Outcomes Of Allogeneic Hematopoietic Stem Cell Transplantation Research Articles

The Presence of Somatic Mutation in Donor Does Not Affect Long-Term Outcomes in 339 Patients Following Allogeneic Hematopoietic Stem Cell Transplantation Using Uniform Fludarabine/Busulfan Myeloablative Conditioning and Cyclosporine/Methotrexate and ATG Gvhd Prophylaxis

Introduction: Clonal hematopoiesis with indeterminate potential (CHIP) constitutes a part of the biological aging process and comprises the acquisition of somatic mutations in hematopoietic stem cells (HSCs). In the context of allogeneic hematopoietic stem cell transplantation (HCT), the potential transfer of CHIP from donor to recipient may raise concerns on HCT-related complications. There are contradictory data on donor CHIP's impact on long-term transplant outcomes using very diverse conditioning regimen as well as various graft-versus-host disease (GVHD) prophylaxis. This study aims to evaluate the impact of donor CHIP on allogeneic HCT outcomes in a cohort of the patients transplanted using a uniform, myeloablative intensity conditioning of Fludarabine-Busulfan (4 days) as well as Cyclosporine/Methotrexate with 4.5 mg/kg rabbit antithymocyte globulin (ATG) over 3 days for GVHD prophylaxis. Patients and methods: Peripheral blood samples were obtained from recipients and their corresponding donors who underwent allogeneic HCT at Tom Baker Cancer Centre, Calgary, Canada. Samples were archived from 339 patients and 255 donors prior to HCT, and additional patient sampling was done on day 28 (D28), day 56 (D56), or day 84 post allogeneic HCT (D84). As a result, paired recipient-donor samples were available for 255 HCTs. This study was approved by the institutional review boards of Princess Margaret Cancer Centre, Toronto, and Tom Baker Cancer Centre, Calgary. For the detection of CHIP, we have applied a bar-coded error-corrected sequencing protocol, a single-molecule molecular inversion probe capture protocol (NAR Genom Bioinform, 2022), which was performed at Wiesmann Institute of Science (Rehovot, Israel). We designed probes targeting 34 genes covering CHIP mutations along with other AML related mutations. Bar-coded NGS library was generated and processed. All statistical analyses were performed using R statistical software 3.5.0 and EZR version 1.41. Results: Sixty-seven clonal mutations in 56 recipients (18.2%) and 22 clonal mutations in 18 donors (7.1%) were detected prior to HCT. For recipients, TET2, JAK2, RUNX1, PPM1D, and DNMT3A were detected in at least 2 patients or more. For donors, the most frequently mutated gene was TET2 (3.1%), and the seconds were DNMT3A and PTPN11 (1.2% for both). Baseline characteristics of 255 patient-donor pairs did not show any difference between D-CHIP and no D-CHIP groups except donor age. Donor CHIP status was distributed evenly throughout most of the demographics of recipients, type of disease, pre-transplant status, and transplant procedure. Most of the pts received peripheral blood stem cells (97%). With a median follow up duration 6.02 years, the 5-year OS rates tend to be higher in no D-CHIP group than D-CHIP group (63.1% vs 42.8%) with a HR of 1.73 (95% CI [0.90-3.35]), although it was not statistically significant (p=0.096). The cumulative incidence of relapse for both groups were not different in 5 years (28.1% vs. 28.4%, p=0.849). The cumulative incidence of NRM within 5 years in D-CHIP group was slightly higher than no D-CHIP group (28.4% vs 17.5%), but it was not statistically significant (p=0.250). Neutrophil engraftment by day 28 was 99.1% vs. 100%, without statistical difference between the two groups (p=0.785). The cumulative incidence of grade II-IV acute GVHD within day+100 seemed to be higher in D-CHIP group compared to no D-CHIP group, but it was not statistically significant (24.8% vs. 34.5%, p=0.148; Figure A). In terms of chronic GVHD, cumulative incidence of moderate to severe GVHD was significantly higher in 5 years after transplant (29.4% vs. 58.8%; HR 2.55 [1.331-4.96], p=0.006; Figure B). Even when we set the cut off level of donor CHIP positivity up to >1% or >10%, the association between donor CHIP and risk of chronic GVHD remained significant. The impact of donor CHIP on the cumulative incidence of moderate to severe GVHD was confirmed in multivariate analysis (HR 2.3 [1.3-4.1], p=0.003). Other factors associated with moderate to severe chronic GVHD were previous history of grade II-IV acute GVHD (p=0.008) and donor type (p=0.054). Conclusion: Under clinical setting of uniform conditioning regimen and GVHD prophylaxis incorporating ATG (4.5mg/kg), donor CHIP was found to be associated with higher risk of moderate to severe chronic GVHD, while it does not affect other allogeneic HCT outcomes.

The two-step approach to allogeneic hematopoietic stem cell transplantation.

Allogeneic hematopoietic stem cell transplantation (HSCT) provides the only potentially curative option for multiple hematological conditions. However, allogeneic HSCT outcomes rely on an optimal balance of effective immune recovery, minimal graft-versus-host disease (GVHD), and lasting control of disease. The quest to attain this balance has proven challenging over the past few decades. The two-step approach to HSCT was conceptualized and pioneered at Thomas Jefferson University in 2005 and remains the main platform for allografting at our institution. Following administration of the transplant conditioning regimen, patients receive a fixed dose of donor CD3+ cells (HSCT step one-DLI) as the lymphoid portion of the graft on day -6 with the aim of optimizing and controlling T cell dosing. Cyclophosphamide (CY) is administered after the DLI (days -3 and -2) to induce donor-recipient bidirectional tolerance. On day 0, a CD34-selected stem cell graft is given as the myeloid portion of the graft (step two). In this two-step approach, the stem cell graft is infused after CY tolerization, which avoids exposure of the stem cells to an alkylating agent, allowing rapid count recovery. Here, the two-step platform is described with a focus on key results from studies over the past two decades. Finally, this review details lessons learned and current strategies to optimize the graft-versus-tumor effect and limit transplant-related toxicities.

DURABLE LONG‐TERM REMISSION IN HIGH‐RISK RELAPSE REFRACTORY LYMPHOMA—20 YEARS’ EXPERIENCE OF ALLOGENEIC HAEMOPOIETIC STEM CELL TRANSPLANT IN SINGAPORE

Background: Allogeneic hematopoietic stem cell transplantation (AlloHSCT) is a curative option for those who have high risk relapsed/refractory lymphoma in the era of novel and cellular therapies including CAR-T cell. There is a paucity of data evaluating the long term outcomes of AlloHSCT in Asian lymphoma patients. We performed a retrospective analysis of 20 years to evaluate the prognostic factors and outcomes of AlloHSCT for lymphoma patients in Singapore. Methods: We evaluated 121 lymphoma patients (both non-Hodgkin (NHL) and Hodgkin lymphoma (HL)) from two major transplant centres in Singapore who had AlloHSCT over a 20-year period (2003–2022). Results: The 121 patients have a median age of 41 (range 16–71). Diagnoses include B-NHL (N = 41, diffuse large B cell lymphoma n = 21, follicular lymphoma n = 2, mantle cell lymphoma n = 6, primary mediastinal B cell lymphoma n = 5, chronic lymphocytic leukemia n = 7), T-NHL (N = 38, peripheral T cell lymphoma n = 32, other T-NHL n = 6), NK T cell (N = 24) and HL (N = 18). 84% received reduced intensity conditioning (RIC), and 27.3% had a previous transplant. Donor types include matched sibling donor (N = 54), matched unrelated donor (N = 35), Haplo-identical donors (N = 23) and Cord blood (N = 9). With a median duration of follow up of 56 months (range 0–232 months), the 4-year progression free survival (PFS) and overall survival (OS) were 38% and 45% respectively. The non-relapse mortality was 11.6% at day 100 and 24% at 1 year. The cumulative incidence of acute graft-versus-host disease (GvHD) was 36.4% with 5 patients having grade IV acute GvHD. On univariate analysis, patients who were in complete remission (CR) at the time of AlloHSCT and those who have been given RIC had improved OS. Subset analyses showed that the outcomes of AlloHSCT for relapsed/refractory Hodgkin lymphoma were the most favourable (4-year PFS and OS at 61.2% and 62% respectively), whereas patients with T-NHL, B-NHL and NK T cell lymphoma had lower survival rates (4-year PFS 35%, 44%, 19%; 4-year OS 52%, 43%, 30% respectively). Keyword: Stem Cell Transplant No conflicts of interests pertinent to the abstract.

Is Treosulfan-Based Conditioning Attractive as a Reduced-Intensity Conditioning Regimen in Korea?

Allogeneic hematopoietic stem cell transplantation (HSCT) was not actively performed in elderly acute myeloid leukemia (AML) or myelodysplastic syndrome patients who are at a high-risk based on hematopoietic cell transplantation-specific comorbidity index (HCT-CI). The advent of reduced-intensity conditioning (RIC) regimens has made HSCT applicable in this population. However, the selection of appropriate conditioning is a major concern for the attending physician. The benefits of combination of treosulfan and fludarabine (Treo/Flu) have been confirmed through many clinical studies. Korean data on treosulfan-based conditioning regimen are scarce. A retrospective study was conducted to compare the clinical outcomes of allogeneic HSCT using RIC between 13 patients receiving Treo/Flu and 39 receiving busulfan/fludarabine (Bu/Flu). In terms of conditioning-related complications, the frequency of ≥ grade 2 nausea or vomiting was significantly lower and the duration of symptoms was shorter in the Treo/Flu group than in the Bu/Flu group. The incidence of ≥ grade 2 mucositis tended to be lower in the Treo/Flu group. In the analysis of transplant outcomes, all events of acute graft versus host disease (GVHD) and ≥ grade 2 acute GVHD occurred more frequently in the Treo/Flu group. The frequency of Epstein-Barr virus reactivation was significantly higher in the Treo/Flu group (53.8% vs. 23.1%, P = 0.037). Non-relapse mortality (NRM) at 12 months was higher in the Treo/Flu group (30.8% vs. 7.7%, P = 0.035). Significant prognostic factors included disease type, especially secondary AML, disease status and high-risk based on HCT-CI, ≥ grade 2 acute GVHD, and cases requiring ≥ 2 immunosuppressive drugs for treating acute GVHD. In the comparison of survival outcomes according to conditioning regimen, the Bu/Flu group seemed to show better results than the Treo/Flu group (60% vs. 46.2%, P = 0.092 for overall survival; 56.4% vs. 38.5%, P = 0.193 for relapse-free survival). In additional analysis for only HCT-CI high-risk groups, there was no difference in transplant outcomes except that the Treo/Flu group tended to have a higher NRM within one year after transplantation. Survival outcomes of both groups were similar. This study suggests that Treo/Flu conditioning may be an alternative to Bu/Flu regimen in elderly patients with high-risk who are not suitable for standard conditioning.

Prognostic Factors for Outcomes of Allogeneic HSCT for Children and Adolescents/Young Adults With CML in the TKI Era

The breakthrough effects of tyrosine kinase inhibitors (TKIs) have lessened indications for allogeneic hematopoietic stem cell transplantation (HSCT) in chronic myeloid leukemia (CML). However, HSCT is still attractive for children and adolescents/young adults (AYAs) requiring lifelong TKI therapy. Nevertheless, little has been reported on the outcomes of large clinical studies of HSCT targeting these age groups. This study aimed to identify prognostic factors for the outcomes of HSCT, including reduced-intensity conditioning (RIC)-HSCT, for children and AYAs with CML in the TKI era. We performed a registry analysis for 200 patients with CML aged <30 years who underwent pretransplant TKI therapy from the observational nationwide database established by the Japanese Society for Transplantation and Cellular Therapy. The patients received bone marrow (BM), peripheral blood (PB), or cord blood (CB) from either related or unrelated donors. The indication for HSCT for individual patients was determined by the institution according to European LeukemiaNet recommendations and other guidelines. The 5-year overall survival (OS) rates for patients with chronic phase (CP) (n = 124), accelerated phase (AP) (n = 23), and blastic phase (BP) (n = 53) at diagnosis were 82.8%, 71.1%, and 73.3%, respectively, with no significant difference (P =.3293). The strongest predictor of engraftment was transplant source, with CB (hazard ratio [HR], 0.33) and PB (HR, 2.00) (compared with BM) being independent unfavorable and favorable predictors, respectively. Transplant source was also an independent predictor of chronic GVHD, with PB (HR, 1.81) and CB (HR, 0.39) (compared with BM) being unfavorable and favorable predictors, respectively. The strongest predictor of OS rate for patients with CP at diagnosis was disease phase at HSCT, with second or greater CP, AP, or BP (HR, 2.81) (compared with first CP [CP1]) being an unfavorable predictor. In addition, patients with CP at diagnosis who had major and complete molecular responses at HSCT had excellent outcomes, with 5-year OS rates of 100% and 94.4%, respectively. The 5-year OS rate was compared between RIC (n = 31) and myeloablative conditioning (MAC) (n = 58) in patients with CP1, both of which were 89.3%, with no significant difference (P = .9440). On univariate analysis for the RIC cohort with CP at diagnosis, the age at HSCT (HR, 1.27) (increase per year) and the time from diagnosis to HSCT (HR, 1.83) (increase per year) were significant predictors for OS. Our study demonstrates that RIC may be an appropriate alternative to MAC for children and AYAs with CP1. As for the transplant source, we recommend first selecting BM because of a higher engraftment rate compared to CB and a lower incidence of chronic GVHD compared to PB. Although HSCT in the status of a major molecular response is desirable, it is not advisable to continue TKI pointlessly long because age at HSCT and timing of HSCT are prognostic factors that determine survival. The decision to perform RIC-HSCT instead of continuing TKI should be carefully made, considering the possibility of transplant-related complications.

Allogeneic hematopoietic stem cell transplantation for heavily pretreated patients with mycosis fungoides and Sezary syndrome.

Allogeneic hematopoietic stem cell transplantation (AHSCT) is a promising strategy for treatment of heavily pretreated mycosis fungoides/Sezary syndrome (MF/SS). Herein, we aimed to evaluate the outcomes of AHSCT for heavily pretreated patients with MF/SS retrospectively. This analysis included consecutive 19 patients with MF/SS who received 20 AHSCT between 2012-2021 in our transplant center. Eight patients have been previously reported. Fifteen patients had diagnosis of MF and referred to SS in five patients. In our cohort, all cases had advanced disease (stages IIB: n=1, IIIA: n=7; IIIB: n=4, IVA: n=4, and IVB: n=3). Nine patients (47.4%) had developed large cell transformation. Only two patients received AHSCT in complete response, one very good partial response and two partial response while the others had progressive disease (n=15) before transplant. Seven (35%) patients were alive at the time of analysis, with a median follow up of 10.5months (range, 0.3-113months) after AHSCT. Nine patients (47.4%) died without disease relapse or progression. Non-relapse mortality was 35.9% at 1year and 26.9% at 3years and thereafter. For all patients the probability of overall survival was 48.5% and 32.3% at 1- and 5-year post-transplant, respectively. AHSCT for MF/SS resulted in an estimated progression free survival of 45.4% at 1year. Given the poor prognosis of patients not receiving transplants and in the absence of curative non-transplantation therapies, our results support that AHSCT is able to effectively rescue 32.3% of the population of transplant eligible, heavily pretreated patients in 5years.

Outcome of Allogeneic HSCT after Chemo-Based Conditioning in Infants with Acute Myeloid Leukemia in First Complete Remission: A Multicenter EBMT-PDWP Study

Background: Pediatric patients younger than two years of age with acute myeloid leukemia (AML) commonly receive a chemotherapy-based myeloablative conditioning regimen before allogeneic hematopoietic stem cell transplantation (HSCT). The optimal choice of cytotoxic agents is still controversial.Methods: A retrospective EBMT-registry based study was conducted to investigate the impact of different chemotherapy-based conditionings on the outcomes in young children. Children younger than two years of age receiving a first HSCT of bone marrow (BM), peripheral blood stem cells (PBSC) or cord blood (CB) from matched siblings (MSD) or unrelated donors (UD) in first complete remission (CR1) between 2000 and 2019 were included. Busulfan/Cyclophosphamide (BuCy) and BuCy/Melphalan (BuCyMel) were the most frequent combinations on which this analysis focused. The primary endpoint was leukemia-free survival (LFS). Multivariate analysis adjusting for differences between the conditioning regimens and risk factors influencing outcome was performed using the Cox's proportional hazards regression model.Results: 289 patients (56% male) transplanted at a median age of 1.2 years (IQR 0.9-1.6) after BuCy (164, 57%) or BuCyMel (125, 43%) were included. 184 (64%) patients received BM, 71 (24%) CB and 34 (12%) PBSC from UD (201, 70%) and MSD (88, 30%). In-vivo T-cell-depletion (TCD) was performed in 160 (58%, missing data 14) of the HSCTs with anti-thymocyte-globulin (ATG, 153) or alemtuzumab (7). Ex-vivo TCD was performed in 13 (5%, missing data 3) of the HSCTs. Graft-versus-host-disease (GvHD)-prophylaxis was Cyclosporin-A-based in 90% of the HSCTs. Median follow-up (FU) was 4.9 years (95% CI 3.9-5.5).After a median FU of 4 years, 4-y-LFS after BuCyMel (74.3%, 95% CI 65.1-81.4) was significantly better compared to BuCy (59.7%, 95% CI 51.2-67.2), hazard ratio (HR) 0.56 (95% CI 0.35-0.90, P=0.02). Overall survival (4-y-OS) after BuCyMel (77.2%, 95% CI 68.1-84.0) was significantly better compared to BuCy (66.6%, 95% CI 58.0-73.8), HR=0.58 (95% CI 0.35-0.97, P=0.04).No significant differences were found in the probability of relapse (4-y-RI (whole cohort) 26.2% (95% CI 21.0-31.7), HR of BuCyMel 0.59 (95% CI 0.34-1.02), P=0.06), non-relapse mortality (4-y-NRM (whole cohort) 7.8% (95% CI 5.0-11.4), HR of BuCyMel 0.49 (95% CI 0.19-1.24), P=0.13) and incidence of acute grade II-IV GvHD at day 100 (day-100-aGvHD II-IV (whole cohort) 36.8% (95% CI 31.2-42.5), HR of BuCyMel 0.59 (95% CI 0.35-1.01), P=0.06). Incidence of chronic GvHD (4-y-cGvHD (whole cohort)) was 9.8% (95%-CI 6.3-14.2). The donor type had no significant influence on the outcome.Conclusion: Bu-based conditionings of HSCT for infants with AML at high risk of relapse offer a high probability of cure. Conditioning with three alkylators (BuCyMel) resulted in better LFS and OS compared with two alkylators (BuCy) without significantly increasing the risk of both NRM and aGvHD. Future trials will evaluate the impact of the more recently introduced alkylator Treosulfan within the conditioning of HSCT in pediatric AML. DisclosuresPeters: Amgen: Membership on an entity's Board of Directors or advisory committees, Other: Travel grants. Locatelli: Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Miltenyi: Speakers Bureau; Medac: Speakers Bureau; Jazz Pharamceutical: Speakers Bureau; Takeda: Speakers Bureau. Moraleda: Pfizer: Other: Educational Grants, Research Funding; Sanofi: Other: Educational Grants, Research Funding; MSD: Other: Educational Grants, Research Funding; ROCHE: Consultancy, Honoraria, Other: Educational Grants, Research Funding; Takeda: Consultancy, Honoraria, Other: Educational Grants, Research Funding; Sandoz: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Other: Educational Grants, Research Funding; Gilead: Consultancy, Honoraria, Other: Educational Grants, Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Other: Educational Grants, Research Funding; NovoNordisk: Other: Educational Grants, Research Funding; Janssen: Other: Educational Grants, Research Funding; Celgene: Other: Educational Grants, Research Funding; Amgen: Other: Educational Grants, Research Funding. Biffi: BlueBirdBio: Consultancy, Other: Advisory Board. Corbacioglu: Gentium/Jazz Pharmaceuticals: Consultancy, Honoraria.

Planned Granulocyte Colony-Stimulating Factor Adversely Impacts Survival after Allogeneic Hematopoietic Cell Transplantation Performed with Thymoglobulin for Myeloid Malignancy

The in vivo depletion of recipient and donor T lymphocytes using antithymocyte globulin (ATG; Thymoglobulin) is widely adopted in allogeneic hematopoietic stem cell transplantation (HCT) to reduce the incidence of both graft failure and graft-versus-host disease (GVHD). However, excess toxicity to donor lymphocytes may hamper immune reconstitution, compromising antitumor effects and increasing infection. Granulocyte-colony stimulating factor (G-CSF) administered early after HCT may increase ATG-mediated lymphotoxicity. This study aimed to investigate the effect of an interaction between ATG and post-transplantation granulocyte colony-stimulating factor (G-CSF) on allogeneic HCT outcomes, using the Center for International Blood and Marrow Transplant Research (CIBMTR) registry. We studied patients age ≥18 years with acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS) who received Thymoglobulin-containing preparative regimens for HLA-matched sibling/unrelated or mismatched unrelated donor HCT between 2010 and 2018. The effect of planned G-CSF that was started between pretransplantation day 3 and post-transplantation day 12 was studied in comparison with transplantations that did not include G-CSF. Cox regression models were built to identify risk factors associated with outcomes at 1 year after transplantation. A total of 874 patients met the study eligibility criteria, of whom 459 (53%) received planned G-CSF. HCT with planned G-CSF was associated with a significantly increased risk for nonrelapse mortality (NRM) (hazard ratio [HR] 2.03; P <.0001; 21% versus 12%) compared to HCT without G-CSF. The 6-month incidence of viral infection was higher with G-CSF (56% versus 47%; P=.007), with a particular increase in Epstein-Barr virus infections (19% versus 11%; P=.002). The observed higher NRM with planned G-CSF led to lower overall survival (HR, 1.52; P=.0005; 61% versus 72%). There was no difference in GVHD risk between the treatment groups. We performed 2 subgroup analyses showing that our findings held true in patients age ≥50 years and in centers where G-CSF was used in some, but not all, patients. In allogeneic peripheral blood HCT performed with Thymoglobulin for AML and MDS, G-CSF administered early post-transplantation resulted in a 2-fold increase in NRM and a 10% absolute decrement in survival. The use of planned G-CSF in the early post-transplantation period should be carefully considered on an individual patient basis, weighing any perceived benefits against these risks.

Allogeneic Hematopoietic Stem Cell Transplantation for Chronic Myelomonocytic Leukemia: Clinical and Molecular Genetic Prognostic Factors in a Nordic Population

Chronic myelomonocytic leukemia (CMML) is an aggressive disease in which survival after allogeneic hematopoietic stem cell transplantation (HCT) remains relatively poor. An assessment of prognostic factors is an important part of treatment decision making and has the potential to be greatly improved by the inclusion of molecular genetics. However, there is a significant knowledge gap in the interpretation of mutational patterns. This study aimed to describe outcomes of allogeneic HCT in patients with CMML in relation to clinical and molecular genetic risk factors. This retrospective study included 64 patients with CMML who underwent allogeneic HCT between 2008 and 2018, with a median follow-up of 5.4 years. Next-generation sequencing using targeted myeloid panels was carried out on saved material from 51 patients from the time of transplantation. Kaplan-Meier and Cox regression were used for analysis of overall survival (OS), and cumulative incidence with competing risks and Fine and Gray models were used for analysis of relapse and nonrelapse mortality (NRM). Mutations were detected in 48 patients (94%), indicating high levels of minimal residual disease (MRD) positivity at transplantation, even among those in complete remission (CR) (n=14), 86% of whom had detectable mutations. The most frequently mutated genes were ASXL1 (37%), TET2 (37%), RUNX1 (33%), SRSF2 (26%), and NRAS (20%). Risk stratification using the CMML-specific Prognostic Scoring System molecular score (CPSS-Mol) resulted in 45% of patients moving to a higher risk-group compared with risk stratification using the CPSS. High leucocyte count (≥13×109/L), transfusion requirement, and previous intensive chemotherapy were associated with higher incidence of relapse. Being in CR was not linked to better outcomes. Neither ASXL1 nor RUNX1 mutation was associated with a difference in OS, relapse, or NRM, despite being high risk in the nontransplantation setting. TET2 mutations were associated with a significantly higher 3-year OS (73% versus 40%; P=.039). Achieving MRD-negative CR was rare in this CMML cohort, which may explain why we did not observe better outcomes for those in CR. This merits further investigation. Our analyses suggest that the negative impact of ASXL1 and RUNX1 mutations can be overcome by allogeneic HCT; however, risk stratification is complex in CMML and requires larger cohorts and multivariate models, presenting an ongoing challenge in this rare disease.

Hematopoietic Stem Cell Transplantation for Patients with Paroxysmal Nocturnal Hemoglobinuria with or without Aplastic Anemia: A Multicenter Turkish Experience

Objective:Although inhibition of the complement system at different steps is a promising therapy modality in patients with paroxysmal nocturnal hemoglobinuria (PNH), allogeneic hematopoietic stem cell transplantation (HCT) is still the only curative therapy, especially for patients with intractable hemolysis or bone marrow failure. The aim of this study is to evaluate the outcomes of allogeneic HCT in PNH patients with aplastic anemia (PNH-AA) or without.Materials and Methods:Thirty-five PNH/PNH-AA patients who were treated with allogeneic HCT in 10 transplantation centers in Turkey were retrospectively analyzed.Results:Sixteen (45.7%) and 19 (54.3%) patients were diagnosed with classical PNH and PNH-AA, respectively. The median age of the patients was 32 (18-51) years. The 2-year overall survival (OS) rate and rate of graft-versus-host disease-free, failure-free survival (GFFS) was 81.2% and 78.1%, respectively. The 2-year OS in cases of classical PNH and PNH-AA was 81.3% and 79.9%, respectively (p=0.87), and 2-year GFFS in cases of PNH and PNH-AA was 79% and 76% (p=0.977), without statistical significance. The OS and GFFS rates also did not differ between transplantations with matched sibling donors (MSDs) and matched unrelated donors (MUDs).Conclusion:Allogeneic HCT with MSDs or MUDs is a good option for selected patients with classical PNH and PNH-AA. In particular, patients with debilitating and refractory hemolysis and patients with bone marrow failure might form an excellent group of candidates for allogeneic HCT.

Outcomes of allogeneic transplantation for hemoglobin Bart's hydrops fetalis syndrome in Hong Kong.

Hemoglobin Bart's hydrops fetalis syndrome (BHFS) was once considered a fatal condition universally. Medical advances over the past three decades have resulted in increasing numbers of BHFS survivors. This retrospective review summarized local territory-wide experience and outcomes of BHFS patients who received allogeneic hematopoietic stem cell transplantation (HSCT) in Hong Kong. All BHFS patients who underwent allogeneic HSCT in Hong Kong, either in one of the two former pediatric transplant centers (Queen Mary Hospital and Prince of Wales Hospital) on or before 2019 or in the single territory-wide pediatric transplant center (Hong Kong Children's Hospital) since 2019, from January 1, 1996, till December 31, 2020, were included. Basic demographic data, perinatal history, transplant details, long-term outcomes, and morbidities were reviewed. Total five allogeneic HSCT were performed in two males and three females at a median age of 22months, which include one 8/8 matched-sibling bone marrow transplant, one 5/6 matched-sibling cord blood transplant with HLA-DR antigenic mismatch, two 12/12 matched-unrelated peripheral blood stem cell transplant (PBSCT), and one haploidentical PBSCT with TCRαβ/CD45RA depletion from maternal donor. Neutrophil and platelet engrafted (>20×109 /L) at a median of 15 and 22days, respectively. All achieved near full donor chimerism at 1month. All patients survived and remained transfusion-independent without significant morbidities with median follow-up duration of 10years. To conclude, local data demonstrated favorable outcome of allogeneic HSCT for BHFS patients, but sample number is small. Non-directive approach in counseling and international collaboration is recommended.

Ikaros Expression in the Graft Is Associated with Chronic Graft Versus Host Disease

Introduction: Hematopoietic stem cell transplantation (HSCT) is the only potentially curative treatment for several diseases. Immune reconstitution post HSCT is a complex and extremely variable process. Ikaros transcription factor has an important role in hematopoiesis of several cell lines, especially in the lymphoid compartment. We hypothesized that Ikaros expression, both in the graft and in the recipient after transplant, might influence immune reconstitution and, consequently, the risk of opportunistic infections, relapse, and graft versus host disease (GVHD). Objectives: To correlate Ikaros expression both in the graft and in the recipient's peripheral blood (PB) after engraftment with the risk of GVHD after allogeneic HSCT outcomes. Patients and methods: 51 patients were included. Median age was 51 years (19-80), 53% of patients were male, and 57% of them had acute leukemia. Donor were haploidentical in 45% of cases, related identical in 29% and unrelated identical in 26%. Most patients (82%) received reduced-intensity conditioning regimens. Median follow-up was 20 months (10-40 months). Samples were collected from the graft and from the PB of the recipient 3 weeks after neutrophil recovery. Real time polymerase chain reaction (RT-PCR) was performed for analysis of absolute and relative Ikaros expression. Results: There was no association between Ikaros expression and the risk of acute GVHD, relapse or mortality. However, a significant association was observed in the risk of chronic GVHD. Cumulative incidence (CI) of chronic GVHD and of moderate / severe chronic GVHD (according to National Institute of Health - NIH classification) in two years were 49% and 28%, respectively. Higher Ikaros expression in the graft was associated with a significantly higher risk of moderate/severe chronic GVHD (54% vs. 15%, respectively, P=0.01). Higher Ikaros expression in the recipient's PB after engraftment was also associated with a significantly higher risk of moderate/severe chronic GVHD (65% vs. 11%, respectively, P=0.01). Conclusions: Ikaros expression in the graft and in the PB of the recipient after transplant seems to be correlated with a higher risk of moderate/severe chronic GVHD and might be evaluated in larger and prospective trials as a potential biomarker. Disclosures No relevant conflicts of interest to declare.

Torque Teno Virus as a Potential Biomarker for Complications and Survival After Allogeneic Hematopoietic Stem Cell Transplantation.

Impaired immune reconstitution after allogeneic hematopoietic stem cell transplantation (HSCT) contributes to increased risk of cancer relapse and infection resulting in significant morbidity and mortality. Unfortunately, effective strategies to functionally assess the quality of immune reconstitution are still missing. Quantification of in vivo replication of the ubiquitous, non-pathogenic virus Torque Teno Virus (TTV) has been reported in small series as a test to functionally evaluate the quality of post-transplant immune reconstitution. In the present study, we analyzed by quantitative PCR TTV titers in plasma samples from a large cohort of 168 allogeneic HSCT recipients. Our analysis confirms that TTV titers peaked at 100 days post-transplant, followed by progressive normalization thereafter. Negative correlation of TTV titers with T cell absolute numbers during the first year post-transplant points to the restoration of an active anti-TTV immunity. Univariable and multivariable linear regression analysis demonstrated that donor CMV positive serostatus, donor type and immune suppression resulting from GVHD treatment affected the restoration of anti-TTV immunity. Importantly, higher TTV titers at 100 days after transplantation were associated with worse overall survival and higher risk of acute GVHD and infections. Our results provide new insights into the factors affecting the dynamics of TTV replication and indicate that TTV is a potentially useful biomarker to assess immune reconstitution and to predict complications and outcomes of allogeneic HSCT.

Safety and outcome of allogeneic stem cell transplantation in mycosis fungoides and Sezary syndrome: A seven-year tertiary center analysis.

e20038 Background: Allogeneic hematopoietic stem cell transplantation (AHSCT) is a promising strategy for treatment of advanced-stage mycosis fungoides/Sezary syndrome (MF/SS). In this study, we retrospectively analyzed the outcomes of AHSCT for MF/SS and found that MF/SS appears to be susceptible to graft versus leukemia (GVL) effects. Methods: We studied outcomes in a consecutive series of 14 patients with MM/SS who underwent AHSCT between January 2012-November 2019 at our center. Treatment response was evaluated according to the Consensus WHO criteria for MF/SS. Results: The median age of patients 51.5 years (range: 28-68 years). Eight patients had MF and six patients had SS. Nine of those 14 patients had large cell transformation. All patients had advanced disease (stages IIB: n = 1, IIIA: n = 2, IIIB: n = 6, IVA1: n = 2 and IVB = 3). The median interval from disease onset to AHSCT was 3.7 years (range: 10.5 mos-11.3 years). All of the patients received at least three lines of treatments prior to AHSCT. Four patients achieved CR (3 are alive and still in CR) and all the other patients had progressive disease (PD) at the time of AHSCT. Graft source was peripheral blood stem cell in all patients. Six patients underwent transplantation from 9/10 HLA-matched unrelated donors and eight patients from HLA-identical sibling donors. Most of the patients (12/14) received RIC regimen (Flu-Cy-TBI) and ATG-Fresenius also added the protocol in AHSCT from unrelated donors. Five patients had stage 2-4 cutaneous acute GVHD and chronic GVHD developed in four patients (mild: n = 1, moderate: n = 2, severe: n = 1). Six patients who underwent transplantation at PD attained CR after AHSCT however relapse occurred in four patients at a median of four months (range: 3-10 months) after HSCT. At the time of data collection, nine patients have deceased; three were due to early TRM, three were underlying disease, two had aspergillus infection and one had nocardia infection. Two patients were alive with disease being treated by the Brentixumab vedotin, gemcitabine and DLI. With a median follow up period of 8.7 months after AHSCT, the estimated 1-year OS and PFS was 40.4%±5% and 35.4%±3.9%, respectively. Conclusions: AHSCT is an effective treatment option for advanced-stage MF/SS. Further studies are warranted to improve the outcome after AHSCT.

Outcomes of therapy-related acute lymphoblastic leukemia in adults after allogeneic stem cell transplantation.

Therapy-related acute lymphoblastic leukemia (t-ALL) is an increasingly recognized subset of therapy-related acute leukemia. There are limited data on the role of allogeneic hematopoietic stem cell transplantation (HSCT) in t-ALL. Recent reports suggest comparable outcomes of t-ALL with de novo ALL after HSCT. We retrospectively reviewed all patients of t-ALL who underwent HSCT at our center. Patients were analyzed for prior malignancy, therapy, time to diagnosis of t-ALL, clinical, laboratory characteristics, transplant details, relapse-free survival (RFS), and overall survival (OS). Eighteen patients (M:F ratio 1:1; Median age 44years) underwent HSCT for t-ALL. Median latent period from primary malignancy to t-ALL was 44.8months. 11q23 rearrangement and t(9;22) were present in 33.3% and 22.2% patients, respectively. Stem cell donors were matched related, matched unrelated, and haploidentical in 27.8% (n=5), 55.6% (n=10), and 16.7% (n=3) patients, respectively. Five patients died before D+ 100 (27.8%). Estimated 2-year RFS and OS were 47.1% and 51.8%, respectively. We did not find any pretransplant and post-transplant risk factors that were predictive of improved OS or RFS after multivariate analysis. Allogeneic HSCT outcomes in t-ALL were comparable to HSCT outcomes in de novo ALL. Multicenter studies with more patients and longer follow-up may provide factors affecting outcome and survival.

Outcome of allogeneic hematopoietic stem cell transplantation for mycosis fungoides and Sézary syndrome.

Although allogeneic hematopoietic stem cell transplantation (HSCT) has been reported to provide prolonged remission of relapsed/refractory mycosis fungoides (MF) and Sézary syndrome (SS), its role has not been fully evaluated. Here, the outcomes of allogeneic HSCT for patients with MF/SS were retrospectively evaluated by using the registry database of the Japan Society for Hematopoietic Cell Transplantation. Forty-eight patients were evaluable and enrolled in the analysis. Median age was 45.5 years. Eighteen patients (38%) received myeloablative conditioning, and 33 (69%) received HSCT from an alternative donor. Disease status was complete or partial response in 25% of the patients and relapsed or refractory in the others. At the time of analysis, 18 patients were alive, with a median follow-up of 31.0 months (range, 3.8-31.1). Three-year overall survival (OS) and progression-free survival (PFS) were 30% (95%CI, 16-45%) and 19% (95%CI, 9-31%), respectively. Disease progression was not observed later than 17 months after transplantation. Both disease status and performance status at transplant significantly affected OS and PFS. Although our findings suggest that allogeneic HSCT provides long-term PFS in patients with MF/SS, the timing of transplantation should be decided carefully based on the disease status and the patient's condition in order to improve the outcome.

Improved outcomes of allogeneic hematopoietic stem cell transplantation including haploidentical transplantation for childhood myelodysplastic syndrome.

This retrospective study aimed to investigate the outcomes of allogeneic hematopoietic stem cell transplantation (HSCT) for childhood myelodysplastic syndrome (MDS). Thirty-six patients (low-grade MDS, 24; advanced MDS, 12) received HSCT at the Asan Medical Center over two decades (early period, 1997-2007; recent period, 2008-2017). The transplantation outcomes were analyzed according to disease status, conditioning regimen, various donor types, and period of HSCT. During a median follow-up of 5.6 (range, 1.4-21.1) years, the probability of overall survival (OS) and failure-free survival was 77% and 69%, respectively. The cumulative incidence of transplantation-related mortality (TRM) was 12%. Significantly reduced TRM and improved OS were observed in patients who received HSCT during the recent period vs. the early period (TRM, 4% vs. 30%, P = 0.021; OS, 87% vs. 50%, P = 0.006). Comparable outcomes were observed for HSCT from haploidentical family donors vs. HLA-identical donors (TRM, 10% vs. 14%, P= 0.837; OS, 86% vs. 79%, P = 0.625). This study identified the improved outcomes of allogeneic HSCT for childhood MDS over time, in addition, the feasible outcomes of haploidentical HSCT suggested its use as an attractive alternative in the future procedures.

Allogeneic hematopoietic stem-cell transplantation for myelofibrosis.

Myelofibrosis is one of the Philadelphia chromosome (Ph)-negative myeloproliferative neoplasms with heterogeneous clinical course. Though many treatment options, including Janus kinase (JAK) inhibitors, have provided clinical benefits and improved survival, allogeneic hematopoietic stem-cell transplantation (AHSCT) remains the only potentially curative therapy. Considering the significant transplant-related morbidity and mortality, it is crucial to decide who to proceed to AHSCT, and when. In this review, we discuss recent updates in patient selection, prior splenectomy, conditioning regimen, donor type, molecular mutation, and other factors affecting AHSCT outcomes. Relapse is a major cause of treatment failure; we also describe recent data on minimal residual disease monitoring and management of relapse. In addition, emerging studies have reported pretransplant therapy with ruxolitinib for myelofibrosis showing favorable results, and further research is needed to explore its use in the post-transplant setting.

Relative Impact of HLA Matching and Non-HLA Donor Characteristics on Outcomes of Allogeneic Stem Cell Transplantation for Acute Myeloid Leukemia and Myelodysplastic Syndrome

Increasing donor–recipient HLA disparity is associated with negative outcomes of allogeneic hematopoietic stem cell transplantation (HSCT), but its comparative relevance amid non-HLA donor characteristics is not well established. We addressed this question in 3215 HSCTs performed between 2005 and 2013 in Germany for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). Donors were HLA-matched related (MRD; n = 872) or unrelated (10/10 MUD, n = 1553) or HLA-mismatched unrelated (<10/10 MMUD, n = 790). Overall survival (OS) was similar after MRD compared with 10/10 MUD HSCT, reflecting opposing hazards of relapse (hazard ratio [HR], 1.32; P < .002) and nonrelapse mortality (HR, .63; P < .001). After UD HSCT, increasing HLA disparity was associated with inferior OS (HR, 1.21 [P < .02] and HR, 1.57 [P < .001] for 9/10 and ≤8/10 MMUD, respectively, compared with 10/10 MUD). Among non-HLA donor characteristics, age, sex mismatching (male recipient–female donor), and cytomegalovirus (CMV) mismatching (positive recipient–negative donor) impacted OS. Multivariate subgroup analysis showed that OS was similar after HSCT from the youngest 9/10 MMUD (<30 years) compared with the oldest 10/10 MUD (>40 years) (HR, 1.18; P = .25) and also in male patients transplanted from female 10/10 MUD compared with male 9/10 MMUD (HR, .89; P = .46). In contrast, OS of CMV-positive patients tended to be better with CMV-negative 10/10 MUDs compared with CMV-positive 9/10 MMUDs (HR, 1.31; P = .04). Because of low patient numbers in subgroups, definite conclusions and establishment of a hierarchy among HLA matching and non-HLA donor characteristics could not be made. Our data suggest that the impact of donor age and sex mismatch but not CMV mismatch on outcome of allogeneic HSCT may be comparable with that of single HLA disparity.

Promising Outcome of Umbilical Cord Blood Transplantation in Patients with Multiple Comorbidities

The hematopoietic cell transplantation–specific comorbidity index (HCT-CI) has been recently proposed to predict the probability of nonrelapse mortality (NRM) and overall survival (OS) in allogeneic hematopoietic stem cell transplantation (HSCT). However, the usefulness of the HCT-CI in single-unit umbilical cord blood transplantation (UCBT) remains unclear. We investigated the impact of the HCT-CI on the clinical outcomes of allogeneic HSCT in a single-center retrospective study including 53 recipients of UCBT (UCBT group) and 90 recipients of other HSCT (non-UCBT group). In the non-UCBT group 2-year OS rates for HCT-CI score < 3 and ≥3 were 67% (n = 74; 95% confidence interval [CI], 54% to 78%) and 26% (n = 16; 95% CI, 7% to 51%), respectively (P = .001). In the UCBT group these rates were 66% (n = 39; 95% CI, 48% to 79%) and 69% (n = 14; 95% CI, 36% to 87%), respectively (P = .73). In the non-UCBT group 1-year NRM rates for HCT-CI score < 3 and ≥3 were 14% (95% CI, 6.4% to 22%) and 37% (95% CI, 14% to 61%), respectively (P = .02). In the UCBT group these rates were 6.1% (95% CI, 3.4% to 24%) and 7.7% (95% CI, .4% to 29%), respectively (P = .78). Using multivariate analysis we showed that HCT-CI score ≥ 3 was significantly associated with lower OS (hazard ratio, 3.06; 95% CI, 1.47 to 6.38; P = .003) and higher NRM (hazard ratio, 2.87; 95% CI, 1.18 to 6.96; P = .02) for the non-UCBT group. UCBT showed good OS with low incidence of NRM, even in patients with high HCT-CI scores. Altogether, we propose single-unit UCB to be a promising stem cell source for improving survival in patients with multiple comorbidities.