NEWS OF THE
WEEK
be marketed and, from a deal made earli er this year by Immunex, five BristolMyers Squibb oncology products will be comarketed. Immunex will have exclusive North American rights to new products developed. For these products, Cyanamid will have rights in all other countries. Cyanamid also will have the right of first refusal on new Immunex products—other than anticancer drugs—aimed at markets outside North America. Ann Thayer
Recombinant blood dot factor cleared for sale The Food & Drug Administration and the Canadian Bureau of Biologies have granted the first marketing licenses for a recombinant form of factor VIII. Factor VIII is the blood clotting factor that is deficient in persons with hemo philia A, the most common form of the disease. The drug is just the second new genet ically engineered product to get FDA clearance in 1992, joining Chiron's interleukin-2. The drug results from a 10-year R&D collaboration between Genetics In stitute, a 12-year-old biotechnology firm in Cambridge, Mass., and its marketing licensee worldwide, Baxter Healthcare, Deerfield, ΠΙ. It also is the first product to win FDA approval for Genetics Institute, which wiU manufacture it in bulk and
receive royalties on sales. Recombinant factor VHI differs only in the way it is made—in tissue culture— from factor VHI currently available, which is extracted from large quantities of hu man blood. The recombinant protein has pharmacokinetic behavior equivalent to material derived from blood plasma, but eliminates any possibility of transmitting diseases such as AIDS and hepatitis. However, FDA stresses that all antihemo philic factors currently licensed in the U.S. are prepared in ways believed to elimi nate the risk of transmitting those viruses. Baxter currently produces and markets a form purified from blood plasma. Factor Vin was among the first geneti cally engineered proteins to be developed.
genes, had been deleted. All of the ani mals have remained healthy for more than three years after innoculation with the mutated virus. Twenty-seven months after the vacci nation, four of the six vaccinated animals were challenged with standard doses of wild-type, pathogenic SIV. None devel oped evidence of SIV infection. Thirtyseven weeks after the initial challenge, two of the same four animals were chal lenged with very high doses of patho genic SIV. Again there was no subse quent evidence of SIV infection. The researchers say they do not know what mechanisms are responsible for the protective immunity observed in the ex periments. They note that most viral vac cines currently in use in humans are of the live attenuated variety, because it is "diffi cult to match live virus infection for the strength, breadth, nature, and duration of the immune response that is generated." Their current results "suggest that live attenuated HTV-1 may also be the most potent, effective vaccine for the prevention of AIDS," the researchers report. Safety Vaccination with a live, attenuated simi concerns are likely to be the key issue for an immunodeficiency virus (SIV) com development of this vaccine approach in pletely protects rhesus monkeys from humans, because the approach involves SIV infection, according to researchers at infection with a retrovirus, rather than Harvard Medical School's New England simply exposure to retroviral antigens. Nevertheless, if other vaccine approaches Regional Primate Research Center. The vaccine offered "the most impres show little or no efficacy, "limited safety sive protective effects we have seen in any testing of live, multiply deleted HIV-1 in of our vaccine experiments/' the scientists high-risk human volunteers seems war reported last week in Science [258, 1941 ranted," the researchers conclude. In another report on AIDS research (1992)]. Indeed, the team, led by Ronald G Desrosiers, suggests that the approach last week in Science [258, 1935 (1992)], may be applicable to developing a vaccine Larry O. Arthur and coworkers at the against human immunodeficiency virus National Cancer Institute's Frederick Cancer Research & Development Center (HIV-1), which causes AIDS. Developing an effective AIDS vaccine demonstrate that human cellular pro has proved to be far more difficult than teins associate with the surface of immu researchers predicted when HIV-1 was nodeficiency viruses like SIV and HIV-1. identified in 1984. Efforts to develop a The proteins, β2 microglobulin and hu protective SIV vaccine—generally ac man lymphocyte antigen (HLA) DR α cepted as a model for an HIV-1 vac and β chains, are present in appreciable cine—also have largely failed, despite re amounts on the viruses. The research searchers' ability to employ riskier strat suggests that the proteins play an active egies in developing candidate animal role in the life cycles of these viruses. Researchers reported in 1991 the vaccines than with human vaccines. SIV candidate vaccines tested so far anomolous result that monkeys vacci have included SIV subunits, inactivated nated with uninfected human cells whole SIV particles, and vaccinia virus were protected to some degree against subsequent infection with SIV grown recombinants that express SIV genes. Desrosiers and primate research cen in human cells. The NCI results sug ter collaborators Muthiah D. Daniel, gest that antibodies to proteins found Frank Kirchhoff, Susan C. Czajak, and on human cells may disrupt SIV func Prabhat K. Sehgal vaccinated six mon tion by binding to the β2 microglobulin keys with SIV from which a portion of or HLA DR molecules on the virus. Rudy Baum the nef gene, one of the SIV regulatory
Genentech licensee Miles also expects ap proval soon. Several years ago, Genetics Institute and Genentech cross-licensed— on a worldwide, royalty-free basis—factor VIA patents and its orphan drug designa tion, which gives companies a seven-year exclusive market. However, there is an ongoing patent interference proceeding before the U.S. Patent Office involving factor VIII pat ents held by Genetics Institute and Chi ron, which has licensed its patent to Novo Nordisk. And Scripps Clinic & Re search Foundation and drug producer Rorer claim that a patent they hold relat ed to factor Vin purification is infringed by recombinant products (C&EN, April 27, page 30). Genetics Institute says a court decision on this suit may come by mid-1993. Ann Thayer
Vaccine shields monkeys against AIDS
However, this factor is relatively large, somewhat fragile, and heavily glycosylat cial development. Both Genetics Institute ble drugs, which have been awaiting FDA and Genentech have now developed via clearance for over two and a half years. ed, so technical hurdles slowed commer
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DECEMBER 21,1992 C&EN
