Patients with chronic lymphocytic leukemia (CLL) treated with Roche's (RHHBY) Gazyva lived almost one year longer without their disease getting worse compared to patients treated with another Roche drug, Rituxan, according to results of a phase III study announced Thursday. 

The positive study results will benefit Roche because they validate the development plan for Gazyva, which was to engineer a more potent version of Rituxan, the company's top-selling hematological monoclonal antibody therapy with 2012 sales of approximately $7 billion. Rituxan sales, however, could start to fade in 2016 when a biosimilar version of the drug is expected to enter the market. 

On Nov. 1, the FDA approved Gazyva in combination with another drug chlorambucil to treat patients with newly diagnosed CLL. Thursday's data bolster Gazyva's approval by confirming the drug's superiority over Rituxan when used to treat newly diagnosed CLL patients. 

In the study, the combination of Gazyva and chlorambucil reduced the risk of tumor growth or death (progression-free survival, or PFS) by 61% compared to Rituxan plus chlorambucil. 

For patients in the Gazyva arm, the median PFS was 26.7 months compared with 15.2 months for patients in the Rituxan arm. 

PFS was the primary endpoint of the study and was statistically significant.

"These new data are important because they showed for the first time that Gazyva significantly extended progression-free survival when directly compared against Rituxan," said Hal Baron, Roche's chief medical officer, in a statement.

Gazyva reduced the risk of death by 34% compared to Rituxan -- a key secondary endpoint of the study --  but the trend toward an overall survival benefit was not statistically significant at this time. Patients in the study continue to be followed for survival. Median survival has not been reached in either of the study arms. 

A statistically significant survival benefit was observed in the other stage of the study, where Gazyva plus chlorambucil reduced the risk of death by 59% compared to chlorambucil alone.

Data from the Gazyva study were released Thursday in a research abstract in advance of next month's American Society of Hematology (ASH) annual meeting. A full presentation of the Gazyva study results will be made during the plenary session of the ASH meeting.


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