ScreenShot: A Foundation Model for Few-Shot Combination Drug Screening
Combinatorial drug screening is hindered by an expansive search space, high costs, and scarce patient samples, while existing approaches rely heavily on molecular profiling and cohort-specific training, limiting their clinical applicability. This work proposes ScreenShot, a hierarchical Transformer-based foundation model pretrained on 40 drug screening datasets, which leverages in-context learning to predict individual patient responses to combination therapies directly from minimal functional assay data—without requiring molecular profiles or task-specific fine-tuning. ScreenShot achieves, for the first time, few-shot prediction of combinatorial drug responses in a zero-fine-tuning, profile-free setting, and integrates a weighted k-means++ active learning strategy to guide experimental design. Evaluated on four independent test sets, ScreenShot outperforms baseline methods in both response prediction accuracy and identification of effective treatments; its active learning strategy attains the hit-detection performance of uniform screening using only one-third of the experimental budget.