April 11 (Bloomberg) -- Amgen Inc., the world's largest biotechnology company by sales, is developing six cancer drugs to help recover from a decline in its anemia products.

Amgen plunged 32 percent last year in Nasdaq trading after its top-selling anemia medicines, Aranesp and Epogen, were linked to risks of tumor growth and death. The company depends on those treatments for 41 percent of its revenue.

The market for cancer drugs has doubled in the past four years, and will be worth $67 billion worldwide in 2012, according to research firm Decision Resources Inc. Amgen's anti-cancer undertaking is risky as about 95 percent of cancer drugs entering human tests fail to become marketed products, according to the Dana-Farber Cancer Institute in Boston. Amgen will provide preliminary drug data, mostly from animal tests, next week.

``They are a bit late to the party,'' said Michael King, an analyst with Rodman & Renshaw in New York, in a telephone interview. Amgen has ``marketing muscle'' that could help turn a new cancer drug into a sales success, he said. ``They're not going away, despite all their troubles,'' King said.

The six drug candidates, five of which were generated internally, are being tested in more than 30 clinical trials under way or planned, Amgen said.

Attacking Tumors

The medicines are designed to attack tumors through three of the most popular approaches in cancer research today. One drug, called AMG-386, cuts off blood flow to tumors like Genentech Inc.'s Avastin, which had $2.3 billion in U.S. sales last year. The Amgen treatment is designed to block more proteins that lead to blood vessel formation than Avastin does alone.

Another experimental drug, AMG-655, provokes cancer cells to commit suicide. A third treatment, AMG-479, blocks a chemical signal that allows tumor cells to grow uncontrollably.

Data on the drugs' effectiveness in animals will be made public at the American Association for Cancer Research annual meeting April 12-16 in San Diego. The company will offer a glimpse in 2009 on whether some of its drugs work in people.

Amgen's fourth-quarter profit rose less than 1 percent, as sales of its arthritis drug Enbrel and spending cuts partly offset a decline in its anemia drug business. Aranesp and Epogen generated $6.1 billion in 2007 sales, a decline from $6.6 billion a year earlier. Amgen had $14.8 billion in revenue in 2007, falling short of its $15.4 billion to $16 billion forecast.

Amgen fell 97 cents, or 2.2 percent, to $43.01 at 4 p.m. in Nasdaq Stock Market composite trading. The stock has dropped 7.4 percent this year.

First Attempt

Amgen's effort to discover cancer drugs began in 2001, fueled by revenue from the anemia business. Its first marketed medicine was acquired in 2006 through the $2.2 billion takeover of Abgenix Inc. The product, Vectibix for colorectal tumors, was predicted to generate $2 billion a year in sales.

The drug was marketed to physicians and Wall Street as a safer and less expensive alternative to ImClone Systems Inc.'s Erbitux.

Instead of being safer, Vectibix appeared to be more risky. A study of more than 1,000 newly diagnosed patients was halted in March 2007 after Vectibix raised the risk of death when used with Avastin. Vectibix ended up generating $170 million in its first year on the market.

``Maybe they won't be as hypey with their next compound,'' said King, the Rodman & Renshaw analyst.

Amgen's vice president of global oncology development, David Chang, said the company has learned a lesson from the Vectibix experience. Amgen is testing its new candidates in smaller, proof-of-concept studies that enroll 120 to 200 patients, Chang said. It is collecting patients' tumor samples to identify who might benefit in larger trials.

``One has to base all the decisions on science, and build the right level of evidence before moving to definitive studies,'' Chang said in a telephone interview.

New Approaches

Amgen is seeking to break ground in cancer research with AMG-655, which triggers suicide of cancer cells, Chang said. It is designed to stimulate a protein that sends a signal leading to programmed cell death. It appeared to work against tumors with minimal side effects on healthy cells in animals, Chang said. No other marketed drug works this way, and Amgen believes it is among the leaders in development, Chang said.

The company's AMG-479 aims to inhibit a protein called IGF- 1, which appears in almost all tumor types, Chang said. When stimulated, it provides cancer cells a survival edge over healthy cells, so blocking it could make tumors more vulnerable to treatment, he said.

Other companies, including Pfizer Inc., ImClone and Schering-Plough Corp. have said they are pursuing the IGF-1 blockers. Amgen insists it can compete.

``We are a relatively late entry to oncology,'' Chang said. ``This is a field that's evolving, so I don't think we're too late. Sanofi and GlaxoSmithKline were leaders in oncology not long ago, and I don't think they have the claim to fame in 2008. We don't think this is going to be a field with clear winners and losers. There's so much opportunity to go around.''

To contact the reporter on this story: Luke Timmerman in San Francisco at ltimmerman@bloomberg.net

Last Updated: April 11, 2008 16:17 EDT