Dose-dependent effects of in vivo antithymocyte globulin during conditioning for allogeneic bone marrow transplantation from unrelated donors in patients with chronic phase CML

Impact of Anti-T-lymphocyte globulin dosing on GVHD and Immune reconstitution in matched unrelated myeloablative peripheral blood stem cell transplantation

Data on the influence of different Anti-lymphocyte globulin (ATLG) doses on graft versus host disease (GVHD) incidence and immune reconstitution in matched unrelated (MUD) allogeneic Stem cell transplantation (allo-SCT) is limited. This retrospective study conducted at the University Medical-Center Hamburg compares GVHD and Immune reconstitution after myeloablative MUD (HLA 10/10) PBSC allogeneic stem cell transplant between 30 mg/Kg (n = 73) and 60 mg/Kg (n = 216) ATLG. Detailed phenotypes of T, B natural killer (NK), natural killer T (NKT) cells were analyzed by multicolor flow at day 30, 100, and 180 posttransplant. Neutrophil and platelet engraftments were significantly delayed in the 60 mg/kg group with a higher Cumulative incidence of Infections (67% vs 75% p = 0.049) and EBV (21% vs 41% p = 0.049) reactivation at day 100 in this group. In the 30 mg/kg group, we observed a faster reconstitution of naïve-B cells (p < 0.0001) and γδ T cells (p = 0.045) at day+30 and a faster naïve helper T-cell (p = 0.046), NK-cells (p = 0.035), and naïve B-cell reconstitution (p = 0.009) at day+180. There were no significant differences in aGVHD, cGVHD, NRM, RI, PFS, and OS between the groups. The choice of ATLG dose has significant impact on IR but not on GVHD after MUD-allo-SCT. Higher doses are associated with delayed engraftment and increased infections.

Differential Elimination of Anti-Thymocyte Globulin of Fresenius and Genzyme Impacts T-Cell Reconstitution After Hematopoietic Stem Cell Transplantation

Anti-thymocyte globulin (ATG) is a lymphocyte depleting agent applied in hematopoietic stem cell transplantation (HSCT) to prevent rejection and Graft-vs.-Host Disease (GvHD). In this study, we compared two rabbit ATG products, ATG-Genzyme (ATG-GENZ), and ATG-Fresenius (ATG-FRES), with respect to dosing, clearance of the active lymphocyte binding component, post-HSCT immune reconstitution and clinical outcome. Fifty-eigth pediatric acute leukemia patients (n = 42 ATG-GENZ, n = 16 ATG-FRES), who received a non-depleted bone marrow or peripheral blood stem cell graft from an unrelated donor were included. ATG-GENZ was given at a dosage of 6-10 mg/kg; ATG-FRES at 45-60 mg/kg. The active component of ATG from both products was cleared at different rates. Within the ATG-FRES dose range no differences were found in clearance of active ATG or T-cell re-appearance. However, the high dosage of ATG-GENZ (10 mg/kg), in contrast to the low dosage (6-8 mg/kg), correlated with prolonged persistence of active ATG and delayed T-cell reconstitution. Occurrence of serious acute GvHD (grade III-IV) was highest in the ATG-GENZ-low dosage group. These results imply that dosing of ATG-GENZ is more critical than dosing of ATG-FRES due to the difference in clearance of active ATG. This should be taken into account when designing clinical protocols.

A New Enzyme-Linked Immunosorbent Assay for a Total Anti-T Lymphocyte Globulin Determination: Development, Analytical Validation, and Clinical Applications

BACKGROUND

Anti-T lymphocyte globulin (ATLG) modulates the alloreactivity of T lymphocytes, reducing the risk of immunological posttransplant complications, in particular rejection and graft-versus-host disease, after allogeneic hematopoietic stem cell transplantation (HSCT). We developed and validated a new enzyme-linked immunosorbent assay (ELISA) method to measure serum levels of total ATLG and evaluate the pharmacokinetics (PK) of the drug in children with β-Thalassemia, receiving allogeneic HSCT.

METHODS

Diluted serum samples were incubated with Goat-anti-Rabbit IgG antibody coated on a microtiter plate and then, with Goat-anti-Human IgG labeled with horseradish peroxidase. After incubation and washings, substrate solution was added and absorbance was read at 492 nm. ATLG concentrations in samples were determined by interpolation from a standard curve (range: 200-0.095 ng/mL), prepared by diluting a known amount of ATLG in phosphate-buffered saline (PBS). Low, medium, and high-quality control concentrations were 1.56, 6.25, and 25 ng/mL, respectively. This method was developed and validated within the acceptance criteria in compliance with the Guidelines for a biological method validation: the sensitivity of the method was 0.095 ng/mL. We analyzed serum samples from 14 children with β-Thalassemia who received ATLG (Grafalon) at a dose of 10 mg/kg administered as intravenous (IV) infusion on days -5, -4, and -3 before HSCT (day 0). Blood sampling for PK evaluation was performed on days -5, -4, and -3 before and after drug infusion; and then from day -2 to +56.

RESULTS

The median total ATLG levels pre-IVand post-IV were 0 and 118 mcg/mL on day -5; 85.9 and 199.2 mcg/mL on day -4; 153 and 270.9 mcg/mL on day -3, respectively. The median PK values of CL was 0.0029 (range: 0.0028-0.0057) L·kg·d, Vd was 0.088 (range: 0.025-0.448) L/kg and t1/2 was 20.2 (range: 5.8-50.2) days.

CONCLUSIONS

These data suggest that given the marked interindividual variability of total ATLG disposition, the development of a validated ELISA method and the possibility to measure PK parameters in paediatric populations are essential steps to optimize drug therapeutic regimens.

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.

Unmanipulated Haploidentical Reduced-Intensity Stem Cell Transplantation Using Fludarabine, Busulfan, Low-Dose Antithymocyte Globulin, and Steroids for Patients in Non-Complete Remission or at High Risk of Relapse: A Prospective Multicenter Phase I/II Study in Japan

This prospective, multicenter phase I/II study of unmanipulated HLA-haploidentical reduced-intensity stem cell transplantation using a low dose of anti-T lymphocyte globulin (ATG) and steroid was conducted in 5 institutions in Japan. Thirty-four patients with hematologic malignancies who were in an advanced stage or at a high risk of relapse at the time of transplantation were enrolled. Among them, 7 patients underwent transplantation as a second transplantation because of relapse after the previous allogeneic stem cell transplantation. The conditioning regimen consisted of fludarabine, busulfan, and ATG (Fresenius, 8 mg/kg), and graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus and methylprednisolone (1 mg/kg). All patients except 1 (97.1%) achieved donor-type engraftment. Rapid hematopoietic engraftment was achieved, with neutrophils > .5 × 10(9)/L on day 11 and platelets > 20 × 10(9)/L on day 17.5. Treatment was started for ≥grade I GVHD, and the cumulative incidences of acute grade I and grade II to IV GVHD were 27.5% and 30.7%, respectively. The incidence of chronic GVHD (extensive type) was 20%. Fourteen patients (41.2%) had a relapse. The cumulative incidence of transplantation-related mortality at 1 year after transplantation was 26.5%. The survival rate at day 100 was 88.2%. The survival rates at 1 year for patients with complete remission (CR)/chronic phase (n = 8) and non-CR (n = 26) status before transplantation were 62.5% and 42.3%, respectively. In the multivariate analysis, non-CR status before transplantation was the only factor significant prognostic factor of increased relapse (P = .0424), which tended to be associated with a lower survival rate (P = .0524). This transplantation protocol is safe and feasible, if a suitable donor is not available in a timely manner. As the main cause of death was relapse and not GVHD, more intensified conditioning or attenuation of GVHD prophylaxis and/or donor lymphocyte infusion may be desirable for patients with non-CR status.

Outcomes of peripheral blood stem cell transplantation patients from HLA-mismatched unrelated donor with antithymocyte globulin (ATG)-Thymoglobulin versus ATG-Fresenius: a single-center study

Although antithymocyte globulin (ATG) had been widely used in hematopoietic stem cell transplantation from unrelated donor due to its ability to prevent acute and chronic graft-versus-host disease (GVHD), the comparative efficacy and safety of ATG-Thymoglobulin (ATG-T) and ATG-Fresenius (ATG-F) in patients undergoing HLA-mismatched allogeneic peripheral blood stem cell transplantation from unrelated donors (UR-PBSCT) has not been evaluated. Retrospective analysis of patients who underwent HLA-mismatched UR-PBSCT between January 2003 and December 2013 and received pre-transplant ATG-T at a total dose of 10 mg/kg or ATG-F at a total dose of 20 mg/kg was performed. Patients who received ATG-T (n = 23) or ATG-F (n = 28) had similar baseline demographic, disease, and transplant characteristics. There were no significant between-groups differences in the probability of acute GVHD (P = 0.721) and chronic GVHD (P = 0.439). ATG-F was associated with nonsignificant trends toward higher disease-free survival at 3-year follow-up compared with ATG-T (45.7 ± 11.1 vs 61.3 ± 9.7 %, respectively, P = 0.07). A significantly greater proportion of ATG-T patients experienced high fever than ATG-F patients (P < 0.01) during ATG infusion. There was no difference in the rate of infection between the two treatment groups. There were less adverse effects comparing ATG-F with ATG-T. ATG-T at a total dose of 10 mg/kg and ATG-F at a total dose of 20 mg/kg had a similar clinical outcome in the setting of HLA-mismatched UR-PBSCT.

Comparison of different rabbit ATG preparation effects on early lymphocyte subset recovery after allogeneic HSCT and its association with EBV-mediated PTLD

PURPOSE

Rabbit antithymocyte globulin (ATG) is commonly used before allogeneic hematopoietic stem cell transplantation (allo-HSCT) to prevent graft-versus-host disease. Studies comparing the effect of different ATG preparations and dosages on immune reconstitution and risk for Epstein-Barr virus (EBV)-mediated post-transplant lymphoproliferative disorder (PTLD) are rare.

METHODS

In this retrospective study, we determined T and B cell subsets by flow cytometry after allo-HSCT in children, who received ATG-Genzyme (ATG-G, n = 15), ATG-Fresenius (ATG-F, n = 25) or no-ATG treatment (n = 19). Additionally, PCR-quantified EBV-genome copy counts were correlated with incidence of PTLD.

RESULTS

We could confirm a dose-dependent impairment of CD8(+) and CD4(+) T cell regeneration by ATG-G, including naïve and memory CD4(+) T cells. No differences were seen between the currently applied dosages of 5-10 mg/kg ATG-G and 20-60 mg/kg ATG-F. Significantly delayed T cell subset reconstitution was determined only at high dosages of 20-60 mg/kg ATG-G compared to ATG-F. B cell reconstitution was comparably impaired in ATG-G- and ATG-F-treated patients. Although the incidence of EBV reactivation was similar in both ATG groups, EBV copy counts of >10(4) copies/10(5) peripheral blood mononuclear cells and the occurrence of PTLD were only found in ATG-G-treated patients.

CONCLUSIONS

We conclude that high, but importantly not currently applied low dosages of ATG-G, impair thymic T cell regeneration and memory T cell immunity to a greater extent than ATG-F in pediatric patients. In addition, our results suggest an increased risk for EBV-PTLD when treated with ATG-G. Prospective studies are warranted to compare different ATG preparations with regard to the immune reconstitution and EBV-PTLD.

Rabbit anti-T-lymphocyte globulin (ATG) persists with differential reactivity in patients' sera after full hematopoetic regeneration from allogeneic stem cell transplantation

BACKGROUND

Rabbit polyclonal anti-T-lymphocyte Globulin (ATG-F®, Fresenius) is widely used for GvHD prophylaxis in allogeneic stem cell transplantation (SCT). ATG has a wide epitope spectrum and has been shown to react with all compartments of peripheral blood mononuclear cells (PBMNCs). ATG induces apoptosis in all cellular compartments. In this study we investigated the binding of ATG in sera from ten patients treated with rabbit ATG to PBMNCs and subcellular compartments after full hematopoetic regeneration on day 21 post SCT.

METHODS

Sera from ten patients treated with unrelated donor allogeneic SCT for hematologic malignancy were collected after full hematopoetic regeneration on day 21 post SCT and incubated with healthy donor PBMNCs. Rabbit ATG on PBMNCs was detected by staining with fluorochrome labeled anti-rabbit IgG antibody. PBMNC compartments were investigated by counterstaining with lineage markers CD4, CD8, CD14 CD20 and CD56. Positive control was the fresh ATG preparation.

RESULTS

We found that patient's' sera retained activity towards PBMNCs in all patients, yet at reduced intensity. When cell compartments were analyzed we found a differential pattern of ATG reactivity within sera. The mean percentage of total cells reacting with serum ATG from ten patients compared to fresh ATG (100%) was 44% of CD4 positive and 58% of CD8 positive T-lymphocytes, 41% of CD56 positive NK-cells, 83% of CD20 positive B-lymphocytes and 98% of CD14 positive monocytes. However, inter-individual variations were high with a wide spread around the mean especially for T-lymphocytes.

CONCLUSION

We conclude that upon PBMNC regeneration following SCT and immunosuppressive treatment with ATG subpopulations of T-lymphocytes (CD4, CD8) and NK cells (CD56) are selected that lose epitopes recognized by ATG while B-lymphocytes (CD20) and monocytes (CD14) maintain a homogeneity with respect to epitopes recognized by ATG. This may be due to loss of idiotypes reacting with subpopulations of high frequency and turnover. Further studies should investigate the subphenotype of these populations and functional effects of extremely high or low reactivity with one or more compartments in some patients on GvHD and disease outcome.

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.

Molecular monitoring of BCR-ABL transcripts after allogeneic stem cell transplantation for chronic myeloid leukemia

The monitoring of minimal residual disease (MRD) through low sensitivity real-time (RT) polymerase chain reaction (PCR) analysis of BCR-ABL transcripts allows early detection of chronic myeloid leukemia (CML) relapse after allogeneic hematopoietic stem cell transplantation (HSCT). The introduction of more sensitive techniques, such as RT quantitative (Q)-PCR, may lead to an overestimation of the risk of CML relapse. In this study, we reviewed the results of peripheral blood RT Q-PCR in CML patients who underwent allogeneic HSCT from 1983 to 2007. In our laboratory, RT Q-PCR analysis was routinely performed since 2002. Eighty-seven of 189 patients had available RT Q-PCR data; 63 patients had at least 3 RT Q-PCR analyses assessable. Fifty-two of 63 patients (83%) had, at least once, detectable transcript levels, but with an BCR-ABL/ABL ratio <.1% defined as <MR3 (molecular remission <0,1%), whereas 11 (17%) had persistent undetectable BCR-ABL transcripts. Six of 52 patients with <MR3 relapsed, defined as BCR-ABL transcript numbers >.1% confirmed by the finding of Ph+ cells in bone marrow. No patients with persistent undetectable transcripts relapsed (P = .19). Relapse did not correlate with the number of occurrences of <MR3 or with the time to the first <MR3 result. Finally, of 46 patients with detectable transcripts who did not relapse, 35 had undetectable transcripts at last contact. RT Q-PCR analysis had low specificity (19%) and low positive predictive value (12%) in predicting relapse of CML patients after allogeneic HSCT. Our data suggest that detection of low BCR-ABL transcript levels by RT Q-PCR analysis has a poor accuracy in defining the risk of CML relapse and should not be considered as the unique indication to treatment. Fluctuation of BCR-ABL transcripts levels is common as late as ≥10 years posttransplantation, possibly suggesting the long-term persistence of CML stem cells.

Genetic variation in donor CTLA-4 regulatory region is a strong predictor of outcome after allogeneic hematopoietic cell transplantation for hematologic malignancies

Relapse remains a major cause of death after allogeneic hematopoietic cell transplantation (allo-HCT). Graft-versus-tumor effect is primarily mediated by donor T cells. Cytotoxic T lymphocyte antigen-4 (CTLA-4) is a critical inhibitor of T cell proliferation. Single nucleotide polymorphisms (SNPs) in CTLA-4 may affect immune responses. We hypothesized that CTLA-4 SNPs will be associated with disease control after allo-HCT. One hundred sixty-four adult patients with the availability of pretransplantation recipient and donor DNA samples were included in this analysis. Ten tagSNPs of the CTLA-4 gene were identified. Donor CTLA-4 SNP rs4553808 was associated with decreased relapse-free survival (RFS) (P = .019) and overall survival (OS) (P = .033). In multivariable analysis of an additive genetic model, genotype of CTLA-4 SNP rs4553808 was an independent risk factor for inferior RFS (hazard ratio [HR] = 1.73, 95% confidence interval [CI] 1.10-2.71, P = .017) and OS (HR = 1.84, 95% CI 1.13-3.0, P = .015). CTLA-4 SNPs can be used to identify high-risk patient subsets that may benefit from preemptive immunomodulation to decrease relapse rates and improve survival.

IgG antibodies to ATG early after pediatric hematopoietic SCT increase the risk of acute GVHD

Anti-thymocyte globulin (ATG), raised in rabbits, is frequently used in allogeneic hematopoietic SCT (HSCT), to prevent graft rejection and acute GVHD. In solid organ transplant patients, antibodies to rabbit IgG result in an enhanced clearance of ATG. The occurrence of such antibodies in HSCT recipients and their clinical impact is unknown. Concentrations of ATG and anti-ATG antibodies were measured in 72 pediatric HSCT recipients treated with ATG as part of the conditioning. Anti-ATG antibodies were detected in 20 children (28%), all transplanted with a non-depleted graft. IgG anti-ATG, alone or combined with IgM and/or IgA anti-ATG, appeared in 10 children. Four patients developed IgG anti-ATG antibodies early (before day 22) post-HSCT. They had steep drops in ATG levels and showed rapid T-cell recovery, which was associated with a significantly increased risk of acute GVHD. In six patients IgG anti-ATG responses occurred later (range 28-46 days) after HSCT without an increased risk of GVHD. A total of 10 children only mounted an IgM (and IgA) anti-ATG response, which was without major impact on ATG levels. These results indicate that early development of IgG anti-ATG antibodies has a major impact on acute GVHD. Routine analysis ATG/anti-ATG Ab measurement should be considered.

Chronic graft-versus-host disease: long-term results from a randomized trial on graft-versus-host disease prophylaxis with or without anti-T-cell globulin ATG-Fresenius

Previous randomized graft-versus-host disease (GVHD)-prophylaxis trials have failed to demonstrate reduced incidence and severity of chronic GVHD (cGVHD). Here we reanalyzed and updated a randomized phase 3 trial comparing standard GVHD prophylaxis with or without pretransplantation ATG-Fresenius (ATG-F) in 201 adult patients receiving myeloablative conditioning before transplantation from unrelated donors. The cumulative incidence of extensive cGVHD after 3 years was 12.2% in the ATG-F group versus 45.0% in the control group (P < .0001). The 3-year cumulative incidence of relapse and of nonrelapse mortality was 32.6% and 19.4% in the ATG-F group and 28.2% and 33.5% in the control group (hazard ratio [HR] = 1.21, P = .47, and HR = 0.68, P = .18), respectively. This nonsignificant reduction in nonrelapse mortality without increased relapse risk led to an overall survival rate after 3 years of 55.2% in the ATG-F group and 43.3% in the control group (HR = 0.84, P = .39, nonsignificant). The HR for receiving immunosuppressive therapy (IST) was 0.31 after ATG-F (P < .0001), and the 3-year probability of survival free of IST was 52.9% and 16.9% in the ATG-F versus control, respectively. The addition of ATG-F to standard cyclosporine, methotrexate GVHD prophylaxis lowers the incidence and severity of cGVHD, and the risk of receiving IST without raising the relapse rate. ATG-F prophylaxis reduces cGVHD morbidity.

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.

Standard graft-versus-host disease prophylaxis with or without anti-T-cell globulin in haematopoietic cell transplantation from matched unrelated donors: a randomised, open-label, multicentre phase 3 trial

BACKGROUND

Graft-versus-host disease (GVHD) is a major cause of morbidity and mortality after allogeneic haematopoietic cell transplantation from unrelated donors. Anti-T-cell globulins (ATGs) might lower the incidence of GVHD. We did a prospective, randomised, multicentre, open-label, phase 3 trial to compare standard GVHD prophylaxis with ciclosporin and methotrexate with or without anti-Jurkat ATG-Fresenius (ATG-F).

METHODS

Between May 26, 2003, and Feb 8, 2007, 202 patients with haematological malignancies were centrally randomly assigned using computer-generated centre-stratified block randomisation between treatment groups receiving ciclosporin and methotrexate with or without additional ATG-F. One patient in the ATG-F group did not undergo transplantation, thus 201 patients who underwent transplantation with peripheral blood (n=164; 82%) or bone marrow (n=37; 18%) grafts from unrelated donors after myeloablative conditioning were included in the full analysis set, and were analysed according to their randomly assigned treatment (ATG-F n=103, control n=98). The primary endpoint was severe acute GVHD (aGVHD) grade III-IV or death within 100 days of transplantation. The trial is registered with the numbers DRKS00000002 and NCT00655343.

FINDINGS

The number of patients in the ATG-F group who had severe aGVHD grade III-IV or who died within 100 days of transplantation was 12 and 10 (21.4%, 95% CI 13.4-29.3), respectively, compared with 24 and nine (33.7%, 24.3-43.0) patients, respectively, in the control group (adjusted odds ratio 0.59, 95% CI 0.30-1.17; p=0.13). The cumulative incidence of aGVHD grade III-IV was 11.7% (95% CI 6.8-19.8) in the ATG-F group versus 24.5% (17.3-34.7) in the control group (adjusted hazard ratio [HR] 0.50, 95% CI 0.25-1.01; p=0.054), and cumulative incidence of aGVHD grade II-IV was 33.0% (n=34; 95% CI 25.1-43.5) in the ATG-F group versus 51.0% (n=50; 95% CI 42.0-61.9) in the control group (adjusted HR 0.56, 0.36-0.87; p=0.011). The 2-year cumulative incidence of extensive chronic GVHD was 12.2% (n=11; 95% CI 7.0-21.3) versus 42.6% (n=34; 95% CI 33.0-55.0; adjusted HR 0.22, 0.11-0.43; p<0.0001). There were no differences between treatment groups with regard to relapse, non-relapse mortality, overall survival, and mortality from infectious causes.

INTERPRETATION

The addition of ATG-F to GVHD prophylaxis with ciclosporin and methotrexate resulted in decreased incidence of acute and chronic GVHD without an increase in relapse or non-relapse mortality, and without compromising overall survival. The use of ATG-F is safe for patients who are going to receive a haematopoietic cell transplantation from matched unrelated donors.

FUNDING

Fresenius Biotech GmbH.

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 follow-up of allogeneic HSCT for CML reveals significant improvement in the outcome over the last decade

Allogeneic hematopoetic stem cell transplantation (HSCT) is still the only curative therapeutic option for chronic myelogenous leukemia (CML). To examine the development of allogeneic HSCT at our center over the past two decades (decade 1: 1984-1994; decade 2: 1995-2005), all CML patients transplanted in first chronic phase (n = 234) were analyzed with respect to patient characteristics, overall survival, transplant-related mortality (TRM), and relapse incidence. The median follow up time was 54 months (range 1-218). The incidence of acute graft vs host disease (GvHD) degrees II-IV and extensive chronic GvHD were not different between the two decades (p = 0.894 and p = 0.422, respectively). There was also no difference in the relapse incidence (23 vs 26%, p = 0.869). One-year TRM and overall survival were improved in the later decade (33 vs 18%, p = 0.011 and 62 vs 73% at 5 years, p = 0.063, respectively). The major reason for improved outcome in decade 2 was the improved management of acute GvHD and infections in the early phase after transplantation (p = 0.026). In conclusion, the past decade has seen significant improvement in the performance of allogeneic HSCT for CML.

Stable Engraftment after a Conditioning Regimen with Fludarabine and Melphalan for Bone Marrow Transplantation from an Unrelated Donor

Graft failure and nonrelapse mortality (NRM) are major obstacles after the first unrelated-donor bone marrow transplantation (UD-BMT) with reduced-intensity conditioning. We evaluated UD-BMT with fludarabine (5 x 25 mg/m2) and melphalan (2 x 90 mg/m2) treatment combined with short-term methotrexate and tacrolimus (n = 20) or cyclosporine (n = 2) therapy for 22 patients with hematologic malignancies who were ineligible for conventional conditioning. Only 9 patients were in remission at transplantation. Seventeen patients underwent HLA-matched or DRB1 allele-mismatched transplantation, and 5 patients underwent HLA-A allele-mismatched or serologically HLA-DR-mismatched transplantation. Regimen-related toxicities were tolerable, although transient oral mucositis, hepatobiliary enzyme elevation, and diarrhea were observed frequently. All evaluable patients achieved sustained neutrophil engraftment, and all patients tested showed complete donor chimerism on day 28. With a median follow-up of 16 months, NRM and overall survival rates at 1 year were 19% and 81%, respectively, among the patients who underwent HLA-matched or DRB1 allele-mismatched transplantation. Acute graft-versus-host disease (GVHD) of grades II to IV occurred in 26% of the patients. The cumulative incidence of chronic GVHD was 44%. Despite the small number of patients and the short follow-up period, this reduced-intensity regimen enabled satisfactory engraftment and achievement of rapid complete donor chimerism with tolerable toxicities in the patients, including those who underwent HLA-mismatched UD-BMT.

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.

What role is there for antithymocyte globulin in allogeneic nonmyeloablative canine hematopoietic cell transplantation?

We investigated whether pretransplantation immunosuppression with canine-specific rabbit antithymocyte globulin (ATG), combined with a suboptimal dose of 1 Gy of total body irradiation (TBI), would permit engraftment of canine dog leukocyte antigen-identical marrow. Cumulative ATG doses of 2 to 5 mg/kg produced a T-cell depletion of 1 log in the peripheral blood and 50% in the lymph nodes. Serum levels of ATG peaked on days 4 to 6 after initiation of therapy and became undetectable by day 13 as a result of canine antibody responses to ATG. ATG prolonged allogeneic skin graft survival to 14 days (n = 5), compared with 8 days in control dogs (P = .0003). Five dogs were given marrow transplants after ATG (3.5-5 mg/kg) and 1 Gy of TBI. Posttransplantation immunosuppression consisted of mycophenolate mofetil and cyclosporine. All dogs showed initial engraftment, with maximum donor chimerism levels of 25%. However, only 1 dog achieved sustained engraftment, and 4 rejected their grafts. The duration of engraftment ranged from 8 to > or = 36 weeks (median, 11 weeks), and this is comparable to that in 6 historical controls not given ATG (range, 3-12 weeks; median, 10 weeks; P = .20). The total nucleated cell doses in the marrow grafts had the highest correlation coefficient with the duration of engraftment: 0.82 (P = .09). We concluded that administering ATG before an otherwise suboptimal conditioning dose of 1 Gy of TBI failed to secure uniform stable hematopoietic engraftment.

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.

Antithymocyte globulin for the prevention of graft-versus-host disease after unrelated hematopoietic stem cell transplantation for acute myeloid leukemia: results from the multicenter German cooperative study group

A total of 155 patients with acute myeloid leukemia (AML) received hematopoietic stem cell transplants from unrelated donors after standard conditioning. Clinical outcome after the use of two different antithymocyte globulins for the prevention of graft-versus-host disease (GvHD) was analyzed in a retrospective study as follows: rabbit ATG (Thymoglobulin Sangstat/Genzyme, n=49, median age 42 years, 53% in CR, further ATG-S); rabbit ATG (ATG-Fresenius, n=38, median age 42 years, 58% in CR, further ATG-F) or no ATG (n=68, median age 36 years, 55% in CR). The groups were comparable regarding disease status at transplant, age, CMV status and cytogenetics. Grade III-IV acute GvHD was found in 15% in the ATG and 27% in the no ATG group (P=0.44). The most important independent risk factors for chronic GvHD (cGvHD) were the use of ATG, disease status at transplant and conditioning. cGvHD developed significantly more frequently in no ATG group. With the median follow-up of 34 months, the 5-year survival is 42% for those transplanted in CR. To conclude, these data demonstrate that the transplants performed in CR, with ATG, are associated with a good outcome, low incidence of cGvHD and no increase of relapse.

Reduced-intensity conditioning using TBI (8 Gy), fludarabine, cyclophosphamide and ATG in elderly CML patients provides excellent results especially when performed in the early course of the disease

Allogeneic bone marrow or stem cell transplantation is a curative therapeutic option for chronic myelogenous leukemia. In order to decrease the toxicity of the procedure, the dosage of total body irradiation was reduced from 12 to 8 Gy and subsequently the dose of cyclophosphamide from 120 to 80 mg/kg. The purine analogue fludarabine, ATG, cyclosporine A and a short course of methotrexate were given for immune suppression. So far, 35 elderly CML patients with sibling and unrelated donors have been transplanted. Transplant-related mortality at day + 100 was 11%. After engraftment, all patients achieved a complete cytogenetic remission. Relapse occurred in 14% of the patients. The risk of relapse was significantly higher in those patients transplanted in second chronic or accelerated phase (P = 0.048). After a median follow-up of 30 months (range 12-62), 63% of the patients are alive. Those patients transplanted within the first year from diagnosis had an overall survival of 79% (P = 0.049), emphasizing the benefit of early transplantation. Stepwise reduction of conditioning intensity resulted in stable engraftment, low relapse rates and encouraging overall survival in this high-risk patient group.

Dose Study of Thymoglobulin During Conditioning for Unrelated Donor Allogeneic Stem-Cell Transplantation

BACKGROUND

Steroid-related bone loss is a recognized complication after renal transplantation. In a prospective, randomized, multicenter study we compared the influence of a steroid-free immunosuppressive regimen with a regimen with limited steroid exposure on the changes in bone mass after renal transplantation.

METHODS

A total of 364 recipients of a renal transplant were randomized to receive either daclizumab (1 mg/kg on days 0 and 10 after transplantation; steroid-free group n=186) or prednisone (0.3 mg/kg per day tapered to 0 mg at week 16 after transplantation; steroids group n=178). All patients received tacrolimus, mycophenolate mofetil, and, during the first 3 days, 100 mg prednisolone intravenously. Changes in bone mineral density (BMD) were evaluated in 135 and 126 patients in the steroid-free and steroids group, respectively.

RESULTS

The mean (+/- SD) BMD of the lumbar spine decreased slightly in both groups during the first 3 months after transplantation (steroid-free -1.3 +/- 4.0% [P<0.01]; steroids -2.3 +/-4.2% [P<0.01]). In the following months, lumbar BMD recovered in both groups (P<0.01), resulting in a lumbar BMD at 12 months after transplantation comparable with the baseline value. No difference between the groups was found at 3 months (steroid-free versus steroids +1.0%; 95% confidence interval -0.0%-+2.0%, P=0.060) and at 12 months after transplantation (steroid-free versus steroids +0.9%; 95% confidence interval -0.8%-+2.6%, NS).

CONCLUSION

The use of a moderate dose of steroids during 4 months after transplantation has no important influence on bone mass during the first year after renal transplantation. On average, both regimens prevented accelerated bone loss.

Reduced-intensity conditioning with busulfan and fludarabine with or without antithymocyte globulin in HLA-identical sibling transplantation – a retrospective analysis

It is unknown whether the addition of antithymocyte globulin (ATG) to reduced-intensity conditioning with busulfan (BU) and fludarabine (FLU) is beneficial in HLA-identical sibling transplantation. Therefore, we analyzed retrospectively data on 83 patients, who received peripheral blood stem cells from HLA-identical siblings after conditioning with either 8 mg/kg BU and 150 mg/m2 FLU (n=45) or 8 mg/kg BU, 180 mg/m2 FLU and 40 mg/kg ATG (n=38). Graft-versus-host disease (GVHD) prophylaxis consisted of CSA alone (n=32) or a combination with either MTX or MMF (n=51). The median age was 52 years. Graft failure occurred in two patients after BU/FLU and in three after BU/FLU/ATG (P=0.66). After conditioning with BU/FLU, platelet recovery was significantly faster (P=0.017), and less platelet (P<0.001) and red blood cell (P=0.002) support was needed. Incidences of acute GVHD grades II and IV were 46 and 49%, respectively. Limited chronic GVHD occurred more often after BU/FLU compared to BU/FLU/ATG (54 vs 23%, P=0.02). The overall survival, non-relapse and relapse mortality did not differ significantly. We conclude that in peripheral blood stem cell transplantation from HLA-identical siblings after reduced-intensity conditioning with BU and FLU, ATG has no major impact on the rate of graft rejection and acute GVHD, but it reduces the incidence of limited chronic GVHD.