ALBERT

Description: Introduction and aim of study. Cyclosporin A (CsA) is commonly used as prophylaxis against Graft versus Host disease (GVHD) after allogeneic haematopoietic stem cell transplantation (SCT). Therapeutic drug monitoring is necessary because of its unpredictable absorption and narrow therapeutic window. Usually dose adjustments are based on trough levels, although these correlate poorly with CsA systemic exposure in adults. The aim of this study was to investigate intravenous and oral CsA pharmacokinetics in children after SCT and to develop a limited sampling strategy in order to determine CsA systemic exposure. Methods. Pharmacokinetics was investigated in children, aged 1.8 to 16.1 yrs, 2 to 43 days after stem cell infusion (median: 25 days), after intravenous or oral administration of CsA in, respectively, 9 and 8 children. Parameter estimation was performed using nonlinear mixed effect modeling as implemented in the NONMEM program. Results and conclusions. Pharmacokinetics were described adequately with a two-compartment model with lag time (population estimates: Cl=10.5 l/h; Vc=15.5 L; Vp=60.6L; t ½ absorption=1.01 h, Tlag=0.6 h). Combination of Cthrough and a Bayesian fitting procedure with the pharmacokinetic model can adequately estimate the systemic exposure to CsA (r2=0.90, Figure 1). The estimation of actual AUC improves when more concentration time-points are used. No relation between body weight and clearance was found (Figure 2). Based on these data, CsA should not be dosed per kilogram body weight. A regimen with a fixed dose for all, adjusted on through levels in combination with the described pharmacokinetic model, may be more appropriate. (open circles: oral administration; closed circles: intravenous administration) Figure Figure Figure Figure

Description: Introduction: Chronic granulomatous disease (CGD) is a rare primary immunodeficiency disease characterized by impairment of the phagocyte NADPH-oxidase complex, resulting in deficient microbial killing and life-threatening bacterial and fungal infections. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only curative approach, but it can be complicated by graft failure, graft versus-host disease (GvHD) and transplant-related mortality (TRM). In order to define prognostic risk factors in this setting, the IEWP of the EBMT performed a large retrospective registry study on 600 pediatric and adult patients with CGD undergoing allo-HSCT. Patients and Methods: We analyzed the outcome of patients with CGD who received allo-HSCT in EBMT centers between 1993 and 2017. The main end-points of the study were overall survival (OS) and event-free survival (EFS; events were death and primary or secondary engraftment failure) according to patient's age, donor type, stem cell source and conditioning regimen. One patient died before allo-HSCT and was excluded from analysis. Results: We studied 536 children (aged 〈 18 years) and 63 adults (aged ≥ 18 years) affected by CGD. The median follow-up was 45.37 months (IQR 15.8-81.8). Genetic results were available for 307 patients: inheritance was X-linked (75%) or autosomal recessive (25%). Median age at transplant was 7.2 years (range: 0.12-48.56). Conditioning regimen was Busulfan/Fludarabine (n=244; 41%), Busulfan/Cyclophosphamide (n=104; 17%), Treosulfan/Fludarabine (n=76; 13%), Treosulfan/Fludarabine/Thiotepa (n=52; 9%) or other drug combinations (n=123; 20%). Donors were human leukocyte antigen (HLA) matched related (MFD, 10/10; n=211, 40%), matched unrelated (MUD, 10/10 or 6/6 in UCB; n=201; 38%), mismatched related (MMFD, ≥ 9/10; n= 27; 5%) or mismatched unrelated (MMUD, ≥ 9/10 or 5/6 in UCB; n= 83; 16%). Stem cell source was bone marrow (BM; n=408; 69%), peripheral blood (PB; n=153; 26%) or umbilical cord blood (UCB; n=27; 5%). Donor engraftment occurred in 516 evaluable patients (88%), while primary or secondary engraftment failure occurred in 68 patients (12%). Seventy-nine patients (13%) died after allo-HSCT. The 2 year Kaplan-Meier estimate of OS and EFS were 87.1% (95% CI, 84.2-89.9) and 77.8% (95% CI, 74.2-81.4), respectively (Fig A). The 2-year cumulative incidence of grade II-IV acute GvHD, chronic GvHD and extensive chronic GvHD was 18.6% (95%, 15.1-22.2), 16.2 % (95%, 18.8-19.7) and 5.5% (95%, 3.4-7.7), respectively. A univariate cox model with spline term demonstrated that older age at transplant was associated with an increased risk of death (p=0.002). Children undergoing allo-HSCT had a superior 2y OS (88.1%; 95% CI 85.2-91.0), compared to adults (78.2%; 95% CI, 67.7-88.7), p=0.03 (Fig B). Patients undergoing allo-HSCT from a MFD had a superior EFS (86.5%; 95% CI 81.5-91.4) compared to MUD (73.3%; 95% CI 66.7-79.9), MMUD (78.2%; 95% CI 69-87.5) and MMFD (59.7; 95% CI 40.4-79.1), p〈 0.001 (Fig C). Patients receiving BM grafts had superior 2y EFS (81.0%; 95% CI 76.9-85.1) compared to PB (72.5%; 95% CI 64.7-80.4) and UCB (66.7%; 95% CI 48.9-84.4), p=0.04. The pattern of disease inheritance and the choice of conditioning regimen didn't have an impact on outcome (Fig D). Fifty-three patients with graft failure underwent a second allo-HSCT and the 2y OS in this group was 82.1% (95% CI, 71.5-92.7). Year of transplantation didn't have an influence on outcome. Conclusion: This is the largest study describing the outcome of allo-HSCT in children and adults affected by CGD. We demonstrate an excellent outcome, with a low incidence of graft failure, TRM and GvHD. Older patients with CGD have reduced survival after allo-HSCT, indicating that transplant should be considered at a younger age. The use of a MMFD is associated with poorer outcome; indication to transplant in this setting should be carefully evaluated by the treating physicians. Disclosures Chiesa: Bluebird Bio: Consultancy; Gilead: Consultancy. Kalwak:medac: Other: travel grants; Sanofi: Other: travel grants. Sykora:Aventis-Behring: Research Funding; medac: Research Funding. Locatelli:Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria; bluebird bio: Consultancy; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Wynn:Orchard SAB: Membership on an entity's Board of Directors or advisory committees; Orchard Therapeutics: Equity Ownership; Chimerix: Research Funding; Genzyme: Honoraria; Bluebird Bio: Consultancy; Orchard Therapeutics: Consultancy; Chimerix: Consultancy. Zecca:Chimerix: Honoraria. Veys:Pfizer: Honoraria; Servier: Research Funding; Novartis: Honoraria. Slatter:Medac: Other: Travel assistance.

Description: Hematopoietic stem cell transplant (HSCT) from an HLA identical sibling is a well-established curative therapy for sickle cell disease (SCD). HSCT from an unrelated donor is a treatment option, but the likelihood of finding a donor varies according to ethnicity and results are still limited. HLA haploidentical relatives can be alternatively used but, to date, only small series of patients have been described. We report outcomes of patients (pts) transplanted with related haploidentical (Haplo) or unrelated (UD) donors grafts and reported to EBMT/EUROCORD databases. Sixty four pts transplanted in 22 EBMT centers between 1991 and 2017 were retrospectively analyzed. Pts were described according to the donor type: haploidentical (n=40) and unrelated (n=24) [adult UD n=19; cord blood (CB) n=5]. The objective of the study was to describe alternative donor transplants for SCD in Europe without performing comparison analyses due to the size and heterogeneity of the groups. Primary endpoint was 3-year overall survival (OS). Median follow-up (FU) was 28 months (range: 1.6-156) [29.5 months (range: 2.1 - 133.5) for Haplo and 24.6 (range: 1.6 - 156) for UD]. Median age at HSCT was 14.2 years (range: 3-31.7) in Haplo and 11.8 (range: 2.1-42.8) in UD, with a predominance of children (

Description: Human Adenovirus (HAdV) reactivation is a frequent and potentially fatal complication in pediatric allogeneic stem cell transplantation (HSCT) recipients, especially after in vivo T-cell depletion. Patients with HAdV reactivations are generally treated with the antiviral agent Cidofovir (CDV), a monophosphate nucleotide analogue. Studies reporting effectiveness of CDV therapy are mostly incomplete due to lack of data on the immune status of the patients. Here, we report the relationship between the effectiveness of CDV therapy and lymphocyte reconstitution as well as the acute and chronic nephrotoxicity of CDV in the setting of pediatric .infections after pediatric HSCT. Between 2003 and 2012, 321 children received 363 allogeneic transplantations in our pediatric HSCT center. HAdV reactivations were monitored by weekly plasma HAdV DNA RQ-PCR. Disseminated infections, defined as two consecutive PCR values above 103 (3 log ) copies / mL occurred in 40 patients (12 %). 30 patients were treated with CDV for infections with an HAdV load ≥ 3 log at start of therapy. In 27 patients, sufficient data were available to evaluate the effectiveness of CDV. Cidofovir was administered IV 3x / week at 1 mg / kg. Prehydration and Probenecid were used to reduce the risk of nephrotoxicity. Patient were median 4.5 (0.5 - 18) years of age and 26 of 27 patients received in vivo T-cell depletion. CDV therapy was initiated median 28 (1 - 121) days after HSCT while the median treatment duration was 15 (1 - 99) days. At start of CDV treatment, the HAdV load was median 4.2 log (range 3.1 log - 6.5 log) copies / mL. Response was evaluated after 14 days of CDV therapy. A ≥ 10x (1 log) reduction of HAdV load was measured in 10 of 27 evaluable patients (37%) while 13 patients (48%) showed a stabilization of HAdV load. CDV treatment failed in 4 patients (15 %), as define by a 1 log increase of HAdV load despite uninterrupted CDV therapy. In 23 patients with a reduction or stabilization of the HAdV load, lymphocyte numbers increased strongly in the two weeks after initiation of CDV treatment (median 130 to 608 lymphocytes / µL, p 〈 0.0001, Wilcoxon signed-rank test). This increase was caused by reconstitution of NK cells (n = 5), T-cells (n = 4) or both (n = 12). In only 2 patients with a stabilization of HAdV load, no concomitant reconstitution of NK or T-cells was observed. Ultimately, 17 patients (63 %) cleared the virus 5 - 89 (median 33) days after the initiation of CDV therapy. The moment of HAdV clearance was strongly correlated to the first day the T-lymphocytes reached 50 cells/ µl (R2 = 0.79, p 〈 0.0001, linear regression analysis). 7 patients died of progressive HAdV viremia with multi-organ failure (MOF) at 20 - 154 (median 51) days after initiation of CDV therapy. Three patients were not evaluable as they died of another cause (n=2) or were lost to follow up (n=1) without clearance of the virus. For the analysis of CDV nephrotoxicity, 3 patients with HAdV related MOF during CDV therapy were excluded, leaving 24 patients. In 4 patients (17%), CDV therapy had to be discontinued because of acute glomerular failure, which invariably occurred within the first 2 weeks of treatment. Tubular kidney failure, defined by the need for suppletion of phosphate, magnesium or bicarbonate, was observed in 17 of 24 patients (71%). Kidney failure was transient in the majority of patients. After 1 year, 1 of 12 survivors (8 %) had chronic glomerular and tubular kidney failure that could not be explained by nephrotoxic co-medication. In 9 additional HSCT recipients who received 〉 7 days of CDV therapy for non-disseminated HAdV infections, 1 of 8 surviving patients (13 %) had chronic kidney failure that was unlikely to be caused by other nephrotoxic medication. In conclusion, a reduction of HAdV load in the first 2 weeks of therapy was always accompanied by lymphocyte recovery while Cidofovir could not prevent further dissemination in 4 of 27 patients. In most patients with a stabilization of the viremia, this could be attributed to both CDV as well as T- or NK-cell reconstitution whereas in only 2 patients (7%), the HAdV load stabilized in the absence of lymphocyte recovery. These data suggest that CDV possibly plays a role in the stabilization of HAdV viremia in the time pending T-cell recovery. In view of the considerable toxicity profile, a multicenter randomized clinical trial is warranted to establish efficacy of CDV treatment for disseminated HAdV infections after pediatric HSCT. Disclosures: Off Label Use: The antiviral agent Cidofovir (CDV), a monophosphate nucleotide analogue, is widely used off-label for the treatment of disseminated Human Adenovirus infections after Pediatric Hematopoietic Stem Cell Tansplantation.

Description: Background Cytomegalovirus (CMV) reactivation frequently occurs during early immune reconstitution after hematopoietic stem cell transplantation (HSCT). Although CMV is associated with accelerated immune ageing in healthy individuals, the impact of early CMV reactivation on T-cell immunity long term post HSCT is unknown. In this study, we report the impact of early CMV reactivations on the reconstitution and composition of the T-lymphocyte compartment one to two year after HSCT in a large cohort of pediatric HSCT recipients. Methods We analyzed the lymphocyte compartment one and two year after transplantation in 131 consecutive (2002 - 2011) pediatric HSCT recipients that were eligible for follow up one year post HSCT. Viral infections were routinely monitored by weekly serum viral DNA PCR in the first 100 days. Peripheral blood mononuclear cells were routinely analyzed by multicolor flow cytometry. Six patients with early CMV reactivation and an HLA type for which CMV-tetramers were available were analyzed for the presence and phenotype of CMV-specific CD8+ T-lymphocytes. Results One year post HSCT, patients with early CMV reactivation (n = 46, PCR ≥ 1x ≥ 200 copies / mL) had significantly higher lymphocyte counts compared to patients without CMV reactivation (n = 85, PCR always 〈 200 copies / mL). This could be attributed to a significant increase of CD3+ T-lymphocytes while NK- and B-cell numbers did not differ. Within the T-cell compartment, a three-fold expansion of CD8+ T-cells (median 1323 vs. 424 cells / μL, p 〈 0.0001, Mann-Whitney) and an increase in gamma-delta T-cells (median 104 vs. 47 cells / μL, p = 0.0005) was observed, while absolute numbers of CD4+ T-cells did not differ between the groups. This effect was not observed in relation to Epstein-Barr virus (EBV) or Adenovirus (HAdV) reactivation. In multivariate analysis, CD8+ T-cell numbers one year post HSCT were highly influenced by CMV reactivation (p 〈 0.0001, linear regression) but not affected by pre-transplant CMV serostatus of donor (p = 0.22) or recipient (p = 0.14). In a representative subcohort (n = 53, 2008 - 2010), we more closely analyzed the differentiation stages of T-cells based on expression of CD45RA and CCR7. In both the CD4+ and CD8+T-cell subset, the proportion of Effector Memory (EM) and EMRA T-cells was enlarged in patients with (n = 18) compared to patients without (n = 35) early CMV reactivation. In the CD8+ T-cell compartment, this was caused by a major expansion of CD8+ EM and EMRA T-cells (median 485 vs. 141, p 〈 0.0001 and 509 vs. 114 cells / μL, p 〈 0.0001, Figure A), while the Naive (median 105 vs. 169 cells / μL, p = 0.17) and Central Memory (CM) compartment did not differ. In the CD4+ compartment, a non-significant increase of EM and EMRA cells was accompanied by a non-significant decrease of N and CM cells. CMV-specific CD8+ T-cells (median 4.1, range 0.3 - 25.6% of CD8+ T-cells) were detected within the EM and EMRA compartment. Two year after HSCT, data were available for 76 patients. Both in patients with (lymphocyte subsets: n = 34 / T-cell differentiation: n = 12) and without (n = 42 / n = 19) early CMV reactivation, a further reconstitution of CD4+ and CD8+ T-cells was observed, reflected by an expansion of Naive and CM cells (Figure B). However, the total number of CD8+ T-cells decreased in patients with early CMV reactivation, caused by a contraction of late differentiated CD8+ EM and EMRA cells (median 825 to 618, p = 0.0068 and 555 to 378 cells / μL, p = 0.0342, Wilcoxon). Conclusion Early CMV reactivation leaves a virus-specific and dynamic imprint on the reconstituting immune system 1 and 2 year after HSCT. The marked expansion of CD8 + EM and EMRA T-cells was not seen in patients with early EBV or HAdV reactivation and did not compromise the reconstitution of the Naive and CM compartment available to respond to neo- and recall antigens. Pediatric HSCT recipients differed from solid organ transplantation recipients in which CMV has been correlated to an accelerated and ongoing accumulation of late differentiated T-cells. The dynamic contraction of the CD8+ late differentiated memory T-cell compartment in the second year after HSCT implies that an ongoing process of immune-regulation and further reconstitution is modeling the cellular immune system after discontinuation of immunosuppressive medication. Disclosures: No relevant conflicts of interest to declare.

Description: Haploidentical hematopoietic stem-cell transplantation (HSCT) is associated with an increased risk of graft failure. Adult bone marrow–derived mesenchymal stromal cells (MSCs) have been shown to support in vivo normal hematopoiesis and to display potent immune suppressive effects. We cotransplanted donor MSCs in 14 children undergoing transplantation of HLA-disparate CD34+ cells from a relative. While we observed a graft failure rate of 15% in 47 historic controls, all patients given MSCs showed sustained hematopoietic engraftment without any adverse reaction. In particular, children given MSCs did not experience more infections compared with controls. These data suggest that MSCs, possibly thanks to their potent immunosuppressive effect on alloreactive host T lymphocytes escaping the preparative regimen, reduce the risk of graft failure in haploidentical HSC transplant recipients.

Description: Christina Peters, Petr Sedlacek, Jean Hugues Dalle, Stelios Graphakos, Antonio Campos, Akif Yesilipek, Jacek Wachowiak, Arjan Lankester, Andrea Pession, Amir Ali Hamidieh, Marianne Ifversen, Jochen Büchner, Gergely Krivan, Franca Fagioli, Arnaud Dalissier; Myriam Labopin; Peter Bader on behalf of the EBMT Pediatric Diseases Working Party Most children with acute lymphoblastic leukemia (ALL) with indication for allogeneic hematopoietic stem cell transplantation (HSCT) receive myeloablative conditioning with a total body irradiation (TBI)-containing regimen. To investigate the outcomes of patients (pts) who did not undergo TBI, we performed a retrospective registry based study on children below 18 years who received a myeloablative chemo-conditioning for a first allogeneic HSCT from different donors between 2000 and 2012. In this analysis, only chemotherapeutic regimens with more than 30 applications were included. In total, 732 pts were included: 313 pts who received bone marrow (BM) or peripheral blood stem cells (PBSC) in 1st CR, 247 pts with BM/PBSC transplantation in CR2, 85 pts and 52 pts who received umbilical cord blood (CB) in 1st or 2nd CR, respectively. The most commonly applied myeloablative chemo-combinations were: Busulfan (Bu)/Cyclophosphamide (Cy) (n=202), Bu/Cy/Etoposide (VP) (n=189), Bu/Cy/Melphalan (Mel) (n=93), Bu/AraC/Mel (n=80), Bu/Fludarabine (Flu)/Thiotepa (Thio) (n=62), Bu/Cy/Thio (n=53, Bu/Cy/Thio (n=53), and Bu/Flu (n=53). 313 pts received either BM or PBSC in CR1 with a median follow up of 26 months (1-156) and we compared Bu/Cy/VP vs the other chemo-conditioning regimens. The Bu/Cy/VP cohort had a longer follow up (med 37 vs. 20 months, p=0.002), pts were younger (med 3,6 vs. 6,5 years, p=0.003) and the median year of transplant was earlier (med 2009 vs. 2010, p=0.03). Donor type, CMV match, gender match, stem cell were comparable. In univariate analysis, conditioning with Bu/Cy/VP was better than all other combinations: relapse incidence (RI) 21% vs 32% (p=0.05), leukemia-free survival (LFS) 72 vs 54% (p=0.004), overall survival (OS) 79 vs 68% (p=0.03) and chronic GVHD (cGVHD) 9% vs 19% (p=0.014). Engraftment and incidence and severity of acute GVHD were similar and non- relapse mortality (NRM) was 7% vs 13% (p=0.10). Other significant influencing factors were: interval between diagnosis and transplantation below or beyond 208 days (NRM 6% vs 16%, p=0.015), donor sibling vs other (RI 35% vs 23%, p=0.01, NRM 5% vs 16%, p=0.001) and in vivo T cell depletion (TCD) vs no TCD (RI 35% vs. 19%, p=0.003; NRM 20% vs 4%, p=0.0001). In the cox model, conditioning type (Bu/CY/VP vs other), age, year of transplantation, interval from diagnosis to transplant, donor type, stem cell source and in vivo TCD were evaluated. For LFS only BU/CY/VP was associated with better outcome (p=0.004, HR .52), RI was lower after Bu/Cy/VP (HR .54, p=0.02), NRM was higher in pts older than 4,6 years (p=0.02, HR 2,48) and after TCD HSCT (p=0.01, HR 9,13) and OS was best after Bu/Cy/VP (p=0.03, HR 0.57). We conclude that omission of TBI is feasible for children who undergo first allogeneic HSCT in first or second complete remission. The combination of busulfan, cyclophosphamide and etoposide resulted in better LFS and OS with less NRM and RI for children who received bone marrow or peripheral blood stem cells in CR1. These observations should be the basis for prospective trials in homogenous patient groups. Disclosures No relevant conflicts of interest to declare.