CAR-T Cells in the Treatment of Chronic Lymphocytic Leukemia

CAR-T prison cells in the Treatment of Chronic Lymphocytic LeukemiaAbstract crabby person has always been a difficult line of work to be solved by benignants, of which leukemia is one of them. With the development of cistron recombination technology and our in-depth understanding of placecer, chimeral antigen sensory receptor T stalls (CAR-T) mass be carried out in clinical trials. Recently, CAR-T has make bare-assed progress in the treatment of acute and continuing lymphocytic leukemia. CAR-T cells are T-cell receptor gene and anti-CD19 anti torso gene backrest, transfection to T cells, in vitro addition later transfer to patients for the treatment of leukemia new immunotherapy. The come forth of the modified CAR-T cells has a specific binding site, which merchant ship recognize the CD19 antigen on the surface of B cells in lymphoblastic leukemia. CD19 antigen preserve stimulate the continuous activating and proliferation of CAR-T, CAR-T in the patients frame merchantman be multiplied hundreds of durations, effectively killing acute and degenerative lymphocytic leukemia cells.Keywords car-t cell therapy, chronic lymphocytic leukemia1. CAR-T principleWith the development of gene recombination technology, the specific anti clay can be stably verbalised on the surface of T cells, so that it has a specific antigen epitope. Chimeric antigen receptor T cell immunotherapy is carried out on the basis of a cellular immunotherapy. The chimeric anti-gen receptor (CARs) is an antigen-recognition airfield composed of a specific antibody in the extracellular domain and an antigen-chimeric protein composed of the intracellular CDC3- chain or FcI protein linked to the transmembrane domain1. After the CARs are recognized and stimulated by specific antigens, they can provide activation signals for T cells and conduct the signals finished the intracellular domain, which results in the activation of cells, which are CARs dependent cell activation and cytotoxicity, and cytokines Release 2. In order to addition the cytotoxicity of CARs, the proliferation of signal transduction was achieved by constructing co-stimulatory molecules connected to the extracellular CD3C in the intracellular domain, resulting in a multiplication of the cell killing effect, which greatly enhanced the CARs Cell killing effect 3. Generation of CARs intracellular contains yet if one activation domain, so its specificity in the identification of tumor cell-associated antigens subsequently killing effect is very limited 4. Second-generation CARs contain an activation domain and a co-stimulatory domain, much(prenominal) as CD28 or 4-1BB 5-6. The three-generation CARs are composed of the activation domain and multiple co-stimulatory domains, such as CD27, CD28, 4-1BB and OX40. The increase of these domains not only increases the ability of CAR-T cells to specific wholey recognize TAA and binding , More able to substantively extend the extracellular area of the cell signal transmission, causing overthrow directs of cell killing cascade 7. With the amelioration of structural design of CARs and the improvement of tumor preying and killing, the researchers encounter constructed many other intracellular co-stimulatory molecular structures, including CD134, Lck, ICOS and DAP10 8. In addition, CD19-derived CAR-T cells were merely engineered by researchers at the Duke University Center for Immunology to autocrine IL-12, which whitethorn or whitethorn not be required in specific syngeneic tumor models Pretreatment chemotherapy, if further extended to clinical patients can be in the lower nerve effects to obtain better readiness 9. Therefore, the continuous innovation of CARs think technologies is not only the structural optimization, tho in addition the construction of more costimulatory molecules in function. The efficiency and function of CAR-T cells will be further improved.2. commence specific CAR-T cellsCD19 is a autho risation target for B-cell neoplasms and can be expressed in normal B cells, follicular dendritic cells, cancerous B cells, and precursor B cells in addition to hematopoietic stem cells 10. bully and chronic lymphocytic leukemia is usually accompanied by CD19 expression, but in other lymphoid system tumor expression is not the same. Jena and others done genetic modification technology for the first time utilise to chronic viral vector, the CD19 + specific chimeric antigen receptorand expression of B cells, transfected into the patients T cells, the revolution of T cells called CD19-specific CAR -T cells 11. These T cells in vitro aft(prenominal) a spectacular turn of events of amplification, re-enter the acute and chronic lymphocytic leukemia patients play a role in the body. CD19-specific CAR-T cells are able to recognize leukemia specific CD19 targets and clitoris B-cells from CD19 cells by releasing a variety of cytokines, thereby promoting the clearance of malignant tum or cells. The results show that, later on retroviral gene transfection of T cells, in clinical employments is safe and effective 12. CD19-specific CAR-T cells have been shown to be effective in fight CD19 + tumor cell lines and in vivo B-cell tumors in animals 13. In immunodeficient mice, CD19 + T cells can be effectively removed by the addition of CD19 + T cells 14.3. CAR-T cells in the treatment of chronic lymphocytic leukemiaChronic lymphocytic leukemia (CLL) is a slow-growing, indifferent(p) B-cell leukemia, usually occurring in adults, and many patients can have no symptoms for some(prenominal) days, compared with other types of leukemia. Currently CLL has no specific treatment options, no patent symptoms of CLL advocates observation and wait, mainly symptomatic treatment, drug therapy is difficult to achieve long remission and clinical cure. Genetically modified CAR-T cells have a significant therapeutical effect on B-cell malignancies. The New England Journal subjec t fielded in June that the June Task Force 15 successfully enured 3 patients with CLL with CAR-T cells for the first time, 2 of whom were still in complete remission after 2 years of follow-up. They subsequently found that 16, the infusion of CAR-T cells in patients with peripheral fall and drum shopping centre in a large number of survival, proliferation in the body more than 1000 times, effective removal of CLL cells function can be maintained for more than 6 months. not only that, some CAR-T cells are even in the form of recollection cells that produce a fast retort when re-exposed to CLL cells. The mechanisms by which CAR-T cells proliferate and survive in vivo are unclear, probably due to the activation or release of cytokines by normal B cells and CD19-expressing leukemic cells in the internal environment. The cytokines such as IFN-r, CXCL9, IL-6 and soluble IL-2 receptor change magnitude significantly after CAR-T cells entered the body, reaching a backsheesh on the twenty-third day after transfusion. Elevated cytokines in bone marrow were conformable with reduced levels of leukemic cells, but TNF levels in peripheral assembly line and bone marrow did not vary significantly. The number of CAR-T cells in vivo was detected by RT-PCR, and the ratio of cells increased 1000-fold on the 21st day after transfection, business relationship for more than 20% of the peripheral blood lymphocytes. The number of CAR-T cells was consistent with the time of oncolytic syndrome and elevated levels of cytokines. The doubling time of CAR-T cells in peripheral blood was nearly 1.2 days and the half-life was 31 days. It is noteworthy that cytotoxic side effects such as cytokine release syndrome and macrophage activation syndrome may occur after treatment with CAR-T cell immunotherapy. These symptoms and children hemophagocytic syndrome, lymphoproliferative disease occurs in similar cytokine act 17. Cytokine storm is due to CAR-T cells kill B cells ca apply by tumor cell lysis, characterized by inflammation, long-term fever, hepatosplenomegaly, cell reduction. At this point the laboratory examination of patients with ferritin, triglyceride, transaminase, bilirubin, soluble IL-2 receptor a chain were increased and fibrinogen reduction 18. CAR-T cells after the input, the patients peripheral blood and bone marrow loss of B cells and hypogammaglobulinaemia up to 6 months or more, but patients do not necessarily have re on-going infection. If the clinical symptoms require symptomatic treatment, the number of CAR-T cells in the patients body or the anti-tumor effect will not be significantly shanghaied. In the past, patients treated with rituximab, after a few months of treatment, B cells can piecemeal pick up. Whether this phenomenon will occur in patients with CAR-T cell immunotherapy is still unclear. Because CAR-T cells can proliferate extensively and produce cytotoxicity in vivo, CAR-T cell-specific detection is needed in the cut of cl inical treatment 19, and timely prevention of adverse reactions occurs.4. ill reactions and treatmentAlthough CAR-T cell therapy has achieved surprising clinical results, but have to defend that there are still many cell treatment act upon risk, adverse reactions after treatment for the treatment of a great test. Because CAR-T can proliferate in vivo and produce severe cytotoxic effects on target cells, the most common and serious is cytokine release syndrome (CRS) 20. In the current report of CAR-T cells in the treatment of blood cancer cases, almost all appeared in different severity of the CRS response. CRS is mainly due to the large number of cells after activation, including circulating IL-6, ferritin, INF, IL-2, granulocyte colony stimulating factor IL-10, IL-8, IL-5, including rapid increase in cytokines Caused by fever without cause of infection, persistent hypotension, and even reports of neurological toxicity such as seizures 21-22. CRS was observed in 48 of the 51 pat ients treated with CD19-modified CAR-T cells (94%) and serum ferritin levels were greater than 1000 mg / dl in all patients with severe CRS 4-5 C The relationship between the increase of CRP and the course of disease was similar to that of ferritin, but serum C reactive protein and ferritin level did not have significant effect on the prediction of CRS progression. Further, they used 10 healthy volunteers as baseline and found that severe CRS responses inside 1 month after CAR-T cell therapy were associated with 24 cytokines including IFN, IL-6, SGP-130, and SIL6R Serum levels of the peak correlation 23. Patients with severe CRS response to the survival of patients posed a great risk, patients with severe hypotension or shock, respiratory distress syndrome, neurotoxicity, liver and kidney dysfunction, it must actively deal with the situation. In addition to the use of vasoactive drugs, tracheotomy and enhanced ancillary therapy, the occupation of IL-6 receptor inhibitor tincture of monoclonal antibody is necessary by inhibiting IL-6 binding to cells and soluble IL-6 And block its classic and bypass IL-6 signal pathway, so after receiving the monoclonal antibody treatment, many patients quickly achieved a good clinical response 24. CRS can be divided into 5 levels, different levels of recommended CRS treatment is different, it is loosely recommended priority early adequate use of trastuzumab to prevent severe CRS response, but because IL-6 mAb is not easy through the blood-brain barrier, 3 to 4 neurotoxic patients, may be preferred to use glucocorticoids to prevent severe CRS. Therefore, IL-6 monoclonal antibody can be relatively early application, can be controlled for CRS and does not affect the efficacy of CAR-T5. Summary and outlookNowadays, the clinical application of CAR-T cell therapy, curiously the treatment of CD19 CAR-T in hematologic tumors, has made great achievements and the application potential of adoptive immunotherapy as the main represent ative of CAR-T cell immunotherapy Is very broad. Not only in the blood disease, but as well as in unanimous tumors and many benign or chronic diseases, it also has a gang of potential applications. With the development of gene recombination technology and antigen protein construction technology, more CAR-T has been applied to precise targeted therapy. In addition, epitopes expressed on the surface of different blood tumor cells, such as CD20, CD22, CD34, etc. may also be used as future treatment of other refractory blood diseases targeted to disease treatment to bring a new direction. One of the patients treated with CD19-modified CAR-T cells for MLL rearrangement of B-cell acute lymphoblastic leukemia showed that two patients developed AML after one month of treatment, which may be connect to the CD19-negative cellular repellent escape Of a mechanism-related 25. Therefore, the application of CAR-T in combination with multiple epitopes and the sustained killing effect of CAR-T cells in vivo may bring new hope to these cases. There have also been advances in the use of checkpoint inhibitors in combination with CAR-T in the treatment of animals such as AML 26. However, CAR-T therapy is still a significant clinical risk of adverse treatment, therefore, CAR-T therapy to avoid the safety and toxicity is also a clinical problem to be solved. At present, CAR-T cell therapy for specific antigenic epitopes is combined with nonspecific traditional therapy for tumor cells. It is also a safe and reasonable government for the treatment of these diseases, not only killing the tumor cells completely, reducing immune escape and ineffective CAR-T cell immunotherapy, in turn, reduces the dose of non-targeted therapies such as prior chemotherapy and the consequent toxic reactions. Therefore, in the process of discovering new target antigens and constructing precise immunotherapy, The combination of non-targeted drugs and hematopoietic stem cell transplantation is also the research direction of CAR-T cell therapy for a long time. Thus, CAR-T cell therapy has provided new hope for refractory hematologic malignancies, and although there is a pleasing therapeutic effect, more research and further clinical trials are needed, Multi-angle, combined with preceding and recent targeted therapy experience, will give CAR-T cell therapy to bring a broader application prospect and exciting clinical efficacy.References1 Deniger DC, Switzer K, Mi T, et al.Bispecific T-cells expressing polyclonal repertoire of endogenous gammadelta T-cell receptors and introduced CD19-specific anti receptorJ.Molecular therapythe journal of the AMerican society of gene therapy, 2013, 21(3)638-647.2 Jena B, Dotti G, make LJ.Redirecting T-cell specificity by introducing a tumor-specific chimeric antigen receptorJ.Blood, 2010, 116(7)1035-1044.3 Wang J, Jensen M, Lin Y, et al.Optimizing adoptive polyclonal T cell immunotherapy of lymphomas, using a chimeric T cell receptor possessing CD 28 and CD137 costimulatory domainsJ.Human gene therapy, 2007, 18(8)712-725.4 Jensen MC, Popplewell L, Cooper LJ, et al.Antitransgene rejection reponses contribute to weakened persistence of adoptively transferred CD20/CD19-specific chimeric antigen receptor redirected T cells in humansJ.Biology of blood and marrow transplantationjournal of the American society for blood and Marrow transplantation, 2010, 16(9)1245-1256.5 Kowolik CK, Topp MS, Gonzalez S, et al.CD28 Costimulation provided through a CD19-specific chimeric antigen receptor enhances in vivo persistence and antitumor efficacy of aoptively tyansferred T cellJ.Cancer research, 2006, 662210995-11004.6 Sanchez-paulete AR, Labiano S, Rodriguez-ruiz ME, et al.Deciphering CD137(4-1BB) signaling in T cell costimulation for translation into successful cancer immunotherapyJ.European journal of immunology, 2016, 46(3)513-522.7 Pule MA, Straathof KC, Dotti G, et al.A chimeric T cell antigen receptor that augments cytokine release and supports clonal expansion of Primary human T cellJ.Molecular therapythe journal of the American society of gene therapy, 2005, 12(5)933-941.8 Zhao Y, Wang QJ, Yang S, et al.A herceptin-based chimeric antigen rcetor with modified signaling domains leads to enhanced survival of transduced T lymphocytes and antitumor activityJ.Journal of immunology, 2009, 183(9)5563-5574.9 Pegram HJ, Lee JC, Hayman EG, et al.Tumor-targeted T cells modified to secrete IL-12 cradicate systemic tumors without need for prior conditioningJ.Blood, 2012, 119(18)4133-4141.10 Morgan RA, Yang JC, Kitano M, et al. 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