Tumor-intrinsic PIK3CA represses tumor immunogenicity in a model of pancreatic cancer

The presence of tumor-infiltrating T cells is associated with favorable patient outcomes, yet most pancreatic cancers are immunologically silent and resistant to currently available immunotherapies. Here we show using a syngeneic orthotopic implantation model of pancreatic cancer that Pik3ca regulates tumor immunogenicity. Genetic silencing of Pik3ca in KrasG12D/Trp53R172H-driven pancreatic tumors resulted in infiltration of T cells, complete tumor regression, and 100% survival of immunocompetent host mice. By contrast, Pik3ca-null tumors implanted in T cell–deficient mice progressed and killed all of the animals. Adoptive transfer of tumor antigen–experienced T cells eliminated Pik3ca-null tumors in immunodeficient mice. Loss of PIK3CA or inhibition of its effector AKT increased the expression of MHC class I and CD80 on tumor cells. These changes contributed to the increased susceptibility of Pik3ca-null tumors to T cell surveillance. Our results indicate that tumor cell PIK3CA-AKT signaling limits T cell recognition and clearance of pancreatic cancer cells. Strategies that target this pathway may yield an effective immunotherapy for this cancer.

Source: Journal of Clinical Investigation - July 16, 2019 Category: Biomedical Science Authors: Nithya Sivaram, Patrick A. McLaughlin, Han V. Han, Oleksi Petrenko, Ya-Ping Jiang, Lisa M. Ballou, Kien Pham, Chen Liu, Adrianus W.M. van der Velden, Richard Z. Lin Source Type: research