Abstract 579: Mini-tumors: Pre-clinical HCI assays to screen anti-cancer drugs in the context of organoids, cancer-associated fibroblasts and immune cells

Abstract Introduction Effective drug development relies on representative pre-clinical models to discover and characterize novel cancer therapies. Recapitulating the human specific tumor micro-environment (TME) is essential for IO studies or TME-targeting agents and detection of human-specific (off-)target effects to better predict therapeutic response and clinical outcomes. The recently developed patient-derived organoid (PDO) technology, provides access to representative organotypic cultures, established from patient cancer stem cells. These cultures can be further improved by including additional cell types with strong clinical implications, especially cancer-associated fibroblasts (CAFs) and immune cells. Both CAFs and immune cells from various lineages modulate tumor growth and metastasis, drug resistance and immune-mediated cancer cell killing in the TME and have become popular targets for therapy in the recent decades. Here, we present our improved pre-clinical platform for drug testing, consisting of organotypic mini-tumors combined with high-content imaging screening (HCI) to discriminate different cell types and assess morphological, cytostatic and cytotoxic effects of drugs simultaneously. Methods 3D mini-tumor co-cultures were established of allogenic CAFs and PDOs from pancreatic, colon and breast cancer patients. The mini-tumors were expanded in a TME stimulating medium cocktail that drives myofibroblast expansion and differentiation through PDGFRβ and TGFβ signaling. Subsequently, drug responses to various standard of care (SoC) treatments were determined. Additionally, allogenic PBMCs were included in mini-tumor cultures to assess mini-tumor infiltration and killing. Results Mini-tumor co-cultures were successfully established and characterized in different stimulating cocktails. We found mini-tumor sensitivity to SoC treatment to be altered compared to PDO mono-cultures or co-cultures without TME stimulating factors. Moreover, we observed changes in PBMC infiltration and cancer cell killing in mini-tumors grown in TME stimulating conditions. Conclusion and discussion Taken together, our newly developed pre-clinical mini-tumor HCI platform provides the unique opportunity to screen and test drugs targeting human cancer cells, CAFs or immune cells in vitro in a pathology and TME-resembling context. This will ultimately result in effective target validation and mode of action analysis, timeline and cost reductions, and most importantly, a more efficient entry into the clinic. Citation Format: Marten Hornsveld, Guusje Odenkirchen, Cyrelle van Dort, Jara Garcia Mateos, Saskia de Man, Gera Goverse, Bram Herpers, Mariusz Madej, Leo Price, Marrit Putker. Mini-tumors: Pre-clinical HCI assays to screen anti-cancer drugs in the context of organoids, cancer-associated fibroblasts and immune cells [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 579.