Azacitidine. Poor-prognosis myelodysplasia: promising, but more data needed.

Some myelodysplastic syndromes carry a poor prognosis. This is also the case for chronic myelomonocytic leukaemia (related to myelodysplastic syndromes), and acute myeloblastic leukaemia, a frequent complication of myelodysplasia. The only treatment capable of providing long-term remission (in about 1 in 2 patients on average) is haematopoietic stem cell transplantation, but this burdensome treatment can only be used in a minority of cases. Azacitidine (Vidaza, Celgene), an agent that blocks DNA synthesis, is the first drug to receive EU marketing authorisation in these settings. Its clinical evaluation is based on an unblinded trial that included 358 patients comparable to those discussed in the marketing authorisation. In addition to individually tailored symptomatic care, they were randomised to receive either azacitidine or conventional care regimens chosen by their physician (no treatment, low-dose cytarabine, or an anthracycline plus cytarabine). The median overall survival time was significantly longer with azacitidine (24.5 versus 15 months), and transfusion requirements were also reduced. Another comparative trial versus symptomatic treatment alone in 191 patients with various prognoses also showed an increase in survival time with azacitidine, but this study suffered from methodological flaws. The main adverse effects of azacitidine are potentially severe toxicity for various blood cells, gastrointestinal disorders, and reactions at the injection site. In practice, when haematopoietic stem cell transplantation is not feasible for poor-prognosis patients with myelodysplastic syndromes or related disorders, azacitidine can be used instead of disappointing standard treatments, even though more clinical evaluation is needed.