Allogeneic hematopoietic cell transplantation for adults with acute myeloid leukemia conducted in Japan during the past quarter century

Allogeneic hematopoietic stem cell transplantation using reduced intensity conditioning regimen for patients with acute myeloid leukemia not in complete remission

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only potentially curative treatment option for patients with refractory and relapsed acute myeloid leukemia (R/R AML) not in complete remission. Many studies investigating the prognosis of patients with R/R AML not in remission focused on patients who received myeloablative conditioning regimen (MAC). Conversely, reduced intensity conditioning regimen (RIC) could be a considerable conditioning regimen for some patients because of the high frequency of R/R AML in older patients who are not candidates for MAC.

OBJECTIVE

This study aimed to evaluate the prognosis and identify factors associated with outcomes in patients with R/R AML who underwent allogeneic HSCT with RIC.

STUDY DESIGN

This study included 707 adult patients with AML not in complete remission who had received RIC. The primary endpoint was progression-free survival (PFS), which was estimated using the Kaplan-Meier method. Prognostic factors were identified using a Cox proportional hazards model with multiple imputations using a chained equation approach.

RESULTS

The 5-year PFS, overall survival, relapse, and nonrelapse mortality were 18.8% (95% confidence interval [CI]: 15.6-22.2), 22.0% (95% CI: 8.5-25.7), 53.6% (95% CI 49.7-57.4%) and 27.5% (95% CI: 24.0-31.2), respectively. Multivariable analysis revealed that male sex, poor performance status, karyotype risk, and blasts in the peripheral blood were significantly associated with PFS.

CONCLUSIONS

This study identified prognostic factors in patients with R/R AML not in complete remission. These results can help to develop a transplant strategy for the treatment of R/R AML.

Myeloablative conditioning in cord blood transplantation for acute myeloid leukemia patients is efficacious only until age 55

Umbilical cord blood transplantation (CBT) is accepted as an effective treatment for acute myeloid leukemia (AML), and reduced-intensity conditioning (RIC), rather than myeloablative conditioning (MAC) regimens allowed elderly patients to be treated safely. However, appropriate intensities of conditioning regimens are still unclear, especially for middle-aged patients. To compare outcomes after RIC and MAC regimens, we analyzed AML patients aged 16 years or older in the Japanese registry database, who underwent single cord unit CBT between 2010-2019. Median ages of the RIC group (n = 1353) and the MAC group (n = 2101) were 59 and 51 years (P < 0.001), respectively. 5-year overall survival (OS) after MAC was superior to that of RIC (38.3% vs 27.7%, P < 0.001) with lower incidence of relapse (33.9% vs 37.4%, P = 0.029) and better neutrophil engraftment (84.7% vs 75.9%, P < 0.001). Detailed subgroup analysis revealed that age at transplantation is the most important factor affecting 5-year OS in RIC and MAC. This analysis identified a threshold of 55 years, beyond which the superiority of MAC disappeared, irrespective of other factors such as disease status or performance status. In conclusion, RIC may be preferable for patients aged 56 or older in CBT for AML due to higher potential toxicities.

Allogeneic hematopoietic cell transplantation from alternative donors in acute myeloid leukemia

Allogeneic hematopoietic cell transplantation (HCT) potentially provides a cure for patients with acute myeloid leukemia (AML) who are unlikely to be cured with chemotherapy alone. Previously, human leukocyte antigen (HLA)-matched related donors were used exclusively, which made the procedure available for a limited proportion of patients. The introduction of high-resolution HLA-typing technology, innovations in immunosuppressive therapy, and improved supportive care measures have significantly changed the situation. Now, patients without a matched related donor have an ample opportunity to receive allogeneic HCT with the use of matched or mismatched unrelated donors, umbilical cord blood grafts, or haploidentical related donors. The outcomes of alternative donor transplantations have improved over the past decades, and the growth of unrelated donor registries as well as the donor diversification have enhanced the chance of finding a suitable donor. With multiple alternative donor choices available for most patients, the donor selection is becoming increasingly important. To discuss the optimal donor choice in case of unavailability of an HLA-matched related donor, this article reviews the existing literature of retrospective and prospective comparisons of different alternative donor transplantations in AML and discusses the current state-of-art modalities in allogeneic HCT using alternative donors.

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.

Prognostic factors in haploidentical transplantation with post-transplant cyclophosphamide for acute myeloid leukemia

BACKGROUND AIMS

Haploidentical hematopoietic stem cell transplantation (haplo-HCT) is an appropriate option when an HLA-matched related or unrelated donor is not available. Haplo-HCT using post-transplant cyclophosphamide (PTCy) is being increasingly performed worldwide due to its effective suppression of GVHD and its safety.

METHODS

We conducted a large nationwide cohort study to retrospectively analyze 366 patients with acute myeloid leukemia undergoing haplo-HCT with PTCy between 2010 and 2019 and to identify prognostic factors.

RESULTS

A multivariate Cox analysis revealed that an older recipient age (≥60 years), a male donor to a male recipient, a cytomegalovirus IgG-negative donor to a cytomegalovirus IgG-positive recipient, a poor cytogenetic risk, a noncomplete remission status at the time of transplantation, and a history of HCT were independently associated with worse overall survival (OS). Based on each hazard ratio, these factors were scored (1-2 points) and stratified by their total score into three groups: favorable (0-1 points), intermediate (2-3 points), and poor (4 points or more) groups, and 2-year OS rates were 79.9%, 49.2%, and 25.1%, respectively (P < 0.001).

CONCLUSIONS

The present study revealed significant prognostic factors in haplo-HCT with PTCy, and a scoring system based on these factors may be used to predict outcomes.

The effect of center experience on allogeneic hematopoietic cell transplantation outcomes in acute myeloid leukemia

This study aimed to address the prognostic impact of center experience based on the data of 7821 adults with acute myeloid leukemia who underwent allogeneic hematopoietic cell transplantation (HCT) from 2010 to 2019 in Japan, where medical care was provided within a uniform healthcare system. Center experience was defined based on the number of allogeneic HCTs performed for any indication during the study period, by which centers were divided into low-, intermediate-, and high-volume centers. After adjusting for known confounding factors, the risk of overall mortality was lowest for the high-volume centers and highest for the low-volume centers, with the difference between the center categories attributed primarily to the risk of relapse. Patients transplanted at high-volume centers had higher risks of acute and chronic graft-versus-host diseases but without an increased risk of non-relapse mortality (NRM). These findings reveal the presence of a center effect in allogeneic HCT conducted during the past decade in Japan, highlighting the difference in relapse based on center experience. The weaker effect on NRM compared with that on relapse suggests that the transplantation care quality is becoming equalized across the country.

Allogeneic hematopoietic cell transplantation for patients with acute myeloid leukemia not in remission

Allogeneic hematopoietic cell transplantation (HCT) is the last option for long-term survival for patients with chemotherapy-refractory acute myeloid leukemia (AML). By using the Japanese nationwide registry data, we analyzed 6927 adults with AML having undergone first allogeneic HCT while not in complete remission (CR) between 2001 and 2020. The 5-year overall survival (OS), relapse, and non-relapse mortality (NRM) rates were 23%, 53%, and 27%, respectively. Multivariate analysis identified several factors predictive of OS mainly through their effects on relapse (cytogenetics, percentage of blasts in the peripheral blood, and transplantation year) and NRM (age, sex, and performance status). As regards disease status, relapsed disease was associated with a higher risk of overall mortality than primary induction failure (PIF). The shorter duration of the first CR increased the risks of relapse and overall mortality for the relapsed group, and the longer time from diagnosis to transplantation did so for the PIF group. Our experience compiled over the past two decades demonstrated that >20% of patients still enjoy long-term survival with allogeneic HCT performed during non-CR and identified those less likely to benefit from allogeneic HCT. Future efforts are needed to reduce the risk of posttransplant relapse in these patients.

Comparison of fludarabine-based conditioning regimens in adult cord blood transplantation for myeloid malignancy: A retrospective, registry-based study

Fludarabine/busulfan and fludarabine/melphalan are viable options as conditioning regimens. However, the optimal fludarabine-based conditioning in cord blood transplantation (CBT) remains unclear. Therefore, this retrospective, registry-based study aimed to analyze the impact of five fludarabine-containing conditioning regimens on 1395 adult patients (median age, 61 years) with acute myeloid leukemia, myelodysplastic syndrome, and chronic myeloid leukemia who underwent their first CBT. Treatment outcomes of fludarabine combined with melphalan (100-140 mg/m2 ) and low-dose total body irradiation (TBI; FM140T); melphalan (80-99 mg/m2 ) and TBI (FM80T); busulfan (12.8 mg/kg) and melphalan (FB4M); busulfan (12.8 mg/kg) and TBI (FB4T); and busulfan (6.4 mg/kg) and TBI (FB2T) were compared. The 3-year survival rate was 67%, 53%, 44%, 36%, and 39%, respectively (p < .0001). The FM140T survival rate was the most favorable after adjusting for confounders, and the hazard ratios (vs. FM140T) for overall mortality were as follows: FM80T, 1.6 (95% confidence interval [CI], 1.2-2.2); FB4M, 2.1 (95% CI, 1.6-2.8); FB4T, 2.7 (95% CI, 2.0-3.7); and FB2T, 2.2 (95% CI, 1.6-3.1). The better survival observed with FM140T, regardless of the disease, disease risk, age, or transplant year, was attributed to the lower relapse rate and lower non-relapse mortality (NRM) associated with fewer infectious deaths. Conversely, FB4T was associated with a higher relapse rate and higher NRM. The findings indicate that the outcomes of CBT in myeloid malignancies were highly dependent on both the alkylating agent and its dose in combination with fludarabine. Therefore, compared with fludarabine/busulfan-based conditioning, FM140T may be the preferred regimen.

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.

Efficacy and safety of allogeneic hematopoietic cell transplantation in acute myeloid leukemia patients aged > 65 years with unfavorable cytogenetics

Unrelated donor bone marrow transplantation (UR-BMT), unrelated donor cord blood stem cell transplantation (UR-CBT), and haploidentical peripheral blood stem cell transplantation (Haplo-PBSCT) are the main alternative stem cell sources for allogeneic hematopoietic cell transplantation (HCT) in Japan. The present study aimed to identify factors associated with the outcomes of UR-BMT, UR-CBT, and Haplo-PBSCT in older patients with acute myeloid leukemia (AML) and intermediate- or poor-risk cytogenetics to improve the clinical efficacy and safety of allogeneic HCT. We retrospectively analyzed data for 448 AML patients aged > 65 years who received UR-BMT (n = 102), UR-CBT (n = 250), or Haplo-PBSCT (n = 96) between 2014 and 2020. Overall survival (OS) in the UR-BMT group was superior (P = 0.033) to that in the other groups. However, all patients without complete remission (non-CR) who had Karnofsky performance status (KPS) < 80 at HCT and poor-risk cytogenetics died within 1 year after HCT. Multivariate Cox regression analysis identified KPS <80 at HCT and poor-risk cytogenetics as independent predictors of worse OS in non-CR patients. KPS < 80 may be an alternative indicator for non-CR AML patients with poor-risk cytogenetics during the selection of HCT, alternative treatments, or best supportive therapy, and the optimal KPS is important for the success of HCT.

Overcoming relapse: prophylactic or pre-emptive use of azacitidine or FLT3 inhibitors after allogeneic transplantation for AML or MDS

Relapse remains the most critical obstacle in treatment by allogeneic hematopoietic stem cell transplantation (HSCT). Non-relapse mortality has improved annually, but relapse mortality remains high. Post-transplant maintenance treatment, such as hypomethylating agents and FMS-like tyrosine kinase 3 (FLT3) inhibitors, has been investigated for decades as a means of preventing disease relapse after HSCT. Other factors besides the relapse tendency of the primary disease that can affect the transition of estimated disease burden in patients undergoing HSCT are disease status at HSCT (non-remission, remission with minimal/measurable residual disease (MRD), and remission without MRD) and conditioning regimen intensity. Optimal selection of patients at high risk for relapse who can tolerate a long duration of therapy is pivotal for successful post-transplant maintenance therapy. In this review, we provide an overview of current progress in research on post-transplant maintenance treatment using azacitidine or FLT3 inhibitors for preventing disease relapse after HSCT for AML or MDS, and discuss the future outlook in this area.

Age and allogeneic hematopoietic cell transplantation outcomes in acute myeloid leukemia

Although several studies have reported significant effects of patient age on outcomes of allogeneic hematopoietic cell transplantation (HCT), the prognostic relevance of age must be determined separately for myeloablative conditioning (MAC) and reduced-intensity conditioning (RIC). We analyzed Japanese nationwide transplantation registry data of patients aged 20-79 years with acute myeloid leukemia who underwent allogeneic HCT using MAC (n = 7525) or RIC (n = 3154) between 2008 and 2019. Patient were divided into six groups by age, with each group representing a decade, and overall survival (OS), relapse, and non-relapse mortality (NRM) were compared between adjacent age groups. The adverse impact of age on OS increased each decade starting at age 40 among patients receiving MAC, but only differed significantly between patients in their 50s and 60s among those receiving RIC. In patients receiving both MAC and RIC, the detrimental effect of advanced age on OS was accompanied by an increased risk of NRM. These findings show that age affects NRM and OS significantly, but differs depending on conditioning intensity. RIC mitigates the adverse prognostic impact of older age and is thus considered a reasonable option for older patients.

Conditioning regimens for allogeneic hematopoietic cell transplantation in acute myeloid leukemia: Real-world data from the Japanese registry studies

Conditioning regimens play a crucial role in preventing relapse of acute myeloid leukemia (AML) following allogeneic hematopoietic cell transplantation (HCT). In early times, myeloablative conditioning was used exclusively, but it was associated with significant toxicity. However, the advent of reduced-intensity conditioning has allowed allogeneic HCT to be performed more safely, leading to an expansion of our choices for conditioning regimens. As the transplantation methods have become highly diversified, it is reasonable to determine an optimal conditioning regimen in consideration of patient-, disease-, and transplantation-related factors. In this context, large-scale registry-based studies provide real-world data to allow for a detailed evaluation of the utility of individual conditioning regimens in specific clinical settings. The Japanese Society for Transplantation and Cellular Therapy has been conducting a nationwide survey for HCT since 1993 that currently covers >99% of all the transplantation centers nationwide, and >1,000 allogeneic HCTs performed for adults with AML are registered per year. We have been using the registry data to implement a number of studies focusing on adults with AML, and the large number of patients registered consecutively from nearly all transplantation centers nationwide represent real-world practice in Japan. This article reviews and discusses the results obtained from our registry-based studies pertaining to various conditioning regimens.

Syngeneic hematopoietic stem cell transplantation for acute myeloid leukemia: a propensity score-matched analysis

The present study evaluated outcomes and prognostic factors in adult patients with acute myeloid leukemia (AML) after syngeneic hematopoietic stem cell transplantation (HSCT). Among patients in first complete remission (CR1), outcomes of syngeneic HSCT (Syn) were compared with those of autologous HSCT (Auto), allogeneic HSCT from human leukocyte antigen (HLA)-matched sibling donor (MSD), or allogeneic HSCT from HLA-matched unrelated donor (MUD). Among 11,866 patients receiving first HSCT, 26 in the Syn group were analyzed. The 5-year overall survival (OS) rate, the cumulative incidence of relapse, and the cumulative incidence of non-relapse mortality (NRM) were 47.8%, 59.6%, and 4.6%, respectively. The OS was significantly better in patients in CR1 (n = 13) than in patients in non-CR1 (P = 0.012). Furthermore, 39 patients in CR1 each were assigned to the Auto, MSD, and MUD groups using propensity score matching. The 5-year OS in the Syn (68.4%) was not significantly different from those in the Auto (55.9%, P = 0.265), MSD (62.4%, P = 0.419), or MUD (63.7%, P = 0.409) groups. A higher relapse in the Syn than in the MSD and MUD groups was offset by lower NRM. In summary, syngeneic HSCT might be an alternative option for AML patients in CR1.

Allogeneic Hematopoietic Cell Transplantation from Alternative Donors in Acute Myelogenous Leukemia: A Comparative Analysis

In the absence of HLA-matched related and unrelated donors, alternative donors must be found for patients in need of allogeneic hematopoietic cell transplantation (HCT). There are at least 3 donor options: a mismatched unrelated donor (MMUD), umbilical cord blood (UCB), and a haploidentical related donor (haplo); however, the optimal alternative donor type remains to be established. This study aimed to address how the outcomes of patients receiving these 3 alternative donor HCTs differ, and whether these outcomes change over time post-transplantation. We retrospectively analyzed Japanese nationwide transplantation registry data of adults with acute myelogenous leukemia (AML) undergoing allogeneic HCT while in first complete remission (CR) from an MMUD with a 7/8 match at the allele level (n = 601), with UCB (n = 1110), or from a haploidentical related donor (n = 221) between 2007 and 2018. For patients who underwent transplantation between 2007 and 2014, the 3-year overall survival (OS) for the MMUD, UCB, and Haplo groups was 60%, 54%, and 47%, respectively (P = .022). For those who underwent transplantation between 2015 and 2018, the 3-year OS in these groups was 60%, 66%, and 63%, respectively (P = .693). Multivariate analysis revealed that the risks of both overall mortality and nonrelapse mortality (NRM) were significantly lower in the later period than in the earlier period in the UCB group (hazard ratio [HR], 0.66 [P < .001] for OS; HR, 0.64 [P < .001] for NRM) and the Haplo group (HR, 0.58 [P = .019 for OS; HR, 0.39 [P = .004] for NRM), but not in the MMUD group (HR, 1.07 [P = .631] for OS; HR, 1.26 [P = .175] for NRM). The results of a test for interaction showed a significant difference in the effect of transplantation period on OS and NRM between the MMUD and UCB groups (P = .014 for OS; P = .004 for NRM) and between the MMUD and Haplo groups (P = .034 for OS; P = .003 for NRM). These findings demonstrate the recent improvements in the outcomes of UCB and Haplo transplantations in patients with AML in first CR that have resulted in a similar OS in patients undergoing HCT with grafts from MMUDs, UCB, and haploidentical donors in the later period of the study.

Long-term trends in the clinical outcomes of patients with acute myeloid leukemia: a population-based real-world data analysis using the Osaka Cancer Registry

We evaluated the survival patterns for acute myeloid leukemia (AML) patients registered in the Osaka Cancer Registry from 1975 to 2017. During this period, 9706 patients were diagnosed with AML, with a median age of 60 years (range, 0-100). Patients were grouped by age (≤ 20, 21-40, 41-60, 61-70, and ≥ 71) and the year of their diagnosis (1975-1989, 1990-2001, 2002-2010, and 2011-2017). The overall survival (OS) rates of patients of ≤ 60 years of age improved significantly from the period 1975-1989 up to 1990-2001. However, there was a stagnation from 2002-2010 to 2011-2017. In terms of non-acute promyelocytic leukemia patients of > 60 years of age, the improvement of OS was limited during a very long period. In conclusion, the clinical outcome of patients with AML dramatically improved from 1975 to 2001. However, our dataset revealed stagnation in the improvement since 2002. Novel treatment options are needed to further improve the survival of elderly patients.

Difference in outcomes following allogeneic hematopoietic cell transplantation for patients with acute myeloid leukemia and myelodysplastic syndromes

To evaluate whether outcomes following allogeneic hematopoietic cell transplantation differ according to disease type, a three-way comparison for patients with de novo acute myeloid leukemia (AML) (n = 3318), AML evolving from myelodysplastic syndromes (MDS) (n = 208), and MDS with excess blasts (MDS-EB) (n = 994) was performed. The 5-year probabilities of overall survival (OS) for de novo AML, AML evolving from MDS, and MDS-EB were 60%, 42%, and 41% (p < 0.001), respectively. Multivariate analysis revealed that, compared to de novo AML, AML evolving from MDS was associated with a higher risk of NRM (p = 0.030) and MDS-EB with a higher risk of relapse (p < 0.001), both leading to lower OS (p = 0.010 and p < 0.001, respectively). These findings demonstrate inter-disease differences in post-transplant outcomes and highlight the needs to reduce NRM for AML evolving from MDS and to reduce relapse for MDS-EB.

The evolving concept of indications for allogeneic hematopoietic cell transplantation during first complete remission of acute myeloid leukemia

The long-standing debate of whether patients with acute myeloid leukemia (AML) should proceed to allogeneic hematopoietic cell transplantation (HCT) during first complete remission (CR1) remains unsettled. Although allogeneic HCT during CR1 used to be recommended for those with intermediate or poor cytogenetics if they had a matched sibling donor, the concept of indications for allogeneic HCT during CR1 has been evolving by virtue of advances in understanding of the molecular pathogenesis of AML and innovations in transplantation practice attained over the last few decades. The incorporation of molecular profiles of leukemia has been shown to contribute to further refinements of risk classification that had previously relied mostly on cytogenetics, while the progress in transplantation procedures has made it possible to perform transplantations more safely even for patients without a matched sibling donor. These significant changes have underpinned the need to reappraise indications for allogeneic HCT during CR1 of AML. Improvements in clinical applications of genetic and measurable residual disease information as well as in transplantation technology are expected to further refine indications for allogeneic HCT during CR1, and thus promote an individualized approach for the treatment of AML.

Allogeneic hematopoietic stem cell transplantation for myelodysplastic syndrome in adolescent and young adult patients

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curable treatment option for adolescent and young adult (AYA) patients with myelodysplastic syndrome (MDS). The study aim was to evaluate epidemiological data and identify prognostic factors for AYA patients with MDS undergoing allogeneic HSCT. Here, 645 patients were selected from patients enrolled in a multicenter prospective registry for HSCT from 2000 to 2015. The primary endpoint was 3-year overall survival (OS). Survival rates were estimated using the Kaplan-Meier method. Prognostic factors were identified using the multivariable Cox proportional hazards model. The 3-year OS was 71.2% (95% confidence interval [CI]: 67.4-74.6%). In multivariable analysis, active disease status (adjusted hazard ratio: 1.54, 95% CI: 1.09-2.18, p = 0.016), poor cytogenetic risk (1.62, 1.12-2.36, p = 0.011), poor performance status (2.01, 1.13-3.56, p = 0.016), human leukocyte antigen (HLA)-matched unrelated donors (2.23, 1.39-3.59, p < 0.001), HLA-mismatched unrelated donors (2.16, 1.09-4.28, p = 0.027), and cord blood transplantation (2.44, 1.43-4.17, p = 0.001) were significantly associated with poor 3-year OS. In conclusion, in AYA patients with MDS the 3-year OS following allogeneic HSCT was 71.2%. Active disease status, poor cytogenetic risk, poor performance status, and donor sources other than related donors were associated with poor 3-year OS.

The impact of graft cell source on bloodstream infection in the first 100 days after allogeneic hematopoietic cell transplantation

Bloodstream infection (BSI) is a major infectious complication after allogeneic hematopoietic cell transplantation (HCT). To clarify the impact of graft cell source on the incidence of BSI after transplantation, we retrospectively examined 782 adult patients receiving their first allogeneic HCT: 122 recipients of related peripheral blood stem cells or bone marrow, 215 recipients of unrelated bone marrow, and 445 recipients of unrelated umbilical cord blood (U-CB). The cumulative incidence of BSI was 42.5% at 100 days after transplantation (95% confidence interval, 39.0-46.0). Gram-positive cocci were present in 64.2% of detected isolates. Among the pre-transplant factors including age, performance status, primary disease, disease status, graft cell source, sex and ABO blood type matching, and the intensity of conditioning regimen, U-CB use was identified as the most significant risk factor for BSI by multivariate analysis (hazard ratio, 1.76; 95% confidence interval, 1.40-2.22; p < 0.00001). Among the U-CB recipients, those who are not in remission at the time of transplantation were at the greatest risk of BSI (hazard ratio, 1.69; 95% confidence interval, 1.14-2.50; p < 0.01). The study makes it clear that graft cell source has an impact on BSI development after allogeneic HCT.

Relapse of acute myeloid leukemia after allogeneic hematopoietic cell transplantation: clinical features and outcomes

Posttransplant relapse represents the greatest obstacle to the success of allogeneic hematopoietic cell transplantation (HCT) for patients with acute myeloid leukemia (AML). This study investigated clinical features and outcomes of posttransplant relapse of AML based on data for 1265 patients with AML suffering relapse after allogeneic HCT conducted during complete remission (CR). Relapse occurred at a median of 6.1 months. The incidence rate of relapse peaked at 29.0 per 100 patient-years during the first 3-6 months period post transplant, after which the rate declined over time, and after 3 years remained consistently at less than 1 per 100 patient-years. The probability of overall survival (OS) after posttransplant relapse was 19% at 2 years, with 68% of deaths being attributed to leukemia. The interval from transplantation to relapse was identified as the strongest indicator for OS. Donor lymphocyte infusion (DLI) and second allogeneic HCT (HCT2) were administered to 152 (12%) and 481 (38%) patients, respectively. Landmark analyses showed some signs of survival benefit when these procedures were performed during CR, but no benefit was gained when performed during non-CR. Our findings clarify clinical features of posttransplant relapse of AML, and indicate the urgent need for developing effective bridging to cellular therapies.

Effect of allogeneic HCT from unrelated donors in AML patients with intermediate- or poor-risk cytogenetics: a retrospective study from the Japanese Society for HCT

This study aimed to analyze the factors associated with outcomes of bone marrow transplantation (UR-BMT) or cord blood stem cell transplantation from unrelated donors (UR-CBT). We assessed the time from diagnosis to transplantation among acute myeloid leukemia (AML) patients with intermediate- or poor-risk cytogenetics to identify the potential clinical efficacy of transplantation. We retrospectively analyzed 5331 patients who received UR-BMT or UR-CBT between 2008 and 2017. Patients were divided into four groups according to time from diagnosis to transplantation: (1) UR-BMT and > 5 months (n = 2353), (2) UR-BMT and ≤ 5 months (n = 379), (3) UR-CBT and > 5 months (n = 1494), and (4) UR-CBT and ≤ 5 months (n = 1106). There was no difference in overall survival (OS) for transplantation at ≤5 months and > 5 months in patients with first complete remission for both UR-BMT and UR-CBT, but OS in patients with primary induction failure (PIF) and transplantation at ≤ 5 months was significantly higher in the UR-CBT group compared with that at >5 months (P < 0.001). Multivariate Cox regression analysis also showed that transplantation at >5 months in patients with PIF was an independent predictor of poorer OS. Therefore, UR-CBT at ≤ 5 months after diagnosis is an alternative option for AML patients with PIF.

Predicting non-relapse mortality following allogeneic hematopoietic cell transplantation during first remission of acute myeloid leukemia

The aim of this study was to develop a comprehensive system for predicting non-relapse mortality after allogeneic hematopoietic cell transplantation (HCT) during first complete remission (CR) of acute myeloid leukemia (AML). After dividing 2344 eligible patients randomly into a training set and a validation set, we first identified and scored five parameters, that is, age, sex, performance status, HCT-comorbidity index (HCT-CI), and donor type, on the basis of their impact on non-relapse mortality for patients in the training set. The non-relapse mortality-J (NRM-J) index using the sum of these scores was then applied to patients in the validation set, resulting in a clear differentiation of non-relapse mortality, with expected 2-year rates of 11%, 16%, 27%, and 33%, respectively (P < 0.001). The estimated c-statistic was 0.67, which was significantly higher than that of the European Society for Blood and Marrow Transplantation score (0.60, P = 0.002) and the HCT-CI (0.57, P < 0.001). The NRM-J index showed a significant association with overall survival, but not with relapse. Our findings demonstrate that the NRM-J index is useful for predicting post-transplant non-relapse mortality for patients with AML in first CR, for whom the decision of whether to perform allogeneic HCT is critical.