As flashy new entries piled into the race to create an injection-free hepatitis C drug about a year ago, Xconomy’s national biotech editor, Luke Timmerman, likened the contest to the Daytona 500 of the pharmaceutical world.
Now Pfizer, the world’s biggest drug company, has scratched itself from the starting lineup. The New York pharmaceutical giant has shelved its small molecule compound filibuvir, whose other tag was PF-00868554.
Pfizer wasn’t considered a frontrunner in the hotly competitive field, where Foster City, CA-based Gilead Sciences (NASDAQ: GILD) seemed to emerge with the edge after its presentations at a November meeting of the American Association for the Study of Liver Diseases in Boston. Others making a strong showing at the meeting included Abbott Laboratories (NYSE:ABT) of Abbott Park, IL; Bristol-Myers Squibb (NYSE: BMS); Merck, based in Whitehouse Station, NJ; and Germany’s Boehringer Ingelheim.
The prize they’re all vying for is a share of a potential $15 billion market for hepatitis C drugs. Worldwide, there are 180 million people infected with the virus, including four million in the United States, according to the National Institute of Allergy and Infectious Disease. Current treatments have side effects that can discourage patients from taking them; so new options could prevent dire consequences. A chronic infection of the liver with the hepatitis C virus can lead to two potentially fatal conditions—liver cancer, and the severe liver damage called cirrhosis.
Patients infected with the treacherous hepatitis C virus have already benefited from a first wave of recent treatment improvements over the long-established standard therapy, which consisted of injections of interferon along with tablets of a drug called ribavirin.
In May of 2011, the FDA approved two new products: Cambridge, MA-based Vertex Pharmaceuticals‘ (NASDAQ: VRTX) drug telaprevir, which it markets as Incivek; and boceprevir, which is marketed as Victrelis by Merck (NYSE:MRK). Both are pills taken in conjunction with interferon and ribavirin to boost the effectiveness of those standard treatments, and both belong to a class of drugs called protease inhibitors. Telaprevir and boceprevir were the first two approved drugs to act directly to block the hepatitis C virus from replicating.
Vertex’s telaprevir is the market leader with total 2012 revenues of $1.16 billion. But now Vertex’s competitors are trying to replace telaprevir with new all-oral drugs aimed at eliminating the need for interferon injections, which can cause daunting flu-like symptoms.
Pfizer had been one of those Vertex rivals. It had taken its drug candidate, filibuvir, into Phase 2. When it recently scrapped the project, it wasn’t due to safety concerns, a company spokeswoman said Monday. In a prepared statement, Pfizer said it had halted work on the drug after considering the best use of its resources for pipeline development.
“We decided to discontinue PF-00868554 (filibuvir) for the treatment of the Hepatitis C Virus after a strategic review,” the company stated. “We continue to prioritize our R&D capital allocation to drive the next wave of innovative medicines and vaccines that bring benefit to patients and value to health care systems around the world.”
That leaves one less contender jockeying for position as drug developers race toward an injection-free hepatitis C drug. The field is complex because these drugs are being tested in various combinations in a search for the best formula. Some companies are teaming up to see if their drugs work well together.
Gilead has combined two compounds from its own stable of drug candidates for hepatitis C, sofosbuvir and GS-5885, in a once-daily combination it hopes will eliminate the need for interferon. Gilead’s sofosbuvir has also been tested with good results in combination with Bristol-Myers Squibb’s daclatasvir (NYSE: BMS).
Vertex, eager to retain the revenues it gained by developing telaprevir, is developing its own next-generation drug, VX-135. The compound will be used in three different combinations: with ribavirin; with simeprevir, a protease inhibitor being developed jointly by Janssen R&D Ireland and Medivir AB; and with GlaxoSmithKline’s experimental drug GSK2336805. Vertex expects to begin the Phase 2 trials during the first half of 2013.
The prospects for an interferon-free hepatitis C regimen look promising, said researcher Catherine Stedman of Christchurch Hospital, Christchurch, New Zealand in a January review article in the Journal of Gastroenterology and Hepatology. Investigators have been able to suppress virus levels sustainably through eight different combinations of drugs that act directly on hepatitis C replication (DAA drugs), without including interferon, Stedman found. There may be room in the market for a range of these formulas, because the various hepatitis C viral strains may respond differently to different drug combinations.
“The prospect of interferon-free combination DAA therapy for hepatitis C virus is now finally becoming a reality,” Stedman said in her review paper.