Sequence-centric deep learning druggability prediction using protein language models with multi-scale attention and feature fusion
Sequence-based protein druggability classification can support early target triage when structural information is unavailable, uncertain, or inconsistently linked to druggability labels. We present DrugPLMFormer, a sequence-first retrospective screening framework that combines frozen protein language model embeddings with self-attentive BiLSTM encoding, Transformer-based long-range modeling, optional physicochemical feature fusion, and compute-budgeted BO–CTCM model selection. Hyperparameters were selected through multi-fidelity screening within an approximately 200-evaluation budget, using a validation objective that combined AUPRC and MCC to balance threshold-free discrimination with operating-point stability, rather than to imply unrestricted generalization. On ProTar-II, using a 50% sequence-identity homology-aware split, DrugPLMFormer achieved 95.98% accuracy, 96.01% F1-score, 96.42% sensitivity, 95.61% specificity, and 0.981 ROC-AUC. Without using external data for training, tuning, threshold selection, or early stopping, the selected model showed favorable held-out mean performance on ProTar-II-Ind (96.62% accuracy, 0.9688 ROC-AUC) and DPI_CDF (96.20% accuracy, 0.9696 ROC-AUC). Paired external analyses indicated that accuracy and F1-score differences were numerically favorable but not statistically significant, whereas the ROC-AUC improvement on DPI_CDF was statistically supported. Train-to-external homology analysis showed that most external proteins had less than 50% sequence identity to the training set, although residual dataset shift and label heterogeneity may still affect generalization. With cached PLM embeddings, downstream CPU inference required approximately 1.0–1.2 ms per sequence, excluding tokenization and ESM-2 embedding generation. Overall, DrugPLMFormer provides a reproducible, leakage-aware framework for retrospective sequence-based druggability screening and target prioritization, while prospective validation and experimental confirmation remain necessary before operational deployment.