By Deena Beasley
CHICAGO (Reuters) - A new drug for the most common form of leukemia in adults improves survival for patients whose disease has worsened despite standard treatment, according to late-stage study findings released on Saturday.
Ibrutinib, sold by Pharmacyclics Inc and Johnson & Johnson under the brand name Imbruvica, was approved by U.S. regulators for treatment of chronic lymphocytic leukemia in February.
The therapy "beat the pants off" of ofatumumab, or Arzerra, marketed by GlaxoSmithKline Plc, in the Phase 3 trial, said Dr. John Byrd, the study's lead investigator and a professor of medicine at the Ohio State University Comprehensive Cancer Center in Columbus, Ohio.
JP Morgan analyst Cory Kasimov said the trial results, along with the fact that the drug is a pill that does not need to be combined with another therapy, could help propel sales.
Pharmacyclics said earlier this month that it expected Imbruvica revenue of $295 million this year, which disappointed some investors.
The trial involved 391 patients with chronic lymphocytic leukemia that had progressed after two or more prior therapies. Standard treatment for such patients is a combination of chemotherapy and an antibody drug, such as Arzerra.
The results were presented at the American Society of Clinical Oncology (ASCO) meeting on Saturday in Chicago.
At a median follow-up of 9.4 months, the study found that ibrutinib lowered the risk of death by 57 percent compared with ofatumumab. Researchers said they expect the trial to result in median overall survival in the range of several years.
At median follow-up, 86 percent of patients on ibrutinib had responded to the drug and were continuing treatment with minimal side effects, compared with response rates between 35 percent and 40 percent for standard therapies, Dr. Byrd said.
Side effects associated with ibrutinib included diarrhea, minor bleeding and heart arrhythmias.
"These results provide a compelling new treatment option for patients with chronic lymphocytic leukemia, including older adults with this disease, and will significantly change (physicians') practice," Dr. Olatoyosi Odenike, a leukemia expert at the University of Chicago said in an ASCO statement. Odenike was not involved in the study.
The U.S. Food and Drug Administration in February approved Imbruvica as a secondary treatment for chronic lymphocytic leukemia. It was previously approved for mantle cell lymphoma patients who have tried other therapies.
Studies are also under way to test the drug as an initial treatment for chronic lymphocytic leukemia.
Imbruvica is an oral drug designed to target an enzyme known as Bruton's tyrosine kinase and block the function of certain cancerous cells.
Drugs in a similar class are under development by companies including AbbVie and Gilead Sciences Inc.
Chronic lymphocytic leukemia, a slowly progressing form of blood cancer, is diagnosed in about 16,000 Americans and will kill around 4,600 every year, according to the American Cancer Society.
(Reporting By Deena Beasley; Editing by Michele Gershberg, Jonathan Oatis and Nick Zieminski)