Abstract 164: Development of a living biobank of breast cancer organoids

Abstract Introduction: Breast cancer is one of the most frequently diagnosed cancers among women, with a high mortality rate. More than 20 different subtypes of breast cancer are identified. Advancement in patient-derived organoid technology makes it possible to preserve cellular, structural, and tissue microenvironment, which mimics the tissue in vivo. The present study aims to develop a cryopreserved (living) tumor biobank from patient-derived tumor breast tissues. Eventually, biobank organoids will be used to test treatment options outside of patients, in a dish, and provide information on what treatments the patient responds to. Method: Patient-derived organoids (PDOs) were bio-fabricated using an unsorted tumor and normal cell suspension in a collagen-based hydrogel. Immune-enhanced tumor organoids (iTOs) were also bio-fabricated using patient-matched PMBCs and tumor cells. Breast cancer living biobanks were developed by freezing organoids in cryopreservation solutions and reestablishing them in growth media compatible with breast organoids. Histological staining for hormone receptors and Her2 receptor markers was performed. Organoids were cultured for seven days, followed by treatment with chemotherapy (Paclitaxel, Doxorubicin, and Sulphonamide) and immunotherapy (Nivolumab, Pembrolizumab, and Atezolizumab), and assessed for cell viability. Results: H&E staining showed the characteristics of the breast tissue with well-defined acini. In tumor organoids, acini were somewhat perturbed compared to normal breast organoids. Immunofluorescence staining showed the expression of breast biomarkers, including EGF receptor 2 (HER2), Progesterone receptor (PR), and Estrogen receptor (ER). Zona occludin 2 and keratin 19 expression in luminal cells and expression of Keratin 14 and P63 in basal cells, suggesting correct polarization in the organoids. Immunofluorescence staining of iTOs, with T cell markers including CD3, CD4, and CD8, indicated that immune cells remained viable in the iTOs. Drug responses to Doxorubicin, Paclitaxel, Sulphonamide and a combination of Doxorubicin-Paclitaxel showed significant inhibition of cell growth in normal and tumor organoids (p< 0.04). Treatment of breast iTOs showed moderate responses to nivolumab (n=11) and pembrolizumab (n=5), with a 63%-100% efficacy (P < 0.05) respectively. No responses were observed for Atezolizumab (n=5). Drug responses of biobank organoids showed comparable drug sensitivities to their fresh, non-frozen counterparts, suggesting that biobank organoids retain physiological relevant information and can be used for testing new drug therapies. Conclusion: Breast cancer organoids recapitulate the histological features of breast tissue in culture and respond to chemotherapy and immunotherapy. In the future, patient-derived breast tumor organoids can be cryopreserved and serve as living biobanks to provide a platform for personalized medicine. Citation Format: Nadeem Wajih, Richard Erali, Edward A. Levine, Konstantinos Votanopoulos, Shay Soker. Development of a living biobank of breast cancer organoids [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 164.