster form.

Conclusion

Collectively, these data indicate that CTC cluster and CAF levels can be used as a predictive biomarker for cancer recurrence. Moreover, for the first time, we demonstrate the efficacy of our TRAIL-based liposomal therapy to target and kill prostate CTC in primary patient blood samples, suggesting a potential new adjuvant therapy to use in combination with surgery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08589-8.

Engineered Cytokines for Cancer and Autoimmune Disease Immunotherapy

Cytokine signaling is critical to a range of biological processes including cell development, tissue repair, aging, and immunity. In addition to acting as key signal mediators of the immune system, cytokines can also serve as potent immunotherapies with more than 20 recombinant products currently Food and Drug Administration (FDA)-approved to treat conditions including hepatitis, multiple sclerosis, arthritis, and various cancers. Yet despite their biological importance and clinical utility, cytokine immunotherapies suffer from intrinsic challenges that limit their therapeutic potential including poor circulation, systemic toxicity, and low tissue- or cell-specificity. In the past decade in particular, methods have been devised to engineer cytokines in order to overcome such challenges and here, the myriad strategies are reviewed that may be employed in order to improve the therapeutic potential of cytokine and chemokine immunotherapies with applications in cancer and autoimmune disease therapy, as well as tissue engineering and regenerative medicine. For clarity, these strategies are collected and presented as they vary across size scales, ranging from single amino acid substitutions, to larger protein-polymer conjugates, nano/micrometer-scale particles, and macroscale implants. Together, this work aims to provide readers with a timely view of the field of cytokine engineering with an emphasis on early-stage therapeutic approaches.

Taxanes Sensitize Prostate Cancer Cells to TRAIL-Induced Apoptotic Synergy via Endoplasmic Reticulum Stress

Docetaxel and cabazitaxel are guideline-chemotherapy treatments for metastatic castration-resistant prostate cancer (mCRPC), which comprises the majority of prostate cancer deaths. TNF-related apoptosis inducing ligand (TRAIL) is an anticancer agent that is selectively cytotoxic to cancer cells; however, many human cancers are resistant to TRAIL. In this study, we sensitized androgen-independent and TRAIL-resistant prostate cancer cells to TRAIL-mediated apoptosis via taxane therapy and examined the mechanism of sensitization. DU145 and PC3 cells displayed no significant reduction in cell viability when treated with soluble TRAIL, docetaxel, or cabazitaxel alone indicating that both cell lines are resistant to TRAIL and taxanes individually. Taxane and TRAIL combination synergistically amplified apoptosis strongly suggesting that taxanes sensitize prostate cancer cells to TRAIL. A Jun N-terminal kinases (JNK) inhibitor inhibited apoptosis in treated cells and significantly reduced death receptor expression indicating JNK activation by ER stress sensitizes PCa cells to TRAIL-induced apoptosis by upregulating DR4/DR5 expression. In addition, suppression of C/EBP homologous protein (CHOP) reduced TRAIL sensitization in both cell lines indicating that ER stress-related apoptosis is mediated, in part, by CHOP. Cytochrome c knockdown showed a significant decrease in sensitivity in PC3 cells, but not in Bax-deficient DU145 cells. A computational model was used to simulate apoptosis for cells treated with taxane and TRAIL therapy as demonstrated in in vitro experiments. Pretreatment with taxanes sensitized cells to apoptosis induced by TRAIL-mediated apoptosis, demonstrating that combining TRAIL with ER stress inducers is a promising therapy to reverse TRAIL resistance to treat mCRPC.

Regulation of Cancer Metastasis by TRAIL/Death Receptor Signaling

Death ligands such as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL; TNFSF10) and their corresponding death receptors (e.g., DR5) not only initiate apoptosis through activation of the extrinsic apoptotic pathway but also exert non-apoptotic biological functions such as regulation of inflammation and cancer metastasis. The involvement of the TRAIL/death receptor signaling pathway in the regulation of cancer invasion and metastasis is complex as both positive and negative roles have been reported. The underlying molecular mechanisms are even more complicated. This review will focus on discussing current knowledge in our understanding of the involvement of TRAIL/death receptor-mediated signaling in the regulation of cancer cell invasion and metastasis.

Delivery of cancer therapies by synthetic and bio-inspired nanovectors

BACKGROUND

As a complement to the clinical development of new anticancer molecules, innovations in therapeutic vectorization aim at solving issues related to tumor specificity and associated toxicities. Nanomedicine is a rapidly evolving field that offers various solutions to increase clinical efficacy and safety. MAIN: Here are presented the recent advances for different types of nanovectors of chemical and biological nature, to identify the best suited for translational research projects. These nanovectors include different types of chemically engineered nanoparticles that now come in many different flavors of 'smart' drug delivery systems. Alternatives with enhanced biocompatibility and a better adaptability to new types of therapeutic molecules are the cell-derived extracellular vesicles and micro-organism-derived oncolytic viruses, virus-like particles and bacterial minicells. In the first part of the review, we describe their main physical, chemical and biological properties and their potential for personalized modifications. The second part focuses on presenting the recent literature on the use of the different families of nanovectors to deliver anticancer molecules for chemotherapy, radiotherapy, nucleic acid-based therapy, modulation of the tumor microenvironment and immunotherapy.

CONCLUSION

This review will help the readers to better appreciate the complexity of available nanovectors and to identify the most fitting "type" for efficient and specific delivery of diverse anticancer therapies.

Peptide functionalized liposomes for receptor targeted cancer therapy

Most clinically approved cancer therapies are potent and toxic small molecules that are limited by severe off-target toxicities and poor tumor-specific localization. Over the past few decades, attempts have been made to load chemotherapies into liposomes, which act to deliver the therapeutic agent directly to the tumor. Although liposomal encapsulation has been shown to decrease toxicity in human patients, reliance on passive targeting via the enhanced permeability and retention (EPR) effect has left some of these issues unresolved. Recently, investigations into modifying the surface of liposomes via covalent and/or electrostatic functionalization have offered mechanisms for tumor homing and subsequently controlled chemotherapeutic delivery. A wide variety of biomolecules can be utilized to functionalize liposomes such as proteins, carbohydrates, and nucleic acids, which enable multiple directions for cancer cell localization. Importantly, when nanoparticles are modified with such molecules, care must be taken as not to inactivate or denature the ligand. Peptides, which are small proteins with <30 amino acids, have demonstrated the exceptional ability to act as ligands for transmembrane protein receptors overexpressed in many tumor phenotypes. Exploring this strategy offers a method in tumor targeting for cancers such as glioblastoma multiforme, pancreatic, lung, and breast based on the manifold of receptors overexpressed on various tumor cell populations. In this review, we offer a comprehensive summary of peptide-functionalized liposomes for receptor-targeted cancer therapy.

Micelle-in-Liposomes for Sustained Delivery of Anticancer Agents That Promote Potent TRAIL-Induced Cancer Cell Apoptosis

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) induces cancer cell-specific apoptosis and has garnered intense interest as a promising agent for cancer treatment. However, the development of TRAIL has been hampered in part because most human cancer cells are resistant to TRAIL. A few small molecules including natural compounds such as piperlongumine (PL) have been reported to sensitize cancer cells to TRAIL. We prepared a novel type of nanomaterial, micelle-in-liposomes (MILs) for solubilization and delivery of PL. PL-loaded MILs were used to sensitize cancer cells to TRAIL. As visualized by cryo-TEM, micelles were successfully loaded inside the aqueous core of liposomes. The MILs increased the water solubility of PL by ~20 fold. A sustained PL release from MILs in physiologically relevant buffer over 7 days was achieved, indicating that the liposomes prevented premature drug release from the micelles in the MILs. Also demonstrated is a potent synergistic apoptotic effect in cancer cells by PL MILs in conjunction with liposomal TRAIL. MILs provide a new formulation and delivery vehicle for hydrophobic anticancer agents, which can be used alone or in combination with TRAIL to promote cancer cell death.

Designed ferritin nanocages displaying trimeric TRAIL and tumor-targeting peptides confer superior anti-tumor efficacy

TRAIL is considered a promising target for cancer therapy because it mediates activation of the extrinsic apoptosis pathway in a tumor-specific manner by binding to and trimerizing its functional receptors, DR4 or DR5. Although recombinant human TRAIL has shown high potency and specificity for killing cancer cells in preclinical studies, it has failed in multiple clinical trials for several reasons, including a very short half-life mainly caused by instability of the monomeric form of TRAIL and rapid renal clearance of the off-targeted TRAIL. To overcome such obstacles, we developed a TRAIL-active trimer nanocage (TRAIL-ATNC) that presents the TRAIL ligand in its trimer-like conformation by connecting it to a triple helix sequence that links to the threefold axis of the ferritin nanocage. We also ligated the tumor-targeting peptide, IL4rP, to TRAIL-ATNC to enhance tumor targeting. The developed TRAIL-ATNCIL4rP showed enhanced agonistic activity compared with monomeric TRAIL. The in vivo serum half-life of TRAIL-ATNCIL4rP was ~ 16-times longer than that of native TRAIL. As a consequence of these properties, TRAIL-ATNCIL4rP exhibited efficacy as an anti-tumor agent in vivo against xenograft breast cancer as well as orthotopic pancreatic cancer models, highlighting the promise of this system for development as novel therapeutics against cancer.

When liposomes met antibodies: Drug delivery and beyond

Drug encapsulated liposomes and monoclonal antibodies (Mabs) are two distinctively different classes of therapeutics, but both aim to become the ultimate "magic bullet". While PEGylated liposomes rely on the enhanced permeability and retention (EPR) effect for accumulation in solid tumor tissues, Mabs are designed to bind tightly to specific surface antigens on target cells to exert effector functions. Immunoliposome (IL) refers to the structural combination of liposomes and antibodies, whereas the antibodies are usually decorated on the liposome surface. ILs can therefore take advantage of interactions between antibodies and cancer cells for more efficient endocytosis and intracellular drug delivery. The antibody structure, affinity, density, as well as the liposome surface properties and drug to lipid ratios all contribute to the IL pharmacokinetic(PK) and pharmacodynamic(PD) behaviors. The optimal formulation parameters may vary for different target cells and tissues. Furthermore, besides the delivery of cytotoxic drugs to cancer cells, new ILs are being developed to interact with multiple target receptors, multiple target cells and trigger multiple therapeutic effects. We envision that the IL format can be a great platform for the molecular engineering of multi-valent, multi-specific interactions to achieve complex biological functions for therapeutic benefits, especially in the area of cancer immunotherapy.

Chemotherapy-induced release of circulating-tumor cells into the bloodstream in collective migration units with cancer-associated fibroblasts in metastatic cancer patients

BACKGROUND

Recent studies have shown that chemotherapy destabilizes the blood vasculature and increases circulating tumor cell (CTC) influx into the circulation of metastatic cancer patients (Met-pa). CTCs are a precursor of cancer metastasis, in which they can migrate as single CTCs or as CTC clusters with stromal cells such as cancer-associated fibroblasts (CAFs) as cell aggregates.

METHODS

Blood samples were collected from 52 Met-pa, and the number of CTC and CAF was determined along with the temporal fluctuation of these through the chemotherapy treatment.

RESULTS

In this study, CTC level was found to increase two-fold from the initial level after 1 cycle of chemotherapy and returned to baseline after 2 cycles of chemotherapy. Importantly, we determined for the first time that circulating CAF levels correlate with worse prognosis and a lower probability of survival in Met-pa. Based on the CTC release induced by chemotherapy, we evaluated the efficacy of our previously developed cancer immunotherapy to eradicate CTCs from Met-pa blood using an ex vivo approach and demonstrate this could kill over 60% of CTCs.

CONCLUSION

Collectively, we found that CAF levels in Met-pa serve as a predictive biomarker for cancer prognosis. Additionally, we demonstrate the efficacy of our therapy to kill primary CTCs for a range of cancer types, supporting its potential use as an anti-metastasis therapy in the clinical setting.

Fabrication and Characterization of Tumor Nano-Lysate as a Preventative Vaccine for Breast Cancer

Breast cancer is the most common cancer among women in the United States, with late stages associated with the lowest survival rates. The latest stage, defined as metastasis, accounts for 90% of all cancer-related deaths. There is a strong need to develop antimetastatic therapies. TRAIL, or TNF-related apoptosis inducing ligand, has been used as an antimetastatic therapy in the past, and conjugating TRAIL to nanoscale liposomes has been shown to enhance its targeting efficacy. When circulating tumor cells (CTCs) released during metastasis are exposed to TRAIL-conjugated liposomes and physiologically relevant fluid shear stress, this results in rapid cancer cell destruction into cell fragments. We sought to artificially recreate this phenomenon using probe sonication to mechanically disrupt cancer cells and characterized the resulting cell fragments, termed "tumor nano-lysate", with respect to size, charge, morphology, and composition. Furthermore, an in vivo pilot study was performed to investigate the efficacy of tumor nano-lysate as a preventative vaccine for breast cancer in an immunocompetent mouse model.

A simplified method for the efficient purification and refolding of recombinant human TRAIL

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) belongs to the TNF cytokine superfamily that specifically induces apoptosis in a broad spectrum of human cancer cell lines but not in most healthy cells. The antitumor potential of recombinant human TRAIL (rhTRAIL) has attracted great attention among biologists and oncologists. However, attempts to express rhTRAIL in Escherichia coli often results in limited yield of bioactive protein due to the formation of inclusion bodies (IBs), which are dense insoluble particulate protein aggregates inside cells. We describe herein a highly simplified method to produce pure bioactive rhTRAIL using E. coli. The method is straightforward and requires only basic laboratory equipment, with highly efficient purification and high yield of renaturation, and may also be applied to produce other proteins that form IBs in E. coli.

The Role of Circulating Tumor Cells in the Metastatic Cascade: Biology, Technical Challenges, and Clinical Relevance

Metastases and cancer recurrence are the main causes of cancer death. Circulating Tumor Cells (CTCs) and disseminated tumor cells are the drivers of cancer cell dissemination. The assessment of CTCs' clinical role in early metastasis prediction, diagnosis, and treatment requires more information about their biology, their roles in cancer dormancy, and immune evasion as well as in therapy resistance. Indeed, CTC functional and biochemical phenotypes have been only partially characterized using murine metastasis models and liquid biopsy in human patients. CTC detection, characterization, and enumeration represent a promising tool for tailoring the management of each patient with cancer. The comprehensive understanding of CTCs will provide more opportunities to determine their clinical utility. This review provides much-needed insights into this dynamic field of translational cancer research.

TRAIL in oncology: From recombinant TRAIL to nano- and self-targeted TRAIL-based therapies

TNF-related apoptosis-inducing ligand (TRAIL) selectively induces the apoptosis pathway in tumor cells leading to tumor cell death. Because TRAIL induction can kill tumor cells, cancer researchers have developed many agents to target TRAIL and some of these agents have entered clinical trials in oncology. Unfortunately, these trials have failed for many reasons, including drug resistance, off-target toxicities, short half-life, and specifically in gene therapy due to the limited uptake of TRAIL genes by cancer cells. To address these drawbacks, translational researchers have utilized drug delivery platforms. Although, these platforms can improve TRAIL-based therapies, they are unable to sufficiently translate the full potential of TRAIL-targeting to clinically viable products. Herein, we first summarize the complex biology of TRAIL signaling, including TRAILs cross-talk with other signaling pathways and immune cells. Next, we focus on known resistant mechanisms to TRAIL-based therapies. Then, we discuss how nano-formulation has the potential to enhance the therapeutic efficacy of TRAIL protein. Finally, we specify strategies with the potential to overcome the challenges that cannot be addressed via nanotechnology alone, including the alternative methods of TRAIL-expressing circulating cells, tumor-targeting bacteria, viruses, and exosomes.

Engineering of Exosomes to Target Cancer Metastasis

As a nanoscale subset of extracellular vehicles, exosomes represent a new pathway of intercellular communication by delivering cargos such as proteins and nucleic acids to recipient cells. Importantly, it has been well documented that exosome-mediated delivery of such cargo is involved in many pathological processes such as tumor progression, cancer metastasis, and development of drug resistance. Innately biocompatible and possessing ideal structural properties, exosomes offer distinct advantages for drug delivery over artificial nanoscale drug carriers. In this review, we summarize recent progress in methods for engineering exosomes including isolation techniques and exogenous cargo encapsulation, with a focus on applications of engineered exosomes to target cancer metastasis.

Targeted Delivery of siRNA Lipoplexes to Cancer Cells Using Macrophage Transient Horizontal Gene Transfer

Delivery of nucleic acids into solid tumor environments remains a pressing challenge. This study examines the ability of macrophages to horizontally transfer small interfering RNA (siRNA) lipoplexes to cancer cells. Macrophages are a natural candidate for a drug carrier because of their ability to accumulate at high densities into many cancer types, including, breast, prostate, brain, and colon cancer. Here, it is demonstrated that macrophages can horizontally transfer siRNA to cancer cells during in vitro coculture. The amount of transfer can be dosed depending on the amount of siRNA loaded and total number of macrophages delivered. Macrophages loaded with calcium integrin binding protein-1 (CIB1)-siRNA result in decreased tumorsphere growth and decreased mRNA expression of CIB1 and KI67 in MDA-MB-468 human breast cancer cells. Adoptive transfer of macrophages transfected with CIB1-siRNA localizes to the orthotopic MDA-MB-468 tumor. Furthermore, it is reported that macrophage activation can modulate this transfer process as well as intracellular trafficking protein Rab27a. As macrophages are heavily involved in tumor progression, understanding how to use macrophages for drug delivery can substantially benefit the treatment of tumors.

Minimal dosing of leukocyte targeting TRAIL decreases triple-negative breast cancer metastasis following tumor resection

Surgical removal of the primary tumor is a common practice in breast cancer treatment. However, postsurgical metastasis poses an immense setback in cancer therapy. Considering that 90% of cancer-related deaths are due to metastasis, antimetastatic therapeutic strategies that can target disseminating tumor cells in the circulation before they can form secondary tumors hold preclinical and clinical potential for cancer patients. Our current work uses a liposomal formulation functionalized with the adhesion receptor E-selectin and the apoptosis-inducing ligand TNF (tumor necrosis factor)-related apoptosis-inducing ligand (TRAIL) to reduce metastasis following tumor resection in an aggressive triple-negative breast cancer (TNBC) mouse model. We demonstrate that minimal administration of E-selectin-TRAIL liposomes can target metastasis in a TNBC model, with primary tumor resection to mimic clinical settings. Our study indicates that TRAIL liposomes, alone or in combination with existing clinically approved therapies, may neutralize distant metastasis of a broad range of tumor types systemically.

Delivery technologies for cancer immunotherapy

Immunotherapy has become a powerful clinical strategy for treating cancer. The number of immunotherapy drug approvals has been increasing, with numerous treatments in clinical and preclinical development. However, a key challenge in the broad implementation of immunotherapies for cancer remains the controlled modulation of the immune system, as these therapeutics have serious adverse effects including autoimmunity and nonspecific inflammation. Understanding how to increase the response rates to various classes of immunotherapy is key to improving efficacy and controlling these adverse effects. Advanced biomaterials and drug delivery systems, such as nanoparticles and the use of T cells to deliver therapies, could effectively harness immunotherapies and improve their potency while reducing toxic side effects. Here, we discuss these research advances, as well as the opportunities and challenges for integrating delivery technologies into cancer immunotherapy, and we critically analyse the outlook for these emerging areas.

Nanoparticle-Laden Macrophages for Tumor-Tropic Drug Delivery

Macrophages hold great potential in cancer drug delivery because they can sense chemotactic cues and home to tumors with high efficiency. However, it remains a challenge to load large amounts of therapeutics into macrophages without compromising cell functions. This study reports a silica-based drug nanocapsule approach to solve this issue. The nanocapsule consists of a drug-silica complex filling and a solid silica sheath, and it is designed to minimally release drug molecules in the early hours of cell entry. While taken up by macrophages at high rates, the nanocapsules minimally affect cell migration in the first 6-12 h, buying time for macrophages to home to tumors and release drugs in situ. In particular, it is shown that doxorubicin (Dox) as a representative drug can be loaded into macrophages up to 16.6 pg per cell using this approach. When tested in a U87MG xenograft model, intravenously (i.v.) injected Dox-laden macrophages show comparable tumor accumulation as untreated macrophages. Therapy leads to efficient tumor growth suppression, while causing little systematic toxicity. This study suggests a new cell platform for selective drug delivery, which can be readily extended to the treatment of other types of diseases.

Mass Action Kinetic Model of Apoptosis by TRAIL-Functionalized Leukocytes

Background: Metastasis through the bloodstream contributes to poor prognosis in many types of cancer. A unique approach to target and kill colon, prostate, and other epithelial-type cancer cells in the blood has been recently developed that uses circulating leukocytes to present the cancer-specific, liposome-bound Tumor Necrosis Factor (TNF)-related apoptosis inducing ligand (TRAIL) on their surface along with E − selectin adhesion receptors. This approach, demonstrated both in vitro with human blood and in mice, mimics the cytotoxic activity of natural killer cells. The resulting liposomal TRAIL-coated leukocytes hold promise as an effective means to neutralize circulating tumor cells that enter the bloodstream with the potential to form new metastases.

Methods: The computational biology study reported here examines the mechanism of this effective signal delivery, by considering the kinetics of the coupled reaction cascade, from TRAIL binding death receptor to eventual apoptosis. In this study, a collision of bound TRAIL with circulating tumor cells (CTCs) is considered and compared to a prolonged exposure of CTCs to soluble TRAIL. An existing computational model of soluble TRAIL treatment was modified to represent the kinetics from a diffusion-limited 3D reference frame into a 2D collision frame with advection and adhesion to mimic the E − selectin and membrane bound TRAIL treatment. Thus, the current model recreates the new approach of targeting cancer cells within the blood. The model was found to faithfully reproduce representative observations from experiments of liposomal TRAIL treatment under shear.

Results: The model predicts apoptosis of CTCs within 2 h when treated with membrane bound TRAIL, while apoptosis in CTCs treated with soluble TRAIL proceeds much more slowly over the course of 10 h, consistent with previous experiments. Given the clearance rate of soluble TRAIL in vivo, this model predicts that the soluble TRAIL method would be rendered ineffective, as found in previous experiments.

Conclusion: This study therefore indicates that the kinetics of the coupled reaction cascade of liposomal E − selectin and membrane bound TRAIL colliding with CTCs can explain why this new approach to target and kill cancer cells in blood is much more effective than its soluble counterpart.

A novel α-enolase-targeted drug delivery system for high efficacy prostate cancer therapy

Prostate cancer, one of the leading causes of disease and death in men all over the world, is challenging to treat. α-Enolase, a multifunctional protein, is overexpressed on human prostate carcinoma cells, and thereby it is a potential target for treatment of prostate cancer. In the current study, the pHCT74 peptide was used to construct a kind of highly targeted liposome (pHCT74-lipo) loaded with doxorubicin (pHCT74-lipo-Dox), which specifically targeted α-enolase on prostate tumour cells. Compared with liposomes without pHCT74 modification, pHCT74-lipo-Dox displayed a superior intracellular internalization with enhanced tumour cytotoxicity. In the in vivo study, pHCT74-lipo showed much higher tumour accumulation. In addition, loaded into pHCT74-lipo, doxorubicin demonstrated significantly improved anti-tumour activity on prostate tumour-bearing mice. These results suggest that the pHCT74 peptide has potential to be used in the development of a novel drug delivery system for targeted therapy against prostate cancer.

Circulating Tumor Cells: Diagnostic and Therapeutic Applications

Metastasis contributes to poor prognosis in many types of cancer and is the leading cause of cancer-related deaths. Tumor cells metastasize to distant sites via the circulatory and lymphatic systems. In this review, we discuss the potential of circulating tumor cells for diagnosis and describe the experimental therapeutics that aim to target these disseminating cancer cells. We discuss the advantages and limitations of such strategies and how they may lead to the development of the next generation of antimetastasis treatments.

NanoTRAIL-Oncology: A Strategic Approach in Cancer Research and Therapy

TRAIL is a member of the tumor necrosis factor superfamily that can largely trigger apoptosis in a wide variety of cancer cells, but not in normal cells. However, insufficient exposure to cancer tissues or cells and drug resistance has severely impeded the clinical application of TRAIL. Recently, nanobiotechnology has brought about a revolution in advanced drug delivery for enhanced anticancer therapy using TRAIL. With the help of materials science, immunology, genetic engineering, and protein engineering, substantial progress is made by expressing fusion proteins with TRAIL, engineering TRAIL on biological membranes, and loading TRAIL into functional nanocarriers or conjugating it onto their surfaces. Thus, the nanoparticle-based TRAIL (nanoTRAIL) opens up intriguing opportunities for efficient and safe bioapplications. In this review, the mechanisms of action and biological function of TRAIL, as well as the current status of TRAIL treatment, are comprehensively discussed. The application of functional nanotechnology combined with TRAIL in cancer therapy is also discussed.

Nanoparticles for Immune Cytokine TRAIL-Based Cancer Therapy

The immune cytokine tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has received significant attention as a cancer therapeutic due to its ability to selectively trigger cancer cell apoptosis without causing toxicity in vivo. While TRAIL has demonstrated significant promise in preclinical studies in mice as a cancer therapeutic, challenges including poor circulation half-life, inefficient delivery to target sites, and TRAIL resistance have hindered clinical translation. Recent advances in drug delivery, materials science, and nanotechnology are now being exploited to develop next-generation nanoparticle platforms to overcome barriers to TRAIL therapeutic delivery. Here, we review the design and implementation of nanoparticles to enhance TRAIL-based cancer therapy. The platforms we discuss are diverse in their approaches to the delivery problem and provide valuable insight into guiding the design of future nanoparticle-based TRAIL cancer therapeutics to potentially enable future translation into the clinic.

Engineering and physical sciences in oncology: challenges and opportunities

The principles of engineering and physics have been applied to oncology for nearly 50 years. Engineers and physical scientists have made contributions to all aspects of cancer biology, from quantitative understanding of tumour growth and progression to improved detection and treatment of cancer. Many early efforts focused on experimental and computational modelling of drug distribution, cell cycle kinetics and tumour growth dynamics. In the past decade, we have witnessed exponential growth at the interface of engineering, physics and oncology that has been fuelled by advances in fields including materials science, microfabrication, nanomedicine, microfluidics, imaging, and catalysed by new programmes at the National Institutes of Health (NIH), including the National Institute of Biomedical Imaging and Bioengineering (NIBIB), Physical Sciences in Oncology, and the National Cancer Institute (NCI) Alliance for Nanotechnology. Here, we review the advances made at the interface of engineering and physical sciences and oncology in four important areas: the physical microenvironment of the tumour and technological advances in drug delivery; cellular and molecular imaging; and microfluidics and microfabrication. We discussthe research advances, opportunities and challenges for integrating engineering and physical sciences with oncology to develop new methods to study, detect and treat cancer, and we also describe the future outlook for these emerging areas.

Nanocarriers for TRAIL delivery: driving TRAIL back on track for cancer therapy

Since its initial identification, tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) has been shown to be capable of selectively inducing apoptosis in cancer cells. However, translation of the encouraging preclinical studies of this cytokine into the clinic has been restricted by its extremely short half-life, the presence of resistant cancer cell populations, and its inefficient in vivo delivery. Recently, there has been exceptional progress in developing novel formulations to increase the circulatory half-life of TRAIL and new combinations to treat cancers that are resistant to TRAIL. In particular, TRAIL-based nanotherapies offer the potential to improve the stability of TRAIL and prolong its half-life in plasma, to specifically deliver TRAIL to a particular target site, and to overcome resistance to TRAIL. The aim of this review is to provide an overview of the state-of-the art drug delivery systems that are currently being tested or developed to improve the biological attributes of TRAIL-based therapies.