LAUSR

Tumor diversity and rarity of patient tumor material negatively contribute to the development of new effective treatments for sarcomas. As a high proportion of sarcoma patients presents inherent or acquired chemo-resistance, immune checkpoint inhibitors could represent an alternative for these cases. However, only a small fraction of sarcoma patients seem to respond to immune checkpoint therapy, suggesting the existance of heterogenous immune-suppressive mechanisms across individuals and sarcoma subtypes. Therefore, new strategies to boost the immune system, together with tools predicting which patients could benefit from therapy, are needed for sarcoma patients. There is still a lack of methods that take advantage of benefits, such as low consumption of patient material or reagents, offered by miniaturized in vitro analysis systems. In this work, we used a novel multichambered microwell chip for testing personalized immunotherapy on patient-derived sarcoma spheroids. We derived multiple primary sarcoma spheroids from various sarcoma subtypes and grades, which were used to test NK cell cytotoxicity in combination with anti-TIGIT, anti-PD-L1, anti-EGFR treatment. Using this combinatorial strategy, we could boost NK-mediated killing significantly. We analyzed immune cell infiltration in the original tumor and found PD-1+ and TIGIT+ cytotoxic lymphocytes in both peripheral and central tumor tissues, suggesting that anti-TIGIT and anti-PD-L1 therapy could be appropriate in some sarcoma patients. In addition, high levels of pro-inflammatory cytokines were found in plasma from sarcoma patients, together with high levels of soluble PVR. This work provides a better understanding of immune surveillance of sarcoma and shows an important implementation of patient-derived spheroids. The miniaturized format allowing long-term cell culture, efficient screening and high-quality imaging of small sample volumes makes this methodology promising for personalized immunotherapy. Citation Format: Valentina Carannante, Niklas Sandström, Karl Olofsson, Shi Yong Neo, Patrick Albert Sandoz, Hanna Van Ooijen, Quentin Verron, Jacopo Fontana, Damien Toullec, Elisabeth Moussaud-Lamodière, Brinton Seashore-Ludlow, Thomas Frisk, Madoka Takai, Päivi Östling, Felix Haglund, Andreas Lundqvist, Martin Wiklund, Björn Önfelt. Miniaturized and multiplexed evaluation of NK cell cytotoxicity and infiltration in patient-derived sarcoma spheroids using a novel multichambered microwell chip. [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 4578.