New York, July 29 (IANS): A new drug found promising for treating blood cancer in its first human trial is now in phase II clinical trials, a new study says.

The drug coaxes dormant cancer stem cells, residing in the bone marrow, to begin differentiating and exit into the blood stream where they can be destroyed by chemotherapy agents.

"This drug gets that unwanted house guests to leave and never come back," said the study's senior author Catriona Jamieson, associate professor of medicine at University of California, San Diego School of Medicine in the US.

"It is a significant step forward in treating people with refractory or resistant myeloid leukemia, myelodysplastic syndrome and myelofibrosis,” Jamieson said.

"It is a bonus that the drug can be administered as easily as an aspirin, in a single, daily oral tablet," Jamieson noted.

For the first-in-human study conducted between 2010-2012, the drug called PF-04449913 was tested in 47 adults with blood and marrow cancer.

They received escalating daily doses of the drug in 28-day cycles.

Treatment cycles were repeated until a participant experienced unacceptable adverse effects without evidence of clinical improvement.

The drug elicited clinical activity sufficient to establish proof-of-concept for the treatment in 23 individuals, or nearly half the study participants.

Given the promising results, the drug's efficacy as a treatment for different types of blood cancer is now being investigated in five phase II clinical trials.

"Our hope is that this drug will enable more effective treatment to begin earlier and that with earlier intervention, we can alter the course of disease and remove the need for, or improve the chances of success with, bone marrow transplantation," Jamieson said.

The study was published online in the journal The Lancet Haematology.