CLINICAL EFFICACY OF CD34 POSITIVE SELECTION EX‐VIVO PURGING DURING AUTOLOGOUS STEM CELL TRANSPLANTATION IN PERIPHERAL T CELL LYMPHOMA

Abstract

Background: Autologous stem cell transplantation (ASCT) is the standard treatment for peripheral T-cell lymphomas (PTCLs). Strategies that reduce the relapse rate and treatment-related mortality are essential for successful ASCT. Because in vivo/in vitro purging methods using rituximab are not appropriate for T-cell lymphomas, an ex vivo CD34+ selective purging system using CliniMACS is the most reliable method to reduce autograft tumor cell contamination in these tumors. In the present study, we retrospectively analyzed the clinical outcomes of HDT/ASCT after ex vivo purging via the CD34+ selective method in T-cell NHL patients. Methods: We retrospectively investigated the influence of ex vivo purging with CD34+ selection to maximize the effects of ASCT. Of 67 consecutive PTCL patients, 32 and 35 underwent purged and unpurged ASCT. Results: The purged group had improved overall survival (OS), disease-free survival (DFS), and cumulative incidence of relapse (hazard ratio [HR] = 2.68, p = 0.016; HR = 3.97, p = 0.002; and HR = 3.65, p = 0.004, respectively), compared to the unpurged group. Prognostic factor analysis showed that unpurged ASCT, chromosomal abnormalities at initial diagnosis, high risk, and pre-ASCT disease status were associated with poor survival outcomes. Subgroup analysis demonstrated that purging was most appropriate for International Prognostic Index high-risk patients who underwent upfront ASCT (HR = 3.35 [OS] and = 6.59 [DFS]). In purged ASCT group, NK cell activity and the lymphocyte-to-monocyte ratio known as an independent prognostic factor were increased after ASCT with statistical significance; the lymphocyte-to-monocyte ratio (LMR) was significantly increased after ASCT in the purged group (mean difference = 1.484, 95% CI = 0.407–2.560; p = 0.009). Also, Engraftment was achieved in all patients with no need for unpurged autologous stem cell backup in purged group. There were no engraftment failures or differences in adverse events including of transplant-related viral infections between the two groups. The research was funded by: The research was funded by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (NRF-2020R1G1A1099654). Keywords: Aggressive T-cell non-Hodgkin lymphoma, Stem Cell Transplant No conflicts of interests pertinent to the abstract.