THE PRIMARY RESULTS OF THE EFFICACY OF UPFRONT HIGH‐DOSE CHEMOTHERAPY WITH AUTOLOGOUS STEM CELL TRANSPLANTATION FOR IV STAGE AND HIGH‐INTERMEDIATE/HIGH IPI RISK GROUPS DLBCL

Abstract

Introduction: Approximately 30% of patients(pts) with IPI ≥2 diffuse large B-cell lymphoma (DLBCL) have relapsed after the frontline regimens. High-dose chemotherapy (HDCT) with autologous hematopoietic stem cell transplantation (auto-HSCT) in the first remission can be an effective option to decrease the relapse rate in these patients. Methods: 108 pts, which fit the following criteria: DLBCL NOS, age 18-65, stage IV, IPI ≥2, treated by x6 CHOP/EPOCH/H-CVAD + R in frontline from 01.01.2010 to 31.12.2019 at NMRC of Oncology named after N.N.Petrov of MoH of Russia were retrospectively analyzed. If patients achieved a complete response (CR) or partial response (PR) after frontline, they enrolled into upfront HDCT with auto-HSCT group (Group 1, n = 38) or follow-up group (Group 2, n = 70) based on multidisciplinary team (MDT) decision. More than one extranodal involvement (extra) had 78.9% (30/38) pts in Group 1 and 75.7% (53/70) pts in Group 2. MYC and BCL-2 coexpression were analyzed in 84% (32/38) pts samples in Group 1 and 65.7% (46/70) in Group 2 and were present (DEL) in 46.8% (15/32) pts samples in Group 1 and 28.2% (13/46) in Group 2. A Fisher's exact test (Fisher's) with a two-tailed p-value was used to determine the difference in relapse rate between Group 1 and Group 2. A McNemar test (McNemar) with Yates correction (Yates) was used to determine the difference in responses in Group 1 after upfront HDCT with auto-HSCT. Results: CR after induction was achieved in 61% (23/38) pts in Group 1. After HDCT with auto-HSCT, the CR rate increased to 97% (37/38) and continues for a median of 30 (7-56) months in 87% (33/38) pts. It demonstrates the statistically significant difference – McNemar = 11.27 (p ≤ 0.001) and with Yates = 10.42 (p = 0.002). Early relapses (ER) were diagnosed in 6% (2/38) pts, late relapses (LR) in 6% (2/38) pts. HDCT associated mortality (infection) has occurred in 3% (1/38) pts. Group 2 pts achieved CR in 81% (57/70) cases. CR continues for median 38 (8-73) months in 67% (47/70) pts. Group 2 pts have 14% (14/70) ER and 6% (4/70) LR. No treatment-related deaths occurred. ER rate was higher in Group 2 (p = 0.048). In Group 2 pts with ˃1 extra experienced more ER (Group 1 – 3.3% (1/30), Group 2 – 20.8% (11/53), p = 0.048). DEL was significant in terms of both ER (Group 1 – 6.6% (1/15), Group 2 – 38.4% (6/13), p = 0.029) and all relapses (AR) (Group 1 – 6.6% (1/15), Group 2 – 53.8% (7/13), p = 0.011). The ER rate in Group 2 was significantly higher if the combination of ˃1 extra and DEL were present (Group 1 – 9.1% (1/11), Group 2 – 60% (6/10), p = 0.0237). Conclusions: 1. CR rate significantly increased in DLBCL NOS pts with stage IV, IPI ≥2 treated by upfront HDCT with auto-HSCT. 2. ER rate significantly decreases in DLBCL NOS with stage IV, IPI ≥2 after upfront HDCT with auto-HSCT pts if ˃1 extranodal site, DEL, and combination of these factors are present; AR rate decreases if pts only have DEL. EA – previously submitted to EHA 2021. Keywords: Aggressive B-cell non-Hodgkin lymphoma, Stem Cell Transplant No conflicts of interests pertinent to the abstract.