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Keywords:

  • Biological;
  • correlates;
  • HIV ;
  • protection;
  • specimens;
  • trials

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Lessons learnt from prevention trials
  5. CAPRISA 004: a phase IIB trial that assessed the safety and effectiveness of 1% tenofovir microbicide gel
  6. iPrEx: a phase III trial that assessed the safety and efficacy of TDF-FTC oral PrEP
  7. RV144: a phase III trial to examine safety and efficacy of HIV vaccine ALVAC and AIDSVAX B/E
  8. Discussion
  9. Conclusion
  10. Future implications
  11. Acknowledgements
  12. References

Problem

Inadequate, irrelevant, or inappropriate timing of biological specimen collection during clinical trials is a cause for delay in understanding and explaining correlates of protection and/or effectiveness, particularly at the portal of entry in the context of sexual HIV transmission and its prevention.

Methods

We present examples of HIV prevention trials to illustrate the impact of preplanned versus unplanned laboratory science program on the interpretation of trial results and advancement of the field.

Results

Of the five completed pre-exposure prophylaxis trials, only two announced main outcome results simultaneously with data on correlates of drug-related effectiveness. In four of the vaccine trials completed, the only one that showed a protective effect presented data on protection correlates significantly later.

Conclusion

Clinical trials must preplan collaborative immunophysiological research and prioritize biological specimen collection and storage for enhancement of research on correlates of protection. Similarly appropriate specimens should be prioritized for pathogenesis research.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Lessons learnt from prevention trials
  5. CAPRISA 004: a phase IIB trial that assessed the safety and effectiveness of 1% tenofovir microbicide gel
  6. iPrEx: a phase III trial that assessed the safety and efficacy of TDF-FTC oral PrEP
  7. RV144: a phase III trial to examine safety and efficacy of HIV vaccine ALVAC and AIDSVAX B/E
  8. Discussion
  9. Conclusion
  10. Future implications
  11. Acknowledgements
  12. References

An estimated 34 million people worldwide were living with human immunodeficiency virus (HIV) infection at the end of 2010. In Africa, 59% of those infected were women 15 years and older.[1] Sexual transmission accounts for over 60% of new HIV infections.[2] 2.7 million people became newly infected between 2007 and 2010, while only 47% of HIV-infected patients needing anti-retroviral therapy had access to it.[3] These alarming statistics highlight an urgent need for effective HIV prevention strategies.

Over the last thirty years, developing effective biomedical strategies such as vaccines, male circumcision, treatment for sexually transmitted infections, oral pre-exposure prophylaxis (PrEP), and topical PrEP (microbicides) has been central to the broader HIV prevention research agenda. However, most of these prevention strategies have not been translated into clinical practice, primarily because late phase clinical trials showed either unpredictable and perplexing results or an effectiveness level less than desired.[4, 5] For instance, only four of seven of anti-retroviral-based PrEP trials[6-12] and one of four vaccine trials[13-17] demonstrated a protective effect. Studies such as the Vaginal and Oral Interventions to Control the Epidemic (VOICE) Microbicide Trial Network (MTN)-003 and the Preexposure Prophylaxis Trial for HIV Prevention among African Women (FEM-PrEP) trials, in which the efficacy of oral tenofovir (tenofovir disoproxil fumarate-TDF), vaginal tenofovir (TNF), and TDF/emtricitabine (TDF-FTC) were assessed, respectively, were stopped for futility[8, 10] while the same drugs studied in the Centre for the AIDS Program of Research in South Africa (CAPRISA) 004, Preexposure Prophylaxis Initiative (iPrEx), TDF–FTC PrEP for Heterosexual HIV Transmission in Botswana (TDF2), and the Partners Pre-exposure Prophylaxis (Partners PrEP) showed a significantly protective effect.[6-9] Likewise, in the vaccine field, trials of the AIDSVAX B/E gp120 vaccine (VAX 004 and VAX003)[13, 14] were ineffective while the Thai HIV vaccine trial (RV144),[17] which used AIDSVAX B/E gp120 combined with the CD4+ T cell–stimulating ALVAC canarypox vaccine, showed a protective result, albeit statistically significant in only one of three analyses.

Inherent in these paradoxical results is the realization that it is no longer adequate to follow the empirical unidirectional process of drug development, which proceeds from pre-clinical research to clinical trials before reaching licensure and registration stages. Instead, laboratory science ought to be a fundamental component of clinical trials. Moreover, these results raise critical questions such as how and when we should apply laboratory sciences to allow better understanding of trial outcomes and to inform the design of future trials. It is also important to consider how much information to gather during clinical trials to best translate laboratory findings into clinical trial outcomes. Therefore, in this review, we aim to highlight the significance of collecting timely, appropriate, and relevant biological specimens, particularly from the genital tract, in the context of sexually transmitted HIV and its prevention. We also provide a guide to future strategies that will enhance the conduct of clinical trials alongside laboratory science programs.

Lessons learnt from prevention trials

  1. Top of page
  2. Abstract
  3. Introduction
  4. Lessons learnt from prevention trials
  5. CAPRISA 004: a phase IIB trial that assessed the safety and effectiveness of 1% tenofovir microbicide gel
  6. iPrEx: a phase III trial that assessed the safety and efficacy of TDF-FTC oral PrEP
  7. RV144: a phase III trial to examine safety and efficacy of HIV vaccine ALVAC and AIDSVAX B/E
  8. Discussion
  9. Conclusion
  10. Future implications
  11. Acknowledgements
  12. References

Whether persistent HIV infection is established or aborted after viral exposure depends on the balance of the interaction between virus-specific properties, host defenses, and host genetics. The interaction between these factors also predicts subsequent clinical disease progression in the acute and chronic stages of infection. However, in the context of clinical trials, the major focus is on the presence of the drug in host cells at the time of primary viral entry, tilting the balance toward the study of host defenses, and their interplay with founder virus genetics and pharmacokinetics and pharmacodynamics. Thus, clinical trials provide an opportunity to study both the natural correlates of protection and the impact of pre-exposure prophylaxis in humans on three important aspects of HIV infection: innate and adaptive immune responses, viral dynamics, and pharmacokinetics of the drug intervention. Consequently, it is essential that trial design takes into account the need to identify correlates of protection from the outset. Evidently, trials such as the CAPRISA 004 and the iPrEx that adopted this approach did not only answer the essential question of effectiveness but were also able to gather data on correlates of protection.[6, 9] Conversely, many years after announcing the efficacy data, researchers are still investigating the mechanisms of futility/protection in the MRKAd5 HIV-1 vaccine (HVTN 502/Merck 023-STEP) and the RV144 trials.[18, 19] Some of the major differences between these trials were the availability of relevant and adequate biological specimens and a plan within the parent protocol to address these questions. We therefore make a case for trials to be designed such that the scientific program into the understanding of correlates of protection is incorporated into the main objectives of the trial, and appropriate biological specimens are collected and stored.

CAPRISA 004: a phase IIB trial that assessed the safety and effectiveness of 1% tenofovir microbicide gel

  1. Top of page
  2. Abstract
  3. Introduction
  4. Lessons learnt from prevention trials
  5. CAPRISA 004: a phase IIB trial that assessed the safety and effectiveness of 1% tenofovir microbicide gel
  6. iPrEx: a phase III trial that assessed the safety and efficacy of TDF-FTC oral PrEP
  7. RV144: a phase III trial to examine safety and efficacy of HIV vaccine ALVAC and AIDSVAX B/E
  8. Discussion
  9. Conclusion
  10. Future implications
  11. Acknowledgements
  12. References

The CAPRISA 004 trial compared TNF and placebo gels in 889 sexually active, HIV-uninfected 18- to 40-year-old women in urban and rural KwaZulu-Natal, South Africa.[9] Participants were requested to insert the first dose of gel up to 12 hr before sex and the second dose as soon as possible within 12 hr after intercourse. Study visits occurred monthly, when HIV testing was also performed. Blood and genital tract specimens were collected and stored at months 3, 12, 24, and seroconversion visits. Endpoint status of HIV infection was determined over a 2- to 3-week period, the same period used to recruit participants with HIV breakthrough infections into the seroconverter cohort. This immediate transition facilitated collection of appropriately timed specimens for studies on correlates of protection and effectiveness.[20-22] During transitioning, further blood and genital specimens including undiluted cervicovaginal fluid (CVF) were collected and stored for the estimation of TNF drug levels. These were later analyzed with a validated ultra-performance liquid chromatograph-mass spectrometry (HP-LC/MS) method.[23]

The results of this study were announced at a special session at the XVIII International AIDS Conference held in Vienna in 2010 and showed that tenofovir gel reduced HIV acquisition by an estimated 39%, increasing to 54% in women with high gel adherence.[9, 24] The latter were defined as women whose returned applicator counts indicated that they followed the prescribed regimen of two doses of TNF gel per sex act on at least 80% occasions. Furthermore, the results based on CVF specimens showed a strong correlation between drug concentration at the exposure site and the level of adherence.[25] As per the protocol specifications, samples were collected during the first visit post-infection from 34 of the 38 HIV seroconverters and from a randomly selected visit from 301 women assigned to TNF who remained uninfected during the trial. These samples were analyzed to calculate the concentration of TNF in the different genital tract sub-compartments. The HIV incidence rate in women with TNF concentrations of ≤1000 ng/mL was close to that in the placebo group [7.8 versus 9.1 per 100 women-years; incidence rate ratio (IRR) = 0.86, 95% confidence interval (CI) 0.54–1.35, = 0.51]. However, the HIV incidence rate in women with TNF concentrations greater than 1000 ng/mL was significantly lower than that in the placebo group (2.4 versus 9.1 per 100 person-years; IRR = 0.26, 95% CI 0.05–0.80, = 0.01). Consequently, drug concentration altered the level of protection in the genital tract.[23]

These findings therefore highlight the need to collect biological specimens that are timed correctly (closest to the time of infection), collected from the relevant site (female genital tract, the portal of entry) using a validated specimen collection device (vaginal aspirator), and processed using an already validated method (LC/MS) for the purposes of assessing the correlation between drug levels and effectiveness and delineating mechanisms behind protection. Furthermore, timely availability of these data emphasizes the significance of preplanning studies on correlates of protection.

iPrEx: a phase III trial that assessed the safety and efficacy of TDF-FTC oral PrEP

  1. Top of page
  2. Abstract
  3. Introduction
  4. Lessons learnt from prevention trials
  5. CAPRISA 004: a phase IIB trial that assessed the safety and effectiveness of 1% tenofovir microbicide gel
  6. iPrEx: a phase III trial that assessed the safety and efficacy of TDF-FTC oral PrEP
  7. RV144: a phase III trial to examine safety and efficacy of HIV vaccine ALVAC and AIDSVAX B/E
  8. Discussion
  9. Conclusion
  10. Future implications
  11. Acknowledgements
  12. References

The iPrEx trial, the results of which were simultaneously published and announced in 2010, investigated the link between oral PrEP and the risk of HIV infection following sexual exposure.[6] This trial randomly assigned 2499 HIV-seronegative men who have sex with men (MSM) or transgender women who have sex with men to receive TDF-FTC or placebo orally. Study visits were scheduled every 4 weeks after enrollment, and blood was collected and analyzed at weeks 4, 8, 12, 16, and 24 and every 12 weeks thereafter. A pre-specified subgroup analysis was performed to investigate whether drug levels in blood correlated with protective effect.[6] They showed that TDF-FTC taken daily was safe and provided an average of 44% (95% CI, 15 to 63%) protection against HIV infection. The level of protection shown varied depending on how consistently participants used PrEP. Among those whose data (based on self-reports, bottles dispensed, and pill counts) indicated adherence of 90% or more, HIV risk was reduced by roughly 73% (95% CI, 41 to 88%), while among those whose adherence was less than 90%, HIV risk was reduced by only about 21% (95% CI, 52 to 31%).[6] As per the protocol stipulations, plasma was tested for the presence of active intracellular metabolites of TDF-FTC and TFV, that is, FTC triphosphate (FTC-TP) and tenofovir diphosphate (TFV-DP), respectively, using validated LC/MS assays. Among subjects who became infected with HIV, the median time between the tested specimen date and the last uninfected visit was 35 days (interquartile range, 28 to 56). In the TDF-FTC group, the study drug was detected in 22 of 43 of seronegative subjects (51%) and in 3 of 34 HIV-infected subjects (9%) (< 0.001). In the TDF-FTC group, among subjects with a detectable study-drug level, as compared with those without a detectable level, the odds of HIV infection were lower by a factor of 12.9% (95% CI, 1.7 to 99.3%; < 0.001), corresponding to a relative reduction in HIV risk of 92% (95% CI, 40 to 99%; < 0.001). After adjustment for reported unprotected receptive anal intercourse, the relative risk reduction was 95% (95% CI, 70 to 99%; < 0.001).[6]

The iPrEx trial is another example that highlights the importance of incorporating measurements of correlates of effectiveness in the parent protocol and collecting well-timed and appropriate specimens. This speeds up elucidation of the clinical trial results, which in turn expedites translation, and implementation of findings into clinical practice.

RV144: a phase III trial to examine safety and efficacy of HIV vaccine ALVAC and AIDSVAX B/E

  1. Top of page
  2. Abstract
  3. Introduction
  4. Lessons learnt from prevention trials
  5. CAPRISA 004: a phase IIB trial that assessed the safety and effectiveness of 1% tenofovir microbicide gel
  6. iPrEx: a phase III trial that assessed the safety and efficacy of TDF-FTC oral PrEP
  7. RV144: a phase III trial to examine safety and efficacy of HIV vaccine ALVAC and AIDSVAX B/E
  8. Discussion
  9. Conclusion
  10. Future implications
  11. Acknowledgements
  12. References

Approximately two years after the main outcome results of RV144 were announced in 2009, Haynes announced preliminary results on the correlates of protection at the AIDS Vaccine 2011 conference held in Bangkok.[26] Low efficacy of vaccines, which only elicited either cellular or humoral immune responses, strongly suggested the necessity of a vaccine consisting of immunogens that would modulate the association between HIV exposure and the outcome of infection by targeting both limbs of the adaptive immune system. Therefore, RV144 was designed to test the efficacy of a vaccine consisting of a recombinant canarypox vector vaccine [ALVAC-HIV (vCP1521)] plus a recombinant glycoprotein 120 subunit vaccine (AIDSVAX B/E).[17] In this trial, the vaccine and placebo were administered to 16,402 healthy men and women between the ages of 18-30 years in Rayong and Chon Buri provinces in Thailand. The estimated efficacy was 31.2% for protection against HIV-1 infection in the modified intention-to-treat (MITT) analysis; however, no effect in viral load and CD4+ counts were observed in vaccine recipients with breakthrough HIV infection. As this trial has been shown to be the most successful HIV vaccine trial thus far albeit with results that are difficult to explain, the importance of studying the underlying immune responses in vaccine recipients is highlighted. Blood specimens were collected from 41 HIV-infected and 205 uninfected vaccine recipients, and 40 placebo recipients were further studied in six primary and 30 secondary assays.[19] In primary assays, the following immune responses were measured: binding IgA antibodies in plasma; IgG avidity to A244 gp120 (the antigen used in the vaccine candidates); ADCC; neutralizing antibodies; binding IgG antibodies to the V1/V2 loops of HIV Envelope scaffolded onto a gp70 from murine leukemia virus; and CD4+ T-cell responses as measured by secretion of the cytokines interferon-gamma, interleukin-2, tumor necrosis factor-alpha, and expression of the CD154 surface marker. An interesting observation was the correlation of the high titre of plasma IgA with a 54% increase in the HIV infection rate, due to interference of IgA with binding of IgG to V1/V2 on gp120.[19]

Understanding and hence collecting mucosal specimens from the genital tract as the portal of entry is one of the lessons learned from previous trials.[27] However, the field continues to be wanting in this regard.[28, 29] For instance, this trial collected inadequate mucosal specimens, and hence only plasma IgA that differs from mucosal IgA was analyzed. An analyses of RV152, a follow-up trial for RV144 breakthrough HIV infections, found a low viral load in seminal fluid of male vaccine recipients, a finding that was not statistically significant in dilute cervicovaginal (CVL) specimens collected in women.[30] This finding suggests that the vaccine could induce mucosal immune responses that were not revealed by analyzing only peripheral blood specimens in RV144.[30] For further studies of mucosal immune responses, Rerks-Ngarm et al. proposed more rigorous collection of mucosal specimens in future studies. This shortcoming once again emphasizes the importance of a meticulous clinical trial design that enables further pathogenesis studies of delineating biological mechanisms of protection and effectiveness.

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Lessons learnt from prevention trials
  5. CAPRISA 004: a phase IIB trial that assessed the safety and effectiveness of 1% tenofovir microbicide gel
  6. iPrEx: a phase III trial that assessed the safety and efficacy of TDF-FTC oral PrEP
  7. RV144: a phase III trial to examine safety and efficacy of HIV vaccine ALVAC and AIDSVAX B/E
  8. Discussion
  9. Conclusion
  10. Future implications
  11. Acknowledgements
  12. References

The main focus of this article is to highlight the importance of collecting timeous, appropriate, and relevant specimens within clinical trials to study both the natural correlates of protection and the drug-related surrogates of effectiveness in protection against HIV acquisition. It is difficult, however, to recommend standard timing of sample collection, type of sampling device, and sub-compartment to sample from for all biomedical clinical trials because (i) correlates of protection are not always known and as such surrogates or indirect measures of biological activity are instead used in certain instances; (ii) different drug administration routes have different pharmacokinetics and pharmacodynamics in different biological compartments; and (iii) confounders and mediators of the association between the exposure and outcome may vary depending on route of drug administration.

Timeous specimen collection refers to specimen collection closest to the time of infection – time points immediately prior to and post-estimated date of infection. Seroconversion (time point at which viral RNA copies are detected in blood) following sexual mucosal exposure to HIV takes an estimated 10 days in human studies while mucosal transmission with its distinctive local expansion and propagation of founder virus population takes a few hours to a few days in macaque studies.[31, 32] This period thus presents the window of opportunity to study natural protection correlates, to intervene biomedically to prevent or abort infection and to study the impact of biomedical intervention on effectiveness and/or protection. Inherently, it is the events occurring during this period that we need to study thoroughly to effectively manipulate the immune system for the prevention of HIV infection and disease progression.

Collecting relevant specimens for studying determinants and mechanisms of HIV infection entails collecting specimens that reflect the dynamics of HIV infection establishment. Over and above structural and sociocultural factors, biological factors, such as viral characteristics, host genetic architecture, and immune responses at the portal of entry, play major roles in determining the outcome of infection following exposure to sexually transmitted HIV (Fig. 1). Presence of drug and its impact on the local genital tract ecosystem further refines the outcome following exposure. For instance, in a phase III microbicide trial of nonoxynol-9, a detergent-based spermicidal microbicide that works by disrupting cell membranes, the mucosal barrier was disrupted and thereby paradoxically increasing the risk of transmission despite reassuring data from early phase trials.[33]

image

Figure 1. Dynamics of HIV infection determinants: balance between structural, socio-behavioral, and biological factors.

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In other clinical trials, further biological factors shown to modulate the risk of infection include changes in vaginal pH, presence of infections, inflammation, immune activation, and seminal factors of the transmitter. Bacterial vaginosis and other inflammatory sexually transmitted infections (STIs) such as chlamydia and herpes simplex virus have been shown to significantly increase the risk of HIV acquisition.[34] Inflammation has been shown to be a necessary step in productive infection as it enhances recruitment of target cells,[35] and together with the drug used, may or may not impair the viral bottleneck of transmission and encourage multivariant infection.[20] Systemic innate immune activation has also been shown to increase the risk of HIV acquisition, an association that may remain undeterred in the presence of HIV preventive strategies.[21, 22] Semen and seminal proteins have been shown to negatively influence anti-HIV and anti-HSV activities of microbicides PRO 2000 and cellulose sulfate, both of which failed to provide protection in Phase III clinical trials.[34-39] Lastly, in women, endogenous and exogenous hormones have been shown to modulate the risk of HIV acquisition in the context of sexual transmission of HIV.[40, 41] Evidently, some if not all these factors need to be included or controlled for in any analyses that seek to understand correlates of protection and effectiveness in sexually transmitted HIV infection, and hence, the collection of specimens to address them needs to be encouraged.[42-44] (Fig. 2)

image

Figure 2. Competing indications for genital tract specimens in sexually transmitted HIV biomedical prevention and pathogenesis research. Various factors mediate and/or confound the association between HIV exposure and the outcome of HIV infection, and hence there may be competing interests for specimens collected in order to understand correlates of protection/effectiveness in sexually transmitted HIV. In PrEP trials, adrug or active metabolite levels in different genital tract subcompartments are used as surrogate markers of effectiveness whereas in other prevention trials such as vaccines bimmunological markers are more appropriate as correlates of protection. cSemen and seminal proteins are a significant determinant of infection following exposure to HIV and the preventive drug thereof and have been shown to potentially dampen the effect of PrEP strategy thus tilting the scale towards risk rather than protection. dPresence of infections leads to pro-inflammation and subsequent recruitment of target cells necessary in productive infection, suppresses innate immunity, alters microbiota, cause breach in mucosa which increase the risk of HIV acquisition. Mucosal breach and inflammation, as has been observed with local preventive strategies, have been shown to mitigate the eviral bottleneck of transmission, thus being associated with increased risk of multivariant infection. Consequently it is important to study the impact of the preventive strategy on the viral bottleneck of transmission and evolution.

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One of the common practices in biomedical prevention studies is to collect and store CVL to run assays to address all the five scientific indications discussed above, and yet, CVL is not always appropriate for various reasons. CVL is merely a representation of cervicovaginal secretions containing few desquamated cells presented in a dilute solution and as such is not amenable to all assays. Jespers et al. in two publications have done a comprehensive review of various types of specimens collected from different sub-compartments of the genital tract and sampled for various scientific indications, and hence, this will not be repeated here.[45, 46] However, we do want to emphasize the importance of having the primary scientific question guide the choice of specimen collected. To illustrate this, we present various specimens that could be collected to answer different research questions related to the same drug by sampling different sub-compartments[47, 48] (Table 1). The anatomical site within the genital tract from which to collect the specimen, sampling device, timing of collection, and the method of collection and processing of the specimen is determined by the scientific question at hand.

Table 1. Five Matrices Sampled for Studies of Pharmacokinetics and Pharmacodynamics of Tenofovir gel Post-Intravaginal Administration
Sampling sub-compartmentsSpecimenExamples of research QuestionsApplication
  1. Collection of aundiluted cervicovaginal fluid using a Rovumeter® (Recipe Pharmaceuticals, Munich, Germany), btissue biopsy using the Tischler forceps. TNF (Tenofovir) and TNF-DP (intracellular active metabolite – tenofovir diphosphate) measured in five biological matrices: cervicovaginal fluid (CVF), vaginal and cervical biopsy tissues, endocervical mononuclear cells, blood plasma and PBMC's.

Cervico-vaginal fluidDirect aspiratea

Is the drug being administered at all intravaginally?

Is TFV present around the time of infection?

Measure TNF

TNF detection is a predictor of adherence

To determine whether TNF exposure predicts protection/efficacy, seroconversion, and development of resistance

To develop a pK model to determine what level predicts protection/efficacy, seroconversion, and development of resistance

Differential penetration and pharmacokinetics in different tissues

Cervix and vagina tissuesBiopsyb

Is the administered drug absorbed into the mucosa tissues?

Is the absorbed drug metabolized, that is, phosphorylated into its active form?

Do target cells take up the absorbed drug?

Measure TFV-DP

To determine whether TFV-DP exposure predicts protection/efficacy, seroconversion, and development of resistance

To develop a pK model to determine what level predicts protection/efficacy, seroconversion, and development of resistance

Differential penetration and pharmacokinetics in different tissues

Cervical mononuclear cellsEndocervical cytobrushIs the administered drug metabolized into its active form in the intracellular compartment?

pK studies

Differential penetration and pharmacokinetics in different tissues

BloodPlasmaHow much of the drug administered intravaginally is absorbed into the systemic circulation?

pK studies

Systemic absorption and safety

Differential penetration and pharmacokinetics in different tissues

BloodPBMCsHow much of the drug administered intravaginally is absorbed into the systemic cellular compartment?

pK studies

Differential penetration and pharmacokinetics in different tissues

Conclusion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Lessons learnt from prevention trials
  5. CAPRISA 004: a phase IIB trial that assessed the safety and effectiveness of 1% tenofovir microbicide gel
  6. iPrEx: a phase III trial that assessed the safety and efficacy of TDF-FTC oral PrEP
  7. RV144: a phase III trial to examine safety and efficacy of HIV vaccine ALVAC and AIDSVAX B/E
  8. Discussion
  9. Conclusion
  10. Future implications
  11. Acknowledgements
  12. References

Following on from clinical trials with unexpected and perplexing outcomes, it is evident that laboratory science ought to be an important component of clinical trials to explain and understand the outcomes, to identify correlates of harm and/or protection, and to delineate mechanisms that mediate the association between the exposure and outcome. As such, moving in a unidirectional manner from pre-clinical to clinical research and licensure and registration is no longer sufficient. We propose that trials should be designed such as to enable a return to laboratory sciences alongside clinical trials.

Future implications

  1. Top of page
  2. Abstract
  3. Introduction
  4. Lessons learnt from prevention trials
  5. CAPRISA 004: a phase IIB trial that assessed the safety and effectiveness of 1% tenofovir microbicide gel
  6. iPrEx: a phase III trial that assessed the safety and efficacy of TDF-FTC oral PrEP
  7. RV144: a phase III trial to examine safety and efficacy of HIV vaccine ALVAC and AIDSVAX B/E
  8. Discussion
  9. Conclusion
  10. Future implications
  11. Acknowledgements
  12. References

To conduct pathogenesis research that enhances our understanding of natural correlates of protection and/or harm, appropriate, correctly timed, and adequate biological specimens need to be collected, processed, and stored. Likewise, in the context of clinical trials, to understand the impact of pre-exposure prophylaxis on acquisition and subsequent disease progression, appropriately timed specimens should be collected closest to the estimated time of infection and stored appropriately. Validated and standardized assays, as much as is possible, should be employed to process and analyze biological specimens. To enhance this comprehensive research agenda, all important stakeholders including funders, sponsors, and researchers should be conscious of this fact due to cost implications. Furthermore, sample collection and a nested seroconverter cohort necessitate cross-disciplinary co-ordination, a fact which ought to be considered in protocol design. We propose steps that may be adopted by different clinical trials to enhance this research agenda (Box 1).

Box 1. Necessary steps to enhance the laboratory research agenda within clinical trials include the following

  • Incorporating and prioritizing the objectives of the laboratory science program within the parent clinical trial protocol
  • Designing the laboratory science program in a collaborative manner with laboratory scientists including virologists, geneticists, immunologists, and pharmacists from the outset
  • Establishing a cohort of participants with breakthrough infections
    • Timeous detection of HIV infection using sensitive assays during clinical trial follow-up
    • Timeous recruitment of these participants during the acute infection phase into the laboratory science program is crucial to capture acute infection events and study immunophysiological mechanisms
  • Collecting and storing relevant, appropriate, and appropriately timed biological specimens
    • Genital mucosal specimens in the context of sexual transmission and prevention thereof should be prioritized
      • Different indications (virology, immunology, pharmacokinetics, and microbiology) each necessitate specimens collected using different devices
      • Different indications necessitate specimens collected from different sub-compartments of the genital tract (e.g., endocervix, ectocervix, transformation zone, and vagina in women)
      • Different indications necessitate specimens processed differently
    • Specimens collected closest to the estimated time of infection are crucial for understanding correlates of protection/harm
      • Pre-infection specimens are important for predicting infection
      • Post-infection specimens are important for studying acute infection and predicting disease progression

Acknowledgements

  1. Top of page
  2. Abstract
  3. Introduction
  4. Lessons learnt from prevention trials
  5. CAPRISA 004: a phase IIB trial that assessed the safety and effectiveness of 1% tenofovir microbicide gel
  6. iPrEx: a phase III trial that assessed the safety and efficacy of TDF-FTC oral PrEP
  7. RV144: a phase III trial to examine safety and efficacy of HIV vaccine ALVAC and AIDSVAX B/E
  8. Discussion
  9. Conclusion
  10. Future implications
  11. Acknowledgements
  12. References

The Oxford Nuffield Medical Fellowship and Discovery Foundation Academic Fellowship schemes support Sengeziwe Sibeko and the Columbia University–Southern African Fogarty AIDS International Training and Research Programme (AITRP), funded by the Fogarty International Center, National Institutes of Health (grant D43TW00231), supported her training.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Lessons learnt from prevention trials
  5. CAPRISA 004: a phase IIB trial that assessed the safety and effectiveness of 1% tenofovir microbicide gel
  6. iPrEx: a phase III trial that assessed the safety and efficacy of TDF-FTC oral PrEP
  7. RV144: a phase III trial to examine safety and efficacy of HIV vaccine ALVAC and AIDSVAX B/E
  8. Discussion
  9. Conclusion
  10. Future implications
  11. Acknowledgements
  12. References
  • 1
    UNAIDS: Global HIV/AIDS Response-Progress Report, 2011. In http://www.unaids.org/en/resources/publications/2011/name, 2011.
  • 2
    Hladik F, McElrath MJ: Setting the stage: host invasion by HIV. Nat Rev Immunol 2008; 8:447457.
  • 3
    UNAIDS: UNAIDS report on the global AIDS epidemic 2010. In http://www.unaids.org/globalreport, 2010.
  • 4
    Padian NS, McCoy SI, Karim SS, Hasen N, Kim J, Bartos M, Katabira E, Bertozzi SM, Schwartländer B, Cohen MS: HIV prevention transformed: the new prevention research agenda. Lancet 2011; 378:269278.
  • 5
    van der Straten A, Van Damme L, Haberer JE, Bangsberg DR: Unraveling the divergent results of pre-exposure prophylaxis trials for HIV prevention. AIDS 2012; 26:F13F19.
  • 6
    Grant RM, Grant RM, Anderson PL, McMahan V, Liu AY, Vargas L, Goicochea P, Casapía M, Guanira-Carranza JV, Ramirez-Cardich ME, Montoya-Herrera O, Fernández T, Veloso VG, Buchbinder SP, Chariyalertsak S, Schechter M, Bekker LG, Mayer KH, Kallás EG, Amico KR, Mulligan K, Bushman LR, Hance RJ, Ganoza C, Defechereux P, Postle B, Wang F, McConnell JJ, Zheng JH, Lee J, Rooney JF, Jaffe HS, Martinez AI, Burns DN: Glidden DV; iPrEx Study Team: preexposure chemoprophylaxis for HIV prevention in men who have sex with men. N Engl J Med 2010; 363:25872599.
  • 7
    Thigpen MC, Kebaabetswe PM, Paxton LA, Smith DK, Rose CE, Segolodi TM, Henderson FL, Pathak SR, Soud FA, Chillag KL, Mutanhaurwa R, Chirwa LI, Kasonde M, Abebe D, Buliva E, Gvetadze RJ, Johnson S, Sukalac T, Thomas VT, Hart C, Johnson JA, Malotte CK, Hendrix CW; Brooks JT; TDF2 Study Group: Antiretroviral Preexposure Prophylaxis for Heterosexual HIV Transmission in Botswana. N Engl J Med 2012; 367:423434.
  • 8
    Van Damme L, Corneli A, Ahmed K, Agot K, Lombaard J, Kapiga S, Malahleha M, Owino F, Manongi R, Onyango J, Temu L, Monedi MC, Mak'Oketch P, Makanda M, Reblin I, Makatu SE, Saylor L, Kiernan H, Kirkendale S, Wong C, Grant R, Kashuba A, Nanda K, Mandala J, Fransen K, Deese J, Crucitti T, Mastro TD, Taylor D; FEM-PrEP Study Group: Preexposure prophylaxis for HIV infection among African women. N Engl J Med 2012; 367: 411422.
  • 9
    Abdool Karim Q, Abdool Karim SS, Frohlich JA, Grobler AC, Baxter C, Mansoor LE, Kharsany AB, Sibeko S, Mlisana KP, Omar Z, Gengiah TN, Maarschalk S, Arulappan N, Mlotshwa M, Morris L, Taylor D; CAPRISA 004 Trial Group: Effectiveness and safety of tenofovir gel, an antiretroviral microbicide, for the prevention of HIV infection in women. Science 2010; 329: 11681174.
  • 10
    Microbicide Trials Network: MTN statement on decision to discontinue use of tenofovir gel in VOICE, a major HIV prevention study in women. In http://www.mtnstopshiv.org/node/3909, 2011.
  • 11
    Peterson L, Taylor D, Roddy R, Belai G, Phillips P, Nanda K, Grant R, Clarke EE, Doh AS, Ridzon R, Jaffe HS, Cates W: Tenofovir disoproxil fumarate for prevention of HIV infection in women: a phase 2, double-blind, randomized, placebo-controlled trial. PLoS Clin Trials 2007; 2:e27.
  • 12
    Baeten JM, Donnell D, Ndase P, Mugo NR, Campbell JD, Wangisi J, Tappero JW, Bukusi EA, Cohen CR, Katabira E, Ronald A, Tumwesigye E, Were E, Fife KH, Kiarie J, Farquhar C, John-Stewart G, Kakia A, Odoyo J, Mucunguzi A, Nakku-Joloba E, Twesigye R, Ngure K, Apaka C, Tamooh H, Gabona F, Mujugira A, Panteleeff D, Thomas KK, Kidoguchi L, Krows M, Revall J, Morrison S, Haugen H, Emmanuel-Ogier M, Ondrejcek L, Coombs RW, Frenkel L, Hendrix C, Bumpus NN, Bangsberg D, Haberer JE, Stevens WS, Lingappa JR, Celum C: Antiretroviral prophylaxis for HIV prevention in heterosexual men and women. N Engl J Med 2012; 367:399410.
  • 13
    Gilbert PB, Peterson ML, Follmann D, Hudgens MG, Francis DP, Gurwith M, Heyward WL, Jobes DV, Popovic V, Self SG, Sinangil F, Burke D, Berman PW: Correlation between immunologic responses to a recombinant glycoprotein 120 vaccine and incidence of HIV-1 infection in a phase 3 HIV-1 preventive vaccine trial. J Infect Dis 2005; 191:666677.
  • 14
    Pitisuttithum P, Gilbert P, Gurwith M, Heyward W, Martin M, van Griensven F, Hu D, Tappero JW, Choopanya K; Bangkok Vaccine Evaluation Group: Randomized, double-blind, placebo-controlled efficacy trial of a bivalent recombinant glycoprotein 120 HIV-1 vaccine among injection drug users in Bangkok, Thailand. J Infect Dis 2006; 194:16611671.
  • 15
    Buchbinder SP, Mehrotra DV, Duerr A, Fitzgerald DW, Mogg R, Li D, Gilbert PB, Lama JR, Marmor M, Del Rio C, McElrath MJ, Casimiro DR, Gottesdiener KM, Chodakewitz JA, Corey L, Robertson MN; Step Study Protocol Team: Efficacy assessment of a cell-mediated immunity HIV-1 vaccine (the Step Study): a double-blind, randomised, placebo-controlled, test-of-concept trial. Lancet 2008; 372:18811893.
  • 16
    Gray GE, Allen M, Moodie Z, Churchyard G, Bekker LG, Nchabeleng M, Mlisana K, Metch B, de Bruyn G, Latka MH, Roux S, Mathebula M, Naicker N, Ducar C, Carter DK, Puren A, Eaton N, McElrath MJ, Robertson M, Corey L, Kublin JG; HVTN 503/Phambili study team: 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. Lancet Infect Dis 2011; 11:507515.
  • 17
    Rerks-Ngarm S, Pitisuttithum P, Nitayaphan S, Kaewkungwal J, Chiu J, Paris R, Premsri N, Namwat C, de Souza M, Adams E, Benenson M, Gurunathan S, Tartaglia J, McNeil JG, Francis DP, Stablein D, Birx DL, Chunsuttiwat S, Khamboonruang C, Thongcharoen P, Robb ML, Michael NL, Kunasol P, Kim JH; MOPH-TAVEG Investigators: Vaccination with ALVAC and AIDSVAX to prevent HIV-1 infection in Thailand. N Engl J Med 2009; 361:22092220.
  • 18
    McElrath MJ, De Rosa SC, Moodie Z, Dubey S, Kierstead L, Janes H, Defawe OD, Carter DK, Hural J, Akondy R, Buchbinder SP, Robertson MN, Mehrotra DV, Self SG, Corey L, Shiver JW, Casimiro DRStep Study Protocol Team: HIV-1 vaccine-induced immunity in the test-of-concept Step Study: a case-cohort analysis. Lancet 2008; 372:18941905.
  • 19
    Haynes BF, Gilbert PB, McElrath MJ, Zolla-Pazner S, Tomaras GD, Alam SM, Evans DT, Montefiori DC, Karnasuta C, Sutthent R, Liao HX, DeVico AL, Lewis GK, Williams C, Pinter A, Fong Y, Janes H, DeCamp A, Huang Y, Rao M, Billings E, Karasavvas N, Robb ML, Ngauy V, de Souza MS, Paris R, Ferrari G, Bailer RT, Soderberg KA, Andrews C, Berman PW, Frahm N, De Rosa SC, Alpert MD, Yates NL, Shen X, Koup RA, Pitisuttithum P, Kaewkungwal J, Nitayaphan S, Rerks-Ngarm S, Michael NL, Kim JH: Immune-correlates analysis of an HIV-1 vaccine efficacy trial. N Engl J Med 2012; 366:12751286.
  • 20
    Valley-Omar Z, Sibeko S, Anderson J, Goodier S, Werner L, Arney L, Naranbhai V, Treurnicht F, Abrahams MR, Bandawe G, Swanstrom R, Karim QA, Karim SS, Williamson C: CAPRISA 004 tenofovir microbicide trial: no impact of tenofovir gel on the HIV transmission bottleneck. J Infect Dis 2012; 206:3540.
  • 21
    Naranbhai V, Abdool Karim SS, Altfeld M, Samsunder N, Durgiah R, Sibeko S, Abdool Karim Q, Carr WH; the CAPRISA004 TRAPS team: Innate immune activation enhances HIV acquisition in women, diminishing the effectiveness of tenofovir microbicide gel. J Infect Dis 2012; 206: 9931001.
  • 22
    Mureithi MW, Poole D, Naranbhai V, Reddy S, Mkhwanazi NP, Sibeko S, Werner L, Abdool Karim Q, Abdool Karim S, Ndung'u T, Altfeld M; CAPRISA004 Trial Group: Preservation HIV-1-specific IFNγ+ CD4+ T-cell responses in breakthrough infections after exposure to tenofovir gel in the CAPRISA 004 microbicide trial. J Acquir Immune Defic Syndr 2012; 60: 124127.
  • 23
    Abdool Karim SS, Kashuba AD, Werner L, Karim QA: Drug concentrations after topical and oral antiretroviral pre-exposure prophylaxis: implications for HIV prevention in women. Lancet 2011; 378:279281.
  • 24
    Abdool Karim Q: Safety and effectiveness of 1% tenofovir vaginal microbicide gel in South African women: results of the CAPRISA 004 trial. XVIII International AIDS Conference, Vienna, Austria 2010. In http://pag.aids2010.org/session.aspx?s=13.
  • 25
    Kashuba A, Abdool Karim S, Kraft E, White N, Sibeko S, Werner L, Mansoor LE, Gengiah T, Sidhoo S, Abdool Karim Q: Do systemic and genital tract tenofovir concentrations predict HIV seroconversion in the CAPRISA 004 tenofovir gel trial? In XVIII International AIDS Conference, Vienna, Austria 2010.
  • 26
    Haynes BF: Case Control Study of the RV144 Trial for Immune Correlates: The Analysis and Way Forward. AIDS Vaccine Conference, Bangkok, Thailand 2011, 2011. In http://app2.capitalreach.com/esp1204/servlet/tc?cn=aidsvac&c=10188&s=20457&e=16000&#plenary01.
  • 27
    Haynes BF, Shattock RJ: Critical issues in mucosal immunity for HIV-1 vaccine developmen. J Allergy Clin Immunol 2008; 122:39.
  • 28
    Kim JH, Rerks-Ngarm S, Excler JL, Michael NL: HIV vaccines: lessons learned and the way forward. Curr Opin HIV AIDS 2010; 5:428434.
  • 29
    Spetz AL, Chiodi F: Reduction of HIV-1 load in semen during follow-up study of RV144 vaccine trial boosts interest for novel correlates of immune protection in genital mucosa. J Infect Dis 2012; 24:111.
  • 30
    Rerks-Ngarm S, Paris RM, Chunsutthiwat S, Premsri N, Namwat C, Bowonwatanuwong C, Li SS, Kaewkungkal J, Trichavaroj R, Churikanont N, de Souza MS, Andrews C, Francis D, Adams E, Flores J, Gurunathan S, Tartaglia J, O'Connell RJ, Eamsila C, Nitayaphan S, Ngauy V, Thongcharoen P, Kunasol P, Michael NL, Robb ML, Gilbert PB, Kim JH: Extended evaluation of the virologic, immunologic, and clinical course of volunteers who acquired HIV-1 infection in a phase III vaccine trial of ALVAC-HIV and AIDSVAX B/E. J Infect Dis 2012. Epub ahead of print.
  • 31
    McMichael AJ, Borrow P, Tomaras GD, Goonetilleke N, Haynes BF: The immune response during acute HIV-1 infection: clues for vaccine development. Nat Rev Immunol 2010; 10:1123.
  • 32
    Haase AT: Targeting early infection to prevent HIV-1 mucosal transmission. Nature 2010; 464:217223.
  • 33
    Van Damme L, Ramjee G, Alary M, Vuylsteke B, Chandeying V, Rees H, Sirivongrangson P, Mukenge-Tshibaka L, Ettiègne-Traoré V, Uaheowitchai C, Karim SS, Mâsse B, Perriëns J, Laga M, COL-1492 Study Group: Effectiveness of COL-1492, a nonoxynol-9 vaginal gel, on HIV-1 transmission in female sex workers: a randomised controlled trial. Lancet 2002; 360:971977.
  • 34
    Thurman AR, Doncel GF: Innate immunity and inflammatory response to Trichomonas vaginalis and bacterial vaginosis: relationship to HIV acquisition. Am J Reprod Immunol 2011; 65:8998.
  • 35
    Li Q, Estes JD, Schlievert PM, Duan L, Brosnahan AJ, Southern PJ, Reilly CS, Peterson ML, Schultz-Darken N, Brunner KG, Nephew KR, Pambuccian S, Lifson JD, Carlis JV, Haase AT: Glycerol monolaurate prevents mucosal SIV transmission. Nature 2009; 458:10341038.
  • 36
    McCormack S, Ramjee G, Kamali ARH, Crook AM, Gafos M, Jentsch U, Pool R, Chisembele M, Kapiga S, Mutemwa R, Vallely A, Palanee T, Sookrajh Y, Lacey CJ, Darbyshire J, Grosskurth H, Profy A, Nunn A, Hayes R, Weber J: PRO2000 vaginal gel for prevention of HIV-1 infection (Microbicides Development Programme 301): a phase 3, randomised, double-blind, parallel-group trial. Lancet 2010; 376:13291337.
  • 37
    Van Damme L, Govinden R, Mirembe FM, Guédou F, Solomon S, Becker ML, Pradeep BS, Krishnan AK, Alary M, Pande B, Ramjee G, Deese J, Crucitti T, Taylor D, CS Study Group: Lack of effectiveness of cellulose sulfate gel for the prevention of vaginal HIV transmission. N Engl J Med 2008; 359:463472.
  • 38
    Herold BC, Mesquita PM, Madan RP, Keller MJ: Female genital tract secretions and semen impact the development of microbicides for the prevention of HIV and other sexually transmitted infections. Am J Reprod Immunol 2011; 65:325333.
  • 39
    Keller MJ, Mesquita PM, Torres NM, Cho S, Shust G, Madan RP, Cohen HW, Petrie J, Ford T, Soto-Torres L, Profy AT, Herold BC: Postcoital bioavailability and antiviral activity of 0.5% PRO 2000 gel: implications for future microbicide clinical trials. PLoS ONE 2010; 5:e8781.
  • 40
    Morrison CS, Chen PL, Kwok C, Richardson BA, Chipato T, Mugerwa R, Byamugisha J, Padian N, Celentano DD, Salata RA: Hormonal contraception and HIV acquisition: reanalysis using marginal structural modeling. AIDS [Internet]. 2010; 24:17771778.
  • 41
    Heffron R, Donnell D, Rees H, Celum C, Mugo N, Were E, de Bruyn G, Nakku-Joloba E, Ngure K, Kiarie J, Coombs RW, Baeten JM: Partners in Prevention HSV/HIV Transmission Study Team: Use of hormonal contraceptives and risk of HIV-1 transmission: a prospective cohort study. The Lancet Infect dis [Internet]. 2012; 12:1926.
  • 42
    Dezzutti CS, Hendrix CW, Marrazzo JM, Pan Z, Wang L, Louissaint N, Kalyoussef S, Torres NM, Hladik F, Parikh U, Mellors J, Hillier SL, Herold BC: Performance of swabs, lavage, and diluents to quantify biomarkers of female genital tract soluble mucosal mediators. PLoS ONE 2011; 6:e23136.
  • 43
    Snowhite IV, Jones WE, Dumestre J, Dunlap K, Braly PS, Hagensee ME: Comparative analysis of methods for collection and measurement of cytokines and immunoglobulins in cervical and vaginal secretions of HIV and HPV infected women. J Immunol Methods 2002; 263:8595.
  • 44
    Coombs RW, Reichelderfer PS, Landay AL: Recent observations on HIV type-1 infection in the genital tract of men and women. AIDS 2003; 17:455480.
  • 45
    Jespers V, Harandi AM, Hinkula J, Medaglini D, Le R, Stahl-Hennig C, Bogers W, El Habib R, Wegmann F, Fraser C, Cranage M, Shattock RJ, Spetz AL: Assessment of mucosal immunity to HIV-1. Expert Rev Vaccines 2010; 9:381394.
  • 46
    Jespers V, Francis SC, van de Wijgert J, Crucitti T: Methodological issues in sampling the local immune system of the female genital tract in the context of HIV prevention trials. Am J Reprod Immunol 2011; 65:368376.
  • 47
    Patterson KB, Prince HA, Kraft E, Jenkins AJ, Shaheen NJ, Rooney JF, Cohen MS, Kashuba AD: Penetration of tenofovir and emtricitabine in mucosal tissues: implications for prevention of HIV-1 transmission. Sci Transl Med 2011; 3:112re4.
  • 48
    Dumond J, Yeh R. Antiretroviral drug exposure in the female genital tract: implications for oral pre-and post-exposure prophylaxis. AIDS 2007; 21:18991907.