Shaping the future one slice at a time: How 3D organotypic tumour slice models are driving drug discovery in ovarian cancer.

Despite therapeutic advancements, ovarian cancer remains one of the most lethal gynaecological malignancies, highlighting the urgent need for innovative drug discovery approaches. Traditional 2D cell line models fail to accurately replicate the complexity of the tumour and its microenvironment (TME), leading to suboptimal drug evaluations. Organotypic tumour slice culture (OTSC) has emerged as a promising 3D ex vivo platform that preserves native tissue architecture, cellular interactions, and molecular heterogeneity of the tumour and its TME, providing a more physiologically relevant system for drug testing. This review examines the evolution of OTSC in ovarian cancer and its applications across chemotherapy, targeted therapy, immunotherapy, and virotherapy. We highlight the role of OTSC in identifying predictive biomarkers of drug response, drug resistance mechanisms - including those in the stroma - and elucidating novel therapeutic strategies. While OTSC has demonstrated its ability to rapidly provide insights into patient-specific responses, further integration of advanced multi-omics analyses could enhance its potential as a precision medicine platform. With its 3D heterogenic complexity, OTSC could also facilitate the development and evaluation of TME-directed therapies, novel multitarget drugs, and tumour-targeting drug delivery systems, ultimately shaping the future of ovarian cancer therapy and improving clinical outcomes.