A Study of Safety, Tolerability and Immunogenicity of a 1-Dose Regimen of MRKAd5 HIV-1 Gag Vaccine Versus the ALVAC_HIV Vaccine (V520-019)

Study Overview
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Brief Summary
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This study is designed to determine whether patients previously primed with Ad5 of MRKAd5 HIV-1 gag vaccine respond better when boosted with ALVAC-HIV vaccine than when boosted with MKRAd5 HIV-1 gag vaccine.

Official Title
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A Probe Study of the Safety, Tolerability, and Immunogenicity of a 1-Dose Regimen of the MRKAd5 HIV-1 Gag Vaccine Versus the ALVAC-HIV (vCP205) Vaccine in Healthy Adults Who Previously Received a 3-Dose Regimen of MRKAd5, Ad5, or Placebo in Merck V520 Protocols 007 or 012

Conditions
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HIV-1 Infection

Intervention / Treatment
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* Biological: V520
* Biological: Comparator: ALVAC-HIV vaccine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Subject was previously enrolled in Merck HIV Vaccine study V520 Protocol 007 or 012, and received the complete 3-dose regimen during participation Subject is in good general health Subject is not infected with HIV Subject agrees not to donate blood during the first 52 weeks of the study Subject agrees not to donate sperm during the first 12 weeks of the study Subject who is of reproductive potential agrees to use an acceptable method of birth control through Week 12 of the study Exclusion Criteria: Subject has been administered immune globulin or blood product 3 months prior to receiving study vaccination Subject has been vaccinated with a live virus vaccine in the past 30 days Subject has been vaccinated with an inactivated vaccine in the past 14 days Subject has an active medical disease Subject is taking daily required prescription drugs Female subject is pregnant, breastfeeding or expecting to conceive Subject is positive for HIV Subject has used injection drug within the past year Subject has a sexual partner that is infected with HIV Subject has a sexual partner that is an active injection drug user Subject has been treated for or diagnosed with a new sexually transmitted disease in the past 6 months Subject engaged in unprotected intercourse with more than 2 persons in the previous 6 months Subject engaged in protected intercourse with more than 4 persons in the previous 6 months Subject has previously participated in an HIV vaccine clinical trial (other than Merck V520 Protocols 007 and 012) Subject weighs less than 110 lbs. Subject has a recent history of alcohol abuse Subject intends to donate blood in the first 52 weeks of the trial

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Stratum 1<br>Placebo recipients in the parent protocol (Merck V520 Protocols 007 or 012) will receive ALVAC-HIV Vaccine | Biological: Comparator: ALVAC-HIV vaccine<br>* A single dose 0.1 intramuscular injection<br>|
| Experimental: Stratum 2<br>Nonresponders who received active vaccine in parent protocol will be randomized to receive ALVAC-HIV vaccine or MRKAd5 HIV-1 gag vaccine | Biological: V520<br>* MRKAd5 HIV-1 gag vaccine, a single dose 1.0 mL intramuscular injection<br>Biological: Comparator: ALVAC-HIV vaccine<br>* A single dose 0.1 intramuscular injection<br>|
| Experimental: Stratum 3<br>Low responders who received active vaccine in the parent protocol will be randomized to receive ALVAC-HIV vaccine or MRKAd5 HIV-1 gag vaccine | Biological: V520<br>* MRKAd5 HIV-1 gag vaccine, a single dose 1.0 mL intramuscular injection<br>Biological: Comparator: ALVAC-HIV vaccine<br>* A single dose 0.1 intramuscular injection<br>|
| Experimental: Stratum 4<br>High responders who received active vaccine in the parent protocol will be randomized to receive ALVAC-HIV vaccine or MRKAd5 HIV-1 gag vaccine | Biological: V520<br>* MRKAd5 HIV-1 gag vaccine, a single dose 1.0 mL intramuscular injection<br>Biological: Comparator: ALVAC-HIV vaccine<br>* A single dose 0.1 intramuscular injection<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Safety and tolerability of ALVAC-HIV or MRKAd5 HIV-1 vaccine in subjects who previously received a 3-dose regimen of Ad5 HIV-1 gag vaccine measured by number of injection-site adverse experiences (AE), non serious systemic AE, lab AE, serious AE. |  | Injection-site AE up to 5 days after vaccination, non-serious systemic AE and Lab AE up to 29 days after vaccination, serious AE for the entire study period (Week 260). | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| immunogenicity of a single-dose regimen of the ALVAC-HIV vaccine or MRKAd5 HIV-1 vaccine measured by various assays |  | 4 weeks following vaccination |