Features of Epstein-Barr Virus (EBV) reactivation after reduced intensity conditioning allogeneic hematopoietic stem cell transplantation

Epstein-Barr virus as a potentiator of autoimmune diseases

The Epstein-Barr virus (EBV) is epidemiologically associated with development of autoimmune diseases, including systemic lupus erythematosus, Sjögren syndrome, rheumatoid arthritis and multiple sclerosis. Although there is well-established evidence for this association, the underlying mechanistic basis remains incompletely defined. In this Review, we discuss the role of EBV infection as a potentiator of autoimmune rheumatic diseases. We review the EBV life cycle, viral transcription programmes, serological profiles and lytic reactivation. We discuss the epidemiological and mechanistic associations of EBV with systemic lupus erythematosus, Sjögren syndrome, rheumatoid arthritis and multiple sclerosis. We describe the potential mechanisms by which EBV might promote autoimmunity, including EBV nuclear antigen 1-mediated molecular mimicry of human autoantigens; EBV-mediated B cell reprogramming, including EBV nuclear antigen 2-mediated dysregulation of autoimmune susceptibility genes; EBV and host genetic factors, including the potential for autoimmunity-promoting strains of EBV; EBV immune evasion and insufficient host responses to control infection; lytic reactivation; and other mechanisms. Finally, we discuss the therapeutic implications and potential therapeutic approaches to targeting EBV for the treatment of autoimmune disease.

Increased Epstein‒Barr virus reactivation following prophylaxis for cytomegalovirus infection after haploidentical haematopoietic stem cell transplantation

Letermovir (LTV) prophylaxis is effective in reducing the incidence of clinically significant cytomegalovirus (CMV) infection (cs CMVi) after allogeneic haematopoietic stem cell transplantation (allo-HSCT). Since our centre began administering LTV prophylaxis in June 2022, we have observed a certain increase in the incidence of Epstein-Barr virus (EBV) reactivation after haploidentical HSCT. We retrospectively analysed 230 consecutive patients who underwent haploidentical HSCT with rabbit anti-thymocyte globulin (ATG) from October 2022 to June 2023. The LTV group included 133 patients who received LTV prophylaxis, and the control group included 97 patients who did not receive LTV prophylaxis. At 1 year after HSCT, EBV reactivation was observed in 36 patients (27%) in the LTV group and 13 patients (13%) in the control group (p = 0.012). All patients with EBV reactivation had EBV-DNAemia, and one patient in each group developed EBV-associated posttransplantation lymphoproliferative disorder (PTLD). The proportion of patients with low EBV-DNA loads (> 5 × 102 to < 1 × 104 copies/mL) was greater in the LTV group than in the control group (23% vs. 10%, p = 0.01). The proportion of patients with CMV reactivation was lower in the LTV group than in the control group (35% vs. 56%, p = 0.002). There was no significant difference between the groups in terms of neutrophil and platelet count recovery, the cumulative incidence of acute/chronic graft-versus-host disease, overall survival, cumulative relapse rate or nonrelapse mortality. Our results show that the increased incidence of EBV reactivation may be associated with LTV prophylaxis for CMV after haploidentical HSCT.

Post-transplant cyclophosphamide versus anti-thymocyte globulin after reduced intensity peripheral blood allogeneic cell transplantation in recipients of matched sibling or 10/10 HLA matched unrelated donors: final analysis of a randomized, open-label, multicenter, phase 2 trial

The use of post-transplantation cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis is not established after reduced intensity conditioning (RIC) hematopoietic stem cell transplantation (HSCT) from fully matched donors. This was a randomized, open-label, multicenter, phase 2 trial. All patients received a RIC regimen with fludarabine, intravenous busulfan for 2 days (Flu-Bu2), and a peripheral blood stem cell (PBSC) graft from a matched related or 10/10 HLA-matched unrelated donor. Patients were randomly assigned to receive anti-thymocyte globulin (ATG) 5 mg/kg plus standard GVHD prophylaxis or PTCy 50 mg/kg/d at days +3 and +4 plus standard GVHD prophylaxis. The primary endpoint was the composite endpoint of GVHD- and relapse-free survival (GRFS) at 12 months after HSCT. Eighty-nine patients were randomly assigned to receive either PTCy or control prophylaxis with ATG. At 12 months, disease-free survival was 65.9% in the PTCy group and 67.6% in the ATG group (P = 0.99). Cumulative incidence of relapse, non-relapse mortality, and overall survival were also comparable in the two groups. GRFS at 12 months was 54.5% in the PTCy group versus 43.2% in the ATG group (P = 0.27). The median time to neutrophil and platelet count recovery was significantly longer in the PTCy group compared to the ATG group. Except for day +30, where EORTC QLQ-C30 scores were significantly lower in the PTCy compared to the ATG group, the evolution with time was not different between the two groups. Although the primary objective was not met, PTCy is effective for GVHD prophylaxis in patients receiving Flu-Bu2 conditioning with a PBSC graft from a fully matched donor and was well tolerated in term of adverse events and quality of life. This trial was registered at clinicaltrials.gov: NCT02876679.

Early T-cell reconstitution predicts risk of EBV reactivation after allogeneic hematopoietic stem cell transplantation

The quality of immune reconstitution (IR) is crucial for the outcome of patients who received allogeneic hematopoietic stem cell transplantation (allo-HSCT), and is closely connected with infection, relapse and graft-versus-host disease (GvHD) which are the most important causes for transplantation failure. However, the IR pattern in the early stage after allo-HSCT, particularly haploidentical (HID) HSCT, remains unclear. In this retrospective study, we examined the T cell reconstitution of patients within the initial 30 days (n = 173) and 100 days (n = 122) after allo-HSCT with myeloablative condition (MAC), of which > 70% were HID HSCT, to assess the influence of IR on the transplant outcomes. By comparing 78 patients with good IR (GIR) to 44 patients with poor IR (PIR), we observed that GIR was associated with lower risk for Epstein-Barr virus (EBV) reactivation and cytomegalovirus (CMV) reactivation, but had no significant impacts on the survival outcomes (i.e., overall survival, event-free survival) and cumulative incidences of GvHD. Importantly, we found lymphocyte reconstitution pattern at day 30 after allo-HSCT would be a surrogate for IR evaluated at day 100. In the Cox proportional hazard model, early reconstitution of CD4+, CD4+CD25+, CD4+CD45RO+, CD4+CD25+CD27low, and CD8+ T cells at day 30 was reversely correlated with risk of EBV reactivation. Finally, we constructed a predictive model for EBV reactivation with CD8+ and CD4+CD45RO+ T cell proportions of the training cohort (n = 102), which was validated with a validation cohort (n = 37). In summary, our study found that the quality of IR at day 30 had a predictive value for the risk of EBV reactivation, and might provide guidance for close monitoring for EBV reactivation.

T-Cell Posttransplant Lymphoproliferative Disorders After Allogeneic Hematopoietic Stem Cell Transplantation: Case Series and Systemic Review

Posttransplant lymphoproliferative disorder (PTLD) is a rare lymphoid and/or plasmocytic proliferation that occurs after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We aimed to identify the pathologic features and clinical outcomes of T-cell PTLD, an extremely rare subtype of PTLD, after allo-HSCT. In this study, six allo-HSCT recipients with T-cell PTLD from five transplant centers in China were enrolled. All the T-cell PTLD were donor-derived, and three patients were with monomorphic and three with polymorphic types, respectively. All patients received cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP)-based chemotherapy. Five patients achieved complete response (CR), and one experienced progressive disease (PD). The median time from HSCT to onset was 4 (range: 0.6-72) months, analyzed in combination with the other 16 patients with T-cell PTLD identified from previous reports. About 56.3% of the T-cell samples (9/16) were positive for in situ hybridization with an Epstein-Barr virus (EBV)-encoded small nuclear early region (EBER ISH). CHOP-based chemotherapy might be the optimal strategy for patients who showed no response to empiric therapy with a CR rate of 87.5%. In conclusion, our study observed that T-cell PTLD has distinct clinical manifestations and morphological features, which characterized by less relation to EBV, later occurrence, and poorer prognosis when compared with B-cell PTLD.

Immune reconstitution and survival of patients after allogeneic hematopoietic stem cell transplantation from older donors

BACKGROUND

The impact of donor age on the immune reconstitution of patients with hematological malignancies who underwent hematopoietic cell transplantation (HCT) is unclear.

METHOD

We retrospectively compared the outcomes of 381 patients who underwent allogeneic peripheral blood stem cell transplantation (PBSCT) from 308 donors under 50 years of age and 73 donors over 50 years of age. IVIG was regularly supplemented for patients in the first 3 months post-HCT.

RESULTS

The counts of CD8+CD45RA+ naïve T cells were significantly lower in patients of the older donor group than in the younger donor group in the first year after PBSCT (190.6 cells/μl vs. 239.6 cells/μl, p = .018). Patients in the older donor group had significantly fewer CD19+ B cells on day +270 (123.4 cells/μl vs. 183.5 cells/μl, p = .021) and day +365 (169 cells/μl vs. 271.1 cells/μl, p = .01) after PBSCT. Serum IgA (.76 g/L vs. .97 g/L, p < .001) and IgM levels (.75 g/L vs. 1.04 g/L, p < .001) were significantly lower in patients in the older donor group from day +60 to +365 after PBSCT. The EBV reactivation rate within the first 3 months after PBSCT was significantly higher in patients in the older donor group (48.6% vs. 38.3%, p = .034). However, the incidences of CMV reactivation, II-IV acute graft-versus-host disease (aGvHD), chronic GvHD (cGvHD), 3-year relapse rate, 3-year transplant-related mortality (TRM) and 3-year overall survival (OS) were not significantly different between the two groups.

CONCLUSION

In conclusion, donors ≥50 years old were associated with inferior immune reconstitution and higher EBV reactivation in patients after PBSCT, but no change in OS.

Features of Epstein-Barr Virus and Cytomegalovirus Reactivation in Acute Leukemia Patients After Haplo-HCT With Myeloablative ATG-Containing Conditioning Regimen

Background

Haploidentical donor hematopoietic cell transplantation (haplo-HCT) has become a preferred option for patients without HLA-matched donors, but it increases the risk of viral reactivations. Epstein-Barr virus (EBV) and cytomegalovirus (CMV) are common viruses post-HCT, but limited data have been reported in the setting of haplo-HCT.

Methods

We conducted a retrospective study enrolling acute leukemia patients who received haplo-HCT with myeloablative conditioning regimen employing ATG in our center from July 2014 to July 2017. All the patients enrolled were EBV-IgM and EBV-DNA negative but EBV-IgG positive, and so were their donors. The same went for CMV as well.

Results

In total, 602 patients were recruited consisting of 331 with acute myeloid leukemia (AML) and 271 with acute lymphoblastic leukemia (ALL). One-year cumulative incidences of EBV (22.9% ± 2.4% vs. 27.4% ± 2.8%, P = 0.169) and CMV (24.7% ± 2.4% vs. 29.4% ± 2.8%, P = 0.190) reactivation were comparable between AML and ALL. EBV and CMV were independent risk factors for each other. In the AML group, male recipients [HR = 1.275, 95% CI (1.001-1.624), P = 0.049] and acute graft-versus-host disease [HR = 1.592, 95% CI (1.001-2.533), P = 0.049] were independent risk factors for EBV reactivation and CMV reactivation, respectively. CMV rather than EBV reactivation was related to a trend of worsened treatment-related mortality (TRM) (15.6% ± 0.1% vs. 10.2% ± 0.0%, P = 0.067) and progression-free survival (PFS) (60.6% ± 4.1% vs. 70.3% ± 2.3%, P = 0.073), while significant impacts were revealed only in the subgroup analysis. CMV reactivation resulted in a remarkable inferior 2-year overall survival (OS) (64.2% ± 5.7% vs. 77.6% ± 3.2%, P = 0.038) and PFS (55.0% ± 5.9% vs. 71.9% ± 3.4%, P = 0.042) in ALL patients. On the other hand, in the EBV+/CMV- subgroup, relapse was lower in ALL patients (8.2% ± 0.2% vs. 32.4% ± 0.8%, P = 0.010) compared with AML patients, which led to a superior 2-year OS (82.0% ± 6.2% vs. 60.3% ± 8.8%, P = 0.016) and PFS (74.5% ± 7.0% vs. 57.5% ± 8.4%, P = 0.036).

Conclusion

We concluded that EBV and CMV reactivations were frequent in acute leukemia patients after haplo-HCT, with possibly distinctive risk factors from HLA-matched HCT. There could be a potential interaction between EBV and CMV, but impacts on transplant outcomes remained complex.

Risk factors for post-transplant Epstein-Barr virus events in pediatric recipients of hematopoietic stem cell transplants

BACKGROUND

Epstein-Barr virus (EBV) can cause severe disease following hematopoietic stem cell transplant (HSCT), including post-transplant lymphoproliferative disorder (PTLD). The objective was to analyze risk factors associated with post-transplant EBV outcomes among pediatric allogeneic HSCT recipients.

METHODS

We used data from 156 pediatric allogeneic HSCT recipients enrolled in the Canadian multicenter TREASuRE study. Cox and Prentice-Williams-Petersen models were used to analyze risk factors for post-transplant EBV events including occurrence and recurrence of EBV DNAemia, increase in EBV viral load (EBV-VL), and preemptive use of rituximab, an effective therapy against PTLD.

RESULTS

Females were at higher risk for increasing EBV-VL (adjusted hazard ratio (HR) = 2.83 [95% confidence intervals (CI): 1.33-6.03]) and rituximab use (HR = 3.08 [1.14-8.30]), but had the same EBV DNAemia occurrence (HR = 1.21 [0.74-1.99]) and recurrence risks (HR=1.05 [0.70-1.58]) compared to males. EBV DNAemia was associated with recipient pre-transplant EBV seropositivity (HR = 2.47 [1.17-5.21]) and with graft from an EBV-positive donor (HR = 3.53 [1.95-6.38]). Anti-thymocyte globulin (ATG) was strongly associated with all EBV outcomes, including the use of rituximab (HR = 5.33 [1.47-19.40]). Mycophenolate mofetil (MMF) significantly decreased the risk of all EBV events including the rituximab use (HR = 0.13 [0.03-0.63]).

CONCLUSION

This study in pediatric allogeneic HSCT patients reveals a reduced risk of all EBV outcomes with the use of MMF. Risk factors for EBV events such as EBV-VL occurrence and recurrence include EBV positivity in the donor and recipient, and use of ATG, whereas risk factors for the most severe forms of EBV outcome (EBV-VL and the use of rituximab) include female sex and ATG use.

Immunosuppressant indulges EBV reactivation and related lymphoproliferative disease by inhibiting Vδ2+ T cells activities after hematopoietic transplantation for blood malignancies

Background

Following the extensive use of immunosuppressive drugs in the clinic, immunosuppression-associated side effects have received increasing attention. Epstein-Barr virus (EBV) reactivation and related lymphoproliferative diseases (LPD) are the lethal complications observed after allogeneic hematopoietic cell transplantation (alloHCT). While studies generally suggest an association between immunosuppressants and EBV reactivation, the effects of specific immunosuppressive drugs and which T-cell subsets mediate these correlations are unclear. Vδ2⁺ T cells are correlated with EBV reactivation after alloHCT. Researchers have not determined whether Vδ2⁺ T-cell activities are affected by immunosuppressants and thereby facilitate EBV reactivation and related LPD.

Methods

A clinical cohort study of 170 patients with hematopoietic malignancies who received haploidentical hematopoietic cell transplantation (haploHCT) was performed to investigate whether the early cessation of mycophenolate mofetil (MMF) decreases EBV reactivation and related LPD and to determine whether this change is associated with the recovery of Vδ2 ⁺ T cells after transplantation. The effects of MMF on the expansion and anti-EBV capacity of Vδ2⁺ T cells were detected in vitro and in an immunodeficient mouse model.

Results

A reduction in the course of MMF significantly improved the recovery of Vδ2⁺ T cells from 30 to 90 days after haploHCT (p=0.002, p=0.042 and p=0.035, respectively), accompanied by a significant decrease in EBV reactivation (from 26% to 13%, p=0.033) and EBV-LPD (from 10.6% to 2.4%, p=0.029). The day-30 Vδ2⁺ T level remained an independent factor for EBV reactivation in patients with different MMF durations (p=0.007). In the in-vitro experiments, MMF inhibited Vδ2⁺ T-cell expansion and its cytotoxicity on EBV-transformed malignant cells. Furthermore, the therapeutic and prophylactic effects of adoptively transferred human Vδ2⁺ T cells were attenuated by the MMF treatment in immunodeficient mice with EBV-LPD.

Conclusions

These results elucidated a negative effect of immunosuppressants on the anti-EBV capacity of Vδ2⁺ T cells. Strategies that appropriately relieve the immunosuppression may improve anti-EBV immunity by increasing the activity of Vδ2⁺ T cells after alloHCT.

The time-dependent effects of early-onset Epstein-Barr viremia on adult acute leukemia patients following allo-HSCT with ATG-containing MAC regimen

Epstein-Barr virus (EBV) viremia is a common complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The purpose of this study was to evaluate the impacts of early-onset EBV viremia in acute leukemia (AL) patients who underwent allo-HSCT with anti-thymocyte globulin (ATG)-containing myeloablative conditioning (MAC) regimen. Two hundred and ninety-six patients were included between January 2013 and December 2015. In 126 patients (42.6%) who developed early-onset EBV viremia, with a median time of 48 (range 18~99) days after allo-HSCT. The cumulative incidence of EBV viremia at 30 and 90 days after allo-HSCT were 4.1 and 39.9%, respectively. Prognostic analysis showed that the adjusted overall survival in early-EBV^pos group was significantly lower than early-EBV^neg group within the first 26.7 months after allo-HSCT [hazard ratio (HR), 1.63, P = 0.012], but significantly higher than those afterward (after 26.7 months: HR 0.11, P = 0.035); for the adjusted event-free survival, early-EBV^pos group was significantly inferior in early-EBV^pos group within the first 10.8 months after transplantation (HR: 1.55, P = 0.042), and this adverse effect was not detected any more after 10.8 months (HR: 0.58, P = 0.107). Compared with early-EBV^neg group after adjusting by aGVHD and CMV viremia, HR for death from transplant-related mortality was 2.78-fold higher in patients with early-EBV viremia in piecewise constant Cox analysis (P = 0.006), and this adverse effect was not detected any more after the cut-point time (HR: 0.67, P = 0.361). No differences in terms of relapse and relapse mortality were observed between early-EBV^pos and early-EBV^neg group (P > 0.05). In conclusion, the impacts on transplant outcomes of early-EBV viremia were time-dependent, which may help to optimize management strategies for early-EBV viremia after allo-HSCT, especially in AL patients with ATG-containing MAC regimen.

Factors Associated with Post-Transplant Active Epstein-Barr Virus Infection and Lymphoproliferative Disease in Hematopoietic Stem Cell Transplant Recipients: A Systematic Review and Meta-Analysis

This systematic review was undertaken to identify risk factors associated with post-transplant Epstein-Barr virus (EBV) active infection and post-transplant lymphoproliferative disease (PTLD) in pediatric and adult recipients of hematopoietic stem cell transplants (HSCT). A literature search was conducted in PubMed and EMBASE to identify studies published until 30 June 2020. Descriptive information was extracted for each individual study, and data were compiled for individual risk factors, including, when possible, relative risks with 95% confidence intervals and/or p-values. Meta-analyses were planned when possible. The methodological quality and potential for bias of included studies were also evaluated. Of the 3362 titles retrieved, 77 were included (62 for EBV infection and 22 for PTLD). The overall quality of the studies was strong. Several risk factors were explored in these studies, but few statistically significant associations were identified. The use of anti-thymocyte globulin (ATG) was identified as the most important risk factor positively associated with post-transplant active EBV infection and with PTLD. The pooled relative risks obtained using the random-effect model were 5.26 (95% CI: 2.92-9.45) and 4.17 (95% CI: 2.61-6.68) for the association between ATG and post-transplant EBV infection and PTLD, respectively. Other risk factors for EBV and PTLD were found in the included studies, such as graft-versus-host disease, type of conditioning regimen or type of donor, but results are conflicting. In conclusion, the results of this systematic review indicate that ATG increases the risk of EBV infection and PTLD, but the link with all other factors is either nonexistent or much less convincing.

Transfusion-related Epstein-Barr virus (EBV) infection: A multicenter prospective cohort study among pediatric recipients of hematopoietic stem cell transplants (TREASuRE study)

BACKGROUND

Epstein-Barr virus (EBV) is carried in the blood of most adults, and transfusion-related infections have been reported. EBV is particularly deleterious in immunosuppressed transplant patients. The aim was to determine if EBV transmission occurred through leukodepleted blood product transfusion in pediatric recipients of hematopoietic stem cell transplants (HSCT).

STUDY DESIGN AND METHODS

This prospective Canadian multi-center cohort study includes 156 allogeneic HSCT pediatric recipients. The association between EBV and transfusion was analyzed using Cox regressions. EBV infection, defined by a PCR+ test in the blood of seronegative recipients of an EBV-negative graft, was monitored in order to correlate the recipient EBV strain with that of the blood donors. EBV genotypes were determined by PCR amplification followed by DNA sequencing at two loci (EBNA3b and LMP1).

RESULTS

No statistically significant associations were found between transfusions and EBV. One case of post-transplant EBV infection was identified among the 21 EBV-seronegative recipients receiving an EBV-negative graft. A total of 22 blood donors were retraced to determine whether the recipient's EBV strain matched that of a donor. One donor strain showed 100% sequence homology at the EBNA3b locus, but differed by one or two point mutations and by a 132-bp deletion at the LMP1 locus. The blood donor in question was alone among the 22 donors to show amplifiable virus in plasma. Blood from this donor readily produced an immortalized lymphoblastoid cell line in culture.

CONCLUSION

While considered a rare event, EBV transmission through transfusion may occur in the context of severe immunosuppression.

High incidence but low mortality of EBV-reactivation and PTLD after alloHCT using ATG and PTCy for GVHD prophylaxis

We explore risk factors and impacts of post-transplant EBV-Reactivation (EBV-R) and PTLD in 270 patients that underwent RIC alloHCT using ATG-PTCy and cyclosporine for GVHD prophylaxis. Twenty-five (12%) patients had probable (n = 7) or proven (n = 18) PTLD. Patients were managed with reduction of immunosuppression and 22 with weekly rituximab (375 mg/m² IV). ORR was 84%; 8 (32%) recipients died, and one-year OS and NRM of patients with PTLD was 59.7% and 37%, respectively. One hundred seventy-two (63.7%) recipients had EBV-R. One-year OS and RFS of patients with EBV-R were 68.2% and 60.6%, and of EBV-Negative patients were 62.1% and 50.1%, respectively. High incidence but low mortality of EBV-R and PTLD was documented. EBV-R induced a protective effect on RFS in multivariable analysis (HR 0.91, p = .011). Therefore, EBV-R may have a protective effect on RFS in this setting. Further research is necessary to evaluate the interplay of EBV-R, immune reconstitution, and post-transplant outcomes.

Post-transplant cyclophosphamide versus antithymocyte globulin in patients with acute myeloid leukemia in first complete remission undergoing allogeneic stem cell transplantation from 10/10 HLA-matched unrelated donors

BACKGROUND

Graft-versus-host disease (GVHD) remains a major contributor to mortality and morbidity after allogeneic stem-cell transplantation (allo-HSCT). The updated recommendations suggest that rabbit antithymocyte globulin or anti-T-lymphocyte globulin (ATG) should be used for GVHD prophylaxis in patients undergoing matched-unrelated donor (MUD) allo-HSCT. More recently, using post-transplant cyclophosphamide (PTCY) in the haploidentical setting has resulted in low incidences of both acute (aGVHD) and chronic GVHD (cGVHD). Therefore, the aim of our study was to compare GVHD prophylaxis using either PTCY or ATG in patients with acute myeloid leukemia (AML) who underwent allo-HSCT in first remission (CR1) from a 10/10 HLA-MUD.

METHODS

Overall, 174 and 1452 patients from the EBMT registry receiving PTCY and ATG were included. Cumulative incidence of aGVHD and cGVHD, leukemia-free survival, overall survival, non-relapse mortality, cumulative incidence of relapse, and refined GVHD-free, relapse-free survival were compared between the 2 groups. Propensity score matching was also performed in order to confirm the results of the main analysis RESULTS: No statistical difference between the PTCY and ATG groups was observed for the incidence of grade II-IV aGVHD. The same held true for the incidence of cGVHD and for extensive cGVHD. In univariate and multivariate analyses, no statistical differences were observed for all other transplant outcomes. These results were also confirmed using matched-pair analysis.

CONCLUSION

These results highlight that, in the10/10 HLA-MUD setting, the use of PTCY for GVHD prophylaxis may provide similar outcomes to those obtained with ATG in patients with AML in CR1.

Epstein-Barr virus reactivation after allogeneic hematopoietic stem cell transplantation: multifactorial impact on transplant outcomes

Epstein-Barr virus (EBV) reactivation after allogeneic hematopoietic cell transplantation (allo-HCT) is one of the major concerns that may lead to fatal EBV diseases. However, updated data are needed because of the remarkable evolution of the HCT protocol and donor selection. We conducted a retrospective study that enrolled 890 allo-HCT recipients. Independent risk factors for EBV reactivation were use of antithymocyte globulin, haploidentical donor, and the presence of chronic graft-versus-host disease. The cumulative incidence of EBV reactivation was 2.9%, 11.7%, 27.3%, and 41.9% for patients with 0, 1, 2, and 3 risk factors, respectively (P < 0.001). Posttransplant lymphoproliferative disorders (PTLDs) occurred in seven patients. EBV reactivation was associated with inferior survival in recipients who survived more than 2 years post-HCT (P < 0.001) but might time-dependently benefit those patients with malignancies by decreasing relapse incidence (P = 0.046). A decreased relapse incidence was observed 1 year after HCT for recipients at first or second remission (P = 0.042) and in the first year post-HCT for recipients with advanced diseases (P = 0.032). We concluded that with current management, PTLDs were efficiently controlled, but EBV reactivation still had a multifactorial impact on transplant outcomes. Multicenter prospective studies are warranted to validate these findings.

Reactivation and dynamics of cytomegalovirus and Epstein-Barr virus after rabbit antithymocyte globulin and cyclosporine for aplastic anemia

OBJECTIVES

This study aimed to identify the natural course of cytomegalovirus (CMV)/Epstein-Barr virus (EBV) after rabbit antithymocyte globulin and cyclosporine (rATG-CsA) for aplastic anemia (AA).

METHODS

In 113 prospectively observed AA patients treated with rATG-CsA, the CMV/EBV cohort was classified into two groups by baseline viremic status: no viremia (CMV-G1, n = 112; EBV-G1, n = 98) and the presence of viremia (CMV-G2, n = 1; EBV-G2, n = 13).

RESULTS

In CMV-G1, the mean CMV load increased up to 3 months but was completely resolved from 6 months. The mean EBV load of EBV-G1 showed a peak at 1 month and then gradually decreased over time but remained detectable throughout the observation period. EBV-G2 showed fluctuating EBV dynamics. With reactivation rates of 38.4% in CMV-G1 and 62.2% in EBV-G1, a longer time to rATG-CsA from diagnosis and a lower absolute lymphocyte count at 1 month from rATG-CsA were significantly associated with CMV and EBV reactivation, respectively. The mean peak CMV and EBV loads of patients with CMV-related (3.5%) and EBV-related (0.9%) diseases were evidently higher than those of the remaining patients without CMV and EBV diseases in the respective cohort.

CONCLUSION

Considering frequent reactivation and distinct courses of CMV/EBV, virologic surveillance is recommended after rATG-CsA for AA.

Comparison of Two Doses of Antithymocyte Globulin in Reduced-Intensity Conditioning Allogeneic Hematopoietic Stem Cell Transplantation

The appropriate dose of antithymocyte globulin (ATG) to be used in reduced-intensity conditioning (RIC) allogeneic hematopoietic stem cell transplantation (allo-HSCT) is yet to be determined. We retrospectively analyzed the outcomes of patients who underwent unrelated or mismatch related RIC allo-HSCT for hematologic malignancies and received r-ATG (4.5 mg/kg, 141 patients) versus R-ATG (6 mg/kg, 216 patients). There was a higher incidence of cytomegalovirus (P < .001) and Epstein-Barr virus viremia (P =.03) in the R-ATG group than in the r-ATG group. The cumulative incidences of acute graft-versus-host disease (aGVHD) grades II to IV at day 180 in the r-ATG and R-ATG groups were 59% and 44% (P = .006) and grades III to IV 20% and 12% (P = .029), respectively. In multivariable models adjusting for disease diagnosis, the risk of aGVHD grades III to IV did not reach statistical significance (P = .087). The respective cumulative incidences of chronic GVHD in the r-ATG and R-ATG groups were 26% and 15% (P = .10), respectively. There were no significant differences in relapse rate (P = .24), nonrelapse mortality (P = .96), progression-free survival (P = .24), overall survival (P = .70), and GVHD-free relapse-free survival (P = .24). In this retrospective analysis, aGVHD incidence was higher in those treated with r-ATG compared with R-ATG, but this did not translate into significant differences of clinical outcome. Given the increasing use of RIC allo-HSCT for treating malignant hematologic conditions, the correct dose and schedule of ATG administration should be defined by prospective randomized controlled trials.

Epstein-Barr virus infection is associated with a higher Child-Pugh score and may predict poor prognoses for patients with liver cirrhosis

BACKGROUND

Studies on Epstein-Barr virus (EBV) have focused mostly on neoplastic disease. Few studies have considered immunocompetent patients who are not severely immunocompromised. Liver cirrhosis is associated with various levels of immune dysfunction. In the current study, we determined EBV infection rates, the influence on liver function, and analyzed the risk factors for death in patients with liver cirrhosis.

METHODS

The medical records of patients diagnosed with liver cirrhosis between 1 January 2014 and 31 December 2016 were reviewed. Patients who were or were not infected with EBV were enrolled in this study. Liver functions were compared. The risk factors for 28-, 90-, and 180-day mortality rates were analyzed by univariate and multivariate logistic regression.

RESULTS

The medical records hospitalized patients diagnosed with liver cirrhosis were reviewed. Of these patients, 97 had assessed EBV deoxyribonucleic acid (DNA) and 36 (37.1%) patients were EBV DNA-positive. The age of the EBV-infected patients was older than patients not infected with EBV. EBV-infected patients had a lower level of albumin, and a lower albumin-to-globulin ratio (P = 0.019 and P = 0.013, respectively). EBV-infected patients had higher Child-Pugh scores (P = 0.033) and higher acute-on-chronic liver failure (ACLF) rate (P = 0.050). The Child-Pugh score and ACLF were the risk factors for the 28-, 90-, and 180-day mortality rates.

CONCLUSIONS

This study revealed that patients with liver cirrhosis had higher EBV infection rates, especially patients > 60 years of age, which likely reflected viral reactivation. And liver injury was aggravated in EBV-infected patients. Thus, EBV infection indirectly influenced the prognosis of EBV-infected patients by increasing the Child-Pugh score and ACLF rate.

Low dose Rituximab for pre-emptive treatment of Epstein Barr virus reactivation after allogenic hematopoietic stem cell transplantation

INTRODUCTION

The most used preemptive therapy for Epstein Barr virus reactivation post allogeneic hematopoietic stem cell (HSCT) transplant is Rituximab, 375 mg/m2, once weekly until EBV viremia negativity. There is no data suggesting such a high dose.

OBJECTIVE

We hypothesized that a lower dose of Rituximab would be as efficient with less toxicity.

PATIENTS

In a retrospective, monocentric study, we analyzed 16 consecutive patients treated preemptively with low dose Rituximab for EBV reactivation post HSCT. Patients were treated with low Rituximab dose of 100 mg/m² weekly. Success was defined by a decrease of EBV viremia of 1 log¹⁰ and below 1000 UI/ml, and the absence of post-transplant lymphoproliferative disorder (PTLD).

RESULTS

Success rate was 93.4% (15/16). One (1/16, 6%) PTLD was diagnosed after preemptive therapy, despite a negative viremia.

CONCLUSION

A low dose of Rituximab of 100 mg/m² per injection for pre-emptive therapy of EBV reactivation post HSCT is safe and effective for preventing PTLD. Prospective, randomized, multicentric trials with larger number of patient are needed to determine the best rituximab dose.

Incidence, risk factors, and clinical significance of Epstein-Barr virus reactivation in myelodysplastic syndrome after allogeneic haematopoietic stem cell transplantation

Epstein-Barr virus (EBV) reactivation is a life-threatening complication after allogeneic haematopoietic stem cell transplantation (allo-HSCT). In this study, we investigated the characteristics of EBV reactivation in 186 consecutive myelodysplastic (MDS) patients who underwent allo-HSCT in our centre. In 35 patients (18.8%) who experienced EBV reactivation after allo-HSCT, the median onset was 53 days (range 4-381 days). The cumulative incidence of EBV reactivation at the first, sixth, and twelfth month after allo-HSCT was 10.7%, 15.1%, and 17.9%, respectively. Twenty-five patients (71.4%) received pre-emptive rituximab therapy, and no patients developed post-transplant lymphoproliferative disorders. Stem cell source was proven to be a risk factor correlated with EBV reactivation. The cumulative incidence of relapse in the EBV-positive group was 11.4%, 25.2%, and 31.0% at the first, second, and third year after transplantation, respectively, being significantly higher than the corresponding 6.8%, 10.2%, and 10.2%, in the EBV-negative group (P = 0.014). Prognostic analysis showed that EBV reactivation was an independent risk factor for relapse-free survival (RFS). Patients in the EBV-positive group showed obviously shorter RFS than those in the EBV-negative group, with 3-year RFS of 62% and 85%, respectively (P = 0.017).

Human cytomegalovirus and Epstein-Barr virus infections, risk factors, and their influence on the liver function of patients with acute-on-chronic liver failure

Background

Studies on human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) have focused primarily on the immunosuppressed population. Few studies have considered immunocompetent and not severely immunocompromised patients. We determined the infection rates of HCMV and EBV, their risk factors and their influence on liver function in patients with HBV-related acute-on-chronic liver failure (ACLF).

Methods

Patients infected with ACLF-based hepatitis B virus (HBV) from 1 December 2016 to 31 May 2018 were enrolled in our study and were divided into infected and uninfected groups. The risk factors for HCMV and EBV infection and their influence on liver function were analysed.

Results

A total of 100 hospitalized patients with ACLF due to HBV infection were enrolled in this study. Of these patients, 5% presented HCMV deoxyribonucleic acid (DNA) and 23.0% presented EBV DNA. An HBV DNA count of < 1000 IU/mL increased the occurrence of HCMV infection (P = 0.003). Age, especially older than 60 years, was a risk factor for EBV infection (P = 0.034, P = 0.033). HCMV-infected patients had lower alanine aminotransferase (ALT) levels; albumin levels and Child–Pugh scores in EBV-infected patients were higher than those in uninfected patients.

Conclusions

HCMV and EBV were detected in patients with ACLF caused by HBV infection. Lower replication of HBV (HBV DNA < 1000 IU/mL) may increase the probability of HCMV infection; age, especially older than 60 years of age, was a risk factor for EBV infection. HCMV infection may inhibit HBV proliferation and did not increase liver injury, while co-infection with EBV may influence liver function and may result in a poor prognosis.

Ex vivo and in vivo T cell-depleted allogeneic stem cell transplantation in patients with acute myeloid leukemia in first complete remission resulted in similar overall survival: on behalf of the ALWP of the EBMT and the MSKCC

Background

Graft-versus-host disease (GVHD) is one of the leading causes of non-relapse mortality and morbidity after allogeneic hematopoietic stem cell transplantation (allo-HCT).

Methods

We evaluated the outcomes of two well-established strategies used for GVHD prevention: in vivo T cell depletion using antithymocyte globulin (ATG) and ex vivo T cell depletion using a CD34-selected (CD34+) graft. A total of 525 adult patients (363 ATG, 162 CD34+) with intermediate or high-risk cytogenetics acute myeloid leukemia (AML) in first complete remission (CR1) were included. Patients underwent myeloablative allo-HCT using matched related or unrelated donors.

Results

Two-year overall survival estimate was 69.9% (95% CI, 58.5–69.4) in the ATG group and 67.6% (95% CI, 60.3–74.9) in the CD34+ group (p = 0.31). The cumulative incidence of grade II–IV acute GVHD and chronic GVHD was higher in the ATG cohort [HR 2.0 (95% CI 1.1–3.7), p = 0.02; HR 15.1 (95% CI 5.3–42.2), p < 0.0001]. Parameters associated with a lower GVHD-free relapse-free survival (GRFS) were ATG [HR 1.6 (95% CI 1.1–2.2), p = 0.006], adverse cytogenetic [HR 1.7 (95% CI 1.3–2.2), p = 0.0004], and the use of an unrelated donor [HR 1.4 (95% CI 1.0–1.9), p = 0.02]. There were no statistical differences between ATG and CD34+ in terms of relapse [HR 1.52 (95% CI 0.96–2.42), p = 0.07], non-relapse mortality [HR 0.96 (95% CI 0.54–1.74), p = 0.90], overall survival [HR 1.43 (95% CI 0.97–2.11), p = 0.07], and leukemia-free survival [HR 1.25 (95% CI 0.88–1.78), p = 0.21]. Significantly, more deaths related to infection occurred in the CD34+ group (16/52 vs. 19/112, p = 0.04).

Conclusions

These data suggest that both ex vivo CD34-selected and in vivo ATG T cell depletion are associated with a rather high OS and should be compared in a prospective randomized trial.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0668-3) contains supplementary material, which is available to authorized users.

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

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

Increased Coexpression of PD-1, TIGIT, and KLRG-1 on Tumor-Reactive CD8+ T Cells During Relapse after Allogeneic Stem Cell Transplantation

Allogeneic stem cell transplantation (allo-SCT) can be a curative treatment for patients with a hematologic malignancy due to alloreactive T cell responses recognizing minor histocompatibility antigens (MiHA). Yet tumor immune escape mechanisms can cause failure of T cell immunity, leading to relapse. Tumor cells display low expression of costimulatory molecules and can up-regulate coinhibitory molecules that inhibit T cell functionality on ligation with their counter-receptors on the tumor-reactive T cells. The aim of this explorative study was to evaluate immune checkpoint expression profiles on T cell subsets and on cytomegalovirus (CMV)- and/or MiHA-reactive CD8⁺ T cells of allo-SCT recipients using a 13-color flow cytometry panel, and to correlate these expression patterns to clinical outcomes. MiHA-reactive CD8⁺ T cells exhibited an early differentiated CD27⁺⁺/CD28⁺⁺ phenotype with low KLRG-1 and CD57 expression. These T cells also displayed increased expression of PD-1, TIM-3, and TIGIT compared with total effector memory T cells and CMV-specific CD8⁺ T cells in healthy donors and allo-SCT recipients. Remarkably, high coexpression of PD-1, TIGIT, and KLRG-1 on MiHA-reactive CD8⁺ T cells was associated with relapse after allo-SCT. Taken together, these findings indicate that MiHA-specific CD8⁺ T cells of relapsed patients have a distinctive coinhibitory expression signature compared with patients who stay in remission. This phenotype may serve as a potential monitoring tool in patients. Moreover, these findings suggest that PD-1 and TIGIT play important roles in regulating T cell-mediated tumor control, providing a rationale for immunotherapy with blocking antibodies to treat relapse after allo-SCT.

Pre-emptive rituximab for Epstein-Barr virus reactivation after haplo-hematopoietic stem cell transplantation

BACKGROUND

Epstein-Barr virus-related post-transplantation lymphoproliferative disease (EBV-PTLD) is a serious complication in hematopoietic stem cell transplantation (HSCT) recipients.

METHODS

We conducted a retrospective study to investigate the incidence and potential risk factors for EBV reactivation and to assess the efficacy of the management of EBV reactivation with pre-emptive rituximab in children who had T-cell-replete haploidentical HSCT (TCR-haplo-SCT) with low-dose anti-thymocyte globulin (ATG). EBV-DNA level in peripheral blood (PB) was measured when suspected EBV reactivation were observed. When the EBV-DNA level in PB increased to >1,000 copies/10⁶ peripheral blood mononuclear cells (PBMC), patients were pre-emptively treated with rituximab (375 mg/m² /dose).

RESULTS

A total of 19 (50%) of 38 patients received rituximab infusion at a median time of 56 days after HSCT (range, 17-270 days). The median viral load at initiation of therapy was 2,900 copies/10⁶ PBMC (range, 1,000-650 000). Pre-emptive therapy was started after a median of 2 days (range, 0-7 days). The median number of weekly treatment cycles was 2 (range, 1-3). None of the patients developed PTLD or other EBV-associated diseases.

CONCLUSION

Pre-emptive rituximab therapy could be a useful strategy for EBV-PTLD in TCR-haplo-SCT recipients with low-dose ATG.

Impact of stem cell graft on early viral infections and immune reconstitution after allogeneic transplantation in adults

BACKGROUND

Viral infections are well-known complications after allogeneic stem cell transplant (allo-SCT).

OBJECTIVES

We compared prospectively incidences of DNAemia and active infections (AI) for five opportunistic viruses (Human Herpesvirus 6 (HHV-6), Epstein-Barr virus (EBV), BK polyomavirus (BKPyV), Cytomegalovirus (CMV) and Adenovirus (ADV)) and kinetics of immune reconstitution (IR) in adults receiving either double umbilical cord blood (dUCB group) or unrelated peripheral blood stem cell (uPBSC group) allo-SCT after a reduced-intensity conditioning (RIC) regimen.

STUDY DESIGN

Whole blood samples were collected at transplant, every 15days during the first 3 months and at 4, 5 and 6 months post-transplant.

RESULTS

Sixty-five patients were enrolled (uPBSC n=34; dUCB n=31). Incidences of HHV-6 and BKPyV DNAemia were significantly higher for dUCB (97% vs 23.5% and 58% vs 32%, respectively) while EBV DNAemia was more frequently detected in uPBSC (71% vs 26%). The incidence of CMV DNAemia was similar between both groups. ADV AI developed only in dUCB. HHV-6 AI were also higher in dUCB (84% vs 21%). In multivariate analysis, dUCB graft was the only independent factor associated with HHV-6 DNAemia (OR: 19.0; 95%CI: 5.2-69.1; p<0.0001) while EBV DNAemia were significantly associated with uPBSC (OR: 29.9; 95%CI: 5.68-158; p <0.0001). dUCB graft was also the only factor associated with HHV-6 AI. Finally, higher counts and faster recoveries of B lymphocytes (p<0.0001) and monocytes (p=0.0007) were observed in the dUCB group.

CONCLUSION

We demonstrate a strong correlation between sources of graft and patterns of viral DNAemia and AI and IR after RIC allo-SCT.

Dynamics of Epstein-Barr viral load after hematopoietic stem cell transplantation and effect of preemptive rituximab therapy

BACKGROUND

Epstein-Barr virus (EBV) displays oncogenic properties, particularly in the immunocompromised host. Notably, hematopoietic stem cell transplantation (HSCT) recipients with a detectable blood EBV viral load (BEBVL) are considered at higher risk of post-transplant lymphoproliferative diseases (PTLD). Therefore, BEBVL is monitored after HSCT, and preemptive rituximab may be used in patients with high values. However, little is known about post-HSCT BEBVL dynamics, and the threshold that should lead to anti-CD20 therapy is poorly defined.

METHODS

We retrospectively analyzed the post-HSCT BEBVL of 332 adult HSCT recipients in our center from 2005 to 2013, including the effect of rituximab.

RESULTS

Detection of BEBVL >100, 1000, 5000, 10 000, and 50 000 copies/mL occurred in, respectively, 77.7%, 69.6%, 37.0%, 27.1%, and 7.5% of the patients after a respective median time of 9, 14, 15, 16, and 14 weeks. No BEBVL threshold was associated with an overall survival difference. Seventy-eight patients received rituximab, with a BEBVL decrease in most. Among patients with detectable BEBVL, long-term survival did not differ in rituximab treated and non-treated, except for patients with BEBVL ≥50 000. Only one case of PTLD was observed.

CONCLUSIONS

BEBVL is frequently detectable after HSCT, but suggests no strong association with survival. Preemptive rituximab therapy threshold remains to be defined.

Immune Reconstitution after Allogeneic Hematopoietic Stem Cell Transplantation

The timely reconstitution and regain of function of a donor-derived immune system is of utmost importance for the recovery and long-term survival of patients after allogeneic hematopoietic stem cell transplantation (HSCT). Of note, new developments such as umbilical cord blood or haploidentical grafts were associated with prolonged immunodeficiency due to delayed immune reconstitution, raising the need for better understanding and enhancing the process of immune reconstitution and finding strategies to further optimize these transplant procedures. Immune reconstitution post-HSCT occurs in several phases, innate immunity being the first to regain function. The slow T cell reconstitution is regarded as primarily responsible for deleterious infections with latent viruses or fungi, occurrence of graft-versus-host disease, and relapse. Here we aim to summarize the major steps of the adaptive immune reconstitution and will discuss the importance of immune balance in patients after HSCT.

Association of Epstein-Barr virus reactivation with the recovery of CD4/CD8 double-negative T lymphocytes after haploidentical hematopoietic stem cell transplantation

EBV infection is one of the life-threatening clinical complications in patients who underwent haploidentical hematopoietic stem cell transplantation (haploHSCT). Although immune recovery is recognized to be crucial for decreasing subsequent morbidity of infections, the link between T-cell recovery and EBV infection after haploHSCT remains elusive. We recently compared the influences of different doses of antithymocyte globulin conditioning on the T-cell reconstitution post haploHSCT and suggested that CD4^-CD8^-T cells might interact with the occurrence of EBV reactivation. In the current study, haploHSCT recipients with EBV-DNAemia (n=64) were compared with a control group without EBV reactivation (n=192), with regard to the recoveries of T-cell subpopulations. In contrast to other T-cell subpopulations, the median counts ofCD4^-CD8^-T cells in recipients with EBV-DNAemia were significantly lower than the control group at a serial time course (30, 90 and 180 days) after transplantation. Landmark studies further confirmed the correlation of CD4^-CD8^-T cells with the EBV infection. Multivariate analysis showed that hampered recovery of CD4^-CD8^-T cells and EBV reactivation were the independent risk factors to predict transplant-related mortality. Our findings may facilitate the intervention strategies to improve the overall survival of haploHSCT recipients.

Herpesvirus infections in hematopoietic stem cell transplant recipients seropositive for human cytomegalovirus before transplantation

BACKGROUND

Viral infections are a major cause of morbidity and mortality after hematopoietic stem cell transplantation (HSCT). The effect of herpesvirus infections in human cytomegalovirus (HCMV)-seropositive (IgG-positive/IgM-negative) HSCT recipients remains poorly understood. The risk factors associated with Epstein-Barr virus (EBV), HCMV, and human herpes virus type 6 (HHV-6) infections after HSCT, both alone and in combination, were investigated in this study.

METHODS

Peripheral blood specimens were collected from 44 HSCT recipients and examined for viral DNA using quantitative fluorescence PCR assays. Risk factors for EBV, HCMV, and HHV-6 infections were analyzed by binary logistic regression, and relationships between these viruses were analyzed using the Chi-square test.

RESULTS

EBV, HCMV, and HHV-6 were detected in 50%, 45.45%, and 25% of HCMV-seropositive (IgG-positive/IgM-negative) HSCT recipients, respectively. Male sex (p=0.007) and conditioning regimens including anti-thymocyte globulin (ATG) (p=0.034) were strongly associated with an increased risk of EBV infection. Graft-versus-host disease (GVHD) prophylaxis with corticosteroids was a risk factor for both EBV (p=0.013) and HCMV (p=0.040) infections, while EBV infection (p=0.029) was found to be an independent risk factor for HHV-6 infection. Pre-existing HHV-6 infection was associated with lower rates of HCMV infection (p=0.002); similarly, pre-existing HCMV infection was protective against HHV-6 infection (p=0.036).

CONCLUSIONS

HCMV-seropositive (IgG-positive/IgM-negative) HSCT recipients exhibited a high rate of herpesvirus infections, particularly EBV. ATG and male sex were strongly associated with an increased risk of EBV infection. GVHD prophylaxis with prednisone was found to affect both EBV and HCMV infections. Prior infection with EBV was shown to promote HHV-6 infection. Taken together, these data highlight the need for active monitoring of herpesvirus infections in patients undergoing HSCT.

Epstein-Barr virus-associated posttransplant lymphoproliferative disorder after allogeneic stem cell transplantation

PURPOSE OF REVIEW

Epstein-Barr virus (EBV)-associated posttransplant lymphoproliferative disorder is an increasingly life-threatening complication after allogeneic stem cell transplantation with the use of more complex transplant procedures.

RECENT FINDINGS

Reduced intensity conditioning regimens in combination with in-vivo or ex-vivo T-cell depletion are particularly important risk factors. Prospective monitoring of EBV viremia by real-time quantitative polymerase-chain reaction (PCR) should be performed after high-risk allogeneic stem cell transplantation. However, lack of standardization and concerns about sensitivity and low positive-predictive value challenge the interpretation of PCR monitoring. Preemptive treatment is feasible and can reduce EBV-related mortality but may lead to overtreatment in some patients. Readily available rituximab and methods of adoptive transfer of T-cells are valuable tools. Rituximab is probably the most attractive agent showing the most robust data in this setting. Rituximab seems to offer a good balance between efficacy and toxicity for the treatment of established EBV-associated posttransplant lymphoproliferative disorder. But most often there is a need to combine with adoptive immunotherapy with T-cells to maintain long-term disease control, with either simple unmanipulated donor lymphocyte infusion or more specific and complex adoptive EBV-specific cytotoxic T-cells.

SUMMARY

EBV-associated posttransplant lymphoproliferative disorder can often be prevented or treated, especially in earlier stages. The specific role and timing of the different treatment strategies need to be defined.

T-cell-replete haploidentical stem cell transplantation is highly efficacious for relapsed and refractory childhood acute leukaemia

BACKGROUND

Despite improvements in first-line therapies, the outcomes of relapsed or refractory childhood acute leukaemia that has not achieved complete remission after relapse, has relapsed after stem cell transplantation (SCT), has primary induction failure and has relapsed with a very unfavourable cytogenetic risk profile, are dismal.

OBJECTIVES AND METHODS

We evaluated the feasibility and efficacy of T-cell-replete haploidentical peripheral blood stem cell transplantation (haplo-SCT) with low-dose anti-human thymocyte immunoglobulin (ATG), tacrolimus, methotrexate and prednisolone (PSL) in 14 paediatric patients with high-risk childhood acute leukaemia.

RESULTS

All patients achieved complete engraftment. The median time to reaching an absolute neutrophil count of more than 0.5 × 10(9) L(-1) was 14 days. Acute graft-vs-host disease (aGVHD) of grades II-IV and III-IV developed in 10 (71%) and 2 (14%) patients, respectively. Treatment-related mortality and relapse occurred in one (7%) patient and six (43%) patients, respectively. Eleven patients were alive and seven of them were disease-free with a median follow-up of 36 months (range: 30-159 months). The probability of event-free survival after 2 years was 50%.

CONCLUSION

These findings indicate that T-cell-replete haplo-SCT, with low-dose ATG and PSL, provides sustained remission with an acceptable risk of GVHD in paediatric patients with advanced haematologic malignancies.

Reduced-toxicity conditioning prior to allogeneic stem cell transplantation improves outcome in patients with myeloid malignancies

The introduction of reduced intensity/toxicity conditioning regimens has allowed allogeneic hematopoietic cell transplantation to be performed in patients who were previously considered too old or otherwise unfit. Although it led to a reduction in non-relapse mortality, disease control remains a major challenge. We studied the outcome of 165 patients with acute myeloid leukemia (n=124) or myelodysplastic syndrome (n=41) transplanted after conditioning with fludarabine (30 mg/m(2)/day for 5 days), intravenous busulfan (either 260 mg/m(2): reduced intensity conditioning, or 390-520 mg/m(2): reduced toxicity conditioning), and rabbit anti-thymoglobulin (2.5 mg/kg/day for 2 days). The median age of the patients at transplantation was 56.8 years. The 2-year relapse incidence was 29% (23% versus 39% for patients transplanted in first complete remission and those transplanted beyond first complete remission, respectively; P=0.008). The 2-year progression-free survival rate was 57% (95% CI: 49.9-65). It was higher in the groups with favorable or intermediate cytogenetics than in the group with unfavorable cytogenetics (72.7%, 60.5%, and 45.7%, respectively; P=0.03). The cumulative incidence of grades 2-4 and 3-4 acute graft-versus-host disease at day 100 was 19.3% and 7.9%, respectively. The cumulative incidence of chronic graft-versus-host disease at 1 year was 21.6% (severe forms: 7.8%). Non-relapse mortality at 1 year reached 11%. The 2-year overall survival rate was 61.8% (95% CI: 54.8-69.7). Unfavorable karyotype and disease status beyond first complete remission were associated with a poorer survival. This well-tolerated conditioning platform can lead to long-term disease control and offers possibilities of modulation according to disease stage or further development.

Continuous reduced nonrelapse mortality after allogeneic hematopoietic stem cell transplantation: a single-institution's three decade experience

This study analyzed changes in patients, transplantation, graft characteristics, and outcome among 827 patients who received their first allo-SCT in a single center between 1983 and 2010. In the 2001 to 2010 decade, compared with the 1983 to 1990 and 1991 to 2000 decades, patients were significantly older and presented with higher risk diseases, reduced intensity conditioning and alternative donors were used more often, and stem cell sources changed from bone marrow to peripheral blood stem cells and cord blood. In the 2001 to 2010 decade, we observed a significant decrease in nonrelapse mortality (NRM) (P = .0007 and P < .0001, respectively) and an increase in relapse incidence (P = .04 and P = .009, respectively), but overall survival (OS) was increased (P = .11 and P = .009, respectively), and there was a trend towards an increased progression-free survival (P = .30 and P = .09, respectively), as compared with the 1983 to 1990 and 1991 to 2000 decades. Chronic graft-versus-host disease (GVHD) was significantly increased, whereas grades III to IV acute GVHD remained stable. These data suggest that, despite the fact that older and higher risk patients with more comorbidities underwent transplantation in the last 10 years, NRM decreased while the incidence of relapse increased and the OS improved.

The targeting of immunosuppressive mechanisms in hematological malignancies

The adaptive immune system has the capacity to recognize and kill leukemic cells. However, immune tolerance mechanisms that normally protect healthy tissues from autoimmune effects prevent the development of effective antitumor immunity. Tumors use several different immunosuppressive mechanisms to evade otherwise effective T-cell responses. A growing number of immune evasion mechanisms have been characterized mainly in solid tumors. In hematological malignancies, less is known about how different immune escape mechanisms influence tumor immune evasion and the extent of their impact on ongoing immune responses. The present review highlights the potential role of three well-defined immunosuppressive mechanisms in hematological malignancies: (i) inhibitory T-cell pathways (especially programmed death ligand 1/programmed death 1 (PD-L1/PD-1)), (ii) regulatory immune cells, and (iii) metabolic enzymes such as indoeamine-2,3-dioxygenase (IDO). The possible therapeutic targeting of these pathways is also discussed. Exciting new strategies that might affect future antileukemia immunotherapy include monoclonal antibodies that block inhibitory T-cell pathways (PD-1/PD-L1) and the prevention of tryptophan depletion by IDO inhibitors. Furthermore, the clinical effect of several chemotherapeutic drugs may arise from the targeting of immunosuppressive cells. Evidence for a new feedback mechanism to suppress the function of regulatory immune cells was recently provided by the identification and characterization of spontaneous cytotoxic T lymphocyte (CTL) responses against regulatory immune cells. Such specific CTLs may be immensely useful in anticancer immunotherapy (for example, by anticancer vaccination). The targeting of one or more immunosuppressive pathways may be especially interesting in combination with antileukemic immunotherapy in cases in which immunosuppressive mechanisms antagonize the desired effects of the therapy.

Stable long-term pulmonary function after fludarabine, antithymocyte globulin and i.v. BU for reduced-intensity conditioning allogeneic SCT

Lung function decline is a well-recognized complication following allogeneic SCT (allo-SCT). Reduced-intensity conditioning (RIC) and in vivo T-cell depletion by administration of antithymocyte globulin (ATG) may have a protective role in the occurrence of late pulmonary complications. This retrospective study reported the evolution of lung function parameters within the first 2 years after allo-SCT in a population receiving the same RIC regimen that included fludarabine and i.v. BU in combination with low-dose ATG. The median follow-up was 35.2 months. With a median age of 59 years at the time of transplant, at 2 years, the cumulative incidences of non-relapse mortality was as low as 9.7%. The cumulative incidence of relapse was 33%. At 2 years, the cumulative incidences of extensive chronic GVHD (cGVHD) and of pulmonary cGVHD were 23.1% and 1.9%, respectively. The cumulative incidences of airflow obstruction and restrictive pattern were 3.8% and 9.6%, respectively. Moreover, forced expiratory volume (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio remained stable from baseline up to 2 years post transplantation (P=0.26, P=0.27 and P=0.07, respectively). These results correspond favorably with the results obtained with other RIC regimens not incorporating ATG, and suggest that ATG may have a protective pulmonary role after allo-SCT.

Controlled Epstein-Barr virus reactivation after allogeneic transplantation is associated with improved survival

Epstein-Barr virus reactivation (EBV-R) frequently occurs in patients having allogeneic hematopoietic stem cell transplantation (HSCT). We evaluated the impact of controlled EBV-R on survival of 190 patients (114M/76F, median age: 51 yr, range 18-69), having HSCT for hematological malignancies (105 acute leukemias and myelodysplasias, 71 lymphoproliferative disorders, 14 others). Overall survival (OS) and progression-free survival (PFS) were compared between patients with and without EBV-R. Of 138, patients had reduced-intensity conditioning regimen. Various stem cell sources (141 PB, 33 umbilical cord blood and 16 bone marrow) were used. Patients with EBV-R had longer PFS and OS than those without EBV-R: PFS at 2 yr 69% vs. 51% and at 5 yr 47% vs. 38% (P < 0.04); OS at 2 yr 76% vs. 64% and at 5 yr 63% vs. 47%) (P < 0.001). The use of rituximab had no impact on OS and PFS, but it reduced the intensity of GVHD, despite the fact that TRM was not significantly different between the two groups of patients. So, rituximab may have an additional effect to other factors on PFS and OS. In multivariate analysis, antithymocyte globulin administration was not a significant factor for PFS (P = 0.68) and for OS (P = 0.81). Circulating NK cells were significantly increased by 22% (P = 0.03) in EBV-R patients with no differences for other parameters. Controlled EBV-R in the setting of HSCT is associated with better OS and PFS, with a significant increase in circulating NK cells.

Diagnosis and treatment of viral diseases in recipients of allogeneic hematopoietic stem cell transplantation

Viral infections are important causes of morbidity and mortality after allogeneic stem cell hematopoietic transplantation (allo-HSCT). Although most viral infections present with asymptomatic or subclinical manifestations, viruses may result in fatal complications in severe immunocompromised recipients. Reactivation of latent viruses, such as herpesviruses, is frequent during the immunosuppression that occurs with allo-HSCT. Viruses acquired from community, such as the respiratory and gastrointestinal viruses, are also important pathogens of post-transplant viral diseases. Currently, molecular diagnostic methods have replaced or supplemented traditional methods, such as viral culture and antigen detection, in diagnosis of viral infections. The utilization of polymerase chain reaction facilitates the early diagnosis. In view of lacking efficacious agents for treatment of viral diseases, prevention of viral infections is extremely valuable. Application of prophylactic strategies including preemptive therapy reduces viral infections and diseases. Adoptive cellular therapy for restoring virus-specific immunity is a promising method in the treatment of viral diseases.

Risk factors for Epstein-Barr virus-related post-transplant lymphoproliferative disease after allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation is a successful treatment for hematologic malignancies and a variety of genetic and metabolic disorders. In the period following stem cell transplantation, the immune-compromised milieu allows opportunistic pathogens to thrive. Epstein-Barr virus-associated post-transplant lymphoproliferative disease can be a life-threatening complication for transplanted patients because of suppressed T-cell-mediated immunity. We analyzed possible risk factors associated with post-transplant lymphoproliferative disease in a cohort of over 1,000 patients. The incidence of post-transplant lymphoproliferative disease was 4%. Significant risk factors identified by multivariate analysis were: human leukocyte antigen-mismatch (P<0.001), serological Epstein-Barr virus mismatch recipient-/donor+ (P<0.001), use of reduced intensity conditioning (P=0.002), acute graft-versus-host disease grade II to IV (P=0.006), pre-transplant splenectomy (P=0.008) and infusion of mesenchymal stromal cells (P=0.015). The risk of post-transplant lymphoproliferative disease has increased in more recent years, from less than 2% before 1998 to more than 6% after 2011. Additionally, we show that long-term survival of patients with post-transplant lymphoproliferative disease is poor despite initial successful treatment. The 3-year survival rate among the 40 patients with post-transplant lymphoproliferative disease was 20% as opposed to 62% among patients without post-transplant lymphoproliferative disease (P<0.001). The study identifies patients at risk of post-transplant lymphoproliferative disease after transplantation in need of pre-emptive measures.