Executive Summary

SOLUBLE CD4 VIABILITY AS AIDS TREATMENT SUPPORTED BY GALLO, chief of the National Cancer Institute's Tumor Cell Biology Laboratory. At an Aug. 28 press briefing following the annual meeting for AIDS researchers sponsored by his lab, Robert Gallo said his enthusiasm for soluble CD4 is undiminished even though "early results are disappointing" in several clinical trials. Gallo acknowledged that the clinical trials with CD4 showed "little effect," but attributed the situation to the "difficulty in maintaining blood levels" because of the rapid excretion of soluble CD4. The molecule has a half-life estimated at 15 to 30 minutes. At the international conference on AIDS in Montreal last June, Gallo hailed soluble CD4 as the closest research has come to the development of a "magic bullet" for AIDS. CD4 is believed to bind with the human immunodeficiency virus (HIV) and block the virus' ability to penetrate cells. In order to solve the problem of maintaining CD4 blood levels, Gallo's lab is reviewing gene therapy experiments developed by W. French Anderson, chief of the laboratory of molecular hematology at the National Heart, Lung, and Blood Institute. The experiments involve clinical implantation of an organism that would secrete CD4 and allow the molecule to be "expressed at a certain level all the time," Gallo explained. In the area of AIDS vaccines, Gallo reported that three research groups working with primates infected with simian immunodeficiency virus (SIV) presented their unpublished results at the annual meeting. Gallo said that the studies indicate "partial success and therefore major progress in a virus related to HIV." Each of the studies used vaccines consisting of whole dead virus. Although none of the studies demonstrated "100% protection" against infection, each of the groups showed that a "statistically significant number of monkeys" had either "delay or not yet disease development in animals that would by now have developed disease," Gallo reported. Gallo contended that a vaccine for AIDS is possible. In the area of immunotherapy, Gallo noted that Daniel Zaguary, University of Paris, has given pieces of viral protein of predicted benefit to people with AIDS. The results, as yet unpublished, "are very interesting and I predict will be an important avenue for therapy in the future," Gallo said.