HHV-6 Viremia Research Articles

Graft Failure Incidence, Risk Factors, and Outcomes in Patients Undergoing Non-Myeloablative Allogeneic Hematopoietic Cell Transplantation Using Post-Transplant Cyclophosphamide

Graft failure (GF) is a major complication of allogeneic hematopoietic cell transplantation (alloHCT) that results in significant morbidity and mortality. Post-transplant cyclophosphamide (PTCy)-based graft-versus-host disease (GVHD) prophylaxis has emerged as an effective regimen across the spectrum of donor-match settings, but few studies have investigated the characteristics of GF in the setting of PTCy-based GVHD prophylaxis. The objective was to detail the incidence, clinical features, risk factors, and outcomes for patients with primary graft failure (PGF) and secondary graft failure (SGF). In this retrospective study at a single institution, 958 consecutive patients undergoing first nonmyeloablative (NMA) alloHCT with PTCy-based GVHD prophylaxis were analyzed. PGF was defined as a failure to achieve an ANC ≥ 500 cells/m3 by day 30 of transplant in the absence of residual disease. SGF was defined as complete loss of donor chimerism after initial engraftment. The incidences of PGF and SGF were 3.8% (n = 37) and 1.8% (n = 17), respectively. Neither PGF nor SGF were associated with HLA disparity. In a multivariate analysis, risk factors for PGF in this cohort included age ≥ 65 (OR 2.4, 95% CI 1.2 to 4.8, P = .0120), an underlying diagnosis of MDS, MPN, or MDS/MPN overlap (OR 2.8, 95% CI 1.4 to 5.7, P = .0050), post-transplant viremia with HHV-6 (OR 2.9, 95% CI 1.5 to 5.7, P = .0030), and low CD34+ dose (OR 0.7, 95% CI 0.5 to 0.9, P = .0080). Patients with PGF had poor overall survival, driven primarily by a high rate of nonrelapse mortality (59% at 36 months). SGF was associated with use of a bone marrow graft source and a diagnosis of Hodgkin lymphoma. Patients with SGF had excellent clinical outcomes with only one of seventeen patients experiencing relapse and relapse-related mortality. The incidence of PGF and SGF in patients receiving NMA conditioning and PTCy is low and is not impacted by HLA disparities between donors and recipients. PGF is more common in recipients with age ≥ 65, a diagnosis of MDS, MPN, or MDS/MPN-overlap, post-transplant HHV-6 viremia, and low CD34+ cell dose. Low total nucleated cell dose is also a risk factor for PGF in patients receiving a bone marrow graft source. Patients who experience PGF have poor outcomes due to high rates of nonrelapse mortality, whereas patients who experience SGF have excellent long-term outcomes.

Improved Gvhd and Relapse Free Survival Outcomes in Older Acute Leukemia Patients Receiving Young Haploidentical Donor Vs Older Matched Sibling Donor Reduced Intensity Conditioning Hematopoietic Cell Transplants

Background: Allogeneic hematopoietic cell transplants (alloHCT) from HLA-matched sibling donors (MSD) or matched unrelated donors (MUD) may cure patients with acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), and myelodysplastic syndromes (MDS). Older patients with AML benefit from alloHCT, but donor selection may be complicated by the advanced age and comorbidities of HLA-matched siblings. Haploidentical (Haplo) HCT with post-transplant cyclophosphamide (PTCy) is an alternative approach to traditional HLA-matched alloHCT. HaploHCT is associated with reduced graft-versus-host disease (GVHD) risk but reduced overall survival (OS) in some series with older recipients. There are limited published data assessing outcomes using younger Haplo donors versus older MSD for older HCT recipients. The objective of this study is to characterize treatment outcomes and GVHD rates in older HCT recipients of younger HaploHCT compared to older MSD grafts. Methods: This retrospective cohort analysis included patients aged 50 years and older with AML, ALL, or MDS who received reduced intensity conditioning (RIC) and either a young Haplo donor or older MSD graft from 2014 to 2020. Young donors included those <50 years old, and older donors were ≥50 years old. The primary outcome was OS one-year post-HCT. Secondary analyses included aGVHD and cGVHD outcomes, relapse-free survival (RFS), GVHD-RFS (GRFS), non-relapse mortality (NRM), infection incidence, time to neutrophil recovery, and relapse incidence. Kaplan-Meier method with log-rank test was used to assess OS, RFS, and GRFS. All data presented are organized as Haplo versus MSD. Results: Twenty-nine patients received younger donor Haplo grafts and 47 patients received older MSD grafts. Median age for donors was 35.4 years vs 61.6 years in the Haplo and MSD cohort, respectively. The underlying hematologic disorder leading to alloHCT in the two cohorts were AML (83% vs 47%), ALL (3% vs 11%), and MDS (28% vs 43%) (p<0.001). Stratified cytogenetic risk categories for each diagnosis were not significantly different. RIC regimens included Fludarabine (Flu)/Melphalan or Flu/Busulfan for older MSD recipients, whereas the younger donor Haplo cohort received Flu/Cy/TBI (200cGy). PTCy/Tacrolimus (Tac) was the GVHD prophylaxis (ppx) regimen for all Haplo recipients, whereas 96% of MSD cohort got Tac/Methotrexate (MTX) and 4% of MSD cohort got Tac/MTX/MMF. Peripheral blood was the graft source in 62% of HaploHCT and 100% of MSD (p<0.001). Seventy-six percent of donors in the Haplo cohort were recipient offspring. One-year OS was 86% vs 72% (p=0.27), RFS was 69% vs 70% (p=0.76), NRM was 7% vs 9% (p=0.86), and GRFS 89% vs 62% (p=0.005) [Table 1] for Haplo vs MSD cohorts, respectively. Median OS (HR 0.88, p=0.785) and median RFS (HR 1.38, p=0.459) were not reached in either group. Median GRFS was longer in the Haplo cohort (190 vs 148 days, HR 0.52, p=0.021) [Figure 1]. One-year incidence of relapse was not different between cohorts (p=0.14). Incidence of aGVHD (38% vs 32%, p=0.51) was similar in both cohorts, although maximum aGVHD grade was lower in the Haplo group (p=0.04). cGVHD incidence numerically favored HaploHCT (45% vs 66%, p=0.08) [Table 1]. Individuals receiving HaploHCT had a longer median time to neutrophil engraftment (19 vs 14 days, p<0.001) and a shorter median time to full CD3 chimerism (32 vs 76.5 days, p<0.001). They also had a higher incidence of CMV viremia (p=0.014), BK viremia (p=0.05), and fungal infections (p=0.047) [Table 1]. Incidence of HHV6 (p=0.18) and EBV viremia (p=0.89) were not different between cohorts. Discussion: Our results demonstrate similar OS, RFS and incidence of aGVHD and cGVHD between younger donor HaploHCT and older MSD alloHCT for older patients. GRFS was significantly better in the Haplo cohort, which may have been primarily influenced by higher incidence of cGVHD and higher grades of aGVHD observed for recipients of older MSD grafts with Tac/MTX-based GVHD ppx. aGVHD and cGVHD rates may be reduced with the use of HaploHCT and incorporation of PTCy at the expense of more opportunistic infections. Our results suggest that young donor HaploHCT using PTCy may be a reasonable alternative for alloHCT and reduce risks for GVHD for older patients with leukemia even if a MSD is available. These data also suggest MSD alloHCT with PTCy should be explored. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

CD45RO+ T-Cell Add Back and Prophylactic Blinatumomab Administration Post Tcrαβ/CD19-Depleted Haploidentical Transplantation in Pediatric Patients with High Risk Acute Leukemia

For patients receiving haploidentical donor (haplo) hematopoietic cell transplant (HCT), depletion of TCRαβ T cells from the haplo-graft allows for excellent outcomes and low rates of graft-versus-host disease (GVHD), albeit with a significant delay in immune reconstitution (IR). The adoptive transfer of donor T-cells has been used to optimize IR but increases the risk of GVHD. CD45RA-depleted (memory) T-cells are associated with low rates of alloreactivity and thereby GVHD but retain specificity for leukemic and viral antigens. We implemented a prospective trial utilizing escalating doses of CD45RA-depeleted T-cell as addback following TCRαβ/CD19-depleted haploHCT to improve IR. Patients with acute lymphoblastic leukemia (ALL) also received prophylactic Blinatumomab (Blina) following infusion of CD45RA-depeleted T-cell to overcome the risk immune escape secondary to HLA-loss and relapse (NCT03849651).Between 2019 to 2020, 30 pediatric patients (9 males, 21 females) with high-risk acute leukemia were enrolled. Median age at HCT was 8.7 years (range 0.9-18.8). Nineteen patients had ALL, 11 patients had AML. Ten patients were in CR1, 13 in CR2 and 7 in CR3/>. Five patients received prior CD19-CAR T-cell therapy. The donors used were mothers (n=15), fathers (n=13), or sibling/others (n=2). All patients received a reduced intensity preparative regimen consisting of Fludarabine, Melphalan, Cyclophosphamide and Thiotepa. ATG was given on days -5, -4 and -3. Mobilized peripheral blood graft were infused on day 0 with a median number of CD34+ cells, γδ+ T-cells, αβ+ T cells, and B cells of 14.8, 22.7, 0, and 0.09x 10 6/kg, respectively. No GVHD prophylaxis was used post-HCT. Two weeks following engraftment, patients received CD45RA-depleted T-cell addback in 3 escalating doses (DL1: 1x10 5cells/kg, DL2: 1x10 6 cells/kg, DL3:1x10 7 cells/kg).All 30 patients engrafted with a median time for neutrophil and platelet engraftment of 10 (range: 9-11) and 15 (range: 13-20) days, respectively. Infusion of escalating doses of CD45RA-depleted T-cells was well tolerated. One month post infusion, there was a significant increase in the median number of CD3 T-cells, including CD8 and CD45RO+ T-cell subsets (**p<0.01, ***p<0.001, Fig 1A). There was also significant expansion of virus-specific T-cells (VSTs) directed towards Cytomegalovirus (CMV), Adenovirus (AdV), BK, or HHV-6 as shown by Elispot assays (**p<0.01, Fig. 1B). TCR repertoire, as assessed by Vb spectratyping, was broad and comparable to the donor by month 6 post-HCT. The incidence of CMV, AdV, and HHV-6 viremia was 60%, 6.7%, and 16.7% respectively. The median duration of viremia was 4 weeks for CMV (range: 1-13), 3 weeks for AdV (range: 2-13) and 2.5 weeks for HHV-6 (range: 2-20). There were 11 episodes of viral disease (7 colitis, 3 pneumonitis, 1 lymphadenitis). All episodes of viral disease resolved, except 2 that were ongoing at the time of death. The incidence of acute GVHD within 28 days post-infusion after dose level 1, 2 and 3 was 0%, 20% and 10% respectively (p=NS). The cumulative incidence of aGVHD and grade III-IV aGVHD for the entire cohort was 26.7% (12.4-43.3%) and 13.3% (4.1-28.1%) respectively. There was no chronic GVHD; however, follow up is short. Sixteen patients received and tolerated prophylactic Blina infusions. The median time to receiving Blina after CD45RO+ infusion was 29 days (range 15-56). Four of the 16 patients who received Blina relapsed: 3 with CD19+ disease and 1 with CD19-negative disease. With a median follow up of 12.7 months (range 3.5-24.5), 1 year OS and LFS for the cohort was 86.3% (74.6-99.7%) and 69.8% (55.2-88.4%) respectively. The cumulative incidence of relapse was 31.8% (15.3-49.8%) and of non-relapse mortality was 3.3% (0.2-14.8%) respectively.In this interim analysis, addback of CD45RA- depleted T-cells following TCRαβ/CD19-depleted haplo HCT was safe and led to enhanced functional immune reconstitution. Prophylactic infusion of Blina is well tolerated and its use post-transplant warrants further investigation. Analyses into the effect of ATG on immune reconstitution are underway. [Display omitted] DisclosuresSharma: CRISPR Therapeutics: Other, Research Funding; Novartis: Other: Salary support paid to institution; Vertex Pharmaceuticals/CRISPR Therapeutics: Other: Salary support paid to institution; Spotlight Therapeutics: Consultancy; Medexus Inc: Consultancy; Vindico Medical Education: Honoraria. Gottschalk: Catamaran Bio: Consultancy; Immatics: Membership on an entity's Board of Directors or advisory committees; Other: Other: patents and patent applications in the field of cancer cell and gene therapy ; Novartis: Consultancy; Tidal: Consultancy; Tessa Therapeutics: Consultancy. Triplett: Miltenyi: Other: Travel, meeting registration.

Association of HHV-6 With Outcomes in CMV-seronegative Liver Transplant Recipients With CMV-seropositive Donors Receiving Preemptive Antiviral Therapy.

Risk factors, virological parameters, and outcomes associated with HHV-6 viremia in high-risk donor CMV-seropositive and recipient CMV-seronegative (D+R-) liver transplant recipients in the current era are incompletely defined. The study population consisted of patients in the preemptive therapy (PET) arm of a randomized, controlled trial of PET versus valganciclovir prophylaxis for CMV prevention in D+R- liver transplant recipients. Weekly blood samples through 100 d in the PET group were tested for HHV-6 viremia using a real-time quantitative polymerase chain reaction. Assessments included virological characteristics and relationship with CMV, risk factors, and impact of HHV-6 viremia with outcomes through 12 mo posttransplant. HHV-6 viremia at any level developed in 42% (40 of 96). Older patient age (P = 0.03), longer hospitalization (P = 0.015), and ICU stay at transplantation (P = 0.029) were significantly associated with high-grade viremia. Concurrent HHV-6 and CMV viremia was associated with earlier onset of HHV-6 viremia (P = 0.004), higher HHV-6 area under the curve (P = 0.043), and higher peak HHV-6 viral load (P = 0.006) versus HHV-6 viremia alone. High-grade viremia was independently associated with biopsy-proven rejection within 12 mo (P = 0.045) posttransplant. Among D+R- liver transplant recipients receiving valganciclovir as PET, high-grade HHV-6 viremia was associated with increased age and critical illness in ICU at time of transplant and was independently associated with allograft rejection.

Allogeneic Blood and Marrow Transplantation for Pediatric Patients with Sickle Cell Anemia: An Institutional Experience

Introduction: Sickle cell anemia (SCA) is a genetic disease with potentially debilitating complications and shortened life-expectancy. Allogeneic hematopoietic stem cell transplantation (HSCT) remains the only cure for SCA, but is limited by the lack of available histocompatible sibling donors and transplant related morbidities. Alternative donor HSCT for SCA has been associated with variable outcomes. Methods: We conducted a retrospective review of all patients with SCA who underwent HSCT at our center between January 2014 and June 2017. Results: Table 1 shows the pre-HSCT characteristics of the study population (n=19). Candidates for HSCT were selected based on institutional and/or study eligibility criteria and were consented per the Declaration of Helsinki. The majority of patients were receiving chronic transfusions or hydroxyurea therapy. Two patients had concurrent autoimmune diseases and 79% had low 25-hydroxycholecalciferol levels (median 17.8 ng/ml). 9 patients (47.3%) received HLA-identical sibling transplants (MSD), 6 (31.5%) UD, and 4 (21%) α/β T cell depleted related haplo-identical (haplo) transplants. The median pre-HSCT comorbidity index (CI) was above 3 for patients receiving alternative donor transplants (>3 is associated with higher pre-HSCT acuity). HSCT characteristics are shown in Table 2. The majority of patients (68.4%) received bone marrow (BM), while 21% received mobilized peripheral blood stem cell (PBSC) grafts. All patients achieved initial high-level (>90%) donor chimerism. The median time to neutrophil engraftment (>500 cells/µL) was 14 days with significantly earlier engraftment seen among haplo recipients (median 10 days) compared to other graft sources (p < 0.02). The median time to platelet engraftment (>50,000 /µL) was 20 days. The median time to CD3+ T lymphocyte recovery (>200 cells/uL) was 195 days (range 20-384) (significantly earlier for the haplo group (figure 1a, p=0.01) and for CD19 (>66 cells/uL) was 104 (range 90-526) days post-HSCT (figure 1b). Secondary early graft rejection occurred in 2 patients who received haplo-identical HSCT, with sustained donor engraftment following a second transplant with the same donors in one of these patients. Overall incidence of > grade II (severe) acute graft versus host disease (GVHD) was 26%, with no significant difference observed among haplo recipients despite the absence of primary GVHD prophylaxis. Two UD recipients developed chronic GVHD (10.5% overall incidence). 11 (57%) patients (6 MSD, 3 UD, 2 haplo) developed CMV viremia, with one late onset disseminated CMV meningitis; 7 patients (36.8%) (3 MSD, 4 UD) developed adenoviremia; one patient developed HHV-6 viremia around the time of graft rejection. Both patients with concurrent autoimmune diseases did not experience significant post-HSCT complications. One patient with type I diabetes mellitus diagnosed 60 days prior to HSCT has had stable glycemic control. One patient with systemic lupus erythematous (SLE) remains in SLE remission post-HSCT. With a median follow-up of 568 (105-919) days, the overall 2-year survival was 84.2%. 88.8% for MSD, 83.3% for UD, and 75% (3 patients) survival for α/β T cell depleted haploidentical related HSCT (p=0.7) and a mean performance score of 90 among survivors. No adverse events were noted among donors with sickle cell trait, including 4 parent donors who received PBSC mobilization with either filgrastim and/or plerixafor. Conclusion: Alternative donor allogeneic HSCT should be considered for carefully selected patients with SCA. α/β T cell depleted related haplo-identical HSCT appears promising with low rates of severe acute GVHD in the absence of primary prophylaxis. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Prospective study of blood viral load of Epstein-Barr virus, herpes virus type 6 and human parvovirus B19 in Crohn's disease: Does therapy matter?

The interplay between inflammatory bowel disease (IBD) and DNA viruses, such as Epstein-Barr (EBV), human parvovirus B19 (HPVB19) and human herpes type 6 (HHV6) is scarcely studied. The main aim of this prospective study is to screen for EBV, HSV6, and HPVB19 DNA viremia in adult patients with stable Crohn's disease (CD), correlating the results with IBD treatment. From July 2015 - March 2017, 100 patients were enrolled and divided in four groups of 25 participants each, according to in course treatment. Blood collections were performed every 5 months in all patients. Antibodies for EBV and HPVB19 were screened and repeated if negative. Blood EBV DNA, HPVB19 DNA, and HHV6 DNA were quantified by quantitative real-time Polymerase Chain Reaction. Patients had evidence of EBV (100 %) and HPVB19 (70 %) past infection. Across the study timeline, EBV-DNA, HPVB19-DNA, and HHV6-DNA were detected in the blood of 25, 11, and 7 patients, respectively. Viremia was detected only once in 72 %, 73 %, and 86 % of the patients in the studied period, for EBV, HPVB19, and HHV6, respectively. We did not find significant differences between treatment groups, independently of the viral cut-off for the three viruses. The detection of EBV, HPVB19, and HHV6 viremia, in stable CD patients, was not impacted by biological/immunosuppressant therapy. Although attractive as a non-invasive technique, this approach did not prove to be useful in stable patients. More and larger studies are needed to address the relevance of these viruses on IBD course, in stable patients and during exacerbations.

No Evidence for Long-Term Persistence of HHV-6 Viremia after Cord Blood Transplantation

HHV-6 reactivation is common after cord blood transplantation (CBT). However, the ability of the new immune system to clear HHV-6 viremias is unknown. A previous study of 23 CBT recipients suggested that ∼50% of patients had detectable HHV-6 by whole blood PCR over a year after transplant (Illiaquer et al. J Infect Dis 2014; 567-570). We studied HHV-6 persistence in a larger cohort using serum. We reviewed CBT recipients at the University of Minnesota (2011-2017) who reactivated HHV-6 (whole blood quantitative PCR > 500 copies/mL on at least 1 occasion) by 1 year post-transplant. A subset (n = 59) had an available research serum sample at 1 year (+/- 4 weeks) on an IRB-approved biorepository protocol; we tested these samples by quantitative PCR for HHV-6A and B (Rotor-Gene, Qiagen) in a CLIA-certified laboratory. Median (range) age was 44 (1-72) years; 40 (68%) were male. The most common underlying diseases were acute leukemia (n = 29), lymphomas (n = 10), and non-malignant disorders (n = 9). 33 patients were CMV seropositive. ATG or alemtuzumab were used in 16 patients. Conditioning was reduced-intensity in 31 patients. GVHD prophylaxis was cyclosporine/MMF in 41 and sirolimus/MMF in 18. Grade II-IV acute GVHD occurred in 25 patients and chronic GVHD by 1 year in 12. Twelve (20%) patients cleared viremia (based on whole blood PCR) before the research sample was collected. This clearance occurred at median (range) of 64 (13-244) days after HCT. One (2%) patient cleared HHV-6 at 538 days after HCT. 46 (78%) patients continued to have detectable whole blood PCR until a median (range) of 127 (15-1441) days after HCT with no subsequent negative sample. Among research serum samples collected at 1 year, only 1 had HHV-6A (14,556 copies/mL) and 1 had HHV-6B (below the lower limit of quantification). The patient with detectable HHV-6A had chromosomal integration. The patient with detectable HHV-6B had previous whole blood levels ranging 9,900-164,800 copies/mL. Late persisting HHV-6 viremia was rare in our 59 CBT recipients. Using serum in our study permitted exclusive detection of cell-free HHV-6 DNA, which is a more specific test for HHV-6 reactivation. We suggest no defect in cord blood allograft's ability to clear HHV-6 viremia.

Impact of HHV-6 in Recipients of Ex Vivo T-Cell Depleted Hematopoietic Cell Transplant

<h3>Introduction</h3> Recipients of ex-vivo T-cell depleted (TCD) (CD34⁺ selected) hematopoietic cell transplant (HCT) are at increased risk for infections by double-stranded DNA viruses. TCD HCT recipients at Memorial Sloan Kettering Cancer Center were routinely screened for HHV-6 by plasma PCR between 2012 and 2016. The objectives of our study were to 1) report the incidence of persistent HHV-6 viremia and disease 2) identify risk factors of persistent HHV-6 viremia; 3) examine the association between persistent HHV-6 viremia and overall survival (OS) at 1-year post-HCT. <h3>Methods</h3> Recipients with TCD HCT between 2012 and 2016 routinely screened for HHV-6 by plasma PCR were reviewed retrospectively. CD34⁺ selection was performed by the CliniMACS CD34 Reagent system (Miltenyi Biotec, Germany). HHV-6 viremia was defined as ≥1 HHV-6 viral load (VL) >limit of quantification. Persistent HHV-6 viremia was defined as ≥2 consecutive measurements of VL ≥500 copies/mL through day+100 post-HCT, death, relapse, and second transplant whichever occurred first. Cox proportional model was used to examine the risk factors of persistent HHV-6 viremia. One-year OS was estimated by Kaplan-Meier method. <h3>Results</h3> Of 312 patients, 59% were male and median age was 55 years (range, 22-73). 67% had acute leukemia and myelodysplastic syndrome and 18% had mismatched donors. 55% developed HHV-6 viremia. Eighty-three (27%) had persistent HHV-6 viremia with a median duration of 67 days (interquartile range [IQR], 56-75) (Figure 1). Mismatched donor (P=0.04) and recipient CMV seronegativity (R-) (P=0.04) were associated with persistent HHV-6 viremia. Of 83 patients with persistent HHV6 viremia, 23 (28%) had max VL ≥10,000 copies/mL and 7 (8%) developed HHV-6 disease (encephalitis 1, pneumonitis 4, and organizing pneumonia 2). Maximum VL with HHV-6 disease was a median VL 71,700 copies/mL (IQR, 8,211-123,500). Persistent HHV-6 viremia was associated with lower absolute lymphocyte counts (ALCs) up to 1-year post-HCT (figure 2) and lower 1-year OS (P=0.02) (figure 3). <h3>Conclusion</h3> 27% of TCD HCT recipients developed persistent HHV-6 viremia. Mismatched donor and CMV R- were associated with persistent HHV-6 viremia. Among patients with persistent HHV-6 viremia, 8% developed HHV-6 disease. Persistent HHV-6 viremia was associated with lower ALCs and OS at 1-year post-HCT.

Incidence and Impact of Non-CMV Herpes Viral Infection in Haploidentical and Matched Sibling Donors Receiving Post-Transplant Cyclophosphamide (PTCy): A CIBMTR Analysis

Single-center studies have reported increased risk of CMV infection in patients undergoing allogeneic transplant using haploidentical graft with post-transplant cyclophosphamide (HaploCy), however limited data exists regarding the impact of this transplant platform on the incidence of non-CMV herpes viruses (NCHV) infection (viremia/disease). Furthermore, it is unclear if the donor type or altered immune reconstitution resulting from the use of PTCy contributes to this infection risk. To study this, patients reported to the CIBMTR with AML/ALL/MDS transplanted between 2012 and 2017 receiving HaploCy (n = 757), matched-sibling donors receiving PTCy (SibCy, n=403), or matched sibling with calcineurin inhibitor and methotrexate/mycophenolate mofetil (SibCNI, n=1605) with either marrow or peripheral blood grafts were examined (Table 1). Too few matched unrelated donors (MUD) receiving PTCY reported to CIBMTR resulted in exclusion of MUD transplants. The cumulative incidence of NCHV in the HaploCy, SibCy and SibCNI were 6.9% (99% CI, 4.7-9.4), 3.2% (1.3-5.9), and 1.7% (1-2.6) respectively by day 30 [p<0.001] and increased to 13.9% (10.8 – 17.3), 10.7 % (7.1 – 15), and 5.7% (4.3 – 7.3) by 6 months after transplant [p<0.001] [Figure 1]. Notably, this is driven by a higher frequency of HHV-6 viremia [HaploCy = 9.3%; SibCy = 5.7%; SibCNI = 1.9%]. Figure 2 shows the multivariable models of survival, relapse, transplant related mortality, and chronic GVHD with a reference group of SibCNI without NCHV infection for the main effect variable of donor and infection. The model examines through the first 2 years after transplant and there was a center effect. Our results suggest that HaploCY is associated with an increased incidence of NCHV infection and HHV-6 viremia predominates. The SibCy cohort experienced an increased incidence of NCHV infections as well. However, only in the HaploCy group is this independently associated with increased TRM and decreased survival. Improved surveillance and preemptive treatment may mitigate the mortality associated with NCHV infections in HaploCy recipients.

Combination of a Cyclophosphamide-Total Body Irradiation Conditioning Regimen and Tacrolimus Plus Mycophenolate Mofetil for Gvhd Prophylaxis Is Associated with Higher HHV-6 Encephalitis Incidence after Cord Blood Transplantation

Background Human herpesvirus-6 (HHV-6) encephalitis occurs frequently through cord blood transplantation (CBT), and leads to a high risk of mortality and morbidity. Although CBT is a known risk factor for HHV-6 encephalitis, a thorough analysis of risk factors for HHV-6 encephalitis in patients receiving CBT has not been performed, and several risk factors remain unidentified. In our center, generally, either tacrolimus (Tac) plus methotrexate (MTX) (Tac/MTX) or mycophenolate mofetil (MMF) (Tac/MMF) was selected for graft-versus-host disease (GVHD) prophylaxis after CBT, at the physician's discretion. However, in recent years, Tac/MMF became the standard choice. We observed that the incidence of HHV-6 encephalitis tended to be markedly higher among patients receiving treatment with a cyclophosphamide (Cy) and total body irradiation (TBI) (Cy/TBI)-based regimen and Tac/MMF after CBT. Therefore, we aimed to ascertain whether certain conditioning regimens and GVHD prophylaxis regimens are associated with the occurrence of HHV-6 encephalitis after CBT. Methods In this retrospective study, we examined 103 patients undergoing CBT for hematological diseases at our center between 2011 and 2019. To analyze the effect of GVHD prophylaxis on the occurrence of HHV-6 encephalitis, we divided patients into two groups based on the GVHD prophylaxis regimen used: the Tac/MTX group and the Tac/MMF group. We excluded one patient who received Tac alone and one who received cyclosporine plus MTX. Finally, 101 patients were enrolled. Routine peripheral blood examinations for HHV-6 were performed once or twice a week. HHV-6 encephalitis was defined as the presence of a central nervous system dysfunction, along with a positive polymerase chain reaction result for HHV-6 DNA in the cerebrospinal fluid. HHV-6 viremia was defined as the presence of HHV-6 in the peripheral blood. Results The median age of patients was 47 years, and the median follow-up duration for surviving patients was 432 days. Conditioning regimens included myeloablative conditioning (MAC, n=64) and reduced-intensity conditioning (RIC, n=37). MAC included Cy/TBI-based regimens in 42 patients and fludarabine (Flu) plus busulfan (Bu) (Flu/Bu)-based regimens in 23, and RIC included Flu plus melphalan-based regimens in 34 patients and other regimens in 2. Sixty-four patients received Tac/MMF as GVHD prophylaxis, whereas 37 received Tac/MTX. Six patients received HLA-matched (6/6) cord blood (CB), 27 received HLA one-antigen mismatched CB, and 68 received HLA two-antigen mismatched CB. The median total nucleated cell number and CD34-positive cell number at cryopreservation were 2.2 × 107/kg and 0.7 × 105/kg, respectively. Thirteen patients (12.8%) experienced primary graft failure. Overall, the cumulative incidence of HHV-6 viremia on day 40 was 68%, and the median time from CBT to HHV-6 viremia was 23 days. The cumulative incidence of HHV-6 viremia was significantly higher in the Tac/MMF group than in the Tac/MTX group (Tac/MMF group, 75%; Tac/MTX group, 56%; p=0.03). Ten patients developed HHV-6 encephalitis. Overall, the cumulative incidence of HHV-6 encephalitis on day 60 was 10.1%. The cumulative incidence of HHV-6 encephalitis tended to be higher in the Tac/MMF group than in the Tac/MTX group (14.1% vs. 2.7%, respectively; p=0.08). Therefore, the administration of Tac/MMF as GVHD prophylaxis after CBT was identified as a probable risk factor for HHV-6 encephalitis, and we sought to identify more such risk factors, specifically among patients receiving Tac/MMF. In the analysis of Tac/MMF group, the cumulative incidence of HHV-6 encephalitis was significantly higher among patients receiving Cy/TBI-based regimens than among those receiving other regimens (35.7% vs. 8.1%, respectively; p&lt;0.01) (Fig. 1a). In addition, among the entire group of patients receiving Cy/TBI-based regimens, the cumulative incidence of HHV-6 encephalitis was significantly higher in the Tac/MMF than in the Tac/MTX group (35.7% vs. 0%, respectively; p&lt;0.01) (Fig. 1b). Conclusion Our analysis showed that patients receiving Tac/MMF as GVHD prophylaxis after CBT with a Cy/TBI-based regimen have a significantly higher risk of developing HHV-6 encephalitis. Further studies using a large cohort are required to elucidate the association between the occurrence of HHV-6 encephalitis and the use of Tac/MMF in patients undergoing CBT with a Cy/TBI-based regimen. Disclosures No relevant conflicts of interest to declare.

Development of HHV-6-Specific Immunity after Cord Blood Transplantation in Adults Depends on Reconstitution of Thymopoiesis and Regeneration of CD4+ T Cells

The treatment of hematological malignancies with umbilical cord blood transplantation (UCBT) is rapidly increasing for adult patients. Disadvantages of UCBT include insufficient cell numbers for adult patient reconstitution, a lack of antigen experienced cells, and deficits in T cell signal transduction mechanisms. Consequently, UCBT is frequently associated with impaired immune function and high infection-related mortality. To counter these difficulties, transplantation with two UCB units has been employed to improve immune reconstitution in adult patients. We evaluated both the quantitative and functional reconstitution of cellular immunity in a group of adult patients undergoing UCBT. Thirty-two patients with a median age of 50 years with hematopoietic malignancies were treated with reduced intensity conditioning (Flu/Mel/rATG) followed by infusion with two sequential UCB grafts and GvHD prophylaxis with tacrolimus and sirolimus. The grafts were at least a 4/6 match with each other and the recipient. Here we report the results of 27 patients who have completed at least one year of follow up. Assessments were done prior to transplant and at various time intervals until 12 months post UCBT. Neutrophil and platelet engraftment occurred at a median of 21 days and 42 days, respectively. CD3+ populations remained severely depressed until 8 wks post-transplant when they gradually began to re-emerge. However the CD4+ and CD8+ populations demonstrated distinctly different reconstitution kinetics. At 6 months the median value of absolute numbers of CD4+ lymphocytes was 35% of pre-transplant levels increasing to 42% at 1 yr post-transplant, a median value far below the normal range for adults. In contrast, at 6 months post-transplant CD8+ lymphocytes remained severely depressed to 12% of pre-transplant levels, but dramatically increased and reached normal levels by 1 yr after UCBT. Interestingly, both the CD14+ monocyte and the CD16+CD56+ NK cell populations expanded dramatically at 4 wks post-transplant and reached pre-transplant levels and were within the normal range by 6 months. CD20+ B cell repopulation began at 8 wks post-transplant, displayed a striking expansion leading to a 17-fold increase in the median value for B cell numbers over pre-transplant values at 1 year and resulting in a median value of absolute numbers near the top of the normal range. To evaluate functional T cell immune reconstitution in vivo, we performed IFN-γ ELISpot analysis on CMV stimulated PBLs and compared the results to a PCR-based assay for CMV viremia. Additionally, we assessed the reconstitution of thymopoiesis with the T cell receptor excision circle (TREC) assay and real-time PCR. 16/27 patients and 26/52 UCB products were CMV seropositive prior to transplant. In the post-UCB period, development of CMV-specific effectors as determined by ELISpot did not always correlate with clearance of CMV viremia. Specifically, prior to 8 weeks post-UCBT, 8 out of 12 (67%) patients with CMV-positive ELISpot displayed CMV viremia, between 8 weeks and 100 days post-UCBT 4 out of 11 (36%) patients with CMV-positive ELISpot displayed CMV viremia and after 100 days post-UCBT only 3 out of 10 patients (30%) who developed CMV-positive ELISpot remained positive for CMV viremia. Identification of functional CMV effectors was only associated with the numbers of CD8+CD45RA+ cells (p=0.01) and the development of high TREC concentrations (p=0.01) that were detected after 6 months of UCBT, and was independent of GvHD or mixed chimerism. Taken together these results indicate that reconstitution of T cell immunity after UCBT is characterized by delayed recovery of CD4+ and CD8+ T cells and correlates with reconstitution of thymopoiesis and increase of naive CD8+CD45RA+ T cells that can develop into efficient pathogen-specific effectors.

The role of herpesviruses 6 and 7 in the development of chronic fatigue syndrome: a review of literature and description of clinical cases

At the issue represented the etiopathogenesis of the chronic fatigue syndrome of (CFS) with immune dysfunction. Many doctors consider this problem only from the point of view of non-psychological disorders requiring only psycho-correction and non-drug treatment. However, syndromocomplex of CFS includes not only neuropsychiatric disorders, but also fibromyalgia syndrome, unexplained genesis, lymphadenopathy, non-specific polyarthralgias. It is also controversial about the feasibility of treating type 6 herpesviruses and type 7 viruses. Some authors consider the need for antiviral therapy only when reactivating the herpesvirus infection, in the transplantation of organs and tissues. However, for frequent HHV-7 and HHV-6 viremia remains resistant to ganciclovir, unlike CMV and EBV, which is successfully controlled by viremia.

The role of herpesviruses 6 and 7 in the development of chronic fatigue syndrome: a review of literature and description of clinical cases

At the issue represented the etiopathogenesis of the chronic fatigue syndrome of (CFS) with immune dysfunction. Many doctors consider this problem only from the point of view of non-psychological disorders requiring only psycho-correction and non-drug treatment. However, syndromocomplex of CFS includes not only neuropsychiatric disorders, but also fibromyalgia syndrome, unexplained genesis, lymphadenopathy, non-specific polyarthralgias. It is also controversial about the feasibility of treating type 6 herpesviruses and type 7 viruses. Some authors consider the need for antiviral therapy only when reactivating the herpesvirus infection, in the transplantation of organs and tissues. However, for frequent HHV-7 and HHV-6 viremia remains resistant to ganciclovir, unlike CMV and EBV, which is successfully controlled by viremia.

Treatment with Foscarnet after Allogeneic Hematopoietic-Cell Transplant (AlloHCT) Is Associated with Long-Term Loss of Renal Function

Introduction: Despite a well-established risk of chronic kidney disease (CKD) in 20-30% of patients undergoing AlloHCT, the benefits of treating serious infections, such as cytomegalovirus (CMV), with nephrotoxic drugs often outweigh this risk. Given a lack of consensus on the optimal management of post-transplant Human-Herpes Virus 6 (HHV6) reactivation, our center has taken an aggressive stance toward screening for and treating HHV-6 viremia with foscarnet, a nephrotoxic drug with an unknown impact on long-term renal function.Methods: To clarify the impact of foscarnet exposure on long-term renal function after transplant, we conducted a retrospective cohort study of all adult patients who underwent AlloHCT at Duke from June 2002 - Feb 2016 (n=997). HHV6 viral loads were checked weekly for the first 90 days after umbilical cord blood and haploidentical transplants, and as clinically indicated (e.g. cytopenias, encephalopathy) in others. Foscarnet treatment for HHV6 viremia was given at the physician's discretion. Data were abstracted with a web-based clinical research query tool and manual chart review. Estimated glomerular filtration rate (eGFR) was calculated with the CKD-EPI equation based on repeated measures of serum creatinine (Cr) values at baseline, 90 days (n=839), 6 months (n=720), and 12 months (n=491) after transplant. Acute Kidney Injury (AKI) and Acute Kidney Failure (AKF) were defined as 2 and 3x baseline Cr, or >50% and >75% decrease in eGFR, respectively. Multivariate logistic regression was used to estimate the association of foscarnet exposure on the probability of >30% decline in eGFR at 90 days, 6 months, and 12 months after adjustment for confounders.Results: Of the 997 patients included in the study, 45% (n=448) were treated with foscarnet. Patients treated with foscarnet were slightly older (median age 52yrs vs. 49yrs), less likely to receive myeloablative conditioning, and more likely to be CMV positive, receive an alternative donor graft (umbilical cord blood or haploidentical), and experience acute GvHD. The most frequent indications for treatment were CMV (n=257, 57.4%) and HHV6 (n=140, 31.3%). In the first 90 days post-transplant, when most patients were treated with foscarnet, patients exposed vs. unexposed had similar rates of AKI/AKF: AKI 59.2% vs. 59.2%; p=0.99; AKF 26.1% vs. 27.3%; p=0.67. There was no difference in eGFR at 90 days, but patients treated with foscarnet had significantly lower eGFRs at 6 months and 12 months (Figure 1). There was a significant difference in the decline in eGFR from baseline to 12 months: median -29.1 (mL/min/1.73m2) (interquartile range (IQR) -50.8 to -10.7) vs. -22.2 (-37.4 to -7.4); p=0.002. After adjustment for age, race, acute and chronic GVHD, conditioning regimen, donor type, treatment with alemtuzumab, and HHV6 status, patients treated with foscarnet were more likely to experience a >30% decrease in eGFR from baseline to 12 months compared to those who were not (Odds Ratio 1.8 (95% CI 1.11-2.93); p=0.02). In this multivariate model, acute and chronic GVHD were not significant predictors of eGFR decline at 12 months. Unadjusted median survival was 11.9 months (95% CI; 10.1-14.0 months) and 20.8 months (95% CI; 15.8-25.4 months) for patients treated vs. not treated with foscarnet, respectively (p<0.001).Conclusion: Foscarnet use post AlloHCT had a profound impact on long-term renal function independent of other transplant-related factors. As declines of >30% in eGFR are strongly associated with a 10-year risk of end-stage renal disease and mortality in >60% and 50% of patients in the general population, respectively, (Coresh, et al. JAMA 2014), this information should be considered as one weighs the risks vs. benefits of treating HHV6 viremia following AlloHCT. DisclosuresHorwitz:Gamida Cell: Research Funding.

2569. High Incidence of Enterovirus, HHV6, Parechovirus and Adenovirus Blood Viremia in Children 0 to 3 Years Old Presenting With Fever Without Source

BackgroundFever without source (FWS) is defined as a fever in which an extensive history and clinical examination fail to identify a cause. Although the vast majority of children with FWS have a self-limited viral infection, up to 10–25% have a serious bacterial infection (SBI). Therefore, many children require invasive diagnostic tests, hospital admission, and empirical administration of broad-spectrum antibiotics. The aim of this study was to assess the respective role of Human enterovirus (HEV), human parechovirus (HPeV), adenovirus (ADV) and herpesvirus type 6 (HHV6) viremia in children <3 years old presenting with FWS.MethodsProspective monocentric diagnostic study. Between November 2015 to December 2017, children <3 year olds with FWS had, in addition to the standardized institutional work-up for FWS, plasma tested by real-time (reverse-transcription) polymerase chain reaction (PCR) for ADV, HHV6, HEV, and HPeV. Specimens with cycle threshold values <40 were considered positive. Quantification was performed on positive specimens for HEV, ADV, and HHV6 specimens when volume permitted.ResultsOne hundred thirty-five patients had plasma PCR for ADV, HHV6, HEV, and HPeV. Male:female ratio was 1.45:1 and median age was 2.4 months (interquartile range 1.3–9.7). Among those, 47/135 (34.8%) had at least 1 virus detected in the plasma. More specifically, HEV was detected in 19 patients (14.1%), HHV6 in 15 (11.1%), HPeV in 8 (5.9%), and ADV in 7 (5.2%). Co-infection with 2 viruses was detected in 2 patients (ADV/HEV and ADV/HPeV). No patient with positive plasma PCR had a positive blood or CSF culture. Two patients with positive plasma PCR fulfilled American Academy of Pediatrics criteria for urinary tract infection. The first was HEV+ in plasma and CSF, midstream urine was positive for leukocytes and grew E. coli 106 CFU/mL, whereas the second was HHV6+ in plasma and catheter urine was positive leukocytes/nitrites and grew P. mirabilis 105 CFU/mL.ConclusionThis epidemiological study highlights the frequent detection of active enteroviral, adenoviral, and HHV6 infections in plasma of children with FWS. Virus–virus and virus–bacteria co-infections are rare. Further studies are needed to establish causality between FWS and viremia.Disclosures A. G. L’Huillier, Gertrude Von Meissner foundation: Investigator, Research grant. Ernst and Lucie Schmidheiny foundation: Investigator, Research grant. Research and Development Grant, Geneva University Hospitals: Investigator, Research grant. L. Kaiser, Swiss National Funds: Investigator, Research grant. A. Galetto-Lacour, Gertrude Von Meissner foundation: Investigator, Research grant. Ernst and Lucie Schmidheiny foundation: Investigator, Research grant. Research and Development Grant, Geneva University Hospitals: Investigator, Research grant.

Human herpesvirus 6 viremia affects T-cell reconstitution after allogeneic hematopoietic stem cell transplantation

AbstractHuman herpesvirus 6 (HHV6) viremia is a common cause of morbidity following allogeneic hematopoietic cell transplantation (HCT). We previously associated T-cell reconstitution with HHV6 viremia. Here, we investigated whether HHV6 viremia affects T-cell reconstitution after HCT in a time-dependent retrospective analysis. We included 273 pediatric patients (0.1-22.7 years; median follow-up, 58 months) receiving a first HCT between 2004 and 2014. HHV6 was screened weekly in plasma via polymerase chain reaction and occurred in 79 patients (29%) at a median time of 19 days after transplant. Main outcome of interest was immune reconstitution (IR) (CD3/CD4/CD8 T cells), measured biweekly until 12 weeks and monthly thereafter. Cox proportional-hazard models were used with IR and HHV6 as time-dependent variables in multivariate analysis with serotherapy in conditioning, graft source, graft-versus-host disease, age, and other viruses (Epstein-Barr virus, cytomegalovirus, and adenovirus) as covariates. Only patients with very high HHV6 viremia (>105 copies/mL) showed hampered CD4+ (hazard ratio [HR], 0.913; 95% confidence interval [CI], 0.892-0.934; P < .001) and CD8+ (HR, 0.912; 95% CI, 0.891-0.933; P < .001) reconstitution in comparison with patients without HHV6, from ∼6 months after HCT. Especially naïve CD4+ IR was affected (P = .028) but not effector memory CD4+ IR (P = .33). Interestingly, T-cell reconstitution was improved in patients treated with antivirals (HR, 1.572; 95% CI, 1.463-1.690; P < .001). These findings suggest that HHV6 viremia affects late but not early T-cell reconstitution.

Low Dose Antithymocyte Globulin (ATG) for Graft-Versus-Host Disease (GVHD) Prophylaxis

ATG appears to reduce the incidence of acute and chronic GVHD after allogeneic hematopoietic stem cell transplantation (HSCT). Potential risks of this strategy include viral reactivation, delayed immune recovery and increased relapse rates. The ideal dosing of rabbit ATG in this context is largely unknown. We therefore hypothesized that low dose ATG would reduce the incidence of acute and chronic GVHD in matched unrelated donor (MUD) transplants without compromising survival and relapse rate. A retrospective analysis was performed of a cohort of high-risk MUD HSCT recipients treated since year 2013, when our practice changed to include rabbit ATG at 3 mg/Kg for all MUD transplants at the Case Medical Center in Cleveland, Ohio. Herein we present the results of this analysis.Methods. 58 MUD transplants were performed between years 2013 and 2016, with a median follow up of 262 days post-transplant. All donor-recipient pairs were matched by high resolution HLA typing at HLA-A, -B, -C, and DRB1, (8/8 matches) with the exception of 4 pairs (7/8 matches. Median age was 56 years (range, 53-64). Underlying diagnoses were AML (n=26), MDS (13), CML (n=5), NHL (n=9), Hodgkin's lymphoma (n=2), Multiple Myeloma (n=1) and myeloproliferative disorders (n=2). Preparative regimens were ablative in 26 cases (45 %) and of reduced intensity in 31 cases (55 %). Graft source was bone marrow (n=5) and peripheral blood (n=53). All but 4 pts received GVHD prophylaxis with tacrolimus, and mini-methotrexate (5 mg/m2 on days +1, +3, +6 and +11), in addition to rabbit ATG 3 mg/Kg divided in two doses on days -2 and -1 pre HSCT. Cytomegalovirus (CMV), Epstein-Barr virus (EBV), and Human Herpes Virus (HHV6) PCR were conducted thrice weekly during the first 100 days after HSCT.Results. The 100-day cumulative incidence of grade II-IV acute GVHD was 41% (95% CI: 29-57; Fig 1), while the cumulative incidence of grade III-IV acute GVHD was 18% (95% CI: 9-35; Fig 2). 1-year cumulative incidence of chronic GVHD was 27% (95% CI: 17-42; Fig 3). At 180 days, the incidence of CMV viremia (defined as more than 1,000 copies/mL) was 25% (95% CI: 16-40), while the incidence of EBV and of HHV6 viremia was 35% (95% CI: 24-51) and 14% (95% CI: 8-27), respectively. There was no instance of EBV-related lymphoproliferative disorder.3-year overall survival estimate is 48% (95% CI: 34-62). Cumulative incidence of Non-relapse mortality (NRM) and relapse at 1 year was 21% (95% CI: 12-37) and 44% (95% CI: 29-65), respectively.Conclusion. Our study shows that low dose rabbit ATG appears to reduce chronic GVHD rates without a major effect on acute GVHD incidence. CMV, EBV and HHV6 reactivation did occur, albeit at rates that are somewhat lower than those historically reported, without EBV-driven lymphoproliferative disorder. [Display omitted] [Display omitted] [Display omitted] DisclosuresCaimi:Genentech: Speakers Bureau; Roche: Research Funding; Novartis: Consultancy; Gilead: Consultancy.

Human herpesvirus-6 viremia is not associated with poor clinical outcomes in children following allogeneic hematopoietic cell transplantation.

HHV-6 is an evolving pathogen in the field of AlloHCT. However, the impact of HHV-6 on AlloHCT outcomes remains to be elucidated. We studied the incidence and clinical impact of HHV-6 viremia in children following AlloHCT. One hundred consecutive children were monitored weekly by plasma PCR for the first 180 days following AlloHCT for HHV-6, CMV, EBV, and ADV. HHV-6 viremia was defined as plasma PCR >1000 viral copies/mL. The median age was nine yr. Following AlloHCT, 19% (95% CI 11.3-26.7%) of patients had HHV-6 viremia, with the highest incidence of reactivation (14/19, 73%) occurring during day +15-day +98. The proportion of platelet engraftment by day +180 was lower in patients with HHV-6 viremia (58%) than in those without HHV-6 viremia (82%), p = 0.028. Delay in neutrophil and platelet engraftment was not associated with HHV-6 viremia in multivariate analysis. Similarly, HHV-6 viremia was not associated with TRM in multivariate analysis (p = 0.15). In summary, HHV-6 viremia is prevalent in pediatric AlloHCT recipients. Based on our study results, we recommend that HHV-6 PCR should only be performed on clinical suspicion.

Utility of a monitoring strategy for human herpesviruses 6 and 7 viremia after liver transplantation: a randomized clinical trial.

Reactivation of human herpesvirus (HHV)-6 and HHV-7 has been linked to various posttransplant adverse events through immunomodulatory effects. The potential utility of monitoring for HHV-6 and HHV-7 viremia remains unclear. In this clinical trial, 129 liver transplant recipients were randomized to be monitored in real-time for HHV-6 and HHV-7 viremia by polymerase chain reaction at regular intervals from 0 to 12 weeks after transplantation ("monitoring" group) or to undergo usual care ("no-monitoring" group). Therapeutic intervention for a positive polymerase chain reaction result included reduction in immunosuppression and preemptive antiviral therapy, at the discretion of the attending team. The primary outcome was a composite of adverse events indirectly attributable to viral reactivation (including opportunistic infection, graft rejection and severe hepatitis C virus recurrence). In the "monitoring" group, HHV-6 and HHV-7 viremia occurred in 23 of 64 patients (35.9%) and 21 of 64 patients (32.8%) patients, respectively. We found no cases of symptomatic HHV-6 and HHV-7 disease. Some therapeutic interventions were performed in 59.1% of viremic episodes. There were no differences in cumulative incidence of the primary outcome between the "monitoring" and "no-monitoring" groups at 1 year (58.7% vs. 52.3%; odds ratio, 0.77; 95% confidence interval, 0.38-1.55) or at 5 years after transplantation (79.0% vs. 70.3%; odds ratio, 0.63; 95% confidence interval, 0.28-1.42). However, we found a trend toward a lower incidence of graft rejection at year 1 in the "monitoring" group (30.2% vs. 44.6%; P=0.091). In this first trial, no benefit could be demonstrated from routine monitoring of HHV-6 and HHV-7 viremia in graft or patient outcome after liver transplantation.

Quantitative Assessment of T Cell Repertoire Recovery after Double Unit Cord Blood Transplantation Demonstrates Early T Cell Diversity and Correlation Between CMV Reactivation and CD8 Clonal Domimance

Introduction: Double-unit cord blood transplantation (DCBT) is a viable therapy for adults with high-risk hematologic malignancies who lack an adult donor. However, lack of transfer of memory T cells in the graft is associated with an increased risk of viral infections. To study immune reconstitution, we recently described a novel method that combines 5′ rapid amplification of complementary DNA ends (RACE) PCR and deep sequencing to quantify T cell receptor (TCR) diversity after allogeneic hematopoietic stem cell transplant (van Heijst, Nat Med 2013). In that study, we showed that recipients of DCBT recover TCR diversity comparable to healthy donors by 12 months. We now report results of a prospective analysis of CD4+ and CD8+ T cell repertoire recovery in DCBT recipients and correlation with clinical outcomes.Methods: We prospectively collected samples from 33 DCBT recipients. The median age was 45 years (range 26-71), 18 (55%) were CMV seropositive, and the majority (n = 17, 52%) had non-European ancestry. Diagnoses included 20 (61%) acute leukemias and 13 (39%) lymphomas. Conditioning was myeloablative (n=1, 3%), reduced intensity (n=28, 85%), or non-myeloablative (n=4, 12%), and all patients received GVHD prophylaxis with cyclosporine-A and mycophenolate mofetil and no ATG. Patients received double-unit CB grafts (4-6/6 HLA-A,-B antigen, -DRB1 allele donor-recipient matched); this was supplemented with haploidentical CD34-selected PBSC in 18 patients. The 66 units had a median donor-recipient HLA-allele match of 6/8 (range 3-8). Infused total nucleated cell doses were 2.3 (1.7-3.3) and 1.9 (1.3-2.5) for the larger and smaller units, respectively. Samples were collected from the DCB grafts, recipient day+21 bone marrow, and peripheral blood at days +30, 60, 90, 120, 180 and 365 post-transplant. TCR-β sequences from each sample were amplified and sequenced using the Illumina/MiSeq sequencing platform after isolation of CD4+ and CD8+ T cells. TCR abundances were assessed at the level of clonotype and TCR diversity was calculated using inverse Simpson index.Results: Of the 33 patients, long-term samples were obtained in 25 patients, short-term samples (≤ day 100) in 6 patients who died early after DCBT, and no samples other than the graft for 2 patients. The remainder of the results focuses on 25 patients with complete samples. As previously shown, there is a 1-2-log increased diversity in CD4+ vs. CD8+ T cells (Figure). Furthermore, median CD4+ steady-state diversity is achieved early by day 60. In contrast, there is a higher rate of clonal dominance in CD8+ compared to CD4+ T cells (24/25 vs. 11/25, p=0.0001 by Fisher test). Several patterns of clonal dominance were observed, including two main patterns in CD8+ T cells. In 7/24 patients, clonal dominance is established by day 60 and persists throughout, whereas in 12/24 patients, clonal dominance fluctuates throughout follow-up. In CD4 +T cells, where less dominance is observed, a similar distribution is seen, though prolonged clonal dominance is rare. Interestingly, some of the dominant clones can be detected in the graft and are present in the day 21 marrow sample. Persistent clonal dominance in CD8+ T cells was seen 6/9 patients with CMV reactivation, whereas ongoing fluctuation was seen in 9/12 patients without CMV reactivation. In 2 patients with fluctuating clones who reactivated CMV, 1 had low level and the other a late viremia. In contrast, no link to a specific pattern was observed in patients with HHV6 viremia or acute GVHD. Finally, when we assessed similarity in clonal distribution between time points, there was more similarity in CD8+ than CD4+ T cells.Conclusions: This novel deep TCR repertoire sequencing provides a quantitative picture of T cell recovery after DCBT and supports the following: 1) separate analysis of CD4+ and CD8+ T cell populations is critical given different patterns of recovery in T cell subsets; 2) there is significant turnover in CD4+ clones but with overall limited dominance, whereas there is less turnover in CD8+ clones; 3) although the grafts contain predominantly naïve T cells, the clonal evolution of CD8+ T cells strongly suggests generation of virus-specific T cells that control viral infection; and 4) CMV appears to be an important driver of CD8+ T cell clonal expansion after CBT. Ongoing analyses are correlating immune recovery with cord blood unit dominance as well as the biology of GVHD and relapse. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.