LAUSR

The use of imperfect models and ex vivo culture systems to try to predict patient drug response represents an enormous bottle neck in cancer treatment. Nonetheless, determining how effective an approved drug will be for an individual cancer patient, as well as identifying novel compounds that may be beneficial to a specific population often requires the use of primary tumor cells. Patient-derived organoids represent an intermediate between primary tumor cells, whose limited supply may hinder reliable drug testing, and cell lines, which often do not reflect what happens in vivo. Herein, we describe the development of a novel assay platform, termed 3D-DBP (3D dynamic BH3 profiling), to detect early apoptotic measurements in ovarian cancer patient-derived organoids and present evidence that this method can be used to predict patient response to therapy. We have optimized the use of patient-derived organoids from 16 individual tumors in a microscopy-based imaging assay. We image the BH3 peptide-induced release of cytochrome c from mitochondria, which indicates permeabilization of the outer mitochondrial membrane, in intact organoids. The less cytochrome c retained in each organoid, the more primed that organoid is for apoptosis. By comparing results of drug-treated and untreated cells, we can identify drugs that cause a significant increase in apoptotic priming in organoids. In the 16 patient-derived organoids investigated this 3D DBP technique was an effective means of predicting patient response to carboplatin therapy. In summary, we have not only created a means of visualizing drug response in intact organoids, but also have demonstrated its clinical utility. Citation Format: Kelley E. McQueeney, Patrick Bhola, Sarah J. Hill, Anthony Letai. Early apoptotic measurements of patient-derived organoids predict patient response to therapy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4309.