Abstract 2207: Upfront metronomic chemotherapy synergizes with immunotherapy to optimize chemoimmunotherapy in squamous cell lung carcinoma

Abstract

Abstract Background and purpose: For squamous cell lung carcinoma (SQCLC), the survival benefits of combining chemotherapy (at the maximum tolerated dose, MTD) with concurrent immune checkpoint inhibitors (ICIs), also known as chemoimmunotherapy, have been confirmed in recent clinical trials. Nevertheless, the actual relationship between MTD chemotherapy and ICIs remains controversial, as most oncologists considered that MTD chemotherapeutic agents could cause immunosuppression. Hence, we attempted to optimize and assess different combinatorial patterns of chemoimmunotherapy in SQCLC. Methods: We utilized the in vitro SQCLC cell lines, in vivo syngeneic immunocompetent mouse models, and patient samples to fully explore how to increase the ectopic lymphoid-like structures (ELSs) and the therapeutic targets for anti-programmed death 1 (PD-1) / anti PD-1 ligand (PD-L1) monoclonal antibodies (mAbs), as well as the underlying mechanisms, in order to render SQCLC to be more sensitive to ICIs and improve the efficacy of chemoimmunotherapy. Results: Low-dose chemotherapeutic agents induced SQCLC cells to undergo immunogenic cell death (ICD) by activating the PI3K/Akt/NF-κB signaling pathway and thereby enhancing neoantigen exposure. Following, the high mobility group box-1 released by cells undergoing ICD promoted neoantigen uptake and presentation by activating dendritic cells (DCs) and consequently invoking specific T cell responses. In vivo, low-dose chemotherapeutic agents activated systemic immune responses and immunological memory, and enhanced antitumor ELSs compared with routine MTD chemotherapy. Moreover, the upfront metronomic (low-dose and frequent administration) chemotherapy extended the time window of the immunostimulatory effect and synergized better with the subsequent administration of anti-PD-1/PD-L1 mAbs. One possible mechanism of this synergy is increasing the activated type I macrophages, DCs, and cytotoxic CD8+ T cells, and maintaining the diversity and normal composition of intestinal gut microbiota. In contrast, when combined with ICIs, the effects of routine MTD chemotherapy appeared to be additive rather than synergistic. Conclusion: The upfront metronomic chemotherapy better synergizes with immunotherapy over the routine MTD chemotherapy in SQCLC. This preclinical study provides a novel strategy to optimize chemoimmunotherapy, and it is worth being translated into the clinic in the future. Citation Format: Xi-Ran He, Yang Du, Yu-Shen Jin, Hua Bai, Jie Tian, Jie Wang. Upfront metronomic chemotherapy synergizes with immunotherapy to optimize chemoimmunotherapy in squamous cell lung carcinoma [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 2207.