Abstract 319: Impact of Chemotherapy on Lung Cancer Cells and Their Microenvironment, Evaluated in Tridimensional Multicellular Tumor Spheroids

Abstract Introduction: Pembrolizumab, an anti-PD1 antibody, is approved in non pretreated advanced Non Small Cell Lung Cancer (NSCLC) with high expression of PD-L1, more than 50 %, on tumor cells. Conversely, the combination of platinum-based chemotherapy + pembrolizumab in this indication is not restricted to the level of PD-L1 expression. This suggests that chemotherapy could sensitize tumor tissue to Immune Checkpoint Inhibitors (ICIs). Based on those clinical datas, we propose to evaluate the impact of chemotherapy on tumor cells and on their microenvironment by using tridimensional multicellular tumor spheroids (MCTS). Material and methods: MCTS integrated lung adenocarcinoma cells expressing GFP, fibroblasts with ruby fluorescent protein and monocytes/macrophages from healthy donors. MCTS were treated with repeated and combined chemotherapy drugs (carboplatin and gemcitabine, or carboplatin and paclitaxel), reproducing therapeutic schedules. Different biological factors were analysed : impact of chemotherapy on MCTS morphology, cell viability, invasion abilities, modifications in genes and protein expression profiles using differential gene expression sequencing (DGE-Seq) and flow cytometry, respectively. Results: Chemotherapy decreased MCTS size and cell viability. Whereas carboplatin/gemcitabine mainly affected lung cancer cells inside MCTS, carboplatin/paclitaxel seemed to be cytotoxic mainly on peripheral malignant cells. Fibroblasts were resistant to chemotherapy, unlike macrophages which were strongly affected. A large RNA analysis was performed using DGE-Seq and showed that expression of several genes, and notably of CD274 (PD-L1) and CD273 (PD-L2), were induced after treatment. We confirmed PD-L1 up-regulation byflow cytometry. Conclusion: Platinium-based chemotherapy up-regulate immune checkpoints expression in lung cancer cells. Our results are in line with the latest studies performed in mice. They underline that our MCTS model is closed to in vivo conditions. It could be developedas a drug screening tool. Citation Format: Pauline Hulo, Sophie Deshayes, Virginie Dehame, Marc Grégoire, Jaafar Bennouna, Christophe Blanquart. Impact of chemotherapy on lung cancer cells and their microenvironment, evaluated in tridimensional multicellular tumor spheroids [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 319.