Unlocking the “undruggable”: current landscape and emerging frontiers in lysosomal receptor-mediated protein degradation

Abstract

Extracellular and membrane-associated proteins are essential in signal transmission, immunological control, and disease pathogenesis; nonetheless, their ‘undruggable’ characteristics have historically impeded drug discovery. The targeted protein degradation (TPD) technologies provide innovative solutions to address this dilemma. Despite the rapid advancement of techniques such as Proteolysis-targeting chimera (PROTACs) that utilize the Ubiquitin-proteasome system (UPS), their applicability is limited to intracellular proteins. Lysosome-targeting chimeras (LYTACs), utilizing the endocytosis-lysosomal route, facilitate the selective degradation of secreted and transmembrane proteins, thereby considerably broadening the target spectrum of TPD. Since its inception in 2020, the LYTAC platform has consistently progressed, incorporating several Lysosome-targeting receptor (LTR) targeting techniques and innovative delivery vehicles, including aptamers, peptides, and nanoparticles. It has exhibited promise in oncology, neurological conditions, and immune-mediated disorders. Nevertheless, LYTAC encounters several obstacles, such as intricate ligand design, potential immunogenicity, inadequate tissue selectivity, and restricted clinical validation. Platforms and tactics designed to improve degrading efficiency, broaden disease applicability, and facilitate clinical translation signify interesting research avenues in this domain. This paper presents a thorough evaluation of the research advancements and application potential of LYTAC technology, while examining significant limitations and future direction of development.

Graphical abstract

1. Introduction

Proteins are fundamental molecules in biological processes, fulfilling many roles such as preserving cellular structure, modulating signal transduction, and conducting metabolic activities (Pawson and Scott 1997; Noormohammadi et al. 2018). Disruption of protein homeostasis often results in numerous diseases, including cancers, neurological disorders, and immunological dysregulation (Sonninen et al. 2020; Chen et al. 2023). Thus, targeting proteins associated with diseases is an essential method in contemporary medicine. Existing therapeutic strategies predominantly depend on small-molecule inhibitors that necessitate stable binding to distinct three-dimensional configurations (e.g. ‘pockets’) of target proteins to achieve their effects (Hopkins and Groom 2002). Consequently, despite therapeutic advancements in specific diseases, around 80% of proteins within the human proteome (including scaffold proteins, transcription factors, secreted proteins, and transmembrane receptors) pose significant challenges for targeting with high-affinity inhibitors due to their flat structures or absence of ‘pocket’ conformations. These are referred to as ‘undruggable proteins’ (Overington et al. 2006).

Targeted protein degradation (TPD) is an innovative strategy that utilizes the cell's own protein degradation mechanisms to facilitate the destruction of disease-associated proteins in the proteasome or lysosomes. Strategies reliant on the Ubiquitin-proteasome system (UPS), such as Proteolysis-targeting chimera (PROTACs), have progressed significantly in the last twenty years, with multiple compounds advancing to clinical trials (Sakamoto et al. 2001). Nonetheless, UPS-mediated degradation is confined to intracellular proteins. Approximately 40% of human proteins are challenging to target with UPS methodologies due to their encoded gene products being extracellular or membrane-bound (Uhlén et al. 2015).

In this context, researchers have focused on another vital cellular disintegration pathway: lysosomes. Lysosomes not only eliminate cytoplasmic constituents through the autophagy-lysosome pathway but, more significantly, destroy extracellular secretions and transmembrane proteins via the endocytosis-lysosome system (Saftig and Klumperman 2009). Utilizing this feature could greatly extend the target range of TPD technologies. The Lysosome-targeting chimeras (LYTACs) developed by the Bertozzi team in 2020 marked a substantial progression in this field (Banik et al. 2020). Their core principle entails the conjugation of a target protein binder with a lysosome-targeting ligand. By utilizing LTR, Cation-independent mannose-6-phosphate receptor (CI-M6PR)/Insulin-like Growth Factor 2 Receptor (IGF2R) on the cell membrane, LYTACs direct extracellular or membrane-associated target proteins into the endocytic pathway for subsequent degradation in lysosomes. LYTAC facilitates the destruction of challenging Protein of interest (POIs) by this mechanism, targeting LTRs on the cell membrane surface. This technique allows LYTACs to effectively eradicate targets that are extracellular or membrane-bound proteins, which are typically challenging to access using traditional methods, such as Epidermal Growth Factor Receptor (EGFR), Programmed death-ligand 1 (PD-L1), CD71, and ApoE4.

As research progresses, the applicability of LYTAC technology continues to broaden. Researchers have devised methods, including KineTAC (Pance et al. 2023), GalNAc-LYTACs (Ahn et al. 2021), ITACs (Zhou et al. 2024), DENTAC (Zhu et al. 2023), eHSPTACs (Zhang et al. 2025b), GLP-1-LYTACs (Zhu et al. 2023), FRTACs (Zhou et al. 2024), TfR-LYTAC (Su et al. 2024), GLTACs (Fang et al. 2025), and MedTAC (Chang et al. 2025), to accomplish precise cellular and tissue targeting, each designed to target distinct LTRs. Modifications to the surfaces of conjugates and the integration of aptamers, nanoparticles, and peptide molecules have augmented transport efficiency and boosted pharmacokinetic characteristics. Moreover, researchers are investigating the optimization and reconfiguration of LYTAC molecular structures, offering methodologies for the manipulation of extracellular proteins and membrane receptors in foundational research. The integration of LYTAC technology with diverse disease therapies has broadened opportunities for clinical use and intervention, showcasing considerable promise in tumor immunotherapy, metabolic disorders, and neurodegenerative illnesses.

Notwithstanding its optimistic prospects, this nascent strategy encounters obstacles in immunogenicity, pharmacokinetics, synthetic adaptability, tissue/cell specificity, delivery and degradation efficacy, and clinical translational viability. Complex structural configurations frequently undermine stability and manufacturing processes, while the dynamic balance between target binding and receptor recruitment is not fully elucidated, and variations in receptor distribution across diverse tissue microenvironments may jeopardize specificity. Simultaneously, the systematic confirmation of long-term safety and immunotolerance remains unattained, creating doubts over LYTAC's translational applicability. Nonetheless, continuous improvements in molecular engineering, delivery mechanisms, and receptor biology are systematically surmounting these obstacles. It is anticipated that, with advancing research, LYTAC and its derivative techniques will become increasingly effective instruments for TPD.

This review provides a systematic evaluation of LYTACs from the perspective of technological evolution and shifting design paradigms. We first summarize the foundational contributions of diverse LTRs and ligand modalities, including antibodies, peptides, aptamers, and small-molecule ligands, which have collectively expanded the degradable proteome and established the molecular and structural basis of LYTAC technology. Building upon this foundation, we further compare distinct LYTAC platforms in terms of delivery format, tissue or cell specificity, degradation performance, and safety-related features, thereby delineating their respective strengths and limitations across different biological contexts. The central novelty of this review lies in highlighting that the field has reached a critical inflection point, transitioning from proof-of-concept studies toward clinical translation, a shift that is driving LYTAC design from static molecular construction toward integrated therapeutic systems emphasizing functional logic, spatiotemporal control, and programmability.

In contrast to prior reviews that primarily focus on molecular architectures or platform categorization, this work addresses a translationally critical yet underexplored question: how appropriate LYTAC platforms can be selected and engineered according to specific disease contexts and pathological environments. By examining the differential applicability of various LYTAC strategies across oncology, inflammatory disorders, and neurodegenerative diseases, this review underscores the importance of aligning platform characteristics with disease biology to achieve optimal efficacy and safety. Moreover, we dissect emerging solutions such as logic-gated regulation, reversible supramolecular assembly, disease-microenvironment-responsive delivery and activation, and multi-layered proteostasis control strategies that collectively address key translational bottlenecks, including off-target toxicity, receptor saturation kinetics, and instability in complex in vivo settings. Through this integrative analysis, the review aims to provide actionable design principles and a translational roadmap for the development of next-generation, drug-like LYTAC degraders.

2. Development of LYTAC technology based on CI-M6PR/IGF2R

2.1. Origin and fundamental principles of LYTAC technology

The family of cell surface LTRs has been documented to assist in the transport of proteins to lysosomes (Coutinho et al. 2012). In 2020, the Bertozzi team initially developed a chimeric chemical that could concurrently attach to cell surface LTRs and extracellular proteins. This chemical facilitates the internalization and degradation of target proteins within lysosomes, offering a natural mechanism for the clearance of membrane-bound or extracellular proteins; the initial LYTACs were designated as LYTAC. The fundamental composition of LYTAC comprises a small molecule or antibody conjugated to a chemically produced glycopeptide ligand, functioning as an agonist for lysosomal shuttle receptors. The CI-M6PR is the most representative LTR in this approach, as it identifies N-glycan proteins with Mannose-6-phosphate (M6P) residues and facilitates their transport to lysosomes (Ghosh et al. 2003). At the acidic pH of lysosomes, the protein detaches from the receptor and is subjected to lysosomal destruction, whereas CI-M6PR perpetually circulates among endosomes, the cell membrane, and the Golgi apparatus for recurrent use (Gauthier et al. 2024). In contrast to current technologies, LYTAC can degrade both secreted and membrane-associated proteins (Sakamoto et al. 2001) without dependence on external proteases (Alon et al. 1993). The benefits, such as chemical tunability and modular assembly, provide an innovative method for the selective degradation of secreted and membrane proteins, showcasing considerable promise in fundamental research and therapeutic applications for diseases. Experimental validation confirms that the LYTAC platform can engage with a variety of target proteins, encompassing small molecules to large peptides, by directly degrading therapeutically significant proteins such as apolipoprotein E4 (ApoE4), EGFR, CD71, and PD-L1 (Banik et al. 2020) (Figure 1).

Figure 1.

The LYTACs concept, wherein the CI-M6PR glycopeptide ligand associates with antibodies to facilitate the transport of released membrane-associated proteins into lysosomes. Reprinted with permission from Banik et al. (2020). Copyright 2020, Springer Nature.

2.2. M6P ligand-driven LYTAC technology

M6P serves as a crucial signal for lysosomal hydrolases by specifically recognizing and binding to CI-M6PR, thus facilitating lysosomal-targeted transport (Kornfeld 1992). By examining the cellular mechanisms and regulatory elements that control M6P-mediated POI degradation as a ligand, and by systematically creating and changing ligands, innovative strategies can be formulated to improve and progress conventional LYTAC technology.

2.2.1. Improvements in synthesis procedures and raw materials

Banik et al. pioneered the application of antibodies as POI ligands for binding to polyM6Pn in 2020, hence laying the foundation of LYTAC technology. The NCA polymerization synthesis of PolyM6Pn is intricate, produces extremely diverse products, and may provide immunogenicity hazards, hence constraining molecular characterization and clinical applications (Banik et al. 2020). Researchers have offered many solutions to solve these difficulties. Wang's team employed a chemical-enzymatic method using Endo-S/Endo-S2 to site-specifically and directly attach high-affinity M6P polysaccharides to antibodies, resulting in uniform antibody-M6P conjugates. This circumvented protein engineering or the incorporation of non-native structures (Zhang et al. 2022b) (Figure 2a). Mukai's team modified the glycosylation site by substituting Asn297 with Asn298, resulting in a high degree of sialylation. This facilitated the direct attachment of synthetic M6P glycan (bisM6P) and the effective internalization of soluble proteins upon interaction with Fc-engineered antibodies (Mukai et al. 2024). The Tang team developed a modular LYTAC that recruits M6PR, incorporating multivalent M6Pn alterations on a short peptide backbone by advanced chemical modifications. Phosphate ester analogues and thiol-ene reactions were utilized to enhance stability and streamline synthesis, with the tetrameric structure exhibiting excellent degradation efficacy (Stevens et al. 2023) (Figure 2b). Kim et al. created LYTACgyM6pG by conjugating yeast-derived M6pG to a PD-L1 nanobody by copper-free click chemistry, resulting in improved biocompatibility and increased lysosomal targeting (Kim et al. 2025b) (Figure 2c). Luan's team created CL8-M6P3 by amalgamating the Connective tissue growth factor (CTGF)-targeting peptide CL8 with the innovative glycopeptide scaffold M6P3 to facilitate CTGF breakdown, and subsequently advanced NanoCLY nanoparticles to improve stability and targeting (Lin et al. 2025b).

Figure 2.

Schematic representation of structural optimization and mechanistic investigations for M6P-ligand-mediated LYTAC. a, Chemically engineered glycosylation remodeling produces homogeneous antibody-M6P conjugates for functional applications. Reprinted with permission from Zhang et al. (2022). Copyright 2022, American Chemical Society. b, The Modular M6PR recruits LYTAC, improving synthesis efficiency and stability. Reprinted with permission from Stevens et al. (2023). Copyright 2023, American Chemical Society. c, Schematic representation of the mechanism of LYTAC^gyM6pG. Reprinted with permission from Kim et al. (2025). Copyright 2025, American Chemical Society. d, Identification of biological factors for LYTAC-facilitated degradation of membrane proteins. Reprinted with permission from Ahn et al. (2023). Copyright 2023, The American Association for the Advancement of Science. e, Impact of intracellular ATP concentrations on the efficacy of extracellular protein degradation during the degradation process. Reprinted with permission from Ning et al. (2025). Copyright 2025, American Chemical Society.

2.2.2. Mechanisms and determinants of target protein degradation

Ahn et al. conducted a genome-wide Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) knockout screening combined with proteomics analysis to elucidate the mechanisms and influencing factors of CI-M6PR-based LYTAC in the degradation of membrane proteins, uncovering a novel mechanism of cell surface receptor occupation and transport: (1) The neddylation modification of Cullin-3 (CUL3) is essential for the development of the LYTAC complex into lysosomes and acts as a predictive biomarker for cellular vulnerability to degradation; (2) The cell surface CI-M6PR, as a representative LTR, is generally occupied by endogenously M6P-modified glycoproteins. Consequently, inhibiting M6P biosynthesis amplifies the availability of receptors on the cell membrane, thereby augmenting LYTAC's targeted degradation efficacy; (3) Before the dissociation of the LYTAC-receptor complex, the reverse transposition complex recycles the complete LYTAC-CI-M6PR complex from the endosome to the cell surface. Disabling genes associated with the Retromer Complex obstructs this competitive recycling mechanism, thereby improving the efficacy of LYTAC-mediated degradation. Ahn et al. established that the propensity for internalization of soluble cargo is associated with the expression levels of CI-M6PR on the cell surface, although it shows no significant link with the efficiency of membrane protein breakdown. This indicates that the regulatory variables controlling membrane protein absorption and degradation are not the same, implying possible variations in the mechanisms underlying these two activities. This discovery has considerable implications for lysosome-targeting TPD technologies and other therapeutic techniques reliant on cell surface receptors, such as enzyme replacement therapy and antibody-drug conjugates (Ahn et al. 2023)(Figure 2d).

In addition to clarifying essential chemical pathways, the dynamic observation of crucial intracellular components during degradation is also critical. ATP functions as the principal energy source for cellular activities, whilst lysosomes act as significant ATP stores. Expanding on this, Liu's team incorporated PDGF aptamers, ATP-responsive probes, and IGF2R ligands into a DNA framework to create multifunctional TDF-LYTACs. By integrating these with an ATP-sensing aptamer probe activated by the APE1 enzyme, scientists accomplished real-time imaging of intracellular ATP concentrations during protein degradation via APE1-mediated fluorescence recovery of the ATP probe. This work initially showed a positive association between extracellular protein degradation efficiency and ATP levels: elevated ATP levels markedly boost degradation efficiency, whereas diminished ATP levels impede the degradation process. This serves as a crucial reference for formulating disease treatment methods centered on the lysosomal pathway (Ning et al. 2025) (Figure 2e).

2.3. IGF2 peptide ligand-driven LYTAC technology

Although various structurally defined M6PR ligand modification strategies have been reported, they are constrained by protracted procedures, intricate and inconsistent conjugation architectures, and non-genetic encoding challenges. Nonetheless, the CI-M6PR/IGF2R binding domain 11 can also facilitate binding to non-glycosylated Insulin-like growth factor 2 (IGF2) (Brown et al. 2007). The conjugation of these peptides to antibodies that target specific proteins and their subsequent expression could substantially enhance the development of IGF2R-based LYTAC medicinal applications.

2.3.1. ILYTAC: the initial IGF2R-targeting approach concerning IGF2 fusion proteins

Zhang et al. first documented a collection of IGF2-fused recombinant proteins known as iLYTACs. The dual-function iLYTACs are entirely genetically encoded and may be efficiently produced within days using normal cloning and bacterial expression, without requiring any chemical changes. The two developed iLYTAC variants effectively and efficiently degraded many disease-related protein targets, including EGFR, PD-L1, αSyn, and CD20, thereby broadening the applicability of current LYTAC technology. In comparison to conventional LYTAC, iLYTAC presents several advantages: (1) Small molecular weight (16-22 kDa) and economical as a recombinant protein, facilitating its application as a ‘plug-and-play’ toolkit platform; (2) EGFR degradation prompted by both iLYTAC variants exhibited enhanced antitumor efficacy in murine models relative to Cetuximab (Cet) monotherapy, indicating innovative strategies for integrating iLYTAC with monoclonal antibodies to improve cancer treatment results. While iLYTAC is compatible with E. coli expression methods, protein production necessitates refolding or reconstitution, presenting obstacles for future large-scale manufacturing. The present degradation efficiency is inferior to that of particular LYTAC reagents, perhaps attributable to the misfolding of specific IGF2 fusion proteins, and has unsatisfactory pharmacokinetic characteristics in vivo. The iLYTAC technology ultimately depends on wild-type IGF2, which could stimulate the tyrosine kinase activity of IGF1R, hence presenting possible safety concerns (Zhang et al. 2023) (Figure 3a).

Figure 3.

IGF2 Peptide-Ligand-Driven LYTAC Technology and Derivative Platforms. a, Schematic of two types of fully genetically encoded iLYTACs for degrading POIs. Reprinted with permission from Zhang et al. (2023). Copyright 2023, American Chemical Society. b, Targeting and degrading transmembrane PD-L1 using IGF2 peptide-based and protein-only LYTAC compounds. Reprinted with permission from Mikitiuk et al. (2023). Copyright 2023, Multidisciplinary Digital Publishing Institute. c, Schematic of fully genetically encoded GELYTAC structure and POI degradation process. Reprinted with permission from Yang et al. (2024). Copyright 2024, Proceedings of the National Academy of Sciences of the United States of America.

2.3.2. IGF2 ligand-mediated LYTAC optimization and novel derivative platforms

To overcome the limitations of conventional LYTAC, such as intricate chemical changes and the risk of oncogenic signaling via wild-type IGF2 activation of IGF1R (Pandini et al. 2002), several teams have suggested enhancements. The group led by Mikitiuk developed a pure-protein LYTAC utilizing non-glycosylated IGF2 peptides, facilitating selective interaction with IGF2R. This markedly improved specificity and precision while mitigating potential negative effects from high IGF1R activation (Mikitiuk et al. 2023) (Figure 3b). Expanding upon previous IGF2 mutant research (Alvino et al. 2009), Pan's team developed sLYTAC with an engineered IGF2-M5.6 fusion antibody that selectively targets IGF2R, facilitating the effective degradation of Human epidermal growth factor receptor 2(HER2) and EGFR. This sLYTAC can be directly fused and expressed in mammalian cells, facilitating simpler preparation than chemically modified LYTAC methods. This method effectively degrades both homodimers and heterodimers of tumor-associated targets (e.g. HER2 homodimers, HER2/EGFR, and HER2/HER3 heterodimers), hence bypassing resistance due to bypass signaling activation or epitope masking. This method exhibited substantial tumor growth inhibition in animal studies (Pan et al. 2025).

To rectify the inadequate pharmacokinetics and restricted large-scale manufacture of initial iLYTACs, Jonathan's team developed an entirely genetically encoded GELYTAC. Consisting of a minor protein binder and an evolved variation of IGF2, it specifically targets extracellular mCherry, TGF-β, and the shedding extracellular domain of the IL-6 receptor, and can be secreted by human primary T cells. The modular characteristics of GELYTAC facilitate the humanization or substitution of linkers or nanobodies to diminish immunogenicity and promote swift clearance from non-target settings. The advantage of its genetic encoding also promotes integration with gene therapy approaches, such as mRNA or viral vectors (Yang et al. 2024) (Figure 3c). The IGF2-tagged aptamer chimeras (ITACs) created by the Dahan team effectively degrade overexpressed pathogenic membrane proteins, highlighting the critical influence of IGF2R levels on degradation efficiency, optimal degradation is achieved at moderate cell surface IGF2R levels, whereas excessively high or low levels diminish efficiency (Tian et al. 2024).

3. Investigation of LYTAC technology for tissue- and cell-specific LTRs

The CI-M6PR, the early-stage lysosomal receptor targeting cell membranes, has a deficiency in tissue selectivity (Kornfeld 1992), hence constraining the tissue and cellular specificity of its target protein breakdown. Researchers are developing tissue- or cell-specific LTRs, such as Asialoglycoprotein receptor (ASGPR), cytokine receptors, Integrins, Scavenger receptor (SR), Low-density lipoprotein receptor-related protein 1(LRP-1), Glucagon-like peptide-1 receptor (GLP-1), Glucose Transporter (GLUT1), Folate receptor(FR), Transferrin receptor (TfR), Glypican-3 (GPC3) receptor, and sortilin, to achieve precise lysosomal degradation of specific cell membrane and extracellular proteins in tumors, thereby enhancing the specificity of LYTAC-mediated degradation.

3.1. ASGPR: hepatocyte-specific LTR

ASGPR is another well-defined LTR, unlike CI-M6PR, it is highly expressed in hepatocytes (Spiess 1990). The trivalent GalNAc ligand, characterized by a 15-20 A distance between sugars, demonstrates the best binding affinity and endocytosis efficiency among galactose ligands interacting with ASGPR (Lee et al. 1983). ASGPR facilitates the transport of glycoproteins to lysosomal breakdown through clathrin-mediated endocytosis, while ASGPR subsequently recycles to the plasma membrane (Stockert 1995). The distinctive tissue expression profile and swift turnover rate (about 15 minutes) render ASGPR a compelling option for liver-specific TPD (Schwartz et al. 1982).

3.1.1. Preliminary development of ASGPR and factors regulating degradation efficiency

ZHOU and his team coupled the ASGPR ligand tri-GalNAc with biotin, antibodies, or antibody fragments to create a new category of degraders. They preliminarily demonstrated the feasibility of ASGPR-mediated hepatocyte-specific TPD techniques by targeting NA and EGFR. The research demonstrated that increased levels and amounts of tri-GalNAc on antibodies augmented their internalization ability. For tri-GalNAc-Ab conjugates, reduced molecular weights were associated with enhanced absorption of the POI. Moreover, neither the process of complex formation nor the effectiveness of internalization served as rate-limiting factors for protein uptake (Zhou et al. 2021) (Figure 4a). The Bertozzi team integrated a POI-targeting ligand with the tri-GalNAc motif to create GalNAc-LYTACs, confirming their effectiveness by degrading EGFR and HER2. They developed a small-molecule polyspecific integrin-binding peptide (PIP) that generates the targeted ligand PIP-GalNAc upon interaction with tri-GalNAc, markedly improving the inhibitory effects on hepatocellular carcinoma cell proliferation. This illustrates that the structural design of LYTAC can be condensed into compact conjugates. Additionally, through the systematic alteration of modification sites and GalNAc/antibody ratios via antibody engineering, site-specific GalNAc-LYTACs were produced, enhancing their in vivo degrading efficacy and pharmacokinetics while ensuring safety during repeated administration (Ahn et al. 2021) (Figure 4b).

Figure 4.

LYTACs achieved cell-specific targeting and degradation of protein via ASGPR. a, Degradation of EGFR and NA using Tri-GalNAc-antibody and Tri-GalNAc-biotin. Reprinted with permission from Zhou et al. (2021). Copyright 2021, American Chemical Society. b, GalNAc-LYTACs hijack liver-specific ASGPR for targeted delivery to hepatocytes. Reprinted with permission from Ahn et al. (2021). Copyright 2021, Springer Nature. c, Mechanism of action of the MoDE-A bifunctional molecule. Reprinted with permission from Caianiello et al. (2021). Copyright 2021, Springer Nature. d, Rapid, ASGPR-dependent clearance of targets achieved using bispecific antibodies, antibody-drug conjugates, and small molecules with diverse bispecific constructs. Reprinted with permission from Bagdanoff et al. (2023). Copyright 2023, Elsevier.

To further investigate the effects of different glycoconjugates on ASGPR-mediated protein degradation, Donahue et al. utilized a chemoenzymatic Fc glycan remodeling technique (Zhang et al. 2022b) to swiftly produce site-specific antibody-ligand conjugates with unique ASGPR ligands. The conjugates markedly diminished circulating PCSK9 and membrane-bound EGFR levels, with the characteristics of the glycan-based ligands and the length of the conjugation spacer being essential for the degradation efficacy of the proteins of interest (POIs). The hook effect was exclusively detected in antibody conjugates with synthetic tri-GalNAc cluster ligands, and not in LYTACs featuring natural triantennary complex-type N-glycans. This indicates that the two ligand types may engage in different interaction mechanisms during receptor binding and target protein degradation, necessitating more mechanistic exploration (Donahue et al. 2023).

3.1.2. In vivo application studies of ASGPR-mediated LYTAC

The team, headed by Caianiello, created and verified the modular bifunctional synthetic chemical MoDE-As in vivo. The MoDE-A molecule consists of three domains: an ASGPR-binding motif, a polyethylene glycol spacer, and a target protein-binding motif. D-MoDE-A and M-MoDE-A facilitated the degradation of α-DNP and MIF, respectively, exhibiting effectiveness across diverse target protein concentrations and dosing schedules in mice, with favorable tolerability. This method reduced the likelihood of autoimmune reactions against target proteins (Caianiello et al. 2021) (Figure 4c). Bagdanoff et al. developed various heterobifunctional constructs facilitating lysosomal degradation of PCSK9 in murine models, encompassing bispecific antibodies, antibody-drug conjugates, and small molecule-ligand conjugates. Despite the use of intravenous administration in this research, the ever-reduced complex structures indicate the potential for the development of orally accessible heterobifunctional molecules. In contrast to the MoDE-As paradigm, the heterobifunctional compounds induced swift and significant elimination of circulating PCSK9 after a single in vivo administration, highlighting the promise of small-molecule-based strategies (Bagdanoff et al. 2023) (Figure 4d).

To optimize drug delivery, Dai's team leveraged peptide modification and self-assembly properties. Utilizing solid-phase peptide synthesis, they formulated the amphiphilic glycopeptide Lauryl-P3GKS(GalNAc), wherein hydrophilic lysine residues offer effective cross-linking sites, while the modified GalNAc guarantees particular affinity for ASGPR. These peptides autonomously aggregate in aqueous solutions to create stable, size-uniform nanospheres measuring around 200 nm. Conjugating the nanospheres with anti-CD24 antibody produces Nanosphere-AntiCD24, which inhibits the CD24/Siglec-10 signaling pathway. Moreover, the incorporation of Glucose Oxidase (GOx) into the hydrophobic domain of the peptide inhibits tumor proliferation in xenograft murine models (Wang et al. 2023a). Wang's team reported genetically engineered bispecific exosomes (LYTEXs) that promote lysosomal degradation of membrane-associated therapeutic targets, including GFP, HER2, and PD-L1, by targeting ASGPR. Repeated in vivo investigations indicated that biGEXs localize at tumor locations and efficiently impede tumor cell proliferation. This technology may be easily adapted to target various membrane-associated proteins by co-expressing recognition modules with affinity segments of lysosomal sorting proteins (Wang et al. 2023c).

ASGPR-based LYTAC technology has also demonstrated utility in tumor immunomodulation. Li et al. developed a small-molecule-conjugated LYTAC degrader, JW-9, which engages ASGPR through a trivalent GalNAc ligand and incorporates the heparanase inhibitor OGT2115. JW-9 effectively degrades secreted heparanase in the tumor microenvironment, thereby preserving heparan sulfate proteoglycans and increasing the surface expression of ligands for natural killer cell-activating receptors. In hepatocellular carcinoma models, JW-9 treatment markedly enhanced NK cell-mediated tumor recognition and cytotoxicity, illustrating the potential of ASGPR-targeting LYTACs to reverse immunosuppressive niches and potentiate cellular immunotherapy (Li et al. 2024).

3.2. Developing novel LYTAC strategies using other LTR receptors

Following the development of degradation strategies targeting cell membrane and extracellular proteins via LTRs like CI-M6PR and ASGPR, researchers have turned their attention to other LTRs mediating endocytic degradation, such as integrins, transferrin receptors, and folate receptors. This aims to develop novel LYTACs, thereby expanding the technology's application scope.

3.2.1. Cytokine receptors

Pance's team created KineTACs, a specialized chimeric system employing cytokine receptors as LTRs. KineTACs utilize a human antibody scaffold that is entirely genetically encoded and may be produced without intricate chemical synthesis or bioconjugation. KineTACs loaded with CXCL12, CXCL11, or vMIPII effectively engage the C-X-C Motif Chemokine Receptor 7 (CXCR7) internalization route for lysosomal degradation, demonstrating minimal off-target effects. This platform is relevant to several therapeutically significant cell surface proteins, including HER2 and EGFR, as well as tumor-associated membrane proteins CDCP1, TROP2, and PD-1. It also targets soluble extracellular proteins, such as Vascular endothelial growth factor (VEGF) and Tumor Necrosis Factor alpha (TNF-α), showcasing extensive adaptability. Research indicates that factors beyond antibody-POI binding affinity, binding epitope, structural design, and LTR-to-target protein ratio, such as signaling capacity, CXCL12 variant affinity for CXCR7, N297 glycosylation status of the Fc region, and pH dependency of the target protein, also significantly influence degradation efficiency (Pance et al. 2023) (Figure 5).

Figure 5.

Schematic of validated LTRs with TPD function and corresponding LYTAC technologies. (The figure was created by the authors).

3.2.2. Integrins

Integrin αvβ3 (ITGA3B1) is a heterodimeric receptor that is prominently expressed in numerous tumor cells. It engages in angiogenesis and tumor advancement via interactions with the extracellular matrix and cytoskeleton, affecting processes like cell migration and proliferation (Hamidi et al. 2016). Research demonstrates that integrins are modulated within the endocytosis-lysosomal degradation pathway according to cellular conditions and external stimuli (Caswell and Norman 2006). Therefore, employing ITGA3B1 as an LTR presents opportunities for advancement as a TPD technology.

He's team developed the first integrin-mediated TPD technology, known as the Integrin-mediated lysosomal degradation (IFLD) approach. The bifunctional molecule BMS-L1-RGD was synthesized by conjugating the target protein-binding domain BMS-8 with the highly stable, hydrophilic biotin-cRGD, serving as the integrin-binding domain. BMS-L1-RGD effectively degraded PD-L1 and showed substantial in vivo tumor reduction in murine models (Zheng et al. 2022) (Figure 5). Following the IFLD approach, Zhou's team generated innovative integrin-targeted chimeric antibodies (ITACs) through the conjugation of cRGD peptides with antibodies. In comparison to normal cells, ITACs exhibited superior degradation efficiency for proteins, including biotin-647 and EGFR in cancer cell lines. Moreover, the parameters affecting ITAC degradation of POIs were methodically examined: for membrane proteins such as EGFR, extended linkers increased degradation efficiency by enhancing complex flexibility and spatial orientation; conversely, for soluble proteins, linker length had negligible influence (Zhou et al. 2024). To broaden the uses of the IFLD technique, his team devised a method to induce Carbonic Anhydrase IX (CAIX) degradation through the lysosomal pathway via integrin. This technique reduces intracellular pH in tumor cells and limits their proliferation under hypoxic settings. In a Phase Ib/II clinical trial, the degrading agent exhibited inhibitory action akin to the CAIX inhibitor SLC-0111, demonstrating commendable specificity, safety, and potential for application (Kim et al. 2025a). In addition to research utilizing c-RGD as an integrin ligand, Sun's team chose DML-7 as the integrin ligand to develop bispecific aptamer chimeras (ITGBACs) aimed at eradicating pathogenic membrane proteins such as CD71 and PTK7. This method markedly triggered cell cycle arrest and death, therefore suppressing tumor growth (Sun et al. 2024). Moreover, utilizing the synthetic simplicity, compact dimensions, and non-immunogenic properties of IFLD-based degraders, their integration with immune checkpoint ligands facilitates dual-target degradation. This method improves immune cell infiltration and cytotoxicity in malignancies, offering extensive therapeutic potential (He et al. 2025).

3.2.3. SR

SRs have elevated expression on neoplastic cells (Yu et al. 2015). Zhu's team initially showed that SRs can effectively function as LTRs to facilitate the lysosomal breakdown of membrane proteins. They introduced an innovative dendritic DNA chimera (DENTAC) method, which involves the chemical coupling of synthetic SR ligand dendritic DNA (PTDD) to a protein-binding moiety, therefore attaining chemical programmability and controllability. DENTAC consistently destroyed Nucleolin (NCL) across various cancer cell lines and confirmed the in vivo anticancer activity of N-DENTAC targeting NCL in mouse models of lung cancer (Zhu et al. 2023) (Figure 5).

SR-A, a subtype of scavenger receptor, is predominantly located on the surfaces of diverse immune cells (Abdul Zani et al. 2015). Wang's team suggested a non-covalent degrader design technique, employing the SR-A peptide ligand SRAL and the previously identified IL-17A-binding peptide (Wang et al. 2023b) to produce the lysosome-targeted co-assembled complex LYTACA, which facilitates lysosomal degradation of IL-17A or PD-L1. In murine models, LYTACA exhibited a significant reduction of psoriasiform symptoms and cutaneous inflammation in vivo. Moreover, LYTACA effectively degraded PD-L1 in A549 and HepG2 cells by targeting ASGPR via its interaction with a monovalent GalNAc ligand. This illustrates the scalability of the technique beyond the SR-A receptor, presenting specific benefits: accessible monovalent structures can enhance effects via co-assembly, facilitating successful receptor interactions that usually necessitate intricate multivalent ligands (Wang et al. 2024).

3.2.4. LRP-1

The Loppinet team developed a novel endocytosis pathway reliant on LRP-1 and transglutaminase 2 (TG2), manufacturing and confirming the effectiveness of a series of heterobifunctional compounds utilizing small-molecule ligands. These compounds selectively target systems abundant in active TG2 and exhibit elevated surface LRP-1 expression, demonstrating tissue selectivity by guiding POIs to lysosomes through the TG2/LRP-1 pathway. The successful applications of streptavidin, the vitamin B12 receptor, the cubilin receptor, and integrin αvβ5 were also validated (Loppinet et al. 2023) (Figure 5). Similarly, utilizing LRP-1, and taking into account the prolonged circulation time, tissue-targeting ability, and superior biocompatibility of platelets, the Hu team designed the first Platelet-delivered LYTAC technology (DePLTs), thereby introducing a live carrier and the ligand Heat Shock Protein 90 (HSP90) into the lysosome-dependent TPD system for the first time. Utilizing HSP90's interaction with LRP-1, they induced PD-L1 endocytosis and degradation, effectively elucidating the function of the extracellular HSP90-LRP-1 pathway in lysosomal degradation (Chen et al. 2025).

3.2.5. Extracellular heat shock protein 90 (eHSP90)

Expanding on the newly revealed HEMTAC technology (Li et al. 2022), Chen's team innovated the application of eHSP90 as a unique LTR in lysosomal degradation systems. They developed eHSPTACs, an innovative dual-functional small-molecule degradation approach, by combining eHSP90-binding ligands with POI ligands through linkers. This method efficiently facilitates the endocytosis and lysosomal degradation of extracellular AF488-labeled α-DNP antibodies and membrane-bound PD-L1 by forming a ternary complex (POI-eHSPTACs-eHSP90), while addressing the problem of free HSP90 release during eDePLT-mediated PD-L1 degradation via the lysosomal pathway. This method also addresses the problem of free HSP90 release during PD-L1 degradation by eDePLT. The PD-L1 degradation molecule dPDL1-4 specifically triggered T-cell responses and substantially suppressed tumor growth in B16F10 syngeneic animal models. Moreover, the elevated expression of eHSP90 in tumor cells resulted in eHSPTACs exhibiting markedly greater selectivity for tumor cells compared to normal cells (Zhang et al. 2025b) (Figure 5).

3.2.6. GLP-1R

Motivated by the distinctive cellular characteristics of GLP-1R, the Zhu team created a GLP-1R-based targeted degradation platform known as GLP-1-LYTACs. This approach utilizes click chemistry to bind GLP-1 with targeted moieties, including antibodies. GLP-1-LYTACs demonstrate remarkable adaptability and modularity, facilitating prolonged and effective GLP-1R-mediated degradation of model proteins (GFP), extracellular proteins (Neutravidin), and membrane proteins (EGFR and PD-L1). Notably, GLP-1-Ctx-induced EGFR degradation in HeLa and A549 cells demonstrated an absence of the ‘hook effect’ and also suppressed the activation of the EGFR/PI3K/Akt signaling pathway (Zhu et al. 2023) (Figure 5).

3.2.7. Glucose transporter (Glut1)

Glut1, which is abundantly expressed in tumor cells, enhances glucose transmembrane diffusion and transports different chemicals through endocytosis pathways (Mueckler and Thorens 2013). Utilizing this characteristic, Luo's team formulated the GFLD method employing Glut1 as a new LTR and found three glycopolymers as Glut1 ligands. Leveraging the benefits of glyco-oligomers (facile synthesis and adjustable monomer ratios, alongside the modifiability and high specificity of antibodies), they developed Ave-glyco-oligomer conjugates for the destruction of PD-L1. In a triple-negative breast cancer model with elevated PD-L1 expression, Ave-glc6 exhibited the most potent degrading capability. The research demonstrated that the reverse transcription complex facilitated the recycling and reutilization of Glut1 on the cell membrane (Luo et al. 2024) (Figure 5).

3.2.8. Folate receptor (FR)

FR are highly expressed in numerous cancer cells but rarely found in normal tissues (Leamon and Jackman 2008), presenting an opportunity for the targeted destruction of cancer-associated proteins within tumors. Zhou's team innovated the creation of easily obtainable folate receptor-targeting chimeras (FRTACs). FRTACs comprise a folate ligand that attaches to folate receptors and an antibody that identifies cancer-related targets. The utilization of readily accessible FR ligands presents considerable advantages in application compared to the intricate synthesis necessary for LTR ligands. In addition to established characteristics such as folate labeling efficiency and linker length, Zhou et al. identified that degradation efficiency is affected by many elements: For soluble extracellular proteins, degradation is closely correlated with FR expression levels; conversely, for endogenous membrane proteins, a greater FR-to-target protein expression ratio is essential for degradation efficiency. FRTACs facilitate the degradation of various protein targets both in vitro and in vivo, including mouse IgG, EGFR, PD-L1, and CD47, and they could significantly decrease PD-L1 levels in three murine tumor models, thereby successfully impeding tumor progression (Zhou et al. 2024) (Figure 5).

Subsequent investigations indicated that the low binding efficiency between FRTACs and their targets restricted the retention of FRTACs on those targets. Zhou's team subsequently found that folate demonstrates a greater nanomolar-level affinity for FRα, so addressing this constraint. By conjugating numerous folate moieties at different places on the antibody, they augmented the multivalent affinity effect, thus improving both the antibody-drug conjugation rate and receptor binding affinity. The engineered FRα-targeted FRTACs efficiently destroyed membrane proteins such as EGFR, TROP2, PD-L1, and HER2. FR-Ctx markedly reduced EGFR at doses as low as 0.1 nM, with no significant impact detected within the 500 nM range. Utilizing FRα overexpression in solid tumors, FRTACs exhibit robust in vivo PD-L1 degradation and stimulate CD8⁺ T cells, demonstrating markedly enhanced antitumor efficacy relative to traditional antibody treatments (Xiao et al. 2025).

3.2.9. TfR

The Su team developed a genetically designed chimeric TfR-LYTAC that targets lysosomes via TfR mediation. The TfR-LYTAC is entirely encoded by a single gene unit and facilitates PD-L1 degradation in many cancer cell types. To improve efficacy, the scientists advanced a tumor-targeting delivery system: by employing bacterial genetics, TfR-LYTAC was conjugated to ClyA, the predominant protein on the surface of bacterial outer membrane vesicles (OMVs), creating an innovative delivery platform: OMV-LYTAC. This technology integrates the PD-L1 degradation ability of TfR-LYTAC with the intrinsic anticancer and immune-stimulating properties of bacterial OMVs, which also confer prolonged half-life and enhanced tumor accumulation. In tumor mouse models, modified OMV-LYTAC mitigated several levels of immune cell depletion and markedly inhibited tumor growth (Su et al. 2024) (Figure 5).

Furthermore, in order to improve the controllability of genetically modified TfR-LYTAC for tumor treatment, Zhou's team created a smartphone-operated, low-temperature photothermal TfR-LYTAC platform. This system consists of two elements: engineered Escherichia coli MG1655@ICG, which possesses a temperature-sensitive genetic circuit that accumulates in hypoxic tumor areas and expresses TfR-LYTAC upon photothermal activation; and a smartphone-operated laser device that regulates a mild temperature of 42−45 °C through feedback control. This prevents skin damage from elevated temperatures (>60 °C) in traditional photothermal therapies and allows prolonged laser treatment (12 minutes), efficiently triggering PD-L1 degradation in melanoma and colon cancer models (Shi et al. 2025).

Gao's team developed a modular TfR-mediated LYTAC technology known as Pep-TACs that uses covalent peptides. This was accomplished by incorporating a lengthy flexible arylsulfonylfluoro group (k-ASF)-modified D-type peptide sequence alongside a covalently modified POI-binding peptide region. This design allows Pep-TACs to effectively bind in vitro experiments that replicate intricate tumor microenvironments (acidic pH, immune cells, and raised IFN-γ levels), attaining up to 91% PD-L1 degradation efficiency, thereby resolving the problem of inadequate PD-L1 residence time for lysosomal transport due to the restricted binding stability of short peptides (Xiao et al. 2025).

Targeting TfR1, which is highly expressed on rapidly proliferating cancer cells, Zhang's team developed TransTACs using protein engineering strategies. TransTACs utilize constitutive endocytosis, distinguishing themselves from numerous current degraders that depend on agonist-mediated internalization. This facilitates the effective degradation of membrane proteins, including CAR, PD-L1, EGFR, and CD20, wherein the divalent binding to TfR1 and geometric configuration markedly affect internalization effectiveness. TransTACs reversibly modify human primary Chimeric Antigen Receptor T cells (CAR-T) and elicit synergistic anticancer effects in mouse xenograft models via EGFR degradation and TfR1 suppression (Zhang et al. 2025a).

3.2.10. GPC3

GPC3 is overexpressed in more than 70% of hepatocellular carcinoma patients, but it is nearly absent in normal adult liver tissue, rendering it an optimal LTR given its high specificity (Haruyama and Kataoka 2016). Sheng's team created GPC3-targeted lysosomal chimeric GLTACs. These drugs facilitate endocytosis and degradation of membrane protein POIs, such as PD-L1, c-Met, and Fibroblast Growth Factor Receptor 1 (FGFR1), across several cell lines by generating a GPC3-GLTAC-POI ternary complex, while exhibiting low damage to normal cells. Yet, the advancement of GLTACs encounters numerous obstacles: ineffectiveness non cells lacking of GPC3 expression, potential immunogenicity and stability concerns, and absence of in vivo adverse effect validation in animal models (Fang et al. 2025) (Figure 5).

3.2.11. Sortilin

Sortilin's effective lysosomal transport capability and distinct expression profile render it an attractive ligand-targeted receptor for targeted treatment (Petersen et al. 1997). The Huang team suggested a new modular mRNA-encoded MedTAC method. Utilizing lipid nanoparticles (LNPs) to transfer mRNA encoding LYTAC allows the body's cells to produce the bispecific LYTAC molecule, which consists of a target protein-binding module and a Sortilin ligand module. This addresses the stability and delivery issues inherent in conventional LYTAC systems. MedTAC facilitates the fast and prolonged lysosomal degradation of membrane proteins such as PTK7, HER2, EGFR, and c-Met. MedTAC-PTK7 specifically targets PTK7-positive triple-negative breast cancer cells in vitro, resulting in considerable upregulation of proteins related to immunology, cell adhesion/migration, and metabolic control, while also modulating tumor immunological microenvironments. In a breast cancer mouse model, MedTAC-PTK7 exhibited advantageous pharmacokinetics and biosafety while markedly suppressing tumor growth (Chang et al. 2025) (Figure 5).

A consolidated comparison of representative LTR-based degradation platforms, including receptor usage, targeting features, delivery formats, and translational considerations, is provided in Table 1.

Table 1.

Master comparison of LTR-based degradation strategies.

Receptor	Tissue/Cell specificity	Canonical ligand	Example POIs degraded	Delivery form	In-vitro evidence	In-vivo evidence	Known limitations	Translational notes
CI-M6PR/ IGF2R	Ubiquitous expression	M6P glycan, IGF2	Membrane Proteins: EGFR, PD-L1, HER2, CD71, PTK7; Extracellular Proteins: CTGF, ApoE4.	1.M6P-based Chemical Conjugate 2. IGF2-based Fusion Proteins (iLYTAC/sLYTAC) 3. Cell-Mediated Delivery (GELYTAC)	Extensive degradation (often >80%) observed in Hep3B, Jurkat, MDA-MB-231, and BT549 cells. Evidence includes Western blot, flow cytometry, and confocal microscopy showing lysosomal colocalization.	1. Clearance of circulating proteins (e.g. Cetuximab) in BALB/c mice. 2. Significant tumor growth inhibition and TME remodeling in TNBC xenograft models via CTGF degradation.	1. Ligand Competition: High concentrations of endogenous M6P-glycoproteins compete for receptor binding. 2. Safety Concerns: WT-IGF2 binds to IGF1R, potentially promoting tumor growth (Mitogenic risk). 3. Synthesis: Complexity and potential immunogenicity of synthetic multivalent M6P glycans.	1. Safety Engineering: Use of mutant IGF2 (e.g. sLYTAC) to abolish IGF1R binding while maintaining IGF2R affinity. 2. Bioproduction: Utilizing glyco-engineered yeast for human-compatible M6P glycan production. 3. Next-Gen: Directed evolution of GELYTAC for improved potency and cell-based therapeutic delivery.
ASGPR	Highly liver-specific. Primarily expressed on the surface of hepatocytes	Glycoproteins with terminal Galactose or N-acetylgalactosamine (GalNAc) residues (especially tri-antennary structures)	Membrane Proteins: EGFR, HER2, PD-L1, CD24; Extracellular Proteins: PCSK9, pro-inflammatory cytokines, anti-DNP antibodies.	1. GalNAc-Antibody Conjugates 2. Bifunctional Small Molecules (MoDE-As) 3. Nanospheres (Nano-LYTACs) 4. Engineered Exosomes (LYTEXs)	Confirmed endocytosis and lysosomal degradation in Hep3B and HepG2 cells; observed inhibition of downstream signaling (e.g. EGFR)	1. Plasma Clearance: Rapid depletion of circulating PCSK9 or antibodies in mice. 2. Tumor Inhibition: Degradation of CD24 enhanced phagocytosis and suppressed tumor growth	1. Tissue Restriction: Limited to liver-related targets. 2. Receptor Competition: Endogenous glycoproteins may compete for binding. 3. Pharmacokinetics: Small-molecule degraders (MoDE-As) may have short half-lives due to rapid metabolism.	1. Site-specific Conjugation: Methods like chemoenzymatic coupling improve PK stability. 2. Safety Profile: Offers an excellent safety window due to localized action in the liver.
Cytokine Receptors	CXCR7: Broadly expressed in heart, kidney, brain, vascular endothelium, and various tumors (HeLa, MDA-MB-231); IL-2R: Specifically on activated T cells.	CXCL12, CXCL11, vMIPII (for CXCR7); IL-2 (for IL-2R)	Membrane Proteins: PD-L1, HER2, EGFR, PD-1; Extracellular Proteins: Soluble TNFα, circulating Atezolizumab.	Bispecific Antibody Fusion (KineTAC): Cytokines (as receptor-binding arms) fused to antibodies/nanobodies targeting the POI	Significant degradation of PD-L1 and HER2 in HeLa and MDA-MB-231; PD-1 degradation on activated primary human CD8+ T cells.	Clearance of pre-injected labeled target proteins (e.g. Atezolizumab-647) from mouse circulation via IP injection of CXCL12-KineTAC.	1. Pharmacokinetics: Potential short half-life due to the small size of cytokine components. 2. Competition: Endogenous cytokine levels may compete for receptor binding.	1. Modularity: Simple swapping of the cytokine arm allows targeting of different receptor systems. 2. Genetic Encodability: Suitable for integration into therapeutic cells (e.g. CAR-T) for local secretion.
Integrins	Tumor-associated: Highly expressed on various malignant tumor cells (e.g. MDA-MB-231, B16-F10, HeLa, A549) and tumor angiogenic endothelial cells.	Extracellular matrix proteins containing the RGD (Arg-Gly-Asp) motif; synthetic cRGD peptides or RGD mimetics are commonly used	Membrane Proteins: PD-L1, EGFR, HER2, CD71, CAIX; Extracellular Proteins: Anti-DNP antibodies.	1. Bifunctional Small Molecules (IFLD/ITAC) 2. RGD-Antibody Conjugate. 3. Bispecific Aptamer Chimeras (ITGBAC). 4. Supramolecular Nanofibers (Supra-LYTAC).	Demonstrated concentration- and time-dependent degradation (often >70%) in tumor lines; validated lysosome- and integrin-mediated endocytosis.	Significant tumor growth inhibition and TME improvement in B16-F10 or MDA-MB-231 xenograft models via PD-L1 or CAIX degradation.	1. Basal Expression: Potential off-target risks due to expression in normal tissues (vessels, muscles). 2. Internalization Variance: Endocytosis rates differ across integrin subtypes.	1. Multivalent Design: Supramolecular nanofibers or polymers can enhance affinity and potency. 2. Synergy: PD-L1 degradation synergizes with immune checkpoint therapy to boost anti-tumor immunity.
SR	Primarily expressed on macrophages, monocytes, DCs, some endothelial cells, and tumor cells (e.g. A549, MCF-7, HeLa)	Modified LDL (e.g. acLDL), polyanions (e.g. G-rich DNA/polynucleotides), and specific synthetic peptides	Membrane Proteins: EGFR, Nucleolin (NCL), PD-L1; Extracellular Proteins: IL-17A.	1. Dendronized DNA Chimeras (DENTAC) using branched DNA as multivalent SR-binding arms. 2. Supramolecular Co-assembly (LYTACA) based on peptide ligands.	Observed efficient degradation in A549 and RAW264.7 cells; confirmed SR-mediated endocytosis as the primary pathway.	1. Tumor Models: NCL-DENTAC significantly inhibited lung cancer growth. 2. Inflammation Models: IL-17A-LYTACA reduced inflammation in an IMQ-induced psoriasis mouse model.	1. Broad Ligand Spectrum: SRs bind diverse ligands, leading to potential competition. 2. Immune Modulation Risk: Recruiting SRs may interfere with normal macrophage immune functions.	1. Multivalent Enhancement: SRs exhibit high affinity for multivalent ligands (DNA dendrons/nanoparticles). 2. Dual-Targeting: Can degrade cancer cell proteins and modulate tumor-associated macrophages (TAMs).
LRP-1	Broadly expressed in liver, brain, lungs, heart, and vascular smooth muscle; highly expressed in various tumor cells and TME cells.	HSP90, RAP, ApoE, α2M, Lactadherin	Membrane Proteins: Integrin αvβ5, PD-L1; Extracellular Proteins: Cubilin	1. Bifunctional Conjugates. 2. Engineered Platelets (DePLTs): Using platelet-released HSP90 to recruit LRP-1.	Significant POI downregulation in HeLa and 4T1 cells; validated RAP-competitivity (LRP-1 dependent) and lysosomal dependence.	In post-surgical breast cancer models, DePLTs successfully homed to wounds to degrade PD-L1, activating local anti-tumor immunity.	1. Hook Effect: High concentrations may saturate receptors, reducing endocytosis efficiency. 2. Ubiquitous Expression: Risk of off-target effects due to broad tissue distribution.	1. BBB Potential: LRP-1 is a key transcytosis receptor, promising for CNS protein degradation. 2. Wound Homing: Platelet-based delivery enables selective degradation at inflammatory or surgical sites.
eHSP90	Tumor-specific: Highly secreted by tumor cells (e.g. A549, H1299); minimally expressed/secreted by normal cells.	GA and derivatives (e.g. 17-AAG), Ganetespib.	Membrane Proteins: PD-L1; Extracellular Proteins: AF488-labeled α-DNP antibody.	Bifunctional Small Molecules (eHSPTACs): Linking an HSP90 ligand to a POI ligand via a chemical linker.	Dose-dependent degradation of PD-L1 in cancer cells; confirmed dependence on LRP-1 and lysosomes.	In MC38 tumor models, dPDL1-4 significantly reduced tumor PD-L1 levels and enhanced anti-tumor immune infiltration.	Indirect Dependence: Relies on LRP-1 for internalization; low LRP-1 expression can limit degradation efficiency.	Inherent Selectivity: Leverages high eHSP90 levels in the TME to achieve superior tumor selectivity compared to M6PR-LYTACs.
GLP-1R	Primarily expressed in pancreas, lungs, hypothalamus, GI tract, and cardiovascular system. Also present in GLP-1R + tumor cells.	GLP-1 (7-36), Exendin-4	Membrane Proteins: EGFR, PD-L1.	Peptide-Antibody Conjugates (PACs): Conjugating GLP-1 peptide (recruiting arm) to a POI-targeting mAb via Click chemistry.	Significant degradation of EGFR and PD-L1 in GLP-1R-overexpressing cells; validated GLP-1R-dependency.	Detailed in-vivo efficacy data was not provided.	1. Restricted Expression: Limited to GLP-1R+ tissues/cells. 2. Biological Interference: Potential to trigger physiological effects (e.g. insulin secretion) as GLP-1R is a metabolic regulator.	Potential for Comorbidity Treatment: GLP-1 analogs are clinically proven; their rapid internalization makes them ideal for targeting metabolic organs or specific cancers.
Glut1	Ubiquitous but Tumor-enriched. High in BBB and RBCs; significantly overexpressed in various cancers (e.g. A549, HeLa, MC38)	D-Glucose derivative, specifically 2-deoxy-D-glucose.	Membrane Proteins: PD-L1, EGFR.	Bifunctional Polymers/Molecules (GFLDs): Multiple glucose ligands conjugated to a POI binder (mAb or small molecule) via a polymer backbone or linker.	Efficient PD-L1 degradation in A549 cells; observed strong POI-lysosome co-localization; degradation inhibited by excess free glucose.	In MC38 tumor models, GFLD significantly downregulated PD-L1, increased CD8+ T cell infiltration, and outperformed mAb-only therapy.	1. Competitive Inhibition: Endogenous blood glucose may compete for binding. 2. Off-target Risk: GLUT-1 expression in RBCs and brain requires careful targeting optimization.	Metabolic Targeting: Exploits tumor metabolic reprogramming; glucose ligands offer low immunogenicity and high biosafety.
FR	High Tumor Selectivity. Overexpressed in various cancers (ovarian, lung, breast); minimal expression in normal tissues (restricted to apical surfaces like renal tubules).	FA or its derivatives.	Membrane Proteins: PD-L1, EGFR, HER2; Secreted Proteins: mCherry.	Bifunctional Conjugates: 1. Small molecule/mAb conjugates; 2. Polyvalent scaffolds (e.g. polymer-based multivalent FA display).	Sub-nanomolar potency in FR+ lines (HeLa, OVCAR-3); confirmed dependency on endocytosis and lysosomal acidity.	Significant reduction of PD-L1/EGFR in H292/RM-1 tumor models; robust tumor growth inhibition and activation of T-cell immune responses.	1. Competition: Potential interference by endogenous folate; 2. Subtype Focus: Mainly targeted at FRα	Precision Medicine: Superior tumor selectivity over M6PR, minimizing systemic toxicity; FA ligands are stable, simple to synthesize, and cost-effective.
TfR	Broadly expressed in macrophages, DCs, and various tumor cells (e.g. MDA-MB-231, HepG2, A549).	DENTACs: Negatively charged dendritic DNA; LYTACAs: Negatively charged self-assembling peptides mimicking oxLDL.	Membrane Proteins: PD-L1, EGFR, Nucleolin (NCL); Extracellular Proteins: IL-17A.	DENTAC: Branched DNA-antibody conjugates via click chemistry. LYTACA: Non-covalent self-assembling nanoplatform based on bifunctional peptides.	DENTAC significantly degraded NCL/EGFR in A549 cells. LYTACA induced lysosomal degradation of PD-L1/IL-17A in SR-A + lines.	NCL-DENTAC inhibited lung tumor growth. IL-17A-LYTACA reduced IL-17A levels and alleviated inflammation in psoriasis mouse models.	1. Receptor Competition: Blood components may compete for SR binding. 2. Potential Immunogenicity: Large DNA structures or peptides may trigger immune responses.	1. Multivalency: SRs favor multivalent negative ligands, ideal for nano/polymer degraders. 2. Immunomodulation: Can target both immune and tumor cells to remodel the TME.
GPC3	Highly specifically expressed in hepatocellular carcinoma (HCC); also expressed in squamous lung cancer, ovarian cancer, and melanoma. Barely expressed in normal adult tissues.	Wnt proteins; Nanobodies targeting GPC3 (e.g. HN3 VHH) are used in research.	Membrane Proteins: PD-L1, c-Met, EGFR, FGFR1.	Nanobody-Antibody Conjugates/Bispecific Molecules: Conjugating GPC3 nanobody with POI binders via modular ligation.	Confirmed efficient degradation of PD-L1 and c-Met in GPC3(+) HCC cells (e.g. Huh7, HepG2); validated that degradation is GPC3-expression dependent.	Demonstrated significant PD-L1 reduction in tumor tissues, enhanced T cell infiltration, and inhibited tumor growth in HCC xenograft mouse models.	1. Limited Scope: Only effective against GPC3-positive tumors. 2. Endocytosis Variability: Degradation kinetics may be limited by variations in receptor density across different cell lines.	Superior Safety Window: Due to GPC3's tumor specificity, off-target toxicity risk is much lower than broad receptors, making it an ideal platform for precision therapy of HCC and related solid tumors.
Sortilin	Highly expressed in various malignancies (e.g. breast cancer, lung cancer); minimally present in healthy tissues outside the nervous system.	Neurotensin, Proprotein convertases; Research utilizes specific non-endogenous binders screened via AlphaFold-Multimer.	Membrane Proteins: PTK7, PD-L1, EGFR, HER2, EpCAM.	mRNA-encoded Lysosomal Targeting Chimera (MedTAC): Utilizing LNPs to deliver mRNA for in-situ expression of secreted chimeric proteins consisting of Sortilin and POI binders.	Achieved rapid POI degradation in multiple tumor cell lines.	In breast cancer mouse models, a single low dose reduced PTK7 by 80% within 24 h, with sustained degradation for over 72 h.	1. Potential Neural Impact: Potential CNS side effects due to Sortilin expression in the nervous system. 2. Immunogenicity: Possible immune responses triggered by mRNA carriers or chimeric proteins.	Rapid and Precise: Combines mRNA technology's production advantages with Sortilin's tumor specificity, enabling rapid, precise, and sustained MP degradation.

3.3. Endotags: a highly efficient and controllable LTR-targeting universal platform

Although endocytosis-based TPD technologies show great potential in treating diseases like cancer, these methods often face limitations such as competition with endogenous ligands, off-target effects, and complex synthesis. To address these issues, Huang's team developed a novel computationally designed protein, that is, EndoTags, enabling efficient and controllable protein degradation and signaling regulation. Targeting different receptor endocytosis mechanisms, the team designed three classes of EndoTags: (1) For constitutively recycling receptors like sortilin and TfR, Sort-EndoTag and TfR-EndoTag were designed to non-competitively bind to the LTR with natural ligands. These tags specifically bind receptors without interfering with natural ligand functions (e.g. vasopressin or transferrin). Sort-EndoTag demonstrated the most significant enhancement in endocytosis efficiency in glioblastoma cells (Figure 6a); (2) For IGF2R, which requires conformational changes, a dual-epitope protein IGF-EndoTag2 was developed to simultaneously bind its two domains, forcing IGF2R into an endocytosis-conducive conformation. Its internalization efficiency reached twice that of the natural ligand IGF2 and remained unaffected by intracellular M6P-modifying enzymes (Figure 6b); (3) For ASGPR, which relies on multivalent aggregation, the designed trimeric AS-EndoTag-3C significantly enhanced endocytosis efficiency in hepatocytes (Huang et al. 2025) (Figure 6c).

Figure 6.

Design strategies for endocytosis-triggering EndoTags. a, Designing a constituent cyclic receptor that does not overlap with natural ligand binding sites to avoid competition. b, Designing a binding moiety that triggers endocytosis by inducing a conformational change in the receptor. EndoTag binds to two distinct epitopes on the target and actively triggers this conformational change. c, Engineering endocytosis through multivalent aggregation of the receptor. Multivalent EndoTags aggregate multiple copies of the target receptor and induce endocytosis. Reprinted with permission from Huang et al. (2025). Copyright 2024, Springer Nature.

The fusion of EndoTags with EGFR or PD-L1 antibodies considerably improves the internalization and degradation efficiency of target proteins, with the PD-L1 antibody-EndoTag fusion surpassing the efficacy of the standalone antibody in mouse tumor models, significantly inhibiting tumor growth and extending longevity. EndoTags effectively eliminate soluble proteins such as IgG at double the speed of traditional techniques. EndoTags significantly improve the efficiency of synthetic signaling systems: when integrated with the SNIPR system, signal activation intensity amplifies almost 100-fold; when paired with the Co-LOCKR system, it facilitates precise degradation governed by an ‘AND gate.’ These attributes establish EndoTags as a comprehensive platform for protein degradation, signaling regulation, and targeted delivery (Huang et al. 2025).

3.4. LTR-independent LYTAC technology

Contemporary LYTAC technologies depend on particular LTRs; nevertheless, the variable expression and overactivation of these receptors in tissues may result in application constraints and drug resistance. Cai's team proposed SignalTAC, which is founded on a lysosomal sorting signal, to overcome this issue. SignalTAC consists of a target-binding protein, a cell-penetrating peptide (CPP), and the sorting motif P1, enabling the direct routing of membrane proteins such as EGFR, HER2, PD-L1, CD20, and CD71 to lysosomal degradation, independent of any LTR or E3 ligases. In vivo, SignalTAC decreased HER2 signaling, slowed tumor proliferation, and preserved substantial EGFR degradation through nanobodies or peptides (Yu et al. 2023) (Figure 7a).

Figure 7.

Construction and application of two generations of Signaltac containing lysosomal endocytosis signals and SApt. a, First-generation SignalTACs participate in the clathrin-mediated endolysosomal pathway for targeting membrane protein degradation. Reprinted with permission from Yu et al. (2023). Copyright 2023, American Chemical Society. b, Second-generation Signaltac-mediated lysosomal targeting for membrane protein degradation and construction of both Signaltac variants. Reprinted with permission from Fang et al. (2024). Copyright 2024, Royal Society of Chemistry. c, Schematic of endocytosis and transport pathways for Tz-p3 and Tz-p2-p1. Reprinted with permission from Fang et al. (2024). Copyright 2024, Royal Society of Chemistry. d, Working concept of signal aptamer chimeras (SApts) for lysosomal transport and membrane protein degradation. Reprinted with permission from Xie et al. (2025). Copyright 2025, Proceedings of the National Academy of Sciences of the United States of America.

Building on this, the team further developed a new generation of CPP-free SignalTAC utilizing another sorting signal, the tyrosine motif P3.P3 exhibited superior efficiency in the endocytosis and degradation of HER2 and PD-L1, as well as enhanced anticancer efficacy, in comparison to P1-based designs. Mechanistic investigations demonstrated that P3 is internalized via fossa-mediated endocytosis and requires AP-1/AP-3 for lysosomal ingress, while P1 is dependent upon clathrin and AP-2/AP-3/GGA, involving Golgi transport. This highlights unique functional routes for various sorting signals, offering theoretical backing for the advancement of more efficient degrading technologies utilizing endogenous signals (Fang et al. 2024) (Figure 7b,c).

Although Cai's team introduced novel insights with SignalTAC (Yu et al. 2023), its antibody structure remains burdened by high molecular weight and complex preparation. To address this, Qub's team utilized the YXXØ sorting signal of LAMP-2a, click-chemically linking it to the terminus of an aptamer to construct a signal-aptamer chimera (SApt). This molecule achieves degradation of membrane proteins like PTK7, Met, and NCL through clathrin- or caveolin-mediated endocytosis, independent of LTR. In vivo, SApt modulates downstream pathways and induces tumor cell apoptosis, demonstrating significant antitumor activity. This approach offers a novel strategy to overcome LTR dependency and expand TPD applications (Xie et al. 2025) (Figure 7d).

4. Development of LYTAC technologies binding different ligands

4.1. Aptamers

Aptamers are single-stranded small DNA or RNA molecules with complex three-dimensional structures; their unique secondary or tertiary structures enable specific binding to proteins (Chen et al. 2022). Compared to antibodies, aptamers exhibit lower immunogenicity in vivo (Xiao et al. 2021). Additionally, aptamers can be rapidly synthesized and produced at scale.

4.1.1. Design and application of bispecific aptamer chimeras

Leveraging the flexibility of aptamers, the Han team designed an innovative bispecific aptamer chimera platform, Aptamer1-Linker-Aptamer2 (A1-L-A2), addressing the time-consuming gene editing methods and limited small-molecule inhibitor targets in existing LYTAC technologies. A1-L-A2 comprises three components: an aptamer targeting IGF2R (A1), an aptamer targeting the membrane protein (A2), and a DNA linker (L). A1 employs a 40 nt DNA aptamer as a fixed design, enabling high-affinity targeting of IGF2R. To optimize degradation efficiency and broaden applicability, on the one hand, the team systematically optimized the linker structure, identifying a 23 bp dsDNA linker D3 chimera as the optimal configuration: stable structure, extended half-life, and highest cellular affinity; on the other hand, modifying A2 sequences enabled targeting of diverse membrane proteins (Miao et al. 2021) (Figure 8a). Another bispecific aptamer chimera, VED-LYTACs, consisting of dsDNA that connects M6PR-A and VEGF-A, successfully binds to and degrades VEGF, thereby reducing endothelial cell motility, angiogenesis, and sprouting both in vitro and in vivo (Zhou et al. 2024).

Figure 8.

Schematic of LYTAC-mediated degradation of target proteins using aptamers, nanoparticles, or small peptides as ligands. a, Membrane protein degradation via A1-L-A2-mediated lysosomal internalization facilitated by IGF2R-mediated lysosomal proteolysis. Reprinted with permission from Miao et al. (2021). Copyright 2021, John Wiley and Sons. b, Schematic of TDA-MLYTAC-induced targeted degradation of single- or dual-membrane proteins. Reprinted with permission from Zhu et al. (2025). Copyright 2025, American Chemical Society. c, Schematic of multivalent AptLYTACs for targeted degradation of cell surface proteins. Reprinted with permission from Duan et al. (2024). Copyright 2024, John Wiley and Sons. d, targeted degradation of extracellular proteins or EVs mediated by monotab. Reprinted with permission from Yao et al. (2024). Copyright 2024, Springer Nature. e, Schematic of PSMLTAC, a peptide-based small molecule degradator, targeting POI degradation via the endocytosis-lysosomal pathway. Reprinted with permission from Chen et al. (2024). Copyright 2024, American Chemical Society.

In contrast, the preparation of chimeras via antibody and tri-GalNAc conjugation is complex and time-consuming, presenting issues such as large molecular weight, synthetic complexity, and low internalization efficiency (Ahn et al. 2021; Zhou et al. 2021). Zhi's team conjugated aptamers targeting different proteins, rather than antibodies, to tri-GalNAc to prepare ASGPR-mediated Apt-LYTACs. It can specifically mediate the internalization and degradation of SA-488, PDGF, and PTK7 in hepatocytes; among these, GalNAc-Apt-PTK7 treatment significantly reduced PTK7 levels, inhibiting cellular activity and migration capacity, thereby directly affecting cellular function (Wu et al. 2023). Another major advantage of aptamers is their ease of acquisition. Tan's team employed Cell-SELEX technology to obtain aptamers at scale, using DML-7 as the core component, they constructed bispecific aptamer chimeras (ITGBACs) by linking aptamers targeting membrane proteins with linkers of varying lengths. Among these, chimeras with a 13-bp linker demonstrated optimal binding activity and degradation efficiency, significantly reducing levels of target proteins CD71 and PTK7, indicating broad applicability (Sun et al. 2024). By optimizing aptamer stability and tissue targeting, this platform holds promise for clinical translation.

4.1.2. DNA vector optimization and multivalent strategy development

A key direction in advancing the aptamer-based LYTAC technology involves progressively optimizing the structure and function of the carrier DNA. Beyond the three linker formats tested by the Han team in A1-L-A2, including D1 (ssDNA), D2 (short dsDNA), and D3 (long dsDNA) (Miao et al. 2021), the DNA tetrahedron structure (TDN) offers distinct advantages due to its editability, site specificity, and simplified synthesis and modification processes. Zhu's team developed a multivalent LYTAC platform (TDA-MLYTAC) using TDN as a carrier, precisely assembling tri-GalNAc and aptamers targeting POI. This multivalent chimera demonstrated significantly higher degradation efficiency against PTK7 compared to monovalent LYTAC, while also exhibiting enhanced cellular uptake and lysosomal targeting capabilities (Zhu et al. 2025) (Figure 8b). Similarly, Liu's team designed TDN-framework-based chimeras (TDF-LYTACs) targeting PDGF via IGF2R, achieving 90% degradation efficiency within 20 hours. Combined with real-time monitoring of intracellular ATP levels, this further highlights the dual advantages of aptamers in targeted degradation and biosensing. Theoretically, TDF-LYTACs can assemble and function as long as reliable LTR aptamers exist, laying the foundation for developing more precise disease treatment strategies (Ning et al. 2025). Through TDN's modular design, precise construction of multivalent LYTACs can be achieved.

To investigate the correlation between the valency of aptamer complexes and the therapeutic efficacy of Apt-LYTACs, Tan's team developed multivalent aptamer-based Apt-LYTACs. They discovered that trivalent single-target Apt-LYTACs exhibited maximal efficiency in degrading membrane proteins. Notably, multivalent Apt-LYTACs not only require fewer aptamers but also significantly enhance target protein degradation, but excessive aptamer loading may reduce efficiency due to steric hindrance or bpM6P damage (Duan et al. 2024) (Figure 8c). However, the rigidity of TDN structures may limit effective binding between certain vertex-modified ligands and receptors. Therefore, exploring carriers with greater structural flexibility holds promise for further enhancing the protein degradation efficiency of multivalent LYTACs.

Conversely, to obtain a more profound understanding of the impact of multivalent DNA structures on degradation processes, Shi's team leveraged DNA's high programmability to self-assemble controllable multivalent linear DNA LYTAC frameworks with 1-, 3-, and 9-valent configurations. By modifying the valence and ligand spacing of the chimeras, they discovered that: increasing valence significantly enhanced both the binding affinity and degradation rate of LYTAC toward target proteins SA and Met, and this multivalent enhancement effect also applied to different LTRs. Significantly, for LYTACs with the same valence, adjusting DNA length and ligand spacing did not significantly affect degradation efficiency, indicating that the flexibility of the linear DNA framework effectively mitigates steric hindrance effects (Lv et al. 2025). Leveraging the significant advantage of multivalent structures in enhancing binding affinity, multiple research teams have successively developed aptamer-based LYTAC technologies such as AuNP-APTACs, IMTAC, and MD. These methodologies have improved the endocytosis and degradation efficiency of targets to varying degrees, further enhancing therapeutic efficacy (Lu et al. 2023; Cui et al. 2024; Yu et al. 2024).

4.1.3. Dual-target aptamer chimera strategy

The IGF2-based aptamer chimeras (ITACs) developed by the HAN team not only accomplished efficient degradation of membrane proteins such as c-MET, PTK7, Epithelial Cell Adhesion Molecule (EpCAM), and FGFR2, but more importantly, the modular characteristics of aptamers enabled dual-target degradation: Through DNA complementary pairing, two mITACs with precise stoichiometry were precisely assembled with IGF2 to form dual-target ITACs (dITACs), capable of simultaneously degrading two types of membrane proteins with higher efficiency than mixing the two ITACs separately. This strategy not only simplified the preparation process but also demonstrated flexibility and programmability in multi-target synergistic therapy (Tian et al. 2024). Tan's team integrated two distinct aptamers into a unified Apt-LYTAC scaffold by designing controlled assembly between biotin (introduced bpM6P) and streptavidin (SA, aptamer-modified), enabling simultaneous degradation of PTK7 and Met. Degradation efficiency was further optimized by adjusting aptamer ratios, with a 2:1 Sgc8:SL1 ratio maximizing degradation of both target proteins (Duan et al. 2024) (Figure 8c). In a similar vein, based on the multivalent LYTAC platform, Zhu et al. designed a bispecific TDA-MLYTAC (TDN-SS'-2) capable of simultaneously degrading PTK7 and EpCAM. This approach demonstrated significantly higher efficiency than the combined use of two monovalent LYTACs, while also inhibiting HepG2 cell migration and inducing cell death. The two aptamer-modified TDA-MLYTACs demonstrate immense potential, suggesting that rational design of recognition components could revolutionize the development of multi-target protein degradation tools (Zhu et al. 2025) (Figure 8b).

4.2. Nanoparticles (NPs)

To overcome the constraints of conventional LYTAC regarding limited bioavailability and non-specific dispersion, researchers have initiated investigations into nanoparticle-based LYTAC technologies. NPs exhibit low molecular weight and superior cellular absorption, facilitating efficient and steady distribution to points of interest. Conversely, nanoparticles, including polymeric and lipid nanoparticles, can be effectively ingested by cells and delivered to lysosomes without the necessity for ligand modification.

4.2.1. NP-enhanced POI delivery and degradation

NPs: Liu's team innovatively utilized gold nanoparticles (AuNPs) as carriers, leveraging their high specific surface area and modifiability to develop novel high-valent bispecific chimeras, AuNP-APTACs. Each AuNP carries approximately 376 aptamers on average, forming a superior binding structure that remains stable in serum. This significantly enhances the degradation efficiency of the six-pass trans-membrane ABCG2, effectively reversing multidrug resistance (MDR) in cancer cells (Lu et al. 2023). To enhance stability and tumor targeting, Luan's team self-assembled CL8-M6P3 into GSH-responsive nanoparticles (NanoCLY), which release active LYTAC peptides within the tumor microenvironment to degrade CTGF. In vivo, NanoCLY inhibits tumor growth and metastasis, demonstrating synergistic effects when combined with PTX. This approach integrates the targeted delivery advantages of nanocarriers with the protein degradation functionality of peptide-mediated (Lin et al. 2025b).

Nanospheres: Dai's team constructed Nanosphere-AntiCD24 complexes by self-assembling GalNAc modified with amphiphilic peptides and conjugating them to CD24 antibodies. With a diameter of approximately 200 nm, the surface GalNAc modification enhances ASGPR-mediated CD24 endocytosis, thereby blocking the CD24/Siglec-10 signaling pathway and restoring macrophage phagocytosis of tumor cells. Additionally, the team loaded GOx onto the nanospheres, improving drug stability and tumor enrichment capacity through the nanocarrier platform (Wang et al. 2023a).

Circular DNA: Zhang's team developed multivalent nanotargeted chimeras (mNbTACs) by printing multiple nanobody sequences onto circular DNA templates via DNA printing technology. These structures bind both POI and scavenger receptors in a multivalent manner. The circular DNA architecture confers exceptional stability to mNbTACs, enabling efficient degradation of POIs. The further constructed bispecific Dox-loaded complex Dox omvNbsPPH simultaneously binds PD-L1 and HER2 for degradation, significantly increasing CD8⁺ T cell infiltration and proliferation in the tumor microenvironment to synergistically inhibit tumor growth (Jiang et al. 2024).

Circular DNA origami: Compared to ssDNA or dsDNA, DNA origami exhibits superior programmability, precision, and compatibility. Chao's team designed IMTAC, a smart modular nanoplatform based on circular DNA origami. By precisely regulating the pH-responsive promoter on the nanocarrier, and the stoichiometry and arrangement of multivalent small-molecule ligands, it achieves specific targeting of IGF2R in HCC tissues and synergistic degradation of EGFR and PD-L1. In acidic tumor microenvironments, IMTAC efficiently activates degradation switches, reduces off-target effects, and significantly enhances drug utilization (Cui et al. 2024).

DNA nanowires: Liu's team concatenated two single-stranded DNA strands containing membrane proteins and IGF2R aptamers sequentially into linear DNA nanowires, which self-assembled into periodically arranged Multivalent degraders (MDs). This multivalent structure substantially enhances the affinity between degraders and target cells while enabling precise control over heterologous aptamer density, ratio, and spatial distribution. MDs with a 20-bp aptamer spacing demonstrated optimal performance. MDs significantly enhance T-cell activity by degrading PD-L1 while simultaneously inhibiting downstream Erk signaling pathways and tumor cell proliferation through VEGFR2 degradation (Yu et al. 2024).

Protein nanocapsules: Liu's team designed a nanotechnology-based NLTC dual-functional protein nanocapsule. On the one hand, it utilizes a pH-responsive, detachable polyethylene glycol (PEG) shell for selective accumulation in tumor tissues, achieving multivalent binding and degradation of α-DNP and PD-L1 through surface composition regulation. On the other hand, catalase (CAT) was encapsulated to decompose H₂O₂ in the tumor microenvironment into O₂, thereby alleviating the TME and activating T cell-mediated antitumor immune responses to synergistically enhance immunotherapy efficacy (Xing et al. 2025).

4.2.2. None-LTR-dependent nanoparticle endocytosis degradation pathways for POIs

Currently developed LYTAC technologies typically rely on specific LTRs, and their overactivation may induce resistance, limiting their application. Chen's team developed the covalent nanobody chimera GlueTAC by combining a covalent nanobody GlueBody with a CPP and lysosomal sorting sequence (LSS). GlueTAC enhances internalization and lysosome-mediated degradation efficiency while offering advantages such as compact size and independence from specific receptors or E3 ligases. It induces internalization and lysosomal degradation of the membrane protein PD-L1, demonstrating superior immune activation effects compared to traditional antibodies. In vivo, GlueTAC sustainably restores T-cell activity and suppresses tumor growth (Zhang et al. 2021).

To tackle resistance issues caused by cellular heterogeneity or genetic mutations, Shen's team pioneered the use of nanoparticle-intrinsic lysosomal targeting capabilities. By immobilizing antibodies onto nanoparticles via streptavidin-biotin interactions, they developed MONOTAB: a modular, single-function ‘plug-and-play’ platform. MONOTAB directly promotes lysosomal biogenesis without relying on specific LTRs, achieving efficient degradation of membrane protein PD-L1 and secreted protein Matrix metalloproteinase 2 (MMP2) without hook effects. It also achieved intervention of non-protein targets, Extracellular Vesicles (EVs) (Yao et al. 2024) (Figure 8d).

Beyond oncology applications, this nanodelivery strategy was also employed by Gao's team to study Alzheimer's Disease (AD) with RAGE overexpression. The team synthesized endoTAC, a lysosome-cystoid nanomesh chimera based on multivalent receptor binding. By leveraging multivalent interactions between RAP peptides on the nanomaterial and RAGE, endoTAC enhances lysosomal sorting efficiency and achieves efficient degradation of RAGE in pathological Blood-Brain Barrier (BBB) regions. SV@endoTAC reverses AD pathological features by downregulating RAGE and upregulating LRP1 to restore BBB function and integrity, reduce Aβ deposition, restore neuronal morphology, and eventually alleviates oxidative stress and neuroinflammation alleviated (Wang et al. 2025).

4.3. Peptide-mediated small molecule degradation strategy

Existing lysosome-TPD technologies primarily rely on antibodies or nanobodies. Although small-molecule degraders are not yet widely used, they offer advantages such as lower cost and superior tumor penetration capabilities. Therefore, Sheng's team designed a peptide-mediated small molecule chimera, PSMLTAC, which combines a lysosomal sorting signal (NPGY motif), a CPP, and a small molecule target ligand. PSMLTAC delivers target proteins PD-L1, PDEδ, BTK, and NAMPT to lysosomes for degradation via clathrin-mediated endocytosis (independent of specific LTRs). Studies indicate that CPP length and composition significantly influence PSMLTAC degradation efficiency. However, this class of PSMLTAC degraders still faces challenges in overcoming metabolic stability and oral bioavailability limitations alleviated by the peptide backbone and macromolecular size (Chen et al. 2024) (Figure 8e).

Ryu's team pioneered the use of tumor-specific CAIX as a tool for endocytic degradation of POIs, designing Supra-LYTAC: a supramolecular nanofiber chimera based on self-assembling amphiphilic peptides. This chimera forms complexes near the membrane through multivalent binding and delivers the membrane protein PD-L1 to lysosomal degradation via CAIX-mediated endocytosis, significantly inhibiting tumor growth in animal models. The study revealed that protein-peptide self-assembly is integral to Supra-LYTAC's function, particularly secondary interactions within the peptide backbone (e.g. hydrophobic interactions, π-π stacking, and hydrogen bonds), which are essential for nanofiber formation and POI capture efficiency: LYTACs constructed with FFK peptides based on strong secondary interactions demonstrated significantly higher degradation efficiency than LYTAC based on weaker GGK peptides (Kim et al. 2025a).

For pathological protein accumulation in neurological diseases, existing TPD technologies struggle to cross the BBB. Addressing this, Spiegel's team designed TransMoDEs: the first dual-functional molecules enabling intracellular lysosomal degradation of POIs within the central nervous system while also transporting across the BBB for degradation in organs such as the liver. Based on Angiopep-2 peptide segments, Streptavidin and HaloTag proteins can be targeted to endocytosis, respectively, by TransMoDEs. Notably, while Angiopep-2 traditionally acts via LRP1-mediated pathways, this study revealed that TransMoDEs' endocytosis mechanism does not rely solely on LRP1 but involves clathrin-dependent endocytosis, suggesting potential involvement of other receptors. This technique presents innovative therapeutic options for neurodegenerative disorders such as AD, despite the insufficient identification of its precise cellular targets (Howell et al. 2024).

5. Novel structure-tunable LYTAC

Facing the non-specific toxicity issues caused by the widespread distribution of POI and LTR in traditional LYTACs, Liu's team developed a ‘Logic-TAC’ system based on DNA logic gate computing. Through double-stranded DNA structural design, Logic-TAC seals the binding regions of target proteins MUC1 and IGFIIR, maintaining inertness in circulation. Since normal cells lack EpCAM, input 1 remains inactive, preventing exposure of the MUC1-IGF2R binding site and thus inhibiting MUC1 degradation. This ensures selective targeting of cancer cells, effectively suppressing tumor growth in breast cancer models. Simultaneously, the system strictly controls the binding sequence, avoiding ineffective endocytosis of ‘unloaded’ LYTAC molecules and boosting degradation efficiency (Fang et al. 2024) (Figure 9a).

Figure 9.

Structurally innovative or conditionally activated LYTAC technologies. a, Logic-TAC cancer cell-selective MUC1 degradation scheme via SECORE strategy. Reprinted with permission from Fang et al. (2024). Copyright 2024, John Wiley and Sons. b, Host-guest bridged lysosome-targeted chimeras (HGTACs) enabling tunable and sustainable TPD. Reprinted with permission from Chen et al. (2025). Copyright 2025, John Wiley and Sons. c, Schematic of extracellular acid-triggered multi-TAC protonation promoting PD-L1 dimerization, internalization, and lysosomal degradation. Reprinted with permission from Zhou et al. (2025a). Copyright 2025, John Wiley and Sons.

Traditional LYTAC relies on covalent linkage, limiting flexibility for dynamic regulation and ratio optimization. To address this, Jiang's team decomposed LYTAC into a β-CD-tri-GalNAc host module targeting ASGPR and an Ada-ligand guest module targeting POI. Through non-covalent interactions between supramolecular host and guest components, they achieved dynamic assembly (reversible binding) of the chimeric HGTACs, demonstrating sustained degradation of model protein NS-650 and membrane proteins EGFR and HER2. In vivo, HGTACs inhibited tumor growth. Crucially, degradation efficiency is flexibly controlled by adjusting host-guest stoichiometry or introducing competitive ligands, overcoming the fixed stoichiometry limitation of traditional LYTACs (Chen et al. 2025) (Figure 9b).

Given PD-L1's non-specific distribution, Xu's team designed multi-TACs: a multivalent chimeric GG56 comprising the PD-L1 small-molecule inhibitor BMS-1, acid-responsive monomers (EPA or DPA), and an MMP-2-cleavable PEG segment. GG56 leverages the tumor microenvironment's acidic conditions (pH 6.5-6.8) to trigger micelle NP dissociation, exposing BMS-1 within the hydrophobic core. This enables efficient PD-L1 degradation via electrostatic adsorption-mediated endocytosis-lysosomal pathways, reversing immune evasion without LTR. In mouse models, GG56 significantly suppressed tumor growth by degrading PD-L1 and recruiting Cytotoxic T Lymphocyte (CTLs). Combination with chemotherapeutic agents and radiosensitizers enhanced immunotherapeutic efficacy (Zhou et al. 2025a) (Figure 9c).

6. Multi-platform and combined strategies drive innovative LYTAC applications

Conventional LYTACs may demonstrate inadequate accumulation at target sites and unintended off-target effects in vivo, requiring enhanced spatiotemporal control of delivery systems. Hu's team covalently modified HSP90 and POI ligands onto platelets, establishing DePLTs. This system leverages platelets' innate targeting to surgical wounds. Upon thrombin activation, it achieves Bromodomain-containing Protein 4 (BRD4) and PD-L1 clearance via both UPS and LRP-1-mediated lysosomal degradation, effectively promoting T-cell infiltration and suppressing tumor recurrence in TNBC models (Chen et al. 2025) (Figure 10a). Inspired by bio-nanotechnology in AD therapy (Xie et al. 2019), the Qu team developed the first biomarker-activated KPLYs. Utilizing PDA nanoparticles and PiB-derived molecules, cli-LYTAC is generated via click chemistry at the lesion site, where PDA scavenges Reactive Oxygen Species (ROS), suppresses inflammation, and promotes glial cell polarization toward the neuroprotective M2 phenotype while upregulating CD206 expression and restoring lysosomal function; KD8 modification further enhances the nanoparticle's BBB penetration efficiency, enabling degradation of Aβ aggregates via the CD206-mediated pathway. This alleviates inflammation and improves lysosomal function in AD models, demonstrating neuroprotective effects (Liu et al. 2023) (Figure 10b). The LYTAC Plus nucleic acid hydrogel platform was invented by Hong's team. M6P-DNA and VEGFR peptide self-assemble and, when paired with ANG-2 siRNA, facilitate the dual activities of VEGFR-2 degradation and gene silence. In n-AMD murine models, the hydrogel accumulates locally and markedly suppresses neovascularization (Huang et al. 2024) (Figure 10c). Furthermore, Luan's team created a peptide-based LYTAC (RS17-M6P3) administered by PPS microneedles, which selectively degrades CD47 and inhibits the CD47-SIRPα signaling pathway. Simultaneously, PPS prompts TAMs to shift to the M1 phenotype, hence augmenting antitumor immunity (Lin et al. 2025a) (Figure 10d).

Figure 10.

Development and Application of LYTAC Technology Across Multiple Platforms and in Combination Therapies.a, Schematic of TPD targeting intracellular or extracellular targets in vivo using platelet-derived protein degraders and covalently labeled HSP90. Reprinted with permission from Chen et al. (2025). Copyright 2024, Springer Nature. b, Schematic of KPLYs-mediated antibody degradation of Ab for AD treatment. Reprinted with permission from Liu et al. (2023). Copyright 2023, Elsevier. c, Mechanism schematic of LYTAC Plus simultaneously degrading membrane proteins and silencing genes. Reprinted with permission from Huang et al. (2024). Copyright 2024, John Wiley and Sons. d, Schematic of PPS microneedle-delivered peptide-based LYTAC (RS17-M6P3) degrading immune checkpoint CD47 and inducing macrophage transformation. Reprinted with permission from Lin et al. (2025a). Copyright 2025, American Chemical Society. e, Schematic of photoactive bispecific aptamer chimeras (PBACs) modulating cellular autophagy via near-infrared laser to enhance targeted membrane protein degradation. Reprinted with permission from Zhang et al. (2025c). Copyright 2025, American Chemical Society. f, Schematic of SPN-based nano-LYTAC-mediated cancer ultrasound immunotherapy. Reprinted with permission from Xu et al. (2024). Copyright 2024, American Chemical Society.

For combination therapies, photodynamic/sonodynamic therapy was integrated into the LYTAC platform to enhance efficacy. Tan's team designed PT-LYTAC, integrating NIR photosensitizing molecules into a bispecific aptamer. This not only degrades PTK7 but also generates reactive oxygen species under light exposure to induce mitochondrial damage and activate autophagy. In colorectal cancer models, a single dose of PT-LYTAC combined with NIR light completely suppressed tumor growth (Zhang et al. 2025c) (Figure 10e). Pu's team combined SDT with LYTAC-mediated immunotherapy to develop the nanoparticle-based sonodynamic nano-LYTAC (SPNly). This system degrades IL-4R on M2 macrophages while simultaneously generating ROS under ultrasound irradiation to induce immunogenic cell death (ICD) in tumor cells. This approach reshapes the immune microenvironment and inhibits tumor metastasis (Xu et al. 2024) (Figure 10f). To provide an indication-oriented perspective, representative LYTAC strategies and their potential disease applications are summarized in Table 2.

Table 2.

Indications for LYTAC Therapy Across Different Disease Areas.

Indications	Key POIs	LTRs	Ideal platform	Biological rationale
Hepatocellular Carcinoma (HCC)	EGFR, PD-L1, GPC3, c-Met, FGFR1	ASGPR, GPC3	GalNAc-LYTAC, GLTACs	Exploits highly specific hepatic receptors for precision degradation, minimizing systemic toxicity.
Breast Cancer (e.g. TNBC)	HER2, TROP2, PTK7, MUC1	Sortilin, FRα, IGFIIR	MedTAC, FRTACs, Logic-TAC	Utilizes mRNA-encoding or logic-gate designs to trigger degradation in response to specific markers, overcoming resistance.
Lung Cancer	PD-L1, NCL	SR, Glut1	DENTAC, GFLD	Targets atypical receptors overexpressed in lung cancer to leverage efficient endocytic pathways for POI clearance.
Melanoma/Colon Cancer	PD-L1	TfR	Photothermal-triggered TfR-LYTAC	Combines photothermal therapy (PTT) for spatiotemporally controlled degradation at the tumor site to boost immune activation.
Alzheimer's Disease (AD)	ApoE4, α-syn, Aβ aggregates, RAGE	CI-M6PR, CD206, RAGE, TfR	iLYTAC, KPLYs, TransMoDEs	Clears extracellular pathological aggregates inaccessible to PROTACs; utilizes TfR-mediated transcytosis to cross the BBB.
Psoriasis/Skin Inflammation	IL-17A, TNF-α	SR-A, CXCR7	LYTACA, KineTAC	Acts as a ‘molecular vacuum’ to neutralize and clear circulating cytokines via co-assembly or cytokine receptor pathways.
Hypercholesterolemia	PCSK9	ASGPR	Small-molecule/Ab GalNAc-LYTAC	Utilizes the high-capacity ASGPR endocytic recycling pathway in the liver to clear plasma PCSK9 and lower LDL levels.
Ocular Diseases (e.g. AMD)	VEGF, VEGFR-2	CI-M6PR	LYTAC Plus (Nucleic acid hydrogel)	Provides localized and sustained release of degraders to inhibit neovascularization by targeting extracellular growth factors.

7. Challenges and outlook

Despite significant advances in endocytosis-lysosomal pathway-based TPD technologies in recent years, numerous limitations persist in molecular design, degradation efficiency, targeting specificity, and clinical translation. Recent reviews have comprehensively summarized the mechanistic foundations and translational hurdles of lysosome-targeting chimeras. In particular, Zhou systematically analyzed receptor selection, ligand design, pharmacokinetic limitations, and clinical barriers, providing a conceptual framework that contextualizes the challenges discussed in this review (Zhou et al. 2025b). Exploring novel research directions and derivative platforms to address these challenges represents a critical pathway for LYTAC technology development (Figure 11).

Figure 11.

Current challenges facing LYTAC technology and promising research directions. a, Ligand Design: Traditional macromolecular ligands often exhibit high plasma clearance and strong immunogenicity, whereas engineered or novel ligands hold promise for improving pharmacokinetics and reducing immunogenicity. b, Dynamic regulation: Fixed-coupling LYTAC lacks flexibility for ratio optimization. Reversible, dynamically assembled strategies enable LTR-ligand and POI-ligand flexible adjustment of ratios, enhancing the balance between efficacy and safety. c, Degradation Efficiency: Degradation efficiency fluctuates due to competition from endogenous ligands and affinity imbalances. Systematic investigation of degradation mechanisms, sequential binding strategies, or light/enzyme-triggered modules can enhance endocytosis and degradation capacity. d, Tissue Specificity: Non-specific LTR distribution and inadequate tissue penetration may induce systemic toxicity. Developing disease-specific LTRs combined with delivery platforms like nanoparticles, exosomes, or hydrogels holds promise for precision therapy. e, Clinical Translation: Current research predominantly remains confined to in vitro studies and short-term mouse models, lacking comprehensive clinical data. Efforts should focus on developing delivery platforms, exploring combination therapies, and conducting integrated assessments of pharmacokinetics, safety, and organ tropism. (The figure was created by the authors).

7.1. Ligand design challenges: improving immunogenicity and pharmacokinetics

First, in ligand design, early LYTACs predominantly relied on glycosylated LTR ligands like M6P or macromolecular POI ligands such as antibodies (Banik et al. 2020). However, their complex molecular structures and coupling processes not only increased synthesis difficulty but also introduced immunogenicity risks. Although subsequent introductions of aptamers (Miao et al. 2021; Wu et al. 2023; Sun et al. 2024; Zhou et al. 2024) and small-molecule peptides (Lu et al. 2023; Cui et al. 2024; Jiang et al. 2024; Yu et al. 2024; Xing et al. 2025) addressed limitations of antibody-based LYTACs in molecular weight, synthetic flexibility, and immunogenicity, these novel ligands still exhibit suboptimal specificity, affinity, and pharmacokinetic properties, which manifests as high plasma clearance rates, necessitating higher doses or frequent dosing, thereby increasing potential side effects. From a medicinal chemistry perspective, Yang and Zhu summarized recent progress in small-molecule ligands targeting lysosome-shuttling receptors, highlighting how ligand valency, linker composition, and receptor affinity collectively influence degradation efficiency and pharmacokinetics. These insights provide an important chemical foundation for optimizing LYTAC ligand design beyond macromolecular or glycan-based approaches (Yang and Zhu 2025). Therefore, future improvements should focus on alternative approaches such as gene-encoded or protein-engineered alternatives like iLYTAC (Zhang et al. 2023), GELYTAC (Yang et al. 2024), and MedTAC (Chang et al. 2025) to enhance quality consistency. Concurrently, further optimization of peptide/aptamer pharmacologic properties is needed through chemical modifications, stable multivalent systems, and delivery platform development.

The immunogenicity risk of LYTACs stems not only from their exogenous macromolecular structures but may also arise from unintended interference with intracellular homeostatic signaling pathways, potentially triggering inflammatory responses. Recent insights highlight the critical role of ubiquitination in innate immunity surveillance. For instance, Jiang reported that the ubiquitination-associated protein N4BP3 activates the TLR4-NF-κB pathway by promoting K48-linked ubiquitination of IκBα, exacerbating inflammatory bowel disease. This mechanism suggests that any LYTAC component capable of nonspecifically binding to or mimicking endogenous ubiquitination regulators warrants careful assessment for off-target inflammatory activation (Jiang et al. 2025). Therefore, in designing novel LYTAC ligands such as genetically encoded or small-molecule ligands, components with no cross-reactivity to endogenous inflammatory signaling pathways should be prioritized to mitigate immunogenicity and enhance therapeutic safety. In this context, structural biology provides an essential analytical foundation. Wu demonstrated how high-resolution structural analysis combined with functional validation can elucidate cooperative binding mechanisms and specificity determinants, offering a methodological reference for rational LTR-ligand design in LYTAC systems (Wu et al. 2024).

7.2. Insufficient flexibility in dynamic regulation and ratio optimization: the potential of supramolecular design

Second, conventional LYTAC architectures typically employ permanent covalent coupling between LTR ligands and POI binders with fixed stoichiometry, which limits adaptability under physiological conditions where receptor and target expression levels vary (Banik et al. 2020; Ahn et al. 2021; Zhou et al. 2021). Such rigid designs restrict fine-tuning of degradation efficiency and may exacerbate off-target uptake or safety liabilities when optimal LTR-POI ratios differ across tissues or disease states.

To address this limitation, supramolecular assembly strategies have been experimentally explored to decouple functional stoichiometry from irreversible covalent bonds. A representative example is the host-guest-based HGTAC platform, in which LTR-binding and POI-binding modules are assembled through reversible noncovalent interactions (Chen et al. 2025). In cellular models, this modular design enabled tunable control over complex formation by adjusting component ratios or interaction affinities, thereby modulating lysosomal trafficking and degradation outcomes. While still at an early stage, such supramolecular approaches provide a feasible route to introduce dynamic regulation into LYTAC systems, complementing more rigid covalent designs and expanding the toolbox for balancing efficacy and safety.

7.3. Degradation efficiency instability: optimizing binding mechanisms and endocytosis signals

The degradation efficiency of LYTAC is influenced by multiple factors, including receptor characteristics, molecular structure, endocytic transport, the inherent properties of the POI, and pharmacokinetics. Current research has made progress in optimizing ligands and delivery platforms. However, LYTACs often compete with abundant endogenous ligands on membranes and suffer from ‘hook effects’ due to imbalanced binding affinities between POIs and LTRs, reducing ternary complex formation and degradation efficiency (Banik et al. 2020; Zhang et al. 2022b). Furthermore, differences in endocytosis and transport mechanisms mediated by distinct LTRs remain poorly understood.

Beyond this, recent engineering advances in folate-drug conjugates offer novel strategies to balance POI/LTR affinity and optimize pharmacokinetics. For instance, Zheng conjugated the folate-targeted drug EC140 to an Fc protein at multiple sites. This achieved a high drug-to-antibody ratio (DAR 4.1), leveraged the Fc domain to extend systemic circulation (t1/2 ~28 h), and enhanced FR binding via multivalency. Such strategies of optimizing carriers and ligand chemistry through protein engineering provide valuable insights for designing LYTAC molecules with improved pharmacokinetics and enhanced targeting capability, thereby helping to overcome the hook effect and unstable degradation efficiency (Zheng et al. 2025). In parallel, incorporating endocytosis-enhancing elements such as HSP90 inhibitor fragments (Chen et al. 2025; Zhang et al. 2025b) or small-molecule chimeras (Chen et al. 2024) represents another experimentally supported route to stabilize lysosomal trafficking and degradation outcomes.

7.4. Tissue lack of targeting: enhancing specificity and disease-directed therapy

The existing LYTACs exhibit limited tissue selectivity, with LTRs often exhibiting non-specific distribution (Banik et al. 2020). Systemic administration readily leads to degradation of non-target cell POIs, while excessive LTR activation may impair normal function and induce drug resistance. Moreover, therapeutic requirements vary significantly across diseases: tumor treatment emphasizes tissue penetration and adaptation to the immune microenvironment (Cui et al. 2024; Su et al. 2024; Xu et al. 2024; Pan et al. 2025; Shi et al. 2025; Xing et al. 2025; Lin et al. 2025a, 2025b; Zhou et al. 2025a); neurodegenerative diseases demand BBB crossing (Liu et al. 2023; Howell et al. 2024; Wang et al. 2025); and autoimmune diseases rely more on specific tissue targeting (Pei et al. 2024).

Enhancing the tissue targeting of LYTACs necessitates moving beyond reliance on a single LTR and developing intelligent delivery systems capable of active navigation to disease sites. The work by Pei serves as a paradigm. To address the challenge of specifically targeting inflamed myocardium in viral myocarditis (VM), they designed an engineered EV integrating three distinct targeting modules. The strategy involved genetically engineering EVs to display a vMIP-II-Lamp2b fusion protein, coating EVs with platelet membranes, and conjugating a cardiac-targeting peptide. This coordinated ‘delivery navigation’ system significantly enhanced accumulation in inflamed cardiac tissue in vivo (Pei et al. 2024). For LYTAC technology, conjugation to similar multi-targeted and disease-microenvironment-responsive EVs (Pei et al. 2024; Yao et al. 2024) or nanocarriers together with complementary delivery platforms such as nanoparticles (Lu et al. 2023; Cui et al. 2024; Jiang et al. 2024; Yu et al. 2024; Xing et al. 2025; Lin et al. 2025b; Wang et al. 2023a), mRNA systems (Chang et al. 2025), hydrogels (Huang et al. 2024), engineered platelets (Chen et al. 2025), and cell engineering platforms (Su et al. 2024; Shi et al. 2025; Wang et al. 2023c; Zhang et al. 2025a), offers a practical route to improve tissue specificity and reduce systemic toxicity.

The integration of LYTAC technology with intracellular gene-regulatory strategies offers a promising avenue for systematic proteostasis intervention. Li et al. highlight that super-enhancers, as key transcriptional regulatory elements, drive high expression of oncogenes such as MYC, IL-6, and CD47 in digestive system tumors, which is closely linked to tumor proliferation, immune evasion, and chemoresistance. Studies confirm that small-molecule inhibitors targeting super-enhancer components like BET protein BRD4 or CDK7, such as JQ1 and THZ1, along with CRISPR-Cas9 gene-editing systems, can effectively suppress oncogenic transcription and reverse malignant phenotypes (Li et al. 2023). Combining LYTAC-mediated extracellular protein degradation with super-enhancer transcriptional modulation may establish a ‘transcription-degradation’ dual-track strategy, enabling more precise and multi-layered control of disease-related protein homeostasis.

7.5. Clinical translation bottlenecks: long-term safety and efficacy evaluation

Clinical translation remains a central bottleneck for LYTAC technology, largely because most studies to date have been confined to in vitro systems or short-term animal models. A major unmet need is the systematic evaluation of long-term safety, organ specificity, and immunocompatibility under repeated systemic administration, which is essential for assessing clinical feasibility beyond proof-of-concept degradation.

A further translational challenge lies in selecting appropriate degradation modalities for different target classes. For cell-surface or secreted proteins, alternative approaches such as AbTACs and PROTACs have demonstrated complementary strengths (Zhao et al. 2022). Strategic selection or rational combination of degradation pathways based on target biology and disease context may therefore be required to overcome the intrinsic limitations of any single modality and enable effective clinical translation of extracellular protein degradation strategies.

Within this landscape, ASGPR-GalNAc-based LYTACs currently represent the most clinically tractable platform for first-in-human (FIH) evaluation, owing to the hepatocyte-restricted expression of ASGPR and the extensive clinical precedent of GalNAc conjugates (An 2024). Accordingly, an initial LYTAC clinical program should be designed as a mechanism-driven Phase Ia study, prioritizing safety, human pharmacokinetics, and direct evidence of on-target lysosomal degradation rather than early efficacy.

Prior to clinical entry, IND-enabling studies should establish receptor-dependent uptake, dose-dependent POI degradation, and lysosomal trafficking in vitro and in vivo, together with repeat-dose toxicology in rodent and non-rodent species expressing functional ASGPR (Willoughby et al. 2018). Particular attention should be given to hepatic safety, immune activation, and the biological consequences of sustained receptor engagement. Pharmacokinetic-pharmacodynamic modeling that quantitatively links systemic exposure to the magnitude and duration of POI depletion is essential to support rational starting-dose selection.

The FIH study should enroll patients rather than healthy volunteers and adopt a single-ascending-dose followed by multiple-ascending-dose design. A MABEL-based approach is recommended to define the starting dose, targeting partial POI degradation (e.g. 10-20%) to mitigate risks associated with irreversible protein clearance. Intravenous administration allows maximal control in early trials, with dosing intervals guided by POI recovery kinetics and receptor recycling. Safety monitoring should emphasize hepatic biomarkers, cytokine release, complement activation, and anti-drug antibody formation, while pharmacodynamic evaluation should directly quantify POI depletion using serum-based assays or tissue biopsies where feasible (Zhang et al. 2022a). Collectively, this integrated framework consolidates the clinical translation potential of LYTACs into a coherent and actionable pathway toward human studies. To integrate the current preclinical evidence landscape of LYTAC development, a comparative overview of representative degradation platforms, including payload formats, tissue specificity, efficacy, and safety observations, is summarized in Table 3.

Table 3.

Comparative overview of representative LYTAC-based degradation platforms.

Platforms	Payloads	Cell/Tissue specificity	Preclinical efficacy	Toxicity data
LYTAC	Antibodies (e.g. Cetuximab, Atezolizumab)	Broad (CI-M6PR expression)	80-90% degradation of EGFR (10 nM, 48 h) in Hep3B cells; significant PD-L1 reduction (25 nM) in HDLM-2 cells.	5 mg/kg i.p. in mice showed stable PK; no acute systemic toxicity reported.
iLYTAC	Recombinant Proteins/IgG binders	Broad (CI-M6PR expression)	Efficient degradation of EGFR and HER2 at 10-100 nM; ‘Off-the-shelf’ IgG compatibility.	Higher biocompatibility than chemical LYTACs; no immunogenicity risk.
sLYTAC	Antibodies/Binders	Targeting Drug-resistant tumor	Strong degradation at 10 nM; effectively inhibits drug-resistant tumor cell growth.	Eliminated IGF1R binding to avoid potential oncogenic risks of WT-IGF2.
GELYTAC	Genetically encoded binders	Broad (CI-M6PR expression)	Secreted from primary T-cells; drives target uptake and degradation in receiver cells via directed evolution.	Genetically encodable; allows localized delivery, reducing systemic off-target risks.
GalNAc-LYTAC	Small molecules/Antibodies	Hepatocytes (ASGPR expression)	10 nM concentration mediates EGFR degradation in Hep3B; liver-specific uptake at 5 mg/kg in vivo.	Liver-specific; no accumulation in spleen or other organs, showing high safety.
MoDE-A	Bifunctional small molecules	Hepatocytes (ASGPR expression)	>80% clearance of circulating antibodies (α-DNP) within 24 h at doses as low as 0.1 mg/kg.	AST/ALT levels remained in the normal range, indicating no hepatotoxicity.
LYTEX	Multivalent scFvs	Tumor/Liver (ASGPR expression)	Efficient lysosomal degradation of PD-L1 and HER2 via multivalent antibody-expressing exosomes.	High biocompatibility (natural vesicles); multivalent binding enhances target precision.
KineTAC	Cytokines (CXCL12, IL-2)	CXCR7 + cells or T cells	> 70% degradation of cell-surface PD-1 on primary T cells (100 nM, 24 h). Efficiently uptake 25 nM TNFα via CXCR7.	Leverages ‘decoy’ receptors (CXCR7) that lack signaling, reducing systemic side effects.
ITAC	cRGD peptide-Ab conjugates	Cancer/Vascular specific (Integrins αvβ3 expression)	Dose-dependent degradation of HER2 and CD20; significant depletion observed in αvβ3-overexpressing cells.	Cyclic RGD shows high affinity with minimal impact on normal cell viability.
ITGBAC	Bispecific Aptamers	ITGA3B1-rich cells	Efficiently eliminated CD71 and Met membrane proteins; demonstrated significant therapeutic potential in tumor models.	Aptamer-based design ensures low immunogenicity and good tissue penetration.
DENTAC	Dendritic DNA-protein conjugates	SR-expressing cells	Successfully degraded NCL and EGFR; validated in a lung cancer mouse xenograft model.	Dendronized DNA structures are biocompatible and stable in physiological conditions.
LYTACA	Self-assembling peptides	Macrophages/Skin lesions (SR-A expression)	Reduced IL-17A levels in skin lesions of a psoriasis mouse model, alleviating inflammation.	Non-toxic, modular supramolecular system; localized effect in psoriasis-like skin.
DePLTs	Engineered Platelets (HSP90-labeled)	Wound/Tumor Selective (LRP-1 expression)	Effectively degraded intracellular BRD4 and extracellular PD-L1; significantly inhibited tumor growth in post-surgical breast cancer models.	Leveraging autologous-like platelets minimizes systemic distribution and reduces off-target biosafety concerns.
eHSPTAC	Bifunctional small molecules	Tumor-specific (High eHSP90)	Achieved dose-dependent degradation of PD-L1; selectively targeted tumor cells over normal cells.	Enhanced safety: eHSP90 is primarily localized in the tumor microenvironment, minimizing systemic toxicity.
GLP-1-LYTAC	GLP-1 peptide-ligand conjugates	Incretin receptor + cell	Successfully mediated degradation of EGFR and PD-L1 in GLP-1R-overexpressing cells at nanomolar concentrations.	GLP-1R is a clinically validated target; conjugates show good biocompatibility in metabolic-related tissues.
GFLD	Glucose-ligand conjugates	Cancer Metabolism Specific (Glut1 expression)	~85% degradation of PD-L1 in lung cancer cells (A549) by exploiting high glucose transporter expression.	Protects normal tissues with low glucose demand; demonstrates high metabolic selectivity in vivo.
FRTAC	Folate-ligand conjugates	Cancer Selective (FRα expression)	Robustly degraded soluble and membrane-associated HER2 and EGFR in vitro and in vivo.	Precision medicine: FRα is limited in healthy tissues but overexpressed in tumors, providing a wide therapeutic window.
TfR-LYTAC	OMV-fused chimeric proteins	Tumor & Immune cells (TfR1 expression)	Effective PD-L1 degradation via engineered bacterial OMVs; combined with immune activation to suppress tumor growth in vivo.	OMVs act as adjuvants; localized tumor targeting reduces systemic cytokine storm risks.
Pep-TAC	Covalent peptides (Aryl sulfonyl fluoride)	TfR1-rich tumors	Significant PD-L1 degradation on tumor cells and macrophages; enhanced efficacy under acidic conditions.	Covalent binding increases residence time, allowing lower dosing and reduced systemic exposure.
TransTAC	Heterobispecific antibodies	Cancer-enhanced (TfR1 expression)	Efficiently degrades EGFR, PD-L1, CD20, and CAR; enables reversible control of CAR-T cell activity.	Exploits fast recycling rate of TfR1; well-tolerated in preclinical models with high target precision.
GLTAC	Antibody-recruiting chimeras	HCC Specific (GPC3 expression)	Selectively degraded PD-L1 in GPC3-positive liver cancer cells (HepG2); minimal effect on GPC3-negative cells.	Highly selective: GPC3 is a tumor-specific antigen, ensuring minimal off-target toxicity in healthy tissues.
MedTAC	mRNA-encoded modular binders	Precision/Malignancy-specific (Sortilin expression)	Single low dose (0.5 mg/kg) reduced PTK7 levels by 80% within 24 h; sustained 44% degradation at 72 h.	Excellent safety: Sortilin is minimally expressed in healthy tissues outside the nervous system; survival extended > 50 days.
SignalTAC	Signal peptide-fused antibodies	Broad (CI-M6PR expression)	Effectively degraded EGFR (70%) and CD20; bypassed the need for large glycan modifications.	Reduced complexity compared to glycan-LYTACs; shows minimal immunogenicity in preliminary assays.
VED-LYTAC	Bispecific Aptamers	Hepatocyte Specific	Achieved > 60% degradation of EGFR in HepG2 cells; simpler synthesis than antibody-GalNAc conjugates.	High biocompatibility and faster clearance, reducing long-term systemic exposure risks.
Apt-LYTAC	VEGF-targeting aptamer chimeras	Retinal/Ocular Selective (CI-M6PR expression)	Significant degradation of VEGF; reduced retinal neovascularization area in mice model.	Targeted ocular delivery minimizes systemic side effects compared to systemic anti-VEGF drugs.
TDA-MLYTAC	Tetrahedral DNA Nanostructures (Multivalent)	Enhanced Hepatocyte Targeting (ASGPR expression)	Improved stability and uptake; dual-target degradation of EGFR and PD-L1 simultaneously.	DNA nanostructures are biodegradable; demonstrated no obvious liver or kidney damage in vivo.
TDF-LYTAC	ATP-responsive DNA framework	Metabolism-responsive (CI-M6PR expression)	Mediated PDGF degradation; correlated degradation efficiency with intracellular ATP fluctuations.	High precision: degradation is facilitated by the cell's internal energy state, adding a layer of safety.
AuNP-APTAC	Hypervalent gold nanoparticles	MDR Cancer Cells (ASGPR expression)	~80% ABCG2 degradation in vitro; reversed multidrug resistance effectively.	Low cytotoxicity at 10 nM; high biocompatibility of gold core.
NanoCLY	Self-assembled peptides	TME-responsive (CI-M6PR expression)	~85% CTGF reduction in vivo; tumor inhibition rate >70% in TNBC models.	Minimized on-target toxicity in normal tissues; safe at 10 mg/kg.
mNbTAC	Circular multivalent nanobodies	Heterogeneous Tumors (SR expression)	TIR reached 90% in vivo; simultaneous degradation of PD-L1 & HER2.	Reduced cardiotoxicity of Doxorubicin via targeted delivery.
IMTAC	Modular DNA origami	pH-Responsive at pH 6.5 (CI-M6PR expression)	Modular degradation of EGFR/PD-L1 in vivo; precision targeting in TME.	Zero systemic immune activation; no off-target effects at pH 7.4.
NLTC	Catalase encapsulated nanoplatform	Tumor-Selective (CI-M6PR expression)	Significant PD-L1 degradation; CD8+ T cell infiltration increased ~2.5 fold.	Avoided on-target off-tumor toxicity in lung and liver; tumor-specific activation.
GlueTAC	Covalent nanobodies	Antigen-specific (ASGPR expression)	Dose of 10 mg/kg led to significant PD-L1 degradation and inhibited tumor growth in MC38 models.	Covalent stabilization reduces off-target dissociation; no systemic weight loss was observed in mice.
MONOTAB	Modified Nanoparticles	Plug-and-Play, Receptor-Independent	By leveraging innate nanoparticle endocytosis, this platform achieved 70-80% PCSK9 and EV degradation while bypassing receptor saturation.	Eliminates hook effect; PLGA carrier exhibits excellent biocompatibility and low immunogenicity.
endoTAC	Polyvalent nano-chimera	Brain/AD-specific	Polyvalent interactions reduced brain RAGE levels by ~60% in AD mice, leading to marked cognitive improvements in water maze tests.	Reduced neuroinflammation by lowering IL-1β and TNF-α levels; targeted brain delivery minimizes peripheral exposure.
PSMLTAC	Small molecule-peptide conjugates	Membrane & Intracellular (LRP1 expression)	Demonstrated potent degradation of PD-L1 with a DC50 of 0.28 μM, outperforming traditional PROTACs in both membrane and intracellular PDE5 degradation.	Peptide-mediated entry showed no significant toxicity in healthy cell lines; selective for diseased cells.
Supra-LYTAC	Supramolecular nanofibers	Cancer-specific (Hypoxia)	Achieved spatiotemporal degradation of target proteins in CAIX-overexpressing tumors; supramolecular structures enhanced target residence time via multivalent binding.	Dynamic assembly ensures tumor-triggered activation, reducing off-target effects in normoxic tissues.
TransMoDEs	Bifunctional small molecules	Brain & BBB-crossing (LRP1 expression)	Simultaneously induced lysosomal degradation and transcytosis of target proteins in brain cells, offering a dual mechanism for CNS protein clearance.	High BBB permeability allows lower effective dosing in the brain, thereby reducing peripheral side effects.
Logic-TAC	DNA logic circuits	Cancer-Selective (ASGPR/CI-M6PR expression)	Achieved >80% MUC1 degradation in MCF-7 cells. The dual-antigen logic gating ensures activation occurs exclusively in cancer cells.	Minimized side effects on normal MCF-10A cells due to the sealed recognition regions.
HGTAC	Host-guest assemblies (CD-Ad)	Tunable & Modular (ASGPR expression)	Utilizing β-CD/adamantane interactions, it achieved tunable degradation of EGFR and HER2, featuring a recyclable host module for sustained activity.	Tunable stoichiometry allows for fine-tuning of degradation efficiency, avoiding over-degradation.
multi-TAC	Acid-responsive copolymers	Tumor-Targeted (pH)	pH 6.5, multivalent adsorption facilitated >85% PD-L1 degradation, significantly outperforming monovalent small molecules.	pH-triggered activation limits degradation to the tumor site; good systemic biocompatibility.
KPLYs	PiB-derived multifunctional NPs	AD-Lesion Specific	Induced ~65% clearance of extracellular β fibrils in AD mouse brains, reducing navigation time in cognitive tests by 30%. Activated in situ by β-Cu complexes in AD lesions, it selectively degraded extracellular fibrils and reversed cognitive decline.	ROS scavenging and M2 polarization of microglia help to mitigate neuroinflammation during degradation.
PT-LYTAC	Photoactive aptamer chimeras	Spatially Controlled (CI-M6PR expression)	After 10 min of 660 nm NIR irradiation, ~75% EGFR degradation was achieved within 6 h.	Minimal dark toxicity; NIR light provides deep tissue penetration with low heat damage to normal tissues.
Nano-LYTAC	Polymeric sonosensitizer NPs	Immune Cell Targeting (CI-M6PR expression)	With low-intensity ultrasound, it reduced M2 macrophages by 50% and tripled the population of CD8+ T cells in the TME.	Synergistic safety: Low-intensity ultrasound ensures localized activation; the polymeric carrier is highly biodegradable.

8. Perspectives on future development directions

With the foundational feasibility of LYTAC-mediated extracellular protein degradation now established, future progress will depend on addressing a set of prioritized scientific and technological questions that extend beyond individual molecular designs. A central direction is the systematic dissection of receptor-ligand-cargo interactions at the quantitative and structural levels. High-resolution structural biology, together with biophysical and cellular assays, will be essential to clarify binding hierarchies, competitive interactions with endogenous ligands, and stoichiometric constraints that govern productive lysosomal trafficking.

Another critical direction lies in advancing LYTACs from static constructs toward dynamically regulated systems. Future studies should prioritize platforms that enable tunable assembly, temporal control, or conditional activation in response to disease-associated cues. Approaches such as supramolecular host-guest systems, genetically encoded degraders, and environmentally responsive designs provide opportunities to overcome fixed stoichiometry, hook effects, and context-dependent variability in receptor or target expression.

In parallel, improving tissue and disease specificity remains a key developmental priority. Beyond reliance on single lysosome-targeting receptors, future research should explore multi-layered targeting strategies that integrate receptor selection with delivery platforms capable of active navigation within complex in vivo environments. Engineered nanoparticles, extracellular vesicles, mRNA-based systems, and cell-derived carriers offer modular frameworks for coordinating targeting ligands, degradation modules, and environmental responsiveness, thereby reducing off-target exposure and systemic toxicity.

Finally, future development should increasingly adopt a systems-level perspective on proteostasis intervention. Rather than viewing extracellular protein degradation in isolation, integrating LYTAC-based approaches with intracellular regulatory strategies (such as transcriptional modulation or signaling pathway control) may enable multi-dimensional regulation of disease-associated protein networks. Collectively, these directions emphasize that the next phase of LYTAC research will be defined not by incremental improvements in degradation potency, but by the rational integration of structure, dynamics, targeting logic, and system-level control to support robust and predictable therapeutic outcomes.

9. Conclusion

Overall, TPD technology based on the endocytosis-lysosomal pathway offers a novel approach to overcoming the limitations of ‘undruggable’ proteins. However, multiple challenges remain in molecular design, degradation efficiency, tissue specificity, and clinical translation. With the continuous emergence of novel ligands, delivery systems, and controllable strategies, these issues are expected to be gradually resolved. Furthermore, the synergistic application of this technology with other degradation methods and therapeutic approaches opens broader prospects for future clinical translation. It is foreseeable that, with deepening basic research and optimized engineering approaches, LYTAC and its derivative platforms will demonstrate greater application potential in disease treatment.

Funding Statement

This work was supported by the National Natural Science Foundation of China (82372102), Traditional Chinese Medicine science and Technology Project of Shandong Province (Z20241405) and Taishan Scholar Project of Shandong Province of China (tsqn202103200).

Acknowledgements

Y.M Ma drafted the manuscript and drew the figures. Y. L. Xiao, Z.L Yu and Y.M Ma discussed and revised the manuscript. Z.L Yu designed the study. All authors agree to be accountable for the content of the work.

Disclosure statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Permission from the copyright holder to reproduce figures have been obtained.

Data availability statement

Data availability is not applicable to this article as no new data were created or analyzed in this study.