After Years of Growing Pains, Biotechnology Stocks Are Coming of Age : Investing: Some stocks have made spectacular gains in the past 6 months. Analysts warn that there are still risks involved.

Biotechnology stocks are shining after years of volatility and some big setbacks.

Although plenty of roadblocks still lie ahead, there are more products nearing the market and more investor money is pouring in, prompting analysts to say the once-fledgling industry has at last come of age.

Over the last 6 months, some biotechnology stocks have more than doubled in value, and the biggest companies have jumped nearly 50% in value.

“The group is doing well because most of the technological risk is out of these stocks as they make the transition to commercialization,” said analyst Stuart Weisbrod of Prudential-Bache Securities Corp. “Most companies will soon introduce drug products, making the valuation on these stocks a lot more sane.”

Some biotechnology companies are pursuing genetic engineering to produce large quantities of rare proteins that are essential to the immune system or that play other important roles in fighting disease. The approval or impending approval of such drugs has sparked plenty of fireworks on Wall Street.

The stock of Seattle-based Immunex Corp., for example, has jumped to $30 a share from $12 last December. A federal Food and Drug Administration advisory committee will soon review an Immunex protein said to jump-start the immune system after bone marrow transplants. A favorable review could mean swift marketing approval from the FDA.

Chiron Corp.’s stock has jumped to $40.125 from $30.50 last December. That company received approval this year for its hepatitis C test kits.

Amgen Inc. of Thousand Oaks, now the second-largest biotechnology firm in the nation behind Genentech Inc., has soared to $81 from $59.50 a share last December.

Analysts say more investor money will pour into the industry once Roche Holdings Ltd. of Switzerland pays $1.6 billion to buy 60% of Genentech. The deal between Roche and Genentech, which is based in South San Francisco, was reached earlier this year.

“Most investors owned Genentech because they wanted to invest in biotechnology. That $1.6 billion will be freed up by the end of July. I think a fair amount will come back in to the biotech stocks,” said Jim McCamant, editor of the Medical Technology Stock Letter in Berkeley.

Another factor contributing to the bounce in the stocks are broader-based investor groups, said John Catterall, vice president at Biogen Inc., a biotechnology company based in Cambridge, Mass.

Catterall said that large pension funds, which have long avoided biotechnology, are now investing in it.

“The underlying fabric here is that historically biotech stocks have been owned by specialty funds and sophisticated niche players. What you see now is what I call mainstreaming--the traditional pension funds are getting a little toehold in the group,” he said.

The industry has also received a boost from a number of headline-making products.

One of these is a hormone that a preliminary study reports may be able to reverse the effects of aging. Others include a drug that increases the production of red blood cells, and one that dissolves blood clots and could be used to treat heart attack victims.

Among at least six new drugs await Food and Drug Administration approval are proteins to treat the side effects of chemotherapy and to combat septic shock, a life-threatening infection afflicting many surgery patients.

But investing in biotechnology is tricky. These stocks are volatile because investors are trying to assess the potential of products still being developed. Some drugs may not be as successful as analysts had expected.

“I think the stocks will cycle,” said Jeffrey Casdin, an analyst at Oppenheimer & Co. “They are in a long-term upturn that is not immune to market correction. But in the long term, the cycles will become less volatile as there are more products to underlie the earnings of these companies.”