Abstract LB-344: MAP4K4 as a therapeutic target and novel biomarker for NSCLC

Introduction: Biomarker-guided personalized targeted therapies have improved lung cancer treatment; however, non-small cell lung cancer (NSCLC) targets such as KRAS — where activated mutations occur in ∼30% of cases — have so far eluded attempts at therapeutic targeting. There continues to be an urgent need to identify molecular mechanisms driving the disease and new targeted therapies. Mitogen-Activated Protein Kinase Kinase Kinase Kinase 4 (MAP4K4) overexpression promotes migration and invasion in several cancer types and correlates with poor prognosis in lung cancer. We investigated the role of MAP4K4 in NSCLC and tested whether MAP4K4 could serve as a biomarker on circulating tumor cells (CTCs) to monitor pre-metastatic and late stage disease. Methods: We used a novel class of highly selective small molecule inhibitor of MAP4K4, represented by SRI-28731, as a tool to further elucidate the role of MAP4K4 in NSCLC. We measured the expression of MAP4K4 and signaling changes following compound inhibition in lung cancer cell lines by immunoblotting and immunofluorescence. Clonogenic and wound healing assays were performed using our selective compound to assess proliferation and migration. To determine if MAP4K4 could be used as a biomarker in liquid biopsies we used FASTcell™, a non-enrichment optical scanning technology that enables identification and characterization of 1 tumor cell in 25 million blood cells. Results: We confirmed high expression of MAP4K4 in 4 out of 7 lung cancer cell lines, including A549 cells, and 3 of these harbored KRAS mutations. By clonogenic assay, A549 cell proliferation was inhibited by 51% and 99% with 2.5 nM and 5 nM of SRI-28731, respectively. In addition, lung cancer cell migration was impaired in the presence of 10 or 20 nM SRI-28731. Smad 1/5/8 phosphorylation was decreased in cells treated with the MAP4K4 inhibitor. Compound treated cells displayed a change in their actin cytoskeleton compared to DMSO treated cells. To explore whether MAP4K4 could be used as a biomarker on CTCs of metastatic NSCLC patients, we utilized the FASTcell™ platform and detected MAP4K4 expression on A549 cells mixed into normal blood. We are in the process of testing the assay with additional lung cancer cell lines and also testing MAP4K4 expression on CTCs from lung cancer patients. Conclusions: Our preliminary data suggest a role for MAP4K4 in proliferation, migration and signaling in lung cancer. Inhibition of MAP4K4 may be a valid therapeutic approach and the expression of MAP4K4 may serve as a biomarker in liquid biopsies. We showed that high levels of MAP4K4 in human lung cancer cell lines was concomitant to KRAS mutations, suggesting a possible correlation between the two markers. This novel biomarker could provide an opportunity to detect KRAS-positive cancers earlier and our new selective inhibitor could lead to life-saving, personalized treatment options for NSCLC cancer patients. Citation Format: Claire E. Repellin, Xiaohe Liu, Mary R. Stofega, Janey C.L. Snider, Zheng Ao, Ling Jong, Lidia C. Sambucetti. MAP4K4 as a therapeutic target and novel biomarker for NSCLC. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-344.