Sprycel tops Gleevec in newly diagnosed CML: study

NEW YORK (Reuters) - Bristol-Myers Squibb's cancer drug Sprycel was superior to the highly effective Gleevec in treating newly diagnosed patients with chronic myeloid leukemia, researchers reported on Saturday.

Sprycel, known chemically as dasatinib, is approved to treat chronic myeloid leukemia (CML) patients whose cancer worsens despite treatment with Gleevec, a pill sold by Swiss drugmaker Novartis, or for patients who cannot tolerate Gleevec.

Bristol hopes to convince regulators to approve Sprycel as an initial treatment for the blood cancer, which could significantly increase sales. Sprycel, a relatively new product that Bristol is counting on for profit growth, had first-quarter sales of $131 million.

"It gives our patients another option for frontline management," Dr. Sonali Smith of the University of Chicago Medical Center told a meeting of the American Society of Clinical Oncology.

Sprycel and a newer Novartis drug, Tasigna, may improve on Gleevec's remarkable success in treating CML. The older drug increased the CML 10-year survival rate from less than 20 percent to up to 90 percent and transformed CML from a death sentence to a manageable disease for most patients.

Dr. Hagop Kantarjian of the University of Texas M.D. Anderson Cancer Center in Houston and colleagues tested 519 patients, who took one pill a day for a year.

Many more patients taking Sprycel had complete cytogenic response -- the disappearance of the leukemia cells -- with 77 percent clearing the tiny tumor cells, compared to 66 percent who took Gleevec for a year, and with fewer side-effects.

The study also looked at major molecular response, or a reduction of disease by 99.9 percent. The major molecular response rate was 46 percent with Sprycel versus 28 percent with Gleevec.

Both measurements mean patients do better after 5 years and 10 years, Kantarjian said.

"This is still relatively short follow-up," Smith said. "These patients live for many years so we won't know for a long time."

SECOND DRUG

A similar study being presented at ASCO found that patients did better on Tasigna, or nilotinib, compared to Gleevec.

About 44 percent of patients taking the newer Novartis drug had a major molecular response compared with 22 percent for Gleevec after 12 months.

All three drugs belong to a class called tyrosine kinase inhibitors, which deactivate messages that make leukemia cells malignant and kill them.

"We think that the new tyrosine kinase inhibitors are a major improvement over what has been already a highly successful and revolutionary treatment," said Kantarjian.

"At this stage we consider both drugs to be probably superior to the standard of care, imatinib," he said. "The side effects or toxicities with both the new drugs on average are less than with Gleevec."

He said there were fewer instances of nausea, vomiting, muscle cramps and muscle aches, fluid retention or weight gain in the Sprycel patients.

Researchers did see higher rates of low blood cell counts and fluid around the lungs with Sprycel, but it was mostly mild to moderate.

Kantarjian, who worked on both studies, said Sprycel and Tasigna "on average appear to be equally effective," but he noted they have not been tested against each other.

"I think both drugs will likely be approved for the front line treatment of CML," Kantarjian predicted.

(Reporting by Bill Berkrot and Julie Steenhuysen; Editing by Maggie Fox)