Roche’s Genentech breathed new life into the company’s blood cancer portfolio today as it unveiled promising new data for its investigational treatment GA101 for chronic lymphocytic leukemia (CLL).

Data from the Phase III trial (dubbed CLL11) showed off GA101 and Rituxan’s efficacy when combined with standard chemotherapy agent, chlorambucil.

GA101 plus a chemotherapy agent reduced the risk of disease progression or death by 86%. Rituxan and chlorambucil reduced the risk of disease progression or death by 68%. Median progression-free survival (PFS) for GA101 with chlorambucil improved to 23 months versus 10.9 months with chlorambucil alone.

Roche/Genentech also reported today that FDA gave GA101 a Breakthrough Therapy designation for CLL.

The second, and more significant stage of the trial will square off GA101 with Rituxan, an aging blockbuster which raked in approximately $7 billion for Roche last year—and also faces patent expiration in 2014.

Formal results from the tête-à-tête are not yet available. “No formal comparisons between the GA101 and Rituxan arms can be made as the number of PFS events required for that formal analysis has not yet been reached,” read a statement by Roche today. Those results are expected within the next 12 months.

And GA101’s future has a lot riding on that data. Deutsche Bank AG analyst Tim Race said in an interview prior to the release: “In theory, it’s a smarter-designed version of Rituxan. The problem is that Rituxan is a brilliant drug, and being better than a brilliant drug is always difficult,” reported Bloomberg.

Rivals are already nibbling at the heels of Rituxan. Both Novartis/Sandoz and Boehringer Ingelheim have Rituxan biosimilars in Phase III trials. Novartis/Sandoz’s contender GP2013 is likely to end by March 2014. Boehringer’s biosimilar BI 695500 began trials in September of last year and is expected to be completed in April 2015.

Roche/Genentech will report on these findings at the American Society of Clinical Oncology’s Annual Meeting in Chicago on Tuesday, June 4th.