Abstract PS17-42: A fast and effective 3D preclinical assay system comprised of patient derived breast cancer microtumors combined with DigiWest protein signaling pathway analyses for therapeutic response prediction (Project PRIMO)
Authors: Anderle Nicole , Ruoff Felix , Yuez Simge , Koch André , Hartkopf Andreas , Brucker Sara , Pawlak Michael , Templin Markus , Schmees Christian 
Published: February 2021

Abstract
In the era of personalized medicine, the ability of pre-selecting individualized therapeutic options and pre-defining their suitability in advance of clinical treatment might facilitate decision making in breast cancer treatment and hence, improve patient outcome. In order to preclinically validate anti-cancer drug efficacy, it is crucial to design a model system that reveals the influence of cellular interactions of the tumor microenvironment and cellular heterogeneity on drug response. Within the PRIMO (Personalized Medicine for tailored cancer therapies) project, such a 3D preclinical model system comprised of patient-derived microtumors (PDM) and autologous tumor-infiltrating lymphocytes (TILs) isolated from fresh primary breast cancer tissue using limited digestion and subsequent culture in defined media in the absence of serum is established. Herein, the heterogeneous cellular composition of isolated PDM is analyzed by FFPE immunohistochemistry and compared to corresponding primary tumor tissue. The composition of autologous TILs influencing individual treatment responses is characterized by multi-color flow cytometry detecting different cell populations, such as tumor-specific CD8+ or regulatory CD4+ T-cells. By using the DigiWest technology, a proprietary high throughput immune assay screening tool, in-depth protein profiling of up to 200 analytes from low amounts of PDM material is performed. The generated protein profiles of PDM are compared to their corresponding primary tumor tissue as well as the pathological receptor grading. Furthermore, differences in activation of key signal transduction pathways are detected and related to treatment responses to small molecules, chemotherapeutics as well as immunotherapeutic agents within PDM and PDM-TIL co-cultures assessed by a functional viability assay in a microplate format. To expand this preclinical model system, we established PDM-co-cultures adding further immune cell types including natural killer (NK) cells or dendritic cells (DC).
In summary, immunohistochemical analyses combined with protein profiling of breast cancer PDM enables drug-mode-of-action analyses, biomarker identification together with personalized therapeutic sensitivity prediction. The platform presented here expands the preclinical repertoire of relevant test systems for efficacy testing of drugs and investigational compounds, pre-identified by protein pathways as well as genetic profiling in personalized medicine of breast cancer.
Citation Format: Nicole Anderle, Felix Ruoff, Simge Yuez, André Koch, Andreas Hartkopf, Sara Brucker, Michael Pawlak, Markus Templin, Christian Schmees. A fast and effective 3D preclinical assay system comprised of patient derived breast cancer microtumors combined with DigiWest protein signaling pathway analyses for therapeutic response prediction (Project PRIMO) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS17-42.