A critical issue with using CAR-T cells is that they can only be activated when the antigen in the target tumor cell is exposed and captured, meaning some antigen-less tumor cells could escape from CAR-T cells. along with their disadvantages and limitations that still need to be overcome. Keywords: CAR-T, switch molecule, universal CAR-T, allogeneic, cancer 1. Introduction Known as a living drug, CAR-T cell therapy has been intensively performed over the past decade. Promising research data have been accumulated and more efficient and controllable CAR-T cells have been developed. At first, CAR-T therapy was tested on patients with hematological cancers. Especially, patients with B-cell Acute Lymphoblastic Leukemia (B-ALL) without improvement with known therapies such as hematopoietic stem cell transplantation (HSCT) and chemotherapies were tested on, since CAR-T therapy was the last treatment option. Currently, two CAR-T cell drugs, YESCARTA (axicabtagene ciloleucel) and KYMRIAH (tisagenlecleucel), are FDA approved to, respectively, treat adult patients with certain types of large B-cell lymphoma who have not responded to or who have relapsed after at least two other kinds of treatment and to treat patients up to 25 years of age with B-cell precursor ALL that is refractory CP-809101 or in second or later relapse. Three other CAR-T with an International Nonproprietary Name (INN), vadacabtagene leraleucel, idecabtagene vicleucel, and lisocabtagene maraleucel, are referenced in IMGT/mAb-DB, from IMGT?, the international ImMunoGeneTics information system? [1]. Even though there are still side-effects during CAR-T therapy such as cytokine release syndrome (CRS) and neurotoxicity, recent studies using modified CAR-T cells through various advanced techniques showed promising results for using CAR-T cells more efficiently and CP-809101 safely. The efficient and CP-809101 safe usage of CAR-T cells may include the following concepts: (1) production of CAR-T cells before injecting them back into the patients should be done fast to avoid further progression of disease. (2) CAR-T cells could be used both allogeneically and universally. Gene editing is the most widely used technique to create universal CAR-T cells. A major target for this system is the T cell receptor (TR) [2] to minimize Graft-versus-Host Disease (GvHD) that normally occurs during allogeneic transplantation. To minimize GvHD, chemotherapy regimens including immunosuppressive combinations of Fludarabine and Cyclophosphamide, and serotherapy using Alemtuzumab (anti-CD52 mAb) could be administered ahead of allogeneic CAR-T treatment [3]. Another advantage of TR depleted CAR-T cells is usually that they can be used off-the-shelf. Even though autologous CAR-T therapy works well for GvHD, the time needed to prepare CAR-T cells using T cells obtained from the patients is usually too long and the disease may progress further before the CAR-T therapy can commence. Indeed, previous reports studying patients with diffuse large B-cell lymphoma or follicular lymphoma showed that 26% (10 of 38) of patients did not receive Tisagenlecleucel treatment due to the rapid disease progression [4]. In another study of children and young adults with B-cell lymphoblastic Leukemia, 7.6% (7 of 92) of patients also did not receive Tisagenlecleucel treatment due to death [5]. By preparing CAR-T cells for each disease in advance, it is possible to promptly use prepared CAR-T cells whenever needed. A further point to critically consider when using CAR-T cells as a drug is the careful handling of the side-effects. Since the curative effect of CAR-T cells stem mainly from various released cytokines, common side-effects are often associated with uncontrolled cytokine release and could be very harmful; for instance, some cytokines can penetrate the blood brain barrier (BBB) and cause neurotoxicity [6]. To prevent this problem, various safety switches have been developed such as the incorporation of suicide genes, expression of known target genes for therapeutic antibodies, and the addition of molecular switch proteins between CAR and tumor cells. In this review, we summarized the techniques used to generate allogeneic and universal CAR-T cells and discuss their advantages and considerations for their wide use. 2. General CAR Structure The early trial to create CAR-T cells fused VHsp6 to C or C, and found that VHC or VHC chimeric chains can form heterodimers with or chains of the recipient T cell [7]. This was the first system to escape the MHC-restricted manner of T cell activation. RHOJ The signaling domain name of CAR has subsequently been engineered by adding a signaling domain name of CD247 (First generation CAR), adding one co-stimulation domain name either of TNFRSF9 or CD28 plus the CD247 domain name (Second generation CAR), adding two co-stimulation domains of both CD28 and.