CD7 CAR-T Cell as Bridging Therapy for Successful Allogeneic Hematopoietic Stem Cell Transplantation in Relapsed/Refractory T Lymphoblastic Leukemia/ Lymphoma: A Case Report and Literature Review.

BACKGROUND Relapsed/refractory T-cell acute lymphoblastic leukemia/lymphoma (R/R T-ALL/LBL) carries an exceptionally poor prognosis. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) after achieving minimal residual disease (MRD)-negative complete remission (CR) offers the only possibility of long-term remission. However, conventional salvage chemotherapy rarely achieves MRD negativity. Thus, novel bridging strategies to eliminate MRD and enable transplant are urgently needed. CASE REPORT We report the case of a 51-year-old man with T-ALL/LBL who remained MRD-positive despite multiple lines of salvage therapy. As a bridge to transplant, he received donor-derived CD7 chimeric antigen receptor T cells (CAR-T) from his 9/10 HLA-matched son after lymphodepletion. Grade 3 cytokine release syndrome occurred on day 3 and resolved with management; no neurotoxicity was observed. Bone marrow evaluation on day 15 confirmed morphological complete remission and MRD negativity, which proved sustained. The patient then underwent myeloablative haploidentical HSCT from the same donor. Neutrophil engraftment occurred on day +14 and platelet engraftment on day +45. No acute or chronic graft-versus-host disease developed. Serial monitoring through day +150 demonstrated sustained MRD-negative remission and donor chimerism. CONCLUSIONS Sequential CD7 CAR-T therapy followed by consolidative allo-HSCT is a promising curative approach for high-risk R/R T-ALL/LBL patients, enabling MRD clearance not achievable with chemotherapy alone. This case highlights the feasibility and efficacy of donor-derived CD7 CAR-T as a bridge to transplant, with manageable toxicity. Prospective studies with larger cohorts are needed to further validate this strategy and optimize timing and conditioning.