Early apoptotic measurements of patient-derived organoids predict patient response to platinum therapy

Increasingly, determining how effective a drug will be for an individual cancer patient, as well as identifying novel compounds that may be beneficial to a specific population requires the use of primary patient tumor cells. Patient-derived organoids represent an intermediate between primary tumor cells, whose limited supply may hinder reliable drug testing, and established cell lines, which have usually been subject to countless generations of selection and adaptation. 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 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. We compare with other methods of analysis of ex vivo drug sensitivity and find that 3D DBP provides better predictive information. While we have previously demonstrated the predictive power of image-based BH3 profiling in two-dimensional cultures, this work extends DBP to three-dimensional cultures where imaging is more challenging. In summary, we not only have created a means of visualizing drug response in intact organoids, but also have demonstrated its potential clinical utility.