Application of R19M, An FMC63 scFv Idiotype Monoclonal Antibody

Anti-CD19 CAR-T cell therapy

With the development of cancer immunotherapy, Chimeric AntigenReceptor (CAR)-T cell, which combines the advantages of antibodyand immune cells, has attracted tremendous attention. CAR ismainly composed of a cell membrane extracellular antigen bindingregion and an intracellular signal transduction region through a hingeregion and a transmembrane region. The extracellular antigenbinding domain can specifically recognize and bind to a target cellsurface antigen. It is derived from a single-chain variable region(scFv) of a monoclonal antibody. The intracellular signal transductiondomain is mainly composed of a costimulatory signal and a CD3zetachain of T cell receptor (TCR). After CAR-T cells binding to the targetcell antigen through the scFv, the intracellular signal transductionregion transmits signals to the T cell, thereby activates T cell, whichin turn results secretion of perforin, granzymes and interferons. TheFDA has approved two CAR-T cell therapies in 2018, namelyKymriah of Novartis and Yescarta of Gilead. Both of them aredirected against CD19-positive B-cell tumors, using the sameantigen-binding region, the scFv derived from the mousemonoclonal antibody FMC63.

Detection of CAR-T cells

Generation of CAR-T cell requires transfection of the CAR gene intoT cell via a viral or non-viral system. When the CAR is expressed onthe membrane of T cell, CAR-T cell then has the activity ofrecognizing and killing the target cells. Therefore, accurate detectionof CAR-positive T cells is a key step in the quality control of CAR-Ttherapy, and an important criterial in clinical dose control, processmonitoring and assistant diagnosis. There are two common types ofdetection methods: detection of CAR gene-positive T cells anddetection of CAR protein-positive T cells.