(Reuters) - A pivotal trial of Gilead Sciences Inc's drug idelalisib has been stopped early after independent monitors determined that the drug was shown to be effective against Leukemia, sending shares of the company up more than 3 percent.
The Phase 3 trial compared treatment with idelalisib and another drug, Rituxan, to treatment with Rituxan alone in patients with chronic lymphocytic leukemia who were not eligible for treatment with chemotherapy.
Idelalisib is part of a new class of medications designed to selectively block a type of protein known to promote tumor growth in certain types of blood cancer.
Gilead said an interim analysis by the Data Monitoring Committee overseeing the trial found that the drug had a significant impact on the length of time patients survived without their disease getting worse.
"This was a modest upside surprise to us in both timing and result," ISI Group analyst Mark Schoenebaum said in a research note.
He said Wall Street analysts, on average, expect the drug to have sales of $100 million in 2015, $450 million in 2016 and $800 million in 2017.
"We believe that consensus numbers will likely go up in the near term," Schoenebaum said.
Gilead said it is discussing the trial results, and a potential regulatory filing, with the U.S. Food and Drug Administration.
The company filed last month for FDA approval of the drug as a treatment for non-Hodgkin's lymphoma.
Idelalisib patients in the recently stopped trial will continue receiving the drug, while others will be offered the option of switching to the experimental pill, Gilead said.
Gilead, which has dominated the market for HIV drugs and is vying for a lead position in therapies for hepatitis C, is testing idelalisib as a treatment for a number of different blood cancers.
Shares of the company, which closed at $58.90 on the Nasdaq, were up 3.2 percent at $60.80 in after-hours trading.
Reporting by Deena Beasley; editing by Matthew Lewis and Andrew Hay