Pancreatic cancer represents the fourth leading cause of cancer-related death in developed countries. Despite remarkable advances in the understanding of its molecular pathophysiology, treatment options remain scarce, highlighting the need for novel therapies. Adoptive cell transfer (ACT) of lymphocytes engineered ex vivo to express chimeric antigen receptors (CAR) has come of age as a safe and clinically efficacious treatment for advanced cancers.

We sought to develop a CAR specific for prostate stem cell antigen (PSCA), a glycoprotein with restricted expression in normal tissues that is over-expressed in pancreatic cancer cells starting at early stages of malignant transformation.

In order to establish the optimal CAR design, we generated constructs containing antigen-recognition domains derived from mouse or human antibodies, and intracellular domains containing one or two co-stimulatory domains, in addition to CD3zeta. We compared multiple constructs and found that a CAR based on human monoclonal antibody Ha1-4.117 had greater reactivity in vitro. Using a murine model of ACT we observed that CAR-engineered human lymphocytes induced an antitumor effect on HPAC xenografts. Interestingly, unlike what has been described for other CARs, a second generation PSCA CAR (containing CD28 signaling domain) induced a more potent antitumor effect than its third generation counterpart (containing CD28 and 41BB domains).

Our results provide evidence to support PSCA as a target antigen for immunotherapy of pancreatic cancer, using adoptively transferred autologous lymphocytes engineered to express an Ha1-4.117-based CAR.

Citation Format: Daniel Abate-Daga, Kiran H. Lagisetty, Luca Gattinoni, Zhiya Yu, Nicholas P. Restifo, Steven A. Rosenberg, Richard A. Morgan. Development of a fully-human chimeric antigen receptor against PSCA for the treatment of pancreatic cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3966. doi:10.1158/1538-7445.AM2013-3966