West Coast Editor

Gilead Sciences Inc.'s bid to win marketing approvals for Viread against hepatitis B virus in the U.S. and Europe could mean upside for the compound - which sold $154.9 million in the third quarter as an HIV therapy - that's been overlooked so far by Wall Street, and investors are due for a full look at the data from a pair of supporting trials early next month.

That's when Gilead will offer results from the pair of Phase III pivotal studies, 102 and 103, which compared Viread (tenofovir disoproxil fumarate) to Foster City, Calif.-based Gilead's Hepsera (adefovir dipivoxil). Top-line data were disclosed in June, and details are due at the annual meeting of the American Association for the Study of Liver Diseases in Boston.

Preliminary results of the first Phase III study showed that 71 percent of HBV e-antigen (HBeAg)-negative patients on Viread had a complete response at 48 weeks vs. 49 percent on Hepsera. The second trial, conducted in HBeAg-positive patients, showed 67 percent of patients on Viread had a complete response at 48 weeks vs. 12 percent on Hepsera. HBeAg is a protein that appears later in the disease, after the surface antigen has been detected, but does not show up in all variations of HBV.

Gilead's stock (NASDAQ:GILD) rose 98 cents on word that the marketing applications have been submitted, closing Friday at $43.30.

Hepsera for chronic HBV has sold well, and chalked up sales of $75.2 million for the second quarter, up 32 percent from a year ago. If Viread, whose active ingredient is the most widely used molecule for HIV in the U.S., wins a label in HBV as well, peak sales could reach about $250 million, and some analysts call that number conservative. Launch of Viread for HBV could happen in the second half of next year.

Early jitters regarding the chance that Viread could cut into Hepsera sales seem to have settled somewhat, as observers point to a growing HBV market and the likelihood that patients who are doing well on Hepsera will stay on it.

Company officials could not be reached Friday, but Cara Miller, spokeswoman for Gilead, said the firm likely will have more to say about Hepsera, Viread and HBV during the third-quarter earnings call Thursday.

Gilead's Truvada - which combines Viread with the company's Emtriva (emtricitabine) - has proven the star in HIV lately, tallying sales of $385.4 million for the second quarter vs. $299.2 million in the year-ago period. Sales outside the U.S. accounted for about $199 million of the total (vs. $91.5 million last year), with Europe showing especially strong.

Worldwide, more than 400 million people are afflicted with chronic HBV, which can lead to liver cancer and cirrhosis, and the complications kill up to 1.2 million people each year, making HBV one of the world's top 10 causes of death. In the U.S., about 1.3 million people are living with the disease, and more than half are Asian American. In Europe, about 1 million get infected each year. Of those, about 90,000 develop chronic HBV.

Along with the Phase III data with Viread at AASLD, Gilead's shares could get a boost from more data related to the Phase Ia trial with the firm's non-nucleoside polymerase inhibitor, GS-9190, for hepatitis C virus. The company already has said the single-dose approach garnered promising activity, but analysts are hoping for details about results with multiple doses.

Others making news lately with HBV bids include Pharmasset Inc., which started a Phase III trial with its once-daily pyrimidine nucleoside analogue, clevudine, already sold as Levovir capsules in South Korea. Two 48-week trials are designed to show superiority of clevudine 30 mg over Hepsera 10 mg, each administered once daily as monotherapy. Study 305 will enroll about 376 chronic HbeAg-positive patients, and Study 306 will sign up about 480 who are HBeAg-negative with chronic disease. (See BioWorld Today, Oct. 2, 2007.)