Chimeric Molecules Research Articles

Design, construction and in vivo functional assessment of a hinge truncated sFLT01.

Gene therapy for the treatment of ocular neovascularization has reached clinical trial phases. The AAV2-sFLT01 construct was already evaluated in a phase 1 open-label trial administered intravitreally to patients with advanced neovascular age-related macular degeneration. SFLT01 protein functions by binding to VEGF and PlGF molecules and inhibiting their activities simultaneously. It consists of human VEGFR1/Flt-1 (hVEGFR1), a polyglycine linker, and the Fc region of human IgG1. The IgG1 upper hinge region of the sFLT01 molecule makes it vulnerable to radical attacks and prone to causing immune reactions. This study pursued two goals: (i) minimizing the immunogenicity and vulnerability of the molecule by designing a truncated molecule called htsFLT01 (hinge truncated sFLT01) that lacked the IgG1 upper hinge and lacked 2 amino acids from the core hinge region; and (ii) investigating the structural and functional properties of the aforesaid chimeric molecule at different levels (in silico, in vitro, and in vivo). Molecular dynamics simulations and molecular mechanics energies combined with Poisson-Boltzmann and surface area continuum solvation calculations revealed comparable free energy of binding and binding affinity for sFLT01 and htsFLT01 to their cognate ligands. Conditioned media from human retinal pigment epithelial (hRPE) cells that expressed htsFLT01 significantly reduced tube formation in HUVECs. The AAV2-htsFLT01 virus suppressed vascular development in the eyes of newborn mice. The htsFLT01 gene construct is a novel anti-angiogenic tool with promising improvements compared to existing treatments.

Abstract LB218: A safe and highly potent anti-PD-1-IL-2c fusion that decouples efficacy and toxicity of IL-2 therapy

Abstract Interleukin 2 (IL-2) is a pivotal immune agonist for tumor immunotherapy that has produced impressive clinical efficacy in a number of cancer types. Nevertheless, its pleiotropic effect has led to prohibitory side effects and immune restraint. In contrast, the PD-1 blockade-based cancer immunotherapy has a good safety profile by targeting and sustaining the activity of tumor-antigen specific T cells within cancer tissues. To take full advantage of complementary antitumor activity of PD-1 monoclonal antibody (mAb) and IL-2 as well as supreme intratumoral T-cell-targeting property of PD-1, a bifunctional fusion protein composed of PD-1 mAb and IL-2 mutein (αPD-1-IL-2c) is designed. IL-2c is a chimeric molecule that contains a fragment from IL-15 and does not bind to IL-2 receptor alpha (IL-2Rα). αPD-1-IL-2c stimulated greater pSTAT5 activation and proliferation in PD-1+ T cells than PD-1- T cells. αPD-1-IL-2c also induced a much stronger anti-tumor immune response compared to PD-1 mAb, IL-2c, or PD-1 mAb in combination with IL-2c in multiple syngeneic models such as B16F10, CT26, and MC38. In CT26 and MC38 models, αPD-1-IL-2c achieved complete response starting from 0.3 mg/kg dosing. In B16F10 model, αPD-1-IL-2c showed greater than 70% tumor growth inhibition (TGI). Global gene expression profiling studies showed that PD-1-IL-2c treatment significantly elevated expression levels of Cd3d, Cd3e, Cd8a, Il2rα, Cxcr3, Cxcr6, Zap70, Lck, and Pdcd1 in tumor tissues compared to treatment with PD-1 mAbs or IL-2c, indicating a specific expansion and activation of T cell in the tumor microenvironment (TME). The safety profile of αPD-1-IL-2c was assessed and compared to WT IL-2 and a leading “No-α” αPD-1-IL-2 fusion protein (αPD-1-IL-2x). WT IL-2 and αPD-1-IL-2x induced significant body weight loss and severe splenomegaly when dosed at 1.25 mg/kg. In contrast, αPD-1-IL-2c dosed at 10 mg/kg did not cause appreciable body weight loss and only led to minimal splenomegaly. In summary, we have developed a safe and highly potent αPD-1-IL-2 mutein that achieves full PD-1 blockade and TME-specific T cell activation and expansion without appreciable toxicity. Citation Format: Fan Ye, Jianing Huang, Zoey Huang, Sandra Chen, Eric Liao, Ella Li, Allison Quach, Jenny Jiang, Hanna Lin, Michael Hua, Savannah Yung, Lili Cheng, Ziyang Zhong. A safe and highly potent anti-PD-1-IL-2c fusion that decouples efficacy and toxicity of IL-2 therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB218.

Abstract 2229: Targeted locus amplification based sequencing for mapping viral integration sites in human papillomavirus positive head and neck squamous cell carcinomas

Abstract Background: Human papillomavirus (HPV) infections are the principal cause of cervical cancers, subsets of anogenital and head and neck cancers (HNC). During persistent infection, viral DNA integration into the host genome may occur, which is suggested to affect carcinogenesis. One of the most critical limitations of currently used HPV integration detection techniques (PCR-based or NGS-based) is their application to FFPE material, because of DNA fragmentation. The aim of this study was to assess HPV integration in HPV-positive HNSCC cell lines and FFPE tissue comparing the new Targeted Locus Amplification (TLA) technology with previously used PCR technology (APOT/DIPS). Methods: Seven HPV-positive cell lines and FFPE material of 10 HPV-positive HNSCC were used for HPV integration detection by TLA, a proximity ligation-based next-generation sequencing technique. Crosslinked DNA is digested with restriction enzymes, and re-ligated into chimeric DNA molecules. For cell lines, a PCR based HPV16 target enrichment is performed, and for FFPE material a capture-based target enrichment is performed for HPV16 and HPV18 sequences, both followed by Illumina sequencing. Results: TLA was able to sequence up to 100 kb around the target, detecting exact HPV integration loci, structural variants, and chromosomal rearrangements. In all cell lines, one or more integration sites were identified, in accordance with APOT/DIPS PCR data and the literature. In the FFPE tissue samples, TLA identified integrated HPV in 6 out of 10 tumors, with simple and complex integration patterns. In general, TLA confirmed PCR data and detected additional integration sites. Conclusion: TLA provides the opportunity for reliable and robust detection of HPV integration in HNSCC cell lines and FFPE tissue. This new sequencing technology could be a useful tool for further research on HPV integration in disease and patient outcome and eventually in clinical diagnostics. Citation Format: Imke Demers, Harini Balaji, Harma Feitsma, Irinia Sergeeva, Joost Swennenhuis, Nora Wuerdemann, Steffen Wagner, Bernd Kremer, Christian Huebbers, Jens Peter Klussmann, Ernst-Jan Speel. Targeted locus amplification based sequencing for mapping viral integration sites in human papillomavirus positive head and neck squamous cell carcinomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2229.

Abstract 4081: Leveraging single-cell RNA sequencing data to design multi-targeting SeekRRNA therapeutics

Abstract SeekR™ chimeric molecules consist of dual flanking RNA aptamers designed to bind specific proteins (BINDERS), joined by a double stranded RNA bridge that encodes multiple siRNAs designed to silence select disease target genes (SILENCERS). Aptamers are folded nucleic acid chains that act much like chemical antibodies in that they can bind proteins in a sequence-specific manner. By identifying RNA aptamers capable of seeking and binding to specific cell surface protein receptors, SeekR™ RNA therapeutics can be engineered to self-deliver to a particular receptor defined tissue type. For example, a SeekR™ can be directed to prostate tumors that selectively express PSMA. The combination of two RNA aptamer binders with two siRNA silencers thus enables the selective delivery of the siRNAs to tumor cells expressing the binder target, wherein it directs sequence-specific silencing of cancer target genes. To identify and prioritize the right combination of SeekR targets, we have taken advantage of single-cell sequencing (scRNA-seq) data sets. By analyzing scRNA-seq data, we can identify specific cell populations within tumors to co-target with an aptamer and siRNA. We leveraged several publicly available colon and non-small cell lung cancer scRNA data sets for this analysis. A custom analysis pipeline was applied to these data to identify specific cell types within tumor samples. We then profiled specific cancer targets and determined percentages of target co-expression within a single tumor compared to normal cells. This provides information for cell-type-specific targeting to reduce potential toxicity within non-tumor tissue. In addition to targeting aptamers, we performed ligand-receptor analyses to prioritize specific siRNA targets in particular cell types within the tumor environment. This analysis revealed novel combinations of binders and silencers that will more precisely deliver the right multi-targeted gene silencing to the correct cell types. In summary, scRNA-seq data provide a rich resource of data to direct SeekR™ development and optimization. Citation Format: Susan Massey, Richard Hsiao, Shweta Yadav, David Azorsa, Spyro Mousses, Jeffrey A. Kiefer. Leveraging single-cell RNA sequencing data to design multi-targeting SeekRRNA therapeutics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4081.

Proteolysis Targeting Chimeric Molecules: Tuning Molecular Strategies for a Clinically Sound Listening.

From seminal evidence in the early 2000s, the opportunity to drive the specific knockdown of a protein of interest (POI) through pharmacological entities called Proteolysis Targeting Chimeric molecules, or PROTACs, has become a possible therapeutic option with the involvement of these compounds in clinical trials for cancers and autoimmune diseases. The fulcrum of PROTACs pharmacodynamics is to favor the juxtaposition between an E3 ligase activity and the POI, followed by the ubiquitination of the latter and its degradation by the proteasome system. In the face of an apparently modular design of these drugs, being constituted by an E3 ligase binding moiety and a POI-binding moiety connected by a linker, the final structure of an efficient PROTAC degradation enhancer often goes beyond the molecular descriptors known to influence the biological activity, specificity, and pharmacokinetics, requiring a rational improvement through appropriate molecular strategies. Starting from the description of the basic principles underlying the activity of the PROTACs to the evaluation of the strategies for the improvement of pharmacodynamics and pharmacokinetics and rational design, this review examines the molecular elements that have been shown to be effective in allowing the evolution of these compounds from interesting proof of concepts to potential aids of clinical interest.

Exploring Performance Parameters of Artificial Allosteric Protein Switches

Biological information processing networks rely on allosteric protein switches that dynamically interconvert biological signals. Construction of their artificial analogues is a central goal of synthetic biology and bioengineering. Receptor domain insertion is one of the leading methods for constructing chimeric protein switches. Here we present an in vitro expression-based platform for the analysis of chimeric protein libraries for which traditional cell survival or cytometric high throughput assays are not applicable. We utilise this platform to screen a focused library of chimeras between PQQ-glucose dehydrogenase and calmodulin. Using this approach, we identified 50 chimeras (approximately 23% of the library) that were activated by calmodulin-binding peptides. We analysed performance parameters of the active chimeras and demonstrated that their dynamic range and response times are anticorrelated, pointing to the existence of an inherent thermodynamic trade-off. We show that the structure of the ligand peptide affects both the response and activation kinetics of the biosensors suggesting that the structure of a ligand:receptor complex can influence the chimera’s activation pathway. In order to understand the extent of structural changes in the reporter protein induced by the receptor domains, we have analysed one of the chimeric molecules by CD spectroscopy and hydrogen–deuterium exchange mass spectrometry. We concluded that subtle ligand-induced changes in the receptor domain propagated into the GDH domain and affected residues important for substrate and cofactor binding. Finally, we used one of the identified chimeras to construct a two-component rapamycin biosensor and demonstrated that core switch optimisation translated into improved biosensor performance.

Beyond Proteolysis-Targeting Chimeric Molecules: Designing Heterobifunctional Molecules Based on Functional Effectors.

In recent years, with the successful development of proteolysis-targeting chimeric molecules (PROTACs), the potential of heterobifunctional molecules to contribute to reenvisioning drug design, especially small-molecule drugs, has been increasingly recognized. Inspired by PROTACs, diverse heterobifunctional molecules have been reported to simultaneously bind two or more molecules and bring them into proximity to interaction, such as ribonuclease-recruiting, autophagy-recruiting, lysosome-recruiting, kinase-recruiting, phosphatase-recruiting, glycosyltransferase-recruiting, and acetyltransferase-recruiting chimeras. On the basis of the heterobifunctional principle, more opportunities for advancing drug design by linking potential effectors to a protein of interest (POI) have emerged. Herein, we introduce heterobifunctional molecules other than PROTACs, summarize the limitations of existing molecules, list the main challenges, and propose perspectives for future research directions, providing insight into alternative design strategies based on substrate-proximity-based targeting.

Synthetic Reprogramming of Kinases Expands Cellular Activities of Proteins.

Phosphorylation-inducing chimeric small molecules (PHICS) can enable a kinase to act at a new cellular location or phosphorylate non-native substrates (neo-substrates)/ sites (neo-phosphorylations).[1, 2] We report a modular design and high-yielding synthesis of such PHICS that endowed multiple new activities to protein kinase C (PKC). For example, while PKC is unable to downregulate the activity of a gain-of-function variant (S180A) of Bruton's tyrosine kinase that evokes B cell malignancy phenotype, PHICS enabled PKC to induce inhibitory neo-phosphorylations on this variant. Furthermore, while PKC typically phosphorylates its membrane-associated substrates, PKC with PHICS phosphorylated multiple cytosol-based neo-substrates (e.g., BCR-ABL). Finally, a PHICS for BCR-ABL induced death of chronic myeloid leukemia cell lines. These studies show the power of synthetic chemistry to expand the chemical and functional diversity of proteins in cells using bifunctional molecules.

Synthetic Reprogramming of Kinases Expands Cellular Activities of Proteins

Synthetic Reprogramming of Kinases Expands Cellular Activities of Proteins

A prebiotically plausible scenario of an RNA–peptide world

The RNA world concept1 is one of the most fundamental pillars of the origin of life theory2–4. It predicts that life evolved from increasingly complex self-replicating RNA molecules1,2,4. The question of how this RNA world then advanced to the next stage, in which proteins became the catalysts of life and RNA reduced its function predominantly to information storage, is one of the most mysterious chicken-and-egg conundrums in evolution3–5. Here we show that non-canonical RNA bases, which are found today in transfer and ribosomal RNAs6,7, and which are considered to be relics of the RNA world8–12, are able to establish peptide synthesis directly on RNA. The discovered chemistry creates complex peptide-decorated RNA chimeric molecules, which suggests the early existence of an RNA–peptide world13 from which ribosomal peptide synthesis14 may have emerged15,16. The ability to grow peptides on RNA with the help of non-canonical vestige nucleosides offers the possibility of an early co-evolution of covalently connected RNAs and peptides13,17,18, which then could have dissociated at a higher level of sophistication to create the dualistic nucleic acid–protein world that is the hallmark of all life on Earth.

Defects in macrophage galactose-type lectin (MGL) signaling and pathogenesis of Mycobacterium tuberculosis and Human Immunodeficiency virus co-infection

Abstract Mycobacterium tuberculosis (Mtb) and Human Immunodeficiency virus (HIV) are important causes of death in infected patients worldwide, and act synergistically to worsen disease in those with co-infection. C-type lectin receptors (CLRs) are an important component of innate immunity that can recognize and respond to pathogen-associated signals. The macrophage galactose-type lectin (MGL, CLEC10) has been described as an immunomodulatory CLR associated with M2 macrophages and regulation of inflammation following infection. Our lab previously identified an important antibacterial role of murine MGL-1 in host immunity to Mtb. More recently we observed that human peripheral blood mononuclear cell-derived macrophages, and THP-1 cells, upregulated MGL following in vitro exposure to Mtb, Mycobacterium bovis BCG, and TLR2 agonists. Silencing of MGL in primary human macrophages permitted greater intracellular Mtb replication. Interestingly, we observed that MGL is suppressed by HIV in differential transcriptome analysis of lung from HIV-infected humanized mice, in lung and spleen of autopsy specimens from HIV-infected decedents, and upon in vitro infection of human macrophages. Using a recombinant human MGL/Fc chimeric molecule we observed that Mtb, and not HIV, directly bound MGL. MGL surface expression was reduced in lung of mice with chronic HIV infection compared to those with Mtb, and variable in co-infected animals. These results indicate that human MGL is an important CLR for pathogen recognition and initiation of protective immunity by host macrophages to Mtb. The suppression of MGL due to HIV may increase susceptibility to Mtb in people with HIV or exacerbate disease progression in those with co-infection. Supported by grants from NIH (R33 AI138328, R61 AI138328, U24 MH100930)

Alpha-synuclein peptides presented on chimeric MHC class Ib molecules prevent loss of substantia nigra neurons in an animal model for Parkinson’s disease

Abstract Aim An accumulating body of evidence suggests the involvement of alpha-synuclein (aSyn) specific autoreactive T cells in Parkinson’s disease (PD). Here, we investigate whether novel antigen-specific tolerance-inducing biomolecules, that present peptide antigens on MHC class Ib-related molecules, can inhibit neurodegeneration and prevent PD in vivo. Methods The alpha3 domain of the human MHC class Ib molecule HLA-G inhibits T cells via the human ILT-2 or the murine PIRB receptor. We fused this HLA-G alpha3 domain to MHC class I alpha1-alpha2 antigen presenting domains, antigenic peptides and beta2-microglobulin. These single-chain AutoImmunity Modifying Biologicals (AIM Bios) induce antigen-specific tolerogenic CD8+ Treg cells in human cells in vitro and in mice in vivo. We used this platform to prevent autoimmune disease symptoms in mouse models for autoimmune diseases, including an aSynA53T-AAV driven model for PD. Results Single-chain model AIM Bios with MHC-derived antigen-presenting domains and antigenic peptides polarize cognate CD8+ T cells towards a CD8+CD122+ IL-10 secreting Treg phenotype. Such antigen-specific Treg can also be induced in mice in vivo. Disease-associated aSyn CD8+ epitopes were identified in aSynA53T-AAV PD mice. Corresponding AIM Bios prevented mobility impairments. Post mortem histopathological assessment confirmed the induction a favorable in-situ immune cell composition and the rescue of substantia nigra neurons. The translational potential of this approach deserves further exploration. Supported by grants from the IZKF Wuerzburg A421 and by Aeterna Zentaris Inc.

Antigen mimicry as an effective strategy to induce CSPG4-targeted immunity in dogs with oral melanoma: a veterinary trial

BackgroundMelanoma is the most lethal form of skin cancer in humans. Conventional therapies have limited efficacy, and overall response is still unsatisfactory considering that immune checkpoint inhibitors induce lasting clinical...

Targeted protein degradation and drug discovery

Targeted protein degradation attracts attention as a novel modality for drug discovery, as well as for basic research. Various types of degrader molecules have been developed so far, which include proteolysis-targeting chimaeras (PROTACs) and specific and nongenetic IAP-dependent protein erasers (SNIPERs), E3 modulators, hydrophobic tagging molecules, IAP antagonists and deubiquitylase inhibitors. PROTACs and SNIPERs are chimeric degrader molecules consisting of a target ligand linked to another ligand that binds to an E3 ubiquitin ligase. In the cells, they recruit an E3 ligase to the target protein, thereby inducing ubiquitylation and proteasomal degradation of the target protein. Because of their modular structure, novel PROTACs and SNIPERs targeting proteins of your interest can be rationally developed by substituting target ligands. In this article, various compounds capable of inducing protein degradation were overviewed, including SNIPER compounds developed in our laboratory.

In silico design and computational evaluation of novel 2-arylaminopyrimidine-based compounds as potential multi-targeted protein kinase inhibitors: application for the native and mutant (T315I) Bcr-Abl tyrosine kinase

An integrated computational approach to drug discovery was used to identify novel potential inhibitors of the native and mutant (T315I) Bcr-Abl tyrosine kinase, the enzyme playing a key role in the pathogenesis of chronic myeloid leukemia (CML). This approach included i) design of chimeric molecules based on the 2-arylaminopyrimidine fragment, the main pharmacophore of the Abl kinase inhibitors imatinib and nilotinib used in the clinic for the CML treatment, ii) molecular docking of these compounds with the ATP-binding site of the native and mutant Abl kinase, iii) refinement of the ligand-binding poses by the quantum chemical method PM7, iv) molecular dynamics simulations of the ligand/Abl complexes, and v) prediction of the ligand/Abl binding affinity in terms of scoring functions of molecular docking, machine learning, quantum chemistry, and molecular dynamics. As a result, five top-ranking compounds able to effectively block the enzyme catalytic site were identified. According to the data obtained, these compounds exhibit close modes of binding to the Abl kinase active site that are mainly provided by hydrogen bonds and multiple van der Waals contacts. The identified compounds show high binding affinity to the native and mutant Abl kinase comparable with the one calculated for the FDA-approved kinase-targeted inhibitors imatinib, nilotinib, and ponatinib used in the calculations as a positive control. The results obtained testify to the predicted drug candidates against CML may serve as good scaffolds for the design of novel anticancer agents able to target the ATP-binding pocket of the native and mutant Abl kinase. Communicated by Ramaswamy H. Sarma

Research Highlights

Research Highlights

Therapeutic targeting of mitophagy in Parkinson's disease.

Parkinson's disease is a neurodegenerative disorder characterised by cardinal motor symptoms and a diverse range of non-motor disorders in patients. Parkinson's disease is the fastest growing neurodegenerative condition and was described for the first time over 200 years ago, yet there are still no reliable diagnostic markers and there are only treatments that temporarily alleviate symptoms in patients. Early-onset Parkinson's disease is often linked to defects in specific genes, including PINK1 and Parkin, that encode proteins involved in mitophagy, the process of selective autophagic elimination of damaged mitochondria. Impaired mitophagy has been associated with sporadic Parkinson's and agents that damage mitochondria are known to induce Parkinson's-like motor symptoms in humans and animal models. Thus, modulating mitophagy pathways may be an avenue to treat a subset of early-onset Parkinson's disease that may additionally provide therapeutic opportunities in sporadic disease. The PINK1/Parkin mitophagy pathway, as well as alternative mitophagy pathways controlled by BNIP3L/Nix and FUNDC1, are emerging targets to enhance mitophagy to treat Parkinson's disease. In this review, we report the current state of the art of mitophagy-targeted therapeutics and discuss the approaches being used to overcome existing limitations to develop innovative new therapies for Parkinson's disease. Key approaches include the use of engineered mouse models that harbour pathogenic mutations, which will aid in the preclinical development of agents that can modulate mitophagy. Furthermore, the recent development of chimeric molecules (AUTACs) that can bypass mitophagy pathways to eliminate damaged mitochondria thorough selective autophagy offer new opportunities.

New and Old Anti-CD20 Monoclonal Antibodies for Nephrotic Syndrome. Where We Are?

Nephrotic proteinuria is the hallmark of several glomerulonephritis determined by different pathogenetic mechanisms, including autoimmune, degenerative and inflammatory. Some conditions such as Minimal Change Nephropathy (MCN) and Focal Segmental Glomerulosclerosis (FSGS) are of uncertain pathogenesis. Chimeric anti-CD20 monoclonal antibodies have been used with success in a part of proteinuric conditions while some are resistant. New human and humanized monoclonal anti-CD 20 antibodies offer some advantages based on stronger effects on CD20 cell subtypes and have been already administered in hematology and oncology areas as substitutes of chimeric molecules. Here, we revised the literature on the use of human and humanized anti-CD 20 monoclonal antibodies in different proteinuric conditions, resulting effective in those conditions resistant to rituximab. Literature on the use of human anti-CD 20 monoclonal antibodies in different proteinuric diseases is mainly limited to ofatumumab, with several protocols and doses. Studies already performed with ofatumumab given in standard doses of 1,500 mg 1.73m2 suggest no superiority compared to rituximab in children and young adults with steroid dependent nephrotic syndrome. Ofatumumab given in very high doses (300 mg/1.73m2 followed by five infusion 2,000 mg/1.73 m2) seems more effective in patients who are not responsive to common therapies. The question of dose remains unresolved and the literature is not concordant on positive effects of high dose ofatumumab in patients with FSGS prior and after renal transplantation. Obinutuzumab may offer some advantages. In the unique study performed in patients with multidrug dependent nephrotic syndrome reporting positive effects, obinutuzumab was associated with the anti-CD38 monoclonal antibody daratumumab proposing the unexplored frontier of combined therapies. Obinutuzumab represent an evolution also in the treatment of autoimmune glomerulonephritis, such as membranous nephrotahy and lupus nephritis. Results of randomized trials, now in progress, are awaited to add new possibilities in those cases that are resistant to other drugs. The aim of the present review is to open a discussion among nephrologists, with the hope to achieve shared approaches in terms of type of antibodies and doses in the different proteinuric renal conditions.

Heterobifunctional molecules tackle targeted protein dephosphorylation

Recently, Chen and colleagues reported the development of phosphatase-targeting chimeric molecules (PhosTACs), heterobifunctional small molecules that promote targeted, proximity-induced protein dephosphorylation. This strategy represents an innovative approach to selectively manipulate phosphoprotein function and provides proof-of-concept for a new class of bifunctional small molecules in the chemical biologist's toolbox.

Development of a degrader against oncogenic fusion protein FGFR3-TACC3

Fibroblast growth factor receptor 3-transforming acidic coiled-coil containing protein 3 (FGFR3-TACC3), which has been identified in many cancers such as glioblastoma and bladder cancer, is a potent oncogenic fusion protein that induces constitutive activation of FGFR signaling, resulting in uncontrolled cell proliferation. Although several tyrosine kinase inhibitors against FGFR are currently under development, resistance to such types of inhibitors in patients has become a concern. In this study, a chimeric molecule SNIPER(TACC3)-11 (5a) was developed and found to reduce FGFR3-TACC3 levels effectively. Compound 5a conjugated KHS108 (a TACC3 ligand) to an LCL161 derivative (11) (an inhibitor of apoptosis protein [IAP] ligand) with a PEG linker (n = 2). Mechanistical analysis showed that cellular IAP1 was required for the reduction of FGFR3-TACC3 levels. Consistent with the decrease in FGFR3-TACC3 levels, compound 5a suppressed the growth of FGFR3-TACC3 positive cells. Thus, compound 5a is a candidate therapeutic with a novel drug modality against cancers that exhibit FGFR3-TACC3-dependent proliferation and exerts pharmacological effects distinct from FGFR3 kinase inhibitors because it lacks substructures crucial for kinase inhibition.