Effect of Conditioning Regimens and Graft-versus-Host Disease Prophylaxis on the Outcomes of Umbilical Cord Blood Transplantation Performed with Cyclophosphamide/Total Body Irradiation-Based Regimens

Umbilical cord blood (UCB) is a valuable alternative donor source for allogeneic hematopoietic stem cell transplantation. Various conditioning regimens and graft-versus-host disease (GVHD) prophylaxis regimens aimed at improving the outcomes of umbilical cord blood transplantation (UCBT) have been explored; however, the differences in their effects remain unclear. This study was conducted to elucidate the differences in the effects of conditioning and GVHD prophylaxis regimens on UCBT outcomes by disease type in a nationwide, retrospective study. We retrospectively analyzed the effects of conditioning and GVHD prophylaxis regimens on the outcomes of UCBT performed with cyclophosphamide (Cy)/total body irradiation (TBI)-based regimens in patients with acute myeloid leukemia (AML; n = 1126), acute lymphoblastic leukemia (ALL; n = 620), myelodysplastic syndrome (MDS; n = 170), and lymphoma (n = 128). Multivariate analysis for overall survival (OS) demonstrated the benefit of adding high-dose cytarabine to the Cy/TBI regimen for the AML group (relative risk [RR], .76; P = .003) and lymphoma group (RR, .54; P = .02), but not for the ALL and MDS groups. In the ALL group, adding etoposide to the Cy/TBI regimen was associated with a lower OS (RR, 1.45; P = .03). For GVHD prophylaxis, a tacrolimus/methotrexate regimen was associated with a lower OS compared with a cyclosporine/methotrexate regimen in the AML group (RR, 1.26; P = .01); this difference was not observed in the other groups. These differences in OS according to the conditioning and GVHD prophylaxis regimen were attributable mainly to differences in relapse risk. Our data show that the effects of conditioning regimens and GVHD prophylaxis on UCBT outcomes differed according to disease type. UCBT outcomes could be improved by selecting optimal conditioning regimens and GVHD prophylaxis for each disease type.

Prognostic factors in haploidentical transplantation with post-transplant cyclophosphamide for acute myeloid leukemia

BACKGROUND AIMS

Haploidentical hematopoietic stem cell transplantation (haplo-HCT) is an appropriate option when an HLA-matched related or unrelated donor is not available. Haplo-HCT using post-transplant cyclophosphamide (PTCy) is being increasingly performed worldwide due to its effective suppression of GVHD and its safety.

METHODS

We conducted a large nationwide cohort study to retrospectively analyze 366 patients with acute myeloid leukemia undergoing haplo-HCT with PTCy between 2010 and 2019 and to identify prognostic factors.

RESULTS

A multivariate Cox analysis revealed that an older recipient age (≥60 years), a male donor to a male recipient, a cytomegalovirus IgG-negative donor to a cytomegalovirus IgG-positive recipient, a poor cytogenetic risk, a noncomplete remission status at the time of transplantation, and a history of HCT were independently associated with worse overall survival (OS). Based on each hazard ratio, these factors were scored (1-2 points) and stratified by their total score into three groups: favorable (0-1 points), intermediate (2-3 points), and poor (4 points or more) groups, and 2-year OS rates were 79.9%, 49.2%, and 25.1%, respectively (P < 0.001).

CONCLUSIONS

The present study revealed significant prognostic factors in haplo-HCT with PTCy, and a scoring system based on these factors may be used to predict outcomes.

Sirolimus Is an Acceptable Alternative to Tacrolimus for Graft-versus-Host Disease Prophylaxis after Haploidentical Peripheral Blood Stem Cell Transplantation with Post-Transplantation Cyclophosphamide

Graft-versus-host disease (GVHD) prophylaxis with post-transplantation cyclophosphamide (PTCy), tacrolimus (Tac), and mycophenolate mofetil (MMF) for allogeneic haploidentical donor (haplo) hematopoietic cell transplantation (HCT) results in comparable outcomes to matched unrelated donor HCT. A phase II study from the Moffitt Cancer Center substituting sirolimus (Siro) for Tac in this prophylactic regimen reported comparable rates of grade II-IV acute GVHD (aGVHD). Many centers have substituted Siro for Tac in this setting based on a preferable side effect profile, although comparative data are limited. In this study, we retrospectively compared outcomes in haplo-HCT with PTCy/Siro/MMF versus haplo-HCT with PTCy/Tac/MMF. The study cohort included all consecutive patients receiving haploidentical donor T cell-replete peripheral blood stem cell (PBSC) HCT for hematologic malignancies at Moffitt Cancer Center or the City of Hope National Medical Center between 2014 and 2019. A total of 423 patients were included, of whom 84 (20%) received PTCy/Siro/MMF and 339 (80%) received PTCy/Tac/MMF. The median age for the entire cohort was 54 years (range, 18 to 78 years), and the median follow-up was 30 months. The Siro group had a higher proportion of patients age ≥60 years (58% versus 34%; P < .01), and the groups also differed in diagnosis type, conditioning regimen, and cytomegalovirus serostatus. There were no significant differences in the rates of grade II-IV aGVHD (45% versus 47%; P = .6) at day +100 or chronic GVHD (cGVHD) (47% versus 54%; P = .79) at 2 years post-HCT. In multivariate analysis, neutrophil engraftment at day +30 was significantly better in the Tac group (odds ratio, .30; 95% confidence interval, .1 to .83; P = .02), with a median time to engraftment of 17 days versus 18 days in the Siro group, but platelet engraftment was similar in the 2 groups. Otherwise, in multivariate analysis, GVHD prophylaxis type had no significant influence on aGVHD or cGVHD, nonrelapse mortality, relapse, GVHD-free relapse-free survival, disease-free survival, or overall survival after PBSC haplo-HCT. These findings suggest that Siro is a comparable alternative to Tac in combination with PTCy/MMF for GVHD prophylaxis, with overall similar clinical outcomes despite delayed engraftment after peripheral blood stem cell haplo-HCT. Although Tac remains the standard of care, Siro may be substituted based on the side effect profile of these medications, with consideration of patient medical comorbidities at HCT.

Kinetics of Recovery of Naïve and Memory T Cells in Acute Leukemia Patients after Allogeneic Stem Cell Transplantation Depending on Different GVHD Prophylaxis Regimens

Background: Memory T cells are a heterogeneous population of immune cells that provide adaptive immunity. Its full recovery seems essential for graft-versus-tumor reactions that provide an opportunity for biological cure in patients with acute leukemia. The use of mismatched or haploidentical donors has increased, which has become possible because of modifications in graft versus host disease (GVHD) prophylaxis. Materials and Methods: Sixty-five leukemia patients (acute myeloid leukemia - 40, acute lymphoblastic leukemia - 25), median age 33 (17-61) years, underwent allo-HSCT from 2016 to 2019 in the National Research Centre for Hematology. Patients were divided into three groups based on the impact of GVHD prophylaxis on T cell recovery: horse antithymocyte globulin (ATG)-based regimen (n=32), horse ATG combined with posttransplant cyclophosphamide (PT-Cy) (n=18), and ex vivo T cell depletion (n=15). Results: The early period after transplantation (before day +100) was characterized by significantly lower absolute numbers of T naïve, memory stem and T central memory cells in peripheral blood in patients after ATG+PT-Cy-regimen or ex vivo T cell depletion than after ATG-based prophylaxis (p<0.05). Moreover, strong depletion of naïve T and memory stem cells prevents the development of GVHD, and determining the absolute number of CD8+ naïve T and memory stem cells with a cutoff of 1.31 cells per microliter seems to be a perspective in assessing the risks of developing acute GVHD (p=0.008). The dynamics of T cell recovery showed the involvement of either circulating or bone marrow resident T effector cells shortly after allogeneic transplantation in all patients, but the use of manipulated grafts with ex vivo T cell depletion requires the involvement of naïve and memory stem cells. There was no significant effect of T cell recovery on leukemia relapse after allogeneic transplantation. Conclusion: These experimental outcomes contribute to providing the best understanding of immunological events that occur early after transplantation and help in the rational choice of GVHD prophylaxis in patients who will undergo allogeneic transplantation. Our study demonstrated the comparable immunological effects of posttransplant cyclophosphamide and ex vivo T cell depletion and immunological inefficiency of horse ATG for GVHD prevention.

Corticosteroids as graft-versus-host disease prophylaxis for allogeneic hematopoietic cell transplant recipients with calcineurin inhibitor intolerance

BACKGROUND AIMS

Although calcineurin inhibitors (CNIs) have a well-established role in the prevention of graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (HCT), their use can be limited by significant toxicities, which may result in premature treatment discontinuation. The optimal management of patients with CNI intolerance is unknown. The objective of this study was to determine the effectiveness of corticosteroids as GVHD prophylaxis for patients with CNI intolerance.

METHODS

This retrospective single-center study included consecutive adult patients with hematologic malignancies who underwent myeloablative peripheral blood allogeneic HCT with anti-thymocyte globulin, CNI, and methotrexate GVHD prophylaxis in Alberta, Canada. Multivariable competing-risks regression was used to compare cumulative incidences of GVHD, relapse, and non-relapse mortality between recipients of corticosteroid versus continuous CNI prophylaxis, and multivariable Cox proportional hazards regression was applied to compare overall survival, relapse-free survival (RFS) and moderate-to-severe chronic GVHD and RFS.

RESULTS

Among 509 allogeneic HCT recipients, 58 (11%) patients developed CNI intolerance and were switched to corticosteroid prophylaxis at median 28 days (range 1-53) after HCT. Compared with patients who received continuous CNI prophylaxis, recipients of corticosteroid prophylaxis had significantly greater cumulative incidences of grade 2-4 acute GVHD (subhazard ratio [SHR] 1.74, 95% confidence interval [CI] 1.08-2.80, P = 0.024), grade 3-4 acute GVHD (SHR 3.22, 95% CI 1.55-6.72, P = 0.002), and GVHD-related non-relapse mortality (SHR 3.07, 95% CI 1.54-6.12, P = 0.001). There were no significant differences in moderate-to-severe chronic GVHD (SHR 0.84, 95% CI 0.43-1.63, P = 0.60) or relapse (SHR 0.92, 95% CI 0.53-1.62, P = 0.78), but corticosteroid prophylaxis was associated with significantly inferior overall survival (hazard ratio [HR] 1.77, 95% CI 1.20-2.61, P = 0.004), RFS (HR 1.54, 95% CI 1.06-2.25, P = 0.024), and chronic GVHD and RFS (HR 1.46, 95% CI 1.04-2.05, P = 0.029).

CONCLUSIONS

Allogeneic HCT recipients with CNI intolerance are at increased risks of acute GVHD and poor outcomes despite institution of corticosteroid prophylaxis following premature CNI discontinuation. Alternative GVHD prophylaxis strategies are needed for this high-risk population.

Post-transplant cyclophosphamide as sole GHVD prophylaxis after matched reduced-intensity conditioning allotransplant

BACKGROUND

Post-transplant cyclophosphamide (PTCY) alone as graft-versus-host disease (GVHD) prophylaxis may avoid/reduce short- and mid-term toxicities of drugs commonly used for GVHD prophylaxis, accelerate immune reconstitution after the graft to decrease infections and facilitate the early integration of adjunct maintenance therapies to prevent relapse.

OBJECTIVE

A prospective phase 2 study was designed in order to assess the feasibility and safety of PTCY as a sole GVHD prophylaxis in adult patients receiving a Baltimore-based reduced-intensity conditioning (RIC) peripheral blood (PB) allogeneic hematopoietic stem cell transplantation (Allo-HSCT) with a matched donor.

STUDY DESIGN

Patients were planned to be included stepwise up to 59 evaluable PTCY recipients, in order to be able to stop the protocol in case of excessive corticosteroid resistant grade 3-4 severe acute GVHD (aGVHD). Because a high incidence of grade 2-4 aGVHD was observed after analysis of the first 27 patients, the protocol was amended to test the addition of 1 day of anti-thymoglobulin to PTCY. In spite of this, the trial had to be stopped after 38 treated patients, because of an unacceptable rate of grade 3-4 aGVHD. Donors were matched related to 12 patients and unrelated to 26.

RESULTS

With a median follow-up of 29.6 months, 2-year overall, disease-free and GVHD-free relapse-free (GRFS) survivals were respectively 65.4%, 62.1% and 46.9%. Cumulative incidences of grade 2-4 and 3-4 aGVHD at day 100 were 52.6% and 21.1%, respectively, while that of moderate/severe chronic(c) GVHD was 15.7% at 2 years. Addition of ATG to PTCY did influence neither aGVHD, cGVHD nor GRFS.

CONCLUSION

Despite paradoxically good survivals, especially GRFS, this study failed to demonstrate that PTCY (± ATG) alone can be used for Baltimore-based RIC PB Allo-HSCT with matched donors. Other combinations should be tested to try and avoid long-term use of immunosuppressive drugs following Allo-HSCT in this setting.

Post-transplant cyclophosphamide and early mixed donor Chimerism in myeloid malignancies; a single-center experience

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curative option for high-risk myeloid malignancies. Post-transplant cyclophosphamide (PT-Cy) has proven to be effective for graft versus host disease (GVHD) prophylaxis. Given that graft-versus-tumor (GVT) effect plays a major role in reducing the risk of disease relapse, the application of PT-Cy must balance the risk of relapse. Mixed chimerism (MC) refers to a state of concurrent presence of recipient and donor cells post allo-HSCT which may precede relapse disease.

OBJECTIVE

We investigated the impact of PT-Cy on early MC (EMC) and disease relapse in patients with a myeloid malignancy post allo-HSCT.

STUDY DESIGN

This retrospective single-center study included patients that underwent allo-HSCT between 2015 and 2021. Patient and disease characteristics were collected from the electronic health records. EMC was defined as <95% donor cells at day 90-120 post allo-HSCT.

RESULTS

A total of 144 patient that received an allo-HSCT were included in the study. One hundred and eight (75%) patients received PT-Cy as part of the GVHD prophylaxis regimen. The majority underwent allo-HSCT for acute myeloid leukemia (62%) or myelodysplastic syndrome (31%). Sixty-five percent received allo-HSCT from a matched unrelated donor transplant and 65% received a myeloablative conditioning regimen. A lower rate of chronic GVHD (p = 0.03) and a higher rate of EMC (p = 0.04) were observed in patients that received PT-Cy. PT-Cy was not associated with overall survival (OS) and relapse-free survival (RFS). Multivariable analysis identified measurable residual disease status (p = 0.003), hematopoietic cell transplantation-specific comorbidity index (p = 0.012) and chronic GVHD (p = 0.006) as independent prognostic variables for OS. AML-adverse risk (p = 0.004) and EMC (p = 0.018) were independently prognostic for RFS. While EMC overall was not significantly associated with higher risk of relapse, EMC was associated with shorter RFS within adverse-risk AML patients.

CONCLUSION

Our study shows that PT-Cy was associated with an increased risk of EMC. The predictive value of EMC for relapse remains unclear and may depend on the underlying disease, which should be validated in a larger cohort.

Human leukocyte antigen 7/8-matched unrelated bone marrow transplantation using anti-thymocyte globulin in children

Human leukocyte antigen (HLA) mismatched unrelated donor transplantation is associated with an increased risk of graft-versus-host disease, graft failure, and infection, which increases post-transplant morbidity and mortality. In this single-center retrospective study, outcomes were evaluated in 30 consecutive children who underwent bone marrow transplantation (BMT) from HLA 1 allele-mismatched (HLA 7/8-matched) unrelated donors with rabbit anti-thymocyte globulin (rATG) as graft-versus-host disease (GVHD) prophylaxis. The 3-year overall survival (OS), event-free survival (EFS), and GVHD-relapse-free survival rates were 91.7% (95% CI 70.5%-91.9%), 88.3% (95% CI 67.5%-96.1%), and 73.9% (95% CI 52.4%-86.8%), respectively. Grade II-IV and III-IV acute GVHD occurred in 10 (33%) and 2 (7.0%) patients, respectively. The 3-year cumulative incidence of chronic GVHD was 7.8%. No fatal viral infections occurred. The study results show the feasibility of HLA 7/8-matched unrelated BMT with ATG to achieve favorable outcomes and acceptable GVHD, especially for patients who lack a fully matched donor.

Impact of Post-Transplantation Cyclophosphamide on Transfusion Requirements in HLA-Matched Sibling Peripheral Blood Stem Cell Transplantation

Post-transplantation cyclophosphamide (PTCy)-based graft-versus-host disease (GVHD) prophylaxis is being increasingly used in allogeneic hematopoietic stem cell transplantation (allo-HSCT) from HLA-matched related donors (MRDs); however, information regarding the transfusion needs in this setting is lacking. This study compared RBC and platelet units transfused and time to transfusion independence according to the GVHD prophylaxis regimen in MRD HSCT. We performed a matched-pair analysis comparing the transfusion requirements and the clinical outcomes of patients who underwent MRD peripheral blood HSCT using PTCy between January 2017 and June 2021 (n = 100) with historical MRD HSCTs using standard cyclosporine A (CsA)-based prophylaxis (n = 100). Neutrophil engraftment was significantly delayed in the PTCy group compared with the CsA group (16 days versus 13 days; P = .003). PTCy was associated with increased RBC (median, 5 units versus 4 units; P = .04) and platelet (median, 6 units versus 3 units; P = .01) transfusion requirements during the first 30 days after transplantation. The proportion of patients requiring platelet transfusion during days 31 to 90 after transplantation was also higher in the PTCy group (55% versus 25%; P < .0001). In multivariate analysis, PTCy was associated with delayed RBC and platelet transfusion independence (hazard ratio, .61 [P = .007] and .51 [P < .0001], respectively). The cumulative incidence (CuI) of BK polyomavirus-associated hemorrhagic cystitis grade ≥2 at 100 days was higher in the PTCy group (34% versus 12%; P < .0001); however, the PTCy group had lower rates of grade II-IV acute GVHD (100-day CuI, 57% versus 23%; P < .0001) and moderate to severe chronic GVHD (1-year CuI, 49% versus 28%; P = .003), as well as better 2-year overall survival (74% versus 56%; P = .01). Our study shows that although PTCy increases the transfusion burden in MRD HSCT, it is associated with a low incidence of severe GVHD and with encouraging survival outcomes.

Controversies and expectations for the prevention of GVHD: A biological and clinical perspective

Severe acute and chronic graft versus host disease (GVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation. Historically, cord blood and matched sibling transplantation has been associated with the lowest rates of GVHD. Newer methods have modified the lymphocyte components to minimize alloimmunity, including: anti-thymocyte globulin, post-transplant cyclophosphamide, alpha/beta T cell depletion, and abatacept. These agents have shown promise in reducing severe GVHD, however, can be associated with increased risks of relapse, graft failure, infections, and delayed immune reconstitution. Nonetheless, these GVHD prophylaxis strategies have permitted expansion of donor sources, especially critical for those of non-Caucasian decent who previously lacked transplant options. This review will focus on the biologic mechanisms driving GVHD, the method by which each agent impacts these activated pathways, and the clinical consequences of these modern prophylaxis approaches. In addition, emerging novel targeted strategies will be described. These GVHD prophylaxis approaches have revolutionized our ability to increase access to transplant and have provided important insights into the biology of GVHD and immune reconstitution.

Lower dose of ATG combined with basiliximab for haploidentical hematopoietic stem cell transplantation is associated with effective control of GVHD and less CMV viremia

Currently, the graft-versus-host disease (GVHD) prophylaxis consists of an immunosuppressive therapy mainly based on antithymocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy). GVHD remains a major complication and limitation to successful allogeneic haploidentical hematopoietic stem cell transplantation (haplo-HSCT). We modified the ATG-based GVHD prophylaxis with the addition of basiliximab in the setting of haplo-HSCT and attempted to explore the appropriate dosages. We conducted a retrospective analysis of 239 patients with intermediate- or high-risk hematologic malignancies who received haplo-HSCT with unmanipulated peripheral blood stem cells combined or not with bone marrow. All patients received the same GVHD prophylaxis consisting of the combination of methotrexate, cyclosporine or tacrolimus, mycofenolate-mofetil, and basiliximab with different doses of ATG (5-9mg/kg). With a median time of 11 days (range, 7-40 days), the rate of neutrophil engraftment was 96.65%. The 100-day cumulative incidences (CIs) of grade II-IV and III-IV aGVHD were 15.8 ± 2.5% and 5.0 ± 1.5%, while the 2-year CIs of total cGVHD and extensive cGVHD were 9.8 ± 2.2% and 4.1 ± 1.5%, respectively. The 3-year CIs of treatment-related mortality (TRM), relapse, overall survival (OS), and disease-free survival (DFS) were 14.6 ± 2.6%, 28.1 ± 3.4%, 60.9 ± 3.4%, 57.3 ± 3.4%, respectively. Furthermore, the impact of the reduction of the ATG dose to 6 mg/kg or less in combination with basiliximab on GVHD prevention and transplant outcomes among patients was analyzed. Compared to higher dose of ATG(>6mg/kg), lower dose of ATG (≤6mg/kg) was associated with a significant reduced risk of CMV viremia (52.38% vs 79.35%, P<0.001), while the incidences of aGVHD and cGVHD were similar between the two dose levels. No significant effect was found with regard to the risk of relapse, TRM, and OS. ATG combined with basiliximab could prevent GVHD efficiently and safely. The optimal scheme of using this combined regimen of ATG and basiliximab is that administration of lower dose ATG (≤6mg/kg), which seems to be more appropriate for balancing infection control and GVHD prophylaxis.

Prognostic impact of the dosage of methotrexate combined with tacrolimus for graft-versus-host disease prophylaxis after cord blood transplantation

The optimal dosage of methotrexate (MTX) for graft-versus-host disease (GVHD) prophylaxis after cord blood transplantation (CBT) has not been well elucidated. Therefore, we conducted a retrospective study comparing a mini-MTX group (5 mg/m² on day 1, 3 and 6) to a short-MTX group (10 mg/m² on day 1 and 7 mg/m² on day 3 and 6) after CBT. Sixty-three patients were classified as the mini-MTX group and 20 as the short-MTX group. The median time and cumulative incidence of neutrophil engraftment did not vary between the two groups. The cumulative incidence of grade 2-4 and grade 3-4 acute GVHD was similar in both groups. Overall survival in the mini-MTX group was significantly lower than in the short-MTX group (46.9% vs. 88.7% at 1 year, p < 0.01), contributing to higher non-relapse mortality (NRM) in the mini-MTX group (32.0% vs. 5.0% at 1 year, p = 0.02). In multivariate analysis, the mini-MTX regimen was the most powerful prognostic factor for OS (hazard ratio 4.11; p = 0.03). Although the reduced dosage of MTX had no effect on neutrophil engraftment, increased NRM due to higher incidence of infection, graft failure, and severe acute GVHD resulted in a lower survival rate in the mini-MTX group after CBT.

Effect of methotrexate dose in graft-versus-host disease prophylaxis after single-unit cord blood transplantation in adult acute myeloid leukemia

To investigate the association between methotrexate (MTX) dosage and engraftment, graft-versus-host disease (GVHD) incidence, and survival in umbilical cord blood transplantation (UCBT), we compared transplant outcomes after UCBT with various GVHD prophylaxis regimens, using registry data with additional data collection. Patients transplanted for acute myeloid leukemia with a calcineurin inhibitor (CNI) and either MTX or mycophenolate mofetil (MMF) combination were selected. In total, 888 single-unit UCBTs (MTX_15-10-10, 415; MTX_10-7-7, 294; MTX_5-5-5, 71; MMF, 108) were included. In multivariate analyses with MTX_15-10-10 as the reference, the likelihood of neutrophil and platelet engraftment was significantly worse in the MTX_10-7-7 group, and similarly better in MMF group compared with MTX_15-10-10. All variables including CyA vs Tac and 4-group GVHD prophylaxis became significant for the risk of grade II-IV acute GVHD in the final multivariate model. We observed significant additional effects of combined MTX dose in the Tac group, which were larger with lower MTX dose and MMF. No significant difference was observed in survival risk among GVHD prophylaxis groups. Despite the potential background differences in the combined CNI and conditioning regimen, we conclude that the recommended GVHD prophylaxis is a combination of CyA plus MTX_15-10-10 or Tac plus MMF.

Experience Using Anti-Thymocyte Globulin With Post-Transplantation Cyclophosphamide for Graft-Versus-Host Disease Prophylaxis in Peripheral Blood Haploidentical Stem Cell Transplantation

Haploidentical hematopoietic cell transplantation (HaploHCT) is an alternative treatment option for patients without a suitable 10/10 HLA matched donor. We share an updated experience at our center of using in vivo dual T-cell depletion with anti-thymocyte globulin (ATG) and post-transplantation cyclophosphamide (PTCy) in peripheral blood haploHCT and report the impact of reducing the dose of ATG from 4.5 mg/kg to 2 mg/kg on post-transplantation complications and outcomes. Ninety-five consecutive adults underwent haploHCT at our center between August 2016 and February 2020, all of whom were included in the study. Nine (9.5%) patients received myeloablative conditioning, and 86 (90.5%) patients underwent reduced-intensity haploHCT. All patients received thymoglobulin, PTCy and cyclosporine (CsA) for graft-versus-host disease (GVHD) prophylaxis: Sixty (63.2%) patients received 4.5 mg/kg, and 35 (36.8%) patients received 2 mg/kg of ATG. Clinical information was collected retrospectively and updated in June 2020. The median age was 57 (18-73), and acute myeloid leukemia was the most prevalent diagnosis (58.9%). The day 100 cumulative incidence of grade II-IV and grade III-IV aGVHD, and 1-year moderate/severe cGVHD were 22.3%, 11.1%, and 20.2%, respectively. Those patients who received 2 mg/kg of ATG had higher incidence of grade III-IV aGVHD (23.9% vs 3.5%, P = .006) and comparable moderate/severe cGVHD (1-year 20.6% vs 19.8%, P = .824) than those patients who received 4.5 mg/kg. Overall, the 18-month overall survival (OS), relapse-free survival (RFS), and non-relapse mortality (NRM) were 43.8%, 38.4%, and 40.2%, respectively. The reduction of the ATG dose did not have a significant impact in OS (hazard ratio [HR] 1.06, P = .847), RFS (HR 0.984, P = .955), and in NRM (HR 1.38; P = .348). The reduction of the ATG resulted in a negative impact on aGVHD without conferring any benefit in OS, RFS, and NRM. Consequently, the ATG dose used at our institution in combination with PTCy and CsA for haploHCT continues to be 4.5 mg/kg.

Haploidentical Transplantation with Modified Post-transplantation Cyclophosphamide for Patients with Primary Aplastic Anemia: A Multicenter Experience

Aplastic anemia (AA) is a life-threatening hematological disorder that can be cured by hematopoietic stem cell transplantation. Haploidentical transplantation becomes an alternative choice for patients in the absence of a matched sibling donor. We used a retrospective study aimed to confirm the feasibility of busulfan-based modified post-transplantation cyclophosphamide (PTCY) strategy in haploidentical hematopoietic stem cell transplantation for AA patients. We analyzed the outcomes of 27 patients from 3 clinical centers who had undergone haploidentical transplantation between October 2018 and July 2020. The modified condition regimen consisted of anti-thymoglobulin/antilymphocyte globulin, fludarabine, busulfan and low-dose cyclophosphamide, and high-dose cyclophosphamide, mycophenolate mofetil (MMF) and tacrolimus were administered as graft versus host disease (GVHD) prophylaxis after transplantation. The median follow-up time was 370 (range 65-721) days. One patient developed primary graft failure, and successful engraftment was observed in 96.29% (95% confidence interval [CI], 93.45%-97.91%) of patients. The median times for neutrophil and platelet engraftment were 13 (range 11-18) days and 13 (range 11-28) days, respectively. The most common regimen-related toxicity was bladder toxicity, followed by stomatitis and gastrointestinal toxicity. The cumulative incidence of grade II-IV aGVHD was 25.93% (95% CI, 5.84%-52.64%), whereas the cumulative incidence of grade III-IV aGVHD was 7.4% (95% CI, 0%-52.16%). Chronic GVHD was observed in 3 patients by the end of follow-up. All 27 patients are alive, with a failure-free survival rate of 96.30% (95% CI, 6.49%-99.47%) and GVHD relapse-free survival rate of 88.89% (95% CI, 69.39%-96.28%). Virus reactivation was comparable, with rates of 53.54% for cytomegalovirus (CMV) reactivation and 41.57% for Epstein-Barr virus, but the CMV diseases and post-transplantation lymphoproliferative disorder were rare. Our study using haploidentical transplantation with modified PTCY demonstrated an encouraging result with prolonged survival and reduced complications for aplastic anemia patients.

Post-transplant cyclophosphamide for GVHD prophylaxis compared to ATG-based prophylaxis in unrelated donor transplantation

Post-transplant cyclophosphamide (PTCY) effectively prevents graft-versus-host disease after unmanipulated HLA-haploidentical HSCT. The use of PTCY in the unrelated donor HSCT setting is less explored. We conducted a retrospective study of 132 consecutive patients undergoing a matched or 9/10 mismatched unrelated donor HSCT in 4 centers in Spain, 60 with anti-thymocyte globulin (ATG)-based prophylaxis combined with MTX-CsA, and 72 using a PTCY-based regimen. Peripheral blood stem cells were used as graft in most patients (111 patients, 84%); mMUD donors were balanced between groups. Cumulative incidences of grades II-IV and III-IV acute GVHD at 100 days were lower in the PTCy group (46% vs. 67%, p = 0.008; 3% vs. 34%, p = 0.003), without statistically significant differences in the 2-year cumulative incidence of chronic moderate-severe GVHD. At 2 years, no significant differences were observed in overall survival, event-free survival, cumulative incidence of relapse, and non-relapse mortality. GVHD was the most frequent cause of NRM in the ATG group. No differences were observed between groups in the composite endpoint of GVHD-free and relapse-free survival. In this study, PTCy combined with additional immunosuppression after MUD/mMUD HSCT showed a reduction of aGVHD rate with safety results comparable to those obtained with the ATG-based prophylaxis.

Ex vivo T-cell depletion vs post-transplant cyclophosphamide, sirolimus, and mycophenolate mofetil as graft-vs-host disease prophylaxis for allogeneic hematopoietic stem cell transplantation

OBJECTIVE

To compare the efficacy and safety of CD34+ selected ex vivo T-cell depletion (TCD) vs post-transplant cyclophosphamide, sirolimus, and mycophenolate mofetil (PTCy-Sir-MMF) as graft-vs-host disease (GVHD) prophylaxis.

METHODS

We retrospectively included patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) with either TCD (n = 38) or PTCy-Sir-MMF (n = 91).

RESULTS

Cumulative incidence of neutrophil and platelet recovery was 92% vs 99% (P = .06) and 89% vs 97% (P = .3) in TCD and PTCy-Sir-MMF, respectively. Cumulative incidences of aGHVD grade II-IV, III-IV, and moderate to severe cGVHD were 11% vs 19% (P = .2), 3% vs 2% (P = .9), and 3% vs 36% (P < .001) in TCD and PTCy-Sir-MMF, respectively. The 2-year non-relapse mortality, relapse, disease-free and overall survival were 25% vs 8% (P = .01), 20% vs 16% (P = .2), 55% vs 76% (P = .004), 57% vs 83% (P = .004) for TCD and PTCy-Sir-MMF, respectively. Cumulative incidence of cytomegalovirus and Epstein-Barr infection requiring therapy was 76% vs 40% (P < .001) and 32% vs 0% (P < .001) in TCD and PTCy-Sir-MMF, respectively. PTCy-Sir-MMF platform showed faster T-cell reconstitution.

CONCLUSIONS

PTCy-Sir-MMF provides better survival outcomes but is associated with higher risk of cGVHD compared to TCD.

Reduced dose of MTX for GVHD prophylaxis promotes engraftment and decreases non-relapse mortality in umbilical cord blood transplantation

Although a combination of calcineurin inhibitor and methotrexate (MTX) is used for graft-versus-host disease (GVHD) prophylaxis in umbilical cord blood transplantation (CBT), optimal dose of MTX for CBT remains to be determined.We conducted a retrospective study to evaluate the safety and efficacy of standard-dose MTX (St-MTX, 15 mg/m² on day 1 and 10 mg/m² on days 3 and 6) and mini-dose MTX (Mini-MTX, 5 mg/m² on days 1, 3 and 6) for GVHD prophylaxis in patients who underwent single unit CBT against hematological malignancies.Thirty-two and 26 patients received St-MTX and Mini-MTX, respectively. Cumulative incidence of neutrophil engraftment was significantly higher in the Mini-MTX group than in the St-MTX group (88.5% vs 65.6%, P = 0.00448). Cumulative incidences of grade II to IV and grade III to IV of acute graft-versus-host disease (GVHD) were 34.4% and 6.2% in the St-MTX group, and 34.6% and 7.7% in the Mini-MTX group with no statistical significance. One-year non-relapse mortality (NRM) was significantly lower in the Mini-MTX group compared to the St-MTX group (31.2% vs 3.8%, P = 0.00938), whereas relapse rate was not different between the groups. Multivariate analysis also indicated that Mini-MTX significantly improved engraftment (HR, 0.5359; 95% CI, 0.3082 to 0.9318; P = 0.0270) and reduced NRM (HR, 0.117; 95% CI, 0.0151 to 0.9067; P = 0.040).Our study suggests that GVHD prophylaxis using Mini-MTX in CBT is feasible and associated with improvement of engraftment and reduction in NRM.

Post-Transplant Cyclophosphamide as Sole Graft-versus-Host Disease Prophylaxis Is Feasible in Patients Undergoing Peripheral Blood Stem Cell Transplantation for Severe Aplastic Anemia Using Matched Sibling Donors

High-dose cyclophosphamide (PTCY) after allogeneic hematopoietic cell transplantation (HSCT) has been shown to be effective in preventing graft-versus-host disease (GVHD) after HLA-matched bone marrow transplantation. We performed a phase II study of PTCY given at 50 mg/kg i.v. on days 3 and 4 as the sole GVHD prophylaxis after HSCT for severe aplastic anemia (SAA) in patients receiving granulocyte colony-stimulating factor-mobilized peripheral blood stem cell (PBSC) grafts from HLA-matched related donors after conditioning with fludarabine, CY, and single-dose total body irradiation. Thirty patients with a median age of 29 years (range, 16 to 49) were enrolled in this study. Engraftment was seen in 27 patients (90%) at a median of 16 days (range, 12 to 21) post-HSCT. None of the patients developed veno-occlusive disease of the liver or hemorrhagic cystitis. Grades II to IV acute GVHD was seen in 22% of patients with grades III to IV GVHD in 11.1%. The 2-year cumulative incidence of chronic GVHD was 22.7%. Fourteen patients (46.6%) did not require any further immunosuppression after receiving PTCY. Comparing with 2 historical cohorts of 30 patients each who received cyclosporine and methotrexate (MTX; at 15 mg/m² [MTX15] and 10 mg/m² [MTX10]), the incidence of grades II to IV acute GVHD was lower, albeit not significantly, with the use of PTCY (PTCY, 22.2%, vs MTX15, 37.1%, vs MTX10, 53.8%; P = .056), whereas rates of chronic GVHD were significantly reduced (PTCY, 22.7%, vs MTX15, 63.6%, vs MTX10, 76.2%; P = .013). Viral infections including cytomegalovirus were significantly higher with the use of PTCY (60%) compared with cyclosporine and MTX (MTX15, 23.3%, vs MTX10, 33.3%; P = .008). Overall survival was similar between the 3 groups. We conclude that PTCY as the sole GVHD prophylaxis is associated with low rates of acute and chronic GVHD in patients undergoing PBSC transplant for SAA using HLA-matched donors. This trial is registered at CTRI/2010/091/001480.

Haploidentical bone marrow and stem cell transplantation: experience with post-transplantation cyclophosphamide

Allogeneic blood or bone marrow transplantation (BMT) is a potentially curative therapy for high-risk hematologic malignancies not curable by standard chemotherapy, but the procedure is limited by the availability of human leukocyte antigen-matched donors for many patients, as well as toxicities including graft-versus-host disease (GVHD). Our group has developed the use of high-dose post-transplantation cyclophosphamide (PTCy) to selectively remove alloreactive T cells without compromising engraftment. This protocol has allowed for successful transplantation of human leukocyte antigen (HLA)-haploidentical (haplo) grafts, thus expanding the donor pool for the many patients who would not otherwise be a candidate for this life-saving procedure. In this review we will summarize the data that led to the development of PTCy, then focus on the outcomes of haploBMT trials with PTCy across different transplant platforms for patients with malignant hematologic diseases, and finally we will discuss emerging evidence that suggests equivalency of haploBMT with PTCy compared with more traditional transplants.

Risk Factors, Pattern and Clinical Outcome of Acute Graft Versus Host Disease in Acute Leukemia Patients Undergoing Allogeneic Stem Cell Transplant

We sought to determine risk factors, pattern and outcome of acute graft versus host disease (aGVHD) in seventy-seven acute leukemia patients who underwent allogeneic stem cell transplant at our centre from January 2008 to March 2013. GVHD prophylaxis with cyclosporine-methotrexate or cyclosporine-mycophenolate mofetil was used. Patients were divided in 2 groups, grade II-IV aGVHD (group A) and grade 0-I aGVHD (group B). Incidence of any grade and grade II-IV aGVHD was 44 and 18 %, respectively. The most common site of aGVHD was gastro-intestinal tract (65 %) followed by skin (35 %). Higher total nucleated cell (TNC) dose infused was associated with increased incidence of grade II-IV aGVHD. Incidence of relapse and incidence of slippage of chimerism was 21 and 36 % in group A while 37 and 27 % in group B respectively. Transplant related mortality (TRM) was 21 % in group A and 13 % in group B. Probability of OS and RFS at 4 years was 63 and 34 % in group A compared with 40 and 38 % in group B, respectively. We conclude that higher TNC dose infused is a risk factor for grade II-IV aGVHD with gut being the commonest site. Grade II-IV aGVHD did not have a significant impact on incidence of relapse, TRM and OS.

Impact of graft-versus-host disease prophylaxis on outcomes after myeloablative single-unit umbilical cord blood transplantation

Myeloablative single-unit umbilical cord blood transplantation (sUCBT) using busulfan, thiotepa, fludarabine, and antithymocyte globulin (Grupo Español de Trasplante Hematopoyético [GETH]-2005 protocol) resulted in high rates of engraftment and high antitumor activity. We designed a new graft-versus-host disease prophylaxis, substituting long-term steroids with mycophenolate mofetil together with a slight reduction of antithymocyte globulin (GETH/Gruppo Italiano Trapianto Midollo Osseo [GITMO]-2008 protocol). The results in 145 consecutive patients were compared with those obtained in 88 patients from the previous GETH-2005 trial. The cumulative incidence (CI) of myeloid engraftment at 60 days for patients in the GETH-2005 and GETH/GITMO-2008 trials was 94% and 88%, respectively, at a median time to neutrophil recovery of 19 and 23 days, respectively (P < .0001). In the multivariable analyses, platelet engraftment, acute and chronic graft-versus-host disease, nonrelapse mortality, relapse, and event-free survival were not significantly different. The 3-year event-free survival rate in the GETH/GITMO-2008 trial was 66%, 31%, and 25% for patients transplanted in early, intermediate, and advanced stages of the disease, respectively (P < .0001). This study confirms that myeloablative sUCBT using busulfan-based conditioning is a valuable strategy for patients with hematological malignancies. The use of mycophenolate mofetil apparently had an adverse effect on myeloid engraftment, and therefore a cautious use of this agent is warranted in the UCBT setting.