Abstract:  Lung cancer is the tumor with the highest morbidity and mortality. About 75% of patients are already in the advanced stage at the time of diagnosis. Liver metastasis is an important factor leading to the poor prognosis of lung cancer patients. About 20% of patients with non-small cell lung cancer (NSCLC) will develop liver metastases. In recent years, immune checkpoint inhibitors (ICI) monotherapy and combination therapy have made breakthrough progress in patients with advanced NSCLC. Clinical studies suggested that patients with liver metastases could also benefit from ICI therapy, however compared to the overall population, liver metastasis was still an independent prognostic factor for poor efficacy of immunotherapy. Therefore, exploration of the resistance mechanism of patients with liver metastases is of great significance to improve the survival prognosis of this population. Tumor microenvironment (TME) phenotype is a key factor in determining the efficacy of immunotherapy. The specific difference in TME among different organs may be an important reason for their different responses to immunotherapy. A variety of cellular components in the liver interact to form its complex immune microenvironment and participate in the immune regulation of the liver. Therefore, this article was intended to focus on the liver immune microenvironment and the latest progress in immunotherapy to summarize the domestic and foreign research progress in NSCLC liver metastasis. We hope to provide novel insights for the development of new treatment strategies for patients with liver metastases.

Key words: Non-small cell lung cancer, Liver metastasis, Tumor microenvironment, Immune checkpoint inhibitor