Most ovarian cancer patients (+/-900 new cases in Belgium annually) are diagnosed at an advanced stage of the disease, resulting in a poor prognosis. Standard therapy schemes are applied to all epithelial ovarian cancers, but specific histologic subtypes like clear cell carcinoma do not respond and are often excluded from clinical trials. We aim to develop an in vivo predictive test for treatment response. Mice models are currently the gold standard for patient derived tumor xenografts. However, clinical applications are limited because of the high amount of donor material required and the long experimental duration. Very promising are zebrafish PDX platforms which are cost-effective, require much less donor material and are able to predict initial therapy response within 2 weeks. We propose such a platform, suitable for engraftment of both tumor tissue and circulating tumor cells, allowing adequate follow-up during therapies in a minimally-invasive manner. This proposal responds perfectly to the demand of pharmaceutical industries and oncologists to better stratify patients for therapies, also for rare subtypes. As several therapies can be tested in a short time, this platform would not only be an added value for phase 2 and 3 clinical trials, but also in standard clinical practice. This project clearly fits within the Flemish priority transition objectives for health and well-being.