Investigation of V520 in an HIV Vaccine Proof-of-Concept Study (V520-023)

A Multicenter, Double-Blind, Randomized, Placebo-Controlled Phase II Proof-of-Concept Study to Evaluate the Safety and Efficacy of a 3-Dose Regimen of the Merck Adenovirus Serotype 5 HIV-1 Gag/Pol/Nef Vaccine (MRK AD5 HIV-1 Gag/Pol/Nef) in Adults at High Risk of HIV-1 Infection

This study will test the safety and efficacy of an investigational Human Immunodeficiency Virus (HIV) vaccine. Efficacy will be measured by either prevention of HIV infection or control of HIV viral load in subjects who become HIV infected.

On September 18, 2007 the Protocol V520-023 DSMB (Data & Safety Monitoring Board) reviewed data from a planned interim analysis. These data demonstrated that the investigational vaccine candidate was not effective, and all vaccinations in the study were halted.

Participants were encouraged to continue to come to the clinic for scheduled visits and ongoing risk reduction counseling since the vaccine was not effective.

No further treatment was given in V520-023, however participants were followed. V520-023 protocol ended earlier than originally planned per protocol and participants (HIV infected and uninfected) had the option of participating in an observational long term follow up protocol called V520-030/HVTN 504, which served as an extension of V520-023 and would continue through the end of 2009.

Inclusion Criteria:

• Healthy, HIV seronegative adults at high risk of acquiring HIV infection
• Cannot have previously received an investigational vaccine

Exclusion Criteria:

• In a monogamous relationship with an HIV-1 seronegative partner for > 1 year
• History of anaphylaxis and/or allergy to vaccine components, including Tris buffer, MgCl2, and polysorbate 80 (TWEEN)
• Received an immune globulin or blood derived products 3 months before injection with the first dose of vaccine/placebo or scheduled within 14 days after injection
• Previously vaccinated with a live virus vaccine within 30 days before injection with the first dose of vaccine or scheduled within 14 days after injection
• Previously vaccinated with an inactivated vaccine within 5 days before injection with the first dose of vaccine or scheduled within 14 days after injection
• Known history of immunodeficiency
• History of malignancy (with some exceptions)
• Contraindication to intramuscular (IM) injection such as anticoagulant therapy or thrombocytopenia
• Female subject who is pregnant or breast feeding, or expecting to conceive or donate eggs through Week 30 of the study
• Male subject who is planning to impregnate or provide sperm donation through Week 30 of the study
• Previously received an investigational HIV vaccine
• Has active drug or alcohol abuse or dependence that would interfere with adherence to study requirements, or endanger the subject's health while on the study
• Has a condition that might endanger the subject's health or interfere with the evaluation of the study objectives