American Association for Cancer Research
00085472can203564-sup-254245_2_supp_7033963_qr4cyj.pdf (1.06 MB)

Supplementary Figures from Inhibition of Granulocytic Myeloid-Derived Suppressor Cells Overcomes Resistance to Immune Checkpoint Inhibition in LKB1-Deficient Non–Small Cell Lung Cancer

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journal contribution
posted on 2023-03-31, 04:28 authored by Rui Li, Ramin Salehi-Rad, William Crosson, Milica Momcilovic, Raymond J. Lim, Stephanie L. Ong, Zi Ling Huang, Tianhao Zhang, Jensen Abascal, Camelia Dumitras, Zhe Jing, Stacy J. Park, Kostyantyn Krysan, David B. Shackelford, Linh M. Tran, Bin Liu, Steven M. Dubinett

Supplemental Figures S1-S6


National Cancer Institute

National Heart Lung and Blood Institute

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LKB1 inactivating mutations are commonly observed in patients with KRAS-mutant non–small cell lung cancer (NSCLC). Although treatment of NSCLC with immune checkpoint inhibitors (ICI) has resulted in improved overall survival in a subset of patients, studies have revealed that co-occurring KRAS/LKB1 mutations drive primary resistance to ICIs in NSCLC. Effective therapeutic options that overcome ICI resistance in LKB1-mutant NSCLC are limited. Here, we report that loss of LKB1 results in increased secretion of the C–X–C motif (CXC) chemokines with an NH2-terminal Glu-Leu-Arg (ELR) motif in premalignant and cancerous cells, as well as in genetically engineered murine models (GEMM) of NSCLC. Heightened levels of ELR+ CXC chemokines in LKB1-deficient murine models of NSCLC positively correlated with increased abundance of granulocytic myeloid-derived suppressor cells (G-MDSC) locally within the tumor microenvironment and systemically in peripheral blood and spleen. Depletion of G-MDSCs with antibody or functional inhibition via all-trans-retinoic acid (ATRA) led to enhanced antitumor T-cell responses and sensitized LKB1-deficent murine tumors to PD-1 blockade. Combination therapy with anti–PD-1 and ATRA improved local and systemic T-cell proliferation and generated tumor-specific immunity. Our findings implicate ELR+ CXC chemokine-mediated enrichment of G-MDSCs as a potential mediator of immunosuppression in LKB1-deficient NSCLC and provide a rationale for using ATRA in combination with anti–PD-1 therapy in patients with LKB1-deficient NSCLC refractory to ICIs. These findings show that accumulation of myeloid-derived suppressor cells in LKB1-deficient non–small cell lung cancer can be overcome via treatment with all-trans-retinoic acid, sensitizing tumors to immunotherapy.

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