Monitoring and preemptive rituximab therapy for Epstein-Barr virus reactivation after antithymocyte globulin containing nonmyeloablative conditioning for umbilical cord blood transplantation

Effect of pre-emptive rituximab on EBV DNA levels and prevention of post-transplant lymphoproliferative disorder in pediatric kidney transplant recipients: A case series from the pediatric nephrology research consortium

BACKGROUND

There are scant data on the effect of rituximab on EBV DNA levels and prevention of post-transplant lymphoproliferative disorder (PTLD) in pediatric kidney transplant recipients with EBV DNAemia.

METHODS

Kidney transplant recipients with EBV DNAemia treated with rituximab to prevent PTLD between 7/1999 and 7/2019 at five pediatric centers were included. Those with confirmed PTLD at the onset of rituximab were excluded. Primary outcomes included percentage change in EBV DNAemia and occurrence of PTLD post rituximab.

RESULTS

Twenty-six pediatric kidney transplant recipients were included. Median age at transplant was 4 years (IQR 2.1-10.3). EBV DNA load monitoring by qPCR was performed at 1-3 month intervals. EBV DNAemia onset occurred at a median of 73 days post-transplant (IQR 52-307), followed by DNAemia peak at a median of 268 days (IQR 112-536). Rituximab was administered at a median of 9 days post peak (IQR 0-118). Rituximab regimens varied; median dose 375 mg/m2 (IQR 375-439) weekly for 1-4 doses per course. Following rituximab, EBV DNA load decreased to <10% of baseline at 120 days in 20/26 patients; however, only 30% achieved complete resolution at last follow-up (median 2094 days post-transplant [IQR 1538-3463]). Two (7%) developed PTLD at 915 and 1713 days post rituximab. All recipients had functioning grafts. One death occurred in a child with PTLD following remission due to unrelated reasons.

CONCLUSIONS

In the largest pediatric kidney transplant recipient case series with EBV DNAemia given rituximab to prevent PTLD, rituximab achieved a short-term reduction in DNA load; however, recurrent DNAemia is common.

Rituximab for posttransplant lymphoproliferative disorder - therapeutic, preemptive, or prophylactic?

To minimize mortality due to posttransplant lymphoproliferative disorder (PTLD), the following strategies have been used: (1) Therapy without EBV Monitoring, i.e., administration of rituximab after PTLD diagnosis, usually by biopsy, in the absence of routine Epstein-Barr virus (EBV) DNAemia monitoring, (2) Prompt Therapy, i.e., monitoring EBV DNAemia, searching for PTLD by imaging when the DNAemia has exceeded a pre-specified threshold, and administration of rituximab if the imaging is consistent with PTLD, (3) Preemptive Therapy, i.e., monitoring EBV DNAemia and administration of rituximab when the DNAemia has exceeded a pre-specified threshold, and (4) Prophylaxis, i.e., administration of rituximab to all transplant recipients. The superiority of one of these strategies over the other strategies has not been established. Here we review the pros and cons of each strategy. Preemptive therapy or prophylaxis may currently be preferred for patients who are at a high risk of dying due to PTLD. However, Therapy without EBV Monitoring may be used for both high- and low-risk patients in the future, if effective and relatively non-toxic therapies for rituximab-refractory PTLD (e.g., EBV-specific T cells) have become easily available.

Immune dysregulation as a leading principle for lymphoma development in diverse immunological backgrounds

Lymphoma is a heterogeneous group of malignancies arising from lymphocytes, which poses a significant challenge in terms of diagnosis and treatment due to its diverse subtypes and underlying mechanisms. This review aims to explore the shared and distinct features of various forms of lymphoma predisposing conditions, with a focus on genetic, immunological and molecular aspects. While diseases such as autoimmune disorders, inborn errors of immunity and iatrogenic immunodeficiencies are biologically and immunologically distinct, each of these diseases results in profound immune dysregulation and a predisposition to lymphoma development. Interestingly, the increased risk is often skewed towards a particular subtype of lymphoma. Patients with inborn errors of immunity in particular present with extreme forms of lymphoma predisposition, providing a unique opportunity to study the underlying mechanisms. External factors such as chronic infections and environmental exposures further modulate the risk of lymphoma development. Common features of conditions predisposing to lymphoma include: persistent inflammation, recurrent DNA damage or malfunctioning DNA repair, impaired tumor surveillance and viral clearance, and dysregulation of fundamental cellular processes such as activation, proliferation and apoptosis. Our growing understanding of the underlying mechanisms of lymphomagenesis provides opportunities for early detection, prevention and tailored treatment of lymphoma development.

Rituximab Toxicity after Preemptive or Therapeutic Administration for Post-Transplant Lymphoproliferative Disorder

Rituximab is commonly used as prevention, preemption, or therapeutically for post-transplant lymphoproliferative disorder (PTLD) after hematopoietic cell transplantation (HCT). Although it is generally assumed that rituximab toxicity (ie, infections resulting from hypogammaglobulinemia and neutropenia) is negligible in relation to mortality due to PTLD, limited evidence supports the validity of this assumption. We sought to determine the impact of rituximab on immunoglobulin levels, neutrophil count, infection density, and mortality outcomes. This study retrospectively analyzed 349 HCT recipients, 289 of whom did not receive rituximab and 60 of whom received rituximab preemptively or therapeutically at a median of 55 days post-transplantation. IgM, IgG, and IgA levels at 6 months and 12 months post-transplantation were lower in patients who received rituximab compared with those who did not (significant at P < .05 for IgM and IgA at 6 months and for IgM and IgG at 12 months). Rituximab recipients also had a higher incidence of severe neutropenia (<.5/nl) between 3 and 24 months (subhazard ratio [SHR], 2.3; P = .020). Regarding non-Epstein-Barr viral infections/PTLD, the rituximab group had a higher infection density between 3 and 24 months compared with the no-rituximab group (3.8 versus 1.6 infections per 365 days at risk; incidence rate ratio, 2.2; P < .001). The rituximab group also had a higher incidence of fatal infections (SHR, 3.1; P = .026), higher nonrelapse mortality (SHR, 2.4; P = .006), and higher overall mortality (hazard ratio, 1.7; P = .033). There were no significant between-group differences in the incidence of clinically significant graft-versus-host disease, graft failure, or relapse. Based on this study, rituximab given for PTLD is associated with substantial morbidity and mortality. Whether the benefit of preemptive rituximab outweighs the risk remains to be determined. © 2022 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Recent Advances in Adult Post-Transplant Lymphoproliferative Disorder

PTLD is a rare but severe complication of hematopoietic or solid organ transplant recipients, with variable incidence and timing of occurrence depending on different patient-, therapy-, and transplant-related factors. The pathogenesis of PTLD is complex, with most cases of early PLTD having a strong association with Epstein-Barr virus (EBV) infection and the iatrogenic, immunosuppression-related decrease in T-cell immune surveillance. Without appropriate T-cell response, EBV-infected B cells persist and proliferate, resulting in malignant transformation. Classification is based on the histologic subtype and ranges from nondestructive hyperplasias to monoclonal aggressive lymphomas, with the most common subtype being diffuse large B-cell lymphoma-like PTLD. Management focuses on prevention of PTLD development, as well as therapy for active disease. Treatment is largely based on the histologic subtype. However, given lack of clinical trials providing evidence-based data on PLTD therapy-related outcomes, there are no specific management guidelines. In this review, we discuss the pathogenesis, histologic classification, and risk factors of PTLD. We further focus on common preventive and frontline treatment modalities, as well as describe the application of novel therapies for PLTD and elaborate on potential challenges in therapy.

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.

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.

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.

Herpes Virus Infections Other than Cytomegalovirus in the Recipients of Hematopoietic Stem Cell Transplantation

This review discusses the epidemiologic and clinical aspects of herpes viruses other than cytomegalovirus in patients who have undergone hematopoietic stem cell transplantation.

Successful preemptive therapy with single-dose rituximab for Epstein-Barr virus infection to prevent post-transplant lymphoproliferative disease after pediatric hematopoietic stem cell transplantation

BACKGROUND

The efficacy of preemptive treatment containing rituximab to prevent post-transplant lymphoproliferative disease (PTLD) in children has not yet been fully elucidated.

METHODS

We analyzed 19 pediatric patients who developed high Epstein-Barr virus (EBV) DNAemia (EBV viral load of greater than 40 000 copies/mL) after allogeneic hematopoietic stem cell transplantation (HSCT) and were preemptively administered rituximab. Rituximab was intravenously injected at a dose of 375 mg/m² once the EBV viral load was greater than 40 000 copies/mL.

RESULTS

In all 19 patients, EBV DNAemia was eradicated after a median of 9 days (range, 3-20 days), and PTLD did not occur. One patient had transient fever, and four patients did not fully recover B cell counts after transplantation. We suggested that delayed B cell recovery was caused by chronic graft-versus-host disease (GVHD) related drugs, not rituximab administration. And there were no other infection-related side effects.

CONCLUSIONS

In conclusion, preemptive therapy containing rituximab is expected to reduce the incidence of PTLD after HSCT and improve post-transplantation outcomes in children.

Delayed immune reconstitution after allogeneic transplantation increases the risks of mortality and chronic GVHD

Slow immune reconstitution is a major obstacle to the successful use of allogeneic hematopoietic cell transplantation (allo-HCT). As matched sibling donor (MSD) allo-HCT is regarded as the gold standard, we evaluated the pace of immune reconstitution in 157 adult recipients of reduced-intensity conditioning followed by MSD peripheral blood HCT (n = 68) and compared these to recipients of umbilical cord blood (UCB; n = 89). At day 28, UCB recipients had fewer natural killer (NK) cells than MSD recipients, but thereafter, NK cell numbers (and their subsets) were higher in UCB recipients. During the first 6 months to 1 year after transplant, UCB recipients had slower T-cell subset recovery, with lower numbers of CD3⁺, CD8⁺, CD8⁺ naive, CD4⁺ naive, CD4⁺ effector memory T, regulatory T, and CD3⁺CD56⁺ T cells than MSD recipients. Notably, B-cell numbers were higher in UCB recipients from day 60 to 1 year. Bacterial and viral infections were more frequent in UCB recipients, yet donor type had no influence on treatment-related mortality or survival. Considering all patients at day 28, lower numbers of total CD4⁺ T cells and naive CD4⁺ T cells were significantly associated with increased infection risk, treatment-related mortality, and chronic graft-versus-host disease (GVHD). Patients with these characteristics may benefit from enhanced or prolonged infection surveillance and prophylaxis as well as immune reconstitution-accelerating strategies.

Human cord blood-derived viral pathogens as the potential threats to the hematopoietic stem cell transplantation safety: A mini review

Umbilical cord blood (UCB) is a valuable source of hematopoietic stem cells (HSCs) and potential alternative for bone marrow transplantation for patients who lack human leukocyte antigen (HLA)-matched donors. The main practical advantages of UCB over other HSC sources are the immediate availability, lower incidence of graft-versus-host disease, minimal risk to the donor, and lower requirement for HLA compatibility. However, the use of UCB is limited by delayed engraftment and poor immune reconstitution, leading to a high rate of infection-related mortality. Therefore, severe infectious complications, especially due to viral pathogens remain the leading cause of morbidity and mortality during the post-UCB transplantation (UCBT) period. In this context, careful screening and excluding the viral-contaminated UCB units might be an effective policy to reduce the rate of UCBT-related infection and mortality. Taken together, complete prevention of the transmission of donor-derived viral pathogens in stem cell transplantation is not possible. However, having the knowledge of the transmission route and prevalence of viruses will improve the safety of transplantation. To the best of our knowledge, there are few studies that focused on the risk of virus transmission through the UCB transplant compared to other HSC sources. This review summarizes the general aspects concerning the prevalence, characteristics, and risk factors of viral infections with a focus on the impact of viral pathogens on cord blood transplantation safety.

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).

Association of Epstein‑Barr virus infection with allogeneic hematopoietic stem cell transplantation in patients in Portugal

The identification of patients at higher risk of developing Epstein-Barr virus (EBV) infection in hematopoietic stem cell transplants (HSCT) is useful for the prevention of EBV-associated diseases A prospective observational study was developed that included 40 patients (27 male and 13 females, with mean age of 32.2±1.5 years old) undergoing allogeneic-HSCT between January and December 2015. EBV was examined in whole blood samples collected during routine procedures at day (D)+30, D +60, +90, D+120, D+150 and D+180 post-transplant. EBV was detected, at least once during the follow-up period in 70.0% of our patients. Results indicated that patients with unrelated donors had increased risk of developing EBV infection at D+60 and D+150 (OR=3.9, P=0.058; OR=8.0, P=0.043; respectively). Moreover, myeloablative conditioning (OR=4.3, P=0.052), anti-thymocyte globulin use (OR=12.0, P=0.030) and graft-vs.-host disease (OR=6.7, P=0.032) were associated with EBV infection at D+60, D+150 and D+90, respectively. In our series, none of these patients developed post-transplant lymphoproliferative disease. To the best of our knowledge, the present study is the first study to report EBV infection in patients undergoing aHSCT from Portugal. The study revealed that EBV infection is associated with different factors. These findings provide evidence towards the identification of high-risk patients for EBV-infection and associated disease.

Infections in Allogeneic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has become a widely used modality of therapy for a variety of malignant and nonmalignant diseases. Despite advances in pharmacotherapy and transplantation techniques, infection remains one of the most severe and frequently encountered complications of allo-HSCT.

This chapter will address the risk factors for development of infection following allo-HSCT, including those related to the host, the conditioning regimen, and the graft, as well as the timing of opportunistic infections after allo-HSCT. The most common bacterial, viral, fungal, and parasitic infections, as well as issues surrounding their diagnostics and treatment, will be discussed. Finally, this chapter will address vaccination and other preventative strategies to be utilized when caring for patients undergoing allo-HSCT.

Unrelated cord blood transplantation in patients with idiopathic refractory severe aplastic anemia: a nationwide phase 2 study

Outcomes remain poor for refractory severe aplastic anemia (SAA) patients. Alternative donor transplantation may be considered, but results from previous studies are not encouraging. We conducted a prospective nationwide phase 2 study to assess unrelated cord blood (CB) transplantation (CBT) efficacy and safety in refractory SAA patients (Aplastic Anemia and Cord Blood Transplantation protocol). To demonstrate a significant difference in 1-year survival from 20% (null hypothesis) to 50% (alternative hypothesis), we needed to include 25 transplanted patients and therefore included 26 (median age, 16 years). Eligibility criteria required 1 or 2 unrelated CB units, containing separately or together >4 × 10⁷ frozen nucleated cells (NCs) per kilogram of recipient body weight. Conditioning regimen comprised fludarabine (FLU), cyclophosphamide (CY), antithymocyte globulin (ATG), and 2-Gy total body irradiation (TBI). With a median follow-up of 38.8 months, engraftment occurred in 23 patients (88%); cumulative incidences of grade II-IV acute and chronic graft-versus-host disease were 45.8% and 36%, respectively. Twenty-three patients were alive at 1 year, with an 88.5% overall survival (OS) rate, differing significantly from the expected 20% (P < .0001; 84% OS at 2 years). CBT with units containing ≥4 × 10⁷ frozen NCs per kilogram is therefore a valuable curative option for young adults with refractory SAA and no available matched unrelated donors. This trial was registered at www.clinicaltrials.gov as #NCT01343953.

Epstein-barr virus DNAemia monitoring for the management of post-transplant lymphoproliferative disorder

BACKGROUND

Post-transplant lymphoproliferative disorder (PTLD) is a potentially fatal complication of allogeneic hematopoietic cell transplantation (HCT). Epstein-Barr virus (EBV) reactivation (detectable DNAemia) predisposes to the development of PTLD.

METHODS

We retrospectively studied 306 patients monitored for EBV DNAemia after Thymoglobulin-conditioned HCT to determine the utility of the monitoring in the management of PTLD. DNAemia was monitored weekly for ≥12 weeks post-transplantation.

RESULTS

Reactivation was detected in 82% of patients. PTLD occurred in 14% of the total patients (17% of patients with reactivation). PTLD was treated with rituximab only when and if the diagnosis was established. This allowed us to evaluate potential DNAemia thresholds for pre-emptive therapy. We suggest 100,000-500,000 IU per mL whole blood as this would result in unnecessary rituximab administration to only 4-20% of patients and near zero mortality due to PTLD. After starting rituximab (for diagnosed PTLD), sustained regression of PTLD occurred in 25/25 (100%) patients in whom DNAemia became undetectable. PTLD progressed or relapsed in 12/17 (71%) patients in whom DNAemia was persistently detectable.

DISCUSSION

In conclusion, for pre-emptive therapy of PTLD, we suggest threshold DNAemia of 100,000-500,000 IU/mL. Persistently detectable DNAemia after PTLD treatment with rituximab appears to have 71% positive predictive value and 100% negative predictive value for PTLD progression/relapse.

Management of Epstein-Barr Virus infections and post-transplant lymphoproliferative disorders in patients after allogeneic hematopoietic stem cell transplantation: Sixth European Conference on Infections in Leukemia (ECIL-6) guidelines

Epstein-Barr virus-related post-transplant lymphoproliferative disorders are recognized as a significant cause of morbidity and mortality in patients undergoing hematopoietic stem cell transplantation. To better define current understanding of post-transplant lymphoproliferative disorders in stem cell transplant patients, and to improve its diagnosis and management, a working group of the Sixth European Conference on Infections in Leukemia 2015 reviewed the literature, graded the available quality of evidence, and developed evidence-based recommendations for diagnosis, prevention, prophylaxis and therapy of post-transplant lymphoproliferative disorders exclusively in the stem cell transplant setting. The key elements in diagnosis include non-invasive and invasive methods. The former are based on quantitative viral load measurement and imaging with positron emission tomography; the latter with tissue biopsy for histopathology and detection of Epstein-Barr virus. The diagnosis of post-transplant lymphoproliferative disorder can be established on a proven or probable level. Therapeutic strategies include prophylaxis, preemptive therapy and targeted therapy. Rituximab, reduction of immunosuppression and Epstein-Barr virus-specific cytotoxic T-cell therapy are recommended as first-line therapy, whilst unselected donor lymphocyte infusions or chemotherapy are options as second-line therapy; other methods including antiviral drugs are discouraged.

New drugs and allogeneic hematopoietic stem cell transplantation for hematological malignancies: do they have a role in bridging, consolidating or conditioning transplantation treatment?

INTRODUCTION

Novel targeted therapies and monoclonal antibodies can be combined with allogeneic stem cell transplantation (allo-SCT) at different time-points: 1) before the transplant to reduce tumour burden, 2) as part of the conditioning in place of or in addition to conventional agents 3) after the transplant to allow long-term disease control. Areas covered: This review focuses on the current integration of new drugs with allo-SCT for the treatment of major hematological malignancies for which allo-SCT has been a widely-adopted therapy. Expert opinion: After having been used as single agent salvage treatments in relapsed patients after allo-SCT or in combination with donor lymphocyte infusions, many new drugs have also been safely employed before allo-SCT as a bridge to transplantation or after it as planned consolidation/maintenance. This era of new drugs has opened new important opportunities to 'smartly' combine 'targeted drugs and cell therapies' in new treatment paradigms that may lead to higher cure rates or longer disease control in patients with hematological malignancies.

Immunotherapy for infectious diseases in haematological immunocompromise

Opportunistic infections remain a major problem across a broad spectrum of immunocompromised haematological patient groups, with viruses, bacteria, fungi and protozoa all presenting significant challenges. Given the major difficulties in treating many of these infections with the currently available antimicrobial chemotherapeutic arsenal, and the rapid emergence of antimicrobial resistance amongst all of the microbial kingdoms, novel strategies that enable host control or elimination of infection are urgently required. Recently, major progress has been made in our understanding of host immunocompromise in the haematological patient. In addition, a wide range of novel immunomodulatory strategies for infectious diseases have been developed. Here we discuss the major and wide-ranging areas of progress that have been made for host-directed immunotherapies in the context of infectious diseases, with relevance to haematological immunocompromise.

Improving outcomes after allogeneic hematopoietic cell transplantation for Hodgkin lymphoma in the brentuximab vedotin era

Allogeneic hematopoietic cell transplantation (allo HCT) remains a valuable alternative for relapsed/refractory (R/R) Hodgkin lymphoma (HL). Data on allo HCT outcomes in the era of new HL therapies are needed. We evaluated 72 R/R HL patients who received reduced intensity conditioning (RIC) allo HCT and compared the time periods 2009-2013 (n=20) to 2000-2008 (n=52). Grafts included HLA-matched sibling (35%), unrelated donor (8%) and umbilical cord blood (UCB, 56%). In recent period, patients more often received brentuximab vedotin (BV, 60% vs 2%), had fewer comorbidities (Sorror index 0: 60% vs 12%) and were in complete remission (50% vs 23%). Median follow-up was 4.4 years. Three-year progression-free survival (PFS) improved for patients treated between 2009-2013 (49%, 95% CI 26-68%) as compared to the earlier era (23%, 95% CI 13-35%, p=0.02). Overall survival (OS) at 3-years was 84% (95% CI 57-94%) vs 50% (95% CI 36-62%, p=0.01), reflecting lower non-relapse mortality and relapse rates. In multivariate analysis mortality was higher among those with chemoresistance (HR 3.83, 95% CI 1.38-10.57), while treatment during the recent era was associated with better OS (HR for period 2009-2013: 0.24, 95% CI 0.07-0.79) and PFS (HR 0.46, 95% CI 0.23-0.92). Allo HCT in patients with R/R HL is now a more effective treatment.

The Epstein-Barr virus DNA load in the peripheral blood of transplant recipients does not accurately reflect the burden of infected cells

Transplant recipients frequently exhibit an increased Epstein-Barr virus (EBV) load in the peripheral blood. Here, we quantitated the EBV-infected cells in the peripheral blood of these patients and defined the mode of viral infection, latent or lytic. These data indicated that there is no strong correlation between the number of infected cells and the EBV load (EBVL). This can be explained by a highly variable number of EBV copies per infected cell and by lytic replication in some cells. The plasma of these patients did not contain any free infectious viruses, but contained nevertheless EBV DNA, sometimes in large amounts, that probably originates from cell debris and contributed to the total EBVL. Some of the investigated samples carried a highly variable number of infected cells in active latency, characterized by an expression of the Epstein-Barr nuclear antigens (EBNA2) protein. However, a third of the samples expressed neither EBNA2 nor lytic proteins. Patients with an increased EBVL represent a heterogeneous group of patients whose infection cannot be characterized by this method alone. Precise characterization of the origin of an increased EBVL, in particular, in terms of the number of EBV-infected cells, requires additional investigations including the number of EBV-encoded small RNA-positive cells.

Infectious Complications after Umbilical Cord-Blood Transplantation from Unrelated Donors

Umbilical cord-blood (UCB) is a well-recognized alternative source of stem cells for unrelated donor hematopoietic stem cell transplantation (HSCT). As compared with other stem cell sources from adult donors, it has the advantages of immediate availability of cells, absence of risk to the donor and reduced risk of graft-versus-host disease despite donor-recipient HLA disparity. However, the use of UCB is limited by the delayed post-transplant hematologic recovery due, at least in part, to the reduced number of hematopoietic cells in the graft and the delayed or incomplete immune reconstitution. As a result, severe infectious complications continue to be a leading cause of morbidity and mortality following UCB transplantation (UCBT). We will address the complex differences in the immune properties of UCB and review the incidence, characteristics, risk factors, and severity of bacterial, fungal and viral infectious complications in patients undergoing UCBT.

Antithymocyte globulin in allogeneic hematopoietic cell transplantation: benefits and limitations

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

Supportive care in alternative donor transplantation

Alternative donor hematopoietic cell transplantation (HCT) using umbilical cord blood, haploidentical or mismatched unrelated donors is a viable option for patients without human leukocyte antigen (HLA)-identical sibling or matched unrelated donors. The same principles of supportive care as conventional graft sources apply to alternative donor HCT recipients. However, there are some unique supportive care issues related to post-transplant complications, engraftment, graft-versus-host disease, immune reconstitution, and infections that are unique to each of the three alternative graft sources, both in the early and late post-transplant periods. This review discusses the supportive care issues relevant to this population and their management.

Reduced intensity haplo plus single cord transplant compared to double cord transplant: improved engraftment and graft-versus-host disease-free, relapse-free survival

Umbilical cord blood stem cell transplants are commonly used in adults lacking HLA-identical donors. Delays in hematopoietic recovery contribute to mortality and morbidity. To hasten recovery, we used co-infusion of progenitor cells from a partially matched related donor and from an umbilical cord blood graft (haplo-cord transplant). Here we compared the outcomes of haplo-cord and double-cord transplants. A total of 97 adults underwent reduced intensity conditioning followed by haplo-cord transplant and 193 patients received reduced intensity conditioning followed by double umbilical cord blood transplantation. Patients in the haplo-cord group were more often from minority groups and had more advanced malignancy. Haplo-cord recipients received fludarabine-melphalan-anti-thymocyte globulin. Double umbilical cord blood recipients received fludarabine-cyclophosphamide and low-dose total body irradiation. In a multivariate analysis, haplo-cord had faster neutrophil (HR=1.42, P=0.007) and platelet (HR=2.54, P<0.0001) recovery, lower risk of grade II-IV acute graft-versus-host disease (HR=0.26, P<0.0001) and chronic graft-versus-host disease (HR=0.06, P<0.0001). Haplo-cord was associated with decreased risk of relapse (HR 0.48, P=0.001). Graft-versus-host disease-free, relapse-free survival was superior with haplo-cord (HR 0.63, P=0.002) but not overall survival (HR=0.97, P=0.85). Haplo-cord transplantation using fludarabine-melphalan-thymoglobulin conditioning hastens hematopoietic recovery with a lower risk of relapse relative to double umbilical cord blood transplantation using the commonly used fludarabine-cyclophosphamide-low-dose total body irradiation conditioning. Graft-versus-host disease-free and relapse-free survival is significantly improved. Haplo-cord is a readily available graft source that improves outcomes and access to transplant for those lacking HLA-matched donors. Trials registered at clinicaltrials.gov identifiers 00943800 and 01810588.

In Vivo T Cell Depletion with Myeloablative Regimens on Outcomes after Cord Blood Transplantation for Acute Lymphoblastic Leukemia in Children

The inclusion of antithymocyte globulin (ATG) in cord blood transplantation is controversial. We evaluated outcomes according to ATG inclusion in 297 children and adolescents with acute lymphoblastic leukemia (ALL) who received myeloablative total body irradiation-based conditioning and either single-unit (74%) or double-unit (26%) grafts. Ninety-two patients (31%) received ATG and 205 (69%) did not. ATG recipients were more likely to be cytomegalovirus seronegative. The incidences of day 100 grades II to IV acute graft-versus-host disease (GVHD; 30% versus 54%, P = .0002) and chronic GVHD (22% versus 43%, P = .0008) were lower with ATG compared with non-ATG regimens. However, day 100 grades III to IV acute GVHD was comparable (11% versus 17%, P = .15). The 3-year incidences of transplant-related mortality (16% versus 17%, P = .98), relapse (17% versus 27%, P = .12), and leukemia-free survival (66% versus 55%, P = .23) in ATG and non-ATG recipients were similar. There were no differences in viral reactivation between treatment groups (60% versus 58%, P = .83). Therefore, the data suggest that incorporation of ATG with myeloablative conditioning regimens may be useful in reducing the risk of acute and chronic GVHD without any deleterious effect on transplant-related mortality, relapse, or leukemia-free survival in children and adolescents with ALL.

Topping it up: methods to improve cord blood transplantation outcomes by increasing the number of CD34+ cells

Cord blood is increasingly recognized for its excellent stem cell potential, lenient matching criteria, instant availability and clinical behavior in transplants when cell dose criteria can be met. However with 1-2 log fewer total (stem cell) numbers in the graft compared with other cell sources, the infused cell dose per kilogram is critical for engraftment and outcome, creating the need for development of stem cell support platforms. The co-transplant platforms of haplo cord and double unit cord blood (DUCB) transplantation are aimed toward increasing stem cell dose. Together with the optimization of reduced-intensity protocols, long-term sustained engraftment using cord blood has become available to most patients, including elderly patients. Haplo cord has a low incidence of both acute and chronic graft-versus-host disease but may require anti-thymocyte globulin ATG for effective neutrophil recovery. DUCB can be performed without anti-thymocyte globulin with excellent immune reconstitution and disease-free survival, but engraftment is considerably slower, and graft-versus-host disease incidence significant. Both haplo-cord and DUCB transplantation appear to both be valid alternatives to matched unrelated donors in adults.

Impact of Epstein Barr virus-related complications after high-risk allo-SCT in the era of pre-emptive rituximab

We monitored 133 high-risk allo-SCT recipients for 6 months after transplant for EBV reactivation by quantitative real-time PCR. Rituximab was given as pre-emptive therapy for viremia >1000 copies/mL. The 1-year cumulative incidence of EBV reactivation was 29.4% (95% confidence interval (CI): 18-40) in patients monitored due to initial high-risk characteristics (n=93) and 31.8% (95% CI: 19.7-44) in those followed because of the development of refractory GVHD (n=40). Overall response rate to Rituximab was 83%. Nine patients (9.6%) developed post-transplant lymphoproliferative disorder (PTLD) at a median of +62 days after SCT. Eight of them showed a concomitant CMV reactivation. Second SCT was the only risk factor associated with EBV infection and PTLD in multivariate analysis (hazard ratio (HR) 2.6 (95% CI: 1.1-6.4; P=0.04) and HR 6.4 (95%CI: 1.3-32; P=0.02)). The development of EBV reactivation was not associated with non-relapse mortality or OS (P=0.97 and P=0.84, respectively).

Epstein-Barr virus infection in adult renal transplant recipients

Epstein-Barr virus (EBV) DNAemia in the first year posttransplantation has been studied extensively. There is a paucity of information on prevalence and sequelae of EBV infection in adult renal transplantation beyond the first year. This single-center study examines the relationship between EBV DNAemia and demographic, immunosuppressive, hematologic and infection-related parameters in 499 renal transplant recipients between 1 month and 33 years posttransplant. Participants were tested repeatedly for EBV DNAemia detection over 12 months and clinical progress followed for 3 years. Prevalence of DNAemia at recruitment increased significantly with time from transplant. In multivariate adjusted analyses, variables associated with DNAemia included EBV seronegative status at transplant (p = 0.045), non-White ethnicity (p = 0.014) and previous posttransplant lymphoproliferative disease (PTLD) diagnosis (p = 0.006), while low DNAemia rates were associated with mycophenolate mofetil use (p < 0.0001) and EBV viral capsid antigen positive Epstein-Barr nuclear antigen-1 positive serostatus at transplant (p = 0.044). Patient and graft survival, rate of kidney function decline and patient reported symptoms were not significantly different between EBV DNAemia positive and negative groups. EBV DNAemia is common posttransplant and increases with time from transplantation, but EBV DNAemia detection in low-risk (seropositive) patients has poor specificity as a biomarker for future PTLD risk.

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.

Absence of post-transplantation lymphoproliferative disorder after allogeneic blood or marrow transplantation using post-transplantation cyclophosphamide as graft-versus-host disease prophylaxis

Immunosuppressive regimens that effectively prevent graft-versus-host disease (GVHD) after allogeneic blood or marrow transplantation (allo-BMT) have been associated with an increased incidence of post-transplantation lymphoproliferative disorder (PTLD) in the first year after transplantation. We evaluated the incidence of PTLD associated with the use of high-dose post-transplantation cyclophosphamide (PTCy) as GVHD prophylaxis. Between 2000 and 2011, a total of 785 adult allo-BMT recipients were given PTCy as GVHD prophylaxis at the Johns Hopkins Hospital, including 313 patients who received PTCy as sole GVHD prophylaxis. HLA-haploidentical or unrelated donor graft transplantation was performed in 526 patients (67%). No cases of PTLD occurred during the first year after allo-BMT in this series. PTLD is a rare occurrence after allo-BMT using PTCy, even in high-risk alternative donor transplantations.

EBV-induced post transplant lymphoproliferative disorders: a persisting challenge in allogeneic hematopoetic SCT

EBV-induced post transplantation lymphoproliferative disorder (EBV-PTLD) is a life-threatening complication after allogeneic hematopoietic cell transplantation. Profound T-cell depletion of the allograft represents a major risk factor for EBV-PTLD. With regard to the increasing use of alternative stem cell sources such as cord blood or purified haploidentical stem cell grafts both associated with impaired immune reconstitution, the frequent occurrence of EBV-PTLD demands particular vigilance on laboratory changes and early symptoms. Here we have summarized today's knowledge about EBV-PTLD in a comprehensive review explaining the underlying mechanisms of EBV-based transformation, EBV-PTLD development, clinical presentation, incidence, diagnosis, screening, therapy and prognosis. In this context, we emphasize on the necessity of regularly applied screening tools and pre-emptive treatment strategies including anti-CD20 Abs particularly in high-risk patients to avoid disease progression to malignant lymphoma. Although EBV-PTLD has always been associated with a high mortality rate, novel immunotherapeutic approaches such as the transfer of EBV-specific T cells nowadays offer improved chances of disease control even at late stages.

Infections in Leukemia and Hematopoietic Stem Cell Transplantation

Infections are one of the most common complications in patients diagnosed with leukemia and serve as a major obstacle to treatment. Through the early 1970s, infections were the most common cause of death in patients diagnosed with acute leukemia, but improvement in treatment and supportive care over the past few decades, coupled with expanded prophylaxis and prevention regimens, have led to reduction in both the frequency and severity of infections. Regardless, due in part to an aging cancer population and the diversity of cancer treatments and procedures, infectious diseases remain a major cause of morbidity and mortality in patients with leukemia.

Selection of optimal alternative graft source: mismatched unrelated donor, umbilical cord blood, or haploidentical transplant

Only 30% of patients who require an allogeneic hematopoietic cell transplant will have an HLA-matched sibling donor. A search for an unrelated donor will be undertaken for patients without a matched family donor. However, many patients, particularly patients of diverse racial and ethnic backgrounds, may not be able to rapidly identify a suitably matched unrelated donor. Three alternative graft sources, umbilical cord blood (UCB), haploidentical (haplo)-related donor, and mismatched unrelated donor (MMUD) are available. UCB is associated with decreased GVHD, but hematologic recovery and immune reconstitution are slow. Haplo-HCT is characterized by donor availability for transplantation and after transplantation adoptive cellular immunotherapy but may be complicated by a high risk of graft failure and relapse. A MMUD transplant may also be an option, but GVHD may be of greater concern. Phase 2 studies have documented advances in HLA typing, GVHD prophylaxis, and infection prevention, which have improved survival. The same patient evaluated in different transplant centers may be offered MMUD, UCB, or haplo-HCT depending on center preference. In this review, we discuss the rationale for donor choice and the need of phase 3 studies to help answer this important question.

Reduced-intensity conditioning stem cell transplantation: comparison of double umbilical cord blood and unrelated donor grafts

There are little data comparing umbilical cord blood (UBC) and conventional stem cell sources for reduced-intensity conditioning (RIC) hematopoietic stem cell transplantation (HSCT). We performed a retrospective analysis of RIC HCST using double UCB (dUCB) grafts and RIC HSCT using unrelated donor (URD) grafts. The study included 64 dUCB transplantations and 221 URD transplantations performed at Dana-Farber Cancer Institute and Massachusetts General Hospital between 2004 and 2008. The cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) was 14.1% for dUCB and 20.3% for URD (P = .32). The 2-year cumulative incidence of chronic GVHD was significantly lower in dUCB compared with URD (21.9% versus 53.9%; P < .0001). The 2-year cumulative incidence of nonrelapse mortality was significantly higher in dUCB (26.9% versus 10.4%; P = .0009). In our analysis, dUCB HSCT and URD HSCT had comparable 3-year overall survival (46% in dUCB and 50% in URD; P = .49) and progression-free survival (30% in dUCB and 40% in URD; P = .47). dUCBT was associated with greater nonrelapse mortality despite less chronic GVHD. Our findings suggest that the use of 2 partially matched UCB units appears to be a suitable alternative for patients undergoing RIC HSCT without an HLA-matched donor.

Graft-vs-Host Disease following Allogeneic Hematopoietic Cell Transplantation

Background

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

Methods

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

Results

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

Conclusions

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

Secondary cancers following allogeneic haematopoietic cell transplantation in adults

Secondary cancers that arise in allogeneic haematopoietic-cell transplant recipients, possibly as a result of treatment exposures, are a relatively rare complication of transplantation. However, they can be associated with significant morbidity and mortality. Secondary cancers include post-transplant lymphoproliferative disorders, new solid cancers and donor-derived haematological malignancies. This review describes the epidemiology, risk factors and screening recommendations for secondary cancers among adult allogeneic haematopoietic-cell transplant recipients. Constructing a patient-specific risk profile based on known exposures and risk-factors is the key to developing appropriate screening and preventative strategies for secondary cancers after allogeneic transplantation.

Immunotherapy against EBV-lymphoma in recipients of HSCT

Epstein-Barr virus (EBV)-associated lymphoproliferations represent life-threatening complications of hematopoietic stem cell transplantation. In the last decade, immunological therapeutic strategies that allow us to selectively abrogate the origin of lymphoproliferation, namely B-cell compartment or EBV antigen-expressing tumor cells, have significantly reduced treatment-related toxicity while maintaining equal or superior efficacy. A further implementation is the possibility of preventing disease occurrence by delivering immunotherapy in the presymptomatic phase, on the basis of EBV-DNA blood levels. Despite the excellent results, T-cell therapy with EBV-specific cytotoxic T-lymphocytes has but a marginal role in the treatment of these forms. Promising implementations are underway, including logistic solutions to extend T-cell therapy beyond academic centers, delineation of strategies aimed at simplifying/shortening production and targeting immune evasion mechanisms exerted by tumor cells.

Strategies to prevent EBV reactivation and posttransplant lymphoproliferative disorders (PTLD) after allogeneic stem cell transplantation in high-risk patients

Epstein-Barr virus (EBV)-associated postallogeneic stem cell transplantation (SCT) lymphoproliferative disorder (PTLD) is often life threatening. The risk of EBV reactivation is highest in older patients, T cell-depleted SCT (in vivo or vitro), and in unrelated or mismatched SCT. Cumulative numbers of patients with EBV reactivation and PTLD are rising as more patients at high risk for EBV reactivation and PTLD are receiving allo-SCT. Novel but easily applicable strategies are needed to prevent EBV reactivation and PTLD to serve the needs of the increasingly enlarging population of high-risk SCT recipients across the globe.

Association of HLA polymorphisms with post-transplant lymphoproliferative disorder in solid-organ transplant recipients

The association between HLA polymorphisms and PTLD was investigated in a case-control study, comparing 110 predominantly adult solid-organ transplant recipients who developed PTLD to 5601 who did not. Donor and recipient HLA were analyzed. We detected a significant association between recipient HLA-A26 and the development of PTLD (OR 2.74; p = 0.0007). In Caucasian recipients, both recipient and donor HLA-A26 were independently associated with development of PTLD (recipient A26 OR 2.99; p = 0.0004, donor A26 OR 2.81; p = 0.002). Analysis of HLA-A and -B haplotypes revealed that recipient HLA-A26, B38 haplotype was strongly correlated with a higher incidence of EBV-positive PTLD (OR 3.99; p = 0.001). The common ancestral haplotype HLA-A1, B8, DR3, when carried by the donor, was protective against PTLD (OR 0.41; p = 0.05). Several other HLA specificities demonstrated associations with clinical and pathological characteristics as well as survival. These findings demonstrate the importance of HLA polymorphisms in modulating the risk for PTLD, and may be useful in risk stratification and development of monitoring and prophylaxis strategies.

Features of EBV reactivation after reduced intensity conditioning unrelated umbilical cord blood transplantation

This single centre study assessed the incidence, kinetics and predictive factors of EBV reactivation and EBV-related lymphoproliferative diseases (LPD) in 33 consecutive patients who received a reduced intensity conditioning (RIC) before umbilical cord blood transplantation (UCBT). During the first 6 months after UCBT, weekly all patients were DNA-PCR screened in the peripheral blood for EBV reactivation and were clinically monitored for clinical features attributable to EBV. The cumulative incidences of EBV reactivation (defined as an EBV load >1000 EBV copies per 10(5) cells measured at least once during follow-up) at 6 months and 2 years after UCBT were 9 (95% confidence interval (CI), 2-22%) and 17% (95% CI, 6-33%), respectively. In 28 patients (85%), the EBV load remained negative at all times, and none of these patients experienced any sign of LPD. Five patients (15%) experienced at least one EBV reactivation episode. EBV reactivation was observed at a median of 132 days (range, 85-438) after UCBT. Two patients developed EBV-related LPD (cumulative incidence, 6% at 3 years). With a median follow-up of 468 days (range, 92-1277) post UCBT, the OS was 62% at 3 years. Five patients died of disease progression and seven patients died of transplant-related complications, including one case of EBV-related LPD. Univariate analysis did not identify any significant risk factor associated with EBV reactivation. We conclude that patients undergoing RIC UCBT are at risk for EBV reactivation, with the need for close EBV monitoring and the use of preemptive rituximab treatment as some cases may progress to life-threatening LPD.

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

This single centre study assessed the incidence, kinetics and predictive factors of Epstein-Barr Virus (EBV) reactivation and EBV-related lymphoproliferative diseases (LPDs) in 175 consecutive patients who received a reduced-intensity conditioning (RIC) before allogeneic hematopoietic stem cell transplantation (allo-HSCT). The cumulative incidence of EBV reactivation at 6 months after allo-HSCT defined as an EBV PCR load above 1000 copies of EBV DNA/10(5) cells was 15%, and none of these patients experienced any sign or symptom of LPD. A total of 17 patients, who had EBV DNA levels exceeding 1000 copies/10(5) cells on two or more occasions, were pre-emptively treated with rituximab. With a median follow-up of 655 (range, 92-1542) days post allo-HSCT, there was no statistically significant difference in term of outcome between those patients who experienced an EBV reactivation and those who did not. In multivariate analysis, the use of antithymocyte globulin as part of the RIC regimen was the only independent risk factor associated with EBV reactivation (relative risk=4.9; 95% confidence interval, 1.1-21.0; P=0.03). We conclude that patients undergoing RIC allo-HSCT using anti-thymocyte globulin as part of the preparative regimen are at higher risk for EBV reactivation. However, this did not impact on outcome, as quantitative monitoring of EBV viral load by PCR and preemptive rituximab therapy allowed for significantly reducing the risk of EBV-related LPD.