Matched and mismatched allogeneic stem-cell transplantation from unrelated donors using combined graft-versus-host disease prophylaxis including rabbit anti-T lymphocyte globulin

Hepatic graft-versus-host disease: what we know, when to biopsy, and how to diagnose

Graft-versus-host disease (GVHD) is one of the serious complications that may develop after hematopoietic cell transplantation (HCT), for hematologic malignancies, solid organ transplantation, and other hematologic disorders. GVHD develops due to T lymphocytes present in the graft attacking the host antigens, which results in tissue damage. A significant number of HCT patients develop acute or chronic GVHD, which may affect multiple organs including the liver. The diagnosis of hepatic GVHD (hGVHD) is challenging as many other conditions in HCT patients may lead to liver dysfunction. Particularly challenging among the various conditions that give rise to liver dysfunction is differentiating sinusoidal obstruction syndrome and drug-induced liver injury (DILI) from hGVHD on clinical grounds and laboratory tests. Despite the minimal risks involved in performing a liver biopsy, the information gleaned from the histopathologic changes may help in the management of these very complex patients. There is a spectrum of histologic features found in hGVHD, and most involve histopathologic changes affecting the interlobular bile ducts. These include nuclear and cytoplasmic abnormalities including dysmorphic bile ducts, apoptosis, and cholangiocyte necrosis, among others. The hepatitic form of hGVHD typically shows severe acute hepatitis. With chronic hGVHD, there is progressive bile duct loss and eventually fibrosis. Accurate diagnosis of hGVHD is paramount so that timely treatment and management can be initiated. Techniques to prevent and lower the risk of GVHD from developing have recently evolved. If a diagnosis of acute GVHD is made, the first-line of treatment is steroids. Recurrence is common and steroid resistance or dependency is not unusual in this setting. Second-line therapies differ among institutions and have not been uniformly established. The development of GVHD, particularly hGVHD, is associated with increased morbidity and mortality.

A uniform conditioning regimen of busulfan, fludarabine, and antithymocyte globulin for allogeneic haematopoietic cell transplantation from haploidentical family, matched sibling, or unrelated donors-A single-centre, prospective, explorative study

In a prospective, explorative study, the donor-source difference of haploidentical family (HF), matched sibling (MS), and unrelated donors (UD) was evaluated for the outcome of haematopoietic cell transplantations (HCT) in 101 patients with acute myeloid leukaemia (AML) in complete remission (CR). To eliminate compounding effects, a uniform conditioning regimen containing antithymocyte globulin (ATG) was used. After transplantation, there was a significantly higher cumulative incidence of acute graft-versus-host disease (GVHD) in HF-HCT patients (49%, 7%, and 16% for HF-, MS- and UD-HCT respectively; p < 0.001). A quarter of acute GVHD cases observed in HF-HCT patients occurred within three days of engraftment and were characterized by diffuse skin rash, fever, weight gain, and hypoalbuminaemia. This peri-engraftment acute GVHD was not observed in MS-HCT or UD-HCT patients. Additionally, a significantly higher proportion of HF-HCT patients achieved complete donor chimaerism in the peripheral mononuclear cells at one month (88%, 46%, and 69% for HF-, MS- and UD-HCT respectively; p = 0.001). There was no significant difference in engraftment, chronic GVHD, leukaemia recurrence, non-relapse mortality, and patient survival. In patients with AML in CR who received HCT using ATG-containing conditioning, stronger donor-patient alloreactivity was observed in HF-HCT, in terms of increased acute GVHD and higher likelihood of complete donor chimaerism.

Outcomes with mismatched unrelated donor allogeneic hematopoietic stem cell transplantation in adults: A systematic review and meta-analysis

Background

Allogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative therapy for various hematologic disorders. Alternative donor strategies such as mismatched unrelated donors (MMUD) offer the option of HSCT to patients lacking a human leukocyte antigen (HLA)-matched donor. We conducted a systematic review and meta-analysis to evaluate outcomes after MMUD-HSCT.

Methods

A literature search was performed on PubMed, Cochrane Library, and ClinicalTrials.gov from the inception date through April 6, 2022. After screening 2477 manuscripts, 19 studies were included. Data was extracted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Pooled analysis was done using the meta-package by Schwarzer et al. Proportions with 95% confidence intervals (CI) were computed.

Results

A total of 3336 patients from 19 studies were included. The median age was 52.1 years, and 53% of recipients were males. The graft source was bone marrow in 19% and peripheral blood stem cells in 81% of recipients. The median time to transplant from hematologic diagnosis was 10 (1-247) months. Hematologic diagnoses included myeloid (82.9%), lymphoid (41.1%), and other disorders (3%). The reduced intensity and myeloablative conditioning were used in 65.6% and 32% of recipients, respectively. In-vivo T-cell depletion was performed in 56.7% of the patients. Most patients had one (87.9%) or two (11.4%) antigen HLA-mismatch. The pooled 1-year overall survival (OS) was 63.9% (95% CI 0.57-0.71, n=1426/2706), and the pooled 3-year OS was 42.1% (95% CI 0.34.2-0.50, n=907/2355). The pooled progression-free survival was 46.6% (95% CI 0.39-0.55, n=1295/3253) after a median follow-up of 1.8 (range 1-6) years. The pooled relapse rate was 26.8% (95% CI 0.22-0.32, n=972/3253) after a median follow-up of 2.25 (1-3) years. The pooled incidence of acute (grade II-IV) graft-versus-host disease (GVHD) and chronic GVHD was 36.4% (95% CI 0.31-0.42, n=1131/3030) and 41.2% (95% CI 0.35-0.48, n=1337/3228), respectively. The pooled non-relapse mortality was 22.6% (95% CI 0.17-0.29, n=888/3196) after a median follow-up of 2.6 (1-5) years.

Conclusion

MMUD-HSCT has demonstrated favorable outcomes with an acceptable toxicity profile. It represents a promising option in patients lacking an HLA-matched or haploidentical donor and may expand HSCT access to underrepresented racial and ethnic populations.

Outcomes of allogeneic haematopoietic stem cell transplantation for patients with severe aplastic anaemia using the porcine antilymphocyte globulin-containing conditioning regimen

Antithymocyte globulin (ATG) is widely used for allogeneic haematopoietic stem cell transplantation (allo-HSCT) in severe aplastic anaemia (SAA). Only rabbit-ATG (r-ATG) and porcine-antilymphocyte globulin (p-ALG) are available in China, but the p-ALG-containing conditioning regimen for allo-HSCT in SAA has seldom been reported. In this study, we retrospectively evaluated the outcomes of 41 SAA patients receiving allo-HSCT with a p-ALG-containing conditioning regimen in our transplantation centre. All patients engrafted, and no death during conditioning was observed. The actuarial 3-year overall survival (OS) rates were 95.1 ± 3.4%. The actuarial 3-year disease-free survival (DFS) rates were 85.0 ± 5.7%. Acute graft-versus-host disease (aGVHD) predicted inferior OS (p < 0.05). The interval from diagnosis to transplantation for more than 100 days predicted an inferior DFS rate (p < 0.05) and a higher graft rejection/poor graft function (GR/PGF) rate (p < 0.01). In conclusion, the p-ALG-containing regimen showed satisfactory effects and safety in allo-HSCT for SAA patients. P-ALG could be a potential alternative preparation for r-ATG in SAA allo-HSCT.

Hematopoietic stem cell transplant with HLA-mismatched grafts: impact of donor, source, conditioning, and graft versus host disease prophylaxis

INTRODUCTION

Allogeneic hematopoietic cell transplantation is frequently used to treat malignant and non-malignant conditions, and many patients lack a human leukocyte antigen (HLA) matched related or unrelated donor. For those patients, available alternative graft sources include HLA mismatched unrelated donors, cord blood, or haplo-identical donors. These graft sources have unique characteristics and associated outcomes requiring graft-specific variations to conditioning regimens, graft-versus-host disease prophylaxis, and post-transplant care. Areas covered: This manuscript will cover approaches in selecting donors, conditioning regimens, graft versus host disease prophylaxis, post-transplant care, and ongoing clinical trials related to mismatched grafts. Expert commentary: In the setting, haplo-identical grafts are increasingly popular due to low graft versus host disease (GVHD) risk and control of cellular dose. We recommend young male donors, utilizing bone marrow with post-transplant cyclophosphamide for GVHD prophylaxis. Cord blood transplant is appropriate for young healthy patients, and we recommend 6/8 HLA matched grafts with at least 2.0 × 10⁷/kg total nucleated cell dose. For mismatched unrelated donors we recommend young male donors, utilizing bone marrow with in vivo T-cell conditioning with post-transplant cyclophosphamide, alemtuzumab, or ATG. With these transplants, significant post-transplant surveillance and infectious prophylaxis is key to reducing treatment-related mortality.

T-cell receptor-α repertoire of CD8+ T cells following allogeneic stem cell transplantation using next-generation sequencing

Alloreactivity or opportunistic infections following allogeneic stem cell transplantation are difficult to predict and contribute to post-transplantation mortality. How these immune reactions result in changes to the T-cell receptor repertoire remains largely unknown. Using next-generation sequencing, the T-cell receptor alpha (TRα) repertoire of naïve and memory CD8⁺ T cells from 25 patients who had received different forms of allogeneic transplantation was analyzed. In parallel, reconstitution of the CD8⁺/CD4⁺ T-cell subsets was mapped using flow cytometry. When comparing the influence of anti-T-cell therapy, a delay in the reconstitution of the naïve CD8⁺ T-cell repertoire was observed in patients who received in vivo T-cell depletion using antithymocyte globulin or post-transplantation cyclophosphamide in case of haploidentical transplantation. Sequencing of the TRα identified a repertoire consisting of more dominant clonotypes (>1% of reads) in these patients at 6 and 18 months post transplantation. When comparing donor and recipient, approximately 50% and approximately 80% of the donors’ memory repertoire were later retrieved in the naïve and memory CD8⁺ T-cell receptor repertoire of the recipients, respectively. Although there was a remarkable expansion of single clones observed in the recipients’ memory CD8⁺ TRα repertoire, no clear association between graft-versus-host disease or cytomegalovirus infection and T-cell receptor diversity was identified. A lower TRα diversity was observed in recipients of a cytomegalovirus-seropositive donor (P=0.014). These findings suggest that CD8⁺ T-cell reconstitution in transplanted patients is influenced by the use of T-cell depletion or immunosuppression and the donor repertoire.

Relative Impact of HLA Matching and Non-HLA Donor Characteristics on Outcomes of Allogeneic Stem Cell Transplantation for Acute Myeloid Leukemia and Myelodysplastic Syndrome

Increasing donor-recipient HLA disparity is associated with negative outcomes of allogeneic hematopoietic stem cell transplantation (HSCT), but its comparative relevance amid non-HLA donor characteristics is not well established. We addressed this question in 3215 HSCTs performed between 2005 and 2013 in Germany for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). Donors were HLA-matched related (MRD; n = 872) or unrelated (10/10 MUD, n = 1553) or HLA-mismatched unrelated (<10/10 MMUD, n = 790). Overall survival (OS) was similar after MRD compared with 10/10 MUD HSCT, reflecting opposing hazards of relapse (hazard ratio [HR], 1.32; P < .002) and nonrelapse mortality (HR, .63; P < .001). After UD HSCT, increasing HLA disparity was associated with inferior OS (HR, 1.21 [P < .02] and HR, 1.57 [P < .001] for 9/10 and ≤8/10 MMUD, respectively, compared with 10/10 MUD). Among non-HLA donor characteristics, age, sex mismatching (male recipient-female donor), and cytomegalovirus (CMV) mismatching (positive recipient-negative donor) impacted OS. Multivariate subgroup analysis showed that OS was similar after HSCT from the youngest 9/10 MMUD (<30 years) compared with the oldest 10/10 MUD (>40 years) (HR, 1.18; P = .25) and also in male patients transplanted from female 10/10 MUD compared with male 9/10 MMUD (HR, .89; P = .46). In contrast, OS of CMV-positive patients tended to be better with CMV-negative 10/10 MUDs compared with CMV-positive 9/10 MMUDs (HR, 1.31; P = .04). Because of low patient numbers in subgroups, definite conclusions and establishment of a hierarchy among HLA matching and non-HLA donor characteristics could not be made. Our data suggest that the impact of donor age and sex mismatch but not CMV mismatch on outcome of allogeneic HSCT may be comparable with that of single HLA disparity.

Single Antigen-Mismatched Unrelated Hematopoietic Stem Cell Transplantation Using High-Dose Post-Transplantation Cyclophosphamide Is a Suitable Alternative for Patients Lacking HLA-Matched Donors

The optimal prophylaxis regimen for graft-versus-host disease (GVHD) in the setting of mismatched unrelated donor (MMUD) allogeneic hematopoietic stem cell transplantation (alloHSCT) is not defined. The use of high-dose post-transplant cyclophosphamide (PTCy) in haploidentical transplantation has proven feasible and effective in overcoming the negative impact of HLA disparity on survival. We hypothesized that PTCy could also be effective in the setting of MMUD transplantation. We retrospectively analyzed 86 consecutive adult recipients of alloHSCT in our institution, comparing 2 contemporaneous groups: PTCy MMUD (n = 26) versus matched unrelated donor (MUD) (n = 60). Graft source was primarily peripheral blood (92%). All PTCy MMUD were HLA 7/8 (differences in HLA class I loci in 92% of patients) and received PTCy plus tacrolimus ± mofetil mycophenolate as GVHD prophylaxis. No differences were observed between PTCy MMUD and MUD in the 100-day cumulative incidence of acute GVHD grades II to IV (31% versus 22%, respectively; P = .59) and III to IV (8% versus 10%, P = .67). There was a trend for a lower incidence of moderate to severe chronic GVHD at 1 year after PTCy MMUD in comparison with MUD (22% versus 41%, P = .098). No differences between PTCy MMUD and MUD were found regarding nonrelapse mortality (25% versus 18%, P = .52) or relapse rate (11% versus 19%, P = .18). Progression-free survival and overall survival at 2 years were similar in both cohorts (67% versus 54% [HR, .84; 95% CI, .38 to 1.88; P = .68] and 72% versus 57% [HR, .71; 95% CI, .31 to 1.67; P = .44], respectively). The 2-year cumulative incidence of survival free of moderate to severe chronic GVHD and relapse tended to be higher in the PTCy MMUD group (47% versus 24%; HR, .60; 95% CI, .31 to 1.14; P = .12). We conclude that HLA 7/8 MMUD transplantation using PTCy plus tacrolimus is a suitable alternative for those patients who lack a MUD.

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.

Pathophysiology of GvHD and Other HSCT-Related Major Complications

For over 60 years, hematopoietic stem cell transplantation has been the major curative therapy for several hematological and genetic disorders, but its efficacy is limited by the secondary disease called graft versus host disease (GvHD). Huge advances have been made in successful transplantation in order to improve patient quality of life, and yet, complete success is hard to achieve. This review assimilates recent updates on pathophysiology of GvHD, prophylaxis and treatment of GvHD-related complications, and advances in the potential treatment of GvHD.

A comparison between allogeneic stem cell transplantation from unmanipulated haploidentical and unrelated donors in acute leukemia

BACKGROUND

In the absence of a HLA-matched related or matched unrelated donor, allogeneic stem cell transplantation (allo-SCT) from mismatched unrelated donors or haploidentical donors are potential alternatives for patients with acute leukemia with an indication to allo-SCT. The objective of this study was to compare the outcome of allo-SCT from T cell-replete haploidentical (Haplo) versus matched (MUD 10/10) or mismatched unrelated donor at a single HLA-locus (MMUD 9/10) for patients with acute leukemia in remission.

METHODS

Two hundred sixty-five adult patients with de novo acute leukemia in first or second remission that received a Haplo-SCT between January 2007 and December 2013 were compared with 2490 patients receiving a MUD 10/10 and 813 receiving a MMUD 9/10. Propensity score weighted analysis was conducted in order to control for disease risk imbalances between the groups.

RESULTS

The weighted 3-year non-relapse mortality and relapse incidence were 29 and 30% for Haplo, 21 and 29% for MUD 10/10, and 29 and 25% for MMUD 9/10, respectively. The weighted 3-year leukemia-free survival (LFS) and overall survival (OS) were 41 and 46% for Haplo, 50 and 56% for MUD 10/10, and 46 and 48% for MMUD 9/10, respectively. Using weighted Cox model, both LFS and OS were significantly higher in transplants from MUD 10/10 compared from those in Haplo but not different between transplants from MMUD 9/10 and Haplo. The type of donor was not significantly associated with neither acute nor chronic graft-versus-host disease.

CONCLUSIONS

Patients with acute leukemia in remission have better outcomes if transplanted from a MUD 10/10. We did not find any significant difference in outcome between transplants from MMUD 9/10 and Haplo, suggesting that both can be equally used in the absence of a 10/10 MUD. KEY POINT 1: Better outcomes using fully (10/10) matched unrelated donor for allo-SCT in acute leukemia in remission. KEY POINT 2: Similar outcomes after allo-SCT from unmanipulated haploidentical graft or mismatched (9/10) unrelated donor in acute leukemia in remission.

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.

Long-term outcomes of HLA-haploidentical stem cell transplantation based on an FBCA conditioning regimen compared with those of HLA-identical sibling stem cell transplantation for haematologic malignancies

A comparison was conducted of 213 patients with haematologic malignancies who underwent HLA-identical sibling (n=108) or HLA-haploidentical (n=105) haematopoietic cell transplantation (haplo-HCT) at our centre. The conditioning regimen included fludarabine, busulphan, cyclophosphamide and antilymphocyte globulin (ATG) (FBCA). The total dose of ATG differed between identical and haploidentical groups (3.75 mg/kg versus 12.5 mg/kg). The cumulative incidences of grade II-IV acute GvHD in the identical and haploidentical groups were 20.4% and 21.9% (P=0.73), and 2-year cumulative incidences of chronic GvHD were 36.4% and 24.1% (P=0.17), respectively. The 3-year probabilities of non-relapse mortality for identical and haploidentical groups were 20.5% and 34.9% (P=0.048), and for relapse were 22.2% and 21.0% (P=0.85), respectively. The 3-year overall survivals in the identical and haploidentical groups were 62.6% and 52.6% (P=0.054), whereas the 3-year disease-free survivals were 54.7% and 43.1% (P=0.14), respectively. In the multivariate analysis, patients in the high-risk group exhibited reduced survival, and the higher dose of mononuclear or CD34+ cells resulted in an increase in the likelihood of survival. In conclusion, haplo-HCT based on an FBCA conditioning regimen could achieve nearly comparable outcomes to HLA-identical sibling HCT.

Antithymocyte globulin in allogeneic hematopoietic cell transplantation: benefits and limitations

Significant advances have been made in allogeneic hematopoietic cell transplantation by reducing toxicities and optimizing its efficacy. Antithymocyte globulin (ATG) is an important in vivo T-cell depletion strategy, which reduces the risk of graft-versus-host disease in HLA-matched or -mismatched donor allografting. ATG effectively targets alloreactive T cells at the expense of potentially increasing the risk of post-hematopoietic cell transplantation infections and delayed immune reconstitution. We summarize the targets, mechanisms, various preparations of ATG, the growing role of ATG in prevention of graft-versus-host disease in various transplant modalities as well as emerging data on pharmacokinetic modeling for individualized ATG dosing. Further research is needed to optimize the ATG administration while minimizing the toxicities.

Post-transplantation cyclophosphamide versus conventional graft-versus-host disease prophylaxis in mismatched unrelated donor haematopoietic cell transplantation

Post-transplantation cyclophosphamide (PTCy) is an effective strategy to prevent graft-versus-host disease (GVHD) after haploidentical haematopoietic cell transplantation (HCT). We determined the efficacy of PTCy-based GVHD prophylaxis in human leucocyte antigen (HLA)-mismatched unrelated donor (MMUD) HCT. We analysed 113 adult patients with high-risk haematological malignancies who underwent one-antigen MMUD transplantation between 2009 and 2013. Of these, 41 patients received PTCy, tacrolimus and mycophenolate mofetil (MMF) for GVHD prophylaxis; 72 patients received conventional prophylaxis with anti-thymocyte globulin, tacrolimus and methotrexate. Graft source was primarily bone marrow (83% PTCy vs. 63% conventional group). Incidence of grade II-IV (37% vs. 36%, P = 0·8) and grade III-IV (17% vs. 12%, P = 0·5) acute GVHD was similar at day 100. However, the incidence of grade II-IV acute GVHD by day 30 was significantly lower in the PTCy group (0% vs. 15%, P = 0·01). Median time to neutrophil (18 days vs. 12 days, P < 0·001) and platelet (25·5 days vs. 18 days, P = 0·05) engraftment was prolonged in PTCy group. Rates of graft failure, chronic GVHD, 2-year non-relapse mortality, relapse, progression-free survival or overall survival were similar. Our results demonstrate that PTCy, tacrolimus and MMF for GVHD prophylaxis is safe and produced similar results as conventional prophylaxis in patients with one antigen HLA-MMUD HCT.

Mismatched unrelated alternative donors for hematological malignancies

For the majority of hematologic malignancies allogeneic hematopoietic cell transplantation (HCT) is the only curative treatment option. Sibling donors have been the standard for adult patients. Since there is not a suitable family donor for all patients, the need for alternative donors for HCT is great. Fortunately, the availability of unrelated volunteer donor registries has expanded over the years and the results of HCT with matched unrelated donors (MUD) are comparable to the results with matched related donors (MRD). Nevertheless, there are many patients lacking a well-matched donor. To increase the applicability of transplantation, alternative donors such as mismatched unrelated donors (MMURD), cord blood stem cell products and haploidentical related donors have been widely used. This review seeks to give insights into the use of MMUD donors for HCT and summarize the existing data.

Differential impact of two doses of antithymocyte globulin conditioning on lymphocyte recovery upon haploidentical hematopoietic stem cell transplantation

Background

In vivo depletion of host T cells with antithymocyte globulin (ATG) is a common strategy for preventing graft-versus-host disease in allogeneic hematopoietic stem cell transplantation (HSCT). The total dose of ATG in conditioning regimens appears to be an important factor that influences the outcome in recipients of transplants. However, the optimal ATG dosage has not been established to date. It remains unclear whether, in the setting of haploidentical HSCT (haploHSCT), different doses of ATG might exert differential influences on the recovery of lymphocyte subpopulations.

Methods

This retrospective study analyzed lymphocyte recovery and its correlation to viral infection in two groups of patients that received different doses of ATG before haploHSCT. We performed flowcytometry to determine immunophenotypes of CD19⁺ B cells and CD3⁺, CD4⁺, CD8⁺, CD4⁺CD45RA⁺, CD4⁺CD45RO⁺, CD4⁺CD28⁺, CD8⁺CD28⁺, and CD4⁻CD8⁻ T cells.

Results

We found that, compared to 6 mg/kg, 10 mg/kg ATG significantly hampered the recoveries of CD4⁺, CD4⁺CD45RA⁺, and CD4⁺CD45RO⁺ T cells in the first 2 months following haploHSCT. Similarly, compared to 6 mg/kg, the 10 mg/kg dose of ATG negatively influenced the recoveries of CD4⁻CD8⁻ and CD8⁺CD28⁺ T cells; recovery was delayed for 6 and 12 months after transplantation, respectively. Moreover, we showed that an increase in Epstein-Barr virus (EBV) infections, associated with the higher dose of ATG, was correlated with the delayed recovery of CD4⁻CD8⁻ double negative T cells.

Conclusions

The present study revealed a differential impact of different ATG conditioning doses on the recoveries of T cell subpopulations post-haploHSCT. This study was the first to connect the recovery of CD4⁻CD8⁻ T cells to the risk of EBV infection after HSCT. These findings will facilitate optimization of the ATG conditioning dosage and improve the outcome of patients with leukemia that receive haploHSCT.

Comparison of Characteristics and Outcomes of Trial Participants and Nonparticipants: Example of Blood and Marrow Transplant Clinical Trials Network 0201 Trial

Controversy surrounds the question of whether clinical trial participants have better outcomes than comparable patients who are not treated on a trial. We explored this question using a recent large, randomized, multicenter study comparing peripheral blood (PB) with bone marrow transplantation from unrelated donors, conducted by the Blood and Marrow Transplant Clinical Trials Network (BMT CTN). We compared characteristics and outcomes of study participants (n = 494) and nonparticipants (n = 1384) who appeared eligible and received similar treatment without enrolling on the BMT CTN trial at participating centers during the study time period. Data were obtained from the Center for International Blood and Marrow Transplant Research. Outcomes were compared between the 2 groups using Cox proportional hazards regression models. No significant differences in age, sex, disease distribution, race/ethnicity, HLA matching, comorbidities, and interval from diagnosis to hematopoietic cell transplantation were seen between the participants and nonparticipants. Nonparticipants were more likely to have lower performance status, lower risk disease, and older donors, and to receive myeloablative conditioning and antithymocyte globulin. Nonparticipants were also more likely to receive PB grafts, the intervention tested in the trial (66% versus 50%, P < .001). Overall survival, transplantation-related mortality, and incidences of acute or chronic graft-versus-host disease were comparable between the 2 groups though relapse was higher (hazard ratio, 1.22; 95% confidence interval, 1.02 to 1.46; P = .028) in nonparticipants. Despite differences in certain baseline characteristics, survival was comparable between study participants and nonparticipants. The results of the BMT CTN trial appear generalizable to the population of trial-eligible patients.

Unrelated cord blood compared with haploidentical grafts in patients with hematological malignancies

BACKGROUND

Alternative donors, such as unrelated umbilical cord blood (UCB) and related haploidentical (haplo) donors, are more and more frequently searched for and used for patients who are candidates for allogeneic hematopoietic stem cell transplantation but are without a suitable related or unrelated donor. The aim of the current retrospective study was to compare the outcome of patients after haplo and UCB grafts prepared using a nonmyeloablative conditioning regimen.

METHODS

A total of 150 adult patients with high-risk hematologic diseases who underwent allogeneic hematopoietic stem cell transplantation from alternative donors at 2 centers (Paoli-Calmettes Institute [Marseille, France] and Humanitas Cancer Center [Milan, Italy]) were analyzed. Sixty-nine patients had haplo donors and 81 patients had UCB donors.

RESULTS

The cumulative incidence of nonrecurrence mortality at 1 year was 23% in the UCB group versus 17% in the haplo group (P = .39). The incidence of grade 2 to 4 acute graft-versus-host disease and extensive chronic graft-versus-host disease in the UCB group versus the haplo group was 52% versus 29% (P = .05) and 12% versus 6% (P<.0001), respectively. The overall survival rate at 2 years was 45% in the UCB group (95% confidence interval [95% CI], 34%-56%) versus 69% in the haplo group (95% CI, 58%-80%) (P = .10). The progression-free survival rate at 2 years was 36% in the UCB group (95% CI, 25%-47%) versus 65% in the haplo group (95% CI, 53%-77%) (P = .01).

CONCLUSIONS

The results of the current study suggest that for patients with high-risk hematological diseases without a related or unrelated donor, haploidentical transplants are a promising alternative option that deserves further investigation.

GVHD prophylaxis with sirolimus-tacrolimus may overcome the deleterious effect on survival of HLA mismatch after reduced-intensity conditioning allo-SCT

Large studies, mostly based on series of patients receiving CSA/tacrolimus (TKR) plus MTX as immunoprophylaxis, have demonstrated a deleterious effect on survival of the presence of a single mismatch out of eight loci after allogeneic hematopoietic SCT (alloHSCT). We retrospectively analyzed a series of 159 adult patients who received sirolimus(SRL)/TKR prophylaxis after alloHSCT. We compared overall outcomes according to HLA compatibility in A, B, C and DRB1 loci at the allele level: 7/8 (n=20) vs 8/8 (n=139). Donor type was unrelated in 95% vs 70% among 7/8 vs 8/8 pairs, respectively (P=0.01). No significant differences were observed in 3-year OS (68 vs 62%), 3-year EFS (53 vs 49%) and 1-year non-relapse mortality (9 vs 13%). Cumulative incidence of grades II-IV acute GVHD (aGVHD) was significantly higher in 7/8 alloHSCT (68% vs 42%, P<0.001) but no significant differences were found for III-IV aGVHD (4.5% vs 11%), overall (35% vs 53%) and extensive (20% vs 35%) chronic GHVD in 7/8 vs 8/8 subgroups, respectively. In summary, the present study indicates favorable outcomes after alloHSCT using the combination of SRL/TKR combination as GVHD prophylaxis with OS in the range of 55-70%, and non-significant differences in overall outcomes, irrespective of the presence of any mismatches at obligatory loci.

T-cell-replete haploidentical HSCT with low-dose anti-T-lymphocyte globulin compared with matched sibling HSCT and unrelated HSCT

We developed an approach of T-cell-replete haploidentical hematopoietic stem cell transplantation (HSCT) with low-dose anti-T-lymphocyte globulin and prospectively compared outcomes of all contemporaneous T-cell-replete HSCT performed at our center using matched sibling donors (MSDs), unrelated donors (URDs), and haploidentical related donors (HRDs). From 2008 to 2013, 90 patients underwent MSD-HSCT, 116 underwent URD-HSCT, and 99 underwent HRD-HSCT. HRDs were associated with higher incidences of grades 2 to 4 (42.4%) and severe acute graft-versus-host disease (17.2%) and nonrelapse mortality (30.5%), compared with MSDs (15.6%, 5.6%, and 4.7%, respectively; P < .05), but were similar to URDs, even fully 10/10 HLA-matched URDs. For high-risk patients, a superior graft-versus-leukemia effect was observed in HRD-HSCT, with 5-year relapse rates of 15.4% in HRD-HSCT, 28.2% in URD-HSCT (P = .07), and 49.9% in MSD-HSCT (P = .002). Furthermore, 5-year disease-free survival rates were not significantly different for patients undergoing transplantation using 3 types of donors, with 63.6%, 58.4%, and 58.3% for MSD, URD, and HRD transplantation, respectively (P = .574). Our data indicate that outcomes after HSCT from suitably matched URDs and HRDs with low-dose anti-T-lymphocyte globulin are similar and that HRD improves outcomes of patients with high-risk leukemia. This trial was registered at www.chictr.org (Chinese Clinical Trial Registry) as #ChiCTR-OCH-12002490.

Current and emerging strategies for the prevention of graft-versus-host disease

Graft-versus-host disease (GVHD) represents the most serious and challenging complication of allogeneic haematopoietic stem-cell transplantation (HSCT). New insights on the role of regulatory T-cells, T cells, and antigen-presenting cells have led to an improved understanding of the pathophysiology of GVHD. However, little progress has been made since the introduction of calcineurin-inhibitor-based regimens in the mid-1980s. Despite standard prophylaxis with these regimens, GVHD still develops in approximately 40-60% of recipients. Thus, there is a need for developing newer approaches to mitigate GVHD, which may facilitate the use of allogeneic HSCT for the treatment of a wider range of haematological cancers. We discuss the rationale, clinical evidence, and outcomes of current (and widely employed) strategies for GVHD prophylaxis, namely calcineurin-inhibitor-based regimens (such as cyclosporine or tacrolimus) combined with methotrexate or mycophenolate mofetil. We assess the clinical evidence for emerging approaches in the prevention of GVHD, including therapies targeting T cells or B cells, the use of mesenchymal stem cells, chemo-cytokine antagonists (such as maraviroc, TNF-α inhibitor, IL-2 receptor antagonist, IL-6 inhibitor), and the use of novel molecular regulators that target multiple cell types simultaneously, including atorvastatin, bortezomib, and epigenetic modulators.

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.

Donor choice according to age for allo-SCT for AML in complete remission

In a retrospective study of 168 patients with AML in CR who underwent allo-SCT, we compare the impact of young unrelated donors (UD) vs older matched related donors (MRD) on 5-year OS (5-yr OS). Median follow-up was 59 months and median donor age was 39 years, which was used as cutoff for young vs older donors. Kaplan-Meier-estimated 5-yr OS was better with UD ≤39 years vs MRD >39 years (66% vs 34%, P=0.001). In multivariate analysis, only donor age and cytogenetic risk impacted 5-yr OS. Compared with UD ≤39 years, both MRD >39 years (relative risk (RR): 4.31, P=0.001) and UD >39 years (RR: 2.14, P=0.03) were associated with poorer 5-yr OS. Standard-risk cytogenetics was associated with better 5-yr OS compared with bad-risk cytogenetics, (RR: 0.53, P=0.02). Subgroup analyses of patients ≥50 years (n=76) revealed similar results, with 5-yr OS of 62% for UD ≤39 yrs and 26% for MRD >39 yrs (P=0.022). In patients undergoing allo-HSCT for AML, young UD may improve outcome as compared with older MRD.

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.

Course and management of allogeneic stem cell transplantation in patients with mitochondrial neurogastrointestinal encephalomyopathy

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder caused by mutations in the gene encoding thymidine phosphorylase (TP). Allogeneic hematopoietic stem cell transplantation (HSCT) has been proposed as a treatment for patients with MNGIE and a standardized approach to HSCT in this condition has recently been developed. We report on the transplant course, management and short-term follow-up in two MNGIE patients who underwent HSCT. The source of stem cells was bone marrow taken from an HLA 9/10 allele-matched unrelated donor in the first patient and from an HLA 10/10 allele-matched sibling donor in the second. Both patients achieved full donor chimerism, and we observed restoration of buffy coat TP activity and lowered urine nucleoside concentrations in both of them. The post-transplant clinical follow-up showed improvement in gastrointestinal dysmotility, abdominal cramps and diarrhea. Neurological assessment remained unchanged. However, the first patient died 15 months after HSCT due to gastrointestinal obstruction and shock; the second patient died 8 months after the procedure due to respiratory distress following septic shock. Although HSCT corrects biochemical abnormalities and improves gastrointestinal symptoms, the procedure can be risky in subjects already in poor medical condition as are many MNGIE patients. Since transplant-related morbidity and mortality increases with progression of the disease and number of comorbidities, MNGIE patients should be submitted to HSCT when they are still relatively healthy, in order to minimize the complications of the procedure. Anyway, there is still incomplete knowledge on the natural history of the disease in many affected patients and it is not yet clear when the best time to do a transplant is. Further clues to the therapeutic potential of HSCT could result from a prolonged observation in a greater number of non-transplanted and transplanted patients, which would allow us to answer the questions of if, how and when MNGIE patients require HSCT treatment.

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.

Clinical effect of reduced-intensity conditioning regimen containing antithymocyte globulin for hematopoietic cell transplantation from unrelated-donors

The impact of reduced-intensity conditioning (RIC) on the outcomes of hematopoietic cell transplantation (HCT) from unrelated -donors (UD) remains to be determined. We therefore assessed 128 patients, aged 16 to 66 years, with acute leukemia (n = 105) or myelodysplastic syndrome (n = 23) in a UD-HCT trial using RIC with busulfan, fludarabine, and antithymocyte globulin. Patients were transplanted with unmanipulated bone marrow (BM, n = 41) or mobilized peripheral blood mononuclear cells (M-PB, n = 87) and received cyclosporine and methotrexate for graft-versus-host disease (GVHD) prophylaxis. After a median follow-up of 26.7 months (range, 5.9-70.7 months) in surviving patients, 19 patients had died without progression/recurrence of underlying disease, giving a cumulative incidence of transplantation-related mortality (TRM) of 17% (95% confidence interval, 11%-27%; 1-year TRM, 14%). Graft failure (n = 7) and infections (n = 5) were the most common causes of TRM. Only three patients died due to GVHD (acute, one; chronic, two). Graft failure, which occurred in eight patients, showed a significant correlation with graft source (BM, 6/41 vs. M-PB, 2/87; P = 0.009). Donor-patient HLA-disparity did not correlate with GVHD, 1-year TRM, and graft failure. RIC containing antithymocyte globulin led to decreased GVHD-associated, as well as overall, TRM after UD-HCT.

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.

Reduced-intensity conditioning for alternative donor hematopoietic stem cell transplantation in patients with dyskeratosis congenita

DC is an inherited bone marrow failure syndrome mainly characterized by nail dystrophy, abnormal skin pigmentation, and oral leukoplakia. Bone marrow failure is the most common cause of death in patients with DC. Because previous results of HSCT with a myeloablative regimen were disappointing, we used a reduced-intensity conditioning regimen for two patients with classic DC, and one patient with cryptic DC who harbored the TERT mutation. Graft sources included two mismatched-related bone marrow (BM) donors and one unrelated BM donor. Successful engraftment was achieved with few regimen-related toxicities in all patients. They were alive 10, 66, and 72 months after transplantation, respectively. Long-term follow-up is crucial to determine the late effects of our conditioning regimen.

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.

Antithymocyte globulins and chronic graft-vs-host disease after myeloablative allogeneic stem cell transplantation from HLA-matched unrelated donors: a report from the Sociéte Française de Greffe de Moelle et de Thérapie Cellulaire

This retrospective report assessed the impact of rabbit antithymocyte globulins (ATG), incorporated within a standard myeloablative conditioning regimen prior to allogeneic stem cell transplantation (allo-SCT) using human leukocyte antigen-matched unrelated donors (HLA-MUD), on the incidence of acute and chronic graft-vs-host disease (GVHD). In this series of leukemia patients, 120 patients (70%) did not receive ATG ('no-ATG' group), whereas 51 patients received ATG ('ATG' group). With a median follow-up of 30.3 months, the cumulative incidence of grade 3-4 acute GVHD was 36% in the no-ATG group and 20% in the ATG group (P = 0.11). The cumulative incidence of extensive chronic GVHD was significantly lower in the ATG group as compared to the no-ATG group (4 vs 32%, respectively; P = 0.0017). In multivariate analysis, the absence of use of ATG was the strongest parameter associated with an increased risk of extensive chronic GVHD (relative risk) = 7.14, 95% CI: 1.7-33.3, P = 0.008). At 2 years, the probability of nonrelapse mortality, relapse, overall and leukemia-free survivals was not significantly different between the no-ATG and ATG groups. We conclude that the addition of ATG to GVHD prophylaxis resulted in decreased incidence of extensive chronic GVHD without an increase in relapse or nonrelapse mortality, and without compromising survival after myeloablative allo-SCT from HLA-MUD.

Hematopoietic stem cell transplantation in patients with severe congenital neutropenia: an analysis of 18 Japanese cases

We studied the outcome of allogeneic HSCT in patients with SCN. Between 1989 and 2005, 18 patients with SCN in Japan received HSCT for reasons other than malignant transformation, i.e., because of the lack of or a partial response to treatment with r-HuG-CSF. The median age of the patients at the first HSCT was three and a half yr (range 0.2-16.7 yr). Nine patients received stem cells from an HLA-identical sibling donor and nine from an alternative donor. Twelve and six patients received myeloablative and non-myeloablative conditioning regimens, respectively. Engraftment occurred at the first HSCT in 12 patients, four patients received a second HSCT for graft failure, and two patients died. The cause of death was renal failure and graft failure at the first and second HSCT, respectively. The cumulative incidence of grade II-IV acute GVHD and TRM at the first transplantation was 11% and 5.6%, respectively. Of our patients, 16 are alive and in complete remission, with a median follow-up of six and a half yr. Our results suggest that HSCT is beneficial for patients with SCN refractory to r-HuG-CSF treatment.

NCI First International Workshop on the Biology, Prevention, and Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation: report from the Committee on the Epidemiology and Natural History of Relapse following Allogeneic Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is increasingly being used for treatment of hematologic malignancies, and the immunologic graft-versus-tumor effect (GVT) provides its therapeutic effectiveness. Disease relapse remains a cause of treatment failure in a significant proportion of patients undergoing alloHSCT without improvements over the last 2-3 decades. We summarize here current data and outline future research regarding the epidemiology, risk factors, and outcomes of relapse after alloHSCT. Although some factors (eg, disease status at alloHSCT or graft-versus-host disease [GVHD] effects) are common, other disease-specific factors may be unique. The impact of reduced-intensity regimens on relapse and survival still need to be assessed using contemporary supportive care and comparable patient populations. The outcome of patients relapsing after an alloHSCT generally remains poor even though interventions including donor leukocyte infusions can benefit some patients. Trials examining targeted therapies along with improved safety of alloHSCT may result in improved outcomes, yet selection bias necessitates prospective assessment to gauge the real contribution of any new therapies. Ongoing chronic GVHD (cGVHD) or other residual post-alloHSCT morbidities may limit the applicability of new therapies. Developing strategies to promptly identify patients as alloHSCT candidates, while malignancy is in a more treatable stage, could decrease relapses rates after alloHSCT. Better understanding and monitoring of minimal residual disease posttransplant could lead to novel preemptive treatments of relapse. Analyses of larger cohorts through multicenter collaborations or registries remain essential to probe questions not amenable to single center or prospective studies. Studies need to provide data with detail on disease status, prior treatments, biologic markers, and posttransplant events. Stringent statistical methods to study relapse remain an important area of research. The opportunities for improvement in prevention and management of post-alloHSCT relapse are apparent, but clinical discipline in their careful study remains important.

Low-dose total body irradiation and fludarabine conditioning for HLA class I-mismatched donor stem cell transplantation and immunologic recovery in patients with hematologic malignancies: a multicenter trial

HLA-mismatched grafts are a viable alternative source for patients without HLA-matched donors receiving ablative hematopoietic cell transplantation (HCT), although their use in reduced intensity conditioning (RIC) or nonmyeloablative (NMA) conditioning HCT has been not well established. Here, we extended HCT to recipients of HLA class I-mismatched grafts to investigate whether NMA conditioning can establish stable donor engraftment. Fifty-nine patients were conditioned with fludarabine (Flu) 90 mg/m(2) and 2 Gy total body irradiation (TBI), followed by immunosuppression with cyclosporine (CsA) 5.0 mg/kg twice a day and mycophenolate mofetil (MMF) 15 mg/kg 3 times a day for transplantation of granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood stem cells (PBSCs) from related (n = 5) or unrelated donors (n = 54) with 1 antigen +/- 1 allele HLA class I mismatch or 2 HLA class I allele mismatches. Sustained donor engraftment was observed in 95% of the evaluable patients. The incidence of grade II-IV acute and extensive chronic graft-versus-host disease (aGVHD, cGVHD) was 69% and 41%, respectively. The cumulative probability of nonrelapse mortality (NRM) was 47% at 2 years. Two-year overall and progression-free survival (OS, PFS) was 29% and 28%, respectively. NMA conditioning with Flu and low-dose TBI, followed by HCT using HLA class I-mismatched donors leads to successful engraftment and long-term survival; however, the high incidence of aGVHD and NRM needs to be addressed by alternate GVHD prophylaxis regimens.

A novel GVHD-prophylaxis with low-dose alemtuzumab in allogeneic sibling or unrelated donor hematopoetic cell transplantation: the feasibility of deescalation

Prophylaxis of acute graft-versus-host disease (aGVHD), while maintaining the graft-versus-leukemia (GVL)/lymphoma effect and preventing severe infectious diseases, remains the main challenge in allogeneic hematopoetic cell transplantation (allo-HCT). To evaluate this, we examined the feasibility of deescalating the dose of alemtuzumab (MabCampath) in combination with cyclosporine (CsA) as the sole GVHD-prophylaxis in patients after fludarabine (Flu)-based reduced-intensity conditioning (RIC) in an observational cohort study. We included 127 consecutive patients (median age 63 years) with an unrelated (UD; n=69) or related donor (SIB; n=58) after their first transplantation, mostly presenting with advanced disease. The first 30 patients received 20 mg/day on day -2 and -1 (40 mg), the following 48 patients 10 mg/day on day -2 and -1 (20 mg), and the last 49 patients 10 mg on day -1 (10 mg) alemtuzumab intravenous (i.v.) prior to transplant. We observed no statistical differences comparing the 40 mg, 20 mg, or 10 mg dose groups, in terms of cumulative incidences of aGVHD grade III-IV 7% (confidence interval [CI] 95%; 1-51), 12% (1-40), 6% (1-40), extensive chronic GVHD (cGVHD) 24.4% (3.3-55.8), 17% (2.5-42), and 14.2% (1.5-41.5) and of aGVHD grade II-IV 7 % (0-51.5), 29% (11.9-49.1), 21% (15.3-43.1), respectively. The difference between the 20-mg and 40-mg groups was significant for aGVHD grade II-IV(P < .05). In conclusion, we demonstrate the feasibility of reducing the dose of alemtuzumab as GVHD-prophylaxis to 10 mg absolute in combination with CsA only for UD transplantation in particular.

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.

Role of HLA in hematopoietic SCT

HLA disparity between hematopoietic stem cell (HSC) donor and recipient triggers T-cell and NK-cell allorecognition, and induces the GVHD, GVL effect and/or may cause an engraftment failure. This review will cover the scope of human genomic variation, the methods of HLA typing and interpretation of high-resolution HLA results. We describe the main subsets of related and unrelated HSC donors and outline the main aspects of HLA disparity and their effect on the outcome of the patients after allogeneic HSC transplantation (HSCT). The HLA match between HSCT donor and recipient is crucial, but for many patients a perfectly matched donor is not available. The HSCT from the alternative mismatched donor with one allele/antigen mismatch (9/10) can be as beneficial as a HSCT from a fully matched donor, especially in younger patients. For the remaining patients, the donors with permissive mismatches may be the option. The permissiveness depends not only on the potential adverse effect of the HLA mismatches, but also on the urgency of the transplantation, the desirable GVL effect and the potential efficacy of the alternative therapy available for the patient.

Acute graft-versus-host disease: differing risk with differing graft sources and conditioning intensity

Acute graft-versus-host disease (aGVHD) is a constant component of allogeneic hematopoietic cell transplantation (HCT), with variations in incidence and severity affected by the graft source, human leukocyte antigen (HLA) compatibility, and the preparative regimen. The graft source - related versus unrelated donors, bone marrow (BM) versus peripheral blood (PB), umbilical cord blood (UCB) versus unrelated donor BM - are discussed in this review, as well as myeloablative versus reduced-intensity (RI) preparative regimens. Recent comparisons of matched related versus matched unrelated donor HCT support a minimal difference in aGVHD between these two donor sources. The use of BM versus mobilized PB in the matched related donor (MRD) setting has been compared in randomized as well as phase-II comparative clinical trials which support a slight increase in aGVHD in the adult population. Similar results have been seen in the unrelated donor (URD) setting, although based on minimal comparative data to date. Preliminary comparisons of UCB versus URD BM have shown a decreased incidence of aGVHD with UCB, despite increased HLA mismatching. Haploidentical HCT has continued to be explored, with limitations due to delayed immune reconstitution and disease relapse. Many reduced-intensity preparative regimens have been published, with a reduced or minimal difference in incidence of aGVHD when historically compared to myleoablative preparative regimens. More formal comparisons of the different graft sources as well as preparative regimen intensities will be required to determine a more accurate picture of the differences between these transplantation alternatives.

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.

A fludarabine, thiotepa reduced toxicity conditioning regimen designed specifically for allogeneic second haematopoietic cell transplantation after failure of previous autologous or allogeneic transplantation

We present a phase II study of fludarabine 5 x 30 mg/m(2), thiotepa 3 x 5 mg/kg as preparative regimen specifically for allogeneic second haematopoietic stem cell transplantation (HCT) after failure of previous HCT. Forty-nine patients (median age 52 years, range 27-68) received an allogeneic second HCT after failed autologous (n=29) or allogeneic (n=20) HCT. Diagnoses were AML (n=18), ALL (n=3), multiple myeloma (n=11), lymphoma (n=16) and CML (n=1). GVHD prophylaxis consisted of CYA and mainly low dose alemtuzumab (40 mg). The median follow-up for patients alive is 528 days (range 217-1344). In 43 of 49 (88%) evaluable patients response rates were CR=19, PR=14 and SD=10 at one month. At one year, the probability (95% confidence interval) of relapse is 55.1 (38.2-72)% and the nonrelapse mortality (NRM) is 29 (14.2-44.4)%. Estimated survival at one year is 42.6 (28.7-56.6)% and event free survival is 38.1 (24.4-51.8)%. Survival was significantly better for patients experiencing relapse beyond one year, than for patients relapsing within one year from first transplantation (51.2 (33.5-68.9)% vs 27 (7-48.5)%; P=0.013). We conclude that this regimen is feasible and well tolerated for allogeneic second HCT.

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.