Pathology: cancer cells compress intratumour vessels

Polyester nanoparticles delivering chemotherapeutics: Learning from the past and looking to the future to enhance their clinical impact in tumor therapy

Polymeric nanoparticles (NPs), specifically those comprised of biodegradable and biocompatible polyesters, have been heralded as a game-changing drug delivery platform. In fact, poly(α-hydroxy acids) such as polylactide (PLA), poly(lactide-co-glycolide) (PLGA), and poly(ε-caprolactone) (PCL) have been heavily researched in the past three decades as the material basis of polymeric NPs for drug delivery applications. As materials, these polymers have found success in resorbable sutures, biodegradable implants, and even monolithic, biodegradable platforms for sustained release of therapeutics (e.g., proteins and small molecules) and diagnostics. Few fields have gained more attention in drug delivery through polymeric NPs than cancer therapy. However, the clinical translational of polymeric nanomedicines for treating solid tumors has not been congruent with the fervor or funding in this particular field of research. Here, we attempt to provide a comprehensive snapshot of polyester NPs in the context of chemotherapeutic delivery. This includes a preliminary exploration of the polymeric nanomedicine in the cancer research space. We examine the various processes for producing polyester NPs, including methods for surface-functionalization, and related challenges. After a detailed overview of the multiple factors involved with the delivery of NPs to solid tumors, the crosstalk between particle design and interactions with biological systems is discussed. Finally, we report state-of-the-art approaches toward effective delivery of NPs to tumors, aiming at identifying new research areas and re-evaluating the reasons why some research avenues have underdelivered. We hope our effort will contribute to a better understanding of the gap to fill and delineate the future research work needed to bring polyester-based NPs closer to clinical application. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Lymphatic system regulation of anti-cancer immunity and metastasis

Cancer dissemination to lymph nodes (LN) is associated with a worse prognosis, increased incidence of distant metastases and reduced response to therapy. The LN microenvironment puts selective pressure on cancer cells, creating cells that can survive in LN as well as providing survival advantages for distant metastatic spread. Additionally, the presence of cancer cells leads to an immunosuppressive LN microenvironment, favoring the evasion of anti-cancer immune surveillance. However, recent studies have also characterized previously unrecognized roles for tumor-draining lymph nodes (TDLNs) in cancer immunotherapy response, including acting as a reservoir for pre-exhausted CD8+ T cells and stem-like CD8+ T cells. In this review, we will discuss the spread of cancer cells through the lymphatic system, the roles of TDLNs in metastasis and anti-cancer immune responses, and the therapeutic opportunities and challenges in targeting LN metastasis.

Tumor-On-A-Chip Models for Predicting In Vivo Nanoparticle Behavior

Nanosized drug formulations are broadly explored for the improvement of cancer therapy. Prediction of in vivo nanoparticle (NP) behavior, however, is challenging, given the complexity of the tumor and its microenvironment. Microfluidic tumor-on-a-chip models are gaining popularity for the in vitro testing of nanoparticle targeting under conditions that simulate the 3D tumor (microenvironment). In this review, following a description of the tumor microenvironment (TME), the state of the art regarding tumor-on-a-chip models for investigating nanoparticle delivery to solid tumors is summarized. The models are classified based on the degree of compartmentalization (single/multi-compartment) and cell composition (tumor only/tumor microenvironment). The physiological relevance of the models is critically evaluated. Overall, microfluidic tumor-on-a-chip models greatly improve the simulation of the TME in comparison to 2D tissue cultures and static 3D spheroid models and contribute to the understanding of nanoparticle behavior. Interestingly, two interrelated aspects have received little attention so far which are the presence and potential impact of a protein corona as well as nanoparticle uptake through phagocytosing cells. A better understanding of their relevance for the predictive capacity of tumor-on-a-chip systems and development of best practices will be a next step for the further refinement of advanced in vitro tumor models.

Modulating cancer mechanopathology to restore vascular function and enhance immunotherapy

Solid tumor pathology, characterized by abnormalities in the tumor microenvironment (TME), challenges therapeutic effectiveness. Mechanical factors, including increased tumor stiffness and accumulation of intratumoral forces, can determine the success of cancer treatments, defining the tumor's "mechanopathology" profile. These abnormalities cause extensive vascular compression, leading to hypoperfusion and hypoxia. Hypoperfusion hinders drug delivery, while hypoxia creates an unfavorable TME, promoting tumor progression through immunosuppression, heightened metastatic potential, drug resistance, and chaotic angiogenesis. Strategies targeting TME mechanopathology, such as vascular and stroma normalization, hold promise in enhancing cancer therapies with some already advancing to the clinic. Normalization can be achieved using anti-angiogenic agents, mechanotherapeutics, immune checkpoint inhibitors, engineered bacterial therapeutics, metronomic nanomedicine, and ultrasound sonopermeation. Here, we review the methods developed to rectify tumor mechanopathology, which have even led to cures in preclinical models, and discuss their bench-to-bedside translation, including the derivation of biomarkers from tumor mechanopathology for personalized therapy.

The impact of tumor microenvironment: unraveling the role of physical cues in breast cancer progression

Metastasis accounts for the vast majority of breast cancer-related fatalities. Although the contribution of genetic and epigenetic modifications to breast cancer progression has been widely acknowledged, emerging evidence underscores the pivotal role of physical stimuli in driving breast cancer metastasis. In this review, we summarize the changes in the mechanics of the breast cancer microenvironment and describe the various forces that impact migrating and circulating tumor cells throughout the metastatic process. We also discuss the mechanosensing and mechanotransducing molecules responsible for promoting the malignant phenotype in breast cancer cells. Gaining a comprehensive understanding of the mechanobiology of breast cancer carries substantial potential to propel progress in prognosis, diagnosis, and patient treatment.

A synergistic approach for modulating the tumor microenvironment to enhance nano-immunotherapy in sarcomas

The lack of properly perfused blood vessels within tumors can significantly hinder the distribution of drugs, leading to reduced treatment effectiveness and having a negative impact on the quality of life of patients with cancer. This problem is particularly pronounced in desmoplastic cancers, where interactions between cancer cells, stromal cells, and the fibrotic matrix lead to tumor stiffness and the compression of most blood vessels within the tumor. To address this issue, two mechanotherapy approaches-mechanotherapeutics and ultrasound sonopermeation-have been employed separately to treat vascular abnormalities in tumors and have reached clinical trials. Here, we performed in vivo studies in sarcomas, to explore the conditions under which these two mechanotherapy strategies could be optimally combined to enhance perfusion and the efficacy of nano-immunotherapy. Our findings demonstrate that combination of the anti-histamine drug ketotifen, as a mechanotherapeutic, and sonopermeation effectively alleviates mechanical forces by decreasing 50 % collagen and hyaluronan levels and thus, reshaping the tumor microenvironment. Furthermore, the combined therapy normalizes the tumor vasculature by increasing two-fold the pericytes coverage. This combination not only improves six times tumor perfusion but also enhances drug delivery. As a result, blood vessel functionality is enhanced, leading to increased infiltration by 40 % of immune cells (CD4+ and CD8+ T-cells) and improving the antitumor efficacy of Doxil nanomedicine and anti-PD-1 immunotherapy. In conclusion, our research underscores the unique and synergistic potential of combining mechanotherapeutics and sonopermeation. Both approaches are undergoing clinical trials to enhance cancer therapy and have the potential to significantly improve nano-immunotherapy in sarcomas.

Multibarrier-penetrating drug delivery systems for deep tumor therapy based on synergistic penetration strategy

Nanotherapies, valued for their high efficacy and low toxicity, frequently serve as antitumor treatments, but do not readily penetrate deep into tumor tissues and cells. Here we developed an improved tumor-penetrating peptide (TPP)-based drug delivery system. Briefly, the established TPP iNGR was modified to generate a linear NGR peptide capable of transporting nanotherapeutic drugs into tumors through a CendR pathway-dependent, neuropilin-1 receptor-mediated process. Although TPPs have been reported to reach intended tumor targets, they often fail to penetrate cell membranes to deliver tumoricidal drugs to intracellular targets. We addressed this issue by harnessing cell penetrating peptide technology to develop a liposome-based multibarrier-penetrating delivery system (mbPDS) with improved synergistic drug penetration into deep tumor tissues and cells. The system incorporated doxorubicin-loaded liposomes coated with nona-arginine (R9) CPP and cyclic iNGR (CRNGRGPDC) molecules, yielding Lip-mbPDS. Lip-mbPDS tumor-targeting, tumor cell/tissue-penetrating and antitumor capabilities were assessed using CD13-positive human fibrosarcoma-derived cell (HT1080)-based in vitro and in vivo tumor models. Lip-mbPDS evaluation included three-dimensional layer-by-layer confocal laser scanning microscopy, cell internalization/toxicity assays, three-dimensional tumor spheroid-based penetration assays and antitumor efficacy assays conducted in an animal model. Lip-mbPDS provided enhanced synergistic drug penetration of multiple biointerfaces for potentially deep tumor therapeutic outcomes.

Anti-lymphangiogenesis for boosting drug accumulation in tumors

The inadequate tumor accumulation of anti-cancer agents is a major shortcoming of current therapeutic drugs and remains an even more significant concern in the clinical prospects for nanomedicines. Various strategies aiming at regulating the intratumoral permeability of therapeutic drugs have been explored in preclinical studies, with a primary focus on vascular regulation and stromal reduction. However, these methods may trigger or facilitate tumor metastasis as a tradeoff. Therefore, there is an urgent need for innovative strategies that boost intratumoral drug accumulation without compromising treatment outcomes. As another important factor affecting drug tumor accumulation besides vasculature and stroma, the impact of tumor-associated lymphatic vessels (LVs) has not been widely considered. In the current research, we verified that anlotinib, a tyrosine kinase inhibitor with anti-lymphangiogenesis activity, and SAR131675, a selective VEGFR-3 inhibitor, effectively decreased the density of tumor lymphatic vessels in mouse cancer models, further enhancing drug accumulation in tumor tissue. By combining anlotinib with therapeutic drugs, including doxorubicin (Dox), liposomal doxorubicin (Lip-Dox), and anti-PD-L1 antibody, we observed improved anti-tumor efficacy in comparison with monotherapy regimens. Meanwhile, this strategy significantly reduced tumor metastasis and elicited stronger anti-tumor immune responses. Our work describes a new, clinically transferrable approach to augmenting intratumoral drug accumulation, which shows great potential to address the current, unsatisfactory efficacies of therapeutic drugs without introducing metastatic risk.

Using a probabilistic approach to derive a two-phase model of flow-induced cell migration

Interstitial fluid flow is a feature of many solid tumors. In vitro experiments have shown that such fluid flow can direct tumor cell movement upstream or downstream depending on the balance between the competing mechanisms of tensotaxis (cell migration up stress gradients) and autologous chemotaxis (downstream cell movement in response to flow-induced gradients of self-secreted chemoattractants). In this work we develop a probabilistic-continuum, two-phase model for cell migration in response to interstitial flow. We use a kinetic description for the cell velocity probability density function, and model the flow-dependent mechanical and chemical stimuli as forcing terms that bias cell migration upstream and downstream. Using velocity-space averaging, we reformulate the model as a system of continuum equations for the spatiotemporal evolution of the cell volume fraction and flux in response to forcing terms that depend on the local direction and magnitude of the mechanochemical cues. We specialize our model to describe a one-dimensional cell layer subject to fluid flow. Using a combination of numerical simulations and asymptotic analysis, we delineate the parameter regime where transitions from downstream to upstream cell migration occur. As has been observed experimentally, the model predicts downstream-oriented chemotactic migration at low cell volume fractions, and upstream-oriented tensotactic migration at larger volume fractions. We show that the locus of the critical volume fraction, at which the system transitions from downstream to upstream migration, is dominated by the ratio of the rate of chemokine secretion and advection. Our model also predicts that, because the tensotactic stimulus depends strongly on the cell volume fraction, upstream, tensotaxis-dominated migration occurs only transiently when the cells are initially seeded, and transitions to downstream, chemotaxis-dominated migration occur at later times due to the dispersive effect of cell diffusion.

Alteration of mechanical stresses in the murine brain by age and hemorrhagic stroke

Residual mechanical stresses, also known as solid stresses, emerge during rapid differential growth or remodeling of tissues, as observed in morphogenesis and tumor growth. While residual stresses typically dissipate in most healthy adult organs, as the growth rate decreases, high residual stresses have been reported in mature, healthy brains. However, the origins and consequences of residual mechanical stresses in the brain across health, aging, and disease remain poorly understood. Here, we utilized and validated a previously developed method to map residual mechanical stresses in the brains of mice across three age groups: 5-7 days, 8-12 weeks, and 22 months. We found that residual solid stress rapidly increases from 5-7 days to 8-12 weeks and remains high in mature 22 months mice brains. Three-dimensional mapping revealed unevenly distributed residual stresses from the anterior to posterior coronal brain sections. Since the brain is rich in negatively charged hyaluronic acid, we evaluated the contribution of charged extracellular matrix (ECM) constituents in maintaining solid stress levels. We found that lower ionic strength leads to elevated solid stresses, consistent with its unshielding effect and the subsequent expansion of charged ECM components. Lastly, we demonstrated that hemorrhagic stroke, accompanied by loss of cellular density, resulted in decreased residual stress in the murine brain. Our findings contribute to a better understanding of spatiotemporal alterations of residual solid stresses in healthy and diseased brains, a crucial step toward uncovering the biological and immunological consequences of this understudied mechanical phenotype in the brain.

Ionizable Lipid Nanoparticle-Mediated TRAIL mRNA Delivery in the Tumor Microenvironment to Inhibit Colon Cancer Progression

Introduction

Immunotherapy has revolutionized cancer treatment by harnessing the immune system to enhance antitumor responses while minimizing off-target effects. Among the promising cancer-specific therapies, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has attracted significant attention.

Methods

Here, we developed an ionizable lipid nanoparticle (LNP) platform to deliver TRAIL mRNA (LNP-TRAIL) directly to the tumor microenvironment (TME) to induce tumor cell death. Our LNP-TRAIL was formulated via microfluidic mixing and the induction of tumor cell death was assessed in vitro. Next, we investigated the ability of LNP-TRAIL to inhibit colon cancer progression in vivo in combination with a TME normalization approach using Losartan (Los) or angiotensin 1-7 (Ang(1-7)) to reduce vascular compression and deposition of extracellular matrix in mice.

Results

Our results demonstrated that LNP-TRAIL induced tumor cell death in vitro and effectively inhibited colon cancer progression in vivo, particularly when combined with TME normalization induced by treatment Los or Ang(1-7). In addition, potent tumor cell death as well as enhanced apoptosis and necrosis was found in the tumor tissue of a group treated with LNP-TRAIL combined with TME normalization.

Discussion

Together, our data demonstrate the potential of the LNP to deliver TRAIL mRNA to the TME and to induce tumor cell death, especially when combined with TME normalization. Therefore, these findings provide important insights for the development of novel therapeutic strategies for the immunotherapy of solid tumors.

Linking cell mechanical memory and cancer metastasis

Metastasis causes most cancer-related deaths; however, the efficacy of anti-metastatic drugs is limited by incomplete understanding of the biological mechanisms that drive metastasis. Focusing on the mechanics of metastasis, we propose that the ability of tumour cells to survive the metastatic process is enhanced by mechanical stresses in the primary tumour microenvironment that select for well-adapted cells. In this Perspective, we suggest that biophysical adaptations favourable for metastasis are retained via mechanical memory, such that the extent of memory is influenced by both the magnitude and duration of the mechanical stress. Among the mechanical cues present in the primary tumour microenvironment, we focus on high matrix stiffness to illustrate how it alters tumour cell proliferation, survival, secretion of molecular factors, force generation, deformability, migration and invasion. We particularly centre our discussion on potential mechanisms of mechanical memory formation and retention via mechanotransduction and persistent epigenetic changes. Indeed, we propose that the biophysical adaptations that are induced by this process are retained throughout the metastatic process to improve tumour cell extravasation, survival and colonization in the distant organ. Deciphering mechanical memory mechanisms will be key to discovering a new class of anti-metastatic drugs.

Nanotechnology-based delivery systems to overcome drug resistance in cancer

Cancer nanomedicine is defined as the application of nanotechnology and nanomaterials for the formulation of cancer therapeutics that can overcome the impediments and restrictions of traditional chemotherapeutics. Multidrug resistance (MDR) in cancer cells can be defined as a decrease or abrogation in the efficacy of anticancer drugs that have different molecular structures and mechanisms of action and is one of the primary causes of therapeutic failure. There have been successes in the development of cancer nanomedicine to overcome MDR; however, relatively few of these formulations have been approved by the United States Food and Drug Administration for the treatment of cancer. This is primarily due to the paucity of knowledge about nanotechnology and the fundamental biology of cancer cells. Here, we discuss the advances, types of nanomedicines, and the challenges regarding the translation of in vitro to in vivo results and their relevance to effective therapies.

Pirfenidone-Loaded Polymeric Micelles as an Effective Mechanotherapeutic to Potentiate Immunotherapy in Mouse Tumor Models

Ongoing research is actively exploring the use of immune checkpoint inhibitors to treat solid tumors by inhibiting the PD-1/PD-L1 axis and reactivating the function of cytotoxic T effector cells. Many types of solid tumors, however, are characterized by a dense and stiff stroma and are difficult to treat. Mechanotherapeutics have formed a recent class of drugs that aim to restore biomechanical abnormalities of the tumor microenvironment, related to increased stiffness and hypo-perfusion. Here, we have developed a polymeric formulation containing pirfenidone, which has been successful in restoring the tumor microenvironment in breast tumors and sarcomas. We found that the micellar formulation can induce similar mechanotherapeutic effects to mouse models of 4T1 and E0771 triple negative breast tumors and MCA205 fibrosarcoma tumors but with a dose 100-fold lower than that of the free pirfenidone. Importantly, a combination of pirfenidone-loaded micelles with immune checkpoint inhibition significantly delayed primary tumor growth, leading to a significant improvement in overall survival and in a complete cure for the E0771 tumor model. Furthermore, the combination treatment increased CD4+ and CD8+ T cell infiltration and suppressed myeloid-derived suppressor cells, creating favorable immunostimulatory conditions, which led to immunological memory. Ultrasound shear wave elastography (SWE) was able to monitor changes in tumor stiffness during treatment, suggesting optimal treatment conditions. Micellar encapsulation is a promising strategy for mechanotherapeutics, and imaging methods, such as SWE, can assist their clinical translation.

Therapeutic In Situ Cancer Vaccine Using Pulsed Stereotactic Body Radiotherapy-A Translational Model

Both radiation and cancer therapeutic vaccine research are more than 100 years old, and their potential is likely underexplored. Antiangiogenics, nanoparticle targeting, and immune modulators are some other established anticancer therapies. In the meantime, immunotherapy usage is gaining momentum in clinical applications. This article proposes the concept of a pulsed/intermittent/cyclical endothelial-sparing single-dose in situ vaccination (ISVRT) schedule distinguishable from the standard therapeutic stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS) plans. This ISVRT schedule can repeatedly generate tumor-specific neoantigens and epitopes for primary and immune modulation effects, augment supplementary immune enhancement techniques, activate long-term memory cells, avoid extracellular matrix fibrosis, and essentially synchronize with the vascular normalized immunity cycle. The core mechanisms of ISVRT impacting in situ vaccination would be optimizing cascading antigenicity and adjuvanticity. The present proposed hypothesis can be validated using the algorithm presented. The indications for the proposed concept are locally progressing/metastatic cancers that have failed standard therapies. Immunotherapy/targeted therapy, chemotherapy, antiangiogenics, and vascular-lymphatic normalization are integral to such an approach.

Biomechanical stimulation promotes blood vessel growth despite VEGFR-2 inhibition

BACKGROUND

Angiogenesis, or the growth of new vasculature from existing blood vessels, is widely considered a primary hallmark of cancer progression. When a tumor is small, diffusion is sufficient to receive essential nutrients; however, as the tumor grows, a vascular supply is needed to deliver oxygen and nutrients into the increasing mass. Several anti-angiogenic cancer therapies target VEGF and the receptor VEGFR-2, which are major promoters of blood vessel development. Unfortunately, many of these cancer treatments fail to completely stop angiogenesis in the tumor microenvironment (TME). Since these therapies focus on the biochemical activation of VEGFR-2 via VEGF ligand binding, we propose that mechanical cues, particularly those found in the TME, may be a source of VEGFR-2 activation that promotes growth of blood vessel networks even in the presence of VEGF and VEGFR-2 inhibitors.

RESULTS

In this paper, we analyzed phosphorylation patterns of VEGFR-2, particularly at Y1054/Y1059 and Y1214, stimulated via either VEGF or biomechanical stimulation in the form of tensile strains. Our results show prolonged and enhanced activation at both Y1054/Y1059 and Y1214 residues when endothelial cells were stimulated with strain, VEGF, or a combination of both. We also analyzed Src expression, which is downstream of VEGFR-2 and can be activated through strain or the presence of VEGF. Finally, we used fibrin gels and microfluidic devices as 3D microtissue models to simulate the TME. We determined that regions of mechanical strain promoted increased vessel growth, even with VEGFR-2 inhibition through SU5416.

CONCLUSIONS

Overall, understanding both the effects that biomechanical and biochemical stimuli have on VEGFR-2 activation and angiogenesis is an important factor in developing effective anti-angiogenic therapies. This paper shows that VEGFR-2 can be mechanically activated through strain, which likely contributes to increased angiogenesis in the TME. These proof-of-concept studies show that small molecular inhibitors of VEGFR-2 do not fully prevent angiogenesis in 3D TME models when mechanical strains are introduced.

Correlation between IVIM parameters and microvessel architecture: direct comparison of MRI images and pathological slices in an orthotopic murine model of rhabdomyosarcoma

OBJECTIVE

This study aimed to explore the correlation between intravoxel incoherent motion (IVIM) parameters and microvessel architecture (microvessel density (MVD), vasculogenic mimicry (VM), and pericyte coverage index (PCI)) in an orthotopic murine model of rhabdomyosarcoma.

METHODS

The murine model was established by injecting rhabdomyosarcoma-derived (RD) cells into the muscle. Nude mice underwent routine magnetic resonance imaging (MRI) and IVIM examinations with ten b values (0, 50, 100, 150, 200, 400, 600, 800, 1000, and 2000 s/mm2). D, D*, and f values were calculated with the ADW4.7 workstation. MRI images and pathological slices were directly compared to ensure that radiology parameters accurately reflect pathology. MVD, VM, PCI, and cellularity were obtained by histological analysis. The correlations were assessed between IVIM parameters (D, D*, f, and fD* values) and pathological markers (MVD, VM, PCI, and cellularity).

RESULTS

The average of D, D*, f, and fD* values were 0.55 ± 0.07 × 10-3 mm2/s, 5.25 ± 0.73 × 10-3 mm2/s, 13.39 ± 7.68%, and 0.73 ± 0.49 × 10-3 mm2/s, respectively. The average of MVD, VM, PCI, and cellularity were 41.91 ± 10.98, 1.16 ± 0.83, 0.49 ± 0.18, and 39.15 ± 9.00%. D*, f, and fD* values showed a positive correlation with MVD separately, while the D value did not correlate with MVD. D value negatively correlated to VM moderately, and other parameters did not associate with VM. D* and fD* values were positively correlated with PCI, but no correlation was observed between other parameters and PCI.

CONCLUSIONS

IVIM may evaluate the tumor microvessel architecture. D*, f, and fD* may reflect the endothelial lining blood vessel; D could indirectly reflect the VM; D* and fD* could reflect PCI(the normal degree of the tumor blood vessel).

CLINICAL RELEVANCE STATEMENT

An intravoxel incoherent motion may be useful in assessing rhabdomyosarcoma microvessel structure to predict the target and effectiveness of anti-angiogenic therapy.

KEY POINTS

• IVIM may be used to evaluate the tumor microvessel architecture in the mouse rhabdomyosarcoma model. • The MRI-pathology control method achieves correspondence between MRI slices and pathology slices, which ensures the consistency of the ROI of MRI and the pathology observation region.

No Interference of H9 Extract on Trastuzumab Pharmacokinetics in Their Combinations

Trastuzumab is used to treat breast cancer patients overexpressing human epidermal growth factor receptor 2, but resistance and toxicity limit its uses, leading to attention to trastuzumab combinations. Recently, the synergistic effect of trastuzumab and H9 extract (H9) combination against breast cancer has been reported. Because drug exposure determines its efficacy and toxicity, the question of whether H9 changes trastuzumab exposure in the body has been raised. Therefore, this study aimed to characterize trastuzumab pharmacokinetics and elucidate the effect of H9 on trastuzumab pharmacokinetics at a combination dose that shows synergism in mice. As a result, trastuzumab showed linear pharmacokinetics after its intravenous administration from 1 to 10 mg/kg. In the combination of trastuzumab and H9, single and 2-week treatments of oral H9 (500 mg/kg) did not influence trastuzumab pharmacokinetics. In the multiple-combination treatments of trastuzumab and H9 showing their synergistic effect (3 weeks of trastuzumab with 2 weeks of H9), the pharmacokinetic profile of trastuzumab was comparable to that of 3 weeks of trastuzumab alone. In tissue distribution, the tissue to plasma ratios of trastuzumab below 1.0 indicated its limited distributions within the tissues, and these patterns were unaffected by H9. These results suggest that the systemic and local exposures of trastuzumab are unchanged by single and multiple-combination treatments of H9.

Cancer chemotherapy resistance: Mechanisms and recent breakthrough in targeted drug delivery

Conventional chemotherapy, one of the most widely used cancer treatment methods, has serious side effects, and usually results in cancer treatment failure. Drug resistance is one of the primary reasons for this failure. The most significant drawbacks of systemic chemotherapy are rapid clearance from the circulation, the drug's low concentration in the tumor site, and considerable adverse effects outside the tumor. Several ways have been developed to boost neoplasm treatment efficacy and overcome medication resistance. In recent years, targeted drug delivery has become an essential therapeutic application. As more mechanisms of tumor treatment resistance are discovered, nanoparticles (NPs) are designed to target these pathways. Therefore, understanding the limitations and challenges of this technology is critical for nanocarrier evaluation. Nano-drugs have been increasingly employed in medicine, incorporating therapeutic applications for more precise and effective tumor diagnosis, therapy, and targeting. Many benefits of NP-based drug delivery systems in cancer treatment have been proven, including good pharmacokinetics, tumor cell-specific targeting, decreased side effects, and lessened drug resistance. As more mechanisms of tumor treatment resistance are discovered, NPs are designed to target these pathways. At the moment, this innovative technology has the potential to bring fresh insights into cancer therapy. Therefore, understanding the limitations and challenges of this technology is critical for nanocarrier evaluation.

Intravital measurements of solid stresses in tumours reveal length-scale and microenvironmentally dependent force transmission

In cancer, solid stresses impede the delivery of therapeutics to tumours and the trafficking and tumour infiltration of immune cells. Understanding such consequences and the origin of solid stresses requires their probing in vivo at the cellular scale. Here we report a method for performing volumetric and longitudinal measurements of solid stresses in vivo, and findings from its applicability to tumours. We used multimodal intravital microscopy of fluorescently labelled polyacrylamide beads injected in breast tumours in mice as well as mathematical modelling to compare solid stresses at the single-cell and tissue scales, in primary and metastatic tumours, in vitro and in mice, and in live mice and post-mortem tissue. We found that solid-stress transmission is scale dependent, with tumour cells experiencing lower stresses than their embedding tissue, and that tumour cells in lung metastases experience substantially higher solid stresses than those in the primary tumours. The dependence of solid stresses on length scale and the microenvironment may inform the development of therapeutics that sensitize cancer cells to such mechanical forces.

Mutant p53 sustains serine-glycine synthesis and essential amino acids intake promoting breast cancer growth

Reprogramming of amino acid metabolism, sustained by oncogenic signaling, is crucial for cancer cell survival under nutrient limitation. Here we discovered that missense mutant p53 oncoproteins stimulate de novo serine/glycine synthesis and essential amino acids intake, promoting breast cancer growth. Mechanistically, mutant p53, unlike the wild-type counterpart, induces the expression of serine-synthesis-pathway enzymes and L-type amino acid transporter 1 (LAT1)/CD98 heavy chain heterodimer. This effect is exacerbated by amino acid shortage, representing a mutant p53-dependent metabolic adaptive response. When cells suffer amino acids scarcity, mutant p53 protein is stabilized and induces metabolic alterations and an amino acid transcriptional program that sustain cancer cell proliferation. In patient-derived tumor organoids, pharmacological targeting of either serine-synthesis-pathway and LAT1-mediated transport synergizes with amino acid shortage in blunting mutant p53-dependent growth. These findings reveal vulnerabilities potentially exploitable for tackling breast tumors bearing missense TP53 mutations.

Novel biotin-linked amphiphilic calix[4]arene-based supramolecular micelles as doxorubicin carriers for boosted anticancer activity

Supramolecular carrier-mediated chemotherapy is a highly attractive strategy for targeted drug delivery. In this study, four novel biotin-linked calix[4]arenes BPCA1-BPCA4 have been rationally designed to construct nano-complex with doxorubicin. The in vitro and in vivo assessments reveal that BPCA4-DOX with excellent stability are capable of affording significantly superior anti-tumor activity and lower side effects.

Evaluation of growth-induced, mechanical stress in solid tumors and spatial association with extracellular matrix content

Mechanical stresses in solid tumors play an important role in tumor progression and treatment efficacy but their quantification is under-investigated. Here, we developed an experimental and computational approach to calculate growth-induced, residual stresses and applied it to the breast (4T1), pancreatic (PAN02), and fibrosarcoma (MCA205) tumor models. Following resection, tumors are embedded in agarose gels and cuts are made in two perpendicular directions to release residual stress. With the use of image processing, the detailed bulging displacement profile is measured and finite elements models of the bulging geometry are developed for the quantification of the stress levels. The mechanical properties of the tumors are measured in vivo prior to resection with shear wave elastography. We find that the average magnitude of residual stresses ranges from 3.31 to 10.88 kPa, and they are non-uniformly distributed within the tissue due to the heterogeneity of the tumor microenvironment. Interestingly, we demonstrate that a second cut can still release a significant amount of stresses. We further find a strong association of spatial hyaluronan and collagen content with the spatial profile of stress for the MCA205 and PAN02 tumors and a partial association for the 4T1. Interestingly the colocalization of hyaluronan and collagen content had a stronger association with the spatial profile of stress for MCA205, PAN02, and 4T1. Finally, measurements of the elastic modulus with shear wave elastography show a nonlinear correlation with tumor volume for the more fibrotic MCA205 and 4T1 tumors. Overall, our results provide insights for a better understanding of the mechanical behavior of tumors.

The exit of nanoparticles from solid tumours

Nanoparticles enter tumours through endothelial cells, gaps or other mechanisms, but how they exit is unclear. The current paradigm states that collapsed tumour lymphatic vessels impair the exit of nanoparticles and lead to enhanced retention. Here we show that nanoparticles exit the tumour through the lymphatic vessels within or surrounding the tumour. The dominant lymphatic exit mechanism depends on the nanoparticle size. Nanoparticles that exit the tumour through the lymphatics are returned to the blood system, allowing them to recirculate and interact with the tumour in another pass. Our results enable us to define a mechanism of nanoparticle delivery to solid tumours alternative to the enhanced permeability and retention effect. We call this mechanism the active transport and retention principle. This delivery principle provides a new framework to engineer nanomedicines for cancer treatment and detection.

Bio-Responsive Macromolecular Drug and Small-Molecular Drug Conjugates: Nanoparticulate Prodrugs for Tumor Microenvironment Heterogeneity Management and Therapeutic Response Enhancement

How to break through the poor response of current drug therapy, which often resulted from tumor microenvironment heterogeneity (TMH), remains an enormous challenge in the treatment of critical diseases. In this work, a practical solution on bio-responsive dual-drug conjugates for overcoming TMH and improving antitumor treatment, which integrates the advantages of macromolecular drugs and small-molecular drugs, is proposed. Nanoparticulate prodrugs based on small-molecular drug and macromolecular drug conjugates are designed as a robust weapon for programmable multidrug delivery at tumor-specific sites: the tumor microenvironment acid condition triggers delivery of macromolecular aptamer drugs (AX102) to manage TMH (including tumor stroma matrix, interstitial fluid pressure, vasculature network, blood perfusion, and oxygen distribution), and intracellular lysosomal acid condition activates rapid release of small-molecular drugs (doxorubicin and dactolisib) to enhance curative effects. As compared with doxorubicin chemotherapy, the tumor growth inhibition rate is enhanced by 47.94% after multiple tumor heterogeneity management. This work verifies that the nanoparticulate prodrugs facilitate TMH management and therapeutic response enhancements, as well as elucidates synergetic mechanisms for drug resistance reversal and metastasis inhibition. It is hoped that the nanoparticulate prodrugs will be an excellent demonstration of the co-delivery of small-molecular drugs and macromolecular drugs.

Biomedical,clinical and environmental applications of platinum-based nanohybrids: An updated review

Platinum nanoparticles (Pt NPs) have numerous applications in various sectors, including pharmacology, nanomedicine, cancer therapy, radiotherapy, biotechnology and environment mitigation like removal of toxic metals from wastewater, photocatalytic degradation of toxic compounds, adsorption, and water splitting. The multifaceted applications of Pt NPs because of their ultra-fine structures, large surface area, tuned porosity, coordination-binding, and excellent physiochemical properties. The various types of nanohybrids (NHs) of Pt NPs can be fabricated by doping with different metal/metal oxide/polymer-based materials. There are several methods to synthesize platinum-based NHs, but biological processes are admirable because of green, economical, sustainable, and non-toxic. Due to the robust physicochemical and biological characteristics of platinum NPs, they are widely employed as nanocatalyst, antioxidant, antipathogenic, and anticancer agents. Indeed, Pt-based NHs are the subject of keen interest and substantial research area for biomedical and clinical applications. Hence, this review systematically studies antimicrobial, biological, and environmental applications of platinum and platinum-based NHs, predominantly for treating cancer and photo-thermal therapy. Applications of Pt NPs in nanomedicine and nano-diagnosis are also highlighted. Pt NPs-related nanotoxicity and the potential and opportunity for future nano-therapeutics based on Pt NPs are also discussed.

Overcoming tumor microenvironment obstacles: Current approaches for boosting nanodrug delivery

In order to achieve targeted delivery of anticancer drugs, efficacy improvement, and side effect reduction, various types of nanoparticles are employed. However, their therapeutic effects are not ideal. This phenomenon is caused by tumor microenvironment abnormalities such as abnormal blood vessels, elevated interstitial fluid pressure, and dense extracellular matrix that affect nanoparticle penetration into the tumor's interstitium. Furthermore, nanoparticle properties including size, charge, and shape affect nanoparticle transport into tumors. This review comprehensively goes over the factors hindering nanoparticle penetration into tumors and describes methods for improving nanoparticle distribution by remodeling the tumor microenvironment and optimizing nanoparticle physicochemical properties. Finally, a critical analysis of future development of nanodrug delivery in oncology is further discussed. STATEMENT OF SIGNIFICANCE: This article reviews the factors that hinder the distribution of nanoparticles in tumors, and describes existing methods and approaches for improving the tumor accumulation from the aspects of remodeling the tumor microenvironment and optimizing the properties of nanoparticles. The description of the existing methods and approaches is followed by highlighting their advantages and disadvantages and put forward possible directions for the future researches. At last, the challenges of improving tumor accumulation in nanomedicines design were also discussed. This review will be of great interest to the broad readers who are committed to delivering nanomedicine for cancer treatment.

Recent Advances in the Role of Autophagy in Endocrine-Dependent Tumors

Autophagy plays a complex role in several cancer types, including endocrine-dependent cancers, by fueling cellular metabolism and clearing damaged substrates. This conserved recycling process has a dual function across tumor types where it can be tumor suppressive at early stages but tumor promotional in established disease. This review highlights the controversial roles of autophagy in endocrine-dependent tumors regarding cancer initiation, tumorigenesis, metastasis, and treatment response. We summarize clinical trial results thus far and highlight the need for additional mechanistic, preclinical, and clinical studies in endocrine-dependent tumors, particularly in breast cancer and prostate cancer.

The emerging promise of tumour mechanobiology in cancer treatment

Tumour cell biomechanics has lately came to the fore as a disparate feature that fosters cancer development and progression. Tumour mechanosensing entails a mechanical interplay amongst tumour cells, extracellular matrix (ECM) and cells of the tumour microenvironment (TME). Sensory receptors (mechanoceptors) detect changes of extracellular mechanical inputs such as various types of mechanical forces/stress and trigger oncogenic signalling pathways advocating for cancer initiation, growth, survival, angiogenesis, invasion, metastasis, and immune evasion. Moreover, alterations in ECM stiffness and potentiation of mechanostimulated transcriptional regulatory molecules (transcription factors/cofactors) have been shown to strongly correlate with resistance to anticancer drugs. On this basis, new mechanosensitive proteins emerge as potential therapeutic targets and/or biomarkers in cancer. Accordingly, tumour mechanobiology arises as a promising field that can potentially provide novel combinatorial regimens to reverse drug resistance, as well as offer unprecedented targeting approaches that may help to more effectively treat a large proportion of solid tumours and their complications. Here, we highlight recent findings regarding various aspects of tumour mechanobiology in the clinical setting and discuss evidence-based perspectives of developing diagnostic/prognostic tools and therapeutic approaches that exploit tumour-TME physical associations.

Dual targeting of Mg/N doped-carbon quantum dots with folic and hyaluronic acid for targeted drug delivery and cell imaging

Mg/N doped-carbon quantum dots (CQDs) with dual drug targeting and cell imaging properties was synthesized. Mg/N doped-CQDs synthesized by a hydrothermal method. Operating pyrolysis parameters such as temperature, time, and pH were optimized to achieve CQDs with high quantum yield (QY). This CQD applied in cellular imaging. For the first time, dual active targeting of Mg/N doped CQDs performed using folic acid and hyaluronic acid (CQD-FA-HA). Then, epirubicin (EPI) loaded on this nanocarrier as the final complex (CQD-FA-HA-EPI). Cytotoxicity analysis, cellular uptake, and cell photography performed for the complex on three cell lines, including 4T1, MCF-7, and CHO. In vivo studies were performed in BALB/c inbred female mice models bearing breast cancer. Characterization results showed the successful formation of Mg/N doped-CQDs with a high QY of 89.44%. In vitro drug release approved pH dependency of synthesized nanocarrier with a controlled release behavior. Cytotoxicity tests and cellular uptake results demonstrated increased toxicity and absorption into 4T1 and MCF-7 cell lines for targeted nanoparticles compared to free drug. In cell imaging, an increase in the entry of the complex into 4T1 and MCF-7 cells compared to free drug, confirmed the proper function of the synthesized complex. In vivo results indicated that the tumor volume of mice receiving CQD-FA-HA-EPI was the lowest among other studied groups, along with the lowest damage to the liver, spleen, and heart according to the histopathological analysis. Finally, CQD-FA-HA proposed as a novel platform with tumor targeting, drug carrier, and photoluminescence properties.

Advanced liposome and polymersome-based drug delivery systems: Considerations for physicochemical properties, targeting strategies and stimuli-sensitive approaches

Liposomes and polymersomes are colloidal vesicles that are self-assembled from lipids and amphiphilic polymers, respectively. Because of their ability to encapsulate both hydrophilic and hydrophobic therapeutics, they are of great interest in drug delivery research. Today, the applications of liposomes and polymersomes have expanded to a wide variety of complex therapeutic molecules, including nucleic acids, proteins and enzymes. Thanks to their chemical versatility, they can be tailored to different drug delivery applications to achieve maximum therapeutic index. This review article evaluates liposomes and polymersomes from a perspective that takes into account the physical and biological barriers that reduce the efficiency of the drug delivery process. In this context, the design approaches of liposomes and polymersomes are discussed with representative examples in terms of their physicochemical properties (size, shape, charge, mechanical), targeting strategies (passive and active) and response to different stimuli (pH, redox, enzyme, temperature, light, magnetic field, ultrasound). Finally, the challenges limiting the transition from laboratory to practice, recent clinical developments, and future perspectives are addressed.

Ultrasound-Responsive Biomimetic Superhydrophobic Drug-Loaded Mesoporous Silica Nanoparticles for Treating Prostate Tumor

Interfacial nanobubbles on a superhydrophobic surface can serve as ultrasound cavitation nuclei for continuously promoting sonodynamic therapy, but their poor dispersibility in blood has limited their biomedical application. In this study, we proposed ultrasound-responsive biomimetic superhydrophobic mesoporous silica nanoparticles, modified with red blood cell membrane and loaded with doxorubicin (DOX) (F-MSN-DOX@RBC), for RM-1 tumor sonodynamic therapy. Their mean size and zeta potentials were 232 ± 78.8 nm and −35.57 ± 0.74 mV, respectively. The F-MSN-DOX@RBC accumulation in a tumor was significantly higher than in the control group, and the spleen uptake of F-MSN-DOX@RBC was significantly reduced in comparison to that of the F-MSN-DOX group. Moreover, the cavitation caused by a single dose of F-MSN-DOX@RBC combined with multiple ultrasounds provided continuous sonodynamic therapy. The tumor inhibition rates in the experimental group were 71.5 8 ± 9.54%, which is significantly better than the control group. DHE and CD31 fluorescence staining was used to assess the reactive oxygen species (ROS) generated and the broken tumor vascular system induced by ultrasound. Finally, we can conclude that the combination of anti-vascular therapy, sonodynamic therapy by ROS, and chemotherapy promoted tumor treatment efficacy. The use of red blood cell membrane-modified superhydrophobic silica nanoparticles is a promising strategy in designing ultrasound-responsive nanoparticles to promote drug-release.

Sononeoperfusion: a new therapeutic effect to enhance tumour blood perfusion using diagnostic ultrasound and microbubbles

BACKGROUND

Hypoperfusion or resultant hypoxia in solid tumours is a main reason for therapeutic resistance. Augmenting the blood perfusion of hypovascular tumours might improve both hypoxia and drug delivery. Cavitation is known to result in microstreaming and sonoporation and to enhance drug diffusion into tumours. Here, we report the ability to enhance both tumour blood perfusion and doxorubicin (Dox) delivery using a new sononeoperfusion effect causing a cavitation effect on tumour perfusion in subcutaneous Walker-256 tumours of rats using ultrasound stimulated microbubble (USMB).

METHODS

To induce the sononeoperfusion effect, USMB treatment was performed with a modified diagnostic ultrasound (DUS) system and SonoVue® microbubbles. The therapeutic pulse was operated with a peak negative pressure of 0.26 to 0.32 MPa and a pulse repetition frequency (PRF) of 50 Hz to 2 kHz. Contrast-enhanced ultrasound (CEUS) was used for tumour perfusion assessment.

RESULTS

The USMB treatment of 0.26 MPa and 1 kHz could significantly enhance tumour perfusion with a 20.29% increase in the CEUS peak intensity and a 21.42% increment in the perfusion area for more than 4 hours (P < 0.05). The treatment also increased Dox delivery to tumours by approximately 3.12-fold more than that of the control (P < 0.05). Furthermore, ELISAs showed that vasodilators and inflammatory factors increased 4 hours after treatment (P < 0.05), suggesting that the inflammatory response plays an important role in the sononeoperfusion effect.

CONCLUSION

The USMB-induced sononeoperfusion effect could significantly enhance the blood perfusion of Walker-256 tumours and promote drug delivery. It might be a novel physical method for overcoming the therapeutic resistance of hypoperfused or hypoxic tumours.

Inhibition of CXCR4 Enhances the Efficacy of Radiotherapy in Metastatic Prostate Cancer Models

Radiotherapy (RT) is a standard treatment for patients with advanced prostate cancer (PCa). Previous preclinical studies showed that SDF1α/CXCR4 axis could mediate PCa metastasis (most often to the bones) and cancer resistance to RT. We found high levels of expression for both SDF1α and its receptor CXCR4 in primary and metastatic PCa tissue samples. In vitro analyses using PCa cells revealed an important role of CXCR4 in cell invasion but not radiotolerance. Pharmacologic inhibition of CXCR4 using AMD3100 showed no efficacy in orthotopic primary and bone metastatic PCa models. However, when combined with RT, AMD3100 potentiated the effect of local single-dose RT (12 Gy) in both models. Moreover, CXCR4 inhibition also reduced lymph node metastasis from primary PCa. Notably, CXCR4 inhibition promoted the normalization of bone metastatic PCa vasculature and reduced tissue hypoxia. In conclusion, the SDF1α/CXCR4 axis is a potential therapeutic target in metastatic PCa patients treated with RT.

Application of sequential cyclic compression on cancer cells in a flexible microdevice

Mechanical forces shape physiological structure and function within cell and tissue microenvironments, during which cells strive to restore their shape or develop an adaptive mechanism to maintain cell integrity depending on strength and type of the mechanical loading. While some cells are shown to experience permanent plastic deformation after a repetitive mechanical tensile loading and unloading, the impact of such repetitive compression on deformation of cells is yet to be understood. As such, the ability to apply cyclic compression is crucial for any experimental setup aimed at the study of mechanical compression taking place in cell and tissue microenvironments. Here, we demonstrate such cyclic compression using a microfluidic compression platform on live cell actin in SKOV-3 ovarian cancer cells. Live imaging of the actin cytoskeleton dynamics of the compressed cells was performed for varying pressures applied sequentially in ascending order during cell compression. Additionally, recovery of the compressed cells was investigated by capturing actin cytoskeleton and nuclei profiles of the cells at zero time and 24 h-recovery after compression in end point assays. This was performed for a range of mild pressures within the physiological range. Results showed that the phenotypical response of compressed cells during recovery after compression with 20.8 kPa differed observably from that for 15.6 kPa. This demonstrated the ability of the platform to aid in the capture of differences in cell behaviour as a result of being compressed at various pressures in physiologically relevant manner. Differences observed between compressed cells fixed at zero time or after 24 h-recovery suggest that SKOV-3 cells exhibit deformations at the time of the compression, a proposed mechanism cells use to prevent mechanical damage. Thus, biomechanical responses of SKOV-3 ovarian cancer cells to sequential cyclic compression and during recovery after compression could be revealed in a flexible microdevice. As demonstrated in this work, the observation of morphological, cytoskeletal and nuclear differences in compressed and non-compressed cells, with controlled micro-scale mechanical cell compression and recovery and using live-cell imaging, fluorescent tagging and end point assays, can give insights into the mechanics of cancer cells.

Dual "Unlocking" Strategy to Overcome Inefficient Nanomedicine Delivery and Tumor Hypoxia for Enhanced Photodynamic-Immunotherapy

Lacking blood vessels is one of the main characteristics of most solid tumors due to their rapid and unrestricted growth, which thus causes the inefficient delivery efficiency of nanomedicine and tumor hypoxia. Herein, a dual "unlocking" strategy to overcome these obstacles is proposed by combining engineered hybrid nanoparticles (named ZnPc@FOM-Pt) with dexamethasone (DXM). It is verified that pretreatment of tumors with DXM can increase intratumorally micro-vessel density (delivery "unlocking") to enhance the tumor delivery efficiency of ZnPc@FOM-Pt and decrease HIF-1α expression. Correspondingly, more Pt can catalyze tumor-overexpressed H₂ O₂ to produce oxygen to further cause hypoxia "unlocking," ultimately achieving boosted ZnPc-based photodynamic therapy in vivo (tumor inhibition rate: 99.1%). Moreover, the immunosuppressive tumor microenvironment is efficiently reversed and the therapeutic effect of anti-PD-L1-based immunotherapy is promoted by this newly designed nanomedicine. This dual "unlocking" strategy provides an innovative paradigm on simultaneously enhancing nanomedicine delivery efficacy and hypoxia relief for tumor therapy.

Microdevice-based mechanical compression on living cells

Compressive stress enables the investigation of a range of cellular processes in which forces play an important role, such as cell growth, differentiation, migration, and invasion. Such solid stress can be introduced externally to study cell response and to mechanically induce changes in cell morphology and behavior by static or dynamic compression. Microfluidics is a useful tool for this, allowing one to mimic in vivo microenvironments in on-chip culture systems where force application can be controlled spatially and temporally. Here, we review the mechanical compression applications on cells with a broad focus on studies using microtechnologies and microdevices to apply cell compression, in comparison to off-chip bulk systems. Due to their unique features, microfluidic systems developed to apply compressive forces on single cells, in 2D and 3D culture models, and compression in cancer microenvironments are emphasized. Research efforts in this field can help the development of mechanoceuticals in the future.

TGF-β signaling in lymphatic vascular vessel formation and maintenance

Transforming growth factor (TGF)-β and its family members, including bone morphogenetic proteins (BMPs), nodal proteins, and activins, are implicated in the development and maintenance of various organs. Here, we review its role in the lymphatic vascular system (the secondary vascular system in vertebrates), which plays a crucial role in various physiological and pathological processes, participating in the maintenance of the normal tissue fluid balance, immune cell trafficking, and fatty acid absorption in the gut. The lymphatic system is associated with pathogenesis in multiple diseases, including lymphedema, inflammatory diseases, and tumor metastasis. Lymphatic vessels are composed of lymphatic endothelial cells, which differentiate from blood vascular endothelial cells (BECs). Although TGF-β family signaling is essential for maintaining blood vessel function, little is known about the role of TGF-β in lymphatic homeostasis. Recently, we reported that endothelial-specific depletion of TGF-β signaling affects lymphatic function. These reports suggest that TGF-β signaling in lymphatic endothelial cells maintains the structure of lymphatic vessels and lymphatic homeostasis, and promotes tumor lymphatic metastasis. Suppression of TGF-β signaling in lymphatic endothelial cells may therefore be effective in inhibiting cancer metastasis. We highlight recent advances in understanding the roles of TGF-β signaling in the formation and maintenance of the lymphatic system.

Drug delivery in transarterial chemoembolization of hepatocellular carcinoma: Ex vivo evaluation using transparent tissue imaging

In this study, we elucidated for the first time the role of anti-cancer drugs in transarterial chemoembolization (TACE) via direct visualization of the spatial distribution of drugs with respect to blood vessels in intact transparent hepatocellular carcinoma (HCC) tissues. To date, precise estimation of drug penetration into tumors using thin 3D tissue sections has been challenging. This study utilized the tissue optical clearing technique to resolve the lack of tissue clarity, thereby enabling deep tissue imaging for the quantitative assessment of drug delivery following TACE. We compared the drug delivery effect, time-dependent embolic effect, and immunogenic response following conventional TACE (cTACE), drug-eluting embolic TACE (DEE-TACE), and transarterial embolization (TAE) in a rat model of HCC. After each treatment, three-dimensional drug delivery was quantitatively evaluated via the transparent liver tumor imaging, and time-dependent tumor necrosis was analyzed by serial tumor harvesting and histological staining. The results showed that chemotherapeutic agents travel only short distances after cTACE (∼80µm) and DEE-TACE (∼110µm), whereas necrosis occurs extensively within 24 h of treatment (85.3-97.2% of tumor cells). In addition, the percentages of CD4 and IL-17+ CD4 T cells increased significantly following treatment; however, drug-loading did not appear to affect the immune response following TACE. In conclusion, transarterially delivered chemotherapeutic agents appeared to exert a limited role, owing to the rapid and overwhelming effect of embolization. STATEMENT OF SIGNIFICANCE: TACE has been widely used for the treatment of HCC, especially for unresectable intermediate and advanced HCCs. Drug use in TACE is expected to provide patients with synergistic therapeutic benefits with the effect of embolic agents; however, the role of chemotherapeutic agents in TACE remains controversial. This study quantitatively verified that chemotherapeutic agents travel only short distances after TACE, while necrosis occurs extensively within 24h, and drug loading does not significantly affect immune responses following TACE. Three-dimensional imaging of intact transparent HCC can contribute to a better understanding of drug delivery mechanisms associated with TACE and also reveal that drug use in TACE may need to be reconsidered and limited to situations when embolization is expected to be insufficient.

Remarkable Remission Rate and Long-Term Efficacy of Upfront Metronomic Chemotherapy in Elderly and Frail Patients, with Diffuse Large B-Cell Lymphoma

The upfront treatment of very elderly and frail patients with diffuse large B-cell lymphoma (DLBCL) is still a matter of debate. Herein, we report results of the metronomic all-oral DEVEC [prednisolone/deltacortene®, vinorelbine (VNR), etoposide (ETO), cyclophosphamide] combined with i.v. rituximab (R). This schedule was administered as a first line therapy in 22 elderly/frail DLBCL subjects (median age = 84.5 years). In 17/22 (77%) patients, the Elderly-IPI-score was high. After a median follow-up of 24 months, 15 patients had died: seven (50%) for causes unrelated to DLBCL or its treatment, six (40%) for progression, and two (13%) for multiorgan failure. Six treatment-pertinent serious-adverse-events occurred. At the end of induction, 14/22 (64%) achieved complete remission; overall survival and event-free survival at 24 months were both 54% (95% CI = 32−72%), while the time to progression was 74% (95% CI = 48−88%). Furthermore, antiproliferative and proapoptotic assays were performed on DLBCL/OCI-LY3 cell-line using metronomic VNR and ETO and their combination. Both metronomic VNR and ETO had concentration-dependent antiproliferative (IC50 = 0.036 ± 0.01 nM and 7.9 ± 3.6 nM, respectively), and proapoptotic activities in DLBCL cells. Co-administration of the two drugs showed a strong synergism (combination index < 1 and dose reduction index > 1) against cell proliferation and survival. This low-dose schedule seems to compare favourably with intravenous-CHEMO protocols used in the same subset. Indeed, the high synergism shown by metronomic VRN+ETO in in vitro studies, explains the remarkable clinical responses and it allows significant dose reductions.

Do Tumor Mechanical Stresses Promote Cancer Immune Escape?

Immune evasion-a well-established cancer hallmark-is a major barrier to immunotherapy efficacy. While the molecular mechanisms and biological consequences underpinning immune evasion are largely known, the role of tissue mechanical stresses in these processes warrants further investigation. The tumor microenvironment (TME) features physical abnormalities (notably, increased fluid and solid pressures applied both inside and outside the TME) that drive cancer mechanopathologies. Strikingly, in response to these mechanical stresses, cancer cells upregulate canonical immune evasion mechanisms, including epithelial-mesenchymal transition (EMT) and autophagy. Consideration and characterization of the origins and consequences of tumor mechanical stresses in the TME may yield novel strategies to combat immunotherapy resistance. In this Perspective, we posit that tumor mechanical stresses-namely fluid shear and solid stresses-induce immune evasion by upregulating EMT and autophagy. In addition to exploring the basis for our hypothesis, we also identify explicit gaps in the field that need to be addressed in order to directly demonstrate the existence and importance of this biophysical relationship. Finally, we propose that reducing or neutralizing fluid shear stress and solid stress-induced cancer immune escape may improve immunotherapy outcomes.

A Nanomedicine Structure-Activity Framework for Research, Development, and Regulation of Future Cancer Therapies

Despite their clinical success in drug delivery applications, the potential of theranostic nanomedicines is hampered by mechanistic uncertainty and a lack of science-informed regulatory guidance. Both the therapeutic efficacy and the toxicity of nanoformulations are tightly controlled by the complex interplay of the nanoparticle's physicochemical properties and the individual patient/tumor biology; however, it can be difficult to correlate such information with observed outcomes. Additionally, as nanomedicine research attempts to gradually move away from large-scale animal testing, the need for computer-assisted solutions for evaluation will increase. Such models will depend on a clear understanding of structure-activity relationships. This review provides a comprehensive overview of the field of cancer nanomedicine and provides a knowledge framework and foundational interaction maps that can facilitate future research, assessments, and regulation. By forming three complementary maps profiling nanobio interactions and pathways at different levels of biological complexity, a clear picture of a nanoparticle's journey through the body and the therapeutic and adverse consequences of each potential interaction are presented.

Effects of Whole-Body Vibration on Breast Cancer Bone Metastasis and Vascularization in Mice

We evaluated whether whole-body vibration (WBV) prevented bone loss induced by breast cancer (BC) metastasis and the involvement of bone marrow vasculature. One day after orthotopic transplantation of mammary 4T1 tumor cells, 8-week-old BALB/c mice were subjected to 0.3 g/90 Hz vertical vibration for 20 min/day for 5 days/week (BC-WBV) or sham-handled (BC-Sham) over 3 weeks. Age-matched intact mice (Intact) were also sham-handled. Both tibiae were harvested from BC-WBV (n = 7), BC-Sham (n = 9), and Intact (n = 5) mice for bone structure imaging by synchrotron radiation-based computed tomography (SRCT) and hematoxylin and eosin staining, whereas right tibiae were harvested from other BC-WBV and BC-Sham (n = 6 each) mice for vascular imaging by SRCT. Tumor cells were similarly widespread in the marrow in BC-WBV and BC-Sham mice. In BC-Sham mice, cortical bone volume, trabecular volume fraction, trabecular thickness, trabecular number density, and bone mineral density were smaller, and marrow volume and trabecular separation were larger than in Intact mice. However, although trabecular thickness was smaller in BC-WBV than Intact mice, the others did not differ between the two groups. Serum osteocalcin tended to be higher in BC-WBV than BC-Sham mice. Compared with BC-Sham mice, BC-WBV mice had a smaller vessel diameter, a trend of a larger vessel number density, and smaller vessel diameter heterogeneity. In conclusion, WBV mitigates bone loss in BC bone metastasis, which may be partly due to increased bone anabolism. The alteration of marrow vasculature appears to be favorable for anti-tumor drug delivery. Further studies are needed to clarify the multiple actions of WBV on bone, tumor, and marrow vasculature and how they contribute to bone protection in BC metastasis.

Targeting Tumor Physical Microenvironment for Improved Radiotherapy

Radiotherapy has led to important clinical advances; existing cancer radiotherapy resistance is one remaining major challenge. Recently, biophysical cues in the tumor microenvironment (TME) have been regarded as the new hallmarks of cancer, playing pivotal roles in various cancer behaviors and treatment responses, including radiotherapy resistance. With recent advances in micro/nanotechnologies and functional biomaterials, radiotherapy exerts great influence on biophysical cues in TME, which, in turn, significantly affect the response to radiotherapy. Besides, various strategies have emerged that target biophysical cues in TME, to potentially enhance radiotherapy efficacy. Therefore, this paper reviews the four biophysical cues (i.e., extracellular matrix (ECM) microarchitecture, ECM stiffness, interstitial fluid pressure, and solid stress) that may play important roles in radiotherapy resistance, their possible mechanisms for inducing it, and their change after radiotherapy. The emerging therapeutic strategies targeting the biophysical microenvironment, to explore the mechanism of radiotherapy resistance and develop effective strategies to revert it for improved treatment efficacy are further summarized.

Nanoparticle-Based Drug Delivery Systems Targeting Tumor Microenvironment for Cancer Immunotherapy Resistance: Current Advances and Applications

Cancer immunotherapy has shown impressive anti-tumor activity in patients with advanced and early-stage malignant tumors, thus improving long-term survival. However, current cancer immunotherapy is limited by barriers such as low tumor specificity, poor response rate, and systemic toxicities, which result in the development of primary, adaptive, or acquired resistance. Immunotherapy resistance has complex mechanisms that depend on the interaction between tumor cells and the tumor microenvironment (TME). Therefore, targeting TME has recently received attention as a feasibility strategy for re-sensitizing resistant neoplastic niches to existing cancer immunotherapy. With the development of nanotechnology, nanoplatforms possess outstanding features, including high loading capacity, tunable porosity, and specific targeting to the desired locus. Therefore, nanoplatforms can significantly improve the effectiveness of immunotherapy while reducing its toxic and side effects on non-target cells that receive intense attention in cancer immunotherapy. This review explores the mechanisms of tumor microenvironment reprogramming in immunotherapy resistance, including TAMs, CAFs, vasculature, and hypoxia. We also examined whether the application of nano-drugs combined with current regimens is improving immunotherapy clinical outcomes in solid tumors.

The ambivalent nature of the relationship between lymphatics and cancer

Do lymphatic vessels support cancer cells? Or are they vessels that help suppress cancer development? It is known that the lymphatic system is a vehicle for tumor metastasis and that the lymphangiogenic regulator VEGF-C supports the tumor. One such role of VEGF-C is the suppression of the immune response to cancer. The lymphatic system has also been correlated with an increase in interstitial fluid pressure of the tumor microenvironment. On the other hand, lymphatic vessels facilitate immune surveillance to mount an immune response against tumors with the support of VEGF-C. Furthermore, the activation of lymphatic fluid drainage may prove to filter and decrease tumor interstitial fluid pressure. In this review, we provide an overview of the dynamic between lymphatics, cancer, and tumor fluid pressure to suggest that lymphatic vessels may be used as an antitumor therapy due to their capabilities of immune surveillance and fluid pressure drainage. The application of this potential may help to prevent tumor proliferation or increase the efficacy of drugs that target cancer.

Advances of Epigenetic Biomarkers and Epigenome Editing for Early Diagnosis in Breast Cancer

Epigenetic modifications are known to regulate cell phenotype during cancer progression, including breast cancer. Unlike genetic alterations, changes in the epigenome are reversible, thus potentially reversed by epi-drugs. Breast cancer, the most common cause of cancer death worldwide in women, encompasses multiple histopathological and molecular subtypes. Several lines of evidence demonstrated distortion of the epigenetic landscape in breast cancer. Interestingly, mammary cells isolated from breast cancer patients and cultured ex vivo maintained the tumorigenic phenotype and exhibited aberrant epigenetic modifications. Recent studies indicated that the therapeutic efficiency for breast cancer regimens has increased over time, resulting in reduced mortality. Future medical treatment for breast cancer patients, however, will likely depend upon a better understanding of epigenetic modifications. The present review aims to outline different epigenetic mechanisms including DNA methylation, histone modifications, and ncRNAs with their impact on breast cancer, as well as to discuss studies highlighting the central role of epigenetic mechanisms in breast cancer pathogenesis. We propose new research areas that may facilitate locus-specific epigenome editing as breast cancer therapeutics.

A brief glimpse of a tangled web in a small world: Tumor microenvironment

A tumor is a result of stepwise accumulation of genetic and epigenetic alterations. This notion has deepened the understanding of cancer biology and has introduced the era of targeted therapies. On the other hand, there have been a series of attempts of using the immune system to treat tumors, dating back to ancient history, to sporadic reports of inflamed tumors undergoing spontaneous regression. This was succeeded by modern immunotherapies and immune checkpoint inhibitors. The recent breakthrough has broadened the sight to other players within tumor tissue. Tumor microenvironment is a niche or a system orchestrating reciprocal and dynamic interaction of various types of cells including tumor cells and non-cellular components. The output of this complex communication dictates the functions of the constituent elements present within it. More complicated factors are biochemical and biophysical settings unique to TME. This mini review provides a brief guide on a range of factors to consider in the TME research.

The mechanistic immunosuppressive role of the tumour vasculature and potential nanoparticle-mediated therapeutic strategies

The tumour vasculature is well-established to display irregular structure and hierarchy that is conducive to promoting tumour growth and metastasis while maintaining immunosuppression. As tumours grow, their metabolic rate increases while their distance from blood vessels furthers, generating a hypoxic and acidic tumour microenvironment. Consequently, cancer cells upregulate the expression of pro-angiogenic factors which propagate aberrant blood vessel formation. This generates atypical vascular features that reduce chemotherapy, radiotherapy, and immunotherapy efficacy. Therefore, the development of therapies aiming to restore the vasculature to a functional state remains a necessary research target. Many anti-angiogenic therapies aim to target this such as bevacizumab or sunitinib but have shown variable efficacy in solid tumours due to intrinsic or acquired resistance. Therefore, novel therapeutic strategies such as combination therapies and nanotechnology-mediated therapies may provide alternatives to overcoming the barriers generated by the tumour vasculature. This review summarises the mechanisms that induce abnormal tumour angiogenesis and how the vasculature’s features elicit immunosuppression. Furthermore, the review explores examples of treatment regiments that target the tumour vasculature.

Coupling solid and fluid stresses with brain tumour growth and white matter tract deformations in a neuroimaging-informed model

Brain tumours are among the deadliest types of cancer, since they display a strong ability to invade the surrounding tissues and an extensive resistance to common therapeutic treatments. It is therefore important to reproduce the heterogeneity of brain microstructure through mathematical and computational models, that can provide powerful instruments to investigate cancer progression. However, only a few models include a proper mechanical and constitutive description of brain tissue, which instead may be relevant to predict the progression of the pathology and to analyse the reorganization of healthy tissues occurring during tumour growth and, possibly, after surgical resection. Motivated by the need to enrich the description of brain cancer growth through mechanics, in this paper we present a mathematical multiphase model that explicitly includes brain hyperelasticity. We find that our mechanical description allows to evaluate the impact of the growing tumour mass on the surrounding healthy tissue, quantifying the displacements, deformations, and stresses induced by its proliferation. At the same time, the knowledge of the mechanical variables may be used to model the stress-induced inhibition of growth, as well as to properly modify the preferential directions of white matter tracts as a consequence of deformations caused by the tumour. Finally, the simulations of our model are implemented in a personalized framework, which allows to incorporate the realistic brain geometry, the patient-specific diffusion and permeability tensors reconstructed from imaging data and to modify them as a consequence of the mechanical deformation due to cancer growth.