Breakthrough AIDS drug will take years of work

Maryland firm's stock is flying high based on genetic code patent


February 18, 2000|By Mark Guidera | Mark Guidera,SUN STAFF

AIDS researchers and experts warned yesterday that Human Genome Sciences Inc.'s announcement that it had sequenced and patented the genetic code for a key doorway the virus uses to infect cells is no guarantee that any significant new drugs will ever be developed from the breakthrough.

In short, don't expect a "cure" or any dramatic new drugs anytime soon.

That didn't stop shares in the Rockville-based biotechnology company from spiking higher for a second day yesterday. They closed at $217.5625, up $29.5625, or 15 percent.

The main reasons experts urge caution on the news: First, new drugs to treat the disease have historically proved difficult to develop because the virus is so complex and confounding.

Second, having an organism's genetic code does not ensure that a drug can be developed to address it.

"It's nice to have the gene sequence, but who knows if it will lead to development of a drug 10 years from now or ever?" said Dr. Jeffrey Laurence, director of AIDS virus research at Cornell University's Weil Medical College in New York.

He notes that AIDS researchers have been aware of the doorway -- called a "receptor" -- for years, but that has not resulted in a fast turnaround developing new treatments.

Also, the expensive and lengthy clinical trials and regulatory approval process remain unchanged, even for drugs developed based on gene information, notes James McCamant, editor of the Medical Technology Stock Letter, a newsletter that follows the biotechnology industry.

"Having the gene sequence may open up some shortcuts for developing new treatments, but even with the shortcuts, it'll be a five-year process at best," said McCamant.

The Pharmaceutical Research and Manufacturers of America, a trade group, estimates it takes an average of eight to 10 years to develop a new drug and get it to market and costs more than $350 million.

Despite such cautions from experts, shares in Human Genome surged for a second day and hit a new trading high of $231 before falling back yesterday.

The biotechnology sector, which has been one of the hottest this year, also enjoyed a broad rally yesterday, lifting a number of Maryland-based companies' shares. MedImmune Inc. rose $10.75 to $192, Gene Logic Inc. jumped $18.14 to $102.14, and EntreMed Inc. rose $4.5625 to $62.5625.

On Wednesday, Human Genome soared 21 percent to $188 after the company disclosed that it had sequenced a gene responsible for production of what is known as the CCR5 receptor, a docking point on the surface of immune system cells.

Researchers have found that the human immunodeficiency virus uses that receptor to get inside cells and infect them. People who have a mutation in the receptor almost never get AIDS, experts said.

Human Genome announced Wednesday that it had landed U.S. patent protection on the CCR5 gene, and that several pharmaceutical companies that have paid to access its database of genetic information are working on developing drugs that inhibit the docking mechanism.

While Human Genome executives declined to discuss specifics of those projects, possible avenues being explored would include developing drugs that attach or "bind" to CCR5, in effect closing it off to the virus.

Meanwhile, Human Genome said it planned to pursue development of antibodies that might knock out the virus' ability to attach to the receptor.

Even so, the company and its pharmaceutical partners face competition in the effort to develop new AIDS treatments that block HIV from attaching to CCR5, said Laurence, who also is a senior consultant to the American Foundation for AIDS Research.

"There are many, many people developing a variety of [receptor] inhibitors," said Laurence.

As he and other experts note, a number of promising experimental drugs are already in development. Several of those seek to prevent the virus from docking on the CCR5 receptor. Other approaches seek to affect HIV's ability to infect cells through other pathways, including a receptor known as CXCR-4. Of the two receptors, CCR5 is considered by experts as the more promising target.

Among the first AIDS receptor inhibitors to enter human testing is a drug developed by AnorMED Inc., a Canadian biotechnology company. The drug is being tested in early human studies at several sites, including the Johns Hopkins University Medical Center in Baltimore.

Others developing CCR5 and CXCR-4 inhibitors for AIDS include New Jersey-based Schering Plough Corp. and Takeda Pharmaceuticals of Japan.

Dr. Craig A. Rosen, Human Genome's head of research and development, has said the company does not plan to block anyone's efforts to develop drugs that target CCR5. But it would seek royalties from any products developed based on the gene sequence.

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