Nine years after Chairman Wayne Hockmeyer bet the company on a single drug, MedImmune Inc. is the fourth-biggest biotechnology company in the world - and on the cusp of a whole new set of challenges spawned by its success.

Wall Street, accustomed to the 30-plus percent annual profit growth fueled by MedImmune's Synagis drug for an infant respiratory virus, wants more of the same, even as Synagis' sales growth begins to slow.

So Gaithersburg-based MedImmune is forging ahead with a new bet: that the Food and Drug Administration will approve its inhalable influenza vaccine as early as next month. MedImmune projects that the nasal mist vaccine, once approved, could generate $1 billion in annual sales, the proceeds to be split between MedImmune and Wyeth, its co-promotion partner.

"Clearly ... they're putting a lot of stake in FluMist as the next big revenue-driver," said Jill Kiersky, an analyst with Morningstar Inc. in Chicago. But, she said, "I think they've set their goals extremely high."

MedImmune is a far cry from the company it was in 1993, when the FDA's rejection of its first drug - Respigam for respiratory syncytial virus - threatened to push the company out of business. The money-losing company that hunkered down and focused its then-meager cash on pushing the drug through another set of clinical trials is now Maryland's most profitable biotechnology firm.

It derived more than 80 percent of its $618.7 million in revenue last year from a successor drug, Synagis, for the same disease, and posted profit of nearly $149 million for the year.

The current gamble on FluMist provides an example of how the pressure remains intense as a biotech company matures.

Many of the state's more than 300 biotech companies are losing money and scrambling for cash as they push to put their first drugs on the market. But MedImmune is at the other end of the spectrum - pressured to maintain huge year-over-year profit gains from already marketed drugs. MedImmune's other marketed drugs include Ethyol to moderate certain cancer-treatment side effects and CytoGam to prevent against organ transplant rejection. But they don't promise returns nearly as big as Synagis.

Preserving the company's collegial, innovative culture has become more difficult as 14-year-old MedImmune has ballooned to 1,500 employees worldwide and 650 in Maryland, elbowing out an atmosphere in which, Hockmeyer remembers, "everybody was on a first-name basis."

Just how MedImmune handles this stage of its growth may have a lasting effect on a region that so far has few profitable companies that research, make and market their own drugs. If the company can prove that it is more than a one-drug wonder, it could solidify its future and anchor the region's shift from a research center to a significant biotech manufacturing one.

"Human Genome Sciences and MedImmune are the shining stars of success, from research and development and clinical trails and into biomanufacturing," said David Iannucci, secretary of the state's Department of Business and Economic Development, referring to the development-stage biopharmaceutical company in Rockville that is making drugs for clinical trials in its Maryland plants. "It's crucial" to the recruitment of other companies that Maryland "be able to point to companies going through all these stages."

MedImmune Chief Executive Officer David Mott doesn't appear worried. During a recent interview in his first-floor office, the one-time investment banker outlined the company's plans for long-term success. MedImmune, he said, will continue to put a heavy focus on its own research efforts while looking to acquisitions when they complement the company's core focuses. Those focuses are infectious diseases, autoimmune diseases and cancer.

Since his promotion to CEO in October 2000, Mott also has taken a number of steps to try to ensure the growing company doesn't lose its collaborative edge. The steps are focused in part on what Mott refers to as "democratizing the information flow." He has, for example, expanded the company's executive committee from a handful of people. It now includes all vice presidents and senior vice presidents and meets every Monday morning. Even the design of the company's new headquarters building is aimed at ensuring that the paths of researchers' and executives cross. MedImmune broke ground on the $85 million first phase this month.

"We've actually turned back the clock," he said. "You have to actively seek out bureaucracy and political fiefdoms and eliminate that."

But near-term, FluMist will tell whether MedImmune is able to maintain its growth. The company acquired the vaccine by buying Aviron this year for $1.7 billion in stock. MedImmune has been circumspect about exactly how it expects to price the vaccine and at whom it will be marketed. It prefers to await the FDA's decision.

Analysts, however, expect the vaccine to be priced at a premium to current influenza vaccines, which use inactivated viruses. Those vaccines are selling for the upcoming flu season at about $6 a dose, said David Webster, a Bethlehem, Pa.-based consultant who works with drug companies on pricing and other issues. He said he expects FluMist to be priced at $18 to $25 a dose.

MedImmune and analysts such as Deutsche Bank's Dennis Harp see marketing advantages to FluMist. The vaccine may be more palatable to children and their parents because it's not an injection. And sales demand may be boosted by the fact that an advisory committee to the National Centers for Disease Control recently recommended the influenza vaccine for all children ages 6 months to 23 months.

"There's no question there will be a marked increase of flu vaccines in children beginning this next fall because of the recognition that flu [can] cause severe complications," said Dr. Neal Halsey, director of the Institute for Vaccine Safety at the Johns Hopkins Bloomberg School of Public Health. "This will make it a lot easier to give this vaccine" to children.

But the FDA has expressed concern about the safety of the vaccine in previous communications. MedImmune has included information to address those in a 20-plus volume filing to the FDA. One concern is related to the vaccine's use of a live, though weakened, virus. Theoretically, such a vaccine could cause more severe side effects, though Halsey said testing of FluMist in thousands of patients has not resulted in such effects.

Webster said MedImmune's real challenge will be in mastering the manufacturing and marketing. Flu strains change every year, forcing manufacturers to wait until federal health officials identify them - usually in the spring - to manufacture the vaccine against the proper strain.

Influenza vaccines currently are largely ordered in bulk by family practitioners, drugs stores and others, who pay for them on delivery. They then sell the shots to customers.

Webster said the business goal of those who offer vaccines to patients is to bring them in for the shot, sell the vaccine for slightly more than they bought it and hope the patients buy other products or services while they're there.

Over the past several years, when influenza vaccines were in short supply, buyers were willing to pay more for them. Wholesale prices rose from about $2 a dose in the late 1990s to the $6 price today, Webster said.

"If FluMist had launched then, they may have had a chance to crack into the market," Webster said. But now, he said, manufacturers of the traditional vaccine have geared up to protect their market share. "We don't think FluMist is $500 million [a year] in our wildest dreams."

MedImmune obviously disagrees. But Mott, while acknowledging that FluMist is "a big bet and it's a very important bet," said that it's just one of the many drugs the company is developing.

Unlike in 1993, when it was struggling along on a few months of cash at a time, MedImmune had $731 million in cash and marketable securities at the end of March.

"It's very different ... ," Mott said. "We were betting the company in those days."