Incidence Of aGVHD Research Articles

Clinical Outcomes of Patients Receiving 3 Versus 4 Doses of Methotrexate with Concomitant Anti-Thymocyte Globulin; A Single Center Experience

Background: Four doses of methotrexate (MTX) given on day +1, +3, +6, and +11 after allogeneic stem cell transplant (HSCT) is considered one of the most common graft-versus-host disease (GVHD) prophylaxis regimen. However, mucositis and occasionally transaminitis prohibit safe delivery of the fourth dose of MTX. Prior single institution studies showed conflicting results comparing the outcomes of patients who received 3 vs 4 doses of MTX but to our knowledge, the effect of concomitant anti-thymocyte globulin (ATG) use has not been reported. As both ATG and MTX synergistically prevent GVHD via suppressive effects on T-cells. Our institution uniquely incorporates ATG as part of the conditioning regimen for patients receiving HSCT from 10/10 loci match unrelated donors (MUD) and here we report the clinical outcomes between patients who received 3 versus (vs) 4 doses of MTX. Methods: We retrospectively reviewed the charts of patients who underwent HSCT from MUD between 2009 to 2023 at the University of Iowa Hospital and Clinics. We use rabbit ATG (Thymoglobulin R), given at 0.5 mg/kg on day -3, 2 mg/kg on day -2, and 2.5 mg/kg on day -1. MTX is given at 15 mg/m 2 on day +1 and 10 mg/m 2 on day +3, +6 and +11 per institutional protocol. Statistical Analysis: Time was calculated from transplant to recurrence or death for recurrence-free survival (RFS) and overall survival (OS), respectively. For acute and chronic GVHD (aGVHD and cGVHD), time was calculated from transplant to onset of acute and chronic GVHD. Relapse and death were considered as competing events. For non-relapse mortality (NRM), time was calculated from transplant to death; relapse was considered a competing event. Cox regression and Fine-Gray competing risk models were used to estimate the effect of patient, disease, and treatment characteristics on outcomes Results: We identified 296 patients with various indications of HSCT; the most common was acute myeloid leukemia (45.3%). There were 117 and 179 patients who received 3 doses and 4 doses of MTX respectively. Patients characteristics reported in table 1. Median follow-up was 21.9 months (range 0.6 to 150.8). Patients who received 4 doses of MTX were more frequently male (68.2% vs 49.6%, p<0.01), received a reduced intensity (compared to myeloablative) preparative regimen (38.0% vs 23.1%, p<0.01), were older (median 58 vs 54 years, p=0.01), and underwent transplant at an earlier year (median year of transplant 2014 vs 2018, p<0.01). Severe mucositis was the most common reason for omission of the 4 th dose of MTX. Maximum grade of aGVHD was similar between cohorts (p=0.83). A statistically significant difference was not evidenced between patients receiving 4 versus 3 doses of MTX for the following outcomes: aGVHD (HR 1.11, 95% CI 0.84-1.46), grade 3-4 aGVHD (HR 1.41, 95% CI 0.77-2.60), RFS (HR 1.01, 95% CI 0.66-1.56), NRM (HR 1.33, 95% CI 0.84-2.10) and OS (HR 1.21, 95% CI 0.87-1.69). While significant on univariate analysis, MTX dose was not significantly associated with extensive cGVHD (HR 1.44, 95% CI 0.92-2.26) after adjustment for transplant year. Additionally, the median time to neutrophil engraftment was 14 days in both cohorts. Conclusion: When ATG is used concomitantly, omission of the 4 th dose of MTX does not significantly impact the rate of neutrophil engraftment, cumulative incidence of aGVHD, cGVHD, RFS, NRM, and OS after HSCT from MUD. However, a small sample size and non-randomized nature of this study prompts further confirmation study from a large prospective multicenter randomized control trial.

PB CD8 T N and CD4 T EM on day30 after Allo-HSCT Is a Predictive Marker for the Development of aGVHD

Introduction ： Acute GVHD (aGVHD) is a common complication 20-60 days after allo-HSCT and can be life-threatening in some cases. It has been reported to be associated with T-cell immune reconstitution, but the detailed mechanisms are not clear. Early post-transplant lymphocyte recovery is mainly due to homeostatic peripheral expansion (HPE), which is variable depending on various factors such as donor source, recipient's age. T cell-related cytokines, such as sIL-2R , IL-7 and TNFr1 are known biomarkers for the aGVHD, but there are few reports that predict the aGVHD incidence rate using the peripheral blood (PB) lymphocyte subset. We evaluated the effect of PB lymphocyte subset in early post-transplant period on aGVHD. Methods ： We retrospectively analyzed 83 patients (40 in AML, 12 in ALL, 1 in MPAL, 13 in MDS, 2 in MPN, 9 in malignant lymphoma/LPD and 3 in AA) who underwent the allo-HSCT in our hospital from 2013 to 2023. The median age of patients was 44 years (range:17-66). Sixteen received BM, 47 received PB (including 28 with haploidentical (9 with ATG, 19 with PTCY)), and 20 received CB. GVHD prophylaxis was FK506+MTX in 61 patients, CyA+MTX in 3 and MMF+FK506+CY in 19. The median observation period was 495 [38-2983] days. PB lymphocyte subset (Naïve Tcell (T N):CD45RA+CD62L+, Central memory Tcell (T CM) :CD45RA-CD62L+, Effector memory Tcell (T EM) :CD45RA-CD62L-, Effector memory Tcell re-expressed CD45RA (T EMRA) :CD45RA+CD62L-, Th1:CD3+4+CXCR3+CCR6-, Th2:CD3+4+CXCR3-CCR6-, Th17:CD3+4+CXCR3-CCR6+) at day30 (range:28-35) after transplantation were analyzed by FCM. Results ： Twenty-five patients had grade II-IV aGVHD, and 11 had grade Ⅲ-IV aGVHD. Patients with Grade II-IV aGVHD exhibited significantly lower proportion of CD8+T N as compared to non aGVHD groups (GVHD+: 17.7 ± 13.3%; GVHD-: 30.9 ± 16.3%; p < 0.001) . In contrast, the proportion of CD4+T EM and CD8+T EM were higher in the Grade II-IV acute GVHD group (GVHD+: 30.9 ± 23.1%; GVHD-: 21.9 ± 15.6%; p=0.04, GVHD+: 36.1 ± 16.2%; GVHD-: 22.7 ± 14.7%; p < 0.001, respectively). We found a strong statistical correlation between the proportion of CD8+T N and CD8+T EM. The cumulative incidences of Grade II-IV and III -IV acute GVHD at day + 100 for CD8+T N <20% group was 56.9% and 29.6% compared with 14.2% and 6.3% for the CD8+T N >20% group (p < 0.001 and p < 0.01). Similarly, the cumulative incidences of Grade II-IV and III -IV acute GVHD at day + 100 for CD4+T EM >30% group was 48.1% and 32.6% compared with 22.2% and 5.9% for the CD4+T EM <30% group (p= 0.02 and p < 0.01). Two-year NRM was higher in the CD8+T N <20% group than in the CD8+T N >20% group (26.3% vs 4.2%, p=0.008). The two-year cumulative incidence of relapse (CIR) was comparable between the two groups, but tended to be lower in the mismatched CR group (CD8+T N <20%: 33.1% versus CD8+T N >20%: 43.4%, p=0.31). Conclusion ： PB CD8 T N and CD4 T EM fraction on day30 is a predictive biomarker for the development of acute GVHD.

A Parallel Comparison of the Safety and Efficacy of Allogeneic Hematopoietic Stem Cell Transplantation for Refractory and Relapsed T-ALL/Lbl Patients Who Achieved Complete Remission with CD7 CAR-T Versus Patients Who Achieved First Complete Remission with Chemotherapy before Transplantation

Introduction We have developed a fratricide-resistant CD7 CAR-T cells from bulk T cells transduced with CD7 CAR without gene editing or additional gene transfer, named naturally selected CD7 CAR-T (NS7CAR-T). NS7 CAR-T therapy has shown a robust complete remission (CR) rate in patients with refractory or relapsed (R/R) T-cell acute lymphoblastic leukemia and T-cell lymphoblastic lymphoma (T-ALL/LBL). Nonetheless, the risk of relapse remains a challenge post-CD7 CAR-T therapy alone, suggesting the potential benefits of consolidation allogeneic hematopoietic stem cell transplantation (allo-HSCT). The question remains whether CD7 CAR-T therapy could increase the incidence of post-transplant complications. Here we conduct a parallel study to compare the safety and efficacy of allo-HSCT in R/R T-ALL/LBL patients who achieved CR with NS7 CAR-T therapy vs those who reached first CR (CR1) using chemotherapy prior to transplantation. Methods Between November 2020 and January 2023, a total of 223 consecutive patients with T-ALL/LBL who underwent allo-HSCT at our center were retrospectively analyzed. Patients who met the following criteria were included in this parallel study: 1) underwent the first allo-HSCT in our hospital, 2) achieved CR before transplantation either from NS7CAR-T therapy or CR1 from chemotherapy (Fig. 1). A total of 139 patients met the criteria for analysis and underwent allo-HSCT after achieving CR either from NS7CAR-T therapy (n=43) or chemotherapy (CR1=96). The median patient age at the time of transplantation was 15 years (range: 1-51 years). The median follow-up time was 370 days (2-941 days). CD7 CAR-T patients were from two clinical trials registered at www.clinicaltrials.gov NCT04572308, NCT04916860. Transplant donor types included sibling identical (n=12), haploidentical (n=110), and unrelated donors (n=17). We used total body irradiation (TBI)-based conditioning regimens (n=128) or Busulfan/Melphalan-based regimens (n=11). To prevent graft-versus-host disease (GVHD), we used ATG along with a short-term regimen combining methotrexate, cyclosporine/tacrolimus, and mycophenolate mofetil. Results The characteristics of patients from both groups are detailed in Table 1. The median interval between CD7 CAR-T treatment and transplantation was 59 (39-131) days. Within the CAR-T group, 16 patients had primary refractory disease, 18 had relapsed disease and 9 in minimal residual disease (MRD)-positive status in bone marrow before CD7 CAR-T therapy. Prior to CAR-T therapy, 55.8% (24 patients) had extramedullary lesions. In comparing the CAR-T and chemotherapy CR1 groups, we observed no significant differences in long-term efficacy post-allo-HSCT. The 2-year leukemia-free survival (LFS) rates were 64.9 (95% CI, 49.1-79.2)% and 69.8 (95% CI, 59.0-79.6)% (p=0.340); the 2-year overall survival (OS) rates were 64.1 (95%CI, 48.0-78.6)% and 71.8 (95%CI, 60.5-81.9)% (p=0.107); the 2-year relapse incidence (RI) rates were 9.3 (95%CI, 3.7-23.7)% and 11.5 (95%CI, 6.4-20.7)% (p=0.873); and the 2-year non-relapsed mortality (NRM) rates were 28.3 (95% CI, 16.9-47.4)% and 21.6 (95% CI, 13.9-33.4)% (p=0.244), for the CD7 CAR-T and non-CAR-T groups, respectively. The incidence of all grades of acute GVHD (aGVHD) 37.2 (95%CI, 25.2-54.9)% vs. 42.1 (95%CI, 33.3-53.3)% did not significantly differ between the CAR-T and non-CAR-T groups. A trend toward an increased rate but no P significance was observed in Grade 3-4 aGVHD incidence of 20.93 (95%CI, 11.7-37.4)% vs. 9.5 (95%CI, 5.1-17.6)% (p=0.139). One-year incidences of moderate to severe chronic GVHD (cGVHD) were 12.2 (95%CI, 5.4-28.0)% and 18.0 (95%CI, 11.5-28.0)% (p=0.357) in the CD7CAR-T and non-CAR-T groups, respectively (Table 2). No statistically significant differences were detected in the occurrences of transplant-associated thrombotic microangiopathy (TA-TMA), CMV, EBV, and HHV-6 infections between the two groups. Upon analyzing, we found that r/r patients who received allo-HSCT after achieving remission with NS7 CAR-T had a similar OS to CR1 patients (Fig. 2). Conclusions Our parallel study showed that T-ALL/LBL patients, who achieved CR via CD7 CAR-T therapy followed by a consolidation allo-HSCT, had similar favorable OS and LFS compared to patients who underwent allo-HSCT in the CR1 state induced by chemotherapy. This was achieved without increasing the incidence of GVHD, infections, or TA-TMA.

Easix Score Correlates With Endothelial Dysfunction Biomarkers and Predicts Risk of Acute Graft-Versus-Host Disease After Allogeneic Transplantation

Plasma biomarkers of endothelial dysfunction have been postulated for the diagnosis and prognosis of acute graft-versus-host disease (aGVHD). However, their use is not validated in clinical practice yet. The endothelial activation and stress index (EASIX), a simple score based on routine laboratory parameters, is considered to be an indirect marker of endothelial damage. High value of EASIX was correlated with worse non-relapse mortality (NRM) and overall survival (OS) and a high risk of sinusoidal obstructive syndrome and transplant-associated thrombotic microangiopathy (TA-TMA). This study investigates the predictive value of plasma biomarkers and the EASIX score for the prediction of aGVHD. We assessed vascular cell adhesion molecule-1 (VCAM-1), tumor necrosis factor receptor 1 (TNFR1), and VWF:Ag plasma levels and the EASIX score before allogeneic hematopoietic stem cell transplantation (allo-HSCT) and on days 0, 3, 7, 14, and 21 in an experimental cohort (n = 33). EASIX was transformed to a base-2 logarithm to perform the analysis. For the most relevant biomarkers, we estimate the optimal cutoff values and the discriminatory ability to differentiate patients with high-risk of aGVHD. The conclusions obtained in the experimental cohort were validated in a large cohort of 321 patients at the same institution. Plasma biomarkers and EASIX showed similar post-transplantation dynamics consisting of a progressive increase. Multivariate analysis showed an association between high TNFR1 levels and Log-2 EASIX score on day 7 after transplantation with an increased likelihood of developing aGVHD (hazard ratio [HR] = 1, P = .002; HR = 2.31, P = .013, respectively). Patients with TNFR1 ≥1300 ng/mL (HR = 7.19, P = .006) and Log2-EASIX ≥3 (HR = 14.7, P <.001) at day 7 after transplantation were more likely to develop aGVHD with high predictive accuracy (C-index of 74% and 81%, respectively). In the validation cohort, patients with Log2-EASIX ≥3 on day 7 after transplantation presented a significantly higher incidence of grade II-IV aGVHD (HR = 1.94, P = .004) independent of GVHD prophylaxis (HR = 0.38, P = .004), conditioning regimen (HR = 0.59, P =.02) and type of donor (HR = 2.38, P = .014). Differential degree of endothelial damage can be measured using both EASIX score and plasma biomarkers in the early post-transplantation period. Patients at risk of developing aGVHD could be easily identified by a high EASIX score. Both indicators of endothelial activation represent a promising approach to predict aGVHD.

Reaching the cyclosporine a level target slowly in four weeks correlates with better prognosis for Chinese patients after allogeneic haematopoietic cell transplantation

ABSTRACTObjectivesThis study investigated the impact of early cyclosporin A (CsA) initiation (day −5) on the risk of acute graft versus host disease (aGvHD) after allogeneic haematopoietic cell transplantation (allo-HSCT).MethodsSixty-seven leukaemia patients who underwent allo-HSCT were investigated. The correlation between the CsA level in the first four weeks and the following indices was examined: GvHD, cumulative incidence (CI) of GvHD, CI of relapse at month 18, and non-relapse mortality (NRM) at month 18.ResultsA significant association between aGvHD and CsA level in the fourth week after allo-HSCT was observed, with the incidence of aGvHD in the fourth week in the lower level group being higher than that in the higher level group (p = 0.044). The CI of aGvHD was 30.1% and 9.8% at day +90 and 42.3% and 17.1% at day +180 in the lower level and higher level groups, respectively.ConclusionFor Chinese patients, early introduction and reaching the target CsA concentration within four weeks after allo-HSCT have a positive effect on preventing GvHD, especially in the fourth week after HSCT. Compared to the Western population, the target CsA concentration is lower and the time required to reach the target (within 4 weeks) is longer in the Chinese population (274.75 ng/mL).

Outcome improvement over time in reduced intensity conditioning hematopoietic transplantation: a 20-year experience.

The current study includes all consecutive patients (N = 484) who received a reduced-intensity conditioning regimen (RIC) allogeneic hematopoietic stem cell transplantation in our center from 1999 to 2020. Conditioning regimens were based on fludarabine with melphalan or busulfan, with low-dose thiotepa and pharmacological GVHD prophylaxis consisted of cyclosporine A (CsA)-methotrexate (MTX)/mofetil (MMF) (n = 271), tacrolimus-sirolimus (n = 145), and post-transplantation cyclophosphamide (PTCy)-tacrolimus (n = 68). The median time of overall follow-up in survivors was 8years (1-22years) and was at least 3years in all three GVHD prophylaxis groups. Thirty-three percent had a high or very high disease risk index, 56% ≥ 4 European bone marrow transplantation risk, and 65% ≥ 3 hematopoietic stem cell transplantation comorbidity index score-age score. Neutrophil and platelet engraftment was longer for PTCy-tacro (p 0.0001). Cumulative incidence of grade III-IV aGVHD was 17% at 200days, and that of moderate-severe cGvHD was 36% at 8years. GVHD prophylaxis was the only prognostic factor in the multivariable analyses for the development of aGVHD and moderate-severe cGVHD (p 0.0001). NRM and relapse incidences were 29% and 30% at 8years, while OS and PFS rates were 43% and 39% at 8years. At 3years, OS was highest in the PTCy-tacro group (68%) than in the tacro-siro (61%) and CsA-MTX/MMF (49%) cohorts (p < 0.01). In the three groups, respectively, the 200-day incidence of grade III-IV aGvHD (6% vs. 12% vs. 23%) and 3-year moderate-severe cGVHD (8% vs. 40% vs. 38%) were lower in the PTCy cohort. These better outcomes were confirmed in multivariable analyses. Based on our recent results, the PTCy could be considered as a real GvHD prophylaxis in the RIC setting due to improve best 3-year GvHD and survival outcomes.

Post-Transplant Cyclophosphamide Equalizes Clinical Outcomes of Allogeneic Hematopoietic Cell Transplantation across Racial and Ethnic Populations

Background Despite being the only curative option for many hematologic malignancies, allogeneic hematopoietic cell transplant (HCT) has been plagued by health disparities due to differences in access, donor availability, and outcomes across racial and ethnic minority populations (REM) (Gragert, NEJM, 2014). Even when a matched donor is available, HCT outcomes for REM patients are historically worse compared to non-Hispanic white (NHW) patients. (Landry, Stem Cell Investigation, 2021). The development of post-transplant cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis has led to increased use of HLA haploidentical (haplo) or mismatched unrelated donors (MMUD) with comparable outcomes to HLA matched HCT (McCurdy, Advances in Hematology, 2015). While PTCy allows for almost every transplant-eligible REM patient to have a suitable donor, there is limited data evaluating whether this transplant platform results in similar outcomes for REM patients compared to NHW patients. The aim of this study was to investigate if disparities in transplant outcomes still exist between REM patients and NHW patients who received an HLA mismatched transplant with PTCy. Methods We retrospectively analyzed 302 consecutive adult patients who underwent haplo or MMUD HCT with PTCy at Moffitt Cancer Center between 2014 and 2022. All endpoints were compared between four groups: NHW, Hispanic-White, Black, and Other (Asian, biracial, or multiracial.) Results In this cohort, 59% (n=178) of patients identified as NHW, 14% (n=41) as Hispanic-White, 16% (n=48) as Black, 7% (n=21) as biracial or multiracial, and 4% (n=11) identified as Asian. Most patients were male (57%). The median age of all patents was 58. The most common indication for transplant was acute myeloid leukemia (48%), myeloablative conditioning (MAC) was utilized in 42%, and 89% received peripheral blood stem cells grafts. REM patients were more likely to be &amp;lt;65 years of age (60% vs 66-90%, p&amp;lt;0.001), female (36% vs 50-54%, p=0.04), and receive MAC conditioning (33% vs 40-71%, p&amp;lt;0.001). Median follow-up was 21 months. In all clinical outcomes, no significant differences were observed between NHW and REM patients. At day 100, the cumulative incidence of Grade II-IV aGVHD was 37% [95% CI 30-44%] for NHW patients, 32% [95% CI, 18-46%] for Hispanic-White patients, 27% [95% CI, 15-40%] for Black patients, and 26% [95% CI, 13-41%] for patients of Other races (p= 0.38). The cumulative incidence of moderate to severe cGVHD at 2 years was 21% [95% CI 15-28%] for NHW patients, 25% [95% CI, 13-39%] for Hispanic-White, 17% [95% CI, 7.8-29%] for Black, and 27% [95% CI, 13-42%] for patients of Other races (p = 0.80). At 2 years, the probability of relapse was 25% [95% CI 19-32%] for NHW patients, 24% [95% CI, 12-39%] for Hispanic-White patients, 27% [95% CI, 15-40%] for Black patients, and 18% [95% CI, 7.1-33%] for patients of Other races (p = 0.97). During the same time interval, non-relapse mortality (NRM) for NHW patients, Hispanic-White patients, Black patients, and patients of Other races were 19% [95% CI, 13-25%], 15% [95% CI, 5.9-27%], 19% [95% CI, 9.4-32%], and 24% [95% CI, 11-40%] (p = 0.73), respectively. At 2 years, relapse free survival (RFS) was 56% [95% CI 49-64%] for NHW patients, 61% [95% CI, 47-79%] for Hispanic-White patients, 54% [95% CI, 41-71%] for Black patients, and 58% [95% CI, 43-78%] for patients of Other races (p = 0.77). Comparably, OS at 2 years for NHW, Hispanic-White patients, Black patients, and patients of Other races was 64% [95% CI, 57-72%], 72% [95% CI, 60-88%], 53% [95% CI, 40-71%], and 63% [95% CI, 49-83%] respectively after two years (p = 0.92). In multivariate analysis, race/ethnicity had no significant impact on incidence of Grade II-IV aGVHD (p= 0.40), moderate/severe cGVHD (p = 0.80), rates of relapse (p = 0.86), NRM (p= 0.77), RFS (p = 0.69), or OS (p = 0.64) (Table). Conclusions These results show that the use of HLA mismatched donor HCT with PTCy achieves comparable clinical outcomes between REM and NHW patients. Our study suggests that PTCy effectively contributes to equitable healthcare in the setting of allogeneic HCT for REM patients.

Effectiveness and Safety of Rabbit Anti-Thymocyte Globulin Versus Non-Anti-Thymocyte Globulin Regimens for Graft-Versus-Host Disease Prophylaxis: A Systematic Review and Meta-Analysis

Introduction:Graft-versus-host disease (GVHD) is a serious complication after allogeneic hematopoietic stem cell transplant (HSCT), limiting its success. Meta-analyses have confirmed clinical efficacy and safety of several types of anti-thymocyte globulins (ATGs) in GVHD prophylaxis; however, there are no meta-analyses assessing the efficacy of rabbit anti-thymocyte globulin (rATG; Thymoglobulin ®) in particular. This study assessed the effectiveness and safety of rATG relative to non-ATG prophylaxis regimens for acute GVHD (aGVHD) or chronic GVHD (cGVHD) based on randomized controlled trials (RCTs) and observational studies. Methods:A literature search was conducted in MEDLINE, Embase, Cochrane Central, and the Web of Science using the PICOS framework to identify studies published until June 2022 focusing on the prophylaxis use of rATG in GVHD. The United States and European Union clinical trial registry databases were also searched to identify unpublished data from studies. Efficacy outcomes included incidences of aGVHD (Grade II-IV and Grade III-IV), cGVHD (mild to severe and moderate to severe) and overall survival. Safety outcomes included the incidence of relapse, cytomegalovirus (CMV) infection, and Epstein-Barr virus (EBV) reactivation. Pre-specified subgroups of interest included donor type, and stem cell source (an unrelated peripheral blood [PB]/bone marrow [BM] transplant, a related PB/BM transplant, or a mixed unrelated and related PB/BM transplant). All analyses present the overall effect, the effect by subgroups, and the percentage contributing to the overall effect. Results: Overall, 4295 records were retrieved from the databases and hand searching (1000 from PubMed, 1700 from Embase, 1419 from the Web of Science, 155 from the Cochrane Central, 20 from the clinical trial registry databases and 1 from hand searching). After screening, 45 studies (6 RCTs, 35 retrospective studies and 4 prospective observational studies) published between 2001 and June 2022 were included in this review. Among the 45 studies, 39 reported aGVHD Grade II-IV, 33 reported aGVHD Grade III-IV, 33 reported mild to severe cGVHD, 31 reported moderate to severe cGVHD, and 41 reported overall survival ( Table). Use of rATG for GVHD prophylaxis resulted in a significant 24% reduction in Grade II-IV aGVHD (RR=0.76; 95% CI: 0.68-0.85) and a significant 43% reduction in Grade III-IV aGVHD (RR=0.57; 95% CI: 0.49-0.65) compared with non-ATG arm across all donor types. Similarly, a 35% reduction was observed in mild to severe cGVHD (RR=0.65; 95%CI: 0.57-0.74) and a significant 48% reduction (RR=0.52; 95% CI: 0.45-0.60) was observed in moderate to severe cGVHD across all donor types. Use of rATG decreased overall mortality by 9% (RR=0.91; 95% CI: 0.85-0.99). Among the subgroups, the decrease in mortality was statistically significant in unrelated PB/BM transplant donors. The incidence of relapse was reported in 36 studies, with an overall 18% increase (RR=1.18; 95% CI: 1.08-1.30) for patients treated with rATG. However, among the subgroups, the incidence of relapse was comparable between rATG and non-ATG prophylaxis arms for all types of donors. rATG and non-ATG prophylaxis regimens were comparable in terms of CMV infection (RR=1.00; 95% CI: 0.88-1.15). The incidence of EBV infection was significantly higher in the rATG arm (RR=2.53; 95% CI: 1.54-4.17) than that in the non-ATG arm. Conclusions: This meta-analysis provides useful information to support patients and health-care providers in making treatment decisions for the prevention of aGVHD or cGVHD after allogeneic HSCT. rATG demonstrated significant reductions in the incidence of both aGVHD and cGVHD and increased the overall survival across donor types and stem cell sources despite slightly increased risk of relapse in rATG arm versus non-ATG arm.

Phase I/II Study of Reduced Dosing of Post-Transplantation Cyclophosphamide (PTCy) after HLA-Identical Peripheral Blood Hematopoietic Stem Cell Transplantation

Introduction Post-transplant cyclophosphamide (PTCy)-based prophylaxis for acute graft versus host disease (aGvHD) has become a standard protocol in HLA haploidentical bone marrow transplantation. Preliminary evidence indicates that compared to the standard dosage (50 mg/kg on days +3 and +4 post-transplantation), a regimen of half the typical cyclophosphamide dosage is both feasible and effective. However, the optimal dosage and timing of PTCy for aGvHD prophylaxis in a HLA identical setting, using peripheral stem cells as the graft, remain unknown. This study aims to investigate the efficacy and safety of a reduced PTCy dosage regimen in patients undergoing peripheral blood stem cell transplants (PBSCT) with HLA indentical donors. Methods This prospective, single-center phase I/II study enrolled patients scheduled for PBSCT with HLA identical donors. The aGVHD prophylaxis regimen comprised PTCy on days +3 and +4, followed by cyclosporine initiation from day 5 post-transplant. In the phase I stage, an initial cohort of five patients received PTCy at a dosage of 50 mg/kg/day on days +3 and +4 (designated as dose level 1, DL1). This was followed by a 3+3 dose de-escalation design with subsequent dose levels as follows: DL2, 50 mg/kg on day +3 and 25 mg/kg on day +4; and DL3, 25 mg/kg on both day +3 and +4. The dose-limiting toxicity for this de-escalation was defined as the occurrence of grade III-IV aGVHD within the first 100 days post-transplantation. The phase II stage comprised an expansion cohort, which was based on the optimal dose identified during phase I. aGvHD classification was established using the Mount Sinai Acute GVHD International Consortium (MAGIC) criteria, while chronic GvHD (cGvHD) was assessed per the latest National Institutes of Health Consensus on cGvHD. Patients were closely followed-up at +1, +2, +3, +4, +6, +9, +12, +18, and +24 months post-transplant. Results In the first stage, a total of 11 patients (5 in DL1, 3 in DL2, and 3 in DL3) were included, and no patient developed grade III-IV aGVHD. Based on this, DL3 was selected as the PTCy dose for phase II, which comprised 18 patients. Overall, 29 patients (17 females, 12 males) with a median age of 39 years (range 17-65) were included, and the median follow-up duration was 12.7 months (range 2.2-22.1). Patient and disease characteristics are summarized in Table 1. By day +30 post-ASCT, all patients achieved complete remission (CR) and minimal residual disease (MRD) clearance. No patient developed grade III-IV aGVHD within 100 days post-transplantation. There was no significant difference in the neutrophil and platelet engraftment interval among the three groups (Figure 1A, B). Among the 21 patients who received the DL3 dose of PTCy, the estimated cumulative incidence of grade II to IV aGVHD at day +100 was recorded at 28.6%, and the incidence of aGVHD at day +100 presented no difference among the three DL groups (Figure 1C). In addition, 1 patient in DL3 developed grade IV intestinal aGVHD on day +141 and died one month later. The estimated 1-year cumulative incidence of hemorrhagic cystitis (HC) and cytomegalovirus (CMV) reactivation was 19.3% and 19%, respectively (Figure 1D). Five patients (all in DL3) experienced relapse, with a median interval of 6.7 months and an estimated 1-year cumulative incidence of 10.6%. A total of 5 fatalities occurred during our study (1 in DL1, and 4 in DL3), 1 due to relapse, 2 from COVID-19-associated pulmonary aspergillosis, 1 from severe septicemia and 1 due to grade IV aGVHD as mentioned above. The estimated 6-month cumulative incidence of NRM was 9.5%, presenting no difference among the three DL groups (Figure 1E). Among the 20 evaluable patients, the estimated 1-year cumulative incidence of chronic GVHD (cGVHD) and moderate cGVHD was 37.3% and 16% (Figure 1F), respectively, with no severe cGVHD observed. No cases of patient relapse were reported. The estimated 1-year progression-free survival (PFS) and overall survival (OS) were 61.2% and 80.4%, respectively (Figure 1G). Conclusion The findings of this study substantiate that a two-day regimen of PTCy at 25 mg/kg/day serves as an effective and safe prophylactic measure against aGVHD, comparable to the standard dosing protocol. However, to definitively establish whether the de-escalated PTCy dosage provides superior outcomes to the standard regimen, longer-term follow-up and comparative studies are warranted.

Combining Low-Dose Post-Transplant Cyclophosphamide(PTCY) with Anti-Thymocyte Globulin(ATG) for Prophylaxis of Graft-Versus-Host Disease in Alternative-Donor Hematopoietic Stem Cell Transplantation for β-Thalassemia Major

Background ： The 5-year overall survival rate (OS) for children with thalassemia major who undergo allogeneic stem cell transplantation is 90% and the event-free survival (EFS) rate is 86%. Due to the limited availability of matched sibling donors, the proportion of transplantations from alternative donors is increasing, particularly from haplo-identical donors. Post-transplant infections and graft-versus-host disease (GVHD) remain the major causes of mortality, especially in those who receive transplantation from alternative donors. Post-transplant cyclophosphamide (PTCY) has shown outstanding results of GVHD prophylaxis in haploidentical matched related donors transplantation with hematological malignancies. However, there is insufficient clinical evidence for its application in pediatric patients who received transplantation from haplo-identical donors with non-malignant hematological disease. Here, we retrospectively analyzed the results of 40 cases that underwent allogeneic stem cell transplantation from haploidentical matched related donors (Haplo-RD) and unrelated donors (UD) to evaluate the safety and efficacy of the novel regimen in GVHD prophylaxis. Method A total of 40 patients with β-thalassemia major received stem cell transplantation, 10 haploid donors (Group Haplo-RD), and 30 unrelated donors (Group UD). Among Group UD, 15 donors were 1 or 2 HLA locus mismatched, remaining 15 were identically matched. The median age of the patients was 5.5 years, ranging from 2 to 12. The Conditioning regimen mainly consisted of fludarabine, busulfan, cyclophosphamide, and thiotepa. GVHD prophylaxis included ATG 1.5mg/kg×3d, cyclophosphamide (CTX) 25mg/kg×2d, cyclosporin A (CsA), and mycophenolate mofetil (MMF). We analyzed the engraftment rate, GVHD incidence, survival rate, and virus reactivation rate for each group. Results Engraftment rate was 100%, with a median time of 11 (10-15) days for neutrophil implantation and 12 (6-31) days for platelet implantation. All patients achieved complete chimerism on day 30 after transplantation. Three cases (7.5%) suffered from Ⅲ-Ⅳ aGVHD, with one being in the Group Haplo-RD group and two in the Group UD. Four cases (10.0%) of cGVHD were recorded. The overall survival (OS) rate and thalassemia-free survival rate were both 92.5%. In Group Haplo-RD, both the OS and thalassemia-free survival rates were 100%. Eight cases reported cytomegaloviremia but no one developed to CMV disease. The total activation rate for CMV was 20%. Nine cases suffered from BK virus urinary tract infection, resulting in a total activation rate of 22.5%. Detailed results are shown in Table 1 and Figure 1. Discussion Due to the high risk of GVHD and infection, stem cell transplantation from haploidentical and unrelated donors cannot be routine therapy for children with thalassemia major. Standard-dose PTCY regimen significantly increases the risk of CMV and BK infection after transplantation and is not suitable for non-malignant disease. The results have been reported that low-dose PTCY/ ATG can reduce the risk of GVHD as compared with standard-dose ATG in haploidentical donor stem cell transplantation. In our study, the novel GVHD prophylaxis regimen, semi-dose PTCY (25mg/kg×2d) combined with low-dose ATG (1.5mg/kg×3d), was used for stem cell transplantation from haploidentical and unrelated mismatched donors. The incidence of III-IV aGVHD was 7.5% and cGVHD was 10.0%, and there was no rejection of the transplant. The activation rate of CMV and BKV was significantly lower than reported in the literature, and the non-relapse mortality (NRM) after transplantation was significantly reduced. There was no statistical difference in the rate of OS, EFS, aGVHD, and cGVHD between Group Haplo-RD and Group UD. The results provide an effective approach for preventing GVHD and infectious diseases in thalassemia patients who underwent allo-HSCT with high-risk GVHD.

Comparison of Therapeutic Effects between Young Haploidentical Donors and Elderly HLA-Matched Relative Donors for AML Patients Who Undergoing Allogeneic Hematopoietic Stem Cell Transplantation with Conditioning Regime Including ATG

Objective: Donor selection is one of the issues faced in allogeneic hematopoietic stem cell transplantation (allo-HSCT). This study aims to compare the impact of young haploidentical donors and elderly matched relative donors on the outcomes of AML patients undergoing allo-HSCT with conditioning regime including ATG, providing reference for donor selection. Methods: A retrospective analysis was conducted on 708 AML patients who underwent allo-HSCT at our hospital from 2014 to 2021. Among them, 354 patients were included in this study, with 289 patients receiving haploidentical transplantation from donors under the age of 50 (haplo group) and 65 patients receiving fully matched sibling transplantation from donors over the age of 50 (MSD group). Clinical characteristics and transplantation outcomes of both groups of patients and donors were compared. Results: Among the 354 AML-MRC patients, there were 178 males and 176 females, with a median age of 41 (18~56) years. The median follow-up time was 35 (95% CI 30~49) months, and the median overall survival (OS) was 78 (95% CI 23~) months. The 3-year OS rate was 63.1% (95% CI 45.6%~81.4%), the 3-year event-free survival (EFS) rate was 59.0% (95% CI 40.8%~66.1%), the cumulative incidence of relapse (CIR) was 26.8% (95% CI 16.6%~30.0%), and the transplantation-related mortality (TRM) was 22.7% (95% CI 13.2%~33.8%). There were no statistically significant baseline differences between the haplo group and MSD group. The 3-year OS rates for haplo group vs. MSD group were 0.660 (95% CI 0.597-0.731) vs. 0.670 (95% CI 0.558-0.806) (p=0.7), the 3-year EFS rates were 0.620 (95% CI 0.543-0.720) vs. 0.570 (95% CI 0.458-0.656) (p=0.6), and the TRM rates were 0.165 (95% CI 0.121-0.282) vs. 0.134 (95% CI 0.062-0.234) (p=0.6). The CIR rates were 0.199 (95% CI 0.147-0.250) vs. 0.275 (95% CI 0.165-0.397) (p=0.196), and the cumulative incidence of grade II-IV aGVHD was 0.288 (0.237-0.342) vs. 0.309 (95% 0.200-0.424) (P=0.891). The incidence of cGVHD was 0.140 (0.099-0.188) vs. 0.250 (95% 0.147-0.367) (p=0.032). Conclusion: For AML patients undergoing allo-HSCT with conditioning regime including ATG, compared to elderly fully matched donors, young haploidentical donors may reduce the occurrence of post-transplant cGHVD.

Allogeneic Hematopoietic Cell Transplantation with Sequential-Based Conditioning in Refractory / Relapsed Acute Myeloid Leukemia: Experience from a Single Institution

INTRODUCTION: Despite improvements in the treatment and outcomes of patients with acute myeloid leukemia (AML), in nearly 10-20% of the cases, a morphological remission (CR) after administrating induction regimens is not achieved. In other cases, and despite initial CR, early disease relapse may occur, with only a minority of patients durably benefiting from salvage regimens. Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative strategy for patients with relapsed / refractory (R/R) AML. However, the prognostic of these patients after allo-HCT remains dismal, with reported survival rates ranging from 20% to 35% in different publications. Allo-HCT using peripheral blood and sequential-based conditioning regimens has been the transplant platform used at our institution for R/R AML during the last decade. During the study period the use of post-transplant cyclophosphamide (PTCY) combined with tacrolimus (TK) has been implemented on this allo-HCT setting. This study evaluates the results obtained from a single institution obtained from using sequential allo-HCT for patients with R/R AML, and the effectiveness of having implemented the use of PTCY in this type of transplant. Very few studies have evaluated the safety of including PTCY-based in sequential-based conditioning allo-HCTs. METHODS: This study includes the 21 patients with R/R AML who underwent allo-HCT with sequential-based conditioning regimens at our institution between 2011 and 2022. Retrospective data were collected during June 2023. Sequential regimens combined fludarabine (150 mg/m2), cytarabine (2 g/m2 x 5 days), and idarubicin (12 mg/m2 x 3 days) chemotherapy with low doses of Bu (n=3), melphalan (n=17), or treosulfan (n=1). Six adults transplanted after November 2016 received PTCY (50mg/kg/24h) on day +3 and +4 followed by TK from day +5 to day +90 for GvHD prevention. RESULTS: The main baseline characteristics of the study cohort and according to the GVHD prophylaxis are shown in Table 1 . The median age was 53 years (range 31-68), 11 (52%) patients were males, and all patients had R/R AML after having received at least one line of induction chemotherapy with curative intent. Fourteen (66.7%) patients received grafts from HLA-matched donors, and 7 (33.3%) from 9/10 HLA mismatched unrelated donors (MMUD). Baseline characteristics between patients who received PTCY and those who did not were balanced, except for the proportion of allo-HCT performed from MMUD which was higher in the PTCY group (66.7% vs. 20.0% p=0.03). Post-transplant results are shown in Table 2. All patients engrafted (100%). Patients who received PTCY experienced similar median of days to neutrophil engraftment (18 vs. 15 days, P=0.103) and a longer median of time to platelet engraftment (25 vs. 13 days, P=0.046). The day +100 cumulative incidences (CI) of grade II-IV and III-IV aGVHD, and 2-year CI of moderate/severe cGVHD were 33.3%, 0% and 0% for patients who received PTCY-TK, and 40% (p=0.823), 33% (p=0.118), and 40.4% (p=0.099) for those who did not. During the first 2-years after allo-HCT, 8 (38%) out of 21 patients died and 7 (21%) relapsed. The main causes of death were relapse (n=4, 19%) and infection (n=2, 9.5%), and the 2-year OS, PFS, NRM and CIR were 61.5%, 51.9%, 14.3%, and 33.3%. As shown in Table 2 patients who received PTCY had comparable rates of OS (2-y: 50.0% vs. 66.7%, p=0.903) and RFS (2-y: 50.0% vs. 53.3%, p=0.873) and those who did not. In addition, and although no patient who received PTCY died secondary to transplant-related toxicity (2-y 0 vs. 20%, p=0.254), a non-significant trend to higher cumulative incidence of relapse (2-y: 50.0% vs. 26.7%, p=0.282) was observed in this group of patients. Lastly, a non-significant trend to higher GRFS was documented in patients who received PTCY (2-y: 50.0% and 25.0%, p=0.266). CONCLUSIONS: At our institution, 50% of the patients with R/R AML going thought allo-HCT performed using sequential-based conditioning regimens survived after two years. The implementation of PTCY as part of the GVHD prophylaxis results decreased rates clinically relevant GVHD and NRM, resulting on a trend to better GRFS. Although the results provided by this analysis suggest that using PTCY in this allo-HCT is safe and effective, caution is still recommended considering the trend to higher relapse rates observed among these patients and the limited sample size.

Post-Transplant Cyclophosphamide, Tacrolimus or Cyclosporine a and Mycophenolate Mofetil Compared to Anti-Thymocyte Globulin tacrolimus or Cyclosporine a and Methotrexate Combinations As Graft- versus -Host Disease Prophylaxis Post Allogeneic Stem Cell Transplantation from Sibling and Unrelated Donors in Patients with Acute Myeloid Leukemia: a Study on Behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow

Background: Recently, the BMT CTN 1703 phase III study compared post-transplant cyclophosphamide with tacrolimus with mycophenolate mofetil (PTCy/TAC/MMF) to TAC /methotrexate (MTX) as graft- versus-host disease (GVHD) prophylaxis post allogeneic transplantation (HSCT), demonstrating a lower incidence of severe acute (a) GVHD and chronic (c) GVHD and better GVHD-free, relapse-free survival (GRFS). The control arm did not include anti-thymocyte globulin (ATG), used in many centers for GVHD prophylaxis. Methods: The study aim was to compare PTCy with TAC or cyclosporine A (CSA) and MMF (PTCy/TAC or CSA &amp; MMF) to ATG combined with TAC or CSA and MTX (ATG/TAC or CSA &amp; MTX) in acute myeloid leukemia (AML) patients (pts) undergoing HSCT from matched siblings (MSD) or 9-10/10 unrelated donor (UD) in first complete remission (CR1). Statistical tests included a multivariate analysis (MVA) adjusting for potential confounding factors using a Cox proportional-hazards regression model for main outcomes. . Results: 6050 pts met the inclusion criteria, 402 received PTCy/TAC or CSA &amp; MMF and 5648 received ATG/TAC or CSA &amp; MTX as GVHD prophylaxis. Median follow-up was 23.4 (IQR, 20.3-24.9) and 41.8 (IQR, 39.6-43.3) months (p&amp;lt;0.0001). The median year of the transplant was 2018 (2010-2020) and 2016 (2007-2020) (p&amp;lt;0.0001). Pts in the PTCy/TAC or CSA &amp; MMF group were younger, with a median age of 48.7 (range 18-5.6) versus 51.5 (8-77.8) years (p=0.024). The diagnosis was de novo AML in 84.1% vs 85.3% and secondary (s) AML in 15.9% vs. 14.7% (p=0.49). The cytogenetic risk was categorized as intermediate (70.9% vs. 67.1%), adverse (22.2% vs. 25.7 %), and favorable (6.9% vs. 7.2%) for pts in the PTCy/TAC or CSA &amp; MMF and ATG/TAC or CSA &amp; MTX groups, respectively (p=0.35) (data missing for 2214 pts). Karnofsky performance status (KPS) did not differ between the groups. There was a higher frequency of pt cytomegalovirus (CMV) seropositivity and female (F) donor to male (M) pt combination in the PTCy/TAC or CSA &amp; MMF group, 77.8% vs. 71.8% (p=0.009) and 18.4% vs. 14.4% (p=0.029). More pts in the PTCy/TAC or CSA &amp; MMF group received reduced intensity conditioning (RIC) 51.5% versus 41.1% in the ATG/TAC or CSA &amp; MTX group, respectively (p&amp;lt;0001). Day 60 neutrophil engraftment (ANC &amp;gt;0.5 x 10 9/L) was 98.7% vs. 98.6% (p=0.84). Day 180 incidence of a GVHD grade II-IV and III-IV was 21.2% vs. 20.4% (p=0.92) and 8.1% vs. 6% (p=0.1), in pts receiving PTCy/TAC or CSA &amp; MMF versus the ATG/TAC or CSA &amp; MTX GVHD prophylaxis, respectively. The 2-year (y) total and extensive chronic (c) GVHD were 33.7% vs. 30% (p=0.09) and 10.7 % vs. 11.2% (p=0.81), respectively. GVHD was the cause of death in 11.6% vs. 13.9% of pts who died. In the MVA, both aGVHD (grade II-IV or III-IV) and cGVHD (total or extensive) did not differ between the groups with hazard ratios (HRs) =1.15 (95% CI 0.86-1.53, p=0.35), HR=0.87 (95% CI 0.56-1.34, p=0.52), HR=0.91 (95% CI 0.7-1.18, p=0. 47 and HR=1.51 (95% CI 0.96-2.36, p=0.074). Two-y NRM was significantly lower in pts that received PTCy/TAC or CSA &amp; MMF versus ATG/TAC or CSA &amp; MTX for GVHD prophylaxis, HR=1.57 (95% CI 1.07-2.3, p=0.022). Other HSCT outcome parameters did not differ between the groups. The HR for 2-y RI was 0.99 (95% CI 0.77-127, p=0. 93). The HRs for 2-y leukemia-free survival (LFS), overall survival (OS), and GRFS were HR=1.15 (95% CI 0.94-1.42, p&amp;lt;0.18), HR=1.18 (95% CI 0.94-1.49, p=0.16) and HR=1.12 (95% CI 0.93-1.36, p=0.22), respectively. Donor type and conditioning regimen were poor prognostic factors for grade II-IV, III-IV aGVHD, and total and extensive cGVHD. For cGVHD, additional poor prognostic factors were F donor to M pt combination and pt CMV seropositivity. Poor prognostic factors for LFS, OS, and GRFS were 9/10 UD, age (by 10 y), sAML, adverse-risk cytogenetics, lower KPS, and pt CMV seropositivity. For NRM, factors were the same apart from cytogenetics risk which was not a prognostic factor. In addition, time from diagnosis to HSCT was a prognostic factor for NRM and RI. Other poor prognostic factors for RI were lower KPS and pt CMV seropositivity. Conclusions: In this registry-based retrospective analysis, comparing PTCy in combination with TAC or CSA and MMF to ATG in combination with TAC or CSA and MTX as GVHD prophylaxis, we observed a similar incidence and severity of both aGVHD and cGVHD. NRM was significantly lower with the PTCy-based GVHD prophylaxis, while all other transplant outcome parameters were similar.

Evaluation of the Use of Post-Transplant Cyclophosphamide in Patients Diagnosed of Myelodysplastic Syndrome Who Undergo Allogenic Hematopoietic Cell Transplantation

INTRODUCTION Allogeneic hematopoietic cell transplantation (allo-HCT) remains the only potentially curative strategy for patients with MDS. Although the outcomes of allo-HCT performed in MDS patients have improved, transplant toxicity remains a relevant limitation for determining this patient's eligibility and transplant success. The use of PTCY for GVHD prevention is becoming a common practice in the allo-HCT community. At our institution, as in many others, PTCY-based prophylaxis has been progressively used, irrespective of the selected donor type. PTCY effectively prevents the onset of GVHD. However, its use is also associated with increased infectious complications, delayed engraftment, and specific organ toxicities. Little is known, however, about the efficacy and safety of using PTCY in patients with MDS undergoing allo-HCT. This study reports the results of comparing the outcomes of PTCY-based versus (vs.) conventional prophylaxis in a cohort of MDS patients undergoing allo-HCT. METHODS This study includes the 69 patients with MDS who underwent their first allo-HCT at our institution in the years 2010 to 2022. Retrospective data were updated in June 2023. The study cohort was divided into two groups according to the GVHD prophylaxis used in the transplant platform (PTCY-based vs. other prophylaxis) in order to compare their respective outcomes. RESULTS The baseline characteristics of the study cohort according to the GVHD prophylaxis are shown in Table 1. Overall, the median age was 59, with 17 (24.6%) patients older than 65. According to the IPSS-R score, 11 (15.95%) patients were classified into the high-risk group, and 20 (29%) into the very-high-risk group. Fifteen (21.7%) adults underwent allo-HCT upfront, and 54 (78.3%) received prior treatment with either chemotherapy-based 7 (10.1%) or HMA-based regimens 49 (71%). Most of the baseline characteristics were balanced between the two study groups, except for the proportion of allo-HCT using 9/10 mismatched unrelated and haploidentical donors, which was higher in the PTCY group (50.0% vs. 10.3%, p&amp;lt;0.001). Post-transplant results are shown in Table 1. All patients engrafted. The medians of days to neutrophil (20 vs. 16, p&amp;lt;0.01) and platelet (15 vs. 12, p&amp;lt;0.01) engraftment were longer in patients who received PTCY. The use of PTCY resulted in similar rates of grades II-IV (Day +100 cumulative incidence (CI): 40.0% vs. 30.8%, p=0.56), in higher incidence of III-IV aGVHD (20.0% vs. 5.1%, p=0.052), and in lower rates of moderate/severe cGVHD (0% vs. 37.0%, p&amp;lt;0.001). Post-transplant outcomes were similar in patients who received PTCY and in those who did not. The 2-years OS, RFS, NRM, CIR and GRFS of patients who received PTCY were 44.2%, 42.7%, 35.5%, 21.8% and 40.4%; for those patients that did not receive these numbers were 64.1%, 61.5%, 15.4%, 23.1% and 30.8% ( Table 1). A multivariate analysis was performed to compare the effects of PTCY in post-transplant results (aGVHD CI, OS and NRM), controlling for covariates whose omission could bias the results of the univariate comparisons. As shown in Table 2 when controlled by donor type, patients who underwent allo-HCT with PTCY had comparable risk for presenting grades II-IV (HR 0.94, P=0.89) and III-IV aGVHD (HR 2.57, P=0.20) than patients without PTCY. The null hypothesis that patients with MDS and PTCY prophylaxis had similar transplant outcomes than those with conventional prophylaxis was not rejected: OS (HR 1.36, p=0.45), NRM (HR 2.28, p=0.21) and CIR (HR 0.39, p=0.27). The multivariate analysis also revealed that older patients (HR 1.11, p=0.01) and patients transplanted in a worse performance status (KPS&amp;lt;90) (HR 3.40, p=0.006) had worse OS secondary to higher risk for NRM. In addition, patients classified into the very-high-risk group (HR 10.88, p&amp;lt;0.001), and patients with a higher number of blasts prior to allo-HCT (HR 1.26, p=0.06) all had a higher risk for disease relapse. CONCLUSION The use of PTCY in adults undergoing allo-HCT for MDS resulted in comparable post-transplant outcomes than the use of more conventional prophylaxis but lowered the rates of moderate/severe cGHVD. Higher risk for NRM was documented in older adults and in patients with worse performance status. Furthermore, patients with a very-high-risk MDS, according to R-IPSS, were exposed to higher risk for relapse irrespective of the intensity of the conditioning regimen used as part of the transplant platform.

Effectiveness of In Vivo T-Cell Depleted Regimen Containing Porcine Antilymphocyte Globulin and Rabbit Antithymocyte Globulin in Preventing Acute Gvhd after Haploid Hematopoietic Stem Cell Transplantation

Objective To compare the clinical efficacy of porcine antilymphocyte globulin (p-ALG) and rabbit antithymocyte globulin (r-ATG) in the treatment of hematologic malignancies using haploid hematopoietic stem cell transplantation (haplo- HSCT), this study was conducted. Methods This was a single center retrospective analysis of 178 subjects who received haplo-HSCT with p-ALG or r-ATG from January 2020 to December 2022. The patients were divided into three groups according to the doses of p-ALG or r-ATG used in the conditioning regimens. The study evaluated and compared the occurrence of early fever, graft versus host disease (GVHD), infection, and survival among the three groups of patients. Results A total of 178 patients were enrolled in the study with a median age of 30 (14-61) years, including 95 men and 83 women. The median follow-up time post-transplantation was 20.1 (1.7-36.9) months. The study included 57 patients in the p-ALG 75mg/kg group, 49 patients in the p-ALG 90mg/kg group, and 72 patients in the r-ATG 7.5mg/kg group, respectively. The incidences of neutrophil and platelet engraftment, respectively, were 100%,93.5%, and 91.3% (p=0.133); 100%, 93.6%, 90.3% (p=0.033) in P-ALG 75mg/kg, P-ALG 90mg/kg and r-ATG 7.5mg/kg. The median time to neutrophil engraftment was 11 days for the P-ALG 75mg/kg group, 12 days for the P-ALG 90mg/kg group, and 12 days for the r-ATG 7.5mg/kg group (p=0.133). The median time to platelet engraftment was 12 days for the P-ALG 75mg/kg group, 14 days for the P-ALG 90mg/kg group, and 13 days for the r-ATG 7.5mg/kg group (p=0.033). In the p-ALG 75mg/kg, p-ALG 90mg/kg, and r-ATG 7.5mg/kg groups, 16 patients (28.1%), 24 patients (49.0%) and 35 patients (48.6%) developed fever within 14 days after transplantation, respectively. Cytokine release syndrome was found to be the most common cause of fever. The incidence of grades Ⅱ-Ⅳ acute GVHD (aGVHD) and grades Ⅲ-Ⅳ aGVHD, respectively, were 15.8%, 12.2%, and 12.5% (p=0.853); 5.3%, 2.0%, and 5.6% (p=0.523) in P-ALG 75mg/kg, P-ALG 90mg/kg and r-ATG 7.5mg/kg. The cumulative incidence of chronic GVHD at 1 year was 14.0%, 10.2%, and 15.3% (p=0.731) in the three groups. 43.9%, 71.4%, and 61.1% of patients in the p-ALG 75mg/kg, p-ALG 90mg/kg and r-ATG 7.5mg/kg groups, respectively, experienced at least one infection within 1 year after haplo-HSCT (p=0.0.13). Notably, the CMV infection rate in the p-ALG 75mg/kg group was significantly lower than in the p-ALG 90mg/kg and r-ATG 7.5mg/kg groups. The 2-year overall survival (OS) rates of p-ALG 75mg/kg, p-ALG 90mg/kg and r-ATG 7.5mg/kg groups were 78.2%, 70.6%, and 72.3% (p=0.491). The cumulative incidence of 2-year relapse were 33.0%, 29.8%, and 30.0% (p=0.834). ConclusionsCompared with r-ATG group, the p-ALG 75mg/kg group showed a lower incidence of infection. However, there were no significant differences between the two groups in terms of the incidence of grades Ⅱ-Ⅳ aGVHD, 2-year overall survival (OS), and 2-year cumulative incidence of relapse. p-ALG (75mg/kg) has a comparable effect on the prevention of GVHD after haplo-HSCT with a lower incidence of infection. Keywords: Porcine antilymphocyte globulin; Rabbit antithymocyte Globulin; Haploidentical hematopoietic cell transplantation; Graft versus host disease; Infection

Comparative Study for Haplo, MSD and MUD Allo-Hcts for AML Patients with KMT2A Rearrangement: A Study from the Global Committee and the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Background Acute myeloid leukemia (AML) patients with KMT2A rearrangement (KMT2Ar, except for t(9;11)(p21.3;q23.3)/MLLT3::KMT2A) are classified as adverse risk in the 2022 European LeukemiaNet (ELN) classification. There is uncertainty on their outcome following allogeneic cell transplantation (allo-HCT). We compared, in an European Society for Blood and Marrow Transplantation (EBMT) global multi-center registry-based analysis, outcomes following an allogeneic stem cell transplantation (allo-HCT) with either a matched sibling donor (MSD), matched unrelated donor (MUD) or haploidentical donor (HAPLO). Methods Data from 586 AML patients with KMT2Ar receiving a first allo-HCT in 183 EBMT centers from 2010-2022 were analyzed. All patients achieved first complete remission (CR1) before transplantation. Patients with t(9;11), without details on translocation, receiving mismatched UD (&amp;lt;10/10), umbilical cord blood, or grafts with ex-vivo manipulation were excluded. Univariant analysis and Cox regression models were used. Results KMT2A rearranged AML patients received allo-HCT from 201 MSD, 256 10/10 MUD, and 129 HAPLOs. For KMT2Ar type, t(6;11), t(11;19), t(10;11) or other translocations account for 27.8%, 37.5%, 23.9% and 10.8%, respectively. Peripheral blood was the major graft source (83.2%), and myeloablative conditioning accounted for the majority (60.2%) of all allo-HCTs. Engraftment rates were comparable in the three cohorts (MSD 99.5%, MUD 98.4% and HAPLO 96.9% p=0.17). AML relapse was the major cause of death in each donor cohort. On univariate analysis, HAPLO was associated with a lower 2-year relapse incidence (RI) (MSD 41.1%, MUD 37.2%, HAPLO 20%) but a higher 2-year non-relapse mortality (NRM) (MSD 6.1%, MUD 19.3%, HAPLO 21.3%) compared with MSD and MUD. The 180-day cumulative incidence of grade II-IV acute GVHD (aGVHD) was lower in MSD (18.8%) than in MUD (31.3%) or HAPLO groups (26.5%), respectively. The 2-year leukemia-free survival (LFS), overall survival (OS) and GVHD-free/relapse free survival (GRFS) were comparable among the three cohorts. Lower RI was observed in patients with t(11;19) compared with t(6;11) or t(10;11). Complex karyotype (CK) (at least 3 abnormalities) or monosomal karyotype (MK) were both associated with higher RI compared with those without. In addition, in-vivo T cell depletion was related to lower intensive chronic GVHD (cGVHD) incidence. On multivariate analysis, HAPLO HCT was associated with lower RI (hazard ratio [HR=0.46], 95% CI 0.28-0.77; p&amp;lt;0.01) but higher incidence of NRM (HR=2.36, 95% CI 1.17-4.78; p&amp;lt;0.01) compared with MSD, while HAPLO had no significant impact on LFS, OS and GRFS. MUD HCT was associated with higher incidence of grade II-IV aGVHD (HR=1.82, 95% CI 1.19-2,78; p&amp;lt;0.01), NRM (HR=2.73, 95% CI 1.51-4.94; p&amp;lt;0.01), and lower LFS (HR=1.37, 95% CI 1.03-1.83; p&amp;lt;0.05) compared with MSD (reference). Concerning translocation type, t(11;19) was associated with a lower RI (HR=0.64, 95% CI 0.43-0.94; p=0.022), a better LFS (HR=0.66, 95% CI 0.48-0.91; p=0.012), OS (HR=0.63, 95% CI 0.45-0.89; p=0.008) and GRFS (HR=0.75, 95% CI 0.57-1; p=0.049) compared with t(6;11)(reference). Translocations other than t(6;11), t(11;19) or t(10;11) were related to a lower RI (HR=0.45, 95% CI 0.24-0.87) and better OS (HR=0.57, 95% CI 0.34-0.95) compared to t(6;11). MK was associated with higher RI (HR=1.59, 95% CI 1.04-2.45; p&amp;lt;0.05) and lower LFS (HR=1.47, 95% CI 1.01-2.14; p&amp;lt;0.05). Conclusions For AML patients with KMT2Ar, HAPLO HCT was associated with a lower RI but higher NRM, leading to similar LFS, OS and GRFS compared with MUD and MSD HCTs. In the setting of allo-HCT, t(11;19) seems to be associated with favorable outcomes compared with other KMT2Ar.

Herombopag, a Second Generation Thrombopoietin-Receptor Agonist, Stimulates Platelet Engraftment after Haploidentical Allogeneic Hematopoietic Stem Cell Transplantation

Introduction: The delayed platelet engraftment is a common complication in allogeneic hematopoietic stem cell transplantation (allo-HSCT), which elevates treatment-related mortality and impairs quality of life. Although some studies reported that platelet engraftment after allo-HSCT was promoted by thrombopoietin-receptor agonists (TPO-RAs), the recommended detailed TPO-RA administration is still lacking. This prospective, single-center, investigator-initiated pilot study aims to explore the efficacy and safety of herombopag, a second-generation TPO-RA, to stimulate platelet engraftment in haploidentical allo-HSCT (haplo-HSCT). Methods: A total of 36 patients (median age 38; range 15-59 years) with anaplastic anemia, myelodysplastic syndrome, acute leukemia, granulocytic sarcoma, or primary hemophagocytic lymphohistiocytosis were enrolled between November 2021 and June 2023. All patients received haplo-HSCT and post-transplant cyclophosphamide for acute graft-versus-host disease (aGVHD) prophylaxis. Patients received herombopag from day+5 post-HSCT until platelet&amp;gt;100,000/µL, disease progression, intolerable toxicity, or withdrawal of informed consent. The dose of herombopag was 5 mg/day initially and reduced to 2.5 mg/day when platelet&amp;gt;75,000/µL. Complete platelet engraftment (CPE) was defined as a platelet count exceeding 50,000/μl for seven consecutive days without transfusion. Partial platelet engraftment (PPE) was defined as a platelet count exceeding 20,000/μl for seven consecutive days without transfusion. The objective response included both CPE and PPE. The primary endpoint was the 21-day cumulative incidence and 28-day cumulative incidence of CPE and objective response after haplo-HSCT. The secondary endpoints were time to CPE, time to objective response, platelet transfusion units, aGVHD, relapse, non-relapse mortality, and safety. Results: The patients received herombopag treatment for a median of 15 days. The 21-day cumulative incidence of CPE was 55.6%, and that of objective response was 77.8%. The 28-day cumulative incidence of CPE was 69.4%, and that of objective response was 80.6%. The median time to objective response was 20.5 (95%CI 17-27) days. The median time to CPE was 23 (95%CI 10-33) days. The mean units of platelet transfusions required within 30 days after HSCT was 6.7. The median follow-up time was 12.1 months. The one-year overall survival rate was 85.3% (95%CI 72.8%-99.8%). Two patients died of aGVHD and two patients died of lung infection. Four Patients (11.1%) experienced molecular relapse. The cumulative incidence of grade III-IV aGVHD was 16.7%. Furthermore, cytomegalovirus reactivation occurred in 13 patients (36.1%). The most common herombopag-related adverse events were hypomagnesemia (61.1%), increased GGT (52.8%), increased ALT (38.9%), and increased bilirubin (19.4%). No grade III/IV adverse events were observed. Conclusion: Herombopag significantly stimulates platelet engraftment in haplo-HSCT patients and has a favorable safety profile. Further research with a larger sample size and longer follow-up period is required to confirm its optimal use.

Effect of Immunopeptidome Gap Caused By Recipient-Donor HLA Mismatch in Umbilical Cord Blood Transplantation and HLA-Haploidentical Hematopoietic Stem Cell Transplantation

Introduction The immune response by alloreactive T cells plays a crucial role in allogeneic hematopoietic stem cell transplantation (allo-HCT), causing not only graft-versus-leukemia but also harmful graft-versus-host disease (GVHD). Human leukocyte antigens (HLA), which are highly polymorphic and differ widely among individuals, are the key molecules that present antigens to T cells. This individual variation in antigen-presenting capacity, the immunopeptidome, is thought to be assessable as HLA evolutionary divergence (HED) between alleles. Several autoimmune diseases are explained by HED, and HED is reported to be associated with outcome in HLA-matched allo-HCT. Thus, HED can be a useful indicator of potential immune reactivity. HLA-mismatched allo-HCT, including umbilical cord blood transplantation and HLA-haploidentical allo-HCT (Haplo-HCT), has been increasing in recent years. The combination of HLA mismatch alleles varies from case to case, thus speculating that it causes individual differences in immune responses is easy. HLA mismatches have long been known to be associated with recurrence and GVHD, but a few risk assessment studies have focused on the immunopeptidome gap due to each HLA mismatch in individual cases. Aim This study aimed to examine the prognostic impact of the gap of immunopeptidome in mismatched HLA between recipient and donor in HLA-mismatched allo-HCT. Methods Allo-HCT was performed on 317 patients at our institution from 2006 to 2022. Of the 272 patients with evaluable allele data, 123 patients who underwent more than 3 alleles HLA-mismatched allo-HCT were retrospectively analyzed. Graft sources included cord blood (n=69, 56.1%) and haploidentical stem cells derived from peripheral blood (n=54, 43.9%). The median age at allo-HCT was 44 (range: 16-67) years and the median observation period was 545 [8-5551] days. Diagnoses include acute myeloid leukemia (n=61, 49.6%), acute lymphoblastic leukemia (n=24, 19.5%), malignant lymphoma (n=24, 19.5%), myelodysplastic syndrome (n=10, 8.1%), and others (n=4, 3.2%). The conditioning regimens was non-myeloablative (n=89, 72.4%). GVHD prophylaxis for 54 Haplo-HCT was anti-thymocyte globulin in 27 (50%) and post-transplant cyclophosphamide in 27 (50%) patients. The immunopeptidome gap of HLA mismatch (HED-mis) was evaluated between each mismatched allele. Grantham distance, which predicts amino acids from HLA allelic information and attempts to measure evolutionary distance based on the chemistry of the two amino acids, was used to calculate HED-mis. HLA allele data were drawn from clinical records. Tobias Lenz et al. produced the calculator program (https://hladiv.net/). HED-mis for each HLA class I: HLA-A (HED-mis A), HLA-B (HED-mis B), and HLA-C (HED-mis C) were calculated to evaluate acute and chronic GVHD (aGVHD and cGVHD), cumulative relapse rate (CIR), and overall survival (OS). Result The median [range] of HED-mis for 123 patients was 0.13 [0.00-13.70] for HED-mis A, 7.15 [0.00-11.25] for HED-mis B, and 4.19 [0.00-7.58] for HED-mis C. Patients were divided into 4 groups at each HED-miss value quartile: Q1, Q2, Q3, and Q4. Non-Q4 (Q1, Q2 and Q3 with the lower gaps) and Q4 with the highest gap of HED-mis A, B, and C were compared to confirm the effect of gap size. Univariate analysis revealed that non-Q4 of HED-mis B was associated with increased aGVHD 2-4 up to 100 days after all-HCT, compared to Q4 (non-Q4 49.8% vs. Q4 25.0%, p=0.017), but was unrelated to the incidence of severe aGVHD 3-4 ( p=0.58). Q4 of HED-mis A demonstrated no difference in aGVHD 2-4 compared to non-Q4 ( p=0.20) but was associated with increased severe aGVHD 3-4 (non-Q4 of 0.06% vs. Q4 of 20.7%, p=0.019, Table and Figure). Similarly, multivariate analysis adjusted for each HED-mis, graft, and conditioning revealed that Q4 of HED-mis A was a risk factor for severe aGVHD 3-4 (hazard ratio [HR]: 3.85, p=0.015), and non-Q4 of HED-mis B was a risk factor for developing aGVHD 2-4 (HR: 3.64, p=0.017). HED-mis C was unrelated to any grade aGVHD, but Q4 of HED-mis C may have a better 2-year CIR in univariate (20.3%, vs. in non-Q4, 46.2%, p=0.055) and multivariate analyses (HR: 0.34, p=0.051). No association was found with each HED gap and each quartile for cGVHD and OS. Conclusion Gaps in the immunopeptidome of HLA-mismatched alleles, especially in HLA-A, should be considered in severe aGVHD development during donor selection.

Comparable Outcome after Busulfan- or Treosulfan-Based Conditioning Regimen in Children Above 4 Years of Age with ALL Undergoing Allogeneic HSCT. Results from the Prospective International Forum-Trial

Purpose: Total body irradiation (TBI) has proved to be the “gold standard” as part of the conditioning regimen before allogeneic hematopoietic stem cell transplantation (HSCT) in pediatric patients with acute lymphoblastic leukemia (ALL). Its superiority over chemo-based conditioning was recently demonstrated in the prospective, international, randomized phase III study, which enrolled 417 patients beyond the age of 4 years transplanted for ALL in complete morphological remission (CR) from either matched sibling (MSD) or matched unrelated donor (MD) (Peters et al, JCO 2021, FORUM study; EudraCT: 2012-003032-22;ClinicalTrials.gov: NCT01949129). The use of either of the two protocol-prespecified chemo-conditioning regimens resulted in significantly worse EFS. Given the unavailability of TBI in some regions/centres and contraindications to TBI in individual patients, we here compare the outcomes of patients who received busulfan (BU) - based regimen vs of those who were given a treosulfan (TREO) - based conditioning in FORUM centres in both randomizing and non-randomizing countries in the years 2013-2018. Patients and methods: Patients ≤ 18 years at diagnosis (median age at HSCT 9.9 years, range 4-19.5), in CR pre-HSCT and with an MSD or MUD were assigned to myeloablative conditioning with fludarabine (FLU), thiotepa (THIO) and either BU or TREO according to country preference. Children transplanted from MSDs received cyclosporine A only as graft-versus-host disease (GvHD) prophylaxis, whereas recipients of MUD HSCT also received short-term methotrexate and anti-thymocyte globulin (ATG). Further details of the transplant procedure have been previously described (Peters C, et al. J Clin Oncol 2021). Results:In addition to the 193 patients from the randomizing countries, the FORUM trial included 115 additional children enrolled in countries where randomization could not occur (for legal or technical reasons). Overall, 180 vs. 128 patients received BU/THIO/FLU vs TREO/THIO/FLU, respectively. There were no differences about the patients' gender, age, and remission status and slight differences regarding donor, stem cell source and MRD status pre-transplant between the two cohorts of patients (see Table 1 for details). Patient's outcomes were updated as of February 20 th, 2023, and median follow-up was 4.2 years (range 0.3 - 9.1). There were neither differences between the 3-year overall survival (OS) (0.71±0.03 for BU/THIO/FLU vs 0.72±0.04 for TREO/THIO/FLU) nor event-free survival (EFS) (0.61±0.04 for BU/THIO/FLU vs 0.55±0.04 for TREO/THIO/FLU, p=NS). Three-year cumulative incidence of relapse (CIR) and non-relapse mortality (NRM) were 0.31±0.03 and 0.08±0.02 following BU/THIO/FLU and 0.36±0.04 and 0.09±0.03 following TREO/THIO/FLU, respectively (p=NS). Only one case of secondary malignancy was observed in the TREO cohort and one case of fatal liver veno-occlusive disease (VOD) in the BU group. No statistical differences were observed regarding the cumulative incidence of both aGvHD and cGvHD between the two groups; 3-year GFRS was almost identical (0.42± 0.04 in the BU/THIO/FLU group and 0.43±0.04 in the TREO/THIO/FLU cohort). There were no differences in OS, EFS, CIR, NRM and GFRS in either CR1 or CR2 patients between the two conditioning regimens. Furthermore, there were no differences in outcomes between countries. Patients given BU/THIO/FLU had a faster leucocyte, neutrophil and platelet recovery as compared to those prepared with TREO/THIO/FLU. Conclusion: Comparable long-term outcomes were observed after BU/THIO/FLU or TREO/THIO/FLU in children with ALL undergoing allogeneic HSCT included in the FORUM trial. Therefore, either of the 2 regimens may be effectively and safely used worldwide in patients &amp;gt; 4 years having a contraindication to or treated in centres/countries unable to deliver TBI.

Risk Factors and Prognostic Model for II-IV aGVHD in Patients with Engraftment Syndrome after Haploidentical Hematopoietic Stem Cell Transplantation

Background Engraftment syndrome (ES), characterized by noninfective fever, rash, noncardiogenic pulmonary edema, hepatic dysfunction and weight gain, is a common complication after haplo-HSCT. Although ES has been reported in the previous literature, there is still no consensus on the risk factors, outcomes and treatment of ES, as there is not only a lack of uniformity described by authors but also conflicting evidence between studies. One meta-analysis found that patients with ES have significantly higher odds of developing aGVHD than patients without ES. However, a strategy for identifying high-risk patients with ES for aGVHD remains unclear although important for early aGVHD prevention and the improvement of patient outcomes. Here, we retrospectively analyzed a large cohort of posthaplo-HSCT ES patients and described the risk factors, outcomes and prognostic model for II-IV aGVHD in patients with ES. Methods A total of 384 patients with ES after haplo-HSCT at Peking University People's Hospital between 2013 and 2022 were retrospectively identified. We first performed a nested case‒control study to identify the risk factors for ES, and three controls were randomly selected for each case according to the time of transplant and the length of follow-up. The cohort of ES patients was further divided into a derivation cohort of 258 patients and a validation cohort of 126 patients. We used a logistic regression model to perform univariate and multivariate analyses to determine the risk factors and prognostic factors for II-IV aGVHD in patients with ES after haplo-HSCT. The prognostic model performance was assessed by evaluating the discrimination [area under the curve (AUC)], calibration (calibration plot), and net benefit [decision curve analysis (DCA)]. Results In 384 patients diagnosed with ES after haplo-HSCT, the median diagnostic time of ES was 11 days after haplo-HSCT, close to the time of neutrophil engraftment. Among them, 252 (65.6%) patients developed aGVHD, and 123 (32.0%) suffered II-IV aGVHD. The 3-year survival rate of ES patients who developed II-IV aGVHD was 17.1% (21/123) compared with 4.3% (11/252) in those without II-IV aGVHD (p&amp;lt;.001).Through multivariable logistic binary regression models, six prognosis risk factors were selected，including age at HSCT≤25 years(p=0.008; odds ratio [OR], 4.47; 95% confidence interval [CI], 1.54-14.30), obesity (BMI≥28) at HSCT(p=0.039; OR, 12.60; 95% CI, 1.30-194.14), previous pregnancy history (p=0.09; OR, 3.42; 95% CI, 0.83-18.45), time from diagnosis to transplantation≥6 months (p=0.027; OR, 2.73; 95% CI, 0.97-8.50), a high dose of MNC administration (≥9×10 8)(p=0.003; OR, 4.39; 95% CI, 1.70-12.41) and a high dose platelet transfusion (≥2u) during conditioning regimen (p=0.007; OR, 4.04; 95% CI, 1.51-11.73). According to the regression coefficient, 2 scores were assigned for obesity at HSCT, and 1 score was assigned for the other risk factors. Hence, a prognostic model for II-IV aGVHD termed TOPMAP ( time from diagnosis to transplantation, obesity, previous pregnancy history, high-dose MNC administration, age, and high-dose platelet transfusion) was constructed. Patients were stratified into 3 risk groups: low risk (0-2), intermediate risk (3-4), and high risk (5-7), which showed an incidence of II-IV aGVHD of 15.9% for low risk, 39.2% for intermediate risk, and 83.3% for high risk (P&amp;lt;0.001). The AUCs of the prognostic scoring model were 0.816 (95% CI 0.727-0.903) and 0.813 (0.759-0.868) for the internal validation and validation cohorts, respectively. The calibration plots showed a high agreement between the predicted and observed outcomes. Decision curve analysis indicated that patients with engraftment syndrome could benefit from the clinical application of the prognostic model. Conclusion Here, we reported the largest study on ES posthaplo-HSCT and found risk factors for ES onset. We developed the first straightforward scoring model (designated TOPMAP) that incorporates clinical and laboratory risk factors to predict the high-risk group for II-IV aGVHD in patients with ES after haplo-HSCT. This model can effectively help clinicians identify ES patients early, sectionalize them according to risk for II-IV aGVHD, carry out aGVHD prevention and improve patient outcomes.