Missing HLA C group 1 ligand in patients with AML and MDS is associated with reduced risk of relapse and better survival after allogeneic stem cell transplantation with fludarabine and treosulfan reduced toxicity conditioning

Molecular relapse monitoring reveals the domination of impaired NK cell education over impaired inhibition in missing KIR-ligand recognition in patients after unrelated hematopoietic stem cell transplantation for malignant diseases

Transplantation of HLA and/or KIR mismatched allogeneic hematopoietic stem cells can lead NK cells to different states of activation/inhibition or education/resetting and change anti-tumor immunosurveillance. In this study, we used molecular relapse monitoring to investigate a correlation between either missing ligand recognition or variation of the cognate iKIR-HLA pairs with clinical outcomes in patients with hematological malignancies requiring allogeneic hematopoietic stem cell transplantation (allo-HSCT). Patients (N = 418) with acute myeloid leukemia (AML), chronic myeloid leukemia (CML), acute lymphoblastic leukemia (ALL), myelodysplastic syndrome (MDS), or lymphoma receiving T-cell repleted graft from HLA-matched or partly mismatched unrelated donors between 2012 and 2020 in our center were included in this study. Missing-ligand recognition was assessed through the presence or absence of recipients' HLA ligand for a particular inhibitory KIR (iKIR) exhibited by the donor. Inhibitory KIR-HLA pair number variation was defined by loss or gain of a new cognate pair of HLA-KIR within the new HLA environment of the recipient, compared with the donor's one. Considering the results of our research, we drew the following conclusions: (i) loss of iKIR-HLA cognate pair for C1, C2, and/or Bw4 groups led to significant deterioration of disease-free survival (DFS), molecular relapse, overall survival (OS) and non-relapse mortality (NRM) for patients undergoing allo-HSCT in the standard phase of the disease. This phenomenon was not observed in patients who underwent transplantation in advanced hematological cancer. (ii) The missing ligand recognition had no impact if the proportion of HLA mismatches was not considered; however, adjustments of HLA mismatch level in the compared groups highlighted the adverse effect of the missing ligand constellation. (iii) The adverse effect of adjusted missing ligand suggests a predominance of lost NK cell education over lost NK cell inhibition in posttransplant recipients' new HLA environment. Our results suggested that donors with the loss of an iKIR-HLA cognate pair after transplantation should be avoided, and donors who provided an additional iKIR-HLA cognate pair should be preferred in the allo-HSCT donor selection process.

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

BACKGROUND

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.

METHODS

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).

RESULTS

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.

CONCLUSION

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.

Treosulfan-Based Conditioning Regimen Prior to Allogeneic Stem Cell Transplantation: Long-Term Results From a Phase 2 Clinical Trial

Introduction

Reducing toxicities while preserving efficacy in allogeneic stem cell transplant (allo-HCT) remains a particularly challenging problem. Different strategies to enhance the antitumor activity without increasing early and late adverse toxicities of the conditioning regimens have been investigated.

Methods

The aim of “AlloTreo” prospective phase 2 clinical trial was to evaluate the efficacy and safety of a conditioning regimen based on Treosulfan (42 g/m²) and fludarabine (https://clinicaltrials.gov/ct2/show/NCT00598624). We enrolled 108 patients with hematological diseases who received a first allo-HCT between June 2005 and January 2011, inside the frame of this trial at our center. Median age at allo-HCT was 49 (21–69) years. Disease Risk Index was low in 14 (13%) patients, intermediate in 73 (67.7%), high in 17 (15.7%), and very high in 4 (3.7%). Donors were human leukocyte antigen (HLA)-matched related in 50 cases, 10/10-matched unrelated in 36, and 9/10-mismatched unrelated in 22. Graft-versus-host disease (GvHD) prophylaxis consisted of cyclosporine-A and methotrexate. Anti-T-lymphocyte globulin (ATLG) was administered in patients receiving unrelated allo-HCT. Stem cell source was mainly peripheral blood stem cells (95%).

Results

Conditioning regimen was well tolerated. Full donor chimerism was documented for most patients (88%) at day +30. At 12 years, overall survival (OS) was 41.7% (32.2%–50.9%), progression-free survival (PFS) was 31.7% (23%–40.7%), GvHD-free/relapse-free survival was 20.9% (13.7%–29.1%), cumulative incidence (CI) of relapse was 44.5% (34.9%–53.6%), and transplant-related mortality (TRM) was 22.5% (15.1%–30.9%). CI of acute GvHD grades II–IV was 27.8% (19.7%–36.5%) at 100 days; 12-year CI of chronic GvHD was 40.7% (31.3%–49.9%). Relevant long-term adverse effects were 10 secondary malignancy, 3 fatal cardiovascular events, and 1 late-onset transplant-associated thrombotic microangiopathy. Ten successful pregnancies were reported after allo-HCT. In multivariate analysis, older age (≥60 years) at transplant [hazard ratio (HR), 2.157; p = 0.004] and a high/very high disease risk index (HR, 1.913; p = 0.026) were significantly associated with a lower OS.

Conclusions

Overall, our data confirmed the myeloablative potential and safe toxicity profile of full dose Treo (42 g/m²) especially for the younger population.

BSHI guideline: HLA matching and donor selection for haematopoietic progenitor cell transplantation

A review of the British Society for Histocompatibility and Immunogenetics (BSHI) Guideline 'HLA matching and donor selection for haematopoietic progenitor cell transplantation' published in 2016 was undertaken by a BSHI appointed writing committee. Literature searches were performed and the data extracted were presented as recommendations according to the GRADE nomenclature.

Long-Term Outcomes of Treosulfan- vs. Busulfan-Based Conditioning Regimen for Patients With Myelodysplastic Syndrome and Acute Myeloid Leukemia Before Hematopoietic Cell Transplantation: A Systematic Review and Meta-Analysis

Background

Many studies aimed to evaluate the efficacy and safety of treosulfan-based conditioning regimens for allogeneic hematopoietic cell transplantation (allo-HCT) compared with other regimens, but different outcomes were reported across studies.

Aim

To determine the long-term survival outcomes of treosulfan-based vs. busulfan-based conditioning regimens in myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML) patients.

Methods

PubMed, Embase, and Cochrane library were searched for studies published prior to December 6, 2019. The fixed-effects model was applied for overall survival (OS), leukemia-free survival (LFS), non-relapse mortality (NRM), acute and chronic graft versus host disease (GvHD). Relapse incidence (RI) was pooled by the use of the random-effects model.

Results

Six studies were included (3,982 patients; range, 57-1,956). The pooled HR for OS favored treosulfan (HR=0.80, 95%CI: 0.71-0.90). There was no significant difference in NRM between the two regimens (HR=0.84, 95%CI=0.71-1.01). There was no significant difference in LFS between the two regimens (HR=0.98, 95%CI=0.87-1.12). Treosulfan-based regimens showed a lower risk of aGvHD (HR=0.70, 95%CI=0.59-0.82), but there was no difference for cGvHD (HR=0.94, 95%CI=0.81-1.09). There was no significant difference in RI between the two regimens (HR=0.96, 95%CI=0.71-1.31). There was no publication bias among these studies.

Conclusion

The current meta-analysis determined that treosulfan-based conditioning regimens could improve the OS in patients with MDS and AML, with lower acute graft-versus-host disease incidence, compared with busulfan-based regimens.

[Effect of KIR/HLA receptor-ligand mode on prognosis of single unrelated cord blood transplantation in patients with hematological malignancies]

目的

探讨自然杀伤细胞免疫球蛋白样受体（KIR）与人类白细胞抗原（HLA）受配体模式对血液病患者单份非血缘脐血移植（sUCBT）预后的影响。

方法

回顾性分析2012年7月至2018年6月270例接受sUCBT的血液病患者。移植前脐血及患者均进行HLA12个位点高分辨配型，选择移植物（脐血）的KIR均同时表达2DL1和2DL2/2DL3抑制性基因，根据患者KIR配体情况分为缺失组（C1/C1或C2/C2）和无缺失组（C1/C2）。

结果

270例血液病患者中男146例（54.1％），女124例（45.9％），中位年龄13（1～62）岁；缺失组174例（64.4％），无缺失组96例（35.6％）。全部患者均采用不含抗胸腺细胞球蛋白（ATG）清髓性预处理方案。缺失组、无缺失组粒细胞植入率均为98.9％（172/174、95/96），中位植入时间分别为16（10～41）d、17（11～33）d（P＝0.705）；血小板植入率分别为88.5％（154/174）、87.5％（84/96），中位植入时间分别为35（11～113）d、38.5（13～96）d（P＝0.317）；缺失组、无缺失组Ⅱ～Ⅳ级急性GVHD发生率分别为38.7％（95％CI 31.4％～45.9％）、50.0％（95％CI 39.6％～59.6％）（P＝0.075），多因素分析显示KIR配体缺失是影响Ⅱ～Ⅳ度急性GVHD发生的独立保护性因素（P＝0.036）。移植后3年累积复发率分别为17.7％（95％CI 11.7％～24.9％）、22.7％（95％CI14.4％～32.2％）（P＝0.288）。中位随访时间742（335～2 512）d，缺失组、无缺失组3年总生存率分别为72.1％（95％CI 64.1％～78.6％）、60.5％（95％CI 47.9％～69.2％）（χ²＝3.629，P＝0.079），3年无病生存率分别为64.9％（95％CI 56.2％～72.3％）、55.4％（95％CI 44.4％～65.0％）（χ²＝3.027，P＝0.082），移植后180 d 非复发死亡率分别为12.1％（95％CI 7.7％～17.4％）、16.7％（95％CI 10.0％～24.8％）（P＝0.328）。

结论

在不含ATG清髓性预处理sUCBT血液病治疗体系中，缺失抑制性KIR配体患者移植后急性GVHD发生率更低。

Intravenous Busulfan Compared with Treosulfan-Based Conditioning for Allogeneic Stem Cell Transplantation in Acute Myeloid Leukemia: A Study on Behalf of the Acute Leukemia Working Party of European Society for Blood and Marrow Transplantation

Dose intensity of the conditioning regimen has significant impact on the outcomes after stem cell transplantation (SCT) for acute myeloid leukemia. Most studies have shown more relapse, less nonrelapse mortality (NRM), and similar overall survival after reduced-intensity and myeloablative conditioning. There are limited data on the dose equivalence and expected outcomes of treosulfan-based compared with busulfan-based conditioning. We compared SCT outcomes after fludarabine with either intravenous busulfan at a myeloablative dose (FB4, 12.8 mg/kg, n = 1265) or a reduced dose (FB2, 6.4 mg/kg, n = 1456) or treosulfan at 42 g/m² (FT14, n = 403) or 36 g/m² (FT12, n = 168). Median patient age was 48, 60, 57, and 60 years in the FB4, FB2, FT14, and FT12 groups, respectively (P < .0001). Two-year overall survival was 58%, 53%, 53%, and 51%, respectively (P = .25). Multivariate analysis identified advanced age, advanced disease status, and secondary leukemia to be associated with worse survival. Relapse rate was 30%, 35%, 34%, and 40%, respectively. Relapse was more common after FB2, advanced age and disease status, secondary leukemia, and sibling donors. NRM was 17%, 18%, 21%, and 16%, respectively. NRM was least common after FT12 and more common with advanced age and disease status and unrelated donors. Treosulfan-based regimens were associated with lower rates of graft-versus-host disease. There was no difference in any outcome among patients in first complete remission at transplantation. However, there was better survival with treosulfan-based conditioning in advanced leukemia. In conclusion, survival is determined mostly by disease biology and is similar after various regimens. Treosulfan-based conditioning is more similar to myeloablative than to reduced-intensity conditioning but can be administered safely in older patients, with lower rates of graft-versus-host disease and possibly better outcomes in patients with active leukemia.

The effect of killer cell immunoglobulin-like receptor genotype on outcome of hematopoietic stem cell transplantation from matched sibling

The alloreactivity of natural killer (NK) cell after allogeneic hematopoietic stem cell transplantation (AHSCT) is regulated by the interaction between donor killer immunoglobulin-like receptors (KIRs) and recipient human leukocyte antigen (HLA)-class I molecules. The aim was to identify KIR genes, haplotypes and their HLA-class I ligands and to investigate their association with transplantation outcome. The study included 65 patient/donor pairs who received AHSCT from HLA-matched identical siblings. KIR genotyping was done for donors using reverse sequence specific oligonucleotide probes (rSSO) coupled with luminex technology, while HLA-C genotyping was performed in patients using rSSO strip assay. In multivariate analysis, KIR2DS4 was associated with significant reduced incidence of relapse (p = .002). A trend towards reduced incidence of relapse was also observed with more than two KIR B motifs (p = .09), whereas a significant increased relapse was associated with homozygous HLA-C2 ligand compared to combined C1/C2 and C1/C1 (p = .04). Activating KIR2DS3 was associated with rapid leukocyte engraftment (p = .02). While, KIR 2DL5 was associated with decreased CMV infection (p = .03) and better platelets engraftment (p = .05). KIR genes, haplotypes and HLA-C alleles have an impact on HSCT outcome. Better selection of donors with favorable KIR genotype can improve HLA-matched sibling HSCT outcome especially for AML patients.