Tumour-associated macrophages act as a slow-release reservoir of nano-therapeutic Pt(IV) pro-drug

Exploring the efficacy and constraints of platinum nanoparticles as adjuvant therapy in silicosis management

Silicosis represents a formidable occupational lung pathology precipitated by the pulmonary assimilation of respirable crystalline silica particulates. This condition engenders a cascade of cellular oxidative stress via the activation of bioavailable silica, culminating in the generation of reactive oxygen species (ROS). Such oxidative mechanisms lead to irrevocable pulmonary impairment. Contemporary scholarly examinations have underscored the substantial antioxidative efficacy of platinum nanoparticles (PtNPs), postulating their utility as an adjunct therapeutic modality in silicosis management. The physicochemical interaction between PtNPs and silica demonstrates a propensity for adsorption, thereby facilitating the amelioration and subsequent pulmonary clearance of silica aggregates. In addition to their detoxifying attributes, PtNPs exhibit pronounced anti-inflammatory and antioxidative activities, which can neutralize ROS and inhibit macrophage-mediated inflammatory processes. Such attributes are instrumental in attenuating inflammatory responses and forestalling subsequent lung tissue damage. This discourse delineates the interplay between ROS and PtNPs, the pathogenesis of silicosis and its progression to pulmonary fibrosis, and critically evaluates the potential adjunct role of PtNPs in the therapeutic landscape of silicosis, alongside a contemplation of the inherent limitations associated with PtNPs application in this context.

Ionizable Lipids Drive Subcellular Localization and Immune Cell Targeting of Barcoded Nanoparticles in Lung Cancer

To accurately predict the effect of a drug and enhance its potency, it is essential to examine not only the arrival of the carrier and its payload at the target cell but also the final destination of the subcellular organelle because a considerable number of diseases are associated with the malfunctioning of cellular organelles. Here, we present nanoparticle (NP) microscopy via signal amplification of DNA barcodes combined with the multiplexed cyclic immunofluorescence technique for quantifying multiple NP types simultaneously. This technique enhanced the fluorescence signal-to-noise by 15-fold compared to standard fluorescence in situ hybridization, thereby providing a more precise means of analyzing the intra- and interdistribution of three core-shell NPs (G0-P5, 7C1-F5, and C12-D) in vitro and in vivo. The in vitro results demonstrated that in macrophages, nucleic acids condensed with G0-C14 cationic lipids were often located in lysosomes, whereas in tumor cells, nucleic acids were mainly located in mitochondria, regardless of the type of cationic lipid. Together, the in vivo results reveal that nucleic acids condensed with G0-C14 cationic lipids demonstrated the greatest uptake by CD206+ immune cells, whereas nucleic acids condensed with 7C1 and C12-200 cationic lipids exhibited the highest level of uptake by CD206+CD11c+Arg1+ immune cells.

Developing bioinspired delivery systems for enhanced tumor penetration of macromolecular drugs

Macromolecular drugs, such as proteins and nucleic acids, play a pivotal role in treating refractory diseases and hold significant promise in the growing pharmaceutical market. However, without efficient delivery systems, macromolecular drugs are highly susceptible to rapid biodegradation or systemic clearance, underscoring the need for advanced delivery strategies for clinical translation. A major challenge lies in their limited tissue penetration due to large molecular weight and size, which has recently garnered significant attention as it often leads to therapeutic failure or the emergence of resistance. In this review, we first outline the biological barriers limiting macromolecular tissue penetration, then explore the inherent permeation mechanisms of biomacromolecules in biological systems. We then highlight delivery strategies aimed at enhancing the tissue penetration of macromolecular therapeutics, with a particular focus on tissue-adaptive and tissue-remodeling delivery platforms. Finally, we provide a concise perspective on future research directions in deep tissue penetration for biomacromolecules. This review offers a comprehensive summary of recent advancements and presents critical insights into optimizing the therapeutic efficacy of macromolecular drugs.

A review on biomacromolecular ligand-directed nanoparticles: New era in macrophage targeting

Traditional drug delivery strategies often have side effects due to uneven drug distribution leading to the subtherapeutic impacts. Ligand-modified nanoparticles offer a revolutionary approach to precise drug delivery. These modified nanoparticles can potentially target macrophages, which is crucial for defense and disease progression efficiently. Out of many classes of ligands, biomacromolecular ligands emerged as potential ligands for directing these nanoparticles to macrophages due to their consecutive receptors over the macrophage surface, assisting easy internalization and thus supporting elevated efficacy and reduced toxicity. This approach could significantly improve treatment for diseases like cancer, tuberculosis, etc. by directing drugs to macrophages and reducing side effects. By leveraging nanotechnology and biomacromolecular-based ligand-directed targeting, we can achieve more precise and effective treatments, paving the way for advancements in precision medicine.

Effect of Prodrug Activation Rate on In Vivo Drug Release and Antitumor Efficacy of SN38-Prodrug-Entrapped Liposomes

The aim of this study is to investigate the effects of prodrug activation rates on the in vivo drug release and antitumor activity of prodrug-entrapped liposomes. We performed such an investigation using two liposomes encapsulating hydrophilic SN38-glutathione (GSH) prodrugs (linked at 10- and 20-hydroxy of SN38) with different activation rates. The results showed that SN38-GSH was first released from liposomes and, consequently, activated into SN38. The SN38-GSH release rate from liposomes was similar, but the 10SN38-GSH activated much faster than 20SN38-GSH (t1/2, < 1 min versus ∼60 min) in plasma. Such different activation rates did not influence the prodrug's pharmacokinetics and biodistribution, but the fast prodrug activation rate resulted in 4-6-fold higher SN38 concentration in various organs and led to more potent antitumor efficacy. By contrast, the slowly activated SN38-GSH liposomes failed to exhibit potent antitumor activity, even at the maximum tolerance dose. Our data illustrated how the prodrug activation rate influences in vivo drug release and antitumor activity of prodrug-loaded liposomes, suggesting that sufficient prodrug activation is a prerequisite for potent prodrug-loaded liposomes.

Unlocking the power of imidazoquinolines: recent advances in anticancer and immunotherapeutic strategies

The challenges in drug discovery aiming to mitigate cancer progression are the thrust area of scientific research for several decades. Since the advent of heterocyclic chemistry, drug discovery programs have made significant achievements that lead to the development of numerous drugs with broad spectrum of potencies, contributing to both diagnostic and therapeutic advancements. Till date, efforts to discover more potent and efficient drug candidates are underway to minimize adverse side effects of existing chemotherapeutics. In view of the above, small-molecule agonists that can interact with different immune modulators like toll like receptor-7 (TLR-7) and TLR-8 are being investigated and explored. These candidates are expected to display profound effect on anti-tumoral activity by enhancing the production of proinflammatory cytokines. Recently, numerous imidazoquinoline derivatives with proven TLR agonist activities have emerged as promising anticancer therapeutics. With advancements in technology and the evolution of new scopes in drug discovery, different strategies are being adopted, particularly with the help of nanotechnology, immune-technology, combination drug chemistry, etc., to curb the progression of various types of cancers. Herein, the novel strategies for cancer therapeutics with imidazoquinolines reported in the last 5 years, their structure-activity relationship along with important synthetic schemes for important TLR agonists, are discussed.

Beyond the EPR effect: Intravital microscopy analysis of nanoparticle drug delivery to tumors

Delivery of nanoparticles (NPs) to solid tumors has long relied on enhanced permeability and retention (EPR) effect, involving permeation of NPs through a leaky vasculature with prolonged retention by reduced lymphatic drainage in tumor. Recent research studies and clinical data challenge EPR concept, revealing alternative pathways and approaches of NP delivery. The area was significantly impacted by the implementation of intravital optical microscopy, unraveling delivery mechanisms at cellular level in vivo. This review presents analysis of the reasons for EPR heterogeneity in tumors and describes non-EPR based concepts for drug delivery, which can supplement the current paradigm. One of the approaches is targeting tumor endothelium by NPs with subsequent intravascular drug release and gradient-driven drug transport to tumor interstitium. Others exploit various immune cells for tumor infiltration and breaking endothelial barriers. Finally, we discuss the involvement of active transcytosis through endothelial cells in NP delivery. This review aims to inspire further understanding of the process of NP extravasation in tumors and provide insights for developing next-generation nanomedicines with improved delivery.

Pulmonary delivery of dual-targeted nanoparticles improves tumor accumulation and cancer cell targeting by restricting macrophage interception in orthotopic lung tumors

Despite the recognized potential of inhaled nanomedicines to enhance and sustain local drug concentrations for lung cancer treatment, the influence of macrophage uptake on targeted nanoparticle delivery to and within tumors remains unclear. Here, we developed three ligand-coated nanoparticles for pulmonary delivery in lung cancer therapy: phenylboronic acid-modified nanoparticles (PBA-NPs), PBA combined with folic acid (FA-PBA-NPs), and PBA with mannose (MAN-PBA-NPs). In vitro, MAN-PBA-NPs were preferentially internalized by macrophages, whereas FA-PBA-NPs exhibited superior uptake by cancer cells compared to macrophages. Following intratracheal instillation into mice with orthotopic Lewis lung carcinoma tumors, all three nanoparticles showed similar lung retention. However, MAN-PBA-NPs were more prone to interception by lung macrophages, which limited their accumulation in tumor tissues. In contrast, both PBA-NPs and FA-PBA-NPs achieved comparable high tumor accumulation (∼11.3% of the dose). Furthermore, FA-PBA-NPs were internalized by ∼30% of cancer cells, significantly more than the 10-18% seen with PBA-NPs or MAN-PBA-NPs. Additionally, FA-PBA-NPs loaded with icaritin effectively inhibited the Wnt/β-catenin pathway, resulting in superior anti-tumor efficacy through targeted cancer cell delivery. Overall, FA-PBA-NPs demonstrated advantageous competitive uptake kinetics by cancer cells compared to macrophages, enhancing tumor targeting and therapeutic outcomes.

Advancing neurological disorders therapies: Organic nanoparticles as a key to blood-brain barrier penetration

The blood-brain barrier (BBB) plays a vital role in protecting the central nervous system (CNS) by preventing the entry of harmful pathogens from the bloodstream. However, this barrier also presents a significant obstacle when it comes to delivering drugs for the treatment of neurodegenerative diseases and brain cancer. Recent breakthroughs in nanotechnology have paved the way for the creation of a wide range of nanoparticles (NPs) that can serve as carriers for diagnosis and therapy. Regarding their promising properties, organic NPs have the potential to be used as effective carriers for drug delivery across the BBB based on recent advancements. These remarkable NPs have the ability to penetrate the BBB using various mechanisms. This review offers a comprehensive examination of the intricate structure and distinct properties of the BBB, emphasizing its crucial function in preserving brain balance and regulating the transport of ions and molecules. The disruption of the BBB in conditions such as stroke, Alzheimer's disease, and Parkinson's disease highlights the importance of developing creative approaches for delivering drugs. Through the encapsulation of therapeutic molecules and the precise targeting of transport processes in the brain vasculature, organic NP formulations present a hopeful strategy to improve drug transport across the BBB. We explore the changes in properties of the BBB in various pathological conditions and investigate the factors that affect the successful delivery of organic NPs into the brain. In addition, we explore the most promising delivery systems associated with NPs that have shown positive results in treating neurodegenerative and ischemic disorders. This review opens up new possibilities for nanotechnology-based therapies in cerebral diseases.

Nomadic Nanomedicines: Medicines Enabled by the Paracrine Transfer Effect

In nanomedicine, the cellular export of nanomaterials has been less explored than uptake. Traditionally viewed in a negative light, recent findings highlight the potential of nanomedicine export to enhance therapeutic effects. This Perspective examines key pathways for export and how nanomaterial design affects removal rates. We present the idea of the "paracrine transfer effect" (PTE), where nanomaterials are first internalized by a "waypoint" cell and then exported to a "destination" cell, influencing both in potentially exploitable ways. Essential characteristics for nanomedicines to leverage the PTE are discussed, along with two case studies: STING-stimulating polymeric nanoparticles and TLR9-stimulating liposomal spherical nucleic acids. We propose future research directions to better understand and utilize the PTE in developing more effective nanomedicines.

Unraveling the Role of the Tumor Extracellular Matrix to Inform Nanoparticle Design for Nanomedicine

The extracellular matrix (ECM)-and its mechanobiology-regulates key cellular functions that drive tumor growth and development. Accordingly, mechanotherapy is emerging as an effective approach to treat fibrotic diseases such as cancer. Through restoring the ECM to healthy-like conditions, this treatment aims to improve tissue perfusion, facilitating the delivery of chemotherapies. In particular, the manipulation of ECM is gaining interest as a valuable strategy for developing innovative treatments based on nanoparticles (NPs). However, further progress is required; for instance, it is known that the presence of a dense ECM, which hampers the penetration of NPs, primarily impacts the efficacy of nanomedicines. Furthermore, most 2D in vitro studies fail to recapitulate the physiological deposition of matrix components. To address these issues, a comprehensive understanding of the interactions between the ECM and NPs is needed. This review focuses on the main features of the ECM and its complex interplay with NPs. Recent advances in mechanotherapy are discussed and insights are offered into how its combination with nanomedicine can help improve nanomaterials design and advance their clinical translation.

Leveraging insights from cancer to improve tuberculosis therapy

Exploring and exploiting the microenvironmental similarities between pulmonary tuberculosis (TB) granulomas and malignant tumors has revealed new strategies for more efficacious host-directed therapies (HDTs). This opinion article discusses a paradigm shift in TB therapeutic development, drawing on critical insights from oncology. We summarize recent efforts to characterize and overcome key shared features between tumors and granulomas, including excessive fibrosis, abnormal angiogenesis, hypoxia and necrosis, and immunosuppression. We provide specific examples of cancer therapy application to TB to overcome these microenvironmental abnormalities, including matrix-targeting therapies, antiangiogenic agents, and immune-stimulatory drugs. Finally, we propose a new framework for combining HDTs with anti-TB agents to maximize therapeutic delivery and efficacy while reducing treatment dosages, duration, and harmful side effects to benefit TB patients.

Engineering immunity using metabolically active polymeric nanoparticles

Immune system functions play crucial roles in both health and disease, and these functions are regulated by their metabolic programming. The field of immune engineering has emerged to develop therapeutic strategies, including polymeric nanoparticles (NPs), that can direct immune cell phenotype and function by directing immunometabolic changes. Precise control of bioenergetic processes may offer the opportunity to prevent undesired immune activity and improve disease-specific outcomes. In this review we discuss the role that polymeric NPs can play in shaping immunometabolism and subsequent immune system activity through particle-mediated delivery of metabolically active agents as either structural components or cargo.

Nanotherapeutics for Macrophage Network Modulation in Tumor Microenvironments: Targets and Tools

Macrophage is an important component in the tumor immune microenvironment, which exerts significant influence on tumor development and metastasis. Due to their dual nature of promoting and suppressing inflammation, macrophages can serve as both targets for tumor immunotherapy and tools for treating malignancies. However, the abundant infiltration of tumor-associated macrophages dominated by an immunosuppressive phenotype maintains a pro-tumor microenvironment, and engineering macrophages using nanotechnology to manipulate the tumor immune microenvironment represent a feasible approach for cancer immunotherapy. Additionally, considering the phagocytic and specifically tumor-targeting capabilities of M1 macrophages, macrophages manipulated through cellular engineering and nanotechnology, as well as macrophage-derived exosomes and macrophage membranes, can also become effective tools for cancer treatment. In conclusion, nanotherapeutics targeting macrophages remains immense potential for the development of macrophage-mediated tumor treatment methods and will further enhance our understanding, diagnosis, and treatment of various malignants.

Polyinosinic/Polycytidylic Lipid Nanoparticles Enhance Immune Cell Infiltration and Improve Survival in the Glioblastoma Mouse Model

Glioblastoma (GBM) immunotherapy is particularly challenging due to the pro-tumorigenic microenvironment, marked by low levels and inactive immune cells. Toll-like receptor (TLR) agonists have emerged as potent immune adjuvants but failed to show improved outcomes in clinical trials when administered as a monotherapy. We hypothesize that a combined nanoparticulate formulation of TLR agonist and immunogenic cell death-inducing drug (doxorubicin) will synergize to induce improved GBM immunotherapy. Lipid nanoparticle (LNP) formulations of the TLR agonists CpG and polyinosinic/polycytidylic (pIpC), with and without Dox, were first prepared, achieving an encapsulation efficiency >75% and a size <140 nm. In vitro studies identified that LNP pIpC was superior to CpG at activating bone marrow-derived immune cell populations (dendritic cells and macrophages) with minimal toxicity. It was also observed that the pIpC formulation can skew macrophage polarization toward the antitumorigenic M1 phenotype and increase macrophage phagocytosis of cancer cells. Upon intratumoral administration, pIpC Dox LNPs led to significant immune cell infiltration and activation. In survival models, the inclusion of Dox into pIpC LNP improved mice survival compared to control. However, addition of Dox did not show significant improvement in mice's survival compared to singly formulated pIpC LNP. This study has illustrated the potential of pIpC LNP formulations in prospective GBM immunotherapeutic regimes. Future studies will focus on optimizing dosage regimen and/or combination with other modalities, including the standard of care (temozolomide), immune checkpoint blockade, or cancer vaccines.

Liposomal Doxorubicin, Vinblastine and Dacarbazine Plus Consolidation Radiotherapy of Residual Nodal Masses for Frontline Treatment in Older Adults With Advanced Stage Classic Hodgkin Lymphoma: Improved Outcome in a Multi-Center Real-Life Study

In elderly patients with high-risk classic Hodgkin lymphoma (c-HL), we evaluated the impact of a new modality treatment without bleomycin, that is, liposomal doxorubicin (NPLD)-based regimen plus consolidation radiotherapy of residual nodal masses (RNMs), on overall survival (OS) and progression free survival (PFS). In this retrospective study (2013-2023) conducted in tertiary hospitals in the bay of Naples (Italy), 50 older adults (median age, 69 years; range, 60-89) with advanced stage c-HL received frontline treatment with MVD ± irradiation. MVD consisted of 25 mg/m2 of NPLD along with standard Vinblastine and Dacarbazine for a total of 6 cycles (twelve iv administrations, every 2 weeks) followed by radiation of RNMs with size ≥ 2.5 cm at computed tomography. Patients underwent MVD with a median dose intensity of 92%. At 2-deoxy-2[F-18] fluoro-D-glucose positron emission tomography (FDG-PET), 90% of patients (45/50 patients; one failed to perform final FDG-PET due to early death) reached complete responses. Altogether, 17 patients (34%) received consolidation radiotherapy of RNMs with Deauville score ≥ 3. At 5-year median follow-up, the OS and PFS of the entire population were 87.5% (95% confidence interval [CI], 78.7-97.4) and 81.6% (95% CI, 71.4-93.2), respectively. Eleven patients (22%) experienced grade ≥ 3 adverse events, and 4 of them required hospitalization. Our data suggest that in older adults with high-risk c-HL NPLD-driven strategy (without bleomycin) plus consolidation radiotherapy (if needed) may be a promising up-front option, to test in phase II clinical trials for improving survival incidence.

Histopathological biomarkers for predicting the tumour accumulation of nanomedicines

The clinical prospects of cancer nanomedicines depend on effective patient stratification. Here we report the identification of predictive biomarkers of the accumulation of nanomedicines in tumour tissue. By using supervised machine learning on data of the accumulation of nanomedicines in tumour models in mice, we identified the densities of blood vessels and of tumour-associated macrophages as key predictive features. On the basis of these two features, we derived a biomarker score correlating with the concentration of liposomal doxorubicin in tumours and validated it in three syngeneic tumour models in immunocompetent mice and in four cell-line-derived and six patient-derived tumour xenografts in mice. The score effectively discriminated tumours according to the accumulation of nanomedicines (high versus low), with an area under the receiver operating characteristic curve of 0.91. Histopathological assessment of 30 tumour specimens from patients and of 28 corresponding primary tumour biopsies confirmed the score's effectiveness in predicting the tumour accumulation of liposomal doxorubicin. Biomarkers of the tumour accumulation of nanomedicines may aid the stratification of patients in clinical trials of cancer nanomedicines.

Self-assembled hyaluronic acid nanomicelle for enhanced cascade cancer chemotherapy via self-sensitized ferroptosis

The clinical utility of chemotherapy is often compromised by its limited efficacy and significant side effects. Addressing these concerns, we have developed a self-assembled nanomicelle, namely SANTA FE OXA, which consists of hyaluronic acid (HA) conjugated with ferrocene methanol (FC), oxaliplatin prodrug (OXA(IV)) and ethylene glycol-coupled linoleic acid (EG-LA). Targeted delivery is achieved by HA binding to the CD44 receptors that are overexpressed on tumor cells, facilitating drug uptake. Once internalized, hyaluronidase (HAase) catalyzes the digestion of the SANTA FE OXA, releasing FC and reducing OXA(IV) into an active form. The active oxaliplatin (OXA) induces DNA damage and increases intracellular hydrogen peroxide (H2O2) levels via cascade reactions. Simultaneously, FC disrupts the redox balance within tumor cells, inducing ferroptosis. Both in vivo and in vitro experiments confirmed that SANTA FE OXA inhibited tumor growth by combining cascade chemotherapy and self-sensitized ferroptosis, achieving a tumor inhibition rate of up to 76.61 %. Moreover, this SANTA FE OXA significantly mitigates the systemic toxicity commonly associated with platinum-based chemotherapeutics. Our findings represent a compelling advancement in nanomedicine for enhanced cascade cancer therapy.

Different leukocyte subsets are targeted by systemic and locoregional administration despite conserved nanomaterial characteristics optimal for lymph node delivery

Lymph nodes (LNs) house a large proportion of the body's leukocytes. Accordingly, engineered nanomaterials are increasingly developed to direct therapeutics to LNs to enhance their efficacy. Yet while lymphatic delivery of nanomaterials to LNs upon locoregional injection has been extensively evaluated, nanomaterial delivery to LN-localized leukocytes after intravenous administration has not been systematically explored nor benchmarked. In this work, a panel of inert, fluorescent nanoscale tracers and drug delivery vehicles were utilized to interrogate intravenous versus locoregionally administered nanomaterial access to LNs and leukocyte subsets therein. Hydrodynamic size and material effects on LN accumulation extents were similar between intravenous versus intradermal injection routes. Nanomaterial distribution to various LN leukocyte subsets differed substantially with injection route, however, in a manner not proportional to total LN accumulation. While intravenously administered nanomaterials accumulated in LNs lowly compared to systemic tissues, in sharp contrast to locoregional delivery, they exhibited size-dependent but material-independent access to immune cells within the LN parenchyma, which are not easily accessed with locoregional delivery.

Targeting tumor-associated macrophages with nanocarrier-based treatment for breast cancer: A step toward developing innovative anti-cancer therapeutics

Tumor-associated macrophages (TAMs) promote tumor advancement in many ways, such as inducing angiogenesis and the formation of new blood vessels that provide tumors with nourishment and oxygen. TAMs also facilitate tumor invasion and metastasis by secreting enzymes that degrade the extracellular matrix and generating pro-inflammatory cytokines that enhance the migration of tumor cells. TAMs also have a role in inhibiting the immune response against malignancies. To accomplish this, they release immunosuppressive cytokines such as IL-10, and TAMs can hinder the function of T cells and natural killer cells, which play crucial roles in the immune system's ability to combat cancer. The role of TAMs in breast cancer advancement is a complex and dynamic field of research. Therefore, TAMs are a highly favorable focus for innovative breast cancer treatments. This review presents an extensive overview of the correlation between TAMs and breast cancer development as well as its role in the tumor microenvironment (TME) shedding light on their impact on tumor advancement and immune evasion mechanisms. Notably, our study provides an innovative approach to employing nanomedicine approaches for targeted TAM therapy in breast cancer, providing an in-depth overview of recent advances in this emerging field.

Engineering Novel Amphiphilic Platinum(IV) Complexes to Co-Deliver Cisplatin and Doxorubicin

In this study, we report a novel platinum-doxorubicin conjugate that demonstrates superior therapeutic indices to cisplatin, doxorubicin, or their combination, which are commonly used in cancer treatment. This new molecular structure (1) was formed by conjugating an amphiphilic Pt(IV) prodrug of cisplatin with doxorubicin. Due to its amphiphilic nature, the Pt(IV)-doxorubicin conjugate effectively penetrates cell membranes, delivering both cisplatin and doxorubicin payloads intracellularly. The intracellular accumulation of these payloads was assessed using graphite furnace atomic absorption spectrometry and fluorescence imaging. Since the therapeutic effects of cisplatin and doxorubicin stem from their ability to target nuclear DNA, we hypothesized that the amphiphilic Pt(IV)-doxorubicin conjugate (1) would effectively induce nuclear DNA damage toward killing cancer cells. To test this hypothesis, we used flow the cytometric analysis of phosphorylated H2AX (γH2AX), a biomarker of nuclear DNA damage. The Pt(IV)-doxorubicin conjugate (1) markedly induced γH2AX in treated MDA-MB-231 breast cancer cells, showing higher levels than cells treated with either cisplatin or doxorubicin alone. Furthermore, MTT cell viability assays revealed that the enhanced DNA-damaging capability of complex 1 resulted in superior cytotoxicity and selectivity against human cancer cells compared to cisplatin, doxorubicin, or their combination. Overall, the development of this amphiphilic Pt(IV)-doxorubicin conjugate represents a new form of combination therapy with improved therapeutic efficacy.

NIR Light and GSH Dual-Responsive Upconversion Nanoparticles Loaded with Multifunctional Platinum(IV) Prodrug and RGD Peptide for Precise Cancer Therapy

Platinum(II) drugs as a first-line anticancer reagent are limited by side effects and drug resistance. Stimuli-responsive nanosystems hold promise for precise spatiotemporal manipulation of drug delivery, with the aim to promote bioavailability and minimize side effects. Herein, a multitargeting octahedral platinum(IV) prodrug with octadecyl aliphatic chain and histone deacetylase inhibitor (phenylbutyric acid, PHB) at axial positions to improve the therapeutic effect of cisplatin was loaded on the upconversion nanoparticles (UCNPs) through hydrophobic interaction. Followed attachment of DSPE-PEG2000 and arginine-glycine-aspartic (RGD) peptide endowed the nanovehicles with high biocompatibility and tumor specificity. The fabricated nanoparticles (UCNP/Pt(IV)-RGD) can be triggered by upconversion luminescence (UCL) irradiation and glutathione (GSH) reduction to controllably release Pt(II) species and PHB, inducing profound cytotoxicity. Both in vitro and in vivo experiments demonstrated that UCNP/Pt(IV)-RGD exhibited remarkable antitumor efficiency, high tumor-targeting specificity, and real-time UCL imaging capacity, presenting an intelligent platinum(IV) prodrug-loaded nanovehicle for UCL-guided dual-stimuli-responsive combination therapy.

Pharmacokinetic-Pharmacodynamic Analysis of pH-Responsive Doxorubicin-Releasing Micelles with Anticancer Activity

This study aimed to investigate the effect of in vivo pH-responsive doxorubicin (DOX) release and the targetability of pilot molecules in folic acid (FA)-modified micelles using a pharmacokinetic-pharmacodynamic (PK-PD) model. The time profiles of intratumoral DOX concentrations in Walker256 tumor-bearing rats were monitored using a microdialysis probe, followed by compartmental analysis, to evaluate intratumoral tissue pharmacokinetics. Maximal DOX was released from micelles 350 min after the administration of pH-responsive DOX-releasing micelles. However, FA modification of the micelles shortened the time to peak drug concentration to 150 min. Additionally, FA modification resulted in a 27-fold increase in the tumor inflow rate constant. Walker256 tumor-bearing rats were subsequently treated with DOX, pH-responsive DOX-releasing micelles, and pH-responsive DOX-releasing FA-modified micelles to monitor the tumor growth-time profiles. An intratumoral threshold concentration of DOX (55-64 ng/g tumor) was introduced into the drug efficacy compartment to construct a PD model, followed by PK-PD analysis of the tumor growth-time profiles. Similar results of threshold concentration and drug potency of DOX were obtained across all three formulations. Cell proliferation was delayed as the drug delivery ability of DOX was improved. The PK model, which was developed using the microdialysis method, revealed the intratumoral pH-responsive DOX distribution profiles. This facilitated the estimation of intratumoral PK parameters. The PD model with threshold concentrations contributed to the estimation of PD parameters in the three formulations, with consistent mechanisms observed. We believe that our PK-PD model can objectively assess the contributions of pH-responsive release ability and pilot molecule targetability to pharmacological effects.

Softness-Aided Mild Hyperthermia Boosts Stiff Nanomedicine by Regulating Tumor Mechanics

Aberrant tumor mechanical microenvironment (TMME), featured with overactivated cancer-associated fibroblasts (CAFs) and excessive extracellular matrix (ECM), severely restricts penetration and accumulation of cancer nanomedicines, while mild-hyperthermia photothermal therapy (mild-PTT) has been developed to modulate TMME. However, photothermal agents also encounter the barriers established by TMME, manifesting in limited penetration and heterogeneous distribution across tumor tissues and ending with attenuated efficiency in TMME regulation. Herein, it is leveraged indocyanine green (ICG)-loaded soft nanogels with outstanding deformability, for efficient tumor penetration and uniform distribution, in combination with mild-PTT to achieve potent TMME regulation by inhibiting CAFs and degrading ECM. As a result, doxorubicin (DOX)-loaded stiff nanogels gain greater benefits in tumor penetration and antitumor efficacy than soft counterparts from softness-mediated mild-PTT. This study reveals the crucial role of nanomedicine mechanical properties in tumor distribution and provides a novel strategy for overcoming the barriers of solid tumors with soft deformable nanogels.

"Yin-Yang philosophy" for the design of anticancer drug delivery nanoparticles

Understanding the in vivo transport process provides guidelines for designing ideal nanoparticles (NPs) with higher efficacy and fewer off-target effects. Many factors, such as particle size, morphology, surface potential, structural stability, and etc., may influence the delivering process of NPs due to the existence of various physiological barriers within the body. Herein, we summarise the distinct influences of NP physicochemical properties on the four consecutive in vivo transport steps: (1) navigating with bloodstream within blood vessels, (2) transport across vasculature walls into tumour tissues, (3) intratumoural transport through the interstitial space, and (4) cellular uptake & intracellular delivery by cancerous cells. We found that the philosophy behind the current consensus for NP design has certain similarities to the "Yin-Yang" theory in traditional Chinese culture. Almost all physicochemical properties, regardless of big or small sizes, long or short length, positive or negative zeta potentials, are double-edged swords. The balance of potential benefits and side effects, drug selectivity and accessibility should be fully considered when optimising particle design, similar to the "Yin-Yang harmony". This paper presents a comprehensive review of the advancements in NPs research, focusing on their distinct features in tumour targeting, drug delivery, and cell uptake. Additionally, it deliberates on future developmental trends and potential obstacles, thereby aiming to uncover the ways these characteristics influence the NPs' biological activity and provide theoretical guidance for the targeted delivery of NPs.

Mechanisms and Barriers in Nanomedicine: Progress in the Field and Future Directions

In recent years, steady progress has been made in synthesizing and characterizing engineered nanoparticles, resulting in several approved drugs and multiple promising candidates in clinical trials. Regulatory agencies such as the Food and Drug Administration and the European Medicines Agency released important guidance documents facilitating nanoparticle-based drug product development, particularly in the context of liposomes and lipid-based carriers. Even with the progress achieved, it is clear that many barriers must still be overcome to accelerate translation into the clinic. At the recent conference workshop "Mechanisms and Barriers in Nanomedicine" in May 2023 in Colorado, U.S.A., leading experts discussed the formulation, physiological, immunological, regulatory, clinical, and educational barriers. This position paper invites open, unrestricted, nonproprietary discussion among senior faculty, young investigators, and students to trigger ideas and concepts to move the field forward.

Sustained and Localized Drug Depot Release Using Radiation-Activated Scintillating Nanoparticles

Clinical treatment of cancer commonly incorporates X-ray radiation therapy (XRT), and developing spatially precise radiation-activatable drug delivery strategies may improve XRT efficacy while limiting off-target toxicities associated with systemically administered drugs. Nevertheless, achieving this has been challenging thus far because strategies typically rely on radical species with short lifespans, and the inherent nature of hypoxic and acidic tumor microenvironments may encourage spatially heterogeneous effects. It is hypothesized that the challenge could be bypassed by using scintillating nanoparticles that emit light upon X-ray absorption, locally forming therapeutic drug depots in tumor tissues. Thus a nanoparticle platform (Scintillating nanoparticle Drug Depot; SciDD) that enables the local release of cytotoxic payloads only after activation by XRT is developed, thereby limiting off-target toxicity. As a proof-of-principle, SciDD is used to deliver a microtubule-destabilizing payload MMAE (monomethyl auristatin E). With as little as a 2 Gy local irradiation to tumors, MMAE payloads are released effectively to kill tumor cells. XRT-mediated drug release is demonstrated in multiple mouse cancer models and showed efficacy over XRT alone (p < 0.0001). This work shows that SciDD can act as a local drug depot with spatiotemporally controlled release of cancer therapeutics.

Polymeric nanotheranostics for solid tumor management: Recent developments and global regulatory landscape

Polymeric nanotheranostics have emerged as promising vehicles for diagnosis‐cum‐targeted therapy in solid tumors, offering precise delivery of therapeutic agents at the site of solid tumors and minimizing systemic side effects. This article summarizes the latest developments in using polymeric nanoparticles for specific treatment strategies in solid tumors. It explores the various methods these nanoparticles utilize for targeted medication delivery. This includes passive targeting through the amplified permeability and retention effect, active targeting via interactions between ligands and receptors, and stimuli‐responsive release mechanisms such as pH, temperature, and enzymatic triggers. Furthermore, we highlight recent developments in stimuli‐responsive polymeric nanoparticles, which enable controlled drug release in response to specific cues in the tumor microenvironment, thus enhancing therapeutic efficacy. Also, we focus on the theranostic polymeric nanoparticles, which are used for diagnosing and treating solid tumors. We discuss critical regulatory considerations and the regulatory bodies of different countries that regulate nanomedicines' safety, efficacy, quality, and manufacturing processes. Overall, this review provides insights into the latest innovations in polymeric nanoparticles for targeted therapy in solid tumors, elucidating their mechanisms of action, stimuli‐responsive properties, and regulatory pathways, which collectively contribute to developing effective and safe nanomedicines for cancer treatment.

Nanomedicine Tumor Targeting

Nanomedicines are extensively explored for cancer therapy. By delivering drug molecules more efficiently to pathological sites and by attenuating their accumulation in healthy organs and tissues, nanomedicine formulations aim to improve the balance between drug efficacy and toxicity. More than 20 cancer nanomedicines are approved for clinical use, and hundreds of formulations are in (pre)clinical development. Over the years, several key pitfalls have been identified as bottlenecks in nanomedicine tumor targeting and translation. These go beyond materials- and production-related issues, and particularly also encompass biological barriers and pathophysiological heterogeneity. In this manuscript, the author describes the most important principles, progress, and products in nanomedicine tumor targeting, delineates key current problems and challenges, and discusses the most promising future prospects to create clinical impact.

On the uncertainty of the correlation between nanoparticle avidity and biodistribution

The specific delivery of a drug to its site of action also known as targeted drug delivery is a topic in the field of pharmaceutics studied for decades. One approach extensively investigated in this context is the use ligand functionalized nanoparticles. These particles are modified to carry receptor specific ligands, enabling them to accumulate at a desired target site. However, while this concept initially appears straightforward to implement, in-depth research has revealed several challenges hindering target site specific particle accumulation - some of which remain unresolved to this day. One of these challenges consists in the still incomplete understanding of how nanoparticles interact with biological systems. This knowledge gap significantly compromises the predictability of particle distribution in biological systems, which is critical for therapeutic efficacy. One of the most crucial steps in delivery is the attachment of nanoparticles to cells at the target site. This attachment occurs via the formation of multiple ligand receptor bonds. A process also referred to as multivalent interaction. While multivalency has been described extensively for individual molecules and macromolecules respectively, little is known on the multivalent binding of nanoparticles to cells. Here, we will specifically introduce the concept of avidity as a measure for favorable particle membrane interactions. Also, an overview about nanoparticle and membrane properties affecting avidity will be given. Thereafter, we provide a thorough review on literature investigating the correlation between nanoparticle avidity and success in targeted particle delivery. In particular, we want to analyze the currently uncertain data on the existence and nature of the correlation between particle avidity and biodistribution.

Application of Nanomaterial-Based Sonodynamic Therapy in Tumor Therapy

Sonodynamic therapy (SDT) has attracted significant attention in recent years as it is an innovative approach to tumor treatment. It involves the utilization of sound waves or ultrasound (US) to activate acoustic sensitizers, enabling targeted drug release for precise tumor treatment. This review aims to provide a comprehensive overview of SDT, encompassing its underlying principles and therapeutic mechanisms, the applications of nanomaterials, and potential synergies with combination therapies. The review begins by introducing the fundamental principle of SDT and delving into the intricate mechanisms through which it facilitates tumor treatment. A detailed analysis is presented, outlining how SDT effectively destroys tumor cells by modulating drug release mechanisms. Subsequently, this review explores the diverse range of nanomaterials utilized in SDT applications and highlights their specific contributions to enhancing treatment outcomes. Furthermore, the potential to combine SDT with other therapeutic modalities such as photothermal therapy (PTT) and chemotherapy is discussed. These combined approaches aim to synergistically improve therapeutic efficacy while mitigating side effects. In conclusion, SDT emerges as a promising frontier in tumor treatment that offers personalized and effective treatment options with the potential to revolutionize patient care. As research progresses, SDT is poised to play a pivotal role in shaping the future landscape of oncology by providing patients with a broader spectrum of efficacious and tailored treatment options.

In situ single-cell therapeutic response imaging facilitated by the TRIPODD fluorescence imaging platform

Purpose: Small molecule drugs such as tyrosine kinase inhibitors (TKIs) targeting tumoral molecular dependencies have become standard of care for numerous cancer types. Notably, epidermal growth factor receptor (EGFR) TKIs (e.g., erlotinib, afatinib, osimertinib) are the current first-line treatment for non-small cell lung cancer (NSCLC) due to their improved therapeutic outcomes for EGFR mutated and overexpressing disease over traditional platinum-based chemotherapy. However, many NSCLC tumors develop resistance to EGFR TKI therapy causing disease progression. Currently, the relationship between in situ drug target availability (DTA), local protein expression and therapeutic response cannot be accurately assessed using existing analytical tools despite being crucial to understanding the mechanism of therapeutic efficacy. Procedure: We have previously reported development of our fluorescence imaging platform termed TRIPODD (Therapeutic Response Imaging through Proteomic and Optical Drug Distribution) that is capable of simultaneous quantification of single-cell DTA and protein expression with preserved spatial context within a tumor. TRIPODD combines two complementary fluorescence imaging techniques: intracellular paired agent imaging (iPAI) to measure DTA and cyclic immunofluorescence (cyCIF), which utilizes oligonucleotide conjugated antibodies (Ab-oligos) for spatial proteomic expression profiling on tissue samples. Herein, TRIPODD was modified and optimized to provide a downstream analysis of therapeutic response through single-cell DTA and proteomic response imaging. Results: We successfully performed sequential imaging of iPAI and cyCIF resulting in high dimensional imaging and biomarker assessment to quantify single-cell DTA and local protein expression on erlotinib treated NSCLC models. Pharmacodynamic and pharmacokinetic studies of the erlotinib iPAI probes revealed that administration of 2.5 mg/kg each of the targeted and untargeted probe 4 h prior to tumor collection enabled calculation of DTA values with high Pearson correlation to EGFR, the erlotinib molecular target, expression in the tumors. Analysis of single-cell biomarker expression revealed that a single erlotinib dose was insufficient to enact a measurable decrease in the EGFR signaling cascade protein expression, where only the DTA metric detected the presence of bound erlotinib. Conclusion: We demonstrated the capability of TRIPODD to evaluate therapeutic response imaging to erlotinib treatment as it relates to signaling inhibition, DTA, proliferation, and apoptosis with preserved spatial context.

Harnessing Microbial Effectors for Macrophage-Mediated Drug Delivery

Macrophage-based drug delivery systems are promising, but their development is still in its infancy, with many limitations remaining to be addressed. Our aim was to design a system harnessing microbial effectors to facilitate controlled drug cargo expulsion from macrophages to enable the use of more toxic drugs without adding to the risk of off-target detrimental effects. The pore forming and actin polymerizing Listeria monocytogenes effectors listeriolysin-O (LLO) and actin assembly-inducing protein (ActA) were synthesized using a novel green fluorescent protein (GFP)-linked heterologous expression system. These effectors were coated onto polystyrene beads to generate "synthetic cargo" before loading into primary M1 macrophages. Bead uptake and release from macrophages were evaluated by using high-throughput quantitative imaging flow cytometry and confocal microscopy. In vitro results confirmed appropriate activity of synthesized effectors. Coating of these effector proteins onto polystyrene beads (simulated drug cargo) resulted in changes in cellular morphology, bead content, and intracellular bead localization, which may support an interpretation of the induced release of these beads from the cells. This forms the basis for further investigation to fully elucidate any potential release mechanisms. Bacterial effectors ActA and LLO successfully effectuated actin polarization and protrusions from cell membranes similar to those seen in cells infected with Listeria spp., illustrating the potential of using these effectors and production methods for the development of an endogenous drug delivery system capable of low-risk, targeted release of high potency drugs.

A quantitative MRI-based approach to estimate the permeation and retention of nanomedicines in tumors

Despite the potential of the enhanced permeability and retention (EPR) effect in tumor passive targeting, many nanotherapeutics have failed to produce meaningful clinical outcomes due to the variable and challenging nature of the tumor microenvironment (TME) and EPR effect. This EPR variability across tumors and inconsistent translation of nanomedicines from preclinical to clinical settings necessitates a reliable method to assess its presence in individual tumors. This study aimed to develop a reliable and non-invasive approach to estimate the EPR effect in tumors using a clinically compatible quantitative magnetic resonance imaging (qMRI) technique combined with a nano-sized MRI contrast agent. A quantitative MR imaging was developed using a dynamic contrast-enhanced (DCE) MRI protocol. Then, the permeability and retention of the nano-sized MRI contrast agent were evaluated in three different ovarian xenograft tumor models. Results showed significant differences in EPR effects among the tumor models, with tumor growth influencing the calculated parameters of permeability (Ktrans) and retention (Ve) based on Tofts pharmacokinetic (PK) modeling. Our data indicate that the developed quantitative DCE-MRI method, combined with the Tofts PK modeling, provides a robust and non-invasive approach to screen tumors for their responsiveness to nanotherapeutics. These results imply that the developed qMRI method can be beneficial for personalized cancer treatments by ensuring that nanotherapeutics are administered only to patients with tumors showing sufficient EPR levels.

Reductive prodrug and AIE copolymer nanoparticle for monitoring and chemotherapy

Polymeric micelle systems for drug delivery, monitor and chemotherapy have gained significant attention, and reductive polymeric micelle systems have become particularly attractive due to their controlled release behavior without additional assistance. However, there are challenges in accurately controlling drug and probe release from the nanoparticles and determining the loading content of drug and probe. To address these issues, we have developed a reduction-responsive Pt(IV) prodrug-based polymeric delivery system that can be dynamically monitored using aggregation-induced emission luminogens (AIE) based bioprobes. These polymeric micelle can self-assemble into nanoparticles and release both bio-active Pt(II) drug and bio-probe upon reduction activation. TPE molecules released in the inner endo/lysosomal microenvironment aggregate and fluoresce upon irradiation, thus allowing real-time tracking of drug biodistribution without additional contrast agents. Advantages of this system include position-specific chemical bond cleavage, control of platinum content, and monitoring of drug reduction and biodistribution.

"One-Pot" Method Preparation of Dendritic Mesoporous Silica-Loaded Matrine Nanopesticide for Noninvasive Administration Control of Monochamus alternatus: The Vector Insect of Bursapherenchus xylophophilus

Monochamus alternatus is an important stem-boring pest in forestry. However, the complex living environment of Monochamus alternatus creates a natural barrier to chemical control, resulting in a very limited control effect by traditional insecticidal pesticides. In this study, a stable pesticide dendritic mesoporous silica-loaded matrine nanopesticide (MAT@DMSNs) was designed by encapsulating the plant-derived pesticide matrine (MAT) in dendritic mesoporous silica nanoparticles (DMSNs). The results showed that MAT@DMSNs, sustainable nanobiopesticides with high drug loading capacity (80%) were successfully constructed. The release efficiency of DMSNs at alkaline pH was slightly higher than that at acidic pH, and the cumulative release rate of MAT was about 60% within 25 days. In addition, the study on the toxicity mechanism of MAT@DMSNs showed MAT@DMSNs were more effective than MAT and MAT (0.3% aqueous solutions) in touch and stomach toxicity, which might be closely related to their good dispersibility and permeability. Furthermore, MAT@DMSNs are also involved in water transport in trees, which can further transport the plant-derived insecticides to the target site and improve its insecticidal effect. Meanwhile, in addition, the use of essential oil bark penetrants in combination with MAT@DMSNs effectively avoids the physical damage to pines caused by traditional trunk injections and the development of new pests and diseases induced by the traditional trunk injection method, which provides a new idea for the application of biopesticides in the control of stem-boring pests in forestry.

A landscape of recent advances in lipid nanoparticles and their translational potential for the treatment of solid tumors

Lipid nanoparticles (LNPs) are biocompatible drug delivery systems that have found numerous applications in medicine. Their versatile nature enables the encapsulation and targeting of various types of medically relevant molecular cargo, including oligonucleotides, proteins, and small molecules for the treatment of diseases, such as cancer. Cancers that form solid tumors are particularly relevant for LNP-based therapeutics due to the enhanced permeation and retention effect that allows nanoparticles to accumulate within the tumor tissue. Additionally, LNPs can be formulated for both locoregional and systemic delivery depending on the tumor type and stage. To date, LNPs have been used extensively in the clinic to reduce systemic toxicity and improve outcomes in cancer patients by encapsulating chemotherapeutic drugs. Next-generation lipid nanoparticles are currently being developed to expand their use in gene therapy and immunotherapy, as well as to enable the co-encapsulation of multiple drugs in a single system. Other developments include the design of targeted LNPs to specific cells and tissues, and triggerable release systems to control cargo delivery at the tumor site. This review paper highlights recent developments in LNP drug delivery formulations and focuses on the treatment of solid tumors, while also discussing some of their current translational limitations and potential opportunities in the field.

Macrophage-derived biomimetic nanoparticles enhanced SDT combined with immunotherapy inhibited tumor growth and metastasis

Combination therapy based on sonodynamic therapy (SDT) combined with immune checkpoint blockers anti-PD-L1 provides effective anti-tumor effects. We designed a combination therapy based on M1/PLGA@IR780/CAT NPs of SDT-enhanced immunity combined with immune checkpoint blockers against PD-L1, which was based on M1 macrophage membrane-encapsulated poly (lactic-co-glycolic acid) (PLGA) nanoparticles loaded with the acoustic sensitizer IR780 and catalase (CAT) to successfully realize it. SDT based on M1/PLGA@IR780/CAT NPs could induce tumor cell death by promoting dendritic cell (DC) maturation and modulating the tumor immune microenvironment. In particular, the systemic anti-tumor immune response and potent immune memory induced upon combination with anti-PD-L1 checkpoint blockade not only alleviated the progression of mammary cancer in 4T1 mice and effectively blocked distant metastasis, but also prevented tumor recurrence, providing a promising new therapeutic strategy for clinical tumor therapy.

Tailoring the surface charges of iron-crosslinked dextran nanogels towards improved tumor-associated macrophage targeting

Tumor-associated macrophages (TAMs) have emerged as therapeutic interests in cancer nanomedicine because TAMs play a pivotal role in the immune microenvironment of solid tumors. Dextran and its derived nanocarriers are among the most promising nanomaterials for TAM targeting due to their intrinsic affinities towards macrophages. Various dextran-based nanomaterials have been developed to image TAMs. However, the effects of physiochemical properties especially for surface charges of dextran nanomaterials on TAM-targeting efficacy were ambiguous in literature. To figure out the surface charge effects on TAM targeting, here we developed a facile non-covalent self-assembly strategy to construct oppositely charged dextran nanogels (NGs) utilizing the coordination interaction of ferric ions, chlorine e6 (Ce6) dye and three dextran derivatives, diethylaminoethyl-, sulfate sodium- and carboxymethyl-dextran. The acquired dextran NGs exhibit different charges but similar hydrodynamic size, Ce6 loading and mechanical stiffness, which enables a side-by-side comparison of the effects of NG surface charges on TAM targeting monitored by the Ce6 fluorescence imaging. Compared with negative NGs, the positive NG clearly displays a superior TAM targeting in murine breast cancer model. This study identifies that positively charged dextran NG could be a promising approach to better engineer nanomedicine towards an improved TAM targeting.

Applying artificial intelligence and computational modeling to nanomedicine

Achieving specific and targeted delivery of nanomedicines to diseased tissues is a major challenge. This is because the process of designing, formulating, testing, and selecting a nanoparticle delivery vehicle for a specific disease target is governed by complex multivariate interactions. Computational modeling and artificial intelligence are well-suited for analyzing and modeling large multivariate datasets in short periods of time. Computational approaches can be applied to help design nanomedicine formulations, interpret nanoparticle-biological interactions, and create models from high-throughput screening techniques to improve the selection of the ideal nanoparticle carrier. In the future, many steps in the nanomedicine development process will be done computationally, reducing the number of experiments and time needed to select the ideal nanomedicine formulation.

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.

Advanced optical imaging for the rational design of nanomedicines

Despite the enormous potential of nanomedicines to shape the future of medicine, their clinical translation remains suboptimal. Translational challenges are present in every step of the development pipeline, from a lack of understanding of patient heterogeneity to insufficient insights on nanoparticle properties and their impact on material-cell interactions. Here, we discuss how the adoption of advanced optical microscopy techniques, such as super-resolution optical microscopies, correlative techniques, and high-content modalities, could aid the rational design of nanocarriers, by characterizing the cell, the nanomaterial, and their interaction with unprecedented spatial and/or temporal detail. In this nanomedicine arena, we will discuss how the implementation of these techniques, with their versatility and specificity, can yield high volumes of multi-parametric data; and how machine learning can aid the rapid advances in microscopy: from image acquisition to data interpretation.

The spatiotemporal journey of nanomedicines in solid tumors on their therapeutic efficacy

The rapid development of nanomedicines is revolutionizing the landscape of cancer treatment, while effectively delivering them into solid tumors remains a formidable challenge. Currently, there is a huge disconnect on therapeutic response between regulatory approved nanomedicines and laboratory reported nanoparticles. The discrepancy is mainly resulted from the failure of using the classic overall pharmacokinetics behaviors of nanomedicines in tumors to predict the antitumor efficacy. Increasing evidence has revealed that the therapeutic efficacy predominantly relies on the intratumoral spatiotemporal distribution of nanomedicines. This review focuses on the spatiotemporal distribution of systemically administered chemotherapeutic nanomedicines in solid tumor. Firstly, the intratumoral biological barriers that regulate the spatiotemporal distribution of nanomedicines are described in detail. Next, the influences on antitumor efficacy caused by the spatial distribution and temporal drug release of nanomedicines are emphatically analyzed. Then, current methodologies for evaluating the spatiotemporal distribution of nanomedicines are summarized. Finally, the advanced strategies to positively modulate the spatiotemporal distribution of nanomedicines for an optimal tumor therapy are comprehensively reviewed.

Novel Pt(IV) prodrug self-assembled nanoparticles with enhanced blood circulation stability and improved antitumor capacity of oxaliplatin for cancer therapy

Pt(IV) compounds are regarded as prodrugs of active Pt(II) drugs (i.e. cisplatin, carboplatin, and oxaliplatin) and burgeoned as the most ideal candidates to substitute Pt(II) anticancer drugs with severe side effects. Nanoparticle drug delivery systems have been widely introduced to deliver Pt(IV) prodrugs more effectively and safely to tumors, but clinical outcomes were unpredictable owing to limited in vivo pharmacokinetics understanding. Herein, a novel Pt(IV) prodrug of oxaliplatin(OXA) was synthesized and prepared as self-assembled micellar nanoparticles(PEG-OXA NPs). In vitro, PEG-OXA NPs rapidly released biologically active OXA within 5 min in tumor cells while remaining extremely stable in whole blood or plasma. Importantly, the pharmacokinetic results showed that the AUC_0-∞, and t_1/2 values of PEG-OXA NPs were 1994 ± 117 h·µg/mL and 3.28 ± 0.28 h, respectively, which were much higher than that of free OXA solution (2.03 ± 0.55 h·µg/mL and 0.16 ± 0.07 h), indicating the longer drug circulation of PEG-OXA NPs in vivo. The altered pharmacokinetic behavior of PEG-OXA NPs remarkably contributed to improve antitumor efficacy, decrease systemic toxicity and increase tumor growth inhibition compared to free OXA. These findings establish that PEG-OXA NPs have the potential to offer a desirable self-delivery platform of platinum drugs for anticancer therapeutics.

FF-10850, a Novel Liposomal Topotecan Achieves Superior Antitumor Activity via Macrophage- and Ammonia-Mediated Payload Release in the Tumor Microenvironment

Topotecan, an approved treatment for refractory or recurrent ovarian cancer, has clinical limitations such as rapid clearance and hematologic toxicity. To overcome these limitations and maximize clinical benefit, we designed FF-10850, a dihydrosphingomyelin-based liposomal topotecan. FF-10850 demonstrated superior antitumor activity to topotecan in ovarian cancer cell line-based xenograft models, as well as in a clinically relevant DF181 platinum-refractory ovarian cancer patient-derived xenograft model. The safety profile was also improved with mitigation of hematologic toxicity. The improved antitumor activity and safety profile are achieved via its preferential accumulation and payload release triggered in the tumor microenvironment. Our data indicate that tumor-associated macrophages internalize FF-10850, resulting in complete payload release. The release mechanism also appears to be mediated by high ammonia concentration resulting from glutaminolysis, which is activated by tumor metabolic reprogramming. In ammonia-rich conditions, FF-10850 released payload more rapidly and to a greater extent than liposomal doxorubicin, a currently approved treatment for ovarian cancer. FF-10850 significantly enhanced antitumor activity in combination with carboplatin or PARP inhibitor without detrimental effects on body weight in murine xenograft models, and demonstrated synergistic antitumor activity combined with anti-PD-1 antibody with the development of tumor antigen-specific immunity. These results support phase I investigation of FF-10850 for the treatment of solid tumors including ovarian cancer (NCT04047251), and further evaluation in combination settings.

Precise delivery of celastrol by PEGylated aptamer dendrimer nanoconjugates for enormous therapeutic effect via superior intratumor penetration over antibody counterparts

Antibody-coated nanoparticles have been reported to have the extremely low delivery efficiency in solid tumors in preclinical trials. Though aptamers were considered to be superior over antibodies in cancer theranostics, whether PEGylated aptamer nanoparticles are better than antibody nanoparticles in improving delivery specificity and penetration efficiency of chemotherapeutics is still unknown. Here, we conjugate celastrol, a natural product with anti-tumor effect, onto PEGylated EpCAM aptamer or antibody dendrimers to obtain two nanoconjugates, and for the first time, conduct a comprehensive study to compare their performance in delivery specificity, intratumoral penetration ability and therapeutic outcomes. Our results showed that compared to antibody counterparts, PEGylated aptamer nanoconjugates exhibited the enhanced accumulation and retention specificities at tumor sites and the stronger intratumoral penetration capabilities by reducing the macrophage reservoir effects in solid tumors. When delivered celastrol to a colorectal xenograft tumor mice model by PEGylated aptamer dendrimers, 20 % of enhanced therapeutic efficiency was achieved compared to that by antibody-modified ones. Moreover, celastrol at 2 mg/kg delivered by PEGylated aptamer dendrimers showed the prominent anticancer efficiency (nearly 92 %) but without obvious side effects. These data firstly provide the proof-of-concept implementation that PEGylated aptamer nanoconjugates will display the great potential in the effective and safe cancer treatment with regard to the superiority over antibody ones in penetration abilities.

Macrophage-Based Microrobots for Anticancer Therapy: Recent Progress and Future Perspectives

Macrophages, which are part of the mononuclear phagocytic system, possess sensory receptors that enable them to target cancer cells. In addition, they are able to engulf large amounts of particles through phagocytosis, suggesting a potential "Trojan horse" drug delivery approach to tumors by facilitating the engulfment of drug-hidden particles by macrophages. Recent research has focused on the development of macrophage-based microrobots for anticancer therapy, showing promising results and potential for clinical applications. In this review, we summarize the recent development of macrophage-based microrobot research for anticancer therapy. First, we discuss the types of macrophage cells used in the development of these microrobots, the common payloads they carry, and various targeting strategies utilized to guide the microrobots to cancer sites, such as biological, chemical, acoustic, and magnetic actuations. Subsequently, we analyze the applications of these microrobots in different cancer treatment modalities, including photothermal therapy, chemotherapy, immunotherapy, and various synergistic combination therapies. Finally, we present future outlooks for the development of macrophage-based microrobots.

Charting a killer course to the solid tumor: strategies to recruit and activate NK cells in the tumor microenvironment

The ability to expand and activate natural Killer (NK) cells ex vivo has dramatically changed the landscape in the development of novel adoptive cell therapies for treating cancer over the last decade. NK cells have become a key player for cancer immunotherapy due to their innate ability to kill malignant cells while not harming healthy cells, allowing their potential use as an "off-the-shelf" product. Furthermore, recent advancements in NK cell genetic engineering methods have enabled the efficient generation of chimeric antigen receptor (CAR)-expressing NK cells that can exert both CAR-dependent and antigen-independent killing. Clinically, CAR-NK cells have shown promising efficacy and safety for treating CD19-expressing hematologic malignancies. While the number of pre-clinical studies using CAR-NK cells continues to expand, it is evident that solid tumors pose a unique challenge to NK cell-based adoptive cell therapies. Major barriers for efficacy include low NK cell trafficking and infiltration into solid tumor sites, low persistence, and immunosuppression by the harsh solid tumor microenvironment (TME). In this review we discuss the barriers posed by the solid tumor that prevent immune cell trafficking and NK cell effector functions. We then discuss promising strategies to enhance NK cell infiltration into solid tumor sites and activation within the TME. This includes NK cell-intrinsic and -extrinsic mechanisms such as NK cell engineering to resist TME-mediated inhibition and use of tumor-targeted agents such as oncolytic viruses expressing chemoattracting and activating payloads. We then discuss opportunities and challenges for using combination therapies to extend NK cell therapies for the treatment of solid tumors.