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Ever-New Drug Cocktails for Containing AIDS: Drugs' New Era
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Ever-New Drug Cocktails for Containing AIDS: Drugs' New Era (One of a series on the rapid pace of drug development and its ramifications. A final story will deal with treatments for ailments of the aging.)
New York, July 23 (Bloomberg) -- Glaxo Wellcome Plc is working diligently on a new AIDS drug, Ziagen. It will be combined as a single dose with the company's AZT, the first effective treatment for the virus that causes AIDS, and Glaxo's more recent treatment for the disease, 3TC.
Within about two years, the British drug manufacturer may have five AIDS drugs on the market, including Combivir, approved last year. That's a sizable package for one company -- but in the case of AIDS, no number of drugs can be too many.
The existing combinations of drugs, or cocktails, that once seemed so promising in the fight against AIDS are losing their effectiveness as the HIV virus develops resistance to them. ''You need more drugs and more powerful drugs to keep up with the virus,'' said Jeffrey Kraws, an analyst with Everen Securities. ''We are a long way from a cure.''
AIDS, with an estimated 30.6 million people worldwide suffering from the disease or infected with HIV, is the most lethal disease caused by a virus or bacteria that still needs a cure or reliable treatment. Drugs to combat it carry great profit potential.
Sales of HIV treatments from Glaxo, Merck & Co., Roche Holding AG and others already comprise a market that will reach almost $4 billion in 1998 and rise to $5.5 billion in 2000, analysts estimate. Glaxo alone will register sales of $1.7 billion this year from its AIDS drugs and see that number about double by 2000, according to SG Cowen & Co., a securities firm.
Resisting Strains
Preliminary laboratory studies indicate Glaxo's new Ziagen drug, also called abacavir, may work on strains of HIV that can resist other drugs of a similar nature. HIV drugs work by interfering with enzymes HIV needs to infiltrate cells and then duplicate itself.
Ziagen attacks the same protein that Glaxo's existing HIV drugs do, reverse transcriptase, an enzyme that helps copy the genetic material of the virus.
Together with Vertex Pharmaceuticals Inc., a biotech firm in Cambridge, Massachusetts, Glaxo also is working on amprenavir, which attacks protease, an enzyme needed to chop up HIV proteins and help them spread from the infected cell to others. Studies indicate that this drug may be able to suppress HIV even when it hides in brain fluid.
One of the most promising new HIV treatments comes from Immune Response Corp., a company co-founded by the late Jonas Salk, who developed the polio vaccine and who as far back as 1987 was looking at immunization as a way of fighting AIDS. Immune Response, in a partnership with Agouron Pharmaceuticals Inc., could apply for U.S. approval next year of Remune, its treatment to boost the immune system's response in people infected with HIV.
Advantage
Agouron last year introduced Viracept, which battles HIV by interfering with a key enzyme called protease. The drug is taken three times a day with some food, making it easier to combine with other medicines that need to be taken that way. That gives it an edge over Merck's Crixivan, another protease inhibitor that is swallowed on an empty stomach.
Abbott Laboratories, Gilead Sciences Inc. and a joint venture of Merck and DuPont Co. all have new drugs in testing that could help control the virus. The pills would be added to existing combinations used to subdue HIV at least temporarily.
Warner-Lambert Co. is working on a drug designed to hit targets on the virus known as nucleocapsid protein zinc ''fingers,'' which seem to play a crucial role in several stages of duplication of the virus. These fingers don't seem to be able to mutate as quickly as the enzymes that existing HIV drugs attack. For that reason, the virus would have more difficulty becoming resistant. The drug is in early testing on humans.
The Vaccine Quest
Many companies search for the ultimate weapon, a vaccine for HIV, but it remains a wispy hope. French giant Rhone-Poulenc SA, Chiron Corp., American Home Products Corp. and closely held VaxGen all are testing vaccines in human volunteers, including VaxGen's president and lead researcher, Donald Francis.
Francis was one of the first to see AIDS as a disease caused by an infectious agent. He played a key role in battling the first outbreak of Ebola virus in Africa and worked on the development of a hepatitis vaccine.
American Home Products in May bought Apollon Inc., a closely held biotechnology company with a novel approach for vaccines for both HIV and hepatitis. Apollon uses DNA, the basic building block of genes, in its vaccines, a departure from more traditional methods that use proteins.
Rhone-Poulenc has the most versions of a vaccine in testing. Its vaccine unit, Pasteur Merieux Connaught, already has tested several vaccines in early studies in the U.S.
Tough Regimen
At the moment, the better hope for AIDS victims continues to be a phalanx of drugs that contains the disease. For these drugs to work, patients need to follow often complicated regimens and stick with the medicines even when they cause side effects, such as odd deposits of fat in the body, diarrhea and high cholesterol. People infected with HIV can take 20 or more pills a day to keep the virus under control. ''We need a lot of different combinations and we need to make this easier on people,'' said Roy Gulick, an assistant professor of medicine at Cornell University Medical College, who specializes in AIDS research.
AIDS is relentless. Those who treat it and suffer from it can only wish that drug companies are just as persistent in coming up with new treatments.
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