Incidence and risk factors of EBV reactivation after unrelated cord blood transplantation: a Eurocord and Société Française de Greffe de Moelle-Therapie Cellulaire collaborative study. Bone Marrow Transplant. 2013;48:253-256. [PMID: 22773124 DOI: 10.1038/bmt.2012.117]

A Pilot Study of UM171-Expanded Cord Blood Grafts for Tandem Auto/Allogeneic Hematopoietic Cell Transplant in High and Ultra-High-Risk Myeloma Patients

BACKGROUND

Multiple myeloma (MM) remains associated with a poor outcome, particularly in patients with advanced disease and high-risk (HR) cytogenetics. To date, the only curative treatment is allogeneic (allo) hematopoietic cell transplantation (HCT), but high incidences of graft versus host disease (GVHD), non-relapse mortality (NRM) and disease progression remain important obstacles. Cord blood (CB) transplantation has been associated with low rates of relapse and chronic (c) GVHD, but its use has declined because of high incidences of infections, severe acute GVHD and high NRM. In other hematologic malignancies, UM171-expanded CB transplants have led to improved outcomes, allowing for the selection of smaller, better HLA-matched units.

OBJECTIVE

We aimed to investigate the safety and feasibility of single UM171-expanded single CB unit transplantation in frontline tandem auto/allo HCT for HR/ultra-HR MM patients.

STUDY DESIGN

Newly diagnosed MM patients ≤ 65 years with an ISS stage II/III and del17p, t4,14, t14,16, t14,20, del1p or +1q, R-ISS 3, ≥ 2 cytogenetic abnormalities, or plasma cell leukemia without a sibling donor and availability of a 5-7/8 matched CB graft with ≥ 0.5 x 105 CD34+/kg and ≥ 1.5 x 107 TNCs/kg were eligible to this phase I/II prospective study (ClinicalTrials.gov NCT03441958). After induction and autologous HCT, patients received a reduced intensity conditioning regimen and were infused with 7-day UM171-expanded CD34+ cells, along with the lymphocytes contained in the CD34-negative fraction. The primary endpoints were feasibility of UM171 expansion, safety, kinetics of engraftment, incidences and maximum grades of acute and cGVHD at 1 and 2 years, assessment of measurable residual disease (MRD) and quality of life (QoL).

RESULTS

Between 05/2018 and 11/2021, 20 patients were enrolled. One patient had an unsuccessful CB expansion with UM171, leaving 19 patients with a median age of 56 years. Median CD34+ cell dose infused after expansion was 4.62 x 106/kg (range: 0.79-5.76). Median times to achieve absolute neutrophil counts of 0.1 and 0.5 x 109/L were D+6 and D+10.5; median time to reach ≥ 20 x 109/L platelets was D+36. Full donor chimerism was achieved in all cell lineages by D+120 in recipients of reduced intensity conditioning. Cumulative incidences of grade II-IV, grade III-IV acute GVHD and moderate/severe cGVHD at 12 months were 68.4% (95% CI: 46-90), 5.3% (95% CI: 0-16%), and 10.5% (95% CI: 0-25%), respectively. With a median follow-up of 2.9 years (range: 0.46-5.3), cumulative incidences of relapse, PFS, OS and NRM at 3 years were 36.8% (95% CI: 14-59), 47.4% (95% CI: 29-76), 68.4% (95% CI: 50-93) and 15.8% (95%CI: 0-33), respectively. Median time to complete immunosuppression discontinuation was D+238. No unexpected adverse events were observed. Only one of 7 patients alive at 2 years with negative MRD at transplant has relapsed. Non-relapsing patients had a QoL after transplant similar to the general population.

SIGNIFICANCE

UM171-expanded CB transplant in HR/ultra-HR myeloma patients is feasible and allows the use of single CB units with a low risk of cGVHD. Patients with negative pre-transplant MRD might benefit most from a UM171-expanded CB transplant.

Immunology of cord blood T-cells favors augmented disease response during clinical pediatric stem cell transplantation for acute leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) has been an important and efficacious treatment for acute leukemia in children for over 60 years. It works primarily through the graft-vs.-leukemia (GVL) effect, in which donor T-cells and other immune cells act to eliminate residual leukemia. Cord blood is an alternative source of stem cells for transplantation, with distinct biological and immunological characteristics. Retrospective clinical studies report superior relapse rates with cord blood transplantation (CBT), when compared to other stem cell sources, particularly for patients with high-risk leukemia. Xenograft models also support the superiority of cord blood T-cells in eradicating malignancy, when compared to those derived from peripheral blood. Conversely, CBT has historically been associated with an increased risk of transplant-related mortality (TRM) and morbidity, particularly from infection. Here we discuss clinical aspects of CBT, the unique immunology of cord blood T-cells, their role in the GVL effect and future methods to maximize their utility in cellular therapies for leukemia, honing and harnessing their antitumor properties whilst managing the risks of TRM.

The impact of Rituximab administered before transplantation in patients undergoing allogeneic hematopoietic stem cell transplantation: A real-world study

Rituximab is used to eliminate B cells as a chimeric monoclonal antibody directed against CD20, a B-cell antigen expressed on B cells. To explore the impact of rituximab administered before transplantation, we implemented a retrospective, monocentric study and utilized real-world data collected at our center between January 2018 and December 2020, and then followed until December 2021. Based on whether a dose of 375mg/m2 rituximab was used at least once within two weeks before transplantation, patients undergoing allo-HSCT were classified into two groups: rituximab (N=176) and non-rituximab (N=344) group. Amongst all the patients, the application of rituximab decreased EBV reactivation (P<0.01) and rituximab was an independent factor in the prevention of EBV reactivation by both univariate and multivariate analyses (HR 0.56, 95%CI 0.33-0.97, P=0.04). In AML patients, there were significant differences in the cumulative incidence of aGVHD between the two groups (P=0.04). Our data showed that rituximab was association with a decreased incidence of aGVHD in AML patients according to both univariate and multivariate analyses. There was no difference between the two groups in other sets of populations. Thus, our study indicated that rituximab administered before transplantation may help prevent EBV reactivation in all allo-HSCT patients, as well as prevent aGVHD in AML patients after allo-HSCT.

Clinical Characteristics of Posttransplant Lymphoproliferative Disorder After Cord Blood Transplantation Without Antithymocyte Globulin

BACKGROUND

CBT with ATG use is a well-known PTLD risk factor. However, little is known regarding the clinical features of PTLD after ATG-free CBT.

PATIENTS AND METHODS

We analyzed the incidence, risk factors and prognosis of PTLD in 183 adults undergoing ATG-free CBT.

RESULTS

Fifteen patients (diffuse large B-cell lymphoma, n = 9, mucosa-associated lymphoid tissue lymphoma, n = 2 nondestructive PTLD, n = 1, T-cell lymphoma, n = 3) developed PTLD. The 2-year CuI of PTLD was 8.0% (95% CI: 4.6-12.7). Pathologically, all 12 B-cell PTLD patients had Epstein-Barr virus (EBV), compared with 1 of 3 T-cell PTLD patients. All patients, excluding one with nondestructive PTLD, showed extranodal involvement. In the univariate analysis, the 2-year CuI of PTLD was significantly higher in patients who received mycophenolate mofetil to prevent graft-versus-host disease than in nonrecipients (11.2%/2.9%, P = .0457). However, multivariate analysis revealed no independent PTLD risk factors. All 11 PTLD patients who received specific therapy achieved complete remission. The 1-year overall survival of PTLD patients was 70.9%.

CONCLUSION

Although we found a higher CuI of PTLD than previously reported, the prognosis was generally good. In CBT recipients, many factors, including MMF use, may be associated with the clinical features of PTLD.

Epstein-Barr Virus Reactivation After Paediatric Haematopoietic Stem Cell Transplantation: Risk Factors and Sensitivity Analysis of Mathematical Model

Epstein-Barr virus (EBV) establishes a lifelong latent infection in healthy humans, kept under immune control by cytotoxic T cells (CTLs). Following paediatric haematopoetic stem cell transplantation (HSCT), a loss of immune surveillance leads to opportunistic outgrowth of EBV-infected cells, resulting in EBV reactivation, which can ultimately progress to post-transplant lymphoproliferative disorder (PTLD). The aims of this study were to identify risk factors for EBV reactivation in children in the first 100 days post-HSCT and to assess the suitability of a previously reported mathematical model to mechanistically model EBV reactivation kinetics in this cohort. Retrospective electronic data were collected from 56 children who underwent HSCT at Great Ormond Street Hospital (GOSH) between 2005 and 2016. Using EBV viral load (VL) measurements from weekly quantitative PCR (qPCR) monitoring post-HSCT, a multivariable Cox proportional hazards (Cox-PH) model was developed to assess time to first EBV reactivation event in the first 100 days post-HSCT. Sensitivity analysis of a previously reported mathematical model was performed to identify key parameters affecting EBV VL. Cox-PH modelling revealed EBV seropositivity of the HSCT recipient and administration of anti-thymocyte globulin (ATG) pre-HSCT to be significantly associated with an increased risk of EBV reactivation in the first 100 days post-HSCT (adjusted hazard ratio (AHR) = 2.32, P = 0.02; AHR = 2.55, P = 0.04). Five parameters were found to affect EBV VL in sensitivity analysis of the previously reported mathematical model. In conclusion, we have assessed the effect of multiple covariates on EBV reactivation in the first 100 days post-HSCT in children and have identified key parameters in a previously reported mechanistic mathematical model that affect EBV VL. Future work will aim to fit this model to patient EBV VLs, develop the model to account for interindividual variability and model the effect of clinically relevant covariates such as rituximab therapy and ATG on EBV VL.

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.

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.

Viral Infections in HSCT: Detection, Monitoring, Clinical Management, and Immunologic Implications

In spite of an increasing array of investigations, the relationships between viral infections and allogeneic hematopoietic stem cell transplantation (HSCT) are still controversial, and almost exclusively regard DNA viruses. Viral infections per se account for a considerable risk of morbidity and mortality among HSCT recipients, and available antiviral agents have proven to be of limited effectiveness. Therefore, an optimal management of viral infection represents a key point in HSCT strategies. On the other hand, viruses bear the potential of shaping immunologic recovery after HSCT, possibly interfering with control of the underlying disease and graft-versus-host disease (GvHD), and eventually with HSCT outcome. Moreover, preliminary data are available about the possible role of some virome components as markers of immunologic recovery after HSCT. Lastly, HSCT may exert an immunotherapeutic effect against some viral infections, notably HIV and HTLV-1, and has been considered as an eradicating approach in these indications.

Hematopoietic cell transplantation in pediatric patients with acute leukemias or myelodysplastic syndrome using unrelated adult or umbilical cord blood donors in Brazil

The choice of alternative donors for HCT for patients without an HLA-matched related donor depends on several factors. We compared major HCT outcomes in 212 consecutive children transplanted at 11 centers in Brazil for acute leukemia or MDS from an HLA-matched unrelated donor (MUD, n = 95), mismatched unrelated donor (MMUD, n = 47) or unrelated umbilical cord blood (UCB, n = 70). Most had ALL (61%), bone marrow (57%) as the graft source and 95% received a MAC regimen. The 3-year OS probability were 57, 55, and 37% after HCT from MUD, MMUD, and UCB, respectively (HR 1.68, 95%CI 1.07-2.63; P = .02). In comparison with MUD, OS was similar after transplantation of a ≥ 6/8 HLA-matched or a high cell dose (>5 × 10⁷ TNC/kg) CB unit (HR 1.41, 95%CI 0.88-2.27; P = .15). NRM was higher for UCB (HR 3.90, 95%CI 1.43-10.7; P = .01) but not for MMUD (HR 1.03, 95%CI 0.53-2.00; P > .20). Advanced disease (HR 2.05, 95%CI 1.26-3.33; P < .001) and UCB with high probability of being < 6/8 HLA-matched (HR 5.34, 95%CI 2.0-13.9; P < .001) were associated with higher mortality. Relapse and acute GVHD were similar among groups, while PGF was higher among UCB transplants (P = .002) and chronic GVHD among MMUD group (HR 2.88, 95% CI 1.05-7.88; P = .04). Our results suggest that in Brazil HCT outcomes performed with MMUD and MUD donors were comparable, while with UCB units < 6/8 HLA-matched were associated with higher NRM for children with acute leukemia or MDS.

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.

Epstein-Barr Virus-Associated Post-Transplant Lymphoproliferative Disorders after Hematopoietic Stem Cell Transplantation: Pathogenesis, Risk Factors and Clinical Outcomes

Epstein-Barr virus (EBV) is a ubiquitous virus belonging to the human γ-herpes virus subfamily. After primary infection, EBV maintains a life-long latent infection. A major concern is that EBV can cause a diverse range of neoplasms and autoimmune diseases. In addition, patients undergoing hematopoietic stem cell transplantation or solid organ transplantation can experience post-transplant lymphoproliferative disorders (PTLDs) due to dysfunction or suppression of host’s immune system, or uncontrolled proliferation of EBV-infected cells. In recent years, the number of EBV-associated PTLD cases has increased. This review focuses on the current understandings of EBV-associated PTLD pathogenesis, as well as the risk factors and clinical outcomes for patients after allogeneic stem cell transplantation.

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.

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.

Haploidentical transplantation is associated with better overall survival when compared to single cord blood transplantation: an EBMT-Eurocord study of acute leukemia patients conditioned with thiotepa, busulfan, and fludarabine

Background

Thiotepa-busulfan-fludarabine (TBF) is a widely used conditioning regimen in single umbilical cord blood transplantation (SUCBT). More recently, it was introduced in the setting of non-T cell depleted haploidentical stem cell transplantation (NTD-Haplo). Whether TBF based conditioning provides additional benefit in transplantation from a particular alternative donor type remains to be established.

Methods

This was a retrospective study based on an international European registry. We compared outcomes of de-novo acute myeloid leukemia patients in complete remission receiving NTD-Haplo (n = 186) vs. SUCBT (n = 147) following myeloablative conditioning (MAC) with TBF. Median follow-up was 23 months. Treatment groups resembled in baseline characteristics.

Results

SUCBT was associated with delayed engraftment and higher graft failure. In multivariate analysis no statistically significant differences were observed between the two groups in terms of acute or chronic graft-versus-host disease (GvHD) (HR = 1.03, p = 0.92 or HR = 1.86, p = 0.21) and relapse incidence (HR = 0.8, p = 0.65). Non-relapse mortality (NRM) was significantly higher in SUCBT as compared to NTD-Haplo (HR = 2.63, p = 0.001); moreover, SUCBT did worse in terms of overall survival (HR = 2.18, p = 0.002), leukemia-free survival (HR = 1.94, p = 0.007), and GvHD relapse-free survival (HR = 2.38, p = 0.0002).

Conclusions

Our results suggest that TBF-MAC might allow for a potent graft-versus-leukemia, regardless of the alternative donor type. Furthermore, in patients receiving TBF-MAC, survival with NTD-Haplo may be better compared to SUCBT due to decreased NRM.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0655-8) contains supplementary material, which is available to authorized users.

Epstein-Barr virus post-transplant lymphoproliferative disease (PTLD) after hematopoietic stem cell transplantation

Epstein-Barr virus (EBV) viremia and post-transplant lymphoproliferative disease (PTLD) are severe complications after hematopoietic stem cell transplantation (HSCT). A series of risk factors have been found to predict EBV viremia and PTLD, including the T-cell depletion, reduced intensity conditioning, and alternative donor. The rituximab pre-emptive therapy could improve PTLD prognosis significantly, but the trigger of initiating rituximab pre-emptive therapy has not been well established. Additionally, EBV-specific cytotoxic T cell (CTL) is a promising approach to treat EBV-PTLD.

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.

Hematopoietic cell transplantation: Training challenges and potential opportunities through networking and integration of modern technologies to the practice setting

Hematopoietic cell transplantation (HCT), particularly allogeneic HCT, is a complex and a high-risk procedure requiring expertise to manage potential treatment complications. Published data supports the value of quality management systems in improving post-transplant outcomes; however, there are no universally established, or agreed upon, criteria to assess adequacy of training of physicians, transplant or nontransplant, and supporting staff, among others. It is of paramount importance for transplant centers to identify the needed area(s) of expertise in order to seek appropriate training for their staff. Moreover, transplant physicians need to keep up-to-date with the rapidly occurring advances in the field. Outcomes of patients undergoing HCT are affected by various factors related to patient, disease, procedure, preventative, and supportive strategies, among others. Accordingly, availability of databases is necessary to collect information on these variables and use to benchmark future prospective clinical trials aiming at further improving clinical outcomes. Twinning with leading centers worldwide is helping to not only bridge the survival gap of patients diagnosed with cancer in the developing vis-à-vis the developed world, but eventually closing it. The advent of the World Wide Web and revolution in telecommunication has made access to information more readily available to various sectors including healthcare. Telemedicine is enabling healthcare delivery to remote and underserved geographic areas. In the setting of HCT, ensuring compliance to prescribed therapies and post-transplant surveillance are some areas where implementing telemedicine programs could fulfill an unmet need.

Reconstitution of adaptive immunity after umbilical cord blood transplantation: impact on infectious complications

In comparison with allogeneic stem cell transplantation (alloHSCT) with other stem cell sources, umbilical cord blood transplantation (UCBT) was traditionally associated with increased risk of infections, particularly during the first 3 months after transplantation. Longitudinal studies of immune monitoring reported peculiar patterns of T- and B-cell recovery in the peripheral blood of UCB recipients during the first months post-transplantation. Overall, current data suggest delayed reconstitution of naive and memory CD4⁺ and CD8⁺ T-cell pools after UCBT. This is particularly true for adult recipients and for patients who received in vivo T-cell depleting approaches before the transplantation. Such delayed T-cell recovery may increase susceptibility of UCB recipients for developing opportunistic infections and viral reactivations. Regarding B-cell recovery, UCBT was associated with accelerated B-lymphopoiesis. Recent studies also reported evidence for faster functional memory B-cell recovery in UCB recipients. In this article, we briefly review T- and B-cell reconstitution after alloHSCT, with emphasis on peculiarities observed after UCBT. We further put these data in lines with risks of infections after UCBT.

From patient centered risk factors to comprehensive prognostic models: a suggested framework for outcome prediction in umbilical cord blood transplantation

Prospectively identifying patients who will gain maximal benefit from umbilical cord blood transplantation (UCBT) with minimal risk is a desirable unmet need. A complex network of parameters related to patient, disease, donor, and procedure all come into play. We review the prognostic role of patient-related risk factors in adults undergoing UCBT. Furthermore, since comprehensive prognostic models are lacking in UCBT, we suggest a framework for integrating patients' features in the development of prediction models for UCBT outcomes. Such models could contribute to patient selection, optimization of the various modifiable features in the process of UCBT, analysis of retrospective data, and design of interventions.

Management of post-transplant lymphoproliferative disorders

PURPOSE OF REVIEW

Post-transplant lymphoproliferative disease (PTLD) is a major complication of hematopoietic stem cell and solid organ transplantation. The incidence of transplantation in childhood has been steadily rising, making PTLD the most common form of lymphoproliferation in childhood. The purpose of this review is to summarize the role of the Epstein-Barr virus (EBV) in the pathophysiology and discuss the management of PTLD.

RECENT FINDINGS

More than 90% of pediatric PTLD is EBV-positive. In immunocompetent hosts, the virus is controlled by cytotoxic T-cells, the cells targeted by immunosuppression to avoid graft-versus-host disease and/or organ rejection in transplant patients. The majority of pediatric transplant candidates are EBV-negative prior to transplant increasing the risk of EBV-induced lymphoproliferation upon seroconversion after transplant. Treatment options include reduction of immunosuppression, anti-CD20 monoclonal antibodies, and/or chemotherapy. Advanced understanding of the importance of cellular immunity in controlling lymphoproliferation has led to the development of cellular therapies targeting virus-specific antigens.

SUMMARY

PTLD is the most common form of lymphoproliferation in childhood due to the rising incidence of transplantation. EBV plays a pivotal role in the pathophysiology. Cellular therapies targeting viral antigens may replace chemotherapy in the treatment of PTLD in the near future.

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.

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.

Epstein-Barr virus lymphoproliferative disease after hematopoietic stem cell transplant

PURPOSE OF REVIEW

Epstein-Barr virus (EBV) reactivation can cause significant morbidity and mortality after allogeneic hematopoietic stem cell transplant. Delays in reconstitution of EBV-specific T lymphocyte activity can lead to life-threatening EBV lymphoproliferative disease (EBV-PTLD). This review highlights recent advances in the understanding of pathophysiology, risk factors, diagnosis, and management of EBV viremia and PTLD.

RECENT FINDINGS

During the past decade, early detection strategies, such as serial measurement of EBV-DNA load, have helped identify high-risk patients and diagnose early lymphoproliferation. The most significant advances have come in the form of innovative treatment options, including manipulation of the balance between outgrowing EBV-infected B cells and the EBV cytotoxic T lymphocyte response, and targeting infected B cells with monoclonal antibodies, chemotherapy, unmanipulated donor lymphocytes, and donor or more recently third-party EBV cytotoxic T lymphocytes. Defining criteria for preemptive therapy remains a challenge.

SUMMARY

EBV reactivation is a significant complication after stem cell transplant. Continued improvements in risk stratification and treatment options are required to improve the morbidity and mortality caused by EBV-associated diseases. Current approaches use rituximab to deplete B cells or adoptive transfer of EBV cytotoxic T lymphocyte to reconstitute immunity. The availability of rapid EBV-specific T cell products offers the possibility of improved outcomes.

Umbilical cord blood transplantation in adults with advanced hodgkin's disease: high incidence of post-transplant lymphoproliferative disease

We report the outcome of 30 consecutive patients with Hodgkin disease (HD) who underwent single-unit UCBT. Most (90%) patients had failed previous autologous hematopoietic stem cell transplantation. The conditioning regimens were based on combinations of thiotepa, busulfan, cyclophosphamide or fludarabine, and antithymocyte globulin. The cumulative incidence (CI) of myeloid engraftment was 90% [95% confidence interval (C.I.), 74-98%] with a median of 18 d (range, 10-48). CI of acute graft-versus-host disease (GvHD) grades II-IV was 30% (95% C.I., 17-44%), while the incidence of chronic GVHD was 42% (95% C.I., 23-77%). The non-relapse mortality (NRM) at 100 d and 4 yr was 30% (95% C.I., 13-46%) and 47% (95% C.I., 29-65%), respectively. EBV-related post-transplant lymphoproliferative disease (EBV-PTLD) accounted for more than one-third of transplant-related death, with an estimate incidence of 26% (95% C.I., 9-44). The incidence of relapse at 4 yr was 25% (95% C.I., 9-42%). Four-year event-free survival (EFS) and overall survival (OS) were 28% and 30%, respectively. Despite a high NRM and an unexpected high incidence of EBV-PTLD, UCBT in heavily pretreated HD patients is an option for patients lacking a suitable adult donor, provided the disease is not in refractory relapse.

Reduced-intensity conditioning umbilical cord blood transplantation in Nijmegen breakage syndrome

NBS is a rare autosomal recessive congenital disorder associated with chromosome instability caused by a mutation in the NBN gene (8q21). Clinical manifestations include microcephaly, growth retardation, combined immunodeficiency, and a strong predisposition to develop (mainly lymphatic) malignancies. There is no specific treatment for patients with NBS, and the prognosis is generally poor. The therapeutic option for some patients with NBS may be HSCT. We present a case of safe and successful non-myeloablative UCB transplantation in the 19th month of the life of a female child with NBS concomitant with SCID.

The role of the thymus in T-cell immune reconstitution after umbilical cord blood transplantation

Umbilical cord blood (UCB) is an alternative source of hematopoietic stem cells for patients without HLA-matched adult donors. UCB contains a low number of nucleated cells and mostly naive T cells, resulting in prolonged time to engraftment and lack of transferred T-cell memory. Although the first phase of T-cell reconstitution after UCB transplantation (UCBT) depends on peripheral expansion of transferred T cells, permanent T-cell reconstitution is mediated via a central mechanism, which depends on de novo production of naive T lymphocytes by the recipient's thymus from donor-derived lymphoid-myeloid progenitors (LMPs). Thymopoiesis can be assessed by quantification of recent thymic emigrants, T-cell receptor excision circle levels, and T-cell receptor repertoire diversity. These assays are valuable tools for monitoring posttransplantation thymic recovery, but more importantly they have shown the significant prognostic value of thymic reconstitution for clinical outcomes after UCBT, including opportunistic infections, disease relapse, and overall survival. Strategies to improve thymic entry and differentiation of LMPs and to accelerate recovery of the thymic stromal microenvironment may improve thymic lymphopoiesis. Here, we discuss the mechanisms and clinical implications of thymic recovery and new approaches to improve reconstitution of the T-cell repertoire after UCBT.

Improving engraftment and immune reconstitution in umbilical cord blood transplantation

Umbilical cord blood (UCB) is an important source of hematopoietic stem cells (HSC) for allogeneic transplantation when HLA-matched sibling and unrelated donors (MUD) are unavailable. Although the overall survival results for UCB transplantation are comparable to the results with MUD, UCB transplants are associated with slow engraftment, delayed immune reconstitution, and increased opportunistic infections. While this may be a consequence of the lower cell dose in UCB grafts, it also reflects the relative immaturity of cord blood. Furthermore, limited cell numbers and the non-availability of donor lymphocyte infusions currently prevent the use of post-transplant cellular immunotherapy to boost donor-derived immunity to treat infections, mixed chimerism, and disease relapse. To further develop UCB transplantation, many strategies to enhance engraftment and immune reconstitution are currently under investigation. This review summarizes our current understanding of engraftment and immune recovery following UCB transplantation and why this differs from allogeneic transplants using other sources of HSC. It also provides a comprehensive overview of promising techniques being used to improve myeloid and lymphoid recovery, including expansion, homing, and delivery of UCB HSC; combined use of UCB with third-party donors; isolation and expansion of natural killer cells, pathogen-specific T cells, and regulatory T cells; methods to protect and/or improve thymopoiesis. As many of these strategies are now in clinical trials, it is anticipated that UCB transplantation will continue to advance, further expanding our understanding of UCB biology and HSC transplantation.

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.

EBV-associated post-transplant lymphoproliferative disorder after umbilical cord blood transplantation in adults with hematological diseases

We analyzed the incidence, clinicopathological features, risk factors and prognosis of patients with EBV-associated post-transplant lymphoproliferative disorder (EBV-PTLD) in 288 adults undergoing umbilical cord blood transplantation (UCBT) at a single institution. Twelve patients developed proven EBV-PTLD at a median time of 73 days (range, 36-812). Three-year cumulative incidence (CI) of EBV-PTLD was 4.3% (95% CI: 1.9-6.7). All patients presented with extranodal involvement. Most frequently affected sites were the liver, spleen, central nervous system (CNS), Waldeyer's ring and BM in 7, 6, 4, 3 and 3 patients, respectively. One patient had polymorphic and 11 had monomorphic EBV-PTLD (7 diffuse large B-cell lymphomas not otherwise specified, 4 plasmablastic lymphomas). We confirmed donor origin and EBV infection in all histological samples. EBV-PTLD was the cause of death in 11 patients at a median time of 23 days (range, 1-84). The 3-year CI of EBV-PTLD was 12.9% (95% CI: 3.2-22.5) and 2.6% (95% CI: 0.5-4.7) for patients receiving reduced-intensity conditioning (RIC) and myeloablative conditioning, respectively (P<0.0001). In conclusion, adults with EBV-PTLD after UCBT showed frequent visceral and CNS involvement. The prognosis was poor despite routine viral monitoring and early intervention. An increased risk of EBV-PTLD was noted among recipients of RIC regimens.

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.