Predicting molecular bioactivity in low-data regimes remains a central challenge in computational drug discovery, where labeled compounds for specialized tasks are scarce while related datasets are abundant. Here, we propose FerrGAT, a graph attention network framework that addresses this challenge through domain-relevant multi-task pre-training and dual-channel molecular representation learning. FerrGAT first pre-trains a shared GAT encoder on three mechanistically related tasks—antioxidant activity (GST inhibition, 245 compounds from ChEMBL target CHEMBL2095173; 83 active/162 inactive), kinase inhibition (3000 compounds spanning AXL, EGFR and VEGFR2 from ChEMBL; 2240 active/760 inactive), and cellular toxicity (7265 compounds from the Tox21 NR-AhR endpoint; 309 active/6956 inactive)—then transfers the learned representations to a target task via differential learning rate fine-tuning. The architecture fuses atom-level graph features from multi-head attention message passing with global physicochemical descriptors through a learned projection and provides built-in interpretability via attention weight visualization at the atomic level. We evaluated FerrGAT on ferroptosis inhibitor prediction as a representative low-data molecular classification task (1052 compounds from ChEMBL targets GPX4 and HMOX1 combined with 63 literature- and FerrDb-curated ferroptosis modulators; 409 active/643 inactive). In 5-fold cross-validation, FerrGAT achieved an AUC of 0.906, outperforming Morgan fingerprint baselines, including Random Forest (0.877), XGBoost (0.871), and an SVM (0.873). Ablation studies confirmed that domain-relevant pre-training improved AUC by 2.5% over training from scratch, while pre-training on unrelated tasks degraded performance, highlighting the importance of task-domain alignment. Applied to virtual screening of 30 FDA-approved tyrosine kinase inhibitors, the model identified Bemcentinib (AXL inhibitor, score = 0.918) as a top candidate, validated by AutoDock Vina molecular docking (−8.51 kcal/mol) and independent experimental evidence, including lipid peroxidation assays, Western blot, and cellular thermal shift analysis. These results demonstrate that domain-aware transfer learning with graph attention networks provides an effective and interpretable framework for molecular property prediction in data-limited scenarios.
Extracellular targeted protein degradation (eTPD) systems typically utilize lysosome-targeting receptors (LTRs) to mediate internalization and lysosomal degradation of extracellular and membrane proteins. While multiple LTRs have been discovered, there remains a compelling need to seek for new LTRs, particularly those with clear clinical relevance, to expand the therapeutic potential of eTPD. Here we report trophoblast cell surface antigen-2 (TROP2), a clinically validated tumor-associated antigen, as a promising tumor-selective LTR. We engineer TROP2-targeting chimeras (TRTACs) by genetically fusing a TROP2-binding nanobody to nanobodies against specific target proteins. We show that TRTACs can induce tumor cell-selective degradation of diverse membrane proteins, including epithelial growth factor receptor (EGFR), human epithelial growth factor receptor 2 (HER2), and programmed death-ligand 1 (PD-L1). The EGFR-targeted TRTAC significantly inhibits tumor cell proliferation and shows potent antitumor activity in vivo. We further design TRTAC-drug conjugates (TRTAC-DCs) by attaching cytotoxic payloads to TRTACs, enabling targeted protein degradation together with enhanced drug delivery. TRTAC-DCs show significantly enhanced activity against HER2- and EGFR-positive tumors both in vitro and in vivo, with minimal toxicity observed in normal tissues. These findings establish TROP2 as a robust LTR and provide a versatile eTPD platform with profound translational potential for tumor treatment.