The Impact of Graft CD3 Cell/Regulatory T Cell Ratio on Acute Graft-versus-Host Disease and Post-Transplantation Outcome: A Prospective Multicenter Study of Patients with Acute Leukemia Undergoing Allogeneic Peripheral Blood Stem Cell Transplantation.

Abstract

Although it is well known that tumor site- or bone marrow-infiltrating regulatory T cells (Tregs) might be correlated with worse outcomes in solid tumors and acute leukemias by promoting immune surveillance escape, their contribution to the immediate post-allogeneic transplantation phase by peripheral blood (PB) allografts remains unclear. Moreover, the Treg content in stem cells harvested from PB has been suggested to be correlated with acute graft versus-host-disease (aGVHD) and immunologic recovery after allogeneic PB stem cell transplantation (allo-PBSCT). This study aimed to investigate the impact of the graft content of Tregs, as graft CD3+/Tregs ratio (gCD3/TregsR), on acute GVHD and post-allo-PBSCT outcomes. We prospectively enrolled 94 consecutive patients at 9 Italian centers of the Gruppo Italiano Trapianto di Midollo Osseo (GITMO) with acute myelogenous (n = 71; 75%) or lymphoblastic (n = 23; 25%) leukemia in complete remission who underwent matched related donor (n = 35; 37%) or unrelated donor (n = 59; 63%) allo-PBSCT. The median graft CD3+ cell, Treg, and gCD3/TregsR values were 196 × 106/kg body weight (range, 17 to 666 × 106/kg), 3 × 106/kg (range, 0.1 to 35 × 106/kg), and 71 (range, 1 to 1883), respectively. The discriminatory power of the gCD3/TregsR value to predict grade ≥II aGVHD was assessed by estimating the area under the receiver operating characteristic (ROC) curve (AUC). Any grade and grade ≥II aGVHD occurred in 24 (26%) and 17 (18%) allo-PBSCT recipients, respectively. By ROC analysis, AUC (0.74; 95% confidence interval [CI], 0.608 to 0.866; P = .002) identified 70 as the optimal gCD3/TregsR cutoff value predicting the appearance of grade ≥II aGVHD with 76% sensitivity and 71% specificity. Patients were subdivided into a high (ROC curve value ≥70) gCD3/TregsR group (HR; n = 48) and a low (ROC curve value <70) gCD3/TregsR group (LR; n = 46). The incidence of grade II-IV aGVHD was lower in the LR group compared with the HR group (9% [4 of 46] versus 27% [13 of 48]) in both univariate analysis (odds ratio [OR], 4.8; 95% CI, 1.44 to 16.17; P = .015) and multivariate analysis (OR, 5.0; 95% CI, 1.34 to 18.93; P = .017), whereas no differences were documented taking into account aGVHD of any grade. The overall survival, disease-free survival, nonrelapse mortality, and relapse rates at 2 and 3 years were 61% and 54%, 62% and 55%, 15% and 23%, and 27% and 30%, respectively. Of note, gCD3/TregsR did not significantly correlate with relapse (P = .135). Taken together, our data from this prospective multicenter study confirm the value of Tregs in preventing aGVHD while maintaining the graft-versus-leukemia effect. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

• Authors: Mario Delia, Paola Carluccio, Anna Mestice, Patrizia Chiusolo, Elisabetta Metafuni, Silvia Bellesi, Mario Arpinati, Giulio Antonio Milone, Massimo Martino, Patrizio Mazza, Claudia Ingrosso, Adriana Vacca, Giorgia Saporiti, Francesco Zallio, Immacolata Attolico, Domenico Pastore, Giorgina Specchia, Francesco Albano, Pellegrino Musto
• Journal: Transplantation and cellular therapy (Transplant Cell Ther) Vol. 27 Issue 11 Pg. 918.e1-918.e9 (11 2021) ISSN: 2666-6367 [Electronic] United States
• PMID: 34403789 (Publication Type: Journal Article, Multicenter Study, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2021 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Topics

• Graft vs Host Disease
• Hematopoietic Stem Cell Transplantation
• Humans
• Leukemia, Myeloid, Acute (therapy)
• Peripheral Blood Stem Cell Transplantation
• Prospective Studies
• T-Lymphocytes, Regulatory