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

Risk-adapted, treosulfan-based therapy with auto- and allo-SCT for relapsed/refractory aggressive NHL: a prospective phase-II trial

Since the outcome of relapsed/refractory aggressive non-Hodgkin's lymphoma (NHL) is highly variable, a risk-adapted treatment approach was evaluated. After two cycles of DHAP, patients received high-dose treosulfan/etoposide/carboplatinum (TEC) and autologous stem cell rescue. After TEC, low-risk patients with late relapse (>1 year after first CR who achieved CR after DHAP received no further treatment. Patients with late relapse who achieved CR or PR only after TEC underwent a second cycle of TEC. High-risk patients with early relapse/refractory disease received treosulfan/fludarabine followed by allogeneic transplantation. Rituximab was added in patients with B-cell lymphoma (86%). At entry, 36% of all 57 patients had refractory disease, 32% early and 32% late relapse. During DHAP treatment, progression occurred in 32% of patients. Of 33 patients who received TEC, 5 received second TEC and 15 allogeneic transplantation. Main toxicity after TEC was oral mucositis (CTC grades 3 and 4 in 50% and 13%, respectively). In total, 42% patients achieved CR. Median OS was 21.4 months for all patients and 32.6 for those who underwent allogeneic transplantation. International prognostic index (IPI) at study entry was highly discriminative at predicting OS (P<0.0001). Risk-adapted, treosulfan-based therapy with auto- and allo-SCT is feasible. Long-term survival is possible with allogeneic transplantation.

Combination of the Hematopoietic Cell Transplantation Comorbidity Index and the European Group for Blood and Marrow Transplantation score allows a better stratification of high-risk patients undergoing reduced-toxicity allogeneic hematopoietic cell transplantation

This study was conducted to determine whether the integration of the Hematopoietic Cell Transplantation Comorbidity Index (HCT-CI) and the European Group for Blood and Marrow Transplantation (EBMT) score would improve individual capacity for stratification of high-risk HCT candidates. A total of 442 consecutive patients receiving an allogeneic HCT after reduced-toxicity conditioning was included. Final HCT-CI and EBMT scores were calculated and validated. Then, patients were grouped into a 6-category new combination model according to the HCT-CI (0, 1 to 2, ≥ 3) and EBMT scores (0 to 3, 4 to 7), and the model's predictive capacity was also evaluated. Median HCT-CI and EBMT scores were 3 and 4, respectively. Increased HCT-CI was associated with higher 4-year nonrelapse mortality (NRM) and lower 4-year overall survival (OS), whereas a high EBMT score was associated with higher 4-year NRM. The HCT-CI showed a trend for a better predictive capacity than the EBMT score (c-statistic .6 versus .54, P = .1). According to the new model, patients within HCT-CI of 0 and HCT-CI of 1 to 2 groups had similar risk of NRM independently of their EBMT score. Within the HCT-CI ≥ 3 group, patients with low EBMT score showed lower NRM (25% versus 40%, P = .04) and a trend to higher OS (52% versus 36%, P = .06) than patients with a high EBMT score. Moreover, patients with HCT-CI ≥ 3 and EBMT score 0 to 3 had similar outcomes than those with HCT-CI of 1 to 2. In conclusion, the combination of HCT-CI and the EBMT score is feasible and might contribute to a better identification of high-risk patients, improving selection of best allogeneic HCT candidates.

Allogeneic hematopoietic stem cell transplantation for myelodysplastic syndromes

Allogeneic stem cell transplantation (SCT) is the only treatment with curative potential for myelodysplastic syndrome (MDS). The availability of SCT has been expanded with the introduction of reduced intensity conditioning for older patients and the use of alternative donors. Treatment-related mortality and relapse have remained major barriers to uniform success and there is a significant need for innovative approaches to improve these outcomes. Encouraging results have been reported for patients who lack a human leukocyte antigen-identical donor with the use of cord blood and haploidentical donors. Improved approaches for patient selection and optimization of the timing of SCT are needed. New prognostic classification schemas identify risk groups for disease outcomes and facilitate decisions with regard to SCT. Patients with intermediate-2 and high-risk disease and those with therapy-related MDS have a poor prognosis with alternative therapies; improved results have been reported with hematopoietic transplantation. The optimum timing for SCT is controversial in the era of hypomethylating agents. Initial conservative management is indicated for patients with low-risk disease. Hematopoietic transplantation remains the only curative treatment for patients with MDS and should be used before patients overtly progress to advanced disease. Failure to respond to hypomethylating agents does not adversely affect the outcome of SCT; these patients might achieve durable remissions with hematopoietic transplantation. Refined prognostic markers are needed to identify poor prognosis patients to guide patient selection for SCT, and novel transplantation approaches are required to reduce the risk of disease relapse and complications of the procedure.

Myelodysplastic syndromes: who and when in the course of disease to transplant

The myelodysplastic syndromes are clonal hematopoietic disorders for which hematopoietic stem cell transplantation remains the only curative therapy. The timing of transplantation, methods of disease risk stratification, patient selection, pretransplantation therapies, and preparative regimens have evolved over the years, resulting in increasing disease-free survival. In recent years, alternative donor sources have been demonstrated to be a viable alternative to traditional sibling and matched unrelated donor stem cell sources. Efforts at transplantation regimen development continue with the aim of maximizing the chances of cure with minimal toxicity and improved quality of life. Integrating new knowledge regarding disease biology will be critical to continue to improve the success of hematopoietic stem cell transplantation. Exciting areas of ongoing research that may lead to reductions in posttransplantation relapse rate include posttransplantation therapies such as DNA methyltransferase inhibitors, vaccine strategies, and donor lymphocyte infusions to enhance the GVL effect.

Pharmacology of dimethanesulfonate alkylating agents: busulfan and treosulfan

INTRODUCTION

Among the dimethanesulfonates, busulfan, in combination with other alkylating agents or nucleoside analogues, is the cornerstone of high-dose chemotherapy. It is used, and followed hematopoietic stem cell transplantation, for the treatment of various hematologic malignancies and immunodeficiencies. Treosulfan, which is a hydrophilic analogue of busulfan, was the first dimethanesufonate registered for the treatment of ovarian cancer. Recently, treosulfan has been investigated for the treatment of hematologic malignancies in combination with the same second agents before hematopoietic stem cell transplantation.

AREAS COVERED

This work reviews the pharmacological data of these two dimethanesulfonates alkylating agents. Specifically, the article looks at their chemistry, metabolism, anticancer activity, and their pharmacokinetics and pharmacodynamics.

EXPERT OPINION

Busulfan has been investigated widely for more than three decades leading to a large and precise handling of this agent with numerous studies on activity and pharmacokinetics and pharmacodynamics. In contrast, the behavior of treosulfan is still under investigation and not fully described. The complexity of treosulfan's metabolism and mechanism of action gives rise to the need of a deeper understanding of its pharmacological activity in a context of high-dose chemotherapy. Specifically, there is a great need to better understand its pharmacokinetics/pharmacodynamics relationship.

Allogeneic hematopoietic stem cell transplantation in thalassemia major: results of a reduced-toxicity conditioning regimen based on the use of treosulfan

Sixty thalassemia patients (median age, 7 years; range, 1-37) underwent allogeneic hematopoietic stem cell transplantation (HSCT) after a preparation combining thiotepa, treosulfan, and fludarabine. Before HSCT, 27 children were assigned to risk class 1 of the Pesaro classification, 17 to class 2, and 4 to class 3; 12 patients were adults. Twenty patients were transplanted from an HLA-identical sibling and 40 from an unrelated donor. The cumulative incidence of graft failure and transplantation-related mortality was 9% and 7%, respectively. Eight patients experienced grade II-IV acute GVHD, the cumulative incidence being 14%. Among 56 patients at risk, 1 developed limited chronic GVHD. With a median follow-up of 36 months (range, 4-72), the 5-year probability of survival and thalassemia-free survival are 93% and 84%, respectively. Neither the class of risk nor the donor used influenced outcome. This treosulfan-based preparation proved to be safe and effective for thalassemia patients given allogeneic HSCT.

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.

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.