IL-7 armed binary CAR T cell strategy to augment potency against solid tumors

Alejandro Guadalupe Torres Chavez¹Katie McKenna¹Anmol Gupta²Neha Daga³Juan Vera⁴Ann Leen¹Pradip Bajgain^5*

• ¹Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, Texas, United States
• ²University of Michigan Hospital, Department of Internal Medicine, Ann Arbor, United States
• ³Temple University School of Podiatric Medicine, Philadelphia, United States
• ⁴Marker Therapeutics, Houston, Texas, United States
• ⁵Tumor Angiogenesis Unit, Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, United States

Clinical studies of T cells engineered with chimeric antigen receptor (CAR) targeting CD19 in B-cell malignancies have demonstrated that relapse due to target antigen (CD19) loss or limited CAR T cell persistence is a common occurrence. The possibility of such events is greater in solid tumors, which typically display more heterogeneous antigen expression patterns and are known to directly suppress effector cell proliferation and persistence. T cell engineering strategies to overcome these barriers are being explored. However, strategies to simultaneously address both antigen heterogeneity and T cell longevity, while localizing anti-tumor effects at disease sites, remain limited. In this study we explore a dual antigen targeting strategy by directing independent CARs against the solid tumor targets PSCA and MUC1. To enhance functional persistence in a tumor-localized manner, we expressed the transgenic IL-7 cytokine and receptor (IL-7Rα) in respective CAR products. We now demonstrate the potency and durable antitumor effects of this binary strategy in a pancreatic tumor model.