CAR-T Cells – Main Steps for Obtaining a Proper “Live Drug” Adoptive Therapy

Abstract

Chimaeric antigen receptor (CAR) T lymphocytes (CAR-T) discovered in 1992 have been in the recent years in the spotlight of both researchers and clinicians. Immune therapy with engineered CAR-T cells has been approved by the FDA since 2017 for pediatric and young adult acute lymphoblastic leukemia. Since then, around ten therapies were approved for hematological cancers. In contrast to the other immune therapies CAR-T cell therapy is considered a “living drug” with the capacity of self-replicating. Having this particular characteristic, the manufacturing process has in general several steps that should be followed in the process of obtaining specific CAR-T cells. There are mandatory steps for obtaining a CAR-T cell culture: Leukapheresis, activation, gene delivery, expansion, and cryopreservation. All these seminal stages have various sub-stages that can differ from one procedure to other as detailed in the paper. Leukapheresis harvests peripheral blood mononuclear cells, followed by an enrichment of a certain cellular population or a depletion phase to remove contaminants as red blood cells and platelets. T cell population that is obtained needs to be activated using activating antibodies (Abs), magnetic beads coated with activating Abs or artificial antigen-presenting cells. After activation, T cells are subjected to genetic engineering that can be done using electroporation of naked DNA, plasmids, or viral vectors to insert the specific CAR. The last phases of CAR-T cell manufacturing are the expansion of these specific cells and, if not freshly inoculated to the patients, the final step is cryopreservation. The main drawback of CAR-T cell therapy is its high cost; therefore, new automated platforms would decrease their cost. The described stages are still variable within CAR-T manufacturing. Therefore, the future of this immune therapy will have to tackle standardization and automated technology, directions that will increase healthcare system availability.