Engineering adoptive T cell therapy for efficacy in ovarian cancer
Kristin G. Anderson1, Breanna M. Bates2, Edison Y. Chiu3, Philip D. Greenberg1
1University of Washington and Fred Hutchinson Cancer Research Center, 2Fred Hutchinson Cancer Research Center, 3University of Washington
Over 20,000 women are diagnosed with ovarian cancer annually—more than half will die within 5 years and this rate has changed very little in the last 20 years, highlighting the need for innovative therapies. One promising new treatment strategy has the potential to control tumor growth without toxicity to healthy tissues, by employing immune T cells engineered to target proteins uniquely overexpressed in tumors. Recent technological advances have helped identify and validate Wilms’ Tumor Antigen 1 (WT1) and mesothelin (MSLN) as valid antigen targets for ovarian cancer, as these proteins contribute to malignant and invasive phenotypes and have limited expression in healthy cells. In preclinical studies using either patient-derived cell lines or the mouse ID8 ovarian tumor model, we found that T cells engineered to express either a WT1- or MSLN- specific high-affinity T cell receptor (TCR) can kill human and murine ovarian tumor cells in vitro. Moreover, in a disseminated in vivo murine model, adoptively transferred TCR-engineered T cells preferentially accumulated within established ID8 tumors, delayed ovarian tumor growth and prolonged mouse survival. However, our data also revealed that the tumor microenvironment (TME) can limit engineered T cell persistence and killing capacity. Cellular and molecular analyses showed human therapy will face similar TME-mediated obstacles. The ovarian cancer TME is a nutrient- and oxygen-deprived milieu, and adaptive metabolic responses by infiltrating T cells have protean effects on T cell function. Thus, strategies that modulate T cell metabolic pathways and thereby influence activity in the TME might enhance T cell function and improve anti-tumor efficacy by overcoming a critical component of immune evasion by solid tumors. Ongoing studies will be discussed that are exploring strategies to overcome elements common to the human and murine TME, including direct modulation of the environment and T cell engineering to promote T cell survival and function.