Outcomes of Antithymocyte Globulin-Post-Transplantation Cyclophosphamide-Cyclosporine-Based versus Antithymocyte Globulin-Based Prophylaxis for 10/10 HLA-Matched Unrelated Donor Allogeneic Hematopoietic Cell Transplantation.

In 2015, dual T cell depletion with antithymocyte globulin (ATG) and post-transplantation cyclophosphamide (PTCy) combined with cyclosporine A (CsA) replaced our prior institutional graft-versus-host disease (GVHD) prophylaxis regimen of 4.5 mg/kg ATG, CsA, and mycophenolate mofetil (MMF) (ATG-based) in 10/10 HLA-matched unrelated donor (MUD) peripheral blood allogeneic hematopoietic stem cell transplantation (allo-HCT). The initial ATG dose of 4.5 mg/kg [ATG(4.5)/PTCy] was reduced to 2 mg/kg [ATG(2)/PTCy] in 2018. This study compares the results obtained from 444 adults undergoing MUD allo-HCT at our institution who received ATG(4.5)/PTCy (n = 127) or ATG(2)/PTCy (n = 223) with those who received ATG-based prophylaxis without PTCy (n = 84). The rates of grade II-IV and grade III-IV acute GVHD (aGVHD) at day +100 and moderate/severe chronic GVHD (cGVHD) at 1 year were 35.7%, 21.6%, and 14.7%, respectively, in patients receiving ATG-based prophylaxis without PTCy; 16.5%, 4.9%, and 4.3% in patients receiving ATG(4.5)/PTCy; and 23.3% (P = .004), 8.0% (P < .001), and 14.1% (P =.006) in patients receiving ATG(2)/PTCy. One-year overall survival (OS), nonrelapse mortality (NRM), and GVHD-free relapse-free survival (GRFS) were 69.8%, 25.3%, and 52.0%, respectively, for patients receiving ATG-based prophylaxis without PTCy; 82.7%, 17.3%, and 59.8% for patients receiving ATG(4.5)/PTCy; and 78.3% (P = .446), 14.7% (P = 101), and 56.2% (P = .448) for patients receiving ATG(2)/PTCy. On univariate analyses, the use of ATG(2)/PTCy was associated with a lower risk of NRM (hazard ratio, .54; P = .023) compared with the use of ATG-based prophylaxis without PTCy. ATG(2)/PTCy prophylaxis effectively prevents GVHD and is associated with comparable relapse risk, OS, and GRFS as seen with ATG(4.5)/PTCy and ATG-based prophylaxis without PTCy.

Dual T-cell depletion with ATG and PTCy for peripheral blood reduced intensity conditioning allo-HSCT results in very low rates of GVHD.

The efficacy of posttransplant cyclophosphamide (PTCy) and antithymocyte globulin (ATG) in controlling GVHD has been previously reported. We aim to study the safety and efficacy of the use of dual T-cell depletion with ATG and PTCy for peripheral blood reduced intensity conditioning regimen allo-HSCT in 270 patients with hematological malignancies. Median follow-up was 12.7 months. Nineteen percent of patients received grafts from a matched related donor, 46% from 10/10 matched unrelated donors (MUD), 16% from 9/10 MUD and 19% from haploidentical donors. Graft failure rate was 9%. CMV and EBV reactivation rates were 58 and 64%. The cumulative incidence of grade II-IV and III-IV acute GVHD at day + 100 was 20.1% and 4.6%, respectively. The CI of moderate/severe chronic GVHD at 1 year was 12.4%. There were no differences in the incidence of GVHD according to donor type. One-year OS, RFS, NRM, CIR, and GVHD-free/RFS respectively were 65.2%, 56.9%, 22.7%, 20.3%, and 47.6%. Higher disease-risk index and worse Karnofsky performance status were significant factors for poor outcomes. In conclusion, the use of T-cell dual depletion with ATG and PTCy results in very low rates of acute and chronic GVHD and acceptable relapse rates and NRM.

Impact of CD34+ cell dose on reduced intensity conditioning regimen haploidentical hematopoietic stem cell transplantation.

OBJECTIVES: Haploidentical hematopoietic stem cell transplant (haplo-SCT) has been associated with higher rates of graft rejection, and a higher dose of CD34+ cell dose is frequently requested. We aim to explore the impact of CD34+ cell dose in peripheral blood stem cell (PBSC) grafts using reduced intensity conditioning (RIC) in haplo-SCT. METHODS: Sixty-eight consecutive haplo-SCT in adult patients were included. Graft-vs-host disease (GVHD) prophylaxis consisted on ATG, PTCy, and CsA. The cohort was divided in two groups using CD34+ dose of ≥ 9 × 106 CD34+/Kg as cutoff point. Median follow-up was 8.9 months. RESULTS: Median cell dose infused was 9.32 × 106 CD34+/Kg. Forty (58.8%) recipients received grafts with CD34+ cells ≥9 × 106 /kg. The infusion ≥ 9 × 106 CD34+/Kg cell dose had a negative impact in overall survival (P = .03) after adjusting for age at transplant. The cumulative incidence of acute GVHD and graft failure were not significantly influenced per CD34+ cell dose. Only four recipients had grade III aGVHD, and all of them received grafts with a CD34+ cell dose ≥ 9 × 106 . CONCLUSION: In RIC haplo-SCT, recipients may not benefit from PBSC grafts with a CD34+/kg cell dose higher than 9 × 106 cells/kg, as it can have an adverse impact in post-transplant outcome.