GUCY2C as a Target for CAR-T Cells to Treat Pancreatic Cancer
Background: Pancreatic cancer is an extremely deadly cancer with a survival rate of only 10.8%. Currently, surgical resection is the only potentially curative treatment, with modestly improved survival after resection. This low survival rate, and the minority of patients who present eligible for surgery, indicates the clear need for additional therapies. Guanylyl cyclase C (GUCY2C), a transmembrane protein selectively expressed by normal intestinal epithelial cells, but not normal pancreatic cells, is expressed in select pancreatic adenocarcinomas and is available as a potential target for directed therapy. Chimeric antigen receptor (CAR) T cell therapy genetically reprograms a patient’s own T cells to express a receptor that targets tumor antigens. We have previously shown GUCY2C CAR-T cells efficacy in mouse models of intraperitoneal colorectal cancer, as well as subcutaneous gastric and esophageal cancers. GUCY2C CAR-T cell therapy could serve as an adjunct in pancreatic cancer treatment at multiple points along the clinical management pathway including as adjuvant therapy in resected patients, neoadjuvant therapy in borderline resectable patients, and as primary treatment in metastatic patients. Here, we created an orthotopic mouse model of metastasizing human pancreatic cancer that can be used to test the efficacy of GUCY2C-directed CAR T cells at each stage along the patient management continuum.
Methods: A GUCY2C-expressing pancreatic adenocarcinoma cell line (AsPC-1) as well as two patient derived xenografts (PDXs) from the National Cancer Institute were acquired. GUCY2C expression was confirmed with RNA, protein and shRNA knockdown. Orthotopic mouse models were created by surgically implanting AsPC-1 cells or PDXs into the pancreatic tail. Luciferase was added to AsPC-1 cells using lentiviral transduction to track tumor growth. Biomarker status of PDXs was established to monitor tumor growth and treatment efficacy. GUCY2C CAR-T cells were used in vitro to demonstrate therapeutic efficacy against AsPC-1 cells.
Results: AsPC-1 cells implanted in the pancreatic tail metastasized to liver and lungs, revealed by gross morphology, histology, and quantitative RT-PCR analysis. In that context, luciferase fluorescence permitted monitoring of disease progression by IVIS imaging in vivo, without the need to sacrifice mice. An in vitro killing assay demonstrated that AsPC-1 cells were specifically killed by GUCY2C-directed CAR-T cells, compared to non-directed CAR-T cells. Orthotopic implantation of PDXs produced pancreatic tumors in 100% of recipient mice, which could be monitored using circulating CEA.
Conclusions: GUCY2C is expressed in a proportion of pancreatic adenocarcinomas, but not normal pancreatic tissue. We have established the efficacy of our GUCY2C-targeted CAR-T cells in in vivo models of disseminated intraperitoneal colorectal cancer, as well as subcutaneous gastric and esophageal cancers models, in mice. Moving forward, we will use this newly created orthotopic model of pancreatic cancer to explore the efficacy of GUCY2C-directd CAR T cells to treat primary and metastatic tumors, to improve the management of patients along the entire disease continuum.
Crutcher, MD, Madison, "GUCY2C as a Target for CAR-T Cells to Treat Pancreatic Cancer" (2022). Department of Surgery Resident Research Day. Paper 49.