Despite the tremendous clinical success of CAR-T-cell therapy in leukemia, translation of this treatment option to solid tumors still remains challenging. Off-target toxicity of CAR-T-cells against low-level antigen expressing healthy tissue is considered to be the most dangerous scenario when treating cancer patients yielding eventually to at least one reported fatal SAE. To avoid such fatalities a straight assessment of target antigen expression including all known isoforms of the respective protein in tumors as well as healthy tissues must be performed before drug application. The breast differentiation antigen NY-BR-1 (ANKRD30A) is known to serve as a perfect antigen for active immunotherapy of female breast cancer due to absence of expression in any female healthy tissue except for mammary gland. Here we report on the critical evaluation of NY-BR-1 as a target antigen for CAR-T-cells using bioinformatics, staining procedures and functional CAR tests. While bioinformatic analyses and stainings using the anti-NY-BR-1 monoclonal antibody “clone2” confirmed previous findings, we observed different results when the respective “clone2 scFv” was used. This construct not only shows a higher binding capacity to NY-BR-1 but also a modest but detectable binding to the isoform NY-BR1.1 (ANKRD30B). Additionally, a CAR-construct based on “clone2 scFv” yielded into a cross-reactivity of T cells against NY-BR1.1. Due to the known expression of NY-BR1.1 in normal brain tissue in combination with the also known ability of CAR-T-cells to cross the blood brain barrier, the use of a “clone2 CAR” for the treatment of advanced breast cancer must be judged as dangerous. Our findings show that a critical evaluation of a candidate target antigen for CAR therapy shall be performed by the use of the respective scFv rather than the classical mAb approach.
Citation Format: Patrick Schmidt, Claudia Luckner Minden, Claudia Ziegelmeier, Isabella Gosch, Niels Halama, Frank Momburg, Rosa Eurich, Sarah Schott, Frederik Marmé, Andreas Schneeweiß, Claus Peter Heußel, Dirk Jäger, Inka Zörnig. Evaluation of NY-BR-1 as a suitable antigen for CAR based immunotherapy [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B054.
- ©2016 American Association for Cancer Research.