Drug resistance in acute myeloid leukemia : Pharmacokinetic and in vitro studies

Chemotherapy has improved clinical outcome in adult acute myeloid leukemia (AML) but still the majority of the patients die of their disease. One important explanation is transport mediated drug resistance resulting in refractory or relapsing disease. P-glycoprotein (Pgp) is located in the membrane and can extrude cytostatic drugs. This will cause a reduction of intracellular concentrations of the drug and reduce the effect on the leukemic cells. Down regulation of the enzyme topoisomerase II alpha (topo II alpha) is another resistance mechanism. The aim of the first part of this thesis was to study effects of interaction with transport mediated resistance. In a phase I-II pharmacokinetic study 22 de novo AML patients were included and received a high single dose of mitoxantrone (30 or 40 mg/m2) in combination with ara-C. In the leukemic cells we found a high accumulation of mitoxantrone which, in contrast to plasma, remained stable during the 48 hours studied. Compared with previous results with mitoxantrone 12 mg /m2 the area under the curve (AUC) for intracellular concentrations was increased by 150% (30 mg/m2) and 260% (40 mg/m2) respectively. The toxicity was acceptable but a prolonged duration of neutropenia was noted. Several studies have shown that Pgp can be blocked and in the next study 10 AML patients were included and given a continuos infusion of daunorubicin in combination with the Pgp modulator PSC 833. The intracellular in vivo concentrations of daunorubicin in Pgp positive leukemic cells increased as well as the ratio of the AUC for daunorubicin in leukemic cells to the AUC in plasma suggesting that the mechanism was a specific inhibition of PgP by the modulator. Another aspect of drug resistance and cytostatic treatment is the potential interaction of Pgp, and drugs used in the supportive care of AML patients. 21 different drugs were tested in a Pgp expressing leukemia cell line and the change in intracellular rhodamine 123 was measured. However, in this model we found no significant interactions of the tested drugs on Pgp. In the second part of the thesis we studied two different chemosensitivity assays and markers for drug resistance. In the bioluminiscence ATP chemosensitivity assay cell death is measured as reduced ATP levels. 83 samples from 77 AML patients were included and the in vitro effect of six different cytostatic drugs were tested. We found that in vitro sensitivity to daunorubicin was associated with complete remission and prolonged disease free survival. One problem with in vitro assays is the possible contamination of non malignant cells which can interfere with the results. Therefore we established a new assay were selected myeloid cells were analysed using flow cytometry. 63 samples from 60 AML patients in different stages of their disease were tested. The method was feasible and we found correlations to clinical parameters and Pgp expression. Topoisomerase II alpha is a well known target enzyme for many cytostatic drugs. In this final investigation the expression of the enzyme was studied in different phases of the cell cycle in 25 acute leukemia patients. In contrast to normal cells we found that topo II alpha was expressed in GO/G1 phase. A low expression of topo II alpha in the GO/G1 phase seemed to be associated with resistant disease, which suggests that topo II alpha expression in the different cell cycle phases may have a predictive value. In conclusion a high single dose or the inhibition of Pgp increased the intracellular concentrations in vivo of mitoxantrone and daunorubicin respectively. Drugs used in the supportive care of AML patients did not interact with Pgp in vitro. In vitro sensitivity to daunorubicin was associated with both short and long term outcome using the bioluminiscence ATP assay. In vitro chemosensitivity testing of selected myeloid cells and low expression of topo II alpha in the GO/G1 phase, using flow cytometry techniques, correlated to clinical outcome but further studies are needed to evaluate the predictive value

Limited clinical efficacy of azacitidine in transfusion-dependent, growth factor-resistant, low- and Int-1-risk MDS: Results from the nordic NMDSG08A phase II trial

This prospective phase II study evaluated the efficacy of azacitidine (Aza)+erythropoietin (Epo) in transfusion-dependent patients with lower-risk myelodysplastic syndrome (MDS). Patients ineligible for or refractory to full-dose Epo+granulocyte colony stimulation factors for >8 weeks and a transfusion need of greater than or equal to4 units over 8 weeks were included. Aza 75 mg m−2 d−1, 5/28 days, was given for six cycles; non-responding patients received another three cycles combined with Epo 60 000 units per week. Primary end point was transfusion independence (TI). All patients underwent targeted mutational screen for 42 candidate genes. Thirty enrolled patients received greater than or equal toone cycle of Aza. Ten patients discontinued the study early, 7 due to adverse events including 2 deaths. Thirty-eight serious adverse events were reported, the most common being infection. Five patients achieved TI after six cycles and one after Aza+Epo, giving a total response rate of 20%. Mutational screening revealed a high frequency of recurrent mutations. Although no single mutation predicted for response, SF3A1 (n=3) and DNMT3A (n=4) were only observed in non-responders. We conclude that Aza can induce TI in severely anemic MDS patients, but efficacy is limited, toxicity substantial and most responses of short duration. This treatment cannot be generally recommended in lower-risk MDS. Mutational screening revealed a high frequency of mutations

NOX2-dependent immunosuppression in chronic myelomonocytic leukemia

Chronic myelomonocytic leukemia (CMML) is a myeloproliferative and myelodysplastic neoplasm with few treatment options and dismal prognosis. The role of natural killer (NK) cells and other antileukemic lymphocytes in CMML is largely unknown. We aimed to provide insight into the mechanisms of immune evasion in CMML with a focus on immunosuppressive reactive oxygen species (ROS) formed by the myeloid cell NADPH oxidase-2 (NOX2). The dominant population of primary human CMML cells was found to express membrane-bound NOX2 and to release ROS, which, in turn, triggered extensive PARP-1-dependent cell death in cocultured NK cells, CD8(+) T effector memory cells, and CD8(+) T effector cells. Inhibitors of ROS formation and scavengers of extracellular ROS prevented CMML cell-induced lymphocyte death and facilitated NK cell degranulation toward Ab-coated, primary CMML cells. In patients with CMML, elevation of immature cell counts (CD34(+)) in blood was associated with reduced expression of several NK cell-activating receptors. We propose that CMML cells may use extracellular ROS as a targetable mechanism of immune escape

The prognostic impact of FLT3-ITD and NPM1 mutation in adult AML is age-dependent in the population-based setting

In acute myeloid leukemia (AML) FLT3 internal tandem duplication (ITD) and nucleophosmin 1 (NPM1) mutations provide prognostic information with clinical relevance through choice of treatment, but the effect of age and sex on these molecular markers has not been evaluated. The Swedish AML Registry contains data on FLT3-ITD and NPM1 mutations dating to 2007, and 1570 adult patients younger than 75 years, excluding acute promyelocytic leukemia, had molecular results reported. Females more often had FLT3ITD and/or NPM1mut (FLT3ITD: female, 29%; male, 22% [P = .0015]; NPM1mut: female, 36%; male, 27% [P = .0001]), and more males were double negative (female, 53%; male, 64%; P < .0001). Patients with FLT3ITD were younger than those without (59 vs 62 years; P = .023), in contrast to patients with NPM1mut (62 vs 60 years; P = .059). Interestingly, their prognostic effect had a strong dependence on age: FLT3ITD indicated poor survival in younger patients (<60 years; P = .00003), but had no effect in older patients (60-74 years; P = .5), whereas NPM1mut indicated better survival in older patients (P = .00002), but not in younger patients (P = .95). In FLT3ITD/NPM1mut patients, the survival was less dependent on age than in the other molecular subsets. These findings are likely to have clinical relevance for risk grouping, study design, and choice of therapy

Allelic methylation levels of the noncoding VTRNA2-1 located on chromosome 5q31.1 predict outcome in AML

Deletions of chromosome 5q are associated with poor outcomes in acute myeloid leukemia (AML) suggesting the presence of tumor suppressor(s) at the locus. However, definitive identification of putative tumor suppressor genes remains controversial. Here we show that a 106-nucleotide noncoding RNA vault RNA2-1 (vtRNA2-1), previously misannotated as miR886, could potentially play a role in the biology and prognosis of AML. vtRNA2-1 is transcribed by polymerase III and is monoallelically methylated in 75% of healthy individuals whereas the remaining 25% of the population have biallelic hypomethylation. AML patients without methylation of VTRNA2-1 have a considerably better outcome than those with monoallelic or biallelic methylation (n = 101, P = .001). We show that methylation is inversely correlated with vtRNA2-1 expression, and that 5-azanucleosides induce vtRNA2-1 and down-regulate the phosphorylated RNA-dependent protein kinase (pPKR), whose activity has been shown to be modulated by vtRNA2-1. Because pPKR promotes cell survival in AML, the data are consistent with vtRNA2-1 being a tumor suppressor in AML. This is the first study to show that vtRNA2-1 might play a significant role in AML, that it is either mono- or biallelically expressed in the blood cells of healthy individuals, and that its methylation state predicts outcome in AML

Prognostic significance of high hyperdiploid and tri-/tetraploid adult acute myeloid leukemia.

Purpose To ascertain the clinical implications of high hyperdiploid (HH; 49-65 chromosomes) and tri-/tetraploid (TT; >65 chromosomes) adult acute myeloid leukemia (AML), all such cases were retrieved from the Swedish AML Registry. Results Of the 3,654 cytogenetically informative cases diagnosed between January 1997 and May 2014, 68 (1.9%) were HH (n=50)/TT (n=18). Patients with HH/TT were older than those with intermediate risk (IR) AML (median 71 years versus 67 years; P = 0.042) and less often had de novo AML (63% versus 79%; P = 0.004); no such differences were observed between HH/TT and complex karyotype (CK) AML. The overall survival (OS) was similar between patients with HH/TT and CK AML (median 0.9 years versus 0.6 years; P = 0.082), whereas OS was significantly longer (median 1.6 years; P = 0.028) for IR AML. The OS was shorter for cases with HH than with TT (median 0.6 years versus 1.4 years; P = 0.032) and for HH/TT AMLs with adverse abnormalities (median 0.8 years versus 1.1 years; P = 0.044). Conclusions In conclusion, HH/TT AML is associated with a poor outcome, but chromosome numbers >65 and absence of adverse aberrations seem to translate into a more favorable prognosis. Thus, HH/TT AMLs are clinically heterogeneous and should not automatically be grouped as high risk. This article is protected by copyright. All rights reserved

Secondary Acute Myeloid Leukemia and the Role of Allogeneic Stem Cell Transplantation in a Population-Based Setting

Secondary AML (s-AML), including AML with an antecedent hematologic disorder (AHD-AML) and therapy-related AML (t-AML), constitutes a large proportion of patients with AML and is considered to confer a dismal prognosis. The role of allogeneic hematopoietic cell transplantation (HCT) in patients with s-AML and the extent to which HCT is performed in these patients has been little studied to date. We used the population-based Swedish AML Registry comprising 3337 intensively treated adult patients over a 17-year period to study the role of HCT within the group of patients with s-AML as well as compared with patients with de novo AML. HCT was performed in 576 patients (22%) with de novo AML, in 74 patients (17%) with AHD-AML, and in 57 patients (20%) with t-AML. At 5 years after diagnosis, there were no survivors among patients with previous myeloproliferative neoplasms who did not undergo HCT, and corresponding survival for patients with antecedent myelodysplastic syndromes and t-AML was and 2% and 4%, respectively. HCT was compared with chemotherapy consolidation in s-AML using 3 models: (1) a 200-day landmark analysis, in which HCT was favorable compared with conventional consolidation (P = .04, log-rank test); (2) a multivariable Cox regression with HCT as a time-dependent variable, in which the hazard ratio for mortality was 0.73 (95% confidence interval, 0.64 to 0.83) for HCT and favored HCT in all subgroups; and (3) a propensity score matching analysis, in which the 5-year overall survival (OS) and relapse-free survival in patients with s-AML in first complete remission (CR1) was 48% and 43%, respectively, for patients undergoing HCT versus 20% and 21%, respectively, for those receiving chemotherapy consolidation (P = .01 and .02, respectively, log-rank test). Our observational data suggest that HCT improves survival and offers the only realistic curative treatment option in patients with s-AML

Incidence and prognostic significance of isolated trisomies in adult acute myeloid leukemia : A population-based study from the Swedish AML registry

OBJECTIVES AND METHODS: To ascertain the incidence/clinical implications of isolated autosomal trisomies in adult acute myeloid leukemia (AML), all such cases were retrieved from the Swedish AML Registry.RESULTS: Of the 3179 cytogenetically informative AMLs diagnosed January 1997-May 2015, 246 (7.7%) had isolated trisomies. The frequency increased by age (2.4% at age 18-60 years vs. 23% at >60 years; P<.0001); the median age was 69 years. The five most common were +8 (4.0%), +13 (0.9%), +11 (0.8%), +21 (0.7%), and +4 (0.5%). Age and gender, types of AML and treatment, and complete remission and early death rates did not differ between the single trisomy and the intermediate risk (IR) groups or among cases with isolated gains of chromosomes 4, 8, 11, 13, or 21. The overall survival (OS) was similar in the single trisomy (median 1.6 years) and IR groups (1.7 years; P=.251). The OS differed among the most frequent isolated trisomies; the median OS was 2.5 years for +4, 1.9 years for +21, 1.5 years for +8, 1.1 years for +11, and 0.8 years for +13 (P=.013).CONCLUSION: AML with single trisomies, with the exception of +13, should be grouped as IR

Clinical effect of increasing doses of lenalidomide in high-risk myelodysplastic syndrome and acute myeloid leukemia with chromosome 5 abnormalities

Background Patients with chromosome 5 abnormalities and high-risk myelodysplastic syndromes or acute myeloid leukemia have a poor outcome. We hypothesized that increasing doses of lenalidomide may benefit this group of patients by inhibiting the tumor clone, as assessed by fluorescence in situ hybridization for del(5q31). Design and Methods Twenty-eight patients at diagnosis or with relapsed disease and not eligible for standard therapy (16 with acute myeloid leukemia, 12 with intermediate-risk 2 or high-risk myelodysplastic syndrome) were enrolled in this prospective phase II multicenter trial and treated with lenalidomide up to 30 mg daily for 16 weeks. Three patients had isolated del(5q), six had del(5q) plus one additional aberration, 14 had del(5q) and a complex karyotype, four had monosomy 5, and one had del(5q) identified by fluorescence in situ hybridization only. Results Major and minor cytogenetic responses, assessed by fluorescence in situ hybridization, were achieved in 5/26 (19%) and 2/26 (8%) patients, respectively, who received one or more dose of lenalidomide, while two patients achieved only a bone marrow response. Nine of all 26 patients (35%) and nine of the ten who completed the 16 weeks of trial responded to treatment. Using the International Working Group criteria for acute myeloid leukemia and myelodysplastic syndrome the overall response rate in treated patients with acute myeloid leukemia was 20% (3/15), while that for patients with myelodysplastic syndrome was 36% (4/11). Seven patients stopped therapy due to progressive disease and nine because of complications, most of which were disease-related. Response rates were similar in patients with isolated del(5q) and in those with additional aberrations. Interestingly, patients with TP53 mutations responded less well than those without mutations (2/13 versus 5/9, respectively; P = 0.047). No responses were observed among 11 cases with deleterious TP53 mutations. Conclusions Our data support a role for higher doses of lenalidomide in poor prognosis patients with myelodysplastic syndrome and acute myeloid leukemia with deletion 5q. (Clinicaltrials.gov identifier NCT00761449)