Abstract Introduction: The treatment of ovarian cancer is consists principally in radical surgery followed by chemotherapy. Patients generally respond well to first line chemotherapy (70%) but consistently relapse within 18 months, with successive rounds of chemotherapy delivering extremely low patient benefit. Despite every cancer being unique, generally all cancer patients are treated by the same chemotherapy regimes. In previous decades an approach has been to use chemosensitivity assays based on cells isolated from solid tumors to predict chemotherapy response. However, it the metastatic cancer cell (not cells in the primary tumor) that is the true target of chemotherapy. In our laboratory we have resurrected the concept of chemosensitivity but focusing exclusively on cells that have escaped the primary tumor and are potentially enriched in stem-cell like properties. Our objective was to isolate potential ovarian metastatic cells from patients and coorelate their in vitro response to the chemotherapy observed in the patient. Materials and methods: Primary cultures of ovarian cancer ascites (peritoneal fluid) were obtained with signed informed consent from a network of Chilean hospitals and potential metastatic cells cultivated. Chemotherapy response was assessed by MTS and data correlated with CA125 levels, imaging and medical criteria. Results: Analysis of 39 ovarian cancer patients with clinical follow-up demonstrated an average progression free survival of 18 months for patients predicted to respond by our assay, but only 2 months in predicted non-responders. The assay corrected identified 5 of the 6 patients who did not respond to first line carboplatin-paclitaxel therapy. Discussion: We demonstrate a clear distinction in time to relapse between patients predicted to respond in our assay as opposed to patients with no predicted clinical response, demonstrating the requirement to take this research to the stage of randomized clinical trials. Funding BMRC CTU06 & FONDECYT 3120003 and 1120292 Citation Format: Maria L. Bravo, Pamela Gonzalez, Sumie Kato, Marcelo Garrido, Jorge Brañes, Javier Pizarro, Maria Isabel Barriga, Hector Leon, Eva Bustamante, Catalina Alonso, Erasmo Bravo, Miguel Angel Celis, Barbara Aguilera, Alejandro Barra, Nicanor Barrena, Carolina Ibañez, Paula Jimenez, Mauricio Cuello, Gareth Owen. Personalized cancer therapy for ovarian cancer patients. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1187. doi:10.1158/1538-7445.AM2013-1187