Prophylactic vaccination against human papillomaviruses to prevent cervical cancer and its precursors

Abstract

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To evaluate the immunogenicity, clinical efficacy, and safety of prophylactic HPV vaccines in females. The assessment of clinical efficacy will address protection against HPV infection (for homologous and heterologous HPV types), against re‐infection, against cervical cancer and its precursors (high‐grade CIN (grade 2 or grade 3), adenocarcinoma in situ) in women previously not exposed to HPV infection (negative at enrolment for both HPV DNA and antibodies against the vaccine HPV types). We will assess clinical effectiveness by evaluating outcomes in all women, irrespective of the HPV DNA or serology status at enrolment. Evaluation by fine age and time since sexual debut categories is also planned.

Background

Description of the condition

Association between human papillomavirus (HPV) infection and cervical cancer and other HPV‐related cancers and their precursors

The development of cervical cancer passes through a number of phases: (a) infection of the cervical epithelium with certain human papillomavirus (HPV) types; (b) persistence of the HPV infection; (c) progression to precancerous lesions (cervical intraepithelial neoplasia (CIN) and (d) eventually invasion. All phases are reversible, except for the last one (Bosch 2002; Castellsague 2006; IARC 2007). Recently, an IARC (International Agency for Research on Cancer) expert group reviewed the carcinogenicity of human papilloviruses and confirmed that for 12 HPV types (HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, and 59) sufficient evidence exists that they are causally linked with the development of cervical cancer (Bouvard 2009). Type HPV 68 is considered as probably carcinogenic (Schiffman 2009). The HPV type 16, in particular, has a high potential for malignant transformation of infected cervical cells (Schiffman 2005). The HPV types 16 and 18 jointly cause 70% of all the cervical cancers worldwide (Munoz 2004). Moreover, HPV type 16 is also linked with rarer types of cancer, namely cancer of the vulva and vagina in women, penis cancer in men and anus, oropharynx and larynx cancer in women and men (Cogliano 2005; IARC 2007). IARC 2007 

The main route of HPV transmission is sexual. Infection with HPV usually occurs soon after the onset of sexual activity (Winer 2003; Winer 2008). The prevalence of HPV infection generally peaks in late teenage or early twenties and declines thereafter (De Sanjose 2007). Human papillomavirus infection usually clears spontaneously, in particular in women younger than 30 years. Human papillomavirus infection can result in intraepithelial neoplastic cellular lesions which are identifiable by cytological examination (ASCUS, LSIL, HSIL, see list of abbreviations in Appendices) and which can be confirmed histologically (CIN1‐3)*. These lesions generally regress, but the probability of regression decreases, and the likelihood of progression to cancer increases with the duration of HPV infection and the severity of the lesion. From historical data, it has been estimated that CIN3 incurs a probability of progressing to invasive cancer of 12% to 30%; whereas for CIN2 this probability is substantially less (McCredie 2008; Ostor 1993).The natural history of HPV infection to invasive cancer takes a minimum of 10 years and a median of approximately 25 to 30 years (IARC 2007).

A World Health Organization (WHO) expert group accepted a reduction in the incidence of high‐grade CIN (CIN2+) and cervical adenocarcinoma in situ (AIS) or worse as an acceptable surrogate outcome of HPV vaccination trials, since the reduction of the incidence of invasive cervical cancer would require large and lengthy studies which are unlikely to be undertaken (Pagliusi 2004).

The low‐risk HPV types 6 and 11 cause approximately 90% of genital warts in women and men (Lacey 2006). They occur in low‐grade dysplastic cervical lesions but are not associated with cervical cancer (IARC 2007). Moreover, HPV types 6 and 11 cause recurrent respiratory papillomatosis, a rare but very serious disease of the upper airways often requiring repetitive surgical interventions (Lacey 2006).

The recognition of the strong causal association between HPV infection and cervical cancer has resulted in the development of HPV assays to detect cervical cancer precursors (Iftner 2003), and even vaccines that prevent HPV infection (prophylactic vaccines) or that treat HPV‐induced lesions (therapeutic vaccines) (Frazer 2004; Galloway 2003; Schneider 2003). Therapeutic vaccines are still in very early experimental phases and are not further considered in this review.

* Throughout this review, we will use the 2001 Bethesda System to define cytologically defined neoplastic lesions of the cervical epithelium (Solomon 2002) and the CIN nomenclature to define histologically confirmed cervical intraepithelial neoplasia (Richart 1973).

Burden of cervical cancer

Cervical cancer is the third most common cancer in women worldwide (Ferlay 2004). It is estimated that in 2008, approximately 530,000 women developed cervical cancer and that 275,000 died from the disease (Arbyn 2011).  Eighty‐six per cent of cervical cancer cases occur in developing countries. Cervical cancer is the predominant female cancer in Eastern Africa, South‐Central Asia and Melanesia, where a woman's risk of developing this disease by age 75 years ranges between 2.3% and 3.9%. In many developed countries, the incidence of, and mortality from, squamous cervical cancer has dropped substantially over the last decades as a consequence of widespread screening (Bray 2005a; IARC 2004).  For instance, In the USA and North and West‐Europe, the cumulative risk of cervix uteri cancer up to age 65 years is 0.7% or lower (Ferlay 2004). However, approximately 52,000 and 13,000 cases are reported each year in Europe and the USA, respectively (Ferlay 2004). Moreover, the incidence of adenocarcinoma of the cervix is less affected by cytological screening (Bray 2005; Smith 2000). In contrast to many other malignancies, cervical cancer primarily affects younger women, with the majority of cases appearing between the ages of 35 and 50 years (Yang 2004). In Europe, approximately 40% of women with cervical cancer die from the disease within five years of diagnosis (Sant 2009).

Description of the intervention

In this review, we will only study prophylactic HPV vaccines composed of virus‐like particles of the L1 protein, which is the major protein of the capsid of the HPV virus.

To date, three prophylactic HPV vaccines have been developed and clinically evaluated in randomised controlled trials (RCTs): a monovalent HPV16 vaccine (manufactured by Merck, Sharpe & Dome (Merck),Whitehouse Station, NJ, USA); a quadrivalent vaccine, containing the L1 protein of HPV6, HPV11, HPV16 and HPV18 (Gardasil®, produced by the same manufacturer); and a bivalent vaccine containing L1 of HPV types 16 and 18 (Cervarix®, produced by GlaxoSmithKline (GSK), Rixensart, Belgium) (Koutsky 2002). The vaccine produced by Merck contains amorphous aluminium hydroxyphosphate sulphate as an adjuvant, whereas the GSK vaccine contains aluminium salt and ASO4 or monophosphoryl lipid A, which is an immunostimulating molecule (WHO 2009). More details about prophylactic HPV vaccines used are described in Appendix 1.

Animal experiments have shown that neutralising antibodies, elicited by vaccination with papillomavirus VLPs, prevent type‐specific infection and subsequent lesions after viral challenge (Breitburd 1995;Ghim 2000; Stanley 2006). Vaccination by intramuscular injection of L1 VLPs in humans has been demonstrated to be highly immunogenic and well‐tolerated in phase I trials. (Ault 2004; Brown 2001; Evans 2001; Harro 2001;).

Why it is important to do this review

Several phase II and III studies have been conducted to date and numerous reviews have tried to summarise the results (Arbyn 2007; Ault 2007; Harper 2009; Initiative 2009; Kahn 2009; Kjaer 2009; Koutsky 2006; Medeiros 2009; Rambout 2007; Szarewski 2010). However, none of the reviews combined information on all the available endpoints. This is due to incomplete reporting of data, use of different assays, analyses of different per protocol or intention‐to‐treat groups, outcome definitions, lumping of different outcomes, and reporting at variable time points in the scientific literature. Previous reports have also not comprehensively evaluated the impact of vaccination by fine categories of age and time since sexual debut, have not systematically evaluated evidence for cross‐protection against HPV types phylogenetically related to HPV‐16/18, and have not specifically addressed the question of whether vaccination protects against re‐infection among younger and older individuals known to be infected at vaccination and who subsequently clear their infections.  

The objective of this review is to summarise all available (published and unpublished) evidence by combining outcomes with similar definitions and times of measurement. We will request missing outcomes or outcome data missing at specific time points.

Objectives

To evaluate the immunogenicity, clinical efficacy, and safety of prophylactic HPV vaccines in females. The assessment of clinical efficacy will address protection against HPV infection (for homologous and heterologous HPV types), against re‐infection, against cervical cancer and its precursors (high‐grade CIN (grade 2 or grade 3), adenocarcinoma in situ) in women previously not exposed to HPV infection (negative at enrolment for both HPV DNA and antibodies against the vaccine HPV types). We will assess clinical effectiveness by evaluating outcomes in all women, irrespective of the HPV DNA or serology status at enrolment. Evaluation by fine age and time since sexual debut categories is also planned.

Methods

Criteria for considering studies for this review

Types of studies

We will only consider randomised controlled trials (RCTs).

Types of participants

We will include studies that enrol only females, without any age restriction. However, if possible, study participants will be distinguished by age group, sexual history and initial HPV status.

We will not include studies with male participants or special target groups such as immunocompromised patients.

Types of interventions

Intervention

Vaccination with prophylactic HPV vaccines containing virus‐like particles composed of the L1 capsid protein of HPV16 (monovalent vaccine), HPV16 and HPV18 (bivalent vaccine), or HPV6, HPV11, HPV16 and HPV18 (quadrivalent vaccine) (see Appendix 1). All vaccines are administered by intramuscular injection over a period of six months. The monovalent and quadrivalent vaccines are injected at zero, two and six months, whereas the bivalent vaccine is administered at zero, one and six months.

Comparison

Administration of placebo containing no active product or only the adjuvant of the HPV vaccine without L1 VLP, or another non‐HPV vaccine.

In comparisons of bivalent and quadrivalent vaccines, participants who receive the bivalent vaccine will constitute the experimental group and participants who receive the quadrivalent vaccine will be considered as the comparison group.

Types of outcome measures

Primary outcomes

1. Histologically confirmed high‐grade cervical intraepithelial neoplasia (CIN2, CIN3 and adenocarcinoma in situ (AIS).

2. Invasive cervical cancer.

3. Immunogenicty:

   1. percentage of women vaccinated who have seroconverted after the third dose of vaccine;

   2. mean antibody level in International Units (IU) observed after completion of vaccine administration.

4. Safety:

   1. immediate and short term adverse events (observed within four weeks after administration):

      1. local adverse effects (redness, swelling, pain, itching at the injection place);

      2. mild systemic effects;

      3. severe systemic effects;

   2. serious adverse events observed after four weeks of administration of the vaccine during the trial;

   3. pregnancy outcomes observed during the trials, in particular occurrence of congenital anomalies.

Secondary outcomes

1. Incident infection with vaccine HPV types (HPV6, HPV11, HPV16 and HPV18, separately and jointly) and with hrHPV types other than HPV16/18.

2. Persistent infection with vaccine HPV types and hrHPV types other than HPV16/18.

3. Evolution over time of the geometric mean titres of antibodies against the vaccine HPV types.

Search methods for identification of studies

We will search for papers in all languages and undertake translations, if necessary.

Electronic searches

We will retrieve published studies from the Cochrane Gynaecological Cancer Review Group's Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, latest issue), MEDLINE and EMBASE. We have provided the search strategy for MEDLINE in Appendix 2; we will design a similarly structured search strategy to run in EMBASE and to search CENTRAL.

We will save the search string for MEDLINE in My NCBI, an electronic search tool developed by the National Center for Biotechnology Information (NCBI) at the National Library of Medicine, which saves searches and automatically retrieves newer references not picked‐up at previous searches. We will also set up an auto‐alert in EMBASE.

We will use the 'related articles' feature in PubMed, departing from the original included studies; similarly, we will use Scopus to retrieve articles which cite the originally included studies.

We will search databases from 2002 (the year of publication of the results of the first phase II trial) until the present day.

Searching other resources

Websites of regulatory authorities responsible for approval of HPV vaccines for human use

We will consult the websites of the US Food & Drug Administration (FDA) and the European Medicine Agency (EMEA) to retrieve additional data not included in published scientific articles. In particular, we will verify the European Public Assessment Reports (EPAR) established by the Committee for Medicinal Products for Human Use (CHMP) of EMEA for the two HPV vaccines authorised in the European Union:

• http://www.emea.europa.eu/humandocs/Humans/EPAR/cervarix/cervarix.htm;

• http://www.emea.europa.eu/humandocs/Humans/EPAR/gardasil/gardasil.htm.,

We will retrieve data provided by the FDA via the following sites:

• for the quadrivalent vaccine: http://www.fda.gov/BiologicsBloodVaccines/Vaccines/ApprovedProducts/ucm094042.htm;

• for the bivalent vaccine: http://www.fda.gov/BiologicsBloodVaccines/Vaccines/ApprovedProducts/ucm186957.htm.

Registries of randomised trials

We will search the following registries for ongoing trials: www. metaregister.com, www.controlled‐trials.com/rct, www.clinicaltrials.gov and www.cancer.gov/clinicaltrials.

International public health organisations

We will contact international public health organisations that have investigated questions on HPV vaccine efficacy and safety or that have formulated recommendations on the use of HPV vaccines, to retrieve key documents. Concerned organisations include: the World Health Organization (WHO, Geneva), the US Centers for Disease Control and Prevention (CDC, Atlanta), the European Centre for Disease Prevention and Control (ECDC, Stockholm), and the International Agency for Research on Cancer (IARC, Lyon).

Handsearching

We will handsearch the citation lists of included studies.

In addition, we will search the abstracts of the latest conferences of relevant scientific societies related to vaccination, virology (in particular the Papillomavirus Society), paediatrics, and gynaecology for new or pending information not yet published in peer‐reviewed journals.

Correspondence

We will contact the principal investigators of included studies and manufacturers of prophylactic HPV vaccines (MSD, USA) and GSK (Rixensart, Belgium) to obtain available data already published but not sufficiently detailed in published reports. We will develop data sheets to record commonly defined, and timed and efficacy outcomes stratified by age group, sexual history and initial HPV status. We will complete these sheets with data extracted from published reports and we will request any missing data from data owners.

In addition, we will request information on pending or planned relevant trials from principal investigators and researchers of the vaccine manufacturers.

Data collection and analysis

Selection of studies

We will download all titles and abstracts retrieved by electronic searching to a bibliographic database stored in Reference Manager. We will add any references we obtain by handsearching and remove duplicates.

Two review authors (MA and AB) will independently verify inclusion and exclusion of eligible studies and we will discuss any disagreements. In case of doubt, we will read the full report. If no consensus can be reached, we will consult with other review authors. We will document reasons for exclusion.  

Data extraction and management

For included studies, we will extract the following study characteristics and outcome data.

• Study identification: first author, year of publication, journal, trial number.

• Geographical area where the study was conducted.

• Period when study was conducted.

• Inclusion and exclusion criteria.

• Characteristics of included participants (total number enrolled, number of drop‐outs, age, ethnic origin, comorbidity, contraceptive use, number of previous sexual partners, obstetric and gynaecological antecedents, smoking history).

• Initial HPV status (presence or absence of hrHPV DNA; presence or absence of DNA of the vaccine HPV types; serological status (presence of antibodies against vaccine HPV types) at enrolment). Differences in efficacy outcomes by initial HPV status will reflect protection in women or girls previously exposed, or not exposed to prior HPV infection.

• Study design:

• • phase of the randomised trial (II or III);

  • type of vaccine evaluated (monovalent, bivalent, or quadrivalent);

  • control group: type of placebo or other vaccine administered;

  • time points (mean duration of follow‐up after first dose) at which outcomes were collected and reported;

  • study size at enrolment and at subsequent time points of follow‐up;

  • loss to follow‐up according to reason for drop‐out and trial arm, number of doses received, other protocol violations used to assess HPV status (group tests, type‐specific tests);

  • methods used to assess HPV serology;

  • scheduling of screen tests (HPV tests, cytology);

  • diagnostic algorithms used to confirm outcomes;

  • definition of study groups on which per‐protocol and intention‐to‐treat analyses were applied;

  • risk of bias in study design (see below: Assessment of risk of bias in included studies).

• Outcomes, subdivided by the association with vaccine HPV types and all hrHPV types:

  • outcome definition (including diagnostic criteria and assays);

  • unit of measurement; for scales: upper and lower limits, with indication whether high or low score is good;

  • results: number of participants allocated to each intervention group; number of missing values and absolute values required to compute effect measures (see Types of outcome measures).

• Involvement of manufacturers.

We will extract data on outcomes as follows.

• For dichotomous outcomes, we will extract the number of participants in each treatment arm who experienced the outcome of interest and the number of participants assessed at endpoint in order to estimate a risk ratio (RR) or risk difference (RD). Where possible, we will also extract the number of person‐years at risk in order to compute incidence rates and incidence rate ratios or differences.

• For time to event data, the review authors will extract the log of the hazard ratio (log(HR) and its standard error (SE) from trial reports. If these are not reported, or computable from other reported statistics, we will use Adobe Photoshop (Adobe 2007) to prepare digital prints of the published Kaplan‐Meier survival curves (or its complement, the cumulative incidence curve) and note the minimum and maximum duration of follow‐up in order to estimate the log (HR), using the methods proposed by Parmar 1998.

• For continuous outcomes, the review authors will extract the final value and standard deviation (SD) of the outcome of interest and the number of participants assessed in each treatment arm at the end of the considered follow‐up, in order to estimate the mean difference (MD) between treatment arms and its SE, if trials measured outcomes on the same scale; otherwise we will compute standardised mean differences (SMD).

Two review authors (MA, AB) will independently extract data onto a data abstraction form specially designed for the review. We will resolve differences between review authors by discussion or by appeal to a third review author (PMH) if necessary.

Assessment of risk of bias in included studies

We will assess the risk of bias in included RCTs using The Cochrane Collaboration's tool and the criteria specified in chapter 8 of the Cochrane Handbook for Systematic Reviews of Interve ntions (Higgins 2008). This will include assessment of:

• the method used for randomisation to generate the sequence of participants allocated to the treatment arms;

• allocation concealment;

• blinding (of participants, healthcare providers and outcome assessors);

• reporting of incomplete outcome data for each outcome;

• selective reporting of outcomes;

• other possible sources of bias.

Two review authors (MA, AB) will independently apply the risk of bias tool and we will resolve differences by discussion or by appeal to a third review author (PMH). We will present results in both a risk of bias graph and a risk of bias summary. We will interpret the results of meta‐analyses in the light of the findings with respect to risk of bias.

Measures of treatment effect

• We will compute RRs from the proportions or rates among trial participants showing effects in the treatment arms for the dichotomous variables. For vaccine efficacy (VE), we will also express treatment effects as VE = (1‐RR)*100, where a high level of protection will yield values approximating 100%.

• We will assess time to development of infections or lesions using HRs.

• We will assess the evolution of the serologic response to immunisation by MD or SMD in antibody level (preferentially expressed in IU) of type‐specific antibodies at different time points, as well as the ratio of the mean antibody level of type‐specific antibodies in women who have been vaccinated versus women in the control group who are seropositive because of a natural infection. We will make a distinction between overall antibody titres and virus‐neutralising antibody titres, if possible.

Dealing with missing data

We will contact study authors or data owners to request data on the outcomes that were not reported.

We will not impute missing outcome data.

If data are reported for grouped end points, we will contact trial authors or data owners to request data on the separated outcomes. We will use a grid of commonly defined and timed outcomes for this purpose. In addition, we will solicit results stratified by initial HPV status, age and sexual history if these have not been reported.

Assessment of heterogeneity

We will assess heterogeneity between studies by visual inspection of forest plots, by estimation of the percentage heterogeneity between trials which cannot be ascribed to sampling variation (Higgins 2003), by a formal statistical test of the significance of the heterogeneity (Deeks 2001) and, if possible, by subgroup analyses. If there is evidence of substantial heterogeneity, we will investigate and report the possible reasons.

We will avoid heterogeneity caused by combining data series from participants with different initial HPV status (presence of HPV DNA, anti‐HPV antibodies). We will investigate age group and sexual history as potential sources that could explain possible heterogeneity.

Assessment of reporting biases

We will examine funnel plots corresponding to meta‐analysis of the primary outcome to assess the relation between sample size and treatment effects. When there is evidence of small study effects, we will consider publication bias as only one of a number of possible explanations. If these plots suggest that treatment effects may not be sampled from a symmetric distribution, as assumed by the random‐effects model, we will perform sensitivity analyses using fixed‐effect models.

Data synthesis

If sufficient clinically similar studies are available, we will pool the results in meta‐analyses.

• For dichotomous outcomes, we will pool RRs, VEs or RDs.

• For time‐to‐event data, we will pool HRs.

• For continuous outcomes, we will pool the MD or SMD between treatment arms.  

We will apply random‐effects models with inverse variance weighting for all meta‐analyses of RRs, HRs and SMDs using the Review Manager (RevMan) 5 (DerSimonian 1986).

For cluster RCTs, if the analysis accounts for the cluster design then we will extract a direct estimate of the desired treatment effect e.g. RR plus 95% confidence interval (CI). If the analysis does not account for the cluster design, we will extract the number of clusters randomised to each intervention, the average cluster size in each intervention group and the outcome data, ignoring the cluster design, for all women in each group. Next, using an external estimate of the intracluster coefficient (ICC), we will estimate a design effect. Hence, the variance of the effect estimate will be inflated. It will then be possible to enter the data into RevMan (Cochrane Editorial software package) and combine the cluster randomised trials with individually randomised trials in the same meta‐analysis, using the generic inverse variance method of meta‐analysis.

Subgroup analysis and investigation of heterogeneity

We will base particularly important subgroup analyses on separation of participants being initially hrHPV DNA negative, HPV16/18 DNA negative, or HPV16/18 DNA positive. If possible, we will further subdivide these subgroup analyses by initial serological status (presence of antiHPV16/18 antibodies). When published data are not clearly separated by initial HPV status, we will request them from the owners of the databases. Age group and previous sexual experience are particularly important stratifying covariates, which we will request from data owners if insufficiently reported and which we will use for meta‐regression.

We will consider a particularly interesting subgroup analysis depending on available data, and we will base this on participants having received only two doses of vaccine. This subgroup analysis could be added to results from planned trials evaluating efficacy of reduced number of administrations (Eggertson 2007; Dorans 2010).

We will attempt to project reported study outcomes to the nearest multiple of 12 months to account for differences in the timing of reporting.

Type of vaccine and certain other study covariates (see Data extraction and management) may be considered as objects for sub‐group meta‐analysis or meta‐regression (Sharp 1998; Thompson 1999).

Sensitivity analysis

We will perform sensitivity analyses excluding studies at moderate or high risk of bias (see: Assessment of risk of bias in included studies).

Feedback

Riva et al, 16 December 2014

Summary

The protocol background includes the following text:

'Several phase II and III studies have been conducted to date and numerous reviews have tried to summarise the results (Arbyn 2007; Ault 2007; Harper 2009; Initiative 2009; Kahn 2009; Kjaer 2009; Koutsky 2006; Medeiros 2009; Rambout 2007; Szarewski 2010). However, none of the reviews combined information on all the available endpoints. This is due to incomplete reporting of data, use of different assays, analyses of different per protocol or intention‐to‐treat groups, outcome definitions, lumping of different outcomes, and reporting at variable time points in the scientific literature. Previous reports have also not comprehensively evaluated the impact of vaccination by fine categories of age and time since sexual debut, have not systematically evaluated evidence for cross‐protection against HPV types phylogenetically related to HPV‐16/18, and have not specifically addressed the question of whether vaccination protects against re‐infection among younger and older individuals known to be infected at vaccination and who subsequently clear their infections.

The objective of this review is to summarise all available (published and unpublished) evidence by combining outcomes with similar definitions and times of measurement. We will request missing outcomes or outcome data missing at specific time points.'

We agree to the points made above. However, we think the paragraph warrants the following clarifications:

1. This Cochrane review is important in order to examine the validity and trustworthiness of the design of the clinical trials with regard to the choice of outcomes as well as the rigour with which these trials were conducted. Consequently, the reviewers will need to address certain problems and limitations in the design and conduct of the studies:

• The documents we have obtained from the FDA indicate that there were changes in the protocol during the course of the trials and therefore during the approval process. These changes necessarily had a major impact on the quality of the reporting and redefinition of certain sub‐groups in at least three instances .

• The minutes from meetings of the Vaccines and Related Biological Products Advisory Committee (VRBPAC) show that the decision to fast track the research led the American regulatory officials to choose outcomes that would allow them to evaluate only the specific effectiveness of the vaccination on lesions associated with HPV 16 and 18 and not its effectiveness on all HPV‐associated lesions .

• The criteria required to satisfy a fast track procedure were not fulfilled but the fast tracking had an impact on the choice of outcomes .

• The entries regarding the trials on clinictrials.gov indicate that their primary and secondary outcomes were not registered prospectively.

We believe that this Cochrane review should raise these issues with FDA officials and scientific journals which have published results from the Phase III trials because they have broken their own rules of proper scientific conduct.

2. This Cochrane review is important for thoroughly evaluating a potentially increased risk of the subsequent development of precancerous lesions in women who already have HPV infections targeted by the vaccination at the time they are vaccinated. This risk has not been sufficiently examined although existing evidence indicates the need for a thorough and careful examination of the possibility. This evidence includes:

• Results submitted to VRBPAC in June, 2006

• The Australian study done by Brotherton et al .

3. This Cochrane review is important to calculate and report the risk of subsequent development of precancerous lesions in women who already have HPV infections targeted by the vaccination at the time they are vaccinated, and the ways in which it must be communicated to vaccinated women and to vaccinated girls and their legal guardians.

The stated objectives of the protocol are as follows:

'To evaluate the immunogenicity, clinical efficacy, and safety of prophylactic HPV vaccines in females. The assessment of clinical efficacy will address protection against HPV infection (for homologous and heterologous HPV types), against re‐infection, against cervical cancer and its precursors (high‐grade CIN (grade 2 or grade 3), adenocarcinoma in situ) in women previously not exposed to HPV infection (negative at enrolment for both HPV DNA and antibodies against the vaccine HPV types). We will assess clinical effectiveness by evaluating outcomes in all women, irrespective of the HPV DNA or serology status at enrolment. Evaluation by fine age and time since sexual debut categories is also planned.'

These objectives seem entirely pertinent. Nevertheless, it is essential that objectives specify explicitly that the effectiveness of vaccination will be evaluated with regard to all of the high‐grade lesions; i.e., CIN2/3+, no matter the HPV types associated with them, and that the focus will be on young girls who were negative only for HPV‐types targeted by the vaccines and not for 14 HPV types. This point is essential for methodological reasons, since analyzing the effectiveness of vaccination for young girls who were HPV‐negative for 14 HPV types was post hoc and not in the protocols before the trials began. The value of these two analyses is therefore not equal.

The authors have defined eligible study types as follows:

'We will only consider randomised controlled trials (RCTs).'

This point strikes us as essential. Moreover, it should be made clear that post hoc analyses of subgroups will be treated, if at all, separately.

Moreover, we believe that the Cochrane reviewers should clearly indicate how they will take into consideration unpublished results that the manufacturer possesses.

The authors have defined their primary outcomes as follows:

'1. Histologically confirmed high‐grade cervical intraepithelial neoplasia (CIN2, CIN3 and adenocarcinoma in situ (AIS).

2. Invasive cervical cancer.

3. Immunogenicty:

i) percentage of women vaccinated who have seroconverted after the third dose of vaccine;, ii) mean antibody level in International Units (IU) observed after completion of vaccine administration.

4. Safety:

i) immediate and short term adverse events (observed within four weeks after administration):

a) local adverse effects (redness, swelling, pain, itching at the injection place);b) mild systemic effects;c) severe systemic effects;ii) serious adverse events observed after four weeks of administration of the vaccine during the trial; iii) pregnancy outcomes observed during the trials, in particular occurrence of congenital anomalies.'

We believe that primary outcome 1 must state explicitly that histological confirmation will focus specifically on “CIN2, CIN3 and AIS irrespective of HPV type”.

We believe that primary outcome 4 (safety) must include:

• an analysis of the adequacy of the protocol planned for the studies on the safety and innocuousness of the vaccine as well as the effects of the placebo chosen to evaluate these aspects of the research

• a third point (iii) that encompasses an evaluation of the increase in the risk of CIN2/3 for women who were already infected by HPV types targeted by the vaccine

The stated secondary outcomes of the review are as follows:

'1. Incident infection with vaccine HPV types (HPV6, HPV11, HPV16 and HPV18, separately and jointly) and with hrHPV types other than HPV16/18.

2. Persistent infection with vaccine HPV types and hrHPV types other than HPV16/18.

3. Evolution over time of the geometric mean titres of antibodies against the vaccine HPV type.'

We believe that the secondary outcomes should include an HPV‐specific analysis of the lesions found in the vaccinated population to clarify the possibility of viral replacement. It is essential to know whether during the Phase III trials, the efficacy of the vaccines against high‐risk HPV 16 and 18 resulted in an increase in high‐grade lesions associated with other high‐risk HPV types.

The authors Declarations of interest state that:

'MA: has received travel grants fromMSD‐Sanofi‐Pasteur and GSK, (ceased in 2008). AB: no conflict of interest. PM‐H: travel grants received fromGSKandMSD‐Sanofi‐Pasteur. LX: no conflict of interest. CS received travel grant from GSK. LM; no conflict of interest .All of the research to date has been conducted by authors who have conflicts of interest with the vaccine manufacturer.'

In December 2012, we alerted the Cochrane Gynecological and Orphan Cancer Group that the authors originally chosen for this Cochrane review also had conflicts of interest with the manufacturer. Some of these authors were dropped in December 2013. Nevertheless, the question remains, since certain authors did not step aside and state here that they have no conflicts of interest. We believe that the stated conflicts of interest in the protocol are incomplete for Marc Arbyn and Lauri E. Markowitz. As we previously pointed out in December 2012, these two authors have already made favorable pronouncements regarding the vaccine, which constitutes a clear bias:

Marc Arbyn:

“HPV vaccination will reduce the burden of cervical precancer and probably also of invasive cervical and other HPV‐related disease in women.” http://www.ncbi.nlm.nih.gov/pubmed/22623137

Marc Arbyn (with Philippe Beutels):

“Well‐planned introduction of vaccination combined with an organized screening program and active surveillance are crucial for the program to achieve and monitor its desired aims. Such surveillance should include linkage between vaccination, screening and cancer registries.” http://www.ncbi.nlm.nih.gov/pubmed/21051840

Lauri E. Markowitz, Team Lead, Centers for Disease Control and Prevention (Atlanta, Georgia): “The CDC has approved these vaccines as safe and effective. Both vaccines were studied in thousands of people around the world, and these studies showed no serious safety concerns. Side effects reported in these studies were mild, including pain where the shot was given, fever, dizziness, and nausea. Vaccine safety continues to be monitored by CDC and the FDA. More than 46 million doses of HPV vaccine have been distributed in the United States as of June 2012.” http://www.cdc.gov/std/hpv/stdfact‐hpv‐vaccine‐young‐women.htm.

L E Markowitz also transmits his conclusions in the context of events like this (http://www.medscape.org/viewarticle/768633_sidebar2), sponsored by the manufacturer of the quadrivalent vaccine (“supported by an independent educational grant from Merck”).

We believe that it is imperative for this information to appear in the declaration of interest for Marc Arbyn and Lauri Markowitz. We also think that this protocol must explicitly state what measures will be taken in order to limit, as much as possible, the influence of these conflicting ties on the analysis of the results.

Reply

This reply has been added by Jo Morrison, Co‐ordinating Editor, Cochrane Gynaecological Cancer Group on behalf of the author team.

We thank Catherine Riva and colleagues for their helpful suggestions and comments, many of which we plan to address in the full review, since they have commented on the protocol only. In response to their earlier set of comments and on the advice of the Cochrane Funding Arbiter review authors with ties to clinical trials in this area were removed. Although this has reduced our ability to consider extensive unpublished data we have been able to contact investigators of included studies for additional information, where necessary, in accordance with Cochrane guidance. This is not an individual patient data review and to undertake one would be beyond the scope of the original review question and represent an investment of time and resources that we are not in a position to make.

None of the author team listed on the review has financial ties to the vaccine industry or has been involved with the studies that will be included in the review. The review author team complies with the Cochrane Policy conflicts of interest.

http://community.cochrane.org/editorial‐and‐publishing‐policy‐resource/conflicts‐interest‐and‐cochrane‐reviews .

Conflicts of interests have been reported, assessed and approved by the Funding Arbiter. That the authors have an interest and expertise in this area, so have already formed some opinions on the data does not count as conflict of interest and does not negate their involvement in performing a Cochrane review: equipoise is desirable, but an open mind and ability to systematically, and without bias, review the data is a given. If this were not the case then many Cochrane Reviews would be conducted by people without relevant clinical or topic expertise.

The review has been written and is going through a robust editorial and peer review process. We are content for readers of the review to judge it on its merits once it is in the public domain.

Contributors

Catherine Riva, Jean‐Pierre Spinosa, Abby Lippman, Geneviève Rail, Lyba Spring, Anne Taillefer, Fernand Turcotte, Neil Arya and Pierre Biron.

We agree with the conflict of interest statement below:

We certify that we have no affiliations with or involvement in any organization or entity with a financial interest in the subject matter of this feedback.

Appendices

Appendix 1. Characteristics of currently licensed prophylactic HPV vaccines

 

	Monovalent vaccine	Bivalent vaccine	Quadrivalent vaccine
Manufacturer	Merck, Sharp & Dome (Merck & Co, Whitehouse Station, NJ, USA)	GlaxoSmithKline (GSK, Rixensart, Belgium)	Merck, Sharp & Dome (Merck & Co, Whitehouse Station, NJ, USA)
Antigens	HPV16 (40 μg)	L1 VLPs of HPV16 (20 μg) and HPV18 (20 μg)	L1 VLPs of HPV6 (20 μg), HPV11 (40 μg), HPV16 (40 μg) and HPV18 (20 mg)
Vaccination schedule	3 doses: at day 1, month 2 and month 6	3 doses: at day 1, month 1 and month 6	3 doses: at day 1, month 2 and month 6
Adjuvant	225 μg amorphous aluminium hydroxyl‐phosphate sulphate	ASO4: 500 μg Aluminium hydroxide, 50 μg 3‐deacylated monophosphoryl lipid A (MPL)	225 μg amorphous aluminium hydroxyl‐phosphate sulphate
Trade name	Not commercialised	Cervarix	Gardasil, Silgard
Produced by recombinant technology using	Saccharomyces cerevisae (baker’s yeast)	Baculovirus in Trichoplusia in insect cells	Saccharomyces cerevisae (baker’s yeast)

 Adapted from WHO 2009.

Appendix 2. MEDLINE Search strategy

The following search strategy will by used to retrieve references in MEDLINE (Ovid): 1) exp Papillomavirus Infections/ 2) exp Papillomaviridae/ 3) HPV*.mp. 4) human papillomavirus*.mp. 5) human papilloma virus*.mp. 6) or/1‐5 7) exp Papillomavirus Vaccines/ 8) gardasil.mp. 9) cervarix.mp. 10) vaccin*.mp. 11) immuni*.mp. 12) or/7‐11 13) 6 and 12 14) randomized controlled trial.pt. 15) controlled clinical trial.pt. 16) randomized.ab. 17) placebo.ab. 18) drug therapy.fs. 19) randomly.ab. 20) trial.ab. 21) groups.ab. 22) or/14‐21 23) 13 and 22 24) (animals not (humans and animals)).sh. 25) 23 not 24 26) limit 25 to yr = "2002‐2011" key: mp = title, original title, abstract, name of substance word, subject heading word, unique identifier pt = publication type ab = abstract sh = subject heading

Appendix 3. List of abbreviations

AGC: atypical glandular cells AGUS: atypical glandular cells of undetermined significance AIS: adenocarcinoma in situ ASC: atypical squamous cells (comprises ASC‐US and ASC‐H) ASC‐H: atypical squamous cells, HSIL cannot be ruled out ASC‐R: atypical squamous cells favouring a benign reactive process squamous cells of undetermined significance ASC‐US: atypical squamous cells of undetermined significance ASCUS: atypical squamous cells of undetermined significance (comprises ASC‐R, ASC‐US and ASC‐H) CDC: Centre for Disease Control CGIN: cervical glandular intraepithelial neoplasia CHMP: Committee for Medicinal Products for Human Use CI: (95 %) confidence interval CIN: cervical Intra‐epithelial neoplasia CIS: carcinoma in situ CISA: Clinical Immunization Safety Assessment DNA: Desoxyribo‐nucleic acid EC: endocervical curettage ECDC: European Centre for Disease Control EMEA: European Medicines Agency EPAR: European Public Assessment Reports FDA: Food and Drugs Agency GSK: GlaxoSmithKline HC: hybrid capture HPV: human papillomavirus HR: hazard ratio hrHPV: high‐risk HPV type HSIL: high‐grade squamous intraepithelial lesion IARC: International Agency for Research on Cancer lrHPV: low‐risk HPV type LSIL: low‐grade squamous intraepithelial lesion MCO: managed care organizations MSD: Merck‐Sharp & Dome NCBI: National Center for Biotechnology Information ITT: intention‐to‐treat PCR: polymerase chain reaction PP: per‐protocol RCT: randomised controlled trial RD: risk difference RR: risk ratio TBS: The Bethesda System UK: United Kingdom USA: United States of America VAERS: Vaccine Adverse Event Reporting System VE: vaccine efficacy VLP: virus‐like particles VSD: Vaccine Safety Datalink WHO: World Health Organization

What's new

Last assessed as up‐to‐date: 3 March 2011.

Date	Event	Description
26 September 2017	Amended	Feedback edited to provide greater clarity regarding text from the protocol and comments as submitted.

History

Protocol first published: Issue 4, 2011

Date	Event	Description
9 February 2015	Feedback has been incorporated	Feedback comments incorporated
23 December 2013	Amended	Minor amendments to text.
23 December 2013	New citation required and minor changes	Minor amendment to references.
12 December 2013	Amended	Updated reference.
12 December 2013	New citation required and minor changes	Updated author list.

Contributions of authors

Conception of the systematic review: M. Arbyn, L Markowitz, P. Martin‐Hirsch Study design: M. Arbyn Retrieval of references: M. Arbyn, P. Martin‐Hirsch. Checking eligibility of references: M. Arbyn, A Bryant, P. Martin‐Hirsch. Extraction of data: M. Arbyn, A. Bryant, C. Simoens, L. Xu Statistical analysis: M. Arbyn, A. Bryant, C. Simoens Writing of the protocol: M. Arbyn, A. Bryant, C. Simoens

Sources of support

Internal sources

• Scientific Institute of Public Health (Brussels), Belgium.

  Bibliographic support to obtain literature references, secretarial and logistic support in organising contacts and meetings with co‐authors and to store and sort bibliographic references. references

External sources

• Department of Health, UK.

  NHS Cochrane Collaboration programme Grant Scheme CPG‐506.

• Gynaecological Cancer Cochrane Collaboration Review Group (Bath), UK.

  Financial support to conduct four Cochrane reviews.

• European Cancer Network and the European Co‐operation on development and implementation of Cancer screening and prevention Guidelines (ECCG), via the International Agency for Research on Cancer, Lyon), France. Financial support received from the European Commission (DG SANCO, Luxembourg) for the production of guidelines for cervical cancer screening and HPV vaccination., France.

  Financial support received from the European Commission (DG SANCO, Luxembourg) for the production of guidelines for cervical cancer screening and HPV vaccination.

• Belgian Foundation Against Cancer (Brussels), Belgium.

  Financial support to conduct methodological research on evaluation of emerging screening methods and to continue systematic reviews on cervical cancer prevention methods.

• IWT (Institute for the Promotion of Innovation by Science and Technology in Flanders, Brussels, project number 060081), Belgium.

  Financial support to collect data for mathematical modelling of HPV infection (natural history, cost‐effectiveness of HPV screening and vaccination).

Declarations of interest

MA: has received travel grants from MSD‐Sanofi‐Pasteur and GSK, (ceased in 2008). AB: no conflict of interest. PM‐H: travel grants received from GSK and MSD‐Sanofi‐Pasteur. LX: no conflict of interest. CS received travel grant from GSK. LM; no conflict of interest.

Edited (no change to conclusions)