Cedazuridine

Myelodysplastic syndromes (MDS) represent a heterogeneous group of hematopoietic neoplasms arising from a variety of underlying mutations that manifest in peripheral cytopenias and may eventually progress to secondary acute myeloid leukemia (sAML). There are over 45 genes commonly mutated in MDS patients, including those involved in DNA methylation and repair, histone modification, RNA splicing, transcription, signal transduction, and cellular adhesion. It is hypothesized that initial clonal founder mutations give rise to progressive acquisition of secondary mutations and facilitate disease progression to sAML.

Hypomethylating agents such as decitabine are metabolized into triphosphate derivatives that are subsequently incorporated into DNA. Once incorporated, these agents inhibit the activity of DNA methylases such as DNMT1, leading to progressive DNA hypomethylation and eventual activation of tumour suppression genes and apoptotic pathways. However, hypomethylating agents given orally are vulnerable to first-pass metabolism by cytidine deaminase, and hence typically have to be administered through intramuscular or intravenous routes. Co-administration with cedazuridine, which is an efficient inhibitor of cytidine deaminase, drastically increases the oral bioavailability of decitabine, allowing for combination oral therapy.