High activity of sorafenib in FLT3-ITD-positive acute myeloid leukemia synergizes with allo-immune effects to induce sustained responses

Preliminary evidence suggests that the multikinase inhibitor sorafenib has clinical activity in FLT3-ITD-positive (FLT3-ITD) acute myeloid leukemia (AML). However, the quality and sustainability of achievable remissions and clinical variables that influence the outcome of sorafenib monotherapy are largely undefined. To address these questions, we evaluated sorafenib monotherapy in 65 FLT3-ITD AML patients treated at 23 centers. All but two patients had relapsed or were chemotherapy-refractory after a median of three prior chemotherapy cycles. Twenty-nine patients (45%) had undergone prior allogeneic stem cell transplantation (allo-SCT). The documented best responses were: hematological remission in 24 patients (37%), bone marrow remission in 5 patients (8%), complete remission (with and without normalization of peripheral blood counts) in 15 patients (23%) and molecular remission with undetectable FLT3-ITD mRNA in 10 patients (15%), respectively. Seventeen of the patients without prior allo-SCT (47%) developed sorafenib resistance after a median treatment duration of 136 days (range, 56-270 days). In contrast, allo-SCT patients developed sorafenib resistance less frequently (38%) and significantly later (197 days, range 38-225 days; P=0.03). Sustained remissions were seen exclusively in the allo-SCT cohort. Thus, sorafenib monotherapy has significant activity in FLT3-ITD AML and may synergize with allogeneic immune effects to induce durable remissions.Leukemia advance online publication, 8 May 2012; doi:10.1038/leu.2012.105.

Autologous peripheral blood stem cell transplantation for acute myeloid leukemia

We report the results of a prospective, randomized phase 3 trial evaluating autologous peripheral blood stem cell transplantation (ASCT) versus intensive consolidation chemotherapy in newly diagnosed AML patients in complete remission (CR1). Patients with AML (16-60 years) in CR1 after 2 cycles of intensive chemotherapy and not eligible for allogeneic SCT were randomized between intensive chemotherapy with etoposide and mitoxantrone or ASCT ater high-dose cyclophosphamide and busulfan. Of patients randomized (chemotherapy, n = 259; ASCT, n = 258), more than 90% received their assigned treatment. The 2 groups were comparable with regard to prognostic factors. The ASCT group showed a markedly reduced relapse rate (58% vs 70%, P = .02) and better relapse-free survival at 5 years (38% vs 29%, P = .065, hazard ratio = 0.82; 95% confidence interval, 0.66-1.1) with nonrelapse mortality of 4% versus 1% in the chemotherapy arm (P = .02). Overall survival was similar (44% vs 41% at 5 years, P = .86) because of more opportunities for salvage with second-line chemotherapy and stem cell transplantation in patients relapsing on the chemotherapy arm. This large study shows a relapse advantage for ASCT as postremission therapy but similar survival because more relapsing patients on the chemotherapy arm were salvaged with a late transplantation for relapse. This trial is registered at www.trialregister.nl as #NTR230 and #NTR291.

Disruption of SIRPα signaling in macrophages eliminates human acute myeloid leukemia stem cells in xenografts

Although tumor surveillance by T and B lymphocytes is well studied, the role of innate immune cells, in particular macrophages, is less clear. Moreover, the existence of subclonal genetic and functional diversity in some human cancers such as leukemia underscores the importance of defining tumor surveillance mechanisms that effectively target the disease-sustaining cancer stem cells in addition to bulk cells. In this study, we report that leukemia stem cell function in xenotransplant models of acute myeloid leukemia (AML) depends on SIRPα-mediated inhibition of macrophages through engagement with its ligand CD47. We generated mice expressing SIRPα variants with differential ability to bind human CD47 and demonstrated that macrophage-mediated phagocytosis and clearance of AML stem cells depend on absent SIRPα signaling. We obtained independent confirmation of the genetic restriction observed in our mouse models by using SIRPα-Fc fusion protein to disrupt SIRPα-CD47 engagement. Treatment with SIRPα-Fc enhanced phagocytosis of AML cells by both mouse and human macrophages and impaired leukemic engraftment in mice. Importantly, SIRPα-Fc treatment did not significantly enhance phagocytosis of normal hematopoietic targets. These findings support the development of therapeutics that antagonize SIRPα signaling to enhance macrophage-mediated elimination of AML.

Patterns of molecular response to and relapse after combination of sorafenib, idarubicin, and cytarabine in patients with FLT3 mutant acute myeloid leukemia

BACKGROUND: FMS-like tyrosine kinase 3 (FLT3) is a class III receptor tyrosine kinase involved in hematopoietic progenitor cell development. Mutations of FLT3 have been reported in about a third of patients with acute myeloid leukemia (AML), and inhibitors of FLT3 are of clinical interest. Sorafenib is an orally active multikinase inhibitor with potent activity against FLT3 and the Raf/ERK/MEK kinase pathway. METHODS: We studied the patterns of molecular response and relapse in 18 patients with mutated FLT3 treated with the combination of sorafenib, idarubicin, and cytarabine. RESULTS: The median follow-up was 9 months. Sixteen patients achieved complete remission (CR), and the other 2 patients achieved CR but lacked platelet recovery for an overall response rate of 100%. Ten patients had their FLT3-mutated clone eradicated, with 6 patients who showed some residual FLT3-mutated cells, and 2 patients who showed persistent FLT3-mutated cells. The elimination of FLT3-mutated population at the time of morphologic CR, however, was not predictive of relapse. After a median follow-up of 9 months (range, 1-16 months), 10 (55%) patients had relapsed, with a median CR duration of 8.8 months (range, 1-9.5 months). By DNA sequencing, there was no evidence of an acquired FLT3 point mutation at the time of relapse in 7 patients tested, which suggested the presence of other mechanisms of sorafenib resistance. CONCLUSION: Sorafenib, combined with chemotherapy, is effective in attaining CR, but relapses still occur.

High-grade supraclavicular soft tissue sarcoma as secondary malignancy after successful treatment of acute myeloid leukemia: case report and literature review

It is well known that the treatment protocols for hematopoetic neoplasms carry a high risk of long-term oncogenicity. However, few reports have been published of sarcomas as secondary malignancies. An unusual case report of a soft tissue sarcoma appearing as a secondary cancer is presented, with a review of the published data. The present report involves a soft tissue sarcoma of the neck that occurred 18 years after curative treatment of acute myeloid leukemia by induction chemotherapy and bone marrow transplantation. Consecutive graft-versus-host disease affected the cervical skin. Soft tissue sarcomas appearing as secondary tumors are rare in oncology. The presented case describes the appearance of a sarcoma 18 years after curative treatment of acute myeloid leukemia. This is only the second case of this type reported in published studies.

Rapid and highly specific screening for NPM1 mutations in acute myeloid leukemia

NPM1 mutations, the most frequent molecular alterations in acute myeloid leukemia (AML), have become important for risk stratification and treatment decisions for patients with normal karyotype AML. Rapid screening for NPM1 mutations should be available shortly after diagnosis. Several methods for detecting NPM1 mutations have been described, most of which are technically challenging and require additional laboratory equipment. We developed and validated an assay that allows specific, rapid, and simple screening for NPM1 mutations. FAST PCR spanning exons 8 to 12 of the NPM1 gene was performed on 284 diagnostic AML samples. PCR products were visualized on a 2 % agarose E-gel and verified by direct sequencing. The FAST PCR screening method showed a specificity and sensitivity of 100 %, i.e., all mutated cases were detected, and none of negative cases carried mutations. The limit of detection was at 5-10 % of mutant alleles. We conclude that the FAST PCR assay is a highly specific, rapid (less than 2 h), and sensitive screening method for the detection of NPM1 mutations. Moreover, this method is inexpensive and can easily be integrated in the routine molecular diagnostic work-up of established risk factors in AML using standard laboratory equipment.

BIRC6 (APOLLON) is down-regulated in acute myeloid leukemia and its knockdown attenuates neutrophil differentiation

Background Inhibitors of apoptosis (IAPs) were intensively investigated in the context of cancer where they promote tumor growth and chemoresistence. Overexpression of the IAP BIRC6 is associated with unfavorable clinical features and negatively impacts relapse-free survival in childhood acute myeloid leukemia (AML). Currently, BIRC6 levels in adult primary AML have not been compared to the expression in normal myeloid cells. Thus, we compared for the first time BIRC6 levels in adult primary AML patient samples to normal myeloid cells and studied its regulation and function during neutrophil differentiation. Findings We found significantly lower BIRC6 levels in particular AML subtypes as compared to granulocytes from healthy donors. The lowest BIRC6 expression was found in CD34+ progenitor cells. Moreover, BIRC6 expression significantly increased during neutrophil differentiation of AML cell lines and knocking down BIRC6 in NB4 acute promyelocytic leukemia (APL) cells significantly impaired neutrophil differentiation, but not cell viability. Conclusion Together, we found an association of low BIRC6 levels with an immature myeloid phenotype and describe a function for BIRC6 in neutrophil differentiation of APL cells.

Azacytidine for acute myeloid leukemia in elderly or frail patients: A phase II trial (SAKK 30/07)

Abstract This phase II trial treated elderly or frail AML patients with single agent subcutaneous azacytidine at 100 mg/m(2), on 5 of 28 days for up to 6 cycles. Treatment was stopped for lack of response, or continued to progression in responders. Primary endpoint was response within 6 months. A response rate >34% was considered a positive trial outcome. From 9/2008-4/2010, 45 patients from 10 centres (median age 74 (55-86) years) were accrued. Patients received 4 (1-21) cycles. Best response was CR/CRi in 8 (18%; 95% CI: 8%-32%.), 0 (0%) PR, 7 (16%) hematologic improvement, 17 (38%) stable disease. Three nonresponding patients stopped treatment after 6 cycles, 31 patients had stopped early and 11 patients continued treatment for 8-21 cycles. Adverse events (grade >III) were infections (13), febrile neutropenia (14), thrombocytopenia (7), dyspnea (6), bleeding (5) and anemia (4 patients). Median overall survival was 6 months. Peripheral blood blast counts, grouped at 30% had a borderline significant association with response (p = 0.07). This modified azacytidine schedule is feasible for elderly or frail AML patients in an outpatient setting with moderate, mainly hematologic, toxicity and response in a proportion of patients, although the primary objective was not reached.

Addition of bevacizumab to chemotherapy in acute myeloid leukemia at older age: a randomized phase 2 trial of the Dutch-Belgian Cooperative Trial Group for Hemato-Oncology (HOVON) and the Swiss Group for Clinical Cancer Research (SAKK)

An urgent need for new treatment modalities is emerging in elderly patients with acute myeloid leukemia (AML). We hypothesized that targeting VEGF might furnish an effective treatment modality in this population. Elderly patients with AML were randomly assigned in this phase 2 study (n = 171) to receive standard chemotherapy (3 + 7) with or without bevacizumab at a dose of 10 mg/kg intravenously at days 1 and 15. In the second cycle, patients received cytarabine 1000 mg/m(2) twice daily on days 1-6 with or without bevacizumab. The complete remission rates in the 2 arms were not different (65%). Event-free survival at 12 months was 33% for the standard arm versus 30% for the bevacizumab arm; at 24 months, it was 22% and 16%, respectively (P = .42). The frequencies of severe adverse events (SAEs) were higher in the bevacizumab arm (n = 63) compared with the control arm (n = 28; P = .043), but the percentages of death or life-threatening SAEs were lower in the bevacizumab arm (60% vs 75% of SAEs). The results of the present study show that the addition of bevacizumab to standard chemotherapy does not improve the therapeutic outcome of older AML patients. This trial is registered as number NTR904 in The Nederlands Trial Register (www.trialregister.nl).

Deregulated expression of EVI1 defines a poor prognostic subset of MLL-rearranged acute myeloid leukemias: a study of the German-Austrian Acute Myeloid Leukemia Study Group and the Dutch-Belgian-Swiss HOVON/SAKK Cooperative Group

To evaluate the prognostic value of ecotropic viral integration 1 gene (EVI1) overexpression in acute myeloid leukemia (AML) with MLL gene rearrangements.

Comparative analysis of the value of allogeneic hematopoietic stem-cell transplantation in acute myeloid leukemia with monosomal karyotype versus other cytogenetic risk categories

To determine to what extent allogeneic hematopoietic stem-cell transplantation (alloHSCT) quantitatively reduces relapse in acute myeloid leukemia with monosomal karyotype (MK-AML) compared with alternative postremission therapy and how it compares with other cytogenetic subcategories.

ATRA resolves the differentiation block in t(15;17) acute myeloid leukemia by restoring PU.1 expression

Tightly regulated expression of the transcription factor PU.1 is crucial for normal hematopoiesis. PU.1 knockdown mice develop acute myeloid leukemia (AML), and PU.1 mutations have been observed in some populations of patients with AML. Here we found that conditional expression of promyelocytic leukemia-retinoic acid receptor alpha (PML-RARA), the protein encoded by the t(15;17) translocation found in acute promyelocytic leukemia (APL), suppressed PU.1 expression, while treatment of APL cell lines and primary cells with all-trans retinoic acid (ATRA) restored PU.1 expression and induced neutrophil differentiation. ATRA-induced activation was mediated by a region in the PU.1 promoter to which CEBPB and OCT-1 binding were induced. Finally, conditional expression of PU.1 in human APL cells was sufficient to trigger neutrophil differentiation, whereas reduction of PU.1 by small interfering RNA (siRNA) blocked ATRA-induced neutrophil differentiation. This is the first report to show that PU.1 is suppressed in acute promyelocytic leukemia, and that ATRA restores PU.1 expression in cells harboring t(15;17).

C/EBPalpha and the pathophysiology of acute myeloid leukemia

PURPOSE OF REVIEW: The transcription factor C/EBPalpha controls differentiation and proliferation in normal granulopoiesis in a stage-specific manner. Loss of C/EBPalpha function in myeloid cells in vitro and in vivo leads to a block to myeloid differentiation similar to that which is observed in malignant cells from patients with acute myeloid leukemia. The finding of C/EBPalpha alterations in subgroups of acute myeloid leukemia patients suggests a direct link between critically decreased C/EBPalpha function and the development of the disorder. RECENT FINDINGS: Conditional mouse models provide direct evidence that loss of C/EBPalpha function leads to the accumulation of myeloid blasts in the bone marrow. Targeted disruption of the wild type C/EBPalpha protein, while conserving the dominant-negative 30 kDa isoform of C/EBPalpha, induces an AML-like disease in mice. In hematopoietic stem cells C/EBPalpha serves to limit cell self-renewal. Finally, C/EBPalpha function is disrupted at different levels in specific subgroups of acute myeloid leukemia patients. SUMMARY: There is evidence that impaired C/EBPalpha function contributes directly to the development of acute myeloid leukemia. Normal myeloid development and acute myeloid leukemia are now thought to reflect opposite sides of the same hematopoietic coin. Restoring C/EBPalpha function represents a promising target for novel therapeutic strategies in acute myeloid leukemia.

Extramedullary relapse in acute promyelocytic leukemia treated with all-trans retinoic acid and chemotherapy

We analyzed the incidence, presenting features, risk factors of extramedullary (EM) relapse occurring in acute promyelocytic leukemia (APL) treated with all-trans retinoic acid (ATRA) and chemotherapy by using a competing-risk method. In total, 740/ 806 (92%) patients included in three multicenter trials (APL91, APL93 trials and PETHEMA 96) achieved CR, of whom 169 (23%) relapsed, including 10 EM relapses. Nine relapses involved the central nervous system (CNS) and one the skin, of which two were isolated EM relapse. In patients with EM disease, median WBC count was 26950/mm3 (7700-162000). The 3-year cumulative incidence of EM disease at first relapse was 5.0%. Univariate analysis identified age <45 years (P=0.05), bcr3 PML-RARalpha isoform (P= 0.0003) and high WBC counts (> or = 10,000/ mm3) (P<0.0001) as risk factors for EM relapse. In multivariate analysis, only high WBC count remained significant (P= 0.001). Patients with EM relapse had a poorer outcome since median survival from EM relapse was 6.7 months as compared to 26.3 months for isolated BM relapse (P=0.04). In conclusion, EM relapse in APL occurs more frequently in patients with increased WBC counts (> or = 10,000/mm3) and carries a poor prognosis. Whether CNS prophylaxis should be systematically performed in patients with WBC > or = 10,000/mm3 at diagnosis remains to be established.