Survival Outcome of Autologous or Allogeneic Stem Cell Transplantation in 49 Patients with Extranodal NK/T-Cell Lymphoma
Authors: Jin Mao , Ai Sicheng , You Tao , Ma Xiao , Chen Feng , Li Caixia , Jin Zhengming , Wu Depei , Huang Haiwen 
Published: December 2023

Objective:Extranodal NK/T-cell lymphoma (ENKTL) is an uncommon tumor featured by high invasiveness, the ease of developing drug resistance, low curative rate, and short survival time. Hematopoietic stem cell transplantation (HSCT) is now recommended for patients with advanced or relapsed/refractory (r/r) ENKTL, but which HSCT is the most suitable remains to be conclusively determined. Here, we performed a retrospective single-center study to compare the prognostic role of autologous and allogeneic HSCT after induction chemotherapy in ENKTL patients.

Methods: Clinical data on 49 ENKTL patients who underwent HSCT in the First Affiliated Hospital of Soochow University from 8/2007 to 9/2022 was reviewed. We divided all patients into two subgroups: cohort A) auto-HSCT and cohort B) allo-HSCT. Observation period started from the day of stem cell infusion in both cohorts. The primary endpoint was overall survival (OS). The secondary endpoints were progression-free survival (PFS) and non-relapse mortality (NRM). NRM was defined as death from any cause related to transplantation without evidence of lymphoma progression.

Results: Of 49 patients included, 28 (57%) patients received auto-HSCT (cohort A), while 21 (43%) patients received allo-HSCT (cohort B). The two cohorts of patients were different in some terms of baseline characteristics (Figure A). A total of 8 patients with stageⅡdisease received transplantation due to r/r status or primary lesions beyond the nasal area. The patients in cohort B were younger at the time of transplant (median age: 33 years vs. 37 years, p=0.0031) and had a higher proportion of bone marrow involvement (7% vs. 43%, p=0.005). After a median follow-up of 35 months, patients who received allo-HSCT had a worse prognosis compared to patients who underwent auto-HSCT (2-year OS:61% vs 96%, p=0.0015). There was no transplantation-related mortality in the auto-HSCT group, while the NRM was 33.3% in the allo-HSCT group. Limiting the analysis to only patients with complete remission (CR) (allo-HSCT=13, auto-HSCT=25) before HSCT, no differences in 2-year OS and PFS were reported despite 61% vs 4% bone marrow involvement, respectively (76% vs 96% OS and 76.9% vs 84.1% PFS at +24 months, p&gt;0.05). In the allo-HSCT group, patients who achieved first CR(CR1) before HSCT showed higher OS and lower NRM rates compared to those without CR1, with 2-year OS of 88.9% and NRM of 11.1% (p=0.028, p=0.06, respectively). In terms of donor sources, no significant difference in PFS and OS was observed in patients who received haploid conjugate (n = 14) vs. HLA-matched related and unrelated donors(p&gt;0.05).

Conclusions: Overall, consolidation therapy with HSCT improved OS in patients with advanced or relapsed/refractory ENKTL who achieved CR after induction therapy. Given the high NRM in the allo-HSCT, auto-HSCT is probably the preferred clinical option in most patients and allo-HSCT may be more appropriate for younger patients with bone marrow involvement and CR1 acquired before transplantation. Larger studies are needed to validate our results.