LKB1/STK11 Expression in Lung Adenocarcinoma and Associations With Patterns of Recurrence.

BACKGROUND: Mutations in the serine/threonine kinase 11 (STK11)/liver kinase B1 (LKB1) have been implicated in mediating resistance to checkpoint blockade among patients with advanced lung adenocarcinoma. We sought to examine the associations between clinicopathologic characteristics, tumor LKB1 expression, features of the immune microenvironment, and postoperative prognosis among patients with early stage lung adenocarcinoma undergoing surgical therapy. METHODS: Formalin-fixed, paraffin-embedded specimens of patients undergoing resection of stage I to III, chemotherapy-naïve adenocarcinomas (1997 to 2008) were analyzed using tissue microarray sectioning. Sublobar resections were excluded. Intratumoral LKB1/STK11 expression was quantified as H-score. In a subset, tumor-associated immune cell populations were quantified using whole tumor sections in peritumoral and intratumoral compartments. RESULTS: In all, 104 patients met inclusion criteria. Expression of LKB1/STK11 (median H-score 102.9) was higher in women (median 123.3) than in men (100, P = .004) and in never-smokers (median 145) than in former/current smokers (100, P = .002). Expression of LKB1/STK11 was positively correlated with intratumoral infiltration of cluster of differentiation (CD) 3+ (r = 0.351, P = .005), CD4+ (r = 0.436, P < .001), and CD8+ (r = 0.263, P = .049) cells. Patients with extrathoracic recurrence had lower tumor expression of LKB1/STK11 than did other patients with recurrent disease. On multivariate analysis, low LKB1/STK11 expression remained independently associated with poor disease-free survival and distant disease-free survival. CONCLUSIONS: Low LKB1/STK11 expression is associated with specific patient characteristics and poor postoperative prognosis in chemotherapy-naïve lung adenocarcinoma. Further investigation is warranted to delineate its clinical significance in the context of evaluating novel therapeutic agents in patients with resectable disease.