Epigenetic and therapeutic profiling of chronic lymphocytic leukemia
Guillermo Garcia-Manero, M.D.
University of Texas M. D. Anderson Cancer Center
Abstract:
Aberrant DNA methylation refers to the addition of methyl groups to specific regions of the genome. This alteration results in gene silencing and by inactivating genes important for cell function has been implicated in the cancer process. Data from our laboratory has demonstrated that the identification of specific DNA methylation marks may allow the identification of subsets of patients with leukemia and different prognosis. More importantly, aberrant DNA methylation can be reversed both in vitro and in vivo with drugs with hypomethylating activity. These drugs have been shown to have activity in patients with myeloid leukemias. Understanding of methylation alterations that may predict for response with these therapy will be of great importance as it may allow the selective use of these relative non-toxic therapies.
Based on these concepts, we propose to:
Develop an epigenetic/genetic profile of patients with chronic lymphocytic leukemia (CLL).
Develop in vitro systems to test the molecular effects of hypomethylating agents on CLL cells.
Develop clinical trials based on information derived from #1 & #2 using hypomethylating agents in patients with CLL.
To complete these studies, we will obtain a set of pretreatment CLL samples obtained from the CLL Research Consortium Tissue Bank. These samples will be analyzed for both gene specific and global methylation. The data generated will be compared to known prognostic alterations in CLL such as Ig VH mutational status, FISH analysis, and expression of ZAP70 and CD38. Because of the potential role of AID in the control of DNA methylation, we will also analyze its status in this patient population. Appropriate age-matched controls will be used. For aim #2, we will use clonogeneic assays (assays that allow the in vitro growth of CLL cells obtained from patients).
These CLL cells will be epigenetically profiled prior to treatment and effects on global and gene specific methylation, as well as cell kill dynamics, will be measured using different doses of both 5-aza-2’-deoxycytidine and 5-azacytidine, two different drugs with hypomethylating activity. This data will then be used to develop a phase I clinical trial of one of these agents. The data generated by aims #1-3 will then be used to develop a final methylation classification of CLL and to introduce the use of hypomethylating agents for the treatment of CLL patients.