cells are then transplanted back into the person. Typically this process is done in conjunction with a conditioning regimen such as cyclophosphamide, which has been shown to potentiate the effects of infused T-cells. This effect has been attributed to making an immunologic space within which the cells populate. The process as a whole result in an effector cell, typically a T-cell, that can recognize a tumor cell antigen in a manner that is independent of the major histocompatibility complex and which can initiate a cytotoxic response. In 2017, tisagenlecleucel was approved by the FDA as a CAR-T therapy for people with acute B-cell lymphoblastic leukaemia who did not respond adequately to other treatments or have relapsed. In a 22-day process, the "drug" is customized for each person. T cells purified from each person are modified by a virus that inserts genes that encode a chimaeric antigen receptor into their DNA, one that recognizes leukemia cells. Relapsed ALL Typically, people who experience a relapse in their ALL after initial treatment have a poorer prognosis than those who remain in complete remission after induction therapy. It is unlikely that recurrent leukemia will respond favorably to the standard chemotherapy regimen that was initially implemented, and instead, these people should be trialed on reinduction chemotherapy followed by allogeneic bone marrow transplantation. These people in relapse may also receive blinatumomab, as it has shown to increase remission rates and overall survival rates, without increased toxic effects. Low dose palliative radiation may also help reduce the burden of tumor inside or outside the central nervous system and alleviate some symptoms. Recently, there has also been evidence and approval of use for dasatinib, a tyrosine kinase inhibitor. It has shown efficacy in cases of people with Ph1-positive and imatinib-resistant ALL, but more research needs to be done on long-term survival and time to relapse. Side effects Chemotherapies or stem cell transplantations may require a platelet transfusion to prevent bleeding. Moreover, patients undergoing a stem cell transplantation can develop a graft-versus-host disease (GvHD). It was evaluated whether mesenchymal stromal cells can be used to prevent a GvHD. The evidence is very uncertain about the therapeutic effect of mesenchymal stromal cells to treat graft-versus-host diseases after a stem cell transplantation on the all-cause mortality and complete disappear of chronic acute graft-versus-host diseases. Mesenchymal stromal cells may results in little to no difference in the all-cause mortality, relapse of malignant