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Post-transplant Cyclophosphamide in Acute Leukemia Patients Receiving more than 5/10 HLA-Mismatched Allogeneic Hematopoietic Cell Transplantation from Related Donors: a Study on behalf of the ALWP of the EBMT
Wieczorek, M., Labopin, M., Castagna, L., Brissot, E., Socié, G., Raiola, A. M., Angelucci, E., Bermúdez Rodríguez, A., Yakoub-Agha, I., Aljurf, M., et al
American journal of hematology. 2022
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Should anti-thymocyte globulin be added in post-transplant cyclophosphamide based matched unrelated donor peripheral blood stem cell transplantation for acute myeloid leukemia? A study on behalf of the Acute Leukemia Working Party of the EBMT
Spyridonidis, A., Labopin, M., Brissot, E., Moiseev, I., Cornelissen, J., Choi, G., Ciceri, F., Vydra, J., Reményi, P., Rovira, M., et al
Bone marrow transplantation. 2022
Abstract
In this registry-based study which includes acute myeloid leukemia patients who underwent a matched unrelated donor allogeneic peripheral-blood stem cell transplantation in complete remission and received post-transplant cyclophosphamide (PTCY) as graft-versus-host disease (GvHD) prophylaxis, we compared 421 recipients without anti-thymocyte globulin (ATG) with 151 patients with ATG. The only significant differences between PTCY and PTCY + ATG cohorts were the median year of transplant and the follow-up period (2017 vs 2015 and 19.6 vs 31.1 months, respectively, p < 0.0001). Overall, 2-year survival was 69.9% vs 67.1% in PTCY and PTCY + ATG, respectively, with deaths related to relapse (39% vs 43.5%), infection (21.9% vs 23.9%) or GvHD (17.1% vs 17.4%) not differing between groups. On univariate comparison, a significantly lower rate of extensive chronic GvHD was found when ATG was added (9.9% vs 21%, p = 0.029), a finding which was not confirmed in the multivariate analysis. The Cox-model showed no difference between PTCY + ATG and PTCY alone with respect to acute and chronic GvHD of all grades, non-relapse mortality, relapse, leukemia-free survival, overall survival, and GvHD-free-relapse-free survival between study cohorts. Our results highlight that the addition of ATG in PTCY does not provide any extra benefit in terms of further GvHD reduction, better GRFS or better survival.
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ATG in HLA-matched, peripheral blood, hematopoietic cell transplantation in acute myeloid leukemia and myelodysplastic syndrome: a secondary analysis of a CIBMTR database
Arcuri, L. J., Kerbauy, M. N., Kerbauy, L. N., Santos, F. P. S., Ribeiro, A. A. F., Hamerschlak, N.
Transplantation and cellular therapy. 2022
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Editor's Choice
Abstract
BACKGROUND Peripheral blood stem cells (PBSC) are the preferred grafts for hematopoietic cell transplantation (HCT), according to the CIBMTR. Donor recovery is faster with PBSC harvest, but PBSC is associated with higher chronic graft-versus-host disease (GVHD) and poorer quality of life. Anti-T cell globulin (ATG) is polyclonal IgG from rabbits or horses immunized with human thymocytes or a human T-cell line which may reduce graft-versus-host disease in HCT and improve outcomes. OBJECTIVE The objective of this study was to analyze the impact of ATG in HLA-matched Related (MRD) and matched (HLA 8/8) unrelated donor (MUD) HCT. STUDY DESIGN We used a freely available CIBMTR database published online for secondary analyses. The database included patients ≥ 40 y/o who have undergone their first PBSC MRD or MUD HCT for acute myeloid leukemia or myelodysplastic syndrome with or without ATG between 2008 and 2017. Patients who received posttransplant cyclophosphamide or alemtuzumab were excluded. RESULTS Overall survival was not different with ATG (HR = 1.09, 95CI 1.00-1.19, p = 0.06) compared with no ATG. Relapse rate was higher with ATG (HR = 1.29, 95CI 1.17-1.43, p < 0.001) and NRM was lower with ATG (HR = 0.84, 95CI 0.72-0.98, p = 0.03). Grades II-IV acute GVHD was significantly lower with ATG (HR = 0.77, 95CI 0.69-0.87, p < 0.001) but not grades III-IV acute GVHD (HR = 0.85, 95CI 0.69-1.04, p = 0.11). Both chronic GVHD (HR = 0.54, 95CI 0.48-0.60, p < 0.001) and moderate/severe chronic GVHD (HR = 0.45, 95CI 0.38-0.52, p < 0.001) were lower with ATG. There was an interaction between ATG and conditioning regimen for relapse rate and overall survival. Relapse rate was higher in those who received reduced-intensity (RIC) or non-myeloablative (NMA) conditioning regimens and ATG, compared with MAC ± ATG or RIC without ATG (interaction test, p = 0.003). Overall survival was also poorer with ATG and RIC or NMA conditioning regimens (interaction test, p = 0.03). CONCLUSION Our results show that ATG can mitigate the more severe forms of chronic GVHD without impairing overall survival in HLA-matched HCT with PBSC grafts and myeloablative conditioning regimen. ATG should be standard in this population.
PICO Summary
Population
Adults over 40 years drawn from the CIBMTR database, undergoing first peripheral blood stem cell transplant from matched related donor or matched unrelated donor for acute myeloid leukemia or myelodysplastic syndrome with or without ATG (n=4320)
Intervention
Received Anti-T cell globulin (ATG) prophylaxis (n=1007)
Comparison
Received no ATG prophylaxis (n=3313)
Outcome
Overall survival was not different with ATG (HR = 1.09, 95CI 1.00-1.19) compared with no ATG. Relapse rate was higher with ATG (HR = 1.29, 95CI 1.17-1.43) and non-relapse mortality was lower with ATG (HR = 0.84, 95CI 0.72-0.98). Grades II-IV acute GVHD was significantly lower with ATG (HR = 0.77, 95CI 0.69-0.87) but not grades III-IV acute GVHD (HR = 0.85, 95CI 0.69-1.04). Both chronic GVHD (HR = 0.54, 95CI 0.48-0.60) and moderate/severe chronic GVHD (HR = 0.45, 95CI 0.38-0.52) were lower with ATG. Relapse rate was higher in those who received reduced-intensity (RIC) or non-myeloablative (NMA) conditioning regimens and ATG, compared with myeloablative conditioning with or without ATG or RIC without ATG. Overall survival was also poorer with ATG and RIC or NMA conditioning regimens.
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Disease-specific impact of anti-thymocyte globulin in allogeneic hematopoietic cell transplantation: a nationwide retrospective study on behalf of the JSTCT, transplant complications working group
Fuji, S., Hirakawa, T., Takano, K., Doki, N., Sawa, M., Kanda, Y., Uchida, N., Ara, T., Miyamoto, T., Eto, T., et al
Bone marrow transplantation. 2022
Abstract
The disease-specific impact of anti-thymocyte globulin (ATG) in allogeneic hematopoietic cell transplantation (allo-HCT) has not been determined. We retrospectively assessed the impact of ATG in allo-HCT using nationwide registry data from the Japan Society for Transplantation and Cellular Therapy. We included patients who received their first allo-HCT between 2007 and 2018 for acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), or malignant lymphoma (ML). In total, 8747 patients were included: 7635 patients did not receive ATG and 1112 patients received ATG as GVHD prophylaxis. The median follow-up period of surviving patients was 1457 days. There was no significant impact of pretransplant ATG on the OS or NRM rates in patients with ALL, AML, or ML. In patients with MDS, the probability of 3-year OS was 53.3% in the non-ATG group and 64.2% in the ATG group (P = 0.001). The cumulative incidence rates of relapse and NRM at 3 years were 14.2% and 30.3% (95% CI 27.2-33.3%), respectively, in the non-ATG group and 17.1% and 18.1% in the ATG group (P = 0.15 and P < 0.001). The same finding was observed in a propensity-score matched cohort. Our study suggests that the clinical benefit of ATG could vary among hematological diseases.
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HLA-Matching with PTCy: A Reanalysis of a CIBMTR Dataset with Propensity Score Matching and Donor Age
Ambinder, A. J., Jain, T., Tsai, H. L., Horowitz, M. M., Jones, R. J., Varadhan, R.
Blood advances. 2022
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Editor's Choice
Abstract
Blood or marrow transplantation (BMT) outcomes using haploidentical donors (Haplo) and post-transplant cyclophosphamide (PTCy)-based graft versus host disease (GVHD) prophylaxis compare favorably to using HLA-matched donors with calcineurin inhibitor-based GVHD prophylaxis. A recent CIBMTR analysis of patients receiving homogenous PTCy-based prophylaxis found that, with reduced intensity conditioning, Haplo BMTs had worse outcomes than matched unrelated donor (MUD) BMTs. Due to significant differences in characteristics between the groups, we reanalyzed the dataset using propensity score matching and, additionally, added a donor age variable. MUD BMTs were matched to Haplo BMTs in a 1:5 ratio. After matching, no significant differences were found between groups across all measured baseline characteristics. Outcomes analyses demonstrated no significant differences in overall survival (HR of mortality with MUD vs Haplo [95% CI], 0.95[0.65-1.16], P=0.75), disease free survival (HR of relapse or death, 0.98[0.73-1.18], P=0.89), relapse rate (HR, 1.06[0.77-1.38], P=0.69), or non-relapse mortality (HR, 0.85[0.42-1.13], P=0.49) between the two groups. After stratification by conditioning intensity, MUD BMTs in the RIC cohort had a lower risk of NRM (HR, 0.56 [0.14-0.99], P=0.05), with no significant difference in other clinical outcomes. These results suggest that the effect of HLA matching on BMT outcomes with PTCy is less meaningful than previously reported and observed differences resulted in part from differences in donor age. Timely identification of a young, at least half-matched (related or unrelated) donor may be more important than finding a matched donor, if the latter leads to a substantial delay in BMT or use of an older donor.
PICO Summary
Population
Adults with acute myeloid leukaemia, acute lymphoblastic leukaemia in first or second complete remission, or myelodysplastic syndromes attending 111 bone marrow transplantation (BMT) centres across the USA and reported to the CIBMTR registry (n=837)
Intervention
BMT from haploidentical donors (Haplo, n=637, subset receiving reduced-intensity conditioning (RIC) n=341)
Comparison
BMT from matched unrelated donors (MUD, n=200, subset receiving RIC n=114)
Outcome
After matching, no significant differences were found between groups across all measured baseline characteristics. Outcomes analyses demonstrated no significant differences in overall survival (HR of mortality with MUD vs Haplo [95% CI], 0.95[0.65-1.16]), disease free survival (HR of relapse or death, 0.98[0.73-1.18]), relapse rate (HR, 1.06[0.77-1.38]), or non-relapse mortality (HR, 0.85[0.42-1.13]) between the two groups. After stratification by conditioning intensity, MUD BMTs in the RIC cohort had a lower risk of non-relapse mortality (HR, 0.56 [0.14-0.99]), with no significant difference in other clinical outcomes.
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Graft-Versus-Host Disease Prophylaxis with Post-Transplantation Cyclophosphamide versus Cyclosporine A and Methotrexate in Matched Sibling Donor Transplantation
Nagler, A., Labopin, M., Dholaria, B., Wu, D., Choi, G., Aljurf, M., Ciceri, F., Gedde-Dahl, T., Meijer, E., Niittyvuopio, R., et al
Transplantation and cellular therapy. 2021
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Editor's Choice
Abstract
Cyclosporine A and methotrexate (CSA/MTX) is the standard graft-versus-host disease (GVHD) prophylaxis regimen for matched sibling donor (MSD) allogeneic hematopoietic cell transplantation (allo-HCT). Recently, post-transplant cyclophosphamide (PTCy) has been shown to be effective in GVHD prevention. In this registry-based study, we compared outcomes of 118 patients with PTCy and 1202 patients with CSA/MTX who underwent MSD allo-HCT for acute myeloid leukemia (AML). In a matched-pair analysis, PTCy was associated with a higher incidence of relapse at 2-year (41.1% versus 21.3%, p=0.039) compared to CSA/MTX. The incidence of day 180 grade II-IV acute GVHD (25.2% versus 25.4%, p=0.90) and 2-year chronic GVHD (42.6% versus 42.6%, p=0.84) were comparable between PTCy and CSA/MTX, respectively. Similarly, 2-year leukemia-free survival (LFS, 54.4% versus 74.32%, p=0.052), overall survival (OS, 70.6% versus 79.7%, p=0.15) and GVHD-free-relapse-free survival (GRFS, 38.1% versus 52.5%, p=0.49) were not statistically different between PTCy versus CSA/MTX. In conclusion, GVHD prophylaxis with PTCy is feasible, resulting in similar incidences of GVHD, GRFS, LFS, and OS compared to conventional CSA/MTX in patients undergoing allo-HCT from MSD. The higher relapse observed with PTCy needs further evaluation in a prospective study.
PICO Summary
Population
Patients who underwent matched sibling donor (MSD) allogeneic transplant for acute myeloid leukemia, (AML) reported to the EBMT registry (n=1320)
Intervention
Post-transplant cyclophosphamide (PTCy, n=118)
Comparison
Cyclosporine A and methotrexate (CSA/MTX, n=1202)
Outcome
In a matched-pair analysis, PTCy was associated with a higher incidence of relapse at 2-year (41.1% versus 21.3%) compared to CSA/MTX. The incidence of day 180 grade II-IV acute GVHD (25.2% versus 25.4%) and 2-year chronic GVHD (42.6% versus 42.6%) were comparable between PTCy and CSA/MTX, respectively. Similarly, 2-year leukemia-free survival (LFS, 54.4% versus 74.32%), overall survival (OS, 70.6% versus 79.7%) and GVHD-free-relapse-free survival (GRFS, 38.1% versus 52.5%) were not statistically different between PTCy versus CSA/MTX. In conclusion, GVHD prophylaxis with PTCy is feasible, resulting in similar incidences of GVHD, GRFS, LFS, and OS compared to conventional CSA/MTX in patients undergoing allo-HCT from MSD. The higher relapse observed with PTCy needs further evaluation in a prospective study.
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Post-transplant cyclophosphamide containing regimens after matched sibling, matched unrelated and haploidentical donor transplants in patients with acute lymphoblastic leukemia in first complete remission, a comparative study of the ALWP of the EBMT
Sanz, J., Galimard, J. E., Labopin, M., Afanasyev, B., Sergeevich, M. I., Angelucci, E., Kröger, N., Koc, Y., Ciceri, F., Diez-Martin, J. L., et al
Journal of hematology & oncology. 2021;14(1):84
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Editor's Choice
Abstract
BACKGROUND There is no information on the impact of donor type in allogeneic hematopoietic stem cell transplantation (HCT) using homogeneous graft-versus-host (GVHD) prophylaxis with post-transplant cyclophosphamide (PTCy) in acute lymphoblastic leukemia (ALL). METHODS We retrospectively analyzed outcomes of adult patients with ALL in CR1 that had received HCT with PTCy as GVHD prophylaxis from HLA-matched sibling (MSD) (n?=?78), matched unrelated (MUD) (n?=?94) and haploidentical family (Haplo) (n?=?297) donors registered in the EBMT database between 2010 and 2018. The median follow-up period of the entire cohort was 2.2 years. RESULTS Median age of patients was 38 years (range 18-76). Compared to MSD and MUD, Haplo patients received peripheral blood less frequently. For Haplo, MUD, and MSD, the cumulative incidence of 100-day acute GVHD grade II-IV and III-IV, and 2-year chronic and extensive chronic GVHD were 32%, 41%, and 34% (p?=?0.4); 13%, 15%, and 15% (p?=?0.8); 35%, 50%, and 42% (p?=?0.01); and 11%, 17%, and 21% (p?=?0.2), respectively. At 2 years, the cumulative incidence of relapse and non-relapse mortality was 20%, 20%, and 28% (p?=?0.8); and 21%, 18%, and 21% (p?=?0.8) for Haplo, MUD, and MSD, respectively. The leukemia-free survival, overall survival and GVHD-free, relapse-free survival for Haplo, MUD, and MSD was 59%, 62%, and 51% (p?=?0.8); 66%, 69%, and 62% (p?=?0.8); and 46%, 44%, and 35% (p?=?0.9), respectively. On multivariable analysis, transplant outcomes did not differ significantly between donor types. TBI-based conditioning was associated with better LFS. CONCLUSIONS Donor type did not significantly affect transplant outcome in patient with ALL receiving SCT with PTCy.
PICO Summary
Population
Adults with acute lymphoblastic leukaemia (ALL) receiving allogeneic transplant in CR1 with prophylaxis with post-transplant cyclophosphamide (PTCy) prophylaxis (n=469)
Intervention
Haploidentical transplantation (n=297)
Comparison
Matched unrelated donor (MUD, n=94); matched sibling donor (MSD, n=78)
Outcome
Median age of patients was 38 years (range 18-76). Compared to MSD and MUD, Haplo patients received peripheral blood less frequently. For Haplo, MUD, and MSD, the cumulative incidence of 100-day acute GVHD grade II-IV and III-IV, and 2-year chronic and extensive chronic GVHD were 32%, 41%, and 34%; 13%, 15%, and 15%; 35%, 50%, and 42%; and 11%, 17%, and 21%, respectively. At 2 years, the cumulative incidence of relapse and non-relapse mortality was 20%, 20%, and 28% and 21%, 18%, and 21% for Haplo, MUD, and MSD, respectively. The leukemia-free survival, overall survival and GVHD-free, relapse-free survival for Haplo, MUD, and MSD was 59%, 62%, and 51%; 66%, 69%, and 62%; and 46%, 44%, and 35%, respectively. On multivariable analysis, transplant outcomes did not differ significantly between donor types. TBI-based conditioning was associated with better leukaemia free survival.
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Post-Transplant Cyclophosphamide (PTCy) is Associated with Increased Cytomegalovirus Infection: A CIBMTR Analysis
Goldsmith, S. R., Abid, M. B., Auletta, J. J., Bashey, A., Beitinjaneh, A., Castillo, P., Chemaly, R. F., Chen, M., Ciurea, S. O., Dandoy, C. E., et al
Blood. 2021
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Editor's Choice
Abstract
Prior studies suggest increased CMV infection following haploidentical donor transplantation with post-transplant cyclophosphamide (HaploCy). The role of allograft source and PTCy in CMV infection and disease is unclear. We analyzed the effect of graft source and PTCy on incidence of CMV infection as well as transplant outcomes as it relates to CMV serostatus and occurrence of CMV infection by d180. We examined patients reported to CIBMTR between 2012-2017 who had received HaploCy (n = 757), Sib with PTCy (SibCy, n=403), or Sib with calcineurin inhibitor-based prophylaxis (SibCNI, n=1605) for AML/ALL/MDS. Cumulative incidences of CMV infection by d180 were 42% (99% CI, 37-46), 37% (31 - 43), and 23% (20 - 26), respectively [p<0.001]. CMV end-organ disease was statistically comparable. CMV infection risk was highest for CMV-Seropositive recipients (R+), but significantly higher in PTCy recipients regardless of donor [HaploCy (n=545): HR 50.3 (14.4 - 175.2); SibCy (n=279): HR 47.7 (13.3 - 171.4); SibCNI (n=1065): HR 24.4 (7.2 - 83.1); p<0.001]. D+/R- patients also had increased risk for CMV infection. Among seropositive recipients or those developing CMV infection, HaploCy had worse OS and NRM. Relapse was unaffected by CMV infection or serostatus. PTCy was associated with lower chronic GVHD overall, but CMV infection in PTCy recipients was associated with higher cGVHD (p=0.006). PTCy, regardless of donor, is associated with higher incidence of CMV infection, augmenting the risk of seropositivity. Additionally CMV infection may negate the cGVHD protection of PTCy. This study supports aggressive prevention strategies in all patients receiving PTCy.
PICO Summary
Population
Patients with acute myeloid leukaemia, acute lymphoblastic leukaemia or myelodysplastic synrome (n=2765)
Intervention
Haploidentical transplantation with post-transplant cyclophosphamide (HaploCy, n=757),
Comparison
Sibling donor with post-transplant cyclophosphamide (SibCy, n=403), or Sibling donor with calcineurin inhibitor-based prophylaxis (SibCNI, n=1605)
Outcome
Cumulative incidences of CMV infection by day 180 were 42% (HaploCy), 37% (SibCy), and 23% (SibCNI), respectively. CMV end-organ disease was statistically comparable. CMV infection risk was highest for CMV-Seropositive recipients (R+), but significantly higher in PTCy recipients regardless of donor [HaploCy (n=545): HR 50.3; SibCy (n=279): HR 47.7; SibCNI (n=1065): HR 24.4. D+/R- patients also had increased risk for CMV infection. Among seropositive recipients or those developing CMV infection, HaploCy had worse OS and NRM. Relapse was unaffected by CMV infection or serostatus. PTCy was associated with lower chronic GVHD overall, but CMV infection in PTCy recipients was associated with higher cGVHD. PTCy, regardless of donor, is associated with higher incidence of CMV infection, augmenting the risk of seropositivity. Additionally CMV infection may negate the cGVHD protection of PTCy.
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Post-Transplant cyclophosphamide is associated with increase in Non-CMV Herpesvirus infections in Acute leukemia and MDS patients
Singh, A., Dandoy, C. E., Chen, M., Kim, S., Mulroney, C. M., Kharfan-Dabaja, M. A., Ganguly, S., Maziarz, R. T., Kanakry, C. G., Kanakry, J. A., et al
Transplantation and cellular therapy. 2021
Abstract
BACKGROUND There is increasing use of post-transplant cyclophosphamide (PTCy) for GVHD prophylaxis for both haploidentical and fully matched transplants. Published studies have reported an increased incidence of CMV infection with the use of PTCy. Limited data exist regarding the incidence and outcomes of infection with non-CMV herpes viruses (NCHV) in this setting. OBJECTIVE The aim of this study was to evaluate the cumulative incidence of NCHV infections and the association of NCHV infections with transplant-specific outcomes in patients receiving haploidentical transplant with PTCy(HaploCy), matched sibling donor transplant with PTCy (SibCy) or matched sibling donor transplant with calcineurin inhibitor based prophylaxis (SibCNI). We hypothesized that, like CMV infection, patients receiving haploidentical transplant with PTCy will have higher risk of NCHV infections. STUDY DESIGN Using the CIBMTR database, we analyzed patients (HaploCy, n=757; SibCNI, n=1605; SibCy, n=403) receiving first hematopoietic stem-cell transplant between 2012 and 2017 for acute myeloid leukemia, acute lymphoblastic leukemia and myelodysplastic syndrome. RESULTS The cumulative incidence of non-CMV herpes virus infection at six months post-transplant in the HaploCy, SibCy and SibCNI were 13.9% (99%CI=10.8-17.3%), 10.7% (99%CI=7.1-15%), and 5.7% (99%CI=4.3-7.3%), p<0.001 respectively. This was primarily due to a higher frequency of HHV-6 viremia reported in patients receiving PTCy. Incidence of Epstein-Barr viremia was low in all groups and no cases of post-transplant lymphoproliferative disorder were seen in PTCy groups. The incidence of non-CMV herpes virus organ disease was low in all three cohorts. Development of NCHV infection was associated with increased treatment-related mortality, particularly in the HaploCy group. There was no association with the development of GVHD, relapse, and disease-free survival. Patients in PTCy cohorts who did not develop non-CMV herpes virus infection had lower rates of cGVHD. CONCLUSIONS This study demonstrates that the use of PTCy is associated with increased risk of NCHV infection. Development of NCHV infection is associated with increased non-relapse mortality, especially in HaploCY group. Prospective trials should consider viral surveillance strategies in conjunction with assessment of immune reconstitution for better understanding of the clinical relevance of viral reactivation in different transplant settings.
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10.
Post-transplant cyclophosphamide versus anti-thymocyte globulin for graft-versus-host disease prevention in haploidentical transplantation for adult acute lymphoblastic leukemia
Nagler, A., Kanate, A. S., Labopin, M., Ciceri, F., Angelucci, E., Koc, Y., Gulbas, Z., Arcese, W., Tischer, J., Pioltelli, P., et al
Haematologica. 2020
Abstract
Graft-versus-host disease (GVHD) prophylaxis for unmanipulated haploidentical hematopoietic cell transplantation (haplo-HCT) include post-transplant cyclophosphamide (PTCy) and anti-thymocyte globulin (ATG). Utilizing EBMT registry, we compared ATG versus PTCy based GVHD prophylaxis in adult acute lymphoblastic leukemia (ALL) patients undergoing haplo-HCT. Included were 434 patients; ATG (n=98) and PTCy (n=336). Median follow-up was ~2 years. Baseline characteristics were similar between the groups except that the ATG-group was more likely to have relapsed/refractory ALL (P=0.008), non-TBI conditioning (P<0.001), peripheral blood graft source (P=<0.001) and transplanted at an earlier time-period (median year of HCT 2011 vs. 2015). The 100-day grade II-IV and III-IV acute-GVHD was similar between ATG and PTCy, as was 2-year chronic-GVHD. On multivariate analysis (MVA), leukemia-free survival (LFS) and overall survival (OS) was better with PTCy compared to ATG prophylaxis. Relapse incidence (RI) was lower in the PTCy group (P=0.03), while non-relapse mortality (NRM) was not different. Advanced disease and lower performance score were associated with poorer LFS and OS and advanced disease with inferior GVHD-free/relapse-free survival (GRFS). Peripheral grafts were associated with higher GVHD compared to bone marrow grafts. In ALL patients undergoing unmanipulated haplo-HCT, PTCy for GVHD prevention resulted in lower RI and improved LFS and OS compared to ATG.