CAR-T after Stem Cell Transplantation in B-Cell Lymphoproliferative Disorders: Are They Really Autologous or Allogenic Cell Therapies?

SIMPLE SUMMARY: B-cell malignancies, like leukemias and lymphomas, are neoplasms that emerge from the malignant proliferation of B cells. Hematopoietic stem cell transplant (HSCT) is an effective medical treatment for these malignancies, but unfortunately, relapse of the disease after HSCT remains a challenge and is associated with poor long-term survival. A cell-based immunotherapy, the chimeric antigen receptor (CAR) T-cells, has proven to improve the clinical outcome of relapsed/refractory HSCT B-cell lymphoproliferative disorders patients in clinical trials. Even though results are promising, in this review, we discuss about the importance to determine T cell chimerism in HSCT patients, the origin of the manufactured CAR T-cells (autologous vs. allogenic) and the future perspective of the CAR-T cells in transplanted patients. ABSTRACT: Allogenic hematopoietic stem cell transplantation (allo-HSCT) is one of the standard treatments for B-cell lymphoproliferative disorders; however, deep relapses are common after an allo-HSCT, and it is associated with poor prognosis. A successful approach to overcome these relapses is to exploit the body’s own immune system with chimeric antigen receptor (CAR) T-cells. These two approaches are potentially combinatorial for treating R/R B-cell lymphoproliferative disorders. Several clinical trials have described different scenarios in which allo-HSCT and CAR-T are successively combined. Further, for all transplanted patients, assessment of chimerism is important to evaluate the engraftment success. Nonetheless, for those patients who previously received an allo-HSCT there is no monitorization of chimerism before manufacturing CAR T-cells. In this review, we focus on allo-HSCT and CAR-T treatments and the different sources of T-cells for manufacturing CAR T-cells.