PROJECT SUMMARY/ABSTRACT Despite breaking advances in melanoma treatment such as adoptive cell transfer and immune checkpoint blockade, the clinical outcomes remain unsatisfactory due to various factors that limit the efficacy of the therapies. To meet these challenges in immunotherapy for solid tumors, this project aims to define eukaryotic elongation factor-2 kinase (eEF-2K) as a novel and effective immune-modulatory target that can be exploited to significantly improve effectiveness of the current cancer immunotherapy. eEF-2K belongs to the family of atypical α-kinases and is an evolutionarily conserved regulator of protein synthesis, a molecular process that affects energy metabolism. This kinase phosphorylates eEF-2, a 100-kDa protein that promotes ribosomal translocation from the A to P-site, the reaction that induces movement of mRNA along the ribosome during translation. Phosphorylated eEF2 is unable to catalyze ribosomal translocation, thereby inhibiting peptide elongation. Our preliminary studies strongly suggest that eEF-2K is an as-yet- unappreciated but critical regulator of antitumor immunity and that integrative targeting of this kinase may beneficially maximize the potency of immunotherapeutic intervention against melanoma, one of the most aggressive and fatal neoplasms responsible for over 80% of skin cancer-related deaths. Building on our preliminary observations that eEF-2K is not only highly expressed in melanoma cells and patient specimens and contributes to poor therapeutic outcomes, but is also abundantly expressed in immune cells such as T cells and regulates their functional activity, we propose to test the central hypothesis that eEF-2K modulates antitumor immunity via its regulatory roles in both tumor cells and tumor-reactive immune cells, and integrative targeting of eEF-2K could be exploited as an innovative therapeutic strategy for treatment of melanoma. Through comprehensive cellular, molecular, and pre-clinical studies, this multiple PIs’ project will pursue the following highly related and interactive aims: (1) Determine the role and in-depth mechanism of eEF-2K in immune evasion; (2) Define the role of eEF-2K as a regulator of tumor-reactive immune cells; (3) Evaluate the antitumor efficacy of the eEF-2K-based and integrative targeted therapy. We have established the humanized mouse (NOD-scid IL2Rgnull) melanoma models as well as murine syngeneic melanoma systems for this research and are well poised to accomplish the above objectives. This research is innovative and significant because successful completion of this project would not only reveal eEF-2K as a novel and effective immuno-modulatory target for overcoming tumor immune-resistance as well as regulating immune cell functions, but also provide new therapeutic opportunities to substantially improve immunotherapy for advanced treatment-refractory melanoma through the eEF-2K-based integrative- targeted approach.

Project Narrative Melanoma, one of the most aggressive and fatal neoplasms, is the 5th most frequent cancer in men and 7th most frequent cancer in women and is responsible for over 80% of the skin cancer-related deaths. By investigating the role and mechanism of elongation factor-2 kinase (eEF-2K) as a novel immunomodulatory target and by assessing the antitumor efficacy of the eEF-2K-based integrative targeted therapy, we wish to provide innovative and effective immunotherapeutic strategies for patients with immune poor-responsive melanoma.