PROTACs: past, present and future

Chemical dissection of selective myeloid leukemia-1 inhibitors: How they were found and evolved

Myeloid cell leukemia-1 (MCL-1), a key anti-apoptotic protein within the BCL-2 family, is essential in regulating cell survival, particularly in cancer, where its overexpression is often linked to therapeutic resistance. This review begins with an overview of BCL-2-mediated apoptosis, highlighting the pivotal role of MCL-1 in cellular homeostasis. We then focus on the structure and function of MCL-1, elucidating how its unique structural features contribute to its function and interaction with pro-apoptotic proteins. The core of this review is a detailed structural analysis of selective MCL-1 inhibitors, tracing their development from initial discovery to stepwise optimization. We explore various classes of inhibitors, including those with distinct core structures, covalent inhibitors that reversibly/irreversibly bind to MCL-1, and innovative approaches such as metal-based inhibitors and proteolysis-targeting chimeras (PROTACs). The structural evolution of these inhibitors is discussed, with particular emphasis on the modifications that have enhanced their selectivity, potency, and pharmacokinetic profiles. Additionally, we summarize the synergistic potential of MCL-1 inhibitors when used in combination with other therapeutic agents, emphasizing their role in overcoming drug resistance. The review concludes with a discussion of current challenges in MCL-1 modulation and future perspectives, proposing alternative strategies for targeting this critical protein for cancer therapy.

Nanomaterials exert biological effects by influencing the ubiquitin-proteasome system

The ubiquitin-proteasome system (UPS) is an important type of protein post-translational modification that affects the quantity and quality of various proteins and influences cellular processes such as the cell cycle, transcription, oxidative stress, and autophagy. Nanomaterials (NMs), which exhibit excellent physicochemical properties, can directly interact with the UPS and act as molecular-targeted drugs to induce changes in biological processes. This review provides an overview of the influence of NMs on the UPS of misfolded proteins and key proteins, which are related to cancer, neurodegenerative diseases and oxidative stress. This review also summarizes the role of modification processes involved in ubiquitination the biological effects of NMs and the mechanism of such effects of NMs through regulation of the UPS. This review deepens our understanding of the influence of NMs on the protein degradation process and provides new potential therapeutic targets for disease.

Discovery of a highly potent, N-terminal domain-targeting degrader of AR-FL/AR-V7 for the treatment of prostate cancer

The clinical development of PROTACs targeting the androgen receptor (AR) for degradation has made significant progress. However, effective treatments for metastatic prostate cancers containing the androgen receptor splice variant 7 (AR-V7), a constitutively active mutant without the ligand-binding domain (LBD), are still lacking. Here, we reported the identification of a highly potent, noncovalent PROTAC targeting the N-terminal domain (NTD) of AR, NP18, which is developed from the covalent AR-NTD antagonist EPI-002, and effectively degrades both AR-FL and AR-V7 in 22Rv1 cells (DC50: 18 and 26 nM respectively). Mechanistically, NP18 interacts with the N-terminal domain (NTD) of both full-length AR (AR-FL) and splice variant 7 (AR-V7), leading to their selective and proteasomal degradation. Importantly, NP18 exhibited remarkably superior antitumor activity in both 22Rv1 xenograft and patient-derived xenograft (PDX) models than EPI-002. Taken together, these findings highlight NP18 as a promising candidate to counteract AR splice variant-driven resistance.

Co-delivery of PROTAC and siRNA via novel liposomes for the treatment of malignant tumors

Targeted elimination of damaged or overexpressed proteins within the tumor serves a pivotal role in regulating cellular function and restraining tumor cell growth. Researchers have been striving to identify safer and more effective methods for protein removal. Here, we propose the synergistic employment of a small molecule degrading agent (PROTAC) and siRNA to attain enhanced protein clearance efficiency and tumor therapeutic effects. Co-delivery liposomes were prepared to facilitate the efficient encapsulation of PROTAC and siRNA. Specifically, the cationic liposome significantly improved the solubility of the insoluble PROTAC (DT2216). The cationic polymer (F-PEI) achieved efficient encapsulation of the nucleic acid drug, thereby promoting endocytosis and enhancing the therapeutic impact of the drug. Both in vivo and in vitro experiments demonstrated remarkable degradation of target proteins and inhibition of tumor cells by the co-delivery system. In conclusion, the co-delivery liposomes furnished a nano-delivery system proficient in effectively encapsulating both hydrophilic and hydrophobic drugs, thereby presenting a novel strategy for targeted combination therapy in treating tumors.

A prospective therapeutic strategy: GPX4-targeted ferroptosis mediators

As a crucial regulator of oxidative homeostasis, seleno-protein glutathione peroxidase 4 (GPX4) represents the primary defense system against ferroptosis, making it a promising target with important clinical application prospects. From the discovery of covalent and allosteric sites in GPX4, substantial advancements in GPX4-targeted small molecules have been made through diverse discovery and design strategies in recent years. Moreover, as an emerging hotspot in drug development, seleno-organic compounds can functionally mimic GPX4 to reduce hydroperoxides. To facilitate the further development of selective ferroptosis mediators as potential pharmaceutical agents, this review comprehensively covers all GPX4-targeted small molecules, including inhibitors, degraders, and activators. In addition, seleno-organic compounds as GPX mimics are also included. We also provide perspectives regarding challenges and future research directions in this field.

Auto-RapTAC: A Versatile and Sustainable Platform for the Automated Rapid Synthesis and Evaluation of PROTAC

The tedious synthesis and limited throughput biological evaluation remain a great challenge for discovering new proteolysis targeting chimera (PROTAC). To rapidly identify potential PROTAC lead compounds, we report a platform named Auto-RapTAC. Based on the modular characteristic of the PROTAC molecule, a streamlined workflow that integrates lab automation with "click chemistry" joint building-block libraries was constructed. This facilitates the autonomous generation of a variety of PROTACs, each with distinct linkers and E3 ligase ligands, all stored in biocompatible solutions. The ready-for-screening (R4S) approach, when paired with fluorescence-based assays, enables the efficient assessment of the PROTAC degradation activity in a high-throughput manner. To further test the capability of the platform, we identify six new PROTACs that target CDK2, CDK12, and BCL6 within a mere 8-day time frame for each target. In all, this platform could find broad application not only in discovering new PROTACs but also in the rapid development of novel heterobifunctional modalities.

PROTACs in platelets: emerging antithrombotic strategies and future perspectives

PURPOSE OF REVIEW

Proteolysis-targeted chimeras (PROTACs) are heterobifunctional compounds that selectively target proteins for degradation and are an emerging therapeutic modality to treat diseases such as cancer and neurodegenerative disorders. This review will widen the area of application by highlighting the ability of PROTACs to remove proteins from the anucleate platelets and evaluate their antithrombotic potential.

RECENT FINDINGS

Proteomic and biochemical studies demonstrated that human platelets possess the Ubiquitin Proteasomal System as well as the E3 ligase cereblon (CRBN) and therefore may be susceptible to PROTAC-mediated protein degradation. Recent findings confirmed that CRBN ligand-based PROTACs targeting generic tyrosine kinases, Btk and/or Fak lead to efficacious and selective protein degradation in human platelets. Downregulation of Btk, a key player involved in signalling to thrombosis, but not haemostasis, resulted in impaired in-vitro thrombus formation.

SUMMARY

Platelets are susceptible to targeted protein degradation by CRBN ligand-based PROTACs and have limited ability to resynthesise proteins, ensuring long-term downregulation of target proteins. Therefore, PROTACs serve as an additional research tool to study platelet function and offer new therapeutic potential to prevent thrombosis. Future studies should focus on enhancing cell specificity to avoid on-target side effects on other blood cells.

IgE-FcεRI protein-protein interaction as a therapeutic target against allergic asthma: An updated review

In the last decade, research has clarified the binding interactions between immunoglobulin E (IgE) and its high-affinity receptor, the FcεRI alpha chain (FcεRI). The formation of the IgE-FcεRI complex is crucial in the context of atopic allergies, linking allergen recognition to cellular activation and disease manifestation. Consequently, pharmacological strategies that disrupt these interactions are vital for managing atopic conditions. Historically, the complexity of the IgE-FcεRI binding process and challenges in producing functional recombinant derivatives has complicated data interpretation. However, advancements in structural biology, protein engineering, and immunological studies have enhanced our understanding of these protein-protein interactions (PPI), facilitating the development of more effective therapies. The introduction of anti-IgE therapies underscores the significance of the IgE-FcεRI PPI in allergic asthma. IgE, that is present locally and systemically, serves as a sensory mechanism in the adaptive immune response, particularly in mast cells (MCs) and basophils. When bound to FcεRI, IgE enables rapid memory responses to allergens, but dysregulation can lead to severe allergic asthma. Thus, the reactivity of IgE sensors can be finely modulated using various IgE-associated molecules. This review explores the mechanisms underlying IgE-dependent MC activation and its regulation by these molecules, including the latest therapeutic candidates under investigation.

Development and Discovery of a Selective Degrader of Casein Kinases 1 δ/ε

Members of the casein kinase 1 (CK1) family have emerged as key regulators of cellular signaling and as potential drug targets. Functional annotation of the 7 human isoforms would benefit from isoform-selective inhibitors, allowing studies on the role of these enzymes in normal physiology and disease pathogenesis. However, due to significant sequence homology within the catalytic domain, isoform selectivity is difficult to achieve with conventional small molecules. Here, we used a PROTAC (Proteolysis TArgeting Chimeras) approach to develop a highly selective degrader AH078 (37) targeting CK1δ and CK1ε with excellent selectivity over the highly related CK1α isoform. The developed PROTAC, AH078 (37) selectively degraded CK1δ and CK1ε with a DC50 of 200 nM. Characterization of AH078 (37) revealed a VHL and Ubiquitin-dependent degradation mechanism. Thus, AH078 (37) represents a versatile chemical tool to study CK1δ and CK1ε function in cellular systems.

Recent advances in developing targeted protein degraders

Targeted protein degradation (TPD) represents a promising therapeutic approach, encompassing several innovative strategies, including but not limited to proteolysis targeting chimeras (PROTACs), molecular glues, hydrophobic tag tethering degraders (HyTTD), and lysosome-targeted chimeras (LYTACs). Central to TPD are small molecule ligands, which play a critical role in mediating the degradation of target proteins. This review summarizes the current landscape of small molecule ligands for TPD molecules. These small molecule ligands can utilize the proteasome, lysosome, autophagy, or hydrophobic-tagging system to achieve the degradation of target proteins. The article mainly focuses on introducing their design principles, application advantages, and potential limitations. A brief discussion on the development prospects and future directions of TPD technology was also provided.

Revolutionizing lung cancer treatment: Introducing PROTAC therapy as a novel paradigm in targeted therapeutics

This comprehensive review explores the transformative potential of PROTAC (Proteolysis-Targeting Chimeras) therapy as a groundbreaking approach in the landscape of lung cancer treatment. The introduction provides a succinct overview of current challenges in lung cancer treatment, emphasizing the significance of targeted therapies. Focusing on PROTAC therapy, the article elucidates its mechanism of action, comparing it with traditional targeted therapies and highlighting the key components and design principles of PROTAC molecules. In the context of lung cancer, the review meticulously summarizes preclinical evidence, emphasizing efficacy and specificity gleaned from studies evaluating PROTAC therapy. It delves into the implications of this preclinical data, discussing potential advantages over existing targeted therapies. An update on ongoing clinical trials involving PROTAC therapy for lung cancer offers a snapshot of the current progress, with a summary of key outcomes and advancements in early-phase trials. The mechanistic insights into PROTAC therapy's impact on lung cancer cells are explored, alongside a discussion on potential biomarkers for patient stratification and response prediction. The influence of tumor heterogeneity on PROTAC therapy outcomes is also addressed. Safety and tolerability assessments, encompassing preclinical and clinical studies, are comprehensively evaluated, including a comparative analysis with traditional targeted therapies and strategies to mitigate side effects. Looking forward, the article discusses the future perspectives of PROTAC therapy in lung cancer treatment and addresses ongoing challenges, providing a nuanced exploration of potential combination therapies and synergistic approaches. In conclusion, the review summarizes key findings and insights, underscoring the tremendous potential of PROTAC therapy as a promising and innovative avenue in pursuing more effective lung cancer treatments.

Discovery of a Novel Non-invasive AR PROTAC Degrader for the Topical Treatment of Androgenetic Alopecia

Elevated expression levels and enhanced activity of androgen receptor (AR) proteins are key factors in the development of androgenetic alopecia (AGA). AR proteolysis-targeting chimera (PROTAC) degraders have shown therapeutic potential, but their poor skin permeability requires invasive delivery methods. In this study, we conducted a structure feature analysis to investigate the effects of different linkers and E3 ligands of AR PROTACs on skin retention properties and degradation potency. Among these, compound C6 was discovered with excellent skin retention properties and nanomolar level AR degradation. By degrading AR, C6 regulated the expression levels of downstream paracrine factors associated with AGA. Additionally, after non-invasive topical application, C6 demonstrated excellent skin accumulation and achieved hair regeneration in an AGA mouse model. Overall, the development of non-invasive C6 offers a promising new strategy for AGA treatment and highlights the potential for using PROTACs in treating other skin diseases.

The Potential of PARP Inhibitors as Antitumor Drugs and the Perspective of Molecular Design

PARP (poly-ADP ribose polymerase) has received widespread attention in cancer treatment. Research has shown that PARP plays a crucial role in DNA damage repair and has become a popular target for drug design. Based on the mechanism of "synthetic lethality", multiple PARPis (PARP inhibitors) have been launched for the treatment of BRCA deficient tumors. For example, the approved PARPis have shown significant potential in cancer treatment, particularly in breast cancer and cancers associated with BRCA1/BRCA2 deficiencies. However, the clinical efficacy and safety of PARP inhibitors in different cancers remain issues that cannot be overlooked. The design of PARPis aims to eliminate their resistance and broaden their application scope. Designing selective PARP-1 inhibitors is also a potential strategy. PROTACs (Proteolysis Targeting Chimeras) to degrade PARP have become a potential novel cancer treatment strategy.

Modulating Phosphorylation by Proximity-Inducing Modalities for Cancer Therapy

Abnormal phosphorylation of proteins can lead to various diseases, particularly cancer. Therefore, the development of small molecules for precise regulation of protein phosphorylation holds great potential for drug design. While the traditional kinase/phosphatase small-molecule modulators have shown some success, achieving precise phosphorylation regulation has proven to be challenging. The emergence of heterobifunctional molecules, such as phosphorylation-inducing chimeric small molecules (PHICSs) and phosphatase recruiting chimeras (PHORCs), with proximity-inducing modalities is expected to lead to a breakthrough by specifically recruiting kinase or phosphatase to the protein of interest. Herein, we summarize the drug targets with aberrant phosphorylation in cancer and underscore the potential of correcting phosphorylation in cancer therapy. Through reported cases of heterobifunctional molecules targeting phosphorylation regulation, we highlight the current design strategies and features of these molecules. We also provide a systematic elaboration of the link between aberrantly phosphorylated targets and cancer as well as the existing challenges and future research directions for developing heterobifunctional molecular drugs for phosphorylation regulation.

Programmable Circular Multivalent Nanobody-Targeting Chimeras (mNbTACs) for Multireceptor-Mediated Protein Degradation and Targeted Drug Delivery

Multispecific therapeutics hold significant promise in drug delivery, protein degradation, and cell recruitment to address clinical issues of tumor heterogeneity, resistance, and immune evasion. However, their modular engineering remains challenging. We developed a targeted degradation platform, termed multivalent nanobody-targeting chimeras (mNbTACs), by encoding diverse nanobody codons on a circular template using DNA printing technology. The homo- or hetero- mNbTACs specifically recognized membrane targets in a multivalent manner and simultaneously recruited scavenger receptors to favor clathrin-/caveolae-dependent endocytosis and lysosomal degradation of multiple proteins with high efficiency and selectivity. We demonstrated that a bispecific doxorubicin-loaded mNbTAC, named Doxo-mvNbsPPH, passively accumulated at tumor sites, specifically interacted with PD-L1 and HER2 targets, and was rapidly transported into lysosome, inducing potent immunogenic cell death and alleviating immune checkpoint evasion. The synergistic boosting of innate and adaptive immunity promoted the infiltration and proliferation of CD8+ T cells in tumor microenvironment (an 11-fold increase) with high toxicity and low exhaustion, eventually enhancing antitumor efficacy. Our mNbTAC platform provides multispecific therapeutics with variable valences and programmed species, whereas it induces targeted protein degradation through multireceptor-mediated endocytosis and lysosomal degradation without the need for lysosome-targeting receptors, representing a general and modular tool to harness extracellular proteome for disease treatment.

Covalent Proximity Inducers

Molecules that are able to induce proximity between two proteins are finding ever increasing applications in chemical biology and drug discovery. The ability to introduce an electrophile and make such proximity inducers covalent can offer improved properties such as selectivity, potency, duration of action, and reduced molecular size. This concept has been heavily explored in the context of targeted degradation in particular for bivalent molecules, but recently, additional applications are reported in other contexts, as well as for monovalent molecular glues. This is a comprehensive review of reported covalent proximity inducers, aiming to identify common trends and current gaps in their discovery and application.

Design, synthesis and biological evaluation of novel TMPRSS2-PROTACs with florosubstituted 4-guanidino-N-phenylbenzamide derivative ligands

Transmembrane Serine Protease 2 (TMPRSS2) plays a critical role in tumorigenesis and progression, making its degradation a promising therapeutic strategy. In this study, we designed and synthesized TMPRSS2-PROTACs, including VPOT64 and VPOT76, based on camostat. Both compounds exhibited superior inhibitory effects on HT-29 colorectal and Calu-3 lung cancer cells compared to paclitaxel. Notably, VPOT76 effectively degraded TMPRSS2, significantly inhibiting the proliferation of TMPRSS2-positive HT-29 cells and inducing apoptosis with an IC50 of 0.39 ± 0.01 μM. Flow cytometry analysis demonstrated that VPOT76 increased early apoptotic cells in a dose-dependent manner and caused G2 phase arrest at 0.8 μM. Colony formation assays showed that VPOT76 inhibited HT-29 colony formation, even at low concentrations, further confirming its anti-proliferative effect. Additionally, wound healing assays indicated that VPOT76 reduced the migration of HT-29 cells after 48 h, suggesting its potential to impair tumor cell invasion and metastasis. These findings highlight the multifaceted anticancer activities of VPOT76, including apoptosis induction, cell cycle arrest, colony formation inhibition, and migration suppression. Overall, this study establishes VPOT76 as a potent TMPRSS2-degrading PROTAC with strong therapeutic potential, laying the groundwork for further development of TMPRSS2-targeting treatments for colorectal and other cancers.

Targeting oncogenic transcriptional factor c-myc by oligonucleotide PROTAC for the treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death, but effective therapeutic strategies are limited. Transcriptional factor c-Myc plays an oncogenic role in tumorigenesis and is an attractive target for HCC treatment. However, targeted therapy against c-Myc remains challenging. Herein, by conjugating VH032 with an optimized DNA sequence that recognized c-Myc complex, we discovered oligonucleotide-based proteolysis targeting chimeras (PROTACs), termed as MP-16 and MP-17, which effectively induced degradation of c-Myc. Mechanically, MP-16 or MP-17 directly interacted with c-Myc complex to form VHL/PROTAC/c-Myc ternary complex, and triggered c-Myc degradation by recruiting ubiquitin-proteasome system, suppressing cell proliferation of HCC cells. In mice model, MP-16 or MP-17 significantly inhibited HCC tumor growth and exhibited promising drug safety. This work provided novel oligonucleotide PROTACs that degraded c-Myc, giving a new lead structure for HCC therapy.

Targeted protein degradation of PDE4 shortforms by a novel proteolysis targeting chimera

Cyclic AMP (cAMP) has a crucial role in many vital cellular processes and there has been much effort expended in the discovery of inhibitors against the enzyme superfamily that degrades this second messenger, namely phosphodiesterases (PDEs). The journey of competitive PDE inhibitors to the clinic has been hampered by side effects profiles that have resulted from a lack of selectivity for subfamilies and individual isoforms because of high conservation of catalytic site sequences and structures. Here we introduce a proteolysis targeting chimera (PROTAC) that can specifically target a small subset of isoforms from the PDE4 family to send the enzyme for degradation at the proteasome by recruiting a ubiquitin E3 ligase into proximity with the PDE. We constructed our PDE4 PROTAC (KTX207) using a previously characterized PDE4 inhibitor, and we show that evolution of the compound into a PROTAC improves selectivity, potency and enables a long-lasting effect even after the compound is removed from cells after a short treatment duration. Functionally, KTX207 is more effective at increasing cAMP, is 100 times more anti-inflammatory, and is significantly better at reducing the growth in cancer cell models than the PDE4 inhibitor alone. Our study highlights the advantages of targeted degradation versus active-site occupancy for PDE4 inhibition and discusses the potential of this novel pharmacological approach to improve the safety profile of PDE4 inhibition in the future.

Modular Assembly of Heterotrifunctional Molecules Enabled by Iodosulfonylation of Allenes and Subsequent Amination

Beyond the rapid achievements of therapeutic heterobifunctional molecules, some recent efforts have focused on constructing heterotrifunctional molecules, aiming at developing more potent and selective therapeutic agents or emerging additional functions to heterobifunctional molecules. However, the synthesis of these complex molecules requires a specific design and lengthy steps. We have developed a two-step strategy for the modular construction of heterotrifunctional molecules, enabled by the sustainable and convenient iodosulfonylation of allenes followed by SN2'-selective amination. This strategy successfully incorporates a broad range of biologically active molecules, labeling them with a fluorescent group. The applications of the obtained compounds in selective protein labeling, subcellular imaging, and targeted inhibition of tumor cells make this strategy highly appealing.

Classifying covalent protein binders by their targeted binding site

Covalent protein targeting represents a powerful tool for protein characterization, identification, and activity modulation. The safety of covalent therapeutics was questioned for many years due to the possibility of off-target binding and subsequent potential toxicity. Researchers have recently, however, demonstrated many covalent binders as safe, potent, and long-acting therapeutics. Moreover, they have achieved selective targeting among proteins with high structural similarities, overcome mutation-induced resistance, and obtained higher potency compared to non-covalent binders. In this review, we highlight the different classes of binding sites on a target protein that could be addressed by a covalent binder. Upon folding, proteins generate various concavities available for covalent modifications. Selective targeting to a specific site is driven by differences in the geometry and physicochemical properties of the binding pocket residues as well as the geometry and reactivity of the covalent modifier "warhead". According to the warhead reactivity and the nature of the binding region, covalent binders can alter or lock a targeted protein conformation and inhibit or enhance its activity. We survey these various modification sites using case studies of recently discovered covalent binders, bringing to the fore the versatile application of covalent protein binders with respect to drug discovery approaches.

Exploring the Mechanisms, Biomarkers, and Therapeutic Targets of TRIM Family in Gastrointestinal Cancer

Gastrointestinal region (GI) cancers are closely linked to the ubiquitination system, with the E3 ubiquitin ligase playing a crucial role by targeting various substrates. As E3 ubiquitin ligases, proteins of tripartite motif (TRIM) family play a role in cancer signaling, development, apoptosis, and formation. These proteins regulate diverse biological activities and signaling pathways. This study comprehensively outlines the functions of TRIM proteins in gastrointestinal physiology, contributing to our knowledge of the molecular pathways involved in gastrointestinal tumors. Gastrointestinal region (GI) cancers are closely linked to the ubiquitination system, with the E3 ubiquitin ligase playing a crucial role by targeting various substrates.

Proteolysis Targeting Chimeras (PROTACs) in Breast Cancer Therapy

Breast cancer (BC) accounts for 30 % of cancer cases among women cancer patients globally, indicating the urgent need for the development of selective therapies targeting BCs. Recently, proteolysis-targeting chimera (PROTAC) has emerged as a promising strategy to target breast cancer. PROTAC is a chimeric molecule consisting of a target protein ligand, an E3 ligase ligand, and conjugating linkers, enabling it to facilitate the degradation of desired target proteins by recruiting E3 ligase in close proximity. Due to the catalytic behavior and direct degradation of BC-causing proteins, PROTAC could achieve high drug efficacy with low doses, drawing great attention for its potential as therapeutics. This review provides cases of the currently developed PROTACs targeting BCs depending on the type of BCs, limitations, and future perspectives of PROTAC in targeting BCs.

Development of natural product-based targeted protein degraders as anticancer agents

Targeted protein degradation (TPD) has emerged as a powerful approach for eliminating cancer-causing proteins through an "event-driven" pharmacological mode. Proteolysis-targeting chimeras (PROTACs), molecular glues (MGs), and hydrophobic tagging (HyTing) have evolved into three major classes of TPD technologies. Natural products (NPs) are a primary source of anticancer drugs and have played important roles in the development of TPD technology. NPs potentially expand the toolbox of TPD by providing a variety of E3 ligase ligands, protein of interest (POI) warheads, and hydrophobic tags (HyTs). As a promising direction in the TPD field, NP-based degraders have shown great potential for anticancer therapy. In this review, we summarize recent advances in the development of NP-based degraders (PROTACs, MGs and HyTing) with anticancer applications. Moreover, we put forward the challenges while presenting potential opportunities for the advancement of future targeted protein degraders derived from NPs.

Drugs from drugs: New chemical insights into a mature concept

Developing new drugs from marketed ones is a well-established and successful approach in drug discovery. We offer a unified view of this field, focusing on the new chemical aspects of the involved approaches: (a) chemical transformation of the original drugs (late-stage modifications, molecular editing), (b) prodrug strategies, and (c) repurposing as a tool to develop new hits/leads. Special focus is placed on the molecular structure of the drugs and their synthetic feasibility. The combination of experimental advances and new computational approaches, including artificial intelligence methods, paves the way for the evolution of the drugs from drugs concept.

Development of PROTACs using computational approaches

Proteolysis-targeting chimeras (PROTACs) are drugs designed to degrade target proteins via the ubiquitin-proteasome system. With the application of computational biology/chemistry technique in drug design, numerous computer-aided drug design and artificial intelligence (AI)-driven drug design (CADD/AIDD) methods have recently emerged to facilitate the development of PROTAC drugs. We systematically review the role of in silico tools in PROTAC drug design, emphasizing how computational software can model PROTAC action and structure, predict activity, and assist in molecule design. We also discuss current challenges in the rational design of PROTACs from an in silico perspective, such as deviations from small-molecule druggability and the limited availability of training data. We provide an overview of recent discoveries and emerging research in this field, and discuss their potential impact on PROTAC design strategies.

New drug discovery and development from natural products: Advances and strategies

Natural products (NPs) have a long history as sources for drug discovery, more than half of approved drugs are related to NPs, which also exhibit multifaceted advantages in the clinical treatment of complex diseases. However, bioactivity screening of NPs, target identification, and design optimization require continuously improved strategies, the complexity of drug mechanism of action and the limitations of technological strategies pose numerous challenges to the development of new drugs. This review begins with an overview of bioactivity- and target-based drug development patterns for NPs, advances in NP screening and derivatization, and the advantages and problems of major targets such as genes and proteins. Then, target-based drugs as well as identification and validation methods are further discussed to elucidate their mechanism of action. Subsequently, the current status and development trend of the application of traditional and emerging technologies in drug discovery and development of NPs are systematically described. Finally, the collaborative strategy of multi-technology integration and multi-disciplinary intersection is emphasized for the challenges faced in the identification, optimization, activity evaluation, and clinical application of NPs. It is hoped to provide a systematic overview and inspiration for exploring new drugs from natural resources in the future.

Enhancing therapeutic efficacy in homologous recombination-proficient pancreatic cancer via the combination of PARP1-PROTAC and a BRD4 inhibitor

Currently, poly (ADP-ribose) polymerase inhibitors (PARPi) have been approved by U.S. Food and Drug Administration for BRCA-mutated pancreatic cancer therapy. However, limited indications hinder their further application. Repression of bromodomain-containing protein 4 (BRD4) can block the homologous recombination (HR) repair pathway and has the potential to enhance the response to PARPi in HR-proficient pancreatic cancer therapy. In addition, proteolysis targeting chimeras (PROTACs) can hijack E3 ligase within the cell to ubiquitinate degradation-targeted proteins effectively and quickly, thus enhancing the therapeutic effect on tumors. In the present study, the LB23 compound, which induces PARP1 degradation, was employed in combination with the BRD4 inhibitor JQ1, confirming their synergistic effect in HR-proficient pancreatic cancer through various methods. Moreover, compared to the JQ1 and PARPi olaparib combination, PARP1-PROTAC and JQ1 had more notable synergistic effects. Further research into the synergistic mechanism demonstrated that combination therapy enhanced DNA damage and suppressed DNA repair by inducing cell cycle arrest and cell apoptosis. The present study therefore provides the experimental data for this type of combination therapy, which is expected to be an innovative approach for the treatment of HR-proficient pancreatic cancer.

Discovery of novel 20S proteasome subunit β5 PROTAC degraders as potential therapeutics for pharyngeal carcinoma and Bortezomib-resistant multiple myeloma

Resistance to proteasome inhibitors like Bortezomib is a major challenge in the treatment of multiple myeloma (MM). Proteolysis targeting chimeras (PROTACs), an emerging therapeutic approach that induces selective degradation of target proteins, offer a promising solution to overcome drug resistance. In this study, we designed and synthesized novel small-molecule PROTACs that induce 20S proteasome subunit β5 degradation as a strategy to overcome Bortezomib resistance. These 20S proteasome subunit β5 PROTACs demonstrated considerable binding affinity to 20S proteasome subunit β5 and cereblon (CRBN), effectively induced 20S proteasome subunit β5 degradation, and exhibited potent antiproliferative activity against a panel of cancer cell lines. Notably, PROTACs 12f and 14 displayed robust antitumor effects against both the pharyngeal carcinoma cell line FaDu and the Bortezomib-resistant MM cell line KM3/BTZ in vitro and in vivo with excellent safety profiles. Taken together, our findings highlight the potential of PROTACs 12f and 14 as novel 20S proteasome subunit β5-degrading agents for the treatment of pharyngeal carcinoma and overcoming Bortezomib resistance in MM.

Advances in designing ternary complexes: Integrating in-silico and biochemical methods for PROTAC optimisation in target protein degradation

Target protein degradation (TPD) is an emerging approach to mitigate disease-causing proteins. TPD contains several strategies, and one of the strategies that gained immersive importance in recent times is Proteolysis Targeting Chimeras (PROTACs); the PROTACs recruit small molecules to induce the poly-ubiquitination of disease-causing protein by hijacking the ubiquitin-proteasome system (UPS) by bringing the E3 ligase and protein of interest (POI) into appropriate proximity. The steps involved in designing and evaluating the PROTACs remain critical in optimising the PROTACs to degrade the POI. It is observed that using in-silico and biochemical methods to study the ternary complexes (TCs) of the POI-PROTAC-E3 ligase is essential to understanding the structural activity, cooperativity, and stability of formed TCs. A better understanding of the above-mentioned leads to an appropriate rationale for designing the PROTACs targeting the disease-causing proteins. In this review, we tried to summarise the approaches used to design the ternary complexes, i.e., in-silico and in-vitro methods, to understand the behaviour of the PROTAC-induced ternary complexes.

Targeting PRMT5 through PROTAC for the treatment of triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is currently the most aggressive subtype of breast cancer, characterized by high heterogeneity and strong invasiveness, and currently lacks effective therapies. PRMT5, a type II protein arginine methyltransferase, is upregulated in numerous cancers, including TNBC, and plays a critical role, marked it as an attractive therapeutic target. PROTAC (Proteolysis Targeting Chimeras) is an innovative drug development technology that utilizes the ubiquitin-proteasome system (UPS) to degrade target proteins, which is characterized by higher activity, enhanced safety, lower resistance, and reduced toxicity, offering significant value for clinical translation.

METHODS

This study utilizes the PROTAC technology to develop potential degraders targeting PRMT5 in vitro and in vivo.

RESULTS

Through the design, synthesis and screening of a series of targeted compounds, we identified YZ-836P as an effective compound that exerted cytotoxic effects and reduced the protein levels of PRMT5 and its key downstream target protein KLF5 in TNBC after 48 h. Its efficacy was significantly superior to the PRMT5 PROTAC degraders that had been reported. YZ-836P induced G1 phase cell cycle arrest and significantly induced apoptosis in TNBC cells. Additionally, we demonstrated that YZ-836P promoted the ubiquitination and degradation of PRMT5 in a cereblon (CRBN)-dependent manner. Notably, YZ-836P exhibited pronounced efficacy in inhibiting the growth of TNBC patient-derived organoids and xenografts in nude mice.

CONCLUSIONS

These findings position YZ-836P as a promising candidate for advancing treatment modalities for TNBC.

TRIAL REGISTRATION

Ethics Committee of Yunnan Cancer Hospital, KYCS2023-078. Registered 7 June 2023.

Protacs in cancer therapy: mechanisms, design, clinical trials, and future directions

Cancer develops as a result of changes in both genetic and epigenetic mechanisms, which lead to the activation of oncogenes and the suppression of tumor suppressor genes. Despite advancements in cancer treatments, the primary approach still involves a combination of chemotherapy, radiotherapy, and surgery, typically providing a median survival of approximately five years for patients. Unfortunately, these therapeutic interventions often bring about substantial side effects and toxicities, significantly impacting the overall quality of life for individuals undergoing treatment. Therefore, urgent need of research required which comes up with effective treatment of cancer. This review explores the transformative role of Proteolysis-Targeting Chimeras (PROTACs) in cancer therapy. PROTACs, an innovative drug development strategy, utilize the cell's protein degradation machinery to selectively eliminate disease-causing proteins. The review covers the historical background, mechanism of action, design, and structure of PROTACs, emphasizing their precision in targeting oncogenic proteins. The discussion extends to the challenges, nanotechnology applications, and ongoing clinical trials, showcasing promising results and clinical progress. The review concludes with insights into patents, future directions, and the potential impact of PROTACs in addressing dysregulated protein expression across various diseases. Overall, it provides a concise yet comprehensive overview for researchers, clinicians, and industry professionals involved in developing targeted therapies.

MMP-2-triggered, mitochondria-targeted PROTAC-PDT therapy of breast cancer and brain metastases inhibition

Proteolytic targeting chimera (PROTAC) technology is a protein-blocking technique and induces antitumor effects, with potential advantages. However, its effect is limited by insufficient distribution and accumulation in tumors. Herein, a transformable nanomedicine (dBET6@CFMPD) with mitochondrial targeting capacity is designed and constructed to combine PROTAC with photodynamic therapy (PDT). In this work, we demonstrate that dBET6@CFMPD exhibits great biodistribution and retention, and can induce potent antitumor response to suppress primary and metastatic tumors, becoming a nanomedicine with potential in cancer combination therapy.

Design and optimization strategies of PROTACs and its Application, Comparisons to other targeted protein degradation for multiple oncology therapies

Recent years have witnessed notable breakthroughs in the field of biotherapeutics. Proteolysis Targeting Chimeras (PROTACs) are novel molecules which used to degrade particular proteins despite the blockage by small drug molecules, which leads to a predicted therapeutic activity. This is a unique finding, especially at the cellular level targets degradations. Clinical trials and studies on PROTACs are in progress for oncology indications for demonstration of high potency and activity. PROTAC molecules are having excellent tissue distribution properties and their capacity to mutate the proteins and target overexpressed. This concept has attained wide attention from modern researchers in oncological drug discovery with particular physical qualities not offered by other therapeutic approaches. The modular nature of the PROTACs enables their methodical optimization and logical design. A thorough review was conducted in order to delve deeper into the subject and gain a better understanding of its development, computational supports, important factors for the optimization of developed PROTAC candidates, pharmacokinetic and pharmacodynamic (PK-PD) aspects, safety risks such as the degradation of undesired proteins, and other PROTAC-related issues and their target immunotherapeutic response. Furthermore discussed about the benefits, possible challenges, viewpoints, comparison with other targeted protein degraders (LYTACs, AUTOTACs) and the most current research results of PROTACs technology in multiple oncology therapies. Abbreviations: PROTACs, Proteolysis Targeting Chimeras; PK, Pharmacokinetic; PD, Pharmacodynamic; MetAP-2, (methionine aminopeptidase 2); BCL6, B-cell lymphoma 6; GCN5, General Control Nonderepressible 5; BKT, Bruton's tyrosine kinase; BET, Bromodomain and extra-terminal; AR, Androgen or Androgen receptor; ER, Estrogen or Estrogen receptor; FDA, Food and Drug Administration; mCRPC, Metastatic castration-resistant prostate cancer; STAT3, Signal Transducer and Activator of Transcription 3; FAK, Focal adhesion kinase; POI, Protein of interest; PEG, Polyethylene glycol; UPS, Ubiquitin-Proteasome System; VHL, Von Hippel-Lindau; CRBN, Cereblon; MDM2, Mouse Double Minute 2 homologue; cIAP, Cellular Inhibitor of Apoptosis; RNF, Ring Finger Protein; BRD, Bromodomain; CDK, Cyclin-dependent kinase; PAMPA, Parallel Artificial Membrane Permeability studies; BRET, Bioluminescence Resonance Energy Transfer; MCL, Mantle cell lymphoma; MCL-1, Myeloid Cell Leukemia 1; BCL-XL, B-cell lymphoma extra-large; TRK, Tropomyosin Receptor Kinase; RTKs, Transmembrane Receptor Tyrosine Kinase; NTRK, Neurotrophic Tyrosine Receptor Kinase; DHT, Dihydrotestosterone; EGFR, Epidermal Growth Factor Receptor; EGFR-TKIs, EGFR tyrosine kinase inhibitors; NSCLC, non-small cell lung cancer; BCR, B-cell receptor; CML, Chronic myelogenous leukemia; TKI, Tyrosine kinase inhibitors; MoA, Mechanism of action; TPD, Targetted protein degraders; LYTACs, Lysosome targeting chimeras; ASGPR, Asialoglycoprotein receptor; AUTOTACs, Autophagy-Targeting Chimeras; ATTECs, Autophagy-tethering compounds; CRISPR-Cas9, Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR-associated protein 9; TALEN, Transcription Activator-Like Effector Nuclease; ZFN, Zinc Finger Nuclease.

Precision-engineered PROTACs minimize off-tissue effects in cancer therapy

Proteolysis-targeting chimeras (PROTACs) offer a groundbreaking approach to selectively degrade disease-related proteins by utilizing the ubiquitin-proteasome system. While this strategy shows great potential in preclinical and clinical settings, off-tissue effects remain a major challenge, leading to toxicity in healthy tissues. This review explores recent advancements aimed at improving PROTAC specificity, including tumor-specific ligand-directed PROTACs, pro-PROTACs activated in tumor environments, and E3 ligase overexpression strategies. Innovations such as PEGylation and nanotechnology also play a role in optimizing PROTAC efficacy. These developments hold promise for safer, more effective cancer therapies, though challenges remain for clinical translation.

An Oral PROTAC Targeting HPK1 Degradation Potentiates Anti-Solid Tumor Immunity

Hematopoietic progenitor pinase1 (HPK1) knockout has been identified as an efficient route to enhance anti-tumor immune response. Here, this work develops an oral proteolysis targeting chimera (PROTAC) targeting HPK1 to efficiently and selectively degrade HPK1 to augment immunotherapeutic outcomes. In a postoperative tumor model of human cervical cancer in NSG mice, the orally-administrated PROTAC can reach tumors, down-regulate HPK1 levels in locally-administrated CAR-T cells, and promote their efficiency in inhibiting solid tumor recurrence, achieving 50% partial response (PR) and 50% complete response (CR). In addition, oral administration of PROTAC can amplify the suppression capability of the anti-PD-L1 antibody on the growth of CT26 solid tumors in BALB/c mice by promoting the infiltration of CD45-positive immune cells from 0.7% to 1.5% and CD3-positive T cells from 0.2% to 0.5% within the tumors.

Precise HER2 Protein Degradation via Peptide-Conjugated Photodynamic Therapy for Enhanced Breast Cancer Immunotherapy

Breast cancer, the most prevalent malignancy among women, frequently exhibits high HER2 expression, making HER2 a critical therapeutic target. Traditional treatments combining the anti-HER2 antibody trastuzumab with immunotherapy face limitations due to toxicity and tumor microenvironment immunosuppression. This study introduces an innovative strategy combining HER2-targeting peptides with the photosensitizer (PSs) pyropheophorbide-a (Pha) via a gelatinase-cleavable linker, forming self-assembling nanoparticles. These nanoparticles actively target breast cancer cells and generate reactive oxygen species (ROS) under near-infrared light, effectively degrading HER2 proteins. Upon internalization, the linker is cleaved, releasing Pha-PLG and enhancing intracellular photodynamic therapy (PDT). The Pha-PLG molecules self-assemble into nanofibers, prolonging circulation, boosting immune induction, and activating CD8+ T cells, thus promoting a robust anti-tumor immune response. In vivo, studies confirm superior biosafety, tumor targeting, and HER2 degradation, with increased cytotoxic T cell activity and improved antitumor immunity. This integrated strategy offers a promising new avenue for breast cancer treatment.

Design, Synthesis, and Activity Evaluation of BRD4 PROTAC Based on Alkenyl Oxindole-DCAF11 Pair

Proteolytic targeting chimera (PROTAC) represent an advanced strategy for targeting undruggable proteins, and the molecular warheads targeting E3 ligases play a crucial role. Recently, we explored an alkenyl oxindole warhead targeting the E3 ligase DCAF11 and sought to validate its potential. In this study, we synthesized a range of BRD4 PROTACs (8a-8o, 14a-14f, 22a-22m) with modified alkenyl oxindole warheads and developed a high-throughput screening system based on high-content imaging. We identified L134 (22a) as a potent BRD4 degrader, achieving BRD4 degradation (Dmax > 98%, DC50 = 7.36 nM) and demonstrating antitumor activity. Mechanically, BRD4 degradation by L134 was mediated through the ubiquitin-proteasome system in a DCAF11-dependent manner. Therefore, this study provides a rapid screening method for effective PROTACs and highlights the PROTAC L134 based on alkenyl oxindole-DCAF11 pair as a promising candidate for treating BRD4-driven cancers.

Advancing Cancer Immunotherapy through Engineering New PD-L1 Degraders: A Comprehensive Study from Small Molecules to PD-L1-Specific Peptide-Drug Conjugates

Despite the considerable achievements of antibodies targeting PD-1/PD-L1 in cancer immunotherapy, limitations in antitumor immune response and pharmacokinetics hinder their clinical adoption. Small molecules toward PD-L1 degradation signifies an innovative avenue to modulate PD-1/PD-L1 axis. Herein, we unveil a comprehensive engineering involving the development of new PD-L1 degraders based on the berberine (BBR) and palmatine (PMT) bioactive frameworks and explore their translational potential for cancer immunotherapy using a peptide-drug conjugate strategy. Chemical modifications at the O-9 position of PMT dramatically enhance the PD-L1 degradation capacity. Further conjugation of PMT degraders with an anti-PD-L1 peptide featuring disulfide linkers enables efficient GSH-specific prodrug activation, yielding synergistic immunotherapeutic benefits through both external PD-L1 blockade and internal PD-L1 degradation mechanisms. This work elucidates the compelling charm of the discovery and application of PD-L1 degraders, offering solutions to the challenges in advancing cancer immunotherapy in widespread clinics.

Design of Murine Double Minute 2 Proteolysis Targeting Chimera Degraders with a Built-In Tumor-Targeting Ability

Proteolysis targeting chimeras (PROTACs) are heterobifunctional molecules to induce the proteasomal degradation of target proteins. Currently, there are no tumor-targeting PROTACs for modulating oncogenic murine double minute 2 (MDM2). AS1411 is a tumor-targeting aptamer that specifically recognizes nucleolin (NCL) overexpressed on the surface of tumor cells. We recently repurposed AS1411 as an MDM2 recruiter since it could form an NCL-bridged ternary complex with MDM2. In this study, we design a PROTAC molecule AS1411-VH032 via conjugating AS1411 with a recruiter of von Hippel-Lindau (VHL) ligase VH032. AS1411-VH032 facilitates tumor-selective degradation of MDM2, leading to tumor shrinkage with no detectable toxicity. Besides being a molecular target, MDM2 also serves as an E3 ligase harnessed by PROTACs. Thus, we developed an AS1411-based homo-PROTAC homoAS1411, which induces tumor-specific suicide degradation of MDM2 and prevents tumor progression without causing side effects. Both AS1411-VH032 and homoAS1411 are promising MDM2 degraders with built-in tumor-targeting ability, which balances the antitumor efficacy with a favorable safety profile.

Paired Electro-Synthesis of Remote Amino Alcohols with/in H2O

Amino alcohols, particularly remote amino alcohols and peptide alcohols, are valuable due to their functional diversity in biologically active compounds. However, traditional synthesis methods face significant challenges, making electrochemistry an attractive alternative. We have developed a mild and biocompatible sequential paired electrolysis strategy, leveraging copper-electrocatalysis to synthesize diverse remote amino alcohols, including unnatural peptide alcohols. Both experimental results and density functional theory (DFT) calculations demonstrated that water serves as both the hydroxyl source and the solvent, facilitating the generation of CuH with Cu(I) at the cathode, which in turn reduces the aldehyde intermediates formed during the reaction.

DNA Nanotechnology for Application in Targeted Protein Degradation

DNA is a kind of flexible and versatile biomaterial for constructing nanostructures and nanodevices. Due to high biocompatibility and programmability and easy modification and fabrication, DNA nanotechnology has emerged as a powerful tool for application in intracellular targeted protein degradation. In this review, we summarize the recent advances in the design and mechanism of targeted protein degradation technologies such as protein hydrolysis targeted chimeras, lysosomal targeted chimeras, and autophagy based protein degradation. Subsequently, we introduce the DNA nanotechnologies of DNA cascade circuits, DNA nanostructures, and dynamic machines. Moreover, we present the latest developments in DNA nanotechnologies in targeted protein degradation. Finally, the vision and challenges are discussed.

Protein degradation kinetics measured by microinjection and live-cell fluorescence microscopy

We have developed a method combining microinjection and automated fluorescence microscopy to continuously assess the degradation rate, subcellular localization and intracellular concentration of protein analytes at the single-cell level. Cells are unperturbed and grown in unaltered environmental conditions and show high viability. The injection of analytes at defined ratios and concentrations allows for a clearly defined starting point of degradation, without the entanglement of biosynthesis/uptake, often encountered in existing methods. The possibility to evaluate, add, or remove post-translational modifications prior to injection represents a powerful tool to assess minute protein degradation rate changes with high precision and allowed us to determine the absolute degradation rates caused by N-degron pathway engagement, with a focus on the role of acetylation. The low degradation rate of eGFP was found to be caused by inefficient N-terminal proteasomal unfolding. We moreover quantified the surprisingly strong influences of commonly used peptide tags and detected high variation between fluorescent proteins with regard to both protein degradation and subcellular localization. Furthermore, we have validated the use of chemically coupled dyes as robust reporters for protein degradation, and elucidated the significance of their membrane-permeability, thereby extending the applicability of our method to any protein of interest.

Property-based optimisation of PROTACs

PROTACs are an emerging therapeutic approach towards targeted protein degradation. This article examines the leading examples of this modality that are in clinical development through the prism of their physicochemical properties. In particular, the optimisation of the various components of PROTACs together with the difficulties faced by medicinal chemists seeking to achieve oral bioavailability in this challenging space are outlined. Guidance, opinion and advice based on the authors' own experiences in this area are offered in the hope this may be useful to others working in this fascinating frontier of drug discovery.

Proteolysis-targeting vaccines (PROTAVs) for robust combination immunotherapy of melanoma

Protein/peptide subunit vaccines are promising to promote the tumor therapeutic efficacy of immune checkpoint blockade (ICB). However, current protein/peptide vaccines elicit limited antitumor T cell responses, leading to suboptimal therapeutic efficacy. Here, we present proteolysis-targeting vaccines (PROTAVs) that facilitate antigen proteolytic processing and cross-presentation to potentiate T cell responses for robust ICB combination immunotherapy of melanoma. PROTAVs are modular conjugates of protein/peptide antigens, E3 ligase-binding ligands, and linkers. In antigen-presenting cells (APCs), PROTAVs bind to E3 ligases to rapidly ubiquitinate PROTAV antigens, facilitating antigen proteolytic processing by proteasome, and thereby promoting antigen cross-presentation to T cells and potentiating CD8+ T cell responses. We developed a melanoma PROTAV using a tandem peptide of trivalent melanoma-associated antigens. Co-delivered by lipid nanoparticles (LNPs) with bivalent immunostimulant adjuvants, this PROTAV promotes the quantity and quality of melanoma-specific CD8+ T cells in mice. Further, combining PROTAV and ICB ameliorates the immunosuppressive melanoma microenvironment. As a result, PROTAV and ICB combination enhances melanoma complete regression rates and eradicated 100% large Braf V600E melanoma without recurrence in syngeneic mice. PROTAVs hold the potential for robust tumor combination immunotherapy.

A new tau dephosphorylation-targeting chimera for the treatment of tauopathies

Abnormal accumulation of hyperphosphorylated tau protein plays a pivotal role in a collection of neurodegenerative diseases named tauopathies, including Alzheimer's disease (AD). We have recently conceptualized the design of hetero-bifunctional chimeras for selectively promoting the proximity between tau and phosphatase, thus specifically facilitating tau dephosphorylation and removal. Here, we sought to optimize the construction of tau dephosphorylating-targeting chimera (DEPTAC) and obtained a new chimera D14, which had high efficiency in reducing tau phosphorylation both in cell and tauopathy mouse models, while showing limited cytotoxicity. Moreover, D14 ameliorated neurodegeneration in primary cultured hippocampal neurons treated with toxic tau-K18 fragments, and improved cognitive functions of tauopathy mice. These results suggested D14 as a cost-effective drug candidate for the treatment of tauopathies.

Toward effective Atg8-based ATTECs: Approaches and perspectives

Induction of Atg8-family protein (LC3/GABARAP proteins in human) interactions with target proteins of interest by proximity-inducing small molecules offers the possibility for novel targeted protein degradation approaches. However, despite intensive screening campaigns during the last 5 years, no potent ligands for LC3/GABARAPs have been developed, rendering this approach largely unexplored and unsuitable for therapeutic exploitation. In this Viewpoint, we analyze the reported attempts identifying LC3/GABARAP inhibitors and provide our own point of view why no potent inhibitors have been found. Additionally, we designate reasonable directions for the identification of potent and probably selective LC3/GABARAP inhibitors for alternative therapeutic applications.

Patenting perspective of modulators of ClpP endopeptidase: 2019-present

INTRODUCTION

ClpP is a highly conserved serine protease that plays a crucial role in maintaining protein homeostasis in both bacterial cells and human mitochondria. Several studies have demonstrated the potential of ClpP as a drug target, with ClpP modulators, including both inhibitors and activators, showing promise in treating a range of conditions such as drug-resistant bacteria, malignant cancers, and fatty liver disease.

AREA COVERED

This review provides an overview of patents related to ClpP modulators filed over the last five years, detailing their claims and therapeutic applications. The sources of patent information included databases of the European Patent Office, the China Patent Office and the U.S.A. patent Office, while relevant research articles were accessed through PubMed.

EXPERT OPINION

The number of patents concerning ClpP modulators is on the rise, reflecting advancements in related research. By summarizing and outlining relevant patents, we aim to stimulate further interest among researchers, ultimately leading to the development of effective drugs based on ClpP modulators. The broad spectrum of diseases associated with ClpP dysfunction underscores the potential for ClpP modulators to address a wide range of therapeutic needs.

Nanotechnology-Enabled Targeted Protein Degradation for Cancer Therapeutics

Targeted protein degradation (TPD) represents an innovative therapeutic strategy that has garnered considerable attention from both academic and industrial sectors due to its promising developmental prospects. Approximately 85% of human proteins are implicated in disease pathogenesis, and the FDA has approved around 400 drugs targeting these disease-related proteins, predominantly enzymes, transcription factors, and non-enzymatic proteins. However, existing therapeutic modalities fail to address certain "high-value" targets, such as c-Myc and Ras. The emergence of proteolysis-targeting chimeras (PROTAC) technology has introduced TPD into a new realm. The capability to target non-druggable sites has expanded the therapeutic horizon of protein-based drugs, although challenges related to bioavailability, safety, and adverse side effects have constrained their clinical progression. Nano-delivery systems and emerging TPD modalities, such as molecular glues, lysosome-targeted chimeras (LYTACs), autophagy system compounds (ATTEC), and antibody PROTAC (AbTACs), have mitigated some of these limitations. This paper reviews the latest advancements in TPD, highlighting their applications and benefits in cancer therapy, and concludes with a forward-looking perspective on the future development of this field.