Unrelated donor BMT recipients given pretransplant low-dose antithymocyte globulin have outcomes equivalent to matched sibling BMT: a matched pair analysis

The influence of lymphoid reconstitution kinetics on clinical outcomes in allogeneic stem cell transplantation

Lymphoid recovery following myeloablative stem cell transplantation (SCT) displays a logistic pattern of exponential growth followed by a plateau. Within this logistic framework, lymphoid recovery is characterized by the parameters R (slope of ascent), a (time of maximal rate of ascent) and K (plateau), the 'steady-state' lymphocyte count. A retrospective analysis of allogeneic SCT performed from 2008 to 2013 was undertaken to compare lymphoid recovery and clinical outcomes in 131 patients with acute myelogenous leukemia, acute lymphocytic leukemia, and myelodysplastic syndromes. Using Prism software, a logistic curve was successfully fit to the absolute lymphocyte count recovery in all patients. Patients were classified according to the magnitude and rate of lymphoid recovery; pattern A achieved an absolute lymphocyte counts (ALC) of >1000/μL by day 45, pattern B an ALC 500 < x < 1000/μL, and pattern C an ALC <500/μL. Pattern A was characterized by a higher mean K (p < .0001) compared with patterns B and C. Patients with patterns B and C were more likely to have mixed T cell chimerism at 90 d following SCT (p = .01). There was a trend towards improved survival (and relapse-free survival) in those with pattern A and B at 1 year compared to pattern C (p = .073). There was no difference in cGVHD (p = .42) or relapse (p = .45) between pattern types. Cytomegalovirus (CMV), aGVHD, and all relapse were heralded by deviation from logistic behavior. Pattern C patients were more likely to require donor lymphocyte infusion (DLI) (p = .017). Weaning of tacrolimus post-transplant was associated with a second, separate logistic expansion in some patients. This study demonstrated that lymphoid reconstitution follows a prototypical logistic recovery and that pattern observed correlates with T cell chimerism and need for DLI, and may influence survival.

Impact of cyclosporine-A concentration in T-cell replete haploidentical allogeneic stem cell transplantation

This paper aims to study whether cyclosporine-A (CSA) levels have an impact on the clinical outcome of patients with T-cell replete haploidentical allogeneic hematopoietic stem cell transplantation (allo-HSCT). We analyzed 140 consecutive patients who had been given T-cell replete haploidentical allo-HSCT in our institute to assess the effect of CSA concentration in the early stages of allo-HSCT on clinical outcomes, such as hematopoietic recovery, acute graft vs host disease (aGVHD), infection, disease-free survival (DFS), and overall survival (OS). The median concentrations of CSA in the blood in the 1st, 2nd, 3rd, and 4th week after allo-HSCT were 218, 235, 263, and 270 ng/mL, respectively. Additionally, 46%, 40%, 27%, and 18% of the patients had CSA blood levels below 200 ng/mL during those weeks. In total, 39 patients developed aGVHD (grade II-IV), for a cumulative incidence of 27.8%, at a median of 32 days. Patients having a low CSA concentration (below 200 ng/mL) in the 3rd week had a higher cumulative incidence of grade II-IV aGVHD (P = .02). In addition, multivariate logistic regression analysis showed that low CSA concentration (below 200 ng/mL) in the 3rd week was an independent risk factor of grade II-IV aGVHD (P = .02; odds ratio = 2.66; 95% CI, 1.15-6.17). However, CSA levels during the first 4 weeks did not have a significant impact on the patients' hematopoietic recovery, infection, DFS, and OS. Our data indicated that adequate management of CSA levels during the peri-engraftment period might improve clinical outcomes for those with T-cell replete haploidentical allo-HSCT.

Comparison of outcomes in hematological malignancies treated with haploidentical or HLA-identical sibling hematopoietic stem cell transplantation following myeloablative conditioning: A meta-analysis

Purpose

Haploidentical and human leukocyte antigen (HLA)-identical sibling hematopoietic stem transplantation are two main ways used in allogeneic hematopoietic stem cell transplantation (allo-HSCT). In recent years, remarkable progress has been made in haploidentical allo-HSCT (HID-SCT), and some institutions found HID-SCT had similar outcomes as HLA-identical sibling allo-HSCT (ISD-SCT). To clarify if HID-SCT has equal effects to ISD-SCT in hematologic malignancies, we performed this meta-analysis.

Methods

Relevant articles published prior to February 2017 were searched on PubMed. Two reviewers assessed the quality of the included studies and extracted data independently. Odds ratio (OR) and 95% confidence intervals (CIs) were calculated for statistical analysis.

Results

Seven studies including 1919 patients were included. The rate of platelet engraftment is significantly lower after HID-SCT versus ISD-SCT while there is no difference in neutrophil engraftment (OR = 2.58, 95% CI = 1.70–3.93, P < 0.00001). The risk of acute graft-versus-host disease (GVHD) is significantly higher after HID-SCT versus ISD-SCT (OR = 1.88, 95% CI = 1.42–2.49, P < 0.00001), but the relapse rate is lower in HID-SCT group (OR = 0.70, 95% CI = 0.55–0.90, P = 0.005). The incidence rates of overall survival (OS) and disease-free-survival/leukemia-free survival/relapse-free survival (DFS/LFS/RFS) after ISD-SCT are all significantly superior to HID-SCT (OR = 1.32, 95% CI = 1.08–1.62, P = 0.006; OR = 1.25, 95% CI = 1.03–1.52, P = 0.02). There is no significant difference in transplantation related mortality (TRM) rate after HID-SCT and ISD-SCT.

Conclusion

After myeloablative conditioning, patients receiving ISD-SCT have a faster engraftment, lower acute GVHD and longer life expectancy compared to HID-SCT with GVHD prophylaxis (cyclosporine A, methotrexate, mycophenolate mofetil and antithymoglobulin; CsA + MTX + MMF + ATG). Currently, HID-SCT with GVHD prophylaxis (CsA + MTX + MMF + ATG) may not replace ISD-SCT when HLA-identical sibling donor available.

Low dose anti-thymocyte globulin reduces chronic graft-versus-host disease incidence rates after matched unrelated donor transplantation

Anti-thymocyte globulin (ATG) is often added to hematopoietic stem cell transplant conditioning regimens to prevent graft rejection and reduce graft-versus-host disease (GVHD). Doses used in retrospective and prospective clinical trials have ranged from 2.5 to 20 mg/kg with rates of grade II-IV acute GVHD and chronic GVHD up to 40 and 60%, respectively. We retrospectively compared outcomes in recipients of matched unrelated donor (MUD) grafts given low dose rabbit ATG IV 3 mg/kg (n = 52) versus recipients of matched related donor (MRD) grafts (n = 48) without ATG. One year cumulative incidence of chronic GVHD was 25.2% in the MUD group versus 33.3% in the MRD group (p = .5). One-year cumulative incidence of extensive chronic GVHD was 9.6% in the MUD group versus 26.6% in the MRD group (p = .042). Our analysis supports the use of low dose ATG in MUD transplantation as an effective therapy to prevent chronic GVHD.

Reduced-Intensity Conditioning with Busulfan, Fludarabine, and Antithymocyte Globulin for Hematopoietic Cell Transplantation from Unrelated or Haploidentical Family Donors in Patients with Acute Myeloid Leukemia in Remission

To investigate the role of antithymocyte globulin (ATG)-containing reduced-intensity conditioning (RIC) in hematopoietic cell transplantation (HCT) from unrelated (UD) or haploidentical family donors (HFD), we conducted a phase 2 trial of 237 patients (age range, 16 to 69 years) with acute myeloid leukemia (AML) in remission. Patients undergoing UD-HCT (n = 93) or HFD-HCT (n = 59) received RIC comprising busulfan, fludarabine, and ATG, 9 mg/kg, whereas those undergoing HCT from matched sibling donors (MSD, n = 85) received myeloablative busulfan and cyclophosphamide conditioning or aforementioned RIC with ATG, 4.5 mg/kg. For graft-versus-host disease (GVHD) prophylaxis, cyclosporine and methotrexate were administered. The median follow-up period was 44.7 months after HCT for 161 survivors. For UD-HCT versus HFD-HCT, there were no significant differences in leukemia recurrence, nonrelapse mortality, relapse-free survival, grades 2 to 4 acute GVHD, and moderate-to-severe chronic GVHD. Furthermore, when the outcomes of UD-HCT and HFD-HCT were combined and compared with those of MSD-HCT, there were no significant differences in leukemia recurrence (3-year cumulative incidence, 30% versus 29%), nonrelapse mortality (3-year cumulative incidence, 7% versus 8%), relapse-free survival (3-year estimate, 63% versus 63%), and grades 2 to 4 acute GVHD (120-day cumulative incidence, 16% versus 13%). Moderate-to-severe chronic GVHD, however, occurred less frequently in UD/HFD-HCT (2-year cumulative incidence, 22% versus 40%; P = .006). The addition of ATG to conditioning regimen was a significant predictor for less chronic GVHD (subdistribution hazard ratio, .59). In AML in remission, UD/HFD-HCT after ATG-containing RIC achieved leukemia control equivalent to that of MSD-HCT. Despite HLA disparity in UD/HFD-HCT, chronic GVHD occurred less frequently after ATG-containing RIC, suggesting a strong GVHD-modulating effect of ATG.

Optimal dose of rabbit thymoglobulin in conditioning regimens for unmanipulated, haploidentical, hematopoietic stem cell transplantation: Long-term outcomes of a prospective randomized trial

BACKGROUND

Antithymocyte globulin (ATG) is an important component of conditioning regimens to prevent severe graft-versus-host disease (GVHD) in patients undergoing unmanipulated, haploidentical stem cell transplantation (haplo-SCT). However, to the authors' knowledge, the optimal dose of ATG is unknown.

METHODS

In this prospective, randomized trial, the authors compared the long-term outcomes of 2 ATG doses (rabbit thymoglobulin) used in myeloablative conditioning before unmanipulated haplo-HSCT. Patients were randomly assigned (1:1) to received 10 mg/kg (ATG-10) or 6 mg/kg (ATG-6) of ATG. Analysis of disease-free survival, GVHD-free/recurrence-free survival (GRFS), disease recurrence, nonrecurrence mortality, and chronic GVHD (cGVHD) included the entire population. Late effects were assessed in disease-free patients who had survived for at least 6 months and had received regular follow-up evaluations.

RESULTS

A total of 224 patients were recruited. The median follow-up period was 1614 days (range, 28-1929 days). The rate of infection-related deaths in ATG-10 arm was double that of the ATG-6 arm (14.3% vs 7.1%; P = .084). The 5-year cumulative incidence was comparable between the ATG-6 and ATG-10 groups for disease recurrence (12.8% vs 13.4%; P = .832) and nonrecurrence mortality (11.6% vs 17.0%; P = .263). The 5-year probability of disease-free survival was comparable between the groups (75.6% vs 69.6%; P = .283). The 5-year cumulative incidence of cGVHD was found to be higher with ATG-6 (75.0% vs 56.3% [P = .007] and moderate-to-severe cGVHD: 56.3% vs 30.4% [P<.0001]) as well as that for late effects (71.2% vs 56.9%; P = .043). The 5-year probability of GRFS was higher in the ATG-10 group (41.0% vs 26.8%; P = .008). In the multivariate analysis, ATG-10 was found to be associated with a lower risk of cGVHD and improved GRFS.

CONCLUSIONS

ATG-10 was found to be associated with better GVHD prevention and superior GRFS, but an increase in infection-related deaths. Cancer 2017;123:2881-92. © 2017 American Cancer Society.

Impact of ATG Dose on the Outcome of Patients Undergoing Reduced Intensity Conditioning Followed by Allogeneic Hematopoietic Stem Cell Transplantation for Hematological Malignancies

Reduced intensity conditioning for allogeneic hematopoietic stem cell transplantation (allo-HSCT) is often proposed for patients with comorbidities. To enhance engraftment and limit graft-versus-host disease (GVHD), antithymoglobulin (ATG) is usually used. However, the dose needed remains unclear unlike myeloablative conditioning. In order to clarify this point, we conducted a retrospective study on patients who received a reduced intensity conditioning allo-HSCT based on a 2-day fludarabine and busulfan treatment with either 1 or 2 days of ATG treatment. One hundred and eight patients received 2.5 mg/kg (ATG2.5) and another 60 patients 5 mg/kg (ATG5). The median follow-up was 36 months. The median overall survival was 39 months and the median disease-free survival 45 months. In multivariate analysis, overall nonrelapse mortality (NRM) was independently influenced by the acute GVHD grade III-IV (p < 0.001) and ATG dose (30 vs. 21% for ATG5; p = 0.008). Despite heterogeneity of populations, using proportional-hazard assumptions, we have been able to observe in multivariate analysis a lower NRM in the ATG5 group. This leads to a statistically higher overall survival for the ATG5 group. In conclusion, 2 days of ATG decrease NRM independently without increasing the risk of relapse or infectious disease.

Does anti-thymocyte globulin have a place in busulfan/fludarabine conditioning for matched related donor hematopoietic stem cell transplantation?

BACKGROUND/AIMS

There is controversy about the prophylactic effect of anti-thymocyte globulin (ATG) on graft versus host disease (GVHD) in the setting of matched related-donor hematopoietic stem cell transplantation (HSCT). This study assessed the inf luences of ATG on the incidences of acute and chronic GVHD and other clinical outcomes in matched related-donor HSCT.

METHODS

Sixty-one patients received allogeneic HSCT from human leukocyte antigen-matched, related donors. Patients received busulfan/fludarabine conditioning regimens and standard GVHD prophylaxis with or without additional ATG.

RESULTS

There was no significant difference in the cumulative incidences of overall acute GVHD, grade II to IV acute GVHD at day 100, and chronic GVHD during the follow-up period between the ATG and non-ATG groups. Three-year overall survival rates were very similar, but three year disease-free survival of the non-ATG group was higher than that of the ATG group (56.2% for ATG vs. 63.1% for non-ATG, p = 0.597). Relapse rate at 3 years in the ATG group was slightly higher than that of the non-ATG group (37.5% vs. 20%, p = 0.29). Non-relapse mortality rate at 3 years was lower in the ATG group (6.25% vs. 15.6%, p = 0.668).

CONCLUSIONS

Although the addition of ATG doesn't guarantee a reduction in the incidences of acute and chronic GVHD, pre-transplantation ATG may result in lower non-relapse mortality in the context of matched related-donor HSCT with a busulfan/fludarabine conditioning regimen. However, caution is needed when using ATG because of a possibility to increase relapse rate.

The efficacy and safety of rabbit anti-thymocyte globulin vs rabbit anti-T-lymphocyte globulin in peripheral blood stem cell transplantation from unrelated donors

The comparative efficacy and safety of antithymocyte globulin (ATG) at fixed doses in patients undergoing allogeneic peripheral blood stem cell transplantation from unrelated donors (UR-PBSCT) has not been evaluated. In this study, the records of 56 patients and 54 patients who received pre-transplant ATG-Thymoglobulin (ATG-T) at a total dose of 10 mg/kg and ATG- Fresenius (ATG-F) at a total dose of 20 mg/kg, respectively, were retrospectively analyzed. ATG-F patients had a significantly lower probability of developing chronic graft-vs-host disease (cGVHD) than those treated with ATG-T (p = 0.04). ATG-F was associated with a non-significant trend towards lower relapse rates and higher survival at 3- and 5-years of follow-up compared with ATG-T. A significantly greater proportion of ATG-T patients experienced chills and high fever than ATG-F patients (p < 0.01). The current findings suggest that ATG-F may more effectively and safely prevent cGVHD without increasing relapse rates in patients undergoing UR-PBSCT.

New directions for rabbit antithymocyte globulin (Thymoglobulin(®)) in solid organ transplants, stem cell transplants and autoimmunity

In the 30 years since the rabbit antithymocyte globulin (rATG) Thymoglobulin^® was first licensed, its use in solid organ transplantation and hematology has expanded progressively. Although the evidence base is incomplete, specific roles for rATG in organ transplant recipients using contemporary dosing strategies are now relatively well-identified. The addition of rATG induction to a standard triple or dual regimen reduces acute cellular rejection, and possibly humoral rejection. It is an appropriate first choice in patients with moderate or high immunological risk, and may be used in low-risk patients receiving a calcineurin inhibitor (CNI)-sparing regimen from time of transplant, or if early steroid withdrawal is planned. Kidney transplant patients at risk of delayed graft function may also benefit from the use of rATG to facilitate delayed CNI introduction. In hematopoietic stem cell transplantation, rATG has become an important component of conventional myeloablative conditioning regimens, following demonstration of reduced acute and chronic graft-versus-host disease. More recently, a role for rATG has also been established in reduced-intensity conditioning regimens. In autoimmunity, rATG contributes to the treatment of severe aplastic anemia, and has been incorporated in autograft projects for the management of conditions such as multiple sclerosis, Crohn’s disease, and systemic sclerosis. Finally, research is underway for the induction of tolerance exploiting the ability of rATG to induce immunosuppresive cells such as regulatory T-cells. Despite its long history, rATG remains a key component of the immunosuppressive armamentarium, and its complex immunological properties indicate that its use will expand to a wider range of disease conditions in the future.

Alternative Donor Allogeneic Hematopoietic Cell Transplantation for Acute Myeloid Leukemia

Allogeneic hematopoietic cell transplantation (alloHCT) provides a potentially curative therapy for patients with high-risk or chemorefractory acute myeloid leukemia (AML). Historically, the applicability of alloHCT has been limited as only 30%-35% of patients have human leukocyte antigen (HLA)-matched siblings and outcomes using other donor types have been markedly inferior due to excess toxicity, graft failure, graft-versus-host disease (GVHD), and consequently non-relapse mortality. Advances in HLA typing, GVHD prophylactic approaches, and other transplantation techniques have successfully addressed these historical challenges. Herein, we review recent alloHCT studies using volunteer unrelated donors, umbilical cord blood units, or HLA-haploidentical donors, specifically focusing on studies that compared outcomes between donor sources. Although none are randomized and most are retrospective, these analyses suggest that current outcomes for AML patients using most alternative donor types are comparable to those seen using HLA-matched siblings.

Older recipient age is paradoxically associated with a lower incidence of chronic GVHD in thymoglobulin recipients: a retrospective study exploring risk factors for GVHD in allogeneic transplantation with thymoglobulin GVHD prophylaxis

Thymoglobulin (TG) given with conditioning for allogeneic haematopoietic SCT (alloHSCT) is effective in reducing the risk of acute and chronic GVHD (cGVHD). Whether conventional risk factors for GVHD apply to TG-conditioned alloHSCT is unknown. We retrospectively studied 356 adults from three centres who received TG 4.5 mg/kg prior to alloHSCT for haematologic malignancy. Donors were unrelated in 64%. At 3 years, OS was 61% (95% confidence interval (CI) 55-67%), cumulative incidence of relapse was 28% (95% CI 23-33%) and non-relapse mortality was 19% (14-24%). The cumulative incidences of grade 2-4, and grade 3-4 acute GVHD were 23% (95% CI 19-28%) and 10% (95% CI 6-13%), respectively. The cumulative incidence of cGVHD requiring systemic immunosuppression (cGVHD-IS) at 3 years was 32% (95% CI 27-37%). On multivariate analysis, counterintuitively, recipient age over 40 was associated with a significantly decreased risk of cGVHD-IS (P=0.001). We report for the first time a paradoxical association of older age with reduced cGVHD in TG recipients, and conclude that traditional risk factors for GVHD may behave differently in the context of pre-transplant TG.

HLA disparity is not crucial for the survival rate and severity of chronic health conditions in adult recipients following family donor hematopoietic stem cell transplantation

The shortage of HLA-identical siblings or unrelated donors has restricted the application of hematopoietic stem cell transplantation (HSCT). Few studies have systematically assessed survival and chronic health conditions (CHCs) in the same cohort of patients after HLA-mismatched/haploidentical (mismatched) family donor transplantation. In the present study, we retrospectively analyzed the survival of 127 adult patients receiving either HLA-matched (71 cases) or HLA-mismatched (56 cases) family donor transplantation. Of 127 patients, 81 patients survived at least 2 years after HSCT and were still alive until the present investigation. We evaluated the CHCs in 76 survivors (41 matched and 35 mismatched). CHC-related information was scored according to the Bone Marrow Transplant Survivor Study questionnaire. There was no significant difference in overall survival or disease-free survival between HLA-matched and -mismatched transplant recipients. The CHCs were less severe in HLA-mismatched recipients than in matched cohorts. Multivariate analysis identified that age over 40 years at transplantation and presence of chronic graft-versus-host disease were independent risk factors for CHCs, while anti-thymocyte globulin-containing conditioning regimens might be protective. However, HLA disparity was not crucial for either the survival rate or CHCs. In conclusion, HLA-mismatched family donor transplantation can achieve comparable therapeutic effects to HLA-identical sibling transplantation.

Less graft-versus-host disease after rabbit antithymocyte globulin conditioning in unrelated bone marrow transplantation for leukemia and myelodysplasia: comparison with matched related bone marrow transplantation

One of the major drawbacks for unrelated donor (UD) bone marrow transplantation (BMT) is graft-versus-host disease (GVHD). Despite results from randomized trials, antithymocyte globulin (ATG) is not routinely included for GVHD prophylaxis in UD BMT by many centers. One of ways to demonstrate the usefulness of rabbit ATG in UD BMT is to evaluate how its results approximate to those observed in matched related (MRD) BMT. Therefore, we compared the outcomes between UD BMT with rabbit ATG (Thymoglobulin) for GVHD prophylaxis (n = 25) and MRD BMT (n = 91) for leukemia and myelodysplasia. All but one patient received a myeloablative conditioning regimen. Grades II–IV acute GVHD were similar (39.5% vs. 36%, p = 0.83); however, MRD BMT recipients developed more moderate-severe chronic GVHD (36.5% vs. 8.6%, p = 0.01) and GVHD-related deaths (32.5% vs. 5.6%, p = 0.04). UD BMT independently protected against chronic GVHD (hazard ratio 0.23, p = 0.04). The 6-month transplant-related mortality, 1-year relapse incidence, and 5-year survival rates were similar between patients with non-advanced disease in the MRD and UD BMT groups, 13.8% vs. 16.6% (p = 0.50), 20.8% vs. 16.6% (p = 0.37), and 57% vs. 50% (p = 0.67), respectively. Stable full donor chimerism was equally achieved (71.3% vs. 71.4%, p = 1). Incorporation of rabbit ATG in UD BMT promotes less GVHD, without jeopardizing chimerism evolution, and may attain similar survival outcomes as MRD BMT for leukemia and myelodysplasia especially in patients without advanced disease.

A conditioning platform based on fludarabine, busulfan, and 2 days of rabbit antithymocyte globulin results in promising results in patients undergoing allogeneic transplantation from both matched and mismatched unrelated donor

Conditioning regimen including fludarabine, intravenous busulfan (Bx), and 5 mg/kg total dose of rabbit antithymocyte globulin (r-ATG) (FBx-ATG) results in low incidence of graft-versus-host disease (GVHD) and non-relapse mortality (NRM) after allogeneic hematopoietic stem cell transplantation (Allo-HSCT) from HLA-matched related or unrelated donors (MUD). However, whether this platform produces similar results in the setting of one mismatch unrelated donor (MMUD) Allo-HSCT is not known. We retrospectively analyzed patients aged less than 65 years who were diagnosed with hematological malignancies and received FBx-ATG regimen prior to Allo-HSCT from MUD (N = 74) or MMUD (N = 40). We compared outcome of MUD versus MMUD patients. There was no difference in the cumulative incidence of grades II-IV acute GVHD (MUD: 34% vs. MMUD: 35%, P = 0.918), but MMUD patients developed more grade III-IV acute GVHD (MUD: 5% vs. MMUD: 15%, P = 0.016). The cumulative incidences of overall chronic GVHD (MUD: 33% vs. MMUD: 22%, P = 0.088) and extensive chronic GVHD (MUD: 20% vs. MMUD: 19%, P = 0.594) were comparable. One-year NRM was similar in both groups (MUD: 16% vs. MMUD: 14%, P = 0.292); similarly, progression-free survival (MUD: 59% vs. MMUD: 55%, P = 0.476) and overall survival (MUD: 63% vs. MMUD: 61%, P = 0.762) were not different between both groups. With a median follow up of 24 months, 35 of 74 MUD patients (47%) and 19 of 40 MMUD patients (48%) were free of both disease progression and immunosuppressive treatment. We conclude that the FBx-ATG regimen results in low incidences of NRM and GVHD in both MUD and the MMUD recipients.

Antithymocyte globulin in reduced-intensity conditioning regimen allows a high disease-free survival exempt of long-term chronic graft-versus-host disease

Nonmyeloablative (NMA) regimens allow the use of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients considered unfit for standard myeloablative conditioning (MAC) regimens using high-dose alkylating agents with or without total body irradiation (TBI). Reduced-intensity conditioning (RIC) regimens, based on fludarabine (Flu), busulfan (Bu), and rabbit antithymocyte globulin (r-ATG), represent an intermediate alternative between NMA and MAC regimens. This platform was subsequently optimized by the introduction of i.v. Bu and the use of 5 mg/kg r-ATG, based on the hypothesis that these modifications would improve the safety of RIC allo-HSCT. Here we report a study conducted at our institution on 206 patients, median age 59 years, who underwent allo-HSCT after conditioning with Flu, 2 days of i.v. Bu, and 5 mg/kg r-ATG (FBx-ATG) between 2005 and 2012. The prevalence of grade III-IV acute graft-versus-host disease (GVHD) was 9%, and that of extensive chronic GVHD was 22%. Four-year nonrelapse mortality (NRM), relapse, and overall survival (OS) rates were 22%, 36%, and 54%, respectively. NRM tended to be influenced by comorbidities (hematopoietic cell transplantation-specific comorbidity index [HCT-CI] <3 versus HCT-CI ≥3: 18% versus 27%; P = .075), but not by age (<60 years, 20% versus ≥60 years, 25%; P = .142). Disease risk significantly influenced relapse (2 years: low, 8%, intermediate, 28%, high, 34%; very high, 63%; P = .017). Both disease risk (hazard ratio [95% confidence interval]: intermediate, 2.1 [0.8 to 5.2], P = .127; high, 3.4 [1.3 to 9.1], P = .013; very high, 4.0 [1.1 to 14], P = .029) and HCT-CI (hazard ratio [95% confidence interval]: HCT-CI ≥3, 1.7 (1.1 to 2.8), P = .018) influenced OS, but age and donor type did not. The FBx-ATG RIC regimen reported here is associated with low mortality and high long-term disease-free survival without persistent GVHD in both young and old patients. It represents a valuable platform for developing further post-transplantation strategies aimed at reducing the incidence of relapse, particularly in the setting of high-risk disease.

Influence of two different doses of antithymocyte globulin in patients with standard-risk disease following haploidentical transplantation: a randomized trial

To evaluate the effect of the different doses of antithymocyte globulin (ATG) on the incidence of acute GVHD among patients receiving hematopoietic SCT without ex vivo T-cell-depletion from haploidentical donors, 224 patients with standard-risk hematological malignancy were randomized in this study. One hundred and twelve patients received 6 mg/kg ATG, whereas the remaining patients received 10 mg/kg ATG. This study was registered at http://www.chictr.org as No. ChiCTR-TRC-11001761. The incidence of grade III-IV acute GVHD was higher in the ATG-6 group (16.1%, 95% confidence interval (CI), 9.1-23.1%) than in the ATG-10 group (4.5%, CI, 0.7-8.3%, P=0.005, 95% CI for the difference, -19.4% to -3.8%). EBV reactivation occurred more frequently in the ATG-10 group (25.3%, 17.1-33.5%) than in the ATG-6 group (9.6% (4.0-15.2%), P=0.001). The 1-year disease-free survival rates were 84.3% (77.3-91.3%) and 86.0% (79.2-92.8%) for the ATG-6 group and ATG-10 groups, respectively (P=0.88). In conclusion, although 6 mg/kg ATG applied in haploidentical transplantation decreased the risk of EBV reactivation compared with 10 mg/kg ATG, this treatment exposes patients to a higher risk for severe acute GVHD.

Long-term outcomes of antithymocyte globulin in patients with hematological malignancies undergoing myeloablative allogeneic hematopoietic cell transplantation: a systematic review and meta-analysis

Antithymocyte globulin (ATG) has shown efficacy in preventing acute GVHD (aGVHD) in allogeneic hematopoietic cell transplantation (allo-HCT), but its efficacy in chronic GVHD (cGVHD) and long-term outcomes remains controversial. We conducted a systematic review and meta-analysis to evaluate potential benefit and risk of prophylactic ATG use in myeloablative HCT. We searched Pubmed, EMBASE, Cochrane databases, and included 10 trials (two RCTs and eight retrospective) comparing ATG use vs. control with a total of 1859 patients. The median follow-ups were over two yr. Outcomes assessed included overall cGVHD, extensive cGVHD, overall survival (OS), disease-free survival, relapse, and causes of death. Our results showed ATG significantly decreased overall cGVHD (RR = 0.59; 95% CI: 0.53-0.66, p < 0.00001), extensive cGVHD (RR = 0.34; 95% CI: 0.25-0.47, p < 0.00001). Pooled results also showed ATG use was associated with a marginal increased risk of relapse (RR = 1.28; 95% CI: 1.01-1.63, p = 0.04), and a non-inferior OS (HR = 0.86; 95% CI: 0.74-1.01, p = 0.06). We conclude prophylactic use of ATG exerts a favorable effect in reducing cGVHD without survival impairment in a long term, although a higher relapse rate is a major threat.

Two days of antithymocyte globulin are associated with a reduced incidence of acute and chronic graft-versus-host disease in reduced-intensity conditioning transplantation for hematologic diseases

BACKGROUND

The optimal combination of fludarabine, busulfan, and antithymocyte globulin (ATG) for reduced-intensity conditioning (RIC) transplantation has not been established. ATG plays a pivotal role in the prevention of graft-versus-host disease (GvHD), but it is associated with a higher relapse rate and an elevated incidence of infections when high doses are used.

METHODS

The authors retrospectively compared 2 different doses of ATG combined with fludarabine and busulfan in 229 adult patients who underwent transplantation at their institution. ATG was administered over 1 day (FBA1) or over 2 days (FBA2) at a daily dose of 2.5 mg/kg.

RESULTS

There were 124 patients in the FBA2 cohort and 105 patients in the FBA2 cohorts. Patients in the FBA2 cohort were older and more frequently underwent transplantation from an unrelated donor; 93% of patients in the FBA2 cohort received intravenous busulfan versus only 5% in the FBA1 cohort. The incidence of grade 2 through 4 acute GvHD was 23% in the FBA2 cohort versus 42% in the FBA1 cohort (P = .002); the incidence of grade 3 through 4 acute GvHD was 10% versus 23%, respectively (P = .006); and the incidence of chronic GvHD was 35% versus 69%, respectively (P < .0001). The 2-year rates of overall survival, nonrelapse mortality, and relapse/progression for the FBA1 and FBA2 cohorts were 65% versus 67%, respectively (P = .99), 20% versus 19%, respectively (P = .61), and 30% versus 19%, respectively (P = .09). The results were confirmed in multivariate analysis.

CONCLUSIONS

The use of ATG at a dose of 5 mg/kg was correlated significantly with reduced incidence and severity of GvHD without impairing disease control. Taken together, the current results suggest that this conditioning represents a step forward in the optimization of RIC.

Anti-thymocyte globulin for conditioning in matched unrelated donor hematopoietic cell transplantation provides comparable outcomes to matched related donor recipients

Rabbit anti-thymocyte globulin (ATG) is used as prophylaxis against GVHD following allogeneic hematopoietic cell transplantation (HCT). At our institution, ATG is exclusively used in the conditioning of matched unrelated donor (URD) transplant recipients. A total of 50 URD HCT recipients who received ATG (ATG group) were retrospectively compared with 48 matched related donor (MRD) HCT recipients who did not receive ATG (no ATG group). There were no significant differences between the groups in rates of day 100 mortality, acute GVHD or relapse. Chronic GVHD incidence was significantly lower in the ATG group (P = 0.007). At a median follow-up of 36 months in the entire cohort, 50% patients are alive in the ATG group and 63% of the patients are alive in the no ATG group (P = 0.13). We conclude that the administration of ATG to patients undergoing URD HCT preserves the anti-leukemia benefit of the transplant, while reducing the risk of developing GVHD, resulting in OS rates that are comparable to MRD HCT recipients.

Favorable outcomes in patients with high donor-derived T cell count after in vivo T cell-depleted reduced-intensity allogeneic stem cell transplantation

Patients with hematologic malignancies were conditioned using a rabbit antithymocyte globulin-based reduced-intensity conditioning regimen for allogeneic stem cell transplantation. Donor-derived CD3(+) cell count (ddCD3), a product of CD3(+) cell chimerism and absolute CD3(+) cell count, when <110/μL at 8 weeks post-stem cell transplantation predicted a high risk of sustained mixed chimerism and relapse. Alternatively, patients with a higher ddCD3 developed graft-versus-host disease more frequently, and when partially chimeric, had higher rates of conversion to full donor chimerism after withdrawal of immunosuppression. Early data from our small cohort of patients indicate that ddCD3 at 8 weeks may be used to guide decisions regarding withdrawal of immunosuppression and administration of donor lymphocyte infusion in partially T cell-depleted reduced-intensity regimens.

The increase from 2.5 to 5 mg/kg of rabbit anti-thymocyte-globulin dose in reduced intensity conditioning reduces acute and chronic GVHD for patients with myeloid malignancies undergoing allo-SCT

We previously reported that reduced intensity conditioning (RIC) regimen with fludarabine, BU and 2.5 mg/kg of rabbit anti-thymocyte globulin (r-ATG) was effective but associated with a high rate of acute and chronic GVHD. Therefore, we increased the dose of r-ATG to 5 mg/kg. In this report, we analyzed 87 patients with AML or myelodysplastic syndrome (MDS) undergoing allo-SCT from an HLA-identical sibling donor from 2000 to 2010. RIC consisted of fludarabine, BU and r-ATG 2.5 mg/kg on 1 day (r-ATG1; n=53) or 2.5 mg/kg per day over 2 days (r-ATG2; n=22). Grade 2-4 acute GVHD incidence at day 100 was 30.2% and 8.8% in the r-ATG1 and r-ATG2 groups, respectively (P=0.038). Extensive chronic GVHD incidence was 60.4% and 12% in the r-ATG1 and r-ATG2 groups, respectively (P<0.001). The relapse incidences (RI) at 24 months were 18.9% and 28.5% in r-ATG1 and r-ATG2 groups, respectively (P=0.640). Overall and PFS were not different between the r-ATG1 and r-ATG2 groups. r-ATG dose at 5 mg/kg in the setting of RIC seems a good balance allowing GVHD prevention and antitumor effect with a remarkable reduction of GVHD incidence without an identical level of increased relapse rate.

Graft-vs-Host Disease following Allogeneic Hematopoietic Cell Transplantation

Background

Allogeneic hematopoietic cell transplantation (HCT) is a potentially curative therapy with proven efficacy in the management of hematologic malignancies. However, it is complicated by the syndromes of acute and chronic graft-vs-host disease (GVHD).

Methods

A narrative review is provided to summarize major biologic insights into the pathogenesis of these immune-mediated disorders, as well as advances in diagnosis, classification, prevention, management, and allied supportive care with the aim of providing essential understanding for clinicians with or without subspecialty experience in the field of blood and marrow transplantation.

Results

Major scientific advances have contributed to enhanced understanding of the pathogenesis of these disorders, and clinical investigation has provided more effective preventive and therapeutic strategies for GVHD. However, since acute GVHD and chronic GVHD remain leading sources of transplantation-related morbidity and mortality, ongoing investigation is needed to develop new approaches to addressing these syndromes.

Conclusions

The major challenge for future investigation will be to capitalize on biologic insights in order to develop novel strategies for the prevention and therapy of acute and chronic GVHD that will address the current shortcomings in existing therapeutic approaches.

ATG prevents severe acute graft-versus-host disease in mismatched unrelated donor hematopoietic cell transplantation

Severe acute graft-versus-host disease (aGVHD) remains a major source of morbidity and mortality following mismatched unrelated donor hematopoietic cell transplantation (HCT). Through a retrospective analysis, we investigated the efficacy of GVHD prophylaxis with rabbit anti-thymocyte globulin (ATG) 7.5 mg/kg (1 mg/kg given on day -3, then 3.25 mg/kg/day on days -2 and -1 before stem cell infusion) followed by standard tacrolimus plus methotrexate in a consecutive series of 45 HLA partially matched unrelated donor HCT recipients. The cumulative incidence of grade III-IV aGVHD was 11% by 100 days (95% confidence interval [CI] 5%-25%). Moderate to severe chronic GVHD (per NIH consensus criteria) was 19% (95% CI 10%-36%) at 1 year, and 28% (95% CI 16%-48%) at 2 years. With a median follow-up time for surviving patients of 12 months (range: 5-39 months), overall survival was 55% (95% CI 39%-71%) at 1 year, and 45% (95% CI 27%-63%) at 2 years. Nonrelapse mortality was 11% (95% CI 5%-25%) by 100 days post-HCT, 26% (95% CI 16%-44%) by 1 year, and 30% (95% CI 18%-50%) by 2 years. The cumulative incidence of primary disease relapse was 23% (95% CI 13%-41%) at 1 year, and 33% (95% CI 20%-56%) by 2 years after HCT. Cytomegalovirus (CMV) infection or reactivation varied according to recipient and donor CMV serostatus. Epstein-Barr Virus (EBV) reactivation occurred in 54% (95% CI 40%-71%) of patients. Preemptive rituximab therapy was administered for EBV reactivation, however, posttransplant lymphoproliferative disorder was diagnosed in 5 (11%) cases, and was fatal in 1. A regimen of ATG 7.5 mg/kg total ending on day -1 effectively decreased the occurrence of grade III-IV aGVHD and severe chronic GVHD.

Rabbit antithymocyte globulin (thymoglobulin): 25 years and new frontiers in solid organ transplantation and haematology

The more than 25 years of clinical experience with rabbit antithymocyte globulin (rATG), specifically Thymoglobulin, has transformed immunosuppression in solid organ transplantation and haematology. The utility of rATG has evolved from the treatment of allograft rejection and graft-versus-host disease to the prevention of various complications that limit the success of solid organ and stem cell transplantation. Today, rATG is being successfully incorporated into novel therapeutic regimens that seek to reduce overall toxicity and improve long-term outcomes. Clinical trials have demonstrated the efficacy and safety of rATG in recipients of various types of solid organ allografts, recipients of allogeneic stem cell transplants who are conditioned with both conventional and nonconventional regimens, and patients with aplastic anaemia. Over time, clinicians have learnt how to better balance the benefits and risks associated with rATG. Advances in the understanding of the multifaceted mechanism of action will guide research into new therapeutic areas and future applications.

Improved nonrelapse mortality and infection rate with lower dose of antithymocyte globulin in patients undergoing reduced-intensity conditioning allogeneic transplantation for hematologic malignancies

We sought to reduce the risk of infectious complications and nonrelapse mortality (NRM) associated with the use of antithymocyte globulin (ATG) without compromising control of acute graft-versus-host disease (aGVHD) in patients undergoing reduced-intensity conditioning (RIC) transplantation. As part of an ongoing quality improvement effort, we lowered the dose of rabbit ATG from 7.5 mg/kg of ATG (R-ATG) (n = 39) to 6.0 mg/kg of ATG (r-ATG) (n = 33) in association with fludarabine (Flu) and busulfan (BU) RIC transplantation and then monitored patients for adverse events, relapse, and survival. Of the 72 mostly high risk (82%) patients studied, 89% received unrelated donor allografts, 25% of which were HLA-mismatched. No differences in posttransplantation full donor-cell chimerism rates were observed between the 2 ATG-dose groups (P > .05). When R-ATG versus r-ATG patients were compared, we observed no significant difference in the cumulative incidence of grade II-IV aGVHD (32% versus 27%; P = .73) or grade III-IV aGVHD (23% versus 11%; P = .28). However, the r-ATG group had significantly less cytomegalovirus (CMV) reactivation (64% versus 30%; P = .005) and bacterial infections (56% versus 18%; P = .001), a better 1-year cumulative incidence of NRM (18% versus 3%; P = .03), and a trend for better 1-year overall survival (OS) (64% versus 84%; P = .07) compared to R-ATG patients. A seemingly modest reduction in the dose of rabbit ATG did not compromise control of aGVHD or achievement of donor chimerism, but led to a significant decrease in the risk of serious infections and NRM in high-risk RIC allograft recipients.

Outcomes following HSCT using fludarabine, busulfan, and thymoglobulin: a matched comparison to allogeneic transplants conditioned with busulfan and cyclophosphamide

We have reported a lower incidence of acute graft-versus-host disease (aGVHD) with a novel conditioning regimen using low-dose rabbit antithymocyte globulin (ATG; Thymoglobulin [TG]) with fludarabine and intravenous busulfan (FluBuTG). To assess further this single-center experience, we performed a retrospective matched-pair analysis comparing outcomes of adult patients transplanted using the FluBuTG conditioning regimen with matched controls from patients reported to the CIBMTR receiving a first allogeneic hematopoietic stem cell transplant (HCT) after standard oral busulfan and cyclophosphamide (BuCy). One hundred twenty cases and 215 matched controls were available for comparison. Patients receiving FluBuTG had significantly less treatment related mortality (TRM; 12% versus 34%, P < .001) and grades II-IV aGVHD (15% versus 34%, P < .001) compared to BuCy patients. The risk of relapse was higher in the FluBuTG patients (42% versus 20%, P < .001). The risks of chronic GVHD (cGVHD) and disease free survival (DFS) were similar in the cases and controls. These results suggest that the novel regimen FluBuTG decreases the risk of aGVHD and TRM after HLA-identical sibling HSCT, but is associated with an increased risk of relapse, resulting in similar DFS. Whether these conditioning regimens may be more suitable for specific patient populations based on relapse risk requires testing in prospective randomized trials.

Transplantation from matched siblings using once-daily intravenous busulfan/fludarabine with thymoglobulin: a myeloablative regimen with low nonrelapse mortality in all but older patients with high-risk disease

Two hundred patients received hematopoietic stem cell transplantation (HSCT) from matched sibling donors (MSD) after myeloablative conditioning including fludarabine (Flu) and once-daily intravenous busulfan (Bu). Thymoglobulin (TG) was added to methotexate (MTX) and cyclosporine (CsA) as graft-versus-host disease (GVHD) prophylaxis. For low-risk (acute leukemia CR1/CR2, CML CP1) patients projected 5-year nonrelapse mortality (NRM) and overall survival (OS) were 4% and 76% for those <or=45 years old (n = 54) and 6% and 83% for those >45 (n = 31). For high-risk (HR) patients NRM was 6% versus 27% (18% at 1 year) (P = .04) and OS 64% versus 37% (P = .47) in younger (n = 40) and older (n = 75) patients, respectively. To correct for imbalance in HR diagnoses each of 17 younger HR patients were matched with 2 older HR (OHR) patients by diagnosis and details of stage, and thereafter for other risk factors. For the younger HR and OHR patients, respectively, OS was 70% versus 37% (P = .02) and NRM 0 versus 34% (P = .02). When outcomes of OHR patients were compared with the other 3 groups combined NRM was 27% versus 5%, respectively (P = .002). Incidence of acute graft-versus-host disease (aGVHD) grade II-IV, aGVHD grade III-IV, and chronic GVHD (cGVHD) was 23% versus 10% (P = .02), 4% versus 2% (P = ns), and 66% versus 41% (P = .001), respectively. Nine of 14 nonrelapse deaths in the OHR group were related to GVHD or its treatment compared with 3 of 6 in all others (P value for GVHD related death = .01). Multivariate analysis of OS and DFS correcting for potentially confounding pretransplant factors identified only the OHR patients as having significantly increased risk (relative risk [RR] 3.32, confidence interval [CI] 1.71-6.47, P < .0001, and RR 3.32, CI 1.71-6.43, P < .0001, respectively). The effect of age on NRM is only apparent in HR patients, and is not explained by heterogeneity in diagnoses. Older HR patients experience more GVHD and more GVHD-related death than others, but NRM is no higher than reported with many nonmyeloablative regimens.

Allogeneic stem cell transplantation in children with leukemia using human leukocyte antigen-mismatched unrelated donors

Allogeneic HSCT is a curative treatment, when chemotherapy fails, for certain malignant diseases. In Europe, only 15% of the indicated children have an HLA-matched sibling available; in 65-70% of others, HLA allele-matched (9-10/10) UDs can be identified. For the rest, it is necessary to identify other alternative donors (HLA-mismatched family or unrelated cord blood). We present our data of HSCT using HLA partially allele-mismatched (7-8/10) UDs in 24 children with leukemia. Uniform GvHD prophylaxis was used (rATG, CsA and MTX). Acute GvHD grade II was diagnosed in 70.8% of the patients and grade III-IV in 12.5%. Overall incidence of chronic GvHD was 38.7% (extensive in 30%). The probability of EFS was 60.3% (95% CI 35.5-78.1) and OS was 74.9 (95% CI 49.1-88.9). No difference in survival between PBSC and BM recipients was observed. TRM at day + 100 was 4%, and overall was 12.5%. We conclude that used combination of drugs for GvHD prophylaxis is efficient even for patients transplanted with grafts from a HLA-mismatched UDs. It enables stable engraftment, good control of GvHD, full reconstitution of immunity, and is not connected with unacceptable transplant-related mortality.

Risk factors for acute graft-versus-host disease grades II-IV after reduced intensity conditioning allogeneic stem cell transplantation with unrelated donors: a single centre study

We analysed factors associated with moderate to severe acute GVHD in 111 patients treated with fludarabin-based reduced intensity conditioning (RIC) and allogeneic haematopoietic stem cell transplantation (HSCT). Most patients had a haematological malignancy. Donors were 97 HLA-A, -B and -DRbeta1 identical unrelated and 14 HLA-A, -B or -DRbeta1 allele mismatched unrelated donors. In the univariate analysis, we found ten factors associated with acute GVHD. These were diagnosis (P=0.06), GVHD prophylaxis with combinations other than CsA+MTX (P=0.006), graft nucleated (P<0.001) and CD34 (P<0.001) cell-dose, bidirectional ABO mismatch (P=0.001), conditioning (P=0.002), hospital vs home-care (P=0.06), ATG dose (P<0.001), donor herpes virus serology (P=0.07) and an immunized female donor to male recipient (P=0.05). In the multivariate analysis, three factors remained significant: a high CD34 cell dose (P<0.001), low dose (4 mg/kg) ATG (P<0.001), and an immunized female donor to male recipient (P<0.01). Patients receiving a CD34 cell dose > or =17.0 x 10(6) per kg had a higher incidence of GVHD, 53.7%, compared to 22.3% in patients receiving a lower dose (P=0.002). In patients without any of these risk factors (n=70), the incidence of acute GVHD was 14.1%, while it was 38.0 and 85.0% in patients with one (n=29) or two (n=10) risk factors (P<0.001). We concluded that risk factors for acute GVHD using RIC are similar as using myeloablative conditioning.

Long-term outcome of unrelated donor transplantation for AML using myeloablative conditioning incorporating pretransplant Alemtuzumab

The outcome of 55 patients who underwent matched unrelated donor (MUD) transplantation for acute myelogenous leukemia (AML) following a conditioning regimen of cyclophosphamide and total-body irradiation (TBI) with the addition of Alemtuzumab 10 mg/kg/day on days -5 to -1 is described. All patients received graft-versus-host disease (GVHD) prophylaxis with cyclosporine as well as 3 doses of posttransplant methotrexate. Forty-one patients were transplanted in complete remission (CR) (20 in CR1, 20 in CR2, and 1 in CR3), and 14 were not in remission at the time of transplantation as they were refractory to chemotherapy either at induction or at relapse. The group consisted of adult patients with a median age of 37 years. Thirty-five patients were fully matched at HLA-A, -B, -C, and -DRB1. All patients engrafted and there were no cases of graft rejection. Grade II-IV acute GVHD occurred in only 2 patients. Chronic GVHD developed in 30% of patients but was extensive in only 3 cases. The predicted TRM was 11% at day 100 and 26% at 1 year. In multivariate analysis the receipt of an HLA mismatched transplant was associated with a higher transplant-related mortality (TRM) (55% versus 15%). Twelve of the 14 transplant-related deaths were due to infection. The 5-year cumulative incidence of relapse was 36% for the whole group and 28% for patients in CR at transplantation. The 5-year cumulative survival for the whole group was 38% and was 49% for those in remission at transplantation. Seven of the 12 patients transplanted in CR1 with adverse risk cytogenetics remain alive and in remission, and the predicted 5-year overall survival (OS) for this group is 50%. These results support the use of Alemtuzumab for unrelated donor hematopoietic stem cell transplant (HSCT) for poor risk AML in CR1 and for relapsed AML in CR2. The addition of Alemtuzumab is highly effective in preventing both rejection and severe acute and extensive chronic GVHD without an increased relapse risk.

Low mortality of children undergoing hematopoietic stem cell transplantation from 7 to 8/10 human leukocyte antigen allele-matched unrelated donors with the use of antithymocyte globulin

Human leukocyte antigen (HLA)-matched sibling donor hematopoietic stem cell transplantation (HSCT) is available for only approximately 30% patients needing HSCT. Use of alternative donors is associated with a high incidence and severity of graft-versus-host disease (GVHD). Here we report our experience with GVHD prophylaxis using pre-transplant rabbit antithymocyte globulin (rATG), in addition to post transplant cyclosporin A and methotrexate. Seventy-five children received unmanipulated grafts from 7 to 10/10 HLA allele-matched unrelated donors. Median follow-up was 25 months (range, 6-65 months). Only 2/75 patients (2.5%) developed acute GVHD grades III-IV, and 17/75 (25%) developed extensive chronic GVHD. Overall survival was 79%. It was similar in patients receiving grafts from 7 or 8/10 to 9 or 10/10 allele-matched donors, and similar in patients receiving peripheral blood stem cells and marrow. Six (11%) patients died owing to relapse, and 10 (13%) due to transplant-related complications. The addition of rATG appears to result in a low incidence of severe GVHD and overall mortality.

Thymoglobulin prevents chronic graft-versus-host disease, chronic lung dysfunction, and late transplant-related mortality: long-term follow-up of a randomized trial in patients undergoing unrelated donor transplantation

This is an update of a randomized study on antithymocyte globulin (ATG; Thymoglobulin) before transplantation in patients undergoing unmanipulated marrow transplantation from unrelated donors. The median follow-up for surviving patients is 5.7 years. At last follow-up, chronic graft-versus-host disease (GVHD) was scored in 60% of non-ATG and in 37% of ATG patients (P=.05), and extensive chronic GVHD was present in 41% and 15%, respectively (P=.01). Chronic lung dysfunction was diagnosed in 51% versus 19% of patients (P=.005). Forced vital capacity decreased significantly with time in non-ATG patients (P=.005), but not in patients who received ATG (P=.30). The proportion of patients with Karnofsky scores of >or=90% at 4 years was 57% versus 89% in non-ATG versus ATG patients (P=.03). The actuarial 6-year survival for all patients randomized was 31% versus 44% (non-ATG versus ATG; P=.80). The cumulative incidence of transplant-related mortality was 51% versus 41% (P=.70) and of relapse was 32% versus 40% (P=.90). For patients who survived 1 year, transplant-related mortality was 25% versus 3% (P=.03), and actuarial survival was 58% versus 85% (P=.09). In conclusion, the addition of ATG to cyclosporine/methotrexate provides significant protection against extensive chronic GVHD and chronic lung dysfunction, reduces late transplant mortality, and improves quality of life in patients undergoing unrelated donor transplantation.

Conditioning including antithymocyte globulin followed by unmanipulated HLA-mismatched/haploidentical blood and marrow transplantation can achieve comparable outcomes with HLA-identical sibling transplantation

The outcomes of 293 patients with leukemia undergoing HLA-identical sibling (n = 158) or related HLA-mismatched (n = 135) hematopoietic cell transplantation (HCT) performed during the same time period were compared. Patients received BUCY2 in HLA-identical sibling HCT or BUCY2 + ATG in mismatched HCT as conditioning regimens, followed by unmanipulated marrow and/or peripheral blood (PB) transplantation. All patients achieved full engraftment. The cumulative incidences of grades II to IV acute graft-versus-host disease (aGVHD) in the matched and mismatched cohorts were 32% (CI, 25%-39%) versus 40% (CI, 32%-48%, P = .13), respectively, with the relative risk (RR) = 0.64 (95% CI, 0.43-0.94), P = .02. The incidence of chronic GVHD did not differ significantly between the cohorts (P = .97). Two-year incidences of treatment-related mortality and relapse for matched versus mismatched were 14% (range, 9%-20%) versus 22% (range, 15%-29%) with P = .10 and 13% (range, 8%-19%) versus 18% (range, 10%-27%) with P = .40, respectively. Two-year adjusted leukemia-free survival (LFS) and overall survival were 71% (range, 63%-78%) versus 64% (range, 54%-73%) with P = .27 and 72% (range, 64%-79%) versus 71% (range, 62%-77%) with P = .72, respectively. Multivariate analyses showed that only advanced disease stage and a diagnosis of acute leukemia had increased risk of relapse, treatment failure, and overall mortality. In summary, HCT performed with related HLA-mismatched donors is a feasible approach with acceptable outcomes.

Antithymocyte globulin for prevention of graft-versus-host disease

PURPOSE OF REVIEW

This review aims to discuss current clinical trial using antithymocyte globulin in the context of hematopoietic stem cell transplantation. Published papers, as well as abstracts from European and American meetings, have been used together with original data.

RECENT FINDINGS

The review shows that antithymocyte globulin is used frequently in Europe in the setting of unrelated or family mismatched donor transplants. This may not be the case for American centers, reluctant to introduce antithymocyte globulin possibly due to known side effects such as prolonged immune deficiency and increased incidence of infections, including life threatening Epstein-Barr virus-associated lymphoproliferative disorders. Results from few randomized trials show that antithymocyte globulin reduces acute and chronic graft-versus-host disease, and this is in keeping with results from retrospective analysis on large number of patients.

SUMMARY

Several issues remain open, such as optimal dose, optimal timing with respect to infusion of stem cells and whether the commercially available agents have comparable effects. Prospective trials are needed to answer these important questions.

Antilymphocyte/thymocyte globulin for graft versus host disease prophylaxis: efficacy and side effects

Antilymphocyte/thymocyte globulins (ALGs/ATGs) have now been used for over 30 years in the setting of hemopoietic stem cell transplants (HSCT), with the aim of preventing graft-versus-host disease (GvHD). This is true especially for transplants from alternative donors. In this review, we will be discussing available published and unpublished data on the advantages and disadvantages of using ALG/ATG before or after an allogeneic HSCT. These studies show that ALG/ATG significantly reduce the incidence and severity of acute and chronic GvHD. Unfortunately, they also show that immune deficiency is a more prolonged and infectious complication more frequent in patients receiving ALG/ATG, suggesting the importance of aggressive monitoring of viral and fungal infections. In particular, the emerging problem of Epstein-Barr virus (EBV) infections and EBV-related lymphoproliferative disorders will be discussed, together with the use of pre-emptive therapy with rituximab. I personally believe ALG/ATG has an important role in allogeneic HSCT, especially today with the increasing use of peripheral blood transplants and the consequent high risk of chronic GvHD. ALG/ATG should be used with caution, and the negative consequences must be understood and possibly prevented.