Patient-Derived Organoid-Based CRISPR Screens in Cancer Research: Applications, Advances, and Challenges.

Patient-derived organoids (PDOs) have emerged as physiologically relevant cancer models that preserve key genetic, histological, and functional features of the tumors from which they are derived. In parallel, CRISPR-based perturbation technologies have transformed functional genomics by enabling scalable interrogation of gene function. Their integration provides a powerful framework for identifying cancer dependencies, modeling oncogenic evolution, and investigating mechanisms of drug response and resistance in patient-relevant settings. This review examines how CRISPR knockout, CRISPR interference/activation, and precision editing approaches have been applied in PDO systems to uncover context-specific vulnerabilities, reconstruct mutational trajectories, and study tumor heterogeneity. We further compare pooled and arrayed screening formats and discuss what is uniquely enabled by performing CRISPR screens in organoids rather than conventional 2D models. Particular emphasis is placed on the technical and analytical constraints of organoid-based screening, including variable editing efficiency, clonal bottlenecks, biological heterogeneity, and limited scalability. We argue that the major value of organoid-based CRISPR screening lies in its ability to identify functionally actionable cancer vulnerabilities in a patient-contextualized model, while also introducing methodological challenges that must be addressed for robust clinical translation.