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Abdel-Rahman, S.

Publications and source records attributed to Abdel-Rahman, S..

12 recordsLinked to original sources

ClinOracle: Hierarchical AI Prediction of Target Binding and Patient-Derived Functional Activity Across Diverse Therapeutic Targets

AI platforms for drug discovery routinely achieve high hit rates against biochemical targets, yet the central translational challenge remains predicting whether a compound will be functionally active in patient-derived human cells. Here, we present ClinOracle, a hierarchical graph neural network that jointly predicts target binding and patient-derived functional activity by modeling functional activity as conditional on target engagement. Applied across five therapeutic targets spanning oncology, autoimmune, and neuroinflammatory diseases, ClinOracle ranked candidates using a Priority Score integrating translational probability with a developability score based on ADME and drug-likeness, advancing prioritized compounds through multistage prospective validation from biophysical binding to in vivo efficacy. Compounds with the highest Priority Scores consistently outperformed lower-ranked candidates across prospective experimental validation, demonstrating that hierarchical AI can prioritize compounds with patient-derived functional activity directly from molecular structure, rather than biochemical activity alone.

pharmacology and toxicology↗

HTS-Oracle X: AI-Guided Prospective Discovery of Small Molecule Immune Checkpoint Binders

Targeting immune checkpoint protein-protein interactions (PPIs) using small molecules remains limited by the shallow, featureless binding surfaces of co-stimulatory and co-inhibitory receptors and the characteristically low hit rates of conventional high-throughput screening against these interfaces. Here we report HTS-Oracle X, a multimodal deep learning platform that integrates bidirectional cross-attention fusion of ChemBERTa SMILES embeddings with extended RDKit descriptors, trains on continuous biophysical binding signals rather than binary labels, and employs Monte Carlo Dropout uncertainty quantification for uncertainty-adjusted compound selection. Trained on 45,760 Dianthus TRIC-screened compounds per target under scaffold-aware cross-validation, HTS-Oracle X was applied prospectively to a 100,160-compound Enamine library against CD28, TIM-3, and VISTA. From 150 model-selected compounds, 45 dose-response confirmed binders were identified (30.0% overall hit rate), yielding enrichment factors of 234-408x over experimentally established random prospective baselines and 16 sub-micromolar hits. The top hits, HX-CD28-1 (KD = 233 nM), HX-TIM3-1 (KD = 249 nM), and HX-VISTA-1 (KD = 345 nM), demonstrated on-target functional activity in immune cell and tumor co-culture assays. HTSOracle X represents a scalable AI-guided framework for small molecule discovery against non-enzymatic immune checkpoint targets. Table of Contents artwork O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/732853v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@187fac7org.highwire.dtl.DTLVardef@6150d7org.highwire.dtl.DTLVardef@10266f0org.highwire.dtl.DTLVardef@b436e1_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioinformatics↗

OracleScreen-LILRB4: Machine Learning-Guided Discovery of Myeloid Immune Checkpoint Binders Validated in Patient-Derived Cells

The identification of small molecule modulators of immune checkpoint proteins remains a significant challenge in drug discovery due to the flat, featureless nature of protein-protein interaction interfaces and the characteristically low hit rates observed in conventional high-throughput screening campaigns. Here we report OracleScreen-LILRB4, an ensemble machine learning framework trained on quantitative biophysical screening data from two structurally diverse compound libraries (19,800 compounds total) screened against the myeloid immune checkpoint leukocyte immunoglobulin-like receptor B4 (LILRB4/ILT3). By formulating binding prediction as a regression task targeting continuous {Delta}Fnorm values rather than binary hit classifications, OracleScreen-LILRB4 achieved a mean Spearman R of 0.61 and ROC-AUC of 0.86 under scaffold-aware cross-validation. Prospective virtual screening of a 45,760-member compound library and experimental validation of the top 200 predictions yielded a 28.5% hit rate, representing a 15.0-fold enrichment over baseline, with 16 compounds demonstrating nanomolar-affinity LILRB4 (ILT3) engagement. Lead compounds ORS-22 and ORS-14 restored anti-tumor immune activity across patient-derived colorectal cancer and acute myeloid leukemia co-culture systems, reversing SCG2-mediated immunosuppression and recovering cytotoxic T-cell function. These findings establish OracleScreen-LILRB4 as an effective computational framework for accelerating small molecule discovery against non-enzymatic immune checkpoint targets. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=99 SRC="FIGDIR/small/732859v1_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@1ef70a9org.highwire.dtl.DTLVardef@cd976dorg.highwire.dtl.DTLVardef@1907ebforg.highwire.dtl.DTLVardef@1716aec_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioinformatics↗

HTS-Oracle v2: Prospective AI-Guided Discovery and Experimental Validation of Small Molecule Modulators Across Multiple Targets

High-throughput screening (HTS) remains the cornerstone of early-phase small molecule discovery yet consistently underperforms against immunotherapy targets, yielding validated hit rates below 0.1%. Here we introduce HTS-Oracle v2, which features rigorous cross-validation that ensures honest performance estimates. HTS-Oracle v2 was trained and validated across four clinically significant immune checkpoint targets (CD28, ICOS, LAG-3, and TIGIT) achieving ROC-AUC values of 0.968, 0.969, 0.875, 0.928 respectively under rigorous cross-validation. For prospective experimental validation, HTS-Oracle v2 was applied to an 8,960-compound Enamine Protein Mimetic Library, selecting only 25 compounds per target for experimental testing using temperature-related intensity change (TRIC) technology, a 99.7% reduction in screening burden. HTS-Oracle v2 identified 4, 5, 4, and 6 validated binders from 25 prospectively selected compounds per target, corresponding to validated hit rates of 16%, 20%, 16%, and 24%, respectively. Notably, 67-80% of all experimentally confirmed hits across the full 8,960-compound library were captured within just 25 model-selected compounds per target. For CD28, this represents a 28-fold improvement over HTS-Oracle v1 (239x versus 8.4x), establishing HTS-Oracle v2 as an efficient platform for AI-guided prospective hit discovery across immunotherapy targets.

bioinformatics↗

AI-Guided Discovery of Small Molecule LILRB4 (ILT3) Inhibitors Reprograms Microglia and Reduces Amyloid Pathology

The inhibitory microglial receptor LILRB4 (ILT3) suppresses amyloid-beta clearance in Alzheimers disease (AD) through ApoE-dependent signaling but remains undrugged by small molecules. Here, we report the AI-guided discovery of small molecule inhibitors that directly disrupt the LILRB4-ApoE interaction. Ultralarge-scale screening of [~]500 million compounds identified small molecules that bind LILRB4 with nanomolar affinity and competitively block ApoE engagement, as validated across orthogonal biophysical assays. Structural and mutational analyses define a tractable interdomain pocket that mediates ligand recognition. In human iPSC-derived microglia, LILRB4 inhibition suppresses SHP1/2-dependent signaling, attenuates NF-{kappa}B activation, and restores A{beta} uptake. The lead compound exhibits favorable pharmacokinetics with robust brain penetration and, upon oral administration, improves cognitive performance, reduces amyloid burden, and dampens neuroinflammation in the 5xFAD mouse model. These findings establish LILRB4 as a druggable neuroimmune checkpoint and demonstrate that small molecule disruption of inhibitory microglial signaling can restore disease-relevant function in vivo.

pharmacology and toxicology↗

From DNA-Encoded Library (DEL) Screening to In Vivo Validation: LILRB4 (ILT3)-Targeted Small Molecules Reprograms Myeloid Immune Suppression

Alzheimers disease (AD) remains a major unmet clinical challenge, with limited therapeutic strategies capable of effectively modulating neuroimmune dysfunction. Leukocyte immunoglobulin-like receptor B4 (LILRB4/ILT3) has recently emerged as an inhibitory microglial immune checkpoint implicated in ApoE-mediated suppression of amyloid-{beta} (A{beta}) clearance and inflammatory signaling, supporting its potential as a therapeutic target in AD. Here, we applied DNA-encoded library (DEL) screening of approximately 3.6 billion compounds to identify small molecule binders of LILRB4. Biophysical validation identified APX1 as a direct LILRB4 ligand with submicromolar affinity, which was further confirmed by cellular thermal shift assay (CETSA). Docking-guided mutagenesis studies defined a discrete ligand-binding interface involving key hotspot residues required for stable target engagement. Functionally, APX1 disrupted the LILRB4-ApoE interaction in orthogonal ELISA and biolayer interferometry assays. In human iPSC-derived microglia, APX1 suppressed SHP1/2 phosphorylation, attenuated NF-{kappa}B activation and IL-1{beta} secretion, and restored A{beta}42 uptake under ApoE-driven inflammatory conditions. APX1 further demonstrated favorable in vitro developability, metabolic stability, and CNS exposure properties. In the 5xFAD mouse model of AD, oral administration of APX1 improved cognitive performance, reduced cortical and hippocampal A{beta}42 burden, suppressed neuroinflammatory cytokines, and decreased activated microglial populations. Collectively, these findings establish APX1 as a promising small molecule modulator of the LILRB4-ApoE signaling axis and support pharmacological targeting of neuroimmune checkpoints as a therapeutic strategy for AD.

pharmacology and toxicology↗

Direct Small Molecule Modulation of LILRB4 (ILT3) Restores Anti-Tumor Immunity In Vivo and in Patient-Derived Cells

Small molecule targeting of suppressive myeloid immune checkpoints remains a major challenge in cancer immunotherapy, particularly for non-enzymatic receptors lacking conventional druggable active sites. Leukocyte immunoglobulin-like receptor B4 (LILRB4/ILT3) is an immunosuppressive myeloid checkpoint implicated in tumor immune evasion, T-cell dysfunction, and resistance to immunotherapy across both solid and hematologic malignancies. Here, we report the discovery and characterization of GL-4512, a direct small molecule modulator of LILRB4 identified through a Dianthus-based temperature-related intensity change (TRIC) screening platform. Orthogonal biophysical studies, including microscale thermophoresis, surface plasmon resonance, and cellular thermal shift assays, confirmed direct target engagement with nanomolar affinity. Extensive microsecond molecular dynamics simulations combined with site-directed mutagenesis identified a previously unrecognized ligandable pocket within the flexible extracellular domain of LILRB4. Functionally, GL-4512 disrupted the immunosuppressive LILRB4-SCG2 signaling axis and suppressed downstream SHP1/SHP2 and STAT3 signaling. In patient-derived colorectal cancer and acute myeloid leukemia co-culture systems, pharmacological inhibition of LILRB4 restored anti-tumor immune activity, enhanced IFN-{gamma} and IL-2 production, increased cytotoxic T-cell activation, and reduced tumor-cell viability. GL-4512 additionally demonstrated favorable pharmacokinetic and safety properties supporting oral in vivo administration. In immunocompetent CT26 syngeneic colorectal tumors, once-daily oral treatment significantly suppressed tumor growth and enhanced intratumoral immune activation. Collectively, these findings establish LILRB4 as a tractable target for direct small molecule immunomodulation and support therapeutic targeting of suppressive myeloid immune checkpoints for cancer using non-biologic modalities.

pharmacology and toxicology↗

Discovery of ILT3 (LILRB4) Small Molecule Inhibitors by Affinity Se-lection-Mass Spectrometry Reveals Druggability of a Neuroimmune Checkpoint in Alzheimers Disease

Leukocyte immunoglobulin-like receptor B4 (LILRB4/ILT3) is an emerging neuroimmune checkpoint that restricts microglial activation and amyloid clearance in Alzheimers disease (AD) through ApoE-dependent signaling. Here, we establish ILT3 as a tractable small molecule target using affinity selection-mass spectrometry (AS-MS) to identify direct binders. Biophysical validation confirmed high-affinity engagement, with LT12 exhibiting nanomolar binding by MST and SPR. Computational modeling and mutagenesis defined a discrete ILT3 binding pocket, revealing a distributed interaction network critical for ligand engagement. Targeting ILT3 disrupted the ILT3-ApoE interaction, with LT12 showing potent inhibition in orthogonal biochemical assays. In human iPSC-derived microglia, ILT3 modulation attenuated SHP1/2 signaling, suppressed NF-{kappa}B activation, reduced IL-1{beta} secretion, and restored A{beta} uptake. In vivo, pharmacological targeting of ILT3 improved cognition, reduced amyloid burden, and attenuated neuroinflammation in 5xFAD mice. Together, these findings validate ILT3 as a druggable neuroimmune checkpoint and support its therapeutic targeting in AD.

pharmacology and toxicology↗

Targeting the Myeloid Immune Checkpoint ILT3 (LILRB4) with Small Molecules Enables Reprogramming of Suppressive Tumor Immunity

Cancer immunotherapy has transformed cancer treatment; however, durable responses remain limited by suppressive myeloid populations within the tumor microenvironment. Leukocyte immunoglobulin-like receptor B4 (LILRB4/ILT3) is an emerging myeloid immune checkpoint implicated in immune evasion and resistance to immunotherapy, yet small molecule targeting of ILT3 remains largely unexplored. Here, we report the discovery of small molecule ILT3 modulators identified using a Dianthus-based temperature-related intensity change (TRIC) screening platform. Screening of an 8,961-member Enamine Library identified multiple direct ILT3 binders, with lead compound ICB-7 demonstrating high-affinity binding to recombinant human ILT3 by microscale thermophoresis and robust cellular target engagement in CETSA assays. Molecular docking and molecular dynamics simulations revealed a stable hydrophobic binding pocket within the D2 domain of ILT3. Functionally, ICB-7 disrupted the ILT3-SCG2 interaction and inhibited downstream SHP1, SHP2, and STAT3 signaling. In patient-derived colorectal cancer and acute myeloid leukemia co-culture models, ICB-7 enhanced cytotoxic T-cell activity, and reduced tumor-cell viability. The compound also demonstrated favorable pharmacokinetic and safety properties together with significant anti-tumor efficacy in the CT26 syngeneic colorectal carcinoma model. Collectively, these findings establish ILT3 as a tractable target for small-molecule immunomodulation and support pharmacological targeting of suppressive myeloid checkpoints as a promising cancer immunotherapy strategy.

pharmacology and toxicology↗

Development of a High-Throughput TR-FRET Assay for Identification of Small Molecule Inhibitors of the LILRB4 (ILT3)-SCG2 Immune Checkpoint Interaction

Leukocyte immunoglobulin-like receptor B4 (LILRB4, ILT3) is an inhibitory immune checkpoint expressed on myeloid cells, where it contributes to immunosuppression within the tumor microenvironment. Secretogranin 2 (SCG2) has recently been identified as a functional ligand of LILRB4, yet small molecule modulators of this interaction remain unexplored. Here, we report the development of a high-throughput time-resolved fluorescence resonance energy transfer (TR-FRET) assay to interrogate the LILRB4 (ILT3)-SCG2 interaction. The assay demonstrated robust performance and was validated using a blocking anti-LILRB4 antibody, consistent with orthogonal ELISA measurements. Pilot screening of chemical libraries identified 23 primary hits, of which two compounds, BMS-813160 and PSB-603, showed reproducible, dose-dependent inhibition with TR-FRET IC50 values of 26.7 {+/-} 1.03 {micro}M and 37.2 {+/-} 2.14 {micro}M, respectively. Activity was confirmed by ELISA, supporting the robustness of the assay. This platform enables high-throughput discovery of first-in-class small molecule modulators of the LILRB4-SCG2 immune checkpoint and provides a foundation for targeting myeloid-driven immunosuppression.

biophysics↗

Computational Design and Biophysical Validation of Macrocyclic Peptides as Inhibitors of SLIT2/ROBO1 interaction

The SLIT2/ROBO1 signaling axis regulates cellular migration and angiogenesis but also contributes to tumor progression and immune evasion in glioblastoma. Targeting this pathway with small molecules or antibodies remains challenging due to the shallow and extended nature of the SLIT2/ROBO1 interface. Here, we report the first computational design and experimental validation of macrocyclic peptides that inhibit SLIT2/ROBO1 binding. Twenty peptides were generated through a structure-guided interface mapping approach (Des3PI 2.0) and ranked using a contact-based scoring function. The top candidates were synthesized and evaluated using time-resolved fluorescence resonance energy transfer (TR-FRET) and biolayer interferometry (BLI) assays. Among the SLIT2-targeting peptides, SP4 and SP3 showed the most pronounced inhibition in TR-FRET and BLI, confirming direct binding to the SLIT2/ROBO1 interface. The lead peptide SP4 also demonstrated favorable in vitro pharmacokinetic properties, including strong stability in simulated intestinal fluid, high plasma integrity, and moderate metabolic stability in rat liver microsomes. Collectively, this work establishes a computational-to-experimental pipeline for discovering macrocyclic peptides that disrupt challenging protein-protein interactions and provides a foundation for developing next-generation SLIT2/ROBO1 modulators for cancer and neuroimmune disorders. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=54 SRC="FIGDIR/small/684696v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@e011f7org.highwire.dtl.DTLVardef@bb8e5aorg.highwire.dtl.DTLVardef@17ec46corg.highwire.dtl.DTLVardef@1919666_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

Design and Validation of the First-in-Class PROTACs for Targeted Degradation of the Immune Checkpoint LAG-3

Lymphocyte activation gene-3 (LAG-3) is an inhibitory immune checkpoint receptor that plays a central role in T cell exhaustion and immune evasion in cancer. While monoclonal antibodies targeting LAG-3 have entered clinical development, small molecule approaches remain largely unexplored. Here, we report the design and validation of the first-in-class PROTACs for targeted degradation of LAG-3. In this study, we repurposed a LAG-3-binding small molecule identified through DNA-encoded library (DEL) screening as the targeting ligand for a series of CRL4CRBN-based PROTACs designed with varied linker lengths. Western blot analysis in Raji-LAG3 cells demonstrated that LAG-3 PROTAC-1 and LAG-3 PROTAC-3 induce potent, dose-dependent degradation of LAG-3, with DC50 values of 274 nM and 421 nM, respectively. Molecular docking and molecular dynamics (MD) simulations revealed the LAG-3 binding mode of designed PROTACs and provided structural insights into PROTAC-mediated ternary complex formation. Collectively, this work establishes a proof-of-concept for chemical degradation of LAG-3 for the first time and paves the way for novel immunotherapeutic strategies.

pharmacology and toxicology↗