Cellular homeostasis depends critically on the controlled degradation of proteins. Cells employ an intricate waste-disposal system to ensure that obsolete or harmful proteins are tagged for destruction and subsequently dismantled by specialized enzymes. Exploiting this natural process, molecular glues function by bridging proteins that do not normally interact, guiding harmful proteins toward degradation pathways. This elegant strategy offers an unprecedented level of selectivity and therapeutic potential, particularly for proteins that evade conventional drug targeting.

Historically, the identification of molecular glues has been serendipitous, limiting efficient exploitation across diverse therapeutic landscapes. Addressing this, a team led by Georg Winter, Scientific Director at the AITHYRA Research Institute and Adjunct Principal Investigator at CeMM in Vienna, alongside Michael Erb from the Scripps Research Institute, developed an innovative high-throughput chemical diversification technique paired with live-cell functional screening. This approach enables the rapid exploration of vast chemical modifications on an initial small molecule scaffold, uncovering variants that effectively reshape protein surfaces to foster new protein-protein interactions.

This methodology involves synthesizing thousands of molecular variants by systematically appending diverse chemical building blocks to a known protein ligand. Each variant subtly alters the ligand’s interface, potentially fostering novel contacts between the target protein and cellular degradation enzymes. Crucially, the screening is conducted in live cells without prior compound purification, using sensitive assays that report real-time degradation of the protein target. This fusion of chemical synthesis and cellular biology allows researchers to pinpoint active compounds with genuine biological efficacy from enormous chemical spaces in a highly efficient manner.

The researchers applied this cutting-edge approach to the leukemia-associated protein ENL, a critical regulator in certain aggressive forms of acute leukemia. Screening thousands of ligand derivatives led to identifying a compound that selectively induces robust degradation of ENL in leukemia cells. Subsequent investigations demonstrated that this compound reprograms the protein’s interaction landscape, promoting recruitment of a ubiquitin ligase complex responsible for tagging ENL with ubiquitin molecules, effectively marking it for destruction by the proteasome.

Fundamental to the activity of these compounds is their cooperative binding mechanism, a hallmark of molecular glues. Rather than indiscriminately binding to both partners, the molecule binds the target protein first, then facilitates a new interface that recruits the enzymatic degradation machinery. This mechanism underpins both the specificity and efficacy of the induced protein degradation, minimizing off-target effects and enhancing therapeutic potential.

The successful targeted degradation of ENL elucidates the enormous promise held by molecular glue technology. By precisely ablating proteins driving leukemia progression, this approach curtails malignant cell growth and opens pathways for new leukemia treatments with potentially fewer side effects compared to current therapies. Moreover, the demonstration that high-throughput ligand diversification and functional screening can yield such potent glues paves the way for broad applications across a spectrum of diseases.

The implications of this work extend far beyond ENL and leukemia. The generalizable workflow combining scalable chemical innovation with phenotype-based cellular screening transforms the paradigm of proximity-inducing drug discovery. Where once the hunt for molecular glues was slow and hit-or-miss, it can now be approached rationally with vast chemical libraries tested directly in biological contexts, accelerating the translation from molecule to medicine.

Georg Winter emphasizes that this breakthrough sets the foundation for a new era in drug design, making it feasible to target proteins, once deemed ‘undruggable,’ with small molecules that enlist the cell’s own degradation machinery for therapeutic benefit. This extends the druggable proteome dramatically, enabling intervention in diseases where pathogenic proteins have historically eluded pharmacological control.

Furthermore, the integration of artificial intelligence and next-generation automated chemistry platforms at institutions like AITHYRA will likely amplify this approach’s efficiency and breadth. The convergence of AI-driven design, robotic synthesis, and live-cell functional assays creates a powerful ecosystem to systematically identify molecular glues tailored to diverse therapeutic targets, accelerating drug discovery timelines significantly.

As molecular glues gain traction in both academic and pharmaceutical sectors, the strategy heralded by this study could revolutionize how diseases such as cancer, neurodegeneration, and viral infections are treated. Through rational, scalable ligand diversification paired with cell-based functional screening, there is newfound optimism that targeted protein degradation can become a mainstay of precision medicine, offering customized therapies with high specificity and minimal side effects.

This landmark study, published in Nature Chemical Biology, underscores the transformative potential of combining high-throughput chemistry with live-cell biology to unlock new drug modalities. The systematic discovery of molecular glues not only represents a technical tour de force but also a conceptual leap forward, fostering a deeper understanding of protein interactions and cellular degradation pathways that can be leveraged for therapeutic innovation.

The impact of these findings is already resonating through the scientific community, evoking excitement about the possibilities molecular glues hold for treating a vast array of diseases. As this platform matures, it promises to illuminate previously dark corners of the proteome, making the impossible task of targeting elusive proteins a tangible reality.

Subject of Research: Cells

Article Title: High-throughput ligand diversification to discover chemical inducers of proximity

News Publication Date: February 16, 2026

Web References:
https://doi.org/10.1038/s41589-025-02137-2

References:
Shaum JB, Muñoz i Ordoño M, Steen EA, et al. High-throughput ligand diversification to discover chemical inducers of proximity. Nature Chemical Biology. 2026; DOI:10.1038/s41589-025-02137-2.

Image Credits: © Miquel Muñoz

Keywords: Leukemia, Proteins, Molecular glues, Targeted protein degradation, High-throughput screening, Chemical biology, Drug discovery, Acute leukemia, Ubiquitin ligase, ENL protein

Traditional drug development often hinges on the ability of small molecules to directly inhibit enzymatic activity or protein-protein interactions. However, many pathogenic proteins lack druggable pockets, rendering them refractory to classical inhibition. The field of targeted protein degradation circumvents this obstacle by co-opting the cell’s intrinsic protein quality control machinery to selectively eliminate target proteins. As such, molecules known as “degraders” recruit E3 ubiquitin ligases to the target protein, triggering ubiquitination and subsequent proteasomal degradation. While the concept is powerful, identifying effective degraders remains a significant bottleneck due to limitations in screening technologies and the structural complexity of induced-proximity interactions.

Addressing these challenges head-on, the DEFUSE platform redefines the screening paradigm by converting protein degradation into a phenotypic readout of cell survival. The technique ingeniously fuses the protein of interest to a rapid-acting, inducible death protein. In cells expressing this fusion construct, degradation of the target protein disrupts the death protein’s function, thereby rescuing the cell from induced apoptosis. Consequently, the survival of cells under selective pressure becomes an unequivocal indicator of effective targeted degradation. This switch from traditional biochemical assays to a survival-based, high-throughput cellular assay enables rapid and sensitive detection of functional degraders.

Applying DEFUSE to the oncoprotein SKP2, the researchers discovered a novel small molecule, SKPer1, that potently and selectively induces degradation of SKP2. SKP2 is a vital component of the SCF (SKP1-CUL1-F-box protein) E3 ligase complex and has been widely implicated in cancer pathogenesis through its regulation of cell cycle progression and degradation of tumor suppressors such as p27Kip1. Overexpression of SKP2 frequently correlates with poor prognosis in multiple malignancies, making it a highly attractive yet elusive therapeutic target. SKPer1’s ability to specifically eliminate SKP2 confirms the power of DEFUSE in unearthing potent molecular glues that prompt simultaneous interaction of SKP2 with the E3 ligase STUB1, culminating in targeted ubiquitination and proteasomal clearance.

Mechanistically, SKPer1 functions as an induced-proximity degrader, a subclass of targeted degraders that act by physically bridging the target protein with an E3 ligase that otherwise does not interact under normal cellular conditions. This strategy not only broadens the range of E3 ligases that can be harnessed for degradation but also exemplifies the subtleties of molecular glue chemistry in drug discovery. The study expands our understanding of induced proximity effects, demonstrating that carefully engineered small molecules can initiate protein-protein interactions previously uncharacterized, thereby reprogramming cellular ubiquitination pathways with high specificity.

The therapeutic implications of SKPer1 were rigorously validated both in vitro and in vivo. In cellular models, SKPer1 treatment led to a marked reduction in SKP2 protein levels accompanied by decreased proliferative capacity specifically in SKP2-expressing cancer cell lines. Importantly, this degradation translated to selective cytotoxicity, highlighting the molecule’s precision and minimal off-target effects. Animal studies corroborated these findings, where SKPer1 administration achieved significant tumor growth suppression with an encouraging safety profile. This preclinical success underscores SKPer1’s potential as a lead candidate for further drug development, offering hope for combating refractory cancers driven by SKP2 dysregulation.

Beyond the discovery of SKPer1, the DEFUSE platform unveiled an additional innovative insight: a ten-amino acid sequence derived from SKP2 can be leveraged as a modular degradation tag. This peptide sequence serves as a versatile handle that, when fused to other proteins, confers susceptibility to the SKPer1-induced degradation machinery. Such a tool represents a powerful new methodology for conditionally controlling protein stability, offering avenues for both basic research applications and therapeutic development, including the design of bespoke protein degradation systems tailored to diverse targets.

The imaging-based nature of DEFUSE is particularly compelling, as it allows rapid visualization and quantification of degradation events through fluorescence microscopy, enabling screens to be conducted efficiently on large chemical libraries. This contrasts with many existing approaches that rely on indirect or low-throughput assays, thus positioning DEFUSE as a scalable solution for accelerated drug discovery pipelines. The high sensitivity and specificity of the system ensure that identified hits are physiologically relevant degraders, increasing the likelihood of downstream translational success.

Furthermore, DEFUSE’s modular design is adaptable to any protein of interest, broadening its applicability across a spectrum of disease-related proteins. By harnessing different death effector domains, the method could be customized to optimize readouts in various cell types or contextual environments, thereby expanding the potential target space for induced-proximity degraders. In essence, DEFUSE represents a bridge between molecular biology innovation and chemical biology screening, providing a transformative toolkit to decode and exploit protein degradation pathways.

The discovery of SKPer1 also highlights the importance of E3 ligase diversity in degrader design. While many prototypical degraders utilize well-characterized E3 ligases such as cereblon or VHL, SKPer1’s recruitment of STUB1 uncovers new molecular relationships and underscores the therapeutic value of targeting underexplored components of the ubiquitin-proteasome system. This diversification could mitigate resistance mechanisms and expand degrader efficacy across different disease contexts.

Importantly, the study also emphasizes the relevance of induced-proximity pharmacology—where the small molecule acts as a molecular matchmaker rather than a conventional active site binder. This paradigm shift challenges traditional medicinal chemistry approaches and calls for a deeper integration of structural biology, proteomics, and chemical design to optimize molecular glue degraders. The findings from DEFUSE and SKPer1 thus provide critical proof-of-concept evidence for this promising therapeutic strategy.

Taken together, this work provides a blueprint for future efforts aiming to explore the vast “degradable” proteome. The convergence of innovative screening technology, mechanistic insights into induced proximity, and tangible therapeutic success propels the field of targeted protein degradation into a new era. As the scientific community continues to dissect the underlying biology and refine the chemical tools, approaches like DEFUSE could become standard in the drug discovery toolbox, accelerating the development of first-in-class therapies against challenging disease targets.

In conclusion, the development of the DEFUSE screening platform and the identification of SKPer1 as a potent degrader of the oncogenic SKP2 exemplify the transformative power of modern protein degradation technologies. By translating biochemical degradation events into a robust cell survival phenotype and harnessing induced-proximity effects, this study illuminates previously inaccessible facets of drug discovery. The integration of these advancements promises to redefine therapeutic intervention strategies for cancer and beyond, heralding a new wave of precision medicines tailored to manipulate the proteome at will.

This pioneering research not only expands the frontiers of targeted degradation but also sets a precedent for future high-throughput approaches that blend biological ingenuity with chemical innovation. As the global community strives to conquer disease at the molecular level, platforms like DEFUSE and discoveries like SKPer1 represent beacon technologies that will shape the landscape of precision oncology and molecular pharmacology for years to come.

Subject of Research: Targeted protein degradation technology and discovery of small-molecule degraders for oncogenic proteins

Article Title: A rapid imaging-based screen for induced-proximity degraders identifies a potent degrader of oncoprotein SKP2

Article References:
Chu, Y., Chen, S., Yang, M. et al. A rapid imaging-based screen for induced-proximity degraders identifies a potent degrader of oncoprotein SKP2. Nat Biotechnol (2025). https://doi.org/10.1038/s41587-025-02793-8

Image Credits: AI Generated

Traditional cancer therapies often rely on broad mechanisms such as chemotherapy or checkpoint inhibition, which can lead to severe side effects and variable patient responses. Against this backdrop, targeted protein degradation has emerged as a promising strategy, harnessing the cell’s natural machinery to selectively eliminate disease-causing proteins. Molecular glues are small molecules that facilitate novel interactions between a target protein and an E3 ubiquitin ligase, marking the target for destruction. However, designing molecular glues with high specificity has been notoriously challenging due to the complex and intertwined structural landscapes involved.

PVTX-405 distinguishes itself by selectively binding to IKZF2, a transcription factor that plays a pivotal role in immune regulation and cancer cell survival. IKZF2, also known as Helios, is part of the Ikaros family of zinc finger proteins involved in lymphocyte development and function. Aberrant regulation of IKZF2 has been implicated in the immune evasion mechanisms of various tumors, making it an attractive, yet difficult, therapeutic target. The molecular glue mechanism employed by PVTX-405 recruits IKZF2 to a specific E3 ubiquitin ligase complex, triggering its degradation, thereby dismantling malignant cells’ evasion capabilities and potentiating immune system activity against the cancer.

The study details a comprehensive suite of biochemical, structural, and cellular assays that elucidate the mechanism of PVTX-405’s interaction with IKZF2 and the E3 ligase. The researchers used high-resolution cryo-electron microscopy and X-ray crystallography to map the binding interface, revealing how PVTX-405 induces a stable ternary complex between IKZF2 and the E3 ligase. This intricate molecular choreography results in ubiquitination of IKZF2 and subsequent proteasomal degradation. Crucially, the compound does not promote the degradation of closely related Ikaros family members, highlighting its exceptional selectivity—a major milestone for molecular glue technology.

One of the most compelling features of PVTX-405 is its ability to circumvent the common problem of acquired resistance seen with other targeted therapies. By inducing degradation rather than merely inhibiting function, the compound reduces the likelihood of compensatory mechanisms that allow cancer cells to persist. Furthermore, the selective nature of PVTX-405 minimizes off-target effects, potentially reducing the adverse immune-related toxicities seen with conventional immunotherapies.

In cell-based models, treatment with PVTX-405 resulted in robust degradation of IKZF2, leading to a marked reduction in tumor cell proliferation. Immune effector assays demonstrated enhanced anti-tumor cytotoxicity in the presence of PVTX-405, suggesting that degradation of IKZF2 reprograms the tumor microenvironment to favor immune-mediated clearance. These outcomes were corroborated in murine models of several hematologic malignancies, where the compound showed potent anti-cancer effects without inducing significant systemic toxicity.

The therapeutic implications of PVTX-405 extend beyond hematologic cancers. IKZF2 has been associated with regulatory T-cell function, which contributes to immunosuppressive networks within solid tumors. By selectively degrading IKZF2, PVTX-405 has the potential to modulate these immunosuppressive circuits, opening avenues for combinatory regimens with checkpoint inhibitors or adoptive cell therapies in refractory solid tumors. The strategic targeting of transcription factors, traditionally considered “undruggable,” through molecular glue mediators like PVTX-405, heralds a new chapter in overcoming tumor immune escape.

Another critical aspect of the research was the meticulous optimization of PVTX-405’s pharmacokinetic and pharmacodynamic properties. Structure-activity relationship analyses facilitated the refinement of the molecule for improved bioavailability, metabolic stability, and tissue distribution—all essential parameters for clinical translation. The compound’s oral bioavailability and favorable half-life position it as a practical candidate for long-term treatment regimens, enhancing patient compliance and therapeutic impact.

Despite the exciting preclinical data, several hurdles remain before PVTX-405 can be fully integrated into clinical practice. The authors highlight the need for comprehensive toxicology studies to assess potential immune-related side effects in humans. Moreover, understanding the long-term consequences of sustained IKZF2 depletion on normal immune homeostasis is essential to mitigate risks of autoimmunity or immunodeficiency. Nonetheless, the precise targeting mechanism underlying PVTX-405 provides a strong foundation for rational design of next-generation molecular glues with improved safety profiles.

This study also underscores the vital role of interdisciplinary collaboration in drug discovery. Integrating computational modeling, chemical biology, structural biochemistry, and immunology enabled a holistic approach to optimizing PVTX-405’s efficacy and selectivity. The iterative feedback between experimental data and molecular design exemplifies how modern biomedical research can rapidly accelerate the translation of novel compounds from bench to bedside.

PVTX-405’s discovery reiterates the transformative potential of targeted protein degradation as a therapeutic paradigm. Unlike classical inhibitors that rely on occupancy and reversible binding, molecular glue degraders exploit the cell’s quality control machinery to achieve sustained protein knockdown. This paradigm shift may allow clinicians to overcome resistance mutations that impair target binding, a persistent challenge in precision oncology.

A particularly fascinating aspect of this work is the elucidation of the molecular glue’s capacity to induce novel protein-protein interactions. By bridging IKZF2 and an E3 ligase that do not normally interact, PVTX-405 exemplifies the power of small molecules to expand the “interactome” landscape within cells. This concept not only enhances druggable targets but also promotes discovery of cryptic regulatory pathways amenable to chemical intervention.

PVTX-405’s ability to toggle immune effector functions through targeted degradation suggests exciting applications beyond oncology. Autoimmune diseases, chronic infections, and other immune dysregulation disorders could benefit from similarly engineered molecular glues that rewire immune signaling networks in a controlled and reversible manner. The modular nature of molecular glues opens considerable scope for broadening this therapeutic class across diverse disease spectra.

From a commercial and clinical perspective, PVTX-405 represents a compelling asset with significant market potential. The demand for efficacious and tolerable cancer immunotherapies continues to grow, invigorated by advances in immuno-oncology. If successful in clinical trials, PVTX-405 could fill a critical niche where current therapies fail or induce harmful immune-related adverse events, ultimately improving patient survival and quality of life.

In summary, the development of PVTX-405 as a potent, selective molecular glue degrader of IKZF2 is a landmark achievement in cancer immunotherapy research. It exemplifies the convergence of cutting-edge science and therapeutic innovation, offering a novel weapon in the arsenal against cancer. As the research community continues to unravel molecular glue mechanisms and expand their application, PVTX-405 stands as a beacon of hope for more effective, targeted, and less toxic treatments in oncology and beyond.

Subject of Research: Development of a selective molecular glue degrader targeting IKZF2 for cancer immunotherapy.

Article Title: Development of PVTX-405 as a potent and highly selective molecular glue degrader of IKZF2 for cancer immunotherapy.

Article References:
Chen, Z., Dhruv, H., Zhang, X. et al. Development of PVTX-405 as a potent and highly selective molecular glue degrader of IKZF2 for cancer immunotherapy. Nat Commun 16, 4095 (2025). https://doi.org/10.1038/s41467-025-58431-z

Image Credits: AI Generated