Influence of Conditioning Regimens with Total Body Irradiation (TBI) on Graft Versus Host Disease and Graft Versus Leukemia Effect Following Donor Lymphocyte Infusions (DLI)

Abstract

Introduction In this study, our aim is to analyse the effect of conditioned with TBI on the outcome of DLI after allo-HSCT. Patients and Methods This retrospective study cohort included 152 patients treated with a total of 250 DLI for relapsed hematological malignancies after allo-HSCT from March 1991 through July 2018. Patients received myeloablative- (MA) (n=97 (63.8%)) or reduced-intensity (RI) (n=55 (36.2%)) conditioning regimens. TBI was administered at a total dose of 4 Gy/day for 3 days in MA regimens or 2 Gy/day for 1 day in RIC regimens. Results Thirty nine (25.7%) of 152 patients received TBI in conditioning regimen (Table 1). Median number of DLI was 1 (range, 1-5) in both groups. Seventy eight (20 (55.6%) and 58 (53.2%) in TBI and non-TBI group; p>0.1) patients developed acute grade II to IV GVHD. Chronic GVHD was occurred in 22 (51.2%; extensive in 4) and 52 (46%; extensive in 6) patients in TBI and non-TBI group (p=0.07). We could not demonstrate the lower doses of TBI associated with an increased risk of GVHD in TBI groups. Among all patients, 49 (32.2%) and 16 (10.5%) had relapse and/or progressive disease after DLI in non-TBI and TBI groups, respectively (p>0.1). The primary cause of death was relapse in both groups, whereas 5 (23.8%) and 11 (12.8%) patients died of TRM in TBI and non-TBI groups (p>0.1). The OS at 1 and 3 years were slightly higher in non-TBI group (Figure 1a). When analyzed according to the TBI doses, median OS is similar between two groups (Figure 1b). Discussion Irradiation is known to inhibit lymphocyte activity and consequently to reduce the incidence of GVHD in experimental models for allo-HSCT. In our study, acute and chronic GVHD incidence was similar in both groups but lower survival rate was seen in TBI group (p>0.1). Larger and prospective studies are warranted.