(Adds analyst comment, competitor share reaction)
July 23 The U.S. Food and Drug Administration said on Wednesday it has approved Gilead Sciences Inc's Zydelig, a drug to treat three types of blood cancer.
The FDA approved the use of Zydelig in combination with Roche AG's Rituxan for patients with relapsed chronic lymphocytic leukemia (CLL).
It also approved Zydelig under a so-called accelerated approval program for relapsed follicular B-cell non-Hodgkin lymphoma (NHL) and relapsed small lymphocytic lymphoma, when patients have received at least two prior therapies.
For drugs given accelerated approval, companies must conduct additional trials to confirm that the drug's apparent benefit is real.
Zydelig, known generically as idealisib, will carry a boxed warning highlighting the risk of serious and potentially fatal toxicities, including liver toxicity, diarrhea, inflammation of the colon and lung, and perforation of the intestine.
It will be marketed using a special risk management program.
"We believe this broad boxed warning will lead docs to be cautious with this drug," Joseph Pantginis, an analyst at Roth Capital Partners, said in a research note.
Shares of Gilead rose 0.4 percent to $89.66 in afternoon trading. Shares of Pharmacyclics Inc, which makes a rival product, Imbruvica, for chronic lymphocytic leukemia and mantle cell lymphoma and does not carry a boxed warning or risk management program, rose 8.8 percent to $105.05.
Geoff Porges, an analyst at Sanford Bernstein, forecasts revenue for Zydelig growing to $1.5 billion in 2017, higher than the consensus estimate for that year of $990 million.
"Gilead has global rights to the product, and are likely to commercialize it for multiple indications and subtypes of NHL as well as CLL," Porges said in a research report.
Porges said his more optimistic view on the drug is based on its activity in indolent NHL and lead in this disease over Imbruvica and other drugs in the class.
(Reporting by Toni Clarke in Washington; Editing by Susan Heavey and Steve Orlofsky)