Three-dimensional cancer models have gained popularity for in vitro studies of chemotherapeutic compounds by providing a more physiologically relevant analog of gas, nutrient, and drug diffusion throughout the tumor microenvironment. Some 3D assays are performed to study individual spheroids over time, where a majority of these assays rely on maintaining a single spheroid in each well of a 96-well round-bottom ultra-low attachment plate, limiting the number of spheroids in a study. Other assays may gather population-level data from large ensembles of spheroids grown together, but the information about individual differences amongst the spheroids is lost. Important kinetic information may also be lost for destructive endpoint assays such as MTS or MTT. Here, we describe the development of a 3D image cytometry assay that is capable of generating kinetic data for thousands of breast cancer spheroids at the individual level. T47D spheroids are grown and maintained in a 24-well Aggrewell࣪400 plate and imaged using the Celigo image cytometer. Each well contains more than 1000 subwells that both aid in spheroid formation and constrain each spheroid to a specific location. Using the spheroid location data, we are able to track and monitor the growth of each spheroid over 7 days. Furthermore, we investigate the dose-dependent effects on spheroid viability of 6 anti-cancer drugs (Doxorubicin, Everolimus, Gemcitabine, Metformin, Paclitaxel and Tamoxifen) using calcein AM and propidium iodide (PI). To validate the viability measurement results, we utilize the CellTiter96® MTS assay as an orthogonal method to compare the dose-dependent trends using both the calcein AM and PI fluorescence intensities as well as the spheroid sizes. This work may lay a foundation for the investigation of other spheroids, organoids, or tissue samples, significantly increasing the number of spheroids analyzed per condition, improving the statistical analysis, and adding more parameters to further analyze the spheroids. These improvements may be especially helpful for spheroids grown from patient-derived or otherwise heterogeneous cell populations

Citation Format: Jordan Bell, Shilpaa Mukundan, Matthew Teryek, Bo Lin, Biju Parekkadan, Leo Chan. High-throughput chemotherapeutic drug screening of tumor spheroids with individual spheroid results using image cytometry [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 184.