Fludarabine and treosulfan compared with other reduced-intensity conditioning regimens for allogeneic stem cell transplantation in patients with lymphoid malignancies

Reduced-Intensity Compared to Nonmyeloablative Conditioning in Patients with Non-Hodgkin Lymphoma Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

Reduced-intensity conditioning (RIC) and nonmyeloablative (NMA) conditioning are preferred for patients with non-Hodgkin lymphoma (NHL) undergoing allogeneic hematopoietic stem cell transplantation (allo-HCT). Although prior studies have suggested that higher-intensity regimens in RIC-NMA conditioning are associated with inferior outcomes in patients with NHL, the optimal conditioning regimen remains unknown. We performed a retrospective single-center analysis to determine outcomes of adult patients with B cell and T cell NHL who underwent allo-HCT and received either RIC or NMA conditioning between March 2008 and December 2019. RIC regimens included fludarabine-cyclophosphamide-thiotepa-4 Gy-total body irradiation (Flu-Cy-TT-4Gy-TBI), fludarabine-melphalan (Flu-Mel), fludarabine-cyclophosphamide-4 Gy-total body irradiation (Flu-Cy-4Gy-TBI), and fludarabine-busulfan-4 (Flu-Bu-4). The NMA regimen comprised fludarabine-cyclophosphamide-2 Gy-total body irradiation (Flu-Cy-2Gy-TBI). The primary outcome was overall survival (OS); secondary outcomes included progression-free survival (PFS), nonrelapse mortality (NRM), and the incidence of acute and chronic graft-versus-host-disease (GVHD). Of 279 transplants recipients (median age, 58 years), 110 received RIC (55% Flu-Mel, 38% Flu-Cy-TT-4Gy-TBI, 6% Flu-Bu-4, 1% Flu-Cy-4Gy-TBI) and 169 received NMA conditioning with Flu-Cy-2Gy-TBI. With a median of 64 months of follow-up post-allo-HCT, there was no significant difference in OS between the NMA and RIC groups (median, not reached [NR] versus 103 months; P = .1), and this was maintained on multivariable analysis. Similarly, after adjustment for all independently significant covariates (age, Karnofsky Performance Status [KPS], Hematopoietic Cell Transplantation Comorbidity Index [HCT-CI], and disease histology), the regression analysis showed no significant difference in PFS with RIC compared to NMA conditioning (hazard ratio [HR] 1.38; 95% confidence interval [CI], .92 to 2.09; P = .24). On univariable analysis, there was no significant difference in NRM between the RIC and NMA arms (100-day estimate, 10.0% versus 1.8%; P = .5). After adjustment for age, ethnicity, KPS, HCT-CI, GVHD prophylaxis, and donor source, RIC conditioning was associated with a significantly higher incidence of NRM compared to NMA conditioning (HR, 2.61; 95% CI, 1.04 to 6.52; P = .039). On multivariable analysis, compared with the NMA arm, the RIC arm had higher rates of grade II-IV (HR, 2.25; 95% CI, 1.31 to 3.86; P = .002) and grade III-IV acute GVHD (HR, 5.62; 95% CI, 2.03 to 15.6; P < .001). The findings of this study suggest that NMA conditioning with Flu-Cy-TBI-2Gy may be considered over more intensive RIC regimens for patients with NHL undergoing allo-HCT.

Fludarabine melphalan versus fludarabine treosulfan for reduced intensity conditioning regimen in allogeneic hematopoietic stem cell transplantation: a retrospective analysis

Various reduced-intensity conditioning (RIC) regimens are used to decrease toxicity while providing comparable outcomes to myeloablative regimens. We compared toxicity and outcomes between two RIC regimens, fludarabine with melphalan (Flu-Mel) and fludarabine with treosulfan (Flu-Treo), retrospectively over a 10-year period in two donor groups, matched related donor (MRD)/matched unrelated donor (MUD) and haploidentical (Haplo) transplants. The study included 138 patients, of which 105 received MRD/MUD (Flu-Mel: 94, Flu-Treo: 11) and 33 Haplo (Flu-Mel: 17, Flu-Treo: 16) transplants. In the MRD/MUD group, 44 (47%) of patients who received Flu-Mel had grade 3/4 oral mucositis compared to 1 (9%) who received Flu-Treo (P = 0.02). Corresponding numbers in the Haplo group were 7 (41%) and 1 (6%). Grade 3/4 diarrhoea was more frequent with Flu-Mel than Flu-Treo in the Haplo group (41% vs 6%; P = 0.039), but not the MRD/MUD group. Median follow-up time for all patients was 4.8 years. Five-year OS in the MRD/MUD group was 62% with Flu-Mel versus 53% with Flu-Treo (P = 0.0694). Similarly, 5-year OS was 41% with Flu-Mel and 28% with Flu-Treo (P = 0.770) in the Haplo group. Severe mucositis and diarrhoea were significantly less frequent with Flu-Treo than Flu-Mel. Flu-Treo provided comparable outcomes to Flu-Mel in all donor transplants.

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

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) was not actively performed in elderly acute myeloid leukemia (AML) or myelodysplastic syndrome patients who are at a high-risk based on hematopoietic cell transplantation-specific comorbidity index (HCT-CI). The advent of reduced-intensity conditioning (RIC) regimens has made HSCT applicable in this population. However, the selection of appropriate conditioning is a major concern for the attending physician. The benefits of combination of treosulfan and fludarabine (Treo/Flu) have been confirmed through many clinical studies. Korean data on treosulfan-based conditioning regimen are scarce.

METHODS

A retrospective study was conducted to compare the clinical outcomes of allogeneic HSCT using RIC between 13 patients receiving Treo/Flu and 39 receiving busulfan/fludarabine (Bu/Flu).

RESULTS

In terms of conditioning-related complications, the frequency of ≥ grade 2 nausea or vomiting was significantly lower and the duration of symptoms was shorter in the Treo/Flu group than in the Bu/Flu group. The incidence of ≥ grade 2 mucositis tended to be lower in the Treo/Flu group. In the analysis of transplant outcomes, all events of acute graft versus host disease (GVHD) and ≥ grade 2 acute GVHD occurred more frequently in the Treo/Flu group. The frequency of Epstein-Barr virus reactivation was significantly higher in the Treo/Flu group (53.8% vs. 23.1%, P = 0.037). Non-relapse mortality (NRM) at 12 months was higher in the Treo/Flu group (30.8% vs. 7.7%, P = 0.035). Significant prognostic factors included disease type, especially secondary AML, disease status and high-risk based on HCT-CI, ≥ grade 2 acute GVHD, and cases requiring ≥ 2 immunosuppressive drugs for treating acute GVHD. In the comparison of survival outcomes according to conditioning regimen, the Bu/Flu group seemed to show better results than the Treo/Flu group (60% vs. 46.2%, P = 0.092 for overall survival; 56.4% vs. 38.5%, P = 0.193 for relapse-free survival). In additional analysis for only HCT-CI high-risk groups, there was no difference in transplant outcomes except that the Treo/Flu group tended to have a higher NRM within one year after transplantation. Survival outcomes of both groups were similar.

CONCLUSION

This study suggests that Treo/Flu conditioning may be an alternative to Bu/Flu regimen in elderly patients with high-risk who are not suitable for standard conditioning.

The role of allogeneic hematopoietic cell transplantation for chronic lymphocytic leukemia: A review

Although the use of allogeneic hematopoietic cell transplantation (HCT) for chronic lymphocytic leukemia (CLL) has declined with the development of novel targeted agents, it continues to play an important role for eligible patients with high-risk or heavily pretreated CLL who lack other treatment options. CLL is susceptible to a potent graft-versus-leukemia (GVL) effect which produces long-lasting remissions in 30-50% of transplanted patients. While allogeneic HCT is associated with significant risks of graft-versus-host disease (GVHD), infection, and non-relapse mortality (NRM), improvements in patient and donor selection, reduced intensity conditioning (RIC), GVHD prophylaxis, and supportive care have rendered this an increasingly safe and effective procedure in the current era. In this review, we discuss recent advances in allogeneic HCT for CLL, with a focus on the optimal evidence-based strategies to maximize benefit and minimize toxicity of this potentially curative cellular therapy.

Treosulfan plus fludarabine versus TEAM as conditioning treatment before autologous stem cell transplantation for B-cell Non-Hodgkin lymphoma

Conditioning with treosulfan and fludarabine (Treo/Flu) has been proven to be feasible and efficient in several types of malignancies before allogeneic hematopoietic stem cell transplantation (allo-HSCT). Given its favorable reduced toxicity profile, we introduced Treo/Flu as conditioning before autologous HSCT (auto-HSCT) in patients with B-cell Non-Hodgkin lymphoma (NHL). The aim of this study was to evaluate the efficacy and safety of Treo/Flu in comparison to TEAM. Fifty-seven patients with NHL received auto-HSCT after conditioning with either Treo/Flu (n = 22) or TEAM (n = 35). All patients achieved sustained engraftment. PFS, EFS and OS were not significant in both groups. Of note is that patients in the Treo/Flu group were less dependent on thrombocyte transfusions (p = 0.0082), significantly older (in median 11 years, p < 0.0001) and suffered less frequently from infectious complications (p = 0.0105), mucositis and stomatitis (p < 0.0001). This study is the first to present efficacy, feasibility, and safety of conditioning with Treo/Flu preceding auto-HSCT in patients with NHL. Since it demonstrated a lack of significant difference in comparison to TEAM conditioning it might be a valuable alternative especially in elderly patients with B-cell NHL and comorbidities. Further evaluation by prospective clinical trials is warranted.

Day 4 vs. day 12 G-CSF administration following reduced intensity peripheral blood allogeneic stem cell transplant

INTRODUCTION

Granulocyte colony-stimulating factor (G-CSF) hastens neutrophil engraftment and reduces infections after allogeneic hematopoietic cell transplant (alloHCT), yet the optimal start date is unknown. Additionally, concurrent G-CSF and methotrexate for graft-vs-host disease (GVHD) prophylaxis may potentiate myelosuppression, and prolonged G-CSF is costly. Our institution changed from day + 4 to day + 12 G-CSF initiation following reduced intensity (RIC) alloHCT with methotrexate GVHD prophylaxis.

METHODS

We retrospectively compared day + 4 and day + 12 G-CSF initiation after RIC alloHCT from 2017-2021. The primary endpoint was the time to neutrophil engraftment. Secondary endpoints included length of stay (LOS) and the time to platelet engraftment as well as the incidence of infectious events, acute GVHD (aGVHD), and mucositis.

RESULTS

Thirty-two patients were included in each group with similar baseline characteristics. We observed faster neutrophil engraftment (median 12 vs. 15 days, p = 0.01) and platelet engraftment (median 13 vs. 15 days, p = 0.026) with day + 4 vs. day + 12 G-CSF initiation. Median LOS was 23 days (range, 19-32) with day + 4 initiation vs. 24 days (21-30) with day + 12 (p = 0.046). The incidence of culture-negative febrile neutropenia (p = 0.12), any grade aGVHD (p = 0.58), and grade 2-4 mucositis (p = 0.8) were similar between groups.

CONCLUSION

Compared to day + 4, day + 12 G-CSF initiation following RIC alloHCT had a longer time to neutrophil and platelet engraftment. Day + 12 initiation also resulted in longer LOS, which while statistically significant, was potentially of limited clinical significance. These findings are hypothesis generating.

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

Introduction

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

Methods

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

Results

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

Conclusions

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

Outcomes of Fludarabine, Melphalan and Total Body Irradiation as a Reduced Intensity Conditioning Regimen in Matched Donor Allogeneic Peripheral Blood Stem Cell Transplantation

Fludarabine 30 mg/m²/d × 5 and melphalan 140 mg/m² × 1 (Flu-Mel140) is a commonly used reduced-intensity conditioning regimen. We hypothesized that addition of 200cGy total body irradiation (TBI) to Flu-Mel140 may improve antitumor activity and transplant outcomes. Primary objectives was overall survival (OS) at 3 years. Secondary objectives were to assess the cumulative incidences of acute and chronic GVHD, relapse-free survival (RFS), relapse rate, and nonrelapse mortality (NRM). We retrospectively evaluated outcomes of patients receiving Flu-Mel140-TBI followed by HLA-matched donor allogeneic hematopoietic stem cell transplantation (alloSCT) using peripheral blood stem cells. Eighty-one patients (median age, 58 years) underwent alloSCT between January 2008 and December 2018. Thirty-one percent of patients had a prior transplant, 32% had high or very-high disease risk index, and the donor was unrelated in 70% of patients. Grade 3 to 4 regimen-related toxicities were mucositis (37%), cardiac toxicity (17%), and renal toxicity (10%). The cumulative incidence of grade III to IV acute GVHD at day +100 was 24.7% and chronic GVHD at 1 year was 51.3%. Median follow-up for survival was 6.1 years. At 3 years, OS was 39.81%, RFS was 31.47%, and relapse rate was 30.5%. One-year NRM was 29.9%. Patients undergoing first transplantation experienced improved OS compared with second or beyond (63.08% versus 42.31%, P = .02). After adjusting for disease subtypes, age (≤55 versus 55), comorbidity index (CI), number of transplant and GVHD prophylaxis, multivariable analysis did not demonstrate any survival difference among disease subtypes. High CI (≥3) was predictive of adverse OS and NRM, whereas older age (>55 years) was associated with high NRM. Our study shows that Flu-Mel140-TBI seems feasible and provides durable disease control. Addition of TBI did not appear to improve outcomes compared to previously published reports of Flu-Mel140. Considerable NRM could result from the inclusion of patients with older age and prior transplants.

Association of Reduced-Intensity Conditioning Regimens With Overall Survival Among Patients With Non-Hodgkin Lymphoma Undergoing Allogeneic Transplant

Importance

Reduced-intensity conditioning and nonmyeloablative conditioning (RIC-NMAC) regimens are frequently used in allogeneic hematopoietic cell transplant (HCT) for non-Hodgkin lymphoma. However, the optimal RIC-NMAC regimen in allogeneic HCT for non-Hodgkin lymphoma is not known.

Objective

To investigate whether RIC-NMAC regimens at a higher end of the intensity spectrum are associated with increased nonrelapse mortality and lower overall survival compared with RIC-NMAC regimens at the lower end of the intensity spectrum in patients with non-Hodgkin lymphoma undergoing allogeneic HCT.

Design, Setting, and Participants

This cohort study used data from 1823 adult patients with non-Hodgkin lymphoma in the Center for International Blood and Marrow Transplant Research registry. Included patients underwent allogeneic HCT using matched related or unrelated donors between January 2008 and December 2016. Statistical analysis was performed from June 1, 2019, to February 10, 2020.

Interventions

Patients received 1 of 4 RIC-NMAC regimens: fludarabine-intravenous busulfan (Flu-Bu), approximately 6.4 mg/kg (n = 458); fludarabine-melphalan (Flu-Mel140), 140 mg/m2 (n = 885); fludarabine-cyclophosphamide (Flu-Cy) (n = 391); or Flu-Cy with 2 Gy total body irradiation (Flu-Cy-2GyTBI) (n = 89).

Main Outcomes and Measures

The primary outcome was overall survival. Secondary outcomes were nonrelapse mortality, incidence of relapse, progression-free survival, and the incidence of acute and chronic graft-vs-host disease (GVHD).

Results

Of 1823 patients, 1186 (65%) were male, with a mean (SD) age of 54.8 (9.9) years. The 4-year adjusted OS was 58% in the Flu-Bu cohort, 67% in the Flu-Cy-2GyTBI cohort, 49% in the Flu-Mel140 cohort, and 63% in the Flu-Cy cohort (P < .001). After adjustment for age, Karnofsky performance score, HCT comorbidity index, NHL subtype, remission status at HCT, and the use of antithymocyte globulin or alemtuzumab, the regression analysis showed a significantly higher mortality risk associated with Flu-Mel140 compared with Flu-Bu (hazard ratio [HR], 1.34; 95% CI, 1.13-1.59; P < .001). Compared with the Flu-Cy cohort, the Flu-Mel140 cohort had a higher risk of chronic GVHD (HR, 1.38; 95% CI, 1.15-1.65; P < .001). The Flu-Mel140 regimen was associated with a higher nonrelapse mortality risk (HR, 1.78; 95% CI, 1.37-2.31; P < .001) compared with the Flu-Bu regimen.

Conclusions and Relevance

The findings suggest that use of the more intense RIC-NMAC regimen, Flu-Mel140, may have a negative association with overall survival and may be associated with higher nonrelapse mortality. The Flu-Bu and Flu-Cy regimens with or without 2GyTBI regimens appeared to provide comparable overall survival.

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

Background

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

Aim

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

Methods

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

Results

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

Conclusion

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

Clinical Outcomes of Fludarabine and Melphalan With an 800 cGy Total Body Irradiation Conditioning Regimen in Patients With Refractory or Relapsed Aggressive Non-Hodgkin Lymphoma Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

INTRODUCTION

Allogeneic hematopoietic stem cell transplant with reduced-intensity conditioning is an effective therapeutic option for patients with refractory or relapsed aggressive non-Hodgkin lymphoma (NHL).

PATIENTS AND METHODS

We retrospectively evaluated survival outcomes and the efficacy of our fludarabine/melphalan/total body irradiation (TBI) (FMT) regimen. A total of 89 patients had received the FMT regimen from 2007 to 2017.

RESULTS

The majority of patients (n = 81; 91%) belonged to the histologic subtype of aggressive NHL. The estimated 3-year overall survival and disease-free survival for the entire cohort during a median follow-up of 31 months were 47.1% (95% confidence interval, 36%-57%) and 45.4% (95% confidence interval, 35%-56%), respectively. The cumulative incidence rates of relapse and non-relapse mortality at 3 years were 33.1% and 13.8%, respectively. In analyses of risk factors affecting survival outcomes, chemosensitive disease status at transplant (hazard ratio [HR], 2.45; P = .010), delayed relapse after first-line chemotherapy (HR, 2.101; P = .009), no grade III to IV acute graft-versus-host disease (HR, 11.212; P < .001), and mild chronic graft-versus-host disease (HR, 0.448; P = .016) were independent significant predictors of favorable overall survival. Also, similar parameters were related to favorable disease-free survival. All non-hematologic toxicities occurred within 50 days after allogeneic hematopoietic stem cell transplant, and most of the adverse events were tolerable and manageable with a < 30% incidence.

CONCLUSION

Our FMT regimen shows favorable transplant outcomes with relatively low-risk toxicities, so it may be a promising strategy for patients with relapsed or refractory aggressive NHL.

Pharmacokinetics and Pharmacodynamics of Treosulfan in Patients With Thalassemia Major Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

A treosulfan (Treo)-based conditioning regimen prior to hematopoietic stem cell transplantation (HSCT) has been successfully used in treating hematological malignant and nonmalignant diseases. We report Treo pharmacokinetics (PK) in patients with thalassemia major undergoing HSCT (n = 87), receiving Treo at a dose of 14 g/m² /day. Median Treo AUC and clearance (CL) was 1,326 mg*h/L and 10.8 L/h/m² , respectively. There was wide interindividual variability in Treo AUC and CL (64 and 68%) which was not explained by any of the variables tested. None of the Treo PK parameters were significantly associated with graft rejection or toxicity; however, Treo CL <7.97 L/h/m² was significantly associated with poor overall (hazard ratio (HR) 2.7, confidence interval (CI) (1.09-6.76), P = 0.032) and event-free survival (HR 2.4, CI (0.98-5.73), P = 0.055). Further studies in a larger cohort are warranted to identify the factors explaining the variation in Treo PK as well as to establish a therapeutic range of Treo for targeted dose adjustment to improve HSCT outcome.

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

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

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

Reduced-toxicity conditioning with fludarabine and treosulfan is a dose-intensive regimen with enhanced anti-leukemia effect and acceptable toxicity in AML/MDS. HLA-C regulates natural-killer (NK) cell function by inhibiting Killer immunoglobulin-like receptors (KIR) and is divided into C1 and C2 epitopes. The missing-ligand theory suggests that missing recipient KIR ligands drives NK-alloreactivity after SCT, in the absence of HLA-mismatch by activating unlicensed donor NK cells. We analyzed SCT outcomes in 203 patients with AML/MDS, median age 58 years, given SCT from matched-siblings (n = 97) or matched-unrelated donors (n = 106), using two treosulfan doses (total 36 or 42 g/m² ). 34% expressed one HLA-C group 1 allele (C1C1), 19% one HLA-C group 2 allele (C2C2), and 48% both KIR ligands (C1C2). Median follow-up was 48 months. 5-year relapse, nonrelapse mortality (NRM) and leukemia-free survival (LFS) rates were 38%, 27%, and 36%, respectively. Relapse rates were 43%, 45%, and 26% in patients expressing C1C1, C1C2, and C2C2 ligands, respectively (P = .03). Multivariate-analysis identified chemo-refractory disease (HR 3.1, P = .003), poor cytogenetics (HR 1.7, P = .08), female donor to male recipient (HR 0.4, P = .01) and C2C2 ligands (HR 0.4, P = .04) as independent factors predicting relapse. HLA-C ligands were not associated with GVHD or NRM. LFS was 33%, 30%, and 46%, respectively (P = .07). Chemorefractory disease (HR 3.1, P = .0004) and C2C2 group ligand (HR 0.6, P = .06) independently predicted LFS. Treosulfan dose did not predict any SCT outcome. In conclusion, missing HLA-C group 1 ligand is associated with reduced relapse risk, similar NRM and improved LFS, after HLA-matched SCT with treosulfan conditioning in AML/MDS.

Fludarabine/Busulfan versus Fludarabine/Melphalan Conditioning in Patients Undergoing Reduced-Intensity Conditioning Hematopoietic Stem Cell Transplantation for Lymphoma

There is at present little data to guide the choice of conditioning for patients with lymphoma undergoing reduced-intensity conditioning (RIC) allogeneic stem cell transplantation (SCT). In this study, we compared the outcomes of patients undergoing RIC SCT who received fludarabine and melphalan (FluMel), the standard RIC regimen used by the Spanish Group of Transplantation, and fludarabine and busulfan (FluBu), the standard RIC regimen used by the Dana-Farber Cancer Institute/Brigham and Women's Hospital. We analyzed 136 patients undergoing RIC SCT for lymphoma with either FluBu (n = 61) or FluMel (n = 75) conditioning between 2007 and 2014. Median follow-up was 36 months. The cumulative incidence of grades II to IV acute graft-versus-host disease (GVHD) was 13% with FluBu and 36% with FluMel (P = .002). The cumulative incidence of nonrelapse mortality (NRM) at 1 year was 3.3% with FluBu and 31% with FluMel (P < .0001). The cumulative incidence of relapse at 1 year was 29% with FluBu and 10% with FluMel (P = .08). The 3-year disease-free survival rate was 47% with FluBu and 36% with FluMel (P = .24), and the 3-year overall survival rate was 62% with FluBu and 48% with FluMel (P = .01). In multivariable analysis, FluMel was associated with a higher risk of acute grades II to IV GVHD (HR, 7.45; 95% CI, 2.30 to 24.17; P = .001) and higher risk of NRM (HR, 4.87; 95% CI, 1.36 to 17.44; P = .015). The type of conditioning was not significantly associated with relapse or disease-free survival in multivariable models. However, conditioning regimen was the only factor significantly associated with overall survival: FluMel conditioning was associated with a hazard ratio for death of 2.78 (95% CI, 1.23 to 6.27; P = .014) compared with FluBu. In conclusion, the use of FluBu as conditioning for patients undergoing SCT for lymphoma was associated with a lower risk of acute GVHD and NRM and improved overall survival when compared with FluMel in our retrospective study. These results confirm the differences between these RIC regimens in terms of toxicity and efficacy and support the need for comparative prospective studies.