Kathryn Mngadi

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.

Adverse events with isoniazid preventive therapy: experience from a large trial.

Objectives:We describe isoniazid-related adverse events in Thibela TB, a cluster-randomized study of community-wide isoniazid preventive therapy (IPT) among gold miners in South Africa, where HIV prevalence is estimated at 30%. Methods:Consenting employees were screened prior to IPT for active tuberculosis and increased risk of isoniazid toxicity using a questionnaire and chest radiograph. Study-defined IPT-related adverse events were sought at each study visit: liver function tests were only performed if clinically indicated. In a substudy, we questioned consecutive participants at baseline and months 1, 3, and 6 concerning minor IPT-related adverse events. Results:Among 24 221 participants (95.2% men, median age 40 years), 130 individuals had 132 study-defined adverse events (0.54%); 61 (0.25%) possible hypersensitivity rash, 50 (0.21%) peripheral neuropathy, 17 (0.07%) clinical hepatotoxicity, and four (0.02%) convulsions. Four events (two hepatotoxicity, one fatal, and two convulsions) fulfilled criteria for seriousness. Clinical hepatotoxicity was associated with consumption of alcohol [0.11 vs. 0.03% if no alcohol consumed, odds ratio 3.9 (95% confidence interval 1.2–12.1)], but not with sex, age, weight, or concurrent antiretroviral therapy. In the substudy, 324 of 498 (65.1%) participants reported better health since starting IPT; 180 of 324 (55.6%) reported that this was because of increased appetite. The frequency of specific minor symptoms was low among those taking IPT, and all symptoms were reported less often than at baseline. Conclusion:The risk of adverse events, particularly hepatotoxicity, was very low in this population. Our data suggest that clinical criteria can safely be used for screening prior to and monitoring during IPT.

'Team up against TB': promoting involvement in Thibela TB, a trial of community-wide tuberculosis preventive therapy.

Objective:To describe a programme of community education and mobilization to promote uptake in a cluster-randomized trial of tuberculosis preventive therapy offered to all members of intervention clusters. Setting and participants:Gold mines in South Africa, where tuberculosis incidence is extremely high, despite conventional control measures. All employees in intervention clusters (mine shaft and associated hostel) were invited to enrol. Main outcome measure:Cumulative enrolment in the study in intervention clusters. Results:Key steps in communicating information relevant to the study included extensive consultation with key stakeholders; working with a communication company to develop a project ‘brand’; developing a communication strategy tailored to each intervention site; and involving actors from a popular television comedy series to help inform communities about the study. One-to-one communications used peer educators along with study staff, and participant advisory groups facilitated two-way communication between study staff and participants. By contrast, treatment ‘buddies’ and text messaging to promote adherence proved less successful. Mean cumulative enrolment in the first four intervention clusters was 61.9%, increasing to 83.0% in the final four clusters. Conclusion:A tailored communication strategy can facilitate a high level of enrolment in a community health intervention.

Continued Follow-Up of Phambili Phase 2b Randomized HIV-1 Vaccine Trial Participants Supports Increased HIV-1 Acquisition among Vaccinated Men.

Background The Phase 2b double-blinded, randomized Phambili/HVTN 503 trial evaluated safety and efficacy of the MRK Ad5 gag/pol/nef subtype B HIV-1 preventive vaccine vs placebo in sexually active HIV-1 seronegative participants in South Africa. Enrollment and vaccinations stopped and participants were unblinded but continued follow-up when the Step study evaluating the same vaccine in the Americas, Caribbean, and Australia was unblinded for non-efficacy. Final Phambili analyses found more HIV-1 infections amongst vaccine than placebo recipients, impelling the HVTN 503-S recall study. Methods HVTN 503-S sought to enroll all 695 HIV-1 uninfected Phambili participants, provide HIV testing, risk reduction counseling, physical examination, risk behavior assessment and treatment assignment recall. After adding HVTN 503-S data, HIV-1 infection hazard ratios (HR vaccine vs. placebo) were estimated by Cox models. Results Of the 695 eligible, 465 (67%) enrolled with 230 from the vaccine group and 235 from the placebo group. 38% of the 184 Phambili dropouts were enrolled. Enrollment did not differ by treatment group, gender, or baseline HSV-2. With the additional 1286 person years of 503-S follow-up, the estimated HR over Phambili and HVTN 503-S follow-up was 1.52 (95% CI 1.08–2.15, p = 0.02, 82 vaccine/54 placebo infections). The HR was significant for men (HR = 2.75, 95% CI 1.49, 5.06, p = 0.001) but not for women (HR = 1.12, 95% CI 0.73, 1.72, p = 0.62). Conclusion The additional follow-up from HVTN 503-S supported the Phambili finding of increased HIV-1 acquisition among vaccinated men and strengthened the evidence of lack of vaccine effect among women. Trial Registration clinicaltrials.gov NCT00413725 SA National Health Research Database DOH-27-0207-1539

Subtype C ALVAC-HIV and bivalent subtype C gp120/MF59 HIV-1 vaccine in low-risk, HIV-uninfected, South African adults: a phase 1/2 trial

Summary Background Modest efficacy was reported for the HIV vaccine tested in the RV144 trial, which comprised a canarypox vector (ALVAC) and envelope (env) glycoprotein (gp120). These vaccine components were adapted to express HIV-1 antigens from strains circulating in South Africa, and the adjuvant was changed to increase immunogenicity. Furthermore, 12-month immunisation was added to improve durability. In the HIV Vaccine Trials Network (HVTN) 100 trial, we aimed to assess this new regionally adapted regimen for advancement to efficacy testing. Methods HVTN 100 is a phase 1/2, randomised controlled, double-blind trial at six community research sites in South Africa. We randomly allocated adults (aged 18–40 years) without HIV infection and at low risk of HIV infection to either the vaccine regimen (intramuscular injection of ALVAC-HIV vector [vCP2438] at 0, 1, 3, 6, and 12 months plus bivalent subtype C gp120 and MF59 adjuvant at 3, 6, and 12 months) or placebo, in a 5:1 ratio. Randomisation was done by computer-generated list. Participants, investigators, and those assessing outcomes were masked to random assignments. Primary outcomes included safety and immune responses associated with correlates of HIV risk in RV144, 2 weeks after vaccination at 6 months (month 6·5). We compared per-protocol participants (ie, those who completed the first four vaccinations and provided samples at month 6·5) from HVTN 100 with stored RV144 samples assayed contemporaneously. This trial is registered with the South African National Clinical Trials Registry (DOH-27-0215-4796) and ClinicalTrials.gov (NCT02404311). Findings Between Feb 9, 2015, and May 26, 2015, 252 participants were enrolled, of whom 210 were assigned vaccine and 42 placebo. 222 participants were included in the per-protocol analysis (185 vaccine and 37 placebo). 185 (100%) vaccine recipients developed IgG binding antibodies to all three vaccine-matched gp120 antigens with significantly higher titres (3·6–8·8 fold; all p<0·0001) than the corresponding vaccine-matched responses of RV144. The CD4+ T-cell response to the ZM96.C env protein in HVTN 100 was 56·4% (n=102 responders), compared with a response of 41·4% (n=79 responders) to 92TH023.AE in RV144 (p=0·0050). The IgG response to the 1086.C variable loops 1 and 2 (V1V2) env antigen in HVTN 100 was 70·5% (95% CI 63·5–76·6; n=129 responders), lower than the response to V1V2 in RV144 (99·0%, 95% CI 96·4–99·7; n=199 responders). Interpretation Although the IgG response to the HVTN 100 vaccine was lower than that reported in RV144, it exceeded the predicted 63% threshold needed for 50% vaccine efficacy using a V1V2 correlate of protection model. Thus, the subtype C HIV vaccine regimen qualified for phase 2b/3 efficacy testing, a critical next step of vaccine development. Funding US National Institute of Allergy and Infectious Diseases (NIAID), and Bill & Melinda Gates Foundation.

Undue inducement : a case study in CAPRISA 008.

Participant safety and data integrity, critical in trials of new investigational drugs, are achieved through honest participant report and precision in the conduct of procedures. HIV prevention post-trial access studies in middle-income countries potentially offer participants many benefits including access to proven efficacious but unlicensed technologies, ancillary care that often exceeds local standards-of-care, financial reimbursement for participation and possibly unintended benefits if participants choose to share or sell investigational drugs. This case study examines the possibility that this combination of benefits may constitute an undue inducement for some participants in middle-income countries, where economic challenges are prevalent. A case study is presented of a single participant in a cohort of 382 participants who used concealment, fabrication and deception to ensure eligibility for a post-trial access study of an unlicensed HIV prevention technology at potential risk to her health and that of her fetus. A root cause analysis revealed her desire to access HIV prevention during an unplanned pregnancy with a partner whose faithfulness was in question. Researchers should consider implementation of systems to efficiently identify similar cases without inconveniencing the majority of participants Trial registration number NCT01691768.

Challenges with participant reimbursement: experiences from a post-trial access study

Reimbursement of trial participants remains a frequently debated issue, with specific guidance lacking. Trials combining post-trial access and implementation science may necessitate new strategies and models. CAPRISA 008, a post-trial access study testing the feasibility of using family planning services to rollout a prelicensure HIV prevention intervention, tried to balance the real-life scenario of no reimbursement for attendance at public sector clinics with that of a trial including some visits that focused on research procedures and others that focused on standard of care procedures. A reduced reimbursement was offered for ‘standard of care’ visits, meant primarily to cover transport costs to and from the clinic only. This impacted negatively on accrual, retention and participant morale, primarily due to the protracted delay in regulatory approval, during which time, the costs of living, including travel costs had increased. Relevant guidelines were reviewed and institutional policy was updated to incorporate the South African National Health Research Ethics Committee guidelines on reimbursement (taking into account participant time, travel and inconvenience). The reimbursement amount for ‘standard of care’ visits was increased accordingly. The question remains whether a trial that combines post-trial access with implementation science, with clear benefits for the participants and the provision of above standard medical care, should have reimbursement rates that approach those of a proof-of-concept trial, for ‘standard of care’ visits.

Rolling Out of Tenofovir Gel in Family Planning Clinics: The CAPRISA 008 Implementation Trial

Product effectiveness in “real-world” settings in healthcare services may differ markedly from product efficacy observed in clinical trials. Limited data exists, beyond clinical trial settings, to guide the introduction of pre-exposure prophylaxis (PrEP) in healthcare services. Since a large number of young women utilise existing family planning (FP) services at primary healthcare clinics, these facilities present one of the best opportunities for introducing PrEP as a new HIV prevention technology for women as part of their well-established sexual and reproductive health services. CAPRISA 008 was a two-arm, open-label, randomised controlled, non-inferiority implementation trial, which provided participants from CAPRISA 004 with post-trial access to tenofovir gel while generating evidence that could be used for future implementation of topical PrEP (tenofovir gel) in women. Women were randomly assigned to receive tenofovir gel at clinical trial clinics or at FP clinics utilising Quality Improvement (QI) methodology to promote reliable service delivery. Higher adherence in FP clinics met the pre-defined non-inferiority criteria, demonstrating that integration of topical PrEP into FP services for African women is feasible, acceptable and achieves adherence equivalent to a clinical trial setting, providing evidence for PrEP scale-up using this strategy for this challenging high-priority population.

HIV Vaccine and Passive Immunity Trials

Despite a trend of declining HIV incidence rates, up to 2 million people continue to become newly infected with HIV every year. Antiretroviral-based interventions offer optimism to achieve epidemic control, but a vaccine is needed to eliminate HIV. The path to a vaccine remains elusive because of unique features of the virus, including its ability to attack vital parts of the immune system, its high mutation rate and a little understanding on what protects a human, due to a lack of examples of a natural cure. This chapter reviews CAPRISA’s contribution to HIV vaccine research over the past decade focusing on CAPRISA’s involvement in the National Institute of Health-funded HIV Vaccine Trial Network (HVTN) Phambili trial, the first phase IIb HIV vaccine study conducted in sub-Saharan Africa, and lessons learnt during its premature closure. We then discuss ongoing Vanguard vaccine studies in preparation for the next generation of efficacy trials that CAPRISA is participating in sponsored by HVTN and Janssen Pharmaceuticals. We conclude with a synopsis of CAPRISA’s contributions to passive immunisation studies for HIV prevention.

The phase 2b HVTN 503/Phambili study test-of-concept HIV vaccine study, investigating a recombinant adenovirus type 5 HIV gag/pol/nef vaccine in South Africa: unblinded, long-term follow-up

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.