New leukemia drug gives renewed hope to those battling drug resistance to the disease

Jun 18 2006

New research offers hope for victims of chronic myeloid leukemia (CML) battling drug resistance to the disease.

Researchers at the University of California in Los Angeles (UCLA) say that Sprycel (dasatinib), treats CML that has mutated and becomes resistant to the leukemia drug Gleevec.

Charles Sawyers professor of hematology/oncology at UCLA's Jonsson Cancer Center says dasatinib has proved "extremely effective" in fighting cancer, giving patients for whom all conventional therapies have failed another option.

The early results are from a Phase I study of Sprycel have been so favorable that several Phase II studies were launched last year and are almost completed.

Because the trials have moved so quickly and because more positive results are anticipated, an advisory panel for the U.S. Food & Drug Administration has already recommended that the agency approve the drug; that could happen before the end of the month, says Sawyers.

Like Gleevec, Sprycel also is taken in pill form but over five years, about 20 percent of patients become resistant to Gleevec.

As a rule drug development is slow moving but since Gleevec was approved five years ago UCLA scientists have discovered how the CML in some patients mutated and became resistant to Gleevec and were able to test an existing compound on laboratory models and then in patients with great success.

Resistance in CML patients is associated with mutations in a gene that interferes with the drug's action and Sprycel blocks 14 of 15 documented CML mutations known to lead to resistance, says Sawyers and it is 300 times more potent than Gleevec.

The drug was seen to be effective in 68 out of 84 volunteers suffering from a form of CML resistant to Gleevec.

The researchers carried out genetic tests for the Philadelphia chromosome, the genetic abnormality that characterizes most cases of CML and the primary mutation targeted by the drug.

This was done in order to find out which patients would respond to the drug.

The responses have lasted for up to two years in some cases and although the study is complete, a number of patients continue to take the drug and are still being monitored.

Sawyers said it's possible that Gleevec (Novartis) and Sprycel (Bristol-Myers Squibb), might be used together in patients with CML as a very effective double whammy to fight cancer and battle drug resistance.

The study is published in the New England Journal of Medicine.