[Efficacy and safety of TBI+rATG-based conditioning regimen for haploidentical allogeneic hematopoietic stem cell transplantation in 11 cases of chemotherapy-resistant advanced peripheral T-cell lymphoma].

Objective: To evaluate the clinical outcomes and safety of haploidentical hematopoietic stem cell transplantation (haplo-HSCT) using a conditioning regimen based on total body irradiation (TBI) and rabbit anti-human thymocyte globulin (rATG) in the management of chemotherapy-resistant advanced peripheral T-cell lymphoma (PTCL) . Methods: Clinical data of 11 patients with chemotherapy-resistant advanced PTCL who underwent haplo-HSCT with a TBI+rATG-based conditioning regimen at the Department of Hematology, Shanghai Liquan Hospital and Shanghai Zhaxin Integrated Traditional Chinese and Western Medicine Hospital, from September 2019 to December 2022 were retrospectively analyzed. Results: ①Among the 11 patients (six males and five females), with a median age of 40 years (range: 22-58 years), there were six cases of PTCL, not otherwise specified (PTCL-NOS), three cases of angioimmunoblastic T-cell lymphoma (AITL), one case of large-cell transformation of mycosis fungoides (MF-LCT), and one case of T-cell large granular lymphocytic leukemia (T-LGLL). According to the Lugano staging system, all patients were in stage Ⅲ or Ⅳ, and eight patients had B symptoms. Before transplantation, the median number of prior lines of chemotherapy was 4 (range: 2-10), and all patients had progressive disease (PD). The median time from diagnosis to transplantation was 17 months (range: 6-36 months). ②The conditioning regimen consisted of a TBI dose of 10 Gy, administered at 2 Gy on day -8 and 4 Gy from day -7 to day -6, rATG was administered at a daily dose of 2.5 mg/kg from day -5 to day -2. Etoposide (VP-16) was given at a dose of 15 mg/kg/d from day -5 to day -4, while cyclophosphamide (CTX) was administered at a dose of 50 mg/kg/d from day -3 to day -2. In patients with central nervous system involvement, etoposide and cyclophosphamide were replaced with thiotepa (TT) at a dose of 5 mg/kg/d from day -5 to day -4. Additionally, cytarabine (Ara-C) was added at a dose of 2.0 g/m(2) twice a day from day -3 to day -2 into the conditioning. ③Successful engraftment was achieved in all patients, with a median time to neutrophil engraftment of 14.5 d (range: 11-16 d) and a median time to platelet engraftment of 13 days (range: 8-18 days). Acute graft-versus-host disease (aGVHD) occurred in one patient (grade Ⅰ-Ⅱ), and another patient experienced grade Ⅲ-Ⅳ aGVHD. Among the eight survivors, four developed chronic GVHD (cGVHD). ④Post-transplantation, nine patients achieved complete response (CR). ⑤Hematopoietic suppression occurred in all patients after conditioning, with three experiencing diarrhea, four developing mucositis, three exhibiting elevated transaminase/bilirubin levels, and seven developing infectious complications. These non-hematologic adverse events were effectively managed. ⑥At one year post-transplantation, the non-relapse mortality (NRM) was (22.5±14.0) %, the cumulative incidence of relapse (CIR) was (20.2±12.7) %, and overall survival (OS) rate was (72.7±13.4) %, and disease-free survival (DFS) rate was (63.6±14.5) % . Conclusion: TBI+rATG-based conditioning regimen for haplo-HSCT is an effective and safe treatment approach for patients with chemotherapy-resistant advanced PTCL.