A Phase I, Multicenter, Randomized, Double-Blind, Placebo-Controlled HIV-1 Vaccine Trial to Evaluate the Safety and Immunogenicity of rgp120/HIV-1MN (Genentech) in Combination With QS21 Adjuvant and/or Alum in Healthy Adults.

PRIMARY: To examine the safety and potential improvement in immune responses elicited by combining rsgp120/HIV-1MN with the adjuvant QS-21. SECONDARY: To examine the role of alum in the vaccine/adjuvant formulation; to determine the optimal dose ratio of vaccine to adjuvant; and to obtain initial information on the optimal schedule of administration. AS PER AMENDMENT 07/02/97: To determine the ability of immunization with rsgp120/HV-1MN in combination with QS21 with or without alum to induce an HIV-1 envelope-specific delayed-type hypersensitivity (DTH) response in volunteers who undergo rsgp120/MN skin testing. Immune responses in HIV-uninfected individuals receiving subunit envelope vaccines formulated with alum adjuvant suggest that functional antibodies capable of neutralizing HIV-1 in vitro may be induced, but the titers are relatively low in comparison to those measured in individuals with natural HIV-1 infection. These limitations might be overcome by the addition or substitution of a more suitable adjuvant such as QS-21.

Immune responses in HIV-uninfected individuals receiving subunit envelope vaccines formulated with alum adjuvant suggest that functional antibodies capable of neutralizing HIV-1 in vitro may be induced, but the titers are relatively low in comparison to those measured in individuals with natural HIV-1 infection. These limitations might be overcome by the addition or substitution of a more suitable adjuvant such as QS-21. Volunteers are randomized to 20 treatment arms containing four patients each. rsgp120/HIV-1MN is administered at four dose levels: 0, 100, 300, and 600 mcg, and QS-21 adjuvant is administered at three dose levels: 0, 50, and 100 mcg. Some subject cohorts receive alum in the vaccine formulation. Sixty volunteers receive injections at months 0, 1, and 10, and 20 volunteers receive injections at months 0, 1, and 6. AS PER AMENDMENT 07/02/97: All consenting volunteers who have received three immunizations will be tested for DTH response to HIV-1 envelope with use of intradermal MN rsgp120. Follow-up is extended to 56 days after administration of the intradermal injections.