The c-ros oncogene 1 (ROS1), an oncogenic driver, is known to induce non-small cell lung cancer (NSCLC) when overactivated, particularly through the formation of fusion proteins. Traditional targeted therapies focus on inhibiting ROS1 activity with ROS 1 inhibitors to manage cancer progression. However, a new strategy involving the design of protein degraders offers a more potent approach by completely degrading ROS1 fusion oncoproteins, thereby effectively blocking their kinase activity and enhancing anti-tumour potential. Utilizing PROteolysis-TArgeting Chimera (PROTAC) technology and informed by molecular docking and rational design, we report the first ROS1-specific PROTAC, SIAIS039. This degrader effectively targets multiple ROS1 fusion oncoproteins (CD74-ROS1, SDC4-ROS1 and SLC34A2-ROS1) in engineered Ba/F3 cells and HCC78 cells, demonstrating anti-tumour effects against ROS1 fusion-driven cancer cells. It suppresses cell proliferation, induces cell cycle arrest, and apoptosis, and inhibits clonogenicity. The anti-tumour efficacy of SIAIS039 surpasses two approved drugs, crizotinib and entrectinib, and matches that of the top inhibitors, including lorlatinib and taletrectinib. Mechanistic studies confirm that the degradation induced by 039 requires the participation of ROS1 ligands and E3 ubiquitin ligases, and involves the proteasome and ubiquitination. In addition, 039 exhibited excellent oral bioavailability in a mouse xenograft model, highlighting its potential for clinical application. In conclusion, our study presents a promising and novel therapeutic strategy for ROS1 fusion-positive NSCLC by targeting ROS1 fusion oncoproteins for degradation, laying the foundation for the development of further PROTAC and offering hope for patients with ROS1 fusion-positive NSCLC.

PROTACs (Proteolysis-Targeting Chimeras) have emerged as a groundbreaking class of chemical tools that facilitate the degradation of target proteins by leveraging the ubiquitin-proteasome system (UPS). However, the effective utilization of PROTACs in chemical biology studies and therapeutics encounters significant challenges when it comes to achieving cell-selective protein degradation and in vivo applications. This review article aims to shed light on recent advancements in the development of Pro-PROTACs, which exhibit controlled protein degradation capabilities in response to external stimuli or disease-related endogenous biochemical signals. The article delves into the specific chemical strategies employed to regulate the interaction between PROTACs and E3 ubiquitin ligases or target proteins. These strategies enable spatial and temporal control over the protein degradation potential of Pro-PROTACs. Furthermore, the review summarizes recent investigations regarding the delivery of PROTACs using biodegradable nanoparticles for in vivo applications and targeted protein degradation. Such delivery systems hold great promise for enabling efficient and selective protein degradation in vivo. Lastly, the article provides a perspective on the future design of multifunctional PROTACs and their intracellular delivery mechanisms, with a particular focus on achieving cell-selective protein degradation.

Targeted Protein Degradation is an emerging and rapidly developing technique for designing and treating new drugs. With the emergence of a promising class of pharmaceutical molecules, Heterobifunctional Proteolysis-targeting chimeras (PROTACs), TPD has become a powerful tool to completely tackle pathogenic proteins with traditional small molecule inhibitors. However, the conventional PROTACs have gradually exposed potential disadvantages of poor oral bioavailability and pharmacokinetic (PK) and absorption, distribution, metabolism, excretion, and toxicity (ADMET) characteristics due to their larger molecular weight and more complex structure than the conventional small-molecule inhibitors. Therefore, 20 years after the concept of PROTAC was proposed, more and more scientists are committed to developing new TPD technology to overcome its defects. And several new technologies and means have been explored based on \"PROTAC\" to target \"undruggable proteins\". Here, we aim to comprehensively summarize and profoundly analyze the research progress of targeted protein degradation based on PROTAC targeting the degradation of \"undruggable\" targets. In order to clarify the significance of emerging and highly effective strategies based PROTACs in the treatment of various diseases especially in overcoming drug resistance in cancer, we will focus on the molecular structure, action mechanism, design concepts, development advantages and challenges of these emerging methods(e.g., aptamer-PROTAC conjugates, antibody-PROTACs and folate-PROTACs).

The development and application of traditional drugs represented by small molecule chemical drugs and biological agents, especially inhibitors, have become the mainstream drug development. In recent years, targeted protein degradation (TPD) technology has become one of the most promising methods to remove specific disease-related proteins using cell self-destruction mechanisms. Many different TPD strategies are emerging based on the ubiquitin-proteasome system (UPS) and the autophagy-lysosomal pathway (ALP), including but not limited to proteolysis-targeting chimeras (PROTAC), molecular glues (MG), lysosome targeting chimeras (LYTAC), chaperone-mediated autophagy (CMA)-targeting chimeras, autophagy-targeting chimera (AUTAC), autophagosome-tethering compound (ATTEC), and autophagy-targeting chimera (AUTOTAC). The advent of targeted degradation technology can change most protein targets in human cells from undruggable to druggable, greatly expanding the therapeutic prospect of refractory diseases such as metabolic syndrome. Here, we summarize the latest progress of major TPD technologies, especially in metabolic syndrome and look forward to providing new insights for drug discovery.

Chronic myeloid leukemia (CML) is a malignant disease of the hematopoietic system with crucial pathogenic protein named BCR-ABL, which endangers the life of patients severely. As a milestone of targeted drug, Imatinib has achieved great success in the treatment of CML. Nevertheless, inevitable drug resistance of Imatinib has occurred frequently in clinical due to the several mutations in the BCR-ABL kinase. Subsequently, the second-generation of tyrosine kinase inhibitors (TKIs) against BCR-ABL was developed to address the mutants of Imatinib resistance, except T315I. To date, the third-generation of TKIs targeting T315I has been developed for improving the selectivity and safety. Notably, the first allosteric inhibitor has been in market which could overcome the mutations in ATP binding site effectively. Meanwhile, some advanced technology, such as proteolysis-targeting chimeras (PROTAC) based on different E3 ligand, are highly expected to overcome the drug resistance by selectively degrading the targeted proteins. In this review, we summarized the current research progress of inhibitors and degraders targeting BCR-ABL for the treatment of CML.

Proteolysis-targeting chimeras (PROTACs), bifunctional molecules consisting of a ligand of protein of interest (POI), an E3 ligase ligand and a linker, have been developed to hijack the ubiquitin-proteasome system (UPS) to induce different POIs degradation. Currently, the first oral PROTACs (ARV-110 and ARV-471) have shown encouraging efficacy in clinical trials of prostate and breast cancer treatment, which turns a new avenue for the development of PROTAC research. In this review, we focus on a detailed summary of the latest progress of PROTACs and elucidate the advantages of PROTACs technology. In addition, potential challenges and perspectives of PRTOACs are discussed.

Proteolysis targeting chimeras (PROTACs) have been developed to be an effective technology for targeted protein degradation. Each PROTAC contains three key components: a protein-of-interest (POI) ligand, an E3 ligase ligand, and a linker. These bifunctional molecules can hijack the intracellular inherent ubiquitin-proteasome system to degrade different POIs. With several advantages over other therapeutic strategies, PROTACs have set off a new upsurge of drug discovery in recent years. PRTOACs have been extensively explored worldwide and have excelled not only in cancer diseases but also in cardiovascular diseases, fatty liver disease, immune diseases, neurodegenerative diseases, and viral infections. In this review, we aim to summarize the rapid progress from 2010 to 2021 in PROTACs targeting various non-oncoproteins and elucidate the advantages of PROTACs technology. Finally, the potential challenges of this dynamic field are also discussed.

Proteolysis targeting chimera (PROTAC), hijacking protein of interest (POI) and recruiting E3 ligase for target degradation via the ubiquitin-proteasome pathway, is a novel drug discovery paradigm which has been widely used as biological tools and medicinal molecules with the potential of clinical application value. Currently, ARV-110, an orally small molecule PROTAC was designed to specifically target Androgen receptor (AR), firstly enters clinical phase I trials for the treatment of metastatic castration-resistant prostate cancer, which turns a new avenue for the development of PROTAC. We herein provide a detail summary on the latest one year progress of PROTAC target various proteins and elucidate the advantages of PROTAC technology. Finally, the potential challenges of this vibrant field are also discussed.

Anaplastic lymphoma kinase (ALK) is a major target in treating non-small-cell lung cancer, and several ALK inhibitors have been developed to antagonize its kinase activity. However, patients treated with inhibitors ultimately develop drug resistance. Therefore, therapies with new mechanisms of action are needed. Proteolysis targeting chimeras (PROTACs) are molecules that comprise a ligand for binding a protein of interest (POI), a connecting linker and a ligand for recruiting E3 ligase, and cause degradation of the target POI. Here, the first multi-headed PROTAC, as a proof of concept, is developed as a gold nanoparticle (GNP)-based drug delivery system for delivering PROTACs to target ALK. Pegylated GNPs loaded with both ceritinib and pomalidomide molecules, termed Cer/Pom-PEG@GNPs, showed good stability in several media. The GNP conjugates potently decreased the levels of ALK fusion proteins in a dose- and time-dependent manner, and specifically inhibited the proliferation of NCI-H2228 cells. In comparison with small molecule PROTACs, the new multi-headed PROTAC promoted the formation of coacervates of POIs/multi-headed PROTAC/E3 ubiquitin ligases, and POI and E3 ubiquitin ligase interacted through multidirectional ligands and a flexible linker, thereby avoiding the need for complicated structure optimization of PROTACs. In conclusion, Cer/Pom-PEG@GNPs can degrade intracellular ALK fusion proteins with minor off-target toxicity and can be applied in patients resistant to ALK inhibitors. As a nano-based drug carrier, Cer/Pom-PEG@GNPs have the potential to enable prolonged circulation and specifically distribute drugs to tumor regions in vivo; thus, further investigation is warranted.