Abstract B02: Tissue-specific innate lymphoid cells are novel targets for pancreatic cancer immunotherapy

Pancreatic ductal adenocarcinoma (PDAC) is the classic cold tumor, with few tumor-infiltrating activated CD8+ T cells, a major barrier to immunotherapy. Strategies to convert cold PDACs to hot can enable more effective immunotherapies. To identify targets that can convert cold PDACs to hot, we compared a large cohort of rare long-term PDAC survivors with hot tumors to short-term survivors with cold tumors. Surprisingly, hot PDACs were enriched not only in activated CD8+ T cells, but also in group-2 innate lymphoid cells (ILC2s), a class of largely tissue-resident, cytokine-producing innate lymphocyte that potentiates T cell immunity in local tissues. We identified that tumor ILC2s (TILC2s) infiltrate human and mouse PDACs, and TILC2 frequency and tumor expression of the ILC2-activating ligand interleukin (IL)-33 positively correlate with tumor immune cytolytic activity, and long-term patient survival. Using PDAC mouse models, we discovered that the IL33-ILC2 axis activates pancreatic tissue-specific antitumor T-cell immunity. Host IL33 deficiency attenuated TILC2 expansion and CD8+ T-cell activation, accelerating tumor growth in orthotopic PDACs but not heterotopic skin implanted PDACs where TILC2s lack the IL33 receptor. Acute ILC2 depletion partially phenocopied the tissue-specific phenotype of IL33 deficiency, with impaired rejection of immunogenic orthotopic but not heterotopic skin PDACs. Treatment with recombinant IL33 (rIL33), but not with the ILC1-activating ligand rIL18, increased TILC2 frequencies, activated CD8+ T cells, and abrogated orthotopic but not heterotopic PDAC establishment in u003e70% of mice. Taken together, these studies identify ILC2s as novel anticancer immune cells for PDAC immunotherapy. Strategies to activate tissue-specific ILC2s may be a promising immunotherapeutic approach for PDAC. Citation Format: Joanne Leung, Luis A Rojas, Jennifer Ruan, Julia Zhao, Billel Gasmi, Zachary Sethna, Anita Ramnarain, Umesh Bhanot, Gokce Askan, Murali Gururajan, Ela Elyada, Youngkyu Park, David A. Tuveson, Mithat Gonen, Steven D. Leach, Jedd D. Wolchok, Ronald P. DeMatteo, Taha Merghoub, Vinod P. Balachandran, John Alec Moral. Tissue-specific innate lymphoid cells are novel targets for pancreatic cancer immunotherapy [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr B02.