Efficacy of ex vivo Purging with CD34+ Selection to Maximize the Effects of Autologous Stem Cell Transplantation in Peripheral T-cell Lymphoma Patients

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 is the most reliable method to reduce autograft tumor cell contamination in these tumors. Methods: We retrospectively investigated the influence of ex vivopurging 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. Conclusions: There were no engraftment failures or differences in adverse events between the two groups. CD34+ ex vivo purging ASCT is safe, effective, and may improve survival outcomes, particularly in high-risk PTCL patients.