| 1. |
- Grövdal, Michael
(författare)
-
DNA methylation and hypomethylating agents in high-risk myelodysplastic syndromes and acute myeloid leukemia
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Epigenetic alterations are common in cancer. One example is aberrant hypermethylation of the promoters of tumor suppressor genes and hence silencing of gene expression. Azacitidine, a DNA hypomethylating drug, has been shown to prolong survival in patients with high-risk myelodysplastic syndromes (MDS) compared to conventional care regimens, and is now recommended as first-line therapy for patients not eligible for allogeneic stem cell transplantation. Azacitidine has DNA hypomethylating properties and has been shown to re-induce expression of aberrantly silenced genes in various cell lines. However, its mechanism of action in primary hematopoietic progenitors in vivo is relatively unknown. This thesis aimed to assess the prognostic value of DNA methylation in high-risk MDS and in de novo acute myeloid leukemia (AML), to evaluate the effect and feasibility of maintenance treatment with azacitidine in patients in complete remission (CR) after induction chemotherapy, and to study mechanisms of action of azacitidine in primary MDS and normal bone marrow (NBM) progenitors. We show, for the first time, a correlation between promoter methylation patterns and outcome of induction chemotherapy in a cohort of 60 patients with high-risk MDS or AML following MDS (MDS-AML). Patients who were hypermethylated in the E-cadherin (CDH) promoter had lower CR rates than those without methylation (P=0.008). CDH methylation was also associated with shorter survival (P=0.003). By contrast, in a material of 107 patients with de novo AML CDH methylation had no impact on survival or on outcome of induction chemotherapy. In fact, promoter hypermethylation of P15ink4b, previously reported as a poor prognostic marker in MDS and MDS-AML, as well as genome wide promoter methylation corresponded to a better survival (P=0.001 and 0.005, respectively). Another novel finding was that de novo AML patients with a low degree of global DNA methylation had a poorer response to induction chemotherapy (P=0.005). These differences in the prognostic value of methylation status in MDS/MDS-AML and de novo AML suggest important differences in disease biology and response to treatment between the two entities. Several mechanisms of action for azacitidine have been suggested, including induction of apoptosis, differentiation of blasts, histone modification, immunomodulation and DNA and RNA demethylation. However, the majority of data results from cell line experiments or from sequential bone marrow sampling during azacitidine treatment. In paper IV of this thesis we exposed primary MDS and normal bone marrow (NBM) progenitors to azacitidine in vitro. Interestingly, azacytidine caused marked up-regulation of gene expression in MDS but not in NBM CD34+ marrow cells. Compared to cell line experiments, induction of apoptosis as well as global and gene-specific hypomethylation was less pronounced in primary cells. Interestingly, azacitidine in doses up to 5 μM had no negative effect on proliferation in suspension cultures, and doses up to 0.5 μM even had a positive effect on colony growth. This is a useful finding since it may support the use of the drug for patients with low-risk MDS, and as maintenance after allogeneic stem cell transplantation.
|
|
| 2. |
- Grövdal, Michael, et al.
(författare)
-
Maintenance treatment with azacytidine for patients with high-risk myelodysplastic syndromes (MDS) or acute myeloid leukaemia following MDS in complete remission after induction chemotherapy
- 2010
-
Ingår i: British Journal of Haematology. - : Wiley. - 0007-1048 .- 1365-2141. ; 150:3, s. 293-302
-
Tidskriftsartikel (refereegranskat)abstract
- This prospective Phase II study is the first to assess the feasibility and efficacy of maintenance 5-azacytidine for older patients with high-risk myelodysplastic syndrome (MDS), chronic myelomonocytic leukaemia and MDS-acute myeloid leukaemia syndromes in complete remission (CR) after induction chemotherapy. Sixty patients were enrolled and treated by standard induction chemotherapy. Patients that reached CR started maintenance therapy with subcutaneous azacytidine, 5/28 d until relapse. Promoter-methylation status of CDKN2B (P15 ink4b), CDH1 and HIC1 was examined pre-induction, in CR and 6, 12 and 24 months post CR. Twenty-four (40%) patients achieved CR after induction chemotherapy and 23 started maintenance treatment with azacytidine. Median CR duration was 13.5 months, >24 months in 17% of the patients, and 18-30.5 months in the four patients with trisomy 8. CR duration was not associated with CDKN2B methylation status or karyotype. Median overall survival was 20 months. Hypermethylation of CDH1 was significantly associated with low CR rate, early relapse, and short overall survival (P = 0.003). 5-azacytidine treatment, at a dose of 60 mg/m(2) was well tolerated. Grade III-IV thrombocytopenia and neutropenia occurred after 9.5 and 30% of the cycles, respectively, while haemoglobin levels increased during treatment. 5-azacytidine treatment is safe, feasible and may be of benefit in a subset of patients.
|
|
| 3. |
- Grövdal, Michael, et al.
(författare)
-
Negative effect of DNA hypermethylation on the outcome of intensive chemotherapy in older patients with high-risk myelodysplastic syndromes and acute myeloid leukemia following myelodysplastic syndrome
- 2007
-
Ingår i: Clinical Cancer Research. - 1078-0432 .- 1557-3265. ; 13:23, s. 7107-7112
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Promoter hypermethylation of, for example, tumor-suppressor genes, is considered to be an important step in cancerogenesis and a negative risk factor for survival in patients with myelodysplastic syndromes (MDS); however, its role for response to therapy has not been determined. This study was designed to assess the effect of methylation status on the outcome of conventional induction chemotherapy. EXPERIMENTAL DESIGN: Sixty patients with high-risk MDS or acute myeloid leukemia following MDS were treated with standard doses of daunorubicin and 1-beta-d-arabinofuranosylcytosine. Standard prognostic variables and methylation status of the P15(ink4b) (P15), E-cadherin (CDH), and hypermethylated in cancer 1 (HIC) genes were analyzed before treatment. RESULTS: Forty percent of the patients achieved complete remission (CR). CR rate was lower in patients with high WBC counts (P = 0.03) and high CD34 expression on bone marrow cells (P = 0.02). Whereas P15 status alone was not significantly associated with CR rate (P = 0.25), no patient with hypermethylation of all three genes achieved CR (P = 0.03). Moreover, patients with CDH methylation showed a significantly lower CR rate (P = 0.008), and CDH methylation retained its prognostic value also in the multivariate analysis. Hypermethylation was associated with increased CD34 expression, but not with other known predictive factors for response, such as cytogenetic profile. CONCLUSIONS: We show for the first time a significant effect of methylation status on the outcome of conventional chemotherapy in high-risk MDS and acute myelogenous leukemia following MDS. Provided confirmed in an independent study, our results should be used as a basis for therapeutic decision-making in this patient group.
|
|
| 4. |
- Tobiasson, Magnus, et al.
(författare)
-
Comprehensive mapping of the effects of azacitidine on DNA methylation, repressive/permissive histone marks and gene expression in primary cells from patients with MDS and MDS-related disease
- 2017
-
Ingår i: Oncotarget. - : IMPACT JOURNALS LLC. - 1949-2553. ; 8:17, s. 28812-28825
-
Tidskriftsartikel (refereegranskat)abstract
- Azacitidine (Aza) is first-line treatment for patients with high-risk myelodysplastic syndromes (MDS), although its precise mechanism of action is unknown. We performed the first study to globally evaluate the epigenetic effects of Aza on MDS bone marrow progenitor cells assessing gene expression (RNA seq), DNA methylation (Illumina 450k) and the histone modifications H3K18ac and H3K9me3 (ChIP seq). Aza induced a general increase in gene expression with 924 significantly upregulated genes but this increase showed no correlation with changes in DNA methylation or H3K18ac, and only a weak association with changes in H3K9me3. Interestingly, we observed activation of transcripts containing 15 endogenous retroviruses (ERVs) confirming previous cell line studies. DNA methylation decreased moderately in 99% of all genes, with a median beta-value reduction of 0.018; the most pronounced effects seen in heterochromatin. Aza-induced hypomethylation correlated significantly with change in H3K9me3. The pattern of H3K18ac and H3K9me3 displayed large differences between patients and healthy controls without any consistent pattern induced by Aza. We conclude that the marked induction of gene expression only partly could be explained by epigenetic changes, and propose that activation of ERVs may contribute to the clinical effects of Aza in MDS.
|
|
