Sequential responsive nano-PROTACs for precise intracellular delivery and enhanced degradation efficacy in colorectal cancer therapy

Advancements in delivery Systems for Proteolysis-Targeting Chimeras (PROTACs): Overcoming challenges and expanding biomedical applications

PROTAC (Proteolysis-Targeting Chimera), an emerging drug development strategy based on small molecule technology, has garnered widespread attention due to its high efficiency, broad applicability, low resistance, and dosage advantages. However, PROTAC molecules still exhibit certain limitations that require urgent resolution. Although significant progress has been made in designing PROTACs that target various disease-related proteins, research on drug delivery systems (DDS) for PROTACs remains relatively limited. This review aims to explore the critical role of delivery system design in addressing the inherent challenges associated with PROTAC molecules from a novel perspective. Beginning with five major challenges-insufficient targeting, poor pharmacokinetic properties, low cell permeability, limited accessibility, and the Hook effect-this article introduces formulation strategies to mitigate these deficiencies. It discusses potential solutions through targeted modifications, nano-delivery systems, intelligent response systems, and membrane biomimetic technologies, among others. Furthermore, it elucidates the mechanisms and principles underlying these approaches and analyzes the advantages of various delivery strategies. The insights provided in this review offer insights for designing delivery systems tailored to PROTACs with diverse characteristics for different disease applications.

Nanomaterials in the diagnosis and treatment of gastrointestinal tumors: New clinical choices and treatment strategies

Nanomaterials have emerged as a promising modality in the diagnosis and treatment of gastrointestinal (GI) tumors, offering significant advancements over conventional methods. In diagnostic applications, nanomaterials facilitate enhanced imaging techniques, including magnetic resonance imaging (MRI), computed tomography (CT), and fluorescence imaging, which provide improved resolution and more accurate detection of early-stage cancers. Nanoparticles (NPs), such as liposomes, dendrimers, and quantum dots, are increasingly employed for the targeted imaging of specific biomarkers associated with GI malignancies, thereby enhancing diagnostic sensitivity and specificity. Liposomes are primarily used for drug delivery due to their ability to encapsulate hydrophobic drugs, dendrimers are useful for both drug delivery and gene therapy due to their highly branched structure, and quantum dots are primarily used in imaging and diagnostics because of their fluorescent properties. We also discuss their respective advantages and limitations. In therapeutic contexts, nanomaterials play a pivotal role in the development of targeted drug delivery systems. These systems address the limitations of traditional chemotherapy by improving drug bioavailability, reducing systemic toxicity, and promoting selective accumulation at tumor sites via both passive and active targeting mechanisms. Nanomedicines, including NPs and nanocarriers, enable the precise delivery of chemotherapeutic agents, nucleic acid -based therapies, and immunomodulators directly to cancer cells, thereby optimizing therapeutic efficacy. Furthermore, nanotechnology offers the potential to modulate the tumor microenvironment (TME), a critical factor in overcoming challenges related to tumor resistance and metastasis. Despite these promising advancements, several challenges persist, including concerns regarding long-term toxicity, stability, and regulatory approval. Nonetheless, the integration of nanomaterials into clinical practice holds substantial potential for revolutionizing the management of GI cancers, paving the way for more precise, personalized, and effective therapeutic strategies.

Nano-formulations in disease therapy: designs, advances, challenges, and future directions

Nano-formulations, as an innovative drug delivery system, offer distinct advantages in enhancing drug administration methods, improving bioavailability, promoting biodegradability, and enabling targeted delivery. By exploiting the unique size advantages of nano-formulations, therapeutic agents, including drugs, genes, and proteins, can be precisely reorganized at the microscale level. This modification not only facilitates the precise release of these agents but also significantly enhances their efficacy while minimizing adverse effects, thereby creating novel opportunities for treatment of a wide range of diseases. In this review, we discuss recent advancements, challenges, and future perspectives in nano-formulations for therapeutic applications. For this aim, we firstly introduce the development, design, synthesis, and action mechanisms of nano-formulations. Then, we summarize their applications in disease diagnosis and treatment, especially in fields of oncology, pulmonology, cardiology, endocrinology, dermatology, and ophthalmology. Furthermore, we address the challenges associated with the medical applications of nanomaterials, and provide an outlook on future directions based on these considerations. This review offers a comprehensive examination of the current applications and potential significance of nano-formulations in disease diagnosis and treatment, thereby contributing to the advancement of modern medical therapies.

A TCR nanovesicle antibody for redirecting T cells and reversing immunosuppression as a tumor immunotherapy strategy

T-cell receptor T-cell engagers (TCR-TCE) are soluble bispecific proteins composed of TCR and anti-CD3 antibodies, which can effectively redirect tumor-infiltrating T cells to kill tumor cells. However, TCR-TCE development and clinical application are significantly hindered by the instability of natural TCRs and immunosuppressive tumor microenvironment, underscoring the urgent need for alternative engineering strategies. Here, we describe a strategy that utilizes artificial cell membrane nanoparticle technology to generate a TCR nanovesicle antibody (TPC NV), which presents tumor-specific TCR, anti-CD3, and PD-1 antibodies on its membrane, representing a novel TCR-TCE with therapeutic efficacy against solid tumors. TPC NV binds to tumor cells through TCR, redirects tumor-infiltrating T cells via anti-CD3 antibodies, and reverses immunosuppression with anti-PD-1 antibodies, thereby inducing a broad-spectrum T cell response that effectively eliminates established tumors. Furthermore, epacadostat, an inhibitor of indoleamine 2,3-dioxygenase, can be loaded into TPC NV to suppress regulatory T cell (Treg) generation and enhance dendritic cell (DC) maturation by inhibiting tumor tryptophan metabolism. This dual action amplifies adaptive immune activation and triggers a robust systemic anti-tumor immune response.

Proteolysis targeting chimeras (PROTACs) in oncology: a review of patents and regulatory considerations

INTRODUCTION

Proteolysis Targeting Chimeras (PROTACs) represents a groundbreaking advancement in drug discovery and targeted protein degradation. Unlike traditional small-molecule inhibitors, PROTACs leverage the cell's natural protein degradation machinery to selectively degrade pathogenic proteins, offering significant therapeutic potential for previously undruggable targets and complex diseases such as cancer and neurodegenerative disorders. Understanding the regulatory landscape governing their approval is crucial as their development accelerates.

AREAS COVERED

This review provides an overview of recent patents, regulatory considerations, emerging concerns, and future perspectives of PROTACs in cancer management.

EXPERT OPINION

From a regulatory perspective, PROTACs present unique challenges and opportunities. Their dual-functional nature requires a nuanced approach to classification and approval, blending small-molecule and biologic regulatory frameworks. Specific guidelines addressing pharmacokinetic and pharmacodynamic profiles are needed. Comprehensive preclinical evaluation and robust clinical trial designs are essential to manage off-target effects and immunogenic responses. The collaboration between regulatory bodies, academia, and industry is crucial for establishing a clear pathway for PROTAC approval. Future considerations must account for advancements in PROTAC technology to ensure safe and effective therapies reach patients. While PROTACs hold immense promise, their regulatory journey requires tailored guidelines and rigorous evaluation to realize their full potential.

A Self-Assembling LYTAC Mediates CTGF Degradation and Remodels Inflammatory Tumor Microenvironment for Triple-Negative Breast Cancer Therapy

As a multifunctional extracellular protein, connective tissue growth factor (CTGF/CCN2) is significantly associated with the progression and prognosis of triple-negative breast cancer (TNBC). However, current blockade therapies targeting CTGF's multiple domains are limited, creating substantial challenges in treatment. Lysosome-targeting chimeras (LYTACs) have emerged as a promising approach for achieving complete protein degradation and inhibiting CTGF's various bioactivities. In this study, a self-assembling LYTAC nanoplatform, NanoCLY, designed to tumor microenvironment (TME)-responsively degrade CTGF is presented. The complete degradation of CTGF downregulates the TGF-β signaling pathway and disrupts the CTGF-IL-6 cell crosstalk within the TME, which further inhibits the activation of inflammatory cancer-associated fibroblasts (CAFs) and alleviates the inflammatory TME. Notably, the anti-TNBC effect of LYTAC-based CTGF degradation therapy surpasses that of antibody-based blockade therapy in both in vitro and in vivo models. The findings provide a proof of concept for CTGF degradation in TNBC and introduce the first CTGF-LYTAC nanoplatform aimed at TME-directed therapy.

Mechanistic insights and therapeutic strategies for targeting autophagy in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is characterised by early metastasis and resistance to anti-cancer therapy, leading to an overall poor prognosis. Macroautophagy (hereinafter referred to as autophagy) is a conserved cellular homeostasis mechanism that degrades various cargoes (e.g., proteins, organelles, and pathogens) mainly playing a role in promoting survival under environmental stress. Autophagy is an essential defense mechanism against PDAC initiation, acting on multiple levels to maintain cellular and tissue homeostasis. However, autophagy is also intimately involved in the molecular mechanisms driving PDAC progression, facilitating the adaptation of cancer cells to the tumor microenvironment's harsh conditions. In this review, we examine the complex role of autophagy in PDAC and assess the potential of modulating autophagy as a therapeutic strategy. By reviewing current research and clinical trials, we seek to elucidate how targeting autophagy can disrupt PDAC tumor survival mechanisms, enhance the efficacy of existing treatments, and ultimately improve patient outcomes.

Tumor Microenvironment-Responsive Polymer Delivery Platforms for Cancer Therapy

Most chemotherapeutic and bioimaging agents struggle with inadequate bioavailability, primarily due to their limited biocompatibility and lack of specificity in targeting, leading to low or decreased anticancer efficacy and inaccurate imaging. To surmount these obstacles, the development of stimuli-responsive polymer delivery platforms, predominantly leveraging the tumor microenvironment (TME), has emerged as a promising strategy. Therapeutic and diagnostic agents can be released controllably at the tumor site by virtue of the bond cleavage or hydrophobic to hydrophilic transformation of TME-sensitive linkages in TME-responsive systems, thus augmenting cancer treatment and imaging precision, while simultaneously attenuating the damage to healthy tissues and false imaging signals caused by non-specific drug leakage. In this comprehensive review, we scrutinize recent studies of TME-responsive polymer delivery platforms, encompassing pH-, ROS-, GSH-, enzyme-, and hypoxia-responsive vectors, significantly from the perspective of their molecular design and responsive mechanism, and further summarizing their bio-application in drug delivery and diagnostic imaging. Moreover, this review encapsulates the critical challenges and offers an insightful perspective on the future prospects of TME-responsive polymer delivery platforms in terms of molecular and vector design.

Development of a nano-targeting chimera for the degradation of membrane and cytoplasmic proteins

Various targeted protein degradation (TPD) approaches have been developed to overcome the limitations of traditional drug in eliminating pathogenic proteins by exploiting either the proteasomal or lysosomal pathway. However, there is still a lack of design strategies for TPD that utilize two distinct pathways to achieve the degradation of membrane and cytoplasmic proteins. Here, we develop a Nano-Targeting Chimera (Nano-APTAC), which is engineered by covalently attaching the protein-targeting aptamer to graphene oxide (GO) via the amide linkage, to hijack the autophagy-lysosome and ubiquitin-proteasome systems for targeted degradation of membrane and cytoplasmic proteins respectively. In contrast, a mixture of GO and aptamers without covalent interaction has no effect on protein degradation. Furthermore, the in vivo experiments demonstrate the efficacy of Nano-APTACs in depleting targeted proteins and inhibiting tumor growth. The work provides a versatile programmability platform, employing two distinct degradation systems to facilitate personalized design for the degradation of proteins regardless of their localization on the membrane or cytoplasm, and offering potential therapeutic benefits. STATEMENT OF SIGNIFICANCE: GO and aptamers have been combined for various applications. However, the utilization of this combination in TPD remains unknown. In this study, we found that the Nano-APTAC platform, constructed by covalently linking GO-aptamer chimera (not a simple mixture), can utilize autophagy-lysosome system and ubiquitin-proteasome system to degrade membrane and cytoplasmic proteins, respectively. The types of aptamers significantly influence the intracellular behavior of the chimeras, resulting in distinct subcellular localization and guiding the chimera to select specific degradation systems for protein removal. The Nano-APTAC's mode of action extremely expands the range of targeted proteins, prevents overload in specific degradation systems caused by excessive usage, and provides an exceptional level of adaptability in meeting diverse treatment requirements.

Schisandrin B targets CDK4/6 to suppress proliferation and enhance radiosensitivity in nasopharyngeal carcinoma by inducing cell cycle arrest

Nasopharyngeal carcinoma (NPC) is notably prevalent in East and Southeast Asia, where despite advancements in radiotherapy leading to high control rates, challenges like radioresistance and collateral tissue damage remain significant. While Schisandrin B (SchB) has been demonstrated antitumor effects in various tumors, its efficacy in NPC remains unexplored. In this study, we explored the antitumor potential of Sch B on NPC, particularly its effects on cell proliferation and radiosensitivity. Our research demonstrates that Sch B effectively inhibits the proliferation of NPC cell lines HONE-1 and CNE-1 by inducing cell cycle G1 phase arrest, specifically through the down-regulation of cyclin-dependent kinase 4/6, without impacting the normal nasopharyngeal epithelial cell line NP69. This selective inhibitory effect positions Sch B as a targeted therapeutic agent, sparing healthy tissue from adverse effects. Furthermore, we observed that Sch B enhances the efficacy of radiotherapy in NPC cells by obstructing DNA double-strand break repair mechanisms, suggesting that a combined treatment regimen of Sch B and radiation could offer a superior therapeutic strategy. These findings propose Sch B not only as a potent inhibitor of NPC cell proliferation but also as an enhancer of radiosensitivity, providing a promising avenue for improving NPC treatment outcomes.

Constructing a Prognostic Model for Subtypes of Colorectal Cancer Based on Machine Learning and Immune Infiltration-Related Genes

This study constructed a prognostic model combining machine learning-based immune infiltration-related genes in each CRC subtype. We used publicly accessible gene expression data and clinical information on colorectal cancer patients. Integrated bioinformatics analysis was used for the identification of immune-wise genes. Machine learning algorithms, like LASSO regression and random forest, were utilised to identify the most important genes that may serve as predictors for patient prognosis. Univariate Cox regression, consensus clustering as well as machine learning algorithms were conducted to construct a prognostic risk scoring model. Analysis of functional enrichment, immune infiltration analyses and copy number variations as well as mutational burdens was performed and validated at the single-cell level. A machine learning-based model is designed with good predictive power-an area under the receiver operating characteristic curve (AUC-ROC) of C-index in cross-validation. The model also achieved good calibration and discrimination ability to stratify patients into high- and low-risk groups with a statistically significant difference in OS (p < 0.05). We have integrated multiple types of gene network features into machine learning systems based on the characteristics of integrating networks with Multi-Expense Learning algorithms, and we propose a robust approach for predicting CRC molecular subtype patient survival. This model could potentially steer personalised treatment strategies and ameliorate outcomes in patients. Although validation in other cohorts and clinical situations is necessary, it may be useful.

PROTACs coupled with oligonucleotides to tackle the undruggable

Undruggable targets account for roughly 85% of human disease-related targets and represent a category of therapeutic targets that are difficult to tackle with traditional methods, but their considerable clinical importance. These targets are generally defined by planar functional interfaces and the absence of efficient ligand-binding pockets, making them unattainable for conventional pharmaceutical strategies. The advent of oligonucleotide-based proteolysis-targeting chimeras (PROTACs) has instilled renewed optimism in addressing these challenges. These PROTACs facilitate the targeted degradation of undruggable entities, including transcription factors (TFs) and RNA-binding proteins (RBPs), via proteasome-dependent mechanisms, thereby presenting novel therapeutic approaches for diseases linked to these targets. This review offers an in-depth examination of recent progress in the integration of PROTAC technology with oligonucleotides to target traditionally undruggable proteins, emphasizing the design principles and mechanisms of action of these innovative PROTACs.

Bisphosphonate-mineralized nano-IFNγ suppresses residual tumor growth caused by incomplete radiofrequency ablation through metabolically remodeling tumor-associated macrophages

Rationale: Radiofrequency ablation (RFA), as a minimally invasive surgery strategy based on local thermal-killing effect, is widely used in the clinical treatment of multiple solid tumors. Nevertheless, RFA cannot achieve the complete elimination of tumor lesions with larger burden or proximity to blood vessels. Incomplete RFA (iRFA) has even been validated to promote residual tumor growth due to the suppressive tumor immune microenvironment (TIME). Therefore, exploring strategies to remodel TIME is a key issue for the development of RFA therapy. Methods: The negative effect of iRFA on colorectal cancer therapy was firstly investigated. Then a zoledronate-mineralized nanoparticle loaded with IFNγ (Nano-IFNγ/Zole) was designed and its tumor suppressive efficacy was evaluated. Finally, the metabolic reprogramming mechanism of Nano-IFNγ/Zole on tumor-associated macrophages (TAMs) was studied in detail. Results: We found iRFA dynamically altered TIME and promoted TAM differentiation from M1 to M2. Nano-IFNγ/Zole was fabricated to metabolically remodel TAMs. IFNγ in Nano-IFNγ/Zole concentrated in the ablation site to play a long-term remodeling role. Acting on mevalonate pathway, Nano-IFNγ/Zole was discovered to reduce lysosomal acidification and activate transcription factor TFEB by inhibiting isoprene modification of the Rab protein family. These mechanisms, in conjunction with IFNγ-activated JAK/STAT1 signaling, accelerated the reprogramming of TAMs from M2 to M1, and suppressed tumor recurrence after iRFA. Conclusions: This study elaborates the synergistic mechanism of zoledronate and IFNγ in Nano-IFNγ/Zole to reshape suppressive TIME caused by iRFA by remodeling TAMs, and highlights the important value of metabolically induced cellular reprogramming. Since both zoledronate and IFNγ have already been approved in clinics, this integrative nano-drug delivery system establishes an effective strategy with great translational promise to overcome the poor prognosis after clinically incomplete RFA.