T-cell-replete haploidentical transplantation in acute myeloid leukemia

Combining post-transplant cyclophosphamide with antithymocyte globulin for graft-versus-host disease prophylaxis in hematological malignancies

In search of an ideal partner or alternative to conventional immunosuppressive agents, rabbit anti-thymocyte globulin (ATG) and, more recently, post-transplant cyclophosphamide (PT-Cy) have both emerged as valid and efficient options for preventing graft-versus-host disease (GvHD). To further reduce the risk of GvHD, strategies combining ATG and PT-Cy have recently been investigated. In a haploidentical setting, retrospective studies suggest that combining PT-Cy and ATG may result in a lower incidence of chronic GvHD without increasing the risks of infection or relapse, when compared to PT-Cy without ATG. In haploidentical or unrelated donor settings, adding reduced doses of PT-Cy to ATG may reduce the risk of acute and chronic GvHD and improve survival, particularly GvHD-free, relapse-free survival (GRFS), when compared to ATG without PT-Cy. Overall, the combination of PT-Cy and ATG is a safe and promising approach for patients with hematological malignancies undergoing allogeneic hematopoietic stem cell transplantation (HSCT).

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

INTRODUCTION

Relapse 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).

OBJECTIVE

We 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.

METHODS

A total of 80 patients with high-risk AML and MDS were divided into two groups and assigned to one-to-one pairing.

RESULTS

The 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].

CONCLUSIONS

High-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.

Reduced post-transplant cyclophosphamide doses in haploidentical hematopoietic cell transplantation for elderly patients with hematological malignancies

Although post-transplant cyclophosphamide (PT-Cy) is effective for graft-versus-host disease (GVHD) prophylaxis, it is associated with toxicities, which might be dose-dependent. We compared the outcomes with PT-Cy at 80 mg/kg to those with PT-Cy at 100 mg/kg in elderly patients undergoing haploidentical hematopoietic cell transplantation (HCT). Inclusion criteria included peripheral blood stem cells, hematological malignancy, and age>65 years (or age>60 years if cardiac event history). Thirty-eight patients received PT-Cy at 80 mg/kg and 55 100 mg/kg, divided in two doses. The cumulative incidences (CI) of acute grade II-IV, acute grade III-IV, and moderate/severe chronic GVHD were 32%, 16%, and 13% with PT-Cy at 80 mg/kg compared to 33%, 13%, and 16% with 100 mg/kg, respectively. In multivariable analysis, reducing PT-Cy dose had no significant impact on GVHD. Neutrophil and platelet engraftments were significantly improved, and CI of BK virus-associated hemorrhagic cystitis was reduced with 80 mg/kg of PT-Cy compared to 100 mg/kg. At 2 years, non-relapse mortality was 16% and 31%, progression-free survival 65% and 49%, overall survival 70% and 56%, and GVHD-free, relapse-free survival 52% and 36% with 80 mg/kg and 100 mg/kg, respectively. Reducing PT-Cy dose to 80 mg/kg is safe and associated with improved hematological recovery and lower CI of hemorrhagic cystitis in elderly patients undergoing haploidentical HCT.

Haploidentical donor stem cell transplantation had a lower incidence of bronchiolitis obliterans syndrome compared with HLA-matched sibling donor transplantation in patients with hematologic malignancies: Benefit from ATG?

Background

Haploidentical donor stem cell transplantation (HID-SCT) based on antithymocyte globulin (ATG) for graft-versus-host disease (GVHD) prophylaxis had achieved a similar incidence of chronic graft-versus-host disease (cGVHD) with human leukocyte antigen (HLA)-matched sibling donor stem cell transplantation (MSD-SCT). However, bronchiolitis obliterans syndrome (BOS), which serves as pulmonary cGVHD, was rarely compared between HID and MSD transplantation.

Methods

One thousand four hundred five patients with hematologic malignancies who underwent allogeneic SCT were enrolled in this retrospective study. Based on donor type, we divided the patients into three groups: HID, MSD, and match unrelated donor (MUD) groups. The cumulative incidences and risk factors of BOS were analyzed.

Results

The 5-year cumulative incidence of BOS was 7.2% in the whole population. HID transplantation had a lower 5-year cumulative incidence of BOS than MSD transplantation (4.1% vs. 10.0%, p &lt; 0.001) and a similar incidence with MUD transplantation (4.1% vs. 6.2%, p = 0.224). The 5-year cumulative incidence of BOS was lower in the ATG group than that in the non-ATG group in both the whole and MSD populations (4.6% vs. 11.2%, p &lt; 0.001, and 4.1% vs. 11.2%, p = 0.042, respectively). The 5-year incidence of BOS in mixed grafts [peripheral blood stem cell (PBSC) plus bone marrow] group was also lower than that in the PBSC group (4.2% vs. 9.1, p = 0.001). Multivariate analysis showed that HID, ATG, and mixed grafts were protective factors for BOS [odds ratio (OR) 0.3, 95% CI 0.2–0.6, p &lt; 0.001; OR 0.3, 95% CI 0.2–0.7, p = 0.001; OR 0.3, 95% CI 0.1–0.8, p = 0.013], and acute graft-versus-host disease (aGVHD) and cGVHD were independent risk factors for BOS (OR 2.1, 95% 1.1–4.3, p = 0.035; OR 10.1, 95% CI 4.0–25.0, p &lt; 0.001).

Conclusions

HID transplantation had a lower incidence of BOS than MSD transplantation, which might be associated with ATG and mixed grafts.

Comparable Outcomes After Alternative and Matched Sibling Donor Hematopoietic Stem Cell Transplantation and the Role of Molecular Measurable Residual Disease for Acute Myeloid Leukemia in Elderly Patients

Allogeneic hematopoietic stem cell transplantation (HSCT) remains the most effective postremission therapy conferring the chance of cure for acute myeloid leukemia (AML), including elderly patients. Although the number of transplantations for elderly patients with AML (eAML) is increasing owing to greater availability of various graft sources together with the adoption of advanced supportive care and reduced-intensity conditioning (RIC) regimen, there are relatively limited data on the impact of donor type in eAML compared to younger patients. In addition, few studies have evaluated the role of pretransplantation measurable residual disease (MRD) in the elderly population. Given the lack of prospective comparative study, we retrospectively compared transplantation outcomes of elderly patient with AML receiving allo-HSCT from matched sibling donor (MSD-HSCT), matched unrelated donor (MUD-HSCT) or haploidentical related donor (Haplo-HSCT), or autologous HSCT (Auto-HSCT). A total of 154 patients with a median age of 63 years (range 60-74) underwent MSD-HSCT (n = 41), MUD-HSCT (n = 36), Haplo-HSCT (n = 55), or Auto-HSCT (n = 22) for AML. RIC regimens were used in the majority of patients. In Haplo-HSCT, T-cell-replete peripheral blood stem cells with unique RIC regimens using anti-thymocyte globulin (ATG)-based GVHD prophylaxis was used. In the analysis, adjustment for MRD status at the time of transplantation was performed. MRD was measured by the quantitative molecular assays of the targets, including RUNX1-RUNX1T1, CBFB-MYH11, and NPM1, or WT1 in the absence of abnormalities in the aforementioned targets. At a median follow-up of 48 months, survival rates were similar between different donor types, whereas nonrelapse mortality (NRM) was lower in MUD-HSCT compared to MSD-HSCT (P = .002). MSD-HSCT, in which the majority of patients received a conditioning regimen not including ATG, showed more frequent severe chronic graft-versus-host disease (cGVHD). The major causes of non-relapse deaths in MSD-HSCT were related to cGVHD (71%), whereas infectious complications were mainly related to NRM in Haplo-HSCT (50%) or Auto-HSCT (100%). In the MUD-HSCT, GVHD (57%) and infection (43%) contributed similarly to non-relapse death. Cytomegalovirus infection was more frequent in Haplo-HSCT. In multivariate models, pre-transplant MRD-positivity was an independent risk factor for relapse (P = .001), whereas older age (P = .002) and the hematopoietic cell transplantation-comorbidity index (P = .009) were useful in predicting NRM. The current study demonstrated comparable outcomes after alternative and matched sibling donor HSCT in eAML aged 60 years or older, and the results also suggest the necessity for more sophisticated strategies to reduce NRM or relapse according to each donor type. The usefulness of molecular MRD assays demonstrated herein will facilitate trials for MRD-driven decision-making or risk-adaptive approaches in eAML.

Haploidentical vs matched unrelated donor transplantation for acute myeloid leukemia in remission: A prospective comparative study

Despite comparable outcomes of haploidentical transplants (Haplo-HSCT) with HLA-matched unrelated transplants (MUD-HSCT) in retrospective comparisons, few studies have prospectively compared Haplo-HSCT with MUD-HSCT in AML. Here, we prospectively compared the outcomes of Haplo-HSCT with MUD-HSCT for AML in remission (n = 110) to prove non-inferiority of overall survival in Haplo-HSCT. Both groups were well balanced in factors related to biological features of AML and measurable residual disease (MRD) status by Wilms' tumor gene 1 (WT1) assay. A unique, reduced-toxicity preparative regimen was used for Haplo-HSCT, whereas mostly-myeloablative regimen was for MUD-HSCT. Both groups showed similar patterns of neutrophil and platelet recovery, whereas delayed T-cell reconstitution in Haplo-HSCT was found compared with MUD-HSCT. No significant differences were found in acute or chronic graft-vs-host-disease (GVHD) and post-transplant infectious events with an exception of EBV or CMV infection, which occurred more frequently in Haplo-HSCT. After a median follow-up of 47 months, no significant differences in overall survival (65% vs 54%, P = .146), disease-free survival (67% vs 53%, P = .142), relapse (20% vs 21%, P = .858), non-relapse mortality (14% vs 26%, P = .103), or GVHD-free/relapse-free survival (54% vs 41%, P = .138) were observed for Haplo-HSCT vs MUD-HSCT. In multivariate analysis, WT1 expression before transplantation independently predicted relapse, resulting in inferior survival. Separate analysis of unenrolled patients (n = 110) who were excluded or refused to participate in this study showed consistent results with enrolled patients. This prospective study demonstrated the non-inferiority of Haplo-HSCT to MUD-HSCT for AML in remission, and validated the role of WT1 quantification as an MRD marker (ClinicalTrial.gov identifier: NCT01751997).

Myeloablative Haploidentical Transplantation Is Superior to Chemotherapy for Patients with Intermediate-risk Acute Myelogenous Leukemia in First Complete Remission

PURPOSE

Although myeloablative HLA haploidentical hematopoietic stem cell transplantation (haplo-HSCT) following pretransplant anti-thymocyte globulin (ATG) and granulocyte colony-stimulating factor (G-CSF) stimulated grafts (ATG+G-CSF) has been confirmed as an alternative to HSCT from HLA-matched sibling donors (MSD), the effect of haplo-HSCT on postremission treatment of patients with acute myeloid leukemia (AML) with intermediate risk (int-risk AML) who achieved first complete remission (CR1) has not been defined.

PATIENTS AND METHODS

In this prospective trial, among 443 consecutive patients ages 16-60 years with newly diagnosed de novo AML with int-risk cytogenetics, 147 patients with molecular int-risk AML who achieved CR1 within two courses of induction and remained in CR1 at 4 months postremission either received chemotherapy (n = 69) or underwent haplo-HSCT (n = 78).

RESULTS

The 3-year leukemia-free survival (LFS) and overall survival (OS) were significantly higher in the haplo-HSCT group than in the chemotherapy group (74.3% vs. 47.3%; P = 0.0004 and 80.8% vs. 53.5%; P = 0.0001, respectively). In the multivariate analysis with propensity score adjustment, postremission treatment (haplo-HSCT vs. chemotherapy) was an independent risk factor affecting the LFS [HR 0.360; 95% confidence interval (CI), 0.163-0.793; P = 0.011], OS (HR 0.361; 95% CI, 0.156-0.832; P = 0.017), and cumulative incidence of relapse (HR 0.161; 95% CI, 0.057-0.459; P = 0.001) either in entire cohort or stratified by minimal residual disease after the second consolidation.

CONCLUSIONS

Myeloablative haplo-HSCT with ATG+G-CSF is superior to chemotherapy as a postremission treatment in patients with int-risk AML during CR1. Haplo-HSCT might be a first-line postremission therapy for int-risk AML in the absence of HLA-MSDs. Haplo-HSCT might be superior to chemotherapy as a first-line postremission treatment of intermediate-risk AML in CR1.