SOUTH SAN FRANCISCO, Calif. -- Genentech Inc. on Friday saidit is discontinuing clinical trials of CD4-IgG to treat adults withAIDS. However, the company will refocus its CD4-IgG programon studies aimed at preventing transmission of the humanimmunodeficiency virus (HIV) from infected pregnant womento their fetuses.
Genentech said the results of pre-clinical and Phase Itherapeutic clinical studies of about 90 symptomatic HIV-positive patients showed no consistent clinical improvement.These trials began in August 1989 and are due to end thismonth.
AIDS researchers have focused their attention on the CD4receptor of T helper cells, a class of white blood cells. HIVinfects and eventually kills these cells by binding to the CD4receptor.
At one time, three companies were engaged in research on CD4as an AIDS therapeutic. Last February, SmithKline Beecham ofPhiladelphia said it was de-emphasizing its program testingsoluble CD4 as an AIDS therapeutic.
Biogen Inc. of Cambridge, Mass., is also investigating CD4. Atthe Fifth International Conference on AIDS, held in Montreal inJune 1989, Biogen said studies of CD4 showed low toxicity, butlittle efficacy. Dr. Lawrence Corey of the University ofWashington, who was working with Genentech's CD4-IgG,reported similar findings at last year's AIDS conference in SanFrancisco.
While Genentech researchers may be giving up on CD4-IgG asan AIDS therapeutic, the company said it shows promise as atreatment to prevent transmission of the virus from infectedpregnant women to their fetuses. In the April 13, 1990, issueof Nature, Genentech reported that CD4-IgG is able to cross theplacental barrier.
The virus is present in the bloodstreams of about one-third of12- to 15-month-old infants born to HIV-infected women. HIVspreads from a mother to her fetus in the late stages ofpregnancy, said Genentech spokeswoman Susan Rogers.
Last year, the Centers for Disease Control estimated that by1991 there would be 10,000 to 20,000 children under the ageof 13 infected with the AIDS virus.
Genentech will conduct three initial trials of CD4-IgG as anAIDS transmission preventative. The first, a safety study oninfants between the ages of 1 and 3 months born to HIV-infected women, is enrolling patients.
A second study, scheduled to begin in the middle of this year,will administer CD4-IgG to HIV-infected pregnant women inlate stages of pregnancy. A third study will administer higherdoses of CD4-IgG to pregnant woman. The hope, said Rogers, isthat enough CD4-IgG will cross the placenta to bind to all thevirus and prevent fetal infection.
Genentech's CD4-IgG program is conducted under contract fromGenentech Clinical Partners IV, which owns CD4-IgG. Thelimited partnership was formed in June 1989 to developrecombinant CD4 products as therapeutic agents for HIV.
-- Karen Bernstein BioWorld Staff
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