5-Azacitidine (5-AZA) is widely used for the treatment of higher-risk myelodysplastic syndromes. However, response and survival rates vary considerably, while indicated treatment duration remains undefined. For these reasons, factors determining response and survival are of major importance. Clinical, morphological, flow cytometry, cytogenetic and molecular factors are discussed in this review. Biomarkers predictive of response and prognosis, as well as their link to the mode of action of 5-AZA are also addressed, shifting the focus from clinical practice to investigational research. Their use could further improve prognostic classification of 5-AZA treated higher-risk myelodysplastic syndromes in the near future.
Keywords: azacitidine; biomarkers; high-risk MDS; prognosis; response; survival.
Lay abstract Myelodysplastic syndrome is a disorder in which patients have dysfunctional blood cells. The only chance of curing patients with high-risk myelodysplastic syndrome (HR-MDS) is allogeneic stem cell transplantation. However, most HR-MDS patients are not young or fit enough to receive such a toxic treatment. For these patients, hypomethylating drugs such as 5-azacitidine (5-AZA) and decitabine are preferable treatments. These drugs work by reducing the number of molecules known as methyl groups that are attached to DNA, which can lead to cell death. About half of patients respond to it, and those who do respond, survive longer than those who do not. In addition, 5-AZA delays disease progression from HR-MDS to acute myeloid leukemia, a type of blood cancer, and may help patients who do not improve to live longer. However, 5-AZA has side effects that can be hard to bear, such as an increased need for red blood cells and/or platelet transfusions. For this reason, it would be good to predict the clinical and biological factors associated with either response or final outcome following treatment. In this manuscript, we attempt to summarize current knowledge on this topic.