Background: Interferon-gamma (IFN-g) is known to play a pivotal role in PD-L1 expression and immune evasion in cancer cells, but there is little known regarding its interactions with premalignant lung lesions. Methods: Immortalized human bronchial epithelial cells (HBEC-vector control), KRAS-mutated (KRASv12) HBEC cells (HBEC-KRAS), p53 knockdown HBEC cells (HBEC-p53), and p53 knockdown/KRAS mutated cells (HBEC-p53/KRAS) were used to assess mRNA expression as well as surface and total protein expression levels of PD-L1 by RT-PCR, flow cytometry, and Western blot before and after treatment with IFN-g. For STAT-1 knockdown, cells were transiently transfected using Lipofectamine RNAiMAX (Thermo Scientific). After 48 hours of transfection, cells were incubated with IFN-g (50 ng/mL) or PBS with 0.1% BSA for 48 hours, then harvested and analyzed by RT-PCR, flow cytometry, and Western blot. An FFPE tissue block from a patient with known premalignant lesions and lung adenocarcinoma was obtained from the UCLA Lung Cancer Tissue Repository and sectioned to create slides for HE Jan 8-11, 2018; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(17_Suppl):Abstract nr B20.