Abstract 6094: SRC inhibitor saracatinib enhances efficacy of PD-1/PD-L1 immune checkpoint blockade in non-small cell lung cancer

Abstract

Abstract Background: Although immune checkpoint inhibitors (ICI) included PD-1/PD-L1 have demonstrated durable therapeutic responses in some cases, a significant portion of patients with cancer remain nonresponsive (e.g. only ~20% with anti-PD-1 in lung cancer). Substantial limitations in the rate of response underscore the need for suitable combination therapies. SRC family kinases is overexpressed or activated in multiple human malignancies, as a candidate target in regulating antitumor immunity. Saracatinib, an orally bioavailable multi-kinase inhibitor, has demonstrated clinical efficacy in CML. Here, we proved saracatinib as SRC inhibitor that were capable of increasing the antitumor immunity in non-small lung cancer. Method: Cytotoxicity assays were used to determined antitumor activities of saracatinib in non-small lung cancer cell lines. The expression of PD-L1 expression in saracatinib 1 treated cell lines was investigated by western blots, quantitative PCR and flow cytometry. The effect of saracatinib in antitumor immunity alone or in combination with immunotherapy was also determined in vitro and in vivo. RNAi, overexpression, and gene expression analyses were used to define underlying mechanisms. Result: We found that SRC inhibitor saracatinib robustly decreased expression of PD-L1 in non-small lung cancer cells and animal models. The observed inhibitory effect was time- and concentration-dependent. Furthermore, our results showed that saracatinib and anti-PD-L1 combined to improve T-cell-mediated killing of tumor cells in vitro and in vivo, which were associated with activation of CD8+ T cytotoxic cell included expression of IFN-γ and granzyme-B. Prolonged survival was also observed in mice treated with saracatinib in combination with PD-L1 blockade. Conclusion: Our in vivo and in vitro data demonstrated that SRC inhibitor saracatinib enhance T-cell-mediated anti-tumor immune responses in non-small lung cancer. We also provide evidence that support the combination of saracatinib and anti-PD-1/PD-L1 as a potential combination therapeutic approach to increase the efficacy of immunotherapy in non-small lung cancer. Citation Format: Fei-Teng Lu, Fan Luo, Miao-Zhen Qiu, Jia-Xin Cao, Qiu-Yun Luo, Da-Jun Yang, Hong-Yun Zhao. SRC inhibitor saracatinib enhances efficacy of PD-1/PD-L1 immune checkpoint blockade in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6094.