Study of Autologous Versus Allogeneic Stem Cell Transplantation in 56 Patients with Advanced High-Risk Extranodal NK/T-Cell Lymphoma

Introduction: Extranodal NK/T-cell lymphoma (ENKTL) is a rare and highly aggressive form of non-Hodgkin lymphoma (NHL) characterized by a propensity for drug resistance and poor prognosis. For patients with advanced high-risk disease, guidelines recommend stem cell transplantation as consolidation therapy following first-line induction treatment, but do not specify whether autologous or allogeneic transplantation should be performed. Previous studies have not comprehensively included ENKTL patients undergoing both autologous hematopoietic stem cell transplantation (auto-HSCT) and allogeneic hematopoietic stem cell transplantation (allo-HSCT) and have also rarely compared the differences in efficacy between these two types of transplantation, leaving the choice of transplant type inconclusive. We conducted a retrospective study to evaluate the survival outcomes of ENKTL patients who underwent either auto-HSCT or allo-HSCT. Clinical data were collected from ENKTL patients who underwent HSCT in our center between January 2011 and March 2023. A total of 56 ENKTL patients were enrolled, with 34 (60.7%) receiving autologous HSCT and 22 (39.2%) receiving allogeneic HSCT. The primary endpoints were overall survival (OS) and progression-free survival (PFS), while secondary endpoints included cumulative incidence of relapse (CIR) and non-relapse mortality (NRM). Results: The study included 56 ENKTL patients. Of these, 34 (60.7%) underwent autologous HSCT, and 22 (39.2%) underwent allogeneic HSCT, with 4, 3, and 15 patients receiving sibling, unrelated donor, and haploidentical transplants, respectively. The allo-HSCT patients demonstrated a higher percentage of disease progression (95% vs. 62%, P=0.004), bone marrow invasion (40.9% vs. 5.9%, P=0.002), and pre-transplantation non-complete remission (CR) status (45.4% vs. 11.8%, P=0.009), with no significant differences in other clinical characteristics between the groups. Non-relapse mortality（NRM）was higher in the allo-HSCT group (31.8% vs. 0%, P<0.001), and the 3-year CIR was 27.4% for auto-HSCT and 9% for allo-HSCT (P=0.0499). There was a statistically significant difference in OS (3-year OS: 92% for auto-HSCT and 59% for allo-HSCT, P=0.002) but not in PFS (3-year PFS: 73% for auto-HSCT and 59% for allo-HSCT, P=0.29) between the auto-HSCT and allo-HSCT groups. There was a significant difference in OS and PFS between patients with CR and non-CR pre-transplantation disease status, with 3-year OS of 89% for CR and 50% for non-CR, and 3-year PFS of 76% for CR and 43% for non-CR (P<0.001 and P=0.009, respectively). Among advanced patients in CR post-transplantation, there were 18 in the auto-HSCT group and 12 in the allo-HSCT group. There was no significant difference in NRM between auto-HSCT and allo-HSCT (P=0.078), with 1-year NRM of 0% and 16.7%, respectively. The 3-year CIR was significantly different between the two groups (P=0.042), with rates of 26.7% for auto-HSCT and 0% for allo-HSCT. However, OS and PFS were not statistically different between the two groups (P=0.53), with 3-year OS of 85.9% for auto-HSCT and 83.3% for allo-HSCT, and 3-year PFS of 73.3% for auto-HSCT and 83.3% for allo-HSCT. Conclusion: Pre-transplant lymphoma control is a critical determinant of transplantation outcomes, and achieving CR is an independent beneficial factor for survival. For advanced ENKTL patients achieving CR after chemotherapy, both auto-HSCT and allo-HSCT are effective in improving OS and PFS. Taking into account the costs, adverse effects, and the quality of life post-transplant, autologous transplantation may be a suitable option for patients who have achieved complete remission. Given the limited number of cases, these results await further confirmation with a larger sample.