AEGiS-13IAC: Initiation of a Phase III efficacy trial of bivalent B/E rgp120 HIV vaccine (AIDSVAX(tm) B/E) in Bangkok, Thailand.

13th International AIDS Conference

Durban, South Africa - July 9-July 14, 2000

Initiation of a Phase III efficacy trial of bivalent B/E rgp120 HIV vaccine (AIDSVAX(tm) B/E) in Bangkok, Thailand.

Int Conf AIDS 2000 Jul 9-14; 13:(abstract no. WeOrC555)

Choopanya K; K. Choopanya, Bangkok Metropolitan Administration, Taksin Hospital, BVEG Office, 3rd Floor, 543 Somdej Choaphya Rd, Khet Klongsarn, Bangkok, 10600, Thailand, Tel.: +662 863 2121, Fax: +662 863 2129, E-mail: kachitc@dmc.inet.co.th

BACKGROUND: Since 1988, injecting drug users (IDUs) in Bangkok have experienced a severe epidemic of HIV infection. A 1995-98 study conducted in this group showed an annual incidence rate of at least 6%, willingness to participate in HIV vaccine trials, and high rates of follow-up. The bivalent B(MN)/E(A244) rgp120 HIV vaccine, specifically designed to match HIV strains in Thailand, was previously found to be safe and highly immunogenic in phase I/II trials. In March 1999, a phase III efficacy trial was initiated in Bangkok using AIDSVAX(tm) B/E vaccine.

METHODS: Following informed consent, 2500 IDUs attending 17 drug treatment clinics will be randomized in a blinded fashion to AIDSVAX B/E vaccine (300ug of each antigen) or placebo (1:1 ratio) at months 0, 1, and 6, with booster doses at months 12, 18, 24, and 30. Interim safety and efficacy analyses will be conducted by an independent DSMB. The study is designed to last 3 years following recruitment and to detect efficacy of at least 30% (1 é endpoint - protective "sterilizing" immunity as measured by ELISA and Western blot; 2 é endpoint - reduced viral load measured by RNA PCR).

RESULTS: As of 17 January 2000, 2463 volunteers were screened and 1304 were enrolled (93% male; mean age 30 years). Immunization compliance has been 100% (1198 and 517 received the second and third doses, respectively). Thus far, only 6 volunteers have been lost to follow-up and 5 deaths have occurred (none were vaccine related). Immunizations have been well tolerated with no severe vaccine-related side effects.

CONCLUSIONS: The first phase III efficacy trial of an HIV vaccine among a high-risk population of IDUs has been initiated in Bangkok, Thailand. To date, recruitment is proceeding well, follow-up is excellent, and adverse effects are unremarkable. With completed enrollment, an interim efficacy analysis is expected in 2002.

Keywords: AEGIS, AIDS Vaccines, Clinical Trials, HIV Infections, Thailand, Viral Load, Incidence, Vaccination, Double-Blind Method, AIDSVAX, Male
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