First-in-class drug aids myelodysplastic syndrome sufferers
with myelodysplastic syndrome (MDS), and could become the new
standard of therapy for this group of pre-cancer disorders, said
researchers.
MDS is a disease that is difficult to treat, especially since it usually strikes the elderly. Ten years ago, there was little to offer patients other than blood transfusions and supportive care.
The drug, decitabine, is designed to turn on genes that cancer had switched off, and in this study, patients who were treated with it achieved a significantly higher overall response rate, compared to patients receiving supportive care, which includes transfusions of red blood cells and platelets.
It is a DNA hypomethylating agent that fights cancer by reversing a chemical process (methylation) that turns off tumour-suppressor genes that protect cells from becoming cancerous.
Methylation is the gradual addition of chemical units known as methyl groups to genes, and as these groups accumulate, the gene gradually shuts down. Decitabine prevents the methylation process, enabling the gene to become active again.
Results of the randomised Phase III clinical trial concluded that in treated patients who responded to the drug, the median time to progression of the disease, or death, was 17.5 months, compared to 9.8 months in patients who did not.
"This is a very promising drug that we believe works even better when patients use it for a period that is longer than that tested in this trial," says lead author, Hagop Kantarjian.
Analysis of an ongoing study demonstrated a 40 per cent complete response rate when the drug was given in lower doses over a longer period of time.
In contrast, the 83 patients treated with decitabine in this study received comparatively fewer rounds of therapy. The response rate was 17 per cent.
"The data suggest to us that prolonged treatment is important for response but the optimal schedule for using decitabine is being studied," said Kantarjian.
This response rate represents a vast improvement in the care of these pre-cancers, a group of diseases in which the bone marrow progenitor cells that normally morph into red and white blood cells and platelets, fail to respond to normal growth controls.
This results in too many progenitor cells (also known as blasts) and too few mature blood cells. In about 30 per cent of patients, the disease progresses to acute myeloid leukemia (AML).
About three-fourths of MDS patients succumb to either MDS or to AML within about 2-3 years from diagnosis.
"In addition to increased survival and time-to-progression in some patients, decitabine improved quality of life in patients who responded and eliminated the need for frequent transfusions," Kantarjian said.
Results of the trial are published March 13, 2006 in the online version of the journal >Cancer.
