Impact of the presence of HLA 1-locus mismatch and the use of low-dose antithymocyte globulin in unrelated bone marrow transplantation

Clinical effects of tacrolimus blood concentrations early after allogeneic hematopoietic stem cell transplantation

BACKGROUND AIMS

Tacrolimus (TAC) plus short-term methotrexate (stMTX) is used for graft-versus-host disease (GVHD) prophylaxis after allogeneic hematopoietic stem cell transplantation (allo-HSCT). TAC blood concentrations are frequently adjusted to enhance the graft-versus-leukemia/lymphoma effect or attenuate severe GVHD. Limited information is available on the clinical impact of these adjustments and the optimal time to perform them in order to achieve good clinical outcomes.

METHODS

We retrospectively analyzed 211 patients who underwent allo-HSCT at our institutes.

RESULTS

Higher TAC concentrations in week 3 correlated with a significantly higher cumulative incidence of relapse (CIR) (P = 0.03) and lower nonrelapse mortality (P = 0.04). The clinical impact of high TAC concentrations in week 3 on CIR was detected in the refined disease risk index: low/intermediate (P = 0.04) and high (P < 0.01), and conditioning regimens other than cyclophosphamide/total body irradiation and busulfan/cyclophosphamide (P = 0.07). Higher TAC concentrations in week 1 correlated with a lower grade 2-4 acute GVHD rate (P = 0.01). Higher TAC concentrations in weeks 2 and 3 correlated with slightly lower (P = 0.05) and significantly lower (P = 0.02) grade 3-4 acute GVHD rates, respectively. Higher TAC concentrations in weeks 1 and 3 were beneficial for severe acute GVHD in patients with a human leukocyte antigen-matched donor (P = 0.03 and P < 0.01, respectively), not treated with anti-thymocyte globulin (P = 0.02 and P = 0.02, respectively), and receiving three stMTX doses (P = 0.03 and P = 0.02, respectively).

CONCLUSIONS

The clinical impact of TAC concentrations varied according to patient characteristics, including disease malignancy, conditioning regimens, donor sources, and GVHD prophylaxis. These results suggest that TAC management needs to be based on patient profiles.

Outcomes of patients with hematological malignancies who undergo unrelated donor hematopoietic stem cell transplantation with ATG-Fresenius versus ATG-Genzyme

To compare the outcomes of patients with hematological malignancies who received ATG-Fresenius (ATG-F) 20 mg/kg versus those who received ATG-Genzyme (ATG-G) 10 mg/kg in an unrelated donor hematopoietic stem cell transplantation (HSCT) procedure, a total of 186 patients who underwent their first allogeneic HSCT with an unrelated donor were retrospectively analyzed. One hundred and seven patients received ATG-F, and seventy-nine patients received ATG-G. Multivariate analysis showed that the type of ATG preparation had no effect on neutrophil engraftment (P = 0.61), cumulative incidence of relapse (P = 0.092), nonrelapse mortality (P = 0.44), grade II-IV acute graft-versus-host disease (GVHD) (P = 0.47), chronic GVHD (P = 0.29), overall survival (P = 0.795), recurrence-free survival (P = 0.945) or GVHD-free relapse-free survival (P = 0.082). ATG-G was associated with a lower risk of extensive chronic GVHD and a higher risk of cytomegaloviremia (P = 0.01 and HR = 0.41, P < 0.001 and HR = 4.244, respectively). The results of this study suggest that the preparation of rabbit ATG used for unrelated HSCT should be selected based on the incidence of extensive chronic GVHD of each center, and the posttransplant management strategy should be adjusted according to the ATG preparation.

Human leukocyte antigen 7/8-matched unrelated bone marrow transplantation using anti-thymocyte globulin in children

Human leukocyte antigen (HLA) mismatched unrelated donor transplantation is associated with an increased risk of graft-versus-host disease, graft failure, and infection, which increases post-transplant morbidity and mortality. In this single-center retrospective study, outcomes were evaluated in 30 consecutive children who underwent bone marrow transplantation (BMT) from HLA 1 allele-mismatched (HLA 7/8-matched) unrelated donors with rabbit anti-thymocyte globulin (rATG) as graft-versus-host disease (GVHD) prophylaxis. The 3-year overall survival (OS), event-free survival (EFS), and GVHD-relapse-free survival rates were 91.7% (95% CI 70.5%-91.9%), 88.3% (95% CI 67.5%-96.1%), and 73.9% (95% CI 52.4%-86.8%), respectively. Grade II-IV and III-IV acute GVHD occurred in 10 (33%) and 2 (7.0%) patients, respectively. The 3-year cumulative incidence of chronic GVHD was 7.8%. No fatal viral infections occurred. The study results show the feasibility of HLA 7/8-matched unrelated BMT with ATG to achieve favorable outcomes and acceptable GVHD, especially for patients who lack a fully matched donor.

Phase I trial of myeloablative conditioning with 3-day total marrow and lymphoid irradiation for leukemia

This prospective phase I trial aimed to determine the recommended dose of 3-day total marrow and lymphoid irradiation (TMLI) for a myeloablative conditioning regimen by increasing the dose per fraction. The primary end-point of this single-institution dose escalation study was the recommended TMLI dose based on the frequency of dose-limiting toxicity (DLT) ≤100 days posthematopoietic stem cell transplantation (HSCT); a 3 + 3 design was used to evaluate the safety of TMLI. Three dose levels of TMLI (14/16/18 Gy in six fractions over 3 days) were set. The treatment protocol began at 14 Gy. Dose-limiting toxicities were defined as grade 3 or 4 nonhematological toxicities. Nine patients, with a median age of 42 years (range, 35-48), eight with acute lymphoblastic leukemia and one with chronic myeloblastic leukemia, received TMLI followed by unrelated bone marrow transplant. The median follow-up period after HSCT was 575 days (range, 253-1037). Three patients were enrolled for each dose level. No patient showed DLT within 100 days of HSCT. The recommended dose of 3-day TMLI was 18 Gy in six fractions. All patients achieved neutrophil engraftment at a median of 19 days (range, 14-25). One-year overall and disease-free survival rates were 83.3% and 57.1%, respectively. Three patients experienced relapse, and no nonrelapse mortality was documented during the observation period. One patient died due to disease relapse 306 days post-HSCT. The recommended dose of 3-day TMLI was 18 Gy in six fractions. The efficacy evaluation of this regimen is currently being planned in a phase II study.

HLA 1-3 antigen-mismatched related peripheral blood stem cells transplantation using low-dose antithymocyte globulin versus unrelated cord blood transplantation

Little information is available regarding whether unrelated cord blood transplantation (CBT) or an HLA 1-3 antigen-mismatched related donor peripheral blood stem-cell transplantation (PBSCT) using low-dose anti-thymocyte globulin (ATG) is superior as an alternative transplantation for patients who lack an HLA-matched sibling or unrelated donor. Therefore, we evaluated 7861 patients with hematologic malignancies (aged 0 to 70 years) who received either a CBT without ATG (CBT-no ATG, n = 7034) or an HLA 1-3 antigen-mismatched related donor PBSCT using low-dose ATG (PBSCT-ATG, n = 827). CBT-no ATG was associated with significantly better overall survival (OS) than the use of a PBSCT-ATG (hazard ratio [HR], 0.77; p < .001), although PBSCT-ATG patients with an HLA 1 antigen-mismatch showed OS comparable to that in the CBT-no ATG group. Neutrophil and platelet engraftment was significantly delayed, whereas the incidences of nonrelapse mortality, and severe graft-versus-host disease (GVHD) were significantly lower in the CBT-no ATG group. The incidences of relapse and chronic GVHD were comparable between these donors. In conclusion, CBT-no ATG may be a better alternative than HLA-mismatched related donor PBSCT using low-dose ATG. Notably, HLA 2-3 antigen mismatch-related transplantation with low-dose ATG had significant adverse effects on transplantation outcomes.

Decision Analysis for Unrelated Bone Marrow Transplantation or Immediate Cord Blood Transplantation for Patients with Philadelphia Chromosome-Negative Acute Lymphoblastic Leukemia in First Complete Remission

An HLA-matched relative is the first-choice donor for patients with Philadelphia chromosome (Ph)-negative acute lymphoblastic leukemia (ALL) in first complete remission (CR1). The most promising alternative donor is thought to be an HLA-matched unrelated donor (MUD) in patients who do not have an HLA-matched related donor. Cord blood transplantation (CBT) is an alternative option. Higher rates of engraftment failure and nonrelapse mortality are significant problems, but the ready availability of cord blood can be an advantage, because patients can immediately undergo transplantation before progression. This study was conducted to identify an appropriate alternative donor in patients with Ph-negative ALL in CR1 who do not have an HLA-matched related donor (MRD). Decision analyses using a Markov model were performed to compare immediate CBT, in which CBT was performed at 1 month after the achievement of CR1, with elective unrelated bone marrow transplantation (uBMT) from an 8/8 HLA-matched unrelated donor (MUD) (8/8 uBMT) or uBMT from 7/8 MUD (7/8 uBMT), in which uBMT was performed at 4 months, in patients age 16 to 55 years with Ph-negative ALL in CR1 who did not have an MRD. We constructed a decision tree. The cycle length was set at 3 months, and analyses were performed for 19 cycles for uBMT and 20 cycles for CBT, resulting in evaluation of the 5-year life expectancy after both decisions. Transition probabilities (TPs) and utilities were estimated from prospective and retrospective Japanese studies and the registry database of Japan. Subgroup analyses were performed according to risk stratification based on WBC count and cytogenetics at diagnosis and according to age stratification, with a cutoff of 25 years. One-way sensitivity analyses for TPs and utilities were performed as well. The baseline analyses showed that 8/8 uBMT or 7/8 uBMT had superior results to CBT, with quality-adjusted life years (QALYs) of 2.86 in 8/8 uBMT, 2.84 in 7/8 uBMT, and 2.75 in CBT. One-way sensitivity analyses showed that the results of the baseline analyses were reversed if the probability of nonrelapse mortality (NRM) in CBT improved. Subgroup analyses showed similar results in younger, older, and high-risk patients. However, QALY was worse in 8/8 uBMT compared with CBT in standard-risk patients. In one-way sensitivity analyses, the probabilities of NRM in uBMT and CBT affected the baseline results in all analyses except for comparisons between 8/8 uBMT and CBT in younger and high-risk patients. In these 2 populations, the superiority of 8/8 uBMT was consistently demonstrated throughout the one-way sensitivity analyses. For patients with Ph-negative ALL in CR1 who decide to undergo transplantation from an alternative donor, elective uBMT from either an 8/8 MUD or a 7/8 MUD is expected to yield a better outcome than immediate CBT. Nonetheless, CBT is a viable option, and improvements to reduce the risk of NRM in CBT may change these results.

Clinical study of graft-versus-host disease prophylaxis in unrelated hematopoietic stem cell transplantation for pediatric nonmalignant diseases with different doses anti-human T-lymphocyte immunoglobulin

BACKGROUND

Anti-human T-lymphocyte immunoglobulin is commonly used as prophylaxis for graft-versus-host disease after allogeneic hematopoietic stem cell transplantation from unrelated donors. The studies according to optimum dose of ATLG especially in pediatric patients are limited.

PATIENTS AND METHODS

Outcomes of 99 pediatric patients diagnosed with nonmalignant diseases, who received ATLG as GVHD prophylaxis for matched unrelated donor HSCT at a dose of 10 mg/kg (group 1), 20 mg/kg (group 2), and 30 mg/kg (group 3), were analyzed retrospectively.

RESULTS

The incidences of acute and chronic GVHD were statistically not different between three groups (p = .20 and p = .13), but we did not observe chronic GVHD in group 3 patients. Cox regression analysis showed that ATLG dose of 10 mg/kg (p = .007) and severe acute GVHD (p = .001) were significant prognostic factors for inferior overall survival. Although ATLG dose of 10 mg/kg is effective in pediatric patients on acute and chronic GVHD prevention, TRM and overall survival were superior in ATLG doses ≥20 mg/kg (p = .04 and p = .037) with no difference between 20 and 30 mg/kg.

CONCLUSION

Although ATLG dose of 10 mg/kg is effective in pediatric patients on acute and chronic GVHD prevention and safe from the point of infection, TRM and OS were superior in ATLG doses ≥20 mg/kg with no difference between 20 and 30 mg/kg. These observations should be supported with other multicenter prospective studies including larger patient population.

Hematopoietic Stem Cell Transplantation From a Related Donor with Human Leukocyte Antigen 1-Antigen Mismatch in the Graft-Versus-Host Direction Using Low-dose Anti-thymocyte Globulin

Hematopoietic stem cell transplantation (HSCT) from a related donor with an human leukocyte antigen (HLA) 1-antigen mismatch without in vivo T cell depletion is associated with an elevated risk of severe, acute, and chronic graft-versus-host (GVH) disease (GVHD) and poor survival. Therefore, we conducted a multicenter phase II trial of HSCT using low-dose anti-thymocyte globulin (ATG, thymoglobulin). We recruited patients aged 16–65 years with leukemia, myelodysplastic syndrome, or lymphoma who planned to receive HSCT from a related donor with HLA 1-antigen mismatch in the GVH direction at the HLA-A, -B, or -DR locus. Pretransplantation ATG was administered with standard GVHD prophylaxis consisting of tacrolimus and methotrexate. Thirty-eight patients were eligible for the analysis. The 1-year GVHD-free relapse-free survival (GRFS) was 47%. The 3-year overall survival (OS) was 57%. Age of less than 50 years was associated with better OS. OS in patients with high/very high refined disease risk indexes (rDRIs) was comparable to that in those with low/intermediate rDRIs. The 100-day cumulative incidences of grades II–IV and III–IV acute GVHD were 45% and 18%, respectively. HSCT from a related donor with two allele mismatches showed higher incidences of grades II–IV and III–IV acute GVHD. Three-year cumulative incidences of moderate to severe or severe chronic GVHD were 13% and 3%, respectively. HSCT from a related donor with one locus mismatch at the antigen level using low-dose ATG showed lower incidences of acute and chronic GVHD, which led to acceptable GRFS, OS, relapse, and nonrelapse mortality.

Human leukocyte antigen disparities reduce relapse after hematopoietic stem cell transplantation in children with juvenile myelomonocytic leukemia: A single-center retrospective study from China

BACKGROUND

HSCT is the only proven curative therapy for JMML. Matching donor and recipient HLA alleles is considered optimal to reduce the risk of GVHD after HSCT but is not always possible. Only a limited number of studies have compared the influence of HLA disparities on HSCT outcomes for patients with JMML.

METHODS

We conducted a retrospective study among 47 children with JMML who received related or unrelated unmanipulated HSCT (March 2010-October 2018). Among our participants, 27 (57.4%) donor-recipient pairs had 0-1 HLA disparities (Group 1: HLA-matched or ≤1 allele/antigen mismatch donor) and 20 (42.6%) had ≥2 HLA disparities (Group 2: 2-3 mismatched/haploidentical donors).

RESULTS

The median follow-up period was 26.0 months (range: 1-105 months), and the 5-year probabilities of DFS and RI for the whole cohort were 54.6 ± 7.7% and 34.8 ± 15.0%, respectively. Compared to Group 1, Group 2 patients had a significantly lower RI (5.3 ± 10.5% vs 55.5 ± 20.9%, P ˂ .001), though similar rates of grade II-IV acute GVHD (60.0 ± 22.4% vs 33.3 ± 18.2%, P = .08), grade III-IV acute GVHD (25.0 ± 19.5% vs 7.4 ± 10.1%, P = .08), chronic GVHD (30.0 ± 20.9% vs 34.9 ± 18.8%, P = .85), NRM (20.0 ± 18.0% vs 3.9 ± 7.7%, P = .07), and DFS (74.4 ± 9.9% vs 41.3 ± 10.0%, P = .08).

CONCLUSIONS

Disease relapse remains the major cause of treatment failure in JMML patients, especially in patients receiving HLA-matched and limited HLA-mismatched HSCT. Our findings suggest that donor-recipient HLA disparities may improve the outcome of HSCT in children with JMML.

[Optimization of ATG dose in haploid hematopoietic stem cell transplantation for hematologic malignancies]

Objective: To compare the clinical efficacy of different doses of rabbit antithymocyte globulin (rATG) in haplo-HSCT in the treatment of hematologic malignancies. Methods: Malignant hematological patients treated at our hospital from March 2013 to December 2018 were retrospectively analyzed. These patients were divided into three groups as per three doses of ATG (6 mg/kg, 7.5 mg/kg, and 9 mg/kg) in the conditioning regimens. The transplant outcomes were compared in terms of the occurrence of acute graft versus host disease (GVHD) , infection, and survival. Results: ①Total 288 patients were enrolled in the study, including 182 men and 106 women, with a median age of 18 (6-62) years. Total 110 patients were diagnosed with acute lymphoblastic leukemia (ALL) , 128 with acute myelogenous leukemia (AML) , 8 with chronic myeloid leukemia (CML) , 28 with myelodysplastic syndrome (MDS) , and 14 with mixed cell leukemia (MAL) . There were 159 patients in the ATG-6 group, 72 in the ATG-7.5 group, and 57 in the ATG-9 group. The median follow-up time of post transplantation was 14 (0.2-74) months. ②The incidence of neutrophil engraftment (96.9% , 97.2% , and 96.5% , respectively) and platelet engraftment (92.5% , 87.5% , and 86% , respectively) did not significantly differ among the ATG-6, ATG-7.5, and ATG-9 groups (P=0.972, P=0.276) . The incidence of grades 2-4 acute GVHD was 14.5% , 11.1% , and 8.8% in the three groups, respectively (P=0.493) , chronic GVHD incidence in the three group was 8.8% , 14.3% and 12.0% , respectively (P=0.493) . The infection rates of CMV and EBV in the ATG-9 group (77.2% and 12.5% ) were significantly higher than those in the ATG-6 (43.3% and 3.5% ) , and ATG -7.5 group (44.4% and 1.5% ) (P<0.001 and P=0.033, respectively) . ③Among the three groups, there were no significant difference in the 3-year overall survival [68.5% (95% CI 60.3% -77.9% ) , 60.1% (95% CI 48.3% -74.8% ) , 64.7% (95% CI 51.9% -80.7% ) ], cumulative incidences of relapse [34.6% (95% CI 34.3% -35.1% ) , 38.0% (95% CI 37.3% -38.7% ) , 20.6% (95% CI 20.0% -21.3% ) ], disease-free survival [53.3% (95% CI 44.9% -63.4% ) , 51.9% (95% CI 41% -65.8% ) , 63.9% (95% CI 51.9% -78.7% ) ] and non-relapse mortality [24.2% (95% CI 23.8% -24.5% ) , 26.0% (95% CI 25.4% -26.6% ) , 23.6% (95% CI 26.3% -28.2% ) ] (P=0.648, P=0.165, and P=0.486 and P=0.955) . Conclusion: Low dose (6 mg/kg) of rATG may increase the risk of grade Ⅱ-Ⅳ aGVHD, and a high dose (9 mg/kg) of ATG could significantly increase the risk of CMV and EBV infection. Median dose (7.5 mg/kg) of ATG is expected to reduce the incidence of moderate to severe aGVHD and viral infections without increasing the mortality.

Updated Comparison of 7/8 HLA Allele-Matched Unrelated Bone Marrow Transplantation and Single-Unit Umbilical Cord Blood Transplantation as Alternative Donors in Adults with Acute Leukemia

The outcomes of 7/8 allele-matched unrelated bone marrow transplantation (7/8 UBMT) and umbilical cord blood transplantation (UCBT) have been improving. We retrospectively analyzed adults with acute leukemia who underwent their first 7/8 UBMT or UCBT in Japan. Between January 2008 and December 2017, a total of 4150 patients were recorded, including 488 who underwent 7/8 UBMT and 3662 who underwent UCBT. Only 32 patients with 7/8 UBMT had graft-versus-host-disease (GVHD) high-risk HLA mismatched pairs. Overall survival at 3 years was 54% for 7/8 the UBMT group and 46% for the UCBT group, a nonsignificant difference in multivariate analysis (hazard ratio [HR], 1.01; 95% confidence interval [CI], .88 to 1.17; P = .89). The 7/8 UBMT and UCBT groups showed a similar nonrelapse mortality rate (HR, 1.16; 95% CI, .96 to 1.45; P = .16) and relapse rate (HR, .85; 95% CI, .71 to 1.02; P = .08). However, the UCBT group had a lower risk of grade II-IV acute GVHD (HR, .76; 95% CI, .65 to .88; P < .001) and chronic GVHD (HR, .77; 95% CI, .66- .91; P = .002) compared with the 7/8 UBMT group. In stratified analyses combining disease risk with conditioning intensity, 7/8 UBMT showed superior overall survival to UCBT in standard risk and myeloablative conditioning (HR, .72; 95% CI, .56 to .93; P = .014). Both 7/8 UBMT and UCBT are appropriate alternative donor procedures. The stem cell source can be selected on the basis of disease risk, patient tolerability, or concerns regarding GVHD.

Hematopoietic cell transplant outcomes after myeloablative conditioning with fludarabine, busulfan, low-dose total body irradiation, and rabbit antithymocyte globulin

Optimal conditioning and graft-vs-host disease (GVHD) prophylaxis for hematopoietic cell transplantation (HCT) are unknown. Here, we report on outcomes after low toxicity, myeloablative conditioning consisting of fludarabine, busulfan, and 4 Gy total body irradiation, in combination with thymoglobulin and post-transplant methotrexate and cyclosporine. We retrospectively studied 700 patients with hematologic malignancies who received blood stem cells from 7 to 8/8 HLA-matched unrelated or related donors. Median follow-up of surviving patients was 5 years. At 5 years, overall survival (OS), relapse-free survival (RFS), and chronic GVHD/relapse-free survival (cGRFS) were 58%, 55%, and 40%. Risk factors for poor OS, RFS, and cGRFS were (1). high to very high disease risk index (DRI), (2). high recipient age, and (3). cytomegalovirus (CMV)-seropositive recipient with seronegative donor (D-R+). The latter risk factor applied particularly to patients with lymphoid malignancies. Neither donor other than HLA-matched sibling (7-8/8 unrelated) nor one HLA allele mismatch was risk factors for poor OS, RFS, or cGRFS. In conclusion, the above regimen results in excellent long-term outcomes. The outcomes are negatively impacted by older age, high or very high DRI, and CMV D-R+ serostatus, but not by donor unrelatedness or one HLA allele mismatch.

Influence of HLA 1-3-locus mismatch and antithymocyte globulin administration in unrelated bone marrow transplantation

For patients without an HLA-matched donor, an HLA-mismatched unrelated donor (MMUD) has been considered as an alternative donor in allogeneic hematopoietic cell transplantation (allo-HCT). We conducted a nationwide retrospective study to compare the transplant outcomes among 1-, 2-, and 3-locus (allele/antigen) mismatched unrelated donors (1MMUD n = 2044, 2MMUD n = 492, and 3MMUD n = 73) in allo-HCT and to assess the impact of antithymocyte globulin (ATG) in allo-HCT from 1-3MMUD. 2MMUD and 3MMUD were independent significant adverse factors for grade III-IV acute graft-versus-host disease (GVHD) (hazard ratio [HR] 1.72, p < 0.001 and HR 2.48, p < 0.001), non-relapse mortality (NRM) (HR 1.47, p < 0.001 and HR 2.00, p < 0.001), and overall survival (OS) (HR 1.21, p = 0.0066 and HR 1.60, p = 0.0015). Conversely, the use of ATG was an independent favorable factor for grade III-IV acute GVHD (HR 0.43, p < 0.001), NRM (HR 0.51, p < 0.001), and OS (HR 0.74, p = 0.0012). On the other hand, HLA compatibility and the use of ATG were not associated with a risk of relapse. An interaction test between the number of HLA mismatches and the use of ATG revealed that the effect of ATG on NRM and OS in the 2MMUD group was significantly less than that in the 1MMUD group (HR 1.53, p = 0.036 and HR 2.34, p = 0.0046). This study indicated that the number of HLA mismatches and the use of ATG were significantly associated with not only GVHD, but also NRM and OS. Whereas the use of ATG could improve transplant outcomes in allo-HCT from 1MMUD, its effectiveness with 2MMUD and 3MMUD was limited.

Impacts of thymoglobulin in patients with acute leukemia in remission undergoing allogeneic HSCT from different donors

Antithymocyte globulin (ATG) is widely used to reduce acute graft-versus-host disease (aGVHD) and chronic GVHD (cGVHD). To clarify the different impacts of ATG for conditioning across different donor types, we retrospectively analyzed patients with acute leukemia (n = 6617) who underwent hematopoietic stem cell transplantation between 2008 and 2015 with ATG (n = 279) or without ATG (n = 6338). Because thymoglobulin is the only ATG drug approved for GVHD prophylaxis in Japan since September 2008, we included thymoglobulin alone in the present analysis. The survivors' median follow-up time was 1081 days. Patients were categorized into 5 groups: cord blood (CB; n = 1915), matched related donor (n = 1772), 1-antigen mismatched related donor (1-MMRD; n = 225), matched unrelated donor (MUD; n = 1742), and 1-allele mismatched unrelated donor (1-MMUD; n = 963). In multivariate analysis, ATG decreased overall survival (hazard ratio [HR], 1.403; P = .054) and GVHD-free/relapse-free survival (GRFS) (HR, 1.458; P = .053) in association with increased nonrelapse mortality (NRM) (HR, 1.608; P =03) with CB, whereas it improved GRFS (HR, 0.515; P < .01) and decreased grades II to IV aGVHD (HR, 0.576; P < .01), extensive cGVHD (HR, 0.460; P = .02), and NRM (HR, 0.545; P = .03) with 1-MMUD. ATG did not impact survival with 1-MMRD and MUD. The use of ATG in conditioning is beneficial due to the reduction in acute/chronic GVHD without increasing NRM or disease relapse only in 1-MMUD transplantation. On the other hand, ATG is not recommended for CB transplantation.

Personalizing rabbit anti-thymocyte globulin therapy for prevention of graft-versus-host disease after allogeneic hematopoietic cell transplantation: is there an optimal dose?

The efficacy of anti-thymocyte globulin (ATG) as prophylaxis for graft-versus-host disease (GVHD) has been investigated by many clinical studies over the past decade, including some randomized controlled trials. Intriguingly, although ATG is commonly used as prophylaxis for GVHD, there is still controversy about the optimal dose of ATG for prophylaxis of GVHD after allogeneic hematopoietic cell transplantation (allo-HCT). Indeed, the dose and formulation of ATG, as well as the degree of clinical benefit, has varied among studies, which makes it difficult to fully determine the clinical benefit of ATG. The aim of this review is to summarize the information regarding the optimal ATG dose of each formulation according to stem cell source, and to discuss how best to determine the personalized optimal dose of ATG in each allo-HCT recipient.

Short-term clinical outcomes after HLA 1-locus mismatched uPBSCT are similar to that after HLA-matched uPBSCT and uBMT

In Japan, use of unrelated peripheral blood stem cell transplantation (uPBSCT) from HLA-mismatched unrelated donors has recently been approved. We compared outcomes between HLA-matched and 1-locus mismatched uPBSCT, as well as the impact of HLA disparity in uPBSCT and in unrelated bone marrow transplantation (uBMT). In total, 5862 uBMT recipients and 234 uPBSCT recipients were included. In terms of HLA allele disparity, 185 uPBSCT patients (79.1%) had no HLA mismatch, and 49 (20.9%) had 1-locus mismatch; in comparison, 3585 uBMT patients (61.2%) had no HLA mismatch, and 2277 (38.8%) had 1-locus mismatch. The impact of 1-locus mismatch as compared with match in uPBSCT was not significantly higher than in uBMT [hazard ratio (HR) = 1.02 and 1.27 for grade III-IV acute graft-versus-host disease, HR = 0.98 and 1.14 for non-relapse mortality, and HR = 0.87 and 1.06 for overall survival, respectively]. In conclusion, the impact of single-locus mismatch on short-term outcomes was comparable in uPBSCT and uBMT. Larger studies with longer follow-up are needed to assess long-term outcomes.

Feasibility of salvage cord blood transplantation using a fludarabine, melphalan, and low-dose anti-thymocyte globulin conditioning regimen

Primary graft failure (PGF) is a lethal complication that occurs early after allogeneic stem cell transplantation (allo-SCT). Cord blood transplantation (CBT) is a potential re-transplantation option. Total body irradiation (TBI) is often incorporated into the pre-salvage CBT conditioning regimen following PGF; however, patients experiencing PGF are not always amenable to TBI, and non-TBI regimens for salvage CBT should be established. Here, we report five patients with hematologic malignancies who received salvage CBT for PGF following a non-TBI regimen using fludarabine (Flu), melphalan (Mel), and low-dose anti-thymocyte globulin (ATG). The median intervals between the failed allo-SCT and salvage CBT, as well as between the diagnosis of PGF and salvage CBT, were 37 days and 8 days, respectively. The median neutrophil recovery period was 21 days (range 18-21 days). Four of five patients achieved neutrophil engraftment following salvage CBT; all four exhibited sustained engraftment with complete donor chimerism. Three of the five patients were alive after a median follow-up time of 907 days (range 315-909 days) post-salvage CBT; two patients died of causes unrelated to recurrence. These data suggest that CBT following the non-TBI regimen described here is feasible in patients with PGF.