Abstract Precision medicine's goal of achieving a better response rate by avoiding ineffective therapies has sparked new approaches, including the testing of patient-derived 3d (PD3Ds) tumor cultures for modeling individual patient response, and the use of various molecular pathology techniques for advanced tumor profiling. An intrinsic limitation of well-established genomics methodologies is, however, that they cannot directly assess cell-signaling activity within the tumor cells defined by the phosphorylation status of cellular signaling pathway networks. Here we present the development of a robust protein profiling strategy utilizing the DigiWest immuno-assay platform, to obtain data on the activation status of key cellular signaling networks implicated in cancer, and on proteins targeted by FDA-approved drugs. This includes targeted cancer therapies for e.g. EGFR, HER2, PI3K, mTOR, ALK and AKT. Accordingly, we compiled a list of relevant pathway nodes and their phosphorylation sites that yield activity information on RAS/RAF/ERK, PI3K/AKT and mTOR signaling pathways. Based on this, we validated 242 total and phospho antibodies in a pre-set oncoproteomic DigiWest panel that yields information on the activity of all major signaling pathways from the receptor level down to transcription factors, apoptosis and proliferation. This oncoproteomic panel can be utilized for elucidating drug response in pre-clinical cell models, in PD3D organoid models or in clinical tumor samples. Exemplary, we show differential activation states in cancer cell lines representing the most prevalent cancer types and the impact of pathway activation in different models. Finally, we tested this panel in PD3D organoids that were subjected to screening against common targeted therapies. While the initial results are promising, further work on evaluating how such an oncoproteomic panel profiling might contribute to the rationale for personalized therapy decisions is required. Disclosure Statement: NMI TT Pharmaservices offers DigiWest protein profiling as a service. CELLphenomics offers PD3D cell cultures and drug testing as a service. Citation Format: Gerrit Erdmann, Przemylaw Dudys, Anja Arndt, Christian Regenbrecht, Markus Templin, Christoph Sachse. Beyond genomics - A precision oncology approach utilizing multiplex protein profiling for tumor and tumor organoid samples [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 810.
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