MicroGeneSys Inc. is left without a partner for developing itsgp160 HIV vaccine VaxSyn HIV-1, as Wyeth-Ayerst hasdecided to pull out of its 1990 agreement with thebiotechnology company.

The two companies announced Friday that they are negotiatingterms for Wyeth-Ayerst's parent, American Home Products, toterminate its involvement in development of the vaccine.

MicroGeneSys of Meriden, Conn., has been developing VaxSynsince 1987 for use as an AIDS therapeutic and as a possibleprophylactic vaccine. The fate of the vaccine was thrown intoquestion last October, following presentations at a NationalInstitutes of Health conference on advances in AIDS vaccinedevelopment. Although VaxSyn has generated neutralizingantibodies against standard laboratory strains of HIV, it has notbeen able to produce neutralizing antibodies against variants ofthe virus isolated from AIDS patients, so-called primary fieldisolates.

Only one vaccine, United Biomedical Inc.'s V3 loop peptidevaccine, has produced antibodies that could neutralize aprimary field isolate of HIV-1. In response to the datapresented at the conference, the National Institute of Allergyand Infectious Diseases (NIAID) halted its plans to launch aPhase III HIV vaccine trial, originally scheduled for October.The agency will review the field-isolate issue and decidewhether to launch the Phase III efficacy trials by the end of1994.

If such a trial is launched, it will probably be a multivaccinetrial. Last September, Rep. Henry Waxman, D-Calif., chairman ofthe Health and Environment Subcommittee, was briefed byseveral government officials, including Kristine Gebbie, nationalAIDS policy coordinator, and Anthony Fauci, director of NIAID,who opposed a single-vaccine trial (see BioWorld, Nov. 15).

In 1992, Congress appropriated $20 million to the Departmentof Defense for a single-vaccine Phase III trial of VaxSyn, whichevoked an outcry in the medical community.

-- Brenda Sandburg News Editor

(c) 1997 American Health Consultants. All rights reserved.