Patient cytomegalovirus seropositivity with or without reactivation is the most important prognostic factor for survival and treatment-related mortality in stem cell transplantation from unrelated donors using pretransplant in vivo T-cell depletion with anti-thymocyte globulin

Investigation of KIR/HLA relationship and other clinical variables after T-cell-replete haploidentical bone marrow transplantation in patients with acute myeloid leukemia (AML)

BACKGROUND

KIR/HLA mismatch in hematopoietic stem cell transplantation (HSCT), particularly in patients with acute myeloid leukemia (AML), was related to decreased recurrence rates, improved engraftment, and a reduction in graft-versus-host disease, according to recent research (GVHD). Uncertainty exists about the impact of KIR/HLA mismatch on haploidentical-HSCTs treated with post-transplant cyclophosphamide (PTCy). We attempted to analyze the effects of KIR/HLA mismatch on clinical outcomes on transplant outcomes using the cohort of 54 AML patients who received a haplo-HSCT with PTCy.

RESULTS

In contrast to KIR/HLA match, our findings showed that donor KIR/HLA mismatch was substantially associated with superior OS (HR, 2.92; (P = 0.04)). Moreover, donor KIR/HLA mismatch (KIR2DS1_D/C2⁺ _R and KIR2DS2_D/C1⁺ _R mismatch versus KIR2DL1_D/C2^- _R mm, KIR2DL2/3_D/C1^- _R mm and KIR3DL1_D/Bw4^- mm) was correlated with the improvements in OS (HR, 0.74; P = 0.085) and activating. KIR/HLA mismatch versus KIR/HLA match was significantly correlated with improvements in OS (HR, .46; P = 0.03) and inhibitory. KIR/HLA mismatch versus KIR/HLA match was enhancement in the OS (HR, .93; P = 0.06). Despite a higher rate of aGvHD (grade I-IV) in the patients with KIR/HLA mismatch compared to KIR/HLA matched (57% vs. 33% (p = 0.04). However, the KIR/HLA mismatch group saw a decreased relapse rate (3.2% vs. 23%, p = 0.04).

CONCLUSION

This analysis shows the significance of KIR/HLA Incompatibility, other clinical variables like CMV, the relationship between donor/recipient and donor age, and the relationship between donor/recipient and donor age in the haplo-donor selection process. It also suggests that KIR and HLA mismatching between donor and recipient could be routinely performed for haplo-donor selection and may improve clinical outcomes after haplo-HSCTs with PTCy.

Cytomegalovirus infection may be oncoprotective against neoplasms of B-lymphocyte lineage: single-institution experience and survey of global evidence

Background

Although cytomegalovirus (CMV) is not considered tumorigenic, there is evidence for its oncomodulatory effects and association with hematological neoplasms. Conversely, a number of experimental and clinical studies suggest its putative anti-tumour effect. We investigated the potential connection between chronic CMV infection in patients with B-lymphocyte (B-cell) malignancies in a retrospective single-center study and extracted relevant data on CMV prevalences and the incidences of B-cell cancers the world over.

Methods

In the clinical single-center study, prevalence of chronic CMV infection was compared between patients with B-cell leukemia/lymphoma and the healthy controls. Also, global data on CMV seroprevalences and the corresponding country-specific incidences of B- lineage neoplasms worldwide were investigated for potential correlations.

Results

Significantly higher CMV seropositivity was observed in control subjects than in patients with B-cell malignancies (p = 0.035). Moreover, an unexpected seroepidemiological evidence of highly significant inverse relationship between country-specific CMV prevalence and the annual incidence of B-cell neoplasms was noted across the populations worldwide (ρ = −0.625, p < 0.001).

Conclusions

We try to draw attention to an unreported interplay between CMV infection and B-cell lymphomagenesis in adults. A large-scale survey across > 70 countries disclosed a link between CMV and B-cell neoplasms. Our evidence hints at an antagonistic effect of chronic CMV infection against B-lymphoproliferation.

Relationship between certain HLA alleles and the risk of cytomegalovirus reactivation following allogeneic hematopoietic stem cell transplantation

INTRODUCTION

Evidence is emerging to support an association between certain HLA alleles and the risk of cytomegalovirus (CMV) reactivation following allogeneic HSCT (allo-HSCT). The primary aim of this study was to identify HLA alleles associated with resistance or susceptibility to CMV reactivation.

METHODS

We studied 586 adults who underwent allo-HSCT for high-risk hematological malignancies. High resolution HLA typing data was available for recipient and donor. HLA Class I and II alleles observed at a frequency of > 5% in our population, were included in the analysis. A CMV viremia level of more than 200 IU/ml on weekly monitoring was considered to be indicative of CMV reactivation.

RESULTS

The median follow-up time in surviving patients was 21 months (range 4-74 months). The cumulative incidence of CMV reactivation at 6 months in the entire cohort was 55% (95% CI 50.8%-59.2%). Mismatched donor, increasing recipient age, occurrence of AGVHD and recipient CMV seropositivity were associated with increased risk of CMV reactivation. HLA B*07:02 (HR 0.59, 95% CI 0.40-0.83) was associated with decreased risk of CMV reactivation. Patients who developed CMV reactivation had a lower incidence of relapse, higher transplant related mortality (TRM) and lower overall survival (OS) compared to those without CMV reactivation. There was an adverse correlation of OS and TRM with increasing numbers of CMV reactivations.

CONCLUSION

We observed that HLA B*07:02 was associated with decreased risk of CMV reactivation. CMV reactivation was associated with lower relapse post-transplant, but this did not translate into a survival benefit due to higher transplant related mortality. This article is protected by copyright. All rights reserved.

The changing impact of cytomegalovirus among hematopoietic cell transplant recipients during the past decade: A single institutional cohort study

BACKGROUND

With advancements in allogeneic hematopoietic cell transplantation (alloHCT), the need for cytomegalovirus (CMV) surveillance persists.

METHODS

We present a retrospective analysis on the impact of CMV with preemptive therapy in 1,065 alloHCT patients with donor and/or recipient CMV seropositivity from 2009-2019.

RESULTS

51% developed clinically significant CMV infection (CMV-CSI); 6.5% had CMV disease. In multivariate analysis stratified by serostatus and preparative regimen the use of ATG (HR 2.97, 95% CI 2.00 to 4.42, P < 0.001) was associated with development of CMV-CSI. Median length of stay for index hospitalization was longer in patients with CMV-CSI (27 d vs 25 d, respectively; P = .002), as were rates (32.9% vs 17.7%; P < .001) and duration (9 d vs 6 d; P < .001) of rehospitalization, and median total inpatient days (28 d vs 26 d; P < .001). Patients with CMV-CSI had higher rates of neutropenia (47% vs 20%; P < .001) and transfusion support (PRBC, median 5 vs 3; P < .001; platelets, median 3 vs 3; P < .001).

CONCLUSION

Preemptive therapy does not negate the impact of CMV-CSI on peri-engraftment toxicity and healthcare utilization. This cohort represents a large single center study on the impact of CMV in the pre-letermovir era and serves as a real-world comparator for assessing the impact of future prophylaxis. This article is protected by copyright. All rights reserved.

Presence of Parvovirus B19 but Not Herpesvirus Genome in Acute Skin Rash after Allogeneic Stem Cell Transplantation Correlates with Outcome

INTRODUCTION

Skin rash is a first symptom of acute graft-versus-host disease (GvHD) after allogeneic stem cell transplantation (ASCT) but can also be caused by viruses. The relevance of virus DNA analyses in skin rash for diagnosis and clinical outcome is unknown.

OBJECTIVES

To record the frequencies of detection of herpes and parvovirus B19 (ParvoB19) DNA in skin rash within 100 days after ASCT and to analyze their relevance for diagnosis, clinical course, and non-relapse mortality (NRM).

METHODS

We retrospectively identified 55 patients with virus DNA analysis for CMV, EBV, HHV6, HHV8, HSV, VZV, or ParvoB19. We assessed the rate of virus DNA detection and studied associations with histological diagnosis, virus DNA from concomitantly analyzed blood, clinical presentation, exanthema treatment, and NRM.

RESULTS

CMV, EBV, HHV6, HHV8, HSV, VZV and ParvoB19 DNA were detected in 12.5, 11.8, 10, 0, 0, 2.9, and 26.7% of exanthemas. Histopathological diagnosis was not associated with virus polymerase chain reaction (PCR) results. Detection of CMV, EBV, or HHV6 DNA but not ParvoB19 in skin and blood was associated with PCR results (p = 0.016; p < 0.001; p = 0.067; p = n.a.). Detection of CMV, EBV, HHV6, or ParvoB19 DNA in the skin was not significantly associated with patient, ASCT, or GvHD characteristics. Detection of ParvoB19 but not herpes virus DNA was associated with less immunosuppressive treatment (p = 0.015) and lower NRM (p = 0.041). In multivariate analyses, detection of ParvoB19 was associated with a lower NRM.

CONCLUSIONS

Detection of ParvoB19 DNA in exanthema after ASCT might be associated with lower NRM.

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

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

Monocenter study on epidemiology, outcomes, and risk factors of infections in recipients of 166 allogeneic stem cell transplantations during 1 year

OBJECTIVES

During allogeneic hematopoietic stem cell transplantation (allo-SCT), infections significantly contribute to morbidity and mortality. A monocentric prospective analysis was performed to assess epidemiology, risk factors, and outcomes of infections during the peri-transplant period.

METHODS

Data were recorded prospectively using a predefined questionnaire.

RESULTS

In 2015, 163 consecutive patients, 37.4% female, median age 59 (range 18-79) years received 166 allo-SCT. Median duration of leukopenia <10⁹ /L was 14.5 days (range 4-43 days). Fever of unknown origin (FUO) occurred in 118/166 patients (71.1%). Severe sepsis developed in 95, and septic shock developed in 26 patients. Intensive diagnostic workup helped to identify causative microorganisms only in a small number of infectious courses. All but 13 patients needed antibiotic therapy, each according to the standard operating procedures of the department. Cumulative incidence of death by infection after 1 year was 16.6% (95% CI: 11.3-22.7). The only risk factor for FUO in neutropenia was duration of neutropenia </≥14 days (55.4% vs 85.5%, P < .001).

CONCLUSION

Results of an elaborate diagnostic workup of infections in the peri-transplant period are scarce. Attention to risk factors might help to identify patients at risk for severe infections.

Cytomegalovirus (CMV) infection and risk of mortality in allogeneic hematopoietic stem cell transplantation (Allo-HSCT): A systematic review, meta-analysis, and meta-regression analysis

Controversy surrounds the potential association between cytomegalovirus (CMV) infection and increased risk of mortality after allogeneic hematopoietic stem cell transplantation (Allo-HSCT). A systematic literature search was conducted using the PubMed, EMBASE, and Web of Science databases, assessing the association between CMV infection, as documented by the pp65 antigenemia assay or by polymerase chain reaction (PCR) using blood specimens, and overall mortality (OM) and nonrelapse mortality (NRM) in the allo-HSCT setting. Pooled effects were estimated using the generic inverse variance random effects model. Heterogeneity was evaluated by Cochrane's Q test and I² statistics. The source of heterogeneity was investigated by meta-regression and subgroup analyses. Twenty-six of 1367 studies fulfilled eligibility criteria. CMV infection identified by PCR monitoring was significantly associated with an increased risk of OM and NRM (hazard ratio 1.47, 95% confidence interval [1.20-1.81], P ≤ .001; hazard ratio 1.68, 95% confidence interval [1.14-2.49], P = .05, respectively). In this setting, the use of preemptive antiviral therapy (PET) resulted in a twofold increased risk of OM and NRM. The estimated effect sizes were associated with allo-HSCT modalities. Although our analyses point to an association between CMV infection and an increased risk of OM and NRM in allo-HSCT recipients, the high heterogeneity across studies prevented drawing of robust conclusions on this matter.

The prognostic impact of the cytomegalovirus serostatus in patients with chronic hematological malignancies after allogeneic hematopoietic stem cell transplantation: a report from the Infectious Diseases Working Party of EBMT

It has been shown recently that donor and/or recipient cytomegalovirus (CMV) seropositivity is associated with a significant overall survival (OS) decline in acute leukemia patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT). We now analyzed the prognostic impact of the donor/recipient CMV serostatus in 6968 patients with chronic hematological malignancies who underwent allo-HSCT. Donor and/or recipient CMV seropositivity was associated with a significantly reduced 2-year progression-free survival (PFS, 50% vs. 52%, p = 0.03) and OS (62% vs. 65%, p = 0.01). Multivariate Cox regression analyses showed an independent negative prognostic impact of donor and/or recipient CMV seropositivity on PFS (HR, 1.1; 95% CI, 1.0-1.2; p = 0.03), OS (HR, 1.1; 95% CI, 1.0-1.2; p = 0.003), and non-relapse mortality (HR, 1.2; 95% CI, 1.0-1.3; p = 0.02). OS decline was strongest for CMV-seropositive recipients with a CMV-seronegative donor (HR, 1.2; 95% CI, 1.1-1.3), followed by CMV-seropositive patients with a CMV-seropositive donor (HR, 1.1; 95% CI, 1.0-1.2). Conversely, OS did not differ significantly between CMV-seronegative recipients allografted from a CMV-seropositive donor (HR, 1.0; 95% CI, 0.9-1.2) and patients with donor/recipient CMV seronegativity (p = 0.001 for the four groups together). Non-relapse mortality was also significantly (p = 0.01) higher for CMV-seropositive patients with a CMV-seronegative graft (HR, 1.2; 95% CI, 1.1-1.4) than for CMV-seropositive patients with a CMV-seropositive graft (HR, 1.1; 95% CI, 0.9-1.2) or CMV-seronegative recipients with a CMV-seropositive graft (HR, 1.0; 95% CI, 0.8-1.2). Donor and/or recipient CMV seropositivity still results in an OS decline in patients with chronic hematological malignancies who have undergone allo-HSCT. However, this OS decline seems to be lower than that described for acute leukemia patients previously.

Selecting the Best Donor for Haploidentical Transplant: Impact of HLA, Killer Cell Immunoglobulin-Like Receptor Genotyping, and Other Clinical Variables

The use of post-transplant cyclophosphamide (PTCy)-based haploidentical (haplo) transplant is increasing worldwide. However, because multiple potential haplo donors are usually available, data-driven guidance is clearly needed to help transplant centers prioritize donors. To that end, we retrospectively analyzed 208 consecutive donor-recipient pairs receiving PTCy-based haplo transplant at a single institution. Median recipient and donor age were 52 years (range, 19 to 75) and 38 years (range, 15 to 73), peripheral blood stem cell was the stem cell source in 66%, and myeloablative conditioning was used in 41%. Median follow-up for surviving patients was 33 months (range, 7 to 130). Donor variables analyzed included age, sex, relationship, cytomegalovirus (CMV) status, ABO compatibility, HLA disparity, and several natural killer (NK) alloreactivity models. Multivariate Cox analysis was used to adjust for known patient, disease, and transplant covariates. Donor characteristics independently associated with improved survival included presence of HLA-DR mismatch, HLA-DP nonpermissive mismatch, killer cell immunoglobulin-like receptor (KIR) receptor-ligand mismatch, and KIR B/x haplotype with KIR2DS2. Donor characteristics associated with inferior survival included parental donor relationship and the use of a CMV-seronegative donor for a CMV-seropositive patient. Increased HLA disparity (≥4/10 HLA allelic mismatches [graft-versus-host direction]) resulted in relapse protection at the expense of increased nonrelapse mortality with no associated survival effect. We further propose a donor risk factor scoring system to permit a more evidence-based selection algorithm for potential haplo donors. This large, single-institution analysis demonstrates the importance of HLA-DR/HLA-DP disparity, NK alloreactivity, and other clinical variables in the haplo donor selection process and suggests that KIR and HLA-DP genotyping should be performed routinely for haplo donor selection.

Comparable survival using a CMV-matched or a mismatched donor for CMV+ patients undergoing T-replete haplo-HSCT with PT-Cy for acute leukemia: a study of behalf of the infectious diseases and acute leukemia working parties of the EBMT

The role of donor CMV serostatus in the setting of non T-cell depleted haplo-HSCT with post-transplant cyclophosphamide (PT-Cy) has not been specifically addressed so far. Here we analyzed the impact of the donor CMV serological status on the outcome of 983 CMV seropositive (CMV+), acute leukemia patients receiving a first, non T-cell depleted haplo-HSCT registered in the EBMT database. The 1-year NRM was 21.3% (95% CI: 18.4-24.8) and 18.8% (95% CI: 13.8-25.5) in the CMV D+/R+ and D-/R+ pairs, respectively (p = 0.40). Similarly, 1-year OS was 55.1% (95% CI: 50.1-58.0) and 55.7% (95% CI: 48.0-62.8) in the same groups (p = 0.50). The other main outcomes were comparable. No difference in NRM nor OS was observed after stratification for the intensity of conditioning and multivariate anaysis confirmed the lack of significant association with NRM or OS. In conclusion, the choice of a CMV-seronegative donor did not impair early survival of CMV-seropositive patients with acute leukemia after a first, non T-cell depleted haploidentical HSCT and PT-Cy among this series of 983 consecutive patients. Future research may focus on the assessment of the hierarchy of all the donor variables.

Infectious diseases in allogeneic haematopoietic stem cell transplantation: prevention and prophylaxis strategy guidelines 2016

Infectious complications after allogeneic haematopoietic stem cell transplantation (allo-HCT) remain a clinical challenge. This is a guideline provided by the AGIHO (Infectious Diseases Working Group) of the DGHO (German Society for Hematology and Medical Oncology). A core group of experts prepared a preliminary guideline, which was discussed, reviewed, and approved by the entire working group. The guideline provides clinical recommendations for the preventive management including prophylactic treatment of viral, bacterial, parasitic, and fungal diseases. The guideline focuses on antimicrobial agents but includes recommendations on the use of vaccinations. This is the updated version of the AGHIO guideline in the field of allogeneic haematopoietic stem cell transplantation utilizing methods according to evidence-based medicine criteria.

Progress in Treatment of Viral Infections in Children with Acute Lymphoblastic Leukemia

In children, the most commonly encountered type of leukemia is acute lymphoblastic leukemia (ALL). An important source of morbidity and mortality in ALL are viral infections. Even though allogeneic transplantations, which are often applied also in ALL, carry a recognized risk for viral infections, there are multiple factors that make ALL patients susceptible to viral infections. The presence of those factors has an influence in the type and severity of infections. Currently available treatment options do not guarantee a positive outcome for every case of viral infection in ALL, without significant side effects. Side effects can have very serious consequences for the ALL patients, which include nephrotoxicity. For this reason a number of strategies for personalized intervention have been already clinically tested, and experimental approaches are being developed. Adoptive immunotherapy, which entails administration of ex vivo grown immune cells to a patient, is a promising approach in general, and for transplant recipients in particular. The ex vivo grown cells are aimed to strengthen the immune response to the virus that has been identified in the patients' blood and tissue samples. Even though many patients with weakened immune system can benefit from progress in novel approaches, a viral infection still poses a very significant risk for many patients. Therefore, preventive measures and supportive care are very important for ALL patients.

Impact of Donor and Recipient Cytomegalovirus Serostatus on Outcomes of Antithymocyte Globulin-Conditioned Hematopoietic Cell Transplantation

Although previous studies involving allogeneic hematopoietic cell transplantation (HCT) without in vivo T cell depletion by rabbit antithymocyte globulin (ATG) have reported a substantial survival difference between D-R- and D+R- patients, but little to no survival difference between D-R+ and D+R+ patients (D, donor; R, recipient; +, cytomegalovirus [CMV] seropositive; -, CMV seronegative), whether this applies to HCT using ATG is unknown. We studied 928 patients who underwent myeloablative HCT for hematologic malignancies in Alberta between 1999 and 2014 who received graft-versus-host disease (GVHD) prophylaxis using ATG (Thymoglobulin, 4.5 mg/kg) in addition to methotrexate and cyclosporine. D-R- and D+R- patients had similar survival (no significant difference). D-R+ patients had a substantially lower survival than D+R+ patients (41% versus 59% at 5 years; P = .001). This difference was attributed to higher nonrelapse mortality, apparently due to higher GVHD-associated mortality. Survival rates were also lower for D-R+ HLA-matched sibling transplant recipients compared with D+R+ HLA-matched unrelated donor transplant recipients (44% versus 66% at 5 years; P = .009). In conclusion, when using ATG, choosing a seronegative donor for a seronegative patient is relatively unimportant, whereas choosing a seropositive donor for a seropositive patient is important, even if this requires the use of a seropositive matched unrelated donor graft.

Cytomegalovirus Infection after CD34(+)-Selected Hematopoietic Cell Transplantation

The effectiveness of preemptive treatment (PET) for cytomegalovirus (CMV) in recipients of ex vivo T cell-depleted (TCD) hematopoietic cell transplantation (HCT) by CD34(+) selection is not well defined. We analyzed 213 adults who received TCD-HCT at our institution from June 2010 through May 2014. Patients were monitored by a CMV quantitative PCR assay if recipient (R) or donor (D) were CMV seropositive. CMV viremia occurred early (median, 27 days after HCT) in 91 of 213 (42.7%) patients for a 180-day cumulative incidence of 84.5%, 61.8%, and 0 for R+/D+, R+/D-, and R-/D+ patients, respectively. CMV disease occurred in 5% of patients. In Cox regression analysis, R+/D+ status was associated with increased risk for CMV viremia compared with R+/D- (hazard ratio [HR], 1.79, 95% confidence interval [CI], 1.16 to 2.76, P = .01), whereas matched unrelated donor allograft was associated with decreased risk (HR, .62; 95% CI, .39 to .97, P = .04). Of 91 patients with CMV viremia, 52 (57%) had persistent viremia (>28 days duration). Time lag from detection of CMV viremia to PET was associated with incremental risk for persistent viremia (HR, 1.09; 95% CI, 1.01 to 1.18; P = .03). Overall, 166 of 213 (77.9%) patients were alive 1 year after HCT, with no difference between patients with and without CMV viremia or among the different CMV serostatus pairs (P = not significant). CMV viremia occurred in 70% of R + TCD-HCT. Delay in PET initiation was associated with persistent viremia. With PET, CMV R/D serostatus did not adversely impact survival in TCD-HCT on 1-year survival in the present cohort.

Impact of Donor Epstein-Barr Virus Serostatus on the Incidence of Graft-Versus-Host Disease in Patients With Acute Leukemia After Hematopoietic Stem-Cell Transplantation: A Study From the Acute Leukemia and Infectious Diseases Working Parties of the European Society for Blood and Marrow Transplantation

PURPOSE

We investigated the effect of Epstein-Barr virus (EBV) serostatus on the overall outcome of allogeneic hematopoietic stem-cell transplantation (allo-HSCT).

PATIENTS AND METHODS

The study included 11,364 patients who underwent allogeneic peripheral-blood or bone marrow transplantation for acute leukemia between 1997 and 2012. We analyzed the impact of donor and recipient EBV serologic status on overall survival, relapse-free survival, relapse incidence, nonrelapse mortality, and incidence of graft-versus-host disease (GVHD) after allo-HSCT.

RESULTS

Patients receiving grafts from EBV-seropositive donors had the same overall survival as patients who received grafts from EBV-seronegative donors (hazard ratio [HR], 1.05; 95% CI, 0.97 to 1.12; P = .23). Seropositive donors also had no influence on relapse-free survival (HR, 1.04; 95% CI, 0.97 to 1.11; P = 0.31), relapse incidence (HR, 1.03; 95% CI, 0.94 to 1.12; P = .58), and nonrelapse mortality (HR, 1.05; 95% CI, 0.94 to 1.17; P = .37). However, in univariate analysis, recipients receiving grafts from seropositive donors had a higher risk of chronic GVHD than those with seronegative donors (40.8% v 31.0%, respectively; P < .001; HR, 1.42; 95% CI, 1.30 to 1.56). When adjusting for confounders, higher risk was identified for both acute and chronic GVHD. In seronegative patients with seropositive donors, the HR for chronic GVHD was 1.30 (95% CI, 1.06 to 1.59; P = .039). In seropositive patients with seropositive donors, the HR was 1.24 (95% CI, 1.07 to 1.45; P = .016) for acute GVHD and 1.43 (95% CI, 1.23 to 1.67; P < .001) for chronic GVHD. Seropositive patients with seronegative donors did not have an increased risk of GVHD.

CONCLUSION

Our data suggest that donor EBV status significantly influences development of acute and chronic GVHD after allo-HSCT.

Controlling cytomegalovirus: helping the immune system take the lead

Cytomegalovirus, of the Herpesviridae family, has evolved alongside humans for thousands of years with an intricate balance of latency, immune evasion, and transmission. While upwards of 70% of humans have evidence of CMV infection, the majority of healthy people show little to no clinical symptoms of primary infection and CMV disease is rarely observed during persistent infection in immunocompetent hosts. Despite the fact that the majority of infected individuals are asymptomatic, immunologically, CMV hijacks the immune system by infecting and remaining latent in antigen-presenting cells that occasionally reactivate subclinically and present antigen to T cells, eventually causing the inflation of CMV-specific T cells until they can compromise up to 10% of the entire T cell repertoire. Because of this impact on the immune system, as well as its importance in fields such as stem cell and organ transplant, the relationship between CMV and the immune response has been studied in depth. Here we provide a review of many of these studies and insights into how CMV-specific T cells are currently being used therapeutically.

CMV serostatus still has an important prognostic impact in de novo acute leukemia patients after allogeneic stem cell transplantation: a report from the Acute Leukemia Working Party of EBMT

We analyzed the prognostic impact of donor and recipient cytomegalovirus (CMV) serostatus in 16,628 de novo acute leukemia patients after allogeneic stem cell transplantation (allo-SCT). Compared with CMV-seronegative recipients who underwent allograft from a CMV-seronegative donor, cases of CMV seropositivity of the donor and/or the recipient showed a significantly decreased 2-year leukemia-free survival (44% vs 49%, P < .001) and overall survival (50% vs 56%, P < .001), and increased nonrelapse mortality (23% vs 20%, P < .001). Both groups showed a comparable relapse incidence and 2-year probability of graft-versus-host disease. The negative prognostic effects of CMV seropositivity of the donor and/or the recipient (vs CMV seronegativity of both) were significantly stronger for acute lymphoblastic leukemia (ALL) than for acute myeloid leukemia (AML), resulting in a markedly reduced 2-year overall survival (46% vs 55% for ALL compared with 52% vs 56% for AML). The important prognostic impact of donor/recipient CMV serostatus remained in a multivariate Cox regression analysis including the other prognostic variables. We conclude that donor and/or recipient CMV seropositivity is still associated with an adverse prognosis in de novo acute leukemia patients after allo-SCT despite the implementation of sophisticated strategies for prophylaxis, monitoring, and (preemptive) treatment of CMV.

Cytomegalovirus infection and disease after allogeneic hematopoietic stem cell transplantation: experience in a center with a high seroprevalence of both CMV and hepatitis B virus

Cytomegalovirus (CMV) infection and disease are important concerns after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The similarity of hepatitis B virus (HBV) and CMV with regards to their chronic viral persistence and potential reactivation at the time of impaired cellular immunity has raised clinicians' interest in the occurrence and association between them among patients receiving allo-HSCT; however, only limited data have been obtained from a high seroprevalence region of both CMV and HBV. We monitored 117 adult allo-HSCT patients with both CMV polymerase chain reaction and pp65 antigenemia assay weekly until day 100. In 91.8% of our cases, donors and recipients were both CMV seropositive, and 13.7% of the patients were positive for HBV surface antigen. The incidences of CMV infection and disease were 45.3% and 6.8%, respectively. Grade II-IV acute graft-versus-host disease and anti-thymocyte globulin-containing conditioning regimen were associated with an increased risk of CMV infection in a multivariate analysis (hazard ratio 3.02, 95% CI 1.68-5.42, p < 0.001 and hazard ratio 5.29, 95% CI 2.57-10.8, p < 0.001). No survival disadvantage was found in patients who developed CMV infection (p = 0.699) and CMV disease (p = 0.093). No clinically significant HBV reactivation was found, and the underlying HBV infection in donors or recipients before allo-HSCT did not increase the risk of CMV infection and CMV disease and did not influence survival after allo-HSCT.

Improving clinical outcomes using adoptively transferred immune cells from umbilical cord blood

Because of the necessary immunodepletion prior to cord blood transplantation as well as the immaturity of cord blood immune cells, recipients experience a high incidence of viral infection in addition to complications observed after hematopoietic stem cell transplantation, such as relapse and graft-versus-host disease. We describe current immunotherapeutic approaches to treating these complications, including the generation of antigen-specific T cells from cord blood, redirecting cord blood T cells using chimeric antigen receptors, and generating cord blood-derived natural killer cells and regulatory T cells.

Prospective, comprehensive, and effective viral monitoring in children undergoing allogeneic hematopoietic stem cell transplantation

Major advances in the monitoring and treatment of viral infections after hematopoietic stem cell transplantation (HSCT) have been achieved over the last decade. The appropriate extent of viral monitoring and antiviral therapy remains controversial, and reports in pediatric patients receiving allogeneic unmanipulated hematopoietic stem cells (HSCs) are sparse. A total of 40 pediatric patients who underwent HSCT with either peripheral blood stem cells (PBSCs, n = 30) or bone marrow (BM; n = 10) were prospectively monitored every week for viral DNAemia (VDNA) by simultaneous detection of cytomegalovirus (CMV), Epstein-Barr virus (EBV), human herpesvirus 6 (HHV6), human adenovirus (ADV), and polyoma BK virus (BKV) using real-time TaqMan polymerase chain reaction (PCR). All patients received prophylactic acyclovir and preemptive ganciclovir (GCV) when 500 copies/microg DNA (EBV/HHV6) or >1 copy/microg DNA (CMV) were detected on 2 consecutive measurements. VDNA occurred in 25 of 40 recipients (CMV, 11/40 patients [28%]; EBV, 19/40 [48%]; HHV6, 2/40 [5%]; ADV/BKV, 1/40) and was found exclusively after neutrophil engraftment and in most cases up to day +100. Recurrent VDNA (P = .028) and (readily treatable) viral disease (P = .003) were observed predominantly in patients suffering from nonmalignant diseases, a cohort characterized by delayed lymphocyte engraftment. VDNA occurred more frequently in HLA-mismatched HSCT and in the 24 of 40 patients receiving antithymocyte globulin (ATG). The incidence of EBV, but not that of CMV, was increased in the ATG group. Yet, in these patients, viral loads of both EBV and CMV were higher, but with prompt initiation of preemptive GCV, no posttransplantation lymphoproliferative disorder or other life-threatening morbidities occurred. HHV6 was typically detected at low viral loads (<10(2) copies/microg DNA), with only 5% of HSC recipients fulfilling our HHV6 criteria for triggering GCV treatment. In multivariate analysis, ATG treatment, HLA mismatch, recipient CMV seropositivity, and stem cell source, but not severe acute graft-versus-host disease were identified as independent risk factors for VDNA. This comprehensive viral monitoring program with defined thresholds for initiation of preemptive GCV effectively prevents the development of critical viral disease, even in high-risk patients receiving ATG.

Fludarabine-based reduced intensity conditioning transplants have a higher incidence of cytomegalovirus reactivation compared with myeloablative transplants

Two hundred and ten adult CMV seropositive patients undergoing myeloablative conditioning (MAC) [n=127] or reduced intensity conditioning (RIC) [n=83] transplants (HCT) were serially monitored for CMV reactivation and disease, using a qualitative polymerase chain reaction (PCR) followed by quantitation with pp65 antigen or quantitative PCR. CMV reactivation occurred in 53 RIC (63.9%) and 61 MAC (48%; P=0.03) transplants at a median of 47 days (range: 24-1977). Risk factors identified included acute GVHD (P=0.001), RIC regimen (P=0.03), unrelated donor (P=0.02), use of anti-thymocyte globulin/alemtuzumb (P=0.02) and use of bone marrow in MAC transplants (P=0.011). On multivariate analysis, RIC transplants and acute GVHD remained independent predictors. Treatment with antiviral drugs resulted in CMV negativity rates of 86.8% in MAC and 88.6% in RIC transplants. CMV disease occurred in 10.8% of RIC and 4.7% of MAC transplants (P=0.15). At a median follow-up of 26 months (range: 3-88), 48.1% of RIC and 50.3% of MAC transplants are alive. The higher incidence of CMV reactivation among RIC transplants suggests the need for novel prophylactic or pre-emptive strategies in this high-risk group of patients.

Impact of donor CMV status on viral infection and reconstitution of multifunction CMV-specific T cells in CMV-positive transplant recipients

Reconstitution of cytomegalovirus (CMV)-specific CD8(+) T cells is essential to the control of CMV infection in CMV-positive recipients (R(+)) after allogeneic hematopoietic stem cell transplantation (HCT). Six-color flow cytometry was used to assess the functional profile of CMV-specific CD8(+) T cells in 62 of 178 R(+) HCT recipients followed virologically for CMV reactivation. R(+) recipients receiving grafts from CMV-negative donors (D(-); D(-)/R(+)) reconstituted fewer multifunctional CD8(+) T cells expressing tumor necrosis factor-alpha (TNF-alpha), macrophage inflammatory protein-1beta (MIP-1beta), and CD107 in addition to interferon-gamma (IFN-gamma), compared with D(+)/R(+) recipients. Unlike monofunctional CD8(+) T cells secreting IFN-gamma, which were abundantly generated during CMV reactivation in D(-)/R(+) recipients, the relative lack of multifunctional CD8(+) T cells persisted until at least 1 year post-HCT. D(-)/R(+) recipients were more likely to require recurrent and prolonged use of antivirals. These findings were robust to statistical adjustment for pretransplant factors, as well as for posttransplant factors including graft-versus-host disease (GVHD) and its treatment by steroids. These analyses suggest that D(+)/R(+) transplants, on average, generate higher levels of multifunctional CMV-specific T cells and require less antiviral therapy compared with D(-)/R(+) HCT recipients. These results highlight the benefit of D(+) donors in improving outcomes of R(+) HCT recipients by reducing the duration and recurrent need of antiviral treatment, aided by increased levels of multifunctional CMV-specific T cells.

Early reconstitution of effector memory CD4+ CMV-specific T cells protects against CMV reactivation following allogeneic SCT

Reactivation of CMV is a common complication following allogeneic haematopoietic SCT and is associated with significant morbidity and mortality. The relative importance of the CD4+ and CD8+ components of the CMV-specific immune response in protection from reactivation is unclear. The CMV-specific CD4+ and CD8+ immune response was measured at serial time points in 32 patients following allogeneic HSCT. Intracellular cytokine staining following CMV lysate stimulation and HLA-peptide tetramers were used to determine CMV-specific CD4+ and CD8+ responses, respectively. A deficient CMV-specific CD4+ T-cell immune response within the first 30-50 days post transplant was associated with high risk of viral reactivation. Patients with combined impairment of the CD4+ and CD8+ immune response within the first 100 days were susceptible to late viral reactivation. The frequency of CMV-specific CD4+ T cells correlated with CMV-specific CD8+ T cells, comprising 10% of the whole T-cell repertoire. Early CMV-specific CD4+ T-cell reconstitution was dominated by effector memory cells with normal levels of IL-2 resuming 6 months following transplantation. In summary, both CD4 and CD8 CMV-specific immune reconstitution is required for protection from recurrent activation. Measurement of the magnitude of the CMV-specific CD4+ immune response is useful in managing viral reactivation following HSCT.

Patterns of cytomegalovirus reactivation are associated with distinct evolutive profiles of immune reconstitution after allogeneic hematopoietic stem cell transplantation

T cell-mediated immunity is essential for the control of cytomegalovirus (CMV) infections in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Our aims were to identify patterns of CMV-specific immune responses associated with multiple or prolonged reactivations. We analyzed findings in 116 recipients during the course of infection or reactivation and latency. CD8(+) T cell responses were determined weekly, using HLA class I tetramers together with extended phenotypic analyses. Our results confirmed that recipients of allo-HSCT from unrelated donors were more susceptible to multiple reactivations and that the donor's CMV serological status influenced the occurrence of prolonged reactivations. We found that a lack of CMV-specific T cells after the first episode of reactivation was associated with multiple subsequent reactivations. In patients with uncontrolled reactivations, CMV-specific T cells of the late differentiation phenotype CD45RA(+)CD27(-)CD28(-) did not develop. Longitudinal evaluation of CD27 and CD45RA expression within the tetramer-positive subset could help identify patients in whom a protective immune response is developing. Evaluation of CMV-specific immune responses during the first episode of reactivation, together with extended phenotypes, could thus improve immune monitoring, especially in recipients at risk of uncontrolled viral reactivation.

Impact of alemtuzumab as conditioning regimen component on transplantation outcomes in case of CMV-seropositive recipients and donors

We studied the incidence of cytomegalovirus (CMV) infection, clinical outcomes, and complications in 39 recipients of alemtuzumab-containing conditioning-stem cell transplantation, who were classified into two groups based on the median dose (35 mg) of alemtuzumab. All the recipients and donors were CMV-seropositive before transplantation. The median survival duration was 321 days (range, 46-1098 days) and the 2-year survival rate was 47.8%. The probability of nonrelapse mortality at 100 days and 2 years was 14.6% and 31.2%, respectively. The cumulative incidence of Grade II-IV acute graft-versus-host disease (GVHD) at Day 100 was 21.8%. The overall incidence of chronic GVHD (cGVHD) was 28.6%, including a 17.9% incidence of extensive cGVHD. The cumulative incidence of CMV antigenemia was 68.0%. There were no statistical differences in the engraftment, acute and cGVHD, relapse, CMV antigenemia, and overall survival (OS) between the two groups. Yet, the nonrelapse mortality (NRM) was significantly lower for the low-dose group (5.9% vs. 51.7%, P = 0.010). The present study showed that alemtuzumab was effective for GVHD prevention, yet caused a relatively high incidence of CMV antigenemia, regardless of the dose. Thus, a low dose of alemtuzumab (< or = 35 mg) would seem to be preferable in an allogeneic SCT setting when both the recipient and the donor are CMV seropositive.

Predictors for persistent cytomegalovirus reactivation after T-cell-depleted allogeneic hematopoietic stem cell transplantation

Cytomegalovirus (CMV) reactivation occurs in up to 60% of CMV-seropositive recipients after allogeneic hematopoietic stem cell transplantation (HSCT). The incidence of CMV disease among T-cell-depleted HSCT patients has been reported from 5-15%. The incidence of reactivation refractory to antivirals in this population is not well studied.

METHODS

In this retrospective study we characterized the outcome of CMV reactivation in a cohort of 255 adult and pediatric patients who underwent T-cell-depleted HSCT at Memorial Sloan-Kettering Cancer Center from September 1999 through August 2004. CMV infection was monitored by the pp65 antigenemia assay (CMV Ag). Persistent reactivation was defined as antigenemia positivity >21 days on antiviral therapy.

RESULTS

Of 118 CMV-seropositive recipients, 69 (58.4%) had reactivated CMV. Twenty of 69 (29%) developed persistent reactivation at first episode of reactivation, and 7 (10%) in subsequent episode. All patients with persistent reactivation received >/=2 antivirals and CMV hyperimmune globulin; 45% received combination antiviral therapy. The median duration of persistent reactivation was 98 days, range 31-256 days. In multivariate analysis, maximum CMV Ag >25 cells/slide was associated with persistent reactivation (odds ratio 16.2%, 95% confidence interval 4-64, P<0.0001). CMV disease occurred in 6/27 (22%) patients with persistent reactivation. Patients with persistent reactivation had lower CD4(+) and CD8(+) lymphocyte counts compared with those with non-persistent reactivation at day +90 post HSCT (P=0.01 and 0.02, respectively).

CONCLUSIONS

Persistent reactivation occurred in 39% of T-cell-depleted HSCT despite treatment with currently available antivirals. Maximum CMV Ag >25 cells/slide was associated with persistent CMV reactivation. More effective treatment modalities are needed for this high-risk population to reduce CMV-associated morbidity and mortality.

Patients at high risk for CMV infection and disease show delayed CD8+ T-cell immune recovery after allogeneic stem cell transplantation

Human cytomegalovirus (CMV) is a major cause of death after transplantation. The frequency of pp65-specific T cells was examined in 38 HLA-A2+ stem cell recipients during the first year after transplantation. Patients were divided into four groups based on donor/recipient serostatus: d+/r+ (n=17), d+/r- (n=7), d-/r+ (n=9) and d-/r- (n=5). Peripheral blood mononuclear cells were stimulated with the CMVpp65 peptide NLVPMVATV, and the specific T-cell frequency was assessed by interferon gamma (IFN-gamma) ELISPOT assay. Responding T cells were characterized by flow cytometry revealing a terminal differentiated effector phenotype. Surveillance of CMV infection was carried out by real-time polymerase chain reaction (n=26) or immunofluorescence (n=12). Infection was present in 7/9 d-/r+ high-risk patients, and CMV disease occurred exclusively in this group with delayed or absent virus-specific T-cell recovery. In contrast, 16/24 intermediate-risk patients showed CMV-specific T cells. Our data suggest that CMV infection and disease rates are elevated in high-risk patients with delayed CMV-specific T-cell immune reconstitution and lower in those with early recovery of T-cell immunity. We recommend preferring CMV seropositive donors for CMV seropositive recipients, as this should lead to durable CMV-specific T-cell responses soon after transplantation with consecutive protection from CMV disease.

Valganciclovir is safe and effective as pre-emptive therapy for CMV infection in allogeneic hematopoietic stem cell transplantation

Despite significant advances in prevention and therapy, cytomegalovirus (CMV) infection continues to be an important cause of morbidity and mortality in the hematopoietic stem cell transplant (HSCT) recipient. The standard drug for pre-emptive therapy is intravenous ganciclovir (GCV). Valganciclovir (VGC), the oral pro-drug of GCV, has excellent bioavailability and is ideal for oral therapy. Since March 2002, VGC was adopted in our center for outpatient pre-emptive therapy in all patients undergoing allogeneic HSCT. Fifty-two allogeneic HSCT recipients were followed weekly via Digene hybrid capture assay. Patients with a positive assay were treated with VGC 900 mg p.o. b.i.d. x 14 days followed by 900 mg p.o. QD until at least 7 days after a negative test. Eighteen patients (14 sib, four MUD) had 30 episodes of CMV DNA detection treated with oral VGC. Median duration of therapy was 21 days (range 10-21 days). The rate of response was 93% (28/30) as confirmed by a negative assay within 14 days. No significant toxicity was encountered. Two patients failed oral VGC. One case of CMV enteritis was diagnosed in a patient with acute GVHD. Pre-emptive therapy of CMV infection with oral VGC is safe and effective in allogeneic HSCT recipients.

Hemolytic uremic syndrome after bone marrow transplantation: clinical characteristics and outcome in children

Hemolytic uremic syndrome (HUS) is an uncommon but potentially life-threatening complication of hematopoietic stem cell transplantation. We retrospectively studied the medical records of 293 children who underwent allogeneic bone marrow transplantation at St. Jude Children's Research Hospital between 1992 and 1999 to describe the clinical course of and to identify risk factors for transplant-associated HUS. Conditioning regimens included cyclophosphamide, cytarabine, and total body irradiation for patients with hematologic malignancies (n = 244); patients with nonmalignant diseases (n = 49) received disease-specific regimens. Grafts from unrelated or mismatched related donors were depleted of T lymphocytes, whereas matched sibling grafts were unmanipulated. All patients received cyclosporine as prophylaxis for graft-versus-host disease. Recipients of grafts from matched siblings also received pentoxifylline or short-course methotrexate. HUS developed in 28 (9.6%) patients at a median of 171 days after transplantation. We identified older donor age (P = .029), use of antithymocyte globulin in the conditioning regimen (P = .008), and recipient CMV seronegativity (P = .011) as being associated with an increased risk of HUS. With a multiple regression analysis, the use of antithymocyte globulin (beta = .86; P = .04) and recipient cytomegalovirus seronegativity (beta = .93; P = .035) remained significant risk factors for the development of HUS.

Survival Benefit of Asymptomatic Cytomegalovirus Reactivation after HLA-Identical Allogeneic Peripheral Blood Stem Cell Transplantation

BACKGROUND

Cytomegalovirus (CMV) reactivation (CMV-R) is associated with increased morbidity after allogeneic stem cell transplantation (SCT). However, after the introduction of ganciclovir preemptive therapy, CMV-R can be successfully controlled if the recipient's immunity recovers. Although many investigations have already focused on CMV-R as a risk factor, data related to the impact of asymptomatic CMV-R on transplant outcomes is scarce. Accordingly, the present study analyzed the differences in the transplant outcomes the immune reconstitution according to the CMV-R after allogeneic PBSCT.

METHODS

A total of 76 patients undergoing allogeneic peripheral blood stem cell transplantation (PBSCT) were included in the current study. The transplant outcomes and immune reconstitution after 3, 6, and 12 months were analyzed according to the occurrence of CMV-R in 33 patients.

RESULTS

The analysis revealed a favorable prognosis for the group with CMV-R compared to those without CMV-R: P = 0.0037 for OS, P = 0.0204 for NRM, and P = 0.05 for the risk of relapse. CMV-R was also found to correlate to the lymphoid reconstitution (P = 0.024). In multivariate analyses, CMV-R was found to be a favorable prognostic factor in terms of OS (P = 0.010, hazard ratio [HR] 2.948) and NRM (P = 0.05, HR 2.665), along with a higher transplant CD34 cell dose (P = 0.003 for OS, P = 0.002 for NRM), standard risk (P = 0.023 for OS), and acute GVHD grades 0-2 (P = 0.007 for NRM).

CONCLUSION

In a PBSCT setting, CMV-R did not seem to be a poor prognostic factor in terms of OS and NRM, possibly due to the accelerated lymphoid immune reconstitution associated with CMV-R.

Comparable results in patients with acute lymphoblastic leukemia after related and unrelated stem cell transplantation

We report the results of 84 patients with ALL after related (n = 46) or unrelated (n = 38) allogeneic SCT. Mean recipient age was 23 years (range: 1-60) and median follow-up was 18 months (range: 1-133). Forty-three patients were transplanted in CR1; 25 in CR2 or CR3; four were primary refractory; four in PR; eight in relapse. The conditioning regimen consisted of TBI/VP16/CY (n = 76), TBI/VP16 (n = 2), TBI/CY (n = 2), Bu/VP16/CY (n = 4). The OS at 3 years was 45% (44% unrelated, 46% related). Univariate analysis showed a significantly better OS for patients <18 years (P=0.03), mismatched sex-combination (P = 0.03), both with a stronger effect on increasing OS after unrelated SCT. Factors decreasing TRM were patient age <18 years (P = 0.004), patient CMV-seronegativity (P = 0.014), female recipient (P = 0.04). There was no significant difference in TRM and the relapse rate was similar in both donor type groups. Multivariate analysis showed that factors for increased OS which remained significant were mismatched sex-combination (RR: 0.70,95% CI: 0.51-0.93, P = 0.015), patient age < 18 years (RR: 0.66, 95% CI: 0.47-0.93, P = 0.016). A decreased TRM was found for female patients (RR: 0.56, 95% CI: 0.33-0.98, P=0.042), negative CMV status of the patient (RR: 0.57, 95% CI: 0.36-0.90, P = 0.015). Unrelated stem cell transplantation for high-risk ALL patients with no HLA-compatible family donor is justifiable.

Pretransplantation CMV-specific T cells protect recipients of T-cell-depleted grafts against CMV-related complications

We have studied cytomegalovirus (CMV) immunity in 17 CMV-positive recipients of T-cell-depleted or T-cell-replete grafts. In recipients of T-cell-replete grafts, the patient's CMV-specific T-cell response was completely ablated. Because primary anti-CMV responses were rare during the first year, immunity depended essentially on the transfer of donor CMV-specific T cells and, therefore, on the CMV positivity of the donor. In the recipients of T-cell-depleted grafts, CMV-specific cytotoxic T cells were of recipient origin in 2 patients who underwent transplantation with CMV-negative donors and in 3 of 8 patients who underwent transplantation with CMV-positive donors, and they were of mixed or donor origin in the other 5 patients studied. Recipient CMV-specific T cells responded vigorously to antigen ex vivo and persisted for several years without replenishment by donor cells. Furthermore, they appeared to have a protective effect because CMV-related complications were absent in the patients with CMV-specific T cells of recipient origin. Clinical outcomes of a cohort of 91 patients corroborated the experimental results. Patients with recipient T cells in their blood were protected regardless of the donor immune status. Hence, when a T-cell depletion protocol is used that favors the survival of recipient T cells, the patient's pretransplantation CMV-specific immunity protects against posttransplantation CMV-related complications.

Heterogeneous Clearance of Antithymocyte Globulin after CD34+-Selected Allogeneic Hematopoietic Progenitor Cell Transplantation

Antithymocyte globulins (ATG) are purified, concentrated preparations of polyclonal immunoglobulin G from hyperimmune serum of horses or rabbits immunized with human thymus lymphocytes. Both the horse and the rabbit products induce immunosuppression as a result of lymphocyte depletion and immune modulation. The exact mechanism of action is unknown but may include T-cell clearance from the circulation and modulation of T-cell activation, homing, and cytotoxic activities. Both horse and rabbit ATG include multiple antibodies against T-cell surface antigens and have been used extensively in allogeneic hematopoietic progenitor cell transplantation (HPCT) for the treatment and prevention of graft-versus-host disease or graft rejection. To quantify the active ATG after HPCT, we developed a flow-based assay to measure residual ATG capable of binding to lymphocytes. In contrast to prior assays that measure total rabbit or horse immunoglobulin, this assay quantitates only the antibody capable of binding to lymphocytes, which presumably reflects the functionally active fraction of the xenoantiserum. Thirty patients with hematologic malignancies underwent T cell-depleted HPCT and had ATG levels assayed during the peritransplantation period. The time required for ATG levels to decay to background was quite variable (mean, 46 days; range, 14-91 days), although most patients demonstrated a rapid early clearance followed by a slower decline. The actual mean half-life was 6.8 days (range, 2.4-14.0 days). The persistence of ATG for months after administration has significant implications for the pace of immune reconstitution after transplantation and is a potentially confounding variable in any study that involves early administration of donor lymphocyte infusions or other cellular transfer. These findings indicate that ATG levels should be explicitly measured in studies that involve early donor lymphocyte administration so that proper conclusions regarding dose, safety, and efficacy can be reached.

Antimicrobial prophylaxis in allogeneic bone marrow transplantation. Guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Haematology and Oncology

Patients undergoing allogeneic stem cell transplantation are at high risk for infection with a variety of pathogens during different phases of the procedure. Bacteria and fungi predominate the first phase until engraftment. During the second phase, from engraftment to about day 100, major infectious problems are caused by fungi and cytomegalovirus. Both pathogens remain important under continued immunosuppression, however, in the late post-transplantation period infections with encapsulated bacteria may become a problem. In this review the Infectious Diseases Working Party of the DGHO gives recommendations for prophylaxis of infections under allogeneic stem cell transplantation with drugs and other measures. The aim of the group was to do this on an evidence-based-medicine rating, if possible.

Influence of cytomegalovirus (CMV) sero-positivity on CMV infection, lymphocyte recovery and non-CMV infections following T-cell-depleted allogeneic stem cell transplantation: a comparison between two T-cell depletion regimens

We compared the incidence and outcome of preemptively treated cytomegalovirus (CMV) infection, lymphocyte recovery and non-CMV infections between two different TCD modalities, one employing CD34+ selection and T-cell add-back (TCAB), preceded by Campath-1H in vivo (CD34+/TCAB group, n=29), and the other using grafts incubated with Campath-1H in vitro (Campath-1H in vitro group, n=32). The probabilities of CMV reactivation and recurrence were 67 and 83.6% in the CD34+/TCAB group and 42.9 and 20% in the Campath-1H group (P=0.07 and 0.02). Donor sero-positivity reduced CMV reactivation in the Campath-1H group, but not in the CD34+/TCAB group. The durations of positive PCR/antigenemia positivity and antiviral therapy were also significantly longer in the CD34+/TCAB group. However, only two patients developed CMV disease in each group. The mean absolute lymphocyte counts (x 10(9)/l) at 30 days (0.27 vs 0.4, P=0.03) and 100 days (0.77 vs 1.4, P=0.01) were significantly lower in the CD34+/TCAB group along with a higher incidence of non-CMV infections in CMV at-risk patients, but not in the CMV low-risk group. These findings suggest that the modality of TCD should be tailored according to the CMV risk status, and CMV sero-positive patients should receive a less extensively T-cell-depleted graft and a CMV sero-positive graft if possible.

Recent advances in the prevention of CMV infection and disease after hematopoietic stem cell transplantation

Cytomegalovirus (CMV) remains an important pathogen in hematopoietic stem cell transplant (HCT) recipients in the current era of antiviral prophylaxis and preemptive therapy, despite the almost complete elimination of CMV disease during the first 3 months after transplantation. Pretransplant CMV serostatus of the donor and/or recipient remains an important risk factor for poor post-transplant outcome, especially in highly immunodeficient patients (e.g. recipients of ex vivo or in vivo T-cell depletion). Prevention of late CMV disease continues to be a challenge in selected high-risk populations, and indirect immunomodulatory effects of CMV (e.g. invasive bacterial and fungal infections) appear to contribute to the poor outcome. The risk of developing antiviral resistance remains low in most patients; however, in a setting of intense immunosuppression (e.g. after transplantation from a haploidentical donor) the incidence may be as high as 8%. Transfusion-transmitted CMV infection can be reduced by the provision of seronegative or leukocyte-depleted blood products; however, a small risk of 1-2% of CMV disease remains. Surveillance and preemptive therapy is effective in preventing transfusion-related CMV disease. The development of new drugs and immunologic strategies (adoptive transfer of CMV-specific T-cells and donor/recipient vaccination strategies) are important goals for the elimination of the negative impact of CMV in the HCT setting.

Cytomegalovirus infection after bone marrow transplantation in children

Cytomegalovirus (CMV) is a well-known cause of disease occurring after bone marrow transplantation (BMT). The manifestations of CMV range from asymptomatic infection, defined as active CMV replication in the blood in the absence of clinical manifestations or organ failure abnormalities, to CMV disease, characterized by CMV infection with clinical symptoms or organ function abnormalities. Diagnostic procedures to assess the viral load have improved greatly with the increased use of antigenemia, CMV DNA, and immediate early-messenger RNA. Many conditions concur in determining the risk of developing CMV reactivation or disease after bone marrow transplant with serologic status of donor and recipient, type of bone marrow transplant, presence of graft-versus-host disease being the most studied. However, time and quality of immune reconstitution seems to be the pivotal factors. Pneumonia and gastrointestinal involvement are the most frequently documented clinical pictures with late-onset CMV reactivation or disease representing a new challenge. CMV prophylaxis or pre-emptive therapy adopted during the last few years in allogeneic BMT recipients has changed the natural history of the disease, reducing the risk of CMV disease, CMV-associated death, transplant-related mortality, and has prolonged the period at risk. Specific studies on children are lacking, however, the clinical pictures and features seems to be similar both in children and adults.