2.1 CART therapy and CRISPR Cas9
One of the most successful innovations in the area of hematology is the CRISPR/Cas9-edited chimeric antigen receptor (CAR) T cell (CAR-T cell), which is additionally a primary leap forward in the area of immunotherapy and was approved by the FDA for the treatment of leukemia and lymphoma 21,22.
Eshhar 23 et al. first suggested structural and functional similarities between endogenous αβT cell receptors (TCRs) and antibodies. Target cells carrying 2,4,6-trinitrophenyl (TNP) semi-antigenic motifs can be recognized by chimeric TCR chains, which consist of immunoglobulin V region and TCR C region, and do not elicit immune response from the receptor as well as rejection. B cells specifically express CD19, while CART cells modified by the CRISPR Cas9 gene themselves in particular recognize CD19 in addition to their T lymphocyte-borne killing function, thus specifically killing tumor cells with long-lasting effects 24,25.
However, there are a couple of elements that have an effect on the efficacy of CAR-T therapy, together with T cell status, individual specificity, etc.
Patients treated with CAR-T cells may develop serious adverse effects, such as tumor lysis syndrome and cytokine release syndrome (CRS), and although these syndromes are manageable, they may become serious complications if not managed properly.
Delivery of bound CAR and CRISPR RNA through electroporation with lentivirus leads to injury of TCR and β-2-microglobulin (B2M) genes, ensuing in homozygous CAR T cells missing TCR, HLA type I molecules and PD1; as Fas receptor / Fas ligand (FasL) induces T cell apoptosis, CTLA-4, PD- 1, LAG-3 and TIM-3 are T cell suppressor receptors or signaling molecules whose expression motives T cell failure 26-28, therefore, knockdown of these elements through CRISPR Cas9 can decrease T cell apoptosis and amplify CAR T cells and therefore decorate their function.