Grant: Fellowship: LLSC/CIHR Clinician Scientist Fellow Award

Myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) are common and deadly blood cancers. MDS/AML develop from DNA mutations and abnormal regulation by DNA methylation. Changes to DNA methylation also can change the 3-dimensional (3D) structure of bundles of DNA (chromatin) through proteins such as the CCCTC-binding factor (CTCF) protein. Another important factor affecting the survival of blood cancers is dysregulation of normal cell death programs, such as the B-cell lymphoma 2 (BCL-2) pathway. New drugs, such as one called venetoclax, can turn on this pathway and treat blood cancers. Many patients receive 5-azacitidine (5-aza) with or without novel drugs (e.g. venetoclax). 5-aza affects methylation, but only 60% respond. Our preliminary data suggests 5-aza resistance arises from the level of maturity (cell of origin) of the MDS/AML leukemia cell, rather than being associated with specific genetic mutations. We will confirm this is the case by examining DNA methylation on a single-cell level in specific sub-populations of cells to prove these cells are either more or less mature in 5-aza responders or non-responders. We will also prove these cells are different by directly assessing the 3D structure of their chromatin, which is unique to specific cells. We will then examine where the CTCF protein is in these cells, to show that it is mediating these changes. We will also develop and utilise an assay (pyrosequencing) for targeted measurement of DNA methylation in these cells that could potentially be used as a clinical biomarker. Finally, we will examine what role cell death pathways (BCL-2) play in the mechanism of action of 5-aza either as a single-agent or combined with venetoclax. Our findings, including biomarkers, will be poised for clinical translation. This could both prevent patients from getting chemotherapy that is ineffective by predicting whether they will respond, and pave the way for novel, rational 5-aza combination regimens.