Haploidentical hematopoietic cell transplantation for adult acute myeloid leukemia: a position statement from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Current status of conditioning regimens in haploidentical hematopoietic cell transplantation

The development of effective prophylaxis strategies against graft-versus-host disease (GVHD) has contributed to the widespread use of haploidentical related hematopoietic cell transplantation (Haplo-HCT). Currently, GVHD prophylaxis containing posttransplant cyclophosphamide (PTCY) is considered the standard of care in Haplo-HCT, and recent studies have shown comparable results for PTCY-based Haplo-HCT and HCT from other donor sources. The conditioning regimen plays an important role in eradicating tumor cells to prevent disease relapse and suppressing the recipient's immune system to facilitate engraftment. PTCY-based Haplo-HCT was initially developed using a nonmyeloablative conditioning regimen consisting of fludarabine, cyclophosphamide and low-dose total body irradiation, but high relapse rates reinforced the need to intensify the conditioning regimen. In this respect, various myeloablative and reduced-intensity conditioning regimens have been investigated. However, the optimal conditioning regimens for PTCY-based Haplo-HCT have not yet been established, and this issue needs to be addressed based on data from patients undergoing the procedure. In this article, we review the existing literature on conditioning regimens for PTCY-based Haplo-HCT and discuss future perspectives.

Umbilical Cord Blood Hematopoietic Cells: From Biology to Hematopoietic Transplants and Cellular Therapies

Umbilical cord blood (UCB) is a rich source of hematopoietic stem and progenitor cells that are biologically superior to their adult counterparts. UCB cells can be stored for several years without compromising their numbers or function. Today, public and private UCB banks have been established in several countries around the world. After 35 years since the first UCB transplant (UCBT), more than 50,000 UCBTs have been performed worldwide. In pediatric patients, UCBT is comparable to or superior to bone marrow transplantation. In adult patients, UCB can be an alternative source of hematopoietic cells when an HLA-matched unrelated adult donor is not available and when a transplant is urgently needed. Delayed engraftment (due to reduced absolute numbers of hematopoietic cells) and higher costs have led many medical institutions not to consider UCB as a first-line cell source for hematopoietic transplants. As a result, the use of UCB as a source of hematopoietic stem and progenitor cells for transplantation has declined over the past decade. Several approaches are being investigated to make UCBTs more efficient, including improving the homing capabilities of primitive UCB cells and increasing the number of hematopoietic cells to be infused. Several of these approaches have already been applied in the clinic with promising results. UCB also contains immune effector cells, including monocytes and various lymphocyte subsets, which, together with stem and progenitor cells, are excellent candidates for the development of cellular therapies for hematological and non-hematological diseases.

Graft-versus-tumor effect of post-transplant cyclophosphamide-based allogeneic hematopoietic cell transplantation

Post-transplant cyclophosphamide (PTCy) is becoming the standard prophylaxis for graft-versus-host disease (GVHD) in HLA-haploidentical allogeneic hematopoietic cell transplantation (allo-HCT) and in HLA-matched allo-HCT. Immune reconstitution in the post-transplant setting may influence the graft-versus-tumor (GVT) effect because PTCy has a profound effect on T cell and natural killer cell functions and their reconstitution after allo-HCT. However, many recent studies have shown that the incidence of relapse after allo-HCT with PTCy is comparable to that after conventional allo-HCT. To further improve the outcomes, it is critical to establish a strategy to maintain or effectively induce the GVT effect when using PTCy as a platform for GVHD prophylaxis. However, there is a paucity of studies focusing on the GVT effect in allo-HCT with PTCy. Therefore, focusing on this issue may lead to the establishment of more appropriate strategies to improve transplantation outcomes without exacerbating GVHD, including novel therapies involving cell modification.

Strategies to reduce relapse risk in patients undergoing allogeneic stem cell transplantation for acute myeloid leukaemia

Allogeneic stem cell transplantation is a centrally important curative strategy in adults with acute myeloid leukaemia; however, relapse occurs in a significant proportion of patients and remains the leading cause of treatment failure. The prognosis for patients who relapse post-transplant remains poor, and the development of new strategies with the ability to reduce disease recurrence without increasing transplant toxicity remains a priority. In this review, within the context of our understanding of disease biology and the graft-versus-leukaemia (GVL) effect, we will discuss established, evolving and novel approaches for increasing remission rates, decreasing measurable residual disease pretransplant, future methods to augment the GVL effect and the opportunities for post-transplant maintenance. Future progress depends upon the development of innovative trials and networks, which will ensure the rapid assessment of emerging therapies in prospective clinical trials.

Comparison of allo-SCT, auto-SCT and chemotherapy for the treatment of patients with low- or intermediate-risk acute myeloid leukemia: a network meta-analysis

BACKGROUND

The therapeutic status of allogeneic stem cell transplantation (allo-SCT) as a post-remission treatment for patients with high-risk acute myeloid leukemia (AML) was well-accepted. However, the optimal treatment for patients with low/favorable- or intermediate-risk AML who achieve complete remission has remained controversial. Therefore, we conducted a network meta-analysis to discuss this disputed problem.

METHODS

We compared the effects of treatment strategies including allo-SCT, autologous stem cell transplantation (auto-SCT) and consolidation chemotherapy (CT) for patients with low/favorable- or intermediate-risk AML. The pooled HRs and 95% CIs for overall survival and disease-free survival were estimated with Stata12 and R software. Thirty clinical studies with 6682 patients were included in the meta-analysis.

RESULTS

The results indicated that the treatment outcome of allo-SCT was the best, followed by auto-SCT, and CT was likely the worst in the total AML patients. In patients with low/favorable-risk AML, the treatment outcome of auto-SCT was likely ranked first, followed by allo-SCT, and CT was the worst. In patients with intermediate-risk AML, the treatment outcome of haploidentical stem cell transplantation (haplo-SCT) was the best, followed by allo-SCT (excluding haplo-SCT), and auto-SCT and CT were the worst. However, the median age of the haplo-SCT group was much younger than that of the control group, which may be one of the reasons for the better prognosis of the haplo-SCT group.

CONCLUSIONS

Patients with low/favorable- and intermediate-risk (non-high-risk) AML should prioritize allo-SCT if they are eligible for transplantation, and auto-SCT is optional. However, in the subgroup analysis, auto-SCT was the optimal treatment choice for patients with low/favorable-risk AML, and allo-SCT was the priority selection for patients with intermediate-risk AML, especially young patients. These findings could provide references for clinical practice.

HLA Haplotypes and Relapse After Hematopoietic Cell Transplantation

PURPOSE

Recurrence of blood malignancy is the major cause of hematopoietic cell transplant failure. HLA class II molecules play a fundamental role in antitumor responses but the role of class II haplotypes is not known.

METHODS

HLA-DR, -DQ, -DM, and -DO allele variation was determined in 1,629 related haploidentical transplants to study the clinical significance of individual molecules and haplotypes.

RESULTS

Outcome correlated with patient and donor variation for HLA-DRβ residue 86 (Gly/Val), HLA-DQ (G1/G2) heterodimers, and donor HLA-DM (DM11,11/nonDM11,11) molecules, and depended on patient-donor mismatching. Risks of relapse were lower for DRβ-86 GlyGly patients when the donor was GlyVal (hazard ratio [HR], 0.46 [95% CI, 0.30 to 0.68]; P < .001); GlyVal patients benefited from HLA-DRB1-matched donors, whereas no donor was superior to another for ValVal patients. G1G2 patients with G1G2-mismatched donors had lower relapse. Transplantation from donors with DMα residue 184 ArgHis was associated with higher risk of relapse (HR, 1.60 [95% CI, 1.09 to 2.36]; P = .02) relative to ArgArg. Relapse and mortality risks differed across HLA-DR-DQ-DM haplotypes.

CONCLUSION

HLA class II haplotypes may be functional constituents of the transplantation barrier, and their consideration in patients and donors may improve the success of transplantation.

Haploidentical and Matched Sibling Transplantation for Acute Myeloid Leukemia: A Hospital-Based Study

Background

Allogeneic peripheral blood stem cell transplantation (PBSCT) has been increasing for the last years in Latin America. The objective of this study was to describe clinical outcomes in acute myeloid leukemia (AML) receiving allogeneic PBSCT between 2013 and 2019 in a single center of Cali, Colombia.

Methods

A retrospective cohort study was conducted in Fundacion Valle del Lili. Patients diagnosed with AML who received an allogeneic PBSCT between 2013 and 2019 using human leukocyte antigen (HLA)-matched sibling donors (MSDs) or haploidentical related donors (HRDs) with myeloablative conditioning regimen were included. Cases with diagnosis of promyelocytic leukemia, myelodysplastic syndrome-related AML and therapy-related AML were excluded. Data were obtained directly from the hospital PBSCT database and clinical records.

Results

A total of 50 patients were included (HRD, n = 32; MSD, n = 18). Sixty-two percent was in the first complete remission (CR1) at the time of the transplant, of which 26% were MSD and 74% were HRD. The European Group for Blood and Marrow Transplantation (EBMT) risk score was: 44% vs. 50% low, 28% vs. 28% intermediate and 28% vs. 22% high for MSD vs. HRD, respectively. Overall survival at 5 years for MSD was 62% (95% confidence interval (CI): 31-83%) and 43% (95% CI: 25-60%) for HRD. Event-free survival was 56% (95% CI: 26-78%) and 35.6% (95% CI: 18-53%), respectively. Non-relapse mortality at day-100 was 6% (95% CI: 0.8-35%) and 20% (95% CI: 9-39%). Relapse at5 years was 18% (95% CI: 4-58%) and 25% (95% CI: 10-52%). Overall mortality rate was 46%. The grade II-IV, III-IV acute graft-versus-host disease and severe chronic graft-versus-host disease was 44%, 11% and 12% for MSD, and 43%, 9% and 0% for HRD.

Conclusion

These results underline that MSD remains the first donor choice for AML patients in CR1 when available. HRDs are still our next option among alternative donors. It is necessary to find strategies that have a positive impact on those outcomes that markedly affect the quality of allogeneic PBSCT and the prognosis of patients. Comparative, randomized, prospective studies with longer follow-up of haploidentical allogeneic PBSCT with other donor types are required to definitely establish its role among alternative donors.

Transplantation Referral Patterns for Patients with Newly Diagnosed Higher-Risk Myelodysplastic Syndromes and Acute Myeloid Leukemia at Academic and Community Sites in the Connect® Myeloid Disease Registry: Potential Barriers to Care

Hematopoietic stem cell transplantation (HCT) is indicated for patients with higher-risk (HR) myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Age, performance status, patient frailty, comorbidities, and nonclinical factors (eg, cost, distance to site) are all recognized as important clinical factors that can influence HCT referral patterns and patient outcomes; however, the proportion of eligible patients referred for HCT in routine clinical practice is largely unknown. This study aimed to assess patterns of consideration for HCT among patients with HR-MDS and AML enrolled in the Connect® Myeloid Disease Registry at community/government (CO/GOV)- or academic (AC)-based sites, as well as to identify factors associated with rates of transplantation referral. We assessed patterns of consideration for and completion of HCT in patients with HR-MDS and AML enrolled between December 12, 2013, and March 6, 2020, in the Connect Myeloid Disease Registry at 164 CO/GOV and AC sites. Registry sites recorded whether patients were considered for transplantation at baseline and at each follow-up visit. The following answers were possible: "considered potentially eligible," "not considered potentially eligible," or "not assessed." Sites also recorded whether patients subsequently underwent HCT at each follow-up visit. Rates of consideration for HCT between CO/GOV and AC sites were compared using multivariable logistic regression analysis with covariates for age and comorbidity. Among the 778 patients with HR-MDS or AML enrolled in the Connect Myeloid Disease Registry, patients at CO/GOV sites were less likely to be considered potentially eligible for HCT than patients at AC sites (27.9% versus 43.9%; P < .0001). Multivariable logistic regression analysis with factors for age (<65 versus ≥65 years) and ACE-27 comorbidity grade (<2 versus ≥2) showed that patients at CO/GOV sites were significantly less likely than those at AC sites to be considered potentially eligible for HCT (odds ratio, 1.6, 95% confidence interval, 1.1 to 2.4; P = .0155). Among patients considered eligible for HCT, 45.1% (65 of 144) of those at CO/GOV sites and 35.7% (41 of 115) of those at AC sites underwent transplantation (P = .12). Approximately one-half of all patients at CO/GOV (50.1%) and AC (45.4%) sites were not considered potentially eligible for HCT; the most common reasons were age at CO/GOV sites (71.5%) and comorbidities at AC sites (52.1%). Across all sites, 17.4% of patients were reported as not assessed (and thus not considered) for HCT by their treating physician (20.7% at CO/GOV sites and 10.7% at AC sites; P = .0005). These findings suggest that many patients with HR-MDS and AML who may be candidates for HCT are not receiving assessment or consideration for transplantation in clinical practice. In addition, treatment at CO/GOV sites and age remain significant barriers to ensuring that all potentially eligible patients are assessed for HCT.

Correlative factors of ocular surface lesions after allogeneic hematopoietic stem cell transplantation: A retrospective study

BACKGROUND

Ocular graft-versus-host disease (oGVHD) is one of the complications after allogeneic hematopoietic stem cell transplantation (HSCT), which impairs the quality of life and may indicate poor prognosis. In this retrospective study, the aim was to investigate the characteristics of ocular surface after HSCT, and analyze the risk factors related to the severity of ocular surface lesions.

METHODS

248 post-HSCT patients were enrolled in this retrospective study. Subjects were divided into no lesion group, mild lesion group and severe lesion group, according to the severity of ocular surface lesions. The correlations between grades of ocular surface lesions and gender, age, primary disease, donor source, human leukocyte antigen (HLA) type, kinship, donor-recipient relationship, blood type, source of stem cell and systemic GVHD were analyzed.

RESULTS

The median scores of corneal epitheliopathy, lid margin lesions and meibomian gland loss were 3, 6 and 2 points, respectively. The grade of corneal epitheliopathy was related to donor source (P<0.001), kinship (P=0.033), HLA-matching (P<0.001), and systemic GVHD (P=0.007), especially oral GVHD (P<0.001) and liver GVHD (P=0.002). The grade of lid margin lesions was related to donor source (P=0.019), HLA-matching (P=0.006), and systemic GVHD (P=0.013), especially skin GVHD (P=0.019) and oral GVHD (P=0.019). The grade of meibomian gland loss was related to age (P=0.035) and gastrointestinal GVHD (P=0.007). The grade of corneal epitheliopathy after HSCT was related to the lid margin lesion score (P<0.001).

CONCLUSIONS

The occurrence and development of ocular GVHD are mostly accompanied by the history of systemic GVHD. While in few cases, ocular surface lesions related to GVHD can be observed prior to the rejection of other tissues and organs. Severe corneal epitheliopathy occurs in patients with severe lid margin lesions in ocular GVHD. The lesions of corneal epithelium and lid margin are milder in HLA partially matching transplantation.

Systematic overview of HLA-matched allogeneic hematopoietic cell transplantation with post-transplantation cyclophosphamide

The successful application of post-transplantation cyclophosphamide (PTCy) as graft-versus-host disease (GVHD) prophylaxis in HLA-haploidentical allogeneic hematopoietic cell transplantation (allo-HCT) led to the expansion of its application to HLA-matched related and unrelated allo-HCT. Notably, single-agent PTCy was found to be feasible for GVHD prevention in HLA-matched bone marrow transplantation. Single-agent PTCy prophylaxis was later attempted to control GVHD in HLA-matched peripheral blood stem cell transplantation (PBSCT), but this approach was inadequate to alleviate GVHD as evidenced by the high incidence of severe GVHD and/or non-relapse mortality. Therefore, various combinations of immunosuppressants with PTCy have been explored to identify the optimal drug combination that would efficiently prevent GVHD in HLA-matched PBSCT. A recent murine study helped clarify the putative mechanism underlying the activity of PTCy, demonstrating that PTCy impairs the proliferation and function of alloreactive T cells from the donor, but does not eliminate alloreactive T cells altogether. In addition, imbalanced reconstitution of NK cell as well as T cells has been observed in HLA-haploidentical allo-HCT. Therefore, it remains unclear whether or not PTCy-containing GVHD prophylaxis should replace the classical GVHD prophylaxis regimen in the HLA-matched setting, and convincing evidence supporting the benefits of PTCy is needed.

Low-dose post-transplant cyclophosphamide with low-dose antithymocyte globulin for prevention of graft-versus-host disease in first complete remission undergoing 10/10 HLA-matched unrelated donor peripheral blood stem cell transplants: a multicentre, randomized controlled trial

The most widely used regimens of graft-versus-host disease (GVHD) prophylaxis in HLA-matched unrelated donor peripheral blood stem cell transplantation (MUD-PBSCT) are based on anti-thymocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy). To improve the efficiency of GVHD prophylaxis, a novel regimen, composed of low-dose PTCy (20 mg/kg on day +3 and +4) and low-dose ATG (6 mg/kg), was evaluted in patients with hematological malignancies ungoing 10/10 HLA MUD-PBSCT in first remission (CR1). In our prospective, multicenter study, 104 patients were randomly assigned one-to-one to low-dose PTCy-ATG (n = 53) or standard-dose ATG (10 mg/kg, n = 51). Both the cumulative incidences (CIs) of grade II-IV acute GVHD (aGVHD) and chronic GVHD (cGVHD) at 2 years in low-dose PTCy-ATG cohort were significantly reduced (24.5% vs. 47.1%; P = 0.017; 14.1% vs. 33.3%; P = 0.013). The CI of non-relapse-mortality (NRM) was much lower (13.2% vs. 34.5%; P = 0.049) and GVHD-free, relapse-free survival (GRFS) was significantly improved at 2 years in low-dose PTCy-ATG arm (67.3% vs 42.3%; P = 0.032). The low-dose PTCy-ATG based GVHD prophylaxis is a promising strategy for patients in CR1 after 10/10 HLA MUD-PBSCT.

Outcomes of haploidentical peripheral stem cell transplantation with combination of post-transplant cyclophosphamide (PTCy) and anti-thymocyte globulin (ATG) compared to unrelated donor transplantation in acute myeloid leukemia: A retrospective 10-year experience

In the evolution of haploidentical hematopoietic stem cell transplantation (haplo-HSCT), In vivo T-cell modulation with concomitant use of anti-thymocyte globulin (ATG) and high-dose post-transplant cyclophosphamide (PTCy) provides a novel promising method on transplant outcomes; however, the long-term effects of this therapy are mostly unknown. We retrospectively compared the long-term outcomes of adult acute myeloid leukemia (AML) patients undergoing a haplo-HSCT (n = 92) with a new modified combination of ATG and PTCy in the context of peripheral blood stem cell (PBSC) and myeloablative conditioning (MAC) with an otherwise similar group of AML patients who received an unrelated donor (URD) HSCT (n = 57) with ATG protocol from February 2010 to December 2020 at our single-center (HORCSCT). Median follow-up was 3.73 and 4.28 years for haploidentical and URD-HSCT, respectively. In haplo-HSCT, the cumulative incidence of grades II-IV and III-IV acute graft versus host disease (aGvHD) and extensive chronic GvHD (cGvHD) was much lower than in URD (27% versus 56% for grades II-IV, 8.7% versus 24.5% for grades III-IV, and 15.4% versus 34.7% for extensive cGvHD, respectively). Five-year overall survival (OS) was 54.03% for haplo and 54.48% for URD (p = 0.927); GvHD-free relapse-free survival (GRFS) was 44.1% and 29.86% (p = 0.149); relapse incidence was 15.79% and 26.95% (p = 0.72); and non-relapse mortality (NRM) was 29.48% and 26.32% (p = 0.73), respectively. Using multivariable analyses, when compared to Haplo, URD was a significant predictor of relapse (HR=1.80, p = 0.039); however, no difference in OS, GRFS, and NRM was noted between haplo and URD. Therefore, given the favorable results with haplo-HSCT and considering donor availability promptly with low cost, it conservatively suggested that haplo-HSCT with the introduced protocol could be viewed as the first alternative for patients with AML in the absence of matched sibling donors.

Depth of Response to Intensive Chemotherapy Has Significant Prognostic Value among Acute Myeloid Leukemia (AML) Patients Undergoing Allogeneic Hematopoietic Stem-Cell Transplantation with Intermediate or Adverse Risk at Diagnosis Compared to At-Risk Group According to European Leukemia Net 2017 Risk Stratification

We evaluated the prognostic efficiency of the European Leukemia Net (ELN) 2017 criteria on the post-transplant outcomes of 174 patients with intermediate (INT; n = 108, 62%) or adverse (ADV) risk (n = 66, 38%) of acute myeloid leukemia; these patients had received the first allogeneic hematopoietic stem-cell transplantation (HSCT) at remission. After a median follow-up period of 18 months, the 2 year OS, RFS, and CIR after HSCT were estimated to be 58.6% vs. 64.4% (p = 0.299), 50.5% vs. 53.7% (p = 0.533), and 26.9% vs. 36.9% (p = 0.060) in the INT and ADV risk groups, respectively. Compared to the ELN 2017 stratification, pre-HSCT WT1 levels (cutoff: 250 copies/104 ABL) more effectively segregated the post-HSCT outcomes of INT risk patients compared to ADV risk patients regarding their 2 year OS (64.2% vs. 51.5%, p = 0.099), RFS (59.4% vs. 32.4%, p = 0.003), and CIR (18.9% vs. 60.0% p < 0.001). Indeed, high WT1 levels were more prominent in INT risk patients than in ADV risk patients. Notably, FLT3-ITD had the greatest impact on post-HSCT outcomes among all the ELN 2017 criteria components; patients in the FLT3-ITD mutant subgroups exhibited the worst outcomes regardless of their allelic ratios or NPM1 status compared to the pre-HSCT WT1 level of other INT and ADV risk patients.

Hematopoiesis reconstitution and anti-tumor effectiveness of Pai-Neng-Da capsule in acute leukemia patients with haploidentical hematopoietic stem cell transplantation

BACKGROUND

With the rapid development of haploidentical hematopoietic stem cell transplantation (haplo-HSCT), primary poor graft function (PGF) has become a life-threatening complication. Effective therapies for PGF are inconclusive. New Chinese patent medicine Pai-Neng-Da (PND) Capsule exerts dual effect in promoting hematopoiesis recovery and regulating immunity. Still, the application of PND capsule in hematopoietic stem cell transplantation, especially in the haplo-HSCT setting, has not yet been reported.

AIM

To evaluate the role of PND capsule in acute leukemia patients with haplo-HSCT.

METHODS

We retrospectively collected data of acute leukemia patients who underwent haplo-HSCT at the Affiliated People’s Hospital of Ningbo University between April 1, 2015 and June 30, 2020. Twenty-nine consecutive patients received oral PND capsule from the sixth day to the first month after haplo-HSCT were included in the PND group. In addition, 31 patients who did not receive PND capsule during haplo-HSCT were included in the non-PND group. Subsequently, we compared the therapeutic efficacy according to the western medical evaluation indexes and Chinese medical symptom scores, and the survival between the PND group and the non-PND group, using the chi-square test, Fisher’s exact test, and the Kaplan–Meier method.

RESULTS

The duration of platelet engraftment was shorter in the PND group than in the non-PND group (P = 0.039). The PND group received a lower frequency of red blood cells and platelet transfusions than the non-PND group (P = 0.033 and P = 0.035, respectively). In addition, PND capsule marginally reduced the rate of PGF (P = 0.027) and relapse (P = 0.043). After 33 (range, 4-106) months of follow-up, the 3-year relapse-free survival (P = 0.046) and progression-free survival (P = 0.049) were improved in the PND group than in the non-PND group. Also, the therapeutic efficacy of the PND group according to Chinese medical symptom scores was significantly better than that of the non-PND group (P = 0.022). Moreover, the adverse events caused by PND capsule were mild. Nevertheless, there were no significant differences in the duration of neutrophil engraftment, the risk of infection within 100 days after haplo-HSCT, the acute graft-versus-host disease, or the 3-year overall survival between the two groups.

CONCLUSION

PND capsule could promote hematopoiesis reconstitution, improve the therapeutic efficacy of Chinese medical symptom scores, present anti-tumor effectiveness, and prolong the survival of acute leukemia patients with haplo-HSCT.

Post-transplant cyclophosphamide in one-antigen mismatched unrelated donor transplantation versus haploidentical transplantation in acute myeloid leukemia: a study from the Acute Leukemia Working Party of the EBMT

Whether to choose Haploidentical (Haplo) or one-antigen mismatched unrelated donor (1Ag-MMUD) hematopoietic cell transplantation (HCT) with post-transplant cyclophosphamide (PTCy) remains an unanswered question. We compared PTCy- Haplo-HCT to PTCy-1Ag-MMUD-HCT for acute myeloid leukemia (AML) in complete remission (three groups: 1Ag-MMUD using peripheral blood (1Ag-MMUD-PB; n = 155); Haplo using bone marrow (Haplo-BM; n = 647) or peripheral blood (Haplo-PB; n = 949)). Haplo-BM and Haplo-PB had a higher non-relapse mortality (NRM) compared to 1Ag-MMUD-PB (HR 2.28, 95% CI 1.23-4.24, p < 0.01; HR 2.65, 95% CI 1.46-4.81, p < 0.01, respectively). Haplo groups experienced a lower leukemia-free survival (LFS) compared to 1Ag-MMUD-PB (Haplo-BM: HR 1.51, 95% CI 1.06-2.14, p = 0.02; Haplo-PB: 1.47, 95% CI 1.05-2.05, p = 0.02); overall survival (OS) was also lower in Haplo-HCT (Haplo-BM: HR 1.50, 95% CI 1.02-2.21, p = 0.04; Haplo-PB: HR 1.51, 95% CI 1.05-2.19, p = 0.03). No differences were observed for graft-versus-host/relapse-free survival (GRFS) and relapse incidence (RI). Haplo-BM was associated with a lower risk of grade III-IV acute graft-versus-host disease (GVHD) (HR 0.44, 95% CI 0.24-0.81; p < 0.01), while no statistical differences were observed between groups for grade II-IV aGVHD and for cGVHD. Use of PTCy in 1Ag-MMUD-HCT is a valid alternative to consider when using alternative donors. Larger analysis of 1Ag-MMUD versus Haplo-HCT are warranted.

A Prospective Study of an HLA-Haploidentical Peripheral Blood Stem Cell Transplantation Regimen Based on Modification of the Dose of Posttransplant Cyclophosphamide for Poor Prognosis or Refractory Hematological Malignancies

The optimal dose of posttransplant cyclophosphamide (PTCy) for use in patients undergoing HLA-haploidentical hematopoietic cell transplantation with posttransplant cyclophosphamide (PTCy-haplo) has not been sufficiently examined. This study evaluates the safety and efficacy of HLA-haploidentical hematopoietic cell transplantation with a reduced dose of PTCy for patients with a poor prognosis or those with refractory hematological malignancies. We conducted a prospective clinical study of PTCy-haplo with peripheral blood stem cells (PBSCs) using a modified PTCy dosage regimen consisting of 50 mg/kg on day 3 posttransplantation and a reduced dose of 25 mg/kg on day 4. The cumulative incidences of grades II to III and IV acute graft-versus-host disease (GVHD) at day 100 posttransplantation were 30% and 0%, respectively. The cumulative incidence of moderate-to-severe chronic GVHD after transplantation was 7.0%. The cumulative incidence of nonrelapse mortality at 1 year posttransplantation was 6.1%. Overall survival (OS) at 1 year was 66%. In addition, the restricted cubic-spline Cox regression analysis showed nonlinear relationship between the number of infused CD34⁺ cells and CD3⁺ cells, and OS. A graft composition of >4.54 × 10⁶/kg CD34⁺ cells and >1.85 × 10⁸/kg but ≤3.70 × 10⁸/kg CD3⁺ cells was significantly associated with better survival, irrespective of the disease status (hazard ratio, 0.13; 95% confidence interval, 0.04–0.41; P < 0.001). These results suggest that PTCy-haplo with PBSCs using a de-escalated dose of 50 mg/kg on day 3 and 25 mg/kg on day 4 posttransplantation is a feasible option.

Haploidentical Hematopoietic Stem Cell Transplant Using Post-transplant Cyclophosphamide: A Single-Center Initial Experience in Vietnam

AIMS AND OBJECTIVES

Haploidentical transplants constitute a potential alternative therapy for patients who urgently need transplantation in the absence of human leukocyte antigen-matched donors. We report a single-center experience regarding the initial results of haploidentical peripheral blood stem cell transplantation (haplo-PBSCT) using post-transplant cyclophosphamide (PTCy) at the HCMC Blood Transfusion Hematology (BTH) Hospital.

METHODS

We conducted a retrospective case series study of 23 patients who underwent haplo-PBSCT using PTCy at the HCMC BTH Hospital between January 2014 and January 2021. The refined disease risk index (DRI) was used to stratify the outcomes. We evaluated the engraftment rate, graft-versus-host disease (GVHD), and complications during haploidentical transplantation. Overall survival (OS), disease-free survival (DFS), and GVHD-free relapse-free survival (GRFS) were assessed.

RESULTS

The majority of the patients in the present study were diagnosed with acute myeloid leukemia. All patients received reduced-intensity conditioning regimens. The engraftment rate was 86.9%. The median times to neutrophil and platelet engraftment were 17 and 31 days, respectively. Two patients (8.7%) reported severe acute GVHD (grade III-IV), while two patients (8.7%) had grade I-II acute GVHD. Three patients experienced limited chronic GVHD of the skin, requiring topical steroids. The most common complication was bloodstream infection (60.9%). Cytomegalovirus reactivation occurred in 19 patients (82.6%) and 17.4% developed hemorrhagic cystitis. The 1-year relapse rate was 32.5%. The cumulative incidence of non-relapse mortality at 1 year was 17.3%. The 1-year OS and DFS rates were 66.3% and 55.7%, respectively. The 1-year GRFS rate was 49.2%. A high/very high DRI score was associated with worse OS after haplo-PBSCT (P=0.038).

CONCLUSION

Haploidentical transplant using PTCy is a feasible therapy for patients without suitably matched donors in Vietnam. Infection after transplantation remains a challenge and requires effective management.

Haploidentical Stem Cell Transplantation for Acute Myeloid Leukemia: Current Therapies, Challenges and Future Prospective

Haploidentical stem cell transplantation (haplo-SCT), an alternative donor source, offers a curative therapy for patients with acute myeloid leukemia (AML) who are transplant candidates. Advances in transplantation techniques, such as donor selection, conditioning regimen modification, and graft-versus-host disease prophylaxis, have successfully improved the outcomes of AML patients receiving haplo-SCT and extended the haploidentical transplant indictions for AML. Presently, treating de novo AML, secondary AML, therapy-related AML and refractory and relapsed AML with haplo-SCT can achieve comparable outcomes to those of human leukocyte antigen (HLA)-matched sibling donor transplantation (MSDT), unrelated donor transplantation or umbilical cord blood transplantation. For some subgroups of AML subjects, such as patients with positive pretransplantation minimal/measurable residual disease, recent studies suggest that haplo-SCT might be superior to MSDT in decreasing relapse and improving survival. Unfortunately, for patients with AML after haplo-SCT, relapse and infections remain the causes of death that restrict further improvement in clinical outcomes. In this review, we discuss the recent advances and challenges in haplo-SCT for AML treatment, mainly focusing on unmanipulated haplo-SCT protocols. We provide an outlook on future prospects and suggest that relapse prophylaxis, intervention, and treatment, as well as infection prevention and therapy, are areas of active research in AML patients who receive haploidentical allografts.

A phase II study of post-transplant cyclophosphamide combined with tacrolimus for GVHD prophylaxis after HLA-matched related/unrelated allogeneic hematopoietic stem cell transplantation

A combination of three post-transplant drugs, cyclophosphamide (PTCy), a calcineurin inhibitor, and mycophenolate mofetil, has long been used for prophylaxis of graft-versus-host-disease (GVHD) after HLA-haploidentical allogeneic hematopoietic cell transplantation (allo-HCT). Recently, this combination has been used following HLA-matched allo-HCT as well, but the optimal combination of drugs for GVHD prophylaxis in an HLA-matched setting remains unclear. This prospective phase II study evaluated the safety and efficacy of PTCy plus tacrolimus (TAC) for GVHD prophylaxis after allo-HCT from HLA-matched related donors (MRD) or HLA-matched unrelated donors (MUD). The cumulative incidences of grades II-IV and III-IV acute GVHD at 100 days post-transplantation were 18% and 5.9%, respectively, in the MRD group, and 18% and 9.1%, respectively, in the MUD group. The cumulative incidences of moderate to severe chronic GVHD at 1 year were 12% and 9.1% in the MRD and MUD groups, respectively. The 1-year overall survival rates in the MRD and MUD groups were 88% and 64%, respectively, and the 1-year GVHD-free, relapse free survival rates were 59% and 50%, respectively. These results suggest that GVHD prophylaxis with a less intensive double drug combination (PT/Cy and TAC) might be feasible after HLA-matched allo-HCT.Clinical Trial Notation This trial was a prospective single-center trial registered at the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR; identification number: UMIN000023890) and the Japan Registry of Clinical Trials (jRCTs051180143).

NEOVASCULAR COMPLICATIONS FROM CYTOMEGALOVIRUS NECROTIZING RETINOPATHY IN PATIENTS AFTER HAPLOIDENTICAL HEMATOPOIETIC STEM CELL TRANSPLANTATION

PURPOSE

To report the incidence and clinical features of neovascular complications from cytomegalovirus (CMV) necrotizing retinopathy in patients after haploidentical hematopoietic stem cell transplantation.

METHODS

Thirty-nine patients (58 eyes) of CMV necrotizing retinopathy after haploidentical hematopoietic stem cell transplantation in our institute between January 2018 and June 2020 were retrospectively reviewed, and cases that developed neovascular complications during follow-up were identified and described.

RESULTS

Two (2 eyes) cases that developed neovascular glaucoma from CMV necrotizing retinopathy were identified. Both of them manifested as granular peripheral retinitis, panretinal occlusive vasculitis, and some degree of intraocular inflammation, which were consistent with chronic retinal necrosis. Insidious progression of isolated immune-mediated occlusive vasculitis that could only be observed on fundus fluorescein angiography without active retinitis or intraocular inflammation was recognized to be the cause in one of two cases.

CONCLUSION

Neovascular glaucoma developed in 5.1%/cases and 3.4%/eyes complicated by CMV chronic retinal necrosis and vasculitis in patients after haploidentical hematopoietic stem cell transplantation, which warrants the needs for long-term follow-up. Immune-mediated CMV vasculitis could be an isolated manifestation in patients with a minimal immune deviation and may only be found on fundus fluorescein angiography, which emphasizes the importance of fundus fluorescein angiography on a regular basis during follow-up.

Is it time to reconsider prophylactic antimicrobial use for hematopoietic stem cell transplantation? a narrative review of antimicrobials in stem cell transplantation

INTRODUCTION

Hematopoietic Stem Cell Transplantation (HSCT) is a life-saving procedure for multiple types of hematological cancer, autoimmune diseases, and genetic-linked metabolic diseases in humans. Recipients of HSCT transplant are at high risk of microbial infections that significantly correlate with the presence of graft-versus-host disease (GVHD) and the degree of immunosuppression. Infection in HSCT patients is a leading cause of life-threatening complications and mortality.

AREAS COVERED

This review covers issues pertinent to infection in the HSCT patient, including bacterial and viral infection; strategies to reduce GVHD; infection patterns; resistance and treatment options; adverse drug reactions to antimicrobials, problems of antimicrobial resistance; perturbation of the microbiome; the role of prebiotics, probiotics, and antimicrobial peptides. We highlight potential strategies to minimize the use of antimicrobials.

EXPERT OPINION

Measures to control infection and its transmission remain significant HSCT management policy and planning issues. Transplant centers need to consider carefully prophylactic use of antimicrobials for neutropenic patients. The judicious use of appropriate antimicrobials remains a crucial part of the treatment protocol. However, antimicrobials' adverse effects cause microbiome diversity and dysbiosis and have been shown to increase morbidity and mortality.

Immunomodulatory Effects of Bendamustine in Hematopoietic Cell Transplantation

Bendamustine (BEN) is a unique alkylating agent with efficacy against a broad range of hematological malignancies, although investigations have only recently started to delve into its immunomodulatory effects. These immunomodulatory properties of BEN in the context of hematopoietic cell transplantation (HCT) are reviewed here. Pre- and post-transplant use of BEN in multiple murine models have consistently resulted in reduced GvHD and enhanced GvL, with significant changes to key immunological cell populations, including T-cells, myeloid derived suppressor cells (MDSCs), and dendritic cells (DCs). Further, in vitro studies find that BEN enhances the suppressive function of MDSCs, skews DCs toward cDC1s, enhances Flt3 expression on DCs, increases B-cell production of IL-10, inhibits STAT3 activation, and suppresses proliferation of T- and B-cells. Overall, BEN has a broad range of immunomodulatory effects that, as they are further elucidated, may be exploited to improve clinical outcomes. As such, clinical trials are currently underway investigating new potential applications of BEN in the setting of allogeneic HCT.

Impact of access to care on 1-year mortality following allogeneic blood or marrow transplantation

Mortality is highest in the first year following an allogeneic hematopoietic stem cell transplant. With recent advancements, we have expanded the pool of patients to whom we are able to offer transplant as a treatment option. In this context, we analyzed socioeconomic, patient, disease and transplant-related variables that predicted for 1-year all-cause, relapse-related (RRM) and non-relapse related mortality (NRM) in 304 patients at the University of Alabama at Birmingham. The 1-year overall survival, RRM and NRM rates were 60.5%, 13.5% and 22.7% respectively. A KPS score < 80, pre-transplant infection and hypertension and non-complete remission disease status adversely effected all-cause mortality. For NRM, increasing age, pre-transplant infection and diabetes, and poor access to care were associated with higher mortality whereas haploidentical donor type was associated with improved survival. For RRM, a KPS score <80, high/very high disease risk index and the presence of comorbidities were risk factors for higher mortality. Poor access to care, in addition to individual comorbidities, performance status and high-risk disease characteristics, is associated with adverse outcomes following transplant. We propose the incorporation of socioeconomic variables with patient, disease, and transplant-related variables to predict 1-year NRM.

NK cell alloreactivity in acute myeloid leukemia in the post-transplant cyclophosphamide era

Allogeneic hematopoietic stem cell transplantation (alloSCT) for myeloid leukemia remains one of the most effective anti-tumor treatments available, capable of curing an increasingly higher proportion of patients. Alloreactivity generated by T cells has limited efficacy in the early post-transplant period while most patients will relapse within 6 months after transplantation. Prior studies in T cell depleted grafts showed that, with the elimination of T cells, natural killer (NK) cells provide most of the anti-tumor effect in the early post-transplant period. Administration of unmodified T cells to mitigate infections and relapse will expose the patient to a high risk of graft-vs-host disease (GvHD). Post-transplant cyclophosphamide (PTCy), initially used for haploidentical (haplo) donor transplants, is now also increasingly utilized in HLA matched donor transplants to prevent GvHD. In most patients, PTCy eliminates, at least in part, alloreactive T and NK cells early post-transplant. Administration of modified NK cells in the early post-transplant period makes intuitive sense to enhance the anti-tumor effect of the graft and thereby prevent relapse. Effective application of cellular therapy early after transplant has opened a new direction and could revolutionize the field of hematopoietic stem cell transplantation.

Haploidentical stem cell transplantation (HaploSCT) for patients with acute leukemia-an update on behalf of the ALWP of the EBMT

Allogeneic stem cell transplantations (alloSCT) from haploidentical (>2 HLA mismatch) donors (HaploSCT) are constantly increasing in Europe. From 2005 to 2015 numbers of HaploSCT increased by close to 300%. In parallel, there is a major shift from T deplete (CD34+ megadose) to T replete (non-T deplete) HaploSCT. Graft versus host disease (GVHD) prophylaxis also changed from CD34+ cell purifications to anti-thymocyte globulin (ATG) and lately to post-transplantation cyclophosphamide (PTCy). Novel conditioning regimens have been developed incorporating novel drugs and innovative approaches. Results are persistently improving and currently, registry-based and single-center studies showed no statistical significance difference in transplantation outcome between HaploSCT to alloSCT from unrelated donors and even from HLA-matched sibling donors, although the numbers of those studies are small and the lack of randomized studies available so far. HaploSCT have several advantages and such as the possibility to choose between different potential donors. Parameters to consider in the Haplo donor selection are age, gender, kinship, ABO blood group, CMV status, non-shared HLA Haplotypes and killer cell immunoglobulin-like receptor (KIR). Future goals are to further decrease transplant-related mortality currently mainly due to infection complications and reduce relapse rates especially in patients with high-risk acute leukemia.

Evolution of the role of haploidentical stem cell transplantation: past, present, and future

INTRODUCTION

The accessibility to haplo-donors has led to an increase in the number of haplo-HSCT worldwide. A systematic search of the PubMed database between 2000 to present was performed.

AREAS COVERED

In this review, the authors discussed the most used approaches to perform haplo-HSCT and its results: T-cell depletion (TCD, including Perugia platform and its modifications) and T-cell repleted haplo (TCR, including the high-dose post-transplant cyclophosphamide strategy (Baltimore protocol) and the Beijing protocol). The improvements and modifications made to the different strategies have increased the indications of haplo-HSCT, including both malignant and nonmalignant disorders. Focusing on the Baltimore protocol, the authors review the results of the retrospective studies that have compared it to other donor transplants. The limitations of this strategy in terms of toxicity, graft complications, and GVHD are also discussed in detail. Finally, possible approaches to improve the outcomes of TCR haplo-HSCT are presented.

EXPERT OPINION

The recent advances in the field of haplo-HSCT have allowed a large number of patients with incurable diseases to benefit from this procedure despite not having a matched donor. With all available strategies, virtually no patient who needs an allogeneic transplant should be excluded by the absence of a donor.

Pediatric Aggressive Mature B-Cell Lymphomas, Version 2.2020, NCCN Clinical Practice Guidelines in Oncology

Pediatric aggressive mature B-cell lymphomas are the most common types of non-Hodgkin lymphoma in children, and they include Burkitt lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL). These diseases are highly aggressive but curable, the treatment is complex, and patients may have many complicated supportive care issues. The NCCN Guidelines for Pediatric Aggressive Mature B-Cell Lymphomas provide guidance regarding pathology and diagnosis, staging, initial treatment, disease reassessment, surveillance, therapy for relapsed/refractory disease, and supportive care for clinicians who treat sporadic pediatric BL and DLBCL.

Identification of relapse-associated gene mutations by next-generation sequencing in low-risk acute myeloid leukaemia patients

Recommended genetic categorization of acute myeloid leukaemias (AML) includes a favourable-risk category, but not all these patients have good prognosis. Here, we used next-generation sequencing to evaluate the mutational profile of 166 low-risk AML patients: 30 core-binding factor (CBF)-AMLs, 33 nucleophosmin (NPM1)-AMLs, 4 biCEBPα-AMLs and 101 acute promyelocytic leukaemias (APLs). Functional categories of mutated genes differed among subgroups. NPM1-AMLs showed frequent variations in DNA-methylation genes (DNMT3A, TET2, IDH1/2) (79%), although without prognostic impact. Within this group, splicing-gene mutations were an independent factor for relapse-free (RFS) and overall survival (OS). In CBF-AML, poor independent factors for RFS and OS were mutations in RAS pathway and cohesin genes, respectively. In APL, the mutational profile differed according to the risk groups. High-risk APLs showed a high mutation rate in cell-signalling genes (P = 0·002), highlighting an increased incidence of FLT3 internal tandem duplication (ITD) (65%, P < 0·0001). Remarkably, in low-risk APLs (n = 28), NRAS mutations were strongly correlated with a shorter five-year RFS (25% vs. 100%, P < 0·0001). Overall, a high number of mutations (≥3) was the worst prognostic factor RFS (HR = 2·6, P = 0·003). These results suggest that gene mutations may identify conventional low-risk AML patients with poor prognosis and might be useful for better risk stratification and treatment decisions.

Key Aspects of the Immunobiology of Haploidentical Hematopoietic Cell Transplantation

Hematopoietic stem cell transplantation from a haploidentical donor is increasingly used and has become a standard donor option for patients lacking an appropriately matched sibling or unrelated donor. Historically, prohibitive immunological barriers resulting from the high degree of HLA-mismatch included graft-vs.-host disease (GVHD) and graft failure. These were overcome with increasingly sophisticated strategies to manipulate the sensitive balance between donor and recipient immune cells. Three different approaches are currently in clinical use: (a) ex vivo T-cell depletion resulting in grafts with defined immune cell content (b) extensive immunosuppression with a T-cell replete graft consisting of G-CSF primed bone marrow and PBSC (GIAC) (c) T-cell replete grafts with post-transplant cyclophosphamide (PTCy). Intriguing studies have recently elucidated the immunologic mechanisms by which PTCy prevents GVHD. Each approach uniquely affects post-transplant immune reconstitution which is critical for the control of post-transplant infections and relapse. NK-cells play a key role in haplo-HCT since they do not mediate GVHD but can successfully mediate a graft-vs.-leukemia effect. This effect is in part regulated by KIR receptors that inhibit NK cell cytotoxic function when binding to the appropriate HLA-class I ligands. In the context of an HLA-class I mismatch in haplo-HCT, lack of inhibition can contribute to NK-cell alloreactivity leading to enhanced anti-leukemic effect. Emerging work reveals immune evasion phenomena such as copy-neutral loss of heterozygosity of the incompatible HLA alleles as one of the major mechanisms of relapse. Relapse and infectious complications remain the leading causes impacting overall survival and are central to scientific advances seeking to improve haplo-HCT. Given that haploidentical donors can typically be readily approached to collect additional stem- or immune cells for the recipient, haplo-HCT represents a unique platform for cell- and immune-based therapies aimed at further reducing relapse and infections. The rapid advancements in our understanding of the immunobiology of haplo-HCT are therefore poised to lead to iterative innovations resulting in further improvement of outcomes with this compelling transplant modality.

Current Status and Future Directions in Graft-Versus-Host Disease Prevention Following Allogeneic Blood and Marrow Transplantation in Adults

Graft-versus-host disease (GvHD) in its acute and chronic forms continues to represent a significant barrier to the success and wide-applicability of blood and marrow transplantation as a potentially curative treatment modality for a number of benign and malignant blood conditions. Presently, calcineurin inhibitor (CNI)-based regimens remain the most commonly used prevention strategy, although post-transplant cyclophosphamide is emerging as an alternative approach, and is providing a backbone for innovative CNI-free combinations. In this paper, we review the current strategies used for the prevention of GvHD, and highlight some of the developing and promising combinations.

Immunological and Clinical Impact of Manipulated and Unmanipulated DLI after Allogeneic Stem Cell Transplantation of AML Patients

Allogeneic stem cell transplantation (allo-SCT) is the preferred curative treatment for several hematological malignancies. The efficacy of allo-SCT depends on the graft-versus-leukemia (GvL) effect. However, the prognosis of patients with relapsed acute myeloid leukemia (AML) following allo-SCT is poor. Donor lymphocyte infusion (DLI) is utilized after allo-SCT in this setting to prevent relapse, to prolong progression free survival, to establish full donor chimerism and to restore the GvL effect in patients with hematological malignancies. Thus, there are different options for the administration of DLI in AML patients. DLI is currently used prophylactically and in the setting of an overt relapse. In addition, in the minimal residual disease (MRD) setting, DLI may be a possibility to improve overall survival. However, DLI might increase the risk of severe life-threatening complications such as graft-versus-host disease (GvHD) as well as severe infections. The transfusion of lymphocytes has been tested not only for the treatment of hematological malignancies but also chronic infections. In this context, manipulated DLI in a prophylactic or therapeutic approach are an option, e.g., virus-specific DLI using different selection methods or antigen-specific DLI such as peptide-specific CD8+ cytotoxic T lymphocytes (CTLs). In addition, T cells are also genetically engineered, using both chimeric antigen receptor (CAR) genetically modified T cells and T cell receptor (TCR) genetically modified T cells. T cell therapies in general have the potential to enhance antitumor immunity, augment vaccine efficacy, and limit graft-versus-host disease after allo-SCT. The focus of this review is to discuss the different strategies to use donor lymphocytes after allo-SCT. Our objective is to give an insight into the functional effects of DLI on immunogenic antigen recognition for a better understanding of the mechanisms of DLI. To ultimately increase the GvL potency without raising the risk of GvHD at the same time.

Haploidentical transplantation might have superior graft-versus-leukemia effect than HLA-matched sibling transplantation for high-risk acute myeloid leukemia in first complete remission: a prospective multicentre cohort study

This study aimed to investigate graft-versus-leukemia (GVL) of haploidentical donor (HID) compared with HLA-matched sibling donor (MSD) for high-risk acute myeloid leukemia (H-AML) in first complete remission (CR1). One hundred and eighty-nine patients with H-AML in CR1 were enrolled in this multicentre prospective cohort study. Patients were assigned to groups transplanted with HID (n = 83) or MSD (n = 106) based on donor availability (biological randomization). The primary endpoint was the incidence of MRD positivity posttransplantation (post-MRD+). All post-MRD+ patients received preemptive interventions. The cumulative incidences of post-MRD+ were 18 and 42% in HID and MSD groups, respectively, (p < 0.001). Fifty-two patients received preemptive DLI, including 13 (16%) in HID and 39 cases (37%) in MSD groups (p = 0.001). Among HID and MSD groups, the 3-year cumulative incidence of relapse were 14 and 24% (p = 0.101); the 3-year cumulative incidence of treatment-related mortality were 15 and 10% (p = 0.368); the 3-year overall survival rates were 72 and 68% (p = 0.687); the 3-year disease-free-survival were 71 and 66% (p = 0.579); the 3-year graft-versus-host disease and relapse free survival were 63 and 43% (p = 0.035), respectively. HID might have a stronger GVL than MSD in H-AML patients. HID transplantation as postremission therapy should be recommended as one of the optimal choices for H-AML patients in CR1.

Haploidentical transplantation for acute myeloid leukemia patients with minimal/measurable residual disease at transplantation

There have been conflicting results regarding the impact of minimal/measurable disease at transplant on acute myeloid leukemia (AML) outcomes after haploidentical transplantation (haplo-SCT). We assessed the impact of pre-transplant disease status on post-transplant outcomes of 143 patients treated with haplo-SCT using fludarabine-melphalan (FM) conditioning and post-transplant cyclophosphamide (PTCy). With a median follow-up of 29 months, the two-year PFS for all patients was 41%. Compared to patients in complete remission (CR) at transplant, those with active disease (n = 29) and CR with incomplete count recovery (CRi) (n = 39) had worse PFS. They had hazard ratios (HR) of 3.5 (95% CI: 2.05-6.1; P < .001) and 2.3 (95% CI: 1.3-3.9; P = .002), respectively. Among patients who were in CR at transplant, there were no differences in PFS between those who had minimal residual disease (MRD) positive (n = 24), and MRD negative (n = 41) (HR 1.85, 95%CI: 0.9-4.0; P = .1). In multivariable analysis for patients in CR, only age was predictive for outcomes, while MRD status at transplant did not influence the treatment outcomes. Our findings suggest that haplo-SCT with FM conditioning regimen and PTCy-based GVHD prophylaxis has a protective effect, and may potentially abrogate the inferior outcomes of MRD positivity for patients with AML. Patients with positive MRD may benefit from proceeding urgently to a haplo-SCT, as this does not appear to negatively impact transplant outcomes.

Haploidentical Stem Cell Transplantation With Posttransplant Cyclophosphamide Therapy vs Other Donor Transplantations in Adults With Hematologic Cancers: A Systematic Review and Meta-analysis

Importance

Use of haploidentical (HAPLO) stem cell transplantation with posttransplant cyclophosphamide is rapidly increasing in adults with hematologic cancers. However, its specific role compared with other transplant strategies has yet to be identified.

Objective

To synthesize the existing evidence regarding outcomes of stem cell transplantations comparing HAPLO stem cell transplantation and posttransplant cyclophosphamide therapy with transplantations from matched related donors (MRDs), matched unrelated donors (MUDs), or mismatched unrelated donors (MMUDs).

Data Sources

PubMed, Cochrane Library, ClinicalTrials.gov, and meeting abstracts were searched for the key words haploidentical and cyclophosphamide from inception through March 1, 2019.

Study Selection

Studies comparing HAPLO stem cell transplantation and posttransplant cyclophosphamide therapy with transplantations from other donors in adults with hematologic cancers were eligible for meta-analysis.

Data Extraction and Synthesis

Pooled odds ratios (ORs) and 95% CIs were calculated using a random-effects model.

Main Outcomes and Measures

Main outcomes were all-cause mortality, nonrelapse mortality, and relapse.

Results

A total of 30 studies including 22 974 participants were analyzed. HAPLO stem cell transplantation with posttransplant cyclophosphamide therapy was associated with increased all-cause mortality compared with MRDs (OR, 1.17; 95% CI, 1.05-1.30), similar all-cause mortality compared with MUDs (OR, 1.06; 95% CI, 0.96-1.18), and reduced all-cause mortality compared with MMUDs (OR, 0.75; 95% CI, 0.61-0.92). Regarding nonrelapse mortality, HAPLO stem cell transplantation with posttransplant cyclophosphamide was associated with worse outcomes compared with MRDs (OR, 1.20; 95% CI, 1.04-1.40) but better outcomes compared with MUDs (OR, 0.75; 95% CI, 0.61-0.92) and MMUDs (OR, 0.51; 95% CI, 0.25-1.02). In terms of relapse, HAPLO stem cell transplantation with posttransplant cyclophosphamide was associated with similar outcome compared with MRDs (OR, 1.01; 95% CI, 0.86-1.17) and MMUDs (OR, 1.06; 95% CI, 0.77-1.47) but showed increased relapse compared with MUDs (OR, 1.20; 95% CI, 1.03-1.40).

Conclusions and Relevance

Results of this meta-analysis suggest that MRDs, if available, remain the optimal donors regarding mortality and HAPLO stem cell transplantation with posttransplant cyclophosphamide may be preferred over MMUDs. Prospective comparisons with MUDs are needed.

Innate Immune Responses in the Outcome of Haploidentical Hematopoietic Stem Cell Transplantation to Cure Hematologic Malignancies

In the context of allogeneic transplant platforms, human leukocyte antigen (HLA)-haploidentical hematopoietic stem cell transplantation (haplo-HSCT) represents one of the latest and most promising curative strategies for patients affected by high-risk hematologic malignancies. Indeed, this platform ensures a suitable stem cell source immediately available for virtually any patents in need. Moreover, the establishment in recipients of a state of immunologic tolerance toward grafted hematopoietic stem cells (HSCs) remarkably improves the clinical outcome of this transplant procedure in terms of overall and disease free survival. However, the HLA-mismatch between donors and recipients has not been yet fully exploited in order to optimize the Graft vs. Leukemia effect. Furthermore, the efficacy of haplo-HSCT is currently hampered by several life-threatening side effects including the onset of Graft vs. Host Disease (GvHD) and the occurrence of opportunistic viral infections. In this context, the quality and the kinetic of the immune cell reconstitution (IR) certainly play a major role and several experimental efforts have been greatly endorsed to better understand and accelerate the post-transplant recovery of a fully competent immune system in haplo-HSCT. In particular, the IR of innate immune system is receiving a growing interest, as it recovers much earlier than T and B cells and it is able to rapidly exert protective effects against both tumor relapses, GvHD and the onset of life-threatening opportunistic infections. Herein, we review our current knowledge in regard to the kinetic and clinical impact of Natural Killer (NK), γδ and Innate lymphoid cells (ILCs) IRs in both allogeneic and haplo-HSCT. The present paper also provides an overview of those new therapeutic strategies currently being implemented to boost the alloreactivity of the above-mentioned innate immune effectors in order to ameliorate the prognosis of patients affected by hematologic malignancies and undergone transplant procedures.

Reduced intensity allogeneic stem cell transplant with anti-thymocyte globulin and post-transplant cyclophosphamide in acute myeloid leukemia

OBJECTIVES

We aimed to study the efficacy of reduced intensity conditioning (RIC) allo-HSCT combined with anti-thymocyte globulin (ATG) and post-transplant cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis in AML.

METHODS

One hundred forty-seven patients were included. All patients underwent unmanipulated peripheral blood stem cell RIC allo-HSCT. Median follow-up was 12.8 months (range 0.5-39).

RESULTS

Median age was 58 years. Twenty-nine (20%) recipients received 10/10 MRD grafts, 69 (47%) 10/10 MUD grafts, 20 (13.6%) 9/10 MMUD, and 29 (20%) haploidentical grafts. The cumulative incidence of grade II-IV and III-IV acute GVHD at day +100, and moderate/severe chronic GVHD at 1-year were as follow: 14.3%, 1.4%, and 8.3%. There were no significant differences according to donor type (P = .46) and cumulative incidence of GVHD. One-year overall survival (OS), relapse-free survival (RFS), non-relapse mortality, and GVHD-free/Relapse-free survival were as follows: 66.9% (95% CI 58.4-74), 59.9%, and 18.7% and 53.7%. KPS ≤ 80 was predictive of worst OS (P = .04). Those recipients who received MUD transplants had better RFS (P = .01).

CONCLUSIONS

RIC allo-HSCT combined with ATG and PTCy is safe and a potentially curative strategy and it is associated with impressive GRFS in AML.

Safety and Efficacy of Haploidentical Peripheral Blood Stem Cell Transplantation for Myeloid Malignancies Using Post-transplantation Cyclophosphamide and Anti-thymocyte Globulin as Graft-versus-Host Disease Prophylaxis

Haploidentical stem cell transplantation (haploSCT) has greatly improved access to curative treatment for myeloid malignancies in patients without suitable matched sibling/unrelated donors. We investigated the safety and efficacy of haploSCT after reduced intensity conditioning (RIC) with anti-thymocyte globulin (ATG), post-transplant cyclophosphamide (PTCy), and cyclosporine to prevent rejection and graft-versus-host disease (GVHD). In this study, 47 patients received RIC using fludarabine, busulfan, and total body irradiation (200 cGy). Unmanipulated peripheral blood grafts were used. GVHD prophylaxis included ATG (4.5 mg/kg day−3 to −1), PTCy (50 mg/kg/day day +3, +4), and cyclosporine from day +5. The median follow-up was 15 months (range 3–27). Thirty one (66%) patients had acute myeloid leukemia (AML), 10 (21%) had high-risk myelodysplastic syndrome, and 6 (13%) had a myeloproliferative neoplasia. Median age was 60 years (range 22–73). The d+100 cumulative incidences of grade II–IV and III–IV acute GVHD were 17% (95% confidence interval (CI) 7.9–29.1) and 6.4% (1.6–15.9), respectively. The cumulative incidence of moderate-severe chronic GVHD at 1 year was 15.2% (95% CI 6.5–27.1). Overall survival (OS) and relapse-free survival (RFS) were 55.2% (95% CI 39.5–68.4) and 49.5% (95% CI 34.2–63), respectively. Nonrelapse mortality (NRM) for all patients at 1 year was 37.1% (95% CI 23.2–51.1). Infection was the main cause of death (26%). For AML, 1-year OS, RFS, and NRM were 64.1% (95% CI 43.3–78.9), 54.5 (95% CI 34.6–70.7), and 26.8% (95% CI 12.3–43.6), respectively. In conclusion, unmanipulated haploidentical peripheral blood stem cells (PBSC) transplantation following RIC and dual in vivo T-cell depletion results in a low incidence of acute and chronic GVHD for patients diagnosed with myeloid malignancies.

Alpha-1 Antitrypsin-Expressing Mesenchymal Stromal Cells Confer a Long-Term Survival Benefit in a Mouse Model of Lethal GvHD

Acute graft-versus-host disease is a frequent complication associated with allogeneic hematopoietic stem cell transplantation. Patients that become refractory to initial steroid treatment have a poor prognosis. apceth-201 consists of human allogeneic mesenchymal stromal cells, engineered by lentiviral transduction to express the protease inhibitor alpha-1 antitrypsin, to augment the anti-inflammatory potential of the mesenchymal stromal cells. We show that apceth-201 mesenchymal stromal cells efficiently suppress T cell proliferation and polarize macrophages to an anti-inflammatory M2 type, in vitro. To assess the in vivo efficacy of apceth-201, it was tested in two different mouse models of acute graft-versus-host disease. Control animals in a humanized model succumbed quickly to disease, whereas median survival was doubled in apceth-201-treated animals. The product was also tested in a graft-versus-host disease model system that closely mimics haploidentical hematopoietic stem cell transplantation, an approach that is now being evaluated for use in the clinic. Control animals succumbed quickly to disease, whereas treatment with apceth-201 resulted in long-term survival of 57% of the animals. Within 25 days after the second injection, clinical scores returned to baseline in responding animals, indicating complete resolution of graft-versus-host disease. These promising data have led to planning of a phase I study using apceth-201.

Cord blood research, banking, and transplantation: achievements, challenges, and perspectives

The first hematopoietic transplant in which umbilical cord blood (UCB) was used as the source of hematopoietic cells was performed in October 1988. Since then, significant achievements have been reported in terms of our understanding of the biology of UCB-derived hematopoietic stem (HSCs) and progenitor (HPCs) cells. Over 40,000 UCB transplants (UCBTs) have been performed, in both children and adults, for the treatment of many different diseases, including hematologic, metabolic, immunologic, neoplastic, and neurologic disorders. In addition, cord blood banking has been developed to the point that around 800,000 units are being stored in public banks and more than 4 million units in private banks worldwide. During these 30 years, research in the UCB field has transformed the hematopoietic transplantation arena. Today, scientific and clinical teams are still working on different ways to improve and expand the use of UCB cells. A major effort has been focused on enhancing engraftment to potentially reduce risk of infection and cost. To that end, we have to understand in detail the molecular mechanisms controlling stem cell self-renewal that may lead to the development of ex vivo systems for HSCs expansion, characterize the mechanisms regulating the homing of HSCs and HPCs, and determine the relative place of UCBTs, as compared to other sources. These challenges will be met by encouraging innovative research on the basic biology of HSCs and HPCs, developing novel clinical trials, and improving UCB banking both in the public and private arenas.

Influence of Donor Type (Sibling versus Matched Unrelated Donor versus Haploidentical Donor) on Outcomes after Clofarabine-Based Reduced-Intensity Conditioning Allograft for Myeloid Malignancies

Clofarabine-based reduced-intensity conditioning (RIC) regimens are well-established schedules for allograft in patients with myeloid malignancies. A retrospective study was conducted including all adults allografted in our department with such a regimen and disease with the aim to assess whether or not the donor type (matched sibling [MSD], matched unrelated [MUD], or haploidentical [haplo]) impacted outcomes. Between October 2009 and February 2018, 118 patients met the inclusion criteria. Thirty-six, 55, and 27 patients received a graft from an MSD, MUD, or haplo donor, respectively. Peripheral blood stem cells (PBSCs) were the source of graft for all patients. The median age of the entire cohort was 62 years (range, 20 to 73), and the median follow-up was 31 months (range, 4.5 to 106). All patients engrafted except 1 haplo recipient. Neutrophils (>.5 × 10⁹/L) and platelets (50 × 10⁹/L) recoveries were significantly delayed in the haplo group (P = .0003 and P < .0001) compared with MSD and MUD. Acute grades II to IV or III to IV graft-versus-host disease (GVHD) incidences were similar between the 3 groups as well as the incidence of moderate or severe chronic GVHD. Also, similar 2-year overall survival (OS; 64.7% versus 73.9% versus 60.2%, P = .39), disease-free survival (DFS; 57.7% versus 70.9% versus and 53.6%, P = .1), and GVHD relapse-free survival (37.9% versus 54.3% versus 38.9%, P = .23) were observed between MSD versus MUD versus haplo groups. The same was true when considering only acute myeloid leukemia (AML) cases. In multivariate analysis the type of donor remained independent of outcomes in this series, whereas myelodysplastic syndrome (versus AML), high disease risk index, and older donor (≥50 years) were associated with lower OS and DFS. These data suggest that haplo donors are an acceptable alternative for patients receiving a clofarabine-based RIC PBSC allograft for myeloid malignancies who lack an MSD or a MUD.

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.

Allogeneic Hematopoietic Stem Cell Transplantation for Older Patients With Acute Myeloid Leukemia

OPINION STATEMENT

Acute myelogenous leukemia (AML) in the elderly is complex and has a poor prognosis, often characterized by higher risk cytogenetic and molecular features compared to that in younger patients. Rates of transplant have been limited by concern related to non-relapse mortality, as older patients have historically been considered medically unfit for the transplantation process. Reduced-intensity conditioning (RIC) for hematopoietic stem cell transplantation (HSCT) has been shown to provide similar efficacy to myeloablative methods, with decreased non-relapse mortality in the elderly and improved efficacy over non-transplant approaches with cytotoxic chemotherapy alone. Targeted non-cytotoxic and modified cytotoxic agents have emerged to further improve transplant outcomes for older AML patients. Validated comorbidity indices are useful tools to assess an individual's fitness for undergoing HSCT rather than chronological age alone. We believe HSCT is the primary curative treatment approach for many older AML patients, taking into account risk and comorbidities, particularly given the tendency of leukemia in this population to harbor an unfavorable disease profile. We use RIC and advocate for the addition of targeted agents if applicable. With continuing data in support of transplant for older AML patients, we anticipate that transplant rates in this population will continue to rise.

Haploidentical versus unrelated allogeneic stem cell transplantation for relapsed/refractory acute myeloid leukemia: a report on 1578 patients from the Acute Leukemia Working Party of the EBMT

Primary refractory or relapsed acute myeloid leukemia is associated with a dismal prognosis. Allogeneic stem cell transplantation is the only therapeutic option that offers prolonged survival and cure in this setting. In the absence of a matched sibling donor, transplantation from unrelated 10/10 HLA allele-matched or 9/10 HLA allele-mismatched donors and haploidentical donors are potential alternatives. The current study aimed to compare the outcomes of acute myeloid leukemia patients with active disease who received allogeneic stem cell transplantation from a haploidentical donor with post-transplant cyclophosphamide (n=199) versus an unrelated 10/10-matched donor (n=1111) and versus an unrelated 9/10-mismatched donor (n=383) between 2007 and 2014 and who were reported to the European Society for Blood and Marrow Transplantation registry. Propensity score weighted analysis was conducted in order to control for disease risk imbalances between the groups. The leukemia-free survival rates at 2 years of recipients of grafts from a haploidentical donor, an unrelated 10/10-matched donor and an unrelated 9/10-mismatched donor were 22.8%, 28% and 22.2%, respectively (P=NS). In multivariate analysis, there were no significant differences in leukemia-free survival, overall survival, relapse incidence, non-relapse mortality, or graft-versus-host-disease-free relapse-free survival between the three groups. Two predictive factors were associated with a higher relapse incidence: transplantation during first or second relapse compared to primary refractory acute myeloid leukemia and poor cytogenetics. Allogeneic stem cell transplantation may rescue about 25% of acute myeloid leukemia patients with active disease. Importantly, the outcomes of transplants from haploidentical donors were comparable to those from 10/10-matched and 9/10-mismatched unrelated donors. Therefore, a haploidentical donor is a valid option for acute myeloid leukemia patients with active disease.

Comparable outcomes of haploidentical, 10/10 and 9/10 unrelated donor transplantation in adverse karyotype AML in first complete remission

Allogeneic hematopoietic stem cell transplantation (HSCT) is the most powerful therapy preventing relapse in patients with adverse cytogenetics acute myeloid leukemia (AML) in first complete remission (CR1). In the absence of a matched related donor, potential alternatives include 10/10, 9/10 HLA-matched unrelated (UD) or haploidentical (Haplo) donors. We analyzed clinical outcomes of patients undergoing T-cell repleted Haplo (n = 74), 10/10 UD (n = 433) and 9/10 UD HSCT (n = 123) from 2007 to 2015, reported to the EBMT Registry. Adverse risk AML was defined according to the 2017 ELN cytogenetic risk classification. The 2-year nonrelapse mortality was 19% for Haplo, 18% for 10/10 UD and 18% for 9/10 UD (P = .9). The relapse incidence was not significantly affected by donor source, with a 2-year incidence of 27% for Haplo HSCT, 39% for 10/10 UD and 37% for 9/10 UD SCT (P = .3). We show comparable probabilities of leukemia-free survival (LFS) and overall survival (OS) at 2 years among Haplo HSCT, 10/10 UD SCT and 9/10 UD SCT (53% and 59%, 43% and 50%, 44% and 50%, respectively, P = .5 for both parameters). The type of donor was not significantly associated with either acute or chronic graft-vs.-host disease incidence. Using multivariable Cox model, Haplo HSCT recipients experienced comparable OS and LFS to 10/10 and 9/10 UD. In the present series of adverse cytogenetics AML patients in CR1, Haplo HSCT recipients had comparable outcomes to those of 10/10 and 9/10 UDs, suggesting that all these types of HSCT may be considered a valid option in this high risk population.

New approaches in allogenic transplantation in AML

Acute myeloid leukemia (AML) is a heterogeneous disorder with high morbidity and mortality. Allogeneic stem cell transplantation (allo-SCT) is an effective, and sometimes the only, curative postremission therapy for AML patients. Based on genetic risk classification, the published data have suggested that allo-SCT be recommended for high- and most intermediate-risk AML but not for low-risk AML in first complete remission (CR1). Recently, the role of allo-SCT in low-risk AML in CR1 is being established with the development of a risk-directed, minimal residual disease-based strategy. Though human leukocyte antigen-matched sibling transplantation remains the preferred therapeutic option for AML, modern approaches and developments pre-, peri- and post-transplant have facilitated other transplant modalities, especially haploidentical SCT, as promising valid alternative choices. In this paper, we review recent advances in allo-SCT for AML, weigh the benefits of allo-SCT for high-, intermediate-, and even low-risk AML in CR1, discuss the best choice of allo-SCT donor for the treatment of AML, and summarize new approaches for refractory and relapsed AML pre- or post-allo-SCT.