Myeloablative Versus Reduced-Intensity Hematopoietic Cell Transplantation for Acute Myeloid Leukemia and Myelodysplastic Syndromes

Recent advances in the cellular and molecular understanding of myelodysplastic syndromes: implications for new therapeutic approaches

It has been more than 10 years since any new disease-modifying therapies have received regulatory approval for indications related to myelodysplastic syndromes (MDS). Advances in our collective biological understanding of MDS in the last decade, however, have made it possible to hope that effective therapeutics can be designed to improve MDS-associated cytopenias and patients' quality of life, and perhaps even delay clonal progression and extend survival. Classes of MDS-associated mutations and disordered biological pathways targeted by developmental therapeutics include the following: aberrant messenger RNA splicing, neomorphic enzymes in the citric acid cycle with oncogenic activity, overactivated tyrosine and serine-threonine kinases, epigenetic and chromatin remodeling alterations, abnormal telomere dynamics, and failed protection of DNA integrity. At present, treatments for MDS are usually administered as sequential monotherapy, but there is a trend toward clinical trials of combination therapies-in which new agents are added to a DNA hypomethylating agent backbone-for both upfront treatment and the treatment of relapsed/refractory disease. Agents in clinical trials for subsets of MDS include luspatercept, antibodies targeting CD33, isocitrate dehydrogenase inhibitors, deacetylase inhibitors, venetoclax, and immunotherapies designed to overcome immune checkpoint inhibition. These biologically based therapeutics, as well as the encouraging precedent of 7 new approvals by the US Food and Drug Administration in 2017 for the treatment of acute leukemia, offer the prospect that 10 more years will not elapse before another new therapy is approved for MDS.

Thiotepa-busulfan-fludarabine compared to busulfan-fludarabine for sibling and unrelated donor transplant in acute myeloid leukemia in first remission

Background

A preparatory regimen consisting of thiotepa-busulfan-fludarabine (TBF) has been associated with reduced relapse in patients with haematological malignancies after haploidentical and cord blood transplants; however, few data exist regarding TBF conditioning in sibling (MSD) and unrelated donor (URD) transplants for AML.

Results

Among patients receiving a myeloablative (MAC) regimen, TBF-MAC was associated with significantly lower relapse (HR 0.47, p = 0.005) however higher non-relapse mortality (NRM, HR 2.69, p < 10^–4) as compared to BF. This led to similar leukemia-free (LFS) and overall survival (OS) between the two regimens (LFS: p = 0.6; OS: p = 0.27). When we selected TBF-MAC patients receiving busulfan 9.6 mg/kg, NRM resulted still higher but no more significantly different as compared to BF-MAC with busulfan 12.8 mg/kg (HR 1.53, p = 0.12); despite the lower busulfan dose, relapse remained inferior with TBF-MAC (HR 0.45, p = 0.01), however no difference in survival could be demonstrated (LFS: p = 0.31; OS: 0.82). Among patients receiving a reduced-intensity (RIC) regimen, similar outcome was observed with TBF-RIC and BF-RIC (LFS: p = 0.77; OS: p = 0.88).

Conclusions

TBF-MAC as conditioning regimen for transplant from MSD and URD in AML patients in first remission provided stronger anti-leukemic activity but higher NRM as compared to BF-MAC, thus leading to similar survival. TBF-MAC with busulfan 9.6 mg/kg was associated with low relapse and acceptable NRM, however again with no survival benefit. TBF-RIC and BF-RIC resulted in comparable outcome.

Methods

We conducted a registry-based study comparing outcomes of patients with AML in first remission undergoing transplant from MSD or URD prepared with either TBF (n = 212) or BF (n = 2698) conditioning.

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.

A phase 1/2 study of rigosertib in patients with myelodysplastic syndromes (MDS) and MDS progressed to acute myeloid leukemia

This Phase 1/2, dose-escalating study of rigosertib enrolled 22 patients with higher-risk myelodysplastic syndromes (MDS) (n=9) and acute myeloid leukemia (AML; n=13) who had relapsed or were refractory to standard therapy and for whom no second-line therapies were approved. Patients received 3- to 7-day continuous intravenous infusions of rigosertib, an inhibitor of Ras-effector pathways that interacts with the Ras-binding domains, common to several signaling proteins including Raf and PI3 kinase. Rigosertib was administered at doses of 650-1700mg/m²/day in 14-day cycles. Initial dose escalation followed a Fibonacci scheme, followed by recommended phase 2 dose confirmation in an expanded cohort. Rigosertib was well tolerated for up to 23 cycles, with no treatment-related deaths and 18% of patients with related serious adverse events (AEs). Common AEs were fatigue, diarrhea, pyrexia, dyspnea, insomnia, and anemia. Rigosertib exhibited biologic activity, with reduction or stabilization of bone marrow blasts and improved peripheral blood counts in a subset of patients. Ten of 19 evaluable patients (53%) demonstrated bone marrow/peripheral blood responses (n=4 MDS, n=1 AML) or stable disease (n=3 MDS, n=2 AML). Median survival was 15.7 and 2.0 months for responders and non-responders, respectively. Additional studies of rigosertib are ongoing in higher-risk MDS (NCT00854646).

How to build an allogeneic hematopoietic cell transplant unit in 2016: Proposal for a practical framework

Allogeneic hematopoietic cell transplantation is part of the standard of care for many hematological diseases. Over the last decades, significant advances in patient and donor selection, conditioning regimens as well as supportive care of patients undergoing allogeneic hematopoietic cell transplantation leading to improved overall survival have been made. In view of many new treatment options in cellular and molecular targeted therapies, the place of allogeneic transplantation in therapy concepts must be reviewed. Most aspects of hematopoietic cell transplantation are well standardized by national guidelines or laws as well as by certification labels such as FACT-JACIE. However, the requirements for the construction and layout of a unit treating patients during the acute phase of the transplantation procedure or at readmission for different complications are not well defined. In addition, the infrastructure of such a unit may be decisive for optimized care of these fragile patients. Here we describe the process of planning a transplant unit in order to open a discussion that could lead to more precise guidelines in the field of infrastructural requirements for hospitals caring for people with severe immunosuppression.

Mixed phenotype acute leukemia: outcomes with allogeneic stem cell transplantation. A retrospective study from the Acute Leukemia Working Party of the EBMT

Mixed phenotype acute leukemias are infrequent and considered high risk. The optimal treatment approach and the role of allogeneic hematopoietic stem cell transplantation are not entirely clear. In this study, we investigated 519 patients with mixed phenotype acute leukemia in first complete remission who underwent allogeneic hematopoietic stem cell transplantation between 2000 and 2014, and who were reported to the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation (EBMT). Median age was 38.1 years (range 18–75). Cytogenetics classified 49.3% as poor risk. At three years, relapse incidence was 31.4% (26.9–35.9), non-relapse mortality was 22.1% (18.4–26.1), the leukemia-free survival was 46.5% (41.7–51.4), and the overall survival was 56.3% (51.5–61.2). At six months, 32.5% had developed acute graft-versus-host disease, while at three years, 37.5% had developed chronic graft-versus-host disease (32.6–42.3). In a multivariate analysis, age and year of transplant had a strong impact on outcome. Myeloablative conditioning using total body irradiation correlated with a better leukemia-free survival. Our study suggests that mixed phenotype acute leukemia is potentially sensitive to graft-versus-leukemia and thus can benefit from allogeneic hematopoietic stem cell transplantation with a potential for cure.

Hematopoietic Cell Transplantation for Myelofibrosis: the Dynamic International Prognostic Scoring System Plus Risk Predicts Post-Transplant Outcomes

Hematopoietic cell transplantation (HCT) provides potentially curative treatment for patients with myelofibrosis (MF). HCT outcomes are associated with the Dynamic International Prognostic Scoring System (DIPSS) risk scores. In the present study we analyzed results in 233 patients to determine if the DIPSS plus classification, which adds cytogenetics, thrombocytopenia, and RBC transfusion dependence as risk factors, would better predict post-HCT outcomes than the original DIPSS. Multivariate analysis showed that each risk parameter incorporated into the DIPPS plus model contributed to its predictive power of overall mortality, relapse-free survival, and nonrelapse mortality. The 5-year overall survival (OS), relapse, and treatment-related mortality (TRM) rates for patients with low/intermediate-1 risk MF were 78%, 5%, and 20%, respectively. The 5-year OS, relapse, and TRM rates for patients with high-risk MF were 35%, 28%, and 40%, respectively. The HCT-specific comorbidity index of 3 or greater was associated with higher nonrelapse and overall mortality and reduced relapse-free survival. The relapse incidence was significantly increased in older patients (HR, 3.02; P = .0007). With a median follow-up of 8 years 124 patients (53%) were surviving. The components of the DIPSS plus classification still have prognostic relevance after adjustment by the DIPSS classification. This information should enhance our ability to advise patients when making decisions regarding timing of transplant.

Comparison of Conditioning with Fludarabine/Busulfan and Fludarabine/Melphalan in Allogeneic Transplantation Recipients 50 Years or Older

The optimal conditioning regimen for elderly patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HCT) remains unclear. We retrospectively analyzed 1607 patients aged 50 years or older with acute myeloid leukemia (AML), acute lymphoblastic leukemia, or myelodysplastic syndrome (MDS) who underwent allo-HCT using fludarabine/busulfan (FB) or fludarabine/melphalan (FM) between 2007 and 2014. We compared the clinical outcomes among FB2 (busulfan at 6.4 mg/kg iv, n = 463), FB4 (busulfan at 12.8 mg/kg iv, n = 721), and FM140 (melphalan at 140 mg/m², n = 423). The nonrelapse mortality (NRM) rates in the FB4 and FM140 groups were higher than that in the FB2 group (hazard ratio [HR], 1.63 [P < .001]; and HR, 1.71 [P < .001], respectively). Conversely, the relapse rates in the FB4 and FM140 groups were lower than that in the FB2 group (HR, .73 [P = .011]; and HR, .56 [P < .001], respectively). There were no significant differences in overall survival (OS) among the FB2, FB4, and FM140 groups. The 3-year OS in patients with high-risk AML and MDS in the FM140 group (37.0% and 60.2%) were superior to those in the FB2 group (24.4% and 45.5%) and the FB4 group (24.6% and 40.6%) (P = .016 and P = .023), whereas there were no differences in OS in the other patients among the 3 groups. In conclusion, the lower rates of relapse in the FB4 and FM140 groups were largely offset by a worse NRM. However, FM140 might be associated with better OS in patients with high-risk AML and MDS.

Age does not adversely influence outcomes among patients older than 60 years who undergo allogeneic hematopoietic stem cell transplant for AML and myelodysplastic syndrome

Allogeneic hematopoietic stem cell transplant (AHSCT) outcomes data of older AML/myelodysplastic syndrome (MDS) patients are limited. We retrospectively evaluated consecutive patients ⩾60 years old with AML/MDS who underwent AHSCT between January 2005 and December 2014. The primary objectives were to determine nonrelapse mortality (NRM), relapse, relapse-free survival (RFS) and overall survival (OS) at 1 year post AHSCT. A total of 159 patients underwent AHSCT with a median age of 64 (range, 60-75) years. Of these, 103 patients (65%) had AML and 56 patients (35%) had MDS. At 1 year post AHSCT, grade III-IV acute GvHD and chronic GvHD occurred in 20.8% (95% confidence interval (CI), 14.9-27.5%) and 54.1% (95% CI, 46.0-61.5%) of patients, respectively. NRM, RFS, relapse rate and OS at 1 year post AHSCT were 25.3% (95% CI, 18.8-32.3%), 53.3% (95% CI, 46.1-61.7%), 21.4% (95% CI, 15.4-28.1%) and 56.4% (95% CI, 49.2-54.7%), respectively. High disease risk index was associated with poor RFS, OS and higher relapse rate (P<0.03), whereas non-thymoglobulin-based GvHD prophylaxis, higher comorbidity index (⩾3) and MDS were associated with higher NRM (P<0.03). Importantly, age did not have an adverse effect on NRM, relapse, RFS and OS. AHSCT was well tolerated. Hence, older age alone should not be considered a contraindication to AHSCT.

Myeloablative busulfan/cytoxan conditioning versus reduced-intensity fludarabine/melphalan conditioning for allogeneic hematopoietic stem cell transplant in patients with acute myelogenous leukemia

Fludarabine and melphalan (Flu/Mel) has emerged as a more tolerable chemotherapy-based conditioning regimen compared with busulfan and cyclophosphamide (Bu/Cy) for allogeneic stem cell transplant (allo-hematopoietic stem cell transplantation (HSCT)) patients with acute myelogenous leukemia (AML). We conducted a retrospective review of a single-institution database including patients with AML who received allo-HSCT following conditioning with Mel/Flu or Bu/Cy-based regimens. We performed descriptive statistical analysis to examine patient demographics and clinical outcomes. We identified 156 patients meeting criteria between 2005 and 2014. Overall, patients conditioned with Bu/Cy were significantly younger, but more likely to be treated in an earlier era than those receiving Flu/Mel. Regimen choice was not associated with relapse rates (RR), relapse-free survival (RFS), or overall survival (OS) on both univariate and multivariable analyses. Bu/Cy was associated with increased non-relapse mortality (NRM) on multivariable analysis. These findings demonstrate that Flu/Mel provides non-inferior disease control and could be an appropriate regimen for selected patients.

Outcomes of patients diagnosed with acute myeloid leukemia after solid organ transplantation

Organ transplant recipients are at an increased risk for subsequent cancer including acute myeloid leukemia (AML). Treatment of AML following solid transplantation represents a clinical challenge as most patients have significant comorbidities at the time of AML diagnosis. In this study, we evaluated the treatment and outcomes of patients who developed AML following solid organ transplantation at our institution and reviewed the literature on outcomes for these patients. The study cohort consisted of 14 patients (median age 66 years, range 52-77 years) with newly diagnosed AML following solid organ transplantation. The median interval time between solid organ transplantation and AML diagnosis was 72 months (range 15-368 months). Seven patients received standard induction chemotherapy, four patients received intermediate type therapy, and the remaining three patients were deemed not fit for therapy and received palliative and supportive care. Six of the 11 treated patients (55%) achieved complete remission (CR). The median overall survival (OS) for all patients was 6 months. The median OS for the patients who achieved complete remission after therapy was 17 months and 2 months for the remaining patients. Despite initial CR, relapse rates are still high, suggesting that alternative strategies for post-remission therapies are warranted.