CDK4/6 inhibitors reverse primary resistance to anti-PD-1 therapy in LKB1-deficient lung adenocarcinoma

LKB1 deficiency in lung adenocarcinoma (LUAD) leads to primary resistance to immune checkpoint inhibitors. However, the underlying molecular mechanism remains unclear. Here, we showed that LKB1 deficiency significantly affected the tumor immune landscape by decreasing the infiltration of most immunocyte populations and downregulating the expression of intercellular adhesion molecule-1 (ICAM1). LKB1 deficiency promoted cancer evasion due to loss of ICAM1-mediated antitumor immunity, including immune-competent cell cytotoxicity and tumor infiltration. CDK4/6 inhibitors reversed this process in a targeted manner. A tailored combination strategy using CDK4/6 inhibitors and anti-PD-1 antibodies slowed tumor growth and increased survival in syngeneic mouse models of LKB1-deficient lung adenocarcinoma. Combining a CDK4/6 inhibitor, which is clinically approved, with PD-1 blockade therapy is thus a promising option for lung adenocarcinoma patients harboring LKB1 mutations. RNA-sequencing of murine tumor specimens administered with different treatments: vehicle, palbociclib, anti-PD-1 antibody, or their combination. 3 replicates for each group.