[Analysis of the efficacy and prognostic factors of allogeneic hematopoietic stem cell transplantation in patients with myelodysplastic syndrome with blastomycosis and survival comparison of different subtypes after the WHO 2022 reclassification].

Objective: To evaluate the efficacy and prognostic factors of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with myelodysplastic syndrome accompanied by myelodysplasia (MDS-EB) and to compare the prognosis of different subtypes of patients classified by World Health Organization (WHO) 2022. Methods: A total of 282 patients with MDS-EB who underwent allo-HSCT at the Hematology Hospital of the Chinese Academy of Medical Sciences from October 2006 to December 2022 were included in the study. The WHO 2022 diagnostic criteria reclassified MDS into three groups: myelodysplastic tumors with type 1/2 of primitive cell proliferation (MDS-IB1/IB2, 222 cases), MDS with fibrosis (MDS-f, 41 cases), and MDS with biallelic TP53 mutation (MDS-biTP53, 19 cases). Their clinical data were retrospectively analyzed. Results: ① The median age of 282 patients was 46 (15-66) years, with 191 males and 91 females. Among them, 118 (42% ) and 164 (58% ) had MDS-EB1 and MDS-EB2, respectively. ②Among the 282 patients, 256 (90.8% ) achieved hematopoietic reconstruction after transplantation, with 11 (3.9% ) and 15 (5.3% ) having primary and secondary implantation dysfunctions, respectively. The cumulative incidence of acute graft-versus-host disease (GVHD) 100 days post-transplantation was (42.6±3.0) %, and the cumulative incidence of grade Ⅱ-Ⅳ acute GVHD was (33.0±2.8) %. The cumulative incidence of chronic GVHD 1 year post-transplantation was (31.0±2.9) %. Post-transplantation, 128 (45.4% ), 63 (22.3% ), 35 (12.4% ), and 17 patients (6.0% ) developed cytomegalovirus infection, bacteremia, pulmonary fungal infection, and Epstein-Barr virus infection. ③The median follow-up time post-transplantation was 22.1 (19.2-24.7) months, and the 3-year overall survival (OS) and disease-free survival (DFS) rates were 71.9% (95% CI 65.7% -78.6% ) and 63.6% (95% CI 57.2% -70.7% ), respectively. The 3-year non-recurrent mortality rate (NRM) is 17.9% (95% CI 13.9% -22.9% ), and the 3-year cumulative recurrence rate (CIR) is 9.8% (95% CI 6.7% -13.7% ). The independent risk factors affecting OS post-transplantation include monocyte karyotype (P=0.004, HR=3.26, 95% CI 1.46-7.29), hematopoietic stem cell transplantation complication index (HCI-CI) of ≥3 points (P<0.001, HR=2.86, 95% CI 1.72-4.75), and the occurrence of acute gastrointestinal GVHD of grade Ⅱ-Ⅳ (P<0.001, HR=5.94, 95% CI 3.50-10.10). ④The 3-year OS and DFS rates in the MDS-IB1/IB2 group post-transplantation were better than those in the MDS-biTP53 group [OS: 72.0% (95% CI 63.4% -80.7% ) vs 46.4% (95% CI 26.9% -80.1% ), P=0.020; DFS: 67.4% (95% CI 60.3% -75.3% ) vs 39.7% (95% CI 22.3% -70.8% ), P=0.015]. The 3-year CIR was lower than that of the MDS-biTP53 group [7.3% (95% CI 4.3% -11.4% ) vs 26.9% (95% CI 9.2% -48.5% ), P=0.004]. The NRM at 3 years post-transplantation in the MDS-IB1/IB2, MDS-f, and MDS-biTP53 groups were 16.7% (95% CI 12.1% -22.1% ), 20.5% (95% CI 9.4% -34.6% ), and 26.3% (95% CI 9.1% -47.5% ), respectively (P=0.690) . Conclusion: Allo-HSCT is an effective treatment for MDS-EB, with monomeric karyotype, HCI-CI, and grade Ⅱ-Ⅳ acute gastrointestinal GVHD as independent risk factors affecting the patient's OS. The WHO 2022 classification helps distinguish the efficacy of allo-HSCT in different subgroups of patients. Allo-HSCT can improve the poor prognosis of patients with MDS-f, but those with MDS-biTP53 have a higher risk of recurrence post-transplantation.

[A single-center retrospective study of salvage allogeneic hematopoietic stem cell transplantation pretreated with MeCBA regimen for refractory/relapsed acute myeloid leukemia].

Thirty refractory relapsed acute myeloid leukemia (R/R AML) patients who received salvage allo-HSCT with MeCBA conditioning regimen from January 2018 to June 2022 at Henan Cancer Hospital were included, and their clinical data were reviewed. There were 16 males and 14 females among the 30 patients with a median age of 37 (16-53) years. There were 3 sibling allograft donor transplants, 1 unrelated donor transplant, and 26 haplotype transplants. The median course of pre-transplant chemotherapy was 4 (3-22). The time of neutrophil engraftment was 14 (9-22) days and 18 (10-40) days for platelet. The 30-day cumulative incidence of neutrophil engraftment was 100% and the 100-day cumulative incidence of platelet engraftment was 96.7% (95% CI 85.4% -97.5% ). 22 (73.3% ) patients experienced grade 1-2 gastrointestinal reactions, and there was no grade 3-4 organ toxicity. With a median follow-up of 37.1 months, the overall survival (OS) rate, event-free survival (EFS) rate, cumulative recurrence rate (CIR), and non-recurrence mortality (NRM) rate at 3 years after transplantation were 70.0% (95% CI 50.3% -83.1% ), 65.3% (95% CI 44.8% -79.8% ), 21.2% (95% CI 9.2% -44.4% ) and 16.7% (95% CI 7.3% -35.5% ), respectively.

[Two cases of systemic mastocytosis with RUNX1-RUNX1T1 positive acute myeloid leukemia treated with sequential avapritinib after allogeneic hematopoietic stem cell transplantation and literature review].

Systemic mastocytosis (SM) with RUNX1-RUNX1T1 positive acute myeloid leukemia (AML) is a rare myeloid tumor with no standard treatment. Two cases of SM patients with RUNX1-RUNX1T1 positive AML treated with sequential avapritinib after allogeneic hematopoietic stem cell transplantation (allo-HSCT) were reported in Henan Cancer Hospital. Mast cell in bone marrow disappeared, C-KIT mutation and RUNX1-RUNX1T1 fusion gene remained negative. Allo-HSCT sequential avapritinib is an effective treatment for SM patients with RUNX1-RUNX1T1 positive AML.

[Guillain-Barre syndrome after allogeneic hematopoietic stem cell transplantation: a case report and literature review].

Guillain-Barre syndrome rarely develops after allogeneic hematopoietic stem cell transplantation (allo-HSCT), and only a few reports exist in China. Guillain-Barre syndrome is an acute and life-threatening condition that requires early diagnosis and treatment. A patient with acute myeloid leukemia underwent allogeneic HSCT for >5 months and gradually developed limb muscle weakness and limited eye movement after coexisting with delayed acute intestinal graft-versus-host disease. After the examination of cerebrospinal fluid and electromyography, the diagnosis of Guillain-Barre syndrome was confirmed. After a high-dose intravenous immunoglobulin (IVIg) treatment, muscle strength gradually recovered, and the prognosis was good.

[Progress of allogeneic hematopoietic stem cell transplantation in KMT2A-rearranged acute leukemia].

KMT2A (lysine methyltransferase 2A) -rearranged acute leukemia is a class of leukemia with unique biological characteristics with moderate or poor prognosis. In recent years, allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been increasingly indicated for patients with KMT2A-rearranged acute leukemia. By reviewing the clinical studies of allo-HSCT in KMT2A-rearranged acute leukemia, the efficacy of allo-HSCT in children and adults with KMT2A-rearranged acute myeloid leukemia and acute lymphoblastic leukemia was assessed, the factors affecting the prognosis of allo-HSCT were summarized, and the methods that may improve the outcomes of allo-HSCT were explored.

The effect of ADAMTS13 on graft-versus-host disease.

Allogeneic haematopoietic stem cell transplantation (allo-HSCT) can potentially cure malignant blood disorders and benign conditions such as haemoglobinopathies and immunologic diseases. However, allo-HSCT is associated with significant complications. The most common and debilitating among them is graft-versus-host disease (GVHD). In GVHD, donor-derived T cells mount an alloimmune response against the recipient. The alloimmune response involves several steps, including recognition of recipient antigens, activation and proliferation of T cells in secondary lymphoid organs, and homing into GVHD-targeted organs. Adhesion molecules on T cells and endothelial cells mediate homing of T cells into lymphoid and non-lymphoid tissues. In this study, we showed that Von Willebrand factor (VWF), an adhesion molecule secreted by activated endothelial cells, plays an important role in mouse models of GVHD. We investigated the effect of the VWF-cleaving protease ADAMTS13 on GVHD. We found that ADAMTS13 reduced the severity of GVHD after bone marrow transplantation from C57BL6 donor to BALB/C recipient mice. A recombinant VWF-A2 domain peptide also reduced GVHD in mice. We showed that ADAMTS13 and recombinant VWF-A2 reduced the binding of T cells to endothelial cells and VWF in vitro, and reduced the number of T cells in lymph nodes, Peyer's patches and GVHD-targeted organs in vivo. We identified LFA-1 (αLß2) as the binding site of VWF on T cells. Our results showed that blocking T-cell homing by ADAMTS13 or VWF-A2 peptide reduced the severity of the GVHD after allo-HSCT, a potentially novel method for treating and preventing GVHD.

[Efficacy and safety of gilteritinib-based combination therapy bridging allo-HSCT in relapsed or refractory acute myeloid leukemia patients with positive FLT3-ITD mutation].

Objective: This study aims to evaluate the safety and effectiveness of gilteritinib (Gilt) -based combination therapy bridging allo-HSCT for FLT3-ITD(+) R/R AML. Additionally, it aims to assess the impact of Gilt maintenance therapy on the prognosis of patients after allo-HSCT. Methods: The clinical data of 26 patients with FLT3-ITD(+) R/R AML treated at the First Affiliated Hospital of Soochow University from August 2019 to January 2023 were retrospectively analyzed. The analysis included an assessment of the composite complete remission rate (CRc), overall survival (OS) time, disease-free survival (DFS) time, and adverse events experienced by all enrolled patients. Results: A total of 26 patients with FLT3-ITD(+) R/R AML were enrolled, including 14 men and 12 women with a median age of 38 (18-65) years. A total of 18 cases were refractory, and eight cases were relapsed. The curative effect evaluation conducted between 14 and 21 days showed that the complete remission (CR) rate was 26.9% (7/26), the CR with hematology incomplete recovery was 57.7% (15/26), and the partial response (PR) rate was 7.7% (2/26). The CRc was 84.6% (22/26), and the minimal residual disease (MRD) negativity rate was 65.4%. The 12 month cumulative OS rate for all patients was 79.0%, and the 24 month cumulative OS rate was 72.0%. The median OS time was not determined. The median follow-up time was 16.0 months. Among the patients who responded to treatment, the 12 month cumulative DFS rate was 78.0%, and the 24 month cumulative DFS rate was 71.0%. The median DFS time was not determined. Patients who received allo-HSCT had a median OS time that was significantly longer than those who did not receive allo-HSCT (3.3 months, 95%CI 2.2-4.3 months, P=0.005). The median OS time of patients with or without Gilt maintenance therapy after allo-HSCT was not determined, but the OS time of patients with Gilt maintenance therapy after allo-HSCT treatment was longer than that of patients without Gilt maintenance therapy after allo-HSCT treatment (P=0.019). The FLT3-ITD mutation clearance rate in this study was 38.5%, and the median OS time of patients with FLT3-ITD mutation clearance was not determined but was significantly longer than the median OS of patients without FLT3-ITD mutation clearance (15.0 months; P=0.018). The most common grade 3 and above hematological adverse events of Gilt-based combination therapy included leukopenia (76.9%), neutropenia (76.9%), febrile neutropenia (61.5%), thrombocytopenia (69.2%), and anemia (57.7%). One patient developed differentiation syndrome during oral Gilt maintenance therapy after allo-HSCT treatment, but his condition improved after treatment. Conclusion: The Gilt-based combination therapy is highly effective in treating FLT3-ITD(+) R/R AML. It demonstrates a high CRc, MRD negativity rate, and rapid onset, leading to a significant improvement in patients' survival. Furthermore, the clearance rate of FLT3-ITD mutation is notably high. Additionally, implementing bridging allo-HSCT and Gilt maintenance therapy after allo-HSCT treatment has considerably enhances patients' survival. Closely monitoring and managing any adverse event that may occur during treatment are crucial.

Clonal Hematopoiesis-Associated Gene Mutations Affect Acute Graft-Versus-Host Disease After Hematopoietic Stem Cell Transplantation in AML Patients.

BACKGROUND The relationship between clonal hematopoiesis (CH)-associated gene mutations and allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been extensively studied since next-generation sequencing (NGS) technology became widely available. However, research has mainly focused on the relationship between donor CH mutations and transplant prognosis, and research into the relationship between CH mutations in the recipient and acute graft-versus-host disease (aGVHD) is lacking. MATERIAL AND METHODS We analyzed NGS results and their correlation with aGVHD and prognosis in 196 AML patients undergoing allo-HSCT. RESULTS A total of 93 (47.4%) patients had CH mutations. The most frequently mutated genes were DNMT3A (28 of 196; 14.3%), TET2 (22 of 196; 11.2%), IDH1 (15 of 196; 7.7%), IDH2 (14 of 196; 7.1%), and ASXL1 (13 of 196; 6.6%). The incidence of aGVHD was higher in patients older than 45 years old with DTA mutations (DNMT3A, TET2 or ASXL1). DNMT3A mutation but not with TET2 or ASXL1 mutation was an independent risk factor for aGVHD in patients receiving allo-HSCT older than 45 years old. With a median follow-up of 42.7 months, CH mutations were not associated with overall survival and leukemia-free survival. CONCLUSIONS DNMT3A mutation, but not TET2 or ASXL1 mutation, was associated with higher incidence of aGVHD.

Visual restoration with KPro after face allotransplantation with a grade III phthisical eye.

The Boston Keratoprosthesis type I (KPro-I) has been shown to be successful in restoring vision after severe ocular burns; however, its long-term outcomes in phthisical eyes have rarely been reported. A monocular woman with a history of severe alkali chemical injury necessitating facial transplantation presented with a light perception left eye after a complicated course, including failed KPro-I, therapeutic penetrating keratoplasty, endophthalmitis, hypotony, total retinal detachment, and structural changes, including a shrunken 18 mm axial length and eye wall thickening. The patient underwent a combined vitrectomy with silicone oil and KPro-I implantation, resulting in her regaining ambulatory visual acuity (20/250) at 3 years' follow-up.

[Clinical efficacy of allogeneic hematopoietic stem cell transplantation for myelodysplastic syndrome-evolved acute myeloid leukemia].

Objective: The outcomes of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for myelodysplastic syndromes-evolved acute myeloid leukemia (MDS-AML) were explored. Methods: A retrospective review was conducted for 54 patients with MDS-AML treated with allo-HSCT in the Institute of Hematology and Blood Disease Hospital from January 2018 to August 2022. The clinical effects after transplantation were observed, and the related risk factors influencing prognosis were explored. Results: Of the total 54 patients, 26 males, 28 females, and 53 patients achieved hematopoietic reconstruction. After a median follow-up of 597 (15-1 934) days, the 1 year overall survival (OS) rate, disease-free survival (DFS) rate, relapse rate (CIR) and non-relapse mortality (NRM) rate were 75.8%±5.8%, 72.1%±6.1%, 12.7%±4.9%, and 17.1%±5.2%, respectively. The 3 year estimated OS, DFS, CIR, and NRM rates were 57.8%±7.5%, 58.1%±7.2%, 23.2%±6.6%, and 23.7%±6.6%, respectively. The cumulative incidence of acute graft-versus-host disease (aGVHD) was 57.5%±6.9%, and the cumulative incidence of chronic graft-versus-host disease (cGVHD) was 48.4%±7.7%. Hematopoietic cell transplantation comorbidity index (HCT-CI) before transplantation was ≥2, minimal residual disease (MRD) was positive on the day of reconstitution, grade Ⅲ/Ⅳ aGVHD, bacterial or fungal infection and no cGVHD after transplantation were adverse prognostic factors for OS (P<0.05). COX regression model for multivariate analysis showed that HCT-CI score before transplantation, bone marrow MRD on the day of response, grade Ⅲ or Ⅳ aGVHD, and cGVHD after transplantation were the independent adverse factors for OS (P=0.001, HR=6.981, 95%CI 2.186-22.300; P=0.010, HR=6.719, 95%CI 1.572-28.711; P=0.026, HR=3.386, 95%CI 1.158-9.901; P=0.006, HR=0.151, 95%CI 0.039-0.581) . Conclusion: For patients with MDS-AML and high risk of relapse, allogeneic transplantation must be considered as soon as possible. The enhanced management of post-transplantation complications and maintenance treatment should be provided whenever possible after transplantation.

[Analysis of therapeutic effects of allogeneic hematopoietic stem cell transplantation in 12 patients with DEK-NUP214 fusion gene positive acute myeloid leukemia].

Twelve DEK-NUP214 fusion gene-positive patients with acute myeloid leukemia and on allo-HSCT treatment at the Hematology Hospital of the Chinese Academy of Medical Sciences from November 2016 to August 2022 were included in the study, and their clinical data were retrospectively analyzed. The patients comprised five men and seven women with a median age of 34 (16-52) years. At the time of diagnosis, all the patients were positive for the DEK-NUP214 fusion gene. Chromosome karyotyping analysis showed t (6;9) (p23;q34) translocation in 10 patients (two patients did not undergo chromosome karyotyping analysis), FLT3-ITD mutation was detected in 11 patients, and high expression of WT1 was observed in 11 patients. Nine patients had their primary disease in the first complete remission state before transplantation, one patient had no disease remission, and two patients were in a recurrent state. All patients received myeloablative pretreatment, five patients received sibling allogeneic hematopoietic stem cell transplantation, and seven patients received haploid hematopoietic stem cell transplantation. The median number of mononuclear cells in the transplant was 10.87 (7.09-17.89) ×10(8)/kg, and the number of CD34(+) cells was 3.29 (2.53-6.10) ×10(6)/kg. All patients achieved blood reconstruction, with a median time of 14 (10-20) days for neutrophil implantation and 15 (9-27) days for platelet implantation. The 1 year transplant-related mortality rate after transplantation was 21.2%. The cumulative recurrence rates 1 and 3 years after transplantation were 25.0% and 50.0%, respectively. The leukemia free survival rates were (65.6±14.0) % and (65.6±14.0) %, respectively. The overall survival rates were (72.2±13.8) % and (72.2±13.8) %, respectively.

Cytology or Multiparameter Flow Cytometry Positivity in the Cerebrospinal Fluid Before Transplantation is Predictive of Poor Outcomes After Allotransplantation in Acute Myeloid Leukemia Patients.

INTRODUCTION: Central nervous system leukemia (CNSL) remains a serious complication in patients with acute myeloid leukemia (AML) and an ambiguous prognostic factor for those receiving allo-geneic hematopoiesis stem cell transplantation (allo-HSCT). It is unknown whether using more sensitive tools, such as multiparameter flow cytometry (MFC), to detect blasts in the cerebrospinal fluid (CSF) would have an impact on outcome. METHODS: We retrospectively analyzed the clinical outcomes of 1472 AML patients with or without cytology or MFC positivity in the CSF before transplantation. Abnormal CSF (CSF+) was detected via conventional cytology and MFC in 44 patients at any time after diagnosis. A control group of 175 CSF-normal (CSF-) patients was generated via propensity score matching (PSM) analyses according to sex, age at transplant, and white blood cell count at diagnosis. RESULTS: Compared to those in the CSF-negative group, the conventional cytology positive and MFC+ groups had comparable 8-year nonrelapse mortality (NRM) (4%, 4%, and 6%, p = 0.82), higher cumulative incidence of relapse (CIR) (14%, 31%, and 32%, p = 0.007), lower leukemia-free survival (LFS) (79%, 63%, and 64%, p = 0.024), and overall survival (OS) (83%, 63%, and 68%, p = 0.021), with no significant differences between the conventional cytology positive and MFC+ groups. Furthermore, multivariate analysis confirmed that CSF involvement was an independent factor affecting OS and LFS. CONCLUSION: Our results indicate that pretransplant CSF abnormalities are adverse factors independently affecting OS and LFS after allotransplantation in AML patients.

Characterization of recurrent cytomegalovirus reactivations post allogenic stem cell transplantation in a population with high seropositivity.

OBJECTIVES: This study aimed to characterize incidences of CMV reactivations within one year post-allo-SCT and identify risk factors for CMV second reactivation episode in population with high seropositivity where first CMV reactivation episode deemed to be high. METHODS: This retrospective cohort study analyzed data from 359 allo-SCT patients aged 14 and older admitted to a tertiary academic hospital. Data on demographic and clinical factors, CMV serostatus, conditioning regimens, graft-versus-host disease prophylaxis, engraftment time, and CMV reactivations were collected. RESULTS: First and second CMV reactivations occurred in 88.9% and 18.4% of post-allo-SCT patients respectively. Patients were stratified into two groups based on primary disease necessitating allo-SCT, patients with malignant (Group 1) and non-malignant (Group 2) hematological disease. Factors associated with the second reactivation included cord blood as a stem cell source, human leukocyte antigen mismatch, acute graft-versus-host disease, and hematological malignancies. Patients with non-malignant hematological disease displayed better outcomes, including a higher rate of spontaneous clearance of first CMV reactivation (70% versus 49.4%) and lower rates of second CMV reactivation (9.6% versus 31%) than those with malignant hematological disease. The one-year overall survival rate was 87.7% (95.5% in non-malignant hematological disease and 78.13% in malignant hematological disease). CONCLUSION: Our findings are concordant with previous local study in regard to high rate of first CMV reactivation post-allo-SCT. It appears that patients with nonmalignant hematological disease had better outcomes, such as lower second CMV reactivation and higher survival rates compared to patients with malignant hematological disease. Further investigation is needed to identify other factors affecting recurrent CMV reactivations in allo-SCT in patients with malignant hematological disease.

[Allogeneic hematopoietic stem cell transplantation in a patient with MonoMAC syndrome and hematopoietic dysplasia which was induced by GATA2 deficiency: a case report and literature review].

A retrospective analysis was conducted on a MonoMAC syndrome case admitted in October 2022 to the First Affiliated Hospital of Zhejiang University School of Medicine. The patient, a 16-year-old female with a history of persistent monocytopenia and mild anemia for several years, experienced recurrent symptoms of cough, expectoration, and fever, leading to multiple visits to the hospital. The diagnosis of MonoMAC syndrome was confirmed through comprehensive assessments including routine blood tests, pathogen metagenomic sequencing, lung and bone marrow biopsies, and next-generation sequencing of peripheral blood. The patient underwent haploidentical hematopoietic stem cell transplantation, with a smooth course of transplantation, achieving neutrophil engraftment on + 16 d and platelet engraftment on + 17 d, eventually restoring normal monocyte and NK cell counts. MonoMAC syndrome patients often initially present with infectious symptoms, and the diagnosis can be established based on significant monocytopenia in routine blood tests, history of non-tuberculous mycobacterial infections, and GATA2 germline mutations. Allogeneic hematopoietic stem cell transplantation may be required for some patients to improve their prognosis.

Expansion of effector memory Vδ2neg γδ T cells associates with cytomegalovirus reactivation in allogeneic stem cell transplant recipients.

Background: Cytomegalovirus (CMV) reactivation is a significant concern following allogeneic stem cell transplantation. While previous research has highlighted the anti-CMV reactivation effect of γδ T cells in immunocompromised transplant patients, their characterization in recipients at high risk of CMV reactivation remains limited. Methods: This study focused on D+/R+ recipients (where both donor and recipient are CMV seropositive) at high risk of CMV reactivation. We analyzed 28 patients who experienced CMV recurrence within 100 days post-allogeneic hematopoietic stem cell transplantation, along with 36 matched recipients who did not experience CMV recurrence. Clinical data from both groups were compared, and risk factors for CMV reactivation were identified. Additionally, CMV viral load was measured, and flow cytometric analysis was conducted to assess changes in peripheral blood γδ T cell proportions, subpopulation distribution, and differentiation status. We also analyzed the CDR3 repertoire of the TCR δ chain in different γδ T cell subsets. Functional analysis was performed by measuring the lysis of CMV-infected cells upon stimulation. Results: CMV reactivation post-transplantation was associated with acute graft-versus-host disease (aGvHD) and reactivation of non-CMV herpesviruses. Notably, CMV reactivation led to sustained expansion of γδ T cells, primarily within the Vδ2neg γδ T cell subpopulation, with a trend toward differentiation from Naive to effector memory cells. Analysis of the δ chain CDR3 repertoire revealed a delay in the reconstitution of clonal diversity in Vδ2neg γδ T cells following CMV reactivation, while Vδ2pos T cells remained unaffected. Upon stimulation with CMV-infected MRC5 cells, the Vδ2neg γδ T cell subpopulation emerged as the primary effector cell group producing IFN-γ and capable of lysing CMV-infected cells. Moreover, our findings suggest that NKG2D is not necessary involved in Vδ2neg γδ T cell-mediated anti-CMV cytotoxicity. Conclusion: This study provides novel insights into the role of γδ T cells in the immune response to CMV reactivation in transplantation recipients at high risk of CMV infection. Specifically, the Vδ2neg γδ T cell subpopulation appears to be closely associated with CMV reactivation, underscoring their potential role in controlling infection and reflecting CMV reactivation in HSCT patients.