The MDS Beacon™

The dosing schedule of Vidaza (azacitidine) currently approved for use in Europe may be the most effective and safest treatment plan for myelodysplastic syndromes (MDS) compared with alternative dosing schedules according to a retrospective analysis of clinical results collected by Spanish researchers.  The findings were presented at the 51st Annual American Society of Hematology (ASH) meeting and exposition on December 5. 

Vidaza is one of several newly approved drugs for the treatment of MDS. Clinical trial data indicates that Vidaza typically delays progression of MDS to acute myeloid leukemia and improves overall survival among MDS patients. The European Medicines Agency (EMEA) approved Vidaza for European markets in March 2009.

Researchers collected data from 147 MDS patients who were treated with Vidaza on different dosing regimens at hematology clinics in Spain. Vidaza was given to these patients on a compassionate use basis, before Vidaza was officially approved in Spain. The dosing schedule was determined by a patient’s disease status and scheduling availability.

Three different dosing schedules were studied, each on a 28-day cycle. Group A received Vidaza on days 1, 2, 3, 4, and 5. Group B received Vidaza on days 1, 2, 3, 4, 5, 8, and 9. Group C received Vidaza on days 1, 2, 3, 4, 5, 6, and 7, which is also the dosing schedule currently approved for Vidaza by the EMEA (and by the U.S. Food and Drug Administration).  The disease characteristics of patients in all three groups were similar, although there was a higher share of high- or Intermediate-2 risk MDS patients in group C.

Of the three groups, the overall response rate of group C was the highest at 74 percent. Group A showed a response rate of 58 percent, and group B showed a response rate of 65 percent.

Vidaza was generally well tolerated by patients in all three groups according to researchers. However, common drug-related side effects included severe neutropenia (temporarily lowered white blood cell levels) and severe thrombocytopenia (lowered platelet levels). The highest rate of these side effects were seen in groups A and B. In group A, 50 percent experienced neutropenia and 43 percent experienced thrombocytopenia, and in group B, 42 percent experienced neutropenia and 30 percent experienced thrombocytopenia. Group A also showed the highest rate of anemia at 29 percent. Group C showed the overall lowest rate of drug-related side effects, with 35 percent experiencing neutropenia and 22 percent experiencing thrombocytopenia.

The authors concluded that while different dosing schedules for Vidaza are possible, the dosing schedule currently approved by the EMEA received by group C has the greatest efficacy and safety in the treatment of MDS.

Since the data studied in the analysis represented a retrospective, non-random study, the researchers are awaiting further analyses for confirmation of their findings.

For more information, see abstract 2773 at the ASH Meeting Web site.