In the early 1980s, the human immunodeficiency virus (HIV) was identiÂfied as the etiologic agent of acquired immune deficiency syndrome (AIDS). More than 3 million people worldwide died from HIV/AIDS in 2003, according to a July 2004 United Nations report. During the same period, about 5 million people contracted the human immunodeficiency virus, bringing the total number of people living with HIV worldwide to 38 million. Although AIDS was called the Â«gay menâ€™s diseaseÂ» at the beÂginning of the outbreak, it was soon discovered that sexual intercourse was not the only way of transmission. Blood transfusions and mother-to-baby transmission also spread the virus.
In comparison to the scourges caused by other viruses in history, we were more prepared and have achieved astonishing milestones against AIDS, thanks to our accumulated knowledge and efforts around the globe. HIV was identified and shown to be the cause of AIDS in less than 2% years. It took only another 2 years for blood tests to become commercially available. In 1987, the first anti-HIV drug, AZT, was introduced. With the arrival of the HIV protease inhibitors and triple drug therapy (the cocktail therapy) in 1995, many patients who would otherwise have died are still alive. In 1996, Time magazine named AIDS researcher David Ho Â«Man of the YearÂ» for his revolutionary idea of the cocktail therapy.
Who discovered HIV was such a contentious isÂsue that it took the President of the United States and the Premier of France to settle the dispute.
In 1983 Francoise Barre-Sinoussi and Luc Montagnier, in the laboratory led by Montagnier at the Institut Pasteur de Paris, first detected and later isoÂlated a retrovirus, lymphadenopathy-associated virus (LAV), which they believed was the cause of AIDS. During their research on the virus, Montagnierâ€™s labÂoratory collaborated with Robert C. Gallo, a renowned virologist at the National Cancer Institute (NCI), who was one of the most widely referenced scientists in the world in the 1980s and 1990s. Montagnier and Gallo frequently exchanged virus sampies and information. In April 1984, Gallo held a press conference anÂnouncing that his laboratory had isolated a retrovirus, human T-lym-photrophic virus (HTLV-III), that he believed to be the cause of AIDS. Gallo was basking in scientific glory and was widely considered a leading contender for the Nobel Prize. Soon it was confirmed that Galloâ€™s HTLV-III and Montagnierâ€™s LAV were identical. In 1986, a nomenclature comÂmittee was set up, chaired by Harold Varmus, an expert in avian retrovirus and then director of the NIH. The NIH committee settled on the name of human immunodeficiency virus (HIV).
In April 1984, Galloâ€™s laboratory filed a patent on an HIV blood test kit using his HTLV-IIIB-ELISA (enzyme-linked immunosorbent assay), which was issued in a record 13 months via a special category involving naÂtional security. Although Institut Pasteur had filed a patent in the United States much earlier, in December 1983, it was not granted until a later date. Galloâ€™s HIV test kit was approved by the FDA in 1985. An acrimonious leÂgal battle ensued for the priority of the discovery of the HIV between the French and American teams. The contentious scientific and legal controÂversies came to an end in March 1987 when a historic agreement was signed by the directors of the NIH and the Institut Pasteur and ratified by Ronald Reagan and Jacques Chirac. The patents would become the joint properties of the two institutions, which would share the royalties. The three inventors from the NIH, including Gallo, would receive $100,000 annually from the royalties earned.
Even the intervention by two heads of state did not put the matter to rest. In November 1989, a Pulitzer Prize-winning investigative reporter, John Crewdson, published a 50,000-word article in the Chicago Tribune on the Montagnier-Gallo priority dispute. He concluded that Gallo had either stolen or allowed his samples to be contaminated with Montagnierâ€™s virus. The controversy generated resulted in congressional investigations. In the end, it was found that Mikulas (Mika) Popovic from CzechoslovakÂia, a cell biologist in Galloâ€™s laboratory, had isolated HTLV-III from a pool by mixing several blood samples from different sources, including Montagnierâ€™s sample, which contained LAV. Pooling blood samples was an unusual practice in virology. In 1991, Gallo admitted in Nature that he had not discovered the new virus. In 1996, he left the NCI, where he had worked for 30 years, to become the director of the Institute of HuÂman Virology at the University of Maryland Biotechnology Institute in Baltimore.
In 1987, the first anti-AIDS drug, AZT, was introduced by Burroughs Wellcome. AZT, which blocks HIV reverse transcriptase activity, stands for azidothymidine, with the generic name of zidovudine and the trade name of Retrovir. Popular media often give the credit to Gertrude Elion of Burroughs Wellcome for having discovered AZT. In fact, alÂthough Elion and George Hitchings (see chapter 1, page 19) developed the concept of using nucleotides as antimetabolites in treating cancers, AZT itself was synthesized by a group led by Jerome Horowitz of the Detroit Institute of Cancer Research in 1964 as a possible anticancer drug. Horowitz, now a professor at Wayne State University, published his synÂthesis as a note in the. Journal of Organic Chemistry in 1964.
Since its birth, AZT had a checkered life as a drug looking for a disease to treat. AZT did not show efficacy in treating cancers; the drug also failed to prolong the lives of leukemic animals. In 1974, a German laboratory found it effective against viral infection in miceâ€”Wolfram Ostertag of the Max Planck Institute for Experimental Medicine showed that leukemia helper virus (LLV-F) replication by AZT occurred via phosphorylation of AZT to the corresponding triphosphate, which cannot be incorporated into the growing strand of DNA. Ostertag correctly concluded that AZT-triphosphate worked by binding to the growing strand of DNA. BurÂroughs Wellcome acquired AZT and explored the possibility of using it to treat the herpes virus under the guidance of Gertrude Elion, although it did not make it to the market.
In 1984, shortly after Gallo announced his discovery of the retrovirus, HTLV-III, the head of the NCI, Samuel Broder, organized a team to screen antiviral agents as possible treatments for AIDS. In all, more than 50 pharmaceutical companies submitted their possible antiviral drug canÂdidates to Broderâ€™s team for screening. Together with Dani Bolognesi, an AIDS researcher at Duke University, Broder obtained some of the potenÂtial antiviral compounds from Burroughs Wellcome. In February 1985, usÂing an assay developed by Hiroaki Â«MitchÂ» Mitsuya, AZT was found to be active in vitro in the NCI laboratories in Bethesda. Wellcome patented AZT as an antiviral drug in June 1985 and promptly commenced the cliniÂcal trials. As with cancer drugs, the Phase I trials for AIDS drugs are done with patients rather than with healthy volunteers. The first trials to test AZT in patients with HIV showed dramatic efficacy. For ethical reasons, the company terminated the trials and switched patients on placebo to AZT immediately. The FDA approved the use of AZT on March 19,1987, within 22 weeks. The recommended dose was one 100-mg capsule every 4 hours around the clock. Thus AZT established itself as the first antiviral drug in the arsenal against HIV. The mechanism of action of AZT is the blockade of the HIV reverse transcriptase activity. Reverse transcriptase, first isolated by David Baltimore and Howard Termin in 1970, is the enÂzyme that transcribes RNA into DNA. The success of AZT incited the deÂvelopment of many nucleotide anti-HIV drugs in an effort to minimize the toxicities that AZT displayed.
Among the newer reverse transcriptase inhibitors, Ziagen represents a vast improvement over AZT, a nucleotide whose gycosidic core structure is metabolized rapidly. Whereas AZT has to be taken every 4 hours around the clock, Ziagen allows a twice-daily regimen. When the oxygen on AZT is replaced with a methylene group, carbocyclic nucleoside analogs such as Ziagen are metabolized much more slowly by the body. Ziagen was develÂoped by Glaxo Wellcome (now part of GlaxoSmithKline) using a technolÂogy developed by Robert Vince of the University of Minnesota, who licensed the patent to Glaxo Wellcome in 1993.
Robert Vince is a professor of medicinal chemistry and director of the Center for Drug Design at the University of Minnesota. After completing his Ph.D. training in 1966, he began his independent research in the field of antiviral medicine. In the mid-1970s, he designed an antiviral comÂpound, carbocyclic Ara-A (cyclaradine), that was more effective in comÂbating herpes virus than acyclovir was. Because he did not patent his discovery, it was difficult to entice the pharmaceutical industry to develop it. That experience taught him a lesson on the importance of intellectual properties. In the mid-1980s, inspired by the success of AZT, Vince started to tinker with nucleosides as HIV reverse transcriptase inhibitors. In retrospect, it was logical for him to replace the oxygen on the nucleoÂsides related to AZT with a methylene group in order to improve bioavail-ability. But at that time, it represented a significant improvement. Along with a visiting researcher from China, Mei Hua, he synthesized a group of carbocyclic nucleoside analogs, which they called carbovirs. The NIH tested the carbovirs and found them to be the most active compounds in their screen against HIV since AZT. In fact, the carbovirs were the first compounds found active against HIV that were specifically synthesized for that purpose. In 1987, the University of Minnesota patented their synthesis and a group of antiviral drugs, listing Vince and Hua as coin-ventors. The university subsequently licensed the patent to Glaxo Well-come, which arrived at Ziagen by substituting a propyl cyclopropyl group for the purine ring using the synthetic route developed by Vince. Because of Ziagenâ€™s favorable pharmacokinetics profile, it allows a twice-daily regÂimen and has brought in hundreds of millions of dollars in sales for the company.
The credit for any important discovery often seems to be a contentious issue. In this case, the stakes were high, as both AIDS and a large sum of money were involved. Glaxo claimed that Ziagen was not covered by the Vince-Hua patent because the patent did not cover Ziagen per se, whereas Minnesota contested that alkyl surely included cyclopropyl. In October 1999, the University of Minnesota and Glaxo settled this dispute, and as part of the settlement Glaxo agreed that the University patents were valid and enforceable. The settlement brought a financial windfall for MinÂnesota and the inventors. With the Ziagen money, estimated at $250 milÂlion thus far, Minnesota established a Center for Drug Design, with Vince as its director. Vince is putting his share of the Ziagen money to work on potential new AIDS drugs and other potential antiviral and anticancer agents at the center.
In addition to AZT and Ziagen, many HIV reverse transcriptase inÂhibitors exist. An organic chemistry professor at Emory University, Dennis Liotta, and his virologist colleague, Raymond Schinazi, discovered another reverse transcriptase inhibitor 3TC (lamivudine, Epivir), which allows a once-daily regimen. BMSâ€™s d4T was licensed from Yale University. The drug gained international fame when activists at Yale persuaded the uniÂversity to rewrite a license agreement with BMS so that generic d4T could be sold in South Africa. BMSâ€™s ddl was approved in mid-1991, and nevi-rapine (trade name Viramune) by Boehringer Ingelheim was approved by the FDA in June 1996.