Donor Source Research Articles

Effect of Differences in Immunological Reconstitution By Donor Age and Recipient Age on the Incidence of Chronic Graft-Versus-Host Disease

Background: Development of chronic graft-versus-host disease (cGVHD) has been reported to be associated with donor age and recipient age. We hypothesized that differences in post-transplantation immunological reconstitution depending on donor age and recipient age might be responsible for the incidence of cGVHD. Redevelopment of regulatory T (Treg) cell expansion and cytokine production was investigated over time according to donor age and recipient age at the time of transplantation after allogeneic hematopoietic cell transplantation (HCT). Methods: The subjects were 39 consecutive patients who underwent HCT for different hematologic diseases at our hospital between December 2008 and December 2021 and survived for more than 3 years after HCT without cGVHD. The patients were classified into younger (age ≤59, n=23) and older (age ≥60, n=16) groups. The donor source was divided into subgroups based on use of cord blood or an adult donor: cord blood (younger, n=5; older, n=8) and adult donor (younger, n=18; older, n=8). Peripheral blood was drawn from all patients on day 200 and at 24 and 36 months after HCT. Analysis of Treg, T, B, and NK cells was performed using flow cytometry. T cells were isolated using EasySep kits and cultured at 37℃ in 5% CO 2 in air for 4 days with 10% heat-inactivated fetal calf serum as controls, interleukin-2 (IL-2) and transforming growth factor-β1 (TGFβ1) as samples, or concanavalin A (ConA) (10 µg/ml) at a density of 1×10 6 cells/ml. Treg cells were analyzed by flow cytometry and ConA-stimulated culture supernatants were tested for concentrations of IL-4, IL-5, IL-6, IL-10, IL-13, TGFβ1, tumor necrosis factor α (TNFα) and interferon-γ (IFNγ). Results: The results for patients who underwent HCT at our institution during the same observation period as this study suggested that donor source and patient age may be involved in development of cGVHD (p=0.032, p=0.015, respectively). In younger patients, CD4/8 in peripheral blood showed a tendency to increase over time after transplantation: 0.91±1.0 at 200 days, 0.54±0.29 at 2 years, and 1.32±0.57 at 3 years (R=0.308, p=0.072); and young patients after cord blood transplantation showed a marked improvement: 0.30±0 at 200 days, 0.59±0.18 at 2 years, and 1.84±0.27 at 3 years (R=0.913, p=0.0016). Percentages of Treg cells in peripheral blood and stimulated cultures were positively correlated in younger (R=0.349, p=0.043) and older (R=0.381, p=0.029) patients. The percentage, absolute number, and amplification rate of Treg cells in stimulation culture of T cells from younger patients (6.37±4.02%, 3759.4±1963.3 /mL, 12.4±11.5 times) at 200 days after transplantation were significantly higher than those for older patients (3.04±1.48%, 1783.9±1152.0 /mL, 5.4±3.7 times) (p=0.027, p=0.003, p=0.023). Post-transplant Treg cell expansion rates in younger cord blood transplant recipients significantly increased by 2.4±0 times at 200 days, 2.8±0.6 times at 2 years, and 5.8±2.1 times at 3 years (R=0.711, p=0.046). Regarding cytokine production, IL-5 in stimulation culture from younger patients showed a tendency to increase over time: 4.75±8.89 pg/mL at 200 days, 20.04±27.20 pg/mL at 2 years, and 59.51±104.93 pg/mL at 3 years (R=0.294, p=0.087). Conclusions: T cell reconstitution and cytokine production tended to increase over time after transplantation in younger patients. The ability to reconstitute Treg cells was higher in younger patients early after transplantation and increased over time in young cord blood transplant recipients. These factors may account for the high incidence of cGVHD in older transplant recipients from adult donors, although the number of cases in the study is limited and the data are preliminary.

Risk-Adapted Donor Lymphocyte Infusion after Hematopoietic Cell Transplant in Pediatric and Young Adult Patients Is Associated with Low Risk of Graft Versus Host Disease

Introduction: Donor lymphocyte infusion (DLI) is a form of adoptive immunotherapy administered to enhance the graft-versus-leukemia (GVL) effect after an allogeneic hematopoietic cell transplantation (HCT). DLI is frequently chosen for its ease of administration and low risk of graft ablation as compared with other chemotherapeutic options in patients experiencing mixed chimerism (MC) or disease relapse. But in patients with acute leukemia experiencing relapse, clinical responses are seen in fewer than 20-30%. Success is also limited by the occurrence of acute and chronic graft-versus-host disease (GVHD). We had previously described our risk-adapted strategy of administering DLIs based on chimerism and donor source (Rujkijyanont P, et al. Blood Cancer J 2013). To determine the efficacy and toxicity of DLIs and to identify potential factors influencing the outcomes, we conducted a retrospective single center study including patients who received DLIs after HCT. Methods: We collected data on all HCTs and conventional DLIs that had been administered to patients from 1993 to 2022 for any indication at our center. Each HCT was considered as an independent event. Numeric variables were represented by median and range and compared using the Wilcoxon-Mann-Whitney test. Categorical variables were compared using the Fisher exact test. Competing-risk regression models using the Fine-Gray method were developed to evaluate risk factors for acute GVHD and chronic GVHD. Death and relapse were considered as competing risk events for these GVHD outcomes. Follow-up data were censored at subsequent HCT, 2 years after the first DLI, 5 years after transplant, or the last follow-up. Logistic regression analysis was performed to assess factors associated with the response to DLI within 180 days after the first DLI. Results: During the study period, 236 patients received 252 HCTs followed by DLIs (median age at HCT 9.2 [range 0.2-25.1] years). An additional 743 patients received 806 HCTs with no subsequent DLI (median age at HCT 10.3 [range 0.1-27.2] years). Dosing most frequently used was 1 × 10 5, 1 × 10 6 and 1 × 10 7 CD3+ cells/kg, for haploidentical donor (HAPLO), matched unrelated donor (MUD) and matched sibling donor (MSD) recipients, respectively. Initial doses were occasionally lower based on risk of GVHD and were escalated as tolerated and based on response. After receiving DLI, 19.4% developed acute GVHD, and 9.2% developed chronic GVHD with no significant differences observed between MSD, MUD and HAPLO recipients. After adjusting for donor source, longer duration between HCT and DLI was associated with a significantly decreased risk of both acute (HR 0.97 P<0.001) and chronic GVHD (HR 0.98 P=0.04). A higher CD3+ cell dose was also significantly associated with an increased risk of acute GVHD (HR 1.03 P<0.001) but not chronic GVHD (HR 0.96 P=0.12). The overall response rate after DLI for treating MC or graft failure was 45.2% for MSD, 32.6% for MUD and 41.4% for HAPLO recipients. Logistic regression analysis revealed leukemia patients had a higher response rate after receiving a DLI for mixed chimerism from MSD (OR=19.5 P=0.002) and HAPLO (OR=9.03 P=0.042), but not from MUD HCT (OR=0.65 P= 0.57), compared to patients with non-malignant disorders. We also evaluated the response to DLI for frank disease relapse in 15 patients. The response rate after DLI for disease relapse was 50% (1/2) for MSD, 44.4% (4/9) for HAPLO, but 0% (0/4) for MUD recipients. Conclusions: In our analysis, the incidence of GVHD was not higher in pediatric and young adult HCT recipients who received DLI as compared to those who did not. Overall, the risk of developing acute and chronic GVHD after DLI was low and comparable between different donor sources. The risk of GVHD decreased further away from HCT and increased with higher DLI dose. The response rate for treating MC and disease relapse remains less than 50%. Thus, DLIs may be safely administered to pediatric and young adult patients after HCT. The therapeutic effect may be modulated by adjusting the dose, timing and frequency of DLI administration.

Hematopoietic Stem Cell Transplantation for Fanconi Anemia: Outcome and Prognostic Factors for Survival and Subsequent Neoplasms

Introduction Fanconi anemia (FA) is an inherited disorder of impaired DNA repair, associated with progressive bone marrow failure (BMF), leukemia, and cancer predisposition. Hematopoietic cell transplantation (HCT) may be curative for FA associated BMF, and changes in HCT practice over the past decades may have impacted outcomes in FA patients. Methods We used CIBMTR database to perform a retrospective cohort study of children and adults undergoing first allogeneic HCT for FA BMF (patients with MDS/AML excluded) from 2000-2018. We hypothesized that contemporary HCT approaches, including decreases in radiation and increase in use of serotherapy and ex-vivo graft manipulation, would associate with improved outcomes in FA patients receiving HCT. The primary endpoints were overall survival (OS) and early subsequent malignant neoplasm (SMN; by 5 yr post-HCT). Secondary endpoints included event free survival (EFS; death, SMN or graft failure), treatment related mortality (TRM), graft failure, and acute (grade II-IV) and cGVHD. Univariate and multivariate Cox regression models were created to evaluate the impact of conditioning, donor and graft source, treatment era, and patient characteristics on outcomes, adjusting for other significant covariates. Due to confounding factors, we were not able to create a single multivariate model that included radiation, ex-vivo graft manipulation, and donor and graft source; therefore, we performed subgroup univariate analysis for patients receiving unrelated donor bone marrow (BM) or peripheral blood stem cell (PBSC) HCT. Results We analyzed 652 HCTs from 2000-07 (n=353) and 2008-18 (n=293). 223 (35%) patients had a matched related donor (MRD) with any graft type, 244 (38%) had an unrelated donor BM or PBSC grafts, 123 (19%) had an unrelated cord blood graft, and 44 (7%) had a related haploidentical donor with any graft type. Between the two treatment eras, 5-yr OS has dramatically improved (78.8% 2008-18 v 62.5% 2000-07, p<0.01; figure 1) driven by lower 5-yr TRM (15.2% v 25.5%, p=0.004) and lower rates of primary (7.9% v 12.9% at 42 days, p=0.038) and secondary (4.1% v 8.9% at 1 year, p=0.014) graft failure. No statistically significant change was observed for aGVHD, cGVHD, or early SMN. Assessing the entire cohort, use of total body irradiation (TBI) >300cGy was associated with lower OS (HR=1.75, 95% CI 1.24-2.47) and increased TRM (HR=3.36, 95% CI 1.54-7.34; figure 2) on multivariable analysis. For patients that received unrelated BM or PBSC HCT, use of TBI was associated with inferior OS survival (HR=1.93, 95% CI 1.18-3.17), EFS (HR=1.78, 95% CI 1.13-2.80), and TRM (HR=2.31, 95% CI 1.20-4.46) on univariate analysis. Among all patients, CD34 selection or T-cell depletion ( ex vivo depletion) were not associated with better OS (95% HR=1.014, 95% CI 0.84-1.56), EFS (HR=1.163, 95% CI 0.86-1.58), or TRM (HR=0.79, 95% CI 0.52-1.19) but was associated with less aGVHD (HR=0.35 95% CI 0.22-0.57) and lower but not-statistically significant cGVHD (HR=0.54, 95% CI 0.29-1.01) on multivariable analysis. Within the unrelated donor setting, univariate analysis showed reduced aGVHD (HR=0.39 95% CI 0.23-0.68) and cGVHD (HR=0.47 95% CI 0.28-0.79) but did not have a significant effect on OS, EFS, or TRM. Early SMN occurred in 3.2% of participants by 5-years post-HCT and was associated with cGVHD occurrence (HR=2.14, 95% CI 1.06-4.33) and older age (>18 v <9 years, HR=6.35, 95% CI 2.66-15.14), but not ex-vivo depletion or use of ATG or alemtuzumab. Early SMN risk was not impacted by the use of TBI (HR=1.60, 95% CI 0.77-3.34), but secondary analysis demonstrated a trend towards a relationship with doses >300 cGy (HR=2.24, 95% CI 0.99-5.08). Conclusions Outcomes for patients with FA BMF have improved significantly in more recent HCT eras, driven by reductions in TRM and graft failure risk. Although radiation doses >300cGy were associated with greater toxicity, doses of 100-300cGy were not associated with inferior outcomes in our cohort. Use of CD34 selection or T-cell depletion may reduce the risk of GVHD in transplant FA patients, but does not appear to impact 5-yr OS. Risk for early SMN development in FA patients receiving HCT associates with older age and cGVHD.

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.

Relative Prognostic Value of Flow Cytometric Measurable Residual Disease before Allogeneic Hematopoietic Cell Transplantation for Adults with MDS/AML or AML

Background: Measurable residual disease (MRD), assessed by multiparameter flow cytometry (MFC) before allogeneic hematopoietic cell transplantation (HCT), is strongly and independently associated with poor post-HCT outcomes in adults with acute myeloid leukemia (AML). On the other hand, the relative prognostic value of MFC-based MRD testing is unknown in patients with myelodysplastic neoplasm (MDS)/AML, a disease entity newly defined by the 2022 International Consensus Classification (ICC) that encompasses cases of MDS with 10-19% blasts and recognizes the diagnostic continuum between MDS and AML. Methods: To assess the relationship between pre-HCT, disease type, and post-HCT outcomes, we retrospectively analyzed 1,262 adults ≥18 years with MDS/AML (n=150) or AML (n=1,112), based on the ICC 2022 criteria, who received a first allograft while in first or second morphologic remission at a single institution between 4/2006 and 3/2023. Results: The MDS/AML and AML cohorts differed significantly regarding patient and disease-specific characteristics, including age at HCT (60 vs. 56 years in MDS/AML and AML patients, respectively, P<0.001), HCT-CI score ( P<0.001), adverse cytogenetic risk according to ELN 2022 criteria (39% vs. 26%, P<0.001), intensive therapy prior to allogeneic HCT (69% vs. 97%, P<0.001), time from last remission (76 vs. 98 days, P<0.001), first remission status (97% vs. 77%, P<0.001), pre-HCT MRD by MFC (35% vs. 19%, P<0.001), and peripheral blood stem cells as graft source (89% vs. 80%, P=0.015). There were no differences in donor source or conditioning intensity. With a median follow-up of 5.11 years (interquartile range [IQR]: 2.38-9.66) in survivors, there were 384 relapses, 590 deaths, and 258 non-relapse mortality (NRM) events contributing to the estimates for relapse, NRM, relapse-free survival (RFS), and overall survival (OS). At three years, NRM (21% [14-28%] for MDS/AML vs. 16% [14-19%] for AML, P=0.19), relapse (29% [22-36%] vs. 29% [27-32%], P=0.94), RFS (50% [42-59%] vs. 54% [51-58%], P=0.25), and OS (52% [44-61%] vs. 60% [57-63%], P=0.09) were similar between the two groups. After multivariable adjustment, relapse rates for patients with MDS/AML vs. those with AML were similar (hazard ratio [HR]=0.77 [0.50-1.17], P=0.2), as were NRM (HR=1.41 [0.91-2.18), P=0.12), RFS (HR=0.99 [0.73-1.35], P>0.9) and OS (HR=1.17 [0.85-1.61], P=0.3). Importantly, a significant interaction was found between pre-HCT MRD status and disease type (MDS/AML vs. AML) for relapse ( P=0.009), RFS ( P=0.013), and OS ( P=0.048). The interaction models indicated that the HRs for the association between pre-HCT MRD and post-HCT outcomes were lower in patients with MDS/AML (for relapse: HR=1.73 [0.96-3.11] in MDS/AML vs. HR=3.56 [2.90-4.38], in AML; for RFS: HR=1.60 [1.03-2.48] vs. HR=2.67 [2.25-3.16]; for OS: HR=1.53 [0.97-2.39] vs. HR=2.34 [1.96-2.78]). Pre-HCT MRD was associated with a higher risk of relapse in both MDS/AML and AML patients but to a lesser extent in the MDS/AML patients. In these patients, relapse at three years was 37% [24-51%] for those with pre-HCT MRD vs. 24% [16-33%] for those without ( P=0.068), translating into lower RFS (39% [28-56%] vs. 56% [47-67%], P=0.038) and OS (41% [29-58%] vs. 58% [48-70%], P=0.066) in MDS/AML patients with pre-HCT MRD. For comparison, in patients with AML, relapse at three years was 22% [20-25%] for those without MRD vs. 56% [50-62%] for those with ( P<0.001), translating into lower RFS (27% [22-31%] vs. 61% [58-64%], P<0.001) and OS (35% [29-42%] vs. 65% [62-68%], P<0.001) in those with pre-HCT MRD. In line with these findings, C-statistics showed that pre-HCT MRD was not as predictive in MDS/AML patients in comparison to AML patients (for relapse: 0.57 in MDS/AML patients vs. 0.62 in AML patients; for RFS: 0.57 vs. 0.59; for OS: 0.56 vs. 0.58). Conclusion: Our data suggest that, overall, patients with MDS/AML or AML in first or second morphologic remission have similar outcomes following allogeneic HCT. However, MFC-based pre-HCT MRD testing is prognostically substantially less informative for MDS/AML than AML patients, possibly because of increased rates of misclassification. These findings support the rationale to examine the prognostic value of molecular MRD testing in patients with MDS/AML. Figure. Cumulative incidence of relapse stratified (A) by disease type at diagnosis and (B) by disease type at diagnosis and pre-HCT MRD.

Acute Leukemia and MDS Patients Older Than 70 Years Have Inferior Survival Following Allogeneic Stem Cell Transplant Compared to Those with 60-69 Years of Age

Introduction: Increasing number of older patients are undergoing allogeneic stem cell transplants (alloSCT) for acute leukemia and MDS. We and others have previously reported alloSCT outcomes of older patients. However, majority of these studies included very few patients older than 70 years. In addition, the information on the influence of donor source on alloSCT outcomes among older patients is limited. In this study, we aim to answer two questions: Is there any difference in long-term survival between patients 60-69 years and those older than 70 years? Does donor source affect alloSCT outcomes of these two groups? Methods: We retrospectively evaluated alloSCT outcomes of 467 patients older than 60 years with acute leukemia (AML and ALL) and MDS. We compared outcomes between two groups: 60-69 years of age and those older than 70 years. The primary objective was to evaluate long-term overall survival (OS). Multivariable analyses included age, comorbidity index, KPS, disease risk index, donor relation, CMV serotype, conditioning regimen, GVD prophylaxis, and thymoglobulin use as variables. Results: Between January 2010 and December 2022, 335 patients with 60-69 years and 132 older than 70 years underwent alloSCT. Median age of the population was 66 years (range, 60-80); 6% (N=30) were African American and 22% (N=101) were of ethnic minority; 53% (N=249) had AML, 39% (N=184) had MDS, and 7% (N=34) had ALL; donor was matched unrelated in 60% (N=279), matched related and haploidentical in 14% each, and mismatched unrelated in 12% (N=55). Source of allograft was peripheral blood stem cells in all patients. Higher proportion of patients older than 70 years received matched unrelated donor compared to those with 60-69 years (69% vs 56%; p=0.004). Reduced intensity conditioning (RIC) regimen was frequently used among patients older than 70 years compared to 60-69 years (97% vs 79%, p<0.001). Neutrophil and platelet engraftment time was similar in both groups. Graft failure rate was higher for patients older than 70 years compared to 60-69 years (5.3% vs. 1.2%; p=0.014). The cumulative incidence of grade 3-4 acute GVHD was similar (13.5% vs 7.6%, p=0.2), while severe chronic GVHD was higher for the 60-69 group compared to the 70+ group (20.1% vs 10%, p=0.009). Median follow up for OS was 4.46 years. At 3 years, OS was 48% for the 60-69 group and 38.23% for the 70+ group (HR 1.34, p=0.02); RFS was 44% for the 60-69 group and 36.3% for the 70+ group (HR 1.32, p=0.02); relapse rate was 26.2% for the 60-69 group and 27.2% for the 70+ group (HR 1.13, p=0.51); and NRM was 30% for the 60-69 group and 37% for the 70+ group (sHR 1.26, p=0.19). In the multivariable analyses, patients older than 70 years experienced poor survival (HR 1.41, p=0.01) and relapse-free survival (RFS) (HR 1.4, p=0.01), and numerically higher non-relapse mortality (NRM) (sHR 1.38, p=0.08) compared to those with 60-69 years. Compared to haploidentical donors, matched related (sHR 0.39, p=0.04) and unrelated donors (sHR 0.28, p=0.005) were associated with lower NRM, while a trend for increased relapse rate and NRM was associated with the use of thymoglobulin and post-transplant cyclophosphamide (PTCy) containing GVHD prophylaxis, respectively. Conclusion: Our results indicate that although rates of acute GVHD and relapse were similar between both groups, patients older than 70 had worse OS and RFS compared to patients between 60-69. The NRM was numerically higher in patients older than 70 years of age. Haploidentical donor was associated with increased NRM, most likely secondary to toxicity associated with PTCy based GVHD prophylaxis. Detailed analysis of toxicity will be presented at the conference.

Outcomes of Patients with Accelerated/Blast-Phase MPNs That Received Allogeneic Stem-Cell Transplant in the Current Era of Myeloid Therapies

Background Patients (pts) with Philadelphia chromosome-negative (Ph-neg) myeloproliferative neoplasms (MPNs) that progress to an accelerated phase (AP) or blast phase (BP) have a median overall survival (mOS) of less than 1 year (Odenike, Blood 2018; Tam et al, JCO 2009). Allogeneic hematopoietic stem cell transplant (allo-HCT) is the only curative approach for MPN-AP/BP, but mOS remains about a year for pts with MPN-BP that undergo allo-HCT (2005-2019) (Orti et al, AJH 2023). We previously reported on outcomes of pts with MPN-AP/BP treated in the current era of myeloid therapies (2017 onward) and found a mOS of 0.73 years in a multi-center cohort of 80 pts (Patel et al, ASH 2022). We aim to characterize treatment patterns and outcomes of pts with MPN-AP/BP that underwent allo-HCT via a multi-center retrospective analysis. Methods Retrospective chart review was performed at 8 institutions to identify pts with pathology-confirmed Ph-neg MPN-AP/BP diagnosed in 2017 or later. All patients that met inclusion criteria were included. Response was assessed using 2017 European Leukemia Net AML (2017 ELN) criteria (Dohner et al, Blood 2017). OS from diagnosis of MPN-AP/BP and from time of allo-HCT was calculated utilizing Kaplan-Meier analysis. Results The full MPN-AP/BP cohort consists of 180 pts. This analysis includes 58 pts that underwent allo-HCT for MPN-AP/BP across 8 institutions. Median age at MPN-AP/BP diagnosiswas 64 years. The most common therapies for chronic-phase MPN included hydroxyurea (55%), JAK inhibitor (JAKi) (26%), interferon (9%), and hypomethylating agent (HMA, 4%). No patient previously received allo-HCT for chronic-phase MPN. Driver mutations included JAK2 (60%), CALR (22%), MPL (10%), but some pts had triple-negative disease (7%). Sixty-two percent of pts had high-risk disease by 2017 ELN criteria. Forty-four pts had next-generation sequencing performed at time of MPN-AP/BP diagnosis. The most frequently co-occurring mutations detected at time of MPN-AP/BP diagnosis were ASXL1 (30%), SRSF2 (23%), RUNX1 (23%), TP53 (18%), TET2 (16%), IDH2 (11%), U2AF1 (7%), EZH2 (7%), and IDH1 (9%). Additional characteristics are in Table 1. One pt proceeded directly to allo-HCT at time of MPN-AP/BP diagnosis. Frontline therapies (1L) for MPN-AP included intensive chemotherapy (IC) (n=26), hypomethylating agent (HMA) + venetoclax (VEN) (n=16), HMA monotherapy (n=14), and low-dose cytarabine (LDAC) + VEN + JAKi (n=1). Responses are summarized in Table 2A. Thirty-seven pts proceeded to allo-HCT after 1L therapy (17 after IC, 10 after HMA+VEN, 9 after HMA, 1 after LDAC+VEN+JAKi). Twenty pts proceeded to allo-HCT after 2 nd-line and beyond (2L+) therapies. Therapies utilized and responses are summarized in Table 2B. Transplant-specific characteristics include 15 pts receiving myeloablative conditioning while 43 received reduced-intensity conditioning. Donor source was matched unrelated donor for 33 pts, haploidentical donor for 10 pts, matched related donor for 9 patients, mismatched unrelated donor for 5 patients, and cord blood for 1 patient. Twenty-two pts developed acute GVHD while 15 developed chronic GVHD. Amongst the 58 pts that underwent allo-HCT, 19 had relapse of disease and 8 patients received treatment after relapse. Amongst the full cohort of 180 patients, mOS was 0.72 years from time of MPN-AP/BP diagnosis. The mOS for the 58 pts that underwent allo-HCT was 1.82 years from time of MPN-AP/BP diagnosis and 1.30 years from time of allo-HCT. Survival analysis by initial MPN-AP/BP therapy demonstrated a mOS from time of MPN-AP/BP diagnosis of 1.9 years for HMA-based therapy, 1.9 years for HMA + VEN, and 1.5 years for IC ( p=0.006). We also analyzed mOS by disease status prior to transplant. Thirty-four pts had a complete response (CR) or CR with incomplete count recovery (CRi) with mOS of 1.7 years from time of allo-HCT, 12 pts with a partial response (PR) or morphologic leukemia-free state (MLFS) had mOS of 1.8 years, and 11 pts with treatment failure (TF) had mOS of 0.47 years (p=0.82). Conclusions Our cohort of 180 pts with MPN-AP/BP treated in the current era of myeloid therapies had limited survival with a mOS of 0.72 years from MPN-AP/BP diagnosis. Amongst the 58 pts that underwent allo-HCT the mOS was 1.82 years with longer mOS seen in pts that received HMA or HMA + VEN as their 1L therapy when compared to IC. This underscores the need for novel management strategies even in pts eligible for allo-HCT.

Treatment- Sensitive, Dependent, and Refractory Chronic Gvhd: Incidence and Clinical Outcomes

Introduction Chronic graft-versus-host disease (cGVHD) remains a limitation to the long-term success of allogeneic hematopoietic cell transplantation (HCT). The clinical characteristics and outcomes associated with treatment-sensitive, -dependent, and -refractory cGVHD are unknown. We investigated risk factors associated with distinct cGVHD treatment response groups and analyzed the impact of treatment response on clinical outcomes of cGVHD following HCT. Methods The study population included 185 consecutive adult and pediatric patients who developed cGVHD after first allogeneic HCT for malignant and non-malignant disorders at the University of Minnesota between 2008 and 2016. All graft and donor sources, GVHD prophylaxis strategies, and conditioning regimens were included. Only cGVHD cases that started treatment within 30 days of diagnosis are included. We defined cGVHD diagnosis and overall severity using the 2014 NIH Consensus Criteria. We predefined treatment response categories as either treatment-sensitive (TS), -dependent (TD), or -refractory (TR) at 6, 12, and 24 months after cGVHD onset. TS requires clinical improvement after 12 months of initial therapy with discontinuation of therapy by 24 months. TR criteria include disease progression during therapy, addition of new systemic therapies, or death before 6 months of cGVHD treatment. TD patients meet TS criteria, however still require systemic therapy 24 months after initiation of cGVHD therapy. Outcomes by response group were analyzed in a landmark analysis at the time at which treatment response was determined, excluding any with the event of interest (relapse, death) before the landmark time. To compare treatment response categories with a no-cGVHD control group, the landmark time was set to the median day of cGVHD onset (day 220) plus treatment response category ascertainment time (e.g. 12 months). Disease-free survival (DFS) was defined as survival without relapse or death. Failure-free-survival (FFS) after cGVHD was defined as survival without relapse, death, or new systemic treatment initiated more than 30 days after cGVHD onset. Results Patient and transplant characteristics are shown in Table 1. Among 1142 allografts, 222 (19%) developed cGVHD and of those 185 (83%) received systemic cGVHD therapy within 30 days of onset and were included in this analysis. Median time to onset of cGVHD was 216 days (range 71-945) with 7.4 years median time follow up time after cGVHD. The 3-year cumulative incidence of mild, moderate, and severe cGVHD was 3.4%, 11.5%, and 4.4%, respectively. The distribution of treatment response categories as TS, TD, or TR cGVHD are shown at 6, 12, and 24 months in the Sankey plot (Figure 1). Patients were most often TD at 6 months after diagnosis and transitioned to TS or TR by 24 months. Patients with moderate and severe cGVHD were equally likely to be either TD or TR at 6 months. By 12 months, most severe cGVHD cases were TR, while the TD group consisted mostly of moderate cGVHD cases. Patients with prior aGVHD, especially maximum grade III-IV aGVHD, were more likely to have TR cGVHD at 12 months. Patients over 18 were more likely to have TD or TR cGVHD. We noted no other significant risk factors associated with treatment response groups. The most common second-line cGVHD therapy used in addition to systemic corticosteroids was largely sirolimus, followed by cyclosporine and tacrolimus. We analyzed clinical outcomes by treatment response at 12 months from cGVHD diagnosis. 10-year FFS was lowest in TR followed by TD and TS groups (38%, 66%, 79%, respectively; P=0.01). Similarly, both 10-year overall survival and DFS were lowest in TR group followed by TD and TS groups. 10-year NRM was highest in TR and TD groups compared to the TS group (33%, 23%, 5%, respectively; P=0.13). In multivariate analysis, TR cGVHD was associated with worse overall survival at 12 months after cGVHD (HR 2.5 vs. no cGVHD; 95% CI, 1.7-3.7; P < .01) Conclusions We identified TR cGVHD as a significant risk factor for lower OS and FFS at 12 months post-diagnosis. TS and TD cGVHD groups showed similar prognoses, both better than the TR group. Our findings suggest that cGVHD treatment response states are important predictors of clinical outcomes. Additionally, we have shown that long term follow-up after cGVHD treatment is necessary to determine treatment sensitivity and therefore predict long term outcomes.

Omidubicel-Onlv for Allogeneic Transplantation (allo-HCT) in Patients with Hematologic Malignancies: Results of a Multicenter Open Label Expanded Access Program

Introduction Omidubicel-onlv is a nicotinamide-modified allogeneic hematopoietic progenitor cell therapy donor source derived from umbilical cord blood (UCB). A phase 3 randomized study (NCT02730299) demonstrated improved hematopoietic recovery and decreased infections in patients transplanted with omidubicel compared to UCB. An expanded access program (EAP) was conducted to provide access to omidubicel in advance of commercial availability in the United States (US) in April 2023. Objective This was an open-label, single-arm EAP evaluating clinical outcomes in patients with hematologic malignancies following allo-HCT with omidubicel. Methods Eligible patients (≥12 years) with hematologic malignancies received myeloablative conditioning, prophylactic medications, and supportive care as per institutional guidelines. Patients were monitored for neutrophil and platelet engraftment, infections, graft versus host disease (GVHD), and additional clinical events for up to 2 years post-transplantation. Results were retrospectively compared with previously described outcomes in patients from the phase 3 study comparing transplant with omidubicel (P3-OMI, n=52) and unmanipulated UCB (P3-UCB, n=56). Results Between July 2020 and April 2023, 36 patients were enrolled and 29 (18 males, 11 females) were transplanted at 5 US sites. Median age was 39 years (range: 20-73); 55% were White, 21% Asian, 17% Black, and 7% other. Diagnoses were acute myelogenous leukemia (38%), acute lymphocytic leukemia (28%), myelodysplastic syndrome (21%), and other (14%). All patients received myeloablative conditioning (total body irradiation-based: 58.5%, chemotherapy alone: 34.5%). Median transplanted CD34+ cell dose was 5.6x10 6 cells/kg (range: 1.8-18.7x10 6 cells/kg) and HLA match was 4/6 in 52%, 5/6 in 45%, and 6/6 in 3%. Median follow-up was 6.3 months (range: 0.3-27.7). No infusion reactions were reported. Median time to neutrophil (≥500/µl x3 days) and platelet (>20,000/µl x3 days) engraftment were 13 and 34 days, respectively. Primary graft failure occurred in 2 (6.9%) patients, both alive >100 days after second haploidentical transplant. The incidences of first grade 2-3 bacterial and invasive (grade 3) fungal infection through 100 days post-transplant were 16.9% and 0%, respectively. The incidence of grade 3 viral infections 1-year post-transplant was 13.4%. At 100 and 365 days post-transplant, disease-free survival (DFS) rates were 95.2% and 82.5%, and overall survival (OS) rates were 96.3% and 84.2%, respectively. Acute GVHD was reported in 13 (44.8%) patients (grade 2: 34.5%, grade 3: 10.3%) and mild chronic GVHD in 1 (3.5%) patient. There were 4 deaths (13.8%): 2 due to relapse (Days 275 and 381), 1 due to infection (Day 135) and 1 due to respiratory failure (Day 10). Post-transplant lymphoproliferative disease was reported in 1 patient. Demographic and disease characteristics were similar to those in the phase 3 omidubicel registration trial, including racial and ethnic diversity (>39% minorities). Neutrophil engraftment time in EAP patients was similar to P3-OMI (10 days) and shorter than P3-UCB (20.5 days). Similarly, median platelet recovery was similar to P3-OMI (37 days) and shorter than P3-UCB (50 days). Infection, GVHD, DFS, and OS in EAP were also similar to those observed in P3-OMI (Table 1). Conclusion In a real-world EAP setting, the outcomes of allo-HCT with omidubicel in patients with hematologic malignancies were consistent with those from the phase 3 registration study. These data support the role of omidubicel as a donor source, particularly for patients from diverse racial backgrounds.

Recurrence of HBV Reactivation after Allogeneic Hematopoietic Transplantation in Recipients with Resolved HBV Infection: A Nation-Wide Multicenter Retrospective Study

Introduction Reactivation of hepatitis B virus (HBV) is known to cause fulminant hepatitis after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in recipients with resolved HBV infection. Monitoring of HBV-DNA and HBV-DNA-guided preemptive therapy using nucleotide analogue (NA) is recommended to prevent developing hepatitis due to HBV reactivation after allo-HSCT. However, little is known about the adequate duration of NA treatment and the frequency of the recurrence of HBV reactivation (2nd HBV reactivation) after discontinuation of NA. We conducted a nationwide retrospective study of HBV reactivation after allo- HSCT. Patients and Methods We retrospectively reviewed the clinical information of recipients with resolved HBV infection (HBsAg-negative, anti-HBc-positive) before allo-HSCT and were diagnosed as HBV reactivation (HBsAg and/or HBV-DNA positive) after allo-HSCT from January 2010 to December 2020. Patients who received prophylactic NA before HBV reactivation were excluded. This study was approved by the Hokkaido University Hospital institutional review boards and registered as UMIN 000046803. Results A total of 72 patients were enrolled (median age of 60 years, range, 27-73 years; 42 males and 30 females) from 16 institutions. Initial hematological diseases were acute myeloid leukemia 21, myelodysplastic syndrome 14, chronic myeloid leukemia 4, acute lymphoblastic leukemia 12, non-Hodgkin lymphoma 8, adult T cell leukemia-lymphoma 6, mixed phenotype acute leukemia 4, and others 3. HSCT details were as follows: donor source, unrelated bone marrow 33, cord blood 24, related peripheral blood 11, unrelated peripheral blood 4; acute graft versus host disease (GVHD) 48 (66.7%); chronic GVHD 44 (61.1%); systemic steroid usage 41 (56.9%). Initial HBV reactivation after allo-HSCT was observed on day 10-3034 (median 512.5). Immunosuppressants and systemic steroids were administered in 35 (48.6%) and 28 (38.9%) patients respectively at the time of HBV reactivation. The patients who showed anti-HBs below protection levels (<10mIL/mL) were 18 (25%) of 72 patients at pre-HSCT, however, the number increased to 35 (81.4%) of 43 patients who were analyzed at the point of HBV reactivation after allo-HSCT. All patients received preemptive NA (entecavir 65, tenofovir alafenamide 6, tenofovir 1). Elevated aspartate transaminase of more than 200 U/L was observed in 7 cases at HBV reactivation, and all of them showed HBV-DNA more than 4 Log IU/mL. No one developed fulminant hepatitis but 5 patients resulted in continuous HBV carriers. Twenty-four of 72 patients were discontinued NA by each physician's decision. Of 24 patients who discontinued NA, 11 (45.8%) patients developed 2 nd HBV reactivation. The median duration from discontinuation of NA to 2 nd HBV reactivation was 113 days (range, 15 to 434). Duration of initial NA administration was not significantly different between patients with 2 ndHBV reactivation and those without 2 nd HBV reactivation (90-1968 days, median 553 vs 145-3734 days, median 861; p=0.11). In those who analyzed anti-HBs at discontinuation of NA, 4 of 8 cases (50.0%) with anti-HBs <10 mIU/mL developed 2 nd HBV reactivation, whereas only 1 of 6 cases (16.7%) with anti-HBs >10 mIU/mL developed 2 nd HBV reactivation. Four of the 11 cases with 2 nd HBV reactivation were attempted rechallenge of NA discontinuation, however, all 4 cases developed 3 rd HBV reactivation on day 28-127 after discontinuation of NA. These 4 cases further developed 4 th HBV reactivation after the rechallenge of discontinuation of NA. One patient developed protective anti-HBs titer after 2 courses of HB vaccination, and finally successfully discontinue the NA after 4 th HBV reactivation. The patient did not develop further reactivation for more than 3 years. Conclusion 2 nd reactivation of HBV after NA discontinuation was common in patients with HBV reactivation who received allo-HSCT despite the long duration of NA. Acquisition of anti-HBs by HBV reactivation itself or HB vaccine would be necessary to suppress further HBV reactivation. Careful monitoring of HBV-DNA is important even after the discontinuation of NA in the case with HBV reactivation after allo-HSCT because multiple reactivations could occur. A prospective randomized trial of the HB vaccine after allo-HSCT for preventing HBV reactivation is now ongoing (UMIN000034113).

Single CBT As 2nd Allo-SCT Is Promising for Selected Patients with Relapsed Hematopoietic Malignancies

Background: Hematopoietic malignancies that relapse after allogeneic stem cell transplantation (allo-SCT) generally have a poor prognosis, and there is no standard treatment. Second allo-SCT is a potentially curative treatment, but many patients do not receive 2nd allo-SCT at the best time because of the long preparation time for transplantation, and even if they do, treatment-related complications and relapse of the underlying disease often lead them to fatal outcomes. Umbilical cord blood is considered to be a promising source of 2nd allo-SCT because of its short preparation time, rapid and high graft-versus Leukemia (GVL) effect after transplantation, and better response to GVHD treatment compared to other donor sources. Therefore, we investigated the usefulness of cord blood transplantation for relapsed hematopoietic malignancies after allo-SCT. Methods: We retrospectively analyzed the outcomes of patients with hematopoietic malignancies who received single cord blood transplantation (CBT) as 2nd allo-SCT for relapse after allo-SCT in Toranomon Hospital between Apr. 1999 and Mar. 2022. We exclude the patients with Eastern Cooperative Oncology Group (ECOG) performance status(PS) of 4. Results: 263 patients were included in this study. There were 179 patients with myeloid neoplasms and 84 with lymphoid neoplasms. Median age was 45 years (range: 18-71). 239 patients were in non-remission and 24 in remission before SCT. Median interval between 1st SCT and 2nd SCT was 293 days (26-4703). Donor sources of 1st allo-SCT were related donor in 80, unrelated donor in 62, and sCBT in 121 patients. 135 patients received myeloablative conditioning for 2nd allo-SCT, and 128 patients underwent reduced intensity-conditioning. About cord blood as the donor source of 2nd allo-SCT, the median total nucleated cell count at cryopreservation was 2.71(×10 7)/kg (1.67-5.85), and median CD34 + cell count at cryopreservation was 0.97(×10 5)/kg (0.25-3.18). Median observation period of survivors was 1726 (122-6286) days after 2nd allo-SCT. Overall survival (OS), non-relapse mortality and relapse at 2-year were 16.7%, 46.9% and 40.6%, respectively. Younger patients (< 50 years) had significantly better OS than older patients (50 years and more), with 2-year OS of 21.5% and 9.9%, respectively (P < 0.001). Patients with good PS (0 and 1) had significantly better survival than those with poor PS(2 and 3), with 2-year OS of 23.4% and 2.4%, respectively (P<0.001). Patients with myeloid malignancies tended to have better survival than those with lymphoid malignancies, with 2-year survival rates of 19.2% and 11.9%, respectively (P=0.341). Patients with longer interval between SCTs (>1 year) had significantly better survival than those with shorter interval (<1 year), with 2-year OS of 23.6% and 11.6%, respectively (P=0.00443). In multivariate analysis, younger age (<50), good PS (0-1), long interval between SCTs(≧1 year) showed a superior OS. In the younger age population, patients with myeloid neoplasms showed a superior OS compared to those with lymphoid neoplasms (2yrOS: 30.3% vs 10.6%, P=0.00318). Furthermore, patients with myeloid neoplasms having good PS and long interval between SCTs showed an extremely high survival rate of 50.5% at 2 years (n=31)(Figure 1). In the elderly population, patients with long interval and good PS showed a relatively good OS of 31.4% at 2 years (n=28)(Figure 2). The type of disease (myeloid vs lymphoid) didn't have a significant influence on OS in this subpopulation (28.1% vs 50.0%, P=0.129). Conclusion: Although the outcomes of CBT as 2nd allo-SCT haven't been satisfactory, there are certain populations, including elderly patients, with favorable OS.

Outcomes of Tcrαβ and CD19-Depleted Hematopoietic Stem Cell Transplantation from Matched, Mismatched Unrelated and Haploidentical Donors for Pediatric Patients with Hematological Malignancy: A Meta-Analysis

Introduction: TCR αβ+/CD19+ depletion in hematopoietic stem cell transplantation (HSCT) is an emerging graft manipulation technique to help overcome the HLA barrier in the mismatched or haploidentical transplant setting and reduce or prevent graft-versus-host disease. Limited research has explored the impact of various donor sources, and type of malignancy on the outcomes of TCR αβ+/CD19+ depleted HSCT for acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), and myelodysplastic syndrome (MDS). Therefore, we performed a comprehensive meta-analysis of published clinical studies using individual patient data (IPD) to address this scientific gap. Methods: This meta-analysis combined patient-level data from studies involving AML/MDS and ALL patients treated with TCR αβ+/CD19+ depleted HSCT. By utilizing the IPDfromKM technique, we reconstructed time-to-event data from aggregated Kaplan-Meier curves, specifically focusing on overall survival (OS), disease-free survival (DFS), and GVHD-free, relapse-free survival (GRFS). Additionally, we conducted parallel meta-analyses to calculate the pooled incidences of GVHD, graft failure, mortality, as well as CMV and EBV reactivation, and sinusoidal obstruction syndrome (SOS) using aggregate data. All analyses were performed using STATA software. Our comprehensive literature search included publications up to May 2023, excluding studies with significant sample overlap. Results: The meta-analysis incorporated 817 children with AML/MDS or ALL from 12 studies. Successful primary engraftment was observed in 95% of patients (95% CI: 92 - 98), with an average time to neutrophil and platelet engraftment of 12 days. The incidence of acute GVHD grades I-II was 24% (95% CI: 14 - 34), while grades III and IV were 11% (95% CI: 3.0 - 0.18). Chronic GVHD was observed in 19% of patients (95% CI: 11 - 28). The relapse and graft failure rates were 25% (95% CI: 19 - 32) and 6% (95% CI: 2.0 - 9.0), respectively. The all-cause mortality was 34% (95% CI: 29 - 38), with HSCT-related mortality at 11% (95% CI: 8.0 - 13), while relapse-related mortality accounted for 22% (95% CI: 17 - 28). At a median follow-up of 2.55 years, the 1-year and 5-year OS rates were 74.7% (95% CI: 60.6 - 78.3) and 64.4% (95% CI: 59.9 - 68.5), respectively. No significant differences in OS were found between ALL and AML/MDS patients (HR= 0.99, 95% CI: 0.48 - 2.02, P=0.98) or between different donor types (Figure 1A). The DFS rates at 1- and 5-year were 72.8% (95%CI: 67.6 - 77.3) and 61.8% (95%CI: 56.1 - 67.0), respectively. No significant differences in DFS were observed between ALL and AML/MDS patients (HR = 0.74 95%CI: 0.48 - 1.14, P=0.17) or between different donor types (Figure 1B). The overall 1- and 5-year GRFS rates were 71.1% (95% CI: 64.1 - 77.4) and 63.0% (95% CI: 55.3 - 69.8), respectively. The overall incidence of CMV and EBV reactivation was 33% (95% CI: 19 - 46) and 16% (95% CI: 0 - 38), respectively. Conclusions: Our meta-analysis confirms the effectiveness and safety of TCRαβ and CD19-depleted HSCT for hematological malignancies, demonstrating high engraftment success, low graft failure, and a manageable incidence of acute and chronic GVHD. The consistently favorable outcome data across different donor types and malignancies support the broad applicability of this form of graft manipulation.

Clinical Effects of Tacrolimus Blood Concentrations Early after Allogeneic Hematopoietic Stem Cell Transplantation

Tacrolimus (TAC) plus short-term methotrexate (stMTX) is used for graft-versus-host disease (GVHD) prophylaxis after allogeneic hematopoietic stem cell transplantation (allo-HSCT). TAC blood concentrations are frequently adjusted to enhance the graft-versus-leukemia/lymphoma effect or attenuate severe GVHD. Limited information is available on the clinical impact of these adjustments and the optimal time to perform them in order to achieve good clinical outcomes. We retrospectively analyzed 211 patients who underwent allo-HSCT at our institutes. Higher TAC concentrations in week 3 correlated with a significantly higher cumulative incidence of relapse (CIR) (p=0.03) and lower non-relapse mortality (p=0.04). The clinical impact of high TAC concentrations in week 3 on CIR was detected in the refined disease risk index: low/intermediate (p=0.04) and high (p<0.01), and conditioning regimens other than cyclophosphamide/total body irradiation and busulfan/cyclophosphamide (p=0.07). Higher TAC concentrations in week 1 correlated with a lower grade 2-4 acute GVHD rate (p=0.01). Higher TAC concentrations in weeks 2 and 3 correlated with slightly lower (p=0.05) and significantly lower (p=0.02) grade 3-4 acute GVHD rates, respectively. Higher TAC concentrations in weeks 1 and 3 were beneficial for severe acute GVHD in patients with a human leukocyte antigen-matched donor (p=0.03 and p<0.01, respectively), not treated with anti-thymocyte globulin (p=0.02 and p=0.02, respectively), and receiving three stMTX doses (p=0.03 and p=0.02, respectively). The clinical impact of TAC concentrations varied according to patient characteristics, including disease malignancy, conditioning regimens, donor sources, and GVHD prophylaxis. These results suggest that TAC management needs to be based on patient profiles.

Lower Cumulative Incidence of Relapse but Higher Incidence of NRM in Patients with Poor Graft Function Following Allogeneic Stem Cell Transplantation

Introduction Poor Graft Function(PGF), defined as multilineage cytopenias in the setting of complete donor chimerism is a significant complication of allogeneic stem cell transplantation (alloSCT). Recently our group, in a published retrospective analysis of 929 patients, demonstrated that the following factors were associated with the development of PGF: Non matched sibling donor, ICU admission/ positive blood cultures within 1 st 30 days of alloSCT, severe graft versus host disease (GVHD), CMV viremia (Prabahran et al 2021). We extended our prior cohort study to validate risk factors previously associated with PGF and describe outcomes such as recovery from PGF, relapse and non-relapse mortality following a diagnosis of PGF. Methods This was a retrospective analysis of alloSCT recipients at our institution from 2017-2020. Patients 17 years and older were included. Patients who died prior to D60 of alloSCT were excluded as chimerism data was often not available prior to this timepoint. PGF was defined as follows: 1) ≥95% donor chimerism at last reading OR ≥95% CD3 negative chimerism; 2) ≥2 Lineage cytopenias defined as: Thrombocytopenia :≤30x10 9 /L from D40-D60 OR ≤50 x10 9/L from D60 onwards; neutropenia requiring filgrastim support at any time post D40; Hb <80g/L. Factors associated with PGF were evaluated using a logistic regression, with development of PGF being the dependent variable. The predictive power of the subsequent logistic regression model was validated utilizing bootstrapping re-sampling procedure and testing of the concordance index (C-index). Variables associated with PGF were also evaluated in a cox-proportional model and coded as time-dependent covariates. Relapse and non-relapse mortality (NRM) were evaluated in a competing risk model from a landmark of 200 days post alloSCT, performed as per the method of Fine and Gray. Results 308 patients were included in the analysis of which 259 patients did not have PGF (nPGF) and 49 had PGF. Baseline variables of nPGF and PGF patients were matched for median age (53 versus 56 p=0.28), recipient sex (68% versus 65% male, p=0.74)), median CD34 dose (5.00 versus 5.2 x10 9/L p=0.49), donor source (p=0.12) and CMV serostatus (p=0.23). In multivariate analysis, ICU admission within 30 days (p=0.002), non-CMV viral infections (p=0.032) and GVHD (p<0.001) were associated with the development of PGF. The c-index of the model at baseline was 0.77 and 0.75 after bootstrapping validation indicating reasonable predictive performance of this model. ICU admission, non-CMV viral infections and GVHD were still significantly associated with the development of PGF when utilised as time dependent variables in a cox-regression model. Patients with PGF had worse 2-year survival compared to nPGF (60 versus 75% p=0.02). PGF patients without marrow recovery at last follow up had a 6-month OS of 20%. Twenty three out of 49 patients recovered marrow function at last follow up with a median duration of cytopenias of 142 days (51-789). The cumulative incidence (CI) of recovery was 44% and 53% at 1- and 2-years following onset of cytopenias respectively. From a landmark of 200 days (33 patients excluded due to death prior to this timepoint) PGF patients had a higher CI of NRM (Figure 1A =0.001) but lower CI of relapse (Figure 1B p=0.027) compared to nPGF patients. Conclusions PGF is strongly associated with early ICU admission, severe GVHD and non-CMV viral infections. Survival is inferior in patients with PGF particularly those with poor marrow recovery and this is mainly driven by non-relapse mortality. The lower CI of relapse in PGF is a novel finding of this study and may suggest a protective effect of PGF against the development of relapse but this finding requires further validation in external cohorts.

Pre-Transplant Levels of Multiparametric Flow-Cytometry Measurable Residual Disease (MFC-MRD) Predict Outcomes in Children with Acute Myeloid Leukemia Given Allogeneic Hematopoietic Stem Cell Transplantation

Background: Measurable residual disease assessed by multiparametric flow-cytometry (MFC-MRD) is largely used in trials for childhood de novo acute myeloid leukemia (AML) in the early phase of treatment, to stratify patients into different risk groups and to tailor treatment. Despite this, unlike acute lymphoblastic leukemia, the impact of MFC-MRD before allogeneic hematopoietic stem cell transplantation (HSCT) on patients' outcomes has yet to be established. The aim of this study was to evaluate the prognostic role of MFC-MRD before HSCT in a cohort of children with AML treated in centers belonging to Associazione Italiana Ematologia/Oncologia Pediatrica (AIEOP) cooperative group. Patients and Methods: We analyzed MFC-MRD in 208 pediatric patients affected by de novo AML who underwent a first allo-HSCT after a myeloablative conditioning regimen in an AIEOP Centre between 12/2011 and 12/2021. Assessment of MFC-MRD was performed on BM sample within 60 days from the transplantation date. Analysis of 5-10 color-panel MFC-MRD was centrally performed at the Laboratory of Diagnosis and Research, University of Padova, according to standardized operating procedures previously described (Buldini et al., BJH 2017). We defined MFC-MRD positivity as the presence of at least 50 leukemic events of 500,000 acquired nucleated cells. Five-year overall (OS) and event-free survival (EFS) were estimated using Kaplan and Meier method and differences between groups were tested using the log-tank test; the cumulative incidence of relapse (CIR) and non-relapse mortality (NRM) were calculated using the Fine&Gray method to take into account the respective competitive risks. Results: Median age at HSCT of these 208 patients was 7.8 years (range 0.4-23.3); 168 patients (80.8%) were transplanted in CR1, 30 (14.4%) in CR2 and 10 (4.8%) in CR3 or more advanced disease. Forty-eight patients (23.1%) were transplanted from a matched family donor, 85 (40.9%) from an unrelated donor (59 fully-matched and 26 mismatched), while 75 (36%) from a partially matched family donor. The source of stem cells was bone marrow in 117 patients (56.2%), peripheral blood in 81 (39%) and cord blood in 10 (4.8%). Median time from MRD evaluation and HSCT was 22 days (range, 6-57). Overall,168 out of 208 (78.9%) patients were MFC-MRD negative in the pre-HSCT BM, while 44/208 (21.1%) showed a positive MFC-MRD. Among those, MFC-MRD was < 0.1% in 12/44 (27%) patients, 0.1-<1% in 16 patients (36.5%) and ≥ 1% in 16 patients (36.5%). The 5-year OS and EFS of the whole cohort were 79.2% and 65.7%, respectively, while CIR and NRM were 24.7% and 8.6%. Notably, patients with negative MFC-MRD had a significantly better 5-yr OS and EFS (Fig.A) as compared to those with any MFC-MRD positivity (OS 86.3% vs 50.2%; EFS 71.6% vs 42.4%, p <0.0001 in both analysis). CIR significantly differed between patients with MFC-MRD negative and positive (21.1% vs 43.9%, p=0.001) (Fig.B). We also observed a higher NRM in patients with MFC-MRD positivity (13.6%) as compared to those with negative MFC-MRD (7.2%), although this was not statistically significant (p=0.1). Disease status (CR1 vs CR2 vs other CR) did also influence EFS (69.9% vs 55.6% vs 23.3%, p<0.001), OS (83.2% vs 66.6% vs 40.6%, p=0.02) and CIR (21.1% vs 37.7% vs 66.6%, p<0.001), while other variables (including year of HSCT, type of donor and stem cell source employed) did not. In a multivariable model for OS, EFS and CIR, including MFC-MRD, disease status and year of HSCT, MFC-MRD (pos vs neg) remained statistically significant (HR for OS 3.5, p=0.0004; HR for EFS 2.38, p=0.003; HR for CIR 2.14, p=0.02). In addition, advanced disease phase was an independent risk factor for CIR (HR 1.81, p=0.008). Conclusion: These data document the independent prognostic value of MFC-MRD before HSCT in a large cohort of pediatric AML patients, using a centralized evaluation by 5-10 color MFC. Patients with negative MFC-MRD before HSCT have a significantly lower risk of treatment failure. In light of these results, we recommend monitoring MFC-MRD before HSCT in pediatric AML patients as a critical tool for therapy-intervention decision before or after HSCT (e.g., additional treatment for improving leukemia control or less intensive/shorter GvHD prophylaxis) with the aim to improve patients' outcomes.

Combined Cytokine Blocking Therapy (CCBT) Using Basiliximab and Infliximab for Treatment of Steroid-Refractory Graft Versus Host Disease (SR-GvHD)

Background Despite improved advances in graft-vs-host disease (GvHD) prophylaxis regimens and post-allogeneic hematopoietic cell transplant (HCT) supportive care, clinically significant acute GvHD still develops in approximately 30-50% of HCT recipients (Lazaryan A et al. BMT 2016) and often results in increased transplanted-related morbidity and mortality and deterioration of quality of life (Choi J et al. Blood 2012). Standard first-line treatment is high-dose glucocorticoids have been limited including recently approved JAK2 inhibitor (ruxolitinib). The utilization of combined cytokine blockade therapy (CCBT) with the monoclonal antibodies infliximab (a TNF-α inhibitor, INF) and basiliximab (an IL-2 receptor blocker, BAS), has had limited discussion in the literature despite common utilization. The primary objective of this retrospective study was to determine overall response rate (ORR) at days 7, 14 and 28 for CCBT. Secondary outcomes included non-relapse mortality (NRM), and overall survival (OS). Methods 60 patients who met the inclusion criteria were analyzed. Patients included were ≥18 years old and had undergone HCT using any donor or graft source with any conditioning regimen between 2010-2021 at City of Hope Medical Center in Duarte, CA. Patients had steroid refractory aGvHD, according to Mount Sinai Consortium guidelines (Harris AC et al. BMT 2016) and received at least one dose of BAS and at least one dose of INF. Patients with >1 allogeneic transplant, chronic GVHD including overlap syndrome, relapse of primary disease, graft loss, and glucocorticoid treatment for indications other than GVHD were excluded. Treatment BAS was administered intravenously as 20mg doses given first as loading doses on days 1 and 4. Subsequent doses were given weekly starting 7 days after the final loading dose (day 4). INF was administered as 10 mg/kg doses infused weekly. Tacrolimus, sirolimus and cyclosporine dosing and monitoring were performed in accordance with institutional policies. All patients had clinical presentation of SR-GVHD defined as ≥1 of the following: GVHD increasing in stage in any organ or developing in a new organ after 3 days of ≥2 mg/kg methylprednisolone (MSPE) or equivalent, GVHD that has not improved in stage in ≥1 organ after 7 days of ≥2 mg/kg MSPE or equivalent, development of GVHD in a new organ after ≥1 mg/kg MSPE or equivalent for skin GVHD or patients who progress during tapering before a 50% decrease in glucocorticoids is achieved. Results The median age was 53 years (range, 5-78) at time of HCT. Of 60 patients, 65% were males and with 18.3% of male patients receiving grafts from female donor. HCT-CI at the time of HCT was 3 or more in 47% of the patients. Conditioning for those patients was ablative in 43.3% of patients with 76.7% of patients receiving PBSC grafts from mostly MSD/MUD in 75% of patients. Most patients had grade 3 or 4 overall acute GVHD (grade 3: n=35, 58.3%, grade 4: n=20, 33.3%). Median time to start of BAS after start of steroid was 7 days while time to start of INF after steroid was 11 days. Ruxolitinib was initiated in 33.3% (20/60) of patients prior to CCBT. ORR for CCBT therapy at day 7, 14, and 28 were 28.3% (17/60; CR 5.0%), 38.3% (23/60; CR 11.7%), and 38.3% (23/60; CR 23.3%), respectively. Patients who received ruxolitinib prior to CCBT had lower ORR (25%) compared to those who did not (47.5%). 37 patients died-20 of aGVHD, 4 of infection, 1 of sudden cardiac death and 1 of leukemia relapse. OS was 41.7% at 6 months and 36.5% at 12 months (Figure 1A). Cumulative incidence of NRM was 51.7% at 6 months and 55% at 12 months (Figure 1B). Cumulative incidence of any cGvHD was 33.6% at 12 months while it was 30% for extensive cGvHD at the same 12-month interval. In patients with and without ruxolitinib initiated prior to CCBT, OS at 12 months was 30% vs 40%, respectively (Figure 2A) while NRM at 12 months was 65% and 50%, respectively (Figure 2B). Conclusion CCBT has potential efficacy in steroid refractory aGVHD. The observed ORR is reflective of both advanced and highly refractory aGVHD with one-third of patients progressing on ruxolitinib. Given the favorable observed ORR in this difficult to treat population, CCBT is a potentially promising approach and suitable alternative in the second line or as salvage therapy in patients failing Ruxolitinib.

Geriatric Nutritional Risk Index Is an Important Predictor of Survival in Allogeneic Hematopoietic Stem Cell Transplant Recipients

Introduction:The body mass index (BMI) and geriatric nutritional risk index (GNRI) are nutrition-related risk assessment tool and has been used in various clinical settings. The relationship between BMI and the associated risk of hematopoietic stem cell transplantation (HSCT), such as relapse and non-relapse mortality (NRM), have been reported (Fuji S et al. BMT. 2014;49:1505). However, the relationship between GNRI and HSCT outcome remains inconclusive. We aimed to evaluate the association between GNRI and overall survival (OS), relapse, and NRM of patients who received allogenic HSCT for hematological malignancies. Methods:We retrospectively analyzed aged 16 years or older patients who underwent first allogeneic HSCT from January 2010 to December 2022 at the Jikei university hospital. The primary endpoints of this study was OS at 5 years. Secondary endpoints were NRM, the incidences of relapse, all-grade acute GVHD and chronic GVHD. Nutritional risk was evaluated both BMI and GNRI. Patients were classified into three groups based on pre-transplant BMI (underweight; BMI <18.5, overweight; BMI ≥25, and others as standard), and also classified into three groups based on pre-transplant GNRI (low-risk; GNRI>98, intermediate-risk; 92≤GNR≤98, and high-risk; GNR<92). GNRI was calculated as follows: (1.519 x serum albumin) + (41.7 x current body weight/ ideal body weight). Data on serum albumin level and body weight were collected at the beginning of conditioning regimen. Results:Two hundred and three patients who received allogeneic HSCT for hematological malignancies (acute myeloid leukemia; n=98, acute lymphoblastic leukemia; n=51, myelodysplastic syndrome; n=27, myeloproliferative neoplasms; n=8, chronic myeloid leukemia; n=18, and other leukemias; n=2) were evaluated. The median age was 52 years old (range 16-69). The median follow-up period of survivors was 1394 days (range 51-4420) after allogeneic HSCT. The donor sources consisted of 39 (19.2%) HLA-matched related donor, 50(24.6%) HLA-mismatched related donor, 26(12.8%) HLA-matched unrelated donor and 88(43.4%) HLA-mismatched unrelated donor. One hundred and nine patients (53.7%) received myeloablative conditioning regimens. Based on the BMI, underweight, standard, overweight were included 33 (16.3%), 139 (68.4%), and 31 (15.3%) patients, respectively. While, based on the GNRI, the low-risk, intermediate-risk and high-risk were divided into 105 (51.7%), 46 (22.8%), and 51 (25.2%) patients, respectively . The 5-year OS rates of standard, underweight, and overweight were 52.6%, 39.5%, and 62.1%, respectively (p=0.07). On the other hand, the 5-year OS of low-risk, intermediate-risk, and high-risk were 62.6%, 50.4%, and 33.2%, respectively (p=0.01). In addition, multivariate analysis showed high-risk group showed significantly lower OS (p=0.03). Five-year cumulative incidences (CI) of relapse in the standard, underweight, and overweight, were 46.4%, 45.4%, and 25.0%, respectively (p=0.11). However, multivariate analysis showed that CI of relapse ratio was significantly lower in overweight group (p=0.02). While, 5-year CI of relapse rates in the low-risk, intermediate-risk, and high-risk were 36.5%, 47.2%, and 52.5%, respectively (p=0.03). However, multivariate analysis showed that there were no significant differences in relapse among three risk groups (p=0.06). There were no significant differences in CI of NRM, acute GVHD and chronic GVHD either BMI or GNRI. Subgroup analysis in the patients who underwent HSCT in complete remission revealed that there was no significant difference in OS among the three BMI groups (p=0.11), as well as the three GNRI groups (p=0.06). For the patients in non-remission at the time of allogeneic HSCT, there was no significant difference in OS between the three groups in BMI; however, OS was shorter in the high-risk group in GNRI (p=0.01). Conclusions:In our study, OS of high-risk group defined by GNRI showed significantly poor , especially in non-remission patients. Although overweight defined by BMI did predict low CI of relapse, overweight did not predict OS. These results suggest that nutrition-related risk assessed by GNRI could be prognostic marker for survival in patients who received allogeneic HSCT.

Survival Outcome of Autologous or Allogeneic Stem Cell Transplantation in 49 Patients with Extranodal NK/T-Cell Lymphoma

Objective:Extranodal NK/T-cell lymphoma (ENKTL) is an uncommon tumor featured by high invasiveness, the ease of developing drug resistance, low curative rate, and short survival time. Hematopoietic stem cell transplantation (HSCT) is now recommended for patients with advanced or relapsed/refractory (r/r) ENKTL, but which HSCT is the most suitable remains to be conclusively determined. Here, we performed a retrospective single-center study to compare the prognostic role of autologous and allogeneic HSCT after induction chemotherapy in ENKTL patients. Methods: Clinical data on 49 ENKTL patients who underwent HSCT in the First Affiliated Hospital of Soochow University from 8/2007 to 9/2022 was reviewed. We divided all patients into two subgroups: cohort A) auto-HSCT and cohort B) allo-HSCT. Observation period started from the day of stem cell infusion in both cohorts. The primary endpoint was overall survival (OS). The secondary endpoints were progression-free survival (PFS) and non-relapse mortality (NRM). NRM was defined as death from any cause related to transplantation without evidence of lymphoma progression. Results: Of 49 patients included, 28 (57%) patients received auto-HSCT (cohort A), while 21 (43%) patients received allo-HSCT (cohort B). The two cohorts of patients were different in some terms of baseline characteristics (Figure A). A total of 8 patients with stageⅡdisease received transplantation due to r/r status or primary lesions beyond the nasal area. The patients in cohort B were younger at the time of transplant (median age: 33 years vs. 37 years, p=0.0031) and had a higher proportion of bone marrow involvement (7% vs. 43%, p=0.005). After a median follow-up of 35 months, patients who received allo-HSCT had a worse prognosis compared to patients who underwent auto-HSCT (2-year OS:61% vs 96%, p=0.0015). There was no transplantation-related mortality in the auto-HSCT group, while the NRM was 33.3% in the allo-HSCT group. Limiting the analysis to only patients with complete remission (CR) (allo-HSCT=13, auto-HSCT=25) before HSCT, no differences in 2-year OS and PFS were reported despite 61% vs 4% bone marrow involvement, respectively (76% vs 96% OS and 76.9% vs 84.1% PFS at +24 months, p>0.05). In the allo-HSCT group, patients who achieved first CR(CR1) before HSCT showed higher OS and lower NRM rates compared to those without CR1, with 2-year OS of 88.9% and NRM of 11.1% (p=0.028, p=0.06, respectively). In terms of donor sources, no significant difference in PFS and OS was observed in patients who received haploid conjugate (n = 14) vs. HLA-matched related and unrelated donors(p>0.05). Conclusions: Overall, consolidation therapy with HSCT improved OS in patients with advanced or relapsed/refractory ENKTL who achieved CR after induction therapy. Given the high NRM in the allo-HSCT, auto-HSCT is probably the preferred clinical option in most patients and allo-HSCT may be more appropriate for younger patients with bone marrow involvement and CR1 acquired before transplantation. Larger studies are needed to validate our results.

Hematopoietic Cell Transplantation Trends and Outcomes in Canada: A Registry-Based Cohort Study.

Background: Hematopoietic cell transplantation (HCT) is an established therapy for hematologic malignancies and serious non-malignant blood disorders. Despite its curative potential, HCT is associated with substantial toxicity and health resource utilization. Effective delivery of HCT requires complex hospital-based care, which limits the number of HCT centres in Canada. In Canada, the quantity, indications, temporal trends, and outcomes of patients receiving HCT are not known. Methods: A retrospective cohort study of first transplants reported to the Cell Therapy Transplant Canada (CTTC) registry between 2000 and 2019. We determined overall survival (OS) and non-relapse mortality (NRM), categorizing the cohort into early (2000-2009) and later (2010-2019) eras to investigate temporal changes. Results: Of 18,046 transplants, 7571 were allogeneic and 10,475 were autologous. Comparing the two eras, allogeneic transplants increased in number by 22.3%, with greater use of matched unrelated donors in the later era. Autologous transplants increased by 10.9%. Temporal improvements in NRM were observed in children and adults. OS improved in pediatric patients and in adults receiving autologous HCT. In adults receiving allogeneic HCT, OS was stable despite the substantially older age of patients in the later era. Interpretation: HCT is an increasingly frequent procedure in Canada which has expanded to serve older adults. Noted improvements in NRM and OS reflect progress in patient and donor selection, preparation for transplant, and post-transplant supportive care. In allogeneic HCT, unrelated donors have become the most frequent donor source, highlighting the importance of the continued growth of volunteer donor registries. These results serve as a baseline measure for quality improvement and health services planning in Canada.

Endothelial Activation and Stress Index in adults undergoing allogeneic hematopoietic cell transplantation with post-transplant cyclophosphamide-based prophylaxis

Background aimsPost-transplant cyclophosphamide (PTCY)-based prophylaxis is becoming widespread for allogeneic hematopoietic cell transplantation (allo-HCT) performed independently of the selected donor source. In parallel, use of the Endothelial Activation and Stress Index (EASIX)—considered a surrogate parameter of endothelial activation—for predicting patient outcomes and clinical complications is gaining popularity in the allo-HCT setting. MethodsWe first investigated whether the dynamics of EASIX after allo-HCT differ between patients receiving PTCY and patients receiving other prophylaxis. We then investigated whether the predictive capacity of EASIX persists in PTCY-based allo-HCT. A total of 328 patients transplanted between 2014 and 2020 were included, and 201 (61.2%) received PTCY. ResultsEASIX trends differed significantly between the groups. Compared with patients receiving other prophylaxis, patients receiving PTCY had lower EASIX on day 0 and higher values between day 7 and day 100. In patients receiving PTCY, higher EASIX correlated significantly with higher non-relapse mortality (NRM) and lower overall survival (OS) when measured before and during the first 180 days after allo-HCT. In addition, higher EASIX scores measured at specific time points were predictors of veno-occlusive disease (VOD), transplant-associated thrombotic microangiopathy (TA-TMA) and grade 2–4 acute graft-versus-host disease (aGVHD) risk. ConclusionsThis study demonstrates how EASIX trends vary during the first 180 days after allo-HCT in patients receiving PTCY and those not receiving PTCY and validates the utility of this index for predicting NRM, OS and risk of VOD, TA-TMA and grade 2–4 aGVHD in patients receiving PTCY.