Abstract 584: Developing a novel engineered T cell to target resistant pancreatic cancer
Authors: Yazdanifar Mahboubeh , Zhou Ru , Wu Shu-ta , Grover Priyanka , Mukherjee Pinku 
Published: August 2019

Background: Pancreatic cancer is the 3rd leading cause of cancer mortality in the USA recently surpassing breast cancer. Treatment options are limited to surgery and chemo/radiation, which is normally associated with high toxicity. Targeted immune-based therapies have shown promising results but needs further exploration. Mucin 1 (MUC1), a glycoprotein expressed on the apical surface of epithelial cells, undergoes hypoglycozylation in tumors. This tumor-form of MUC1 (tMUC1) is over-expressed in 80% of pancreatic ductal adenocarcinomas (PDA). We have developed an antibody (TAB004) which specifically detects tMUC1 and not the normal MUC1. Functional fragments of TAB004 antibody (scFv) were incorporated into the chimeric antigen receptor (CAR) construct and used to genetically modify primary human T cells. tMUC1 recognizing domain (TAB004 scFv) is linked to the co-stimulatory molecules of T cells (CD28 and CD3ζ). These CAR T cells are highly activated and reactive to MUC1 expressing tumor cells. Pancreatic cancer is highly resistant to many treatments including immunotherapy. We suggest combining our CAR T cell treatment with low dose chemotherapy drug to improve the treatment efficacy.

Methods: CAR gene was transduced into human T cells using retroviral based technique. Cytotoxicity was evaluated using co-culture method with varying T cell to target cell ratios followed by MTT and LDH assay. Released IFNy, granzyme B and Perforin were measured by flow cytometry and ELISA. To investigate the mechanism involved in resistance of some PDA cells, cancer cells and T cells marker were evaluated by flow cytometry and gene expression profile of sensitive vs resistant cancer cells was assessed by Real-time PCR.

Results: tMUC1-CAR-T cells show increased activation and proliferation compared to normal T cells. Engineered tMUC1-CAR T cells exhibit binding and robust cytotoxicity against a panel of PDA cell lines, associated with high IFNγ, granzyme B and Perforin release. Fortunately, the same CAR T cells display minimum binding and toxicity against normal epithelial cells. CAR T cell function is evaluated in the preclinical mouse model of PDA, as single treatment and in combination with chemotherapy drugs. Several genes expression altered in cancer cells before and after treating with CAR T cells. Combining the CAR T cells with low dose chemotherapy drug (Gemcitabine and 5-FU) improved efficacy of the treatment for resistant PDA cells.

Conclusion: Our results validate the idea of using anti MUC1 CAR T cells to treat pancreatic ductal adenocarcinoma. This therapy has shown to be working synergistically with low dose chemotherapy drug with improved function in treating resistant PDA cells. Hence, tMUC1 CAR T cells have the potential to be further developed for clinical use on resistant PDA.

Citation Format: Mahboubeh Yazdanifar, Ru Zhou, Shu-ta Wu, Priyanka Grover, Pinku Mukherjee. Developing a novel engineered T cell to target resistant pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 584.