The IgG4 hinge with CD28 transmembrane domain improves VHH-based CAR T cells targeting a membrane-distal epitope of GPC1 in pancreatic cancer oleh Nan Li, Alex Quan, Dan Li, Jiajia Pan, Hua Ren, Gerard Hoeltzel, Natalia de Val, Dana Ashworth, Weiming Ni, Jing Zhou, Sean Mackay, Stephen M. Hewitt, Raul Cachau, Mitchell Ho