EBV PTLD Research Articles

Pediatric EBV-negative monomorphic post–solid organ transplant lymphoproliferative disorders [EBV(-)M-PTLD]: Characteristics, treatment, and outcome from 11 pediatric academic centers.

10012 Background: Pediatric EBV(-)M-PTLD comprises < 15% of M-PTLD. Two-year-overall survival of pediatric EBV(+) PTLD is 83%. No large multi-institution pediatric-specific reports are available for EBV(-)M-PTLD. Methods: Retrospective study of characteristics, treatment, and outcome of pediatric solid organ recipients diagnosed with EBV(-)M-PTLD at age ≤21 years (y) in 11 pediatric transplant centers in US and UK. Results: Thirty-three patients transplanted with solid organs between 1991-2017 developed EBV(-)M-PTLD. Twenty-two (66%) were male. Median age (range) at organ transplantation was 2.6y(0.1-17), diagnosis of EBV(-)M-PTLD 14y(3-20), interval from transplant to PTLD 8.3y (2.3-18). Transplanted organs were heart (n = 10), kidney (n = 17), liver (n = 4), small bowel (n = 1), liver and small bowel (n = 1). Immunosuppressive therapy at the time of diagnosis of PTLD was available on 31 patients. All were receiving a calcineurin inhibitor except one who was on sirolimus alone. Tacrolimus was given in 27 patients, alone (n = 3), or in various combination with mycophenolate (n = 8), azathioprine (n = 9), prednisone (n = 8), or everolimus (n = 1). Four of these receiving tacrolimus received 3 immunosuppressive drug combinations. Cyclosporine was given in 3 patients, with mycophenolate (n = 1), prednisone (n = 1), or both (n = 2). Murphy stages were I (n = 1), II (n = 7), III (n = 22), and IV (n = 3). Lactate dehydrogenase was elevated in 19/31 (61%) and > 2X upper limit of normal in 10/31 (32%) tested. Pathological diagnoses were diffuse large B-cell lymphoma (n = 30) and B-NHL NOS (n = 3). Treatment included: rituximab alone (n = 1), low-dose cyclophosphamide, prednisone, and rituximab (CPR; n = 9), pediatric mature B-NHL-specific regimen [FAB/LMB with (n = 12) or without (n = 1) rituximab], EPOCH-R (n = 2), R-CHOP (n = 3), modified R-CHOP (n = 2), COP (n = 1), and R-COP (n = 2). At a median 2.9y (0.3-11y) from diagnosis, 26/33 (79%) were alive and in complete remission (CR). Three experienced relapses at 1, 3, and 6.5y after CPR, rituximab alone, and B-NHL therapy, respectively. All achieved a sustained second CR with additional B-NHL therapy. Of the 7 deaths: 6 were from progressive disease despite escalation to intensive B-NHL therapy following initial COP (n = 1), R-COP (n = 1), CPR (n = 2), and B-NHL therapy (n = 2), and one cardiac transplant recipient from presumed cardiotoxicity. There was one graft rejection that was successfully treated. Conclusions: This collaboration represents the first multi-institution series of pediatric EBV(-)M-PTLD. Overall survival was comparable to that reported for pediatric EBV(+) PTLD, but inferior to DLBCL in immunocompetent children. These preliminary data reflect a wide range of therapeutic regimens used over 20 years and strongly support an organized collaborative effort to collect data prospectively.

Donor-derived T cells specific for tumor antigen and multiple pathogens for prevention of relapse and infection after haemopoietic stem cell transplant (HSCT) for myeloid malignancies (the INTACT trial).

7039 Background: Disease relapse and infection cause significant morbidity and mortality after allogeneic HSCT for acute myeloid leukemia (AML) and myelodysplasia (MDS). Wilms’ tumour 1 (WT1) and preferentially expressed antigen in melanoma (PRAME) are both commonly overexpressed in these conditions. We assessed the safety of a novel combination of tumour associated antigen (TAA) and multipathogen (MP) specific T cells administered prophylactically after HSCT in a phase 1 trial. Methods: Patients with overexpression of WT1 or PRAME by ddPCR on diagnostic tumour samples were eligible. TAA and MP specific T cells were ex vivo expanded from stem cell donors by stimulating apheresis derived mononuclear cells with tumour, viral or fungal peptides. T cells specific for CMV, EBV, Adenovirus (AdV) and Aspergillus (Asp) antigens were produced separately and pooled in equal parts into a MP product. Patients received 1 infusion of MP specific and up to 4 infusions of TAA specific T cells at 4-weekly intervals from 28 days post HSCT (cell dose 2x107/m2 per infusion). Results: Ten HSCT recipients have received a total of 38 infusions. Median age was 48 years (17-67), disease AML (n = 6) or high risk MDS (n = 4), DRI intermediate (n = 4) or high (n = 6), conditioning myeloablative (n = 8) or reduced intensity (n = 2), donor source sibling (n = 7) or matched unrelated (n = 3). Median expression of WT1 on diagnostic bone marrow was 1442 copies/104 copies ABL (0-3870), PRAME 131 copies/104 copies ABL (4-12300). Patients received WT1 (n = 4), PRAME (n = 5) or both WT1 and PRAME specific T cells (n = 1). Mean tumour antigen specificity in the TAA product was 1.4% and 13.3% of CD3+ cells for WT1 and PRAME respectively. Mean total pathogen specificity in the MP product was approximately 44% (CMV = 14.0%, EBV = 14.8% and AdV = 11.6% of CD3+ cells, Asp = 14.8% of CD4+ cells). All patients received MP specific T cells. No immediate infusion related adverse events were reported. At a median 540 days post transplant (80-1265), 8 of 10 patients remain alive and in complete disease remission. Two patients did not proceed after completing 3 of 5 infusions due to the development of graft versus host disease (GVHD); both are in remission. There were 2 deaths; one patient with progressive disease who had persistent high risk MDS pre and post HSCT, and one with multiorgan failure who had multiple post transplant complications (venoocclusive disease, sepsis, GVHD), both prior to infusion. Low level viral reactivations occurred (CMV n = 5, EBV n = 7, BKV n = 3, HHV6 n = 4, AdV n = 1), however none required treatment and there were no cases of viral tissue disease or EBV PTLD. There were no invasive fungal infections. Conclusions: Prophylactic infusions of donor derived WT1/PRAME and multipathogen specific T cells post HSCT are well tolerated and associated with low rates of infection and relapse. Clinical trial information: NCT02895412.

Epstein-Barr virus posttransplant lymphoproliferative disorder: update on management and outcomes.

Management of Epstein-Barr virus posttransplant lymphoproliferative disorder (EBV PTLD) is complex, involving risk stratification, prevention and/or preemptive measures involving monitoring EBV DNAemia and balancing treatment options, using a combination of reduction of immune suppression, anti-B cell therapy, and cytotoxic T lymphocytes (CTLs). The highest risk factor for the development of EBV PTLD in hematopoietic cell transplant (HCT) remains T cell depletion, with increasing use of antithymocyte globulin (ATG) or alemtuzumab in conditioning. In solid organ transplantation (SOT), the incidence of PTLD is highest among EBV seronegative recipients who are at risk for primary EBV infection following transplant in the first 12 months. Prevention is a critical component of the management of EBV PTLD. Although preemptive therapy remains standard of care, there continues to be heterogenicity and debate over the optimal choice of EBV DNA quantification and the threshold to use. Novel therapies such as donor-derived multipathogen and EBV specific CTLs for the prevention and third party CTLs for the treatment of EBV PTLD are promising, with rapidly expanding evidence, including large scale Phase III trials currently underway. With an increasing number of risk groups for developing EBV PTLD in HCT and SOT, management strategies using prophylaxis or preemptive therapy remain standard of care, however the use of prophylactic or preemptive EBV specific or multipathogen CTLs show promising results and safety profiles.

Epstein-Barr virus-specific cytotoxic T lymphocyte precursors (EBV-CTLp) after tabelecleucel correlates with response & survival in rituximab relapsing or refractory EBV posttransplant lymphoproliferative disease (PTLD)

Background & Aim Background EBV PTLD is often a fatal disease. Tabelecleucel is an investigational off-theshelf, allogeneic T-cell immunotherapy specific for EBV antigens. Functional in vivo expansion approximated by a limiting dilution analysis of EBV-CTLp has previously been correlated to clinical response. Methods, Results & Conclusion Methods We conducted analyses of reported peak circulating EBV-CTLp levels following tabelecleucel administration in correlation to response and safety across two studies (N = 42) in rituximab refractory or relapsing EBV PTLD following HCT or SOT. Results Two cohorts were defined by the lowest EBV-CTLp quartile (n = 11) and the combined upper 3 quartiles (n = 31). Twenty-five of 31 subjects (80.6%) in upper quartiles exhibited a clinical response compared to 3 of 11 subjects (27.3%) in the lowest quartile. Eighteen of 20 complete responses and 7 of 8 partial responses demonstrated peak CTLp values in the upper quartiles of the population. Overall survival (OS) rate in subjects exhibiting CTLp values in the upper quartiles was 83.9% (95% CI: 65.5-92.9%) at 1 year and 66.1% (95% CI: 45.9-80.2%) at 2 years, compared to 18.2% (95% CI: 2.9-44.2%) in the lowest quartile over the same periods. OS is commensurate with a hazard ratio of 0.168 in favor of subjects with higher EBV-CTLp (95% CI: 0.067-0.425; Log-Rank Test p-value Conclusions These analyses illustrate the correlation of peak EBV-CTLp to clinical benefit in subjects receiving tabelecleucell. Significant correlation of EBV-CTLp with ORR and OS are consistent with potential use as a functional biomarker for the expansion of EBV specific T-cells in the treatment of EBV PTLD in the rituximab refractory/relapsing setting.

Epstein-Barr virus related post-transplant lymphoproliferative disorder prevention strategies in allogeneic hematopoietic stem cell transplantation.

Epstein-Barr virus associated post-transplant lymphoproliferative disorders (EBV PTLD) are recognized as a significant cause of morbidity and mortality in patients undergoing allogeneic hematopoietic stem cell transplantation (alloHSCT). The number of patients at risk of developing EBV PTLD is increasing, partly as a result of highly immunosuppressive regimens, including the use of anti-thymocyte globulin (ATG). Importantly, there is heterogeneity in PTLD management strategies between alloHSCT centers worldwide. This review summarizes the different EBV PTLD prevention strategies being utilized including the alloHSCT and T-cell depletion regimes and the risk they confer; monitoring programs, including the timing and analytes used for EBV virus detection, as well as pre-emptive thresholds and therapy with rituximab. In the absence of an institution-specific policy, it is suggested that the optimal pre-emptive strategy in HSCT recipients with T-cell depleting treatments, acute graft vs host disease (GVHD) and a mismatched donor for PTLD prevention is (a) monitoring of EBV DNA post-transplant weekly using plasma or WB as analyte and (b) pre-emptively reducing immune suppression (if possible) at an EBV DNA threshold of >1000 copies/mL (plasma or WB), and treating with rituximab at a threshold of >1000 copies/mL (plasma) or >5000 copies/mL (WB). There is emerging evidence for prophylactic rituximab as a feasible and safe strategy for PTLD, particularly if pre-emptive monitoring is problematic. Future management strategies such as prophylactic EBV specific CTLs have shown promising results and as this procedure becomes less expensive and more accessible, it may become the strategy of choice for EBV PTLD prevention.

Abatacept Is Effective for Gvhd Prophylaxis after Unrelated Donor Stem Cell Transplantation (URD SCT) for Severe Sickle Cell Disease (SCD)

Background In 2016, results from the first URD SCT for SCD (the SCURT Trial) revealed a 2-year overall survival (OS) and event-free survival (EFS) of 79% (95% CI 59-90) and 69% (95% CI, 48-82) respectively following reduced intensity conditioning (RIC).1 Though the RIC approach provided successful engraftment in the majority, the transplant approach was not considered safe for widespread adoption due to high rates of graft-versus-host disease (GVHD) especially in children >13 years, a predominant cause of mortality. Strategies to minimize GVHD were essential if URD SCT was to be considered with curative intent in SCD. Aim/Method Multicenter trial (NCT03128996) with the primary objective of determining EFS in non-malignant disorders at one-year was amended as follows. The phase I SCD cohort included conditioning with hydroxyurea, proximal alemtuzumab, fludarabine, and melphalan in patients with 8/8 HLA-matched URD (-A, -B, - C and -DRB1).1 Thiotepa (8 mg/kg) was added in 7/8 HLA-mismatched SCT. GVHD prophylaxis included a calcineurin inhibitor and methotrexate as previously described. Abatacept (10 mg/kg) was administered on days -1, +5, +14, +28, +60, +100, +180, +270 and +365 based on efficacy described against acute GVHD with early dosing after SCT for malignant disorders.2,3 The latter 3 doses were omitted in cord transplant recipients. Result Thirteen children (7-21 years) underwent SCT (8/8 URD marrow- 7; 7/8 URD marrow or cord-6) primarily for stroke (N=6), ≥3 severe vaso-occlusive pain crises (N=4) or ≥2 acute chest syndrome episodes per year (N=3). The conditioning regimen was well tolerated. One patient had primary graft rejection after CMV infection (7%) and had autologous recovery. All other patients engrafted; neutrophils at median of 18 days (10-24), platelets at median of 28 days (16-39) and are surviving free of SCD with median follow-up of 12 months (range 4-59). Myeloid lineage donor chimerism was >95% and lymphoid was 39%- 100% at day+100. Two-year OS and EFS was 100% and 92.3% (95% CI, 6.57-35.7), respectively. The day+100 incidence of grade II-IV and III-IV acute GVHD incidence was 23% and 15% respectively. One-year incidence of chronic GVHD was 38%. However, only one patient (7%) developed extensive cGVHD. One patient (7%) developed posterior reversible encephalopathy syndrome and recovered. Viral replication in blood was detected in 7 of 13 patients (7 CMV, 1 EBV reactivation). No patient developed EBV PTLD or required EBV-related intervention. Conclusion In comparison to previous experience1 with RIC and URD SCT, our early observations are (1) a lower incidence of PRES (7 vs 34%) (2) low incidence of severe acute GVHD (15% vs 17% grade III -IV) despite mismatched donors, (3) low incidence of extensive chronic GVHD (7% vs 38%) and (4) no mortality despite patient age (10/13 were >13 years old). We attribute this gain to avoiding steroid use, and the benefit of including abatacept into the treatment regimen. The engraftment, safety, and immune reconstitution profile continue to be monitored in this ongoing trial now accruing in a Phase II cohort. As we and others work toward expanding donor options for SCD transplants, we submit that all alternate donor transplants for severe SCD are experimental and should be performed on clinical trials that track success and pitfalls. Reference: 1. Shenoy S et al. A trial of unrelated donor marrow transplantation for children with severe sickle cell disease. Blood. 2016 Nov 24; 128(21): 2561-2567. 2. Koura et al. In vivo T cell costimulation blockade with abataceptfor acute graft-versus-host disease prevention: a first-in-disease trial. Biol Blood Marrow Transplant. 2013 Nov; 19(11): 1638-49. 3. Watkins BK et al. T cell co-stimulation blockade with CTLA-4 Ig (Abatacept) for acute GVHD prevention in HLA-matched and mismatched unrelated donor transplantation: Results of a Phase 2 trial. Abstract 65. ASTCT Meetings, Houston 2019. Figure Disclosures Shah: Jazz pharmaceuticals: Speakers Bureau. OffLabel Disclosure: Abatacept, FDA approved for rheumatoid arthritis is a fusion protein that inhibits T-cell activation by binding to CD80/CD86 on antigen-presenting cells (APCs).It is used for acute graft-versus-host disease (aGVHD) prevention during unrelated-donor hematopoietic cell transplantation in this study

S1625 REDUCTION OF GRAFT‐VERSUS‐HOST DISEASE USING DUAL LYMPHOCYTE SUPPRESSION WITH ANTI‐THYMOCYTE GLOBULIN AND LOW‐DOSE POST‐TRANSPLANT CYCLOPHOSPHAMIDE IN HAPLOIDENTICAL PATIENTS AT HIGH GVHD RISK

Background:In the setting of haplo HCT, further reducing GVHD merits examination, especially after HCT from maternal donor or collateral relatives with high risk of GVHD occurrence. With the aim to reduce the risk of GVHD without increasing the incidence of relapse, the combined use of antithymocyteglobulin (ATG) and post‐transplant cyclophosphamide (PTCy) has become feasible. However, the combination regimen has not been validated.Aims:There have been only two studies on the combination of ATG and high‐dose PTCy for hematological malignancy without control cohort or with short follow‐up. Our previous single‐center preliminary report on 40 patients seems to support the feasibility of the combined use of ATG/granulocyte colony‐stimulating factor (G‐CSF) and low‐dose PTCy (14.5 mg/kg on days 3 and 4 after HCT). Thus, these results need to be confirmed on a larger number of patients with hematological malignancies.Methods:In an attempt to assess the efficacy of this strategy in Haplo, we conducted a multicenter analysis in patients transplanted from maternal donor or collateral relatives and treated with ATG‐PTCy (low‐dose) regimen, and compared the results to contemporary cohort of patients with same characteristics who received ATG without low‐dose PTCy (ATG cohort). We identified 162 consecutive patients (ATG‐PTCy cohort = 73; ATG cohort = 89) between 2016 and July 2018.Results:All patients but one in ATG cohort achieved myeloid engraftment by day 30 post‐HCT. We found that both the cumulative incidence of 100‐d severe acute GVHD and 2‐y total chronic GVHD in ATG‐PTCy cohort was significantly lower than that in ATG cohort (5% vs 20%; P = 0.007; and 26% vs 49%; P = 0.001). And severe GVHD was the most common cause of death (33%) in the ATG cohort as compared to none in the ATG‐PTCy cohort. Furthermore, TRM was significantly lower in ATG‐PTCy cohort (4% vs 14%; P = 0.039).In contrast, myeloid recovery was significantly slower (median, 15d vs 12d; p < 0.0001) and 100‐d platelet recovery was significantly lower in the ATG‐PTCy group (87% vs 98%; P = 0.0002). The 100d cumulative incidence of CMV reactivation in ATG‐PTCy cohort was significantly higher than that in ATG cohort (73% vs 33%; P < 0.001). The 100‐d cumulative incidence of EBV reactivation and PTLD was comparable (25% vs 17%; P = 0.21; and 4% vs 2%; P = 0.49).In multivariate analysis, the combined treatment resulted in lower severe acute GVHD (Hazard Ratio 0.18; P = 0.004), chronic GVHD (HR 0.39; P = 0.010), and TRM (HR 0.24; P = 0.023) but slower myeloid and platelet recovery (HR 0.27 and 0.30; both P < 0.001). No significant differences were found in relapse rate and disease‐free survival according to treatment group. A propensity score technique was used to confirm results of main analysis.Summary/Conclusion:Unmanipulated haploidentical transplantation with ATG/G‐CSF and low‐dose PTCy as a GVHD prevention strategy results in lower rates of both acute and chronic GVHD without influencing the GVL effect for patients transplanted from maternal donor or collateral relatives with high risk of GVHD occurrence.image

Adoptive Therapy with EBV-Specific T Cells for Treatment of CNS EBV Post-Transplant Lymphoproliferative Disease Arising after Hematopoietic Stem Cell Transplant or Solid Organ Transplant

Adoptive immunotherapy with EBV-specific T-cells (EBV-CTLs) derived from primary hematopoietic transplant donors is effective in the treatment of EBV disease complicating allogeneic hematopoietic stem cell transplant (HCT). In addition, third party donor-derived EBV-CTLs (tabelecleucel) have demonstrated efficacy in the treatment of EBV post-transplant lymphoproliferative in the setting of both HCT and solid organ transplant (SOT). While the introduction of first line therapy with rituximab has reduced the mortality associated with EBV-PTLD, EBV PTLD involving the central nervous system (CNS) remains a particularly ominous event as the efficacy of rituximab for CNS disease is limited by poor CNS bioavailability.Between 1996 and 2016 we treated nineteen patients for EBV-PTLD involving the CNS arising after HCT (12) or SOT (7). These patients received EBV-CTLs from their primary transplant donor (7), tabelecleucel from a third-party donor (11) or from both types of donor (1). Patients were treated for either isolated CNS disease (10) or CNS and systemic disease (9). Patients developing EBV-PTLD after HCT were recipients of T Cell Depleted (N=6), cord blood (N=3) and conventional (N=3) transplant. Those developing EBV-PTLD after SOT had undergone renal (N=4) heart (1) liver (1) and heart/liver (1) transplants.All of these patients had received prior therapy including rituximab (N=17), radiation therapy (N=6), and chemotherapy (N=9).Primary donor EBV-CTLs were generated from EBV seropositive hematopoietic transplant donors at the time of or after the patient underwent transplant. Third party tabelecleucel were selected from a bank of 330 lines generated under GMP conditions from normal HCT donors who specifically consented to use of their T cells in patients other than their designated transplant recipient. Selection of third party tabelecleucel lines was made on the basis of HLA restriction by at least one HLA allele shared by the patient's tumor and the HCT donor, and matching for ≥ 2/10 recipient alleles. Patients received 3 weekly infusions of approximately 1-2x106 T cells/kg/infusion. Patients were sequentially evaluated for clinical and radiographic response, and quantifications of EBV DNA by PCR. Patients not achieving a complete response to an initial cycle of EBV directed cellular therapy were eligible to receive subsequent cycles of cells from either the same or a different donor. Responses were assessed 21-35 days after the first of each cycle of EBV-CTLs. Responses were evaluated based on Lugano criteria with CNS disease being assessed by MRI, CSF or thalium scan. Two patients treated for CNS and systemic disease had simultaneous therapy of their CNS disease and achieved responses of both CNS and systemic disease but the CNS specific response could not be attributed to cell therapy alone.Of the 19 patients, 7 achieved complete responses and 5 durable partial responses for an overall response rate of 63%. The one-year overall survival (OS) for this cohort of 19 patients was 60% with responding patients experiencing one year OS of 91.7% and non-responding patients one year OS of just 14.3%. Eight of the 10 patients treated for isolated CNS disease responded to adoptive EBV directed T cell therapy. One-year overall survival for patients treated for isolated CNS disease is 70% and with CNS and systemic disease is 55.6%. Toxicities associated with infusions in this cohort are limited with 8 patients experiencing adverse events of ≥ grade 3 severity with one patient experiencing a possibly related grade 3 eventThis study demonstrates a high response rate among patients with otherwise refractory EBV PTLD affecting the CNS. Adoptive therapy with EBV directed cellular therapy (primary donor or third party derived) can effectively treat this otherwise frequently lethal complication. The availability of 3rd party tabelecleucel enables treatment early in the course of disease and may thereby improve response rates while minimizing toxicity from chemotherapy.Atara Biotherapeutics holds the IND and has a license to develop and commercialize the EBV and CMV cell therapy programs at Memorial Sloan Kettering. MSKCC and several MSK investigators hold a financial interest in Atara Biotherapeutics. DisclosuresProckop:Atara Biotherapeutics: Research Funding; Mesoblast: Research Funding. Doubrovina:Atara Biotherapeutics: Consultancy, Patents & Royalties, Research Funding. Sauter:Juno Therapeutics: Consultancy, Research Funding; Sanofi-Genzyme: Consultancy, Research Funding; Spectrum Pharmaceuticals: Consultancy; Novartis: Consultancy; Precision Biosciences: Consultancy; Kite: Consultancy. O'Reilly:Atara Biotherapeutics: Consultancy, Patents & Royalties, Research Funding.

Measuring EBV in Lung Transplant Patients - Lessons of 16 Years of Follow Up

Currently there is debate regarding the use and usefulness of EBV viral loads in lung transplant patients. We routinely measure EBV DNA load since 2001 and studied the relation between EBV DNA load, CLAD, survival and PTLD .

Epidemiology and outcome of chronic high Epstein-Barr viral load carriage in pediatric kidney transplant recipients.

The development of EBV infection and PTLD is normally associated with a high EBV viral load in peripheral blood. Observations have previously identified existence of a CHL carrier state that demonstrated variable outcomes based upon the organ which was transplanted. Data defining the incidence and outcome of CHL in pediatric KTx are not well described. The charts of children undergoing isolated KTx at Children's Hospital of Pittsburgh between January 2000 and December 2014 were retrospectively reviewed. EBV loads in the peripheral blood were routinely measured as part of surveillance protocols at our center. CHL was defined as the presence of high load for >50% of samples for ≥6months. PTLD was defined histologically using WHO definitions. Of 188 isolated KTx recipients, we identified a total of 16 (8%) children who developed CHL carrier state. No patient developed EBV-driven late-onset PTLD. Age at the time of KTx was significantly lower in the CHL group (median 3.9years, interquartile range: IQR 2.9-6.6, P=.0004). Children in the CHL group were more likely to be EBV-seronegative prior to KTx (94%, 15/16), compared to the UVL and LVL groups (55% and 50%, respectively, P<.002). The median duration of CHL carrier state was 20months (IQR 10.7-35.8). Fifteen of the 16 CHL carriers experienced spontaneous resolution of CHL carrier state. Children in the CHL group were younger at the time of primary EBV infection (P=.023). Finally, antiviral medication was not effective in either preventing or decreasing the EBV viral load in blood (P=.84). Overall incidence of late-onset PTLD is very low compared to heart and intestinal transplant, even though KTx recipients can develop CHL carrier state. The CHL carriers in KTx recipients were EBV-seronegative prior to transplant and were younger both at the time of KTx and at the time of primary EBV infection compared to those in the UVL and HVL groups. Antivirals did not prevent EBV infection or decrease EBV viral loads.

Administration of Most Closely HLA-Matched Multivirus-Specific T Cells for the Treatment of EBV, CMV, AdV, HHV6, and BKV Post Allogeneic Hematopoietic Stem Cell Transplant

Viral infections remain a significant cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). Adoptive immunotherapy with donor-derived virus-specific T cells (VSTs) has proven safe and effective for the prophylaxis and treatment of EBV, CMV, AdV, BKV and HHV-6 infections post-HSCT. However, broader application is restricted by the time taken to prepare patient-specific products and the lack of virus-specific T cell precursors in cord blood and seronegative donors. Thus, to assess whether 3rd party multivirus-directed VSTs could produce clinical benefit when administered as an "off the shelf" product to partially HLA-matched allogeneic HSCT recipients with drug-refractory BKV, EBV, CMV, AdV and/or HHV-6 infections we initiated a Phase II clinical trial (fixed cell dose of 2x107 VSTs/m2) using a bank of 59 VST lines generated from healthy, eligible donors.To date, 32 patients with one (n=28) or two (n=4) drug-refractory infections have been infused with lines matched at 1 to 6 HLA antigens. Fifteen patients received VSTs to treat CMV (including 3 cases of CMV colitis), 13 for BKV (11 for hemorrhagic cystitis, 2 for nephritis), 4 for AdV (including 1 case of pneumonia), 2 for HHV-6 (including 1 case of encephalitis) and 2 for EBV (including 1 case of EBV-PTLD). Twenty-one patients received just 1 infusion of cells, while 11 required 2 or 3 infusions for sustained benefit. Despite the HLA disparity between the VST lines and the recipients, de novo graft versus host disease (GVHD) occurred in only 1 subject, who developed Grade I skin GVHD that resolved with topical steroids. One additional patient had a flare of chronic skin GVHD coincident with tapering of immunosuppression and 2 patients developed transient fevers a few hours post-infusion, which spontaneously resolved within a couple of hours.Based on viral load, as measured by quantitative PCR, 3rd party VSTs successfully controlled active infections in 29 of 31 evaluable patients: CMV (9 CR, 5 PR, 1 NR); EBV (2 CR); AdV (2 CR, 1 PR, 1 NR); BKV (4 CR, 9 PR); and HHV-6 (1 PR). Of note, all 11 patients with BK hemorrhagic cystitis, 2 of 3 patients with CMV colitis, and the patients with AdV pneumonia and HHV-6 encephalitis, all had marked improvement or resolution of symptoms within 6 weeks following VST treatment. In more than 50% of responders (n=16) we detected an increase in the circulating frequency of VSTs post-infusion, which were confirmed to be 3rd party VST origin in 8 and remained detectable for up to 12 weeks post-infusion. The eventual decrease in 3rd party VSTs coincided with endogenous immune reconstitution in most patients.These results confirm the feasibility and safety of 3rd party multivirus-directed VSTs, administered as an "off the shelf" product to treat drug-refractory infections/disease. The infused cells were capable of expanding in vivo and proved clinically effective against refractory EBV, CMV, AdV, BKV and HHV-6 reactivation and virus associated disease. DisclosuresTzannou:ViraCyte LLC: Consultancy. Brenner:Viracyte: Equity Ownership; Cell Medica: Patents & Royalties. Rooney:Cell Medica: Membership on an entity’s Board of Directors or advisory committees, Patents & Royalties; Viracyte: Equity Ownership. Heslop:Cell Medica: Patents & Royalties: Licensing agreement EBV-specific T cells; Viracyte: Equity Ownership; Chimerix: Other: Endpoint adjudication committee; Celgene: Patents & Royalties, Research Funding. Leen:ViraCyte LLC: Equity Ownership, Patents & Royalties.

Kidney transplant recipients after nonrenal solid organ transplantation show low alloreactivity but an increased risk of infection.

The number of kidney transplant recipients (KTRs) after nonrenal solid organ transplantation (SOT) has increased to almost 5%. Knowledge on patient and allograft outcomes, infections, and alloreactivity, however, remains scarce. We studied 40 KTRs after nonrenal SOT. Seven hundred and twenty primary KTRs and 119 repeat KTRs were used for comparison. Samples were collected pretransplantation, at +1, +2, and +3months post-transplantation. Alloreactive and CMV-specific T cells were measured by interferon-γ ELISPOT assay. Patient survival in KTRs after SOT, primary and repeat KTRs was comparable. While death-censored allograft survival was comparable between KTRs after SOT and primary KTRs, KTRs after SOT showed superior 5-year death-censored allograft survival of 92.5% compared to 81.2% in repeat KTRs. Interestingly, KTRs after SOT show less preformed panel-reactive antibodies, frequencies of alloreactive T cells, and acute rejections compared to repeat KTRs. KTRs after SOT, however, show higher incidences of EBV viremia and PTLD, sepsis, and death from sepsis. Impaired CMV-specific cellular immunity was associated with more CMV replication compared to repeat KTRs. Our results suggest comparable patient and allograft outcomes in KTRs after SOT and primary KTRs. The observed low alloreactivity may contribute to excellent allograft outcomes. Caution should be taken in KTRs after SOT regarding infectious complications due to overimmunosuppression.

Excellent Outcome in All Patients With Combined Kidney and Liver Transplant for Primary Hyperoxaluria Type 1.

Introduction: We have previously reported 100% patient and graft survival in infants receiving combined kidney/liver (K/L) transplants (Txp) for primary hyperoxaluria type 1 (PH1). In this report we compared outcome between infants (Inf) and other children and adults, all others (AO), with K/L Txp for PH1. Methods: Institutional review board approval was obtained. We compared outcome between Inf (n=6), defined as age less than 24 months (mo), and AO (n=5) patients (Pts) receiving K/L Txp from 6/1995 - 6/2007. Data included age at Txp, cold storage time (time to perfusion of the portal vein of the liver graft) in minutes (min), delayed graft function (DGF) in the kidney, serum creatinine (Cr) in mg/dl at postoperative day (POD) 30 and at 1 year (yr), the number of pts with any rejection in either the liver or kidney, pts with hypertension (Htn), pts with any renal stone after Txp, and the 5 yr actuarial pt and kidney graft survival. Categorical differences were compared using the unpaired Student's t-test and nominal variables using the Fischer's exact test. Results: Demographic and outcome data is shown in the table.Table: No Caption available.The mean follow-up was 8.8 yrs in the Inf and 5.4 yrs in the AO groups respectively. Two blood type A pts received type O grafts. One of these pts had a positive crossmatch. All AO and one Inf received a whole liver graft. Two Pts had a living donor KTxp, one before and the other after LTxp. One pt had a living donor LTxp after hepatic artery thrombosis (HAT) in the cadaveric LTxp. One other pt required a second LTxp after HAT. The one pt with post Txp stones developed a stone at 2, 4, and 32 months after KTxp. Two Inf and 2 AO pts developed C. difficile infections. One Inf pt developed EBV infection and PTLD. At 5 years after Txp all patients' albumin and liver function tests are normal. Conclusion: Excellent outcome can be achieved in all patients regardless of age receiving combined K/LTxp for PH1.

Long Term Follow-Up in Small Bowel Transplant Recipients: Ebv Infections and Post Transplant Lymphopfoliferative Disease Surveillance

Background: Control of complications is still one of the most important clinical challenge in small bowel transplantation. Early diagnosis and fast treatment can avoid negative outcomes, so obviously reliable monitoring protocols are capital: the aim of this study was to evaluate endoscopic and histological diagnostic value on a long term follow-up in case of EBV infection and PTLD occurrence. Patients and methods: We evaluated endoscopies performed during last six years on 18 recipients submitted to small bowel transplant between the year 2000 and 2006: follow-up endoscopies and biopsies after 5 years from transplant were routinely scheduled once every 6 months, otherwise more often in case of clinical indications. At transplant, recipients underwent preemptive antiviral therapy and subsequently serial monitoring of Epstein-Barr-Viral load was performed. In case of intestinal EBV infection with negative blood viral load the patients were treated only with low immunosuppression regimen. Patients with EBV infection found both on intestinal specimen and on blood samples, were treated reducing immunosuppression regimen and with i.v. Gancyclovir administration (5mg/Kg 2 times/day) for 2 weeks; patients with PTLD diagnosis were treated with low immunosuppression regimen and with Rituximab administration (375 mg/m2, once/week for 4 weeks). Results: In our series we were able to diagnose EBV infections (both in blood and intestinal mucosa), and consequently to make an early diagnose of PTLD when occurring thanks to close follow-up: endoscopy with biopsies and EBV monitoring on specimen and blood every month, PET scan every 6 month in case of positive blood EBV infection. During the considered follow-up period, with at least 5 years from transplant, we diagnosed 12 cases of EBV intestinal infections, 5 of them with positive blood viral load. Among these five cases, even if they were all treated with Gancyclovir administration, 3 patients developed PTLD occurrence and they were all treated with four weeks Rituximab schedule: we registered negative outcome in one case (the patient died due to post-operative complications after intestinal resection of obstructive intestinal PTLD); other two patients appear now free from disease, with complete PET healing on latest follow-up, even if one of them still has EBV positive intestinal biopsies and blood samples and he is under antiviral therapy up to now. Conclusion: EBV infection is one of the most common complication after intestinal transplantation, with an incidence of 67% in our series. After a median follow-up of 36 months (12-60 months) the overall survival is 88,8 %. Therefore, concerning EBV infections and PTLD surveillance during long term follow-up, endoscopy and histological analysis are good tools to provide faster diagnostic orientation, to plan appropriate treatment earlier, and to achieve positive outcomes.

Adoptive Immune Cell Therapy Using Third Party T-Cell Donors In the Treatment of EBV Related Diseases In Immunodeficient Recipients

AbstractAbstract 487Adoptive transfer of donor-derived EBV-specific T-cells can induce complete and durable regressions of EBV lymphomas complicating allogeneic hematopoietic progenitor cell transplants (HSCT). However, this treatment has not been broadly applicable due to 1) lack of immediate access to such T-cells and 2) lack of adequate donor cells to generate the virus-specific T-cells required, either because of donor unavailability (e.g. cord blood or some unrelated donors) or seronegativity. To address this we have developed a bank of EBV-specific cells of defined HLA restriction, and are now evaluating the potential of these HLA-partially matched, third party EBV-specific T-cells. We here report results for the first 13 patients treated by this approach, including pts who developed clonal EBV lymphomas following HLA matched (n=2) or disparate (n=1) T-cell depleted HSCT (N=3) or HLA-disparate cord blood transplants (N=3); pts with chemotherapy refractory EBV PTLD (n=2) or EBV+ leiomyosarcomas (LS) (n=3) complicating organ transplants (N=5) and pts with EBV+ CNS lymphomas complicating AIDS or prolonged immunosuppression (N=2). These patients received infusions of third party EBV-CTLs after the failure of a median of 2 prior therapies (0 – 4) including rituximab in all but one case. Three patients had also failed prior infusions with autologous (1) or HSCT donor (2) EBV-CTLs. T-cells from consenting EBV seropositive HLA typed normal donors were sensitized in vitro for at least 28 days with irradiated autologous EBV BLCL transformed with the EBV strain B95.8, and were then tested for sterility virus-specificity and lack of alloreactivity and stored cryopreserved prior to use. The donors were selected based on matching for at least 2 HLA alleles and in most instances, known restriction of the EBV-specific T-cells for epitopes presented by HLA alleles shared by the EBV+ malignancy. Up to 4 courses of T-cells were administered in 3 weekly I.V. infusions of 1 × 106 T cells/kg, each course separated by a 3 week observation period. T cell infusions were well tolerated. One patient developed minor skin GvHD. No other patient developed GVHD or organ allograft rejection. Results for the 13 pts are summarized in Table 1.Those pts achieving CR, PR or SD had rapid increments in the frequencies of EBV CTLP detected that persisted 14–21 days after each course. Of the 4 pts with PD, none exhibited increases in the frequency of EBV CTLPs in the blood post T-cell infusion. No increase in EBV CTLPs was observed in a patient who progressed after treatment with EBV-specific T-cells from his haplotype disparate HSCT donor. In this case, the donor's EBV-specific T-cells were restricted by an HLA allele not shared by the host-type lymphoma. This patient was then treated with EBV-specific T-cells from a third party donor restricted by an HLA allele shared by the host-type lymphoma. These T-cells expanded post infusion, resulting in a durable CR. Overall, 9 of 13 survive either in CR or sustained PR or SD >6 to > 60 months post treatment. These results provide evidence that third party EBV-specific T-cells, that are partially HLA-matched, and appropriately HLA restricted can induce regressions of EBV-associated lymphomas, PTLD and LS complicating transplantation or prolonged immunodeficiency. A bank of such T-cells can provide an immediately accessible source of T-cells for adoptive therapy for a large proportion of patients developing these life threatening disorders.NCRPRSDPDSurvivalEBV+ Lymphoma Post HSCT or CBT640024 in CREBV+ PTLD Post Organ Transplant201011 in PREBV+ CNS Lymphoma in Immunodeficiency210011 in CREBV+ Leiomyosarcoma Post Transplant301203 in PR or SD1353249 Disclosures:No relevant conflicts of interest to declare.

Chronic high Epstein-Barr viral load carriage in pediatric small bowel transplant recipients

The development of EBV infection and PTLD is normally associated with a high EBV load in peripheral blood. Often, children undergoing primary or reactivation of EBV infection subsequent to ITx will have chronically elevated EBV loads. To better understand this phenomenon and its consequences, we retrospectively reviewed the records of children who underwent ITx (either isolated or part of multivisceral transplantation) at our center from 1992 to 2007, to identify chronic high EBV load carriers in this population. CHL state was defined as the presence of high load for >50% of samples for greater than or equal to six months following either asymptomatic infection or complete clinical resolution of EBV disease/PTLD. Thirty-five CHL carriers were identified from our patient population. Pretransplant serologies were available on 34 of these patients: 17 were EBV negative and 17 seropositive; one had unknown EBV serostatus prior to transplant. Seven of the 17 seronegative patients developed their CHL carrier state at the time of their primary EBV infection. Thirteen of the 35 (37%) HLC patients developed EBV disease after meeting the definition of high-load carrier states. EBV-related diseases developing in CHL carriers included EBV adenitis (n=1), EBV enteritis (n=7), PTLD (n=4), and EBV+ spindle cell tumor (n=1). Disease was seen in 7/17 of the seronegative (one PTLD) and 6/17 of the seropositive patients (three PTLD). Thirteen of 35 patients (37%) resolved their CHL state without apparent sequelae while nine remain asymptomatic CHL carriers. Three children have had more than one episode of CHL. These data provide important information about the outcome of chronic EBV high-load carriage in pediatric intestinal transplant recipients.

Alemtuzumab Used with Fludarabine and Cyclophosphamide (FCC) for Stem Cell Transplantation in Acquired Aplastic Anemia Is Associated with a Low Risk of Graft Versus Host Disease and Viral Infections and with Sustained Engraftment.

Abstract 1084Poster Board I-106Graft rejection and chronic GVHD remain major obstacles to successful outcome after stem cell transplantation (SCT) for aplastic anemia (AA). Using cyclophosphamide (CY) 200mg/kg with ATG, rejection occurs in 5-10% and chronic GVHD in 30-40% of patients transplanted from HLA matched sibling donors (MSD). For unrelated donor (UD) SCT using Fludarabine with CY and ATG, rejection occurs in 18% (30% for patients > 14 years of age) and chronic GVHD in 27%. We have pioneered the use of Alemtuzumab with CY in AA SCT and shown a reduction in GVHD although graft rejection was high at 24%. More recently, Fludarabine has been added to the conditioning to reduce graft rejection. In this retrospective, multi-center study, we report outcomes after SCT for acquired AA in 37 patients using Alemtuzumab, Fludarabine and CY (FCC) conditioning regimen. Alemtuzumab dose was 0.2mg/kg x5 days (n=20), 60mgx1 (n=12), 25mgx4 (n=4) and 40mgx1+30mgx2 (n=1). All patients received Fludarabine 30mg/m2x4 and CY 300mg/m2 x4 (FCC). Patients were transplanted from 1999 to 2009. Median follow up of survivors was 641days (range 72-3547). Disease severity was ‘very severe' in10, ‘severe' in 20 and ‘non-severe' in 7 patients. SCT was performed using MSD in 15 patients (40%) and UD in 22 (60%), of whom all but one were matched for 8/8 or 10/10 alleles. Median age was 35 years (range 8-55). Stem cell source was bone marrow (BM) in 21 (57%), peripheral blood stem cells (PBSC) in 7 (19%), BM+PBSC in 5 (13%) and G-mobilised BM in 4 (11%). Time from diagnosis to SCT was < 12 months in 57% of patients and > 12 months in 41%. 8/15 (53%) of sibling transplants and 18/22 (82%) of UD transplants received immunosuppressive therapy prior to SCT. There were 5 cases of graft failure, early rejection in 2 UD SCT and late graft rejection in 3 (one UD and two MSD). Of the 5 patients with graft rejection, BM was used as the stem cell source in 3, G-mobilised BM in one and PBSC in one. Cumulative incidence of graft failure at 1 year was 15% ± 4% (14% for MSD and 15% for UD SCT). For patients transplanted > 12 months from diagnosis, graft failure was 25% compared with 10% for patients transplanted within 12 months (p= 0.191). Acute GVHD occurred in 13.5% patients, grade I-II in all cases. Chronic GVHD occurred in only one patient (2.7%, extensive). Data for CMV and adenovirus infections was available in 21 patients, and in 20 patients for EBV. CMV reactivation occurred in 2/21 (9.5%) patients, with one case of CMV disease. EBV infection occurred in 2/20 patients (10%): one responded to Rituximab and one patient died from progressive EBV PTLD. There were no cases of adenovirus infection. Overall survival (OS) at 3 years was 89% (93% for MSD and 85% for UD SCT, p= 0.658). For all patients, OS was 95% when time from diagnosis to SCT was < 12 months and 80% for > 12 months (p= 0.273). For patients > 40 years of age, there was no significant difference in OS compared with patients < 40 years old (93% vs 82%). There were 3 deaths, one from chronic GVHD and CMV at day + 427, one from graft failure at day +134 and one due to EBV PTLD at day +180. We conclude that the use of Alemtuzumab with Fludarabine and CY (FCC) for MSD and UD SCT for acquired AA is associated with excellent survival, a low incidence of acute and chronic GVHD and a low incidence of viral infections. DisclosuresMarsh:Genzyme: Consultancy, Honoraria. Off Label Use: Alemtuzumab used for conditioning for stem cell transplantation for aplastic anemia. Gupta:Genzyme: Honoraria, Research Funding.

Chronic high Epstein‐Barr viral load carriage in pediatric liver transplant recipients

Development of EBV disease and PTLD is usually accompanied by the detection of a high EBV load in peripheral blood. However, many children undergoing primary EBV infection following LTx will maintain chronically elevated EBV loads in the absence of clinical symptoms. To better understand this phenomenon, we retrospectively reviewed the records of children undergoing LTx at our center from 1997 to 2007 to identify chronic high EBV load carriers in this population. A CHL state was defined by the presence of a high load for >50% of samples for greater than or equal to six months following either asymptomatic or complete clinical resolution of EBV disease/PTLD. A total of 35 CHL carriers were identified. Pretransplant serologies were available for 29 of the 35; 22/29 (76%) were EBV negative prior to LTx; eight of these 22 developed their CHL state at the time of their primary EBV infection. Fourteen of the 35 had EBV disease (n = 7) or PTLD (n = 7) prior to development of the CHL state. Only one of 35 CHL carriers developed PTLD or lymphoma while they were a high load carrier. In all, 23/35 resolved their CHL state without apparent sequelae while 11 children continue to be asymptomatic high load carriers. These data provide important information about the outcome of chronic EBV high load carriage in pediatric liver transplant recipients.

A two-arm prospective trial evaluating the ability of EBV PCR to diagnose and monitor posttransplant lymphoproliferative disorder

8057 Background: EBV PCR is known to be useful in the management of patients with PTLD. However, the optimal DNA target, relative importance of peripheral blood intracellular versus free plasma EBV, and baseline profile of these EBV PCR variations in a transplant population remains unclear. This study explored these issues as well as assessed the utility of a 6 assay EBV PCR panel in the management of patients with suspected PTLD. Methods: A prospective 2-arm study was performed. Arm A consisted of 31 patients who underwent lung transplantation. Arm B consisted of 35 patients evaluated for possible PTLD. All patients underwent an initial evaluation with EBV PCR and EBV VCA antibody titer. Arm B patients were evaluated for PTLD with CT scans and biopsies of lesions. All patients in Arm A and those in Arm B with documented PTLD were then followed. For the EBV PCR panel, peripheral blood was separated into plasma and whole blood cells and then DNA was purified. Real time EBV PCR was then performed on both samples using primer sets against LMP, EBER and EBNA. Results: No patients on control Arm A developed PTLD. Seventeen (49%) patients on Arm B were found to have PTLD. Thirteen of 17 (76%) had EBV(+) PTLD. Eighteen Arm B patients were given non-PTLD diagnoses. Of 62 patients evaluable for EBV antibody titers, 60 (97%) had IgG for EBV VCA. In Arm A, only 1/31 (3%) patients developed a transient positive low level plasma EBV load. Fourteen of 31 (42%) had detectable low-level intracellular EBV. In patients with EBV(+) PTLD, 11/13 had EBV in plasma and intracellular samples, 1 had intracellular EBV only and 1 patient with isolated CNS PTLD had a negative EBV panel. The EBV PCR panel had high sensitivity (92%) and specificity (67%) for diagnosing EBV(+) PTLD. Comparing the individual PCR assays, whole blood EBER had the best sensitivity (92%) and plasma EBNA &amp; EBER had the best specificity (100%). The EBV PCR panel tracked patient's clinical course well (p=0.06) as they proceeded through treatment. EBV plasma (p=&lt;0.01) and whole blood (p=0.04) copy numbers by EBNA PCR inversely correlated with EBV VCA IgG titers. Conclusion: Peripheral blood EBV PCR is useful in the diagnosis and monitoring of patients with EBV(+) PTLD. No significant financial relationships to disclose.

Increased Risk of Epstein-Barr Virus Associated Post-Transplant Lymphoproliferative Disorder (EBV-PTLD) after Anti-Thymocyte Globulin (ATG) Non-Myeloablative (NMA) Conditioning for Umbilical Cord Blood Transplantation (UCBT).

EBV-PTLD is a known complication of alternative donor hematopoietic stem cell transplantation (HSCT) particularly when used in combination with HSC T-cell depletion and ATG. Initial reports in the setting of UCBT suggested a low incidence of EBV-PTLD (2–5%). We reviewed 335 consecutive patients (pts) who underwent UCBT at our institution between 7/19/94 and 3/29/05. Median age, weight, and follow-up were 16 years (0.2–69), 53.7kg (3.8–134.0) and 1.2 years (77 days9.2 years), respectively. Equine ATG (ATGAM) was used as part of a myeloablative (MA, Cy 120 mg/kg and TBI 1320–1375 cGy ± Flu 75 mg/m2) and non-myeloablative (NMA, Cy 50 mg/kg, Flu 200 mg/m2 and TBI 200 cGy) preparative regimen in 175/240 and 30/95 patients, respectively. As previously reported the overall incidence of EBV viremia and EBV-PTLD remained low. Overall, use of ATG lead to an increase in the incidence of EBV viremia (defined as > 1,000 copies of EBV DNA per mL of whole blood) and EBV-PTLD (14/205 [7%] with vs. 1/130 [0.7%] without ATG [p=0.16]), but this was not statistically significant. In recipients of a MA preparative regimen, EBV viremia or EBV-PTLD was observed in 8/175 (5%) who received ATG and in 0/65 who did not (p=0.81). However, a higher risk of EBV viremia and PTLD was observed in recipients of ATG and a NMA preparative regimen. EBV viremia or EBV-PTLD after NMA preparative regimen was observed in 6/30 (20%) pts who received ATG and 1/65 (2%) who did not (p<0.01) For the whole group, median time to development of EBV-PTLD was 133 days (54–407) with no difference between the MA and NMA groups [132 days (92–407) vs. 133 days (54–247)]. Among 9 pts who developed EBV-PTLD, 5 are alive (2 MA and 3 NMA) 113-1668 days after UCBT. Therefore, we conclude that patients undergoing a NMA UCBT with ATG are at uniquely higher risk for the development of EBV reactivation or EBV primary infection and EBV-PTLD. Routine monitoring of EBV viral load and pre-emptive treatment of patients who develop a positive viral load must be considered for this group of patients.