San Francisco Chronicle (SF) - FRIDAY, July 21, 1995 Edition: FINAL Section: Business Page: B1 Word Count: 984
Carl T. Hall, Chronicle Staff Writer

Hepatitis C, a mystery microbe every bit as elusive as the virus that causes AIDS, is one of the more important causes of liver disease -- a so-called silent killer that afflicts an estimated 150,000 Americans each year.

Baseball great Mickey Mantle's drinking habits got a lot more attention, but it was alcohol in combination with the Hepatitis C virus that wiped out his liver and required a life-saving transplant.

Were it not for the occasional celebrity liver-disease victim -- they include singer Naomi Judd, the late TV newsman Frank Reynolds and actors Larry Hagman and Jim Nabors -- Hepatitis C virtually would be unknown outside medical circles.

The virus was discovered by a Chiron team that included Michael Houghton, head of Hepatitis C research, and fellow scientists Qui Lim Choo and George Kuo. Emeryville-based Chiron also was the first to develop a way to screen blood supplies for the virus.

Routine testing has prevented an estimated 1 million new infections. It also generated the lion's share of Chiron's $454 million in sales last year and about $75 million in profits. (Losses elsewhere cut overall income to $18 million.)

The hepatitis screen has helped make Chiron the No. 3-ranked biotechnology company with a market value of about $2.3 billion.

But there's still no vaccine to prevent the virus from spreading. Nor is there a cure. Houghton said preliminary studies of a potential Chiron vaccine are encouraging, with human clinical trials expected to get under way in 1996. It would take several more years before a product might be available.

In the alphabet soup of hepatitis viruses, C is the most commonly diagnosed culprit in liver-transplant cases. Yet Hepatitis C "is the one nobody talks about," said Dr. Teresa Wright, chief of gastroenterology at the San Francisco Veterans Administration Hospital.

About the best that can be said about the bug is that it's far less deadly than HIV. Victims may become ill with flu-like symptoms for a few weeks after the initial exposure. Then the virus typically goes into hiding for years while it quietly goes to work on the liver. Eventually, the result is cirrhosis or liver failure which, without a transplant, is fatal.

The virus typically is transmitted through blood contact and probably through unprotected sexual activity, although nobody can explain the source of about 40 percent of the chronic cases.

Some 3.5 million people in the United States now carry the C virus, compared with 1 million to 1.5 million thought to be infected with HIV, the virus that causes AIDS. Wright noted that fully 10 percent of the patients admitted at the VA Hospital, for whatever reason, carry Hepatitis C in their blood. At least 80 percent of all those who contract the virus develop a chronic infection, compared with fewer than 10 percent for the better-known Hepatitis B virus.

The only approved treatment in the United States is alpha interferon, an expensive drug with dangerous side effects.

The medical tragedy will translate into a multibillion-dollar market for whoever arrives first with a vaccine or cure.

Amgen Inc., based in Thousand Oaks, recently completed key clinical trials on a Hepatitis C interferon drug called Infergen, but the company said it needed more time to evaluate the data before deciding whether to seek regulatory approvals.

Merck, SmithKline and Biogen, among others, are testing different forms of interferon. Protein Design Labs Inc., based in Mountain View, is testing a drug that might seek out and destroy the hepatitis virus as it circulates in the blood.

San Mateo-based SciClone Pharmaceuticals Inc. is one of the furthest along in clinical testing of a possible new treatment. In May, the company reported that its drug, Zadaxin, showed favorable results when administered with alpha interferon. Further results are expected as early as August. The firm yesterday said it has started selling Zadaxin overseas to physicians who request it.

Analyst Dennis Roth at Northeast Securities in Great Falls, Va., said the odds are good SciClone will seek government marketing approvals. "Nothing works that well with chronic Hepatitis C," he said, "but the preliminary data are interesting from SciClone."

SciClone CEO Thomas Moore concedes that it's a long shot. "Hepatitis C," he said, "is really a difficult virus."

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A HIGHER PROFILE FOR HEPATITIS

Liver disease, caused by several viruses in cluding the elusive hepatitis C virus, is afflicting more and more Americans, including celebrities such as Mickey Mantle, Larry Hagman and Naomi Judd. Here are some key facts about the disease: -- Hepatitis, or inflammation of the liver, occurs when the virus replicates in the body and attacks the liver, sometimes causing permanent damage. There usually are few symptoms during early stages of the infection.

-- An estimated 150,000 Americans are infected each year with Hepatitis C. About 3.5 million now carry the virus.

-- The virus is spread through blood contact, such as through sharing of needles among intravenous drug users. In more than 40 percent of cases, the cause of infection is unknown. Blood supplies now are routinely screened for the virus since its discovery in the early '80s.

-- The only approved treatment is the drug Alpha Interferon, which boosts the body's natural immune response. But the drug is expensive, can cause side effects and usually does not eliminate the infection permanently.

-- Chiron Corp. expects to begin clinical trials next year on a possible vaccine for Hepatitis C. Sciclone Pharmaceuticals is in late-stage trials of a drug, Zadaxin, that may work in combination with inteferon to boost its effectiveness. Sources: American Liver Foundation, Chiron, Sciclone Pharmaceuticals, Associated Press

CAPTION: PHOTO, Chiron scientists George Kuo (left), Qui-Lim Choo (center) and Michael Houghton studied lab findings on the Hepatitis C virus/BY LIZ HAFALIA/THE CHRONICLE

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