CHICAGO (TheStreet) -- Pharmacyclics (PCYC) and Johnson & Johnson's (JNJ) - Get Report blood-cancer drug Imbruvica reduced the risk of dying by 57% compared to GlaxoSmithKline's (GSK) - Get Report Arzerra when used to treat elderly patients with relapsed chronic lymphocytic leukemia, according to results from a phase III study released today at the American Society of Clinical Oncology (ASCO) annual meeting.

Imbruvica was granted accelerated approval by the FDA in February to treat relapsed or refractory chronic lymphocytic leukemia, the most common form of leukemia in adults. The results from the phase III study known as "RESONATE", announced today, will be used by Pharmacyclics and J&J to secure full approval for the drug.

"With ibrutinib, about 80% of patients were still in remission at one year, twice as many as we would expect with standard therapy," said Dr. John Byrd of the Ohio State University Comprehensive Cancer Center and the lead investigator in the RESONATE study, in a statement. [Ibrutinib is the scientific name for Imbruvica.]

In the study, 391 elderly patients with CLL no longer responsive following two or more prior therapies were randomized to treatment with Imbruvica or Arzerra. At a median follow up of 9.4 months, Imbruvica was associated with an 57% lower risk of dying (hazard ratio 0.43) and an 80% reduction in the risk of tumor progression (hazard ratio 0.21) compared to Arzerra. Median overall survival and median progression-free survival have not been reached for Imbruvica.

Forty-two percent of patients responded to Imbruvica compared to 4% of Arzerra patients.

Diarrhea, minor bleeding and atrial fibrillation were side effects more commonly reported in the Imbruvica arm of the study, while Arzerra patients reported higher rates of peripheral neuropahthy. The study investigators note kidney problems reported in patients from a prior Imbruvica studies were not apparent in the RESONATE study. 

Imbruvica faces competition for CLL patients from still-experimental drugs being developed by Abbvie (ABBV) - Get Report and Gilead Sciences (GILD) - Get Report. Both companies will also be presenting new clinical data at this year's ASCO meeting. 

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