Abstract 243: Organoid co-cultures with allogenic T cells to assess toxicity and efficacy of bispecific antibodies

Abstract Recent advances in cancer immunotherapy positively impacted the life expectancy of patients for an extensive range of clinical indications. With new treatment strategies, druggable targets and biomarkers being identified at an increasing pace, the number of patients eligible for cancer immunotherapy is expected to expand steadily. For example, the emerging Bispecific T cell Engagers (BiTEs) designed to simultaneously target CD3 and tumor-specific antigens and promote T cell cytotoxicity have seen recent clinical success. While BiTEs have been approved for the treatment of hematologic malignancies, promising therapeutic developments for solid tumors face hurdles in translating preclinical findings into therapy since conventional two-dimensional cancer models fail to recapitulate the immune cell interactions in the tumor microenvironment and therefore hold low clinical predictive value. We developed an innovative alternative, building on the discovery that adult stem cells proliferate and organize into three-dimensional organotypic structures that maintain complex characteristics of the original parental tissue, including molecular heterogeneity and morphological and functional traits. Here, we show the development of a patient-relevant preclinical platform for immunotherapy development in which colorectal (CRC) and non-small cell lung cancer (NSCLC) organoids are co-cultured with allogenic or autologous T cells to evaluate the activity and assess the cytotoxic potential of a BiTEs. The expression of tumor-specific BiTE target antigens is determined in patient-derived organoids (PDOs) by flow cytometry. Following this assessment, T cell-induced organoid death is quantified and characterized in real-time by image-based analysis of fluorescent live/dead dyes. Additionally, we measure cytokine secretion as a read-out of T cell activation and function. In our co-cultures, T cell-induced PDO death was increased upon BiTEs treatment. Similarly, IFNγ secretion correlated with expression levels of the targeted tumor antigen. In addition, PDO apoptosis and IFNγ secretion increased in a dose-dependent fashion in the presence of the TA-targeting TCB. In summary, our organoids and T cell co-cultures offer a powerful platform for developing and validating immunotherapies such as T cell-bispecific antibodies and will significantly contribute to our understanding of the critical factors determining successful immunotherapies. Citation Format: Cesar Oyarce, Virginia Bruno, Lorenzo Spagnuolo, Claudia Beaurivage, Javier Frias Aldeguer, Farzin Pourfarzad, Robert G. Vries, Sylvia F. Boj. Organoid co-cultures with allogenic T cells to assess toxicity and efficacy of bispecific antibodies abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 243.