Effect of methotrexate dose in graft-versus-host disease prophylaxis after single-unit cord blood transplantation in adult acute myeloid leukemia

Effect of Conditioning Regimens and Graft-versus-Host Disease Prophylaxis on the Outcomes of Umbilical Cord Blood Transplantation Performed with Cyclophosphamide/Total Body Irradiation-Based Regimens

Umbilical cord blood (UCB) is a valuable alternative donor source for allogeneic hematopoietic stem cell transplantation. Various conditioning regimens and graft-versus-host disease (GVHD) prophylaxis regimens aimed at improving the outcomes of umbilical cord blood transplantation (UCBT) have been explored; however, the differences in their effects remain unclear. This study was conducted to elucidate the differences in the effects of conditioning and GVHD prophylaxis regimens on UCBT outcomes by disease type in a nationwide, retrospective study. We retrospectively analyzed the effects of conditioning and GVHD prophylaxis regimens on the outcomes of UCBT performed with cyclophosphamide (Cy)/total body irradiation (TBI)-based regimens in patients with acute myeloid leukemia (AML; n = 1126), acute lymphoblastic leukemia (ALL; n = 620), myelodysplastic syndrome (MDS; n = 170), and lymphoma (n = 128). Multivariate analysis for overall survival (OS) demonstrated the benefit of adding high-dose cytarabine to the Cy/TBI regimen for the AML group (relative risk [RR], .76; P = .003) and lymphoma group (RR, .54; P = .02), but not for the ALL and MDS groups. In the ALL group, adding etoposide to the Cy/TBI regimen was associated with a lower OS (RR, 1.45; P = .03). For GVHD prophylaxis, a tacrolimus/methotrexate regimen was associated with a lower OS compared with a cyclosporine/methotrexate regimen in the AML group (RR, 1.26; P = .01); this difference was not observed in the other groups. These differences in OS according to the conditioning and GVHD prophylaxis regimen were attributable mainly to differences in relapse risk. Our data show that the effects of conditioning regimens and GVHD prophylaxis on UCBT outcomes differed according to disease type. UCBT outcomes could be improved by selecting optimal conditioning regimens and GVHD prophylaxis for each disease type.

Significance of Omitting Day 11 Mini-Dose Methotrexate for GVHD Prophylaxis After Unrelated Bone Marrow Transplantation

The combination of calcineurin inhibitors and short-term methotrexate has been used as a standard graft-versus-host-disease (GVHD) prophylaxis in allogeneic hematopoietic stem cell transplantation. Mini-dose methotrexate (mini-MTX), consisting of 5 mg/m²/d on days 1, 3, 6, and 11, is occasionally selected as an alternative considering toxicity. The significance of day 11 administration remains unclear. We performed a retrospective study of 135 cases of unrelated bone marrow transplantation at our institute between 2006 and 2019 and compared the outcomes between day 11 MTX dose omitted (n = 72) and full-doses of mini-MTX (n = 63). In total cohort, the 4-year overall survival (OS) was 58.7 %, and the omitted group showed poor GVHD/relapse-free-survival (P = .01) with comparable OS (P = .11) and relapse-free survival (P = .11). Human leukocyte antigen (HLA) mismatch is a major risk factor for severe GVHD. We analyzed the impact of omitting day 11 MTX in 2 cohorts from HLA matched or mismatched donors. In both cohorts, the omitted group had a higher risk of severe acute and chronic GVHD. In conclusion, the omission of day 11 MTX was associated with a higher risk of severe GVHD. Therefore the omission of the day 11 dose is not recommended.

Improved outcomes of single-unit cord blood transplantation for acute myeloid leukemia by killer immunoglobulin-like receptor 2DL1-ligand mismatch

The impact of the killer immunoglobulin-like receptor (KIR)-ligand mismatch between donor and recipient in hematopoietic stem cell transplantation is controversial. Recently, it has been suggested that their effect on cord blood transplantation (CBT) differs among types of mismatched KIR-ligand and graft-versus-host disease (GVHD) prophylaxis. To investigate their role in acute myeloid leukemia (AML), mismatch of KIR2DL1, KIR3DL1, and KIR3DL2-ligand (HLA-C2, Bw4, and A3/11) were retrospectively assessed in patients undergoing CBT with GVHD prophylaxis comprising a calcineurin inhibitor plus methotrexate (CNI/MTX) or mycophenolate mofetil (CNI/MMF). In patients who received CNI/MTX, a favorable effect of KIR-ligand mismatch on relapse was noted in HLA-C2 mismatched cases (24.8% at 3 years post-CBT [no HLA-C2 mismatch, n = 1602] vs. 15.4% [HLA-C2 mismatch, n = 161], P = 0.0116). In this group, overall survival (OS) was also superior (68.2%, P = 0.0083) compared to the other group (55.0%). Multivariate analysis results supported these findings (hazard ratio [HR] 0.61 for relapse, P = 0.017 and HR 0.72 for OS, P = 0.016). However, the KIR-ligand mismatch effect was not observed in patients with KIR-ligand mismatch types other than HLA-C2 and those using CNI/MMF for GVHD prophylaxis. These results suggest that HLA-C2 mismatch in CBT using CNI/MTX as GVHD prophylaxis may improve the outcomes of patients with AML.

Omission of day +11 methotrexate dose and allogeneic hematopoietic cell transplantation outcomes: results of a systematic review/meta-analysis

Allogeneic hematopoietic cell transplantation (allo-HCT) is potentially curative for patients with malignant and benign hematologic conditions. Graft-versus-host disease (GVHD) is a known complication of allo-HCT that results in significant morbidity and mortality. A common GVHD prophylaxis strategy combines a calcineurin inhibitor with methotrexate. When mucositis and organ toxicity develop, the day +11 dose is frequently omitted to limit further organ damage. The potential impact of this practice on allo-HCT outcomes is unclear as published data show conflicting results. Thus, we performed a systematic review/meta-analysis of the available literature to assess the impact of omitting day +11 methotrexate on allo-HCT recipients. Data were extracted in relation to benefits (overall survival [OS], progression-free survival [PFS]) and harms (acute and chronic GVHD, non-relapse mortality [NRM], and relapse). Pooled OS rate favored those who received day +11 methotrexate vs. those who did not (HR = 1.21; 95% CI = 1.02-1.43; p = 0.03). There was no significant difference in pooled rates of PFS (HR = 0.96; 95% CI = 0.60-1.52; p = 0.85), acute GVHD (HR = 1.03; 95% CI = 0.35-2.98; p = 0.96), chronic GVHD (HR = 0.83; 95% CI = 0.44-1.57; p = 0.57), NRM (HR = 0.86; 95% CI = 0.67-1.11; p = 0.25), and relapse (HR = 0.97; 95% CI = 0.75-1.26; p = 0.83) between the two groups. Large prospective multicenter studies are needed to better define the significance of day +11 methotrexate omission.

Prognostic impact of the dosage of methotrexate combined with tacrolimus for graft-versus-host disease prophylaxis after cord blood transplantation

The optimal dosage of methotrexate (MTX) for graft-versus-host disease (GVHD) prophylaxis after cord blood transplantation (CBT) has not been well elucidated. Therefore, we conducted a retrospective study comparing a mini-MTX group (5 mg/m² on day 1, 3 and 6) to a short-MTX group (10 mg/m² on day 1 and 7 mg/m² on day 3 and 6) after CBT. Sixty-three patients were classified as the mini-MTX group and 20 as the short-MTX group. The median time and cumulative incidence of neutrophil engraftment did not vary between the two groups. The cumulative incidence of grade 2-4 and grade 3-4 acute GVHD was similar in both groups. Overall survival in the mini-MTX group was significantly lower than in the short-MTX group (46.9% vs. 88.7% at 1 year, p < 0.01), contributing to higher non-relapse mortality (NRM) in the mini-MTX group (32.0% vs. 5.0% at 1 year, p = 0.02). In multivariate analysis, the mini-MTX regimen was the most powerful prognostic factor for OS (hazard ratio 4.11; p = 0.03). Although the reduced dosage of MTX had no effect on neutrophil engraftment, increased NRM due to higher incidence of infection, graft failure, and severe acute GVHD resulted in a lower survival rate in the mini-MTX group after CBT.