(FORTUNE Small Business) – For Ernest Lynton, the diagnosis was a death sentence. He had cancer of the pancreas, a disease so lethal that he would be lucky to live six months. Surgery had failed--the tumor was too large--and the usual cocktail of chemotherapy drugs didn't hold much promise. He might very well have written a will and waited to die. But Lynton was a scientist by training, a retired physicist, and he was intrigued by the notion of using his cancer to advance knowledge. So he opted to try an experimental drug that seemed to make headway against aggressive tumors like his. Miraculously, the drug shrank the tumor and gave him more than a year of life. The 70-year-old Bostonian used the time joyously, working, traveling, visiting his children and grandchildren. On one of those trips, he and his wife even made a detour to satisfy his scientific curiosity. In 1997 he tracked down the chemist who had created the drug, Stephen Webber, and visited him in his lab outside San Diego. There, the trio marveled at computer images of the drug's molecular structure as they swirled brightly on the screen. Lynton would write to Webber a few months later: "We wanted to tell you how much we owe you ... Your accomplishments have given us a year of quite unexpected ... life."

What none of the three knew that day was that the drug was about to be shelved. Despite an estimated $72 million of investment and more than a decade of work in the lab and on the cancer ward, Agouron Pharmaceuticals had decided to abandon Thymitaq, as the drug was called. Data from the clinical trials were mixed, and the cost of additional testing would be in the tens of millions before the company could seek government approval to sell it.

Besides, executives decided, there was more money in treating AIDS. The number of cases was soaring, and AIDS advocates were demanding new drugs. In the midst of such a raging epidemic, rare cancers just didn't seem as urgent--or as profitable. Ernest Lynton and the other patients who poured the yellowish juice called Thymitaq into their veins were about to become footnotes in a physician's dusty file.

Thymitaq might have faded away if not for an unlikely little company led by an entrepreneur on a hunt. Elizabeth Corsi, 49, is an accomplished veteran of the pharmaceutical industry who left the lush corporate life five years ago to run a pinch-penny startup called Eximias Pharmaceuticals in Berwyn, Pa. "I could make a good living in Big Pharma," she says with characteristic bluntness, "but I want to make a fortune." Toward that end, she is betting on Thymitaq. Convinced that Agouron had missed a big opportunity in the early clinical trials--tests to determine whether the drug is safe and effective in humans--she has spent five years fighting to bring the castoff drug to market.

If she succeeds in winning approval from the U.S. Food and Drug Administration to sell Thymitaq , it could be a blockbuster. The drug would be the first ever approved treatment for inoperable liver cancer, and doctors probably would combine it with other chemotherapy drugs to treat cancers of the pancreas, breast, colon, and head and neck. "This is the last frontier in cancer," Corsi says. "By 2008, Thymitaq will do $500 million a year."

The risks are high. A Phase III clinical trial--the final test before seeking FDA approval--is costly and time-consuming. Eximias will spend $50 million to test Thymitaq. After three years the company has recruited only 325 of the 446 patients it needs in the trial. (Some oncologists are reluctant to have their patients try Thymitaq because it got a bad reputation for toxicity and intolerable side effects during early-stage trials years ago.) To gain FDA approval, Corsi will have to show that patients on the drug lived significantly longer--even if only a matter of weeks, in the case of such an aggressive cancer--than those receiving the most common chemotherapy treatment. Until the trial is completed, neither she nor her investors can know whether the drug will pass or fail. Yet Corsi has found investors willing to take the gamble. At presstime, Eximias was in the final stages of raising $40 million from investors in the U.S. If successful, it probably will be among the largest private-equity financing deals in the pharmaceutical and biotech industries this year.

Thymitaq's story hardly follows the standard regimen for how new drugs come to market. This is an industry dominated by behemoths: Lilly, Merck, and Pfizer, to name a few. Only giants have the resources to handle drug development. Tufts University's Center for the Study of Drug Development estimates the cost of developing a single new drug is $802 million. Still, the rewards can be substantial. The cancer therapeutics market will be worth about $23 billion by 2005, more than double what it was less than a decade ago. Chemotherapy drugs like Corsi's are the fastest-growing segment of the treatment market.

Finding a lost but promising drug--and bringing it to market--is difficult but potentially lucrative. Consider the cool logic of an investment banker who specializes in biotech financing: "You have just been diagnosed with inoperable liver cancer, and you have, at best, seven weeks to live," says E. Hunterson Henrie, a managing director of Ferghana Partners in New York, who is advising Eximias. "How much would you pay for a year?"

Corsi paid a relative pittance for the worldwide rights to Thymitaq. For months after joining Eximias as chief operating officer in 1998, she had been shopping for drugs. (She was named chief executive in 2001.) Her purse was small. Asian and U.S. investors had put only a few million dollars into the venture at that point. She was visiting Agouron's offices in California seeking to buy rights to another drug when executives slid a black notebook across the table and invited her to consider licensing Thymitaq. "I was speechless," she recalls. "This was the company's flagship oncology compound, the jewel in the vault." Agouron was about to be acquired and executives wanted to unload drugs that weren't in its main line of business, AIDS. (Agouron is now part of Pfizer.) That night, as she pored over the inch-thick binder in her hotel room, Corsi was electrified by the data. "What a slick piece of chemistry," she says. "This drug had extraordinary characteristics."

Specifically, one bit of data caught her eye: a graph detailing how quickly patients recovered from neutropenia after a course of Thymitaq. Neutropenia is a type of suppression of the immune system. Other chemotherapy drugs wipe out patients' immune systems for as long as a month, raising the risk they would die not from the cancer but from the treatment--from their inability to fight off infection. With Thymitaq, patients were regaining immune-system strength within one to five days. Also, Thymitaq seemed to be effective in tablet form. Most chemotherapy is given intravenously, requiring patients to check into a clinic. Chemotherapy by pill would be a major advance, a faster, more convenient, and less expensive way of treating cancer. None of the top ten cancer drugs can be taken by mouth. "I was meant to find this drug," she says. "Losing this one would have been a tragedy."

Not to Agouron's way of thinking. Development on Thymitaq was stopped because of "economics," according to a spokeswoman. Webber, the chemist who had created the drug, was devastated. "I thought this drug could really help," he says. But Agouron didn't want to spend the money to complete clinical trials for it. Moreover, liver cancer was a relatively rare disease a decade ago in the U.S., though it was a much bigger problem in Asia. Now liver cancer is on the rise here. That's partly because of the large influx of immigrants from Asia and partly because of the recent epidemic of hepatitis B and C, which in later stages can lead to liver cancer.

Other executives could have easily overlooked the downtrodden drug's upside potential. But, then, Corsi has a remarkable business and educational pedigree. First-generation Italian, the eldest in a working-class family of five children reared near Pittsburgh, she holds a doctorate in pharmacy and an MBA. Earning those degrees was a hard-fought battle. "My father was an old-fashioned man," she says. "He was adamantly opposed to my going to college, but my mother was insistent that I should be able to support myself and my family." (Her siblings are similarly credentialed; three brothers are physicians, and a sister is a nurse.)

After a brief stint as a hospital pharmacist, Corsi found her calling: selling pills rather than counting them. "A pharmacist's personality: introverted, judgmental, rigid, narrow," she says, recalling a personality test she once took. "Not me." She conveys a fierce, single-minded ambition: $10 million to $20 million in her bank account. At 3 A.M., she'll fire off e-mails to underlings, colleagues, and investment bankers. "How soon can I do the IPO?" she wants to know.

Her talent and drive were evident early in her career. In the mid-1980s, as a product manager for Lederle Laboratories, now a unit of Wyeth, she was responsible for promoting an aging but still-effective antibiotic. She began by surveying the competition. Doctors' waiting rooms were full of sales reps laden with the usual cheap trinkets--pens, key fobs, and calendars--intended to win doctors over. So Corsi upped the ante. She ordered a truckload of leather-bound chess sets with marble pieces from Taiwan, then decks of cards featuring viruses instead of royalty--and so on. Soon her reps were in the physicians' inner sanctums, filling their order books. Sales of the antibiotic tripled from about $34 million a year to $100 million.

Over the next two decades she held a series of ever more challenging positions within the pharmaceutical industry. One taught her some valuable lessons about the burgeoning cancer industry. In the early 1990s, as a VP for Rhône-Poulenc Rorer, now Aventis, she oversaw early-stage marketing of a new breast-cancer drug, Taxotere. That's when she saw the emergence of a trend. Patients, once the weak and frightened pawns at the unfortunate center of the medical drama, had begun to wield more power and demand specific drugs. Educated, organized, and vocal, they could be mobilized--which is partly why the company broke with tradition and undertook one of the first mass-market ad campaigns for a drug. Today Taxotere is second among the top-selling cancer drugs in the world, with $1.2 billion in sales in 2002. (Though Corsi had moved on to another job and did not oversee the marketing of the drug after it had been approved, she says, "I probably would have done the same.")

As she analyzed the prospect of licensing Thymitaq, Corsi realized the drug would pose a considerable marketing challenge. In limited early trials, Thymitaq had proved its ability to shrink some large solid tumors, typically the most difficult of cancers to treat. But the drug had gotten a bad reputation among some cancer specialists for toxicity and side effects such as nausea and vomiting. In her view, that stemmed from flaws in the design of the trial. Patients who participated in the early trial were barred by Agouron from taking anything that would have alleviated such side effects as vomiting. "Barbaric," says Corsi of the trial's structure. Some patients quit the trial because the side effects were unbearable. (An Agouron/Pfizer spokeswoman said the clinical trial's design had been approved by the FDA, and added that she found it unfair to judge trials of a decade ago by today's standards.)

Corsi was certain she could repair the drug's reputation with a better-designed clinical trial and a strong marketing campaign aimed at doctors and, perhaps, patients. Still, she knew there were many more hurdles. Completing the final phase of testing would take at least five years. Eximias would have to recruit liver specialists to conduct the investigation, and that would be difficult and costly. At the major cancer centers, where many seek treatment for the rarest and most difficult to treat tumors, doctors disdain these kinds of drug trials. They tend to prefer the more prestigious--and career-boosting--experiments on early-stage, unproven drugs. That meant finding oncologists at smaller community hospitals willing to do the work.

Before making a final decision, Corsi mobilized a formidable network of colleagues and mentors to ask for advice. Among them: Margaret Earl Gantt, a chain-smoking physician with whom Corsi worked at Lederle in the 1980s. As director of clinical development at Lederle, she had been responsible for introducing a series of new drugs that over time generated hundreds of millions in revenue. Gantt had retired, but agreed to look over the data on Thymitaq. Within a day, Corsi got a terse e-mail from Gantt: "Lots of data." The following day another came: "Good data." Then came the assessment she had been waiting to hear: "This is a drug." The endorsement from Gantt, who has since died, was powerful, indicating that the drug appeared to be effective--and valuable too.

Corsi quickly made an offer for worldwide licensing rights to Thymitaq: $350,000. It was a low-ball bid--companies typically pay millions for drug-licensing rights--but it was all she could afford. Agouron accepted it. One footnote: If the drug is approved and sales prove substantial, Agouron/Pfizer will receive royalties.

Immediately Corsi focused her efforts on the FDA. She asked the agency to designate Thymitaq an orphan drug and to put it on the fast-track for review. Orphan drugs are those used to treat rare diseases, those that affect fewer than 200,000 Americans a year. Such regulatory designations can be a major boon for companies that develop drugs, giving them special incentives such as extended patent protection and tax credits for research costs. By 2001 she had achieved both aims. She also won the support of the American Liver Foundation, an influential nonprofit advocacy group based in New York.

Phase III trials are underway, and Corsi reports that she's hearing encouraging anecdotes from the oncologists who are testing it. Her effort will stumble without more money, though. Investors are wary. Biotech and drug development is a boom-and-bust business. Unfortunately for Corsi, the industry is now in the bust part of the cycle.

But even beyond those hurdles, Corsi has run into an unexpected problem. Her single biggest investor is Nina Wang, 67, one of Asia's wealthiest businesswomen. Last year a Hong Kong judge ruled in a probate proceeding that she had "probably" forged her husband's will just before he was kidnapped in 1990. His body was never found. But nonetheless Wang inherited $128 million, from which she has created a multibillion-dollar empire. (Wang, who has appealed the ruling, declined FSB's request for an interview.) Wang does not have a controlling interest, and her participation in the company is limited. (Corsi's own equity stake now amounts to 2%.)

Still, seeing Wang's name on a roster of investors worries some potential investors, who fear her legal problems could reflect badly on the business. In a frantic rush to round up the cash, Corsi has flown all over the world. "Sometimes I feel like I am running a race, handcuffed and blindfolded," she says. By November, Henrie, the investment banker, had assembled a group that he says is willing to commit $40 million.

With that, Corsi will set to work this year building a company. Her projections are heart stopping. Consider the numbers: $15,000 per patient, 5,500 patients the first year. That's $82.5 million. She will hire several dozen $200,000-a-year reps to push the drug in hospitals and clinics. To win the support of leading oncologists, she may let them try it on some patients free. She's also considering a series of media and advertising campaigns to try to mobilize patient support.

Thymitaq is no miracle potion. In treating liver cancer, small advances are considered a victory. "For now," says Corsi, "the best we can hope for is to improve survivability." In layman's terms, that means a few more weeks or months or years of life. Still, to those who sit across from a doctor hearing the word "incurable," a little more time is a precious gift. "These cancers are lethal and aggressive, and we have nothing with which to treat them," says Dr. Keith Stuart, an oncologist at Beth Israel Deaconess Medical Center in Boston, who was involved in the early clinical trials of Thymitaq. "Anything would be a miracle."