Allogeneic stem cell transplantation for relapsed and refractory acute myeloid leukemia patients with 11q23 abnormalities

Allogeneic hematopoietic cell transplantation in adult acute myeloid leukemia with 11q23 abnormality: a retrospective study of the Adult Acute Myeloid Leukemia Working Group of the Japan Society for Hematopoietic Cell Transplantation (JSHCT)

An 11q23 abnormality presents in approximately 5% of adults with acute myeloid leukemia (AML) and is associated with adverse outcomes even after allogeneic hematopoietic cell transplantation (allo-HCT). To evaluate the outcomes and prognostic factors following allo-HCT for adult AML with 11q23 abnormality, we retrospectively analyzed the Japanese registration data of 322 adult AML patients with 11q23 abnormality who had received allo-HCT between 1990 and 2014. In total, the disease status at HCT was first complete remission (CR1) in 159 (49%) patients. The probability of overall survival and the cumulative incidence of relapse at 3 years were 44 and 44%, respectively. In the multivariate analysis, disease status beyond CR1 at the time of HCT was significantly associated with a higher overall mortality and relapse. The 11q23 fusion partner did not have a significant impact on survival. We also evaluated the prognostic value of minimal residual disease (MRD) status at HCT on transplant outcomes among hematological CR patients. MRD status at HCT was the significant prognostic indicator for hematological relapse and survival. These data suggested that allo-HCT offered a curative option for adult AML with 11q23 abnormality. Pretransplant MRD status was the significant prognostic indicator for relapse and survival in CR patients.

The DOT1L inhibitor pinometostat reduces H3K79 methylation and has modest clinical activity in adult acute leukemia

Pinometostat (EPZ-5676) is a first-in-class small-molecule inhibitor of the histone methyltransferase disrupter of telomeric silencing 1-like (DOT1L). In this phase 1 study, pinometostat was evaluated for safety and efficacy in adult patients with advanced acute leukemias, particularly those involving mixed lineage leukemia (MLL) gene rearrangements (MLL-r) resulting from 11q23 translocations. Fifty-one patients were enrolled into 6 dose-escalation cohorts (n = 26) and 2 expansion cohorts (n = 25) at pinometostat doses of 54 and 90 mg/m² per day by continuous intravenous infusion in 28-day cycles. Because a maximum tolerated dose was not established in the dose-escalation phase, the expansion doses were selected based on safety and clinical response data combined with pharmacodynamic evidence of reduction in H3K79 methylation during dose escalation. Across all dose levels, plasma pinometostat concentrations increased in an approximately dose-proportional fashion, reaching an apparent steady-state by 4-8 hours after infusion, and rapidly decreased following treatment cessation. The most common adverse events, of any cause, were fatigue (39%), nausea (39%), constipation (35%), and febrile neutropenia (35%). Overall, 2 patients, both with t(11;19), experienced complete remission at 54 mg/m² per day by continuous intravenous infusion, demonstrating proof of concept for delivering clinically meaningful responses through targeting DOT1L using the single agent pinometostat in MLL-r leukemia patients. Administration of pinometostat was generally safe, with the maximum tolerated dose not being reached, although efficacy as a single agent was modest. This study demonstrates the therapeutic potential for targeting DOT1L in MLL-r leukemia and lays the groundwork for future combination approaches in this patient population. This clinical trial is registered at www.clinicaltrials.gov as NCT01684150.

The Superiority of Allogeneic Hematopoietic Stem Cell Transplantation Over Chemotherapy Alone in the Treatment of Acute Myeloid Leukemia Patients with Mixed Lineage Leukemia (MLL) Rearrangements

BACKGROUND Acute myeloid leukemia (AML) patients with mixed lineage leukemia (MLL) gene rearrangements always had a very poor prognosis. In this study, we report the incidence of MLL rearrangements in AML patients using gene analysis, as well as the clinical significance and prognostic features of these rearrangements. MATERIAL AND METHODS This retrospective study took place from April 2008 to November 2011 in the People's Liberation Army General Hospital. A total 433 AML patients were screened by multiple nested reverse transcription polymerase chain reaction (RT-PCR) to determine the incidence of the 11 MLL gene rearrangements. There were 68 cases of MLL gene rearrangements, for a positive rate of 15.7%. A total of 24 patients underwent allogeneic hematopoietic stem cell transplantation (Allo-HSCT), and 34 patients received at least 4 cycles of chemotherapy. Ten patients were lost to follow-up. RESULTS The median follow-up was 29 months. The complete remission (CR) rate was 85.4%. The overall survival (OS) was 57.4±5.9 months for the Allo-HSCT group and 21.0±2.1 months for the chemotherapy group. The Allo-HSCT group had superior survival compared with the chemotherapy group (5-year OS: 59±17% vs. 13±8%, P<0.01; 5-year disease-free survival [DFS]: 65±10% vs. 40±16%, P>0.05). Multivariate analysis showed that transplantation, platelets >50×10^9/L at onset, and CR are associated with a better OS in MLL rearranged AML patients. Patients with thrombocytopenia and extramedullary involvement were prone to relapse. CONCLUSIONS Our results suggest that Allo-HSCT is superior to chemotherapy alone for treating MLL rearranged AML patients. Patients treated with Allo-HSCT have a better prognosis and a longer survival. CR is an independent prognostic factor for OS, and extramedullary involvement is an independent prognostic factor for DFS. MLL rearranged AML patients with thrombocytopenia at onset <50×10^9 had very bad OS and DFS.

Mixed lineage rearranged leukaemia: pathogenesis and targeting DOT1L

PURPOSE OF REVIEW

The purpose of this study is to explore the recent advances in understanding the pathogenesis of leukaemias with a translocation involving the mixed lineage leukaemia (MLL) gene and therapeutic implications of these discoveries.

RECENT FINDINGS

The pathogenesis of MLL-rearranged leukaemias has recently been elucidated in a flurry of clinical studies that have appeared over the past 5 years. On the basis of these studies, a phase 1 clinical trial has been initiated targeting the histone methyltransferase DOT1L with interim clinical results reported at the American Society of Hematology Annual Meeting in December 2014.

SUMMARY

Acute leukaemia, both myeloid and lymphoid, that harbours a translocation involving the MLL gene at chromosome locus 11q23 has a poor prognosis, even with allogeneic bone marrow transplantation. The pathogenesis of MLL translocated leukaemias has recently been linked to aberrant activity of the histone methyltransferase DOT1. Preclinical studies of DOT1L inhibition with potent, selective inhibitors have shown successful eradication of the leukaemic clone in animal models. On the basis of these studies, a phase 1, first in man, clinical trial has been initiated with a DOT1L inhibitor, EPZ-5676.

Outcome of allogeneic hematopoietic stem-cell transplantation for adult patients with AML and 11q23/MLL rearrangement (MLL-r AML)

Acute myeloid leukemia (AML) with 11q23/MLL rearrangement (MLL-r AML) is allocated to the intermediate- or high-risk cytogenetic prognostic category depending on the MLL fusion partner. A more favorable outcome has been reported in patients receiving an allogeneic hematopoietic stem-cell transplantation (alloHSCT), but this has not been confirmed in large series. We analyzed the outcome of alloHSCT among adult patients reported to the Acute Leukemia Working Party between 2000 and 2010. We identified 159 patients with 11q23/MLL rearranged AML allografted in first complete remission (CR1, n=138) or CR2, mostly corresponding to t(9;11), t(11;19), t(6;11) and t(10;11) translocations. Two-year overall survival (OS), leukemia-free survival (LFS), relapse incidence and non-relapse mortality were 56±4%, 51±4%, 31±3% and 17±4%, respectively. The outcome differed according to 11q23/MLL rearrangement, being more favorable in patients with t(9;11) and t(11;19) compared with t(10;11) and t(6;11) (2-year OS: 64±6% and 73±10% vs 40±13% and 24±11%, respectively; P<0.0001). Multivariate analysis for OS identified t(6;11), t(10;11), age>40 years and CR2 as unfavorable features, whereas t(6;11), t(10;11), CR2 and the use of reduced-intensity conditioning regimen affected poorly the LFS. This study confirms the potential role of alloHSCT for adult patients with 11q23/MLL rearranged AML in CR1.

Efficacy of myeloablative allogeneic hematopoietic stem cell transplantation in adult patients with MLL-ELL-positive acute myeloid leukemia

Acute myeloid leukemia (AML) with mixed lineage leukemia-eleven-nineteen lysine-rich leukemia (MLL-ELL) is a rare subtype of MLL-rearranged AML. The outcome of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for patients with this disease remains unknown. In the present study, we retrospectively investigated the efficacy of allo-HSCT in eight adult MLL-ELL-positive AML patients. Although all eight patients achieved first complete remission (CR1), three (37.5 %) patients experienced relapse after induction therapy. Five (62.5 %) patients underwent allo-HSCT during CR1, whereas two (25.0 %) underwent allo-HSCT during disease relapse, and one (12.5 %) during CR2. All three patients who received allo-HSCT beyond CR1 died due to AML progression after allo-HSCT. Of the five patients who received allo-HSCT during CR1, three (60.0 %) remained alive at study conclusion. The overall survival rate at five years was 50.0 %. Intriguingly, clonally expanded non-leukemic cells expressing MLL-ELL during consolidation therapy were found to be eradicated after allo-HSCT during the monitoring of minimal residual disease in one patient; this indicates that allo-HSCT is efficacious for eliminating pre-leukemic cells resistant to chemotherapy. In conclusion, allo-HSCT soon after CR1 represents a promising therapeutic option for adult AML patients with MLL-ELL, although the outcome of allo-HSCT for patients beyond CR1 was dismal.

Therapy-related Leukemia and Myelodysplasia: Evolving Concepts of Pathogenesis and Treatment

Therapy-related leukemia and therapy-related myelodysplasia (t-AML/MDS) are serious and increasingly frequent complications of cytotoxic chemotherapy and/or radiotherapy. Two syndromes can be distinguished, one of which has a long latency (5-7 years or more) and is seen following alkylating agents, frequently with an antecedent dysplastic phase. The other has a short latency period (1-3 years), no antecedent dysplastic phase, and is characteristically seen following topoisomerase II inhibitors. Chromosomal abnormalities can confirm t-leuk/MDS and are predictive of poor prognosis, particularly those involving gains and losses of chromosome 7. There is no standard therapy for t-AML/MDS. This review concentrates on the various treatment approaches for t-AML/MDS. Treatment can be aggressive, with curative intent, particularly for patients who are young with no end-organ damage from the prior malignancy or chemotherapy. Various chemotherapy regimens have been designed to overcome the chemoresistance which is generally characteristic of these syndromes. Bone marrow transplantation offers the best chance for cure, and both myeloablative and nonmyeloablative protocols have been designed. Low dose chemotherapy is an option for patients not able to withstand traditional curative regimens and supportive care is a legitimate option for elderly or infirm patients. Multicenter studies are urgently needed to provide data on which clearcut treatment guidelines can be based, taking into account the patient's age, disease status and risk factors.

Adult de novo acute myeloid leukemia with t(6;11)(q27;q23)

BACKGROUND

Acute myeloid leukemia (AML) with t(6;11)(q27;q23) is a well established but rare entity, and few studies have reported the full clinical, hematologic, and outcome data of patients with this disease.

METHODS

To characterize the features of t(6;11) AML, the authors searched the Cancer and Leukemia Group B (CALGB) cytogenetic database comprising 2667 adults with newly diagnosed, de novo AML and identified 16 patients (0.6%) with t(6;11). A review of the literature identified 33 adults with de novo t(6;11) AML for whom survival data were available.

RESULTS

CALGB patients had a median age of 45 years (range, 22-65 years) and commonly presented with French-American-British (FAB) subtype M4 or M5 (81%). Gingival involvement at presentation was common (31%). All patients with gingival involvement had FAB M4. Compared with other patients with M4 AML in the CALGB database (n = 429), patients with M4 and t(6;11) (n = 7) had a higher frequency of gingival hypertrophy at presentation (71% vs. 17%, P = 0.003). Patients with t(6;11) were more likely to be African American (P = 0.02) and to die during induction (P = 0.03) than those without t(6;11). The complete response (CR) rate was 69% (11 of 16 patients), and CR duration was short (median, 9 months). The estimated probability of 2-year survival was 13%. Both long-term survivors received allogeneic stem cell transplantation. The estimated probability of 2-year survival of patients reported in the literature was 15%.

CONCLUSIONS

Although the patient sample was small, the authors suggested that investigational approaches, including allogeneic transplantation, be considered for adults with t(6;11) AML.