Abstract 3332: Cancer organoid growth rate as a phenotypic marker to predict adjuvant chemotherapy outcomes in ovarian cancer patients

Abstract Background: Patient-derived organoid (PDO)-based drug sensitivity tests have been utilized to predict patient outcomes, such as recurrence after adjuvant chemotherapy, by assessing the drug response of patient-derived organoids. This study introduces a multi-parameter assay platform called Organoid Growth-based Oncological Sensitivity Test (OncoSensi) for predicting recurrence of adjuvant therapy in patients with Epithelial Ovarian Cancer (EOC). Patient-derived organoid (PDO)-based drug sensitivity tests have been utilized to predict patient recurrence after adjuvant therapy by assessing the drug response of PDOs. However, we found that PDO growth rates vary among individuals, and it is a very important factor in predicting patient recurrence. Methods: Among 135 patients, 95 ovarian cancer patients were followed up for recurrence over a 2-year period after receiving adjuvant chemotherapy (Paclitaxel/Carboplatin). PDOs derived from these 95 patients were utilized to measure growth rates and drug responses without subculturing. Recurrence-free survival rates were compared between responders and non-responders identified by OncoSensi. Results: In this study, we propose an organoid growth-based Oncological Sensitivity Test (OncoSensi) that utilizes the PDO growth rate-based approach to specifically improve the prediction of adjuvant therapy outcomes (recurrence) in patients with EOC. Comparing conventional drug sensitivity tests that considered only single parameters such as the area under the curve (AUC), the proposed OncoSensi algorithm showed improved 6-month, 1-year, 1.5-year recurrence prediction performance in patients with EOC. The recurrence rate within one year for responder groups in OncoSensi is 4.76 %, which is three times lower than the 14.29 % recurrence rate of the previous sensitivity test. For non-responder groups, the recurrence rate within one year for OncoSensi is 41.51 %, which is higher than the 33.96% of the previous sensitivity test. In addition, the responder and non-responder groups were statistically well distinguished (P-value < 0.0001) under OncoSensi index-based analysis conditions. Thus, the good recurrence prediction performance was confirmed using the OncoSensi algorithm. The recurrence rate within one year for responder groups in OncoSensi is 4.76 %, which is three times lower than the 14.29 % recurrence rate of the previous sensitivity test. For non-responder groups, the recurrence rate within one year for OncoSensi is 41.51 %, which is higher than the 33.96% of the previous sensitivity test. Citation Format: Dong Woo Lee, Sang-Yun Lee, Sung Hun Ju, Bosung Ku, Yongmun Choi, Jeong Woo Lee. Cancer organoid growth rate as a phenotypic marker to predict adjuvant chemotherapy outcomes in ovarian cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3332.