Clinical and Biological EFFECTS of 5-Azacitidine FIVE Days/Monthly Schedule IN Symptomatic LOW-RISK (IPSS: 0-1) Myelodisplastic Patient.

Nucleoside 5-Azacitidine (5-Aza) administered at a dose of 75mg/mq/day subcutaneously for 7 days, every 28 days, induces high hematologic response rates, reduces progression to acute myeloid leukaemia (AML) and increases overall survival in the high risk MDS patients.

The use of 5-Aza in the earlier phases of MDS could reduce the proliferative advantage of MDS clone and favours the regrowth of normal hematopoiesis. In the setting of low-risk MDS patients lower doses of 5-Aza could be enough to induce hematologic responses. We attempted to use an alternative schedule, 75 mg/mq subcutaneous daily for 5 consecutive days every 28 days, for a total of 8 courses, to evaluate its efficacy and tolerability in low risk MDS patients. Pharmacogenomic studies (gene expression profile and single nucleotide polymorphism analysis), cytokine network and phosphatidylinositol-phospholipase C – β1 (PI-PLC - β1) expression, before and after 5-Aza treatment, were planned to identify new biological markers to predict the response.

From September 2008 to August 2009, 25 patients were enrolled into the study. According to WHO criteria 12 patients had refractory anemia (RA), 5 patients refractory cytopenia with multilineage dysplasia (RCMD), 7 patients refractory anemia with excess blasts-1 (RAEB-1) and 1 patient refractory anemia with ringed sideroblasts (RARS). All patients were classified as Low Risk (IPSS score 0-1). Age at diagnosis ranged between 56 and 84 years. All patients failed previously EPO therapy and were in chronic red blood cell (RBC) supportive care with a median transfusions requirement of 4 units/monthly. The response treatment criteria was according to IWG 2006.

9/25 (36%) patients completed at least 4 courses of therapy and only 6/25 (24%) patients finished the treatment plan (8 courses). Five patients obtained an hematologic improvement (3 erythroid response and 2 neutrophil response) whereas 4 patients maintained a stable disease. The others 16 patients are ongoing. The drug was very well tolerated. WHO grade III hematologic toxicity consisted in neutropenia (1 case) and thrombocytopenia (1 case) was observed in only two patients, but it was transitory and no delay of treatment was necessary.

Our preliminary results show that the 5-Aza five days/monthly schedule is very well tolerated and it appears to induce hematologic improvements as well as the seven days/monthly schedule, at least in the low-risk MDS setting. Biological studies will be useful to elucidate the genetic bases of sensititvity or resistance to 5-AZA and to optimise the therapy.Acknowledgments: this work was supported by MIUR 2008.

No relevant conflicts of interest to declare.