Nonablative versus reduced-intensity conditioning regimens in the treatment of acute myeloid leukemia and high-risk myelodysplastic syndrome: dose is relevant for long-term disease control after allogeneic hematopoietic stem cell transplantation

Busulfan plus fludarabine as a myeloablative conditioning regimen compared with busulfan plus cyclophosphamide for acute myeloid leukemia in first complete remission undergoing allogeneic hematopoietic stem cell transplantation: a prospective and multicenter study

Objective

We conducted a prospective, randomized, open-label, multicenter study to compare busulfan plus fludarabine (BuFlu) with busulfan plus cyclophosphamide (BuCy) as the conditioning regimen in allogeneic hematopoietic stem cell transplantation (allo-HSCT) for acute myeloid leukemia (AML) in first complete remission (CR1).

Methods

Totally 108 AML-CR1 patients undergoing allo-HSCT were randomized into BuCy (busulfan 1.6 mg/kg, q12 hours, -7 ~ -4d; cyclophosphamide 60 mg/kg.d, -3 ~ -2d) or BuFlu (busulfan 1.6 mg/kg, q12 hours, -5 ~ -2d; fludarabine 30 mg/m².d, -6 ~ -2d) group. Hematopoietic engraftment, regimen-related toxicity (RRT), graft-versus-host disease (GVHD), transplant related mortality (TRM), and overall survival were compared between the two groups.

Results

All patients achieved hematopoietic reconstitution except for two patients who died of RRT during conditioning. All patients obtained complete donor chimerism by day +30 post-transplantation. The incidence of total and III-IV RRT were 94.4% and 81.5% (P = 0.038), and 16.7% and 0.0% (P = 0.002), respectively, in BuCy and BuFlu group. With a median follow up of 609 (range, 3–2130) days after transplantation, the 5-year cumulative incidence of TRM were 18.8 ± 6.9% and 9.9 ± 6.3% (P = 0.104); the 5-year cumulative incidence of leukemia relapse were 16.5 ± 5.8% and 16.2 ± 5.3% (P = 0.943); the 5-year disease-free survival and overall survival were 67.4 ± 7.6% and 75.3 ± 7.2% (P = 0.315), and 72.3 ± 7.5% and 81.9 ± 7.0% (P = 0.177), respectively in BuCy and BuFlu group.

Conclusion

Compared with BuCy, BuFlu as a myeloablative condition regimen was associated with lower toxicities and comparable anti-leukemic activity in AML-CR1 patients undergoing allo-HSCT.

Pharmacological methods to reduce disease recurrence

Allogeneic stem cell transplantation is an increasingly important treatment option in patients with high-risk acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Although there has been substantial progress in reducing transplantation-related mortality (TRM), little progress has been made in reducing the risk of disease relapse, which continues to represent the major cause of treatment failure in patients allografted for AML and MDS. Experience with myeloablative conditioning regimens has demonstrated that, although intensification of the preparative regimen reduces relapse risk, any survival benefit is blunted by a concomitant increase in TRM. A similar inverse correlation between relapse risk and TRM is observed in patients allografted using a reduced-intensity conditioning regimen. However, the markedly lower toxicity of such regimens has permitted the design of novel conditioning strategies aimed at maximizing antitumor activity without excessive transplant toxicity. Coupled with recent advances in drug delivery and design, this has allowed the development of a spectrum of new conditioning regimens in patients with high-risk AML and MDS. At the same time, the optimization of a graft-versus-leukemia (GVL) effect by minimizing posttransplantation immunosuppression, with or without the infusion of donor lymphocytes, is essential if the risk of disease relapse is to be reduced. Recently, the delivery of adjunctive posttransplantation therapies has emerged as a promising method of augmenting antileukemic activity, either through a direct antitumor activity or consequent upon pharmacological manipulation of the alloreactive response. Taken together these advances present a realistic possibility of delivering improved outcome in patients allografted for high-risk AML or MDS.

Allo-HSCT for acute leukemia of ambiguous lineage in adults: the comparison between standard conditioning and intensified conditioning regimens

Knowledge concerning the clinical and biological characteristics of acute leukemia of ambiguous lineage (ALAL) is limited so that there has been a lack of uniformity in treatment. In this report, we retrospectively investigated the effect of intensified conditioning on adult ALAL undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). A total of 59 patients with ALAL (male in 37 cases and female in 22 cases) were consecutively enrolled in the data analyses. Twenty-four patients received the standard conditioning (total body irradiation (TBI) + cyclophosphamide (CY) or busulfan + CY protocol) and 35 received the intensified conditioning (TBI + CY + etoposide or fludarabine + cytarabine plus TBI + CY + etoposide protocol). Five-year transplant-related mortality was 17.6 ± 9.6 % and 25.5 ± 8.0 %, the 5-year overall survival (OS) post-transplantation was 23.8 ± 8.9 % and 64.0 ± 8.4 %, disease-free survival was 16.7 ± 7.6 % and 55.8 ± 9.4 %, the 5-year cumulative incidence of relapse was 80.8 ± 8.5 % and 28.8 ± 9.9 %, respectively, in the standard and the intensified group (P = 0.380, P = 0.029, P = 0.005, and P < 0.001). Both univariate and multivariate analysis indicated that the intensified conditioning regimen and acute graft-versus-host disease were favorable factors to reduce the relapse. The younger patients, patients with CR at the time of transplantation, and the intensified conditioning regimen were favorable factors to elevate the survival. In conclusion, intensified conditioning regimens followed by allo-HSCT might improve long-term survival and decrease relapse of leukemia in adult ALAL compared to the standard conditioning regimens.

Dose intensification of busulfan in the preparative regimen is associated with improved survival: a phase I/II controlled, randomized study

Dose intensity is important for disease control in patients undergoing allogeneic stem cell transplantation. We conducted a phase I/II controlled, adoptive, randomized study to determine the optimal dosing schedule of i.v. busulfan. Patients aged ≤75 years with advanced hematologic malignancies with human leukocyte antigen-compatible donor were eligible. All patients received fludarabine at 30 mg/m(2)/d for 4 days, and busulfan was administered in different doses in oral or i.v. formulations. As determined by the phase I trial, i.v. busulfan at a dose of 11.2 mg/kg/d was used for the phase II expansion cohort. Altogether, 80 patients with a median age of 56 years were enrolled. Forty percent had active disease at the time of transplantation. Engraftment occurred in 91%, and a complete response was achieved in 79% of patients posttransplantation. At a median follow-up of 91 months in the surviving patients, the outcomes for i.v. busulfan dose of 11.2 mg/kg/d versus other doses were as follows: nonrelapse mortality, 34% versus 23% (P = .4); cumulative incidence of relapse, 43% versus 68% (P = .02); relapse-free survival, 25% versus 9% (P = .017); and overall survival, 27% versus 9% (P = .02). We conclude that optimizing i.v. busulfan dose intensity in the preparative regimen may overcome disease-associated poor prognostic factors.

Randomized trial of myeloablative conditioning regimens: busulfan plus cyclophosphamide versus busulfan plus fludarabine

PURPOSE

We conducted a phase III randomized clinical trial to compare two myeloablative conditioning regimens for allogeneic hematopoietic cell transplantation (HCT) in patients with leukemia and myelodysplastic syndrome.

PATIENTS AND METHODS

After randomization, 64 patients received busulfan (3.2 mg/kg per day × 4 days) plus cyclophosphamide (60 mg/kg per day × 2 days; BuCy), and 62 patients received busulfan (same dose and schedule) plus fludarabine (30 mg/m(2) per day × 5 days; BuFlu).

RESULTS

The median age was 41 years (range, 17 to 59 years). Five patients in the BuFlu arm experienced graft failure (primary, n = 1; secondary, n = 4). At 4 weeks after HCT, the median percentage of recipient hematopoietic chimerism was significantly greater in the BuFlu arm (0% v 5.5%; P < .001), and complete donor chimerism was greater in the BuCy arm (97.2% v 44.4%; P < .001). Severe (grade 3 or higher) infection and gastrointestinal adverse events were significantly more common in the BuCy arm, but the frequencies of hepatic adverse events were similar in the two arms. Nonrelapse mortality was similar in the two arms, but the BuCy arm had better overall survival (OS), relapse-free survival (RFS), and event-free survival (EFS; OS at 2 years, 67.4% v 41.4%, P = .014; RFS, 74.7% v 54.9%, P = .027; EFS, 60.7% v 36.0%, P = .014).

CONCLUSION

Our results indicate that the BuFlu regimen is not a suitable replacement for the BuCy regimen in young adults who are eligible for myeloablative conditioning therapy for allogeneic HCT.

Allogeneic hematopoietic cell transplantation for MDS: for whom, when and how?

Hematopoietic cell transplantation (HCT) is currently the only treatment with curative potential for patients with myelodysplastic syndrome (MDS). However, treatment-related mortality and relapse have remained major barriers to uniform success. Therefore, important questions remain to be answered, such as whom to transplant, when and how. With reduced intensity conditioning (RIC) regimens, patients in their 70s and patients with comorbid conditions have been transplanted successfully, although the relapse incidence with this approach tends to be increased in comparison to high intensity regimens. Success rates are higher in patients transplanted at an early stage of their disease. Encouraging is the fact, that results with unrelated donors who are HLA-matched by high resolution typing are comparable to those achieved with HLA genotypically identical siblings. The establishment of cord blood as a source of stem cells, and the recent success with HLA-haploidentical related donors will allow the offering of HCT to virtually all patients. Dependent upon disease stage and characteristics, some 25% to 75% of transplanted patients will be cured. While 20%-30% of patients experience chronic medical problems after HCT, 70% report a "good to excellent" quality of life. New studies must focus on further reducing GVHD for all patients and on overcoming high relapse rates in patients with high risk disease.

Reduced-intensity hematopoietic stem cell transplants for malignancies: harnessing the graft-versus-tumor effect

Allogeneic hematopoietic cell transplantation combines the power of cytotoxic chemo/radiotherapy with the ability of the new immune system to seek out and destroy tumor cells. However, administration of such myeloablative transplants is fraught with risks, some of which are related to the intensive conditioning regimens. Reductions in the intensity of the administered cytotoxic therapy have demonstrated that under some circumstances, the burden of fighting tumor and enhancing stem cell engraftment can be shouldered mostly by the transplanted immune system. Reduced intensity has allowed a potentially curative therapy for hematologic malignancies to be offered to an expanded patient population. Ongoing research seeks to enhance the safety and power of this form of allogeneic immunotherapy.

Reduced-intensity conditioning versus standard conditioning before allogeneic haemopoietic cell transplantation in patients with acute myeloid leukaemia in first complete remission: a prospective, open-label randomised phase 3 trial

BACKGROUND

Reduced-intensity conditioning regimens have been developed to minimise early toxic effects and deaths after allogeneic haemopoietic cell transplantation. However, the efficacy of these regimens before this procedure has not been investigated in a randomised trial. In this prospective, open-label randomised phase 3 trial we compared a reduced-intensity fludarabine-based conditioning regimen with a standard regimen in patients with acute myeloid leukaemia in first complete remission.

METHODS

Patients were aged 18-60 years and had intermediate-risk or high-risk acute myeloid leukaemia (defined by cytogenetics) in first complete remission; an available HLA-matched sibling donor or an unrelated donor with at least nine of ten HLA alleles; and adequate renal, cardiac, pulmonary, and neurological function. Between Nov 15, 2004, and Dec 31, 2009, patients were randomly assigned (1:1, by a computer-based minimisation procedure that balanced patients for age, cytogenetic risk, induction therapy, and donor type) to receive either reduced-intensity conditioning of four doses of 2 Gy of total-body irradiation and 150 mg/m(2) fludarabine or standard conditioning of six doses of 2 Gy of total-body irradiation and 120 mg/kg cyclophosphamide. All patients were given ciclosporin and methotrexate as prophylaxis against graft-versus-host disease. Neither investigators nor patients were blinded to study treatment. Our primary endpoint was the incidence of non-relapse mortality, analysed in the intention-to-treat population. The trial is registered with ClinicalTrials.gov, number NCT00150878.

FINDINGS

The trial was stopped early on Dec 31, 2009, because of slow accrual of patients. 99 patients were randomly assigned to receive reduced-intensity conditioning and 96 to receive standard conditioning. The incidence of non-relapse mortality did not differ between the reduced-intensity and standard conditioning groups (cumulative incidence at 3 years 13% [95% CI 6-21] vs 18% [10-26]; HR 0·62 [95% CI 0·30-1·31]). Relapse incidence (cumulative incidence 3 years 28% [95% CI 19-38] vs 26% [17-36]; HR 1·10 [95% CI 0·63-1·90]), disease-free survival (3 year disease-free survival 58% [95% CI 49-70] vs 56% [46-67]; HR 0·85 [95% CI 0·55-1·32]), and overall survival (3 year overall survival 61% [95% CI 50-74] vs 58% [47-70]; HR 0·77 [95% CI 0·48-1·25]) did not differ significantly between groups. Grade 3-4 of oral mucositis was less common in the reduced-intensity group than in the standard conditioning group (50 patients in the reduced-intensity conditioning group vs 73 patients in the standard conditioning group); the frequency of other side-effects such as graft-versus-host disease and increased concentrations of bilirubin and creatinine did not differ significantly between groups.

INTERPRETATION

Reduced-intensity conditioning results in a similar incidence of non-relapse mortality and reduced toxic effects compared with standard conditioning without affecting survival outcomes, and thus could be preferentially used in patients younger than 60 years with acute myeloid leukaemia transplanted in first complete remission.

Fifty years of melphalan use in hematopoietic stem cell transplantation

Melphalan remains the most widely used agent in preparative regimens for hematopoietic stem cell transplantation (SCT). From its initial discovery more than 50 years ago, it has been gradually incorporated in the conditioning regimens for both autologous and allogeneic transplantations because of its myeloablative properties and broad antitumor effects as a DNA alkylating agent. Melphalan remains the mainstay conditioning for multiple myeloma and lymphomas, and it has been used successfully in preparative regimens of a variety of other hematological and nonhematological malignancies. The addition of newer agents to conditioning, such as bortezomib or lenalidomide for myeloma or clofarabine for myeloid malignancies, may improve antitumor effects for transplantation, whereas melphalan in combination with alemtuzumab may represent a backbone for future cellular therapy because of reliable engraftment and low toxicity profile. This review summarizes the development and the current use of this remarkable drug in hematopoietic SCT.

Effects of intensified conditioning on Epstein-Barr virus and cytomegalovirus infections in allogeneic hematopoietic stem cell transplantation for hematological malignancies

BACKGROUND

Intensified conditioning regimens (increasing the intensity of standard myeloablative conditioning) for hematological malignancies in allogeneic hematopoietic stem cell transplantation (allo-HSCT) could reduce the relapse rate of the underlying disease, but it might simultaneously increase the transplant-related mortality including the mortality of infections. To explore whether intensified conditioning affected Epstein-Barr virus (EBV) and cytomegalovirus (CMV) infections, 185 patients undergoing allo-HSCT were enrolled.

METHODS

A total of 104 cases received standard and 81 intensified conditioning. Cyclosporine A (CsA) withdrawal and/or donor lymphocyte infusion (DLI) were conducted in high-risk patients. The EBV-DNA and CMV-DNA levels of blood were monitored regularly by quantitative real-time polymerase chain reaction (RQ-PCR) and immune reconstitution of recipients were analyzed by flow cytometry.

RESULTS

The 3-year cumulative incidence of EBV viremia, EBV-associated diseases and mortality of EBV-associated diseases were 25.3% ± 4.6%, 10.5% ± 3.4% and 0.0% ± 0.0% in the standard group, compared with 45.6% ± 6.5%, 26.0% ±5.3% and 7.3% ± 3.1% in the intensified group (P = 0.002, P = 0.002, P = 0.008). The 3-year cumulative incidence of CMV viremia and CMV-associated diseases, mortality of CMV-associated diseases and incidence of bacterial and fungal infections were similar between the two groups (P = 0.855, P = 0.581, P = 0.933, P = 0.142, P = 0.182, respectively). Multivariate analysis showed that intensified conditioning was one of the risk factors for EBV viremia and EBV-associated diseases (P = 0.037, P = 0.037), but it had no effects on CMV infections. The percentage of CD4+ T cells and CD4+/CD8+ ratio at 3 months post-transplantation were lower in the intensified group (P = 0.032, P = 0.022). The 3-year OS and DFS in the standard group were 62.2% ± 5.8% and 60.6% ± 5.6%, compared with 51.6% ± 6.2% and 51.1% ± 5.9% in the intensified group (P = 0.029, P = 0.063).

CONCLUSIONS

Intensified conditioning represents a promising approach for high-risk hematological malignancies, although it affects early immune reconstitution of recipients and increases the incidence and mortality of EBV infections.

Prognostic factors in patients aged 50 years or older undergoing allogeneic hematopoietic stem cell transplantation for hematologic malignancy

We retrospectively analyzed patients aged C 50 years with hematologic malignancies who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) to identify preoperative variables predicting the outcome. There were 71 patients with a median age of 57 years (range: 50-63 years) who had acute leukemia (n = 53) or myelodysplastic syndrome (n = 18). Myeloablative conditioning was done in 35 patients and 36 patients had reduced-intensity conditioning. The 5-year overall survival rate (OS), cumulative relapse rate, and non-relapse mortality rate (NRM) were 45, 24, and 33%, respectively. According to multivariate analysis, high-risk disease (HR 3.50, 95% CI 1.43-8.56, P = 0.006), a hematopoietic cell transplantation comorbidity index (HCT-CI) score ≥ 3 (HR 4.41, 95% CI 1.31-14.77, P = 0.016), and an HLA-mismatched unrelated donor (HR 4.03, 95% CI 1.46-11.10, P = 0.007) were significant predictors of worse OS. Highrisk disease was also significantly associated with a higher cumulative relapse rate (HR 4.59, 95% CI 0.94-6.92, P = 0.065). Furthermore, an HCT-CI score ≥ 3 (HR 3.02, 95% CI 1.01-20.78, P = 0.048) and an HLA-mismatched unrelated donor (HR 3.02, 95% CI 1.04-8.74, P = 0.042) were risk factors for NRM. These results suggest that the disease risk, HCT-CI score, and donor type/histocompatibility are prognostic factors for elderly patients, while the conditioning regimen and age are not predictors.

Allogeneic stem cell transplantation for elderly patients with myelodysplastic syndrome

Allogeneic hematopoietic stem cell transplantation (SCT) is well accepted as a curative treatment approach for younger patients with myelodysplastic syndrome (MDS) and has become one of the most frequent indications for allogeneic SCT as reported to the Center for International Blood and Marrow Transplant Research. However, MDS patients are usually elderly with a median age of approximately 75 years at diagnosis. Large register studies have confirmed the feasibility of the procedure in elderly MDS patients; and in the register of the European Group for Blood and Marrow Transplantation, one-third of the allogeneic transplant procedures for MDS were performed in 2010 in patients older than 60 years. Despite its curative potential, its role in the treatment of elderly MDS patients is less defined. Because of the inherent complications of the transplantation leading to treatment-related mortality and the risk of relapse, a careful calculation of the benefit for each patient is mandatory, taking into account comorbidities, disease status, donor selection, and effective nontransplant therapies. Prospective multicenter studies are needed to define optimal intensity of the conditioning regimen, timing of transplantation within a treatment algorithm, including drug-based therapies, and posttransplant strategies to reduce the risk of relapse.

Comparison of new flu-bu12-tg conditioning with the standard bu-cy myeloablative regimen in patients undergoing allogeneic stem cell transplantation for acute myeloid leukemia

AIMS

This study compares the outcomes of patients with high-risk acute myeloid leukemia (AML) who underwent allogeneic stem cell transplantation (SCT) after conditioning combining busulfan (16 mg/kg orally) and cyclophosphamide (120 mg/kg intravenously) (BU-CY) with those allografted after administration of fludarabine (150 mg/m(2) intravenously), busulfan (12 mg/kg orally) and thymoglobulin (6 mg/kg intravenously) (FLU-BU12-TG).

MATERIAL AND METHODS

SCT after BU-CY and FLU-BU12-TG was performed in 21 and 10 AML patients. There were no significant differences between groups in number of patients treated in complete disease remission, gender, age, donors, CD34+, mononuclear cell (MNC) count in the graft and follow-up period. However, significantly more SCTs from unrelated (90% vs. 19%; p=0.00018) and HLA-mismatched donors (50% vs. 0%; p=0.0004) were performed in the FLU-BU12-TG group. The Cox proportional hazards model was used to assess the risk of post-transplant AML relapse and non-relapse mortality (NRM). The probability of post-transplant 2-year event-free survival (EFS) and overall survival (OS) were calculated using the Kaplan-Meier method.

RESULTS

No significant differences were found between the FLU-BU12-TG and BU-CY groups in risk of AML relapse (HR=1.036; 95% CI [0.102 - 10.47]; p=0.9), post-transplant NRM (HR=0.25; 95% CI [0.031 - 1.96]; p=0.18), 2-year EFS (89% vs. 43%; p=0.19) or OS (79% vs. 57%; p=0.23).

CONCLUSION

These pilot results demonstrate the efficacy of the new FLU-BU12-TG conditioning regimen in patients allografted for high-risk AML. This conditioning might become an alternative approach in patients at high risk of severe post-transplant complications after the standard BU-CY myeloablative regimen.

Reduced intensity allogeneic hematopoietic stem cell transplantation for MDS using tacrolimus/sirolimus-based GVHD prophylaxis

We report a consecutive series of 59 patients with MDS who underwent reduced-intensity hematopoietic stem cell transplantation (RI-HSCT) with fludarabine/melphalan conditioning and tacrolimus/sirolimus-based GVHD prophylaxis. Two-year OS, EFS, and relapse incidences were 75.1%, 65.2%, and 20.9%, respectively. The cumulative incidence of non-relapse mortality at 100 days, 1 year, and 2 years was 3.4%, 8.5%, and 10.5%, respectively. The incidence of grade II-IV acute GVHD was 35.4%; grade III-IV was 18.6%. Forty of 55 evaluable patients developed chronic GVHD; of these 35 were extensive grade. This RI-HSCT protocol produces encouraging outcomes in MDS patients, and tacrolimus/sirolimus-based GVHD prophylaxis may contribute to that promising result.

The outcome of allogeneic hematopoietic stem cell transplants without total body irradiation in pediatric patients with acute lymphoblastic leukemia: single centre experience

The most widely accepted conditioning regimen to allogeneic hematopoietic stem cell transplantation consists of total body irradiation, especially in patients affected by acute lymphoblastic leukemia (ALL). In this retrospective study, we report our experience on hematopoietic stem cell transplantation in 44 pediatric patients with acute lymphoblastic leukemia using a non-radiation-based conditioning regimen (busulfan/cyclophosphamide). Median age at transplantation was 12.5 years (range, 4 to 14 y). 39 out of 44 patients received transplants in complete remission. At a median follow-up of 390 days, the probabilities of 3-year disease-free survival and overall survival were 50% and 68%, respectively. Disease status of hematopoietic stem cell transplantation was the only significant variable affecting the overall survival. Acute and chronic graft-versus-host disease occurred in 23 (64%) and 12(18%) patients, respectively. Relapse was significantly higher among patients transplanted in advanced disease status. The results of the study indicate that non-radiation-based preparative regimens can be used in pediatric patients with ALL. However, well-designed comparative trials are needed to better clarify the difference between radiation and non-radiation-based conditioning regimens in pediatric ALL.

Phase II prospective study of treosulfan-based reduced-intensity conditioning in allogeneic HSCT for hematological malignancies from 10/10 HLA-identical unrelated donor

Different RIC regimens were evaluated prior to allo-HSCT in different hematological malignancies. We conducted this prospective study in adult patients with various hematological malignancies in order to evaluate the toxicity and efficacy of treosulfan-based conditioning, followed by allo-HSCT from 10/10 HLA-identical unrelated donors. Conditioning included treosulfan 12 g/m(2)/day i.v. (day -6 to day -4), fludarabine 30 mg/m(2)/day i.v. (day -6 to day -2), and ATG 2.5 mg/kg/day (day -2 to day -1). PBSC were used as HSC source. We included 56 patients (29 AML, 9 MM, 8 MDS, 6 CLL, 3 ALL, and 1 CML) with a median age of 57 years (18-65.5). Fifty-four (96%) patients engrafted; the cumulative incidence of aGVHD grade ≥II at 3 months reached 31%. The cumulative incidence of cGVHD at 18 months was 34% limited and 8% extensive. The median overall survival (OS) was not reached with a 3-year probability of 52%. The cumulative incidence of relapse at 3 years was 25%, and the cumulative incidence of transplant-related mortality (TRM) at 12 and 24 months was 20% and 23%, respectively. Treosulfan appears to be a good alternative for conditioning of MUD transplant patients with promising results in terms of OS, relapse, and TRM.

Allogeneic hematopoietic SCT in patients with AML following treosulfan/fludarabine conditioning

An alternative reduced-toxicity conditioning regimen for allogeneic transplantation, based on treosulfan and fludarabine, has recently been identified. The safety and efficacy of this new conditioning regimen has been investigated prospectively in patients with AML. A total number of 75 patients with AML in CR were treated with 3 × 14 g/m(2) treosulfan and 5 × 30 mg/m(2) fludarabine, followed by matched sibling or unrelated SCT. Patients were evaluated for engraftment, adverse events, GVHD, and for non-relapse mortality, relapse incidence, overall and disease-free survival (DFS). All patients showed primary engraftment of neutrophils after a median of 20 days. Non-hematological adverse events grade III-IV in severity included mainly infections (59%) and gastrointestinal symptoms (7%). Acute GVHD grade II-IV occurred in 21% and extensive chronic GVHD occurred in 16% of the patients. After a median follow-up of 715 days, the 2-year overall and DFS estimates were 61% and 55%, respectively. The 2-year incidences of relapse and non-relapse mortality reached 34% and 11%, respectively. In summary, our data confirm promising safety and efficacy of the treosulfan-based conditioning therapy in AML patients, ClinicalTrials.gov Identifier: NCT01063660.

Failure of hypomethylating agent-based therapy in myelodysplastic syndromes

Hypomethylating agents such as 5-azacytidine or decitabine have been a major breakthrough in the treatment of patients with myelodysplastic syndromes (MDS). They have been shown to improve transfusion requirements and to change the natural history of the disease. However, with increasing cumulative clinical experience, it has become apparent that these agents are not curative and have their own shortcomings. There is a subgroup of patients who do not respond to frontline therapy and a large, growing cohort of patients that lose response or progress while on hypomethylating agent-based therapy. There are no standard treatment options in this arena and it is therefore a focus of significant research interest. Since the mechanisms of resistance to hypomethylating agents are not known, selection of therapy is largely empiric but must take into account the age, comorbidities, and performance status of the patient, as well as the characteristics of the disease at the time of treatment failure. Higher intensity approaches and allogeneic stem cell transplant can yield improved response rates and long-term disease control but should be limited to a selected cohort of patients who can tolerate the treatment-related morbidities. For the majority of patients who likely will be better candidates for lower intensity therapy, several novel, investigational approaches are becoming available. Among these are newer nucleoside analogues, inhibitors of protein tyrosine kinases, molecules that interact with redox signaling within the cell, immunotherapy approaches, and others. Patients with MDS whose disease has failed to respond to hypomethylating agent therapy should be referred for clinical trials when available. As we learn more about the patterns and mechanisms of failure, the next challenge will be to determine which therapies are suitable for each individual patient.

Reduced-Intensity Conditioning Allogeneic Hematopoietic Cell Transplantation in Adults with Acute Myeloid Leukemia

Background

Acute myeloid leukemia (AML), whether de novo or arising from antecedent hematologic disorders in elderly patients, is less likely to be curable with standard chemotherapy regimens used for younger patients. Allogeneic hematopoietic cell transplantation (alloHCT) is currently the most efficient anti-leukemia treatment for AML and has shown a survival advantage in younger patients with intermediate- or poor-risk cytogenetics.

Methods

The authors review their experience as well as the published data regarding the role of reduced-intensity conditioning (RIC) alloHCT in adults with AML. MEDLINE/PubMed and EMBASE/Ovid were searched, as well as reference lists of relevant articles, conference proceedings, and ongoing trial databases.

Results

Elderly patients with AML have a poor survival for all cytogenetics subgroups (except for acute promyelocytic leukemia) and higher rates of transplant-related mortality with myeloablative alloHCT. RIC regimens have been shown to decrease procedure-related toxicity and have emerged as an attractive treatment modality in AML patients not suitable for myeloablative conditioning regimens. While prospective data comparing outcomes of AML patients undergoing RIC alloHCT vs conventional chemotherapy alone are not yet available, RIC alloHCT is a reasonable option for high-risk older patients and for younger AML patients with medical comorbidities who achieve a first or subsequent remission. The application of RIC for patients with refractory disease or untreated relapse as well as the use of alternative donors should be considered within the context of clinical trials.

Conclusions

RIC alloHCT is a safe and effective treatment modality in high-risk elderly AML patients and in younger AML patients with medical comorbidities.

In the absence of clinically significant graft vs. host disease, myeloablative conditioning may allow an effective graft vs. leukaemia effect

In AML, prevention of GvHD leads to better tolerance of myeloablative therapy. 66 individuals with AML in CR underwent myeloablative conditioning and transplantation with allogeneic PBPC grafts. Median presentation age was 44.5 years. Karyotyping was intermediate in 48% and of unfavourable risk in 36%. For GvHD prophylaxis, PBPC harvests were incubated ex vivo with anti CD52 antibodies. TRM at day 100 and 1 year was 9% and 17%. At a median of 1018 days 65% are alive. Grade >1 GvHD was seen in 11%. GvHD and adverse karyotype were associated with treatment failure. In younger patients preservation of the dose intensity may improve cure rates.

[Allogeneic hematopoietic stem cell transplantation in elderly]

Most of patients with hematological malignancies are elderly (more than 60  years). Allogeneic stem cell transplantation is an important and effective treatment for most of these diseases. However, the toxicity and the supposed frailty of elderly patients, have limited the applicability of allogeneic transplantation for these patients. Elderly patients are at high risk to develop life-threatening complications, if allogeneic transplantation is performed with myeloablative conditioning regimens and using bone marrow stem source. Since more than 10 years, reduced intensity conditioning regimen have been developed, allowing to overcome the age as contra-indication for allogeneic transplantation. On the other hand, it is the presence of comorbidities which identify frail patients. For these subjects, allogeneic transplantation should be not indicated. Furthermore, advances in the supportive care and the development of new molecules could allow to reduce the toxicity of myeloablative conditioning regimens and thus to offer more intensive regimens before transplantation also in elderly population.

Clofarabine and busulfan conditioning facilitates engraftment and provides significant antitumor activity in nonremission hematologic malignancies

Patients with hematologic malignancies not in remission before allogeneic hematopoietic stem cell transplantation (HSCT) have a poor prognosis. To improve the antitumor activity of conditioning, we combined clofarabine with myeloablative doses of busulfan in a phase 1/2 study in nonremission hematologic malignancies. Forty-six patients were enrolled, including 31 patients with nonremission acute myelogenous leukemia (AML). Patients had a median age of 53 years, with a median comorbidity index of 3. Donors were unrelated, HLA mismatched, or both in 59% of patients. Common grade III to IV nonhematologic toxicities included transient transaminitis (50%), mucositis (24%), hand-foot syndrome (13%), transient hypoxia (13%), nausea/vomiting (9%), and diarrhea (9%). All patients engrafted. Complete remission was achieved in 80% of all patients by day +30 and in 100% of AML patients without prior hematopoietic stem cell transplantation. Two-year nonrelapse mortality for all patients was 31%, and overall survival was 28%. In AML, the overall survival was 48% at 1 year and 35% at 2 years. These data suggest that clofarabine combined with myeloablative doses of busulfan is well tolerated, secures engraftment, and possesses significant antitumor activity, particularly in nonremission AML. This study is registered at www.ClinicalTrials.gov under identifier NCT00556452.

Reduced-toxicity conditioning with treosulfan and fludarabine in allogeneic hematopoietic stem cell transplantation for myelodysplastic syndromes: final results of an international prospective phase II trial

BACKGROUND

An alternative reduced-toxicity conditioning regimen for allogeneic transplantation, based on treosulfan and fludarabine, has recently been identified. The rationale for this study was to investigate the efficacy and safety of this regimen prospectively in patients with a primary myelodysplastic syndrome.

DESIGN AND METHODS

A total of 45 patients with primary myelodysplastic syndromes were conditioned with 3×14 g/m(2) treosulfan and 5×30 mg/m(2) fludarabine followed by allogeneic hematopoietic stem cell transplantation. Subtypes of myelodysplastic syndromes were refractory anemia with excess blasts-2 (44%), refractory cytopenia with multilineage dysplasia (27%), refractory anemia (9%), refractory anemia with ringed sideroblasts (4%), refractory cytopenia with multilineage dysplasia and ringed sideroblasts (4%), refractory anemia with excess blasts-1 (2%), and myelodysplastic syndrome with isolated del (5q) (2%). The myelodysplastic syndrome was unclassified in 7% of the patients. Forty-seven percent of the patients had a favorable karyotype, 29% an unfavorable one, and 18% an intermediate karyotype. Patients were evaluated for engraftment, adverse events, graft-versus-host disease, non-relapse mortality, relapse incidence, overall survival and disease-free survival.

RESULTS

All but one patient showed primary engraftment of neutrophils after a median of 17 days. Non-hematologic adverse events of grade III-IV in severity included mainly infections and gastrointestinal symptoms (80% and 22% of the patients, respectively). Acute graft-versus-host disease grade II-IV developed in 24%, and extensive chronic graft-versus-host disease in 28% of the patients. After a median follow-up of 780 days, the 2-year overall and disease-free survival estimates were 71% and 67%, respectively. The 2-year cumulative incidences of non-relapse mortality and relapse were 17% and 16%, respectively.

CONCLUSIONS

Our safety and efficacy data suggest that treosulfan-based conditioning therapy is a promising treatment option for patients with myelodysplastic syndromes. clinicaltrials.gov identifier: NCT01062490.

Long-term outcome of reduced-intensity allogeneic hematopoietic SCT in patients with AML in CR

A total of 36 consecutive patients with AML in CR underwent reduced-intensity allogeneic hematopoietic SCT (RISCT) with fludarabine and melphalan conditioning. All patients were ineligible for myeloablative transplantation because of age or comorbidity. In total, 30 patients were in first CR and six patients were in second CR. Donors were siblings in 21 (58%) patients and were unrelated in 15 (42%) patients. Hematopoietic cell transplant specific comorbidity scores ≥3 were present in 26 (72%) patients. With a median follow-up of 52 months (range, 34-103 months), OS and PFS rates at 4 years were 71% (s.e., 8%) and 68% (s.e., 8%), respectively. At 4 years, the cumulative incidence of non-relapse mortality was 20% (s.e., 7%) and of relapse mortality was 8% (s.e., 5%). Neither OS nor PFS was affected by older age (>60 years), unrelated donor, melphalan dose, or comorbidity score. At last follow up, of the 24 surviving patients, 21 (88%) had performance status (ECOG) of 0 without any active chronic GVHD requiring steroids. Hence, RISCT with fludarabine and melphalan conditioning produces durable long-term remission in older patients with AML.

Allogeneic immunotherapy to optimize the graft-versus-tumor effect: concepts and controversies

This article focuses on the recent evolution of novel conditioning regimens in combination with adoptive cellular therapy in the allogeneic transplant setting for hematologic malignancies. Building on data from animal models, the field of allogeneic transplantation is undergoing a paradigm shift toward immunosuppressive regimens with less toxicity that allow donor hematopoietic engraftment in order to provide a graft-versus-tumor effect as the primary goal of transplantation, rather than chemoablation. In addition, the strategies described in this article, including the use of T-cell subsets as adoptive therapy, will apply to a much broader pool of patients than traditional transplant approaches, thereby allowing more patients with life-limiting illnesses, previously deemed ineligible, to pursue therapy with curative intent.

Myeloablative reduced-toxicity i.v. busulfan-fludarabine and allogeneic hematopoietic stem cell transplant for patients with acute myeloid leukemia or myelodysplastic syndrome in the sixth through eighth decades of life

The optimal pretransplant regimen for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) in patients ≥ 55 years of age remains to be determined. The myeloablative reduced-toxicity 4-day regimen i.v. busulfan (Bu) (130 mg/m(2)) and i.v. fludarabine (Flu) (40 mg/m(2)) is associated with low morbidity and mortality. We analyzed 79 patients ≥ 55 years of age (median, 58 years) with AML (n = 63) or MDS (n = 16) treated with i.v. Bu-Flu conditioning regimens between 2001 and 2009 (median follow-up, 24 months). The patients who received this regimen had a good performance status. The 2-year overall survival (OS) rates for patients in first complete remission (CR1), second CR (CR2), or refractory disease and for all patients at time of transplantation were 71%, 44%, 32%, and 46%, respectively; 2-year event-free survival (EFS) rates for patients in CR1, CR2, or refractory disease at time of transplantation and for all patients were 68%, 42%, 30%, and 44%, respectively. One-year transplant-related mortality (TRM) rates for patients who were in CR or who had active disease at the time of transplantation were 19% and 20%, respectively. Grade II-IV acute graft-versus-host (aGVHD) disease was diagnosed in 40% of the patients. Our results suggest that age alone should not be the primary reason for exclusion from receiving myeloablative reduced-toxicity conditioning with i.v. Bu-Flu preceding transplantation in patients with AML/MDS.

Review of stem-cell transplantation for myelodysplastic syndromes in older patients in the context of the Decision Memo for Allogeneic Hematopoietic Stem Cell Transplantation for Myelodysplastic Syndrome emanating from the Centers for Medicare and Medicaid Services

Myelodysplastic syndromes (MDS) comprise a heterogeneous group of clonal hematopoietic stem-cell disorders that result in varying degrees of cytopenia and risk of transformation into acute leukemia. Allogeneic stem-cell transplantation (SCT) is the only known cure for this disease. The treatment is routinely used for younger patients, but only a minority of patients older than the age of 60 undergo this procedure. The overall MDS incidence is 3.3 per 100,000, but the incidence in patients older than age 70 is between 15 and 50 per 100,000. The median age at presentation is 76 years. Medicare-age patients 65 or older represent 80% of the total population receiving an MDS diagnosis. In the United States, one of the obstacles to SCT for older patients with MDS has been lack of third party reimbursement. On August 4, 2010, the Centers for Medicare and Medicaid Services released their Decision Memo for Allogeneic Hematopoietic Stem Cell Transplantation (HSCT) for Myelodysplastic Syndrome. This memo states: "Allogeneic HSCT for MDS is covered by Medicare only for beneficiaries with MDS participating in an approved clinical study that meets the criteria below…. " In this review, we will summarize what is known regarding the role of allogeneic SCT in older patients as well as other elements that should be included within clinical trials that can provide the evidence necessary to demonstrate that allogeneic SCT should be a covered benefit for Medicare beneficiaries.

Phase I trial and pharmacokinetic study of high-dose clofarabine and busulfan and allogeneic stem cell transplantation in adults with high-risk and refractory acute leukemia

We conducted a phase I trial to determine the maximum tolerated dose (MTD) of clofarabine with high-dose busulfan followed by allogeneic stem cell transplantation (SCT) in patients with high-risk and refractory acute leukemia. Patients received intravenous busulfan 0.8 mg/kg every 6 h on days -6 to -3 and clofarabine 30-60 mg/m(2) per day on days -6 to -2. Graft-versus-host disease prophylaxis included sirolimus plus tacrolimus (days -2 to +180). A total of 15 patients, median age 48 (30-58) years, with acute leukemia that was relapsed and refractory (n=8), primary refractory (n=6), or in CR2 (n=1), were treated at four clofarabine dose levels: 30 (n=3), 40 (n=3), 50 (n=3) and 60 mg/m(2) per day (n=6) with busulfan. All engrafted, and the MTD was not reached. Grades 3-4 non-hematological toxicities included vomiting (n=3), mucositis (n=9), hand-foot syndrome (n=1), acute renal failure (n=1) and reversible elevation of aspartate aminotransferase/alanine aminotransferase (n=10). The 1-year event-free survival was 53% (95% confidence interval: 33-86%), and the 1-year overall survival was 60% (95% confidence interval: 40-91%). Given the good tolerability and promising results, we recommend clofarabine 60 mg/m(2) per day × 5 days as a phase II dose in combination with busulfan (12.8 mg per kg total dose) for further study as a myeloablative regimen for allogeneic SCT for high-risk acute leukemia.

Hematopoietic stem cell transplantation for treatment of myleodysplastic syndromes

Allogeneic stem cell transplantation is a potentially curative treatment for myelodysplastic syndromes. Transplants are clearly indicated in patients with intermediate-2 and high risk disease; there is controversy regarding when transplantation should be performed in patients with low and intermediate-1 risk disease. Most patients with MDS are over age 65 and Medicare has recently provisionally approved transplants, but only when performed as part of a comparative clinical trial which still must be finalized. Nonmyeloablative preparative regimens allow treatment of older patients with MDS, and novel approaches are under evaluation to reduce the risk of relapse and treatment related morbidity and mortality.

Who is fit for allogeneic transplantation?

The use of allogeneic hematopoietic cell transplantation (HCT) has expanded progressively, facilitated by the increasing availability of unrelated donors and cord blood, and the inclusion of older patients as transplantation candidates. Indications remain diagnosis-dependent. As novel nontransplantation modalities have been developed concurrently, many patients come to HCT only when no longer responding to such therapy. However, patients with refractory or advanced disease frequently relapse after HCT, even with high-dose conditioning, and more so with reduced-intensity regimens as used for patients of older age or with comorbid conditions. Thus, patients with high-risk malignancies who have substantial comorbidities or are of advanced age are at high risk of both relapse and nonrelapse mortality and should probably not be transplanted. Being in remission or at least having shown responsiveness to pre-HCT therapy is generally associated with increased transplantation success. In addition, to handle the stress associated with HCT, patients need a good social support system and a secure financial net. They must be well informed, not only about the transplantation process, but also about expected or potential post-HCT events, including graft-versus-host disease and delayed effects that may become manifest only years after HCT.

Allogeneic hematopoietic cell transplantation for adults with acute myeloid leukemia: myths, controversies, and unknowns

Progress in the last decade has improved the understanding of leukemia biology. Molecular markers in combinations with cytogenetics have improved the risk stratification of acute myeloid leukemia (AML) and informed decision-making. In parallel, several important advances in the transplant field, such as better supportive care, improved transplant technology, increased availability of alternative donors, and reduced-intensity conditioning have improved the safety as well as access of allogeneic hematopoietic cell transplantation (HCT) for a larger number of patients. In this review, the positioning of HCT in the management of patients with AML is evaluated in view of changing risk/benefit ratios associated with both conventional treatments and transplantation, and some of the controversies are addressed in light of emerging data. Increasing data demonstrate outcomes of alternative donor transplantation approaching HLA-identical sibling donors in high-risk AML supporting the inclusion of alternative donors in trials of prospective studies evaluating post remission strategies for high-risk AML. The use of reduced-intensity conditioning has expanded the eligibility of HCT to older patients with AML, and outcome data are encouraging. Continued study of HCT versus alternative therapies is required to optimize patients' outcomes in AML.

Dose intensity of preparative regimens for acute myeloid leukemia - one-size-fits-all or tailor-made?

Both toxicity and leukemia eradication correlate with the intensity of the transplant preparative regimen. How much any specific patient benefits from increased dose intensity depends, in part, on his/her ability to tolerate higher-dose therapy and the status of the leukemia being treated. Newer tools that include not only age and performance status, but also comorbidity indices, are useful for predicting the ability of a patient to tolerate therapy and should allow for the development of models predicting risk/benefit ratios for the use of more or less intense preparative regimens for any specific patient. If attempts are made to build such models, recent transplant data should be used, since advances in ancillary transplant measures (including better approaches to infection management and treatment of graft-vs-host disease) have led to improved transplant outcomes over the last decade. Ultimately, the goal should be to create preparative regimens with greater antileukemic intensity but with minimal extramedullary toxicity.

Clofarabine ± fludarabine with once daily i.v. busulfan as pretransplant conditioning therapy for advanced myeloid leukemia and MDS

Although a combination of i.v. busulfan (Bu) and fludarabine (Flu) is a safe, reduced-toxicity conditioning program for acute myelogenous leukemia/myelodysplastic syndromes (AML/MDS), recurrent leukemia posttransplantation remains a problem. To enhance the conditioning regimen's antileukemic effect, we decided to supplant Flu with clofarabine (Clo), and assayed the interactions of these nucleoside analogs alone and in combination with Bu in Bu-resistant human cell lines in vitro. We found pronounced synergy between each nucleoside and the alkylator but even more enhanced cytotoxic synergy when the nucleoside analogs were combined prior to exposing the cells to Bu. We then designed a 4-arm clinical trial in patients with myeloid leukemia undergoing allogeneic stem cell transplantation (allo-SCT). Patients were adaptively randomized as follows: Arm I-Clo:Flu 10:30 mg/m(2), Arm II-20:20 mg/m(2), Arm III-30:10 mg/m(2), and Arm IV-single-agent Clo at 40 mg/m(2). The nucleoside analog(s) were/was infused over 1 hour once daily for 4 days, followed on each day by Bu, infused over 3 hours to a pharmacokinetically targeted daily area under the curve (AUC) of 6000 μMol-min ± 10%. Fifty-one patients have been enrolled with a minimum follow-up exceeding 100 days. There were 32 males and 19 females, with a median age of 45 years (range: 6-59). Nine patients had chronic myeloid leukemia (CML) (BC: 2, second AP: 3, and tyrosine-kinase inhibitor refractory first chronic phase [CP]: 4). Forty-two patients had AML: 14 were induction failures, 8 in first chemotherapy-refractory relapse, 7 in untreated relapse, 3 in second or subsequent relapse, 4 were in second complete remission (CR), and 3 in second CR without platelet recovery (CRp), 2 were in high-risk CR1. Finally, 1 patient was in first CRp. Graft-versus-host disease (GVHD) prophylaxis was tacrolimus and mini-methorexate (MTX), and those who had an unrelated or 1 antigen-mismatched donor received low-dose rabbit-ATG (Thymoglobulin™). All patients engrafted. Forty-one patients had active leukemia at the time of transplant, and 35 achieved CR (85%). Twenty of the 42 AML patients and 5 of 9 CML patients are alive with a projected median overall survival (OS) of 23 months. Marrow and blood (T cell) chimerism studies at day +100 revealed that both in the lower-dose Clo groups (groups 1+2) and the higher-dose Clo groups (groups 3+4), the patients had a median of 100% donor (T cell)-derived DNA. There has been no secondary graft failure. In the first 100 days, 1 patient died of pneumonia, and 1 of liver GVHD. We conclude that (1) Clo ± Flu with i.v. Bu as pretransplant conditioning is safe in high-risk myeloid leukemia patients; (2) clofarabine is sufficiently immunosuppressive to support allo-SCT in myeloid leukemia; and (3) the median OS of 23 months in this high-risk patient population is encouraging. Additional studies to evaluate the antileukemic efficacy of Clo ± Flu with i.v. Bu as pretransplant conditioning therapy are warranted.

Phase 1/2 trial of total marrow and lymph node irradiation to augment reduced-intensity transplantation for advanced hematologic malignancies

This phase 1/2 study assessed the augmentation of reduced-intensity conditioning (RIC) with total marrow and lymph node irradiation (TMLI), for peripheral blood stem cell transplantation, in patients with advanced hematologic disease. The regimen consisted of fludarabine 25 mg/m(2) per day for 5 days, melphalan 140 mg/m(2) for one day, and TMLI radiation at 150 cGy/fraction in 8 fractions over 4 days. Eligible patients were over 50 years old and/or had compromised organ function. Median age of the 33 evaluable patients was 55.2 years. Eighteen events of nonhematologic grade III or higher toxicities occurred in 9 patients. Day 30 and day 100 mortalities were 3% and 15%, respectively. Patients achieved myeloid and platelet engraftment at a median of 14 days after transplantation. Long-term toxicities occurred in 2 patients: hypokalemia and tremor, both grade III, on days 370 and 361 after transplantation. Fourteen patients died, 7 of relapse-related causes and 7 of non-relapse-related causes. With a median follow-up for living patients of 14.7 months, 1-year overall survival, event-free survival, and non-relapse-related mortality were 75%, 65%, and 19%, respectively. Addition of TMLI to RIC is feasible and safe and could be offered to patients with advanced hematologic malignancies who might not otherwise be candidates for RIC.

Targeted i.v. BU and fludarabine (t-i.v. BU/Flu) provides effective control of AML in adults with reduced toxicity

Myeloablative doses of BU and fludarabine followed by allogeneic hematopoietic cell transplantation offer effective therapy for AML. We anticipated that pharmacokinetic targeting of i.v. BU to 5300 μM/L min/day × 4 (targeted i.v. BU and fludarabine (t-i.v. BU/Flu)) would limit nonrelapse mortality (NRM) in adults up to 70 years of age. We assessed the safety and efficacy of t-i.v. BU/Flu in a series of 100 adults (median age 48, range 22-69 years) with AML in the first CR (CR1) with high risk of treatment failure (n=49), second CR (CR2, n=25), relapsed disease (REL, n=9), primary induction failure (PIF, n=16) and untreated (n=1). NRM was 3% at 100 days and 15% at 1 year. The cumulative incidence of relapse was 30.6% for CR1, 41.7% for CR2, 55.6% for REL and 58.6% for PIF. OS for primary AML in CR1 was 66% (95% confidence interval (CI): 46-80%) at 1 year, and 62% (95% CI: 42-77%) at 2 years. On multivariable modeling, remission status, moderate/severe chronic GVHD and day-90 BM chimerism ≥90% predicted improved OS. Importantly, there was no effect of age. t-i.v. BU/Flu provides effective disease control with encouraging NRM in patients up to age of 70 years.

High-risk myelodysplastic syndromes: chemotherapy, transplantation, and beyond

Allogeneic hematopoietic cell transplantation (HCT) has curative potential for patients with myelodysplastic syndromes (MDS), though with considerable nonrelapse mortality and morbidity. The International Prognostic Scoring System, despite its confines, remains a widely used tool guiding treatment decisions in MDS. The two hypomethylating agents, 5-azacytidine (azacitidine) and 5-aza-2-deoxycytidine (decitabine), are both effective in high-risk MDS, but about 50% of high-risk MDS patients fail to achieve a meaningful response, and these agents offer only a modest survival benefit, with a median response duration of 13 months. The more recent proposed risk models of MDS, as well as modern transplant strategies and expanded alternative donor sources, have helped to increase the number of patients offered curative treatment. As both drug therapy and HCT modalities evolve, treatment decisions are certain to become more complex. Current therapeutic options should view the hypomethylating agents as a way to optimize disease response before (and possibly after) HCT.