Haploidentical Allogeneic Stem Cell Transplantation Research Articles

The degree of HLA matching determines the incidence of cytokine release syndrome and associated nonrelapse mortality in matched related and unrelated allogeneic stem cell transplantation with post-transplant cyclophosphamide

Cytokine release syndrome (CRS) occurs frequently after haplo-identical allogeneic stem cell transplantation (alloSCT) with post-transplant cyclophosphamide (PTCy), increasing nonrelapse mortality (NRM) and decreasing survival. Data on CRS in HLA-matched alloSCT are limited and effects of specific HLA-mismatches on CRS development unknown. We hypothesized that in HLA-matched alloSCT increasing degrees of HLA-mismatching influence CRS incidence, NRM and survival. Retrospective analysis of 126 HLA-matched PTCy-alloSCT patients showed that higher degrees of HLA-mismatching significantly increased CRS incidence (26%, 75% and 90% CRS with 12/12, 10/10 and 9/10 matched donors, respectively). Maximum temperature during CRS increased with higher HLA-mismatch. Specific associations between HLA-mismatches and CRS could be determined. Grade 2 CRS and CRS-induced grade 3 fever were associated with significantly increased NRM (p < 0.001 and p = 0.003, respectively) and inferior survival (p < 0.001 and p = 0.005, respectively). NRM was mainly caused by disease conditions that may be considered CRS-induced inflammatory responses (encephalopathy, cryptogenic organizing pneumonia and multi-organ failure).

Salvage haploidentical transplantation for graft failure after first haploidentical allogeneic stem cell transplantation: an updated experience.

Graft failure is a fatal complication following allogeneic stem cell transplantation where a second transplantation is usually required for salvage. However, there are no recommended regimens for second transplantations for graft failure, especially in the haploidentical transplant setting. We recently reported encouraging outcomes using a novel method (haploidentical transplantation from a different donor after conditioning with fludarabine and cyclophosphamide). Herein, we report updated outcomes in 30 patients using this method. The median time of the second transplantation was 96.5 (33-215) days after the first transplantation. Except for one patient who died at +19d and before engraftment, neutrophil engraftments were achieved in all patients at 11 (8-24) days, while platelet engraftments were achieved in 22 (75.8%) patients at 17.5 (9-140) days. The 1-year OS and DFS were 60% and 53.3%, and CIR and TRM was 6.7% and 33.3%, respectively. Compared with the historical group, neutrophil engraftment (100% versus 58.5%, p < 0.001) and platelet engraftment (75.8% versus 32.3%, p < 0.001) were better in the novel regimen group, and OS was also improved (60.0% versus 26.4%, p = 0.011). In conclusion, salvage haploidentical transplantation from a different donor using the novel regimen represents a promising option to rescue patients with graft failure after the first haploidentical transplantation.

Outcome and Prognostic Factors of Haploidentical Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Relapsed or Refractory ETV6/RUNX1-Positive Acute Lymphoblastic Leukemia

Introduction: The role of haploidentical allogeneic hematopoietic stem cell transplantation (haplo-HSCT) in pediatric patients with relapsed or refractory (R/R) ETV6/RUNX1-positive acute lymphoblastic leukemia (ALL) is unclear. This study aimed to identify prognostic factors and explore the role of haplo-HSCT in the treatment of ETV6/RUNX1-positive ALL. Methods: We analyzed the clinical characteristics and treatment outcomes of 20 pediatric patients who were diagnosed with ETV6/RUNX1-positive ALL and received chemotherapy/chimeric antigen receptor T-cell bridged to haplo-HSCT between 2016 and 2021 at our institution. Results: With a median follow-up time of 47 months, the 3-year cumulative incidence of relapse, disease-free survival, and overall survival were 35.9% (95% confidence interval (CI): 15.3–57.1%), 59.1% (95% CI: 37.2–81.0%), and 75.0% (95% CI: 56.0–94.0%), respectively. Multivariate analysis revealed that pre-HSCT measurable residual disease (MRD) positivity (hazard ratio, 13.275; 95% CI: 2.406–73.243; p = 0.003) had a significant negative impact on relapse. A total of 7 patients experienced positive ETV6/RUNX1 gene expression at a median of 7.2 months after haplo-HSCT, and 5 of them experienced relapse at a median time of 12.1 months after haplo-HSCT. ROC curve analysis was performed to analyze the significance of pre-HSCT and post-HSCT ETV6/RUNX1 transcripts for predicting relapse; the AUC were 0.798 (95% CI: 0.567–1.0, p = 0.035) and 0.875 (95% CI: 0.690–1.0, p = 0.008), respectively. The optimal cut-off points to predict an inevitable relapse were 0.011% and 0.0019%, respectively. Conclusion: Patients with R/R ETV6/RUNX1-positive ALL may benefit from haplo-HSCT. Deeply eliminating pre-HSCT MRD and preemptive treatment for post-HSCT MRD may be crucial to further improving the prognosis.

Early Hematopoietic Reconstitution Status after Haploidentical Transplantation in AML Patients Is Indicative of Early Complications

Objective To investigate the early hematopoietic reconstruction process of haploidentical allogeneic hematopoietic stem cell transplantation (haplo-allo-HSCT) in patients with acute myeloid leukemia, and to explore its correlation with the occurrence of early complications after transplantation. Methods A retrospective analysis was performed on the clinical information of 187 AML patients who underwent haploidentical allo-HSCT at the Hematology Hospital of the Chinese Academy of Medical Sciences from January 2017 to December 2022, and all of these patients achieved complete remission before transplantation. The results of pre-transplantation-7d-after-tranplantation+14d blood routine were analyzed. The occurrence of aGVHD within 100 days after transplantation was the primary outcome event, and CMV infection within 60 days was the secondary outcome event. The diagnosis and grading of aGVHD is described in Glucksberg and MAGIC. R-4.2.0 statistical software was used for statistical analysis. Results A total of 187 AML patients who underwent haploid transplantation after achieving complete remission were included, with a median age of 35 (27-55) years, including 105 male patients (56.31%) and 82 female patients (43.69%). All patients were grouped into aGVHD patients according to different risk levels: (1) There were differences between the I~IV°aGVHD group and the patients without aGHVD (100 versus 87 patients) in the early post-transplantation plt and WBC absolute levels, and the I~IV°aGVHD group showed a lower plt trend in 1d and 2d, and a higher WBC level (0.08×10 9/L vs 0.07×10 9/L, p=0.036) at 10 days. (2) Compared with patients without aGHVD (70 versus 87 cases), the former showed lower plt levels (62.5×10 9/L vs 80×10 9/L, p=0.029) in 1d and higher WBC levels (0.03×10 9/L vs 0.02×10 9/L, p=0.047; 0.11×10 9/L vs 0.07×10 9/L, p=0.033) in 9d~10d), the Hb level was lower at 1d~3d (91g/L vs 99g/L, p=0.047; 91g/L vs 97.5g×109/L, p=0.039; 89.5g/L vs 95.5g/L, p=0.013). (3) Compared with patients without aGHVD (33 versus 87 patients), the III~IV°aGVHD group showed lower plt levels (60×10 9/L vs 74×10 9/L, p=0.006; 48×10 9/L vs 52×10 9/L, p=0.018; 26×10 9/L vs 36.5×10 9/L, p=0.003) in 1~3d, and high WBC level (0.04×10 9/L vs 0.02×10 9/L, p=0.025; 0.14×10 9/L vs 0.07×10 9/L, p=0.008) showed in 10 days, and lower Hb level in 1d~3d (89g/L vs 99g/L, p=0.047; 89g/L vs 97.5g/L, p=0.039; 83g/L vs 95.5g/L, p=0.013). Based on the maintenance of platelets at 20×109/L for 3 days after transplantation, the cumulative incidence of 100 days III~IV°aGVHD in the ≤3d group was higher (63% vs 30%, p=0.015). Univariate analysis showed that the absolute value of 1~3d plt after transplantation was low, and the PLT maintained at 20×10 9/L after HSCT was short, which was a risk factor for the occurrence of aGVHD. Group analysis of CMV occurring within 60 days showed that in the early post-transplantation period, patients in the non-CMV group had higher absolute platelet values (63.50×10 9/L vs 47.00×10 9/L, p=0.03) than patients in the CMV group at 0 days. Age, pretreatment regimen, transplant type, aGVHD prevention regimen, time to first PLT infusion after transplantation, absolute value of 0 d platelets, and platelet transfusion efficiency were included in univariate and multivariate analysis, and multivariate analysis showed that pretreatment regimen (p=0.017, 1.002 [0.606-0.953]) and transplant type (p&amp;lt;0.001, 0.264 [0.147-0.476]) were independent risk factors affecting the occurrence of CMV. No correlation between platelet transfusion efficiency and PLT infusion frequency and CMV was found. Conclusion Early hematopoietic reconstruction after transplantation in AML-CR patients who received haploid transplantation has certain indicative significance for the occurrence of early complications, and its indicative significance becomes more significant with the increase of aGHVD degree.

TBI/Ratg-Based Conditioning for Haploidentical Allogeneic Hematopoietic Stem Cell Transplantation in 11 Cases of Chemotherapy-Resistant Advanced-Stage Peripheral T-Cell Lymphoma

Objectives: To evaluate the clinical outcomes and safety of haploidentical allogeneic hematopoietic stem cell transplantation(haplo-HSCT)with total body irradiation (TBI)/rabbit Anti-thymocyte globulin (rATG) based conditioning regimen in chemotherapy-resistant advanced-stage peripheral T-cell lymphoma (PTCL). Methods: From September 2019 to December 2022, eleven chemotherapy-resistant advanced-stage PTCL patients who underwent haplo-HSCT were enrolled in our study. All of them received TBI/rATG-based conditioning regimen in our centers. Results: ①Among 11 patients, there were 6 males and 5 females with a median age of 40(range：22~58) years old. Six cases of them are peripheral T-cell lymphoma not otherwise specified (PTCL NOS), 3 cases are angioimmunoblastic T-cell lymphoma (AITL), 1 case is large-cell transformation of mycosis fungoides (MF-LCT), and 1 case is T-cell large granular lymphocytic leukemia(T-LGLL). The Lugano stage was III or IV in all cases, and 8 patients had B symptoms. The median number of previous chemotherapy exposure before transplantation was 4 (range: 2~10) lines and the disease status before transplantation was progressive diseases (PD) in all cases. The median time from diagnosis to transplantation was 17(range：6~36) months.②The conditioning regimen consisted of TBI 2Gy d-8, 4Gy from day-7 to -6, rATG 2.5 mg/kg/d day-5 to -2, etoposide 15mg/kg/d day-5 to -4, cyclophosphamide (CTX) 50mg/kg/d, day-3 to -2. The patients with central nervous system involvement received a regimen of thiotepa 5 mg/kg/d， from day -5 to -4 instead of CTX and etoposide, and add 2.0 g/m2 of cytarabine twice a day, from day -3 to day -2 into the conditioning.③All patients were successfully engrafted. Only one patient developed Grade III-IV acute graft-vs-host disease (aGvHD). Among the 8 survivors, 4 cases developed chronic graft-vs-host disease (cGvHD).④After transplantation, CR was obtained in 9 patients. ⑤Regimen related toxicities: all were non-fatal. Hematopoietic suppression occurred in all patients after conditioning. Three patients had diarrhea and four had mucositis and three had elevated transaminase/bilirubin levels. Seven patients had infections.⑥The 1-year cumulative non-relapse mortality (NRM) and 1-year cumulative incidence of relapse (CIR) was 22.5±14.0% and 20.2±12.7%, respectively. The 1-year overall survival (OS) and 1-year disease-free survival (DFS) was 72.7±13.4% and 63.6±14.5%, respectively Conclusions: TBIand rATG based conditioning regimen is effective and safe for haplo-HSCT in chemotherapy-resistant advanced-stage PTCL.

ETV6-ABL1 Fusion Gene Was Associated with a Poor Prognosis in Patients with Acute Myeloid Leukemia

Background:Acute myeloid leukemia (AML) is commonly characterized by chromosomal abnormalities that result in the formation of chimeric genes involved in leukemogenesis. ETV6-ABL1-a fusion gene results from a complex rearrangement involving translocation, inversion, or insertion of ETV6 into chromosomal band 9q34 or ABL1 into 12p13. This rare but recurrent genetic aberration is found in AML patients and is associated with a poor prognosis. Methods:A retrospective review was conducted of three relapsed AML patients with ETV6-ABL1 fusion genes screened by multiplex RT-PCR who were treated at Beijing Lu Daopei Hospital and Hebei Yanda Lu Daopei Hospital between November 2019 and January 2022. Results:At diagnosis, the median age was 32 years (range 32-42 years), and two patients were male(Pt.2,3). AML subtypes included M2 (Pt.2) and M4 (Pt.1,3), and no patient had a prior history of myeloproliferative neoplasms. Clinical and laboratory characteristics at diagnosis included: hepatosplenomegaly (Pt.3), lymphadenopathy (Pt.1), leukocytosis (median 209.71×10 9 /L, range, 60.28-687.2×10 9/L),but no significant eosinophilia(≥1.5×10 9/L). Cytogenetic analyses showed a normal karyotype in all three patients. FLT3-ITD gene mutation was found in two patients(Pt.1,2). All there patients received the same IA regimen(idarubicincytarabine) as induction chemotherapy and achieved complete remission, followed by multi-agent chemotherapy as consolidation treatment.Pt.1 received additional targeted therapy with sorafenib. However, after a median duration of remission (DOR) of 4 months (range 3-8 months), all patients experienced relapse and sought for further therapy at our hospital. Upon re-evaluation by laboratory tests, ETV6-ABL1 fusion gene was detected by multiplex RT-PCR, and additional NUP98-NSD1 fusion was also found in Pt.2. FLT3-ITD gene mutation was confirmed in Pt. 1 and Pt. 2, but the characteristic t(9;12) (q34;p13) chromosomal abnormalities were not present in any of the patients. Pt. 2 presented with an abnormal karyotype of 46, XY, t(3;17)(q12;p11.2),add (10)(q22)[5] / 46,XY[15], while the rest 2 patients had a normal karyotype. Pt.1 died rapidly from serious infection after relapse. Pt. 2 and Pt. 3 received dasatinib-containing combination regimens as salvage therapy and achieved partial remission. Pt. 2 underwent haploidentical allogeneic hematopoietic stem cell transplantation (allo-HSCT) with an enhanced myeloablative conditioning regimen in March 2021, and has maintained molecular remission until now. Pt. 3 is currently undergoing HSCT preparation. Conclusion: ETV6-ABL1 fusion gene is a rare but recurrent genetic aberration in AML, and its rearrangement is not uniform across eachpatient, typically involving cryptic insertions. Routine chromosome G-banding analysis may not identify this fusion gene, and the combined use of fluorescence in situ hybridization and PCR is recommended for better detection for ETV6-ABL1. Patients with this fusion gene have a high relapse rate and a poor prognosis. Tyrosine kinase inhibitors (eg. Dasatinib)are a reasonable treatment option, and allo-HSCT may be considered for potential cure.

Peripheral Blood Haploidentical Allogeneic Stem Cell Transplantation in Older Adults with Acute Myeloid Leukemia and Myelodysplastic Syndromes Demonstrates Long Term Survival, Results from Australia and New Zealand Transplant and Cellular Therapies

There is a limited body of evidence for haploidentical hematopoietic stem cell transplantation (haplo-HSCT) in older patients. Previous studies have used a high proportion of bone marrow–derived grafts and a variety of conditioning regimens. In Australia and New Zealand, haplo-HCST is predominantly performed using peripheral blood (PB) with universal use of post-transplantation cyclophosphamide (PTCy). To characterize the outcomes of older recipients undergoing haplo-HSCT for acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). Data were collected through the Australasian Bone Marrow Transplant Recipient Registry (ABMTRR) for patients aged 65 or older receiving a PB haplo-HSCT for AML/MDS between January 2010 and July 2020. A total of 44 patients were included in the analysis. The median follow-up time was 377 days. The median age was 68 (range 65-74) with a median Karnofsky performance status of 90. Thirty patients (68.2%) had AML, whereas 14 (31.8%) had MDS. The median donor age was 40. The most common conditioning regimen was nonmyeloablative fludarabine, cyclophosphamide, and total body irradiation (75%); the remainder of the patients received either melphalan- or busulfan-based regimens, and the majority were reduced intensity, with only 2 patients undergoing myeloablative conditioning. All patients received post-transplantation cyclophosphamide and mycophenolate mofetil, with the majority also receiving tacrolimus (90.5%) and the remainder receiving cyclosporine (9.5%). No patients received anti-thymocyte globulin. Neutrophil engraftment was achieved in 97.6% of patients at a median of 18 days, whereas platelet engraftment was achieved in 92.7% of patients at a median of 28 days. The cumulative incidences of cytomegalovirus (CMV) reactivation and CMV disease were 52.5% and 5.1% at 1 year. The incidence of grade 2-4 acute Graft Versus Host Disease (GVHD) was 18.2%. The incidence of chronic GVHD at 2 years was 40.7%, with extensive chronic GVHD occurring in 17.7% of patients. The incidences of relapse and non-relapse mortality (NRM) at 2 years were 8.8% and 20.7% respectively. The leading causes of death were infection (64.7%) followed by relapse (14.2%). The 2-year overall survival was 74%. Relapse free survival and GVHD free, relapse free survival at 2 years was 70% and 48%. Haplo-HSCT using a peripheral blood graft and PTCy GVHD prophylaxis demonstrates long-term disease control with acceptable rates of NRM for older patients with AML/MDS.

Efficacy and safety of TBI+rATG-based conditioning regimen for haploidentical allogeneic hematopoietic stem cell transplantation in 11 cases of chemotherapy-resistant advanced peripheral T-cell lymphoma

Objective: To evaluate the clinical outcomes and safety of haploidentical hematopoietic stem cell transplantation (haplo-HSCT) using a conditioning regimen based on total body irradiation (TBI) and rabbit anti-human thymocyte globulin (rATG) in the management of chemotherapy-resistant advanced peripheral T-cell lymphoma (PTCL) . Methods: Clinical data of 11 patients with chemotherapy-resistant advanced PTCL who underwent haplo-HSCT with a TBI+rATG-based conditioning regimen at the Department of Hematology, Shanghai Liquan Hospital and Shanghai Zhaxin Integrated Traditional Chinese and Western Medicine Hospital, from September 2019 to December 2022 were retrospectively analyzed. Results: ①Among the 11 patients (six males and five females), with a median age of 40 years (range: 22-58 years), there were six cases of PTCL, not otherwise specified (PTCL-NOS), three cases of angioimmunoblastic T-cell lymphoma (AITL), one case of large-cell transformation of mycosis fungoides (MF-LCT), and one case of T-cell large granular lymphocytic leukemia (T-LGLL). According to the Lugano staging system, all patients were in stage Ⅲ or Ⅳ, and eight patients had B symptoms. Before transplantation, the median number of prior lines of chemotherapy was 4 (range: 2-10), and all patients had progressive disease (PD). The median time from diagnosis to transplantation was 17 months (range: 6-36 months). ②The conditioning regimen consisted of a TBI dose of 10 Gy, administered at 2 Gy on day -8 and 4 Gy from day -7 to day -6, rATG was administered at a daily dose of 2.5 mg/kg from day -5 to day -2. Etoposide (VP-16) was given at a dose of 15 mg/kg/d from day -5 to day -4, while cyclophosphamide (CTX) was administered at a dose of 50 mg/kg/d from day -3 to day -2. In patients with central nervous system involvement, etoposide and cyclophosphamide were replaced with thiotepa (TT) at a dose of 5 mg/kg/d from day -5 to day -4. Additionally, cytarabine (Ara-C) was added at a dose of 2.0 g/m(2) twice a day from day -3 to day -2 into the conditioning. ③Successful engraftment was achieved in all patients, with a median time to neutrophil engraftment of 14.5 d (range: 11-16 d) and a median time to platelet engraftment of 13 days (range: 8-18 days). Acute graft-versus-host disease (aGVHD) occurred in one patient (grade Ⅰ-Ⅱ), and another patient experienced grade Ⅲ-Ⅳ aGVHD. Among the eight survivors, four developed chronic GVHD (cGVHD). ④Post-transplantation, nine patients achieved complete response (CR). ⑤Hematopoietic suppression occurred in all patients after conditioning, with three experiencing diarrhea, four developing mucositis, three exhibiting elevated transaminase/bilirubin levels, and seven developing infectious complications. These non-hematologic adverse events were effectively managed. ⑥At one year post-transplantation, the non-relapse mortality (NRM) was (22.5±14.0) %, the cumulative incidence of relapse (CIR) was (20.2±12.7) %, and overall survival (OS) rate was (72.7±13.4) %, and disease-free survival (DFS) rate was (63.6±14.5) % . Conclusion: TBI+rATG-based conditioning regimen for haplo-HSCT is an effective and safe treatment approach for patients with chemotherapy-resistant advanced PTCL.

Integrated genomic and single-cell transcriptomic analyses reveal clonal evolution and immune signature in donor cell leukemia after haploidentical allogeneic hematopoietic stem cell transplantation

The pathogenesis of donor cell leukemia (DCL) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is unclear and likely multifactorial. Leukemic transformation of healthy donor HSCs in recipient’s bone marrow microenvironment provides a useful in vivo model for investigating the mechanisms involved in leukemogenesis. Here, we report a rare case of late-onset DCL developing in a recipient. Whole-genome sequencing indicates that donor-derived cells harboring clonal hematopoiesis of indeterminate potential (CHIP)-associated genetic alterations expand and eventually transform to full-blown AML via acquisition of additional somatic mutations within the recipient’s bone marrow microenvironment. The 10× single-cell RNA sequencing reveals the abundance of GMP-like cells with a specific transcriptional signature in DCL. Moreover, impaired immune surveillance, including dysfunction of cytotoxic T lymphocytes (CTLs) and decreased number of canonical NK cells, is discovered in DCL. Our data add valuable information to the current understanding of the mechanisms of DCL.

Intensified conditioning regimen with fludarabine combined with post-transplantation cyclophosphamide for haploidentical allogeneic hematopoietic stem cell transplantation in children with high-risk acute leukemia

ABSTRACTObjective:Post-transplantation cyclophosphamide (PTCy) can reduce the incidence of graft versus host disease (GVHD) and this intervention is often applied on adults with hematologic malignancy. However, the high relapse rate hinders the development of the intervention and data of PTCy used on children with hematologic malignancy remains limited. In order to overcome issue of high relapse rate in PTCy treatment, we used fludarabine (Flu), enhanced dose of cytarabine (Ara-C, 9 g/m2), busulfan (Bu), Cy, anti-thymocyte globulin (ATG) combined with PTCy for an intensified conditioning regimen.Methods:A total of 22 children with acute leukemia received intensified PTCy conditioning regimen (PTCy intensified group). We matched with 18 children who received modified Bu-Cy and ATG conditioning regimen in the same period (ATG group).Results:The two-year cumulative incidences of grade II–IV acute GVHD was significantly lower in PTCy intensified group (13.6 ± 7.7% vs 38.9 ± 11.5%, P = 0.048). Two-year GVHD-free relapse free survival (GRFS) in PTCy seems to be better among the increment group despite not being significant (63.3 ± 10.3% vs 35.4 ± 11.9%, P = 0.092). The positive rate of minimal residual disease after transplantation was significantly lower than that before transplantation (20.0% vs 2.5%, P = 0.029).Conclusion:In conclusion, ATG and PTCy combined with Flu-based increased intensity conditioning regimen is effective for acute leukemia in children. It could reduce GVHD rate significantly and potentially improve GRFS.

Refractory esophageal stricture of esophageal mucous membrane pemphigoid after allogeneic hematopoietic stem cell transplantation

Haploidentical allogeneic hematopoietic stem cell transplantation from her brother was performed on a 41-year-old lady with no prior history of pemphigoid to treat recurrent AML. On day 59 following transplantation, she experienced esophageal stenosis. During immunosuppressive therapy for graft vs. host disease, this condition was controlled with periodic esophageal dilatation (GVHD). Her esophageal stricture, which required periodic dilatation, grew worse after she stopped immunosuppressive therapy because of recurrent AML. The esophageal mucosa was easily hemorrhagic and desquamative. Histologic analysis revealed that the squamous cell layers had been divided. Indirect immunofluorescence was negative for IgG and positive for IgA on the epidermal layers, while direct immunofluorescence showed a linear deposition of IgG on the basement membrane zone. It was determined through immunoblotting utilizing recombinant protein of BP180 C-terminal domain that both IgG and IgA antibodies were present, supporting the diagnosis of mucous membrane pemphigoid with anti-BP180. After allogeneic transplantation, basal epidermal cell destruction by GVHD may result in autoimmune blistering disorders, which expose basement membrane proteins and antigen presentation. A similar mechanism could apply to our situation. For rare GVHD cases, a thorough histological diagnosis is required.

Thrombopoietin Levels Predict the Response to Avatrombopag Treatment in Patients with Persistent Thrombocytopenia after Haploidentical Hematopoietic Stem Cell Transplantation

Introduction: Persistent thrombocytopenia (PT) is a common and severe complication after haploidentical allogeneic hematopoietic stem cell transplantation (haplo-HSCT), and there are currently no effective treatment strategies. Avatrombopag has shown promising results in the treatment of several thrombocytopenia disorders. However, no studies have examined the efficacy and safety of avatrombopag in the treatment of PT after haplo-HSCT, and predicting clinical response to avatrombopag before initiation is not possible. Thrombopoietin (TPO) is the chief cytokine that regulates megakaryocyte production and maturation, and endogenous TPO may be a biomarker of avatrombopag response. Methods: This study evaluated outcomes in patients who received the treatment of avatrombopag for persistent severe thrombocytopenia after haplo-HSCT between October 2019 and March 2022. On starting avatrombopag treatment, all included patients were with platelet counts ≤20×109/L and/or with platelet transfusion-dependence. Efficacy was assessed based on the platelet counts. Response was defined as platelet recovery to independence from platelet transfusion during or within 7 days after avatrombopag treatment, and complete response (CR) was defined as platelet recovery to ≥ 50×109/L for 7 consecutive days without platelet transfusion support. Endogenous TPO levels were measured by ELISA. Results: We report a cohort of 69 patients with PT after haplo-HSCT who were treated with avatrombopag. The 69 patients included 43 (62.3%) males and 26 (37.7%) females. The median age was 37 (11-60) years. Before starting avatrombopag therapy, the median platelet count was 15×109/L (range, 2-20×109/L). Forty patients (58.0%) had delayed platelet engraftment, and 29 patients (42.0%) had secondary failure of platelet recovery. Sixteen (23.2%) of the 69 patients had a history of using other TPO-RA (rhTPO or eltrombopag) for at least one round. Avatrombopag was initiated on a median of 59 (range 16-824) days after haplo-HSCT. Both the median starting and maximum doses were 40 mg daily. The rate of platelet recovery to transfusion independence was 72.5%, and the rate of platelet recovery to ≥ 50 ×109/L without transfusion support was 56.5%. Forty-seven (94.0%) of the 50 responders were able to taper off avatrombopag. The median duration of treatment was 40 (range 15-195) days. In addition, we present a novel clinical investigation of the use of TPO levels to predict the response to avatrombopag in patients with PT after haplo-HSCT. Logistic regression models demonstrated a significant predictive relation between TPO levels and probability of response. The TPO levels were inversely correlated with response (r = −0.998, P =0.011).(Figure) ROC analysis identified TPO levels ≤1714 pg/mL as the optimal threshold for discriminating responders and nonresponders. Based on univariate analysis, the presence of megakaryocytes in bone marrow before initiation (P=0.016), lower endogenous TPO levels (P =0.024) and no prior history of TPO-RA treatment (P =0.021) were independent factors that influenced the efficacy of avatrombopag. In the multivariate analysis, lower endogenous TPO levels (P =0.021) and no prior history of TPO-RA treatment (P=0.018) were independent factors that influenced the efficacy of avatrombopag. Avatrombopag was well tolerated in all patients, and patients responding to avatrombopag achieved improved overall survival (77.3% vs. 96.6%, P=0.008). Conclusions: Avatrombopag is a safe and effective therapy for severe PT after haplo-HSCT, and endogenous TPO levels prior to treatment could predict the response to avatrombopag. Key words: Avatrombopag, Persistent thrombocytopenia, Allogeneic hematopoietic stem cell transplantation, Haploidentical Figure legends：Multiple logistic regression models for the probability of response to avatrombopag based on endogenous TPO levels. The shaded area represents the 95% CI. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Graft-Versus-Leukemia Effect Is Independent from Graft-Versus-Host Disease Following Ptcy-Based HLA-Haploidentical Transplantation

Background. The potential link between graft-versus-host disease (GVHD) occurrence and acute myeloid leukemia (AML) relapse in patients given human leukocyte antigen (HLA)-haploidentical allogeneic hematopoietic stem cell transplantation (Haplo-HCT) with post-transplant cyclophosphamide (PTCy)-based GVHD prophylaxis has remained debated. Here, we addressed this issue in a large cohort of AML patients with active AML at transplantation, a group of patients who mainly depends on graft-versus-leukemia (GVL) effects for tumor eradication. Methods. Population selection criteria for this study consisted of adults (>= 18 years old), first Haplo-HCT between 2010 and 2020 using PTCy-based GVHD prophylaxis, and primary refractory or relapsed AML (i.e. all patients had active disease at the time of transplant conditioning initiation). Twelve serial Landmark analyses from day 30 to day 365 were generated to assess the impact of GVHD on transplantation outcomes (dynamic landmarking). Results. A total of 803 patients met the population selection criteria. One hundred and thirty-three of them were excluded from the analyses because they died before achieving engraftment (n=90), received a second transplantation for graft failure (n=10) or because missing data in the registry on GVHD (n=31) or missing conditioning intensity (n=2). Therefore, the analyses were carried out in a cohort of 670 patients who were alive and had engrafted. Status at transplantation was primary refractory (55%), first relapse (35%) or second or more advanced relapse (10%). Conditioning was myeloablative in 289 patients. Two-year relapse and nonrelapse mortality incidences were 49% and 19%, respectively. Two-year leukemia-free survival (LFS) was 32%. There were no associations between acute nor chronic GVHD of any grade and lower relapse incidence. In contrast, each grade III-IV acute (HR=3.79, P<0.0001) and extensive chronic (HR=3.23, P<0.0001) GVHD correlated with higher nonrelapse mortality, translating to decreased LFS (HR=1.51, P=0.008 for grade III-IV acute and HR=1.90, P=0.0008, for extensive chronic GVHD, respectively). Conclusions. Our study suggests a dissociation of GvL effects from GVHD in patients with active AML given PTCy-based Haplo-HCT.

Successful eradication of rituximab-refractory EBV-related post- transplant lymphoproliferative disorder after second haplo-identical allogeneic hematopoietic stem cell transplantation for very severe aplastic anemia – a case report

EBV-related post-transplant lymphoproliferative disorder (PTLD) is a potentially fatal disorder arising after solid organ or hematopoietic stem cell transplant (HSCT). The principle of management includes reduction of immune suppression, rituximab, and chemotherapy. We presented a female patient of very severe aplastic anemia (VSAA) complicated with initial graft dysfunction and then graft failure 2 months after haplo-identical allogeneic HSCT, with no response to salvage cyclosporine plus eltrombopag. EBV-related PTLD occurred 6 months after first haplo-transplant as shown by high EBV PCR. The patient initially responded to 6 shots of weekly rituximab, and then progression to ultrahigh level of EBV DNAemia was observed with the presence of intra-hepatic PTLD that was refractory to rituximab. This patient subsequently underwent second haplo-identical allogeneic transplant from the same donor with megadose of stem cell number plus alkylating agent containing RIC regimen. The results were successful hematopoietic engraftment on day +15, clearance of EBV DNAemia in one month, and thereafter eradication of intra-hepatic EBV-PTLD. In conclusion, EBV-related PTLD refractory to rituximab alone is still sensitive to rituximab plus chemotherapy preparative regimen during subsequent allogeneic HSCT, and it is still feasible to perform allo-transplant for transplant-eligible patients despite the presence of rituximab-refractory EBV DNAemia and PTLD.

Outcomes of two-step haploidentical allogeneic stem cell transplantation in elderly patients with hematologic malignancies.

Allogeneic hematopoietic stem cell transplantation (allo-SCT) remains the best curative option for the majority of patients with hematologic malignancies (HM); however, many elderly patients are excluded from transplant and outcome data in this population is still limited. The novel two-step graft engineering approach has been the main platform for allo-SCT at Thomas Jefferson University since 2006. Following administration of the preparative regimen, we infuse donor lymphocytes, followed by cyclophosphamide to induce bidirectional tolerance, then infusion of CD34-selected cells. A total of 76 patients ≥ 65 years old with HM underwent haploidentical (haplo) allo-SCT on the two-step transplant platform between 2007 and 2021. The median time to neutrophil engraftment was 11 days and platelet engraftment was 18 days. With a median follow up of 44 months, the 3-year overall survival (OS) and progression-free survival (PFS) were 36.3% and 35.6%, respectively. The cumulative incidences of non-relapse mortality (NRM) and relapse at 3 years were 43.5% and 21.0% at 3 years, respectively. The cumulative incidence of grade III-IV acute graft-versus-host-disease (GVHD) was 11.1% at 6 months, and chronic GVHD requiring treatment was 15.1% at 2 years. The two-step haplo allo-SCT is a novel alternative platform for high-risk older HM patients, achieving fast engraftment, low relapse rates and promising survival.

Fludarabine and antithymocyte globulin-based conditioning regimen combined with post-transplantation cyclophosphamide for haploidentical allogeneic hematopoietic stem cell transplantation in patients with high-risk acute myeloid leukemia and myelodysplastic syndrome

IntroductionRelapse and graft-versus-host disease (GVHD) are the important complications influencing mortality for patients with high-risk acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). GVHD prophylaxis based on post-transplant cyclophosphamide (PTCy) or antithymocyte globulin (ATG) is widely used in haploidentical HSCT (haplo-HSCT). ObjectiveWe developed a modified intensified conditioning regimen including fludarabine (Flu) and investigated the effect of ATG-PTCy combination on transplant outcomes in high-risk AML and MDS compared with those patients who received only ATG as GVHD prophylaxis. MethodsA total of 80 patients with high-risk AML and MDS were divided into two groups and assigned to one-to-one pairing. ResultsThe modified ATG-PTCy group had more infused mononuclear cells, CD34-positive cells and CD3-positive cells than those in the ATG group (P < 0.05). The amount of platelet transfusion was higher in the ATG group than the modified ATG-PTCy group [2 (range, 1–6) U vs 2 (range, 1–5) U, P = 0.005]. The median of platelet recovery was better in the modified ATG-PTCy group than in the ATG group (12 days vs 13 days,P = 0.041). The infection rates of bacteria, fungi and virus at 100 days after transplantation were similar in both groups. Compared with the ATG group, individuals who received the modified ATG-PTCy regimen had higher 2-year GVHD- and relapse-free survival(GRFS) [60.0% (95%CI, 44.9–75.1%) vs 34.8% (95%CI, 19.9–49.7%), P = 0.028]; lower 180-day incidence of II-IV acute GVHD (aGVHD) [15.0% (95%CI, 4.0–26.0%) vs 39.8% (95%CI, 23.9–55.7%), P = 0.029]; lower 1-year incidence of moderate to severe chronic GVHD (cGVHD) [2.9% (95%CI, 2.0–3.8%) vs 19.6% (95%CI, 5.3–33.9%), P = 0.039]; and without an increase in the 2-year cumulative incidence of relapse (CIR) [19.5% (95%CI, 6.6–32.4%) vs 30.4% (95%CI, 15.3–45.5%), P = 0.291]. ConclusionsHigh-dose stem cells can promote blood cell implantation. The modified ATG-PTCy combination was associated with decreased risk of aGVHD and cGVHD, no increased risk of recurrence, and improved GRFS. It represents an effective strategy for high risk AML and MDS.

Impact on outcomes of mixed chimerism of bone marrow CD34+ sorted cells after matched or haploidentical allogeneic stem cell transplantation for myeloid malignancies.

Allogeneic hematopoietic stem cell transplantation (Allo-HSCT), proposed to patients with high-risk myeloid malignancies, may ultimately fail because of disease relapse. Bone marrow (BM) CD34+ cells in Allo-HSCT recipients can be either re-emerging recipient malignant cells or donor cells attesting of hematopoietic reconstitution. In this context, investigating donor/recipient chimerism in the population of BM CD34+ sorted cells (BM-CD34+SC) was performed in 261 Allo-HSCT recipients (matched n = 145, haploidentical n = 65, matched unrelated n = 51) with myeloid malignancies. BM-CD34+SC chimerism was compared to that of whole peripheral blood (PB) cells as well as other Allo-HSCT-related parameters, and impact on relapse and survival was assessed. Thresholds of 98% donor cells for PB and 90% for BM-CD34+SC were found to allow relapse prediction. This was completed by the application of machine learning tools to explore the predictive value of these parameters in multidimensional models with repeated iterations. BM-CD34+SC mixed chimerism stood out with all these methods as the most robust predictor of relapse with a significant impact on disease-free and overall survivals even after haploidentical Allo-HSCT and/or PTCY administration. This marker therefore appears to be of great interest for the decision of preemptive treatment to avoid post-transplant relapse.

PB2189: HAPLOIDENTICAL HEMATOPOIETIC STEM CELL TRANSPLANTATION IN PATIENTS WITH SEVERE CONGENITAL NEUTROPENIA:A CASE REPORT OF 13 YEARS OLD PATIENT

Background: Haploidentical hematopoietic stem cell transplantation in patients with severe congenital neutropenia:A case report of 13 Years old patient Aims: Severe congenital neutropenia (SCN) is a heterogeneous group of diseases progressing with arrest of maturation in bone marrow. It is characterized by recurring skin, lung, and deep tissue infections from the first months of life. The use of G-CSF therapy has radically changed these patients’ outlook. However, a minority of patients is refractory to G-CSF, and some undergo malignant transformation. Methods: Allogeneic hematopoietic stem cell transplantation (HSCT) appears to be the only curative treatment for such patients. We report a 13 years femal patient who presented in years of life with severe neutropenia with a mutation in ELANE. This patient is allergic to a variety of antimicrobial drugs, difficult to treat, low quality of life, and has a high possibility of conversion to leukemia. In order to improve the quality of life, reduce the risk of conversion to leukemia and prolong its survival time, the transplantation treatment procedure was started through communication with patients and their families.Since the patient has no sibling full donor, the donor chooses the non consanguineous half matched donor sought by the bone marrow bank. The patient received conditioning regimens used for leukemia (myeloablative regimens),including CY (120–200 mg/kg) and BU (16–20 mg/kg or 560 mg/m2 administered orally, generally divided into 16 doses). In addition to the BU and CY combination, the agents used for conditioning included ATG. Results: The transplantation process was smooth, with granulocyte implantation on day + 14 and platelet implantation on day + 22. The hemogram returned to normal after 48 days. The STR-PCR was detected on + 30d, + 60d, + 90d, + 180d and + 270d respectively to evaluate the evidence of implantation and the chimeric body showed complete chimerism after transplantation. So far, the patient has survived without events for 20 months. After transplantation, the patient’s congenital gene ELANE mutation disappeared. Summary/Conclusion: Adolescents with SCN who long term dependence on G-CSF can receive haploidentical allogeneic hematopoietic stem cell transplantation.

Midostaurin in the treatment of a patient with acute myeloid leukaemia with FLT3-TKD mutation and NPM1 mutation

Acute myeloid leukaemia (AML) is aggressive cancer with a diverse clinical course which mainly results from the heterogeneous and complex molecular landscape of the disease. For some genetic alterations, in particular mutations in the FMS-like tyrosine kinase 3 ( FLT3 ) gene, the prognosis of patients with newly diagnosed AML depends on the coexistence of other genetic disorders. A thorough understanding of the interactions between mutations is key to improving risk stratification in newly diagnosed AML and personalizing therapy. The addition of midostaurin, an FLT3 tyrosine kinase inhibitor, to standard chemotherapy improved outcomes in the unfavourable prognostic group of AML patients. This research describes a therapeutic strategy in a patient with newly diagnosed AML with FLT3-tyrosine kinase domain (TKD) mutation and wild-type NPM1 who has received a standard remission induction and consolidation chemotherapy in combination with midostaurin, followed by maintenance therapy with an FLT3 inhibitor and haploidentical allogeneic hematopoietic stem cell transplantation.

High plasma IL-6 levels following haploidentical allogeneic hematopoietic stem cell transplantation post-transplant cyclophosphamide as predictor of early death and worse outcome

IntroductionHaploidentical hematopoietic stem cell transplantation (haplo-HSCT) can be used as an alternative procedure in the absence of HLA-compatible donors. The use of high doses of cyclophosphamide after infusion improves the prognosis and eliminates the need for T cell depletion in vivo. Among the main complications of haplo-HSCT are acute graft-versus-host disease (a-GVHD) and cytokine release syndrome (CRS). This is a systemic inflammatory response that leads to the release of inflammatory proteins, including IL-6. This syndrome has several clinical features, with mild to severe symptoms. This study aimed to compare plasma IL-6 levels in patients submitted to different HSCT types and to associate them with the presence of acute graft versus host disease (a-GVHD), CRS and survival. MethodsA total of 84 patients (22 haploidentical and 62 non-haploidentical) were evaluated at different times. The IL-6 levels in haplo and non-haplo-HSCT recipients were measured before transplantation and on days D7, D14, D28, D60, and D100. ResultsIL-6 levels were higher in haplo-HSCT recipients than in non-haplo-HSCT recipients, remaining elevated from D14 until D100 (P = 0.006) and a cut-off ≥11 pg/mL on D7, which is related to worse overall survival. In our study, we found no association with a-GVHD (P = 0.239), a common complication of this type of transplant, but we found a relationship between the increase in IL-6 and CRS (P = 0.021). ConclusionIL6 can be used as a biomarker for patients submitted to haplo-HSCT, allowing clinical interference in patients having levels of IL-6 times larger than normality values, avoiding early death in this group of patients.