Barbara Metch

Safety and efficacy of the HVTN 503/Phambili Study of a clade-B-based HIV-1 vaccine in South Africa: a double-blind, randomised, placebo-controlled test-of-concept phase 2b study

Summary We report the primary analysis of the safety and efficacy of the MRKad5 gag/pol/nef HIV-1 sub-type B vaccine in South Africa (SA), where the major circulating clade is sub-type C.BACKGROUND The MRKAd5 HIV-1 gag/pol/nef subtype B vaccine was designed to elicit T-cell-mediated immune responses capable of providing complete or partial protection from HIV-1 infection or a decrease in viral load after acquisition. We aim to assess the safety and efficacy of the vaccine in South Africa, where the major circulating clade is subtype C. METHODS We did a phase 2b double-blind, randomised test-of-concept study in sexually active HIV-1 seronegative participants at five sites in South Africa. Randomisation was by a computer-generated random number sequence. The vaccine and placebo were given by intramuscular injection on a 0, 1, 6 month schedule. Our coprimary endpoints were a vaccine-induced reduction in HIV-1 acquisition and viral-load setpoint. These endpoints were assessed independently in the modified intention-to-treat (MITT) cohort with two-tailed significance tests stratified by sex. We assessed immunogenicity by interferon-γ ELISPOT in peripheral-blood mononuclear cells. After the lack of efficacy of the MRKAd5 HIV-1 vaccine in the Step study, enrolment and vaccination in our study was halted, treatment allocations were unmasked, and follow-up continued. This study is registered with the South Africa National Health Research Database, number DOH-27-0207-1539, and ClinicalTrials.gov, number NCT00413725. FINDINGS 801 of a scheduled 3000 participants, of whom 360 (45%) were women, were randomly assigned to receive either vaccine or placebo. 445 participants (56%) had adenovirus serotype 5 (Ad5) titres greater than 200, and 129 men (29%) were circumcised. 34 MITT participants in the vaccine group were diagnosed with HIV-1 (incidence rate 4·54 per 100 person-years) and 28 in the placebo group (3·70 per 100 person-years). There was no evidence of vaccine efficacy; the hazard ratio adjusted for sex was 1·25 (95% CI 0·76-2·05). Vaccine efficacy did not differ by Ad5 titre, sex, age, herpes simplex virus type 2 status, or circumcision. The geometric mean viral-load setpoint was 20,483 copies per mL (n=33) in the vaccine group and 34,032 copies per mL (n=28) in the placebo group (p=0·39). The vaccine elicited interferon-γ-secreting T cells that recognised both clade B (89%) and C (77%) antigens. INTERPRETATION The MRKAd5 HIV-1 vaccine did not prevent HIV-1 infection or lower viral-load setpoint; however, stopping our trial early probably compromised our ability to draw conclusions. The high incidence rates noted in South Africa highlight the crucial need for intensified efforts to develop an efficacious vaccine. FUNDING The US National Institute of Allergy and Infectious Disease and Merck and Co Inc.

Primary Tubal Infertility in Relation to the Use of an Intrauterine Device

Women who use an intrauterine device (IUD) are at increased risk of acute pelvic inflammatory disease, but the relation of the IUD to subsequent infertility is not established. We interviewed 159 nulligravid women with tubal infertility to determine their prior use of an IUD. Their responses were compared with those of a matched group who conceived their first child at the time the infertile women started trying to become pregnant. The risk of primary tubal infertility in women who had ever used an IUD was 2.6 times that in women who had never used one (95 per cent confidence interval, 1.3 to 5.2). The observed difference between cases and controls was not uniform for different types of IUD. The relative risk associated with use of a Dalkon Shield was 6.8 (1.8 to 25.2), and that associated with use of either a Lippes Loop or Saf-T Coil IUD was 3.2 (0.9 to 12.0). The smallest elevation in risk was found among users of copper-containing IUDs (relative risk, 1.9 [0.9 to 4.0] for all women who had ever used a copper-containing IUD). The relative risk for women who used only a copper-containing IUD was 1.3 (0.6 to 3.0). We conclude that use of the Dalkon Shield (and possibly of plastic IUDs other than those that contain copper) can lead to infertility in nulligravid women.

Determinants of enrollment in a preventive HIV vaccine trial: hypothetical versus actual willingness and barriers to participation.

Objective:To compare hypothetical and actual willingness to enroll in a preventive HIV vaccine trial and identify factors affecting enrollment. Methods:Participants previously enrolled in an HIV vaccine preparedness study (VPS) in 8 US cities were invited to be screened for a phase 2 HIV vaccine trial. Demographic and risk characteristics of those enrolling, ineligible, and refusing enrollment were compared using the χ2 or Fisher exact test. Multivariable logistic models were used to identify independent predictors of refusal. Results:Of 2531 high-risk HIV-uninfected former VPS participants contacted for the vaccine trial, 13% enrolled, 34% were ineligible, and 53% refused enrollment. Only 20% of those stating hypothetical willingness during the VPS actually enrolled in this vaccine trial. In multivariate analysis, refusal was higher among African Americans and lower in persons >40 years of age, those attending college, and those with ≥5 partners in the prior 6 months. All racial ethnic groups cited concerns about vaccine-induced seropositivity; African Americans also cited mistrust of government and safety concerns as barriers to enrollment. Conclusions:Steps can be taken to minimize potential social harms and to mobilize diverse communities to enroll in trials. Statements of hypothetical willingness to participate in future trials may overestimate true enrollment.

Safety and Comparative Immunogenicity of an HIV-1 DNA Vaccine in Combination with Plasmid Interleukin 12 and Impact of Intramuscular Electroporation for Delivery

BACKGROUND DNA vaccines have been very poorly immunogenic in humans but have been an effective priming modality in prime-boost regimens. Methods to increase the immunogenicity of DNA vaccines are needed. METHODS HIV Vaccine Trials Network (HVTN) studies 070 and 080 were multicenter, randomized, clinical trials. The human immunodeficiency virus type 1 (HIV-1) PENNVAX®-B DNA vaccine (PV) is a mixture of 3 expression plasmids encoding HIV-1 Clade B Env, Gag, and Pol. The interleukin 12 (IL-12) DNA plasmid expresses human IL-12 proteins p35 and p40. Study subjects were healthy HIV-1-uninfected adults 18-50 years old. Four intramuscular vaccinations were given in HVTN 070, and 3 intramuscular vaccinations were followed by electroporation in HVTN 080. Cellular immune responses were measured by intracellular cytokine staining after stimulation with HIV-1 peptide pools. RESULTS Vaccination was safe and well tolerated. Administration of PV plus IL-12 with electroporation had a significant dose-sparing effect and provided immunogenicity superior to that observed in the trial without electroporation, despite fewer vaccinations. A total of 71.4% of individuals vaccinated with PV plus IL-12 plasmid with electroporation developed either a CD4(+) or CD8(+) T-cell response after the second vaccination, and 88.9% developed a CD4(+) or CD8(+) T-cell response after the third vaccination. CONCLUSIONS Use of electroporation after PV administration provided superior immunogenicity than delivery without electroporation. This study illustrates the power of combined DNA approaches to generate impressive immune responses in humans.

Safety and Immunogenicity of an HIV-1 Gag DNA Vaccine with or without IL-12 and/or IL-15 Plasmid Cytokine Adjuvant in Healthy, HIV-1 Uninfected Adults

Background DNA vaccines are a promising approach to vaccination since they circumvent the problem of vector-induced immunity. DNA plasmid cytokine adjuvants have been shown to augment immune responses in small animals and in macaques. Methodology/Principal Findings We performed two first in human HIV vaccine trials in the US, Brazil and Thailand of an RNA-optimized truncated HIV-1 gag gene (p37) DNA derived from strain HXB2 administered either alone or in combination with dose-escalation of IL-12 or IL-15 plasmid cytokine adjuvants. Vaccinations with both the HIV immunogen and cytokine adjuvant were generally well-tolerated and no significant vaccine-related adverse events were identified. A small number of subjects developed asymptomatic low titer antibodies to IL-12 or IL-15. Cellular immunogenicity following 3 and 4 vaccinations was poor, with response rates to gag of 4.9%/8.7% among vaccinees receiving gag DNA alone, 0%/11.5% among those receiving gag DNA+IL-15, and no responders among those receiving DNA+high dose (1500 ug) IL-12 DNA. However, after three doses, 44.4% (4/9) of vaccinees receiving gag DNA and intermediate dose (500 ug) of IL-12 DNA demonstrated a detectable cellular immune response. Conclusions/Significance This combination of HIV gag DNA with plasmid cytokine adjuvants was well tolerated. There were minimal responses to HIV gag DNA alone, and no apparent augmentation with either IL-12 or IL-15 plasmid cytokine adjuvants. Despite the promise of DNA vaccines, newer formulations or methods of delivery will be required to increase their immunogenicity. Trial Registration Clinicaltrials.gov NCT00115960 NCT00111605

Recombinant adenovirus type 5 HIV gag/pol/nef vaccine in South Africa: unblinded, long-term follow-up of the phase 2b HVTN 503/Phambili study

Background The Phambili study, conducted in South Africa amongst a predominantly heterosexual population, evaluated the efficacy of the MRK Ad5 gag/pol/nef subtype B HIV-1 preventive vaccine. Enrollment and vaccinations were stopped, participants unblinded, and follow-up extended when the Step study evaluating the same vaccine in the Americas, Caribbean and Australia was unblinded for non-efficacy with more HIV infections amongst vaccinee than placebo recipients [ZM1]. Extensive analyses over the complete follow-up period, most of which was unblinded, are reported.BACKGROUND The HVTN 503/Phambili study, which assessed the efficacy of the Merck Ad5 gag/pol/nef subtype B HIV-1 preventive vaccine in South Africa, was stopped when futility criteria in the Step study (assessing the same vaccine in the Americas, Caribbean, and Australia) were met. Here we report long-term follow-up data. METHODS HVTN 503/Phambili was a double-blind, placebo-controlled, randomised trial that recruited HIV-1 uninfected, sexually active adults aged 18-35 years from five sites in South Africa. Eligible participants were randomly assigned (1:1) by computer-generated random numbers to either vaccine or placebo, stratified by site and sex. Cox proportional hazards models were used to estimate HIV-1 infection in the modified intention-to-treat cohort, all of whom were unmasked early in follow-up. The trial is registered with ClinicalTrials.gov, number NCT00413725 and the South African National Health Research Database, number DOH-27-0207-1539. FINDINGS Between Jan 24, 2007, and Sept 19, 2007, 801 participants (26·7%) of a planned 3000 were randomly assigned (400 to vaccine, 401 to placebo); 216 (27%) received only one injection, 529 (66%) received only two injections, and 56 (7%) received three injections. At a median follow-up of 42 months (IQR 31-42), 63 vaccine recipients (16%) had HIV-1 infection compared with 37 placebo recipients (9%; adjusted HR 1·70, 95% CI 1·13-2·55; p=0·01). Risk for HIV-1 infection did not differ according to the number of vaccinations received, sex, circumcision, or adenovirus type 5 (Ad5) serostatus. Differences in risk behaviour at baseline or during the study, or annualised dropout rate (7·7% [95% CI 6·2-9·5] for vaccine recipients vs 8·8% [7·1-10·7] for placebo recipients; p=0·40) are unlikely explanations for the increased rate of HIV-1 infections seen in vaccine recipients. INTERPRETATION The increased risk of HIV-1 acquisition in vaccine recipients, irrespective of number of doses received, warrants further investigation to understand the biological mechanism. We caution against further use of the Ad5 vector for HIV vaccines. FUNDING National Institute of Allergy and Infectious Diseases, Merck, and South African Medical Research Council.

Demographic factors that influence the neutralizing antibody response in recipients of recombinant HIV-1 gp120 vaccines.

We compared neutralizing antibody responses in human immunodeficiency virus (HIV) type 1 gp120 vaccine recipients by age, sex, and race. Four phase 1 or 2 trials involving 505 vaccinated subjects were analyzed. Age and sex had no detectable effect on neutralizing antibody responses. However, race influenced the response to one vaccine, MN gp120, in alum. Four inoculations with this vaccine generated higher serum titers of neutralizing antibodies in African Americans than in whites. Despite potent neutralization of T cell line-adapted HIV-1, serum from these African Americans failed to neutralize primary HIV-1 isolates. Neutralizing antibody responses did not differ between races when SF2 gp120 in MF-59 was administered either alone or with recombinant canarypox vCP205; they also did not differ when vCP1452 was administered either alone or with AIDSVAX B/B in alum. These data indicate that race may affect the neutralizing antibody response to some gp120 immunogens. To fully evaluate immunogenicity, clinical trials of candidate vaccines should enroll diverse populations of subjects.

Safety and Immunogenicity of a CTL Multiepitope Peptide Vaccine for HIV with or without GM-CSF in a Phase I Trial

There is an urgent need for a vaccine capable of preventing HIV infection or the development of HIV-related disease. A number of approaches designed to stimulate HIV-specific CD8+ cytotoxic T cell responses together with helper responses are presently under evaluation. In this phase 1, multi-center, placebo-controlled trial, we tested the ability of a novel multiepitope peptide vaccine to elicit HIV-specific immunity. To enhance the immunogenicity of the peptide vaccine, half of the vaccine recipients received recombinant granulocyte-macrophage colony stimulating factor (GM-CSF) protein as a coadjuvant. The vaccine was safe; tolerability was moderate, with a number of adverse events related to local injection site reactogenicity. Anti-GM-CSF antibody responses developed in the majority of GM-CSF recipients but were not associated with adverse hematologic events. The vaccine was only minimally immunogenic. Six of 80 volunteers who received vaccine developed HIV-specific responses as measured by interferon-gamma ELISPOT assay, and measurable responses were transient. This study failed to demonstrate that GM-CSF can substantially improve the overall weak immunogenicity of a multiepitope peptide-based HIV vaccine.

A phase I trial of preventive HIV vaccination with heterologous poxviral-vectors containing matching HIV-1 inserts in healthy HIV-uninfected subjects

We evaluated replication-defective poxvirus vectors (modified vaccinia Ankara [MVA] and fowlpox [FPV]) in a homologous and heterologous vector prime-boost vaccination regimen containing matching HIV inserts (MVA-HIV and FPV-HIV) given at months 0, 1, 3, 5 and 7 in 150 healthy HIV-negative vaccinia-naïve participants. FPV-HIV alone was poorly immunogenic, while the high dose (10(9)pfu/2 ml) of MVA-HIV alone elicited maximal responses after two injections: CD4+ and CD8+ T-cell responses in 26/55 (47.3%) and 5/60 (8.3%) of participants, respectively, and IFN-γ ELISpot responses in 28/62 (45.2%). The infrequent CD8+ T-cell responses following MVA-HIV priming were boosted only by the heterologous (FPV-HIV) construct in 14/27 (51.9%) of participants post 4th vaccination. Alternatively, HIV envelope-specific binding antibodies were demonstrated in approximately two-thirds of recipients of the homologous boosting regimen, but in less than 20% of subjects after the heterologous vector boost. Thus, a heterologous poxvirus vector prime-boost regimen can induce HIV-specific CD8+ T-cell and CD4+ T-cell responses, which may be an important feature of an optimal regimen for preventive HIV vaccination.

Vaccine-Induced HIV Seropositivity/Reactivity in Noninfected HIV Vaccine Recipients

CONTEXT Induction of protective anti-human immunodeficiency virus (HIV) immune responses is the goal of an HIV vaccine. However, this may cause a reactive result in routine HIV testing in the absence of HIV infection. OBJECTIVE To evaluate the frequency of vaccine-induced seropositivity/reactivity (VISP) in HIV vaccine trial participants. DESIGN, SETTING, AND PARTICIPANTS Three common US Food and Drug Administration-approved enzyme immunoassay (EIA) HIV antibody kits were used to determine VISP, and a routine diagnostic HIV algorithm was used to evaluate VISP frequency in healthy, HIV-seronegative adults who completed phase 1 (n = 25) and phase 2a (n = 2) vaccine trials conducted from 2000-2010 in the United States, South America, Thailand, and Africa. MAIN OUTCOME MEASURE Vaccine-induced seropositivity/reactivity, defined as reactive on 1 or more EIA tests and either Western blot-negative or Western blot-indeterminate/atypical positive (profile consistent with vaccine product) and HIV-1-negative by nucleic acid testing. RESULTS Among 2176 participants free of HIV infection who received a vaccine product, 908 (41.7%; 95% confidence interval [CI], 39.6%-43.8%) had VISP, but the occurrence of VISP varied substantially across different HIV vaccine product types: 399 of 460 (86.7%; 95% CI, 83.3%-89.7%) adenovirus 5 product recipients, 295 of 552 (53.4%; 95% CI, 49.2%-57.7%) recipients of poxvirus alone or as a boost, and 35 of 555 (6.3%; 95% CI, 4.4%-8.7%) of DNA-alone product recipients developed VISP. Overall, the highest proportion of VISP (891/2176 tested [40.9%]) occurred with the HIV 1/2 (rDNA) EIA kit compared with the rLAV EIA (150/700 tested [21.4%]), HIV-1 Plus O Microelisa System (193/1309 tested [14.7%]), and HIV 1/2 Peptide and HIV 1/2 Plus O (189/2150 tested [8.8%]) kits. Only 17 of the 908 participants (1.9%) with VISP tested nonreactive using the HIV 1/2 (rDNA) kit. All recipients of a glycoprotein 140 vaccine (n = 70) had VISP, with 94.3% testing reactive with all 3 EIA kits tested. Among 901 participants with VISP and a Western blot result, 92 (10.2%) had a positive Western blot result (displaying an atypical pattern consistent with vaccine product), and 592 (65.7%) had an indeterminate result. Only 8 participants with VISP received a vaccine not containing an envelope insert. CONCLUSIONS The induction of VISP in HIV vaccine recipients is common, especially with vaccines containing both the HIV-1 envelope and group-specific core antigen gene proteins. Development and detection of VISP appear to be associated with the immunogenicity of the vaccine and the EIA assay used.