Proteolysis Targeting Chimera Technology Research Articles

Targeting the Interplay of Proteins through PROTACs for Management Cancer and Associated Disorders

Abstract: Cancer remains a formidable global health challenge, necessitating innovative therapeutic strategies. Traditional small-molecule inhibitors often face limitations in selectively targeting diseaseassociated proteins, leading to side effects and incomplete therapeutic responses. Proteolysistargeting chimeras (PROTACs) turned out to be a promising approach to address these challenges. Unlike traditional inhibitors, PROTACs leverage the cellular ubiquitin-proteasome system to selectively degrade disease-associated proteins. In this review, we addressed PROTACs: Targeted approach for cancer management, key findings, limitations, and future perspectives. For this, the authors have critically reviewed literature obtained from prime sources comprising Google Scholar, Web of Science, PubMed, and Publons. From the selected papers' reference section, a number of pertinent articles were retrieved. Preclinical studies and early-phase clinical trials have demonstrated the efficacy and potential of PROTACs in cancer management. Additionally, the potential of PROTACs in overcoming therapy resistance, tackling tumor heterogeneity, and engaging multiple pathways is explored. As research advances, addressing challenges and refining PROTAC technology will pave the way for their integration into the next generation of cancer therapeutics, marking a transformative era in precision medicine.

Fluorescence theranostic PROTACs for real-time visualization of ERα degradation

Proteolysis targeting chimera (PROTAC) technology, a groundbreaking strategy for degradation of pathogenic proteins by hijacking of the ubiquitin-proteasome-system has become a promising strategy in drug design. However, the real-time monitoring and visualization of protein degradation processes have been long-standing challenges in the realm of drug development. In this research, we sought to amalgamate the highly efficient protein-degrading capabilities of PROTAC technology with the visualization attributes of fluorescent probes, with the potential to pave the path for the design and development of a novel class of visual PROTACs. These novel PROTACs uniquely possess both fluorescence imaging and therapeutic characteristics, all with the goal of enabling real-time observations of protein degradation processes. Our approach involved the utilization of a high ER-targeting fluorescent probe, previously reported in our laboratory, which served as a warhead that specifically binds to the protein of interest (POI). Additionally, a VHL ligand for recruiting E3 ligase and linkers of various lengths were incorporated to synthesize a series of novel ER-inherent fluorescence PROTACs. Among them, compound A3 demonstrated remarkable efficiency in degrading ERα proteins (DC50 = 0.12 μM) and displaying exceptional anti-proliferative activity against MCF-7 cells (IC50 = 0.051 μM). Furthermore, it exhibited impressive fluorescence imaging performance, boasting an emission wavelength of up to 582 nm, a Stokes shift of 116 nm, and consistent optical properties. These attributes make it especially suitable for the real-time, in situ tracking of ERα protein degradation processes, thus may serve as a privileged visual theranostic PROTAC for ERα+ breast cancer. This study not only broadens the application spectrum of PROTAC technology but also introduces a novel approach for real-time visualization of protein degradation processes, ultimately enhancing the diagnostic and treatment efficacy of PROTACs.

Application of PROTACs in target identification and validation

Proteolysis targeting chimeras (PROTACs), as a novel therapeutic drug model, has received widespread attention from academia and the pharmaceutical industry. PROTAC technology has led researchers to focus on developing chemical biology tool properties due to the unique operating mechanism and protein dynamic regulatory properties. In recent years the rapid development of PROTAC technology has gradually made PROTACs an essential tool for target identification and validation. To further promote the application of PROTAC tools in drug discovery and basic medical science research, this review distinguished target identification and validation concepts. Furthermore, research progress in PROTAC technology was summarized.

Harnessing PROTAC technology to combat stress hormone receptor activation

Counteracting the overactivation of glucocorticoid receptors (GR) is an important therapeutic goal in stress-related psychiatry and beyond. The only clinically approved GR antagonist lacks selectivity and induces unwanted side effects. To complement existing tools of small-molecule-based inhibitors, we present a highly potent, catalytically-driven GR degrader, KH-103, based on proteolysis-targeting chimera technology. This selective degrader enables immediate and reversible GR depletion that is independent of genetic manipulation and circumvents transcriptional adaptations to inhibition. KH-103 achieves passive inhibition, preventing agonistic induction of gene expression, and significantly averts the GR’s genomic effects compared to two currently available inhibitors. Application in primary-neuron cultures revealed the dependency of a glucocorticoid-induced increase in spontaneous calcium activity on GR. Finally, we present a proof of concept for application in vivo. KH-103 opens opportunities for a more lucid interpretation of GR functions with translational potential.

Discovery of proteolysis-targeting chimera targeting undruggable proteins using a covalent ligand screening approach

Targeted protein degradation (TPD) technology, such as proteolysis-targeting chimera (PROTAC), has become a new therapeutic modality. However, the degradation of undruggable proteins, such as those involved in protein-protein interactions (PPIs), using PROTAC is still limited owing to the difficulties in finding small-molecule binders of these proteins. To identify new chemical moieties that bind to the target sites of the protein of interest (POI), we conducted a site-specific and fragment-based covalent ligand screening using liquid chromatography-tandem mass spectrometry (LC-MS/MS). To apply the selected hits to the PROTAC approach, two-dimensional (2D) nuclear magnetic resonance (NMR) experiments were performed to evaluate the reversible binding of their analogs without covalent warheads. To proof the proposed approach, human mouse double minute (MDM)2 was selected as a model system since it is involved in PPIs and is known to be a degradable target protein. Western blot analysis showed that newly synthesized PROTACs, incorporated reversible analogs of screening hits, affected degradation in a dose- and time-dependent manner. This methodology makes it possible to use PROTAC technology to exploit previously undruggable proteins for TPD.

Development of decoy oligonucleotide-warheaded chimeric molecules targeting STAT3

Proteolysis-targeting chimera (PROTAC) technology is a disruptive innovation in the drug development community, and over 20 PROTAC molecules are currently under clinical evaluation. These PROTAC molecules contain small-molecule warheads that bind to target proteins. Recently, oligonucleotide-warheaded PROTACs have emerged as a promising new tool to degrade DNA-binding proteins such as transcription factors. In this study, we applied an oligonucleotide-warheaded PROTAC technology to induce the degradation of signal transducer and activator of transcription 3 (STAT3), which is a hard-to-target protein. A double-stranded decoy oligonucleotide specific to STAT3 was conjugated to E3 binders (pomalidomide, VH032, and LCL161) to generate PROTAC molecules that recruited different E3 ubiquitin ligases cereblon (CRBN), von Hippel-Lindau (VHL), and inhibitor of apoptosis protein (IAP), respectively. One of the resulting PROTAC molecules, POM-STAT3, which recruits CRBN, potently induces STAT3 degradation. STAT3 degradation by POM-STAT3 was abolished by scrambling the oligonucleotide sequences of POM-STAT3 and by adding a double-stranded decoy oligonucleotide against STAT3 in a competitive manner, suggesting the significance of oligonucleotide sequences in STAT3 degradation. Moreover, POM-STAT3-induced STAT3 degradation was suppressed by the CRBN binder thalidomide, proteasome inhibitor bortezomib, E1 inhibitor MLN7243, and siRNA-mediated depletion of CRBN, indicating that STAT3 degradation is mediated by the ubiquitin-proteasome system, which involves CRBN as the responsible E3 ubiquitin ligase. Consistent with STAT3 degradation, NCI-H2087 cell viability was severely reduced following POM-STAT3 treatment. Thus, POM-STAT3 is a STAT3 degrader that potentially has cytocidal activity against cancer cells that are highly dependent on STAT3 signaling, which implies that inducing protein degradation by decoy oligonucleotide-warheaded PROTAC molecules could be harnessed to be therapeutic against oncogenic transcription factors.

PROTAC derivatization of natural products for target identification and drug discovery: Design of evodiamine-based PROTACs as novel REXO4 degraders

IntroductionNatural products (NPs) play a crucial role in the development of therapeutic drugs. However, it is still highly challenging to identify the targets of NPs. Besides, NPs usually exert their pharmacological activities via acting on multiple targets or pathways, which also poses great difficulties for the target identification of NPs. ObjectivesInspired by our continuous efforts in designing drug-like protein degraders, this study introduced a successful example for the target identification and drug discovery of natural products evodiamine by employing PROTAC technology. MethodsTaking advantages of proteolysis targeting chimera (PROTAC), herein an integrated strategy combining PROTAC derivatization, quantitative proteomic analysis and binding affinity validation was developed for target identification and drug discovery of antitumor NP evodiamine. ResultsIn this study, both highly potent PROTACs and negative controls were designed for quantitative proteomic analysis. Furthermore, REXO4 was confirmed as a direct target of 3-fluoro-10-hydroxylevodiamine, which induced cell death through ROS. In addition, the PROTAC 13c effectively degraded REXO4 both in vitro and in vivo, leading to potent antitumor activities and reduced toxic side effects. ConclusionIn summary, we developed an integrated strategy for the target identification and drug discovery of NPs, which was successfully applied to the PROTAC derivatization and target characterization of evodiamine. This proof-of-concept study highlighted the superiority of PROTAC technology in target identification of NPs and accelerated the process of NPs-based drug discovery, exhibiting broad application in NP-based drug development.

Design, Synthesis, and Biological Evaluation of Proteolysis-Targeting Chimeras as Highly Selective and Efficient Degraders of Extracellular Signal-Regulated Kinase 5.

Extracellular signal-regulated kinase 5 (ERK5) is recognized as a key member of the mitogen-activated protein kinase family and is involved in tumor growth, migration, and angiogenesis. However, the results of ERK5 inhibition in multiple studies are controversial, and a highly specific ERK5-targeting agent is required to confirm physiological functions. Using proteolysis-targeting chimera technology, we designed the selective ERK5 degrader PPM-3 and examined its biological effect on cancer cells. Interestingly, the selective degradation of ERK5 with PPM-3 did not influence tumor cell growth directly. Based on proteomics analysis, the ERK5 deletion may be associated with tumor immunity. PPM-3 influences tumor development by affecting the differentiation of macrophages. Therefore, PPM-3 is an effective small-molecule tool for studying ERK5 and a promising immunotherapy drug candidate.

WITHDRAWN: Targeted protein degradation: A promising approach for cancer treatment

Targeted protein degradation (TPD) is a promising approach that has the ability to address disease-causing proteins. Compared to traditional inhibition, proteolysis targeting chimera (PROTAC) technology offers various benefits, including the potential to target mutant and overexpressed proteins along with characteristics to target undruggable proteomes. A significant obstacle to the ongoing effective treatment of malignancies is cancer drug resistance, which is developed frequently by mutated or overexpressed protein targets and causes current remedies to continuously lose their effectiveness. The effective use of PROTACs to degrade targets that have undergone mutations and conferred resistance to first-line cancer therapies has attracted much research attention. To find novel/effective treatments, we analyzed the advancements in PROTACs aimed at cancer resistance and targets. This review provides a description of how PROTAC-based anticancer drugs are currently being developed and how to counter resistance if developed to PROTAC technology. Moreover, modern technologies related to protein degradation, including autophagy-targeting chimeras (AUTAC), lysosome-targeting chimeras (LYTAC), antibody-based PROTAC (AbTAC), Glue-body chimeras (GlueTAC), transcription-factor-targeting chimeras (TRAFTAC), RNA-PROTAC, aptamer-PROTAC, Photo-PROTAC, folate-PROTAC, and in-cell click-formed proteolysis targeting chimeras (CLIPTACs), have been discussed along with their mechanisms of action.

A Modular Chemistry Platform for the Development of a Cereblon E3 Ligase-Based Partial PROTAC Library.

Proteolysis targeting chimeras (PROTACs) are a promising therapeutic strategy to selectively promote the degradation of protein targets by exploiting the ubiquitin-proteasome system. Among the limited number of E3 ligase ligands discovered for the PROTAC technology, ligands of cereblon (CRBN) E3 ligase, such as pomalidomide, thalidomide, or lenalidomide, are the most frequently used for the development of PROTACs. Our group previously reported that a phenyl group could be tolerated on the C4-position of lenalidomide as the ligand of CRBN to develop PROTACs. Herein, we report a modular chemistry platform for the efficient attachment of various ortho-, meta-, and para-substituted phenyls to the C4-position of the lenalidomide via Suzuki cross-coupling reaction, which allows the systematic investigation of the linker effect for the development of PROTACs against any target. We examined the substrate scope by preparing twelve lenalidomide-derived CRBN E3 ligase ligands with different linkers.

The role and efficacy of PROTAC in FLT3-mutated AML treatment

Small molecule Proteolysis Targeting Chimera (PROTAC) is an effective therapy for patients with FLT3-ITD acute myeloid leukemia (AML). By activating the ubiquitination system, PROTAC can generate protein and kinase degradation upon FLT3 to perform outcomes of antiproliferative activities. The focus of this study revolves around the investigation of the efficacy of VHL and CRBN-based PROTAC on FLT3 degradation compared to conventional immunotherapy agents such as quizartinib. By assessing the performances of PROTAC on MOLM-14 and MV4-11 cells with other therapies, comparing both adverse effects and benefits could demonstrate crucial approaches to applying PROTAC for AML treatments. The VHL-recruiting PROTAC based on the modification of quizartinib has shown promising effects where FLT3 within MV4-11 injected athymic mice had experienced around a 60% of decrease. The CRBN-based degrader TL12-186, on the other hand, had also demonstrated antiproliferative outcomes where 14 out of 7559 proteins of the MOLM-14 cell have been successfully degraded, showing a more than 25% decrease. Even though there seem to be some improvements in the VHL-recruiting PROTAC compared to traditional immunotherapy agents like quizartinib, CRBN-mediated PROTAC has shown a relatively less significant result. Critiquing in a variety of aspects, quizartinib has demonstrated better performance in cell permeability, low nanomolecular concentration, and degradation. The significance of this study provides an overview of existing PROTAC technology that shows effects on the treatment of FLT3-mutated AML. Further studies may be conducted on the foundation of this study to demonstrate the enhancements of each modified PROTAC compared to existing therapies.

The next generation of EGFR inhibitors: a patenting perspective of PROTACs based EGFR degraders

ABSTRACT Introduction Abnormal expression of epidermal growth factor receptor (EGFR) contributes to tumor development, especially in non-small cell lung cancer (NSCLC). Although multiple inhibitors have been developed to target diverse EGFR mutations and several have been approved, the inevitable drug resistance and side effect remain a challenge, which motivates novel strategies. Proteolysis-targeting chimeras (PROTACs) have been gaining momentum for their potential as novel therapeutics for human diseases by triggering protein degradation. To date, various potent and specific EGFR PROTACs have been discovered and some of them have entered clinical trials. Areas covered This review provides an overview of EGFR degraders in patents from 2016 to 2022. It provides an update of the discovery strategies, chemical structures, and molecular profiling of all available EGFR PROTACs. SciFinder, PubMed, Web of Science, EPO, and CNIPA databases were used for searching the literature and patents for EGFR PROTACs. Expert opinion By employing the PROTAC technology, highly potent and selective EGFR degraders based on four generation EGFR inhibitors have been developed, which offer a new strategy to target EGFR mutations and overcome the drug resistance. Despite the satisfactory result in vitro and in vivo studies, their therapeutic value awaits more rigorous preclinical testing and clinical investigation.

Clinician's guide to targeted estrogen receptor degradation using PROTAC in patients with estrogen receptor-positive metastatic breast cancer.

Metastatic breast cancer (MBC) remains a major clinical challenge, necessitating the development of innovative therapeutic strategies. Estrogen receptor (ER) degradation using proteolysis-targeting chimeras (PROTAC) has emerged as a promising approach for overcoming acquired resistance to endocrine therapy. This review will summarize recent findings, highlighting the role of ER degradation by PROTAC in patients with MBC. The application of PROTAC technology for ER degradation has demonstrated initial success in preclinical and early clinical studies. PROTACs, consisting of an ER-targeting moiety, an E3 ubiquitin ligase-recruiting moiety, and a linker, facilitate ER ubiquitination and subsequent proteasomal degradation. Yet, significant challenges persist in the clinical translation of ER degradation by PROTAC. These include the optimization of PROTAC design, elucidation of mechanisms underlying resistance to PROTAC-induced ER degradation, and identification of predictive biomarkers for patient stratification. Additionally, addressing potential off-target effects and toxicity profiles remains a critical aspect of developing PROTAC-based therapies. Recent data demonstrate the potential of ER degradation by PROTAC as a therapeutic strategy for patients with MBC. Continued research efforts and development of synergistic combinations are crucial for further advancing PROTAC-based therapies and improving outcomes in patients with MBC.

Development of the first geldanamycin-based HSP90 degraders.

Despite the early clinical promise, adverse events such as acquired resistance and dose-limiting toxicities have barred the widespread use of HSP90 inhibitors as anticancer drugs. A new approach involving proteolysis-targeting chimeras (PROTACs) to degrade the protein instead of inhibiting it may overcome these problems. In this work, we describe the design, synthesis, and evaluation of cereblon-recruiting geldanamycin-based HSP90 degraders based on the PROTAC technology. Our best degrader, 3a, effectively decreased HSP90α and HSP90β levels in cells utilizing the ubiquitin-proteasome pathway.

Recent Advances in Pro-PROTAC Development to Address On-Target Off-Tumor Toxicity.

Proteolysis-targeting chimera (PROTAC) technology represents a novel and promising modality for targeted protein degradation with transformative implications for the clinical management of various diseases. Despite notable advantages, the possibility of on-target off-tumor toxicity in healthy cells represents a critical challenge to clinical applications in cancer treatment. Researchers are currently exploring strategies to enhance targeted degradation activity in a cell-selective manner to minimize undesirable side effects. In this Perspective, we highlight innovative approaches for prodrug-based PROTACs (pro-PROTACs) that facilitate tumor-targeted release. The development of such approaches may further expand the range of potential applications of PROTAC technology within drug development.

Antiviral PROTACs: Opportunity borne with challenge.

Proteolysis targeting chimera (PROTAC) degradation of pathogenic proteins by hijacking of the ubiquitin-proteasome-system has become a promising strategy in drug design. The overwhelming advantages of PROTAC technology have ensured a rapid and wide usage, and multiple PROTACs have entered clinical trials. Several antiviral PROTACs have been developed with promising bioactivities against various pathogenic viruses. However, the number of reported antiviral PROTACs is far less than that of other diseases, e.g., cancers, immune disorders, and neurodegenerative diseases, possibly because of the common deficiencies of PROTAC technology (e.g., limited available ligands and poor membrane permeability) plus the complex mechanism involved and the high tendency of viral mutation during transmission and replication, which may challenge the successful development of effective antiviral PROTACs. This review highlights the important advances in this rapidly growing field and critical limitations encountered in developing antiviral PROTACs by analyzing the current status and representative examples of antiviral PROTACs and other PROTAC-like antiviral agents. We also summarize and analyze the general principles and strategies for antiviral PROTAC design and optimization with the intent of indicating the potential strategic directions for future progress.

PROTACs: A novel strategy for cancer drug discovery and development.

Proteolysis targeting chimera (PROTAC) technology has become a powerful strategy in drug discovery, especially for undruggable targets/proteins. A typical PROTAC degrader consists of three components: a small molecule that binds to a target protein, an E3 ligase ligand (consisting of an E3 ligase and its small molecule recruiter), and a chemical linker that hooks first two components together. In the past 20 years, we have witnessed advancement of multiple PROTAC degraders into the clinical trials for anticancer therapies. However, one of the major challenges of PROTAC technology is that only very limited number of E3 ligase recruiters are currently available as E3 ligand for targeted protein degradation (TPD), although human genome encodes more than 600 E3 ligases. Thus, there is an urgent need to identify additional effective E3 ligase recruiters for TPD applications. In this review, we summarized the existing RING-type E3 ubiquitin ligase and their small molecule recruiters that act as effective E3 ligands of PROTAC degraders and their application in anticancer drug discovery. We believe that this review could serve as a reference in future development of efficient E3 ligands of PROTAC technology for cancer drug discovery and development.

PROTACs: Emerging Targeted Protein Degradation Approaches for Advanced Druggable Strategies.

A potential therapeutic strategy to treat conditions brought on by the aberrant production of a disease-causing protein is emerging for targeted protein breakdown using the PROTACs technology. Few medications now in use are tiny, component-based and utilize occupancy-driven pharmacology (MOA), which inhibits protein function for a short period of time to temporarily alter it. By utilizing an event-driven MOA, the proteolysis-targeting chimeras (PROTACs) technology introduces a revolutionary tactic. Small-molecule-based heterobifunctional PROTACs hijack the ubiquitin-proteasome system to trigger the degradation of the target protein. The main challenge PROTAC's development facing now is to find potent, tissue- and cell-specific PROTAC compounds with favorable drug-likeness and standard safety measures. The ways to increase the efficacy and selectivity of PROTACs are the main focus of this review. In this review, we have highlighted the most important discoveries related to the degradation of proteins by PROTACs, new targeted approaches to boost proteolysis' effectiveness and development, and promising future directions in medicine.

Abstract B039: BIO-PROTAC: Application of cell penetrating scFv to treat undruggable KRAS mutant cancer

Abstract Activation of mutations in RAS has been found in high ratio in human cancers, inducing downstream critical effectors corresponding tumorigenesis. In recent years, RAS-RAF-ERK1/2 pathway is known as a crucial target for the anti-cancer drug development because of high prevalence of ERK activation in human cancers. The attempts in direct targeting to activated RAS, which is GTP bound, has been somewhat successful in the treatment of certain type of cancer, however, still beset by the resistance. Our aim is to develop inhibitor that cell-penetrating scFv (single-chain variable fragment) which targets mutated KRAS (mKBscFv; mutated KRAS binding scFv). The Fv fragment is the smallest unit composed of the variable region of heavy chain and light chain in an immunoglobulin molecule, that has a function of antigen-binding activity. The scFv can specifically bind to an antigen, thereby reducing side effects of non-specific binding seen in chemical drugs. However, due to the lack of cell penetrating ability of scFv, a delivery carrier is often required. In this study, the mKBscFv was measured binding affinity toward wild type KRAS and mutated KRAS using surface plasmon resonance (SPR). The scFv has higher affinity to mutated KRAS than wild type KRAS. A cell-penetrating peptide (CPP) was developed for drug delivery and was expressed at the C-terminus of mKBscFv for transferring cells. The mKBscFv-CPP was tagged with His tag to express in CHO cells, which was purified by FPLC. The purity of mKBscFv-CPP was confirmed by SDS PAGE and immunoblotting. The mKBscFv-CPP treated KRAS mutated cancer cells decreased cell viability in a concentration-dependent manner, and decreased expression of mutated GTP-bound KRAS. In addition to the bioactivity of the mKBscFv, it has further advantage as a proteolysis-targeting chimera (PROTAC). The plasmid DNA was prepared by adding a VHL-expressing sequence to the C-terminus of mKBscFv (mKBscFv-Vh). This gene was transfected into KRAS mutated cancer cells to express the protein, and as a result mutated GTP-bound KRAS was reduced. A CPP peptide domain was added to the C-terminus of this gene to express it as a protein in CHO cells. The mutated GTP-bound KRAS was reduced by mKBscFv-Vh-CPP in KRAS mutated cacner cells. Taken together, mKBscFv that binds to mutated KRAS was developed, and it can be expected to become a new protein anticancer drug effective against mutated KRAS-mediated cancer cells by fusing cell penetrating peptide and PROTAC technology. Citation Format: Gookjin Yoon, Beom Soo Jo, Dong Woo Lee, Jinwook Yang, Min-Ho Park, Sanghui Seok, Jue Yeon Lee, Chong Pyoung Chung, Yoon Shin Park, Yoon Jeong Park. BIO-PROTAC: Application of cell penetrating scFv to treat undruggable KRAS mutant cancer [abstract]. In: Proceedings of the AACR Special Conference: Targeting RAS; 2023 Mar 5-8; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Res 2023;21(5_Suppl):Abstract nr B039.

Proteolysis Targeting Chimera (PROTAC) as a promising novel therapeutic modality for the treatment of triple-negative breast cancer (TNBC).

Breast cancer (BC) is considered one of the most prevalent malignancies impacting women worldwide, constituting 15% of all new cancer cases. It is classified according to its molecular targets into three subtypes; HR+/ERBB2-, ERBB2+/HR+, or HR- and triple-negative breast cancer (TNBC). TNBC is considered aggressive cancer with bad prognosis and poor clinical outcomes. It lacks estrogen, progesterone, and ERBB2 receptors rendering its treatment more challenging. Owing to its unresponsiveness to hormonal therapy, quick tumor growth, and the high probability to have spread at the time of discovery, it is more likely to recur following therapy. Proteolysis Targeting Chimeric molecules (PROTACs) are hetero-bifunctional molecules that are able to hijack the ubiquitin-proteasome system, a major physiological proteolytic mechanism. This leads to ubiquitination through endogenous E3 ligases and subsequent degradation through 26-S proteasome. Since its discovery in 2001, PROTACs have been considered an important therapeutic modality due to their ability to target and degrade undruggable proteins. In vitro studies have been conducted to investigate the possibility of using PROTACs as a therapeutic modality in TNBC. Data available propose great potential of PROTACs technology as a major candidate in TNBC management. Further in vitro and in vivo clinical trials are required to establish a definitive decision. In this review, we aim to give a brief overview of TNBC and PROTACs and highlight the rationale behind using PROTACs as a therapeutic modality in patients with TNBC.